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Sample records for barrier coating deposited

  1. Combustion chemical vapor deposited coatings for thermal barrier coating systems

    Energy Technology Data Exchange (ETDEWEB)

    Hampikian, J.M.; Carter, W.B. [Georgia Institute of Technology, Atlanta, GA (United States). School of Materials Science and Engineering

    1995-12-31

    The new deposition process, combustion chemical vapor deposition, shows a great deal of promise in the area of thermal barrier coating systems. This technique produces dense, adherent coatings, and does not require a reaction chamber. Coatings can therefore be applied in the open atmosphere. The process is potentially suitable for producing high quality CVD coatings for use as interlayers between the bond coat and thermal barrier coating, and/or as overlayers, on top of thermal barrier coatings. In this report, the evaluation of alumina and ceria coatings on a nickel-chromium alloy is described.

  2. Thermal Barrier Coatings Resistant to Glassy Deposits

    Science.gov (United States)

    Drexler, Julie Marie

    Engineering of alloys has for years allowed aircraft turbine engines to become more efficient and operate at higher temperatures. As advancements in these alloy systems have become more difficult, ceramic thermal barrier coatings (TBCs), often yttria (7 wt %) stabilized zirconia (7YSZ), have been utilized for thermal protection. TBCs have allowed for higher engine operating temperatures and better fuel efficiency but have also created new engineering problems. Specifically, silica based particles such as sand and volcanic ash that enter the engine during operation form glassy deposits on the TBCs. These deposits can cause the current industrial 7YSZ thermal barrier coatings to fail since the glass formed penetrates and chemically interacts with the TBC. When this occurs, coating failure may occur due to a loss of strain tolerance, which can lead to fracture, and phase changes of the TBC material. There have been several approaches used to stop calcium-magnesium aluminio-silcate (CMAS) glasses (molten sand) from destroying the entire TBC, but overall there is still limited knowledge. In this thesis, 7YSZ and new TBC materials will be examined for thermochemical and thermomechanical performance in the presence of molten CMAS and volcanic ash. Two air plasma sprayed TBCs will be shown to be resistant to volcanic ash and CMAS. The first type of coating is a modified 7YSZ coating with 20 mol% Al2O3 and 5 mol% TiO2 in solid solution (YSZ+20Al+5Ti). The second TBC is made of gadolinium zirconate. These novel TBCs impede CMAS and ash penetration by interacting with the molten CMAS or ash and drastically changing the chemistry. The chemically modified CMAS or ash will crystallize into an apatite or anorthite phase, blocking the CMAS or ash from further destroying the coating. A presented mechanism study will show these coatings are effective due to the large amount of solute (Gd, Al) in the zirconia structure, which is the key to creating the crystalline apatite or

  3. Roll-to-roll vacuum deposition of barrier coatings

    CERN Document Server

    Bishop, Charles A

    2015-01-01

    It is intended that the book will be a practical guide to provide any reader with the basic information to help them understand what is necessary in order to produce a good barrier coated web or to improve the quality of any existing barrier product. After providing an introduction, where the terminology is outlined and some of the science is given (keeping the mathematics to a minimum), including barrier testing methods, the vacuum deposition process will be described. In theory a thin layer of metal or glass-like material should be enough to convert any polymer film into a perfect barrier material. The reality is that all barrier coatings have their performance limited by the defects in the coating. This book looks at the whole process from the source materials through to the post deposition handling of the coated material. This holistic view of the vacuum coating process provides a description of the common sources of defects and includes the possible methods of limiting the defects. This enables readers...

  4. Oxygen Barrier Coating Deposited by Novel Plasma-enhanced Chemical Vapor Deposition

    DEFF Research Database (Denmark)

    Jiang, Juan; Benter, M.; Taboryski, Rafael Jozef

    2010-01-01

    We report the use of a novel plasma-enhanced chemical vapor deposition chamber with coaxial electrode geometry for the SiOx deposition. This novel plasma setup exploits the diffusion of electrons through the inner most electrode to the interior samples space as the major energy source. This confi......We report the use of a novel plasma-enhanced chemical vapor deposition chamber with coaxial electrode geometry for the SiOx deposition. This novel plasma setup exploits the diffusion of electrons through the inner most electrode to the interior samples space as the major energy source....... This configuration enables a gentle treatment of sensitive materials like low-density polyethylene foils and biodegradable materials. SiOx coatings deposited in the novel setup were compared with other state of the art plasma coatings and were found to possess equally good or better barrier properties. The barrier...... effect of single-layer coatings deposited under different reaction conditions was studied. The coating thickness and the carbon content in the coatings were found to be the critical parameters for the barrier property. The novel barrier coating was applied on different polymeric materials...

  5. In-situ formation of multiphase deposited thermal barrier coatings

    Science.gov (United States)

    Subramanian, Ramesh

    2004-01-13

    A multiphase ceramic thermal barrier coating is provided. The coating is adapted for use in high temperature applications in excess of about 1200.degree. C., for coating superalloy components of a combustion turbine engine. The coating comprises a ceramic single or two oxide base layer disposed on the substrate surface; and a ceramic oxide reaction product material disposed on the base layer, the reaction product comprising the reaction product of the base layer with a ceramic single or two oxide overlay layer.

  6. Degradation of Thermal Barrier Coatings from Deposits and Its Mitigation

    Energy Technology Data Exchange (ETDEWEB)

    Nitin Padture

    2011-12-31

    Ceramic thermal barrier coatings (TBCs) used in gas-turbine engines afford higher operating temperatures, resulting in enhanced efficiencies and performance. However, in the case of syngas-fired engines, fly ash particulate impurities that may be present in syngas can melt on the hotter TBC surfaces and form glassy deposits. These deposits can penetrate the TBCs leading to their failure. In experiments using lignite fly ash to simulate these conditions we show that conventional TBCs of composition 93wt% ZrO{sub 2} + 7wt% Y{sub 2}O{sub 3} (7YSZ) fabricated using the air plasma spray (APS) process are completely destroyed by the molten fly ash. The molten fly ash is found to penetrate the full thickness of the TBC. The mechanisms by which this occurs appear to be similar to those observed in degradation of 7YSZ TBCs by molten calcium-magnesium-aluminosilicate (CMAS) sand and by molten volcanic ash in aircraft engines. In contrast, APS TBCs of Gd{sub 2Zr{sub 2}O{sub 7} composition are highly resistant to attack by molten lignite fly ash under identical conditions, where the molten ash penetrates ~25% of TBC thickness. This damage mitigation appears to be due to the formation of an impervious, stable crystalline layer at the fly ash/Gd{sub 2}Zr{sub 2}O{sub 7} TBC interface arresting the penetrating moltenfly- ash front. Additionally, these TBCs were tested using a rig with thermal gradient and simultaneous accumulation of ash. Modeling using an established mechanics model has been performed to illustrate the modes of delamination, as well as further opportunities to optimize coating microstructure. Transfer of the technology was developed in this program to all interested parties.

  7. Deposition stress effects on thermal barrier coating burner rig life

    Science.gov (United States)

    Watson, J. W.; Levine, S. R.

    1984-01-01

    A study of the effect of plasma spray processing parameters on the life of a two layer thermal barrier coating was conducted. The ceramic layer was plasma sprayed at plasma arc currents of 900 and 600 amps onto uncooled tubes, cooled tubes, and solid bars of Waspalloy in a lathe with 1 or 8 passes of the plasma gun. These processing changes affected the residual stress state of the coating. When the specimens were tested in a Mach 0.3 cyclic burner rig at 1130 deg C, a wide range of coating lives resulted. Processing factors which reduced the residual stress state in the coating, such as reduced plasma temperature and increased heat dissipation, significantly increased coating life.

  8. High Temperature Multilayer Environmental Barrier Coatings Deposited Via Plasma Spray-Physical Vapor Deposition

    Science.gov (United States)

    Harder, Bryan James; Zhu, Dongming; Schmitt, Michael P.; Wolfe, Douglas E.

    2014-01-01

    Si-based ceramic matrix composites (CMCs) require environmental barrier coatings (EBCs) in combustion environments to avoid rapid material loss. Candidate EBC materials have use temperatures only marginally above current technology, but the addition of a columnar oxide topcoat can substantially increase the durability. Plasma Spray-Physical Vapor Deposition (PS-PVD) allows application of these multilayer EBCs in a single process. The PS-PVD technique is a unique method that combines conventional thermal spray and vapor phase methods, allowing for tailoring of thin, dense layers or columnar microstructures by varying deposition conditions. Multilayer coatings were deposited on CMC specimens and assessed for durability under high heat flux and load. Coated samples with surface temperatures ranging from 2400-2700F and 10 ksi loads using the high heat flux laser rigs at NASA Glenn. Coating morphology was characterized in the as-sprayed condition and after thermomechanical loading using electron microscopy and the phase structure was tracked using X-ray diffraction.

  9. Metal organic chemical vapor deposition of environmental barrier coatings for the inhibition of solid deposit formation from heated jet fuel

    Science.gov (United States)

    Mohan, Arun Ram

    Solid deposit formation from jet fuel compromises the fuel handling system of an aviation turbine engine and increases the maintenance downtime of an aircraft. The deposit formation process depends upon the composition of the fuel, the nature of metal surfaces that come in contact with the heated fuel and the operating conditions of the engine. The objective of the study is to investigate the effect of substrate surfaces on the amount and nature of solid deposits in the intermediate regime where both autoxidation and pyrolysis play an important role in deposit formation. A particular focus has been directed to examining the effectiveness of barrier coatings produced by metal organic chemical vapor deposition (MOCVD) on metal surfaces for inhibiting the solid deposit formation from jet fuel degradation. In the first part of the experimental study, a commercial Jet-A sample was stressed in a flow reactor on seven different metal surfaces: AISI316, AISI 321, AISI 304, AISI 347, Inconel 600, Inconel 718, Inconel 750X and FecrAlloy. Examination of deposits by thermal and microscopic analysis shows that the solid deposit formation is influenced by the interaction of organosulfur compounds and autoxidation products with the metal surfaces. The nature of metal sulfides was predicted by Fe-Ni-S ternary phase diagram. Thermal stressing on uncoated surfaces produced coke deposits with varying degree of structural order. They are hydrogen-rich and structurally disordered deposits, spherulitic deposits, small carbon particles with relatively ordered structures and large platelets of ordered carbon structures formed by metal catalysis. In the second part of the study, environmental barrier coatings were deposited on tube surfaces to inhibit solid deposit formation from the heated fuel. A new CVD system was configured by the proper choice of components for mass flow, pressure and temperature control in the reactor. A bubbler was designed to deliver the precursor into the reactor

  10. The Barrier Properties of PET Coated DLC Film Deposited by Microwave Surface-Wave PECVD

    Science.gov (United States)

    Yin, Lianhua; Chen, Qiang

    2017-12-01

    In this paper we report the investigation of diamond-like carbon (DLC) deposited by microwave surface-wave plasma enhanced chemical vapor deposition (PECVD) on the polyethylene terephthalate (PET) web for the purpose of the barrier property improvement. In order to characterize the properties of DLC coatings, we used several substrates, silicon wafer, glass, and PET web and KBr tablet. The deposition rate was obtained by surface profiler based on the DLC deposited on glass substrates; Fourier transform infrared spectroscope (FTIR) was carried out on KBr tablets to investigate chemical composition and bonding structure; the morphology of the DLC coating was analyzed by atomic force microscope (AFM) on Si substrates. For the barrier properties of PET webs, we measured the oxygen transmission rate (OTR) and water vapor transmission rate (WVTR) after coated with DLC films. We addressed the film barrier property related to process parameters, such as microwave power and pulse parameter in this work. The results show that the DLC coatings can greatly improve the barrier properties of PET webs.

  11. Development of Diffusion barrier coatings and Deposition Technologies for Mitigating Fuel Cladding Chemical Interactions (FCCI)

    Energy Technology Data Exchange (ETDEWEB)

    Sridharan, Kumar; Allen, Todd; Cole, James

    2013-02-27

    The goal of this project is to develop diffusion barrier coatings on the inner cladding surface to mitigate fuel-cladding chemical interaction (FCCI). FCCI occurs due to thermal and radiation enhanced inter-diffusion between the cladding and fuel materials, and can have the detrimental effects of reducing the effective cladding wall thickness and lowering the melting points of the fuel and cladding. The research is aimed at the Advanced Burner Reactor (ABR), a sodium-cooled fast reactor, in which higher burn-ups will exacerbate the FCCI problem. This project will study both diffusion barrier coating materials and deposition technologies. Researchers will investigate pure vanadium, zirconium, and titanium metals, along with their respective oxides, on substrates of HT-9, T91, and oxide dispersion-strengthened (ODS) steels; these materials are leading candidates for ABR fuel cladding. To test the efficacy of the coating materials, the research team will perform high-temperature diffusion couple studies using both a prototypic metallic uranium fuel and a surrogate the rare-earth element lanthanum. Ion irradiation experiments will test the stability of the coating and the coating-cladding interface. A critical technological challenge is the ability to deposit uniform coatings on the inner surface of cladding. The team will develop a promising non-line-of-sight approach that uses nanofluids . Recent research has shown the feasibility of this simple yet novel approach to deposit coatings on test flats and inside small sections of claddings. Two approaches will be investigated: 1) modified electrophoretic deposition (MEPD) and 2) boiling nanofluids. The coatings will be evaluated in the as-deposited condition and after sintering.

  12. Thermal barrier coatings on gas turbine blades: Chemical vapor deposition (Review)

    Science.gov (United States)

    Igumenov, I. K.; Aksenov, A. N.

    2017-12-01

    Schemes are presented for experimental setups (reactors) developed at leading scientific centers connected with the development of technologies for the deposition of coatings using the CVD method: at the Technical University of Braunschweig (Germany), the French Aerospace Research Center, the Materials Research Institute (Tohoku University, Japan) and the National Laboratory Oak Ridge (USA). Conditions and modes for obtaining the coatings with high operational parameters are considered. It is established that the formed thermal barrier coatings do not fundamentally differ in their properties (columnar microstructure, thermocyclic resistance, thermal conductivity coefficient) from standard electron-beam condensates, but the highest growth rates and the perfection of the crystal structure are achieved in the case of plasma-chemical processes and in reactors with additional laser or induction heating of a workpiece. It is shown that CVD reactors can serve as a basis for the development of rational and more advanced technologies for coating gas turbine blades that are not inferior to standard electron-beam plants in terms of the quality of produced coatings and have a much simpler and cheaper structure. The possibility of developing a new technology based on CVD processes for the formation of thermal barrier coatings with high operational parameters is discussed, including a set of requirements for industrial reactors, high-performance sources of vapor precursors, and promising new materials.

  13. Aluminum oxide barrier coating on polyethersulfone substrate by atomic layer deposition for barrier property enhancement

    International Nuclear Information System (INIS)

    Kim, Hyun Gi; Kim, Sung Soo

    2011-01-01

    Aluminum oxide layers were deposited on flexible polyethersulfone (PES) substrates via plasma enhanced atomic layer deposition (PEALD) process using trimethylaluminum (TMA) and oxygen as precursor and reactant materials. Several process parameters in PEALD process were investigated in terms of refractive index and layer thickness. Number of process cycle increased the thickness and refractive index of the layer to enhance the barrier properties. Non-physisorbed TMA and unreacted oxygen were purged before and after the plasma reaction, respectively. Identical purge time was applied to TMA and oxygen and it was optimized for 10 s. Thinner and denser layer was formed as substrate temperature increased. However, the PES substrate could be deformed above 120 o C. Aluminum oxide layer formed on PES at optimized conditions have 11.8 nm of thickness and reduced water vapor transmission rate and oxygen transmission rate to below 4 x 10 -3 g/m 2 day and 4 x 10 -3 cm 3 /m 2 day, respectively. Polycarbonate and polyethylene naphthalate films were also tested at optimized conditions, and they also showed quite appreciable barrier properties to be used as plastic substrates.

  14. Mechanistic Study on the Degradation of Thermal Barrier Coatings Induced by Volcanic Ash Deposition

    Science.gov (United States)

    Arai, Masayuki

    2017-08-01

    Thermal stress generated on thermal barrier coatings (TBCs) by volcanic ash (VA) deposition was assessed measuring the tip deflection of a multilayered beam structure as a function of temperature. The TBC in this study was deposited onto the surface of a blade utilized in a land-based gas turbine which is composed of 8 wt.%Y2O3-ZrO2/CoNiCrAlY on a Ni-based superalloy. The VA-deposited TBC sample was heated at 1453 K, and the effect of VA deposition on TBC delamination was examined in comparison with a TBC sample without VA deposition as a reference. On the basis of the VA attack damage mechanism which was investigated via the tip deflection measurement and a comprehensive microstructure examination, a damage-coupled constitutive model was proposed. The proposed model was based on the infiltration of the molten VA inside pores and phase transformations of yttria -tabilized zirconia in the TBC system. The numerical analysis results, which were simulated utilizing the finite element code installing the developed constitutive model, showed us that VA attack on the TBC sample induced near-interfacial cracks because of a significant increasing in the coating stress.

  15. Failure mechanisms of platinum aluminide bond coat/electron beam-physical vapor deposited thermal barrier coatings

    Science.gov (United States)

    Vaidyanathan, Krishnakumar

    Thermal barrier coatings (TBCs) allow operation of structural components, such as turbine blades and vanes in industrial and aircraft gas engines, at temperatures close to the substrate melting temperatures. They consist of four different layers; a high strength creep-resistant nickel-based superalloy substrate, an oxidation resistant bond coat (BC), a low thermal conductivity ceramic topcoat and a thermally grown oxide (TGO), that is predominantly alpha-Al 2O3, that forms between the BC and the TBC. Compressive stresses (3--5 GPa) that are generated in the thin TGO (0.25--8 mum) due to the mismatch in thermal coefficient of expansion between the TGO and BC play a critical role in the failure of these coatings. In this study, the failure mechanisms of a commercial yttria-stabilized zirconia (7YSZ) electron beam-physical vapor deposited (EB-PVD) coating on platinum aluminide (beta-(Ni,Pt)Al) bond coat have been identified. Two distinct mechanisms have been found responsible for the observed damage initiation and progression at the TGO/bond coat interface. The first mechanism leads to localized debonding at TGO/bond coat interface due to increased out-of-plane tensile stress, along bond coat features that manifest themselves as ridges. The second mechanism causes cavity formation at the TGO/bond coat interface, driven by cyclic plasticity of the bond coat. It has been found that the debonding at the TGO/bond coat interface due to the first mechanism is solely life determining. The final failure occurs by crack extension along either the TGO/bond coat interface or the TGO/YSZ interface or a combination of both, leading to large scale buckling. Based on these mechanisms, it is demonstrated that the bond coat grain size and the aspect ratio of the ridges have a profound influence on spallation lives of the coating. The removal of these ridges by fine polishing prior to TBC deposition led to a four-fold improvement in life. The failure mechanism identified for the

  16. Novel Prospects for Plasma Spray-Physical Vapor Deposition of Columnar Thermal Barrier Coatings

    Science.gov (United States)

    Anwaar, Aleem; Wei, Lianglinag; Guo, Qian; Zhang, Baopeng; Guo, Hongbo

    2017-12-01

    Plasma spray-physical vapor deposition (PS-PVD) is an emerging coating technique that can produce columnar thermal barrier coatings from vapor phase. Feedstock treatment at the start of its trajectory in the plasma torch nozzle is important for such vapor-phase deposition. This study describes the effects of the plasma composition (Ar/He) on the plasma characteristics, plasma-particle interaction, and particle dynamics at different points spatially distributed inside the plasma torch nozzle. The results of calculations show that increasing the fraction of argon in the plasma gas mixture enhances the momentum and heat flow between the plasma and injected feedstock. For the plasma gas combination of 45Ar/45He, the total enthalpy transferred to a representative powder particle inside the plasma torch nozzle is highest ( 9828 kJ/kg). Moreover, due to the properties of the plasma, the contribution of the cylindrical throat, i.e., from the feed injection point (FIP) to the start of divergence (SOD), to the total transferred energy is 69%. The carrier gas flow for different plasma gas mixtures was also investigated by optical emission spectroscopy (OES) measurements of zirconium emissions. Yttria-stabilized zirconia (YSZ) coating microstructures were produced when using selected plasma gas compositions and corresponding carrier gas flows; structural morphologies were found to be in good agreement with OES and theoretical predictions. Quasicolumnar microstructure was obtained with porosity of 15% when applying the plasma composition of 45Ar/45He.

  17. Processing and Deposition of Nanocrystalline Oxide Composites for Thermal Barrier Coatings

    National Research Council Canada - National Science Library

    Ying, Jackie

    2000-01-01

    .... Electrophoretic deposition was used to coat the nanocomposite powders onto nickel substrates. The effect of alumina content, powder calcination temperature, and film thickness on the thermal stability of zirconia-based coatings was examined...

  18. Metallographic techniques for evaluation of Thermal Barrier Coatings produced by Electron Beam Physical Vapor Deposition

    International Nuclear Information System (INIS)

    Kelly, Matthew; Singh, Jogender; Todd, Judith; Copley, Steven; Wolfe, Douglas

    2008-01-01

    Thermal Barrier Coatings (TBC) produced by Electron Beam Physical Vapor Deposition (EB-PVD) are primarily applied to critical hot section turbine components. EB-PVD TBC for turbine applications exhibit a complicated structure of porous ceramic columns separated by voids that offers mechanical compliance. Currently there are no standard evaluation methods for evaluating EB-PVD TBC structure quantitatively. This paper proposes a metallographic method for preparing samples and evaluating techniques to quantitatively measure structure. TBC samples were produced and evaluated with the proposed metallographic technique and digital image analysis for columnar grain size and relative intercolumnar porosity. Incorporation of the proposed evaluation technique will increase knowledge of the relation between processing parameters and material properties by incorporating a structural link. Application of this evaluation method will directly benefit areas of quality control, microstructural model development, and reduced development time for process scaling

  19. In-situ formation of multiphase electron beam physical vapor deposited barrier coatings for turbine components

    Science.gov (United States)

    Subramanian, Ramesh

    2001-01-01

    A turbine component (10), such as a turbine blade, is provided which is made of a metal alloy (22) and a base columnar thermal barrier coating (20) on the alloy surface, where a heat resistant ceramic oxide sheath material (32' or 34') covers the columns (28), and the sheath material is the reaction product of a precursor ceramic oxide sheath material and the base thermal barrier coating material.

  20. Yb2Si2O7 Environmental Barrier Coatings Deposited by Various Thermal Spray Techniques: A Preliminary Comparative Study

    Science.gov (United States)

    Bakan, Emine; Marcano, Diana; Zhou, Dapeng; Sohn, Yoo Jung; Mauer, Georg; Vaßen, Robert

    2017-08-01

    Dense, crack-free, uniform, and well-adhered environmental barrier coatings (EBCs) are required to enhance the environmental durability of silicon (Si)-based ceramic matrix composites in high pressure, high gas velocity combustion atmospheres. This paper represents an assessment of different thermal spray techniques for the deposition of Yb2Si2O7 EBCs. The Yb2Si2O7 coatings were deposited by means of atmospheric plasma spraying (APS), high-velocity oxygen fuel spraying (HVOF), suspension plasma spraying (SPS), and very low-pressure plasma spraying (VLPPS) techniques. The initial feedstock, as well as the deposited coatings, were characterized and compared in terms of their phase composition. The as-sprayed amorphous content, microstructure, and porosity of the coatings were further analyzed. Based on this preliminary investigation, the HVOF process stood out from the other techniques as it enabled the production of vertical crack-free coatings with higher crystallinity in comparison with the APS and SPS techniques in atmospheric conditions. Nevertheless, VLPPS was found to be the preferred process for the deposition of Yb2Si2O7 coatings with desired characteristics in a controlled-atmosphere chamber.

  1. Biomimetic thermal barrier coating in jet engine to resist volcanic ash deposition

    Science.gov (United States)

    Song, Wenjia; Major, Zsuzsanna; Schulz, Uwe; Muth, Tobias; Lavallée, Yan; Hess, Kai-Uwe; Dingwell, Donald B.

    2017-04-01

    The threat of volcanic ash to aviation safety is attracting extensive attention when several commercial jet aircraft were damaged after flying through volcanic ash clouds from the May 1980 eruptions of Mount St. Helen in Washington, U.S. and especially after the air traffic disruption in 2010 Eyjafjallajökull eruption. A major hazard presented by volcanic ash to aircraft is linked to the wetting and spreading of molten ash droplets on engine component surfaces. Due to the fact ash has a lower melting point, around 1100 °C, than the gas temperature in the hot section (between 1400 to 2000 °C), this cause the ash to melt and potentially stick to the internal components (e.g., combustor and turbine blades), this cause the ash to melt and potentially stick to the internal components of the engine creating, substantial damage or even engine failure after ingestion. Here, inspiring form the natural surface of lotus leaf (exhibiting extreme water repellency, known as 'lotus effect'), we firstly create the multifunctional surface thermal barrier coatings (TBCs) by producing a hierarchical structure with femtosecond laser pulses. In detail, we investigate the effect of one of primary femtosecond laser irradiation process parameter (scanning speed) on the hydrophobicity of water droplets onto the two kinds of TBCs fabricated by electron-beam physical vapor deposition (EB-PVD) and air plasma spray (APS), respectively as well as their corresponding to morphology. It is found that, comparison with the original surface (without femtosecond laser ablation), all of the irradiated samples demonstrate more significant hydrophobic properties due to nanostructuring. On the basis of these preliminary room-temperature results, the wettability of volcanic ash droplets will be analysed at the high temperature to constrain the potential impact of volcanic ash on the jet engines.

  2. Effects of argon and oxygen flow rate on water vapor barrier properties of silicon oxide coatings deposited on polyethylene terephthalate by plasma enhanced chemical vapor deposition

    International Nuclear Information System (INIS)

    Kim, Sung-Ryong; Choudhury, Moinul Haque; Kim, Won-Ho; Kim, Gon-Ho

    2010-01-01

    Plasma polymer coatings were deposited from hexamethyldisiloxane on polyethylene terephthalate (PET) substrates while varying the operating conditions, such as the Ar and O 2 flow rates, at a fixed radio frequency power of 300 W. The water vapor transmission rate (WVTR) of the untreated PET was 54.56 g/m 2 /day and was decreased after depositing the silicon oxide (SiO x ) coatings. The minimum WVTR, 0.47 g/m 2 /day, was observed at Ar and O 2 flow rates of 4 and 20 sccm, respectively, with a coating thickness of 415.44 nm. The intensity of the peaks for the Si-O-Si bending at 800-820 cm -1 and Si-O-Si stretching at 1000-1150 cm -1 varied depending on the Ar and O 2 flow rates. The contact angle of the SiO x coated PET increased as the Ar flow rate was increased from 2 to 8 sccm at a fixed O 2 flow rate of 20 sccm. It decreased gradually as the oxygen flow rate increased from 12 to 28 sccm at a fixed Ar carrier gas flow rate. The examination by atomic force microscopy revealed a correlation of the SiO x morphology and the water vapor barrier performance with the Ar and O 2 flow rates. The roughness of the deposited coatings increased when either the O 2 or Ar flow rate was increased.

  3. Catalytic thermal barrier coatings

    Science.gov (United States)

    Kulkarni, Anand A.; Campbell, Christian X.; Subramanian, Ramesh

    2009-06-02

    A catalyst element (30) for high temperature applications such as a gas turbine engine. The catalyst element includes a metal substrate such as a tube (32) having a layer of ceramic thermal barrier coating material (34) disposed on the substrate for thermally insulating the metal substrate from a high temperature fuel/air mixture. The ceramic thermal barrier coating material is formed of a crystal structure populated with base elements but with selected sites of the crystal structure being populated by substitute ions selected to allow the ceramic thermal barrier coating material to catalytically react the fuel-air mixture at a higher rate than would the base compound without the ionic substitutions. Precious metal crystallites may be disposed within the crystal structure to allow the ceramic thermal barrier coating material to catalytically react the fuel-air mixture at a lower light-off temperature than would the ceramic thermal barrier coating material without the precious metal crystallites.

  4. Atomic layer deposition of Al2O3 and Al2O3/TiO2 barrier coatings to reduce the water vapour permeability of polyetheretherketone

    International Nuclear Information System (INIS)

    Ahmadzada, Tamkin; McKenzie, David R.; James, Natalie L.; Yin, Yongbai; Li, Qing

    2015-01-01

    We demonstrate significantly enhanced barrier properties of polyetheretherketone (PEEK) against water vapour penetration by depositing Al 2 O 3 or Al 2 O 3 /TiO 2 nanofilms grown by atomic layer deposition (ALD). Nanoindentation analysis revealed good adhesion strength of a bilayer Al 2 O 3 /TiO 2 coating to PEEK, while the single layer Al 2 O 3 coating displayed flaking and delamination. We identified three critical design parameters for achieving the optimum barrier properties of ALD Al 2 O 3 /TiO 2 coatings on PEEK. These are a minimum total thickness dependent on the required water vapour transmission rate, the use of an Al 2 O 3 /TiO 2 bilayer coating and the application of the coating to both sides of the PEEK film. Using these design parameters, we achieved a reduction in moisture permeability of PEEK of over two orders of magnitude while maintaining good adhesion strength of the polymer–thin film system. - Highlights: • Atomic layer deposition of Al 2 O 3 /TiO 2 coatings reduced water vapour permeability. • Bilayer coatings reduced the permeability more than single layer coatings. • Bilayer coatings displayed higher adhesion strength than the single layer coatings. • Double-sided coatings performed better than single-sided coatings. • Correlation was found between total thickness and reduced water vapour permeability.

  5. Effect of corona pre-treatment on the performance of gas barrier layers applied by atomic layer deposition onto polymer-coated paperboard

    International Nuclear Information System (INIS)

    Hirvikorpi, Terhi; Vaehae-Nissi, Mika; Harlin, Ali; Marles, Jaana; Miikkulainen, Ville; Karppinen, Maarit

    2010-01-01

    The effect of corona pre-treatment on the performance of Al 2 O 3 and SiO 2 gas barrier layers applied by atomic layer deposition onto polymer-coated paperboards was studied. Both polyethylene and polylactide coated paperboards were corona treated prior to ALD. Corona treatment increased surface energies of the paperboard substrates, and this effect was still observed after several days. Al 2 O 3 and SiO 2 films were grown on top of the polymer coatings at temperature of 100 deg. C using the atomic layer deposition (ALD) technique. For SiO 2 depositions a new precursor, bis(diethylamido) silane, was used. The positive effect of the corona pre-treatment on the barrier properties of the polymer-coated paperboards with the ALD-grown layers was more significant with polyethylene coated paperboard and with thin deposited layers (shorter ALD process). SiO 2 performed similarly to Al 2 O 3 with the PE coated board when it comes to the oxygen barrier, while the performance of SiO 2 with the biopolymer-coated board was more moderate. The effect of corona pre-treatment was negligible or even negative with the biopolymer-coated board. The ALD film growth and the effect of corona treatment on different substrates require further investigation.

  6. High speed PVD thermal barrier coatings

    International Nuclear Information System (INIS)

    Beele, W.; Eschendorff, G.

    2006-01-01

    The high speed PVD process (HS-PVD) combines gas phase coating synthesis with high deposition rates. The process has been demonstrated for high purity YSZ deposited as a chemically bonded top thermal barrier with columnar structure of EB-PVD features. The process can manufacture EB-PVD like coatings that match in regards to their TGO-formation and columnar structure. Coatings with a columnar structure formed by individual columns of 1/4 of the diameter of a classical EB-PVD type TBC have been deposited. These coatings have the potential to prove a significant reduction in thermal conductivity and in erosion performance. (Abstract Copyright [2006], Wiley Periodicals, Inc.)

  7. Barrier properties of plastic films coated with an Al{sub 2}O{sub 3} layer by roll-to-toll atomic layer deposition

    Energy Technology Data Exchange (ETDEWEB)

    Hirvikorpi, Terhi, E-mail: Terhi.Hirvikorpi@picosun.com [Picosun Oy, Tietotie 3, FI-02150 Espoo (Finland); Laine, Risto, E-mail: Risto.Laine@picosun.com [Picosun Oy, Tietotie 3, FI-02150 Espoo (Finland); Vähä-Nissi, Mika, E-mail: Mika.Vaha-Nissi@vtt.fi [VTT Technical Research Centre of Finland, Biologinkuja 7, Espoo, P.O. Box 1000, FI-02044 VTT (Finland); Kilpi, Väinö, E-mail: Vaino.Kilpi@picosun.com [Picosun Oy, Tietotie 3, FI-02150 Espoo (Finland); Salo, Erkki, E-mail: Erkki.Salo@vtt.fi [VTT Technical Research Centre of Finland, Biologinkuja 7, Espoo, P.O. Box 1000, FI-02044 VTT (Finland); Li, Wei-Min, E-mail: Wei-Min.Li@picosun.com [Picosun Oy, Tietotie 3, FI-02150 Espoo (Finland); Lindfors, Sven, E-mail: Sven.Lindfors@picosun.com [Picosun Oy, Tietotie 3, FI-02150 Espoo (Finland); Vartiainen, Jari, E-mail: Jari.Vartiainen@vtt.fi [VTT Technical Research Centre of Finland, Biologinkuja 7, Espoo, P.O. Box 1000, FI-02044 VTT (Finland); Kenttä, Eija, E-mail: Eija.Kentta@vtt.fi [VTT Technical Research Centre of Finland, Biologinkuja 7, Espoo, P.O. Box 1000, FI-02044 VTT (Finland); Nikkola, Juha, E-mail: Juha.Nikkola@vtt.fi [VTT Technical Research Centre of Finland, P.O. Box 1300, FI-33101 Tampere (Finland); Harlin, Ali, E-mail: Ali.Harlin@vtt.fi [VTT Technical Research Centre of Finland, Biologinkuja 7, Espoo, P.O. Box 1000, FI-02044 VTT (Finland); Kostamo, Juhana, E-mail: Juhana.Kostamo@picosun.com [Picosun Oy, Tietotie 3, FI-02150 Espoo (Finland)

    2014-01-01

    Thin (30–40 nm) and highly uniform Al{sub 2}O{sub 3} coatings have been deposited at relatively low temperature of 100 °C onto various polymeric materials employing the atomic layer deposition (ALD) technique, both batch and roll-to-roll (R2R) mode. The applications for ALD have long been limited those feasible for batch processing. The work demonstrates that R2R ALD can deposit thin films with properties that are comparable to the film properties fabricated by in batch. This accelerates considerably the commercialization of many products, such as flexible, printed electronics, organic light-emitting diode lighting, third generation thin film photovoltaic devices, high energy density thin film batteries, smart textiles, organic sensors, organic/recyclable packaging materials, and flexible displays, to name a few. - Highlights: • Thin and uniform Al{sub 2}O{sub 3} coatings have been deposited onto polymers materials. • Batch and roll-to-roll (R2R) atomic layer deposition (ALD) have been employed. • Deposition with either process improved the barrier properties. • Sensitivity of coated films to defects affects barrier obtained with R2R ALD.

  8. Improvement of adhesion and barrier properties of biomedical stainless steel by deposition of YSZ coatings using RF magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Sánchez-Hernández, Z.E. [Instituto Politécnico Nacional, CICATA-Altamira, Grupo CIAMS, Km 14.5, Carretera Tampico-Puerto Industrial Altamira, C. P. 89600, Altamira, Tamps, México (Mexico); CICATA—Altamira, IPN. Grupo CIAMS, Km 14.5, Carretera Tampico-Puerto Industrial Altamira, C. P. 89600, Altamira, Tamps, México (Mexico); Domínguez-Crespo, M.A., E-mail: mdominguezc@ipn.mx [Instituto Politécnico Nacional, CICATA-Altamira, Grupo CIAMS, Km 14.5, Carretera Tampico-Puerto Industrial Altamira, C. P. 89600, Altamira, Tamps, México (Mexico); Torres-Huerta, A.M.; Onofre-Bustamante, E. [Instituto Politécnico Nacional, CICATA-Altamira, Grupo CIAMS, Km 14.5, Carretera Tampico-Puerto Industrial Altamira, C. P. 89600, Altamira, Tamps, México (Mexico); Andraca Adame, J. [Instituto Politécnico Nacional, Centro de Nanociencias Micro y Nanotecnologías, Departamento de DRX, C. P. 07300, Mexico, DF, México (Mexico); Dorantes-Rosales, H. [Instituto Politécnico Nacional, ESIQIE, Departamento de Metalurgia, C. P. 07300 Mexico, DF, México (Mexico)

    2014-05-01

    The AISI 316L stainless steel (SS) has been widely used in both artificial knee and hip joints in biomedical applications. In the present study, yttria stabilized zirconia (YSZ, ZrO{sub 2} + 8% Y{sub 2}O{sub 3}) films were deposited on AISI 316L SS by radio-frequency magnetron sputtering using different power densities (50–250 W) and deposition times (30–120 min) from a YSZ target. The crystallographic orientation and surface morphology were studied using X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The effects of the surface modification on the corrosion performance of AISI 316L SS were evaluated in phosphate buffered saline (PBS) solution using an electrochemical test on both the virgin and coated samples. The YSZ coatings have a (111) preferred orientation during crystal growth along the c-axis for short deposition times (30–60 min), whereas a polycrystalline structure forms during deposition times from 90 to 120 min. The corrosion protective character of the YSZ coatings depends on the crystal size and film thickness. A significant increase in adhesion and corrosion resistance by at least a factor of 46 and a higher breakdown potential were obtained for the deposited coatings at 200 W (120 min). - Highlights: • Well-formed and protective YSZ coatings were achieved on AISI 316L SS substrates. • Films grown at high power and long deposition time have polycrystalline structures. • The crystal size varies from ∼ 5 to 30 nm as both power and deposition time increased. • The differences of corrosion resistance are attributed to internal film structure.

  9. Improvement of adhesion and barrier properties of biomedical stainless steel by deposition of YSZ coatings using RF magnetron sputtering

    International Nuclear Information System (INIS)

    Sánchez-Hernández, Z.E.; Domínguez-Crespo, M.A.; Torres-Huerta, A.M.; Onofre-Bustamante, E.; Andraca Adame, J.; Dorantes-Rosales, H.

    2014-01-01

    The AISI 316L stainless steel (SS) has been widely used in both artificial knee and hip joints in biomedical applications. In the present study, yttria stabilized zirconia (YSZ, ZrO 2 + 8% Y 2 O 3 ) films were deposited on AISI 316L SS by radio-frequency magnetron sputtering using different power densities (50–250 W) and deposition times (30–120 min) from a YSZ target. The crystallographic orientation and surface morphology were studied using X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The effects of the surface modification on the corrosion performance of AISI 316L SS were evaluated in phosphate buffered saline (PBS) solution using an electrochemical test on both the virgin and coated samples. The YSZ coatings have a (111) preferred orientation during crystal growth along the c-axis for short deposition times (30–60 min), whereas a polycrystalline structure forms during deposition times from 90 to 120 min. The corrosion protective character of the YSZ coatings depends on the crystal size and film thickness. A significant increase in adhesion and corrosion resistance by at least a factor of 46 and a higher breakdown potential were obtained for the deposited coatings at 200 W (120 min). - Highlights: • Well-formed and protective YSZ coatings were achieved on AISI 316L SS substrates. • Films grown at high power and long deposition time have polycrystalline structures. • The crystal size varies from ∼ 5 to 30 nm as both power and deposition time increased. • The differences of corrosion resistance are attributed to internal film structure

  10. A CFD-Based Study of the Feasibility of Adapting an Erosion Burner Rig for Examining the Effect of CMAS Deposition Corrosion on Environmental Barrier Coatings

    Science.gov (United States)

    Miller, Robert A.; Kuczmarski, Maria A.

    2015-01-01

    Thermodynamic and computational fluid dynamics modeling has been conducted to examine the feasibility of adapting the NASA-Glenn erosion burner rigs for use in studies of corrosion of environmental barrier coatings by the deposition of molten CMAS. The effect of burner temperature, Mach number, particle preheat, duct heating, particle size, and particle phase (crystalline vs. glass) were analyzed. Detailed strategies for achieving complete melting of CMAS particles were developed, thereby greatly improving the probability of future successful experimental outcomes.

  11. Double-ceramic-layer thermal barrier coatings of La{sub 2}Zr{sub 2}O{sub 7}/YSZ deposited by electron beam-physical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Xu Zhenhua [State Key Laboratory of Rare Earth Resources Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China); Graduate School of Chinese Academy of Sciences, Beijing 100039 (China); Beijing Institute of Aeronautical Materials, Beijing 100095 (China); He Limin; Mu Rende [Beijing Institute of Aeronautical Materials, Beijing 100095 (China); Zhong Xinghua; Zhang Yanfei; Zhang Jiangfeng [State Key Laboratory of Rare Earth Resources Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China); Graduate School of Chinese Academy of Sciences, Beijing 100039 (China); Cao Xueqiang [State Key Laboratory of Rare Earth Resources Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China)], E-mail: xcao@ciac.jl.cn

    2009-04-03

    Double-ceramic-layer (DCL) thermal barrier coatings (TBCs) of La{sub 2}Zr{sub 2}O{sub 7} (LZ) and yttria stabilized zirconia (YSZ) were deposited by electron beam-physical vapor deposition (EB-PVD). The composition, crystal structure, surface and cross-sectional morphologies and cyclic oxidation behavior of the DCL coating were studied. Both the X-ray diffraction (XRD) and thermogravimetric-differential thermal analysis (TG-DTA) prove that LZ and YSZ have good chemical applicability to form a DCL coating. The thermal cycling test at 1373 K in an air furnace indicates the DCL coating has a much longer lifetime than the single layer LZ coating, and even longer than that of the single layer YSZ coating. The failure of the DCL coating is a result of both the bond coat oxidation and the thermal strain between bond coat and ceramic layer generated by the thermal expansion mismatch. Additionally, the compressive stress initiated during cooling is also an important factor to control the cleavage of the interface between the LZ and YSZ coatings. Since no single material that has been studied so far satisfies all the requirements for high temperature TBCs, DCL coating is an important development direction of TBCs.

  12. Low Conductivity Thermal Barrier Coatings

    Science.gov (United States)

    Zhu, Dong-Ming

    2005-01-01

    Thermal barrier coatings will be more aggressively designed to protect gas turbine engine hot-section components in order to meet future engine higher fuel efficiency and lower emission goals. In this presentation, thermal barrier coating development considerations and requirements will be discussed. An experimental approach is established to monitor in real time the thermal conductivity of the coating systems subjected to high-heat-flux, steady-state and cyclic temperature gradients. Advanced low conductivity thermal barrier coatings have also been developed using a multi-component defect clustering approach, and shown to have improved thermal stability. The durability and erosion resistance of low conductivity thermal barrier coatings have been improved utilizing advanced coating architecture design, composition optimization, in conjunction with more sophisticated modeling and design tools.

  13. Thermal barrier coatings - Technology for diesel engines

    International Nuclear Information System (INIS)

    Harris, D.H.; Lutz, J.

    1988-01-01

    Thermal Barrier Coatings (TBC) are a development of the aerospace industry primarily aimed at hot gas flow paths in turbine engines. TBC consists of zirconia ceramic coatings applied over (M)CrAlY. These coatings can provide three benefits: (1) a reduction of metal surface operating temperatures, (2) a deterrent to hot gas corrosion, and (3) improved thermal efficiencies. TBC brings these same benefits to reciprocal diesel engines but coating longevity must be demonstrated. Diesels require thicker deposits and have challenging geometries for the arc-plasma spray (APS) deposition process. Different approaches to plasma spraying TBC are required for diesels, especially where peripheral edge effects play a major role. Bondcoats and ceramic top coats are modified to provide extended life as determined by burner rig tests, using ferrous and aluminum substrates

  14. Phosphor-Doped Thermal Barrier Coatings Deposited by Air Plasma Spray for In-Depth Temperature Sensing

    Directory of Open Access Journals (Sweden)

    Di Peng

    2016-09-01

    Full Text Available Yttria-stabilized zirconia (YSZ-based thermal barrier coating (TBC has been integrated with thermographic phosphors through air plasma spray (APS for in-depth; non-contact temperature sensing. This coating consisted of a thin layer of Dy-doped YSZ (about 40 µm on the bottom and a regular YSZ layer with a thickness up to 300 µm on top. A measurement system has been established; which included a portable; low-cost diode laser (405 nm; a photo-multiplier tube (PMT and the related optics. Coating samples with different topcoat thickness were calibrated in a high-temperature furnace from room temperature to around 900 °C. The results convincingly showed that the current sensor and the measurement system was capable of in-depth temperature sensing over 800 °C with a YSZ top layer up to 300 µm. The topcoat thickness was found to have a strong effect on the luminescent signal level. Therefore; the measurement accuracy at high temperatures was reduced for samples with thick topcoats due to strong light attenuation. However; it seemed that the light transmissivity of YSZ topcoat increased with temperature; which would improve the sensor’s performance at high temperatures. The current sensor and the measurement technology have shown great potential in on-line monitoring of TBC interface temperature.

  15. Thermal barrier coatings for heat engine components

    Science.gov (United States)

    Levine, S. R.; Miller, R. A.; Hodge, P. E.

    1980-01-01

    A comprehensive NASA-Lewis program of coating development for aircraft gas turbine blades and vanes is presented. Improved ceramic layer compositions are investigated, along the MCrAlY bond films and the methods of uniform deposition of the coatings; the thermomechanical and fuel impurity tolerance limits of the coatings are being studied. Materials include the ZrO2-Y2O3/NiCrAlY system; the effects of the bond coat and zirconia composition on coating life and Mach 1 burner rig test results are discussed. It is concluded that Diesel engines can also utilize thermal barrier coatings; they have been used successfully on piston crowns and exhaust valves of shipboard engines to combat lower grade fuel combustion corrosion.

  16. Article Including Environmental Barrier Coating System

    Science.gov (United States)

    Lee, Kang N. (Inventor)

    2015-01-01

    An enhanced environmental barrier coating for a silicon containing substrate. The enhanced barrier coating may include a bond coat doped with at least one of an alkali metal oxide and an alkali earth metal oxide. The enhanced barrier coating may include a composite mullite bond coat including BSAS and another distinct second phase oxide applied over said surface.

  17. Thermal conductivity of zirconia thermal barrier coatings

    Science.gov (United States)

    Dinwiddie, R. B.; Beecher, S. C.; Nagaraj, B. A.; Moore, C. S.

    1995-01-01

    Thermal barrier coatings (TBC's) applied to the hot gas components of turbine engines lead to enhanced fuel efficiency and component reliability. Understanding the mechanisms which control the thermal transport behavior of the TBC's is of primary importance. Physical vapor deposition (PVD) and plasma spraying (PS) are the two most commonly used coating techniques. These techniques produce coatings with unique microstructures which control their performance and stability. The PS coatings were applied with either standard powder or hollow sphere particles. The hollow sphere particles yielded a lower density and lower thermal conductivity coating. The thermal conductivity of both fully and partially stabilized zirconia, before and after thermal aging, will be compared. The thermal conductivity of the coatings permanently increases upon exposed to high temperatures. These increases are attributed to microstructural changes within the coatings. Sintering of the as-fabricated plasma sprayed lamellar structure is observed by scanning electron microscopy of coatings isothermally heat treated at temperatures greater than 1100 C. During this sintering process the planar porosity between lamella is converted to a series of small spherical pores. The change in pore morphology is the primary reason for the observed increase in thermal conductivity. This increase in thermal conductivity can be modeled using a relationship which depends on both the temperature and time of exposure. Although the PVD coatings are less susceptible to thermal aging effects, preliminary results suggest that they have a higher thermal conductivity than PS coatings, both before and after thermal aging. The increases in thermal conductivity due to thermal aging for partially stabilized plasma sprayed zirconia have been found to be less than for fully stabilized plasma sprayed zirconia coatings. The high temperature thermal diffusivity data indicate that if these coatings reach a temperature above 1100 C

  18. Improved performance thermal barrier coatings

    International Nuclear Information System (INIS)

    Levine, S.R.; Miller, R.A.; Stecura, S.

    1983-01-01

    Thermal barrier coatings offer an attractive approach to improving the durability and efficiency of the hot section of heat engines. The coatings typically consist of an inner alloy bond coating about 0.01 cm thick resistant to oxidation and hot corrosion and an outer ceramic layer, usually a stabilized zirconia, 0.01-0.05 cm thick. Here, the materials, thermomechanical stress, and hot corrosion problems associated with thermal barrier coatings are reviewed along with the capabilities and limitations of current technology. The coatings discussed include ZrO2-Y2O3/NiCrAlY, ZrO2-Y2O3/NiCoCrAlY, ZrO2-MgO/NiCoCrAlY, CaO-SiO2/Co-Cr-Al-Y, and CaO-SiO2/NiCrAlY systems. It is emphasized that the performance of thermal barrier coatings is governed by many complex and interrelated factors, so that optimization of these coatings always involves certain tradeoffs. 27 references

  19. Thermal barrier coating resistant to sintering

    Science.gov (United States)

    Subramanian, Ramesh; Seth, Brij B.

    2004-06-29

    A device (10) is made, having a ceramic thermal barrier coating layer (16) characterized by a microstructure having gaps (18) with a sintering inhibiting material (22) disposed on the columns (20) within the gaps (18). The sintering resistant material (22) is stable over the range of operating temperatures of the device (10), is not soluble with the underlying ceramic layer (16) and is applied by a process that is not an electron beam physical vapor deposition process.

  20. Thermal barrier coating by electron beam-physical vapor deposition of zirconia co-doped with yttria and niobia

    Directory of Open Access Journals (Sweden)

    Daniel Soares de Almeida

    2010-08-01

    Full Text Available The most usual ceramic material for coating turbine blades is yttria doped zirconia. Addition of niobia, as a co-dopant in the Y2O3-ZrO2 system, can reduce the thermal conductivity and improve mechanical properties of the coating. The purpose of this work was to evaluate the influence of the addition of niobia on the microstructure and thermal properties of the ceramic coatings. SEM on coatings fractured cross-section shows a columnar structure and the results of XRD show only zirconia tetragonal phase in the ceramic coating for the chemical composition range studied. As the difference NbO2,5-YO1,5 mol percent increases, the tetragonality increases. A significant reduction of the thermal conductivity, measured by laser flash technique in the zirconia coating co-doped with yttria and niobia when compared with zirconia-yttria coating was observed.

  1. Atomic layer deposition of Al{sub 2}O{sub 3} and Al{sub 2}O{sub 3}/TiO{sub 2} barrier coatings to reduce the water vapour permeability of polyetheretherketone

    Energy Technology Data Exchange (ETDEWEB)

    Ahmadzada, Tamkin, E-mail: tahm4852@uni.sydney.edu.au [School of Aerospace, Mechanical and Mechatronic Engineering, University of Sydney, NSW 2006 (Australia); McKenzie, David R.; James, Natalie L.; Yin, Yongbai [School of Physics, University of Sydney, NSW 2006 (Australia); Li, Qing [School of Aerospace, Mechanical and Mechatronic Engineering, University of Sydney, NSW 2006 (Australia)

    2015-09-30

    We demonstrate significantly enhanced barrier properties of polyetheretherketone (PEEK) against water vapour penetration by depositing Al{sub 2}O{sub 3} or Al{sub 2}O{sub 3}/TiO{sub 2} nanofilms grown by atomic layer deposition (ALD). Nanoindentation analysis revealed good adhesion strength of a bilayer Al{sub 2}O{sub 3}/TiO{sub 2} coating to PEEK, while the single layer Al{sub 2}O{sub 3} coating displayed flaking and delamination. We identified three critical design parameters for achieving the optimum barrier properties of ALD Al{sub 2}O{sub 3}/TiO{sub 2} coatings on PEEK. These are a minimum total thickness dependent on the required water vapour transmission rate, the use of an Al{sub 2}O{sub 3}/TiO{sub 2} bilayer coating and the application of the coating to both sides of the PEEK film. Using these design parameters, we achieved a reduction in moisture permeability of PEEK of over two orders of magnitude while maintaining good adhesion strength of the polymer–thin film system. - Highlights: • Atomic layer deposition of Al{sub 2}O{sub 3}/TiO{sub 2} coatings reduced water vapour permeability. • Bilayer coatings reduced the permeability more than single layer coatings. • Bilayer coatings displayed higher adhesion strength than the single layer coatings. • Double-sided coatings performed better than single-sided coatings. • Correlation was found between total thickness and reduced water vapour permeability.

  2. Thermal Conductivity and Sintering Behavior of Advanced Thermal Barrier Coatings

    Science.gov (United States)

    Zhu, Dongming; Miller, Robert A.

    2002-01-01

    Advanced thermal barrier coatings, having significantly reduced long-term thermal conductivities, are being developed using an approach that emphasizes real-time monitoring of thermal conductivity under conditions that are engine-like in terms of temperatures and heat fluxes. This is in contrast to the traditional approach where coatings are initially optimized in terms of furnace and burner rig durability with subsequent measurement in the as-processed or furnace-sintered condition. The present work establishes a laser high-heat-flux test as the basis for evaluating advanced plasma-sprayed and physical vapor-deposited thermal barrier coatings under the NASA Ultra Efficient Engine Technology (UEET) Program. The candidate coating materials for this program are novel thermal barrier coatings that are found to have significantly reduced thermal conductivities due to an oxide-defect-cluster design. Critical issues for designing advanced low conductivity coatings with improved coating durability are also discussed.

  3. INFLUENCE OF WORKPIECE SURFACE PREPARATION ON THERMAL BARRIER COATING DURABILITY

    Directory of Open Access Journals (Sweden)

    M. A. Petrova

    2014-01-01

    Full Text Available Article deals with the impact of workpiece surface quality on adhesive strength and durability of thermal barrier coating. The result revealed that the roughness of metal layer influences on the adhesion of ceramic coating and depends the thickness of ceramic crystals when using method of Electron beam deposition.

  4. Ion Deposited Carbon Coatings.

    Science.gov (United States)

    1983-07-01

    sample is included in Figure 5.5.3. After one minute exposure, there was no detectable change in the surface of the coating or the polycarbonate. After...surface de 1/600 000 square meter of a blackbody at the 1/600 000 rnitre carr-6 d’un corps noir L ha temperature of freezing platinum under a temp6rature

  5. EMBEDDED OPTICAL SENSORS FOR THERMAL BARRIER COATINGS

    Energy Technology Data Exchange (ETDEWEB)

    David R. Clarke

    2004-12-16

    In this first year of the program we have focused on the selection of rare-earth dopants for luminescent sensing in thermal barrier coating materials, the effect of dopant concentration on several of the luminescence characteristics and initial fabrication of one type of embedded sensor, the ''red-line'' sensor. We have initially focused on erbium as the lanthanide dopant for luminescence doping of yttria-stabilized zirconia and europium as the lanthanide for luminescence doping of gadolinium zirconate. The latter exhibits a temperature-dependent luminescence lifetime up to at least 1100 C. A buried layer, ''red-line'' sensor in an electron-beam deposited yttria-stabilized zirconia coating with erbium has been demonstrated and exhibits a temperature-dependent luminescence lifetime up to at least 400 C.

  6. Low Thermal Conductivity Thermal Barrier Coatings Developed

    Science.gov (United States)

    Zhu, Dongming

    2003-01-01

    Thermal barrier coatings (TBCs) are used extensively in modern gas turbine engines to thermally insulate air-cooled metallic components from the hot gases in the engine. These coatings typically consist of a zirconia-yttria ceramic that has been applied by either plasma spraying or physical vapor deposition. Future engines will rely even more heavily on TBCs and will require materials that have even higher temperature capability with improved insulation (i.e., lower thermal conductivity even after many hours at high temperature). This report discusses new TBCs that have been developed with these future requirements in mind. The Ultra-Efficient Engine Technology Program at the NASA Glenn Research Center is funding this effort, which has been conducted primarily at Glenn with contractor support (GE and Howmet) for physical vapor deposition. As stated, the new TBC not only had to be more insulating but the insulation had to persist even after many hours of exposure-that is, the new TBC had to have both lower conductivity and improved sintering resistance. A new type of test rig was developed for this task. This new test approach used a laser to deliver a known high heat flux in an essentially uniform pattern to the surface of the coating, thereby establishing a realistic thermal gradient across its thickness. This gradient was determined from surface and backside pyrometry; and since the heat flux and coating thickness are known, this permitted continuous monitoring of thermal conductivity. Thus, this laser rig allowed very efficient screening of candidate low-conductivity, sinter-resistant TBCs. The coating-design approach selected for these new low-conductivity TBCs was to identify oxide dopants that had the potential to promote the formation of relatively large and stable groupings of defects known as defect clusters. This approach was used because it was felt that such clusters would reduce conductivity while enhancing stability. The approach proved to be

  7. Novel thermal barrier coatings based on La{sub 2}(Zr{sub 0.7}Ce{sub 0.3}){sub 2}O{sub 7}/8YSZ double-ceramic-layer systems deposited by electron beam physical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Xu Zhenhua, E-mail: zhxuciac@yahoo.com.cn [Beijing Institute of Aeronautical Materials, Department 5, P.O. Box 81-5, Beijing 100095 (China); He Shimei; He Limin; Mu Rende; Huang Guanghong [Beijing Institute of Aeronautical Materials, Department 5, P.O. Box 81-5, Beijing 100095 (China); Cao Xueqiang [State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China)

    2011-03-17

    Research highlights: > LZ7C3 and YSZ have good chemical compatibility for the formation of DCL coating. > DCL coating has a longer lifetime than that of single layer coating of LZ7C3 or YSZ. > Similar TECs of LZ7C3 with YSZ coatings and YSZ coating with TGO layer. > Unique growth modes of columns within DCL coating. > Outward diffusion of Cr element (bond coat) into LZ7C3 layer. - Abstract: Double-ceramic-layer (DCL) thermal barrier coatings (TBCs) of La{sub 2}(Zr{sub 0.7}Ce{sub 0.3}){sub 2}O{sub 7} (LZ7C3) and yttria stabilized zirconia (YSZ) were deposited by electron beam-physical vapor deposition (EB-PVD). The thermal cycling test at 1373 K in an air furnace indicates the DCL coating has a much longer lifetime than the single layer LZ7C3 coating, and even longer than that of the single layer YSZ coating. The superior sintering-resistance of LZ7C3 coating, the similar thermal expansion behaviors of YSZ interlayer with LZ7C3 coating and thermally grown oxide (TGO) layer, and the unique growth modes of columns within DCL coating are all very helpful to the prolongation of thermal cycling life of DCL coating. The failure of DCL coating is mainly a result of the reduction-oxidation of cerium oxide, the crack initiation, propagation and extension, the abnormal oxidation of bond coat, the degradation of t'-phase in YSZ coating and the outward diffusion of Cr alloying element into LZ7C3 coating.

  8. Double-ceramic-layer thermal barrier coatings based on La{sub 2}(Zr{sub 0.7}Ce{sub 0.3}){sub 2}O{sub 7}/La{sub 2}Ce{sub 2}O{sub 7} deposited by electron beam-physical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Z.H. [Beijing Institute of Aeronautical Materials, Department 5, P.O. Box 81-5, Beijing 100095 (China); State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China); Graduate School of Chinese Academy of Sciences, Beijing 100039 (China); He, L.M., E-mail: he_limin@yahoo.com [Beijing Institute of Aeronautical Materials, Department 5, P.O. Box 81-5, Beijing 100095 (China); Mu, R.D.; He, S.M.; Huang, G.H. [Beijing Institute of Aeronautical Materials, Department 5, P.O. Box 81-5, Beijing 100095 (China); Cao, X.Q., E-mail: xcao@ciac.jl.cn [State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China)

    2010-03-15

    Double-ceramic-layer (DCL) thermal barrier coatings (TBCs) of La{sub 2}(Zr{sub 0.7}Ce{sub 0.3}){sub 2}O{sub 7} (LZ7C3) and La{sub 2}Ce{sub 2}O{sub 7} (LC) were deposited by electron beam-physical vapor deposition (EB-PVD). The composition, interdiffusion, surface and cross-sectional morphologies, cyclic oxidation behavior of DCL coating were studied. Energy dispersive spectroscopy and X-ray diffraction analyses indicate that both LZ7C3 and LC coatings are effectively fabricated by a single LZ7C3 ingot with properly controlling the deposition energy. The chemical compatibility of LC coating and thermally grown oxide (TGO) layer is unstable. LaAlO{sub 3} is formed due to the chemical reaction between LC and Al{sub 2}O{sub 3} which is the main composition of TGO layer. Additionally, the thermal cycling behavior of DCL coating is influenced by the interdiffusion of Zr and Ce between LZ7C3 and LC coatings. The failure of DCL coating is a result of the sintering of LZ7C3 coating surface, the chemical incompatibility of LC coating and TGO layer and the abnormal oxidation of bond coat. Since no single material that has been studied so far satisfies all the requirements for high temperature applications, DCL coating is an important development direction of TBCs.

  9. Porosity determination of thermal barrier coatings

    Science.gov (United States)

    Van Roode, Mark; Beardsley, Brad

    1988-01-01

    Coating porosity is believed to be a critical factor for the thermal conductivity of thermal barrier coatings (TBCs). A number of different techniques have been used to determine the porosities of thermal barrier coatings for diesel applications as part of a NASA/DOE sponsored study. A comparison is made between methods based on water immersion, optical microscopy, eddy current thickness measurements, and Archimedes principle for TBC porosity determination.

  10. Thermal barrier coating having high phase stability

    Science.gov (United States)

    Subramanian, Ramesh

    2001-01-01

    A device (10) comprising a substrate (22) having a deposited ceramic thermal barrier coating layer (20) characterized by a microstructure having gaps (28) where the thermal barrier coating (20) consists essentially of a pyrochlore crystal structure having a chemical formula consisting essentially of A.sup.n+.sub.2-x B.sup.m+.sub.2+x O.sub.7-y, where A is selected from the group of elements selected from La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and mixtures thereof; where B is selected from the group of elements selected from Zr, Hf, Ti and mixtures thereof; n and m are the valence of A and B respectively, and for -0.5.ltoreq.x.ltoreq.0.5, ##EQU1## and excluding the following combinations for x=0, y=0: A=La and B=Zr; A=La and B=Hf; A=Gd and B=Hf; and A=Yb and B=Ti.

  11. Lower-Conductivity Thermal-Barrier Coatings

    Science.gov (United States)

    Miller, Robert A.; Zhu, Dongming

    2003-01-01

    Thermal-barrier coatings (TBCs) that have both initial and post-exposure thermal conductivities lower than those of yttria-stabilized zirconia TBCs have been developed. TBCs are thin ceramic layers, generally applied by plasma spraying or physical vapor deposition, that are used to insulate air-cooled metallic components from hot gases in gas turbine and other heat engines. Heretofore, yttria-stabilized zirconia (nominally comprising 95.4 atomic percent ZrO2 + 4.6 atomic percent Y2O3) has been the TBC material of choice. The lower-thermal-conductivity TBCs are modified versions of yttria-stabilized zirconia, the modifications consisting primarily in the addition of other oxides that impart microstructural and defect properties that favor lower thermal conductivity.

  12. Interaction of atomized colloid with an ac electric field in a dielectric barrier discharge reactor used for deposition of nanocomposite coatings

    Science.gov (United States)

    Profili, Jacopo; Dap, Simon; Levasseur, Olivier; Naude, Nicolas; Belinger, Antoine; Stafford, Luc; Gherardi, Nicolas

    2017-02-01

    Nanocomposite thin films can be obtained by polymerization of a colloidal solution in a dielectric barrier discharge (DBD) at atmospheric pressure. In such a process, the dispersion of nanoparticles into the matrix is driven by the charging, transport, and deposition dynamics of the atomized colloid. This work examines the interaction of atomized TiO2 nanoparticles with ac electric fields in a plane-to-plane dielectric barrier discharge reactor. Experiments are performed with the discharge off to examine transport and deposition phenomena over a wide range of experimental conditions with a fixed particle charge distribution. Scanning electron microscopy reveals that the size distribution of TiO2 nanoparticles collected at different locations along the substrate surface placed on the bottom electrode of the DBD reactor can judiciously be controlled by varying the amplitude and frequency of the ac electric field. These results are also compared to the predictions of a simple particle motion model accounting for the electrostatic force, the gravitational force, and the neutral drag force in the laminar flow. It is found that while the initial charge distribution of atomized particles strongly influences the total deposition yield, its maximal position on the substrate, and the width of the deposited area, the initial size distribution of the particles at the entrance of the reactor mostly changes the size distribution at each position along the substrate surface.

  13. Spray-Deposited Superconductor/Polymer Coatings

    Science.gov (United States)

    Wise, Stephanie A.; Tran, Sang Q.; Hooker, Matthew W.

    1993-01-01

    Coatings that exhibit the Meissner effect formed at relatively low temperature. High-temperature-superconductor/polymer coatings that exhibit Meissner effect deposited onto components in variety of shapes and materials. Simple, readily available equipment needed in coating process, mean coatings produced economically. Coatings used to keep magnetic fields away from electronic circuits in such cryogenic applications as magnetic resonance imaging and detection of infrared, and in magnetic suspensions to provide levitation and/or damping of vibrations.

  14. Development of metal based thermal barrier coatings

    Science.gov (United States)

    Shin, Dong-Il

    In this work, metal-based thermal barrier coatings (MBTBCs) have been produced, using high frequency induction plasma spraying (IPS) of iron-based nanostructured alloy powders. Important advances have been made over recent years to the development of ceramic-based thermal barrier coatings (TBCs) for internal combustion engines application, but they are not yet applied in mass production situations. Besides the important economic considerations, the reliability of ceramic: TBCs is also an issue, being associated with the difficulty of predicting their "in-service" lifetime. Through engineering of the nano/amorphous structure of MBTBCs, their thermal conductivity can be made as low as those of ceramic-based TBCs, with reduced mean free paths of the electrons/phonons scattering. In this work, nano/amorphous structured coatings were deposited by IPS using the following spray parameters: spraying distance (210 ˜ 270 mm), plasma gas composition (Ar/N2), IPS torch power (24kW), and powder feed-rate (16g/min.). The structure and properties of the deposited layers were characterized through SEM (Scanning Electron Microscopy) observations. The thermal diffusivity (alpha) properties of the MBTBCs were measured using a laser flash method. Density (rho) and specific heat (Cp) of the MBTBCs were also measured, and their thermal conductivity (k) calculated (k =alpharhoCp). The thermal conductivity of MBTBCs was found to be as low as 1.99 W/m/K. The heat treatment study showed that crystal structure changes, and grain size growth from a few nanometers to tenth of nanometers occurred at 550°C under static exposure conditions. Thermal expansion coefficient (TEC) of MBTBCs was 13E-6/K, which is close to the TEC of cast iron and thus, closer to the TEC values of aluminium alloys than are conventional TBCs. Fracture toughness of MBTBCs has also been assessed by use of Vickers hardness tests, with a 500 g load for 15 s, and the results show that there are no measurable crack

  15. Antireflection coatings on plastics deposited by plasma ...

    Indian Academy of Sciences (India)

    Wintec

    exposure to energetic radiations, followed by deposition of a carbonyl hard coating by spin or dip coating processes, UV curing, etc. However, this .... trodes in a cylindrical glass deposition chamber, has been designed, fabricated and assembled in-house. RF power can be applied across the electrodes with a RF generator.

  16. Surface coatings deposited by CVD and PVD

    International Nuclear Information System (INIS)

    Gabriel, H.M.

    1982-01-01

    The demand for wear and corrosion protective coatings is increasing due to economic facts. Deposition processes in gas atmospheres like the CVD and PVD processes attained a tremendous importance especially in the field of the deposition of thin hard refractory and ceramic coatings. CVD and PVD processes are reviewed in detail. Some examples of coating installations are shown and numerous applications are given to demonstrate the present state of the art. (orig.) [de

  17. Lifetime Modeling of Thermal Barrier Coatings

    OpenAIRE

    Hille, T.S.

    2009-01-01

    Thermal barrier coatings (TBCs) are applied in gas turbines to enhance their thermal efficiency by isolating the metallic components from the aggressive hot gas. TBC lifetime is limited by damage processes originating at internal interfaces, which may ultimately lead to delamination and spallation. In the present thesis constitutive models are presented for the coating components and the most detrimental failure mechanisms. To simulate the thermomechanical failure response, the numerical mode...

  18. Barrier Coatings for Refractory Metals and Superalloys

    Energy Technology Data Exchange (ETDEWEB)

    SM Sabol; BT Randall; JD Edington; CJ Larkin; BJ Close

    2006-02-23

    In the closed working fluid loop of the proposed Prometheus space nuclear power plant (SNPP), there is the potential for reaction of core and plant structural materials with gas phase impurities and gas phase transport of interstitial elements between superalloy and refractory metal alloy components during service. Primary concerns are surface oxidation, interstitial embrittlement of refractory metals and decarburization of superalloys. In parallel with kinetic investigations, this letter evaluates the ability of potential coatings to prevent or impede communication between reactor and plant components. Key coating requirements are identified and current technology coating materials are reviewed relative to these requirements. Candidate coatings are identified for future evaluation based on current knowledge of design parameters and anticipated environment. Coatings were identified for superalloys and refractory metals to provide diffusion barriers to interstitial transport and act as reactive barriers to potential oxidation. Due to their high stability at low oxygen potential, alumina formers are most promising for oxidation protection given the anticipated coolant gas chemistry. A sublayer of iridium is recommended to provide inherent diffusion resistance to interstitials. Based on specific base metal selection, a thin film substrate--coating interdiffusion barrier layer may be necessary to meet mission life.

  19. Barrier Coatings for Refractory Metals and Superalloys

    International Nuclear Information System (INIS)

    SM Sabol; BT Randall; JD Edington; CJ Larkin; BJ Close

    2006-01-01

    In the closed working fluid loop of the proposed Prometheus space nuclear power plant (SNPP), there is the potential for reaction of core and plant structural materials with gas phase impurities and gas phase transport of interstitial elements between superalloy and refractory metal alloy components during service. Primary concerns are surface oxidation, interstitial embrittlement of refractory metals and decarburization of superalloys. In parallel with kinetic investigations, this letter evaluates the ability of potential coatings to prevent or impede communication between reactor and plant components. Key coating requirements are identified and current technology coating materials are reviewed relative to these requirements. Candidate coatings are identified for future evaluation based on current knowledge of design parameters and anticipated environment. Coatings were identified for superalloys and refractory metals to provide diffusion barriers to interstitial transport and act as reactive barriers to potential oxidation. Due to their high stability at low oxygen potential, alumina formers are most promising for oxidation protection given the anticipated coolant gas chemistry. A sublayer of iridium is recommended to provide inherent diffusion resistance to interstitials. Based on specific base metal selection, a thin film substrate--coating interdiffusion barrier layer may be necessary to meet mission life

  20. Performance of Bond Coats Modified by Platinum Group Metals for Applications in Thermal Barrier Coatings

    Science.gov (United States)

    Tawancy, H. M.; Alhems, Luai M.; Aboelfotoh, M. O.

    2017-07-01

    We have investigated the partial replacement of Pt with other less expensive Pt group metals on the properties of γ' + γ bond coats used in thermal barrier coatings (TBCs) deposited on a nickel-base superalloy. The microstructure, thermal stability, oxidation behavior and performance in TBC systems of bond coats synthesized with Pt + Ru, Pt + Ir and Pt + Rh are compared with those of a reference bond coat synthesized with Pt. Yttria-stabilized zirconia has been employed as top coat in all coating systems. It is shown that at high temperatures all bond coats are degraded by interdiffusion and oxidation, however, with different kinetics. The lifetime of each TBC system is found to be limited by the cohesion between the thermally grown oxide and underlying bond coat. Differences in the behavior of various bond coats are correlated with their properties. Among the three Pt group metals investigated, the properties of the Pt + Ru bond coat are shown to closely approach those of the Pt bond coat. It is concluded that Ru with much lower cost presents a potential candidate for reducing the consumption of Pt.

  1. Functional Plasma-Deposited Coatings

    Directory of Open Access Journals (Sweden)

    Mykhaylo Pashechko

    2017-12-01

    Full Text Available The paper focuses on the problem of low adhesion of plasma sprayed coatings to the substrate. The subsequent laser treatment modes and their influence on the coating-substrate interface were studied. This allows to decrease the level of metstability of the coating, thus decreasing its hardness down to 11-12 GPa on the surface and to about 9 GPa on depth of 400 µm. The redistribution of alloying elements through solid and liquid diffusion improves mechanical properties and rises the adhesion up to 450 MPa after remelting and up to 90-110 MPa after laser-aided thermal cycling. At he same time, remelting of coating helps to decrease its porosity down to 1%. Obtained complex of properties also allows to improve wear resistance of coatings and to decrease friction factor.

  2. Lower-Conductivity Ceramic Materials for Thermal-Barrier Coatings

    Science.gov (United States)

    Bansal, Narottam P.; Zhu, Dongming

    2006-01-01

    Doped pyrochlore oxides of a type described below are under consideration as alternative materials for high-temperature thermal-barrier coatings (TBCs). In comparison with partially-yttria-stabilized zirconia (YSZ), which is the state-of-the-art TBC material now in commercial use, these doped pyrochlore oxides exhibit lower thermal conductivities, which could be exploited to obtain the following advantages: For a given difference in temperature between an outer coating surface and the coating/substrate interface, the coating could be thinner. Reductions in coating thicknesses could translate to reductions in weight of hot-section components of turbine engines (e.g., combustor liners, blades, and vanes) to which TBCs are typically applied. For a given coating thickness, the difference in temperature between the outer coating surface and the coating/substrate interface could be greater. For turbine engines, this could translate to higher operating temperatures, with consequent increases in efficiency and reductions in polluting emissions. TBCs are needed because the temperatures in some turbine-engine hot sections exceed the maximum temperatures that the substrate materials (superalloys, Si-based ceramics, and others) can withstand. YSZ TBCs are applied to engine components as thin layers by plasma spraying or electron-beam physical vapor deposition. During operation at higher temperatures, YSZ layers undergo sintering, which increases their thermal conductivities and thereby renders them less effective as TBCs. Moreover, the sintered YSZ TBCs are less tolerant of stress and strain and, hence, are less durable.

  3. Lifetime Modeling of Thermal Barrier Coatings

    NARCIS (Netherlands)

    Hille, T.S.

    2009-01-01

    Thermal barrier coatings (TBCs) are applied in gas turbines to enhance their thermal efficiency by isolating the metallic components from the aggressive hot gas. TBC lifetime is limited by damage processes originating at internal interfaces, which may ultimately lead to delamination and spallation.

  4. Mechanisms of thermal barrier coating degradation and failure

    Science.gov (United States)

    Demasi, J. T.; Sheffler, K. D.

    1985-01-01

    The objectives and initial results of a Thermal Barrier Coating (TBC) Life Prediction Model Development Program are described. The goals of this program are to: identify and understand TBC failure modes; generate quantitative TBC life data; and develop and verify a TBC life prediction model. The coating being studied is a two layer thermal barrier system incorporating a nominal ten mil outer layer of seven percent yttria partially stabilized zirconia plasma deposited over an inner layer of highly oxidation resistant low pressure plasma sprayed NiCrAlY bond coating. This coating currently is in flight service on turbine vane platforms in the JT-9D and PW2037 engines and is bill-of- material on turbine vane airfoils in the advanced PW4000 and IAE V2500 engines. Effort currently is in progress on the first task, which involves the identification and understanding of TBC failures. Five modes of coating damage were considered: thermomechanical ceramic failure; oxidative bond coat failure; hot corrosion; foreign object damage (FOD); and erosion.

  5. Deposition characteristics of titanium coating deposited on SiC fiber by cold-wall chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Xian, E-mail: luo_shenfan@hotmail.com; Wu, Shuai; Yang, Yan-qing; Jin, Na; Liu, Shuai; Huang, Bin

    2016-12-01

    The deposition characteristics of titanium coating on SiC fiber using TiCl{sub 4}-H{sub 2}-Ar gas mixture in a cold-wall chemical vapor deposition were studied by the combination of thermodynamic analysis and experimental studies. The thermodynamic analysis of the reactions in the TiCl{sub 4}-H{sub 2}-Ar system indicates that TiCl{sub 4} transforms to titanium as the following paths: TiCl{sub 4} → TiCl{sub 3} → Ti, or TiCl{sub 4} → TiCl{sub 3} → TiCl{sub 2} → Ti. The experimental results show that typical deposited coating contains two distinct layers: a TiC reaction layer close to SiC fiber and titanium coating which has an atomic percentage of titanium more than 70% and that of carbon lower than 30%. The results illustrate that a carbon diffusion barrier coating needs to be deposited if pure titanium is to be prepared. The deposition rate increases with the increase of temperature, but higher temperature has a negative effect on the surface uniformity of titanium coating. In addition, appropriate argon gas flow rate has a positive effect on smoothing the surface morphology of the coating. - Highlights: • Both thermodynamic analysis and experimental studies were adopted in this work. • The transformation paths of TiCl{sub 4} to Ti is: TiCl{sub 4} → TiCl{sub 3} → Ti, or TiCl{sub 4} → TiCl{sub 3} → TiCl{sub 2} → Ti. • Typical deposited Ti coating on SiC fiber contained two distinct layers. • Deposition temperature is important on deposition rate and morphologies. • Appropriate argon gas flow rate has a positive effect on smoothing of the coating.

  6. Study of high temperature oxidation of duplex and functionally graded materials of thermal barrier coating (FGM TBC)

    International Nuclear Information System (INIS)

    Saeedi, B.; Sabour, A. R.; Khodami, A. M.

    2008-01-01

    Although the number and the severity of thermal barrier coatings applications on hot section components have dramatically increased in the past decade, premature spallation failure of thermal barrier coatings , due to mismatch of thermal expansion at the metal/ceramic interface of the two coating layers, during service is still an overriding concern. Therefore, functionally graded materials with a gradual compositional variation have been introduced. In this study, comparison of properties of two different types of thermal barrier coatings was made to improve the surface characteristics on high temperature components. These thermal barrier coatings consisted of a duplex thermal barrier coatings and a five layered functionally graded thermal barrier coatings . In both coatings, Yttria partially stabilized Zirconia topcoat was deposited by air plasma spraying and Ni Cr Al Y bond coat was deposited by high velocity oxy fuel spraying. In functionally graded materials coating, functionally graded layer was sprayed by air plasma process by varying the feeding ratio of YSZ/Ni Cr Al Y powders using two separate powder feeders. Then, isothermal oxidation was carried out at 950 d eg C in atmosphere to obtain the plot of mass change vs. time to study oxidation kinetic. Microstructural and compositional changes of coating, oxides formed during service were examined by optical microscope and scanning electron microscopy with EDS. functionally graded materials coating failed after 2100 h and duplex coating failed after 1700 h. Finally, it was found that functionally graded materials coating is more qualified than duplex thermal barrier coatings and stands for a longer time

  7. Microstructure Analysis of Laser Remelting for Thermal Barrier Coatings on the Surface of Titanium Alloy

    Directory of Open Access Journals (Sweden)

    Lu Bin

    2016-01-01

    Full Text Available In this paper, the preparation and organization performance of thermal barrier coatings (TCBs on the surface of titanium were studied experimentally. Nanostructured 8 wt% yttria partially stabilized zirconia coatings were deposited by air plasma spraying. The microstructure of nanostructured and the conventional coating was studied after laser remelting. It has shown that formed a network of micro-cracks and pits after laser remelting on nanostructured coatings. With the decrease of the laser scanning speed, mesh distribution of micro cracks was gradually thinning on nanostructured coatings. Compared with conventional ceramic layers, the mesh cracks of nanostructured coating is dense and the crack width is small.

  8. Measurement of interfacial shear mechanical properties in thermal barrier coating systems by a barb pullout method

    International Nuclear Information System (INIS)

    Guo, S.Q.; Mumm, D.R.; Karlsson, A.M.; Kagawa, Y.

    2005-01-01

    A test technique has been developed to facilitate evaluation of the fracture characteristics of coatings and interfaces in thermal barrier coating (TBC) systems. The methodology has particular application in analyzing delamination crack growth, where crack propagation occurs under predominantly mode II loading. The technique has been demonstrated by quantitatively measuring the effective delamination fracture resistance of an electron-beam physical vapor deposition TBC

  9. UNA REVISIÓN DEL SPRAY TÉRMICO COMO TÉCNICA DE DEPOSICIÓN PARA CAPAS DE BARRERAS TÉRMICAS // THE THERMAL SPRAY AS A DEPOSITION TECHNIQUE FOR THERMAL BARRIER COATING: A REVIEW

    Directory of Open Access Journals (Sweden)

    Eduardo Rondón Briceño

    2015-06-01

    Full Text Available It is important to know the thermal barrier deposition techniques since materials with low thermal conductivity in the barrier can be obtained from them. The dependence of the thermal conductivity with the temperature can be divided into four regions. In this work, we were interested in the study of used techniques for the manufacture of materials with a desirable low thermal conductivity that will be exposed to high temperatures that is to say, materials found in the III and IV region. In these regions the thermal conductivity can be reduced increasing the porosity of the material. Through the study of the thermal barrier deposition techniques we found that the thermal spray produces a coat with high porosity, being the low velocity flame spray technique the best to produce coat of La2Zr2O7 with a minimal thermal conductivity. The thermal spray technique is low cost and almost any material can be thermally sprayed, so this can be considered a very attractive technique for industrial applications. // RESUMEN Es importante conocer las técnicas de deposición de barreras térmicas ya que de ellas depende la obtención de materiales con baja conductividad térmica en la barrera. La dependencia de la conductividad térmica con la temperatura puede dividirse en cuatro regiones. En este trabajo estuvimos interesados en el estudio de las técnicas que se utilizan para la fabricación de materiales sometidos a muy altas temperaturas y donde se desea que su conductividad térmica sea baja, es decir, materiales que se encuentran en la región III y IV. En estas regiones se puede disminuir la conductividad térmica aumentando la porosidad del material. A través del estudio de las técnicas de deposición de barreras térmica, hemos encontrado que la técnica del spray térmico produce una alta porosidad en el recubrimiento, siendo el método de rociado con baja velocidad el mejor método para producir capas de La2Zr2O7 con mínima conductividad t

  10. Laser deposition of coatings for aeronautical and industrials turbine blades

    Energy Technology Data Exchange (ETDEWEB)

    Teleginski, V. [Instituto Federal de Sao Paulo (IFSP), SP (Brazil); Silva, S.A.; Riva, R.; Vasconcelos, G. [Instituto de Estudos Avancados (IEAv), Sao Jose dos Campos, SP (Brazil); Silva Pita, G.R. [Universidade Braz Cubas, Mogi das Cruzes, SP (Brazil); Yamin, L.S. [Escola Tecnica Everardo Passos (ETEP), Sao Jose dos Campos, DP (Brazil)

    2016-07-01

    Full text: Zirconium-based ceramic materials are widely employed as Thermal Barrier Coatings (TBC), due to its excellent wear and corrosion resistance at high temperatures. The application of TBC includes aeronautical and industrials turbine blades. The working conditions include oxidizing environments and temperatures above 1000°C. The zirconium-based ceramics are developed in such a way that the microstructural control is possible through the control of chemical composition, fabrication route and, thermal treatment. The present paper proposes a laser route to deposit the TBC coating, where the microstructural control is a function of power density and interaction time between the laser beam and the material. The main objective of this work is to study the influence of the CO2 laser beam (Synrad Evolution 125) parameters: power density and interaction time, on the deposition process of yttria-stabilized zirconia (YSZ) powders on NiCrAlY/AISI 316L substrates. The resulting coating surface and interface were characterized by scanning electron microscopy, energy dispersive spectroscopy and X-ray diffraction. The results indicate that is possible to match laser parameters of scanning speed and intensity to produce homogenous coatings. The X-Ray analyses show that the obtained ceramic coating has reduced number of phases, with prevalence of tetragonal phase.(author)

  11. Environmental Barrier Coatings for Ceramic Matrix Composites - An Overview

    Science.gov (United States)

    Lee, Kang; van Roode, Mark; Kashyap, Tania; Zhu, Dongming; Wiesner, Valerie

    2017-01-01

    SiC/SiC Ceramic Matrix Composites (CMCs) are increasingly being considered as structural materials for advanced power generation equipment because of their light weight, higher temperature capability, and oxidation resistance. Limitations of SiC/SiC CMCs include surface recession and component cracking and associated chemical changes in the CMC. The solutions pursued to improve the life of SiC/SiC CMCs include the incorporation of coating systems that provide surface protection, which has become known as an Environmental Barrier Coating (EBC). The development of EBCs for the protection of gas turbine hot section CMC components was a continuation of coating development work for corrosion protection of silicon-based monolithics. Work on EBC development for SiC/SiC CMCs has been ongoing at several national laboratories and the original gas turbine equipment manufacturers. The work includes extensive laboratory, rig and engine testing, including testing of EBC coated SiC/SiC CMCs in actual field applications. Another EBC degradation issue which is especially critical for CMC components used in aircraft engines is the degradation from glassy deposits of calcium-magnesium-aluminosilicate (CMAS) with other minor oxides. This paper addresses the need for and properties of external coatings on SiC/SiC CMCs to extend their useful life in service and the retention of their properties.

  12. Deposition and Characterization of TRISO Coating Layers

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Do Kyung; Kim, Min Woo; Lee, Hyeon Keun [KAIST, Daejeon (Korea, Republic of); Choi, Doo Jin; Kim, Jun Kyu; Cho, Sung Hyuk [Younsei University, Seoul (Korea, Republic of)

    2008-03-15

    Both ZrC and SiC layers are crucial layers in TRISO coated fuel particles since they prevent diffusion of fission products and provide mechanical strength for the fuel particle. However, each layer has its own defects, so the purpose of this study is to complement such defects of these layers. In this study, we carried out thermodynamic simulations before actual experiments. With these simulation results, we deposited the ZrC layers on SiC/graphite substrates through CVD process. SiC films on graphite have different microstructures which are a hemispherical angular, domed top and faceted structure at different deposition temperature, respectively. According to the microstructures of SiC, preferred orientation, hardness and elastic modules of deposited ZrC layer were changed. TRISO particles. The fracture the SiC coating layer occurred by the tensile stress due to the traditional pressure vessel failure criteria. It is important to find fracture stress of SiC coating layer by the internal pressurization test method. The finite-element analysis was carried out to obtain the empirical equation of strength evaluation. By using this empirical equation, the mechanical properties of several types of SiC coating film with different microstructure and thicknesses will discussed.

  13. TECHNOLOGICAL PECULIARITIES OF THERMAL BARRIER COATINGS BASED ON ZIRCONIUM DIOXIDE

    OpenAIRE

    V. V. Okovity; O. G. Devoino; V. A. Okovity; V. M. Astashinsky

    2016-01-01

    A technology for formation of thermal barrier coatings (TBC) based on zirconium dioxide has been developed in the paper. The paper investigates structures of phase composition and thermal stability of such developed coatings. Investigation results pertaining to formation of an oxide system ZrO2 – Y2O3, while using plasma spraying and subsequent high-energy processing, which allows to increase resistance of a thermal barrier coating to thermal cycling heat resistance of the coating at temperat...

  14. Graded coatings for thermal, wear and corrosion barriers

    International Nuclear Information System (INIS)

    Schulz, U.; Peters, M.; Bach, Fr.-W.; Tegeder, G.

    2003-01-01

    The present paper summarizes the main results generated in a German National Science Foundation (DFG) program on projects concerned with functionally graded materials applied to optimize the thermal, wear and corrosion properties of metallic and ceramic materials. Thermal barrier coatings deposited onto Cu substrates by pulsed laser deposition showed improved spallation behavior by a graded lamella microstructure with improved interface fracture toughness. A particle-hardened graded surface structure improved the wear resistance of plasma sprayed thermal barriers. By means of evaporation techniques a graded bonding area was manufactured with a high potential of lifetime improvement. For non-oxide ceramics graded coatings based on Si 3 N 4 and mullite led to improved oxidation resistance of the substrate material. Graded TiC-TiN thin films allowed to improve the wear resistance of cutting tool alloys with good adhesion to the substrate material. On light metal alloys, the limits of grading with respect to corrosion protection as well as wear were determined. Graded layers of arc-sprayed titanium with in situ produced particles or welded alloy gradients led to improved wear characteristics. Stress profiles in graded layers were analyzed with the help of a modified X-ray diffraction analysis

  15. Ceramic thermal barrier coatings for electric utility gas turbine engines

    Science.gov (United States)

    Miller, R. A.

    1986-01-01

    Research and development into thermal barrier coatings for electric utility gas turbine engines is reviewed critically. The type of coating systems developed for aircraft applications are found to be preferred for clear fuel electric utility applications. These coating systems consists of a layer of plasma sprayed zirconia-yttria ceramic over a layer of MCrAly bond coat. They are not recommended for use when molten salts are presented. Efforts to understand coating degradation in dirty environments and to develop corrosion resistant thermal barrier coatings are discussed.

  16. Advanced Low Conductivity Thermal Barrier Coatings: Performance and Future Directions

    Science.gov (United States)

    Zhu, Dongming; Miller, Robert A.

    2008-01-01

    Thermal barrier coatings will be more aggressively designed to protect gas turbine engine hot-section components in order to meet future engine higher fuel efficiency and lower emission goals. In this presentation, thermal barrier coating development considerations and performance will be emphasized. Advanced thermal barrier coatings have been developed using a multi-component defect clustering approach, and shown to have improved thermal stability and lower conductivity. The coating systems have been demonstrated for high temperature combustor applications. For thermal barrier coatings designed for turbine airfoil applications, further improved erosion and impact resistance are crucial for engine performance and durability. Erosion resistant thermal barrier coatings are being developed, with a current emphasis on the toughness improvements using a combined rare earth- and transition metal-oxide doping approach. The performance of the toughened thermal barrier coatings has been evaluated in burner rig and laser heat-flux rig simulated engine erosion and thermal gradient environments. The results have shown that the coating composition optimizations can effectively improve the erosion and impact resistance of the coating systems, while maintaining low thermal conductivity and cyclic durability. The erosion, impact and high heat-flux damage mechanisms of the thermal barrier coatings will also be described.

  17. Thermal Barrier Coatings for Advanced Gas Turbine and Diesel Engines

    Science.gov (United States)

    Zhu, Dongming; Miller, Robert A.

    1999-01-01

    Ceramic thermal barrier coatings (TBCS) have been developed for advanced gas turbine and diesel engine applications to improve engine reliability and fuel efficiency. However, durability issues of these thermal barrier coatings under high temperature cyclic conditions are still of major concern. The coating failure depends not only on the coating, but also on the ceramic sintering/creep and bond coat oxidation under the operating conditions. Novel test approaches have been established to obtain critical thermomechanical and thermophysical properties of the coating systems under near-realistic transient and steady state temperature and stress gradients encountered in advanced engine systems. This paper presents detailed experimental and modeling results describing processes occurring in the ZrO2-Y2O3 thermal barrier coating systems, thus providing a framework for developing strategies to manage ceramic coating architecture, microstructure and properties.

  18. Deposition and Characterization of TRISO Coating Layers

    Energy Technology Data Exchange (ETDEWEB)

    Kim, D. K.; Choi, D. J.; Lee, H. K.; Kim, J. K.; Kim, J. H.; Chun, J. H. [KAIST, Daejeon (Korea, Republic of)

    2007-03-15

    Zirconium carbide has been chosen and studied as an advanced material of silicon carbide. In order to collect data on the basic properties and characteristics of Zirconium carbide, studies have been conducted using various methods. As a result of chemically vapor deposed subliming zirconium tetrachloride(ZrCl4) and using methane(CH4) as a source in hydrogen atmosphere, graphite film is deposited.. Zirconium carbide was deposited on the sample where silicon carbide was deposited on a graphite substrate using Zirconium sponge as a Zirconium source. In terms of physical characteristics, the deposited Zirconium carbide showed higher strength, but slightly lower elastic modulus than silicon carbide. In order to evaluate the mechanical properties of a coating layer in pre-irradiation step, internal pressure induced method and direct strength measurement method is carried out. In the internal pressure induced method, in order to produce the requirement pressure, pressure media is used. In the direct strength measurement method, the indentation experiment that indent on a hemisphere shell with plate indenter is conducted. For this method, the finite element analysis is used and the analysis is verified by indentation experiments. To measure the strength of TRISO particle SiC coating, SiC hemisphere shell is performed through grinding and heat treatment. Through the finite element analysis, strength evaluation equation is suggested. Using suggested equation, Strength evaluation is performed and the strength value shows 1025MPa as a result of statistical analysis.

  19. Deposition and Characterization of TRISO Coating Layers

    International Nuclear Information System (INIS)

    Kim, D. K.; Choi, D. J.; Lee, H. K.; Kim, J. K.; Kim, J. H.; Chun, J. H.

    2007-03-01

    Zirconium carbide has been chosen and studied as an advanced material of silicon carbide. In order to collect data on the basic properties and characteristics of Zirconium carbide, studies have been conducted using various methods. As a result of chemically vapor deposed subliming zirconium tetrachloride(ZrCl4) and using methane(CH4) as a source in hydrogen atmosphere, graphite film is deposited.. Zirconium carbide was deposited on the sample where silicon carbide was deposited on a graphite substrate using Zirconium sponge as a Zirconium source. In terms of physical characteristics, the deposited Zirconium carbide showed higher strength, but slightly lower elastic modulus than silicon carbide. In order to evaluate the mechanical properties of a coating layer in pre-irradiation step, internal pressure induced method and direct strength measurement method is carried out. In the internal pressure induced method, in order to produce the requirement pressure, pressure media is used. In the direct strength measurement method, the indentation experiment that indent on a hemisphere shell with plate indenter is conducted. For this method, the finite element analysis is used and the analysis is verified by indentation experiments. To measure the strength of TRISO particle SiC coating, SiC hemisphere shell is performed through grinding and heat treatment. Through the finite element analysis, strength evaluation equation is suggested. Using suggested equation, Strength evaluation is performed and the strength value shows 1025MPa as a result of statistical analysis

  20. Experimental techniques for the characterization and development of thermal barrier coating bond coat alloys

    Science.gov (United States)

    Thompson, Robert J.

    Thermal barrier coatings, commonly used in modern gas turbines and jet engines, are dynamic, multilayered structures consisting of a superalloy substrate, an Al-rich bond coat, a thermally grown oxide, and a ceramic top coat. Knowledge of the disparate material properties for each of the constituents of a thermal barrier coating is crucial to both better understanding and improving the performance of the system. The efforts of this dissertation quantify fundamental aspects of two intrinsic strain mechanisms that arise during thermal cycling. This includes measurement of the thermal expansion behavior for bond coats and superalloys as well as establishing specific ternary compositions associated with a strain-inducing martensitic phase transformation, which is known to occur in Ni-rich bond coat alloys. In order to quantify the coefficient of thermal expansion for a number of actual alloys extracted from contemporary thermal barrier coating systems, this work employs a noncontact high temperature digital image correlation technique to nearly 1100°C. The examined materials include: two commercial superalloys, two as-deposited commercial bond coat alloys, and three experimental bond coat alloys. The as-deposited specimens were created using a diffusion aluminizing and a low pressure plasma spray procedure to thicknesses on the order of 50 and 100 mum, respectively. For the plasma sprayed bond coat, a comparison with a bulk counterpart of identical composition indicated that deposition procedures have little effect on thermal expansion. An analytical model of oxide rumpling is used to show that the importance of thermal expansion mismatch between a commercial bond coat and its superalloy substrate is relatively small. Considerably higher expansion values are noted for a Ni-rich bond coat alloy, however, and modeling which includes this layer suggests that it may have a substantial influence on rumpling. Combinatorial methods based on diffusion multiples are also

  1. Novel hybrid polymeric materials for barrier coatings

    Science.gov (United States)

    Pavlacky, Erin Christine

    Polymer-clay nanocomposites, described as the inclusion of nanometer-sized layered silicates into polymeric materials, have been widely researched due to significant enhancements in material properties with the incorporation of small levels of filler (1--5 wt.%) compared to conventional micro- and macro-composites (20--30 wt.%). One of the most promising applications for polymer-clay nanocomposites is in the field of barrier coatings. The development of UV-curable polymer-clay nanocomposite barrier coatings was explored by employing a novel in situ preparation technique. Unsaturated polyesters were synthesized in the presence of organomodified clays by in situ intercalative polymerization to create highly dispersed clays in a precursor resin. The resulting clay-containing polyesters were crosslinked via UV-irradiation using donor-acceptor chemistry to create polymer-clay nanocomposites which exhibited significantly enhanced barrier properties compared to alternative clay dispersion techniques. The impact of the quaternary alkylammonium organic modifiers, used to increase compatibility between the inorganic clay and organic polymer, was studied to explore influence of the organic modifier structure on the nanocomposite material properties. By incorporating just the organic modifiers, no layered silicates, into the polyester resins, reductions in film mechanical and thermal properties were observed, a strong indicator of film plasticization. An alternative in situ preparation method was explored to further increase the dispersion of organomodified clay within the precursor polyester resins. In stark contrast to traditional in situ polymerization methods, a novel "reverse" in situ preparation method was developed, where unmodified montmorillonite clay was added during polyesterification to a reaction mixture containing the alkylammonium organic modifier. The resulting nanocomposite films exhibited reduced water vapor permeability and increased mechanical properties

  2. Influence of Experimental Parameters Using the Dip-Coating Method on the Barrier Performance of Hybrid Sol-Gel Coatings in Strong Alkaline Environments

    Directory of Open Access Journals (Sweden)

    Rita B. Figueira

    2015-04-01

    Full Text Available Previous studies have shown that the barrier effect and the performance of organic-inorganic hybrid (OIH sol-gel coatings are highly dependent on the coating deposition method as well as on the processing conditions. However, studies on how the coating deposition method influences the barrier properties in alkaline environments are scarce. The aim of this experimental research was to study the influence of experimental parameters using the dip-coating method on the barrier performance of an OIH sol-gel coating in contact with simulated concrete pore solutions (SCPS. The influence of residence time (Rt, a curing step between each dip step and the number of layers of sol-gel OIH films deposited on hot-dip galvanized steel to prevent corrosion in highly alkaline environments was studied. The barrier performance of these OIH sol-gel coatings, named U(400, was assessed in the first instants of contact with SCPS, using electrochemical impedance spectroscopy and potentiodynamic methods. The durability and stability of the OIH coatings in SCPS was monitored during eight days by macrocell current density. The morphological characterization of the surface was performed by Scanning Electronic Microscopy before and after exposure to SCPS. Glow Discharge Optical Emission Spectroscopy was used to investigate the thickness of the U(400 sol-gel coatings as a function of the number of layers deposited with and without Rt in the coatings thickness.

  3. A high performance ceria based interdiffusion barrier layer prepared by spin-coating

    DEFF Research Database (Denmark)

    Plonczak, Pawel; Joost, Mario; Hjelm, Johan

    2011-01-01

    . The successive steps of dense layer production was investigated by scanning electron microscopy. X-ray diffraction was employed to monitor the crystal structure of the CGO layer sintered at different temperatures. The described spin coated barrier layer was evaluated using an anode supported cell......A multiple spin-coating deposition procedure of Ce0.9Gd0.1O1.95 (CGO) for application in solid oxide fuel cells (SOFCs) was developed. The thin and dense CGO layer can be employed as a barrier layer between yttria stabilised zirconia (YSZ) electrolyte and a (La, Sr)(Co, Fe)O3 based cathode....... The decomposition of the polymer precursor used in the spin-coating process was studied. The depositions were performed on anode supported half cells. By controlling the sintering temperature between each spin-coating process, dense and crack-free CGO films with a thickness of approximately 1 μm were obtained...

  4. Electrochemical deposition of Ni–TiN nanocomposite coatings and ...

    Indian Academy of Sciences (India)

    s12034-016-1238-3. Electrochemical deposition of Ni–TiN nanocomposite coatings and the effect of sodium dodecyl sulphate surfactant on the coating properties. NAFISE PARHIZKAR1, ABOLGHASEM DOLATI1, ROYA AGHABABAZADEH2 and.

  5. Evolution of pore microstructure in thermal barrier coatings studied by SANS

    Czech Academy of Sciences Publication Activity Database

    Haug, J.; Wiedenmann, A.; Flores, A.; Saruhan-Brings, B.; Strunz, Pavel

    2006-01-01

    Roč. 385, č. 1 (2006), s. 617-619 ISSN 0921-4526 R&D Projects: GA ČR GA202/06/0601 Institutional research plan: CEZ:AV0Z10480505 Keywords : thermal barrier coatings * electron beam physical vapor deposition * SANS Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.872, year: 2006

  6. Effect of Suspension Plasma-Sprayed YSZ Columnar Microstructure and Bond Coat Surface Preparation on Thermal Barrier Coating Properties

    Science.gov (United States)

    Bernard, Benjamin; Quet, Aurélie; Bianchi, Luc; Schick, Vincent; Joulia, Aurélien; Malié, André; Rémy, Benjamin

    2017-08-01

    Suspension plasma spraying (SPS) is identified as promising for the enhancement of thermal barrier coating (TBC) systems used in gas turbines. Particularly, the emerging columnar microstructure enabled by the SPS process is likely to bring about an interesting TBC lifetime. At the same time, the SPS process opens the way to a decrease in thermal conductivity, one of the main issues for the next generation of gas turbines, compared to the state-of-the-art deposition technique, so-called electron beam physical vapor deposition (EB-PVD). In this paper, yttria-stabilized zirconia (YSZ) coatings presenting columnar structures, performed using both SPS and EB-PVD processes, were studied. Depending on the columnar microstructure readily adaptable in the SPS process, low thermal conductivities can be obtained. At 1100 °C, a decrease from 1.3 W m-1 K-1 for EB-PVD YSZ coatings to about 0.7 W m-1 K-1 for SPS coatings was shown. The higher content of porosity in the case of SPS coatings increases the thermal resistance through the thickness and decreases thermal conductivity. The lifetime of SPS YSZ coatings was studied by isothermal cyclic tests, showing equivalent or even higher performances compared to EB-PVD ones. Tests were performed using classical bond coats used for EB-PVD TBC coatings. Thermal cyclic fatigue performance of the best SPS coating reached 1000 cycles to failure on AM1 substrates with a β-(Ni,Pt)Al bond coat. Tests were also performed on AM1 substrates with a Pt-diffused γ-Ni/γ'-Ni3Al bond coat for which more than 2000 cycles to failure were observed for columnar SPS YSZ coatings. The high thermal compliance offered by both the columnar structure and the porosity allowed the reaching of a high lifetime, promising for a TBC application.

  7. High Energy Radial Deposition of Diamond-Like Carbon Coatings

    Directory of Open Access Journals (Sweden)

    Konrad Suschke

    2015-07-01

    Full Text Available Diamond-like carbon (DLC coatings were deposited with a new direct ion deposition system using a novel 360 degree ion source operating at acceleration voltage between 4 and 8 kV. Cross-sectional TEM images show that the coatings have a three layered structure which originates from changes in the deposition parameters taking into account ion source condition, ion current density, deposition angles, ion sputtering and ion source movement. Varying structural growth conditions can be achieved by tailoring the deposition parameters. The coatings show good promise for industrial use due to their high hardness, low friction and excellent adhesion to the surface of the samples.

  8. A Study of Deposition Coatings Formed by Electroformed Metallic Materials.

    Directory of Open Access Journals (Sweden)

    Shoji Hayashi

    Full Text Available Major joining methods of dental casting metal include brazing and laser welding. However, brazing cannot be applied for electroformed metals since heat treatment could affect the fit, and, therefore, laser welding is used for such metals. New methods of joining metals that do not impair the characteristics of electroformed metals should be developed. When new coating is performed on the surface of the base metal, surface treatment is usually performed before re-coating. The effect of surface treatment is clinically evaluated by peeling and flex tests. However, these testing methods are not ideal for deposition coating strength measurement of electroformed metals. There have been no studies on the deposition coating strength and methods to test electroformed metals. We developed a new deposition coating strength test for electroformed metals. The influence of the negative electrolytic method, which is one of the electrochemical surface treatments, on the strength of the deposition coating of electroformed metals was investigated, and the following conclusions were drawn: 1. This process makes it possible to remove residual deposits on the electrodeposited metal surface layer. 2. Cathode electrolysis is a simple and safe method that is capable of improving the surface treatment by adjustments to the current supply method and current intensity. 3. Electrochemical treatment can improve the deposition coating strength compared to the physical or chemical treatment methods. 4. Electro-deposition coating is an innovative technique for the deposition coating of electroformed metal.

  9. Nano-structured yttria-stabilized zirconia coating by electrophoretic deposition

    Energy Technology Data Exchange (ETDEWEB)

    Maleki-Ghaleh, H., E-mail: H_Maleki@sut.ac.ir [Faculty of Materials Engineering, Sahand University of Technology, Tabriz (Iran, Islamic Republic of); Rekabeslami, M. [Faculty of Mechanical Engineering, Materials Science and Engineering Division, K. N. Toosi University of Technology, Tehran (Iran, Islamic Republic of); Shakeri, M.S. [Materials and Energy Research Center, Karaj (Iran, Islamic Republic of); Siadati, M.H. [Faculty of Mechanical Engineering, Materials Science and Engineering Division, K. N. Toosi University of Technology, Tehran (Iran, Islamic Republic of); Javidi, M. [Department of Materials Science and Engineering, School of Engineering, Shiraz University, Shiraz (Iran, Islamic Republic of); Talebian, S.H. [Faculty of Petroleum Engineering, Universiti Technologi Petronas, Perak (Malaysia); Aghajani, H. [Department of Materials Engineering, University of Tabriz, Tabriz (Iran, Islamic Republic of)

    2013-09-01

    The most important role of thermal barrier coatings is to reduce the temperature of the substrate in high temperature applications. Nanoparticle zirconia might be a suitable choice for improving the efficiency of thermal barrier coatings. Nanostructured coatings have lower thermal conduction, higher thermal expansion and lower dimensional variations at higher temperatures in comparison with the microstructured coatings. Electrophoretic deposition has been preferred for thermal barrier coatings due to its simplicity, controllability and low cost. In the present study, three different suspensions of ZrO{sub 2}–8 wt%Y{sub 2}O{sub 3} (40 nm) made with ethanol, acetone and acetyl acetone were used. Electrophoretic deposition was conducted at a fixed voltage of 60 V for 120 s on aluminized Inconel 738-LC, and then heat treated at 1100{sup o}C for 4 h in air atmosphere. The coating morphology and elemental distribution were studied using scanning electron microscopy. It was observed that suspension media have an important effect on the quality of the final product. Acetyl acetone showed better dispersion of particles than the other two media. Consequently, deposition from acetyl acetone resulted in uniform and crack-free layers while those from ethanol and acetone were completely non-uniform due to agglomeration and low viscosity, respectively.

  10. Electrochemical deposition of mineralized BSA/collagen coating

    Energy Technology Data Exchange (ETDEWEB)

    Zhuang, Junjun [School of Materials Science and Engineering, State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou 310027 (China); Lin, Jun; Li, Juan; Wang, Huiming [The First Affiliated Hospital of Medical College, Zhejiang University, Hangzhou 310003 (China); Cheng, Kui [School of Materials Science and Engineering, State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou 310027 (China); Weng, Wenjian, E-mail: wengwj@zju.edu.cn [School of Materials Science and Engineering, State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou 310027 (China); The Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China)

    2016-09-01

    In this work, mineralized collagen coatings with different loading quantity of bovine serum albumin (BSA) were prepared via in situ electrochemical deposition on titanium substrate. The microstructure and BSA loading quantity of the coatings could be controlled by the electrochemical deposition parameters, such as deposition potential, BSA concentration and its adding sequence in the electrolyte. The BSA loading quantity in the coatings was obtained in the range of 0.0170–0.173 mg/cm{sup 2}, enhancing the cell adhesion and proliferation of the coatings with the simultaneous release. The distinct release behaviors of BSA were attributed to their gradient distribution with different mineralization degrees, which could be adjusted by the deposition process. These results suggest that in situ electrochemical deposition is a promising way to incorporate functional molecules into the mineralized collagen coatings and the mineralized BSA/collagen coatings are highly promising for improving the rhBMP-2 loading capability (1.8-fold). - Highlights: • BSA is incorporated into mineralized collagen coating by electrochemical deposition. • The loading amount of BSA in coatings can be adjusted in the range of 0-173 ng. • The BSA/collagen coating shows good cytocompatibility with free-albumin culture. • The incorporation process is put forward for some other molecules deposition.

  11. Optical Diagnostics of Thermal Barrier Coatings

    Science.gov (United States)

    Majewski, Mark Steven

    The high temperature properties of ceramic materials make them suitable for the extreme environments of gas combustion powered turbines. They are instrumental in providing thermal insulation for the metallic turbine components from the combustion products. Also, the addition of specific rare earth elements to ceramics creates materials with temperature diagnostic applications. Laser based methods have been applied to these ceramic coatings to predict their remaining thermal insulation service life and to explore their high temperature diagnostic capabilities. A method for cleaning thermal barrier coatings (TBCs) contaminated during engine operation has been developed using laser ablation. Surface contamination on the turbine blades hinders nondestructive remaining life prediction using photo luminescence piezospectroscopy (PLPS). Real time monitoring of the removed material is employed to prevent damage to the underlying coating. This method relies on laser induced breakdown spectroscopy (LIBS) to compute the cross correlation coefficient between the spectral emissions of a sample TBC that is contaminated and a reference clean TBC. It is possible to remove targeted contaminants and cease ablation when the top surface of the TBC has been reached. In collaboration with this work, Kelley's thesis [1] presents microscopy images and PLPS measurements indicating the integrity of the TBC has been maintained during the removal of surface contaminants. Thermographic phosphors (TGP) have optical emission properties when excited by a laser that are temperature dependent. These spectral and temporal properties have been investigated and utilized for temperature measurement schemes by many previous researchers. The compounds presented in this dissertation consist of various rare earth (Lanthanide) elements doped into a host crystal lattice. As the temperature of the lattice changes, both the time scale for vibrational quenching and the distribution of energy among atomic energy

  12. Electrolytic deposition and corrosion resistance of Zn–Ni coatings ...

    Indian Academy of Sciences (India)

    Zn–Ni coatings were deposited under galvanostatic conditions on steel substrate (OH18N9). The influence of current density of deposition on the surface morphology, chemical and phase composition was investigated. The corrosion resistance of Zn–Ni coatings obtained at current density 10–25 mA cm-2 are measured, ...

  13. Electrolytic deposition and corrosion resistance of Zn–Ni coatings

    Indian Academy of Sciences (India)

    Zn–Ni coatings were deposited under galvanostatic conditions on steel substrate (OH18N9). The influence of current density of deposition on the surface morphology, chemical and phase composition was investigated. The corrosion resistance of Zn–Ni coatings obtained at current density 10–25 mA cm-2 are measured, ...

  14. Erosion and foreign object damage of thermal barrier coatings

    International Nuclear Information System (INIS)

    Nicholls, J.R.; Jaslier, Y.; Rickerby, D.S.

    1997-01-01

    Thermal barrier coating technology is used in the hot sections of gas turbines to extend component life. To maximise these benefits, the thermal barrier coating has to remain intact throughout the life of the turbine. High velocity ballistic damage can lead to total thermal barrier removal, while erosion may lead to progressive loss of thickness during operation. This paper particularly addresses the erosion resistance and resistance to foreign object damage of thermal barrier coatings. It was found that EB-PVD thermal barriers are significantly more erosion resistant when impacted with alumina or silica, than the equivalent plasma spray coating, both at room temperature and 910 C. Examination of tested hardware, reveals that cracking occurs within the near surface region of the columns for EB-PVD ceramic and that erosion occurs by removal of these small blocks of material. In stark contrast, removal of material for plasma sprayed ceramic occurs through poorly bonded splat boundaries. Large particle impact results in severe damage to the EB-PVD thermal barrier, with cracks penetrating through the ceramic coating to the ceramic/bond coat interface. Material removal, per particle impact, increases with increased particle size. (orig.)

  15. Assessment of variations in thermal cycle life data of thermal barrier coated rods

    Science.gov (United States)

    Hendricks, R. C.; Mcdonald, G.

    1981-01-01

    The reported study had the purpose to examine variations in cyclic life and in adhesive/cohesive coating strength. Possible effects of heating rate, stress reversal, temperature level, and ceramic deposition methods on coating life were also investigated. Life cycle data for 22 thermal barrier coated rods were examined and found to be statistically modeled by normal or log-normal distributions. The sample mean was 1330 cycles with a standard deviation of 520 cycles. Adhesive/cohesive pulloff strength data for 20 thermal barrier coated flat head piston specimens were taken. The average pulloff stress was 9 MPa with a standard deviation of 4.2 MPa. It was found that variations in heating rate can produce significant variations in the life cycle data.

  16. Thermophysical and Thermomechanical Properties of Thermal Barrier Coating Systems

    Science.gov (United States)

    Zhu, Dongming; Miller, Robert A.

    2000-01-01

    Thermal barrier coatings have been developed for advanced gas turbine and diesel engine applications to improve engine reliability and fuel efficiency. However, the issue of coating durability under high temperature cyclic conditions is still of major concern. The coating failure is closely related to thermal stresses and oxidation in the coating systems. Coating shrinkage cracking resulting from ceramic sintering and creep at high temperatures can further accelerate the coating failure process. The purpose of this paper is to address critical issues such as ceramic sintering and creep, thermal fatigue and their relevance to coating life prediction. Novel test approaches have been established to obtain critical thermophysical and thermomechanical properties of the coating systems under near-realistic temperature and stress gradients encountered in advanced engine systems. Emphasis is placed on the dynamic changes of the coating thermal conductivity and elastic modulus, fatigue and creep interactions, and resulting failure mechanisms during the simulated engine tests. Detailed experimental and modeling results describing processes occurring in the thermal barrier coating systems provide a framework for developing strategies to manage ceramic coating architecture, microstructure and properties.

  17. Thermal Barrier Coatings on Copper Substrates for Rocket Applications

    Science.gov (United States)

    Schloesser, Jana; Fedorova, Tatiana; Bäker, Martin; Rösler, Joachim

    Currently a new generation of relaunchable space transportation system using liquid hydrogen/ liquid oxygen rocket engines is under development. The inner combustion chamber is exposed to extreme thermal loads and environmental attack during starts. To prevent failure of the cooling channels, a thermal barrier coating to provide thermal and oxidation protection could be applied. Thermal barrier coatings are state of the art for gas turbines and this concept should be transferred to copper substrates in rocket engine applications. The thermomechanical loading conditions are quite different from the gas turbine applications as heat fluxes and temperature gradients are much higher while overall service time is much shorter. As a start for optimization of a suitable coating, a material system known for gas turbines is employed. In this work a thermal barrier coating system is applied by atmospheric plasma spraying to the copper-based high strength alloy Cu-1%Cr-0.3%Zr. The bond coat consists of a NiCrAlY alloy, while partially stabilized zirconia is used as a top coat. Spraying parameter optimization for the new substrate is described. The reached coating system is tested in thermal cycling experiments, where no failure of the coating could be detected. In oxidation experiments good environmental protection of the coating is shown.

  18. Dip Process Thermal Barrier Coatings for Superalloys.

    Science.gov (United States)

    1980-06-01

    melting Ce-Co or Ce-Ni alloy, By internally oxidizing these coatings, t is possible to obtain a duplex with a CeO2 -rich oxide scale as the outer layer... Slurry Fusion Coatings......................15 Ultra-Rich Cerium (.- 90%) Dip Coating on IN738 .......... 17 CONCLUSIONS...alloy powder slurried with an organic vehicle, then fired in an inert atmosphere. Our original concept was to selectively oxidize cerium, using CO/CO 2

  19. Thermal conductivity issues of EB-PVD thermal barrier coatings

    Energy Technology Data Exchange (ETDEWEB)

    Schulz, U.; Raetzer-Scheibe, H.J.; Saruhan, B. [DLR - German Aerospace Center, Institute of Materials Research, 51170 Cologne (Germany); Renteria, A.F. [BTU, Physical Metallurgy and Materials Technology, Cottbus (Germany)

    2007-09-15

    The thermal conductivity of electron-beam physical vapor deposited (EB-PVD) thermal barrier coatings (TBCs) was investigated by the Laser Flash technique. Sample type and methodology of data analyses as well as atmosphere during the measurement have some influence on the data. A large variation of the thermal conductivity was found by changes in TBC microstructure. Exposure at high temperature caused sintering of the porous microstructure that finally increased thermal conductivity up to 30 %. EB-PVD TBCs show a distinct thickness dependence of the thermal conductivity due to the anisotropic microstructure in thickness direction. Thin TBCs had a 20 % lower thermal conductivity than thick coatings. New compositions of the ceramic top layer offer the largest potential to lower thermal conductivity. Values down to 0.8W/(mK) have been already demonstrated with virgin coatings of pyrochlore compositions. (Abstract Copyright [2007], Wiley Periodicals, Inc.) [German] Die Waermeleitfaehigkeit von elektronenstrahl-aufgedampften (EB-PVD) Waermedaemmschichten (TBCs) wurde mittels Laser-Flash untersucht. Probentyp, Messmethodik und die Atmosphaere waehrend der Messung haben einen Einfluss auf die Ergebnisse. Aenderungen in der Mikrostruktur der TBC fuehrten zu grossen Unterschieden der Waermeleitfaehigkeit. Eine Hochtemperaturbelastung verursachte Sintervorgaenge in der poroesen Mikrostruktur, was die Waermeleitfaehigkeit um bis zu 30 % ansteigen liess. EB-PVD TBCs zeigen eine deutliche Dickenabhaengigkeit der Waermeleitfaehigkeit durch die Anisotropie der Mikrostruktur in dieser Richtung. Duenne TBCs haben eine um 20 % geringere Waermeleitfaehigkeit als dicke Schichten. Neue Zusammensetzungen der keramischen Deckschicht bieten die groessten Moeglichkeiten fuer eine Reduktion der Waermeleitfaehigkeit. Werte bis zu 0,8 W/(mK) wurden damit bereits erreicht. (Abstract Copyright [2007], Wiley Periodicals, Inc.)

  20. Microstructural aspects of zirconia thermal barrier coatings

    Science.gov (United States)

    Mitchell, T. E.; Suhr, D. S.; Keller, R. J.; Lanteri, V.; Heuer, A. H.

    1985-01-01

    Various combination of plasma-sprayed bond coatings and zirconia ceramic coatings on a nickel-based superalloy substrate were tested by static thermal exposure at 1200 C and cyclic thermal exposure to 1000 C. The bond coats were based on Ni-Cr-Al alloys with additions of rare earth elements and Si. The ceramic coats were various ZrO2-Y2O3 compositions, of which the optimum was found to be ZrO2-8.9 wt percent Y2O3. Microstructural analysis showed that resistance to cracking during thermal exposure is strongly related to deleterious phase changes. Zones depleted of Al formed at the bond coat/ceramic coat interface due to oxidation and at the bond coat/substrate interface due to interdiffusion, leading eventually to breakdown of the bond coat. The 8.9 percent Y2O3 coating performed best because the as-sprayed metastable tetragonal phase converted slowly into the low-Y2O3 tetragonal plus high-Y2O3 cubic-phase mixture, so that the deleterious monoclinic phase was inhibited from forming. Failure appeared to start with the formation of circumferential cracks in the zirconia, probably due to compressive stresses during cooling, followed by the formation of radial cracks due to tensile stresses during heating. Cracks appeared to initiate at the Al2O3 scale/bond coat interface and propagate through the zirconia coating. Comparisons were made with the behavior of bulk ZrO2-Y2O3 and the relationship between the microstructure of the tetragonal phase and the phase diagram. A separate investigation was also made of the ZrO2-Al2O3 interface.

  1. Gas barrier properties of hydrogenated amorphous carbon films coated on polyethylene terephthalate by plasma polymerization in argon/n-hexane gas mixture

    Energy Technology Data Exchange (ETDEWEB)

    Polonskyi, Oleksandr; Kylián, Ondřej, E-mail: ondrej.kylian@gmail.com; Petr, Martin; Choukourov, Andrei; Hanuš, Jan; Biederman, Hynek

    2013-07-01

    Hydrogenated amorphous carbon thin films were deposited by RF plasma polymerization in argon/n-hexane gas mixture on polyethylene terephthalate (PET) foils. It was found that such deposited films may significantly improve the barrier properties of PET. It was demonstrated that the principal parameter that influences barrier properties of such deposited films towards oxygen and water vapor is the density of the coatings. Moreover, it was shown that for achieving good barrier properties it is advantageous to deposit coatings with very low thickness. According to the presented results, optimal thickness of the coating should not be higher than several tens of nm. - Highlights: • a-C:H films were prepared by plasma polymerization in Ar/n-hexane atmosphere. • Barrier properties of coatings are dependent on their density and thickness. • Highest barrier properties were observed for films with thickness 15 nm.

  2. Design of Thermal Barrier Coatings Thickness for Gas Turbine Blade Based on Finite Element Analysis

    Directory of Open Access Journals (Sweden)

    Biao Li

    2017-01-01

    Full Text Available Thermal barrier coatings (TBCs are deposited on the turbine blade to reduce the temperature of underlying substrate, as well as providing protection against the oxidation and hot corrosion from high temperature gas. Optimal ceramic top-coat thickness distribution on the blade can improve the performance and efficiency of the coatings. Design of the coatings thickness is a multiobjective optimization problem due to the conflicts among objectives of high thermal insulation performance, long operation durability, and low fabrication cost. This work developed a procedure for designing the TBCs thickness distribution for the gas turbine blade. Three-dimensional finite element models were built and analyzed, and weighted-sum approach was employed to solve the multiobjective optimization problem herein. Suitable multiregion top-coat thickness distribution scheme was designed with the considerations of manufacturing accuracy, productivity, and fabrication cost.

  3. Protective silicon coating for nanodiamonds using atomic layer deposition

    International Nuclear Information System (INIS)

    Lu, J.; Wang, Y.H.; Zang, J.B.; Li, Y.N.

    2007-01-01

    Ultrathin silicon coating was deposited on nanodiamonds using atomic layer deposition (ALD) from gaseous monosilane (SiH 4 ). The coating was performed by sequential reaction of SiH 4 saturated adsorption and in situ decomposition. X-ray diffraction (XRD) and transmission electron microscopy (TEM) were utilized to investigate the structural and morphological properties of the coating. Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) were used to compare the thermal stability of nanodiamonds before and after silicon coating. The results confirmed that the deposited cubic phase silicon coating was even and continuous. The protective silicon coating could effectively improve the oxidation resistance of nanodiamonds in air flow, which facilitates the applications of nanodiamonds that are commonly hampered by their poor thermal stability

  4. Large-scale, thick, self-assembled, nacre-mimetic brick-walls as fire barrier coatings on textiles.

    Science.gov (United States)

    Das, Paramita; Thomas, Helga; Moeller, Martin; Walther, Andreas

    2017-01-05

    Highly loaded polymer/clay nanocomposites with layered structures are emerging as robust fire retardant surface coatings. However, time-intensive sequential deposition processes, e.g. layer-by-layer strategies, hinders obtaining large coating thicknesses and complicates an implementation into existing technologies. Here, we demonstrate a single-step, water-borne approach to prepare thick, self-assembling, hybrid fire barrier coatings of sodium carboxymethyl cellulose (CMC)/montmorillonite (MTM) with well-defined, bioinspired brick-wall nanostructure, and showcase their application on textile. The coating thickness on the textile is tailored using different concentrations of CMC/MTM (1-5 wt%) in the coating bath. While lower concentrations impart conformal coatings of fibers, thicker continuous coatings are obtained on the textile surface from highest concentration. Comprehensive fire barrier and fire retardancy tests elucidate the increasing fire barrier and retardancy properties with increasing coating thickness. The materials are free of halogen and heavy metal atoms, and are sourced from sustainable and partly even renewable building blocks. We further introduce an amphiphobic surface modification on the coating to impart oil and water repellency, as well as self-cleaning features. Hence, our study presents a generic, environmentally friendly, scalable, and one-pot coating approach that can be introduced into existing technologies to prepare bioinspired, thick, fire barrier nanocomposite coatings on diverse surfaces.

  5. Large-scale, thick, self-assembled, nacre-mimetic brick-walls as fire barrier coatings on textiles

    Science.gov (United States)

    Das, Paramita; Thomas, Helga; Moeller, Martin; Walther, Andreas

    2017-01-01

    Highly loaded polymer/clay nanocomposites with layered structures are emerging as robust fire retardant surface coatings. However, time-intensive sequential deposition processes, e.g. layer-by-layer strategies, hinders obtaining large coating thicknesses and complicates an implementation into existing technologies. Here, we demonstrate a single-step, water-borne approach to prepare thick, self-assembling, hybrid fire barrier coatings of sodium carboxymethyl cellulose (CMC)/montmorillonite (MTM) with well-defined, bioinspired brick-wall nanostructure, and showcase their application on textile. The coating thickness on the textile is tailored using different concentrations of CMC/MTM (1-5 wt%) in the coating bath. While lower concentrations impart conformal coatings of fibers, thicker continuous coatings are obtained on the textile surface from highest concentration. Comprehensive fire barrier and fire retardancy tests elucidate the increasing fire barrier and retardancy properties with increasing coating thickness. The materials are free of halogen and heavy metal atoms, and are sourced from sustainable and partly even renewable building blocks. We further introduce an amphiphobic surface modification on the coating to impart oil and water repellency, as well as self-cleaning features. Hence, our study presents a generic, environmentally friendly, scalable, and one-pot coating approach that can be introduced into existing technologies to prepare bioinspired, thick, fire barrier nanocomposite coatings on diverse surfaces.

  6. Fluidized bed deposition and evaluation of silicon carbide coatings on microspheres

    International Nuclear Information System (INIS)

    Federer, J.I.

    1977-01-01

    The fuel element for the HTGR is an array of closely packed fuel microspheres in a carbonaceous matrix. A coating of dense silicon carbide (SiC), along with pyrocarbon layers, is deposited on the fueled microspheres to serve as a barrier against diffusion of fission products. The microspheres are coated with silicon carbide in a fluidized bed by reaction of methyltrichlorosilane (CH 3 SiCl 3 or MTS) and hydrogen at elevated temperatures. The principal variables of coating temperature and reactant gas composition (H 2 /MTS ratio) have been correlated with coating rate, morphology, stoichiometry, microstructure, and density. The optimum temperature for depositing highly dense coatings is in the range 1475 to 1675 0 C. Lower temperatures result in silicon-rich deposits, while higher temperatures may cause unacceptable porosity. The optimum H 2 /MTS ratio for highly dense coatings is 20 or more (approximately 5% MTS or less). The amount of grown-in porosity increases as the H 2 /MTS ratio decreases below 20. The requirement that the H 2 /MTS ratio be about 20 or more imposes a practical restraint on coating rate, since increasing the total flow rate would eventually expel microspheres from the coating tube. Evaluation of stoichiometry, morphology, and microstructure support the above mentioned optimum conditions of temperature and reactant gas composition. 18 figures, 3 tables

  7. TECHNOLOGICAL PECULIARITIES OF THERMAL BARRIER COATINGS BASED ON ZIRCONIUM DIOXIDE

    Directory of Open Access Journals (Sweden)

    V. V. Okovity

    2016-01-01

    Full Text Available A technology for formation of thermal barrier coatings (TBC based on zirconium dioxide has been developed in the paper. The paper investigates structures of phase composition and thermal stability of such developed coatings. Investigation results pertaining to formation of an oxide system ZrO2 – Y2O3, while using plasma spraying and subsequent high-energy processing, which allows to increase resistance of a thermal barrier coating to thermal cycling heat resistance of the coating at temperature of 1100 °C. This leads to longer protection of bottom layer against high-temperature exposure. The methodology is based on complex metallographic, X-ray diffraction and electron microscopy investigations of structural elements in composite plasma coatings of the ZrO2 – Y2O system. Resistance of plasma coatings (Мe – Cr – Al – Y/ZrO2 – Y2O3-type, used as TBC to protect gas turbine engine blades under conditions of frequent thermal cyclings is limited by cleavage of an outer ceramic layer. Structural and electron microprobe investigations have shown that as a result of thermal cycling an outer atmosphere due to porous structure of the ceramic coating layer, migrates to the surface of lower metal coating, causing its oxidation. As a result, the metal-ceramic Al2O3 layer is formed at a metal-ceramic interface and it changes a stress state of the coating that causes a reduction of protective properties. Thus, a high heat resistance of thermal barrier coatings depends on processes occurring at the interface between metal and ceramic coating layers. A laser impact on samples with TBC leads to changes in the structure of the oxide layer of ZrO2 – Y2O3. In this case its initial surface characterized by considerable relief is significantly flattened due to processing and the coating is fractured and it is separated in fragments. As the oxide coating has low thermal conductivity, and the time of laser exposure is about 10–3 sec, a heat flux

  8. The modeling of coating thickness, heat transfer, and fluid flow and its correlation with the thermal barrier coating microstructure for a plasma sprayed gas turbine application

    Science.gov (United States)

    Nylén, P.; Wigren, J.; Pejryd, L.; Hansson, M.-O.

    1999-09-01

    The plasma sprya deposition of a zirconia thermal barrier coating (TBC) on a gas turbine component was examined using analytical and experimental techniques. The coating thickness was simulated by the use of commercial off-line software. The impinging jet was modeled by means of a finite difference elliptic code using a simplified turbulence model. Powder particle velocity, temperature history, and trajectory were calculated using a stochastic discrete particle model. The heat transfer and fluid flow model were then used to calculate transient coating and substrate temperatures using the finite element method. The predicted thickness, temperature, and velocity of the particles and the coating temperatures were compared with these measurements, and good correlations were obtained. The coating microstructure was evaluated by optical and scanning microscopy techniques. Special attention was paid to the crack structures within the top coating. Finally, the correlation between the modeled parameters and the deposit microstructure was studied.

  9. Chemical vapor deposited fiber coatings and chemical vapor infiltrated ceramic matrix composites

    Energy Technology Data Exchange (ETDEWEB)

    Kmetz, M.A.

    1992-01-01

    Conventional Chemical Vapor Deposition (CVD) and Organometallic Chemical Vapor Deposition (MOCVD) were employed to deposit a series of interfacial coatings on SiC and carbon yarn. Molybdenum, tungsten and chromium hexacarbonyls were utilized as precursors in a low temperature (350[degrees]C) MOCVD process to coat SiC yarn with Mo, W and Cr oxycarbides. Annealing studies performed on the MoOC and WOC coated SiC yarns in N[sub 2] to 1,000[degrees]C establish that further decomposition of the oxycarbides occurred, culminating in the formation of the metals. These metals were then found to react with Si to form Mo and W disilicide coatings. In the Cr system, heating in N[sub 2] above 800[degrees]C resulted in the formation of a mixture of carbides and oxides. Convention CVD was also employed to coat SiC and carbon yarn with C, Bn and a new interface designated BC (a carbon-boron alloy). The coated tows were then infiltrated with SiC, TiO[sub 2], SiO[sub 2] and B[sub 4]C by a chemical vapor infiltration process. The B-C coatings were found to provide advantageous interfacial properties over carbon and BN coatings in several different composite systems. The effectiveness of these different coatings to act as a chemically inert barrier layer and their relationship to the degree of interfacial debonding on the mechanical properties of the composites were examined. The effects of thermal stability and strength of the coated fibers and composites were also determined for several difference atmospheres. In addition, a new method for determining the tensile strength of the as-received and coated yarns was also developed. The coated fibers and composites were further characterized by AES, SEM, XPS, IR and X-ray diffraction analysis.

  10. Physically vapor deposited coatings on tools: performance and wear phenomena

    International Nuclear Information System (INIS)

    Koenig, W.; Fritsch, R.; Kammermeier, D.

    1991-01-01

    Coatings produced by physical vapor deposition (PVD) enhance the performance of tools for a broad variety of production processes. In addition to TiN, nowadays (Ti,Al)N and Ti(C,N) coated tools are available. This gives the opportunity to compare the performance of different coatings under identical machining conditions and to evaluate causes and phenomena of wear. TiN, (Ti,Al)N and Ti(C,N) coatings on high speed steel (HSS) show different performances in milling and turning of heat treated steel. The thermal and frictional properties of the coating materials affect the structure, the thickness and the flow of the chips, the contact area on the rake face and the tool life. Model tests show the influence of internal cooling and the thermal conductivity of coated HSS inserts. TiN and (Ti,Zr)N PVD coatings on cemented carbides were examined in interrupted turning and in milling of heat treated steel. Experimental results show a significant influence of typical time-temperature cycles of PVD and chemical vapor deposition (CVD) coating processes on the physical data and on the performance of the substrates. PVD coatings increase tool life, especially towards lower cutting speeds into ranges which cannot be applied with CVD coatings. The reason for this is the superior toughness of the PVD coated carbide. The combination of tough, micrograin carbide and PVD coating even enables broaching of case hardened sliding gears at a cutting speed of 66 m min -1 . (orig.)

  11. Coating of ceramic powders by chemical vapor deposition techniques (CVD)

    International Nuclear Information System (INIS)

    Haubner, R.; Lux, B.

    1997-01-01

    New ceramic materials with selected advanced properties can be designed by coating of ceramic powders prior to sintering. By variation of the core and coating material a large number of various powders and ceramic materials can be produced. Powders which react with the binder phase during sintering can be coated with stable materials. Thermal expansion of the ceramic materials can be adjusted by varying the coating thickness (ratio core/layer). Electrical and wear resistant properties can be optimized for electrical contacts. A fluidized bed reactor will be designed which allow the deposition of various coatings on ceramic powders. (author)

  12. Electrophoretic deposition of sol-gel-derived ceramic coatings

    International Nuclear Information System (INIS)

    Zhang, Y.; Crooks, R.M.

    1992-01-01

    In this paper the physical, optical, and chemical characteristics of electrophoretically and dip-coated sol-gel ceramic films are compared. The results indicate that electrophoresis may allow a higher level of control over the chemistry and structure of ceramic coatings than dip-coating techniques. For example, controlled-thickness sol-gel coatings can be prepared by adjusting the deposition time or voltage. Additionally, electrophoretic coatings can be prepared in a four-component alumino-borosilicate sol display interesting optical characteristics. For example, the ellipsometrically-measured refractive indices of electrophoretic coatings are higher than the refractive indices of dip-coated films cast from identical sols, and they are also higher than any of the individual sol components. This result suggests that there are physical and/or chemical differences between films prepared by dip-coating and electrophoresis

  13. Boron carbide (B4C) coating. Deposition and testing

    Science.gov (United States)

    Azizov, E.; Barsuk, V.; Begrambekov, L.; Buzhinsky, O.; Evsin, A.; Gordeev, A.; Grunin, A.; Klimov, N.; Kurnaev, V.; Mazul, I.; Otroshchenko, V.; Putric, A.; Sadovskiy, Ya.; Shigin, P.; Vergazov, S.; Zakharov, A.

    2015-08-01

    Boron carbide was proposed as a material of in-situ protecting coating for tungsten tiles of ITER divertor. To prove this concept the project including investigation of regimes of plasma deposition of B4C coating on tungsten and tests of boron carbide layer in ITER-like is started recently. The paper contends the first results of the project. The results of B4C coating irradiation by the plasma pulses of QSPU-T plasma accelerator are presented. The new device capable of B4C film deposition on tungsten and testing of the films and materials with ITER-like heat loads and ion- and electron irradiation is described. The results of B4C coating deposition and testing of both tungsten substrate and coating are shown and discussed.

  14. Effect of La2O3 addition on interface chemistry between 4YSZ top layer and Ni based alloy bond coat in thermal barrier coating by EB PVD.

    Science.gov (United States)

    Park, Chan-Young; Yang, Young-Hwan; Kim, Seong-Won; Lee, Sung-Min; Kim, Hyung-Tae; Jang, Byung-Koog; Lim, Dae-Soon; Oh, Yoon-Suk

    2014-11-01

    The effect of a 5 mol% La2O3 addition on the forming behavior and compositional variation at interface between a 4 mol% Yttria (Y2O3) stabilized ZrO2 (4YSZ) top coat and bond coat (NiCrAlY) as a thermal barrier coating (TBC) has been investigated. Top coats were deposited by electron beam physical vapor deposition (EB PVD) onto a super alloy (Ni-Cr-Co-Al) substrate without pre-oxidation of the bond coat. Top coats are found to consist of dense columnar grains with a thin interdiffusion layer between metallic bond coats. In the as-received 4YSZ coating, a thin interdiffusion zone at the interface between the top and bond coats was found to consist of a Ni-Zr intermetallic compound with a reduced quantity of Y, Al or O elements. On the other hand, in the case of an interdiffusion area of 5 mol% La2O3-added 4YSZ coating, it was found that the complicated composition and structure with La-added YSZ and Ni-Al rich compounds separately. The thermal conductivity of 5 mol% La2O3-added 4YSZ coating (- 1.6 W/m x k at 1100 degrees C) was lower than a 4YSZ coating (- 3.2 W/m x k at 1100 degrees C) alone.

  15. Thermal Conductivity Analysis and Lifetime Testing of Suspension Plasma-Sprayed Thermal Barrier Coatings

    Directory of Open Access Journals (Sweden)

    Nicholas Curry

    2014-08-01

    Full Text Available Suspension plasma spraying (SPS has become an interesting method for the production of thermal barrier coatings for gas turbine components. The development of the SPS process has led to structures with segmented vertical cracks or column-like structures that can imitate strain-tolerant air plasma spraying (APS or electron beam physical vapor deposition (EB-PVD coatings. Additionally, SPS coatings can have lower thermal conductivity than EB-PVD coatings, while also being easier to produce. The combination of similar or improved properties with a potential for lower production costs makes SPS of great interest to the gas turbine industry. This study compares a number of SPS thermal barrier coatings (TBCs with vertical cracks or column-like structures with the reference of segmented APS coatings. The primary focus has been on lifetime testing of these new coating systems. Samples were tested in thermo-cyclic fatigue at temperatures of 1100 °C for 1 h cycles. Additional testing was performed to assess thermal shock performance and erosion resistance. Thermal conductivity was also assessed for samples in their as-sprayed state, and the microstructures were investigated using SEM.

  16. Microstructure of WC/C coatings deposited on steel substrates

    NARCIS (Netherlands)

    de Hosson, J.T.M.; Carvalho, N.J.M.; Brebbia, CA

    2001-01-01

    Electron microscopy, including scanning (SEM), transmission (TEM) and high-resolution (HRTEM) were employed to characterise slightly different tungsten carbide/carbon coatings deposited onto steel substrates. Complementary techniques, such as X-ray diffraction (XRD), Auger electron spectroscopy

  17. Thermal Barrier Coatings (les Revetements anti-mur de chaleur)

    Science.gov (United States)

    1998-04-01

    a pyrometer at the coating surface and by means of thermocouples at the backside of the substrate. Substrates have been 2mm thick flat plates of...Temperature measurements are performed using a pyrometer at the TBC surface and thermocouples on the substrate. Specimen geometry is a flat plate of...Materials ( FGM ) concept for a TBC system can be suggested. 2. Graded Thermal Barrier Coating Systems Graded materials are characterized by a one or more

  18. Analytical Modeling of Unsteady Aluminum Depletion in Thermal Barrier Coatings

    OpenAIRE

    YEŞİLATA, Bülent

    2014-01-01

    The oxidation behavior of thermal barrier coatings (TBCs) in aircraft turbines is studied. A simple, unsteady and one-dimensional, diffusion model based on aluminum depletion from a bond-coat to form an oxide layer of Al2O3 is introduced. The model is employed for a case study with currently available experimental data. The diffusion coefficient of the depleted aluminum in the alloy, the concentration profiles at different oxidation times, and the thickness of Al-depleted region are...

  19. A review of the erosion of thermal barrier coatings

    International Nuclear Information System (INIS)

    Wellman, R G; Nicholls, J R

    2007-01-01

    The application of thermal barrier coatings (TBCs) to components with internal cooling in the hot gas stream of gas turbine engines has facilitated a steep increase in the turbine entry temperature and the associated increase in performance and efficiency of gas turbine engines. However, TBCs are susceptible to various life limiting issues associated with their operating environment including erosion, corrosion, oxidation, sintering and foreign object damage (FOD). This is a review paper that examines various degradation and erosion mechanisms of TBCs, especially those produced by electron beam physical vapour deposition (EB-PVD). The results from a number of laboratory tests under various impact conditions are discussed before the different erosion and FOD mechanisms are reviewed. The transitions between the various erosion mechanisms are discussed in terms of the D/d ratio (contact area diameter/column diameter), a relatively new concept that relates the impact size to the erosion mechanism. The effects of ageing, dopant additions and calcium-magnesium-alumina-silicates on the life of TBCs are examined. It is shown that while ageing increases the erosion rate of EB-PVD TBCs, ageing of plasma sprayed TBCs in fact lowers the erosion rate. Finally modelling of EB-PVD TBCs is briefly introduced. (topical review)

  20. Stress controlled gas-barrier oxide coatings on semi-crystalline polymers

    International Nuclear Information System (INIS)

    Rochat, G.; Leterrier, Y.; Fayet, P.; Manson, J.-A.E.

    2005-01-01

    Thin silicon oxide (SiO x ) barrier coatings formed by plasma enhanced chemical vapor deposition on poly(ethylene terephthalate) (PET) substrates were subjected to post-deposition annealing treatments in the temperature range for orientation relaxation of the polymer. The resulting change in coating internal stress state was measured by means of thermo-mechanical analyses, and its effect on the coating cohesive properties and coating/polymer adhesion was determined from the analysis of uniaxial fragmentation tests in situ in a scanning electron microscope, assuming a Weibull-type probability of failure and a perfectly plastic stress transfer at the SiO x /PET interface. The strain to failure and intrinsic fracture toughness of the ultrathin oxide coating were found to be as high as 5.7% and 10 J/m 2 , respectively, and its interfacial shear strength with PET was found to be close to 100 MPa. Annealing for 10 min at 150 deg. C did not modify the oxygen permeation properties of the SiO x /PET film, which suggests that the defect population of the oxide was not affected by the thermal treatment. In contrast, the coating internal compressive stress resulting from annealing was shown to increase by 40% the apparent coating cohesive properties and adhesion to the polymer

  1. Electrolytic deposition and corrosion resistance of Zn–Ni coatings ...

    Indian Academy of Sciences (India)

    Administrator

    are meas- ured, and are compared with that of metallic cadmium coating. Structural investigations were performed by the X-ray diffraction (XRD) method. The surface morphology and chemical composition of deposited coatings were studied using a scanning electron microscope (JEOL JSM-6480) with EDS attachment.

  2. Chemical vapor deposition: A technique for applying protective coatings

    Energy Technology Data Exchange (ETDEWEB)

    Wallace, T.C. Sr.; Bowman, M.G.

    1979-01-01

    Chemical vapor deposition is discussed as a technique for applying coatings for materials protection in energy systems. The fundamentals of the process are emphasized in order to establish a basis for understanding the relative advantages and limitations of the technique. Several examples of the successful application of CVD coating are described. 31 refs., and 18 figs.

  3. Corrosion resistance of tungsten carbide based cermet coatings deposited by High Velocity Oxy-Fuel spray process

    Energy Technology Data Exchange (ETDEWEB)

    Aw, Poh Koon [Singapore Institute of Manufacturing Technology (Singapore)], E-mail: pkaw@SIMTech.a-star.edu.sg; Tan, Annie Lai Kuan [Singapore Institute of Manufacturing Technology (Singapore); Tan, Tai Phong [Hamilton Sundstrand Pacific Aerospace Pte Ltd (Singapore); Qiu, Jianhai [School of Materials Science and Engineering, Nanyang Technological University (Singapore)

    2008-06-30

    WC-17Ni and WC-17Co coatings were deposited on mild steel and stainless steel substrates by High Velocity Oxy-Fuel (HVOF) spray process. WC-17Ni and WC-17Co coatings were obtained by the spray process and the porosity of these coatings was measured. Polarization and electrochemical impedance spectroscopy (EIS) were performed on both uncoated substrates and coated samples immersed in 3% NaCl solution. WC-17Ni coating with a lower porosity, serve as a better barrier and effectively prevented corrosion attack when it was deposited on mild steel substrate. The nickel binder in the WC-17Ni coating was found to have a better corrosion resistance than the cobalt binder in the WC-17Co coating.

  4. Oxidation and fatigue behaviour of {gamma}-TiAl coated with HIPIMS CrAlYN/CrN nanoscale multilayer coatings and EB-PVD thermal barrier coatings

    Energy Technology Data Exchange (ETDEWEB)

    Braun, Reinhold; Schulz, Uwe [DLR - German Aerospace Center, Koeln (Germany). Inst. of Materials Research; Leyens, Christoph [DLR - German Aerospace Center, Koeln (Germany). Inst. of Materials Research; Technische Univ. Dresden (Germany). Inst. of Materials Science; Hovsepian, Papken E.; Ehiasarian, Arutiun P. [Sheffield Hallam Univ. (United Kingdom). Nanotechnology Centre for PVD Research

    2010-05-15

    CrAlYN/CrN nanoscale multilayer coatings were deposited on {gamma}-TiAl substrate material using high power impulse magnetron sputtering technology. The nitride coating provided effective oxidation protection to {gamma}-TiAl at 850 C for exposure time periods exceeding 2000 cycles of 1 h dwell time at high temperature in air. High oxidation resistance was also observed at 900 C. After exposure to air at 850 C for 300 h, coated tension specimens exhibited a reduction in fatigue strength of about 70 MPa compared to the bare {gamma}-TiAl alloy. Zirconia topcoats produced by electron-beam physical vapour deposition were well adherent to the CrAlYN/CrN coating with an oxy-nitride overcoat. When thermally cycled at 900 C, the lifetime of this thermal barrier coating system on {gamma}-TiAl exceeded 1000 1 h cycles. Below cracks in the nitride coating, the substrate was oxidised and protrusions of an outer oxide scale with columnar structure formed. (orig.)

  5. EB-PVD process management for highly productive zirconia thermal barrier coating of turbine blades

    International Nuclear Information System (INIS)

    Reinhold, E.; Botzler, P.; Deus, C.

    1999-01-01

    Zirconia thermal barrier coatings are well used in the turbine manufacturing industry because they ensure extended lifetimes of turbine blades. Compared with other techniques, EB-PVD processes are best suited for the deposition on turbine blades with regard to the layer properties. Therefore EB-PVD coaters for turbine blades are becoming increasingly interesting. The coating costs per component are mainly dependent on a highly productive solution for the deposition task. Thus the EB-PVD process management has to be optimized in order to meet the productivity requirements of the manufacturers. This includes the requirement of high deposition rates, large deposition areas, long time stable production cycles as well as a matched duration of preheating, deposition and cooling down per charge. Modern EB-PVD solutions to be introduced allow deposition rates on blades up to 7 μm/min. The consequences for the technological process management and plant design concerning long time stable coating cycles with high productivity will be discussed. (orig.)

  6. Advanced thermal barrier coatings for operation in high hydrogen content fueled gas turbines.

    Energy Technology Data Exchange (ETDEWEB)

    Sampath, Sanjay [Stony Brook Univ., NY (United States)

    2015-04-02

    and resulted in improved TBC lifetimes. Processing based approaches of identifying optimal processing regimes deploying advanced in-situ coating property measurements and in-flight diagnostic tools were used to develop process maps for bond coats. Having established a framework for the bond coat processing using the HVOF process, effort were channeled towards fabrication of APS and VPS bond coats with the same material composition. Comparative evaluation of the three deposition processes with regard to their microstrcuture , surface profiles and TBC performance were carried out and provided valuable insights into factors that require concurrent consideration for the development of bond coats for advanced TBC systems. Over the course of this program several advancements were made on the development of durable thermal barrier coatings. Process optimization techniques were utilized to identify processing regimes for both conventional YSZ as well as other TBC compositions such as Gadolinium Zirconate and other Co-doped materials. Measurement of critical properties for these formed the initial stages of the program to identify potential challenges in their implementation as part of a TBC system. High temperature thermal conductivity measurements as well as sintering behavior of both YSZ and GDZ coatings were evaluated as part of initial efforts to undersand the influence of processing on coating properties. By effectively linking fundamental coating properties of fracture toughness and elastic modulus to the cyclic performance of coatings, a durability strategy for APS YSZ coatings was developed. In order to meet the goals of fabricating a multimaterial TBC system further research was carried out on the development of a gradient thermal conductivity model and the evaluation of sintering behavior of multimaterial coatings. Layer optimization for desired properties in the multimaterial TBC was achieved by an iterative feedback approach utilizing process maps and in-situ and

  7. Structure And Properties Of PVD Coatings Deposited On Cermets

    Directory of Open Access Journals (Sweden)

    Żukowska L.

    2015-06-01

    Full Text Available The main aim of the research is the investigation of the structure and properties of single-layer and gradient coatings of the type (Ti,AlN and Ti(C,N deposited by physical vapour deposition technology (PVD on the cermets substrate.

  8. Electrochemical deposition of Ni–TiN nanocomposite coatings and ...

    Indian Academy of Sciences (India)

    The effects of deposition current density, electrolyte agitation speed and the number of particles in the solution on the amount of incorporated particles in the coating process were investigated. The optimum deposition current density of 4 A dm − 2 and agitation speed of 450 rpm were obtained. The effect of sodium dodecyl ...

  9. Electrochemical deposition of mineralized BSA/collagen coating.

    Science.gov (United States)

    Zhuang, Junjun; Lin, Jun; Li, Juan; Wang, Huiming; Cheng, Kui; Weng, Wenjian

    2016-09-01

    In this work, mineralized collagen coatings with different loading quantity of bovine serum albumin (BSA) were prepared via in situ electrochemical deposition on titanium substrate. The microstructure and BSA loading quantity of the coatings could be controlled by the electrochemical deposition parameters, such as deposition potential, BSA concentration and its adding sequence in the electrolyte. The BSA loading quantity in the coatings was obtained in the range of 0.0170-0.173mg/cm(2), enhancing the cell adhesion and proliferation of the coatings with the simultaneous release. The distinct release behaviors of BSA were attributed to their gradient distribution with different mineralization degrees, which could be adjusted by the deposition process. These results suggest that in situ electrochemical deposition is a promising way to incorporate functional molecules into the mineralized collagen coatings and the mineralized BSA/collagen coatings are highly promising for improving the rhBMP-2 loading capability (1.8-fold). Copyright © 2016 Elsevier B.V. All rights reserved.

  10. Effect of thermal cycling on ZrO2-Y2O3 thermal barrier coatings

    Science.gov (United States)

    Mcdonald, G.; Hendricks, R. C.

    1980-01-01

    The paper studies the comparative life of plasma-sprayed ZrO2-Y2O3 thermal barrier coatings on NiCrAlY bond coats on Rene 41 in short (4 min) and long (57 min) thermal cycles at 1040 C in a 0.3-Mach flame. Attention is given to determining the effect of short- and long-duration cycles on ZrO2-Y2O3 coatings, the cause of any cycle frequency effects, and methods to improve tolerance to thermal stress. Short cycles greatly reduced the life of the ceramic coating in terms of time at temperatures as compared to longer cycles, the failed coating indicating compressive failure. The experiments and stress calculations show that repeatedly subjecting a ceramic coating to high rates of initial heating has a more destructive influence on the coating than sustained operation at temperature. The effect of such thermal compressive stresses might be minimized through coating deposition and thickness control and by turbine cycle measurement to keep starting heating rates below critical values.

  11. Simulation of thermo-Elastics Properties of Thermal Barrier Coatings ...

    African Journals Online (AJOL)

    Thermal barrier coatings are used to protect different parts in compressors and turbines from heat. They are generally composed of two layers, one metallic layer providing resistance to heat corrosion and oxidation, and one thermally insulating ceramic layer. Two different techniques are industrially used. Plasma spray ...

  12. Environmental Barrier Coatings for the Energy Efficient Heat Engines Program

    Energy Technology Data Exchange (ETDEWEB)

    Katherine Faber

    2004-10-31

    This program aimed to develop a fundamental understanding of the microstructural, mechanical, and chemical properties of Ta{sub 2}O{sub 5}-based coatings for Si{sub 3}N{sub 4} (AS800) substrates and optimize such coatings for environmental barriers. The program consisted of three tasks: processing of Ta{sub 2}O{sub 5} coatings, phase and microstructural development, and life-limiting phenomena. Northwestern University formed a cross-functional team with Lehigh University, Honeywell Inc., and Oak Ridge National Laboratory. The major accomplishments are: (1) Conditions for the plasma spray of Ta{sub 2}O{sub 5} and its alloys were optimized to provide maximum density and thickness. (2) Adherent small particle plasma spray coatings of Ta{sub 2}O{sub 5} can be routinely prepared. (3) Ta{sub 2}O{sub 5} can be stabilized against its disruptive phase transformation to 1400 C by the addition of one or more oxides of Al, La, and/or Nb. (4) Residual stresses in the Ta{sub 2}O{sub 5} coatings were measured using X-rays and changed with thermal exposure. (5) Properly doped coatings are more resistant against thermal cycling than undoped coatings, and can be cycled many thousand times without spallation. (6) Water vapor testing in the ORNL Keiser Rig of adherent coatings showed that undoped Ta{sub 2}O{sub 5} is not an effective barrier at preventing chemical changes to the AS800. (7) Limited water vapor testing of doped and adherent coatings, which had successfully survived many thermal cycles, showed that in the water vapor environment, de-cohesion may occur.

  13. Modified drug release using atmospheric pressure plasma deposited siloxane coatings

    International Nuclear Information System (INIS)

    Dowling, D P; Law, V J; Ardhaoui, M; Stallard, C; Maher, S; Keenan, A

    2016-01-01

    This pilot study evaluates the potential of atmospheric plasma polymerised coatings to modify the rate of drug release from polymeric substrates. The antibiotic rifampicin was deposited in a prototype multi-layer drug delivery system, consisting of a nebulized layer of active drug between a base layer of TEOS deposited on a plastic substrate (polystyrene) and an overlying layer of plasma polymerised PDMS. The polymerised TEOS and PDMS layers were deposited using a helium atmospheric plasma jet system. Elution of rifampicin was measured using UV–VIS spectroscopy, in addition to a antimicrobial well diffusion assay with an established indicator organism. The multi-layered plasma deposited coatings significantly extended the duration of release of the rifampicin from 24 h for the uncoated polymer to 144 h for the coated polymer. (paper)

  14. Chemically vapor deposited coatings for multibarrier containment of nuclear wastes

    International Nuclear Information System (INIS)

    Rusin, J.M.; Shade, J.W.; Kidd, R.W.; Browning, M.F.

    1981-01-01

    Chemical vapor deposition (CVD) was selected as a feasible method to coat ceramic cores, since the technology has previously been demonstrated for high-temperature gas-cooled reactor (HTGR) fuel particles. CVD coatings, including SiC, PyC (pyrolytic carbon), SiO 2 , and Al 2 O 3 were studied. This paper will discuss the development and characterization of PyC and Al 2 O 3 CVD coatings on supercalcine cores. Coatings were applied to 2 mm particles in either fluidized or vibrating beds. The PyC coating was deposited in a fluidized bed with ZrO 2 diluent from C 2 H 2 at temperatures between 1100 and 1200 0 C. The Al 2 O 3 coatings were deposited in a vibrated bed by a two-stage process to minimize loss of PyC during the overcoating operation. This process involved applying 10 μm of Al 2 O 3 using water vapor hydrolysis of AlCl 3 and then switching to the more surface-controlled hydrolysis via the H 2 + CO 2 reaction (3CO 2 + 3H 2 + 2AlCl 3 = Al 2 O 3 + 6HCl + 3CO). Typically, 50 to 80 μm Al 2 O 3 coatings were applied over 30 to 40 μm PyC coatings. The coatings were evaluated by metallographic examination, PyC oxidation tests, and leach resistance. After air oxidation for 100 hours at 750 0 C, the duplex PyC/Al 2 O 3 coated particles exhibited a weight loss of 0.01 percent. Leach resistance is being determined for temperatures from 50 to 150 0 C in various solutions. Typical results are given for selected ions. The leach resistance of supercalcine cores is significantly improved by the application of PyC and/or Al 2 O 3 coatings

  15. Microstructure Evolution and Durability of Advanced Environmental Barrier Coating Systems for SiC/SiC Ceramic Matrix Composites

    Science.gov (United States)

    Zhu, Dongming; Evans, Laura J.; McCue, Terry R.; Harder, Bryan

    2016-01-01

    Environmental barrier coated SiC-SiC ceramic matrix composites (CMCs) systems will play a crucial role in next generation turbine engines for hot-section component applications because of their ability to significantly increase engine operating temperatures with improved efficiency, reduce engine weight and cooling requirements. Advanced HfO2 and rare earth silicate environmental barrier coatings (EBCs), along with multicomponent hafnium and rare earth silicide EBC bond coats have been developed. The coating degradation mechanisms in the laboratory simulated engine thermal cycling, and fatigue-creep operating environments are also being investigated. This paper will focus on the microstructural and compositional evolutions of an advanced environmental barrier coating system on a SiC-SiC CMC substrate during the high temperature simulated durability tests, by using a Field Emission Gun Scanning Electron Microscopy, Energy Dispersive Spectroscopy (EDS) and Wavelength Dispersive Spectroscopy (WDS). The effects of Calcium-Magnesium-Alumino-Silicate (CMAS) from road sand or volcano-ash deposits on the degradation mechanisms of the environmental barrier coating systems will also be discussed. The detailed analysis results help understand the EBC-CMC system performance, aiming at the durability improvements to achieve more robust, prime-reliant environmental barrier coatings.

  16. Thermal Conductivity of EB-PVD Thermal Barrier Coatings Evaluated by a Steady-State Laser Heat Flux Technique

    Science.gov (United States)

    Zhu, Dongming; Miller, Robert A.; Nagaraj, Ben A.; Bruce, Robert W.

    2000-01-01

    The thermal conductivity of electron beam-physical vapor deposited (EB-PVD) Zr02-8wt%Y2O3 thermal barrier coatings was determined by a steady-state heat flux laser technique. Thermal conductivity change kinetics of the EB-PVD ceramic coatings were also obtained in real time, at high temperatures, under the laser high heat flux, long term test conditions. The thermal conductivity increase due to micro-pore sintering and the decrease due to coating micro-delaminations in the EB-PVD coatings were evaluated for grooved and non-grooved EB-PVD coating systems under isothermal and thermal cycling conditions. The coating failure modes under the high heat flux test conditions were also investigated. The test technique provides a viable means for obtaining coating thermal conductivity data for use in design, development, and life prediction for engine applications.

  17. Thermochemical compatibility of ytterbia–(hafnia/silica) multilayers for environmental barrier coatings

    International Nuclear Information System (INIS)

    Poerschke, D.L.; Van Sluytman, J.S.; Wong, K.B.; Levi, C.G.

    2013-01-01

    Environmental barrier coating (EBC) systems consisting of multiple layers tailored to address individual protection needs may offer improved performance relative to conventional architectures. If the requirements of thermochemical and thermomechanical compatibility are met, the deposition of a segmented thermal barrier coating on a dense rare earth silicate EBC could provide additional thermal protection and resistance to attack by molten deposits. The thermochemical compatibility between silicates in the YbO 1.5 –SiO 2 system and phases in the YbO 1.5 –HfO 2 system was investigated by equilibrating powder compacts of selected ternary compositions; diffusion couples were used to simulate interactions at the layer interfaces in the proposed architectures. The deduced 1500 °C ternary isothermal section reveals that the ordered δ-Yb 4 Hf 3 O 12 and H 3 –Yb 6 HfO 11 phases are only compatible with ytterbium monosilicate (Yb 2 SiO 5 ) EBC. Implementation of these hafnates in contact with ytterbium disilicate (Yb 2 Si 2 O 7 ) leads to interfacial reactions that facilitate layer debonding. The results provide criteria to guide the design of future thermal/environmental barrier coating architectures

  18. Synchrotron X-ray measurement techniques for thermal barrier coated cylindrical samples under thermal gradients.

    Science.gov (United States)

    Siddiqui, Sanna F; Knipe, Kevin; Manero, Albert; Meid, Carla; Wischek, Janine; Okasinski, John; Almer, Jonathan; Karlsson, Anette M; Bartsch, Marion; Raghavan, Seetha

    2013-08-01

    Measurement techniques to obtain accurate in situ synchrotron strain measurements of thermal barrier coating systems (TBCs) applied to hollow cylindrical specimens are presented in this work. The Electron Beam Physical Vapor Deposition coated specimens with internal cooling were designed to achieve realistic temperature gradients over the TBC coated material such as that occurring in the turbine blades of aeroengines. Effects of the circular cross section on the x-ray diffraction (XRD) measurements in the various layers, including the thermally grown oxide, are investigated using high-energy synchrotron x-rays. Multiple approaches for beam penetration including collection, tangential, and normal to the layers, along with variations in collection parameters are compared for their ability to attain high-resolution XRD data from the internal layers. This study displays the ability to monitor in situ, the response of the internal layers within the TBC, while implementing a thermal gradient across the thickness of the coated sample. The thermal setup maintained coating surface temperatures in the range of operating conditions, while monitoring the substrate cooling, for a controlled thermal gradient. Through variation in measurement location and beam parameters, sufficient intensities are obtained from the internal layers which can be used for depth resolved strain measurements. Results are used to establish the various techniques for obtaining XRD measurements through multi-layered coating systems and their outcomes will pave the way towards goals in achieving realistic in situ testing of these coatings.

  19. Initial Assessment of Environmental Barrier Coatings for the Prometheus Project

    Energy Technology Data Exchange (ETDEWEB)

    M. Frederick

    2005-12-15

    Depending upon final design and materials selections, a variety of engineering solutions may need to be considered to avoid chemical degradation of components in a notional space nuclear power plant (SNPP). Coatings are one engineered approach that was considered. A comprehensive review of protective coating technology for various space-reactor structural materials is presented, including refractory metal alloys [molybdenum (Mo), tungsten (W), rhenium (Re), tantalum (Ta), and niobium (Nb)], nickel (Ni)-base superalloys, and silicon carbide (Sic). A summary description of some common deposition techniques is included. A literature survey identified coatings based on silicides or iridium/rhenium as the primary methods for environmental protection of refractory metal alloys. Modified aluminide coatings have been identified for superalloys and multilayer ceramic coatings for protection of Sic. All reviewed research focused on protecting structural materials from extreme temperatures in highly oxidizing conditions. Thermodynamic analyses indicate that some of these coatings may not be protective in the high-temperature, impure-He environment expected in a Prometheus reactor system. Further research is proposed to determine extensibility of these coating materials to less-oxidizing or neutral environments.

  20. Deposition of selenium coatings on beryllium foils. Revision 1

    International Nuclear Information System (INIS)

    Erikson, E.D.; Tassano, P.L.; Reiss, R.H.; Griggs, G.E.

    1984-01-01

    A technique for preparing selenium films on 50.8 micrometers thick beryllium foils is described. The selenium was deposited in vacuum from a resistance heated evaporation source. A water-cooled enclosure was used to minimize contamination of the vacuum system and to reduce the exposure of personnel to toxic and obnoxious materials. Profilometry measurements of the coatings indicated selenium thicknesses of 5.5, 12.9, 37.5, 49.8 and 74.5 micrometers. The control of deposition rate and of coating thickness was facilitated using a commercially available closed-loop programmable deposition controller. The x-ray transmission of the coated substrates was measured using a tritiated zirconium source. The transmissivities of the film/substrate combination are presented for the range of energies from 4 to 20 keV

  1. New Barrier Coating Materials for PV Module Backsheets: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Barber, G. D.; Jorgensen, G. J.; Terwilliger, K.; Glick, S. H.; Pern, J.; McMahon, T. J.

    2002-05-01

    This conference paper describes the high moisture barrier high resistivity coatings on polyethylene terepthalate (PET) have been fabricated and characterized for use in PV module back sheet applications. These thin film barriers exhibit water vapor transmission rates (WVTR) as low as 0.1 g/m2-day at 37.8 C and have shown excellent adhesion (> 10 N/mm) to both ethylene vinyl acetate (EVA) and PET even after filtered xenon arc lamp UV exposure. The WVTR and adhesion values for this construction are compared to and shown to be superior to candidate polymeric backsheet materials.

  2. Collimated Magnetron Sputter Deposition for Mirror Coatings

    DEFF Research Database (Denmark)

    Vickery, A.; Cooper-Jensen, Carsten P.; Christensen, Finn Erland

    2008-01-01

    At the Danish National Space Center (DNSC), a planar magnetron sputtering chamber has been established as a research and production coating facility for curved X-ray mirrors for hard X-ray optics for astronomical X-ray telescopes. In the following, we present experimental evidence that a collimat......At the Danish National Space Center (DNSC), a planar magnetron sputtering chamber has been established as a research and production coating facility for curved X-ray mirrors for hard X-ray optics for astronomical X-ray telescopes. In the following, we present experimental evidence...... that a collimation of the sputtered particles is an efficient way to suppress the interfacial roughness of the produced multilayer. We present two different types of collimation optimized for the production of low roughness curved mirrors and flat mirrors, respectively....

  3. Influence of Bondcoat Spray Process on Lifetime of Suspension Plasma-Sprayed Thermal Barrier Coatings

    Science.gov (United States)

    Gupta, M.; Markocsan, N.; Li, X.-H.; Östergren, L.

    2018-01-01

    Development of thermal barrier coatings (TBCs) manufactured by suspension plasma spraying (SPS) is of high commercial interest as SPS has been shown capable of producing highly porous columnar microstructures similar to the conventionally used electron beam-physical vapor deposition. However, lifetime of SPS coatings needs to be improved further to be used in commercial applications. The bondcoat microstructure as well as topcoat-bondcoat interface topography affects the TBC lifetime significantly. The objective of this work was to investigate the influence of different bondcoat deposition processes for SPS topcoats. In this work, a NiCoCrAlY bondcoat deposited by high velocity air fuel (HVAF) was compared to commercial vacuum plasma-sprayed NiCoCrAlY and PtAl diffusion bondcoats. All bondcoat variations were prepared with and without grit blasting the bondcoat surface. SPS was used to deposit the topcoats on all samples using the same spray parameters. Lifetime of these samples was examined by thermal cyclic fatigue testing. Isothermal heat treatment was performed to study bondcoat oxidation over time. The effect of bondcoat deposition process and interface topography on lifetime in each case has been discussed. The results show that HVAF could be a suitable process for bondcoat deposition in SPS TBCs.

  4. Prolonging thermal barrier coated specimen life by thermal cycle management

    Science.gov (United States)

    Hendricks, R. C.; Mcdonald, G.; Poolos, N. P.

    1981-01-01

    Thermal barrier coatings applied to the heated side of engine components such as seals, combustor, and blades of a gas turbine offer a potential increase in efficiency through the use of higher gas temperatures or less cooling air or benefits arising from extended component life by reducing component metal temperatures. The considered investigation has the objective to show that while a thermal barrier coated (TBC) specimen can be brought to a fixed temperature using various fuel-air ratio (F/A) values, lower calculated stresses are associated with lower (F/A) values. This implies that control of (F/A) values (i.e., rates of heat input) during the starting transient and to a lesser extent during shutdown and operation, offers a potential method of improving TBC lifetime through thermal cycle management.

  5. Polyamic acid coating of microspheres by oriented thermal vapor deposition

    International Nuclear Information System (INIS)

    Huang Yong; Zhang Zhanwen; Liu Yiyang; Li Bo; Chen Shufen; Qi Xiaobo

    2011-01-01

    In this paper, a study on the oriented thermal vapor deposition device which is used for coating microspheres with polyamic acid (PAA) is developed. Influences of the processing of monomer material and the adjusting of heating process on the deposition rate are discussed. Two different monomers are poured into two evaporators and evaporated independently, the deposition rate and film thickness are measured via two film thickness measuring probes with the crystal vibration. Space position and symmetry of sample pan, two probes and the oriented tube tip are adjusted so that two monomers' deposition ratio approximates to stoichiometric ratio. High quality coating of PAA on poly-alpha-methylstyrene microsphere is acquired by intermittent piezoelectricity vibration or striking which accompanies rotating of the sample pan. (authors)

  6. Microwave plasma deposition of diamond like carbon coatings

    Indian Academy of Sciences (India)

    Abstract. The promising applications of the microwave plasmas have been appearing in the fields of chemical processes and semiconductor manufacturing. Applications include surface deposition of all types including diamond/diamond like carbon (DLC) coatings, etching of semiconductors, promotion of organic reactions, ...

  7. Electrolytic deposition and corrosion resistance of Zn–Ni coatings ...

    Indian Academy of Sciences (India)

    Administrator

    trochemical corrosion resistance were carried out in the 5% NaCl, using potentiodynamic and electrochemical impedance spectroscopy (EIS) methods. On the ground of these research, the possibility of deposition of Zn–. Ni coatings contained 24–26% at. Ni was exhibited. It was stated, that surface morphology, chemical ...

  8. A modelling approach to designing microstructures in thermal barrier coatings

    International Nuclear Information System (INIS)

    Gupta, M.; Nylen, P.; Wigren, J.

    2013-01-01

    Thermomechanical properties of Thermal Barrier Coatings (TBCs) are strongly influenced by coating defects, such as delaminations and pores, thus making it essential to have a fundamental understanding of microstructure-property relationships in TBCs to produce a desired coating. Object-Oriented Finite element analysis (OOF) has been shown previously as an effective tool for evaluating thermal and mechanical material behaviour, as this method is capable of incorporating the inherent material microstructure as input to the model. In this work, OOF was used to predict the thermal conductivity and effective Young's modulus of TBC topcoats. A Design of Experiments (DoE) was conducted by varying selected parameters for spraying Yttria-Stabilised Zirconia (YSZ) topcoat. The microstructure was assessed with SEM, and image analysis was used to characterize the porosity content. The relationships between microstructural features and properties predicted by modelling are discussed. The microstructural features having the most beneficial effect on properties were sprayed with a different spray gun so as to verify the results obtained from modelling. Characterisation of the coatings included microstructure evaluation, thermal conductivity and lifetime measurements. The modelling approach in combination with experiments undertaken in this study was shown to be an effective way to achieve coatings with optimised thermo-mechanical properties.

  9. Low Conductive Thermal Barrier Coatings Produced by Ion Beam Assisted EB-PVD with Controlled Porosity, Microstructure Refinement and Alloying Additions for High Temperature Applications

    Science.gov (United States)

    Wolfe, Douglas E.; Singh, Jogender

    2005-01-01

    Various advanced Hafnia-based thermal barrier coatings (TBC) were applied on nickel-based superalloy coupons by electron beam physical vapor deposition. In addition, microstructural modifications to the coating material were made in an effort to reduce the thermal conductivity of the coating materials. Various processing parameters and coating system modifications were made in order to deposit the alloyed TBC with the desired microstructure and thus coating performance, some of which include applying coatings at substrate temperatures of 1150 C on both PtAl and CoNiCrAlY bond coated samples, as well as using 8YSZ as a bond layer. In addition, various characterization techniques including thermal cyclic tests, scanning electron microscopy, x-ray diffraction, thermal conductivity, and reflectivity measurements were performed. Although the coating microstructure was never fully optimized due to funding being cut short, significant reductions in thermal conductivity were accomplished through both chemistry changes (composition) and microstructural modifications.

  10. Advanced Environmental Barrier Coating Development for SiC-SiC Ceramic Matrix Composite Components

    Science.gov (United States)

    Zhu, Dongming; Harder, Bryan; Hurst, Janet B.; Halbig, Michael Charles; Puleo, Bernadette J.; Costa, Gustavo; Mccue, Terry R.

    2017-01-01

    This presentation reviews the NASA advanced environmental barrier coating (EBC) system development for SiC-SiC Ceramic Matrix Composite (CMC) combustors particularly under the NASA Environmentally Responsible Aviation, Fundamental Aeronautics and Transformative Aeronautics Concepts Programs. The emphases have been placed on the current design challenges of the 2700-3000F capable environmental barrier coatings for low NOX emission combustors for next generation turbine engines by using advanced plasma spray based processes, and the coating processing and integration with SiC-SiC CMCs and component systems. The developments also have included candidate coating composition system designs, degradation mechanisms, performance evaluation and down-selects; the processing optimizations using TriplexPro Air Plasma Spray Low Pressure Plasma Spray (LPPS), Plasma Spray Physical Vapor Deposition and demonstration of EBC-CMC systems. This presentation also highlights the EBC-CMC system temperature capability and durability improvements under the NASA development programs, as demonstrated in the simulated engine high heat flux, combustion environments, in conjunction with high heat flux, mechanical creep and fatigue loading testing conditions.

  11. FeS-coated sand for removal of arsenic(III) under anaerobic conditions in permeable reactive barriers

    Science.gov (United States)

    Han, Y.-S.; Gallegos, T.J.; Demond, A.H.; Hayes, K.F.

    2011-01-01

    Iron sulfide (as mackinawite, FeS) has shown considerable promise as a material for the removal of As(III) under anoxic conditions. However, as a nanoparticulate material, synthetic FeS is not suitable for use in conventional permeable reactive barriers (PRBs). This study developed a methodology for coating a natural silica sand to produce a material of an appropriate diameter for a PRB. Aging time, pH, rinse time, and volume ratios were varied, with a maximum coating of 4.0 mg FeS/g sand achieved using a pH 5.5 solution at a 1:4 volume ratio (sand: 2 g/L FeS suspension), three days of aging and no rinsing. Comparing the mass deposited on the sand, which had a natural iron-oxide coating, with and without chemical washing showed that the iron-oxide coating was essential to the formation of a stable FeS coating. Scanning electron microscopy images of the FeS-coated sand showed a patchwise FeS surface coating. X-ray photoelectron spectroscopy showed a partial oxidation of the Fe(II) to Fe(III) during the coating process, and some oxidation of S to polysulfides. Removal of As(III) by FeS-coated sand was 30% of that by nanoparticulate FeS at pH 5 and 7. At pH 9, the relative removal was 400%, perhaps due to the natural oxide coating of the sand or a secondary mineral phase from mackinawite oxidation. Although many studies have investigated the coating of sands with iron oxides, little prior work reports coating with iron sulfides. The results suggest that a suitable PRB material for the removal of As(III) under anoxic conditions can be produced through the deposition of a coating of FeS onto natural silica sand with an iron-oxide coating. ?? 2010 Elsevier Ltd.

  12. Multilayer Optical Coating Fabrication By Ion Beam Sputter Deposition

    Science.gov (United States)

    Becker, Juergen; Scheuer, Volker

    1989-02-01

    Ion Beam Sputter Deposition (IBSD) was proven to be a useful technique for producing high performance optical coatings. However, compared to other deposition techniques, several problems remain to be solved, such as low deposition rates, small areas with homogeneous deposition rate and the problem of contamination. In the work described here, a cubic vacuum chamber has been equipped with a commercially available ion beam source, a triple stage target holder and a rotating substrate holder. The primary interest was to get a reasonable deposition rate over a sufficiently large area. Single layers of SiO2, Ta205 and TiO2 and multilayers of Si02/Ta205 were produced. Contaminants in the films were analyzed by various techniques mainly by Total-Reflection X-ray Fluorescence (TXRF). Optical properties of the coatings were investigated to study the influence of the contaminants on the performance of the optical coatings. The optical properties were characterized by the refractive index, the absorption coefficient and the scattering behaviour. Scattering losses were measured by means of Total Integrated Scattering (TIS) and Angle Resolved Scattering (ARS). The damage threshold against high-power laser pulses of 1.06 pm was determined.

  13. Simulation of the optical coating deposition

    Science.gov (United States)

    Grigoriev, Fedor; Sulimov, Vladimir; Tikhonravov, Alexander

    2018-04-01

    A brief review of the mathematical methods of thin-film growth simulation and results of their applications is presented. Both full-atomistic and multi-scale approaches that were used in the studies of thin-film deposition are considered. The results of the structural parameter simulation including density profiles, roughness, porosity, point defect concentration, and others are discussed. The application of the quantum level methods to the simulation of the thin-film electronic and optical properties is considered. Special attention is paid to the simulation of the silicon dioxide thin films.

  14. Tantalum oxide-based plasma-sprayed environmental barrier coatings

    Science.gov (United States)

    Weyant, Christopher M.

    Energy efficiency in gas turbine engines is linked to the high temperature capabilities of materials used in the hot section of the engine. To facilitate a significant increase in engine efficiency, tough structural ceramics have been developed that can handle the thermo-mechanical stresses that gas turbine components experience. Unfortunately, the high-temperature, high-pressure, and high-velocity combustion gases in a gas turbine contain water vapor and/or hydrogen which have been shown to volatilize the protective silica layer on silicon-based ceramics. This degradation leads to significant surface recession in ceramic gas turbine components. In order to maintain their structural integrity, an environmental barrier coating (EBC) could be used to protect ceramics from the harsh gas turbine environment. Due to its coefficient of thermal expansion and phase stability at elevated temperatures, tantalum oxide (Ta2O5) was examined as the base material for an air plasma-sprayed EBC on Si3N 4 ceramics. As-sprayed pure Ta2O5 was comprised of both low-temperature beta-Ta2O5 and high-temperature alpha-Ta 2O5 that was quenched into the structure. Residual stress measurements via X-ray diffraction determined the as-sprayed coating to be in tension and extensive vertical macrocracks were observed in the coating. Heat treatments of the pure coating led to conversion of alpha-Ta2 O5 to beta-Ta2O5, conversion of tensile stresses to compressive, localized buckling of the coating, and significant grain growth which caused microcracking in the coating. The pure coating was found to be an inadequate EBC. Al2O3 was investigated as a solid solution alloying addition designed to enhance the stability of beta-Ta2O 5, and reduce grain growth by slowing grain boundary diffusion. La 2O3 was investigated as an alloying addition designed to form second phase particles which would reduce grain growth through pinning. Al2O3 was successful at both stabilizing beta-Ta 2O5 and reducing grain

  15. Deposition of antimicrobial coatings on microstereolithography-fabricated microneedles

    Science.gov (United States)

    Gittard, Shaun D.; Miller, Philip R.; Jin, Chunming; Martin, Timothy N.; Boehm, Ryan D.; Chisholm, Bret J.; Stafslien, Shane J.; Daniels, Justin W.; Cilz, Nicholas; Monteiro-Riviere, Nancy A.; Nasir, Adnan; Narayan, Roger J.

    2011-06-01

    Microneedles are small-scale needle-like projections that may be used for transdermal delivery of pharmacologic agents, including protein-containing and nucleic acid-containing agents. Commercial translation of polymeric microneedles would benefit from the use of facile and cost effective fabrication methods. In this study, visible light dynamic mask microstereolithography, a rapid prototyping technique that utilizes digital light projection for selective polymerization of a liquid resin, was used for fabrication of solid microneedle array structures out of an acrylate-based polymer. Pulsed laser deposition was used to deposit silver and zinc oxide coatings on the surfaces of the visible light dynamic mask microstereolithography-fabricated microneedle array structures. Agar diffusion studies were used to demonstrate the antimicrobial activity of the coated microneedle array structures. This study indicates that light-based technologies, including visible light dynamic mask microstereolithography and pulsed laser deposition, may be used to fabricate microneedles with antimicrobial properties for treatment of local skin infections.

  16. Chemical solution deposition: a path towards low cost coated conductors

    International Nuclear Information System (INIS)

    Obradors, X; Puig, T; Pomar, A; Sandiumenge, F; Pinol, S; Mestres, N; Castano, O; Coll, M; Cavallaro, A; Palau, A; Gazquez, J; Gonzalez, J C; Gutierrez, J; Roma, N; Ricart, S; Moreto, J M; Rossell, M D; Tendeloo, G van

    2004-01-01

    The achievement of low cost deposition techniques for high critical current YBa 2 Cu 3 O 7 coated conductors is one of the major objectives to achieve a widespread use of superconductivity in power applications. Chemical solution deposition techniques are appearing as a very promising methodology to achieve epitaxial oxide thin films at a low cost, so an intense effort is being carried out to develop routes for all chemical coated conductor tapes. In this work recent achievements will be presented towards the goal of combining the deposition of different type of buffer layers on metallic substrates based on metal-organic decomposition with the growth of YBa 2 Cu 3 O 7 layers using the trifluoroacetate route. The influence of processing parameters on the microstructure and superconducting properties will be stressed. High critical currents are demonstrated in 'all chemical' multilayers

  17. Durability and CMAS Resistance of Advanced Environmental Barrier Coatings Systems for SiC/SiC Ceramic Matrix Composites

    Science.gov (United States)

    Zhu, Dongming

    2015-01-01

    Environmental barrier coatings (EBCs) and SiCSiC ceramic matrix composites (CMCs) systems will play a crucial role in next generation turbine engines for hot-section component applications because of their ability to significantly increase engine operating temperatures with improved efficiency, reduce engine weight and cooling requirements. This paper will emphasize advanced environmental barrier coating developments for SiCSiC turbine airfoil components, by using advanced coating compositions and processing, in conjunction with mechanical and environment testing and durability validations. The coating-CMC degradations and durability in the laboratory simulated engine fatigue-creep and complex operating environments are being addressed. The effects of Calcium-Magnesium-Alumino-Silicate (CMAS) from road sand or volcano-ash deposits on the degradation mechanisms of the environmental barrier coating systems will be discussed. The results help understand the advanced EBC-CMC system performance, aiming at the durability improvements of more robust, prime-reliant environmental barrier coatings for successful applications of the component technologies and lifing methodologies.

  18. Combined Thermomechanical and Environmental Durability of Environmental Barrier Coating Systems on SiC/SiC Ceramic Matrix Composites

    Science.gov (United States)

    Zhu, Dongming; Harder, Bryan; Bhatt, Ramakrishna

    2016-01-01

    Environmental barrier coatings (EBCs) and SiC/SiC ceramic matrix composites (CMCs) will play a crucial role in next generation turbine engines for hot-section component applications. The development of prime-reliant environmental barrier coatings is essential to the EBC-CMC system durability, ensuring the successful implementations of the high temperature and lightweight engine component technologies for engine applications.This paper will emphasize recent NASA environmental barrier coating and CMC developments for SiC/SiC turbine airfoil components, utilizing advanced coating compositions and processing methods. The emphasis has been particularly placed on thermomechanical and environment durability evaluations of EBC-CMC systems. We have also addressed the integration of the EBCs with advanced SiC/SiC CMCs, and studied the effects of combustion environments and Calcium-Magnesium-Alumino-Silicate (CMAS) deposits on the durability of the EBC-CMC systems under thermal gradient and mechanical loading conditions. Advanced environmental barrier coating systems, including multicomponent rare earth silicate EBCs and HfO2-Si based bond coats, will be discussed for the performance improvements to achieve better temperature capability and CMAS resistance for future engine operating conditions.

  19. Deposition of tantalum carbide coatings on graphite by laser interactions

    Science.gov (United States)

    Veligdan, James; Branch, D.; Vanier, P. E.; Barietta, R. E.

    1994-01-01

    Graphite surfaces can be hardened and protected from erosion by hydrogen at high temperatures by refractory metal carbide coatings, which are usually prepared by chemical vapor deposition (CVD) or chemical vapor reaction (CVR) methods. These techniques rely on heating the substrate to a temperature where a volatile metal halide decomposes and reacts with either a hydrocarbon gas or with carbon from the substrate. For CVR techniques, deposition temperatures must be in excess of 2000 C in order to achieve favorable deposition kinetics. In an effort to lower the bulk substrate deposition temperature, the use of laser interactions with both the substrate and the metal halide deposition gas has been employed. Initial testing involved the use of a CO2 laser to heat the surface of a graphite substrate and a KrF excimer laser to accomplish a photodecomposition of TaCl5 gas near the substrate. The results of preliminary experiments using these techniques are described.

  20. Development Status and Performance Comparisons of Environmental Barrier Coating Systems for SiCSiC Ceramic Matrix Composites

    Science.gov (United States)

    Zhu, Dongming; Harder, Bryan

    2016-01-01

    Environmental barrier coatings (EBC) and SiCSiC ceramic matrix composites (CMCs) will play a crucial role in future aircraft turbine engine systems, because of their ability to significantly increase engine operating temperatures, reduce engine weight and cooling requirements. This paper presents current NASA EBC-CMC development emphases including: the coating composition and processing improvements, laser high heat flux-thermal gradient thermo-mechanical fatigue - environmental testing methodology development, and property evaluations for next generation EBC-CMC systems. EBCs processed with various deposition techniques including Plasma Spray, Electron Beam - Physical Vapor Deposition, and Plasma Spray Physical Vapor Deposition (PS-PVD) will be particularly discussed. The testing results and demonstrations of advanced EBCs-CMCs in complex simulated engine thermal gradient cyclic fatigue, oxidizing-steam and CMAS environments will help provide insights into the coating development strategies to meet long-term engine component durability goals.

  1. Superhydrophobic coating deposited directly on aluminum

    International Nuclear Information System (INIS)

    Escobar, Ana M.; Llorca-Isern, Nuria

    2014-01-01

    This study develops an alternative method for enhancing superhydrophobicity on aluminum surfaces with an amphiphilic reagent such as the dodecanoic acid. The goal is to induce superhydrophobicity directly through a simple process on pure (99.9 wt%) commercial aluminum. The initial surface activation leading to the formation of the superhydrophobic coating is studied using confocal microscopy. Superhydrophobic behavior is analyzed by contact angle measurements, scanning electron microscopy (SEM) and atomic force microscopy (AFM). The highest contact angle (approaching 153°) was obtained after forming hierarchical structures with a particular roughness obtained by grinding and polishing microgrooves on the aluminum surface together with the simultaneous action of HCl and dodecanoic acid. The results also showed that after immersion in the ethanol-acidic-fatty acid solutions, they reacted chemically through the action of the fatty acid, on the aluminum surface. The mechanism is analyzed by TOF-SIMS and XPS in order to determine the molecules involved in the reaction. The TOF-SIMS analysis revealed that the metal and its oxides seem to be necessary, and that free-aluminum is anchored to the fatty acid molecules and to the alumina molecules present in the medium. Consequently, both metallic aluminum and aluminum oxides are necessary in order to form the compound responsible for superhydrophobicity.

  2. Graphene Oxide Bionanocomposite Coatings with High Oxygen Barrier Properties

    Directory of Open Access Journals (Sweden)

    Ilke Uysal Unalan

    2016-12-01

    Full Text Available In this work, we present the development of bionanocomposite coatings on poly(ethylene terephthalate (PET with outstanding oxygen barrier properties. Pullulan and graphene oxide (GO were used as main polymer phase and nanobuilding block (NBB, respectively. The oxygen barrier performance was investigated at different filler volume fractions (ϕ and as a function of different relative humidity (RH values. Noticeably, the impermeable nature of GO was reflected under dry conditions, in which an oxygen transmission rate (OTR, mL·m−2·24 h−1 value below the detection limit of the instrument (0.01 mL·m−2·24 h−1 was recorded, even for ϕ as low as 0.0004. A dramatic increase of the OTR values occurred in humid conditions, such that the barrier performance was totally lost at 90% RH (the OTR of coated PET films was equal to the OTR of bare PET films. Modelling of the experimental OTR data by Cussler’s model suggested that the spatial ordering of GO sheets within the main pullulan phase was perturbed because of RH fluctuations. In spite of the presence of the filler, all the formulations allowed the obtainment of final materials with haze values below 3%, the only exception being the formulation with the highest loading of GO (ϕ ≈ 0.03. The mechanisms underlying the experimental observations are discussed.

  3. The development of chemically vapor deposited mullite coatings for the corrosion protection of SiC

    Energy Technology Data Exchange (ETDEWEB)

    Auger, M.; Hou, P.; Sengupta, A.; Basu, S.; Sarin, V. [Boston Univ., MA (United States)

    1998-05-01

    Crystalline mullite coatings have been chemically vapor deposited onto SiC substrates to enhance the corrosion and oxidation resistance of the substrate. Current research has been divided into three distinct areas: (1) Development of the deposition processing conditions for increased control over coating`s growth rate, microstructure, and morphology; (2) Analysis of the coating`s crystal structure and stability; (3) The corrosion resistance of the CVD mullite coating on SiC.

  4. Mechanisms and Mitigation of CMAS Attack on Thermal Barrier Coatings

    Science.gov (United States)

    Zaleski, Elisa Marie

    As gas turbine engines are driven to operate at higher temperatures to maximize efficiency, components become susceptible to attack by deposits of calcium magnesium alumino-silicate (CMAS) ingested with the intake air. Of particular interest to this work is the degradation of thermal barrier coatings (TBCs) by CMAS. Molten CMAS is known to interact with TBCs both thermochemically, by dissolving the ceramic and reprecipitating it as a new or modified phase, and thermomechanically, by infiltrating the porosity and degrading the strain tolerance. The thermochemical degradation of TBCs was investigated using primarily differential scanning calorimetry (DSC) by comparing the endotherms and exotherms recorded for pure, model silicates to those observed for silicates mixed with various TBC materials including YSZ and GZO. The five ternary silicates studied (CaO-AlO1.5-SiO2) began melting over a relatively narrow range (˜1125-1145°C). Introducing magnesium to the ternary results in higher melting temperatures and only minor changes to the crystallization behavior. Iron decreases the melting temperature, and markedly improves the crystallization kinetics of pure silicate systems, especially absent magnesium. Modification of the crystallization behavior of pure silicates has been proposed in the literature as a mitigation strategy for CMAS. This work utilizes DSC to look for characteristic changes as described above to probe potentially effective TBCs. The addition of YSZ to a quaternary CMAS results in little change to the melting or crystallization in the DSC, despite the dissolution of YSZ into the silicate. In stark contrast, GZO with CMAS generates a significant crystallization exotherm that appears in the DSC immediately after the silicate melts. As the fraction of GZO is increased, the melting endotherm begins to shrink due to the thermal overlap of the melting and crystallization processes. This signifies a rapid reaction, and a potentially useful TBC material for

  5. Advances in the electro-spark deposition coating process

    International Nuclear Information System (INIS)

    Johnson, R.N.; Sheldon, G.L.

    1986-04-01

    Electro-spark deposition (ESD) is a pulsed-arc micro-welding process using short-duration, high-current electrical pulses to deposit an electrode material on a metallic substrate. It is one of the few methods available by which a fused, metallurgically bonded coating can be applied with such a low total heat input that the bulk substrate material remains at or near ambient temperatures. The short duration of the electrical pulse allows an extremely rapid solidification of the deposited material and results in an exceptionally fine-grained, homogenous coating that approaches (and with some materials, actually is) an amorphous structure. This structure is believed to contribute to the good tribological and corrosion performance observed for hardsurfacing materials used in the demanding environments of high temperatures, liquid metals, and neutron irradiation. A brief historical review of the process is provided, followed by descriptions of the present state-of-the-art and of the performance and applications of electro-spark deposition coatings in liquid-metal-cooled nuclear reactors

  6. Highly defective oxides as sinter resistant thermal barrier coating

    Science.gov (United States)

    Subramanian, Ramesh

    2005-08-16

    A thermal barrier coating material formed of a highly defective cubic matrix structure having a concentration of a stabilizer sufficiently high that the oxygen vacancies created by the stabilizer interact within the matrix to form multi-vacancies, thereby improving the sintering resistance of the material. The concentration of stabilizer within the cubic matrix structure is greater than that concentration of stabilizer necessary to give the matrix a peak ionic conductivity value. The concentration of stabilizer may be at least 30 wt. %. Embodiments include a cubic matrix of zirconia stabilized by at least 30-50 wt. % yttria, and a cubic matrix of hafnia stabilized by at least 30-50 wt. % gadolinia.

  7. Corrosion Resistance of Copper Coatings Deposited by Cold Spraying

    Science.gov (United States)

    Winnicki, M.; Baszczuk, A.; Jasiorski, M.; Małachowska, A.

    2017-12-01

    In the article, a study of corrosion resistance of copper and copper-based cermet (Cu+Al2O3 and Cu+SiC) coatings deposited onto aluminum alloy substrate using the low-pressure cold spraying method is presented. The samples were subjected to two different corrosion tests at room temperature: (1) Kesternich test and (2) a cyclic salt spray test. The selected tests were allowed to simulate service conditions typical for urban, industrial and marine environment. Examination of corroded samples included analysis changes on the coating surface and in the microstructure. The physicochemical tests were carried out using x-ray diffraction to define corrosion products. Moreover, microhardness and electrical conductivity measurements were conducted to estimate mechanical and physical properties of the coatings after corrosion tests. XRD analysis clearly showed that regardless of corrosion conditions, for all samples cuprite (Cu2O) was the main product. However, in the case of Cu+Al2O3 cermet coating, chlorine- and sulfate-containing phases such as Cu2Cl(OH)3 (paracetamite) and Cu3(SO4)(OH)4 (antlerite) were also recorded. This observation gives better understanding of the lowest microstructure changes observed for Cu+Al2O3 coating after the corrosion tests. This is also a justification for the lowest decrease in electrical conductivity registered after the corrosion tests for this coating.

  8. Thermal cycling behaviour of lanthanum zirconate as EB-PVD thermal barrier coating

    International Nuclear Information System (INIS)

    Bobzin, K.; Lugscheider, E.; Bagcivan, N.

    2006-01-01

    Thermal cycling tests with two different EB-PVD thermal barrier coatings (TBC) were performed in a furnace cycle test. The results of these tests showed an increase of endurable cycle number when pyrochloric La 2 Zr 2 O 7 was used as TBC. 1865 cycles were reached with La 2 Zr 2 O 7 and 1380 cycles with 7 weigth-% yttria stabilised zirconia (YSZ) EB-PVD TBC. Additional investigation was made with scanning electron microscope (SEM) to investigate morphology and to determine chemical composition by electron dispersive x-ray spectroscopy (EDS) analysis. X-Ray diffraction was performed to analyze structural constitution of deposited coatings. (Abstract Copyright [2006], Wiley Periodicals, Inc.)

  9. Mechanical Properties of Air Plasma Sprayed Environmental Barrier Coating (EBC) Materials

    Science.gov (United States)

    Richards, Bradley; Zhu, Dongming; Ghosn, Louis; Wadley, Haydn

    2015-01-01

    Development work in Environmental Barrier Coatings (EBCs) for Ceramic Matrix Composites (CMCs) has focused considerably on the identification of materials systems and coating architectures to meet application needs. The evolution of these systems has occurred so quickly that modeling efforts and requisite data for modeling lag considerably behind development. Materials property data exists for many systems in the bulk form, but the effects of deposition on the critical properties of strength and fracture behavior are not well studied. We have plasma sprayed bulk samples of baseline EBC materials (silicon, ytterbium disilicate) and tested the mechanical properties of these materials to elicit differences in strength and toughness. We have also endeavored to assess the mixed-mode fracture resistance, Gc, of silicon in a baseline EBC applied to SiCSiC CMC via four point bend test. These results are compared to previously determined properties of the comparable bulk material.

  10. Parametric Studies Of Failure Mechanisms In Thermal Barrier Coatings During Thermal Cycling Using FEM

    Science.gov (United States)

    Srivathsa, B.; Das, D. K.

    2015-12-01

    Thermal barrier coatings (TBCs) are widely used on different hot components of gas turbine engines such as blades and vanes. Although, several mechanisms for the failure of the TBCs have been suggested, it is largely accepted that the durability of these coatings is primarily determined by the residual stresses that are developed during the thermal cycling. In the present study, the residual stress build-up in an electron beam physical vapour deposition (EB-PVD) based TBCs on a coupon during thermal cycling has been studied by varying three parameters such as the cooling rate, TBC thickness and substrate thickness. A two-dimensional thermomechanical generalized plane strain finite element simulations have been performed for thousand cycles. It was observed that these variations change the stress profile significantly and the stress severity factor increases non-linearly. Overall, the predictions of the model agree with reported experimental results and help in predicting the failure mechanisms.

  11. Polymer derived ceramic composites as environmental barrier coatings on steel

    Science.gov (United States)

    Torrey, Jessica D.

    Polymer derived ceramics have shown promise as a novel way to process low-dimensional ceramics such as fibers and coatings. They offer advantages over traditional ceramic processing routes including lower pyrolysis temperatures and the ability to employ polymeric processing techniques. The main drawback to preceramic polymers is that they undergo a shrinkage during pyrolysis that can be greater than 50-volume%. One way to overcome this shrinkage is to add filler particles, usually elemental or binary metals, which will expand upon reaction with the pyrolysis atmosphere, thereby compensating for the shrinkage of the polymer. The aim of this study is to develop a polymer derived ceramic composite coating on steel as a barrier to oxidation and carburization, while concurrently gaining insight as to the fundamental mechanisms for compositional and microstructural evolution within the system. A systematic approach to selecting the preceramic polymer and expansion agents was taken. Six commercially available poly(silsesquioxane) polymers and a polysiloxane were studied. Several metals and an intermetallic were considered as potential expansion agents. The most desirable polymer/expansion agent combination was achieved with poly(hydridomethylsiloxane) as the matrix and titanium disilicide as the filler. Processing parameters have been optimized and a relationship derived to predict final coating thickness based on slurry viscosity and dip coating withdrawal speed. Microstructural analysis reveals an amorphous composite coating of oxidized filler particles in a silica matrix. A diffusion layer is visible at the coating-steel interface, indicating good bonding. The optimized coatings are ˜18mum thick, have some residual porosity and a density of 2.57g/cm3. A systematic study of the phase transformations and microstructural changes in the coating and its components during pyrolysis in air is also presented. The system evolves from a polymer filled with a binary metal at

  12. Modification of material properties and coating deposition using plasma jet

    International Nuclear Information System (INIS)

    Pogrebnjak, A.D.; Rusimov, Sh.M.

    2006-01-01

    Full text: Using X-ray structure analysis (XRD), scanning electron microscopy (SEM) with micro-analysis, measurements of friction wear and micro-hardness, we studied surface melting effects of powder coatings AN-35, which appeared as a result of action of concentrated energy flows (pulsed plasma flows). Plasma detonation deposition of a powder on a stainless steel substrate were accompanied by formation of an alloyed surface structure, which basic element was α(hcp) and β(fcc) cobalt. A temperature diapason chosen for coating formation (according to the XRD analysis) provided the formation of intermetallic compounds of cobalt and chromium of Co x Cr y type. Pulsed-plasma surface melting of powder coatings also induced doping of the near surface layer by molybdenum atoms. We found that chosen methods of analysis and surface treatment regimes provided essentially decreased wear, as well as increased microhardness and nano hardness of the irradiated surfaces. It was demonstrated that a resulting increase in servicing characteristics was related to the processes of phase transformations occurring in the powder when it had been in a high temperature plasma-detonation flow as a result of pulsed plasma surface doping by molybdenum atoms, redistribution of the coating elements, appearance of micro- and nano-grain structure, as well as decreased coating porosity induced by thermal annealing by concentrated energy flows. New experimental results on the structure and the elemental and phase composition of hybrid coatings, which were deposited on a substrate of AISI 321 stainless steel using a combination of plasma detonation, vacuum arc and subsequent High-Current Electron Beam (HCEB) treatment, are presented. We found that an increase in energy density intensified mass-transfer processes and resulted in changes in aluminum oxide phase composition (γ→α and β→α). Also we observed the formation of a nano-crystalline structure in Al 2 O 3 coatings. Electron beam

  13. Raman microscopic studies of PVD deposited hard ceramic coatings

    International Nuclear Information System (INIS)

    Constable, C.P.

    2000-01-01

    PVD hard ceramic coatings grown via the combined cathodic arc/unbalance magnetron deposition process were studied using Raman microscopy. Characteristic spectra from binary, multicomponent, multilayered and superlattice coatings were acquired to gain knowledge of the solid-state physics associated with Raman scattering from polycrystalline PVD coatings and to compile a comprehensive spectral database. Defect-induced first order scattering mechanisms were observed which gave rise to two pronounced groups of bands related to the acoustical (150- 300cm -1 ) and optical (400-7 50cm -1 ) parts of the phonon spectrum. Evidence was gathered to support the theory that the optic modes were mainly due to the vibrations of the lighter elements and the acoustic modes due to the vibrations of the heavier elements within the lattice. A study into the deformation and disordering on the Raman spectral bands of PVD coatings was performed. TiAIN and TiZrN coatings were intentionally damaged via scratching methods. These scratches were then analysed by Raman mapping, both across and along, and a detailed spectral interpretation performed. Band broadening occurred which was related to 'phonon relaxation mechanisms' as a direct result of the breaking up of coating grains resulting in a larger proportion of grain boundaries per-unit-volume. A direct correlation of the amount of damage with band width was observed. Band shifts were also found to occur which were due to the stresses caused by the scratching process. These shifts were found to be the largest at the edges of scratches. The Raman mapping of 'droplets', a defect inherent to PVD deposition processes, found that higher compressive stresses and large amounts of disorder occurred for coating growth onto droplets. Strategies designed to evaluate the ability of Raman microscopy to monitor the extent of real wear on cutting tools were evaluated. The removal of a coating layer and subsequent detection of a base layer proved

  14. Tribological Properties of Chemical Vapor Deposited Graphene Coating Layer

    International Nuclear Information System (INIS)

    Lee, Jong Hoon; Kim, Sun Hye; Cho, Doo Ho; Kim, Se Chang; Baek, Seung Guk; Lee, Jong Gu; Choi, Jae-Boong; Seok, Chang Sung; Kim, Moon Ki; Koo, Ja Choon; Lim, Byeong Soo; Kang, Junmo

    2012-01-01

    Graphene has recently received high attention as a promising material for various applications, and many related studies have been undertaken to reveal its basic mechanical properties. However, the tribological properties of graphene film fabricated by the chemical vapor deposition (CVD) method are barely known. In this study, the contact angle and frictional wear characteristics of graphene coated copper film were investigated under room temperature, normal air pressure, and no lubrication condition. The contact angle was measured by sessile drop method and the wear test was carried out under normal loads of 660 mN and 2940 mN, respectively. The tribological behaviors of a graphene coating layer were also examined. Compared to heat treated bare copper foil, the graphene coated one shows a higher contact angle and lower friction coefficient.

  15. Tribological Properties of Chemical Vapor Deposited Graphene Coating Layer

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jong Hoon; Kim, Sun Hye; Cho, Doo Ho; Kim, Se Chang; Baek, Seung Guk; Lee, Jong Gu; Choi, Jae-Boong; Seok, Chang Sung; Kim, Moon Ki; Koo, Ja Choon; Lim, Byeong Soo [Sungkyunkwan University, Suwon (Korea, Republic of); Kang, Junmo [Sungkyunkwan University, Suwon (Korea, Republic of)

    2012-03-15

    Graphene has recently received high attention as a promising material for various applications, and many related studies have been undertaken to reveal its basic mechanical properties. However, the tribological properties of graphene film fabricated by the chemical vapor deposition (CVD) method are barely known. In this study, the contact angle and frictional wear characteristics of graphene coated copper film were investigated under room temperature, normal air pressure, and no lubrication condition. The contact angle was measured by sessile drop method and the wear test was carried out under normal loads of 660 mN and 2940 mN, respectively. The tribological behaviors of a graphene coating layer were also examined. Compared to heat treated bare copper foil, the graphene coated one shows a higher contact angle and lower friction coefficient.

  16. The Use of Feature Parameters to Asses Barrier Properties of ALD coatings for Flexible PV Substrates

    Science.gov (United States)

    Blunt, Liam; Robbins, David; Fleming, Leigh; Elrawemi, Mohamed

    2014-03-01

    This paper reports on the recent work carried out as part of the EU funded NanoMend project. The project seeks to develop integrated process inspection, cleaning, repair and control systems for nano-scale thin films on large area substrates. In the present study flexible photovoltaic films have been the substrate of interest. Flexible PV films are the subject of significant development at present and the latest films have efficiencies at or beyond the level of Si based rigid PV modules. These flexible devices are fabricated on polymer film by the repeated deposition, and patterning, of thin layer materials using roll-to-roll processes, where the whole film is approximately 3um thick prior to encapsulation. Whilst flexible films offer significant advantages in terms of mass and the possibility of building integration (BIPV) they are at present susceptible to long term environmental degradation as a result of water vapor transmission through the barrier layers to the CIGS (Copper Indium Gallium Selenide CuInxGa(1-x)Se2) PV cells thus causing electrical shorts and efficiency drops. Environmental protection of the GIGS cell is provided by a thin (40nm) barrier coating of Al2O3. The highly conformal aluminium oxide barrier layer is produced by atomic layer deposition (ALD) where, the ultra-thin Al2O3 layer is deposited onto polymer thin films before these films encapsulate the PV cell. The surface of the starting polymer film must be of very high quality in order to avoid creating defects in the device layers. Since these defects reduce manufacturing yield, in order to prevent them, a further thin polymer coating (planarization layer) is generally applied to the polymer film prior to deposition. The presence of surface irregularities on the uncoated film can create defects within the nanometre-scale, aluminium oxide, barrier layer and these are measured and characterised. This paper begins by reporting the results of early stage measurements conducted to characterise

  17. Amorphous boron coatings produced with vacuum arc deposition technology

    CERN Document Server

    Klepper, C C; Yadlowsky, E J; Carlson, E P; Keitz, M D; Williams, J M; Zuhr, R A; Poker, D B

    2002-01-01

    In principle, boron (B) as a material has many excellent surface properties, including corrosion resistance, very high hardness, refractory properties, and a strong tendency to bond with most substrates. The potential technological benefits of the material have not been realized, because it is difficult to deposit it as coatings. B is difficult to evaporate, does not sputter well, and cannot be thermally sprayed. In this article, first successful deposition results from a robust system, based on the vacuum (cathodic) arc technology, are reported. Adherent coatings have been produced on 1100 Al, CP-Ti, Ti-6Al-4V, 316 SS, hard chrome plate, and 52 100 steel. Composition and thickness analyses have been performed by Rutherford backscattering spectroscopy. Hardness (H) and modules (E) have been evaluated by nanoindentation. The coatings are very pure and have properties characteristic of B suboxides. A microhardness of up to 27 GPa has been measured on a 400-nm-thick film deposited on 52 100 steel, with a corresp...

  18. Integrated Fluid and Materials Modeling of Environmental Barrier Coatings, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Environmental barrier coatings (EBC) prevent oxidation of ceramic materials in reactive, high temperature environments such as the exhaust regions of gas turbine...

  19. Property Evaluation and Damage Evolution of Environmental Barrier Coatings and Environmental Barrier Coated SiC/SiC Ceramic Matrix Composite Sub-Elements

    Science.gov (United States)

    Zhu, Dongming; Halbig, Michael; Jaskowiak, Martha; Hurst, Janet; Bhatt, Ram; Fox, Dennis S.

    2014-01-01

    This paper describes recent development of environmental barrier coatings on SiC/SiC ceramic matrix composites. The creep and fatigue behavior at aggressive long-term high temperature conditions have been evaluated and highlighted. Thermal conductivity and high thermal gradient cyclic durability of environmental barrier coatings have been evaluated. The damage accumulation and complex stress-strain behavior environmental barrier coatings on SiCSiC ceramic matrix composite turbine airfoil subelements during the thermal cyclic and fatigue testing of have been also reported.

  20. Gas barrier properties of diamond-like carbon films coated on PTFE

    International Nuclear Information System (INIS)

    Ozeki, K.; Nagashima, I.; Ohgoe, Y.; Hirakuri, K.K.; Mukaibayashi, H.; Masuzawa, T.

    2009-01-01

    Diamond-like carbon (DLC) films were deposited on polytetrafluoroethylene (PTFE) using radio frequency (RF) plasma-enhanced chemical vapour deposition (PE-CVD). Before the DLC coating, the PTFE substrate was modified with a N 2 plasma pre-treatment to enhance the adhesive strength of the DLC to the substrate. The influences of the N 2 plasma pre-treatment and process pressure on the gas permeation properties of these DLC-coated PTFE samples were investigated. In the Raman spectra, the G peak position shifted to a lower wave number with increasing process pressure. With scanning electron microscopy (SEM), a network of microcracks was observed on the surface of the DLC film without N 2 plasma pre-treatment. The density of these cracks decreased with increasing process pressure. In the film subjected to a N 2 plasma pre-treatment, no cracks were observed at any process pressure. In the gas barrier test, the gas permeation decreased drastically with increasing film thickness and saturated at a thickness of 0.2 μm. The DLC-coated PTFE with the N 2 plasma pre-treatment exhibited a greater reduction in gas permeation than did the samples without pre-treatment. For both sample types, gas permeation decreased with increasing process pressure.

  1. Effect of an Opaque Reflecting Layer on the Thermal Behavior of a Thermal Barrier Coating

    Science.gov (United States)

    Spuckler, Charles M.

    2007-01-01

    A parametric study using a two-flux approximation of the radiative transfer equation was performed to examine the effects of an opaque reflective layer on the thermal behavior of a typical semitransparent thermal barrier coating on an opaque substrate. Some ceramic materials are semitransparent in the wavelength ranges where thermal radiation is important. Even with an opaque layer on each side of the semitransparent thermal barrier coating, scattering and absorption can have an effect on the heat transfer. In this work, a thermal barrier coating that is semitransparent up to a wavelength of 5 micrometers is considered. Above 5 micrometers wavelength, the thermal barrier coating is opaque. The absorption and scattering coefficient of the thermal barrier was varied. The thermal behavior of the thermal barrier coating with an opaque reflective layer is compared to a thermal barrier coating without the reflective layer. For a thicker thermal barrier coating with lower convective loading, which would be typical of a combustor liner, a reflective layer can significantly decrease the temperature in the thermal barrier coating and substrate if the scattering is weak or moderate and for strong scattering if the absorption is large. The layer without the reflective coating can be about as effective as the layer with the reflective coating if the absorption is small and the scattering strong. For low absorption, some temperatures in the thermal barrier coating system can be slightly higher with the reflective layer. For a thin thermal barrier coating with high convective loading, which would be typical of a blade or vane that sees the hot sections of the combustor, the reflective layer is not as effective. The reflective layer reduces the surface temperature of the reflective layer for all conditions considered. For weak and moderate scattering, the temperature of the TBC-substrate interface is reduced but for strong scattering, the temperature of the substrate is increased

  2. Silver doped hydroxyapatite coatings by sacrificial anode deposition under magnetic field.

    Science.gov (United States)

    Swain, S; Rautray, T R

    2017-09-13

    Uniform distribution of silver (Ag) in the hydroxyapatite (HA) coated Ti surface has been a concern for which an attempt has been made to dope Ag in HA coating with and without magnetic field. Cathodic deposition technique was employed to coat Ag incorporated hydroxyapatite coating using a sacrificial silver anode method by using NdFeB bar magnets producing 12 Tesla magnetic field. While uniform deposition of Ag was observed in the coatings under magnetic field, dense coating was evident in the coating without magnetic field conditions. Uniformly distributed Ag incorporated HA in the present study has potential to fight microorganism while providing osseoconduction properties of the composite coating.

  3. Analysis of Properties of Hard Coatings and Wear Resistance of Chemical Vapour Deposition (PVD Coated Technology

    Directory of Open Access Journals (Sweden)

    Pavel Hudeček

    2015-01-01

    Full Text Available Modern coating methods are having become an important part of industry. Wear resistance, durability, toughness (breakage resistance and hot hardness (high hardness and chemical stability at high temperature are the four main technological properties necessary for durability and long life time. These proprieties are for productivity, economy and ecology very important point. This resource deals with the analysis of properties of hard coatings and wear resistance of chemical vapour deposition (PVD coated technology. It focuses on the preparation, execution and evaluation of test coatings on the front ball-milling cutters. Examination of these characteristic properties may give into an insight to the reason why some systems show excellent wear characteristic.

  4. Boron carbide coating deposition on tungsten substrates from atomic fluxes of boron and carbon

    Science.gov (United States)

    Sadovskiy, Y.; Begrambekov, L.; Ayrapetov, A.; Gretskaya, I.; Grunin, A.; Dyachenko, M.; Puntakov, N.

    2016-09-01

    A device used for both coating deposition and material testing is presented in the paper. By using lock chambers, sputtering targets are easily exchanged with sample holder thus allowing testing of deposited samples with high power density electron or ion beams. Boron carbide coatings were deposited on tungsten samples. Methods of increasing coating adhesion are described in the paper. 2 μm boron carbide coatings sustained 450 heating cycles from 100 to 900 C. Ion beam tests have shown satisfactory results.

  5. Thermal Conductivity of Ceramic Thermal Barrier and Environmental Barrier Coating Materials

    Science.gov (United States)

    Zhu, Dong-Ming; Bansal, Narottam P.; Lee, Kang N.; Miller, Robert A.

    2001-01-01

    Thermal barrier and environmental barrier coatings (TBC's and EBC's) have been developed to protect metallic and Si-based ceramic components in gas turbine engines from high temperature attack. Zirconia-yttria based oxides and (Ba,Sr)Al2Si2O8(BSAS)/mullite based silicates have been used as the coating materials. In this study, thermal conductivity values of zirconia-yttria- and BSAS/mullite-based coating materials were determined at high temperatures using a steady-state laser heat flux technique. During the laser conductivity test, the specimen surface was heated by delivering uniformly distributed heat flux from a high power laser. One-dimensional steady-state heating was achieved by using thin disk specimen configuration (25.4 mm diam and 2 to 4 mm thickness) and the appropriate backside air-cooling. The temperature gradient across the specimen thickness was carefully measured by two surface and backside pyrometers. The thermal conductivity values were thus determined as a function of temperature based on the 1-D heat transfer equation. The radiation heat loss and laser absorption corrections of the materials were considered in the conductivity measurements. The effects of specimen porosity and sintering on measured conductivity values were also evaluated.

  6. Advanced Low Conductivity Thermal Barrier Coatings: Performance and Future Directions (Invited paper)

    Science.gov (United States)

    Zhu, Dongming; Miller, Robert A.

    2008-01-01

    Thermal barrier coatings will be more aggressively designed to protect gas turbine engine hot-section components in order to meet future engine higher fuel efficiency and lower emission goals. In this presentation, thermal barrier coating development considerations and performance will be emphasized. Advanced thermal barrier coatings have been developed using a multi-component defect clustering approach, and shown to have improved thermal stability and lower conductivity. The coating systems have been demonstrated for high temperature combustor applications. For thermal barrier coatings designed for turbine airfoil applications, further improved erosion and impact resistance are crucial for engine performance and durability. Erosion resistant thermal barrier coatings are being developed, with a current emphasis on the toughness improvements using a combined rare earth- and transition metal-oxide doping approach. The performance of the toughened thermal barrier coatings has been evaluated in burner rig and laser heat-flux rig simulated engine erosion and thermal gradient environments. The results have shown that the coating composition optimizations can effectively improve the erosion and impact resistance of the coating systems, while maintaining low thermal conductivity and cyclic durability. The erosion, impact and high heat-flux damage mechanisms of the thermal barrier coatings will also be described.

  7. Spectroscopic Study of Plasma Polymerized a-C:H Films Deposited by a Dielectric Barrier Discharge.

    Science.gov (United States)

    Chandrashekaraiah, Thejaswini Halethimmanahally; Bogdanowicz, Robert; Rühl, Eckart; Danilov, Vladimir; Meichsner, Jürgen; Thierbach, Steffen; Hippler, Rainer

    2016-07-19

    Plasma polymerized a-C:H thin films have been deposited on Si (100) and aluminum coated glass substrates by a dielectric barrier discharge (DBD) operated at medium pressure using C₂H m /Ar ( m = 2, 4, 6) gas mixtures. The deposited films were characterized by Fourier transform infrared reflection absorption spectroscopy (FT-IRRAS), Raman spectroscopy, and ellipsometry. FT-IRRAS revealed the presence of sp ³ and sp ² C-H stretching and C-H bending vibrations of bonds in the films. The presence of D and G bands was confirmed by Raman spectroscopy. Thin films obtained from C₂H₄/Ar and C₂H₆/Ar gas mixtures have I D /I G ratios of 0.45 and 0.3, respectively. The refractive indices were 2.8 and 3.1 for C₂H₄/Ar and C₂H₆/Ar films, respectively, at a photon energy of 2 eV.

  8. Corrosion properties of aluminium coatings deposited on sintered NdFeB by ion-beam-assisted deposition

    Energy Technology Data Exchange (ETDEWEB)

    Mao Shoudong; Yang Hengxiu; Li Jinlong; Huang Feng [Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, 519 Zhuangshi Road, Ningbo 315201 (China); Song Zhenlun, E-mail: songzhenlun@nimte.ac.cn [Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, 519 Zhuangshi Road, Ningbo 315201 (China)

    2011-04-15

    Pure Al coatings were deposited by direct current (DC) magnetron sputtering to protect sintered NdFeB magnets. The effects of Ar{sup +} ion-beam-assisted deposition (IBAD) on the structure and the corrosion behaviour of Al coatings were investigated. The Al coating prepared by DC magnetron sputtering with IBAD (IBAD-Al-coating) had fewer voids than the coating without IBAD (Al-coating). The corrosion behaviour of the Al-coated NdFeB specimens was investigated by potentiodynamic polarisation, a neutral salt spray (NSS) test, and electrochemical impedance spectroscopy (EIS). The pitting corrosion of the Al coatings always began at the voids of the grain boundaries. Bombardment by the Ar{sup +} ion-beams effectively improved the corrosion resistance of the IBAD-Al-coating.

  9. Design and Environmental Factors Contributing to the Failure of Thermal Barrier Coating Systems

    Science.gov (United States)

    Weeks, Matthew David

    Gas turbine engines are a staple of 21st century air and sea propulsion systems and are also a critical component in large-scale electricity generation. The hot-section components of these engines are protected by a complex ceramic and metal multi-layer coating called a thermal barrier coating (TBC) system. The failure of TBC systems occurs as a result of both thermo-chemical and thermo-mechanical degradation. This research involves exploring both of these mechanisms for two distinctly different issues. The United States Navy is currently making a push to implement the use of alternative fuels by 2012, but the use of these fuels (syngas, high hydrogen content, and alternatives to JP-8) presents significant materials durability challenges. Initial data suggests that high water vapor levels, high sulfur concentrations, and ash deposits from fuel impurities lead to unique, and severe, degradation modes. This research is aimed at addressing the effects of differing combustion environment characteristics on the corrosion and oxidation of TBC systems. On the industrial front, there is a constant driver to better understand and predict coating failure, particularly in air-plasma sprayed (APS) TBC systems. The morphology of the metal-ceramic interface is known to play a key role in the generation of compressive and tensile stresses that eventually cause coating failure in typical engine environments. Experimental evidence and field experience have shown that a tortuous interface is generally beneficial to coating lifetime. Nevertheless, for the past 40 years engineers have struggled to find a functional correlation between BC topology and coating system lifetime. This document also addresses the progress that has been made toward the establishment of this functional correlation.

  10. Chemical vapor deposited silica coatings for solar mirror protection

    Science.gov (United States)

    Gulino, Daniel A.; Dever, Therese M.; Banholzer, William F.

    1988-01-01

    A variety of techniques is available to apply protective coatings to oxidation susceptible spacecraft components, and each has associated advantages and disadvantages. Film applications by means of chemical vapor deposition (CVD) has the advantage of being able to be applied conformally to objects of irregular shape. For this reason, a study was made of the oxygen plasma durability of thin film (less than 5000 A) silicon dioxide coatings applied by CVD. In these experiments, such coatings were applied to silver mirrors, which are strongly subject to oxidation, and which are proposed for use on the space station solar dynamic power system. Results indicate that such coatings can provide adequate protection without affecting the reflectance of the mirror. Scanning electron micrographs indicated that oxidation of the silver layer did occur at stress crack locations, but this did not affect the measured solar reflectances. Oxidation of the silver did not proceed beyond the immediate location of the crack. Such stress cracks did not occur in thinner silica films, and hence such films would be desirable for this application.

  11. Environmental Barrier Coatings (EBC) for Ceramic Matrix Composite (CMC) Materials

    Science.gov (United States)

    Lee,Kang

    2001-01-01

    The upper use temperature of current Environmental Barrier Coatings (EBC's) based on mullite and BSAS (EPM EBC's) is limited to -255 F due to silica volatility, chemical reactions, and high thermal conductivity. Therefore, new EBC s having low CTE, good chemical compatibility, and high melting point (greater than 2700 F ) are being investigated. Sinter-resistant, low thermal conductivity EBC s are strongly desired to achieve the UEET EBC goal of 270 F EBC surface temperature and 30 F AT over long exposures (greater than 1000 hr). Key areas affecting the upper temperature limit of current EBC s as well as the ongoing efforts to develop next generation EBC s in the UEET Program will be discussed.

  12. The influence of the structures and compounds of DLC coatings on the barrier properties of PET bottles

    International Nuclear Information System (INIS)

    Li, Yang; Zhen-Duo, Wang; Shou-Ye, Zhang; Li-Zhen, Yang; Qiang, Chen

    2009-01-01

    To reduce the oxygen transmission rate through a polyethylene terephthalate (PET) bottle (an organic plastic) diamond-like carbon (DLC) coatings on the inner surface of the PET bottle were deposited by radio frequency plasma-enhanced chemical vapour deposition (RF-PECVD) technology with C 2 H 2 as the source of carbon and Ar as the diluted gas. As the barrier layer to humidity and gas permeation, this paper analyses the DLC film structure, composition, morphology and barrier properties by Fourier transform infrared, atomic force microscopy, scanning electron microscopy and oxygen transmission rate in detail. From the spectrum, it is found that the DLC film mainly consists of sp 3 bonds. The barrier property of the films is significantly relevant to the sp 3 bond concentration in the coating, the film thickness and morphology. Additionally, it is found that DLC film deposited in an inductively coupled plasma enhanced capacitively coupled plasma source shows a compact, homogeneous and crack-free surface, which is beneficial for a good gas barrier property in PET bottles. (fluids, plasmas and electric discharges)

  13. Metal coatings prepared by organometallic chemical vapour deposition (OMCVD)

    Energy Technology Data Exchange (ETDEWEB)

    Wochnowski, Joern; Heck, Juergen [Institute of Inorganic and Applied Chemistry, Hamburg (Germany); Goellnitz, Thimo [Institute of Inorganic and Applied Chemistry, Hamburg (Germany); Institute of Applied Physics, University of Hamburg (Germany); Hoffmann, Germar; Wiesendanger, Roland [Institute of Applied Physics, University of Hamburg (Germany)

    2008-07-01

    In microtechnology, the coating of temperature-sensitive substrates with high melting-point materials is challenging. The use of volatile organometallic compounds can be an answer to solve this ambitious task. We developed an experimental set-up for the deposition of elements, oxides, and functional composites in glass hollowware by means of OMCVD. With the first experimental set-up, the thermally induced decomposition of numerous elementorganic and metallorganic precursors has been tested for the deposition of catalytic or optic materials. Here, we present experimental data of the thermal deposition of different metals as tungsten on a glass surface. We used Atomic Force Microscopy as one standard analytical surface method to obtain structural and morphological information of the deposited metal layers. We discuss the preparation and the analytics of the prepared surfaces. With the objective to bring the deposition temperature of W(CO){sub 6} further down to room temperature, we developed a new photolytic OMCVD set-up. We demonstrate and discuss the realization of our experimental setup.

  14. Thermal barrier coatings for thermal insulation and corrosion resistance in industrial gas turbine engines

    Science.gov (United States)

    Vogan, J. W.; Hsu, L.; Stetson, A. R.

    1981-01-01

    Four thermal barrier coatings were subjected to a 500-hour gas turbine engine test. The coatings were two yttria stabilized zirconias, calcium ortho silicate and calcium meta titanate. The calcium silicate coating exhibited significant spalling. Yttria stabilized zirconia and calcium titanate coatings showed little degradation except in blade leading edge areas. Post-test examination showed variations in the coating due to manual application techniques. Improved process control is required if engineering quality coatings are to be developed. The results indicate that some leading edge loss of the coating can be expected near the tip.

  15. Morphology, Composition, and Bioactivity of Strontium-Doped Brushite Coatings Deposited on Titanium Implants via Electrochemical Deposition

    Directory of Open Access Journals (Sweden)

    Yongqiang Liang

    2014-06-01

    Full Text Available Surface modification techniques have been applied to generate titanium implant surfaces that promote osseointegration for use in dental applications. In this study, strontium-doped brushite coatings were deposited on titanium by electrochemical deposition. The phase composition of the coating was investigated by energy dispersive X-ray spectroscopy and X-ray diffraction. The surface morphologies of the coatings were studied through scanning electron microscopy, and the cytocompatibility and bioactivity of the strontium-doped brushite coatings were evaluated using cultured osteoblasts. Osteoblast proliferation was enhanced by the addition of strontium, suggesting a possible mechanism by which strontium incorporation in brushite coatings increased bone formation surrounding the implants. Cell growth was also strongly influenced by the composition of the deposited coatings, with a 10% Sr-doped brushite coating inducing the greatest amount of bone formation among the tested materials.

  16. Shear strength of a thermal barrier coating parallel to the bond coat

    International Nuclear Information System (INIS)

    Cruse, T.A.; Dommarco, R.C.; Bastias, P.C.

    1998-01-01

    The static and low cycle fatigue strength of an air plasma sprayed (APS) partially stabilized zirconia thermal barrier coating (TBC) is experimentally evaluated. The shear testing utilized the Iosipescu shear test arrangement. Testing was performed parallel to the TBC-substrate interface. The TBC testing required an innovative use of steel extensions with the TBC bonded between the steel extensions to form the standard Iosipescu specimen shape. The test method appears to have been successful. Fracture of the TBC was initiated in shear, although unconstrained specimen fractures propagated at the TBC-bond coat interface. The use of side grooves on the TBC was successful in keeping the failure in the gage section and did not appear to affect the shear strength values that were measured. Low cycle fatigue failures were obtained at high stress levels approaching the ultimate strength of the TBC. The static and fatigue strengths do not appear to be markedly different from tensile properties for comparable TBC material

  17. Novel Functionally Graded Thermal Barrier Coatings in Coal-Fired Power Plant Turbines

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Jing [Indiana Univ., Indianapolis, IN (United States)

    2016-11-01

    This project presents a detailed investigation of a novel functionally graded coating material, pyrochlore oxide, for thermal barrier coating (TBC) in gas turbines used in coal-fired power plants. Thermal barrier coatings are refractory materials deposited on gas turbine components, which provide thermal protection for metallic components at operating conditions. The ultimate goal of this research is to develop a manufacturing process to produce the novel low thermal conductivity and high thermal stability pyrochlore oxide based coatings with improved high-temperature durability. The current standard TBC, yttria stabilized zirconia (YSZ), has service temperatures limited to <1200°C, due to sintering and phase transition at higher temperatures. In contrast, pyrochlore oxide, e.g., lanthanum zirconate (La2Zr2O7, LZ), has demonstrated lower thermal conductivity and better thermal stability, which are crucial to high temperature applications, such as gas turbines used in coal-fired power plants. Indiana University – Purdue University Indianapolis (IUPUI) has collaborated with Praxair Surface Technologies (PST), and Changwon National University in South Korea to perform the proposed research. The research findings are critical to the extension of current TBCs to a broader range of high-temperature materials and applications. Several tasks were originally proposed and accomplished, with additional new opportunities identified during the course of the project. In this report, a description of the project tasks, the main findings and conclusions are given. A list of publications and presentations resulted from this research is listed in the Appendix at the end of the report.

  18. The study of Zn–Co alloy coatings electrochemically deposited by pulse current

    Directory of Open Access Journals (Sweden)

    Tomić Milorad V.

    2012-01-01

    Full Text Available The electrochemical deposition by pulse current of Zn-Co alloy coatings on steel was examined, with the aim to find out whether pulse plating could produce alloys that could offer a better corrosion protection. The influence of on-time and the average current density on the cathodic current efficiency, coating morphology, surface roughness and corrosion stability in 3% NaCl was examined. At the same Ton/Toff ratio the current efficiency was insignificantly smaller for deposition at higher average current density. It was shown that, depending on the on-time, pulse plating could produce more homogenous alloy coatings with finer morphology, as compared to deposits obtained by direct current. The surface roughness was the greatest for Zn-Co alloy coatings deposited with direct current, as compared with alloy coatings deposited with pulse current, for both examined average current densities. It was also shown that Zn-Co alloy coatings deposited by pulse current could increase the corrosion stability of Zn-Co alloy coatings on steel. Namely, alloy coatings deposited with pulse current showed higher corrosion stability, as compared with alloy coatings deposited with direct current, for almost all examined cathodic times, Ton. Alloy coatings deposited at higher average current density showed greater corrosion stability as compared with coatings deposited by pulse current at smaller average current density. It was shown that deposits obtained with pulse current and cathodic time of 10 ms had the poorest corrosion stability, for both investigated average deposition current density. Among all investigated alloy coatings the highest corrosion stability was obtained for Zn-Co alloy coatings deposited with pulsed current at higher average current density (jav = 4 A dm-2.

  19. Sintering and microstructure evolution in columnar thermal barrier coatings

    International Nuclear Information System (INIS)

    Krishnamurthy, Ramanathan; Srolovitz, David J.

    2009-01-01

    Sintering of thermal barrier coatings changes their key properties, such as thermal conductivity and thermal shock resistance, thus adversely impacting their reliability. We present a novel modeling approach to study the evolution of coating structure during sintering. We model the sintering of individual columns using a thermodynamic principle, and incorporate the center-to-center approach rates for the columns calculated using this principle in a larger scale discrete dynamics model for the evolution of a large number of columns. Surface energies, grain boundary energies and strain energies associated with the deformation of the columns are all included in this framework, while sintering is assumed to occur by the concerted action of surface and grain boundary diffusion. Two sets of initial conditions corresponding to different extents of pre-sintering among neighboring columns are considered. When the extent of pre-sintering is small, we observe that small clusters containing 5-20 columns are formed. In contrast, where a larger amount of pre-sintering exists, we observe, especially at large column densities, that clusters containing 50-100 columns separated by large inter-cluster pores/channels that appear to organize themselves into a network are formed. These observations are in good agreement with recently published experimental observations. We also explain how these results can explain the development of a 'mud-crack'-like pattern

  20. Thermal Conductivity and Erosion Durability of Composite Two-Phase Air Plasma Sprayed Thermal Barrier Coatings

    Science.gov (United States)

    Schmitt, Michael P.; Rai, Amarendra K.; Zhu, Dongming; Dorfman, Mitchell R.; Wolfe, Douglas E.

    2015-01-01

    To enhance efficiency of gas turbines, new thermal barrier coatings (TBCs) must be designed which improve upon the thermal stability limit of 7 wt% yttria stabilized zirconia (7YSZ), approximately 1200 C. This tenant has led to the development of new TBC materials and microstructures capable of improved high temperature performance. This study focused on increasing the erosion durability of cubic zirconia based TBCs, traditionally less durable than the metastable t' zirconia based TBCs. Composite TBC microstructures composed of a low thermal conductivity/high temperature stable cubic Low-k matrix phase and a durable t' Low-k secondary phase were deposited via APS. Monolithic coatings composed of cubic Low-k and t' Low-k were also deposited, in addition to a 7YSZ benchmark. The thermal conductivity and erosion durability were then measured and it was found that both of the Low-k materials have significantly reduced thermal conductivities, with monolithic t' Low-k and cubic Low-k improving upon 7YSZ by approximately 13 and approximately 25%, respectively. The 40 wt% t' Low-k composite (40 wt% t' Low-k - 60 wt% cubic Low-k) showed a approximately 22% reduction in thermal conductivity over 7YSZ, indicating even at high levels, the t' Low-k secondary phase had a minimal impact on thermal in the composite coating. It was observed that a mere 20 wt% t' Low-k phase addition can reduce the erosion of a cubic Low-k matrix phase composite coating by over 37%. Various mixing rules were then investigated to assess this non-linear composite behavior and suggestions were made to further improve erosion durability.

  1. Barrier properties and storage stability of edible coatings prepared with electrospraying

    NARCIS (Netherlands)

    Khan, M.K.I.; Schutyser, M.A.I.; Schroen, C.G.P.H.; Boom, R.M.

    2014-01-01

    Electrospraying is a novel technique for the application of coating to foods. In this study, thin lipid-based coatings were prepared by electrospraying on model surface and evaluated for their moisture barrier functionality. Sunflower oil and chocolate based coating materials were electrosprayed at

  2. Anti-browning and barrier properties of edible coatings prepared with electrospraying

    NARCIS (Netherlands)

    Khan, M.K.I.; Cakmak, I.; Tavman, S.; Schutyser, M.A.I.; Schroen, C.G.P.H.

    2014-01-01

    Electrospraying is a novel technique for the application of coating to foods. In this study, thin lipid-based coatings were prepared by electrospraying on model surface and evaluated for their moisture barrier functionality. Sunflower oil and chocolate based coating materials were electrosprayed at

  3. Development and Life Prediction of Erosion Resistant Turbine Low Conductivity Thermal Barrier Coatings

    Science.gov (United States)

    Zhu, Dongming; Miller, Robert A.; Kuczmarski, Maria A.

    2010-01-01

    Future rotorcraft propulsion systems are required to operate under highly-loaded conditions and in harsh sand erosion environments, thereby imposing significant material design and durability issues. The incorporation of advanced thermal barrier coatings (TBC) in high pressure turbine systems enables engine designs with higher inlet temperatures, thus improving the engine efficiency, power density and reliability. The impact and erosion resistance of turbine thermal barrier coating systems are crucial to the turbine coating technology application, because a robust turbine blade TBC system is a prerequisite for fully utilizing the potential coating technology benefit in the rotorcraft propulsion. This paper describes the turbine blade TBC development in addressing the coating impact and erosion resistance. Advanced thermal barrier coating systems with improved performance have also been validated in laboratory simulated engine erosion and/or thermal gradient environments. A preliminary life prediction modeling approach to emphasize the turbine blade coating erosion is also presented.

  4. Thermal barrier coatings: Coating methods, performance, and heat engine applications. (Latest citations from the EI Compendex*plus database). Published Search

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-02-01

    The bibliography contains citations concerning conference proceedings on coating methods, performance evaluations, and applications of thermal barrier coatings as protective coatings for heat engine components against high temperature corrosions and chemical erosions. The developments of thermal barrier coating techniques for high performance and reliable gas turbines, diesel engines, jet engines, and internal combustion engines are presented. Topics include plasma sprayed coating methods, yttria stabilized zirconia coatings, coating life models, coating failure and durability, thermal shock and cycling, and acoustic emission analysis of coatings. (Contains 50-250 citations and includes a subject term index and title list.) (Copyright NERAC, Inc. 1995)

  5. Thermal barrier coatings: Coating methods, performance, and heat engine applications. (Latest citations from the EI Compendex*plus database). Published Search

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1995-11-01

    The bibliography contains citations concerning conference proceedings on coating methods, performance evaluations, and applications of thermal barrier coatings as protective coatings for heat engine components against high temperature corrosions and chemical erosions. The developments of thermal barrier coating techniques for high performance and reliable gas turbines, diesel engines, jet engines, and internal combustion engines are presented. Topics include plasma sprayed coating methods, yttria stabilized zirconia coatings, coating life models, coating failure and durability, thermal shock and cycling, and acoustic emission analysis of coatings. (Contains 50-250 citations and includes a subject term index and title list.) (Copyright NERAC, Inc. 1995)

  6. A study of the deposition process of multilayer coatings on the inner tube surface with the pulsed laser deposition technique

    Energy Technology Data Exchange (ETDEWEB)

    Lozovan, A.A., E-mail: loz-plasma@ya.ru; Alexandrova, S.S.; Mishnev, M.A.; Prishepov, S.V.

    2014-02-15

    Highlights: • Submitted laser bench for coatings, deposited on the inner surfaces of tubes by PLD. • Sprayed multilayered Ti/TiN coatings on the inner surfaces of tubes of small diameter. • We study this of coatings by method RBS and X-ray fluorescence spectroscopy (TXRF). • Shown a significant mixing of the layers thickness of 90 μm. -- Abstract: The multilayer Ti/TiN/Ti coatings (consisting of nano-scale layers) on the inner surface of stainless steel tubes of small diameter were studied. The coatings were deposited by using the pulsed laser deposition (PLD) technique (in the reactive and non-reactive deposition modes). The coatings were analyzed using the X-ray fluorescence analysis with total external reflection (TXRF) and the Rutherford backscattering spectroscopy (RBS). It was found that the deposition of multilayer Ti/TiN/Ti coatings leads to the essential mixing of coating layers due to sputtering of coatings with fast atoms and ions from the laser plume and the evaporation of the coating under the laser radiation reflected from the target surface.

  7. ZnS/Diamond Composite Coatings for Infrared Transmission Applications Formed by the Aerosol Deposition Method

    OpenAIRE

    Johnson, Scooter D.; Kub, Fritz J.; Eddy Jr, Charles R.

    2013-01-01

    The deposition of nano-crystalline ZnS/diamond composite protective coatings on silicon, sapphire, and ZnS substrates, as a preliminary step to coating infrared transparent ZnS substrates from powder mixtures by the aerosol deposition method is presented. Advantages of the aerosol deposition method include the ability to form dense, nanocrystalline films up to hundreds of microns thick at room temperature and at a high deposition rate on a variety of substrates. Deposition is achieved by crea...

  8. Effect of Layer-Graded Bond Coats on Edge Stress Concentration and Oxidation Behavior of Thermal Barrier Coatings

    Science.gov (United States)

    Zhu, Dongming; Ghosn, Louis J.; Miller, Robert A.

    1998-01-01

    Thermal barrier coating (TBC) durability is closely related to design, processing and microstructure of the coating Z, tn systems. Two important issues that must be considered during the design of a thermal barrier coating are thermal expansion and modulus mismatch between the substrate and the ceramic layer, and substrate oxidation. In many cases, both of these issues may be best addressed through the selection of an appropriate bond coat system. In this study, a low thermal expansion and layer-graded bond coat system, that consists of plasma-sprayed FeCoNiCrAl and FeCrAlY coatings, and a high velocity oxyfuel (HVOF) sprayed FeCrAlY coating, is developed to minimize the thermal stresses and provide oxidation resistance. The thermal expansion and oxidation behavior of the coating system are also characterized, and the strain isolation effect of the bond coat system is analyzed using the finite element method (FEM). Experiments and finite element results show that the layer-graded bond coat system possesses lower interfacial stresses. better strain isolation and excellent oxidation resistance. thus significantly improving the coating performance and durability.

  9. Boron carbide coating deposition on tungsten and testing of tungsten layers and coating under intense plasma load

    Science.gov (United States)

    Airapetov, A. A.; Begrambekov, L. B.; Buzhinskiy, O. I.; Grunin, A. V.; Gordeev, A. A.; Zakharov, A. M.; Kalachev, A. M.; Sadovskiy, Ya. A.; Shigin, P. A.

    2015-12-01

    A device intended for boron carbide coating deposition and material testing under high heat loads is presented. A boron carbide coating 5 μm thick was deposited on the tungsten substrate. These samples were subjected to thermocycling loads in the temperature range of 400-1500°C. Tungsten layers deposited on tungsten substrates were tested in similar conditions. Results of the surface analysis are presented.

  10. Boron carbide coating deposition on tungsten and testing of tungsten layers and coating under intense plasma load

    Energy Technology Data Exchange (ETDEWEB)

    Airapetov, A. A.; Begrambekov, L. B., E-mail: lbb@plasma.mephi.ru [National Research Nuclear University MEPhI (Moscow Engineering Physics Institute) (Russian Federation); Buzhinskiy, O. I. [State Research Center Troitsk Institute for Innovation and Fusion Research (TRINITI) (Russian Federation); Grunin, A. V.; Gordeev, A. A.; Zakharov, A. M.; Kalachev, A. M.; Sadovskiy, Ya. A.; Shigin, P. A. [National Research Nuclear University MEPhI (Moscow Engineering Physics Institute) (Russian Federation)

    2015-12-15

    A device intended for boron carbide coating deposition and material testing under high heat loads is presented. A boron carbide coating 5 μm thick was deposited on the tungsten substrate. These samples were subjected to thermocycling loads in the temperature range of 400–1500°C. Tungsten layers deposited on tungsten substrates were tested in similar conditions. Results of the surface analysis are presented.

  11. Microfibrillated cellulose and borax as mechanical, O₂-barrier, and surface-modulating agents of pullulan biocomposite coatings on BOPP.

    Science.gov (United States)

    Cozzolino, Carlo A; Campanella, Gaetano; Türe, Hasan; Olsson, Richard T; Farris, Stefano

    2016-06-05

    Multifunctional composite coatings on bi-oriented polypropylene (BOPP) films were obtained using borax and microfibrillated cellulose (MFC) added to the main pullulan coating polymer. Spectroscopy analyses suggested that a first type of interaction occurred via hydrogen bonding between the C6OH group of pullulan and the hydroxyl groups of boric acid, while monodiol and didiol complexation represented a second mechanism. The deposition of the coatings yielded an increase in the elastic modulus of the entire plastic substrate (from ∼2GPa of the neat BOPP to ∼3.1GPa of the P/B+/MFC-coated BOPP). The addition of MFC yielded a decrease of both static and kinetic coefficients of friction of approximately 22% and 25%, respectively, as compared to the neat BOPP. All composite coatings dramatically increased the oxygen barrier performance of BOPP, especially under dry conditions. The deposition of the high hydrophilic coatings allowed to obtain highly wettable surfaces (water contact angle of ∼18°). Copyright © 2016 Elsevier Ltd. All rights reserved.

  12. Supersonic Plasma Spray Deposition of CoNiCrAlY Coatings on Ti-6Al-4V Alloy

    Science.gov (United States)

    Caliari, F. R.; Miranda, F. S.; Reis, D. A. P.; Essiptchouk, A. M.; Filho, G. P.

    2017-06-01

    Plasma spray is a versatile technology used for production of environmental and thermal barrier coatings, mainly in the aerospace, gas turbine, and automotive industries, with potential application in the renewable energy industry. New plasma spray technologies have been developed recently to produce high-quality coatings as an alternative to the costly low-pressure plasma-spray process. In this work, we studied the properties of as-sprayed CoNiCrAlY coatings deposited on Ti-6Al-4V substrate with smooth surface ( R a = 0.8 μm) by means of a plasma torch operating in supersonic regime at atmospheric pressure. The CoNiCrAlY coatings were evaluated in terms of their surface roughness, microstructure, instrumented indentation, and phase content. Static and dynamic depositions were investigated to examine their effect on coating characteristics. Results show that the substrate surface velocity has a major influence on the coating properties. The sprayed CoNiCrAlY coatings exhibit low roughness ( R a of 5.7 μm), low porosity (0.8%), excellent mechanical properties ( H it = 6.1 GPa, E it = 155 GPa), and elevated interface toughness (2.4 MPa m1/2).

  13. In-situ formation of multiphase air plasma sprayed barrier coatings for turbine components

    Science.gov (United States)

    Subramanian, Ramesh

    2001-01-01

    A turbine component (10), such as a turbine blade, is provided which is made of a metal alloy (22) and a base, planar-grained thermal barrier layer (28) applied by air plasma spraying on the alloy surface, where a heat resistant ceramic oxide overlay material (32') covers the bottom thermal barrier coating (28), and the overlay material is the reaction product of the precursor ceramic oxide overlay material (32) and the base thermal barrier coating material (28).

  14. Electrochemical Sensor Coating Based on Electrophoretic Deposition of Au-Doped Self-Assembled Nanoparticles.

    Science.gov (United States)

    Zhang, Rongli; Zhu, Ye; Huang, Jing; Xu, Sheng; Luo, Jing; Liu, Xiaoya

    2018-02-14

    The electrophoretic deposition (EPD) of self-assembled nanoparticles (NPs) on the surface of an electrode is a new strategy for preparing sensor coating. By simply changing the deposition conditions, the electrochemical response for an analyte of deposited NPs-based coating can be controlled. This advantage can decrease the difference between different batches of sensor coating and ensure the reproducibility of each sensor. This work investigated the effects of deposition conditions (including deposition voltage, pH value of suspension, and deposition time) on the structure and the electrochemical response for l-tryptophan of sensor coating formed from Au-doped poly(sodium γ-glutamate) with pendant dopamine units nanohybrids (Au/γ-PGA-DA NBs) via the EPD method. The structure and thickness of the deposited sensor coating were measured by atomic force microscopy, which demonstrated that the structure and thickness of coating can be affected by the deposition voltage, the pH value of the suspension, and the deposition time. The responsive current for l-tryptophan of the deposited sensor coating were measured by differential pulse voltammetry, which showed that the responsive current value was affected by the structure and thickness of the deposited coating. These arguments suggested that a rich design-space for tuning the electrochemical response for analyte and a source of variability in the structure of sensor coating can be provided by the deposition conditions. When Au/γ-PGA-DA NBs were deposited on the electrode surface and formed a continuous coating with particle morphology and thinner thickness, the deposited sensor coating exhibited optimal electrochemical response for l-tryptophan.

  15. Defect Clustering and Nano-phase Structure Characterization of Multicomponent Rare Earth-Oxide-Doped Zirconia-Yttria Thermal Barrier Coatings

    Science.gov (United States)

    Zhu, Dongming; Chen, Yuan L.; Miller, Robert A.

    2004-01-01

    Advanced thermal barrier coatings (TBCs) have been developed by incorporating multicomponent rare earth oxide dopants into zirconia-based thermal barrier coatings to promote the creation of the thermodynamically stable, immobile oxide defect clusters and/or nanophases within the coating systems. In this paper, the defect clusters, induced by Nd, Gd, and Yb rare earth dopants in the zirconia-yttria thermal barrier coatings, were characterized by high-resolution transmission electron microscopy (TEM). The TEM lattice imaging, selected area diffraction (SAD), and electron energy-loss spectroscopy (EELS) analyses demonstrated that the extensive nanoscale rare earth dopant segregation exists in the plasma-sprayed and electron-physical-vapor-deposited (EB PVD) thermal barrier coatings. The nanoscale concentration heterogeneity and the resulting large lattice distortion promoted the formation of parallel and rotational defective lattice clusters in the coating systems. The presence of the 5-to 100-nm-sized defect clusters and nanophases is believed to be responsible for the significant reduction of thermal conductivity, improved sintering resistance, and long-term high temperature stability of the advanced thermal barrier coating systems.

  16. CrN-Ag nanocomposite coatings: Control of lubricant transport by diffusion barriers

    Energy Technology Data Exchange (ETDEWEB)

    Papi, P.A. [Department of Materials Science and Engineering, Rensselaer Polytechnic Institute, Troy, NY 12180 (United States); Mulligan, C.P. [Department of Materials Science and Engineering, Rensselaer Polytechnic Institute, Troy, NY 12180 (United States); U.S. Army Armament Research Development and Engineering Center, Benet Laboratories, Watervliet, NY 12189 (United States); Gall, D., E-mail: galld@rpi.edu [Department of Materials Science and Engineering, Rensselaer Polytechnic Institute, Troy, NY 12180 (United States)

    2012-12-01

    1-{mu}m-thick self-lubricating CrN-Ag composite coatings containing 16 at.% Ag were deposited on Si substrates by reactive co-sputtering at T{sub s} = 400 Degree-Sign C, and were covered with CrN cap layers with a columnar microstructure and a thickness d = 0-1000 nm. Vacuum annealing at T{sub a} = 500 and 600 Degree-Sign C for 1 h causes Ag transport to the sample surface and the formation of Ag surface grains. Quantitative scanning electron microscopy and energy dispersive spectroscopy analyses show that increasing d from 0 to 10 to 100 nm for T{sub a} = 500 Degree-Sign C leads to a decrease in the areal density of Ag surface grains from 0.86 to 0.45 to 0.04 {mu}m{sup -2}, while their lateral size remains constant at 360 {+-} 60 nm. However, increasing T{sub a} to 600 Degree-Sign C causes a doubling of the Ag grain size, and a 4-30 times larger overall Ag transport. These results are explained by kinetic barriers for Ag diffusion through the porous cap layer with a porosity that decreases with increasing d, resulting in an effective activation barrier for Ag transport that increases from 0.78 eV in the absence of a cap layer to 0.89 eV for d = 10 nm and 1.07 eV for d = 30 nm. Auger electron spectroscopy depth profile analyses of annealed layers reveal no detectable Ag within the CrN cap layer and a uniform depletion of the Ag reservoir throughout the composite coating thickness, indicating unhindered Ag transport within the composite. The overall results show that a CrN diffusion barrier cap layer is an effective approach to control Ag lubricant transport to the surface of CrN-Ag composite coatings. - Highlights: Black-Right-Pointing-Pointer CrN-Ag composite coatings are capped with CrN diffusion barriers. Black-Right-Pointing-Pointer Ag diffuses to the surface during annealing at 500 or 600 Degree-Sign C. Black-Right-Pointing-Pointer The Ag transport is controlled by the cap thickness d = 0-1000 nm. Black-Right-Pointing-Pointer The activation energy for Ag

  17. Thermocyclic behaviour of microstructurally modified EB-PVD thermal barrier coatings

    International Nuclear Information System (INIS)

    Schulz, U.; Fritscher, K.; Raetzer-Scheibe, H.-J.; Kaysser, W.A.; Peters, M.

    1997-01-01

    This paper focuses on the combined effects of substrate temperature and rotation during electron-beam physical vapor deposition (EB-PVD) on the columnar microstructure of yttria partially stabilized zirconia (YPSZ) thermal barrier coatings. Diameter and degree of ordering of the columns and the density of the coatings are sensitive to the processing parameters. Results are discussed in the frame of common structural zone models for PVD processes. The models are extended to consider the rotational effect. EB-PVD YPSZ TBCs of different column diameters were deposited on top of an EB-PVD NiCoCrAlY bondcoat on IN 100 superalloy test bars. The performance of the TBCs was investigated in a cyclic oxidation furnace test rig between 1100 C and 130 C and in a burner rig under hot gas corrosion conditions at a maximum temperature of 900 C. Results showed a correlation between cyclic lifetime and the various microstructures of the TBCs. Samples having a non-regular arrangement of columns performed best in both tests. (orig.)

  18. Low-Thermal-Conductivity Pyrochlore Oxide Materials Developed for Advanced Thermal Barrier Coatings

    Science.gov (United States)

    Bansal, Narottam P.; Zhu, Dong-Ming

    2005-01-01

    When turbine engines operate at higher temperatures, they consume less fuel, have higher efficiencies, and have lower emissions. The upper-use temperatures of the base materials (superalloys, silicon-based ceramics, etc.) used for the hot-section components of turbine engines are limited by the physical, mechanical, and corrosion characteristics of these materials. Thermal barrier coatings (TBCs) are applied as thin layers on the surfaces of these materials to further increase the operating temperatures. The current state-of-the-art TBC material in commercial use is partially yttria-stabilized zirconia (YSZ), which is applied on engine components by plasma spraying or by electron-beam physical vapor deposition. At temperatures higher than 1000 C, YSZ layers are prone to sintering, which increases thermal conductivity and makes them less effective. The sintered and densified coatings can also reduce thermal stress and strain tolerance, which can reduce the coating s durability significantly. Alternate TBC materials with lower thermal conductivity and better sintering resistance are needed to further increase the operating temperature of turbine engines.

  19. Glassy Carbon Coating Deposited on Hybrid Structure of Composite Materials

    Directory of Open Access Journals (Sweden)

    Posmyk A.

    2016-06-01

    Full Text Available This paper presents a method of production metal matrix composites with aluminum oxide foam covered by glassy carbon layer used as reinforcement. The glassy carbon coating was formed for decreasing of friction coefficient and reducing the wear. In first step of technology liquid glassy carbon precursor is on ceramic foam deposited, subsequently cured and carbonated at elevated temperature. In this way ceramic foam is covered with glassy carbon coating with thickness of 2-8 μm. It provides desirable amount of glassy carbon in the structure of the material. In the next step, porous spheres with carbon coating are infiltrated by liquid matrix of Al-Cu-Mg alloy. Thereby, equable distribution of glassy carbon in composite volume is achieved. Moreover, typical problems for composites reinforced by particles like sedimentation, agglomeration and clustering of particles are avoided. Tribological characteristics during friction in air versus cast iron as a counterpart were made. Produced composites with glassy carbon layer are characterised by friction coefficient between 0.08-0.20, thus meeting the typical conditions for solid lubricants.

  20. Interface behavior of tungsten coating on stainless steel by electro spark deposition

    Directory of Open Access Journals (Sweden)

    Wang Yuangang

    2015-01-01

    Full Text Available A new method of electro spark deposition method was put forward, which was based on the theory of electro spark deposition by changing the polarity in the liquid. Tungsten coating layers was produced on surface of Stainless Steel by electro spark deposition. The micro hardness, microstructure, chemical composition and phases of the coating layer were examined by means of hardness test, scanning electron microscopy (SEM and energy dispersive spectrometer (EDS analysis. The results showed that there was tungsten coating in the surface, which was discontinuous. Microhardness of the coating layer was about 3 times more than that of the substrate. The combination between coating layer and substrate was metallurgical bond.

  1. Oxidation and thermal shock behavior of thermal barrier coated 18/10CrNi alloy with coating modifications

    Energy Technology Data Exchange (ETDEWEB)

    Guergen, Selim [Vocational School of Transportation, Anadolu University, Eskisehir (Turkmenistan); Diltemiz, Seyid Fehmi [Turkish Air Force1st Air Supply and Maintenance Center Command, Eskisehir (Turkmenistan); Kushan, Melih Cemal [Dept. of Mechanical Engineering, Eskisehir Osmangazi University, Eskisehir (Turkmenistan)

    2017-01-15

    In this study, substrates of 18/10CrNi alloy plates were initially sprayed with a Ni-21Cr-10Al-1Y bond coat and then with an yttria stabilized zirconia top coat by plasma spraying. Subsequently, plasma-sprayed Thermal barrier coatings (TBCs) were treated with two different modification methods, namely, vacuum heat treatment and laser glazing. The effects of modifications on the oxidation and thermal shock behavior of the coatings were evaluated. The effect of coat thickness on the bond strength of the coats was also investigated. Results showed enhancement of the oxidation resistance and thermal shock resistance of TBCs following modifications. Although vacuum heat treatment and laser glazing exhibited comparable results as per oxidation resistance, the former generated the best improvement in the thermal shock resistance of the TBCs. Bond strength also decreased as coat thickness increased.

  2. Calcium-magnesium Aluminosilicate (CMAS) Interactions with Advanced Environmental Barrier Coating Material

    Science.gov (United States)

    Wiesner, Valerie L.; Bansal, Narottam P.

    2015-01-01

    Particulates, like sand and volcanic ash, threaten the development of robust environmental barrier coatings (EBCs) that protect next-generation silicon-based ceramic matrix composite (CMC) turbine engine components from harsh combustion environments during service. The siliceous particulates transform into molten glassy deposits of calcium-magnesium aluminosilicate (CMAS) when ingested by an aircraft engine operating at temperatures above 1200C. In this study, a sample of desert sand was melted into CMAS glass to evaluate high-temperature interactions between the sand glass and an advanced EBC material. Desert sand glass was added to the surface of hot-pressed EBC substrates, which were then heated in air at temperatures ranging from 1200C to 1500C. Scanning electron microscopy and X-ray energy-dispersive spectroscopy were used to evaluate microstructure and phase compositions of specimens and the CMASEBC interface after heat treatments.

  3. NASA's Advanced Environmental Barrier Coatings Development for SiC/SiC Ceramic Matrix Composites: Understanding Calcium Magnesium Alumino-Silicate (CMAS) Degradations and Resistance

    Science.gov (United States)

    Zhu, Dongming

    2014-01-01

    Environmental barrier coatings (EBCs) and SiCSiC ceramic matrix composites (CMCs) systems will play a crucial role in next generation turbine engines for hot-section component applications because of their ability to significantly increase engine operating temperatures with improved efficiency, reduce engine weight and cooling requirements. The development of prime-reliant environmental barrier coatings is essential to the viability and reliability of the envisioned CMC engine component applications, ensuring integrated EBC-CMC system durability and designs are achievable for successful applications of the game-changing component technologies and lifing methodologies.This paper will emphasize recent NASA environmental barrier coating developments for SiCSiC turbine airfoil components, utilizing advanced coating compositions, state-of-the-art processing methods, and combined mechanical and environment testing and durability evaluations. The coating-CMC degradations in the engine fatigue-creep and operating environments are particularly complex; one of the important coating development aspects is to better understand engine environmental interactions and coating life debits, and we have particularly addressed the effect of Calcium-Magnesium-Alumino-Silicate (CMAS) from road sand or volcano-ash deposits on the durability of the environmental barrier coating systems, and how the temperature capability, stability and cyclic life of the candidate rare earth oxide and silicate coating systems will be impacted in the presence of the CMAS at high temperatures and under simulated heat flux conditions. Advanced environmental barrier coating systems, including HfO2-Si with rare earth dopant based bond coat systems, will be discussed for the performance improvements to achieve better temperature capability and CMAS resistance for future engine operating conditions.

  4. Evaluation of Hydrogen Cracking in Weld Metal Deposited using Cellulosic-Coated Electrodes

    Science.gov (United States)

    2009-06-16

    Cellulosic-coated electrodes (primarily AWS EXX10-type) are traditionally used for "stovepipe" welding of pipelines because they are well suited for deposition of pipeline girth welds and are capable of high deposition rates when welding downhill. De...

  5. Factors Influencing Residual Stresses in Yttria Stabilized Zirconia Thermal Barrier Coatings

    Science.gov (United States)

    McGrann, Roy T. R.; Rybicki, Edmund F.; Shadley, John R.; Brindley, William J.

    1997-01-01

    To improve gas turbine and diesel engine performance using thermal barrier coatings (TBC's) requires an understanding of the factors that influence the in-service behavior of thermal barrier coatings. One of the many factors related to coating performance is the state of stress in the coating. The total stress state is composed of the stresses due to the in-service loading history and the residual stresses. Residual stresses have been shown to affect TBC life, the bond strength of thermal spray coatings, and the fatigue life of tungsten carbide coatings. Residual stresses are first introduced in TBC's by the spraying process due to elevated temperatures during processing and the difference in coefficients of thermal expansion of the top coat, bond coat, and substrate. Later, the residual stresses can be changed by the in-service temperature history due to a number of time and temperature dependent mechanisms, such as oxidation, creep, and sintering. Silica content has also been shown to affect sintering and the cyclic life of thermal barrier coatings. Thus, it is important to understand how the spraying process, the in-service thermal cycles, and the silica content can create and alter residual stresses in thermal barrier coatings.

  6. Influence of substrate metal alloy type on the properties of hydroxyapatite coatings deposited using a novel ambient temperature deposition technique.

    Science.gov (United States)

    Barry, J N; Cowley, A; McNally, P J; Dowling, D P

    2014-03-01

    Hydroxyapatite (HA) coatings are applied widely to enhance the level of osteointegration onto orthopedic implants. Atmospheric plasma spray (APS) is typically used for the deposition of these coatings; however, HA crystalline changes regularly occur during this high-thermal process. This article reports on the evaluation of a novel low-temperature (alloy substrates. This study addresses the suitability of the CoBlast technique for the deposition of HA coatings on a number of alternative metal alloys utilized in the fabrication of orthopedic devices. In addition to titanium grade 5, both cobalt chromium and stainless steel 316 were investigated. In this study, HA coatings were deposited using both the CoBlast and the plasma sprayed techniques, and the resultant HA coating and substrate properties were evaluated and compared. The CoBlast-deposited HA coatings were found to present similar surface morphologies, interfacial properties, and composition irrespective of the substrate alloy type. Coating thickness however displayed some variation with the substrate alloy, ranging from 2.0 to 3.0 μm. This perhaps is associated with the electronegativity of the metal alloys. The APS-treated samples exhibited evidence of both coating, and significantly, substrate phase alterations for two metal alloys; titanium grade 5 and cobalt chrome. Conversely, the CoBlast-processed samples exhibited no phase changes in the substrates after depositions. The APS alterations were attributed to the brief, but high-intensity temperatures experienced during processing. Copyright © 2013 Wiley Periodicals, Inc.

  7. Low Thermal Conductivity, High Durability Thermal Barrier Coatings for IGCC Environments

    Energy Technology Data Exchange (ETDEWEB)

    Jordan, Eric [Univ. of Connecticut, Storrs, CT (United States); Gell, Maurice [Univ. of Connecticut, Storrs, CT (United States)

    2015-01-15

    Advanced thermal barrier coatings (TBC) are crucial to improved energy efficiency in next generation gas turbine engines. The use of traditional topcoat materials, e.g. yttria-stabilized zirconia (YSZ), is limited at elevated temperatures due to (1) the accelerated undesirable phase transformations and (2) corrosive attacks by calcium-magnesium-aluminum-silicate (CMAS) deposits and moisture. The first goal of this project is to use the Solution Precursor Plasma Spray (SPPS) process to further reduce the thermal conductivity of YSZ TBCs by introducing a unique microstructural feature of layered porosity, called inter-pass boundaries (IPBs). Extensive process optimization accompanied with hundreds of spray trials as well as associated SEM cross-section and laser-flash measurements, yielded a thermal conductivity as low as 0.62 Wm⁻¹K⁻¹ in SPPS YSZ TBCs, approximately 50% reduction of APS TBCs; while other engine critical properties, such as cyclic durability, erosion resistance and sintering resistance, were characterized to be equivalent or better than APS baselines. In addition, modifications were introduced to SPPS TBCs so as to enhance their resistance to CMAS under harsh IGCC environments. Several mitigation approaches were explored, including doping the coatings with Al₂O₃ and TiO₂, applying a CMAS infiltration-inhibiting surface layer, and filling topcoat cracks with blocking substances. The efficacy of all these modifications was assessed with a set of novel CMAS-TBC interaction tests, and the moisture resistance was tested in a custom-built high-temperature moisture rig. In the end, the optimal low thermal conductivity TBC system was selected based on all evaluation tests and its processing conditions were documented. The optimal coating consisted on a thick inner layer of YSZ coating made by the SPPS process having a thermal conductivity 50% lower than standard YSZ coatings topped with a high temperature tolerant CMAS resistant gadolinium

  8. Development of Nitride Coating Using Atomic Layer Deposition for Low-Enriched Uranium Fuel Powder

    Science.gov (United States)

    Bhattacharya, Sumit

    High-performance research reactors require fuel that operates at high specific power and can withstand high fission density, but at relatively low temperatures. The design of the research reactor fuels is done for efficient heat emission, and consists of assemblies of thin-plates cladding made from aluminum alloy. The low-enriched fuels (LEU) were developed for replacing high-enriched fuels (HEU) for these reactors necessitates a significantly increased uranium density in the fuel to counterbalance the decrease in enrichment. One of the most promising new fuel candidate is U-Mo alloy, in a U-Mo/Al dispersion fuel form, due to its high uranium loading as well as excellent irradiation resistance performance, is being developed extensively to convert from HEU fuel to LEU fuel for high-performance research reactors. However, the formation of an interaction layer (IL) between U-Mo particles and the Al matrix, and the associated pore formation, under high heat flux and high burnup conditions, degrade the irradiation performance of the U-Mo/Al dispersion fuel. From the recent tests results accumulated from the surface engineering of low enriched uranium fuel (SELENIUM) and MIR reactor displayed that a surface barrier coating like physical vapor deposited (PVD) zirconium nitride (ZrN) can significantly reduce the interaction layer. The barrier coating performed well at low burn up but above a fluence rate of 5x 1021 ions/cm2 the swelling reappeared due to formation interaction layer. With this result in mind the objective of this research was to develop an ultrathin ZrN coating over particulate uranium-molybdenum nuclear fuel using a modified savannah 200 atomic layer deposition (ALD) system. This is done in support of the US Department of Energy's (DOE) effort to slow down the interaction at fluence rate and reach higher burn up for high power research reactor. The low-pressure Savannah 200 ALD system is modified to be designed as a batch powder coating system using the

  9. High efficient vacuum arc plant for coating deposition

    International Nuclear Information System (INIS)

    Aksenov, I.I.; Belous, V.A.

    2008-01-01

    A number of progressive technical solutions are used in the 'Bulat-9' machine designed for vacuum arc coating deposition. The features of the machine are: a dome shaped working chamber that allows to 'wash' its inner surfaces with hot nitrogen or argon gas; a system of automatic loading/unloading of articles to be treated into the chamber through its bottom; shielding of the inner surfaces of the chamber by heated panels; improved vacuum arc plasma sources including filtered one; four ported power supply for the vacuum arc discharges; LC oscillatory circuits suppressing microarcs on the substrate; the system of automatic control of a working process. The said technical features cause the apparatus originality and novelty preserved up to-day

  10. Double dielectric barrier (DBD) plasma-assisted deposition of chemical stabilized nanoparticles on polyamide 6,6 and polyester fabrics

    Science.gov (United States)

    Ribeiro, A. I.; Modic, M.; Cvelbar, U.; Dinescu, G.; Mitu, B.; Nikiforov, A.; Leys, C.; Kuchakova, I.; Vanneste, M.; Heyse, P.; De Vrieze, M.; Carneiro, N.; Souto, A. P.; Zille, A.

    2017-10-01

    The development of new multifunctional textiles containing nanoparticles (NPs) has a special interest in several applications for pharmaceutical and medical products. Cu, Zn and Ag are the most promising antimicrobial NPs, exhibiting strong antibacterial activities. However, most of antimicrobial textiles coated with NPs are not able to perform a controlled release of NPs because of the high degree of aggregation. The aim of this study is to assess the effect of NPs stabilizers such as citrate, alginate and polyvinyl alcohol (PVA) in Cu, Zn and Ag NPs dispersions. The obtained dispersions were used to develop a new class of antibacterial NPs coatings onto polyamide 6,6 (PA66) and polyester fabrics (PES) by Double Dielectric Barrier (DBD) plasma discharge. Dynamic light scattering (DLS) was used to evaluate the best dispersing agent in terms of size, polydispersity index and zeta potential. Coating efficiency was evaluated by SEM, XPS and FTIR. The washing fastness of the coatings developed was also tested. The results show that the best dispersions were obtained using 2.5% of citrate for ZnO, 5% Alginate for Cu and 2.5% alginate for Ag NPs. SEM, XPS and FTIR analysis shows that DBD is an efficient deposition technique only for Ag and Cu NPs and that better perform in PA66 than PES fabric. The DBD deposition in air display similar results in term of NPS deposition of usually more efficient plasma jets using carrier gas such as N2 and Ar.

  11. Deposition of titanium coating on SiC fiber by chemical vapor deposition with Ti-I{sub 2} system

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Xian, E-mail: luo_shenfan@hotmail.com; Wu, Shuai; Yang, Yan-qing; Jin, Na; Liu, Shuai; Huang, Bin

    2017-06-01

    Highlights: • The transformation paths of (Ti + I{sub 2}) powder to Ti coating is: Ti + I{sub 2} → (TiI{sub 2}, TiI{sub 3}) → Ti. • Uniform coating was obtained on SiC fiber, but it contained Si and C elements. • Deposition rate of the coating increased with the increase of temperature. • Deposition thickness increased with time and achieved the maximum at 90 min. - Abstract: Titanium coating was prepared on SiC fiber using titanium-iodine (Ti-I{sub 2}) mixture by hot-wall chemical vapor deposition. Thermodynamic analysis and experimental observation were carried out in this work. The thermodynamic analysis of the reactions in the Ti-I{sub 2} system indicates that Ti and I{sub 2} raw powder materials transform to titanium coating as follows: Ti + I{sub 2} → (TiI{sub 2}, TiI{sub 3}), and (TiI{sub 2}, TiI{sub 3}) → Ti. In theory, the conversions of TiI{sub 3} and TiI{sub 2} reach the maximum when Ti:I{sub 2} is 1:1.5, while in actual experiment that reached the maximum when Ti:I{sub 2} was 1:2, as there existed the waste of I{sub 2} due to sublimation. Typical deposited coating is relatively flat and uniform. However, as SiC is prone to react with Ti at high temperatures, the obtained coating contained some Si and C elements except for Ti. So the coating was not a pure Ti coating but contained some carbides and silicides. Deposition rate of the coating increased with the increase of temperature. The deposited thickness increased with the increase of heat preservation time, and achieved the maximum thickness at 90 min.

  12. Thiol-modified gold-coated glass as an efficient hydrophobic substrate for drop coating deposition Raman (DCDR) technique

    Czech Academy of Sciences Publication Activity Database

    Kočišová, E.; Procházka, M.; Šípová, Hana

    2016-01-01

    Roč. 47, č. 11 (2016), s. 1394-1396 ISSN 0377-0486 R&D Projects: GA ČR(CZ) GBP205/12/G118 Institutional support: RVO:67985882 Keywords : thiol-modified Au-coated glass * drop coating deposition Raman * liposome Subject RIV: BH - Optics, Masers, Lasers Impact factor: 2.969, year: 2016

  13. Surface Cracking and Interface Reaction Associated Delamination Failure of Thermal and Environmental Barrier Coatings

    National Research Council Canada - National Science Library

    Zhu, Dongming

    2003-01-01

    ...%Y2O3 and mullite/BSAS/Si thermal and environmental barrier coating system on SiC/SiC ceramic matrix composites were characterized after long-term combined laser thermal gradient and furnace cyclic...

  14. Properties of DLC coatings deposited by dc and dc with superimposed pulsed vacuum arc

    International Nuclear Information System (INIS)

    Zavaleyev, V.; Walkowicz, J.; Aksyonov, D.S.; Luchaninov, A.A.; Reshetnyak, E.N.; Strel'nitskij, V.E.

    2014-01-01

    Comparative studies of the structure, mechanical and tribological properties of DLC coatings deposited in DC and DC with superimposed high current pulse modes of operation vacuum-arc plasma source with the graphite cathode are presented. Imposition the pulses of high current on DC vacuum-arc discharge allows both increase the deposition rate of DLC coating and reduce the residual compressive stress in the coatings what promotes substantial improvement the adhesion to the substrate. Effect of vacuum arc plasma filtration with Venetian blind filter on the deposition rate and tribological characteristics of the coatings analyzed.

  15. Electrochemical deposition of coatings of highly entropic alloys from non-aqueous solutions

    Directory of Open Access Journals (Sweden)

    Jeníček V.

    2016-03-01

    Full Text Available The paper deals with electrochemical deposition of coatings of highly entropic alloys. These relatively new materials have been recently intensively studied. The paper describes the first results of electrochemical coating with highly entropic alloys by deposition from non-aqueous solutions. An electrochemical device was designed and coatings were deposited. The coatings were characterised with electronic microscopy scanning, atomic absorption spectrometry and X-ray diffraction methods and the combination of methods of thermic analysis of differential scanning calorimetry and thermogravimetry.

  16. Evaluation of Degradation of Isothermally Aged Plasma-Sprayed Thermal Barrier Coating

    Energy Technology Data Exchange (ETDEWEB)

    Koo, Jae Mean; Seok, Chang Sung; Kang, Min Sung; Kim, Dae Jin [Sungkyunkwan University, Seoul (Korea, Republic of); Lee, Dong Hoon [HYUNDAI STEEL CO., Incheon (Korea, Republic of); Kim, Mun Young [KPS Gas Turbine Technology Service Center, Seongnam (Korea, Republic of)

    2010-04-15

    The thermal barrier coating of a gas turbine blade was degraded by isothermal heating in a furnace and by varying the exposure time and temperature. Then, a micro-Vickers hardness test was conducted on the cross section of the bond coat and Ni-based superalloy substrate. Further, the thickness of TGO(Thermally Grown Oxide) was measured by using an image analyzer, and the changes in the microstructure and element contents in the coating were analyzed by using an optical microscope and by performing SEM-EDX analysis. No significant change was observed in the Vickers hardness of the bond coat when the coated specimen was degraded at a high temperature: delamination was observed between the top coat and the bond coat when the coating was degraded for 50 h at a temperature 1,151 .deg. C.

  17. Study of ion implantation in grown layers of multilayer coatings under ion-plasma vacuum deposition

    International Nuclear Information System (INIS)

    Voevodin, A.A.; Erokhin, A.L.

    1993-01-01

    The model of ion implantation into growing layers of a multilayer coating produced with vacuum ion-plasma deposition was developed. The model takes into account a possibility for ions to pass through the growing layer and alloys to find the distribution of implanted atoms over the coating thickness. The experimental vitrification of the model was carried out on deposition of Ti and TiN coatings

  18. Effects of yttrium, aluminum and chromium concentrations in bond coatings on the performance of zirconia-yttria thermal barriers

    Science.gov (United States)

    Stecura, S.

    1980-01-01

    A cyclic furnace study was conducted on thermal barrier systems to evaluate the effects of yttrium, chromium and aluminum in nickel-base alloy bond coatings and the effect of bond coating thickness on yttria-stabilized zirconia thermal barrier coating life. Without yttrium in the bond coatings, the zirconia coatings failed very rapidly. Increasing chromium and aluminum in the Ni-Cr-Al-Y bond coatings increased total coating life. This effect was not as great as that due to yttrium. Increased bond coat thickness was also found to increase life.

  19. The Lattice and Thermal Radiation Conductivity of Thermal Barrier Coatings: Models and Experiments

    Science.gov (United States)

    Zhu, Dongming; Spuckler, Charles M.

    2010-01-01

    The lattice and radiation conductivity of ZrO2-Y2O3 thermal barrier coatings was evaluated using a laser heat flux approach. A diffusion model has been established to correlate the coating apparent thermal conductivity to the lattice and radiation conductivity. The radiation conductivity component can be expressed as a function of temperature, coating material scattering, and absorption properties. High temperature scattering and absorption of the coating systems can be also derived based on the testing results using the modeling approach. A comparison has been made for the gray and nongray coating models in the plasma-sprayed thermal barrier coatings. The model prediction is found to have a good agreement with experimental observations.

  20. Overview on Recent Developments of Bondcoats for Plasma-Sprayed Thermal Barrier Coatings

    Science.gov (United States)

    Naumenko, D.; Pillai, R.; Chyrkin, A.; Quadakkers, W. J.

    2017-12-01

    The performance of MCrAlY (M = Ni, Co) bondcoats for atmospheric plasma-sprayed thermal barrier coatings (APS-TBCs) is substantially affected by the contents of Co, Ni, Cr, and Al as well as minor additions of Y, Hf, Zr, etc., but also by manufacturing-related properties such as coating thickness, porosity, surface roughness, and oxygen content. The latter properties depend in turn on the exact technology and set of parameters used for bondcoat deposition. The well-established LPPS process competes nowadays with alternative technologies such as HVOF and APS. In addition, new technologies have been developed for bondcoats manufacturing such as high-velocity APS or a combination of HVOF and APS for application of a flashcoat. Future developments of the bondcoat systems will likely include optimization of thermal spraying methods for obtaining complex bondcoat roughness profiles required for extended APS-TBC lifetimes. Introduction of the newest generation single-crystal superalloys possessing low Cr and high Al and refractory metals (Re, Ru) contents will require definition of new bondcoat compositions and/or multilayered bondcoats to minimize interdiffusion issues. The developments of new bondcoat compositions may be substantially facilitated using thermodynamic-kinetic modeling, the vast potential of which has been demonstrated in recent years.

  1. Mechanical properties of EB-PVD ZrO2 thermal barrier coatings

    International Nuclear Information System (INIS)

    Held, Carolin

    2014-01-01

    In this work, the elastic properties of thermal barrier coatings which were produced by electron-beam enhanced physical vapour deposition were investigated, as well as the dependency of the properties on the sample microstructure, the thermal treatment and the test method. For this purpose, not only commercial coatings were characterized, but also special sample material was used which consists of a 1 mm thick layer of EB-PVD TBC. This material was isothermally heat treated for different times at 950 C, 1100 C and 1200 C and then tested in a specially developed miniaturized bend test and by dynamic mechanical analysis. The sample material was tested by nanoindentation in order to measure the Young's modulus on a local scale, and the porosity of the samples was determined by microstructure analysis and porosimetry. The decrease of porosity could be connected with sintering and subsequent stiffening of the material. The test results are dependent on the tested volume. A small test volume leads to larger measured Young's moduli, while a large test volume yields lower values. The test volume also has an influence on the increase of stiffness during thermal exposure. With a small tested volume, a quicker increase of the Young's modulus was registered, which could be associated to the sintering of local structures.

  2. Mid-Infrared Reflectance Imaging of Thermal-Barrier Coatings

    Science.gov (United States)

    Edlridge, Jeffrey I.; Martin, Richard E.

    2009-01-01

    An apparatus for mid-infrared reflectance imaging has been developed as means of inspecting for subsurface damage in thermal-barrier coatings (TBCs). The apparatus is designed, more specifically, for imaging the progression of buried delamination cracks in plasma-sprayed yttria-stabilized zirconia coatings on turbine-engine components. Progression of TBC delamination occurs by the formation of buried cracks that grow and then link together to produce eventual TBC spallation. The mid-infrared reflectance imaging system described here makes it possible to see delamination progression that is invisible to the unaided eye, and therefore give sufficiently advanced warning before delamination progression adversely affects engine performance and safety. The apparatus (see figure) includes a commercial mid-infrared camera that contains a liquid-nitrogen-cooled focal plane indium antimonide photodetector array, and imaging is restricted by a narrow bandpass centered at wavelength of 4 microns. This narrow wavelength range centered at 4 microns was chosen because (1) it enables avoidance of interfering absorptions by atmospheric OH and CO2 at 3 and 4.25 microns, respectively; and (2) the coating material exhibits maximum transparency in this wavelength range. Delamination contrast is produced in the midinfrared reflectance images because the introduction of cracks into the TBC creates an internal TBC/air-gap interface with a high diffuse reflectivity of 0.81, resulting in substantially higher reflectance of mid-infrared radiation in regions that contain buried delamination cracks. The camera is positioned a short distance (.12 cm) from the specimen. The mid-infrared illumination is generated by a 50-watt silicon carbide source positioned to the side of the mid-infrared camera, and the illumination is collimated and reflected onto the specimen by a 6.35-cm-diameter off-axis paraboloidal mirror. Because the collected images are of a steady-state reflected intensity (in

  3. Optimization of High Porosity Thermal Barrier Coatings Generated with a Porosity Former

    Czech Academy of Sciences Publication Activity Database

    Medřický, J.; Curry, N.; Pala, Zdeněk; Vilémová, Monika; Chráska, Tomáš; Johansson, J.; Markocsan, N.

    2015-01-01

    Roč. 24, č. 4 (2015), s. 622-628 ISSN 1059-9630 R&D Projects: GA ČR GB14-36566G Institutional support: RVO:61389021 Keywords : gas turbines * high temperature application * porosity of coatings * stabilized zirconia * thermal barrier coatings (TBCs) Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass Impact factor: 1.568, year: 2015

  4. Factors influencing the deposition of hydroxyapatite coating onto hollow glass microspheres

    International Nuclear Information System (INIS)

    Jiao, Yan; Xiao, Gui-Yong; Xu, Wen-Hua; Zhu, Rui-Fu; Lu, Yu-Peng

    2013-01-01

    Hydroxyapatite (HA) and HA coated microcarriers for cell culture and delivery have attracted more attention recently, owing to the rapid progress in the field of tissue engineering. In this research, a dense and uniform HA coating with the thickness of about 2 μm was successfully deposited on hollow glass microspheres (HGM) by biomimetic process. The influences of SBF concentration, immersion time, solid/liquid ratio and activation of HGM on the deposition rate and coating characteristics were discussed. X-ray diffraction (XRD) and Fourier transform infrared spectrum (FTIR) analyses revealed that the deposited HA is poorly crystalline. The thickness of HA coating showed almost no increase after immersion in 1.5SBF for more than 15 days with the solid/liquid ratio of 1:150. At the same time, SBF concentration, solid/liquid ratio and activation treatment played vital roles in the formation of HA coating on HGM. This poorly crystallized HA coated HGM could have potential use as microcarrier for cell culture. Highlights: • HA coatings were deposited on hollow glass microspheres by biomimetic process. • The obtained HA coating was poorly crystalline and carbonated. • The influencing factors of deposition rate and coating characteristics were studied. • The thickness of HA coating showed almost no increase after immersion for 15 days

  5. Water vapour barrier performance of corn-zein coated polypropylene (PP) packaging films

    OpenAIRE

    Atik, İsa Doğan; Özen, Fatma Banu; Tıhmınlıoğlu, Funda

    2008-01-01

    The novel film structure of corn-zein coated on polypropylene (PP) synthetic film for packaging industry was developed to examine the feasibility of resulting coated films as an alternative water barrier performance for food packaging. The effects of coating formulation (solvent, corn-zein, plasticizer concentration and plasticizer type) on final properties of films were observed. Corn-zein is the most important protein of corn and has good film forming property. Composites structures of PP f...

  6. Effect of negative bias on TiAlSiN coating deposited on nitrided Zircaloy-4

    Science.gov (United States)

    Jun, Zhou; Zhendong, Feng; Xiangfang, Fan; Yanhong, Liu; Huanlin, Li

    2018-01-01

    TiAlSiN coatings were deposited on the nitrided Zircaloy-4 by multi-arc ion plating at -100 V, -200 V and -300 V. In this study, the high temperature oxidation behavior of coatings was tested by a box-type resistance furnace in air for 3 h at 800 °C; the macro-morphology of coatings was observed and analyzed by a zoom-stereo microscope; the micro-morphology of coatings was analyzed by a scanning electron microscopy (SEM), and the chemical elements of samples were analyzed by an energy dispersive spectroscopy(EDS); the adhesion strength of the coating to the substrate was measured by an automatic scratch tester; and the phases of coatings were analyzed by an X-ray diffractometer(XRD). Results show that the coating deposited at -100 V shows better high temperature oxidation resistance behavior, at the same time, Al elements contained in the coating is of the highest amount, meanwhile, the adhesion strength of the coating to the substrate is the highest, which is 33N. As the bias increases, high temperature oxidation resistance behavior of the coating weakens first and then increases, the amount of large particles on the surface of the coating increases first and then decreases whereas the density of the coating decreases first and then increases, and adhesion strength of the coating to the substrate increases first and then weakens. The coating's quality is relatively poor when the bias is -200 V.

  7. Application of High-Velocity Oxygen-Fuel (HVOF Spraying to the Fabrication of Yb-Silicate Environmental Barrier Coatings

    Directory of Open Access Journals (Sweden)

    Emine Bakan

    2017-04-01

    Full Text Available From the literature, it is known that due to their glass formation tendency, it is not possible to deposit fully-crystalline silicate coatings when the conventional atmospheric plasma spraying (APS process is employed. In APS, rapid quenching of the sprayed material on the substrate facilitates the amorphous deposit formation, which shrinks when exposed to heat and forms pores and/or cracks. This paper explores the feasibility of using a high-velocity oxygen-fuel (HVOF process for the cost-effective fabrication of dense, stoichiometric, and crystalline Yb2Si2O7 environmental barrier coatings. We report our findings on the HVOF process optimization and its resultant influence on the microstructure development and crystallinity of the Yb2Si2O7 coatings. The results reveal that partially crystalline, dense, and vertical crack-free EBCs can be produced by the HVOF technique. However, the furnace thermal cycling results revealed that the bonding of the Yb2Si2O7 layer to the Silicon bond coat needs to be improved.

  8. Development of barrier coatings for cellulosic-based materials by cold plasma methods

    Science.gov (United States)

    Denes, Agnes Reka

    Cellulose-based materials are ideal candidates for future industries that need to be based on environmentally safe technologies and renewable resources. Wood represents an important raw material and its application as construction material is well established. Cellophane is one of the most important cellulosic material and it is widely used as packaging material in the food industry. Outdoor exposure of wood causes a combination of physical and chemical degradation processes due to the combined effects of sunlight, moisture, fungi, and bacteria. Cold-plasma-induced surface modifications are an attractive way for tailoring the characteristics of lignocellulosic substrates to prevent weathering degradation. Plasma-polymerized hexamethyldisiloxane (PPHMDSO) was deposited onto wood surfaces to create water repellent characteristics. The presence of a crosslinked macromolecular structure was detected. The plasma coated samples exhibited very high water contact angle values indicating the existence of hydrophobic surfaces. Reflective and electromagnetic radiation-absorbent substances were incorporated with a high-molecular-weight polydimethylsiloxane polymer in liquid phase and deposited as thin layers on wood surfaces. The macromolecular films, containing the dispersed materials, were then converted into a three dimensional solid state network by exposure to a oxygen-plasma. It was demonstrated that both UV-absorbent and reflectant components incorporated into the plasma-generated PDMSO matrix protected the wood from weathering degradation. Reduced oxidation and less degradation was observed after simulated weathering. High water contact angle values indicated a strong hydrophobic character of the oxygen plasma-treated PDMSO-coated samples. Plasma-enhanced surface modifications and coatings were employed to create water-vapor barrier layers on cellophane substrate surfaces. HMDSO was selected as a plasma gas and oxygen was used to ablate amorphous regions. Oxygen plasma

  9. Microstructure and durability of zirconia thermal barrier coatings

    International Nuclear Information System (INIS)

    Suhr, D.S.; Mitchell, T.E.; Keller, R.J.

    1983-01-01

    Various combinations of plasma-sprayed bond coatings and zirconia ceramic coatings on a nickel-based superalloy substrate were tested by static thermal exposure at 1200 0 C and cyclic thermal exposure to 1000 0 C. The bond coats were based on Ni-Cr-Al alloys with additions of rare earth elements and Si. The ceramic coats were various ZrO 2 -Y 2 O 3 compositions, of which the optimum was found to be ZrO 2 -8.9 wt% Y 2 O 3 . Microstructural analysis showed that resistance to cracking during thermal exposure is strongly related to deleterious phase changes

  10. Effect of coating thickness on microstructure and low temperature cyclic thermal fatigue behavior of thermal barrier coating (Al2O3)

    Science.gov (United States)

    Verma, Vijay; Patel, Sachin; Swarnkar, Vikas; K, Rajput S.

    2018-03-01

    Effect of coating thickness on low temperature cyclic thermal fatigue behaviour of Al2O3 thermal barrier coating (TBC) was concluded through the cyclic furnace thermal fatigue test (CFTF). Detonation gun (Thermal Spray) process was used for bond coating of NiCr and top coating of Al2O3 on Aluminium Alloy 6061 substrate. Top coating was done at two level of thickness to investigate the effect of coating thickness on low temperature cyclic thermal fatigue. The top coat of thickness 100μm-150μm was considered as thin TBC while the top coat of thickness 250μm-300μm was considered as thick TBC. The thickness of bond coat was taken as 120μm constant for both level of Al2O3 top coating. During CFTF test appearance of any crack on coated surface was adapted as main criterion of coating failure. Crack initiation was observed at edges and corner of thin thermal barrier coating after 60 number of thermal fatigue cycles while in case of thick thermal barrier coating these crack initiation was observed after 72 cycles of cyclic thermal fatigue test. During the study, it was observed that thick thermal barrier coating survived for long duration in comparison of thin TBC. Hence it can be concluded that application of thick TBC is more favourable to improve thermal durability of any component.

  11. Mechanical Properties and Durability of Advanced Environmental Barrier Coatings in Calcium-Magnesium-Alumino-Silicate Environments

    Science.gov (United States)

    Miladinovich, Daniel S.; Zhu, Dongming

    2011-01-01

    Environmental barrier coatings are being developed and tested for use with SiC/SiC ceramic matrix composite (CMC) gas turbine engine components. Several oxide and silicate based compositons are being studied for use as top-coat and intermediate layers in a three or more layer environmental barrier coating system. Specifically, the room temperature Vickers-indentation-fracture-toughness testing and high-temperature stability reaction studies with Calcium Magnesium Alumino-Silicate (CMAS or "sand") are being conducted using advanced testing techniques such as high pressure burner rig tests as well as high heat flux laser tests.

  12. Single-walled carbon nanotubes/hydroxyapatite coatings on titanium obtained by electrochemical deposition

    Energy Technology Data Exchange (ETDEWEB)

    Pei, Xibo; Zeng, Yongxiang [State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu 610041 (China); Department of Prosthodontics, West China Hospital of Stomatology, Sichuan University, Chengdu 610041 (China); He, Rui [State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu 610041 (China); Department of Stomatology, the Affiliated Hospital of Hangzhou Normal University, Hangzhou 310015 (China); Li, Zhongjie; Tian, Lingyang [State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu 610041 (China); Department of Prosthodontics, West China Hospital of Stomatology, Sichuan University, Chengdu 610041 (China); Wang, Jian, E-mail: fero@scu.edu.cn [State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu 610041 (China); Department of Prosthodontics, West China Hospital of Stomatology, Sichuan University, Chengdu 610041 (China); Wan, Qianbing, E-mail: pxb1024@hotmail.com [State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu 610041 (China); Department of Prosthodontics, West China Hospital of Stomatology, Sichuan University, Chengdu 610041 (China); Li, Xiaoyu [State Key Laboratory of Oral Diseases, West China Hospital of Stomatology, Sichuan University, Chengdu 610041 (China); Bao, Hong [Department of Stomatology, Hospital of Chengdu Office of People' s Government of Tibetan Autonomous Region, Chengdu 610000 (China)

    2014-03-01

    Graphical abstract: - Highlights: • The incorporation of SWNTs into the HA coating leaded to the formation of homogeneous and crack-free composite coatings. • The highest bonding strength was detected for the SWNTs/HA-0.5 composite coating (25.70 MPa). • The SWNTs/HA composite coatings induced better cell proliferation, cell viability and ALP activity compared to pure HA coating and pure Ti. • The results suggested that SWNTs/HA-0.5 and SWNTs/HA-1.0 composite coating prepared in this work is acceptable in terms of mechanical property and in-vitro bioactivity. - Abstract: Single-walled carbon nanotubes/hydroxyapatite (SWNTs/HA) composite coatings were successfully fabricated by electrochemical deposition technique. Different concentrations of SWNTs were incorporated into the apatite coating by adding functionalized SWNTs into the electrolyte. Homogeneous and crack-free SWNTs/HA composite coatings were achieved and the coatings had higher crystallinity compared to pure HA coating. In addition, the highest bonding strength of the SWNTs/HA coating reached 25.7 MPa, which was nearly 70% higher than that of pure HA coating. The in-vitro cellular biocompatibility tests revealed that SWNTs/HA composite coatings exhibited higher in-vitro bioactivity than that of pure HA coating and pure titanium (Ti). It suggests that SWNTs/HA composite coating may have enormous potential applications in the field of biomaterials, especially for the metal implants.

  13. Beeswax–chitosan emulsion coated paper with enhanced water vapor barrier efficiency

    International Nuclear Information System (INIS)

    Zhang, Weiwei; Xiao, Huining; Qian, Liying

    2014-01-01

    Graphical abstract: - Highlights: • The water vapor barrier efficiency of paper was enhanced via green-based emulsion coating. • Extremely high lipid content in the emulsion coating layer was firstly utilized to reduce WVTR in emulsion-based film. • A controlled WVTR of beeswax–chitosan emulsion coating could be obtained by dying at specific temperature. - Abstract: For lipid–hydrocolloid emulsion based film, the increase of lipid amount would improve its water vapor barrier property, but also reduce the mechanical strength of the film in the meantime thus leading to a compromised lipid content in the film. However, when the emulsion is coated on paper surface, more lipid could be used for emulsion preparation to enhance the moisture resistance without considering the weakened strength of the film induced by lipid, because the mechanical properties of emulsion coated paper is mainly governed by the strength of base paper instead of the coating layer. In this study, beeswax–chitosan emulsion was first prepared and then coated on paper surface to improve paper's water vapor barrier and water resistance properties. The range and variance analysis of orthogonal test design showed that the order of priorities of the factors accordingly was beeswax solid content, drying temperature and chitosan concentration. The effect of drying temperature on water vapor transmission rate (WVTR) and water contact angle of coated paper was further investigated using 1.2 wt% chitosan and 96% beeswax solid content in the coating layer. The results indicated that water vapor barrier property was in accordance with the density of the coating layer. Atomic force microscope (AFM) was also used to characterize the surface morphology and explain the hydrophobicity of beeswax–chitosan coated paper. It was found that surface beeswax particles melted to wrinkle at high drying temperatures, while roughness values maintained at micro-scale over the temperature range investigated

  14. Advanced Environmental Barrier Coating Development for SiC/SiC Ceramic Matrix Composites: NASA's Perspectives

    Science.gov (United States)

    Zhu, Dongming

    2016-01-01

    This presentation reviews NASA environmental barrier coating (EBC) system development programs and the coating materials evolutions for protecting the SiC/SiC Ceramic Matrix Composites in order to meet the next generation engine performance requirements. The presentation focuses on several generations of NASA EBC systems, EBC-CMC component system technologies for SiC/SiC ceramic matrix composite combustors and turbine airfoils, highlighting the temperature capability and durability improvements in simulated engine high heat flux, high pressure, high velocity, and with mechanical creep and fatigue loading conditions. The current EBC development emphasis is placed on advanced NASA 2700F candidate environmental barrier coating systems for SiC/SiC CMCs, their performance benefits and design limitations in long-term operation and combustion environments. Major technical barriers in developing environmental barrier coating systems, the coating integrations with next generation CMCs having the improved environmental stability, erosion-impact resistance, and long-term fatigue-environment system durability performance are described. The research and development opportunities for advanced turbine airfoil environmental barrier coating systems by utilizing improved compositions, state-of-the-art processing methods, and simulated environment testing and durability modeling are discussed.

  15. FAILURE MECHANISMS OF THERMAL BARRIER COATINGS INTERNAL COMBUSTION ENGINES AND llMPROVEMENTS

    Directory of Open Access Journals (Sweden)

    ADNAN PARLAK

    2003-04-01

    Full Text Available MechanicaJ properties of high performance ceramics have been improved to the point where their use in heat engines is possible. The high temperature strength and low thermal expansion properties of bigh performance ceramics offer an advantage over metals in the development of non-water cooling engine. However, because bard environment in diesel engine combustion chamber, solving the problem of durabiUty of TBC is important. DurabiUty of thermal barrier coatings(TBC is liınited by two main failure mechanisms: Therınal expansion nlİsmatch betwcen bond coat and top coat and bond coat oxidation. Both of these can cause failure of the ceramic top coat. Developments of recent years sholv that bond coats \\Vith higher oxidation resistance tend to have better coating system cyclic lives

  16. Development of coatings for ultrasonic additive manufacturing sonotrode using laser direct metal deposition process

    Energy Technology Data Exchange (ETDEWEB)

    Niyanth S, Niyanth [ORNL; Dehoff, Ryan R [ORNL; Jordan, Brian H [ORNL; Babu, Sudarsanam Suresh [ORNL

    2016-10-01

    ORNL partnered with Fabrisonic, LLC to develop galling resistant hard facing coatings on sonotrodes used to fabricate 3D printed materials using ultrasonic additive manufacturing. The development and deployment of a coated sonotrode is expected to push the existing state of the art to facilitate the solidstate additive manufacturing of hard steels and titanium alloys. To this effect a structurally amorphous stainless steel material and cobalt chrome material were deposited on the sonotrode material. Both the deposits showed good adhesion to the substrate. The coatings made using the structurally amorphous steel materials showed cracking during the initial trials and cracking was eliminated by deposition on a preheated substrate. Both the coatings show hardness in excess of 600 HVN. Thus the phase 1 of this project has been used to identify suitable materials to use to coat the sonotrode. Despite the fact that successful deposits were obtained, the coatings need to be evaluated by performing detailed galling tests at various temperatures. In addition field tests are also necessary to test the stability of these coatings in a high cycle ultrasonic vibration mode. If awarded, phase 2 of the project would be used to optimize the composition of the deposit material to maximize galling resistance. The industrial partner would then use the coated sonotrode to fabricate builds made of austenitic stainless steel to test the viability of using a coated sonotrode.

  17. Low-Energy Plasma Spray (LEPS) Deposition of Hydroxyapatite/Poly-ɛ-Caprolactone Biocomposite Coatings

    Science.gov (United States)

    Garcia-Alonso, Diana; Parco, Maria; Stokes, Joseph; Looney, Lisa

    2012-01-01

    Thermal spraying is widely employed to deposit hydroxyapatite (HA) and HA-based biocomposites on hip and dental implants. For thick HA coatings (>150 μm), problems are generally associated with the build-up of residual stresses and lack of control of coating crystallinity. HA/polymer composite coatings are especially interesting to improve the pure HA coatings' mechanical properties. For instance, the polymer may help in releasing the residual stresses in the thick HA coatings. In addition, the selection of a bioresorbable polymer may enhance the coatings' biological behavior. However, there are major challenges associated with spraying ceramic and polymeric materials together because of their very different thermal properties. In this study, pure HA and HA/poly-ɛ-caprolactone (PCL) thick coatings were deposited without significant thermal degradation by low-energy plasma spraying (LEPS). PCL has never been processed by thermal spraying, and its processing is a major achievement of this study. The influence of selected process parameters on microstructure, composition, and mechanical properties of HA and HA/PCL coatings was studied using statistical design of experiments (DOE). The HA deposition rate was significantly increased by the addition of PCL. The average porosity of biocomposite coatings was slightly increased, while retaining or even improving in some cases their fracture toughness and microhardness. Surface roughness of biocomposites was enhanced compared with HA pure coatings. Cell culture experiments showed that murine osteoblast-like cells attach and proliferate well on HA/PCL biocomposite deposits.

  18. Deposition, characterization, and in vivo performance of parylene coating on general-purpose silicone for examining potential biocompatible surface modifications

    International Nuclear Information System (INIS)

    Chou, Chia-Man; Shiao, Chiao-Ju; Chung, Chi-Jen; He, Ju-Liang

    2013-01-01

    In this study, a thorough investigation of parylene coatings was conducted, as follows: microstructure (i.e., X-ray diffractometer (XRD) and cold field emission scanning electron microscope (FESEM)), mechanical property (i.e., pencil hardness and cross-cut adhesion test), surface property (i.e., water contact angle measurement, IR, and X-ray photoelectron spectroscopy (XPS)), and biocompatibility tests (i.e., fibroblast cell culture, platelet adhesion, and animal studies). The results revealed that parylene, a crystalline and brittle coating, exhibited satisfactory film adhesion and relative hydrophobicity, thereby contributing to its effective barrier properties. Fibroblast cell culturing on the parylene-deposited specimen demonstrated improved cell proliferation and equivalent to or superior blood compatibility than that of the medical-grade silicone (currently used clinically). In the animal study, parylene coatings exhibited similar subcutaneous inflammatory reactions compared with the medical-grade silicone. Both in vitro and in vivo tests demonstrated the satisfactory biocompatibility of parylene coatings. - Highlights: • A complete investigation to identify the characteristics of parylene coatings on general-purpose silicones. • Microstructures, surface properties and mechanical properties of parylene coatings were examined. • In vitro (Cell culture, platelet adhesion) tests and animal studies revealed satisfactory biocompatibility. • An alternative of medical-grade silicones is expected to be obtained

  19. Effect of Al 2 O 3 Recombination Barrier Layers Deposited by Atomic Layer Deposition in Solid-State CdS Quantum Dot-Sensitized Solar Cells

    KAUST Repository

    Roelofs, Katherine E.

    2013-03-21

    Despite the promise of quantum dots (QDs) as a light-absorbing material to replace the dye in dye-sensitized solar cells, quantum dot-sensitized solar cell (QDSSC) efficiencies remain low, due in part to high rates of recombination. In this article, we demonstrate that ultrathin recombination barrier layers of Al2O3 deposited by atomic layer deposition can improve the performance of cadmium sulfide (CdS) quantum dot-sensitized solar cells with spiro-OMeTAD as the solid-state hole transport material. We explored depositing the Al2O3 barrier layers either before or after the QDs, resulting in TiO2/Al2O3/QD and TiO 2/QD/Al2O3 configurations. The effects of barrier layer configuration and thickness were tracked through current-voltage measurements of device performance and transient photovoltage measurements of electron lifetimes. The Al2O3 layers were found to suppress dark current and increase electron lifetimes with increasing Al 2O3 thickness in both configurations. For thin barrier layers, gains in open-circuit voltage and concomitant increases in efficiency were observed, although at greater thicknesses, losses in photocurrent caused net decreases in efficiency. A close comparison of the electron lifetimes in TiO2 in the TiO2/Al2O3/QD and TiO2/QD/Al2O3 configurations suggests that electron transfer from TiO2 to spiro-OMeTAD is a major source of recombination in ss-QDSSCs, though recombination of TiO2 electrons with oxidized QDs can also limit electron lifetimes, particularly if the regeneration of oxidized QDs is hindered by a too-thick coating of the barrier layer. © 2013 American Chemical Society.

  20. Spectroscopic Study of Plasma Polymerized a-C:H Films Deposited by a Dielectric Barrier Discharge

    Directory of Open Access Journals (Sweden)

    Thejaswini Halethimmanahally Chandrashekaraiah

    2016-07-01

    Full Text Available Plasma polymerized a-C:H thin films have been deposited on Si (100 and aluminum coated glass substrates by a dielectric barrier discharge (DBD operated at medium pressure using C2Hm/Ar (m = 2, 4, 6 gas mixtures. The deposited films were characterized by Fourier transform infrared reflection absorption spectroscopy (FT-IRRAS, Raman spectroscopy, and ellipsometry. FT-IRRAS revealed the presence of sp3 and sp2 C–H stretching and C–H bending vibrations of bonds in the films. The presence of D and G bands was confirmed by Raman spectroscopy. Thin films obtained from C2H4/Ar and C2H6/Ar gas mixtures have ID/IG ratios of 0.45 and 0.3, respectively. The refractive indices were 2.8 and 3.1 for C2H4/Ar and C2H6/Ar films, respectively, at a photon energy of 2 eV.

  1. Evaluation of bond strength of isothermally aged plasma sprayed thermal barrier coating

    International Nuclear Information System (INIS)

    Kim, Dae Jin; Lee, Dong Hoon; Koo, Jae Mean; Song, Sung Jin; Seok, Chang Sung; Kim, Mun Young

    2008-01-01

    In this study, disk type of thermal barrier coating system for gas turbine blade was isothermally aged in the furnace changing exposure time and temperature. For each aging condition, bond tests for three samples were conducted for evaluating degradation of adhesive or cohesive strength of thermal barrier coating system. For as-sprayed condition, the location of fracture in the bond test was in the middle of epoxy which have bond strength of 57 MPa. As specimens are degraded by thermal aging, bond strength gradually decreased and the location of failure was also changed from within top coat at the earlier stage of thermal aging to the interface between top coat and TGO at the later stage due to the delamination in the coating

  2. Evaluation of bond strength of isothermally aged plasma sprayed thermal barrier coating

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Dae Jin; Lee, Dong Hoon; Koo, Jae Mean; Song, Sung Jin; Seok, Chang Sung [Sungkyunkwan University, Suwon (Korea, Republic of); Kim, Mun Young [Korea Plant Service and Engineering Co., Ltd., Seongnam (Korea, Republic of)

    2008-07-15

    In this study, disk type of thermal barrier coating system for gas turbine blade was isothermally aged in the furnace changing exposure time and temperature. For each aging condition, bond tests for three samples were conducted for evaluating degradation of adhesive or cohesive strength of thermal barrier coating system. For as-sprayed condition, the location of fracture in the bond test was in the middle of epoxy which have bond strength of 57 MPa. As specimens are degraded by thermal aging, bond strength gradually decreased and the location of failure was also changed from within top coat at the earlier stage of thermal aging to the interface between top coat and TGO at the later stage due to the delamination in the coating.

  3. Environmental Barrier Coatings for Turbine Engines: A Design and Performance Perspective

    Science.gov (United States)

    Zhu, Dongming; Fox, Dennis S.; Ghosn, Louis; Smialek, James L.; Miller, Robert A.

    2009-01-01

    Ceramic thermal and environmental barrier coatings (TEBC) for SiC-based ceramics will play an increasingly important role in future gas turbine engines because of their ability to effectively protect the engine components and further raise engine temperatures. However, the coating long-term durability remains a major concern with the ever-increasing temperature, strength and stability requirements in engine high heat-flux combustion environments, especially for highly-loaded rotating turbine components. Advanced TEBC systems, including nano-composite based HfO2-aluminosilicate and rare earth silicate coatings are being developed and tested for higher temperature capable SiC/SiC ceramic matrix composite (CMC) turbine blade applications. This paper will emphasize coating composite and multilayer design approach and the resulting performance and durability in simulated engine high heat-flux, high stress and high pressure combustion environments. The advances in the environmental barrier coating development showed promise for future rotating CMC blade applications.

  4. Progress Toward Meeting NIF Specifications for Vapor Deposited Polyimide Ablator Coatings

    International Nuclear Information System (INIS)

    Letts, Stephan A.; Anthamatten, Mitchell; Buckley, Steven R.; Fearon, Evelyn; Nissen, April E.H.; Cook, Robert C.

    2004-01-01

    We are developing an evaporative coating technique for deposition of thick polyimide (PI) ablator layers on ICF targets. The PI coating technique utilizes stoichiometrically controlled fluxes from two Knudsen cell evaporators containing a dianhydride and a diamine to deposit a polyamic acid (PAA) coating. Heating the PAA coating to 300 deg. C converts the PAA coating to a polyimide. Coated shells are rough due to particles on the substrate mandrels and from damage to the coating caused by the agitation used to achieve a uniform coating. We have developed a smoothing process that exposes an initially rough PAA coated shell to solvent vapor using gas levitation. We found that after smoothing the coatings developed a number of wide (low-mode) defects. We have identified two major contributors to low-mode roughness: surface hydrolysis, and deformation during drying/curing. By minimizing air exposure prior to vapor smoothing, avoiding excess solvent sorption during vapor smoothing, and using slow drying we are able to deposit and vapor smooth coatings 160 μm thick with a surface roughness less than 20 nm RMS

  5. History of Thermal Barrier Coatings for Gas Turbine Engines: Emphasizing NASA's Role from 1942 to 1990

    Science.gov (United States)

    Miller, Robert A.

    2009-01-01

    NASA has played a central role in the development of thermal barrier coatings (TBCs) for gas turbine applications. This report discusses the history of TBCs emphasizing the role NASA has played beginning with (1) frit coatings in the 1940s and 1950s; (2) thermally sprayed coatings for rocket application in the 1960s and early 1970s; (3) the beginnings of the modern era of turbine section coatings in the mid 1970s; and (4) failure mechanism and life prediction studies in the 1980s and 1990s. More recent efforts are also briefly discussed.

  6. Polymer-Derived Ceramics as Innovative Oxidation Barrier Coatings for Mo-Si-B Alloys

    Science.gov (United States)

    Hasemann, Georg; Baumann, Torben; Dieck, Sebastian; Rannabauer, Stefan; Krüger, Manja

    2015-04-01

    A preceramic polymer precursor, perhydropolysilazane, is used to investigate its function as a new type of oxidation barrier coating on Mo-Si-B alloys. After dip-coating and pyrolysis at 1073 K (800 °C), dense and well-adhering SiON ceramic coatings could be achieved, which were investigated by SEM and cyclic oxidation tests at 1073 K and 1373 K (800 °C and 1100 °C). The coating is promising in reducing the mass loss during the initial stage of oxidation exposure at 1373 K (1100 °C) significantly.

  7. Pulsed laser deposition: the road to hybrid nanocomposites coatings and novel pulsed laser adaptive technique.

    Science.gov (United States)

    Serbezov, Valery

    2013-01-01

    The applications of Pulsed Laser Deposition (PLD) for producing nanoparticles, nanostructures and nanocomposites coatings based on recently developed laser ablating techniques and their convergence are being reviewed. The problems of in situ synthesis of hybrid inorganic-organic nanocomposites coatings by these techniques are being discussed. The novel modification of PLD called Pulsed Laser Adaptive Deposition (PLAD) technique is presented. The in situ synthesized inorganic/organic nanocomposites coatings from Magnesium (Mg) alloy/Rhodamine B and Mg alloy/ Desoximetasone by PLAD are described. The trends, applications and future development of discussed patented methods based on the laser ablating technologies for producing hybrid nanocomposite coatings have also been discussed in this review.

  8. Effects of deposition temperature on electrodeposition of zinc–nickel alloy coatings

    International Nuclear Information System (INIS)

    Qiao, Xiaoping; Li, Helin; Zhao, Wenzhen; Li, Dejun

    2013-01-01

    Highlights: ► Both normal and anomalous deposition can be realized by changing bath temperature. ► The Ni content in Zn–Ni alloy deposit increases sharply as temperature reach 60 °C. ► The abrupt change in coating composition is caused by the shift of cathodic potential. ► The deposition temperature has great effect on microstructure of Zn–Ni alloy deposit. -- Abstract: Zinc–nickel alloy coatings were electrodeposited on carbon steel substrates from the ammonium chloride bath at different temperatures. The composition, phase structure and morphology of these coatings were analyzed by energy dispersive spectrometer, X-ray diffractometer and scanning electron microscopy respectively. Chronopotentiometry and potentiostatic methods were also employed to analyze the possible causes of the composition and structure changes induced by deposition temperature. It has been shown that both normal and anomalous co-deposition of zinc and nickel could be realized by changing deposition temperature under galvanostatic conditions. The abrupt changes in the composition and phase structure of the zinc–nickel alloy coatings were observed when deposition temperature reached 60 °C. The sharply decrease of current efficiency for zinc–nickel co-deposition was also observed when deposition temperature is higher than 40 °C. Analysis of the partial current densities showed that the decrease of current efficiency with the rise of deposition temperature was due to the enhancement of the hydrogen evolution. It was also confirmed that the ennoblement of cathodic potential was the cause for the increase of nickel content in zinc–nickel alloy coatings as a result of deposition temperature rise. The good zinc–nickel alloy coatings with compact morphology and single γ phase could be obtained when the deposition temperature was fixed at 30–40 °C

  9. High-speed deposition of titanium carbide coatings by laser-assisted metal–organic CVD

    Energy Technology Data Exchange (ETDEWEB)

    Gong, Yansheng [Faculty of Materials Science and Chemistry, China University of Geosciences, Wuhan 430074 (China); Tu, Rong, E-mail: turong@whut.edu.cn [State Key Laboratory of Advanced Technology for Material Synthesis and Processing, Wuhan University of Technology, Wuhan 430070 (China); Goto, Takashi [Institute for Materials Research, Tohoku University, Aoba-ku, 2-1-1 Katahira, Sendai 980-8577 (Japan)

    2013-08-01

    Graphical abstract: - Highlights: • A semiconductor laser was first used to prepare wide-area LCVD-TiC{sub x} coatings. • The effect of laser power for the deposition of TiC{sub x} coatings was discussed. • TiC{sub x} coatings showed a columnar cross section and a dense surface texture. • TiC{sub x} coatings had a 1–4 order lower laser density than those of previous reports. • This study gives the possibility of LCVD applying on the preparation of TiC{sub x} coating. - Abstract: A semiconductor laser-assisted chemical vapor deposition (LCVD) of titanium carbide (TiC{sub x}) coatings on Al{sub 2}O{sub 3} substrate using tetrakis (diethylamido) titanium (TDEAT) and C{sub 2}H{sub 2} as source materials were investigated. The influences of laser power (P{sub L}) and pre-heating temperature (T{sub pre}) on the microstructure and deposition rate of TiC{sub x} coatings were examined. Single phase of TiC{sub x} coatings were obtained at P{sub L} = 100–200 W. TiC{sub x} coatings had a cauliflower-like surface and columnar cross section. TiC{sub x} coatings in the present study had the highest R{sub dep} (54 μm/h) at a relative low T{sub dep} than those of conventional CVD-TiC{sub x} coatings. The highest volume deposition rate (V{sub dep}) of TiC{sub x} coatings was about 4.7 × 10{sup −12} m{sup 3} s{sup −1}, which had 3–10{sup 5} times larger deposition area and 1–4 order lower laser density than those of previous LCVD using CO{sub 2}, Nd:YAG and argon ion laser.

  10. The erosion performance of cold spray deposited metal matrix composite coatings with subsequent friction stir processing

    Science.gov (United States)

    Peat, Tom; Galloway, Alexander; Toumpis, Athanasios; McNutt, Philip; Iqbal, Naveed

    2017-02-01

    This study forms an initial investigation into the development of SprayStir, an innovative processing technique for generating erosion resistant surface layers on a chosen substrate material. Tungsten carbide - cobalt chromium, chromium carbide - nickel chromium and aluminium oxide coatings were successfully cold spray deposited on AA5083 grade aluminium. In order to improve the deposition efficiency of the cold spray process, coatings were co-deposited with powdered AA5083 using a twin powder feed system that resulted in thick (>300 μm) composite coatings. The deposited coatings were subsequently friction stir processed to embed the particles in the substrate in order to generate a metal matrix composite (MMC) surface layer. The primary aim of this investigation was to examine the erosion performance of the SprayStirred surfaces and demonstrate the benefits of this novel process as a surface engineering technique. Volumetric analysis of the SprayStirred surfaces highlighted a drop of approx. 40% in the level of material loss when compared with the cold spray deposited coating prior to friction stir processing. Micro-hardness testing revealed that in the case of WC-CoCr reinforced coating, the hardness of the SprayStirred material exhibits an increase of approx. 540% over the unaltered substrate and 120% over the as-deposited composite coating. Microstructural examination demonstrated that the increase in the hardness of the MMC aligns with the improved dispersion of reinforcing particles throughout the aluminium matrix.

  11. Long period gratings coated with hafnium oxide by plasma-enhanced atomic layer deposition for refractive index measurements.

    Science.gov (United States)

    Melo, Luis; Burton, Geoff; Kubik, Philip; Wild, Peter

    2016-04-04

    Long period gratings (LPGs) are coated with hafnium oxide using plasma-enhanced atomic layer deposition (PEALD) to increase the sensitivity of these devices to the refractive index of the surrounding medium. PEALD allows deposition at low temperatures which reduces thermal degradation of UV-written LPGs. Depositions targeting three different coating thicknesses are investigated: 30 nm, 50 nm and 70 nm. Coating thickness measurements taken by scanning electron microscopy of the optical fibers confirm deposition of uniform coatings. The performance of the coated LPGs shows that deposition of hafnium oxide on LPGs induces two-step transition behavior of the cladding modes.

  12. INKJET PRINTING OF ALUMOOXIDE SOL FOR DEPOSITION OF ANTIREFLECTING COATINGS

    Directory of Open Access Journals (Sweden)

    E. A. Eremeeva

    2017-01-01

    Full Text Available Subject of Research. This work describes for the first time the formation of antireflective coating on the base of boehmite phase of AlOOH with low refractive index (1.35 by inkjet printing on the nonporous substrate. This method gives the possibility to increase the contrast of colorful interfering images by 32% obtaining by inkjet printing of titanium dioxide sol. The usage of this technology enables to obtain patterns with wide viewing angle and makes them highly stable. Methods. Traditional sol-gel method with peptizing agents and heating for 90oC was applied for sol synthesis. Then the mixture was under sonic treatment for the obtaining of viscous sol. The viscosity was determined by Brookfield HA/HB viscometer, and the surface tension by Kyowa DY-700 tensiometer. Aluminum oxide ink was deposited on polished slides (26×76 mm2, Paul Marienfeld, Germany, over titanium oxide layer. To print titania ink, we use a desktop office printer Canon Pixma IP 2840 and Dimatix DMP-2831. The thickness of an inkjet AlOOH layer after drying in the air and removal of the solvents did not exceed 150 nm with an RI not less than 1.35 in the entire visible range. Results. The stable colloidal ink was obtained for the first time on the base of aluminum oxide matrix with neutral pH. The rheology was regulated by controlling parameters of sol-gel method in the system of aqueous titanium dioxide sol and by adding ethanol that affects the charge of double electrical layer of disperse phase. The controllable coalesce of drops enables to apply antireflection coating within the thickness accuracy of 10 nm. The morphology of particles and the topology of printed structures were analyzed by optical, scanning electron and atomic-force microscopes. Practical Relevance. We have proposed the approach to obtain colorful, interference patterns using two types of high refractive inks with different refractive indexes. The inkjet printing method opens new opportunities for

  13. Deposition, microstructure, and properties of nanocrystalline Ti(C,O,N) coatings

    Science.gov (United States)

    Ruppi, S.; Larsson, A.

    2003-01-01

    Chemical vapor deposition of Ti(C,N) coatings from the TiCl4- CH3CN- N2-H2 system on cemented carbide substrates was studied. The morphology and grain size of the coatings were modified using carbon monoxide (CO). Transmission electron microscopy confirmed that grain refinement of the Ti(C,N) coatings could be obtained by means of CO doping and nanocrystalline coatings were obtained at CO levels exceeding 6%. CO doping resulted in the incorporation of oxygen in the structure, but no segregation of oxygen to grain boundaries was observed. The coatings appeared to be of homogeneous composition even at the highest CO levels. Both improved coating hardness and surface quality were obtained with decreasing grain size. However, the coatings exhibited clearly lower crater wear resistance in the nanograined region. This was explained by an increased tendency for grain-boundary sliding in the nanocrystalline coatings leading to more pronounced plastic deformation.

  14. Influence of thickness on the properties of hydroxyapatite coatings deposited by KrF laser ablation.

    Science.gov (United States)

    Fernandez-Pradas, J M; Clèries, L; Martinez, E; Sardin, G; Esteve, J; Morenza, J L

    2001-08-01

    The growth of hydroxyapatite coatings obtained by KrF excimer laser ablation and their adhesion to a titanium alloy substrate were studied by producing coatings with thicknesses ranging from 170 nm up to 1.5 microm, as a result of different deposition times. The morphology of the coatings consists of grain-like particles and also droplets. During growth the grain-like particles grow in size, partially masking the droplets, and a columnar structure is developed. The thinnest film is mainly composed of amorphous calcium phosphate. The coating 350nm thick already contains hydroxyapatite, whereas thicker coatings present some alpha tricalcium phosphate in addition to hydroxyapatite. The resulting coating to substrate adhesion was evaluated through the scratch test technique. Coatings fail under the scratch test by spallating laterally from the diamond tip and the failure load increases as thickness decreases, until not adhesive but cohesive failure for the thinnest coating is observed.

  15. Thermal barrier coatings for the space shuttle main engine turbine blades

    Science.gov (United States)

    Bhat, B. N.; Gilmore, H. L.; Holmes, R. R.

    1985-01-01

    The Space Shuttle Main Engine (SSME) turbopump turbine blades experience extremely severe thermal shocks during start-up and shut-down. For instance, the high pressure fuel turbopump turbine which burns liquid hydrogen operates at approximately 1500 F, but is shut down fuel rich with turbine blades quenced in liquid hydrogen. This thermal shock is a major contributor to blade cracking. The same thermal shock cause the protective ZrO2 thermal barrier coatings to spall or flake off, leaving only the NiCrAlY bond coating which provides only a minimum thermal protection. The turbine blades are therefore life limited to about 3000 sec for want of a good thermal barrier. A suitable thermal barrier coating (TBC) is being developed for the SSME turbine blades. Various TBCs developed for the gas turbine engines were tested in a specially built turbine blade tester. This tester subjects the coated blades to thermal and pressure cycles similar to those during actual operation of the turbine. The coatings were applied using a plasma spraying techniques both under atmospheric conditions and in vacuum. Results are presented. In general vacuum plasma sprayed coatings performed much better than those sprayed under atmospheric conditions. A 50 to 50 blend of Cr2O3 and NiCrAlY, vacuum plasma sprayed on SSME turbopump turbine blades appear to provide significant improvements in coating durability and thermal protection.

  16. Thermal analysis of the effect of thick thermal barrier coatings on diesel engine performance

    International Nuclear Information System (INIS)

    Hoag, K.L.; Frisch, S.R.; Yonushonis, T.M.

    1986-01-01

    The reduction of heat rejection from the diesel engine combustion chamber has been the subject of a great deal of focus in recent years. In the pursuit of this goal, Cummins Engine Company has received a contract from the Department of Energy for the development of thick thermal barrier coatings for combustion chamber surfaces. This contract involves the analysis of the impact of coatings on diesel engine performance, bench test evaluation of various coating designs, and single cylinder engine tests. The efforts reported in this paper center on the analysis of the effects of coatings on engine performance and heat rejection. For this analysis the conventional water cooled engine was compared with an engine having limited oil cooling, and utilizing zirocnia coated cylinder had firedecks and piston crowns. The analysis showed little or no benefits of similarly coating the valves or cylinder liner

  17. Boron carbide (B{sub 4}C) coating. Deposition and testing

    Energy Technology Data Exchange (ETDEWEB)

    Azizov, E.; Barsuk, V. [Troitsk Institute for Innovation and Fusion Research (TRINITI), Moscow Region (Russian Federation); Begrambekov, L., E-mail: lbb@plasma.mephi.ru [National Research Nuclear University MEPhI (Moscow Engineering Physics Institute), Moscow (Russian Federation); Buzhinsky, O. [Troitsk Institute for Innovation and Fusion Research (TRINITI), Moscow Region (Russian Federation); Evsin, A.; Gordeev, A.; Grunin, A. [National Research Nuclear University MEPhI (Moscow Engineering Physics Institute), Moscow (Russian Federation); Klimov, N. [Troitsk Institute for Innovation and Fusion Research (TRINITI), Moscow Region (Russian Federation); Kurnaev, V. [National Research Nuclear University MEPhI (Moscow Engineering Physics Institute), Moscow (Russian Federation); Mazul, I. [Federal State Unitary Interprise Efremov Scientific Research Institute of Electrophysical Apparatus (NIIEFA Efremov), St-Peterburg (Russian Federation); Otroshchenko, V.; Putric, A. [Troitsk Institute for Innovation and Fusion Research (TRINITI), Moscow Region (Russian Federation); Sadovskiy, Ya.; Shigin, P.; Vergazov, S.; Zakharov, A. [National Research Nuclear University MEPhI (Moscow Engineering Physics Institute), Moscow (Russian Federation)

    2015-08-15

    Boron carbide was proposed as a material of in-situ protecting coating for tungsten tiles of ITER divertor. To prove this concept the project including investigation of regimes of plasma deposition of B{sub 4}C coating on tungsten and tests of boron carbide layer in ITER-like is started recently. The paper contends the first results of the project. The results of B{sub 4}C coating irradiation by the plasma pulses of QSPU-T plasma accelerator are presented. The new device capable of B{sub 4}C film deposition on tungsten and testing of the films and materials with ITER-like heat loads and ion- and electron irradiation is described. The results of B{sub 4}C coating deposition and testing of both tungsten substrate and coating are shown and discussed.

  18. ELECTROPHORETIC DEPOSITION OF TIO2-MULTI-WALLED CARBON NANOTUBE COMPOSITE COATINGS: MORPHOLOGICAL STUDY

    Directory of Open Access Journals (Sweden)

    M. S. MAHMOUDI JOZEE

    2016-09-01

    Full Text Available A homogenous TiO2 / multi-walled carbon nanotubes(MWCNTs composite film were prepared by electrophoretic co-deposition from organic suspension on a stainless steel substrate.  In this study, MWCNTs was incorporated to the coating because of their long structure and their capability to be functionalized by different inorganic groups on the surface. FTIR spectroscopy showed the existence of carboxylic groups on the modified carbon nanotubes surface. The effect of applied electrical fields, deposition time and concentration of nanoparticulates on coatings morphology were investigated by scanning electron microscopy. It was found that combination of MWCNTs within TiO2 matrix eliminating micro cracks presented on TiO2 coating. Also, by increasing the deposition voltages, micro cracks were increased. SEM observation of the coatings revealed that TiO2/multi-walled carbon nanotubes coatings produced from optimized electric field was uniform and had good adhesive to the substrate.

  19. Modification of implant material surface properties by means of oxide nano-structured coatings deposition

    Science.gov (United States)

    Safonov, Vladimir; Zykova, Anna; Smolik, Jerzy; Rogowska, Renata; Lukyanchenko, Vladimir; Kolesnikov, Dmitrii

    2014-08-01

    The deposition of functional coatings on the metal surface of artificial joints is an effective way of enhancing joint tribological characteristics. It is well-known that nanostructured oxide coatings have specific properties advantageous for future implant applications. In the present study, we measured the high hardness parameters, the adhesion strength and the low friction coefficient of the oxide magnetron sputtered coatings. The corrosion test results show that the oxide coating deposition had improved the corrosion resistance by a factor of ten for both stainless steel and titanium alloy substrates. Moreover, the hydrophilic nature of coated surfaces in comparison with the metal ones was investigated in the tensiometric tests. The surfaces with nanostructured oxide coatings demonstrated improved biocompatibility for in vitro and in vivo tests, attributed to the high dielectric constants and the high values of the surface free energy parameters.

  20. Characterization of Environmental Stability of Pulsed Laser Deposited Oxide Ceramic Coatings

    Energy Technology Data Exchange (ETDEWEB)

    ADAMS, THADM

    2004-03-02

    A systematic investigation of candidate hydrogen permeation materials applied to a substrate using Pulsed Laser Deposition has been performed. The investigation focused on application of leading permeation-resistant materials types (oxide, carbides, and metals) on a stainless steel substrate. and evaluation of the stability of the applied coatings. Type 304L stainless steel substrates were coated with aluminum oxide, chromium oxide, and aluminum. Characterization of the coating-substrate system adhesion was performed using scratch adhesion testing and microindentation. Coating stability and environmental susceptibility were evaluated for two conditions-air at 350 degrees Celsius and Ar-H2 at 350 degrees Celsius for up to 100 hours. Results from this study have shown the pulsed laser deposition process to be an extremely versatile technology that is capable of producing a sound coating/substrate system for a wide variety of coating materials.

  1. Surface modification of reverse osmosis desalination membranes by thin-film coatings deposited by initiated chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Ozaydin-Ince, Gozde, E-mail: gozdeince@sabanciuniv.edu [Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Matin, Asif, E-mail: amatin@mit.edu [Department of Mechanical Engineering, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia); Khan, Zafarullah, E-mail: zukhan@mit.edu [Department of Mechanical Engineering, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia); Zaidi, S.M. Javaid, E-mail: zaidismj@kfupm.edu.sa [Department of Mechanical Engineering, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia); Gleason, Karen K., E-mail: kkgleasn@mit.edu [Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States)

    2013-07-31

    Thin-film polymeric reverse osmosis membranes, due to their high permeation rates and good salt rejection capabilities, are widely used for seawater desalination. However, these membranes are prone to biofouling, which affects their performance and efficiency. In this work, we report a method to modify the membrane surface without damaging the active layer or significantly affecting the performance of the membrane. Amphiphilic copolymer films of hydrophilic hydroxyethylmethacrylate and hydrophobic perfluorodecylacrylate (PFA) were synthesized and deposited on commercial RO membranes using an initiated chemical vapor deposition technique which is a polymer deposition technique that involves free-radical polymerization initiated by gas-phase radicals. Relevant surface characteristics such as hydrophilicity and roughness could be systematically controlled by varying the polymer chemistry. Increasing the hydrophobic PFA content in the films leads to an increase in the surface roughness and hydrophobicity. Furthermore, the surface morphology studies performed using the atomic force microscopy show that as the thickness of the coating increases average surface roughness increases. Using this knowledge, the coating thickness and chemistry were optimized to achieve high permeate flux and to reduce cell attachment. Results of the static bacterial adhesion tests show that the attachment of bacterial cells is significantly reduced on the coated membranes. - Highlights: • Thin films are deposited on reverse osmosis membranes. • Amphiphilic thin films are resistant to protein attachment. • The permeation performance of the membranes is not affected by the coating. • The thin film coatings delayed the biofouling.

  2. Atomic layer deposition-A novel method for the ultrathin coating of minitablets.

    Science.gov (United States)

    Hautala, Jaana; Kääriäinen, Tommi; Hoppu, Pekka; Kemell, Marianna; Heinämäki, Jyrki; Cameron, David; George, Steven; Juppo, Anne Mari

    2017-10-05

    We introduce atomic layer deposition (ALD) as a novel method for the ultrathin coating (nanolayering) of minitablets. The effects of ALD coating on the tablet characteristics and taste masking were investigated and compared with the established coating method. Minitablets containing bitter tasting denatonium benzoate were coated by ALD using three different TiO 2 nanolayer thicknesses (number of deposition cycles). The established coating of minitablets was performed in a laboratory-scale fluidized-bed apparatus using four concentration levels of aqueous Eudragit ® E coating polymer. The coated minitablets were studied with respect to the surface morphology, taste masking capacity, in vitro disintegration and dissolution, mechanical properties, and uniformity of content. The ALD thin coating resulted in minimal increase in the dimensions and weight of minitablets in comparison to original tablet cores. Surprisingly, ALD coating with TiO 2 nanolayers decreased the mechanical strength, and accelerated the in vitro disintegration of minitablets. Unlike previous studies, the studied levels of TiO 2 nanolayers on tablets were also inadequate for effective taste masking. In summary, ALD permits a simple and rapid method for the ultrathin coating (nanolayering) of minitablets, and provides nanoscale-range TiO 2 coatings on porous minitablets. More research, however, is needed to clarify its potential in tablet taste masking applications. Copyright © 2017 Elsevier B.V. All rights reserved.

  3. Process and electrolyte for applying barrier layer anodic coatings

    International Nuclear Information System (INIS)

    Dosch, R.G.; Prevender, T.S.

    1975-01-01

    Various metals may be anodized, and preferably barrier anodized, by anodizing the metal in an electrolyte comprising quaternary ammonium compound having a complex metal anion in a solvent containing water and a polar, water soluble organic material. (U.S.)

  4. One Component Encapsulating Material Matrix as High Barrier Coating Project

    Data.gov (United States)

    National Aeronautics and Space Administration — To address the NASA need for new flexible food packaging materials with effective high barrier against oxygen and moisture to protect food, minimize weight and...

  5. Evaluation of present thermal barrier coatings for potential service in electric utility gas turbines

    Science.gov (United States)

    Bratton, R. J.; Lau, S. K.; Lee, S. Y.

    1982-01-01

    The resistance of present-day thermal barrier coatings to combustion gases found in electric utility turbines was assessed. The plasma sprayed coatings, both duplex and graded types, were primarily zirconia-based, although a calcium silicate was also evaluated. Both atmospheric burner rig tests and high pressure tests (135 psig) showed that several present-day thermal barrier coatings have a high potential for service in gas turbines burning the relatively clean GT No. 2 fuel. However, coating improvements are needed for use in turbines burning lower grade fuel such as residual oil. The duplex ZrO2.8Y2O3/NiCrA1Y coating was ranked highest and selected for near-term field testing, with Ca2SiO4/NiCrA1Y ranked second. Graded coatings show potential for corrosive turbine operating conditions and warrant further development. The coating degradation mechanisms for each coating system subjected to the various environmental conditions are also described.

  6. The oxidation behavior of classical thermal barrier coatings exposed to extreme temperature

    Directory of Open Access Journals (Sweden)

    Alina DRAGOMIRESCU

    2017-03-01

    Full Text Available Thermal barrier coatings (TBC are designed to protect metal surfaces from extreme temperatures and improve their resistance to oxidation during service. Currently, the most commonly used systems are those that have the TBC structure bond coat (BC / top coat (TC layers. The top coat layer is a ceramic layer. Oxidation tests are designed to identify the dynamics of the thermally oxide layer (TGO growth at the interface of bond coat / top coat layers, delamination mechanism and the TBC structural changes induced by thermal conditions. This paper is a short study on the evolution of aluminum oxide protective layer along with prolonged exposure to the testing temperature. There have been tested rectangular specimens of metal super alloy with four surfaces coated with a duplex thermal barrier coating system. The specimens were microscopically and EDAX analyzed before and after the tests. In order to determine the oxide type, the samples were analyzed using X-ray diffraction. The results of the investigation are encouraging for future studies. The results show a direct relationship between the development of the oxide layer and long exposure to the test temperature. Future research will focus on changing the testing temperature to compare the results.

  7. Relation of Thermal Conductivity with Process Induced Anisotropic Void Systems in EB-PVD PYSZ Thermal Barrier Coatings

    Energy Technology Data Exchange (ETDEWEB)

    Renteria, A. Flores; Saruhan-Brings, B.; Ilavsky, J.

    2008-03-03

    Thermal barrier coatings (TBCs) deposited by Electron-beam physical deposition (EB-PVD) protect the turbine blades situated at the high pressure sector of the aircraft and stationary turbines. It is an important task to uphold low thermal conductivity in TBCs during long-term service at elevated temperatures. One of the most promising methods to fulfil this task is to optimize the properties of PYSZ-based TBC by tailoring its microstructure. Thermal conductivity of the EB-PVD produced PYSZ TBCs is influenced mainly by the size, shape, orientation and volume of the various types of porosity present in the coatings. These pores can be classified as open (inter-columnar and between feather arms gaps) and closed (intra-columnar pores). Since such pores are located within the three-dimensionally deposited columns and enclose large differences in their sizes, shapes, distribution and anisotropy, the accessibility for their characterization is very complex and requires the use of sophisticated methods. In this work, three different EB-PVD TBC microstructures were manufactured by varying the process parameters, yielding various characteristics of their pores. The corresponding thermal conductivities in as-coated state and after ageing at 11000C/1h and 100h were measured via Laser Flash Analysis Method (LFA). The pore characteristics and their individual effect on the thermal conductivity are analysed by USAXS which is supported by subsequent modelling and LFA methods, respectively. Evident differences in the thermal conductivity values of each microstructure were found in as-coated and aged conditions. In summary, broader columns introduce higher values in thermal conductivity. In general, thermal conductivity increases after ageing for all three investigated microstructures, although those with initial smaller pore surface area show smaller changes.

  8. Relation of thermal conductivity with process induced anisotropic void system in EB-PVD PYSZ thermal barrier coatings.

    Energy Technology Data Exchange (ETDEWEB)

    Renteria, A. F.; Saruhan, B.; Ilavsky, J.; German Aerospace Center

    2007-01-01

    Thermal barrier coatings (TBCs) deposited by Electron-beam physical deposition (EB-PVD) protect the turbine blades situated at the high pressure sector of the aircraft and stationary turbines. It is an important task to uphold low thermal conductivity in TBCs during long-term service at elevated temperatures. One of the most promising methods to fulfil this task is to optimize the properties of PYSZ-based ,TBC by tailoring its microstructure. Thermal conductivity of the EB-PVD produced PYSZ TBCs is influenced mainly by the size, shape, orientation and volume of the various types of porosity present in the coatings. These pores can be classified as open (inter-columnar and between feather arms gaps) and closed (intra-columnar pores). Since such pores are located within the three-dimensionally deposited columns and enclose large differences in their sizes, shapes, distribution and anisotropy, the accessibility for their characterization is very complex and requires the use of sophisticated methods. In this work, three different EB-PVD TBC microstructures were manufactured by varying the process parameters, yielding various characteristics of their pores. The corresponding thermal conductivities in as-coated state and after ageing at 1100C/1h and 100h were measured via Laser Flash Analysis Method (LFA). The pore characteristics and their individual effect on the thermal conductivity are analysed by USAXS which is supported by subsequent modelling and LFA methods, respectively. Evident differences in the thermal conductivity values of each microstructure were found in as-coated and aged conditions. In summary, broader columns introduce higher values in thermal conductivity. In general, thermal conductivity increases after ageing for all three investigated microstructures, although those with initial smaller pore surface area show smaller changes.

  9. Functionalization and Area-Selective Deposition of Magnetic Carbon-Coated Iron Nanoparticles from Solution

    Directory of Open Access Journals (Sweden)

    Erika Widenkvist

    2011-01-01

    Full Text Available A route to area-selective deposition of carbon-coated iron nanoparticles, involving chemical modification of the surface of the particles, is described. Partial oxidative etching of the coating introduces carboxylic groups, which then are esterified. The functionalized particles can be selectively deposited on the Si areas of Si/SiO2 substrates by a simple dipping procedure. Nanoparticles and nanoassemblies have been analyzed using SEM, TEM, and XPS.

  10. Deposition of Coatings for Raising the Wear Resistance of Friction Surfaces of Spherical Sliding Bearings

    Science.gov (United States)

    Gorlenko, A. O.; Davydov, S. V.

    2018-01-01

    The process of finishing plasma hardening with deposition of a multilayer amorphous coating of the Si - O - C - N system is considered as applied to hardening of the friction surfaces of spherical sliding bearings. The microrelief, the submicrorelief, and the tribological characteristics of the deposited wear-resistant antifriction amorphous coating, which are responsible for the elevated wear resistance of spherical sliding bearings, are investigated.

  11. Alternating Current Electrophoretic Deposition of Antibacterial Bioactive Glass-Chitosan Composite Coatings

    OpenAIRE

    Seuss, Sigrid; Lehmann, Maja; Boccaccini, Aldo

    2014-01-01

    Alternating current (AC) electrophoretic deposition (EPD) was used to produce multifunctional composite coatings combining bioactive glass (BG) particles and chitosan. BG particles of two different sizes were used, i.e., 2 μm and 20–80 nm in average diameter. The parameter optimization and characterization of the coatings was conducted by visual inspection and by adhesion strength tests. The optimized coatings were investigated in terms of their hydroxyapatite (HA) forming ability in simulate...

  12. Advanced TiC/a-C: H nanocomposite coatings deposited by magnetron sputtering

    OpenAIRE

    Pei, Y.T.; Galvan, D.; Hosson, J.Th.M. De; Strondl, C.

    2006-01-01

    TiC/a-C:H nanocomposite coatings have been deposited by magnetron Sputtering. They consist of 2-5 nm TiC nanocrystallites embedded in the amorphous hydrocarbon (a-C:H) matrix. A transition from a Columnar to a glassy microstructure has been observed in the nanocomposite coatings with increasing substrate bias or carbon content. Micro-cracks induced by nanoindentation or wear tests readily propagate through the column boundaries whereas the coatings without a columnar inicrostructure exhibit s...

  13. Additive manufactured Ti6Al4V scaffolds with the RF- magnetron sputter deposited hydroxyapatite coating

    International Nuclear Information System (INIS)

    Chudinova, E; Surmeneva, M; Surmenev, R; Koptioug, A; Scoglund, P

    2016-01-01

    Present paper reports on the results of surface modification of the additively manufactured porous Ti6Al4V scaffolds. Radio frequency (RF) magnetron sputtering was used to modify the surface of the alloy via deposition of the biocompatible hydroxyapatite (HA) coating. The surface morphology, chemical and phase composition of the HA-coated alloy were studied. It was revealed that RF magnetron sputtering allows preparing a homogeneous HA coating onto the entire surface of scaffolds. (paper)

  14. Crack resistance of pvd coatings : Influence of surface treatment prior to deposition

    NARCIS (Netherlands)

    Zoestbergen, E; de Hosson, J.T.M.

    The crack resistance of three different PVD coatings, TiN, Ti(C,N), and a multilayer system of alternating TiN and TiAlN, have been investigated. The three coating systems were deposited onto substrates with a different surface roughness to study the influence of this pretreatment on the crack

  15. High Temperature Oxidation Property of SiC Coating Layer Fabricated by Aerosol Deposition Process

    Directory of Open Access Journals (Sweden)

    Ham G.-S.

    2017-06-01

    Full Text Available This study investigated the high temperature oxidation property of SiC coated layer fabricated by aerosol deposition process. SiC coated layer could be successfully manufactured by using pure SiC powders and aerosol deposition on the Zr based alloy in an optimal process condition. The thickness of manufactured SiC coated layer was measured about 5 μm, and coating layer represented high density structure. SiC coated layer consisted of α-SiC and β-SiC phases, the same as the initial powder. The initial powder was shown to have been crushed to the extent and was deposited in the form of extremely fine particles. To examine the high temperature oxidation properties, oxidized weight gain was obtained for one hour at 1000°C by using TGA. The SiC coated layer showed superior oxidation resistance property than that of Zr alloy (substrate. The high temperature oxidation mechanism of SiC coated layer on Zr alloy was suggested. And then, the application of aerosol deposited SiC coated layer was also discussed.

  16. State of residual stress in laser-deposited ceramic composite coatings on aluminum alloys

    NARCIS (Netherlands)

    Kadolkar, P. B.; Watkins, T. R.; De Hosson, J. Th. M.; Kooi, B. J.; Dahotre, N. B.

    The nature and magnitude of the residual stresses within laser-deposited titanium carbide (TiC) coatings on 2024 and 6061 aluminum (Al) alloys were investigated. Macro- and micro-stresses within the coatings were determined using an X-ray diffraction method. Owing to increased debonding between the

  17. Advanced TiC/a-C : H nanocomposite coatings deposited by magnetron sputtering

    NARCIS (Netherlands)

    Pei, Y.T.; Galvan, D.; Hosson, J.Th.M. De; Strondl, C.

    2006-01-01

    TiC/a-C:H nanocomposite coatings have been deposited by magnetron Sputtering. They consist of 2-5 nm TiC nanocrystallites embedded in the amorphous hydrocarbon (a-C:H) matrix. A transition from a Columnar to a glassy microstructure has been observed in the nanocomposite coatings with increasing

  18. Initial bacterial deposition on bare and zeolite-coated aluminum alloy and stainless steel.

    Science.gov (United States)

    Chen, Gexin; Beving, Derek E; Bedi, Rajwant S; Yan, Yushan S; Walker, Sharon L

    2009-02-03

    In this study, the impact of zeolite thin film coatings on bacterial deposition and "biofouling" of surfaces has been investigated in an aqueous environment. The synthesis of two types of zeolite coatings, ZSM-5 coated on aluminum alloy and zeolite A coated on stainless steel, and the characterization of the coated and bare metal surfaces are described. The extent of cell deposition onto the bare and zeolite-coated aluminum alloy and stainless steel surfaces is investigated in a parallel plate flow chamber system under a laminar flow conditions. The initial rates of bacterial transfer to the various surfaces are compared by utilizing a marine bacterium, Halomonas pacifica g, under a range of ionic strength conditions. H. pacifica g deposited onto bare metal surfaces to a greater extent as compared with cells deposited onto the zeolite coatings. The surface properties found to have the most notable effect on attachment are the electrokinetic and hydrophobicity properties of the metal and zeolite-coated surfaces. These results suggest that a combination of two chemical mechanisms-hydrophobic and electrostatic interactions-contribute to the antifouling nature of the zeolite surface. Additional observations on the relative role of the hydrodynamic and physical phenomena are also discussed.

  19. Microstructural characterization of Co-based coating deposited by low power pulse laser cladding

    NARCIS (Netherlands)

    Farnia, A.; Ghaini, F. Malek; Ocelik, V.; De Hosson, J. Th. M.

    A detailed microstructural study of Stellite 6 coating deposited on a low carbon ferritic steel substrate using preplaced powder method and low power Nd:YAG pulse laser is performed. The grain structure and solidification texture of the coating are investigated by orientation imaging microscopy

  20. Sintering of MnCo2O4 coatings prepared by electrophoretic deposition

    DEFF Research Database (Denmark)

    Bobruk, M.; Molin, Sebastian; Chen, Ming

    2018-01-01

    Sintering of MnCo2O4 coatings prepared by electrophoretic deposition on steel substrates has been studied in air and in reducing-oxidizing atmosphere. Effect of temperature and pO2 on the resulting coating density was evaluated from scanning electron microscopy images of polished cross sections...

  1. Anodized porous titanium coated with Ni-CeO2 deposits for enhancing surface toughness and wear resistance

    Science.gov (United States)

    Zhou, Xiaowei; Ouyang, Chun

    2017-05-01

    In order to make large improvements of surface toughness and wear resistance for pure titanium (Ti) substrate, anodic titanium oxide (ATO) surface with nanoporous structure was coated with the Ni-CeO2 nanocomposite coatings. Regarding TiO2 barrier layer on Ti surface to inhibit its electrochemical activity, pre-treatments were successively processed with anodizing, sensitizing, activating, and then followed by electroless Ni-P film to be acted as an activated layer for electroplating Ni-CeO2 deposits. The existing Pd atoms around ATO nanopores were expected as the heterogeneous nucleation sites for supporting the growing locations of electroless Ni-P film. The innovative of interface design using porous structure was introduced for bonding pinholes to achieve a metallurgical adhesion interface between Ti substrate and surface coatings. Besides the objectives of this work were to elucidate how effects by the adding CeO2 nanoparticles on modifying microstructures and wear mechanisms of Ni-CeO2 nanocomposite coatings. Many efforts of XRD, FE-SEM, TEM and Nanoindentation tests were devoted to comparing different wear behaviors of Ni-CeO2 coatings relative to pure nickel. Results indicated that uniform-distributed Ti nanopores with an average diameter size of ∼200 nm was achieved using the Phosphate-type anodizing solution at DC 150 V. A worn surface without fatigue cracks was observed for TAO surface coated with Ni-CeO2 deposits, showing the existing Ce-rich worn products to be acted as a solid lubricant phase for making a self-healing effect on de-lamination failures. More important, this finding will be the guidelines for Ce-rich precipitations to be expected as the strengthening phase in anodized porous of Ti, Al and Mg alloys for intensifying their surface properties.

  2. Deposition of hybrid organic-inorganic composite coatings using an atmospheric plasma jet system.

    Science.gov (United States)

    Dembele, Amidou; Rahman, Mahfujur; Reid, Ian; Twomey, Barry; MacElroy, J M Don; Dowling, Denis P

    2011-10-01

    The objective of this study is to investigate the influence of alcohol addition on the incorporation of metal oxide nanoparticles into nm thick siloxane coatings. Titanium oxide (TiO2) nanoparticles with diameters of 30-80 nm were incorporated into an atmospheric plasma deposited tetramethylorthosilicate (TMOS) siloxane coating. The TMOS/TiO2 coating was deposited using the atmospheric plasma jet system known as PlasmaStream. In this system the liquid precursor/nanoparticle mixture is nebulised into the plasma. It was observed that prior to being nebulised the TiO2 particles agglomerated and settled over time in the TMOS/TiO2 mixture. In order to obtain a more stable nanoparticle/TMOS suspension the addition of the alcohols methanol, octanol and pentanol to this mixture was investigated. The addition of each of these alcohols was found to stabilise the nanoparticle suspension. The effect of the alcohol was therefore assessed with respect to the properties of the deposited coatings. It was observed that coatings deposited from TMOS/TiO2, with and without the addition of methanol were broadly similar. In contrast the coatings deposited with octanol and pentanol addition to the TMOS/TiO2 mixture were significantly thicker, for a given set of deposition parameters and were also more homogeneous. This would indicate that the alcohol precursor was incorporated into the plasma polymerised siloxane. The incorporation of the organic functionality from the alcohols was confirmed from FTIR spectra of the coatings. The difference in behaviour with alcohol type is likely to be due to the lower boiling point of methanol (65 degrees C), which is lower than the maximum plasma temperature measured at the jet orifice (77 degrees C). This temperature is significantly lower than the 196 degrees C and 136 degrees C boiling points of octanol and pentanol respectively. The friction of the coatings was determined using the Pin-on-disc technique. The more organic coatings deposited with

  3. Thick CrN/NbN multilayer coating deposited by cathodic arc technique

    Energy Technology Data Exchange (ETDEWEB)

    Araujo, Juliano Avelar; Tschiptschin, Andre Paulo; Souza, Roberto Martins, E-mail: antschip@usp.br [Universidade de Sao Paulo (USP), SP (Brazil); Lima, Nelson Batista de [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2017-01-15

    The production of tribological nanoscale multilayer CrN/NbN coatings up to 6 μm thick by Sputtering/HIPIMS has been reported in literature. However, high demanding applications, such as internal combustion engine parts, need thicker coatings (>30 μm). The production of such parts by sputtering would be economically restrictive due to low deposition rates. In this work, nanoscale multilayer CrN/NbN coatings were produced in a high-deposition rate, industrial-size, Cathodic Arc Physical Vapor Deposition (ARC-PVD) chamber, containing three cathodes in alternate positions (Cr/ Nb/Cr). Four 30 μm thick NbN/CrN multilayer coatings with different periodicities (20, 10, 7.5 and 4 nm) were produced. The coatings were characterized by X-Ray Diffraction (XRD) and Transmission Electron Microscopy (TEM). The multilayer coating system was composed of alternate cubic rock salt CrN and NbN layers, coherently strained due to lattice mismatch. The film grew with columnar morphology through the entire stratified structure. The periodicities adopted were maintained throughout the entire coating. The 20 nm periodicity coating showed separate NbN and CrN peaks in the XRD patterns, while for the lower periodicity (≤10nm) coatings, just one intermediate lattice (d-spacing) was detected. An almost linear increase of hardness with decreasing bilayer period indicates that interfacial effects can dominate the hardening mechanisms. (author)

  4. Theoretical prediction of energy release rate for interface crack initiation by thermal stress in environmental barrier coatings for ceramics

    Science.gov (United States)

    Kawai, E.; Umeno, Y.

    2017-05-01

    As weight reduction of turbines for aircraft engines is demanded to improve fuel consumption and curb emission of carbon dioxide, silicon carbide (SiC) fiber reinforced SiC matrix composites (SiC/SiC) are drawing enormous attention as high-pressure turbine materials. For preventing degradation of SiC/SiC, environmental barrier coatings (EBC) for ceramics are deposited on the composites. The purpose of this study is to establish theoretical guidelines for structural design which ensures the mechanical reliability of EBC. We conducted finite element method (FEM) analysis to calculate energy release rates (ERRs) for interface crack initiation due to thermal stress in EBC consisting of Si-based bond coat, Mullite and Ytterbium (Yb)-silicate layers on a SiC/SiC substrate. In the FEM analysis, the thickness of one EBC layer was changed from 25 μm to 200 μm while the thicknesses of the other layers were fixed at 25 μm, 50 μm and 100 μm. We compared ERRs obtained by the FEM analysis and a simple theory for interface crack in a single-layered structure where ERR is estimated as nominal strain energy in the coating layers multiplied by a constant factor (independent of layer thicknesses). We found that, unlike the case of single-layered structures, the multiplication factor is no longer a constant but is determined by the combination of consisting coating layer thicknesses.

  5. Failure Analysis of Multilayered Suspension Plasma-Sprayed Thermal Barrier Coatings for Gas Turbine Applications

    Science.gov (United States)

    Gupta, M.; Markocsan, N.; Rocchio-Heller, R.; Liu, J.; Li, X.-H.; Östergren, L.

    2018-02-01

    Improvement in the performance of thermal barrier coatings (TBCs) is one of the key objectives for further development of gas turbine applications. The material most commonly used as TBC topcoat is yttria-stabilized zirconia (YSZ). However, the usage of YSZ is limited by the operating temperature range which in turn restricts the engine efficiency. Materials such as pyrochlores, perovskites, rare earth garnets are suitable candidates which could replace YSZ as they exhibit lower thermal conductivity and higher phase stability at elevated temperatures. The objective of this work was to investigate different multilayered TBCs consisting of advanced topcoat materials fabricated by suspension plasma spraying (SPS). The investigated topcoat materials were YSZ, dysprosia-stabilized zirconia, gadolinium zirconate, and ceria-yttria-stabilized zirconia. All topcoats were deposited by TriplexPro-210TM plasma spray gun and radial injection of suspension. Lifetime of these samples was examined by thermal cyclic fatigue and thermal shock testing. Microstructure analysis of as-sprayed and failed specimens was performed with scanning electron microscope. The failure mechanisms in each case have been discussed in this article. The results show that SPS could be a promising route to produce multilayered TBCs for high-temperature applications.

  6. Evaluation on the delamination life of isothermally aged plasma sprayed thermal barrier coating

    International Nuclear Information System (INIS)

    Seok, Chang Sung; Koo, Jae Mean; Kim, Dae Jin; Shin, In Hwan; Kim, Mun Young

    2008-01-01

    In this study, disk type of thermal barrier coating system for gas turbine blade was isothermally aged in the furnace changing exposure time and temperature. The aging conditions that delamination occurs were determined by the extensive microscopic analyses and bond tests for each aging condition. The delamination map was drawn from the time-temperature matrix form which summarize the delamination conditions. Finally, a method to draw the delamination life diagram of a thermal barrier coating system by using the delamination map was suggested

  7. Evaluation on the Delamination Life of Isothermally Aged Plasma Sprayed Thermal Barrier Coating

    International Nuclear Information System (INIS)

    Kim, Dae Jin; Shin, In Hwan; Koo, Jae Mean; Seok Chang Sung; Kim, Moon Young

    2009-01-01

    In this study, disk type of thermal barrier coating system for gas turbine blade was isothermally aged in the furnace changing exposure time and temperature. The aging conditions that delamination occurs were determined by the extensive microscopic analyses and bond tests for each aging condition. The delamination map was drawn from the time-temperature matrix form which summarize the delamination conditions. Finally, a method to draw the delamination life diagram of a thermal barrier coating system by using the delamination map was suggested

  8. Evaluation on the Delamination Life of Isothermally Aged Plasma Sprayed Thermal Barrier Coating

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Dae Jin; Shin, In Hwan; Koo, Jae Mean; Seok Chang Sung [Sungkyunkwan University, Seoul (Korea, Republic of); Kim, Moon Young [Kepco Plant Service and Engineering Co., Seongnam (Korea, Republic of)

    2009-02-15

    In this study, disk type of thermal barrier coating system for gas turbine blade was isothermally aged in the furnace changing exposure time and temperature. The aging conditions that delamination occurs were determined by the extensive microscopic analyses and bond tests for each aging condition. The delamination map was drawn from the time-temperature matrix form which summarize the delamination conditions. Finally, a method to draw the delamination life diagram of a thermal barrier coating system by using the delamination map was suggested.

  9. Evaluation on the delamination life of isothermally aged plasma sprayed thermal barrier coating

    Energy Technology Data Exchange (ETDEWEB)

    Seok, Chang Sung; Koo, Jae Mean; Kim, Dae Jin; Shin, In Hwan [Sungkyunkwan Univ., Suwon (Korea, Republic of); Kim, Mun Young [Korea Plant Service and Engineering, Seongnam (Korea, Republic of)

    2008-07-01

    In this study, disk type of thermal barrier coating system for gas turbine blade was isothermally aged in the furnace changing exposure time and temperature. The aging conditions that delamination occurs were determined by the extensive microscopic analyses and bond tests for each aging condition. The delamination map was drawn from the time-temperature matrix form which summarize the delamination conditions. Finally, a method to draw the delamination life diagram of a thermal barrier coating system by using the delamination map was suggested.

  10. Deposition parameters to improve the fouling-release properties of thin siloxane coatings prepared by PACVD

    Science.gov (United States)

    Akesso, Laurent; Navabpour, Parnia; Teer, Dennis; Pettitt, Michala E.; Callow, Maureen E.; Liu, Chen; Su, Xueju; Wang, Su; Zhao, Qi; Donik, Crtomir; Kocijan, Aleksandra; Jenko, Monika; Callow, James A.

    2009-04-01

    A range of SiO x-like coatings was deposited on glass slides from a hexamethylsiloxane precursor by plasma-assisted CVD. The effect of varying deposition parameters, specifically ion cleaning time and HMDSO/O 2 ratios, on the coating properties and antifouling performance was investigated. At low HMDSO/O 2 ratios, the resulting coatings were close to SiO 2. Carbon content in the bulk of the coatings increased with increasing HMDSO/O 2 ratio. Coatings deposited at high HMDSO/O 2 ratios and with the longest cleaning time (30 min), elevated the relative carbon content to 25 atomic %. Surface energies (22-43 mJ/m) were correlated with the degree of surface oxidation and hydrocarbon content. With the exception of the most polar coatings the apolar component of the surface energy ( γLW) was the dominant component. In the most hydrophilic coatings, the Lewis base component of the surface energy ( γ-) was dominant. Significantly improved antifouling performance was detected with the most reduced coatings deposited using the extended ion cleaning times. For both, the removal of sporelings of the marine green alga, Ulvalinza and the initial adhesion of the freshwater bacterium, Pseudomonas fluorescens, there was a strong, positive correlation between strength of attachment and ion cleaning time. Increased ion cleaning time will elevate the deposition temperature, increasing decomposition rates and thus the crosslinking of the polymer. Increased cross-linking may render these coatings less permeable to penetration and mechanical interlocking by the adhesive polymers used by these organisms, thus reducing their adhesion. Films with improved biological performance have potential for use as coatings in the control of biofouling in applications such as heat exchangers, where thin films are important for effective thermal transfer, or optical windows where transparency is important.

  11. Sedimentary architecture and depositional controls of a Holocene wave-dominated barrier-island system

    DEFF Research Database (Denmark)

    Fruergaard, Mikkel; Johannessen, Peter N.; Nielsen, Lars Henrik

    2018-01-01

    control. This study investigates the relative role of forcing conditions, such as antecedent topography, sea-level rise, sediment supply, storms and climate changes, on the evolution of a Holocene wave-dominated barrier-island system. This article presents temporal reconstruction of the depositional...... history of the barrier-island system of Rømø in the Wadden Sea in unprecedented detail, based on ground-penetration radar profiles, sediment cores, high-resolution dating and palynological investigations, and shows that ca 8000 years ago the barrier island formed on a Pleistocene topographic high. During...... the initial phase of barrier evolution the long-term sea-level rise was relatively rapid (ca 9 mm/yr) and the barrier was narrow and frequently overwashed. Sediment supply kept pace with sea-level rise and the barrier-island system mainly aggraded through the deposition of a ca 7 m thick stack of overwash...

  12. Substrate Frequency Effects on Cr x N Coatings Deposited by DC Magnetron Sputtering

    Science.gov (United States)

    Obrosov, Aleksei; Naveed, Muhammad; Volinsky, Alex A.; Weiß, Sabine

    2017-01-01

    Controlled ion bombardment is a popular method to fabricate desirable coating structures and modify their properties. Substrate biasing at high frequencies is a possible technique, which allows higher ion density at the substrate compared with DC current bias. Moreover, high ion energy along with controlled adatom mobility would lead to improved coating growth. This paper focuses on a similar type of study, where effects of coating growth and properties of DC magnetron-sputtered chromium nitride (Cr x N) coatings at various substrate bias frequencies are discussed. Cr x N coatings were deposited by pulsed DC magnetron sputtering on Inconel 718 and (100) silicon substrates at 110, 160 and 280 kHz frequency at low duty cycle. Coating microstructure and morphology were studied by X-ray diffraction (XRD), atomic force microscopy (AFM), scanning electron microscopy (SEM), scratch adhesion testing and nanoindentation. Results indicate a transformation of columnar into glassy structure of Cr x N coatings with the substrate bias frequency increase. This transformation is attributed to preferential formation of the Cr2N phase at high frequencies compared with CrN at low frequencies. Increase in frequency leads to an increase in deposition rate, which is believed to be due to increase in plasma ion density and energy of the incident adatoms. An increase in coating hardness along with decrease in elastic modulus was observed at high frequencies. Scratch tests show a slight increase in coating adhesion, whereas no clear increase in coating roughness can be found with the substrate bias frequency.

  13. Thermal stability of double-ceramic-layer thermal barrier coatings with various coating thickness

    International Nuclear Information System (INIS)

    Dai Hui; Zhong Xinghua; Li Jiayan; Zhang Yanfei; Meng Jian; Cao Xueqiang

    2006-01-01

    Double-ceramic-layer (DCL) coatings with various thickness ratios composed of YSZ (6-8 wt.% Y 2 O 3 + ZrO 2 ) and lanthanum zirconate (LZ, La 2 Zr 2 O 7 ) were produced by the atmospheric plasma spraying. Chemical stability of LZ in contact with YSZ in DCL coatings was investigated by calcining powder blends at different temperatures. No obvious reaction was observed when the calcination temperature was lower than 1250 deg. C, implying that LZ and YSZ had good chemical applicability for producing DCL coating. The thermal cycling test indicate that the cycling lives of the DCL coatings are strongly dependent on the thickness ratio of LZ and YSZ, and the coatings with YSZ thickness between 150 and 200 μm have even longer lives than the single-layer YSZ coating. When the YSZ layer is thinner than 100 μm, the DCL coatings failed in the LZ layer close to the interface of YSZ layer and LZ layer. For the coatings with the YSZ thickness above 150 μm, the failure mainly occurs at the interface of the YSZ layer and the bond coat

  14. Gas phase deposition of oxide and metal-oxide coatings on fuel particles

    International Nuclear Information System (INIS)

    Patokin, A.P.; Khrebtov, V.L.; Shirokov, B.M.

    2008-01-01

    Production processes and properties of oxide (Al 2 O 3 , ZrO 2 ) and metal-oxide (Mo-Al 2 O 3 , Mo-ZrO 2 , W-Al 2 O 3 , W-ZrO 2 ) coatings on molybdenum substrates and uranium dioxide fuel particles were investigated. It is shown that the main factors that have an effect on the deposition rate, density, microstructure and other properties of coatings are the deposition temperature, the ratio of H 2 and CO 2 flow rates, the total reactor pressure and the ratio of partial pressures of corresponding metal chlorides during formation of metal-oxide coatings

  15. Sintering Characteristics of Multilayered Thermal Barrier Coatings Under Thermal Gradient and Isothermal High Temperature Annealing Conditions

    Science.gov (United States)

    Rai, Amarendra K.; Schmitt, Michael P.; Bhattacharya, Rabi; Zhu, Dongming; Wolfe, Douglas E.

    2014-01-01

    Pyrochlore oxides have most of the relevant attributes for use as next generation thermal barrier coatings such as phase stability, low sintering kinetics and low thermal conductivity. One of the issues with the pyrochlore oxides is their lower toughness and therefore higher erosion rate compared to the current state-of-the-art TBC material, yttria (6 to 8 wt%) stabilized zirconia (YSZ). In this work, sintering characteristics were investigated for novel multilayered coating consisted of alternating layers of pyrochlore oxide viz Gd2Zr2O7 and t' low k (rare earth oxide doped YSZ). Thermal gradient and isothermal high temperature (1316 C) annealing conditions were used to investigate sintering and cracking in these coatings. The results are then compared with that of relevant monolayered coatings and a baseline YSZ coating.

  16. It takes more than a coating to get nanoparticles through the intestinal barrier in vitro.

    Science.gov (United States)

    Lichtenstein, Dajana; Ebmeyer, Johanna; Meyer, Thomas; Behr, Anne-Cathrin; Kästner, Claudia; Böhmert, Linda; Juling, Sabine; Niemann, Birgit; Fahrenson, Christoph; Selve, Sören; Thünemann, Andreas F; Meijer, Jan; Estrela-Lopis, Irina; Braeuning, Albert; Lampen, Alfonso

    2017-09-01

    Size and shape are crucial parameters which have impact on the potential of nanoparticles to penetrate cell membranes and epithelial barriers. Current research in nanotoxicology additionally focuses on particle coating. To distinguish between core- and coating-related effects in nanoparticle uptake and translocation, two nanoparticles equal in size, coating and charge but different in core material were investigated. Silver and iron oxide nanoparticles coated with poly (acrylic acid) were chosen and extensively characterized by small-angle x-ray scattering, nanoparticle tracing analysis and transmission electron microscopy (TEM). Uptake and transport were studied in the intestinal Caco-2 model in a Transwell system with subsequent elemental analysis. TEM and ion beam microscopy were conducted for particle visualization. Although equal in size, charge and coating, the behavior of the two particles in Caco-2 cells was different: while the internalized amount was comparable, only iron oxide nanoparticles additionally passed the epithelium. Our findings suggest that the coating material influenced only the uptake of the nanoparticles whereas the translocation was determined by the core material. Knowledge about the different roles of the particle coating and core materials in crossing biological barriers will facilitate toxicological risk assessment of nanoparticles and contribute to the optimization of pharmacokinetic properties of nano-scaled pharmaceuticals. Copyright © 2016 Elsevier B.V. All rights reserved.

  17. Thermal shock behavior of toughened gadolinium zirconate/YSZ double-ceramic-layered thermal barrier coating

    International Nuclear Information System (INIS)

    Zhong, Xinghua; Zhao, Huayu; Zhou, Xiaming; Liu, Chenguang; Wang, Liang; Shao, Fang; Yang, Kai; Tao, Shunyan; Ding, Chuanxian

    2014-01-01

    Highlights: • Gd 2 Zr 2 O 7 /YSZ DCL thermal barrier coating was designed and fabricated. • The Gd 2 Zr 2 O 7 top ceramic layer was toughened by addition of nanostructured 3YSZ. • Remarkable improvement in thermal shock resistance of the DCL coating was achieved. - Abstract: Double-ceramic-layered (DCL) thermal barrier coating system comprising of toughened Gadolinium zirconate (Gd 2 Zr 2 O 7 , GZ) as the top ceramic layer and 4.5 mol% Y 2 O 3 partially-stabilized ZrO 2 (4.5YSZ) as the bottom ceramic layer was fabricated by plasma spraying and thermal shock behavior of the DCL coating was investigated. The GZ top ceramic layer was toughened by addition of nanostructured 3 mol% Y 2 O 3 partially-stabilized ZrO 2 (3YSZ) to improve fracture toughness of the matrix. The thermal shock resistance of the DCL coating was enhanced significantly compared to that of single-ceramic-layered (SCL) GZ-3YSZ composite coating, which is believed to be primarily attributed to the two factors: (i) the increase in fracture toughness of the top ceramic layer by incorporating nanostructured YSZ particles and (ii) the improvement in strain tolerance through the utilization of 4.5YSZ as the bottom ceramic layer. In addition, the failure mechanisms are mainly attributed to the still low fracture toughness of the top ceramic layer and oxidation of the bond-coat

  18. The effect of biodegradable coatings on the barrier properties of papers

    Directory of Open Access Journals (Sweden)

    rouzbeh asadi khansari

    2016-06-01

    Full Text Available The objective of this work was to compare barrier property of biodegradable coatings on two base papers. Two different paper grades differing in structure (Kraft liner and printing & writing papers were used. The papers are made in Mazandaran wood and paper industry. Coating materials with 30% solid content, included clay (100 parts and cationic starch (12 parts, and they were mixed with two binders (PLA 10 parts and PVA 10 parts for two formulations. The immersion method in both levels 1 and 2 minutes and two coating formulations were applied on papers. Then, the treated samples were dried in standard conditions of temperature (25◦C and 54% humidity in the room. For that purpose, air resistance or porosity, thickness, mass, and Cobb60 were determined. As expected, time of treatment, reduced porosity and increased coating weight, but in terms of barrier properties, combination containing PVA was more effective than PLA. In comparison to the control group, all the treated samples had higher air resistance and water absorption, which the increment of water absorption is due to increased capillary in texture paper. The analysis of results showed that the immersion coating factors had considerable effects on performance of air resistance improvement and coating weight of papers. Then, calculated values of the thickness and density of coating were evaluated, which confirmed the status of water absorption. The treatments greatly increased the wettability of the surface by water.

  19. Optimization of High Porosity Thermal Barrier Coatings Generated with a Porosity Former

    Science.gov (United States)

    Medřický, Jan; Curry, Nicholas; Pala, Zdenek; Vilemova, Monika; Chraska, Tomas; Johansson, Jimmy; Markocsan, Nicolaie

    2015-04-01

    Yttria-stabilized zirconia thermal barrier coatings are extensively used in turbine industry; however, increasing performance requirements have begun to make conventional air plasma sprayed coatings insufficient for future needs. Since the thermal conductivity of bulk material cannot be lowered easily; the design of highly porous coatings may be the most efficient way to achieve coatings with low thermal conductivity. Thus the approach of fabrication of coatings with a high porosity level based on plasma spraying of ceramic particles of dysprosia-stabilized zirconia mixed with polymer particles, has been tested. Both polymer and ceramic particles melt in plasma and after impact onto a substrate they form a coating. When the coating is subjected to heat treatment, polymer burns out and a complex structure of pores and cracks is formed. In order to obtain desired porosity level and microstructural features in coatings; a design of experiments, based on changes in spray distance, powder feeding rate, and plasma-forming atmosphere, was performed. Acquired coatings were evaluated for thermal conductivity and thermo-cyclic fatigue, and their morphology was assessed using scanning electron microscopy. It was shown that porosity level can be controlled by appropriate changes in spraying parameters.

  20. Interface control of atomic layer deposited oxide coatings by filtered cathodic arc deposited sublayers for improved corrosion protection

    Energy Technology Data Exchange (ETDEWEB)

    Härkönen, Emma, E-mail: emma.harkonen@helsinki.fi [Laboratory of Inorganic Chemistry, University of Helsinki, P.O. Box 55, FIN-00014 Helsinki (Finland); Tervakangas, Sanna; Kolehmainen, Jukka [DIARC-Technology Inc., Espoo (Finland); Díaz, Belén; Światowska, Jolanta; Maurice, Vincent; Seyeux, Antoine; Marcus, Philippe [Laboratoire de Physico-Chimie des Surfaces, CNRS (UMR 7075) – Chimie ParisTech (ENSCP), F-75005 Paris (France); Fenker, Martin [FEM Research Institute, Precious Metals and Metals Chemistry, D-73525 Schwäbisch Gmünd (Germany); Tóth, Lajos; Radnóczi, György [Research Centre for Natural Sciences HAS, (MTA TKK), Budapest (Hungary); Ritala, Mikko [Laboratory of Inorganic Chemistry, University of Helsinki, P.O. Box 55, FIN-00014 Helsinki (Finland)

    2014-10-15

    Sublayers grown with filtered cathodic arc deposition (FCAD) were added under atomic layer deposited (ALD) oxide coatings for interface control and improved corrosion protection of low alloy steel. The FCAD sublayer was either Ta:O or Cr:O–Ta:O nanolaminate, and the ALD layer was Al{sub 2}O{sub 3}–Ta{sub 2}O{sub 5} nanolaminate, Al{sub x}Ta{sub y}O{sub z} mixture or graded mixture. The total thicknesses of the FCAD/ALD duplex coatings were between 65 and 120 nm. Thorough analysis of the coatings was conducted to gain insight into the influence of the FCAD sublayer on the overall coating performance. Similar characteristics as with single FCAD and ALD coatings on steel were found in the morphology and composition of the duplex coatings. However, the FCAD process allowed better control of the interface with the steel by reducing the native oxide and preventing its regrowth during the initial stages of the ALD process. Residual hydrocarbon impurities were buried in the interface between the FCAD layer and steel. This enabled growth of ALD layers with improved electrochemical sealing properties, inhibiting the development of localized corrosion by pitting during immersion in acidic NaCl and enhancing durability in neutral salt spray testing. - Highlights: • Corrosion protection properties of ALD coatings were improved by FCAD sublayers. • The FCAD sublayer enabled control of the coating-substrate interface. • The duplex coatings offered improved sealing properties and durability in NSS. • The protective properties were maintained during immersion in a corrosive solution. • The improvements were due to a more ideal ALD growth on the homogeneous FCAD oxide.

  1. Co3O4 protective coatings prepared by Pulsed Injection Metal Organic Chemical Vapour Deposition

    DEFF Research Database (Denmark)

    Burriel, M.; Garcia, G.; Santiso, J.

    2005-01-01

    of deposition temperature. Pure Co3O4 spinel structure was found for deposition temperatures ranging from 360 to 540 degreesC. The optimum experimental parameters to prepare dense layers with a high growth rate were determined and used to prepare corrosion protective coatings for Fe-22Cr metallic interconnects...

  2. Novel GIMS technique for deposition of colored Ti/TiO₂ coatings on industrial scale

    Directory of Open Access Journals (Sweden)

    Zdunek Krzysztof

    2016-03-01

    Full Text Available The aim of the present paper has been to verify the effectiveness and usefulness of a novel deposition process named GIMS (Gas Injection Magnetron Sputtering used for the flrst time for deposition of Ti/TiO₂ coatings on large area glass Substrates covered in the condition of industrial scale production. The Ti/TiO₂ coatings were deposited in an industrial System utilizing a set of linear magnetrons with the length of 2400 mm each for covering the 2000 × 3000 mm glasses. Taking into account the speciflc course of the GIMS (multipoint gas injection along the magnetron length and the scale of the industrial facility, the optical coating uniformity was the most important goal to check. The experiments on Ti/TiO₂ coatings deposited by the use of GIMS were conducted on Substrates in the form of glass plates located at the key points along the magnetrons and intentionally non-heated during any stage of the process. Measurements of the coatings properties showed that the thickness and optical uniformity of the 150 nm thick coatings deposited by GIMS in the industrial facility (the thickness differences on the large plates with 2000 mm width did not exceed 20 nm is fully acceptable form the point of view of expected applications e.g. for architectural glazing.

  3. Electro-spark deposition: A technique for producing wear resistant coatings

    Energy Technology Data Exchange (ETDEWEB)

    Sheldon, G.L. (Washington State Univ., Pullman, WA (USA)); Johnson, R.N. (Westinghouse Hanford Co., Richland, WA (USA))

    1984-12-01

    Electro-spark deposition (ESD) is a coating process using short duration, high current electrical pulses to deposit an electrode material on a metallic substrate. A principal attribute of the process is its ability to apply metallurgically bonded coatings with such a low total heat input that the bulk substrate material remains at or near ambient temperatures. A review of the process is briefly given, then current research using WC-TiC and Cr{sub 3}C{sub 2} electrodes to deposit coatings on Type 316 stainless steel and other substrates is presented. The ESD carbide coatings were found to be exceptionally hard, wear-resistant and spalling-resistant in high-stress rubbing tests. Several applications for nuclear reactor components are described. 17 refs., 18 figs., 1 tab.

  4. The effect of number of nano structural coating containing Ti and Ru created by electro deposition

    Science.gov (United States)

    Ardi, Simin; Asl, Shahin Khamene; Hoseini, Mirghasem; Pouladvand, Iman

    2018-01-01

    TiO2 and RuO2 have many applications in the field of photocataliysis, environmental protection, high charge storage capacity devices and etc. Electro deposition offers advantages such as rigid control of film thickness, uniformity and deposition rate. Electro deposition of RuO2-TiO2 coatings on Ti substrates was performed via hydrolysis by electro generated based of TiCl4 and RuCl3 salts dissolved in mixed methyl alcohol-water solvent in presence of hydrogen peroxide for one, three and six layer. The obtained coatings have been heated in electric furnace at 500 ˚C. Results show that coating with six layers on Ti substrate is the useful coating

  5. Electrophoretic deposition and electrochemical behavior of novel graphene oxide-hyaluronic acid-hydroxyapatite nanocomposite coatings

    Energy Technology Data Exchange (ETDEWEB)

    Li, Ming; Liu, Qian; Jia, Zhaojun; Xu, Xuchen; Shi, Yuying [Center for Biomedical Materials and Tissue Engineering, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871 (China); Cheng, Yan, E-mail: chengyan@pku.edu.cn [Center for Biomedical Materials and Tissue Engineering, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871 (China); Zheng, Yufeng [Center for Biomedical Materials and Tissue Engineering, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871 (China); Department of Materials Science and Engineering, College of Engineering, Peking University, Beijing 100871 (China); Xi, Tingfei [Center for Biomedical Materials and Tissue Engineering, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871 (China); Wei, Shicheng [Center for Biomedical Materials and Tissue Engineering, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871 (China); Department of Oral and Maxillofacial Surgery, School of Stomatology, Peking University, Beijing 100081 (China)

    2013-11-01

    Novel ternary graphene oxide-hyaluronic acid-hydroxyapatite (GO-HY-HA) nanocomposite coatings were prepared on Ti substrate using anodic electrophoretic deposition (EPD). Hyaluronic acid was employed as charging additive and dispersion agent during EPD. The kinetics and mechanism of the deposition, and the microstructure of the coated samples were investigated using scanning electron microscopy, X-ray diffraction, Raman spectrum, thermo-gravimetric analysis, and microscopic Fourier transform infrared analysis. The results showed that the addition of GO sheets into the HY-HA suspensions could increase the deposition rate and inhibit cracks creation and propagation in the coatings. The corrosion resistant of the resulting samples were evaluated using potentiodynamic polarization method in simulated body fluid, and the GO-HY-HA coatings could effectively improve the anti-corrosion property of the Ti substrate.

  6. Nickel coating on high strength low alloy steel by pulse current deposition

    Science.gov (United States)

    Nigam, S.; Patel, S. K.; Mahapatra, S. S.; Sharma, N.; Ghosh, K. S.

    2015-02-01

    Nickel is a silvery-white metal mostly used to enhance the value, utility, and lifespan of industrial equipment and components by protecting them from corrosion. Nickel is commonly used in the chemical and food processing industries to prevent iron from contamination. Since the properties of nickel can be controlled and varied over broad ranges, nickel plating finds numerous applications in industries. In the present investigation, pulse current electro-deposition technique has been used to deposit nickel on a high strength low alloy (HSLA) steel substrate.Coating of nickel is confirmed by X-ray diffraction (XRD) and EDAX analysis. Optical microscopy and SEM is used to assess the coating characteristics. Electrochemical polarization study has been carried out to study the corrosion behaviour of nickel coating and the polarisation curves have revealed that current density used during pulse electro-deposition plays a vital role on characteristics of nickel coating.

  7. Water Vapor Sorption and Diffusion in Secondary Dispersion Barrier Coatings: A Critical Comparison with Emulsion Polymers.

    Science.gov (United States)

    Liu, Yang; Soer, Willem-Jan; Scheerder, Jürgen; Satgurunathan, Guru; Keddie, Joseph L

    2015-06-10

    The conventional method for synthesizing waterborne polymer colloids is emulsion polymerization using surfactants. An emerging method is the use of secondary dispersions (SD) of polymers in water, which avoids the addition of any surfactant. Although there are numerous studies of the water barrier properties (sorption, diffusion, and permeability) of waterborne emulsion (Em) polymer coatings, the properties of SD coatings, in comparison, have not been thoroughly investigated. Here, dynamic water vapor sorption analysis is used to compare the equilibrium sorption isotherms of the two forms of styrene-acrylate copolymers (Em and SD) with the same monomer composition. From an analysis of the kinetics of vapor sorption, the diffusion coefficient of water in the polymer coatings is determined. The combined effects of particle boundaries and surfactant addition were investigated through a comparison of the properties of SD and Em coatings to those of (1) solvent-cast polymer coatings (of the same monomer composition), (2) Em polymers that underwent dialysis to partially remove the water-soluble species, and (3) SD polymers with added surfactants. The results reveal that both the particle boundaries and the surfactants increase vapor sorption. The diffusion coefficients of water are comparable in magnitude in all of the polymer systems but are inversely related to water activity because of molecular clustering. Compared to all of the other waterborne polymer systems, the SD barrier coatings show the lowest equilibrium vapor sorption and permeability coefficients at high relative humidities as well as the lowest water diffusion coefficient at low humidities. These barrier properties make SD coatings an attractive alternative to conventional emulsion polymer coatings.

  8. The erosion performance of cold spray deposited metal matrix composite coatings with subsequent friction stir processing

    Energy Technology Data Exchange (ETDEWEB)

    Peat, Tom, E-mail: tompeat12@gmail.com [Department of Mechanical & Aerospace Engineering, University of Strathclyde, James Weir Building, 75 Montrose Street, Glasgow G1 1XJ (United Kingdom); Galloway, Alexander; Toumpis, Athanasios [Department of Mechanical & Aerospace Engineering, University of Strathclyde, James Weir Building, 75 Montrose Street, Glasgow G1 1XJ (United Kingdom); McNutt, Philip [TWI Ltd., Granta Park, Cambridge CB21 6AL (United Kingdom); Iqbal, Naveed [TWI Technology Centre, Wallis Way, Catcliff, Rotherham, S60 5TZ (United Kingdom)

    2017-02-28

    Highlights: • WC-CoCr, Cr{sub 3}C{sub 2}-NiCr and Al{sub 2}O{sub 3} coatings were cold spray deposited on AA5083 and friction stir processed. • The SprayStirred WC-CoCr demonstrated a hardness increase of 100% over the cold sprayed coating. • As-deposited and SprayStirred coatings were examined under slurry erosion test conditions. • Mass and volume loss was measured following 20-min exposure to the slurry. • The WC-CoCr and Al2O3 demonstrated a reduction in volume loss of approx. 40% over the cold sprayed coating. - Abstract: This study forms an initial investigation into the development of SprayStir, an innovative processing technique for generating erosion resistant surface layers on a chosen substrate material. Tungsten carbide – cobalt chromium, chromium carbide – nickel chromium and aluminium oxide coatings were successfully cold spray deposited on AA5083 grade aluminium. In order to improve the deposition efficiency of the cold spray process, coatings were co-deposited with powdered AA5083 using a twin powder feed system that resulted in thick (>300 μm) composite coatings. The deposited coatings were subsequently friction stir processed to embed the particles in the substrate in order to generate a metal matrix composite (MMC) surface layer. The primary aim of this investigation was to examine the erosion performance of the SprayStirred surfaces and demonstrate the benefits of this novel process as a surface engineering technique. Volumetric analysis of the SprayStirred surfaces highlighted a drop of approx. 40% in the level of material loss when compared with the cold spray deposited coating prior to friction stir processing. Micro-hardness testing revealed that in the case of WC-CoCr reinforced coating, the hardness of the SprayStirred material exhibits an increase of approx. 540% over the unaltered substrate and 120% over the as-deposited composite coating. Microstructural examination demonstrated that the increase in the hardness of the

  9. Mechanisms Underpinning Degradation of Protective Oxides and Thermal Barrier Coatings in High Hydrogen Content (HHC) - Fueled Turbines

    Energy Technology Data Exchange (ETDEWEB)

    Mumm, Daniel

    2013-08-31

    The overarching goal of this research program has been to evaluate the potential impacts of coal-derived syngas and high-hydrogen content fuels on the degradation of turbine hot-section components through attack of protective oxides and thermal barrier coatings. The primary focus of this research program has been to explore mechanisms underpinning the observed degradation processes, and connections to the combustion environments and characteristic non-combustible constituents. Based on the mechanistic understanding of how these emerging fuel streams affect materials degradation, the ultimate goal of the program is to advance the goals of the Advanced Turbine Program by developing materials design protocols leading to turbine hot-section components with improved resistance to service lifetime degradation under advanced fuels exposures. This research program has been focused on studying how: (1) differing combustion environments – relative to traditional natural gas fired systems – affect both the growth rate of thermally grown oxide (TGO) layers and the stability of these oxides and of protective thermal barrier coatings (TBCs); and (2) how low levels of fuel impurities and characteristic non-combustibles interact with surface oxides, for instance through the development of molten deposits that lead to hot corrosion of protective TBC coatings. The overall program has been comprised of six inter-related themes, each comprising a research thrust over the program period, including: (i) evaluating the role of syngas and high hydrogen content (HHC) combustion environments in modifying component surface temperatures, heat transfer to the TBC coatings, and thermal gradients within these coatings; (ii) understanding the instability of TBC coatings in the syngas and high hydrogen environment with regards to decomposition, phase changes and sintering; (iii) characterizing ash deposition, molten phase development and infiltration, and associated corrosive

  10. Effect of C/Si Ratio on the Electrochemical Behavior of a-SiCx:H Coatings on SS301 Substrate Deposited by PECVD

    Directory of Open Access Journals (Sweden)

    D. Li

    2014-01-01

    Full Text Available Amorphous hydrogenated silicon carbide (a-SiCx:H coatings were deposited on stainless steel 301 (SS301 using plasma enhanced chemical vapor deposition with the methane gas flow ranging from 30 to 90 sccm. XRD spectra confirmed the amorphous structure of these coatings. The as-deposited coatings all exhibited homogenous dense feature, and no porosities were observed in SEM and AFM analysis. The a-SiCx:H coatings remarkably increased the corrosion resistance of the SS301 substrate. With the increase of the C concentration, the a-SiCx:H coatings exhibited significantly enhanced electrochemical behavior. The a-SiCx:H coating with the highest carbon concentration acted as an excellent barrier to charge transfer, with a corrosion current of 3.5×10-12 A/cm2 and a breakdown voltage of 1.36 V, compared to 2.5×10-8 A/cm2 and 0.34 V for the SS301 substrate.

  11. A Study of Deposition Coatings Formed by Electroformed Metallic Materials

    OpenAIRE

    Hayashi, Shoji; Sugiyama, Shuta; Shimura, Kojiro; Tobayama, Go; Togashi, Toshio

    2016-01-01

    Major joining methods of dental casting metal include brazing and laser welding. However, brazing cannot be applied for electroformed metals since heat treatment could affect the fit, and, therefore, laser welding is used for such metals. New methods of joining metals that do not impair the characteristics of electroformed metals should be developed. When new coating is performed on the surface of the base metal, surface treatment is usually performed before re-coating. The effect of surface ...

  12. Galvanic deposition and characterization of brushite/hydroxyapatite coatings on 316L stainless steel

    Energy Technology Data Exchange (ETDEWEB)

    Blanda, Giuseppe [Laboratorio di Chimica Fisica Applicata, Dipartimento di Ingegneria Chimica Gestionale Informatica Meccanica, Università di Palermo, Viale delle Scienze, 90128 Palermo (Italy); Brucato, Valerio; Pavia, Francesco Carfì; Greco, Silvia [Dipartimento di Ingegneria Civile, Ambientale, Aerospaziale, dei Materiali, Università di Palermo, Viale delle Scienze, 90128 Palermo (Italy); Piazza, Salvatore; Sunseri, Carmelo [Laboratorio di Chimica Fisica Applicata, Dipartimento di Ingegneria Chimica Gestionale Informatica Meccanica, Università di Palermo, Viale delle Scienze, 90128 Palermo (Italy); Inguanta, Rosalinda, E-mail: rosalinda.inguanta@unipa.it [Laboratorio di Chimica Fisica Applicata, Dipartimento di Ingegneria Chimica Gestionale Informatica Meccanica, Università di Palermo, Viale delle Scienze, 90128 Palermo (Italy)

    2016-07-01

    In this work, brushite and brushite/hydroxyapatite (BS, CaHPO{sub 4}·H{sub 2}O; HA, Ca{sub 10}(PO{sub 4}){sub 6}(OH){sub 2}) coatings were deposited on 316L stainless steel (316LSS) from a solution containing Ca(NO{sub 3}){sub 2}·4H{sub 2}O and NH{sub 4}H{sub 2}PO{sub 4} by a displacement reaction based on a galvanic contact, where zinc acts as sacrificial anode. Driving force for the cementation reaction arises from the difference in the electrochemical standard potentials of two different metallic materials (316LSS and Zn) immersed in an electrolyte, so forming a galvanic contact leading to the deposition of BS/HA on nobler metal. We found that temperature and deposition time affect coating features (morphology, structure, and composition). Deposits were characterized by means of several techniques. The morphology was investigated by scanning electron microscopy, the elemental composition was obtained by X-ray energy dispersive spectroscopy, whilst the structure was identified by Raman spectroscopy and X-ray diffraction. BS was deposited at all investigated temperatures covering the 316LSS surface. At low and moderate temperature, BS coatings were compact, uniform and with good crystalline degree. On BS layers, HA crystals were obtained at 50 °C for all deposition times, while at 25 °C, its presence was revealed only after long deposition time. Electrochemical studies show remarkable improvement in corrosion resistance. - Highlights: • Brushite/hydroxyapatite coatings were obtained by a galvanic deposition method. • Galvanic deposition is simple and cheap and does not require external power supply. • Temperature is a key parameter to control composition and morphology of coatings. • Ca/P ratio changes with deposition time, from about 1 up to an optimum value of 1.7. • Compact and adherent layer covering substrate surface were obtained on 316LSS.

  13. Plasma Assisted Chemical Vapour Deposition – Technological Design Of Functional Coatings

    Directory of Open Access Journals (Sweden)

    Januś M.

    2015-06-01

    Full Text Available Plasma Assisted Chemical Vapour Deposition (PA CVD method allows to deposit of homogeneous, well-adhesive coatings at lower temperature on different substrates. Plasmochemical treatment significantly impacts on physicochemical parameters of modified surfaces. In this study we present the overview of the possibilities of plasma processes for the deposition of diamond-like carbon coatings doped Si and/or N atoms on the Ti Grade2, aluminum-zinc alloy and polyetherketone substrate. Depending on the type of modified substrate had improved the corrosion properties including biocompatibility of titanium surface, increase of surface hardness with deposition of good adhesion and fine-grained coatings (in the case of Al-Zn alloy and improving of the wear resistance (in the case of PEEK substrate.

  14. Novel composite cBN-TiN coating deposition method: structure and performance in metal cutting

    International Nuclear Information System (INIS)

    Russell, W.C.; Malshe, A.P.; Yedave, S.N.; Brown, W.D.

    2001-01-01

    Cubic boron nitride coatings are under development for a variety of applications but stabilization of the pure cBN form and adhesion of films deposited by PVD and ion-based methods has been difficult. An alternative method for depositing a composite cBN-TiN film has been developed for wear related applications. The coating is deposited in a two-stage process utilizing ESC (electrostatic spray coating) and CVI (chemical vapor infiltration). Fully dense films of cBN particles evenly dispersed in a continuous TiN matrix have been developed. Testing in metal cutting has shown an increase in tool life (turning - 4340 steel) of three to seven times, depending of machining parameters, in comparison with CVD deposited TiN films. (author)

  15. Failure of thermal barrier coatings under thermal and mechanical fatigue loading. Microstructural observations and modelling aspects

    Energy Technology Data Exchange (ETDEWEB)

    Brodin, Haakan

    2004-09-01

    Industrial and air-borne gas turbine hot components suffer from creep, oxidation, corrosion and microstructural degradation if not shielded from the hot and aggressive combustion gases. Two major strategies commercially available are adopted; film cooling by pressurised air and application of protective coatings. Protective coatings form a slow-growing oxide that protects from oxidation and corrosion. By application of a thermal insulator, a thermal barrier coating, the material will be protected from high temperature through good insulation properties of the coating system. If thermal barrier coatings are to be used in situations where capabilities and possibilities for inspections are limited, better knowledge of the fatigue properties of the coatings is also needed. Therefore development of a reliable fatigue life model is needed. The present work aims at serving as a basis from which a general physically founded thermal barrier coating life model can be formulated. The effects of exposure to high temperatures and mechanical loads on thermal barrier coatings under service like conditions have been investigated in the present thesis. Emphasis is put on the coupling between materials science and solid mechanics approaches in order to establish a better knowledge concerning degradation mechanisms and fatigue life issues than what is common if only one discipline is explored. Investigations of material exposed to isothermal oxidation and thermal cyclic fatigue were performed on plasma-sprayed systems with NiCoCrAlY or NiCrAlY bond coats and yttria partially stabilised zirconia top coats. It has been shown that the thermally grown oxide that will form upon high temperature exposure influences the failure behaviour. If the oxide is composed mainly of alumina, the fatigue properties are good since the adhesion between the ceramic top coat and the metallic bond coat is good. This is also shown in a comparison between different plasma sprayed thermal barrier coating

  16. Nano-Ag-loaded hydroxyapatite coatings on titanium surfaces by electrochemical deposition.

    Science.gov (United States)

    Lu, Xiong; Zhang, Bailin; Wang, Yingbo; Zhou, Xianli; Weng, Jie; Qu, Shuxin; Feng, Bo; Watari, Fumio; Ding, Yonghui; Leng, Yang

    2011-04-06

    Hydroxyapatite (HA) coatings on titanium (Ti) substrates have attracted much attention owing to the combination of good mechanical properties of Ti and superior biocompatibility of HA. Incorporating silver (Ag) into HA coatings is an effective method to impart the coatings with antibacterial properties. However, the uniform distribution of Ag is still a challenge and Ag particles in the coatings are easy to agglomerate, which in turn affects the applications of the coatings. In this study, we employed pulsed electrochemical deposition to co-deposit HA and Ag simultaneously, which realized the uniform distribution of Ag particles in the coatings. This method was based on the use of a well-designed electrolyte containing Ag ions, calcium ions and l-cysteine, in which cysteine acted as the coordination agent to stabilize Ag ions. The antibacterial and cell culture tests were used to evaluate the antibacterial properties and biocompatibility of HA/Ag composite coatings, respectively. The results indicated the as-prepared coatings had good antibacterial properties and biocompatibility. However, an appropriate silver content should be chosen to balance the biocompatibility and antibacterial properties. Heat treatments promoted the adhesive strength and enhanced the biocompatibility without sacrificing the antibacterial properties of the HA/Ag coatings. In summary, this study provided an alternative method to prepare bioactive surfaces with bactericidal ability for biomedical devices.

  17. Pulsed Laser Deposition Processing of Improved Titanium Nitride Coatings for Implant Applications

    Science.gov (United States)

    Haywood, Talisha M.

    Recently surface coating technology has attracted considerable attention of researchers to develop novel coatings with enhanced functional properties such as hardness, biocompatibility, wear and corrosion resistance for medical devices and surgical tools. The materials currently being used for surgical implants include predominantly stainless steel (316L), cobalt chromium (Co-Cr), titanium and its alloys. Some of the limitations of these implants include improper mechanical properties, corrosion resistance, cytotoxicity and bonding with bone. One of the ways to improve the performance and biocompatibility of these implants is to coat their surfaces with biocompatible materials. Among the various coating materials, titanium nitride (TiN) shows excellent mechanical properties, corrosion resistance and low cytotoxicity. In the present work, a systematic study of pulsed laser ablation processing of TiN coatings was conducted. TiN thin film coatings were grown on commercially pure titanium (Ti) and stainless steel (316L) substrates at different substrate temperatures and different nitrogen partial pressures using the pulsed laser deposition (PLD) technique. Microstructural, surface, mechanical, chemical, corrosion and biological analysis techniques were applied to characterize the TiN thin film coatings. The PLD processed TiN thin film coatings showed improvements in mechanical strength, corrosion resistance and biocompatibility when compared to the bare substrates. The enhanced performance properties of the TiN thin film coatings were a result of the changing and varying of the deposition parameters.

  18. Evaluation of Defects of Thermal Barrier Coatings by Thermal Shock Test Using Eddy Current Testing

    Energy Technology Data Exchange (ETDEWEB)

    Heo, Tae Hoon; Cho, Youn Ho; Lee, Joon Hyun [Pusan National University, Busan (Korea, Republic of); Oh, Jeong Seok; Lee, Koo Hyun [KIMM, Daejeon (Korea, Republic of)

    2009-10-15

    Periodical thermal shock can introduce defects in thermal barrier coating made by layers of CoNiCrAlY bond coating(BC) and ZrO{sub 2}-8wt%Y{sub 2}O{sub 3} ceramic top coating(TC) on Inconel-738 substrate using plasma spraying. Thermal shock test is performed by severe condition that is to heat until 1000 .deg. C and cool until 20 .deg. C. As the number of cycle is increased, the fatigue by thermal shock is also increased. After test, the micro-structures and mechanical characteristics of thermal barrier coating were investigated by SEM, XRD. The TGO layer of is Al{sub 2}O{sub 3} formed between BC and TC by periodical thermal shock test, and its change in thickness is inspected by eddy current test(ECT). By ECT test, it is shown that TGO and micro-crack can be detected and it is possible to predict the life of thermal barrier coating

  19. Oscillatory shear response of moisture barrier coatings containing clay of different shape factor.

    Science.gov (United States)

    Kugge, C; Vanderhoek, N; Bousfield, D W

    2011-06-01

    Oscillatory shear rheology of barrier coatings based on dispersed styrene-butadiene latex and clay of various shape factors or aspect ratio has been explored. Barrier performance of these coatings when applied to paperboard has been assessed in terms of water vapour transmission rates and the results related to shape factor, dewatering and critical strain. It has been shown that a system based on clay with high shape factor gives a lower critical strain, dewatering and water vapour transmission rate compared with clays of lower shape factor. The dissipated energy, as calculated from an amplitude sweep, indicated no attractive interaction between clay and latex implying a critical strain that appears to be solely dependent on the shape factor at a constant volume fraction. Particle size distribution was shown to have no effect on the critical strain while coatings of high elasticity exhibited high yield strains as expected. The loss modulus demonstrated strain hardening before the elastic to viscous transition. The loss modulus peak was identified by a maximum strain which was significantly lower for a coating based on clay with a high shape factor. The characteristic elastic time was found to vary between 0.6 and 1.3s. The zero shear viscosity of barrier dispersion coatings were estimated from the characteristic elastic time and the characteristic modulus to be of the order of 25-100 Pa s. Copyright © 2011 Elsevier Inc. All rights reserved.

  20. Electrophoretic deposition of double-layer HA/Al composite coating on NiTi.

    Science.gov (United States)

    Karimi, Esmaeil; Khalil-Allafi, Jafar; Khalili, Vida

    2016-01-01

    In order to improve the bioactivity of NiTi alloys, which are being known as the suitable materials for biomedical applications, numerous NiTi disks were electrophoretically coated by hetero-coagulated hydroxyapatite/aluminum composite coatings in three main voltages from suspensions with different Al concentrations. In this paper, the amount of Ni ions release and bioactivity of prepared samples as well as bonding strength of the coating to substrate were investigated. The surface characterization of the coating by XRD, EDX, SEM, and FTIR showed that HA particles bonded by Al particles. It caused the formation of a free crack coating on NiTi disks. Moreover, the bonding strength of HA/Al coatings to NiTi substrate were improved by two times as compared to that of the pure HA coatings. Immersing of coated samples in SBF for 1 week showed that apatite formation ability was improved on HA/Al composite coating and Ni ions release from the surface of composite coating decreased. These results induce the appropriate bioactivity and biocompatibility of the deposited HA/Al composite coatings on NiTi disks. Copyright © 2015 Elsevier B.V. All rights reserved.

  1. Loadings in thermal barrier coatings of jet engine turbine blades an experimental research and numerical modeling

    CERN Document Server

    Sadowski, Tomasz

    2016-01-01

    This book discusses complex loadings of turbine blades and protective layer Thermal Barrier Coating (TBC), under real working airplane jet conditions. They obey both multi-axial mechanical loading and sudden temperature variation during starting and landing of the airplanes. In particular, two types of blades are analyzed: stationary and rotating, which are widely applied in turbine engines produced by airplane factories.

  2. In situ SANS study of pore microstructure in YSZ thermal barrier coatings

    Czech Academy of Sciences Publication Activity Database

    Strunz, Pavel; Schumacher, G.; Vassen, R.; Wiedenmann, A.

    Roč. 52, č. 11 ( 2004 ), s. 3305-3312 ISSN 1359-6454 R&D Projects: GA ČR GA202/03/0891 Institutional research plan: CEZ:AV0Z1048901 Keywords : plasma spraying * thermal barrier coatings * ceramics Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.490, year: 2004

  3. Experimental concrete coating application on the median barrier of I 65 in Louisville.

    Science.gov (United States)

    2008-06-01

    The objectives of this research were to evaluate the experimental protective coating that was applied to approximately 1,200 linear feet of concrete median barrier along the paving project on a section of I 65 between mile points 131.289 and 136.421 ...

  4. Durability of zirconia thermal-barrier ceramic coatings on air-cooled turbine blades in cyclic jet engine operation

    Science.gov (United States)

    Liebert, C. H.; Jacobs, R. E.; Stecura, S.; Morse, C. R.

    1976-01-01

    Thermal barrier ceramic coatings of stabilized zirconia over a bond coat of Ni Cr Al Y were tested for durability on air cooled turbine rotor blades in a research turbojet engine. Zirconia stabilized with either yttria, magnesia, or calcia was investigated. On the basis of durability and processing cost, the yttria stabilized zirconia was considered the best of the three coatings investigated.

  5. High-rate deposition of optical coatings by closed-field magnetron sputtering

    Science.gov (United States)

    Gibson, D. R.; Brinkley, I.; Waddell, E. M.; Walls, J. M.

    2005-09-01

    "Closed field" magnetron (CFM) sputtering offers a flexible and high throughput deposition process for optical coatings and thin films required in a wide range of optical applications. CFM sputtering uses two or more different metal targets to deposit multilayers comprising a wide range of dielectrics, metals and conductive oxides. Moreover, CFM provides a room temperature deposition process with high ion current density, low bias voltage and reactive oxidation in the entire volume around the rotating substrate drum carrier, thereby producing films over a large surface area at high deposition rate with excellent and reproducible optical properties. Machines based on the Closed Field are scaleable to meet a range of batch and in-line size requirements. Typically, thin film thickness control to <+/-1% is accomplished simply using time. Fine layer thickness control and deposition of graded index layers is also assisted with a specially designed rotating shutter mechanism. The CFM configuration also allows plasma treatment of surfaces prior to deposition, allowing optimisation of coating adhesion to substrates such as plastics. This paper presents data on optical, durability and environmental properties for CFM deposited optical coatings, including anti-reflection, IR blocker and colour control and thermal control filters, graded coatings, as well as conductive transparent oxides such as indium tin oxide. Benefits of the CFM sputter process for a range of optical applications are described.

  6. Design and optimization of coating structure for the thermal barrier coatings fabricated by atmospheric plasma spraying via finite element method

    Directory of Open Access Journals (Sweden)

    L. Wang

    2014-06-01

    Full Text Available The first prerequisite for fabricating the thermal barrier coatings (TBCs with excellent performance is to find an optimized coating structure with high thermal insulation effect and low residual stress. This paper discusses the design and optimization of a suitable coating structure for the TBCs prepared by atmospheric plasma spraying (APS using the finite element method. The design and optimization processes comply with the rules step by step, as the structure develops from a simple to a complex one. The research results indicate that the suitable thicknesses of the bond-coating and top-coating are 60–120 μm and 300–420 μm, respectively, for the single ceramic layer YSZ/NiCoCrAlY APS-TBC. The embedded interlayer (50 wt.%YSZ + 50 wt.%NiCoCrAlY will further reduce the residual stress without sacrificing the thermal insulation effect. The double ceramic layer was further considered which was based on the single ceramic layer TBC. The embedded interlayer and the upper additional ceramic layer will have a best match between the low residual stress and high thermal insulation effect. Finally, the optimized coating structure was obtained, i.e., the La2Ce2O7(LC/YSZ/Interlayer/NiCoCrAlY coating structure with appropriate layer thickness is the best choice. The effective thermal conductivity of this optimized LC/YSZ/IL/BL TBC is 13.2% lower than that of the typical single ceramic layer YSZ/BL TBC.

  7. Kinetic Monte Carlo Simulations of Diffusion in Environmental Barrier Coating Materials

    Science.gov (United States)

    Good, Brian

    2017-01-01

    Ceramic Matrix Components (CMC) components for use in turbine engines offer a number of advantages compared with current practice. However, such components are subject to degradation through a variety of mechanisms. In particular, in the hot environment inside a turbine in operation a considerable amount of water vapor is present, and this can lead to corrosion and recession. Environmental Barrier Coating (EBC) systems that limit the amount of oxygen and water reaching the component are required to reduce this degradation and extend component life. A number of silicate-based materials are under consideration for use in such coating systems, including Yttterbium and Yttrium di- and monosilicates. In this work, we present results of kinetic Monte Carlo computer simulations of oxygen diffusion in Yttrium disilicate, and compare with previous work on Yttterbium disilicate. Coatings may also exhibit cracking, and the cracks can provide a direct path for oxygen to reach the component. There is typically a bond coat between the coating and component surface, but the bond coat material is generally chosen for properties other than low oxygen diffusivity. Nevertheless, the degree to which the bond coat can inhibit oxygen diffusion is of interest, as it may form the final defense against oxygen impingement on the component. We have therefore performed similar simulations of oxygen diffusion through HfSiO4, a proposed bond coat material.

  8. SiO2 coating of silver nanoparticles by photoinduced chemical vapor deposition.

    Science.gov (United States)

    Boies, Adam M; Roberts, Jeffrey T; Girshick, Steven L; Zhang, Bin; Nakamura, Toshitaka; Mochizuki, Amane

    2009-07-22

    Gas-phase silver nanoparticles were coated with silicon dioxide (SiO2) by photoinduced chemical vapor deposition (photo-CVD). Silver nanoparticles, produced by inert gas condensation, and a SiO2 precursor, tetraethylorthosilicate (TEOS), were exposed to vacuum ultraviolet (VUV) radiation at atmospheric pressure and varying temperatures. The VUV photons dissociate the TEOS precursor, initiating a chemical reaction that forms SiO2 coatings on the particle surfaces. Coating thicknesses were measured for a variety of operation parameters using tandem differential mobility analysis and transmission electron microscopy. The chemical composition of the particle coatings was analyzed using energy dispersive x-ray spectrometry and Fourier transform infrared spectroscopy. The highest purity films were produced at 300-400 degrees C with low flow rates of additional oxygen. The photo-CVD coating technique was shown to effectively coat nanoparticles and limit core particle agglomeration at concentrations up to 10(7) particles cm(-3).

  9. Electrophoretic deposition of graphene oxide reinforced chitosan-hydroxyapatite nanocomposite coatings on Ti substrate.

    Science.gov (United States)

    Shi, Y Y; Li, M; Liu, Q; Jia, Z J; Xu, X C; Cheng, Y; Zheng, Y F

    2016-03-01

    Electrophoretic deposition (EPD) is a facile and feasible technique to prepare functional nanocomposite coatings for application in orthopedic-related implants. In this work, a ternary graphene oxide-chitosan-hydroxyapatite (GO-CS-HA) composite coating on Ti substrate was successfully fabricated by EPD. Coating microstructure and morphologies were investigated by scanning electron microscopy, contact angle test, Raman spectroscopy, Fourier transform infrared spectroscopy and thermogravimetric analysis. It was found GO-CS surface were uniformly decorated by HA nanoparticles. The potentiodynamic polarization test in simulated body fluid indicated that the GO-CS-HA coatings could provide effective protection of Ti substrate from corrosion. This ternary composite coating also exhibited good biocompatibility during incubation with MG63 cells. In addition, the nanocomposite coatings could decrease the attachment of Staphylococcus aureus.

  10. SiO2 coating of silver nanoparticles by photoinduced chemical vapor deposition

    International Nuclear Information System (INIS)

    Boies, Adam M; Girshick, Steven L; Roberts, Jeffrey T; Zhang Bin; Nakamura, Toshitaka; Mochizuki, Amane

    2009-01-01

    Gas-phase silver nanoparticles were coated with silicon dioxide (SiO 2 ) by photoinduced chemical vapor deposition (photo-CVD). Silver nanoparticles, produced by inert gas condensation, and a SiO 2 precursor, tetraethylorthosilicate (TEOS), were exposed to vacuum ultraviolet (VUV) radiation at atmospheric pressure and varying temperatures. The VUV photons dissociate the TEOS precursor, initiating a chemical reaction that forms SiO 2 coatings on the particle surfaces. Coating thicknesses were measured for a variety of operation parameters using tandem differential mobility analysis and transmission electron microscopy. The chemical composition of the particle coatings was analyzed using energy dispersive x-ray spectrometry and Fourier transform infrared spectroscopy. The highest purity films were produced at 300-400 0 C with low flow rates of additional oxygen. The photo-CVD coating technique was shown to effectively coat nanoparticles and limit core particle agglomeration at concentrations up to 10 7 particles cm -3 .

  11. Anodized porous titanium coated with Ni-CeO{sub 2} deposits for enhancing surface toughness and wear resistance

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Xiaowei, E-mail: zhouxiaowei901@163.com; Ouyang, Chun

    2017-05-31

    Highlights: • Structural design of anodized nanoporous Ti was introduced for bonding pinholes to achieve a metallurgical bonding interface. • Anodized porous Ti substrate was activated by electroless Ni-P film to be acted as transitional layer to deposit Ni-CeO{sub 2} nanocomposite coatings. • An analytical model was validated for predicting the Ce-rich worn products as a self-lubricant phase for monitoring wear mechanisms. - Abstract: In order to make large improvements of surface toughness and wear resistance for pure titanium (Ti) substrate, anodic titanium oxide (ATO) surface with nanoporous structure was coated with the Ni-CeO{sub 2} nanocomposite coatings. Regarding TiO{sub 2} barrier layer on Ti surface to inhibit its electrochemical activity, pre-treatments were successively processed with anodizing, sensitizing, activating, and then followed by electroless Ni-P film to be acted as an activated layer for electroplating Ni-CeO{sub 2} deposits. The existing Pd atoms around ATO nanopores were expected as the heterogeneous nucleation sites for supporting the growing locations of electroless Ni-P film. The innovative of interface design using porous structure was introduced for bonding pinholes to achieve a metallurgical adhesion interface between Ti substrate and surface coatings. Besides the objectives of this work were to elucidate how effects by the adding CeO{sub 2} nanoparticles on modifying microstructures and wear mechanisms of Ni-CeO{sub 2} nanocomposite coatings. Many efforts of XRD, FE-SEM, TEM and Nanoindentation tests were devoted to comparing different wear behaviors of Ni-CeO{sub 2} coatings relative to pure nickel. Results indicated that uniform-distributed Ti nanopores with an average diameter size of ∼200 nm was achieved using the Phosphate-type anodizing solution at DC 150 V. A worn surface without fatigue cracks was observed for TAO surface coated with Ni-CeO{sub 2} deposits, showing the existing Ce-rich worn products to be acted as a

  12. Review of hot corrosion of thermal barrier coatings of gas turbine

    Directory of Open Access Journals (Sweden)

    LIU Yongbao

    2017-03-01

    Full Text Available The review was done in order to make clear the problem of the hot corrosion of the Thermal Barrier Coatings(TBCsduring gas turbine serving. This paper summarizes the factors resulting from the hot corrosion of TBCs during turbine service and classifies methods for enhancing the corrosive resistance of TBCs. A prospective methodology for improving corrosion resistance is also formulated. The main types of corrosion coating include phase reaction, oxidizing of the bond coating, salt-fog corrosion, CMAS corrosion and fuel impurity corrosion. So far, methods for improving the corrosion resistance of TBCs include developing new coating materials, anticorrosive treatment on the surface of TBCs, modifying the stacking configuration and improving the cleansing functions of the gas turbines. In the future, developing new materials with excellent performance will still be the main direction for boosting the improvement of the hot corrosion resistance of TBCs. Simultaneously, improving the tacking configuration and nanotechnology of TBC coatings are potential approaches for improving corrosion resistance. With the development of a Ceramic Matrix Composite (CMC, the focus of the hot corrosion of TBCs may turn to that of Environmental Barrier Coatings (EBCs.

  13. Radio frequency magnetron sputtering deposition of calcium phosphate coatings: Monte Carlo simulations of the deposition process and depositions through an aperture

    Science.gov (United States)

    Feddes, B.; Wolke, J. G. C.; Jansen, J. A.; Vredenberg, A. M.

    2003-01-01

    Radio frequency magnetron sputtering deposited calcium phosphate (CaP) coatings can be applied to improve the biological performance of medical implants. However, the deposition process is rather complex. Particle ejection from the sputtering target, particle collisions with the background gas, charge state of the sputtered particles, and resputtering of the deposited film all influence the composition and structure of the film. In this work we study the deposition process of the coatings by performing depositions through an aperture. Thus an image of the sputtering target is obtained. In order to interpret these images, the deposition process is simulated using a Monte Carlo computer simulation. We found that the experimental images obtained at different gas pressures are well predicted by the simulations. The calcium and phosphorus are proven to be ejected as neutrals from the target. The particle ejection distribution could not unambiguously be derived. This was partially because the image is distorted due to resputtering of the deposited film. The resputtering is the result of bombardment by energetic argon from the plasma, or energetic negative oxygen from the target. Phosphorus is preferentially resputtered from the film. In conclusion, we found that depositions with an aperture in combination with Monte Carlo simulations are a powerful combination to study and better understand the deposition process.

  14. Thin Bioactive Zn Substituted Hydroxyapatite Coating Deposited on Ultrafine-Grained Titanium Substrate: Structure Analysis

    Directory of Open Access Journals (Sweden)

    Konstantin A. Prosolov

    2018-02-01

    Full Text Available Nanocrystalline Zn-substituted hydroxyapatite coatings were deposited by radiofrequency magnetron sputtering on the surface of ultrafine-grained titanium substrates. Cross-section transmission electron microscopy provided information about the morphology and texture of the thin film while in-column energy dispersive X-ray analysis confirmed the presence of Zn in the coating. The Zn-substituted hydroxyapatite coating was formed by an equiaxed polycrystalline grain structure. Effect of substrate crystallinity on the structure of deposited coating is discussed. An amorphous TiO2 sublayer of 8-nm thickness was detected in the interface between the polycrystalline coating and the Ti substrate. Its appearance in the amorphous state is attributed to prior to deposition etching of the substrate and subsequent condensation of oxygen-containing species sputtered from the target. This layer contributes to the high coating-to-substrate adhesion. The major P–O vibrational modes of high intensity were detected by Raman spectroscopy. The Zn-substituted hydroxyapatite could be a material of choice when antibacterial osteoconductive coating with a possibility of withstanding mechanical stress during implantation and service is needed.

  15. Electrophoretic deposition of cellulose nanocrystals (CNs) and CNs/alginate nanocomposite coatings and free standing membranes.

    Science.gov (United States)

    Chen, Qiang; de Larraya, Uxua Pérez; Garmendia, Nere; Lasheras-Zubiate, María; Cordero-Arias, Luis; Virtanen, Sannakaisa; Boccaccini, Aldo R

    2014-06-01

    This study presents the electrophoretic deposition (EPD) of cellulose nanocrystals (CNs) and CNs-based alginate composite coatings for biomedical applications. The mechanism of anodic deposition of CNs and co-deposition of CNs/alginate composites was analyzed based on the results of zeta-potential, Fourier transform infrared spectroscopy and scanning electron microscopy (SEM) analyses. The capability of the EPD technique for manipulating the orientation of CNs and for the preparation of multilayer CNs coatings was demonstrated. The nanotopographic surface roughness and hydrophilicity of the deposited coatings were measured and discussed. Electrochemical testing demonstrated that a significant degree of corrosion protection of stainless steel could be achieved when CNs-containing coatings were present. Additionally, the one-step EPD-based processing of free-standing CNs/alginate membranes was demonstrated confirming the versatility of EPD to fabricate free-standing membrane structures compared to a layer-by-layer deposition technique. CNs and CNs/alginate nanocomposite coatings produced by EPD are potential candidates for biomedical, cell technology and drug delivery applications. Copyright © 2014 Elsevier B.V. All rights reserved.

  16. Diamond coating deposition by synergy of thermal and laser methods-A problem revisited

    International Nuclear Information System (INIS)

    Ristic, Gordana S.; Trtica, Milan S.; Bogdanov, Zarko D.; Romcevic, Nebojsa Z.; Miljanic, Scepan S.

    2007-01-01

    Diamond coatings were deposited by synergy of the hot filament CVD method and the pulse TEA CO 2 laser, in spectroactive and spectroinactive diamond precursor atmospheres. Resulting diamond coatings are interpreted relying on evidence of scanning electron microscopy as well as microRaman spectroscopy. Thermal synergy component (hot filament) possesses an activating agent for diamond deposition, and contributes significantly to quality and extent of diamond deposition. Laser synergy component comprises a solid surface modification as well as the spectroactive gaseous atmosphere modification. Surface modification consists in changes of the diamond coating being deposited and, at the same time, in changes of the substrate surface structure. Laser modification of the spectroactive diamond precursor atmosphere means specific consumption of the precursor, which enables to skip the deposition on a defined substrate location. The resulting process of diamond coating elimination from certain, desired locations using the CO 2 laser might contribute to tailoring diamond coatings for particular applications. Additionally, the substrate laser modification could be optimized by choice of a proper spectroactive precursor concentration, or by a laser radiation multiple pass through an absorbing medium

  17. Acid formic effect in zinc coatings obtained by galvanostatic deposition

    International Nuclear Information System (INIS)

    Lopes, C.; David, M.; Souza, E.C.

    2016-01-01

    Zinc deposits obtained from electrodeposition is widely used for the purpose of protecting steel substrates from corrosion. They are generally added to Zn deposition bath many additives for improving certain characteristics of the deposit. As far as is known there is no information in literature about the effect of formic acid in corrosion resistance of a Zn deposit. Because it is an acid additive, it has the use of cyclohexylamine, in order for the electrolytic bath continue with a pH equal to the one used commercially, around 5. The main goal of this study is analyze the effect of the formic acid addition in the corrosion resistance of an Zn electrodeposition obtained by galvanostatic deposition. The results obtained by performance tests, cyclic voltammetry and X-ray diffraction showed that the formic acid addition may be promising in combating the corrosion of materials. (author)

  18. Development and application of a green-chemistry solution deposition technique for buffer layer coating on cube-textured metal substrates in view of further deposition of rare-earth based superconductors

    DEFF Research Database (Denmark)

    Pallewatta, Pallewatta G A P

    which consist of YBCO superconducting coatings on cube-textured Ni based alloy tapes.  Before the epitaxial deposition this superconducting layer, a buffer layer is applied on the metal substrate as a diffusion barrier which is also required to transfer the strong texture of the underlying substrate......, allowing the epitaxial growth of the superconducting layer. State-of-the-art coated conductor hetero structures are mainly based on CeO2 based buffer stacks that consist of a sequence of several different buffer layers. Buffer layers deposited by continuous chemical deposition techniques, which...... are the most suitable for large scale production, use to suffer from porosity and cracks that lead to material diffusion from the metal substrate into the superconductor as well as oxidation of the metal during high-temperature processing of the buffer layer. SrTiO3 buffer layers have attracted interest due...

  19. Atomic-layer-deposited WNxCy thin films as diffusion barrier for copper metallization

    Science.gov (United States)

    Kim, Soo-Hyun; Oh, Su Suk; Kim, Ki-Bum; Kang, Dae-Hwan; Li, Wei-Min; Haukka, Suvi; Tuominen, Marko

    2003-06-01

    The properties of WNxCy films deposited by atomic layer deposition (ALD) using WF6, NH3, and triethyl boron as source gases were characterized as a diffusion barrier for copper metallization. It is noted that the as-deposited film shows an extremely low resistivity of about 350 μΩ cm with a film density of 15.37 g/cm3. The film composition measured from Rutherford backscattering spectrometry shows W, C, and N of ˜48, 32, and 20 at. %, respectively. Transmission electron microscopy analyses show that the as-deposited film is composed of face-centered-cubic phase with a lattice parameter similar to both β-WC1-x and β-W2N with an equiaxed microstructure. The barrier property of this ALD-WNxCy film at a nominal thickness of 12 nm deposited between Cu and Si fails only after annealing at 700 °C for 30 min.

  20. Non-destructive evaluation of degradation in EB-PVD thermal barrier coatings by infrared reflectance spectroscopy

    International Nuclear Information System (INIS)

    Flattum, Richard Y.; Cooney, Adam T.

    2013-01-01

    At room temperature and atmospheric conditions infrared reflectance spectroscopy and X-ray diffraction were employed for the detection of the phase transformation and residual stress within thermal barrier coatings (TBC). The TBC's samples initially consisted of the porous ceramic topcoat deposited by electron beam plasma vapor deposition, a bond coat and a superalloy substrate. Reflectance spectroscopy scans were performed from 7497 cm −1 to 68 cm −1 to analysis the fingerprint region as well as the chemical bonding region. These regions should indicate if a detectable change within the TBC response is a result of thermal degradation of the microstructure and the changes in yttrium dispersion throughout the yttrium stabilized zirconium. The thermal degradation was induced by thermal cycling the samples to 1100° C and then cooling them in an atmospheric environment. X-ray diffraction was also used to detect the phase composition within the TBC samples and see if either would clearly identify failure prior to actual spallation. The eventual measurability and quantify-ability of the phase changes within the TBC's may be used as an effective non-destructive evaluation (NDE) technique that would allow personnel in the field to know when servicing of the turbine blade was necessary.

  1. Tribological and Wear Performance of Nanocomposite PVD Hard Coatings Deposited on Aluminum Die Casting Tool

    Directory of Open Access Journals (Sweden)

    Jose Mario Paiva

    2018-02-01

    Full Text Available In the aluminum die casting process, erosion, corrosion, soldering, and die sticking have a significant influence on tool life and product quality. A number of coatings such as TiN, CrN, and (Cr,AlN deposited by physical vapor deposition (PVD have been employed to act as protective coatings due to their high hardness and chemical stability. In this study, the wear performance of two nanocomposite AlTiN and AlCrN coatings with different structures were evaluated. These coatings were deposited on aluminum die casting mold tool substrates (AISI H13 hot work steel by PVD using pulsed cathodic arc evaporation, equipped with three lateral arc-rotating cathodes (LARC and one central rotating cathode (CERC. The research was performed in two stages: in the first stage, the outlined coatings were characterized regarding their chemical composition, morphology, and structure using glow discharge optical emission spectroscopy (GDOES, scanning electron microscopy (SEM, and X-ray diffraction (XRD, respectively. Surface morphology and mechanical properties were evaluated by atomic force microscopy (AFM and nanoindentation. The coating adhesion was studied using Mersedes test and scratch testing. During the second stage, industrial tests were carried out for coated die casting molds. In parallel, tribological tests were also performed in order to determine if a correlation between laboratory and industrial tests can be drawn. All of the results were compared with a benchmark monolayer AlCrN coating. The data obtained show that the best performance was achieved for the AlCrN/Si3N4 nanocomposite coating that displays an optimum combination of hardness, adhesion, soldering behavior, oxidation resistance, and stress state. These characteristics are essential for improving the die mold service life. Therefore, this coating emerges as a novelty to be used to protect aluminum die casting molds.

  2. Tribological and Wear Performance of Nanocomposite PVD Hard Coatings Deposited on Aluminum Die Casting Tool

    Science.gov (United States)

    Fox-Rabinovich, German; Locks Junior, Edinei; Stolf, Pietro; Matos Martins, Marcelo

    2018-01-01

    In the aluminum die casting process, erosion, corrosion, soldering, and die sticking have a significant influence on tool life and product quality. A number of coatings such as TiN, CrN, and (Cr,Al)N deposited by physical vapor deposition (PVD) have been employed to act as protective coatings due to their high hardness and chemical stability. In this study, the wear performance of two nanocomposite AlTiN and AlCrN coatings with different structures were evaluated. These coatings were deposited on aluminum die casting mold tool substrates (AISI H13 hot work steel) by PVD using pulsed cathodic arc evaporation, equipped with three lateral arc-rotating cathodes (LARC) and one central rotating cathode (CERC). The research was performed in two stages: in the first stage, the outlined coatings were characterized regarding their chemical composition, morphology, and structure using glow discharge optical emission spectroscopy (GDOES), scanning electron microscopy (SEM), and X-ray diffraction (XRD), respectively. Surface morphology and mechanical properties were evaluated by atomic force microscopy (AFM) and nanoindentation. The coating adhesion was studied using Mersedes test and scratch testing. During the second stage, industrial tests were carried out for coated die casting molds. In parallel, tribological tests were also performed in order to determine if a correlation between laboratory and industrial tests can be drawn. All of the results were compared with a benchmark monolayer AlCrN coating. The data obtained show that the best performance was achieved for the AlCrN/Si3N4 nanocomposite coating that displays an optimum combination of hardness, adhesion, soldering behavior, oxidation resistance, and stress state. These characteristics are essential for improving the die mold service life. Therefore, this coating emerges as a novelty to be used to protect aluminum die casting molds. PMID:29495620

  3. Tribological and Wear Performance of Nanocomposite PVD Hard Coatings Deposited on Aluminum Die Casting Tool.

    Science.gov (United States)

    Paiva, Jose Mario; Fox-Rabinovich, German; Locks Junior, Edinei; Stolf, Pietro; Seid Ahmed, Yassmin; Matos Martins, Marcelo; Bork, Carlos; Veldhuis, Stephen

    2018-02-28

    In the aluminum die casting process, erosion, corrosion, soldering, and die sticking have a significant influence on tool life and product quality. A number of coatings such as TiN, CrN, and (Cr,Al)N deposited by physical vapor deposition (PVD) have been employed to act as protective coatings due to their high hardness and chemical stability. In this study, the wear performance of two nanocomposite AlTiN and AlCrN coatings with different structures were evaluated. These coatings were deposited on aluminum die casting mold tool substrates (AISI H13 hot work steel) by PVD using pulsed cathodic arc evaporation, equipped with three lateral arc-rotating cathodes (LARC) and one central rotating cathode (CERC). The research was performed in two stages: in the first stage, the outlined coatings were characterized regarding their chemical composition, morphology, and structure using glow discharge optical emission spectroscopy (GDOES), scanning electron microscopy (SEM), and X-ray diffraction (XRD), respectively. Surface morphology and mechanical properties were evaluated by atomic force microscopy (AFM) and nanoindentation. The coating adhesion was studied using Mersedes test and scratch testing. During the second stage, industrial tests were carried out for coated die casting molds. In parallel, tribological tests were also performed in order to determine if a correlation between laboratory and industrial tests can be drawn. All of the results were compared with a benchmark monolayer AlCrN coating. The data obtained show that the best performance was achieved for the AlCrN/Si₃N₄ nanocomposite coating that displays an optimum combination of hardness, adhesion, soldering behavior, oxidation resistance, and stress state. These characteristics are essential for improving the die mold service life. Therefore, this coating emerges as a novelty to be used to protect aluminum die casting molds.

  4. Electro-chemical deposition of nano hydroxyapatite-zinc coating on titanium metal substrate.

    Science.gov (United States)

    El-Wassefy, N A; Reicha, F M; Aref, N S

    2017-08-13

    Titanium is an inert metal that does not induce osteogenesis and has no antibacterial properties; it is proposed that hydroxyapatite coating can enhance its bioactivity, while zinc can contribute to antibacterial properties and improve osseointegration. A nano-sized hydroxyapatite-zinc coating was deposited on commercially pure titanium using an electro-chemical process, in order to increase its surface roughness and enhance adhesion properties. The hydroxyapatite-zinc coating was attained using an electro-chemical deposition in a solution composed of a naturally derived calcium carbonate, di-ammonium hydrogen phosphate, with a pure zinc metal as the anode and titanium as the cathode. The applied voltage was -2.5 for 2 h at a temperature of 85 °C. The resultant coating was characterized for its surface morphology and chemical composition using a scanning electron microscope (SEM), energy dispersive x-ray spectroscope (EDS), and Fourier transform infrared (FT-IR) spectrometer. The coated specimens were also evaluated for their surface roughness and adhesion quality. Hydroxyapatite-zinc coating had shown rosette-shaped, homogenous structure with nano-size distribution, as confirmed by SEM analysis. FT-IR and EDS proved that coatings are composed of hydroxyapatite (HA) and zinc. The surface roughness assessment revealed that the coating procedure had significantly increased average roughness (Ra) than the control, while the adhesive tape test demonstrated a high-quality adhesive coat with no laceration on tape removal. The developed in vitro electro-chemical method can be employed for the deposition of an even thickness of nano HA-Zn adhered coatings on titanium substrate and increases its surface roughness significantly.

  5. Influence of laser irradiation on deposition characteristics of cold sprayed Stellite-6 coatings

    Science.gov (United States)

    Li, Bo; Jin, Yan; Yao, Jianhua; Li, Zhihong; Zhang, Qunli; Zhang, Xin

    2018-03-01

    Depositing hard materials such as Stellite-6 solely by cold spray (CS) is challengeable due to limited ability of plastic deformation. In this study, the deposition of Stellite-6 powder was achieved by supersonic laser deposition (SLD) which combines CS with synchronous laser irradiation. The surface morphology, deposition efficiency, track shape of Stellite-6 coatings produced over a range of laser irradiation temperatures were examined so as to reveal the effects of varying laser energy inputting on the deposition process of high strength material. The microstructure, phase composition and wear/corrosion resistant properties of the as-deposited Stellite-6 coatings were also investigated. The experimental results demonstrate that the surface flatness and deposition efficiency increase with laser irradiation temperature due to the softening effect induced by laser heating. The as-deposited Stellite-6 tracks show asymmetric shapes which are influenced by the relative configuration of powder stream and laser beam. The SLD coatings can preserve the original microstructure and phase of the feedstock material due to relatively low laser energy inputting, which result in the superior wear/corrosion resistant properties as compared to the counterpart prepared by laser cladding.

  6. Analysis of Thermal Radiation Effects on Temperatures in Turbine Engine Thermal Barrier Coatings

    Science.gov (United States)

    Siegel, Robert; Spuckler, Charles M.

    1998-01-01

    Thermal barrier coatings are important, and in some instances a necessity, for high temperature applications such as combustor liners, and turbine vanes and rotating blades for current and advanced turbine engines. Some of the insulating materials used for coatings, such as zirconia that currently has widespread use, are partially transparent to thermal radiation. A translucent coating permits energy to be transported internally by radiation, thereby increasing the total energy transfer and acting like an increase in thermal conductivity. This degrades the insulating ability of the coating. Because of the strong dependence of radiant emission on temperature, internal radiative transfer effects are increased as temperatures are raised. Hence evaluating the significance of internal radiation is of importance as temperatures are increased to obtain higher efficiencies in advanced engines.

  7. Thermal Conductivity and Elastic Modulus Evolution of Thermal Barrier Coatings under High Heat Flux Conditions

    Science.gov (United States)

    Zhu, Dongming; Miller, Robert A.

    1999-01-01

    Laser high heat flux test approaches have been established to obtain critical properties of ceramic thermal barrier coatings (TBCs) under near-realistic temperature and thermal gradients that may he encountered in advanced engine systems. Thermal conductivity change kinetics of a thin ceramic coating were continuously monitored in real time at various test temperatures. A significant thermal conductivity increase was observed during the laser simulated engine heat flux tests. For a 0.25 mm thick ZrO2-8%Y2O3 coating system, the overall thermal conductivity increased from the initial value of 1.0 W/m-K to 1. 15 W/m-K, 1. 19 W/m-K and 1.5 W/m-K after 30 hour testing at surface temperatures of 990C, 1100C, and 1320C. respectively. Hardness and modulus gradients across a 1.5 mm thick TBC system were also determined as a function of laser testing time using the laser sintering/creep and micro-indentation techniques. The coating Knoop hardness values increased from the initial hardness value of 4 GPa to 5 GPa near the ceramic/bond coat interface, and to 7.5 GPa at the ceramic coating surface after 120 hour testing. The ceramic surface modulus increased from an initial value of about 70 GPa to a final value of 125 GPa. The increase in thermal conductivity and the evolution of significant hardness and modulus gradients in the TBC systems are attributed to sintering-induced micro-porosity gradients under the laser-imposed high thermal gradient conditions. The test techniques provide a viable means for obtaining coating data for use in design, development, stress modeling, and life prediction for various thermal barrier coating applications.

  8. DC switch power supply for vacuum-arc coatings deposition

    International Nuclear Information System (INIS)

    Zalesskij, D.Yu.; Volkov, Yu.Ya.; Vasil'ev, V.V.; Kozhushko, V.V.; Luchaninov, A.A.; Strel'nitskij, V.E.

    2008-01-01

    Special DC Switch Power Supply for vacuum-arc deposition was developed and tested in the mode of depositing Al and AlN films. Maximum output power was 6 kW, maximum output current - 120 A, open-circuit voltage - 150 V. The Power Supply allows to adjust and stabilize output current in a wide range. Testing of the Power Supply revealed an advantages over the standard 'Bulat-6' power supply, especially for deposition of non-conductive AlN films.

  9. Abrasion resistance of alloy coatings deposited by plasma spraying

    Czech Academy of Sciences Publication Activity Database

    Ctibor, Pavel; Lescoffit, A.-E.; Teboul, B.; Neufuss, Karel; Voleník, Karel

    2009-01-01

    Roč. 54, č. 2 (2009), s. 113-126 ISSN 0001-7043 R&D Projects: GA AV ČR 1QS200430560 Institutional research plan: CEZ:AV0Z20430508 Keywords : Plasma spraying * alloy coatings * slurry abrasion * hardness and microhardness Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass

  10. lectrolytic deposition of lithium into calcium phosphate coatings

    NARCIS (Netherlands)

    Wang, J.; de Groot, K.; van Blitterswijk, Clemens; de Boer, Jan

    2009-01-01

    Objectives: Lithium ions stimulate the Wnt signaling pathway and the authors previously demonstrated that lithium enhances the proliferation of tissue cultured human mesenchymal stem cells. The aim of this study was to prepare and characterize a calcium phosphate/lithium coating by means of

  11. Deposition of protective coatings in rf organosilicon discharges

    Czech Academy of Sciences Publication Activity Database

    Zajíčková, L.; Buršíková, V.; Kučerová, Z.; Franta, D.; Dvořák, P.; Šmíd, R.; Peřina, Vratislav; Macková, Anna

    2007-01-01

    Roč. 16, č. 1 (2007), s. 123-132 ISSN 0963-0252 R&D Projects: GA MŠk(CZ) LC06041 Institutional research plan: CEZ:AV0Z10480505 Keywords : organosilicon discharges, hardness and elastic modulus, protectove coating s Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 2.120, year: 2007

  12. Environmental Barrier Coating (EBC) Durability Modeling; An Overview and Preliminary Analysis

    Science.gov (United States)

    Abdul-Aziz, A.; Bhatt, R. T.; Grady, J. E.; Zhu, D.

    2012-01-01

    A study outlining a fracture mechanics based model that is being developed to investigate crack growth and spallation of environmental barrier coating (EBC) under thermal cycling conditions is presented. A description of the current plan and a model to estimate thermal residual stresses in the coating and preliminary fracture mechanics concepts for studying crack growth in the coating are also discussed. A road map for modeling life and durability of the EBC and the results of FEA model(s) developed for predicting thermal residual stresses and the cracking behavior of the coating are generated and described. Further initial assessment and preliminary results showed that developing a comprehensive EBC life prediction model incorporating EBC cracking, degradation and spalling mechanism under stress and temperature gradients typically seen in turbine components is difficult. This is basically due to mismatch in thermal expansion difference between sub-layers of EBC as well as between EBC and substrate, diffusion of moisture and oxygen though the coating, and densification of the coating during operating conditions as well as due to foreign object damage, the EBC can also crack and spall from the substrate causing oxidation and recession and reducing the design life of the EBC coated substrate.

  13. An investigation of enhanced capability thermal barrier coating systems for diesel engine components

    Science.gov (United States)

    Holtzman, R. L.; Layne, J. L.; Schechter, B.

    1984-01-01

    Material systems and processes for the development of effective and durable thermal barriers for heavy duty diesel engines were investigated. Seven coating systems were evaluated for thermal conductivity, erosion resistance, corrosion/oxidation resistance, and thermal shock resistance. An advanced coating system based on plasma sprayed particle yttria stabilized zirconia (PS/HYSZ) was judged superior in these tests. The measured thermal conductivity of the selected coating was 0.893 W/m C at 371 C. The PS/HYSZ coating system was applied to the piston crown, fire deck and valves of a single cylinder low heat rejection diesel engine. The coated engine components were tested for 24 hr at power levels from 0.83 MPa to 1.17 MPa brake mean effective pressure. The component coatings survived the engine tests with a minimum of distress. The measured fire deck temperatures decreased 86 C (155 F) on the intake side and 42 C (75 F) on the exhaust side with the coating applied.

  14. Mechanisms of oxygen permeation through plastic films and barrier coatings

    Science.gov (United States)

    Wilski, Stefan; Wipperfürth, Jens; Jaritz, Montgomery; Kirchheim, Dennis; Mitschker, Felix; Awakowicz, Peter; Dahlmann, Rainer; Hopmann, Christian

    2017-10-01

    Oxygen and water vapour permeation through plastic films in food packaging or other applications with high demands on permeation are prevented by inorganic barrier films. Most of the permeation occurs through small defects (PET) are investigated and the mass transport through the polymer is simulated in a 3D approach. Calculations of single defects showed that there is no linear correlation between the defect area and the resulting permeability. The influence of adjacent defects in different distances was observed and led to flow reduction functions depending on the defect spacing and defect area. A critical defect spacing where no interaction between defects occurs was found and compared to other findings. According to the superposition principle, the permeability of single defects was added up and compared to experimentally determined oxygen permeation. The results showed the same trend of decreasing permeability with decreasing defect densities.

  15. Characterization of Tungsten Carbide coatings deposited on AISI 1020 steel

    International Nuclear Information System (INIS)

    Santos, A; Gonzalez, C; Ramirez, Z Y

    2017-01-01

    In order to determine the variation in the mechanical properties of AISI 1020 standardized steel, heat treated by a quenching and tempering process and with a Tungsten Carbide coating, was performed a microstructural and chemical characterization of the coating material through electron microscopy scanning and X-ray energy dispersive spectroscopy. The steel received a heat treatment of quenching performed by heating to 850°C, followed by cooling in water and tempering at a temperature of 450°C with air cooling. Tests of a) microhardness with a Wilson-Wolpert Tukon 2100B micro durometer and b) resistance to adhesive and abrasive wear following the ASTM G99-05 “Standard test method for wear testing with a pin-on-disk machine” and ASTM G65-04 “standard test method for measuring abrasion using dry sand and rubber Wheel” standards respectively. The results show that the microhardness of the steel do not vary with the load used to perform the test; in addition, the heat treatment of quenching and tempering improves by 5.5% the property while the coating increase it by 124.2%. Regarding the abrasive wear resistance, it is observed that the amount of material lost increases linearly with the distance covered. It was determined that the heat treatment decreased on average by 17.5% the volume of released material during the tests while the coating recued it by 66.7%. The amount volume of material lost during the adhesive wear tests increases linearly with the distance covered while the heat treatment decreased on average by 10.5% the volume of released material during the trial and the coating reduced it by 66.5%. (paper)

  16. Effect of thermal aging on the erosion resistance of air plasma sprayed zirconia thermal barrier coating

    International Nuclear Information System (INIS)

    Janos, B.Z.; Lugscheider, E.; Remer, P.

    1999-01-01

    To increase the performance, efficiency and reliability of thermal barrier coatings, it is important to understand the influence of the microstructure on the erosion resistance. Therefore, the erosion behavior of air-plasma-sprayed 7 wt% yttria stabilized zirconia (7YSZ) thermal barrier coatings (TBC) at elevated temperatures was investigated. The paper focuses on both the porosity of the coating as well as the thermal pre-treatment of the ceramic. To simulate operating conditions on the ceramic samples, high-temperature erosion experiments at 1093 C were carried out on as-sprayed samples as well as on samples, thermally aged at different temperatures up to 1482 C in air prior to erosion testing. A significant dependence of erosion rate on porosity and thermal pre-treatment was found. Finally, a technique was developed to predict the erosion rates of air-plasma-sprayed 7YSZ TBCs independent of aging conditions or porosity levels. Erosion rates seem to be highly correlated to the micro-hardness of the zirconia TBC. A power-law model was empirically derived to estimate erosion rates of plasma-sprayed 7YSZ ceramic thermal barrier coatings. (orig.)

  17. Anodisation of sputter deposited aluminium–titanium coatings: Effect of microstructure on optical characteristics

    DEFF Research Database (Denmark)

    Aggerbeck, Martin; Junker-Holst, Andreas; Vestergaard Nielsen, Daniel

    2014-01-01

    Magnetron sputtered coatings of aluminium containing up to 18 wt.% titanium were deposited on aluminium substrates to study the effect of microstructure on the optical appearance of the anodised layer. The microstructure and morphology were studied using transmission electron microscopy (TEM), X......-ray diffraction (XRD), and glow discharge optical emission spectroscopy (GDOES), while the optical appearance was investigated using photospectrometry. The microstructure of the coatings was varied by heat treatment, resulting in the precipitation of Al3Ti phases. The reflectance of the anodised surfaces...... decreasedwith titaniumcontent in the as-deposited, and heat-treated states, and after anodisation of the as-deposited coatings. Specimens turned grey or blackwhen anodising after heat treatment. Partially anodised Al3Ti phaseswere found in the anodised layer, and the interface between substrate and anodised...

  18. Design of a Nickel-Based Bond-Coat Alloy for Thermal Barrier Coatings on Copper Substrates

    Directory of Open Access Journals (Sweden)

    Torben Fiedler

    2014-11-01

    Full Text Available To increase the lifetime of rocket combustion chambers, thermal barrier coatings (TBC may be applied on the copper chamber wall. Since standard TBC systems used in gas turbines are not suitable for rocket-engine application and fail at the interface between the substrate and bond coat, a new bond-coat material has to be designed. This bond-coat material has to be chemically compatible to the copper substrate to improve the adhesion and needs a coefficient of thermal expansion close to that of copper to reduce thermal stresses. One approach to achieve this is to modify the standard NiCrAlY alloy used in gas turbines by adding copper. In this work, the influence of copper on the microstructure of NiCrAlY-alloys is investigated with thermodynamical calculations, optical microscopy, SEM, EDX and calorimetry. Adding copper leads to the formation of a significant amount of \\(\\beta\\ and \\(\\alpha\\ Reducing the aluminum and chromium content leads furthermore to a two-phase fcc microstructure.

  19. Small grain size zirconium-based coatings deposited by magnetron sputtering at low temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Jimenez, O., E-mail: omar.jimenez.udg@gmail.com [Departamento de Ingeniería de Proyectos, CUCEI, Universidad de Guadalajara, AP 307, CP 45101 Zapopan, Jal (Mexico); Department of Materials Science and Engineering, The University of Sheffield, Sheffield S1 3JD (United Kingdom); Audronis, M.; Leyland, A. [Department of Materials Science and Engineering, The University of Sheffield, Sheffield S1 3JD (United Kingdom); Flores, M.; Rodriguez, E. [Departamento de Ingeniería de Proyectos, CUCEI, Universidad de Guadalajara, AP 307, CP 45101 Zapopan, Jal (Mexico); Kanakis, K.; Matthews, A. [Department of Materials Science and Engineering, The University of Sheffield, Sheffield S1 3JD (United Kingdom)

    2015-09-30

    Hard, partly amorphous, ZrTiB(N) coatings were deposited by Physical Vapour Deposition (PVD) onto (111) silicon wafers at low substrate temperatures of 85 and 110 °C using Closed Field Unbalanced Magnetron Sputtering. A segmented rectangular sputter target composed of three pieces (Zr/TiB{sub 2}/Zr) was used as the source of evaporation of coating components. Two different substrate biases (i.e. floating potential and − 50 V) and N{sub 2} reactive-gas flow rates of 2, 4 and 6 sccm were employed as the main deposition parameter variables. The chemical composition, structure, morphology and mechanical properties were investigated using a variety of analytical techniques such as Glow-Discharge Optical Emission Spectroscopy, cross-sectional Scanning Electron Microscopy (SEM), Glancing Angle X-ray Diffraction (GAXRD) and nanoindentation. With other parameters fixed, coating properties were found to be dependent on the substrate negative bias and nitrogen flow rate. Linear scan profiles and SEM imaging revealed that all coatings were smooth, dense and featureless (in fracture cross section) with no apparent columnar morphology or macro-defects. GAXRD structural analysis revealed that mostly metallic phases were formed for coatings containing no nitrogen, whereas a solid solution (Zr,Ti)N single phase nitride was found in most of the reactively deposited coatings — exhibiting a very small grain size due to nitrogen and boron grain refinement effects. Hardness values from as low as 8.6 GPa up to a maximum of 25.9 GPa are related mainly to solid solution strengthening effects. The measured elastic moduli correlated with the trends in hardness behaviour; values in the range of 120–200 GPa were observed depending on the selected deposition parameters. Also, high H/E values (> 0.1) were achieved with several of the coatings.

  20. Small grain size zirconium-based coatings deposited by magnetron sputtering at low temperatures

    International Nuclear Information System (INIS)

    Jimenez, O.; Audronis, M.; Leyland, A.; Flores, M.; Rodriguez, E.; Kanakis, K.; Matthews, A.

    2015-01-01

    Hard, partly amorphous, ZrTiB(N) coatings were deposited by Physical Vapour Deposition (PVD) onto (111) silicon wafers at low substrate temperatures of 85 and 110 °C using Closed Field Unbalanced Magnetron Sputtering. A segmented rectangular sputter target composed of three pieces (Zr/TiB 2 /Zr) was used as the source of evaporation of coating components. Two different substrate biases (i.e. floating potential and − 50 V) and N 2 reactive-gas flow rates of 2, 4 and 6 sccm were employed as the main deposition parameter variables. The chemical composition, structure, morphology and mechanical properties were investigated using a variety of analytical techniques such as Glow-Discharge Optical Emission Spectroscopy, cross-sectional Scanning Electron Microscopy (SEM), Glancing Angle X-ray Diffraction (GAXRD) and nanoindentation. With other parameters fixed, coating properties were found to be dependent on the substrate negative bias and nitrogen flow rate. Linear scan profiles and SEM imaging revealed that all coatings were smooth, dense and featureless (in fracture cross section) with no apparent columnar morphology or macro-defects. GAXRD structural analysis revealed that mostly metallic phases were formed for coatings containing no nitrogen, whereas a solid solution (Zr,Ti)N single phase nitride was found in most of the reactively deposited coatings — exhibiting a very small grain size due to nitrogen and boron grain refinement effects. Hardness values from as low as 8.6 GPa up to a maximum of 25.9 GPa are related mainly to solid solution strengthening effects. The measured elastic moduli correlated with the trends in hardness behaviour; values in the range of 120–200 GPa were observed depending on the selected deposition parameters. Also, high H/E values (> 0.1) were achieved with several of the coatings.

  1. Effect of thermally deposited siloxane-methacrylate coating on bonding to glass fibre posts.

    Science.gov (United States)

    Silva, F P; Faria-E-Silva, A L; Moraes, R R; Ogliari, A O; Reis, G R; Oliveira, A R F; Menezes, M S

    2018-01-01

    To evaluate the alterations promoted by a thermally deposited siloxane-methacrylate coating on the surface of glass fibre posts and their effect on the bond strength of resin-core materials to the posts. Fibre post surfaces were treated with experimental thermally deposited siloxane-methacrylate coatings or clinically available treatments (i.e. hydrogen peroxide and methylene chloride); nontreated posts were used as controls. The contact angles formed between the post surface and the water/adhesive were measured with a tensiometer. Scanning electron microscopy and electron dispersive spectroscopy were used to examine the topographies and chemical changes in the post surfaces following treatment. Surface roughness was evaluated with laser interferometry. Core resin was bonded to the fibre posts, and microtensile bond strength testing was subsequently performed. The data were individually submitted to anova and Tukey's tests (α = 0.05). The water contact angle was reduced significantly (P coating. All treatments significantly increased the adhesive contact angle (P ≤ 0.016) compared to the control as well as the surface roughness (P ≤ 0.006) and the amount of Si on post surfaces. Greater percentages of Si were observed for the thermally deposited coating. The bond strength to the posts was significantly improved by the thermally deposited coating (P treatments did not differ from the control. Treating the surface of glass fibre posts with a thermally deposited siloxane-methacrylate coating improved the bond strength to resin-based materials. The coating could be performed by manufacturers of glass fibre posts in order to reduce the number of clinical steps required for luting posts into root canals. © 2017 International Endodontic Journal. Published by John Wiley & Sons Ltd.

  2. Chemical vapour deposition of optical coatings onto small scale complex optical components

    Science.gov (United States)

    Hitchman, M. L.; Gibson, D. R.; Manookian, W.; Waddell, E. M.

    2005-09-01

    In this paper we describe how optical coatings can be deposited uniformly with a high precision and reproducibility on 3-dimensional substrates, such as spherical lenses, by CVD. We present results that will highlight some specific advantages of CVD over the traditionally used methods of e-beam evaporation and magnetron sputtering and we will show that CVD has tremendous potential for enhancing the quality of optical coatings and for making cost savings.

  3. HARDNESS AND DIMENSIONS OF STEELS WITH HARD COATINGS PRODUCED BY CHEMICAL VAPOUR DEPOSITION AT MEDIUM TEMPERATURES

    OpenAIRE

    Ruppert, W.

    1989-01-01

    Chemical Vapour Deposition (CVD) of hard coatings onto steels requires thorough controlling of dimensions and hardness. Dimensional and hardness problems depend on the metallurgical properties of the base and the heat treatments which are applied to the steel before and at the application of CVD. Some information on the control of the dimensions and the hardness of high-carbon high-chromium tool steels which have to be coated with hard compounds by CVD at high temperatures (HTCVD) was already...

  4. Infrared Radiative Properties of Yttria-Stabilized Zirconia Thermal Barrier Coatings

    Science.gov (United States)

    Eldridge, Jeff I.; Spuckler, Charles M.; Street, Ken W.; Markham, Jim R.; Gray, Hugh R. (Technical Monitor)

    2002-01-01

    The infrared (IR) transmittance and reflectance of translucent thermal barrier coatings (TBCs) have important implications for both the performance of these coatings as radiation barriers and emitters as well as affecting measurements of TBC thermal conductivity, especially as TBCs are being pushed to higher temperatures. In this paper, the infrared spectral directional-hemispherical transmittance and reflectance of plasma-sprayed 8wt% yttria-stabilized zirconia (8YSZ) TBCs are reported. These measurements are compared to those for single crystal YSZ specimens to show the effects of the plasma-sprayed coating microstructure. It is shown that the coatings exhibit negligible absorption at wavelengths up to about 5 micrometers, and that internal scattering rather than surface reflections dominates the hemispherical reflectance. The translucent nature of the 8YSZ TBCs results in the absorptance/emittance and reflectance of TBC-coated substrates depending on the TBC thickness, microstructure, as well as the radiative properties of the underlying substrate. The effects of these properties on TBC measurements and performance are discussed.

  5. Effect of deposition parameters and heat-treatment on the microstructure, mechanical and electrochemical properties of hydroxyapatite/titanium coating deposited on Ti6Al4V by RF-magnetron sputtering

    Science.gov (United States)

    Qi, Jianwei; Chen, Zhangbo; Han, Wenjun; He, Danfeng; Yang, Yiming; Wang, Qingliang

    2017-09-01

    Functionally graded HA/Ti coatings were deposited on silicon and Ti6Al4V substrate by radio-frequency (RF) magnetron sputtering. The effect of RF-power, negative bias and heat-treatment on the microstructure, mechanical and electrochemical properties of the coatings were characterized by SEM, XRD, FTIR, AFM Nanoindentation and electrochemical workstation. The obtained results showed that the as-deposited HA/Ti coatings were characteristic of amorphous structure, which transformed into a crystal structure after heat-treatment, and reformed O-H peak. The content of crystallization was increasing with the increase of negative bias. A dense, homogenous, smooth and featured surface, and columnar cross-section structure was observed in SEM observation. AFM results showed that the surface roughness became higher after heat-treatment, and increased with increasing RF-power. The mechanical test indicated that the coating had a higher nanohardness (9.1 GPa) in the case of  -100 V and 250 W than that of Ti6Al4V substrate, and a critical load as high as 17  ±  3.5 N. The electrochemical test confirmed the HA/Ti coating served as a stable protecting barrier in improving the corrosion resistance, which the corrosion current density was 1.3% of Ti6Al4V, but it was significantly influenced by RF-power and negative bias. The contact angle test demonstrated that all the coatings exhibited favorable hydrophilic properties, and it decreased by 20-25% compared to that untreated samples. Thus all results indicated that magnetron sputtering is a promising way for fabricating a better biocompatible ceramic coating by adjusting deposition parameters and post-deposition heat treatments.

  6. The Development of Environmental Barrier Coatings for SiCSiC Ceramic Matrix Composites: Challenges and Opportunities

    Science.gov (United States)

    Zhu, Dongming

    2014-01-01

    Environmental barrier coatings (EBCs) and SiC/SiC ceramic matrix composites (CMCs) systems will play a crucial role in future turbine engines for hot-section component applications because of their ability to significantly increase engine operating temperatures, reduce engine weight and cooling requirements. The development of prime-reliant environmental barrier coatings is a key to enable the applications of the envisioned CMC components to help achieve next generation engine performance and durability goals. This paper will primarily address the performance requirements and design considerations of environmental barrier coatings for turbine engine applications. The emphasis is placed on current candidate environmental barrier coating systems for SiCSiC CMCs, their performance benefits and design limitations in long-term operation and combustion environments. Major technical barriers in developing advanced environmental barrier coating systems, the coating integrations with next generation CMC turbine components having improved environmental stability, cyclic durability and system performance will be described. The development trends for turbine environmental barrier coating systems by utilizing improved compositions, state-of-the-art processing methods, and simulated environment testing and durability modeling will be discussed.

  7. Calcium-Magnesium-Aluminosilicate (CMAS) Infiltration and Cyclic Degradations of Thermal and Environmental Barrier Coatings in Thermal Gradients

    Science.gov (United States)

    Zhu, Dongming; Harder, Bryan; Smialek, Jim; Miller, Robert A.

    2014-01-01

    In a continuing effort to develop higher temperature capable turbine thermal barrier and environmental barrier coating systems, Calcium-Magnesium-Aluminosilicate (CMAS) resistance of the advanced coating systems needs to be evaluated and improved. This paper highlights some of NASA past high heat flux testing approaches for turbine thermal and environmental barrier coatings assessments in CMAS environments. One of our current emphases has been focused on the thermal barrier - environmental barrier coating composition and testing developments. The effort has included the CMAS infiltrations in high temperature and high heat flux turbine engine like conditions using advanced laser high heat flux rigs, and subsequently degradation studies in laser heat flux thermal gradient cyclic and isothermal furnace cyclic testing conditions. These heat flux CMAS infiltration and related coating durability testing are essential where appropriate CMAS melting, infiltration and coating-substrate temperature exposure temperature controls can be achieved, thus helping quantify the CMAS-coating interaction and degradation mechanisms. The CMAS work is also playing a critical role in advanced coating developments, by developing laboratory coating durability assessment methodologies in simulated turbine engine conditions and helping establish CMAS test standards in laboratory environments.

  8. Phase Stability and Thermal Conductivity of Composite Environmental Barrier Coatings on SiC/SiC Ceramic Matrix Composites

    Science.gov (United States)

    Benkel, Samantha; Zhu, Dongming

    2011-01-01

    Advanced environmental barrier coatings are being developed to protect SiC/SiC ceramic matrix composites in harsh combustion environments. The current coating development emphasis has been placed on the significantly improved cyclic durability and combustion environment stability in high-heat-flux and high velocity gas turbine engine environments. Environmental barrier coating systems based on hafnia (HfO2) and ytterbium silicate, HfO2-Si nano-composite bond coat systems have been processed and their stability and thermal conductivity behavior have been evaluated in simulated turbine environments. The incorporation of Silicon Carbide Nanotubes (SiCNT) into high stability (HfO2) and/or HfO2-silicon composite bond coats, along with ZrO2, HfO2 and rare earth silicate composite top coat systems, showed promise as excellent environmental barriers to protect the SiC/SiC ceramic matrix composites.

  9. Creep Behavior of Hafnia and Ytterbium Silicate Environmental Barrier Coating Systems on SiC/SiC Ceramic Matrix Composites

    Science.gov (United States)

    Zhu, Dongming; Fox, Dennis S.; Ghosn, Louis J.; Harder, Bryan

    2011-01-01

    Environmental barrier coatings will play a crucial role in future advanced gas turbine engines because of their ability to significantly extend the temperature capability and stability of SiC/SiC ceramic matrix composite (CMC) engine components, thus improving the engine performance. In order to develop high performance, robust coating systems for engine components, appropriate test approaches simulating operating temperature gradient and stress environments for evaluating the critical coating properties must be established. In this paper, thermal gradient mechanical testing approaches for evaluating creep and fatigue behavior of environmental barrier coated SiC/SiC CMC systems will be described. The creep and fatigue behavior of Hafnia and ytterbium silicate environmental barrier coatings on SiC/SiC CMC systems will be reported in simulated environmental exposure conditions. The coating failure mechanisms will also be discussed under the heat flux and stress conditions.

  10. Electrophoretic deposition of organic/inorganic composite coatings containing ZnO nanoparticles exhibiting antibacterial properties.

    Science.gov (United States)

    Karbowniczek, Joanna; Cordero-Arias, Luis; Virtanen, Sannakaisa; Misra, Superb K; Valsami-Jones, Eugenia; Tuchscherr, Lorena; Rutkowski, Bogdan; Górecki, Kamil; Bała, Piotr; Czyrska-Filemonowicz, Aleksandra; Boccaccini, Aldo R

    2017-08-01

    To address one of the serious problems associated with permanent implants, namely bacterial infections, novel organic/inorganic coatings containing zinc oxide nanoparticles (nZnO) are proposed. Coatings were obtained by electrophoretic deposition (EPD) on stainless steel 316L. Different deposition conditions namely: deposition times in the range 60-300s and applied voltage in the range 5-30V as well as developing a layered coating approach were studied. Antibacterial tests against gram-positive Staphylococcus aureus and gram-negative Salmonella enteric bacteria confirmed the activity of nZnO to prevent bacterial growth. Coatings composition and morphology were analyzed by thermogravimetric analysis, Fourier transform infrared spectroscopy, scanning electron microscopy and energy dispersive X-ray spectroscopy. Moreover, the corrosion resistance was analyzed by evaluation of the polarization curves in DMEM at 37°C, and it was found that coatings containing nZnO increased the corrosion resistance compared to the bare substrate. Considering all results, the newly developed coatings represent a suitable alternative for the surface modification of metallic implants. Copyright © 2017 Elsevier B.V. All rights reserved.

  11. ELECTROPHORETICALLY DEPOSITED NANOSIZED HYDROXYAPATITE COATINGS ON 316LVM STAINLESS STEEL FOR ORTHOPAEDIC IMPLANTS

    Directory of Open Access Journals (Sweden)

    MARIJA MIHAILOVIĆ

    2011-03-01

    Full Text Available Hydroxyapatite is a widely used bioceramic material in implant coatings research because of its bioactive behavior when being deposited onto the metallic implant and compatibility with the human bones composition. The coating of nanosized hydroxyapatite was electrophoretically deposited on a blasted surface of stainless steel 316LVM samples at constant voltage, for different deposition times and subsequently sintered in both, vacuum and argon atmosphere, at 1040 and 1000 °C, respectively. Although sintering temperatures needed to achieve highly dense coatings can cause HAp coating phase changes, the possibility to obtain a bioactive coating on 316LVM substrate, without the coatings phase changes due to the nature of the used stoichiometric nanostructured hydroxyapatite is presented in this work. The thermal stability of the used HAp powder was assessed by DTA-TG analyses over the temperature range of 23-1000 C, i.e., at the or nearby experimental sintering temperature. The microstructure characterization was accomplished using SEM, while phase composition was determined using XRD.

  12. ZnS/diamond composite coatings for infrared transmission applications formed by the aerosol deposition method

    Science.gov (United States)

    Johnson, Scooter D.; Kub, Fritz J.; Eddy, Charles R.

    2013-06-01

    The deposition of nano-crystalline ZnS/diamond composite protective coatings on silicon, sapphire, and ZnS substrates, as a preliminary step to coating infrared transparent ZnS substrates from powder mixtures by the aerosol deposition method is presented. Advantages of the aerosol deposition method include the ability to form dense, nanocrystalline lms up to hundreds of microns thick at room temperature and at a high deposition rate on a variety of substrates. Deposition is achieved by creating a pressure gradient that accelerates micrometer- scale particles in an aerosol to high velocity. Upon impact with the target substrate the particles fracture and embed. Continued deposition forms the thick compacted lm. Deposition from an aerosolized mixture of ZnS and diamond powders onto all targets results in linear trend from apparent sputter erosion of the substrate at 100% diamond to formation of a lm with increasing fractions of ZnS. The crossover from abrasion to lm formation on sapphire occurs above about 50% ZnS and a mixture of 90% ZnS and 10% diamond forms a well-adhered lm of about 0.7 μm thickness at a rate of 0.14 μm/min. Resulting lms are characterized by scanning electron microscopy, pro lometry, infrared transmission spectroscopy, and x-ray photoemission spectroscopy. These initial lms mark progress toward the future goal of coating ZnS substrates for abrasion resistance.

  13. Hydroxyapatite-Coated Magnesium-Based Biodegradable Alloy: Cold Spray Deposition and Simulated Body Fluid Studies

    Science.gov (United States)

    Noorakma, Abdullah C. W.; Zuhailawati, Hussain; Aishvarya, V.; Dhindaw, B. K.

    2013-10-01

    A simple modified cold spray process in which the substrate of AZ51 alloys were preheated to 400 °C and sprayed with hydroxyapatite (HAP) using high pressure cold air nozzle spray was designed to get biocompatible coatings of the order of 20-30 μm thickness. The coatings had an average modulus of 9 GPa. The biodegradation behavior of HAP-coated samples was tested by studying with simulated body fluid (SBF). The coating was characterized by FESEM microanalysis. ICPOES analysis was carried out for the SBF solution to know the change in ion concentrations. Control samples showed no aluminum corrosion but heavy Mg corrosion. On the HAP-coated alloy samples, HAP coatings started dissolving after 1 day but showed signs of regeneration after 10 days of holding. All through the testing period while the HAP coating got eroded, the surface of the sample got deposited with different apatite-like compounds and the phase changed with course from DCPD to β-TCP and β-TCMP. The HAP-coated samples clearly improved the biodegradability of Mg alloy, attributed to the dissolution and re-precipitation of apatite showed by the coatings as compared to the control samples.

  14. Performance and Durability of Environmental Barrier Coatings on SiC/SiC Ceramic Matrix Composites

    Science.gov (United States)

    Zhu, Dongming; Harder, Bryan; Bhatt, Ramakrishna

    2016-01-01

    This presentation highlights advanced environmental barrier coating (EBC) and SiC-SiC Ceramic Matrix Composites (CMC) systems for next generation turbine engines. The emphasis will be placed on fundamental coating and CMC property evaluations; and the integrated system performance and degradation mechanisms in simulated laboratory turbine engine testing environments. Long term durability tests in laser rig simulated high heat flux the rmomechanical creep and fatigue loading conditions will also be presented. The results can help improve the future EBC-CMC system designs, validating the advanced EBC-CMC technologies for hot section turbine engine applications.

  15. Thermomechanical and Environmental Durability of Environmental Barrier Coated Ceramic Matrix Composites Under Thermal Gradients

    Science.gov (United States)

    Zhu, Dongming; Bhatt, Ramakrishna T.; Harder, Bryan

    2016-01-01

    This paper presents the developments of thermo-mechanical testing approaches and durability performance of environmental barrier coatings (EBCs) and EBC coated SiCSiC ceramic matrix composites (CMCs). Critical testing aspects of the CMCs will be described, including state of the art instrumentations such as temperature, thermal gradient, and full field strain measurements; materials thermal conductivity evolutions and thermal stress resistance; NDE methods; thermo-mechanical stress and environment interactions associated damage accumulations. Examples are also given for testing ceramic matrix composite sub-elements and small airfoils to help better understand the critical and complex CMC and EBC properties in engine relevant testing environments.

  16. Investigation on the corrosion behavior of physical vapor deposition coated high speed steel

    Directory of Open Access Journals (Sweden)

    R Ravi Raja Malarvannan

    2015-08-01

    Full Text Available This work emphasizes on the influence of the TiN and AlCrN coatings fabricated on high speed steel form tool using physical vapor deposition technique. The surface microstructure of the coatings was studied using scanning electron microscope. Hardness and corrosion studies were also performed using Vickers hardness test and salt spray testing, respectively. The salt spray test results suggested that the bilayer coated (TiN- bottom layer and AlCrN- top layer substrate has undergone less amount of corrosion, and this is attributed to the dense microstructure. In addition to the above, the influence of the above coatings on the machining performance of the high speed steel was also evaluated and compared with that of the uncoated material and the results suggested that the bilayered coating has undergone very low weight loss when compared with that of the uncoated substrate depicting enhanced wear resistance.

  17. Structure of anodized Al–Zr sputter deposited coatings and effect on optical appearance

    DEFF Research Database (Denmark)

    Gudla, Visweswara Chakravarthy; Canulescu, Stela; Shabadi, Rajashekhara

    2014-01-01

    The mechanism of interaction of light with the microstructure of anodized layer giving specific optical appearance is investigated using Al–Zr sputter deposited coating as a model system on an AA6060 substrate. Differences in the oxidative nature of various microstructural components result...... in the evolution of typical features in the anodized layer, which are investigated as a function of microstructure and correlated with its optical appearance. The Zr concentration in the coating was varied from 6 wt.% to 23 wt.%. Heat treatment of the coated samples was carried out at 550°C for 4 h in order...... to evolve Al–Zr based second phase precipitates in the microstructure. Anodizing was performed using 20 wt.% sulphuric acidat 18°C with an intention to study the effect of anodizing on the Al–Zr based precipitates in the coating.Detailed microstructural characterization of the coating and anodized layer...

  18. Characterization and antibacterial performance of bioactive Ti–Zn–O coatings deposited on titanium implants

    International Nuclear Information System (INIS)

    Tsai, Ming-Tzu; Chang, Yin-Yu; Huang, Heng-Li; Hsu, Jui-Ting; Chen, Ya-Chi; Wu, Aaron Yu-Jen

    2013-01-01

    Titanium (Ti)-based materials have been used for dental and orthopedic implants because of their excellent biological compatibility, superior mechanical strength, and high corrosion resistance. The hypothesis of this present study was to manufacture the Zn-doped TiO 2 layer possessing the biocompatibility and antibacterial ability on the surface of Ti specimens. TiO 2 , ZnO, and Ti(Zn)O 2 coatings were deposited on polished pure Ti substrates using a cathodic arc deposition system. Murine osteoblasts (MC3T3-E1) and human Staphylococcus aureus (S. aureus) were cultured onto the surface with different deposited coatings, respectively. The biocompatibility was examined by cell viability and osteogenic gene expression. The antibacterial ability was determined by SYTO9 nucleic acid staining. A porous Zn-doped TiO 2 coating was successfully produced. The ZnO exhibited a fibrous structure with nanorods showing a hydrophobic feature (contact angle approximately 89°). These material properties affected the following biological performance. The antibacterial testing found no apparent difference between the uncoated Ti plate and the TiO 2 coating. However, significantly lower numbers of S. aureus were observed on ZnO and Ti(Zn)O 2 coatings compared to that on the uncoated Ti. The biocompatible testing exhibited that TiO 2 and Ti(Zn)O 2 coatings enhanced greater cell viability and proliferation than the uncoated Ti plate and ZnO coating. The osteogenic gene expression of Dlx-5 and osterix also improved for the TiO 2 and Ti(Zn)O 2 coatings. However, a significant inhibition of cell viability was found for the ZnO coating. These findings suggested that the composite Ti(Zn)O 2 coating with a lower content of Zn (7.6 ± 1.3 at.%) not only improved antibacterial activity, but also maintained the biocompatibility to bone cells. - Highlights: ► TiO 2 , Ti(Zn)O 2 and ZnO coatings were deposited by cathodic arc evaporation. ► Zn may incorporated with Ti to form Zn-doped TiO 2 .

  19. Characterization and antibacterial performance of bioactive Ti–Zn–O coatings deposited on titanium implants

    Energy Technology Data Exchange (ETDEWEB)

    Tsai, Ming-Tzu [Department of Biomedical Engineering, Hungkuang University, Taichung 433, Taiwan (China); Chang, Yin-Yu, E-mail: yinyu@nfu.edu.tw [Department of Mechanical and Computer-Aided Engineering, National Formosa University, Yunlin 632, Taiwan (China); Huang, Heng-Li; Hsu, Jui-Ting [School of Dentistry, College of Medicine China Medical University, Taichung 404, Taiwan (China); Chen, Ya-Chi [Department of Materials Science and Engineering, Mingdao University, Changhua 523, Taiwan (China); Wu, Aaron Yu-Jen [Chang Gung Memorial Hospital, Chang Gung University College of Medicine, Kaohsiung 833, Taiwan (China)

    2013-01-01

    Titanium (Ti)-based materials have been used for dental and orthopedic implants because of their excellent biological compatibility, superior mechanical strength, and high corrosion resistance. The hypothesis of this present study was to manufacture the Zn-doped TiO{sub 2} layer possessing the biocompatibility and antibacterial ability on the surface of Ti specimens. TiO{sub 2}, ZnO, and Ti(Zn)O{sub 2} coatings were deposited on polished pure Ti substrates using a cathodic arc deposition system. Murine osteoblasts (MC3T3-E1) and human Staphylococcus aureus (S. aureus) were cultured onto the surface with different deposited coatings, respectively. The biocompatibility was examined by cell viability and osteogenic gene expression. The antibacterial ability was determined by SYTO9 nucleic acid staining. A porous Zn-doped TiO{sub 2} coating was successfully produced. The ZnO exhibited a fibrous structure with nanorods showing a hydrophobic feature (contact angle approximately 89°). These material properties affected the following biological performance. The antibacterial testing found no apparent difference between the uncoated Ti plate and the TiO{sub 2} coating. However, significantly lower numbers of S. aureus were observed on ZnO and Ti(Zn)O{sub 2} coatings compared to that on the uncoated Ti. The biocompatible testing exhibited that TiO{sub 2} and Ti(Zn)O{sub 2} coatings enhanced greater cell viability and proliferation than the uncoated Ti plate and ZnO coating. The osteogenic gene expression of Dlx-5 and osterix also improved for the TiO{sub 2} and Ti(Zn)O{sub 2} coatings. However, a significant inhibition of cell viability was found for the ZnO coating. These findings suggested that the composite Ti(Zn)O{sub 2} coating with a lower content of Zn (7.6 ± 1.3 at.%) not only improved antibacterial activity, but also maintained the biocompatibility to bone cells. - Highlights: ► TiO{sub 2}, Ti(Zn)O{sub 2} and ZnO coatings were deposited by cathodic arc

  20. Gold coated metal nanostructures grown by glancing angle deposition and pulsed electroplating

    Science.gov (United States)

    Grüner, Christoph; Reeck, Pascal; Jacobs, Paul-Philipp; Liedtke, Susann; Lotnyk, Andriy; Rauschenbach, Bernd

    2018-05-01

    Nickel based nanostructures are grown by glancing angle deposition (GLAD) on flat and pre-patterned substrates. These fabricated porous thin films were subsequently coated by pulsed electroplating with gold. The morphology and conformity of the gold coating were investigated by scanning electron microscopy and X-ray diffraction. Controlled growth of closed gold layers on the nanostructures could be achieved, while the open-pore structure of the nanosculptured thin films was preserved. Such gold coated nanostructures are a candidate for optical sensing and catalysis applications. The demonstrated method can be applied for numerous material combinations, allowing to provide GLAD thin films with new surface properties.

  1. State of residual stress in laser-deposited ceramic composite coatings on aluminum alloys

    OpenAIRE

    Kadolkar, P. B.; Watkins, T. R.; De Hosson, J. Th. M.; Kooi, B. J.; Dahotre, N. B.

    2007-01-01

    The nature and magnitude of the residual stresses within laser-deposited titanium carbide (TiC) coatings on 2024 and 6061 aluminum (Al) alloys were investigated. Macro- and micro-stresses within the coatings were determined using an X-ray diffraction method. Owing to increased debonding between the coating and the substrate, the macro-stresses were found to be compressive and to decrease in magnitude with increasing processing speed. The origin of the macro- and micro-stresses is discussed. T...

  2. Microwave absorption properties of carbon nanocoils coated with highly controlled magnetic materials by atomic layer deposition.

    Science.gov (United States)

    Wang, Guizhen; Gao, Zhe; Tang, Shiwei; Chen, Chaoqiu; Duan, Feifei; Zhao, Shichao; Lin, Shiwei; Feng, Yuhong; Zhou, Lei; Qin, Yong

    2012-12-21

    In this work, atomic layer deposition is applied to coat carbon nanocoils with magnetic Fe(3)O(4) or Ni. The coatings have a uniform and highly controlled thickness. The coated nanocoils with coaxial multilayer nanostructures exhibit remarkably improved microwave absorption properties compared to the pristine carbon nanocoils. The enhanced absorption ability arises from the efficient complementarity between complex permittivity and permeability, chiral morphology, and multilayer structure of the products. This method can be extended to exploit other composite materials benefiting from its convenient control of the impedance matching and combination of dielectric-magnetic multiple loss mechanisms for microwave absorption applications.

  3. Continuous fiber reinforced mesh bond coat for environmental barrier coating system

    Science.gov (United States)

    Zhang, James; Das, Rupak; Roberts III, Herbert Chidsey; Delvaux, John McConnell

    2017-09-26

    A gas turbine blade may have a bond coat applied to its surface. A porous substrate may be applied to the bond layer and one or more protective layers may be applied to the bond layer such that the fiber mesh is embedded between the bond layer and the protective layer to prevent creep.

  4. Defect Clustering and Nano-Phase Structure Characterization of Multi-Component Rare Earth Oxide Doped Zirconia-Yttria Thermal Barrier Coatings

    Science.gov (United States)

    Zhu, Dongming; Chen, Yuan L.; Miller, Robert A.

    2003-01-01

    Advanced oxide thermal barrier coatings have been developed by incorporating multi-component rare earth oxide dopants into zirconia-yttria to effectively promote the creation of the thermodynamically stable, immobile oxide defect clusters and/or nano-scale phases within the coating systems. The presence of these nano-sized defect clusters has found to significantly reduce the coating intrinsic thermal conductivity, improve sintering resistance, and maintain long-term high temperature stability. In this paper, the defect clusters and nano-structured phases, which were created by the addition of multi-component rare earth dopants to the plasma-sprayed and electron-beam physical vapor deposited thermal barrier coatings, were characterized by high-resolution transmission electron microscopy (TEM). The defect cluster size, distribution, crystallographic and compositional information were investigated using high-resolution TEM lattice imaging, selected area diffraction (SAD), electron energy-loss spectroscopy (EELS) and energy dispersive spectroscopy (EDS) analysis techniques. The results showed that substantial defect clusters were formed in the advanced multi-component rare earth oxide doped zirconia- yttria systems. The size of the oxide defect clusters and the cluster dopant segregation was typically ranging from 5 to 50 nm. These multi-component dopant induced defect clusters are an important factor for the coating long-term high temperature stability and excellent performance.

  5. Electrochemical behaviour of silica basic hybrid coatings deposited on stainless steel by dipping and EPD

    International Nuclear Information System (INIS)

    Castro, Y.; Duran, A.; Damborenea, J.J.; Conde, A.

    2008-01-01

    The aim of this work is the characterisation of the corrosion behaviour of stainless steel (AISI 304) substrates coated by dipping and electrophoretic deposition (EPD) from a sol-gel basic sol. Particulate silica sols (labelled NaSi) were prepared by basic catalysis from ethyltriethoxysilane (TEOS), methyltriethoxysilane (MTES) and sodium hydroxide. Coatings between 2 and 10 μm were prepared by using concentrated and diluted sols by dipping and EPD process and the corrosion behaviour of the coated substrates were studied through potentiodynamic and impedance spectroscopy measurements (EIS). Potentiodynamic studies of coatings produced by dipping reveal a strong dependence of the protective properties with the concentration of the sol. This behaviour was confirmed by EIS showing that only the coatings obtained from concentrated sol present enough protective properties. On the contrary, EPD coatings prepared from diluted NaSi sol showed an excellent corrosion resistance, maintaining a pure capacitive behaviour for long periods of immersion. EPD deposition is thus proposed as a good alternative method for obtaining thicker and denser coatings with good protective properties from dilute and stable sols

  6. Ion assisted deposition of refractory oxide thin film coatings for improved optical and structural properties

    International Nuclear Information System (INIS)

    Sahoo, N.K.; Thakur, S.; Bhattacharyya, D.; Das, N.C.

    1999-03-01

    Ion assisted deposition technique (IAD) has emerged as a powerful tool to control the optical and structural properties of thin film coatings. Keeping in view the complexity of the interaction of ions with the films being deposited, sophisticated ion sources have been developed that cater to the need of modern optical coatings with stringent spectral and environmental specifications. In the present work, the results of ion assisted deposition (IAD) of two commonly used refractory oxides, namely TiO 2 and ZrO 2 , using cold cathode ion source (CC-102R) are presented. Through successive feedback and calibration techniques, various ion beams as well as deposition parameters have been optimized to achieve the best optical and structural film properties in the prevalent deposition geometry of the coating system. It has been possible to eliminate the unwanted optical and structural inhomogeneities from these films using and optimized set of process parameters. Interference modulated spectrophotometric and phase modulated ellipsometric techniques have been very successfully utilized to analyze the optical and structural parameters of the films. Several precision multilayer coatings have been developed and are being used for laser and spectroscopic applications. (author)

  7. PREPARING OF THE CHAMELEON COATING BY THE ION JET DEPOSITION METHOD

    Directory of Open Access Journals (Sweden)

    Jakub Skocdopole

    2017-07-01

    Full Text Available Preparation of chameleon coatings using an Ionized Jet Deposition (IJD technique is reported in the present paper. IJD is a new flexible method for thin film deposition developed by Noivion, Srl. The chameleon coatings are thin films characterised by a distinct change of their tribological properties according to the external conditions. The deposited films of SiC and TiN materials were examined by the Raman spectroscopy, SEM and XPS. The results of the Raman spectroscopy have proved an amorphous structure of SiC films. The data from XPS on TiN films have shown that the films are heavily oxidized, but also prove that the films are composed of TiN and pure Ti. The SEM provided information about the size of grains and particles constituting the deposited films, which is important for tribological properties of the films. Deposition of the chameleon coating is very complex problem and IJD could be ideal method for preparation of this coating.

  8. Plasma Spray-Physical Vapor Deposition (PS-PVD) of Ceramics for Protective Coatings

    Science.gov (United States)

    Harder, Bryan J.; Zhu, Dongming

    2011-01-01

    In order to generate advanced multilayer thermal and environmental protection systems, a new deposition process is needed to bridge the gap between conventional plasma spray, which produces relatively thick coatings on the order of 125-250 microns, and conventional vapor phase processes such as electron beam physical vapor deposition (EB-PVD) which are limited by relatively slow deposition rates, high investment costs, and coating material vapor pressure requirements. The use of Plasma Spray - Physical Vapor Deposition (PS-PVD) processing fills this gap and allows thin (PVD coater at NASA Glenn Research Center. A design-of-experiments was used to examine the effects of process variables (Ar/He plasma gas ratio, the total plasma gas flow, and the torch current) on chamber pressure and torch power. Coating thickness, phase and microstructure were evaluated for each set of deposition conditions. Low chamber pressures and high power were shown to increase coating thickness and create columnar-like structures. Likewise, high chamber pressures and low power had lower growth rates, but resulted in flatter, more homogeneous layers

  9. Analysis of sub-bandgap losses in TiO2 coating deposited via single and dual ion beam deposition

    Czech Academy of Sciences Publication Activity Database

    Žídek, Karel; Hlubuček, Jiří; Horodyská, Petra; Budasz, Jiří; Václavík, Jan

    2017-01-01

    Roč. 626, March (2017), s. 60-65 ISSN 0040-6090 R&D Projects: GA MŠk(CZ) LO1206 Institutional support: RVO:61389021 Keywords : Ion beam deposition * Titanium dioxide * Optical coating * Sub-bandgap losses * Urbach tail Subject RIV: BH - Optics, Masers, Lasers OBOR OECD: Optics (including laser optics and quantum optics) Impact factor: 1.879, year: 2016 http://www.sciencedirect.com/science/article/pii/S0040609017301256

  10. A study of the barrier properties of polyethylene coated with a nanocellulose/magnetite composite film

    Directory of Open Access Journals (Sweden)

    Đorđević Nenad

    2016-01-01

    Full Text Available The morphological, thermal and barrier properties of low-density polyethylene/polycaprolactone-modified nanocellulose hybrid materials were investigated in this paper. Nanonocelulose/magnetite (NC-Fe3O4 nanocomposite and maleic acid functionalized NC/magnetite (NCMA-Fe3O4 nanocomposite were prepared and used as filler at various concentrations (5, 10 and 15 wt. % in polycaprolactone (PCL layer. PE was coated with PCL/NC/magnetite layer. The addition of the filler did not unfavorably affect the inherent properties of the polymer, especially its barrier properties. Oxygen permeation measurements show that the oxygen barrier properties of magnetite enriched PCL film were improved due to chemical activity of added material. The highest level of barrier capacity was observed for PE samples coated with PCL based composite with NCMA-Fe3O4 micro/-nanofiller, which implies the significant contribution of nanocellulose surface modification with maleic anhydride residue to improved barrier properties. [Projekat Ministarstva nauke Republike Srbije, br. III45019 i br. OI172013

  11. Annotated bibliography of selected references on shoreline barrier island deposits with emphasis on Patrick Draw Field, Sweetwater County, Wyoming

    Energy Technology Data Exchange (ETDEWEB)

    Rawn-Schatzinger, V.; Schatzinger, R.A.

    1993-07-01

    This bibliography contains 290 annotated references on barrier island and associated depositional environments and reservoirs. It is not an exhaustive compilation of all references on the subject, but rather selected papers on barrier islands, and the depositional processes of formation. Papers that examine the morphology and internal architecture of barrier island deposits, exploration and development technologies are emphasized. Papers were selected that aid in understanding reservoir architecture and engineering technologies to help maximize recovery efficiency from barrier island oil reservoirs. Barrier islands from Wyoming, Montana and the Rocky Mountains basins are extensively covered.

  12. Microstructures, hardness and bioactivity of hydroxyapatite coatings deposited by direct laser melting process

    Energy Technology Data Exchange (ETDEWEB)

    Tlotleng, Monnamme, E-mail: MTlotleng@csir.co.za [Laser Materials Processing Group, National Laser Center CSIR, Pretoria 0001 (South Africa); Department of Mechanical Engineering Science, University of Johannesburg, Auckland Park, Kingsway Campus, Johannesburg 2006 (South Africa); Akinlabi, Esther [Department of Mechanical Engineering Science, University of Johannesburg, Auckland Park, Kingsway Campus, Johannesburg 2006 (South Africa); Shukla, Mukul [Department of Mechanical Engineering Technology, University of Johannesburg, Doornfontein Campus, Johannesburg 2006 (South Africa); Department of Mechanical Engineering, MNNIT, Allahabad, UP 211004 (India); Pityana, Sisa [Laser Materials Processing Group, National Laser Center CSIR, Pretoria 0001 (South Africa); Department of Chemical and Metallurgical Engineering, Tshwane University of Technology, Pretoria 0001 (South Africa)

    2014-10-01

    Hydroxyapatite (HAP) coatings on bioinert metals such as Ti–6Al–4V are necessary for biomedical applications. Together, HAP and Ti–6Al–4V are biocompatible and bioactive. The challenges of depositing HAP on Ti–6Al–4V with traditional thermal spraying techniques are well founded. In this paper, HAP was coated on Ti–6Al–4V using direct laser melting (DLM) process. This process, unlike the traditional coating processes, is able to achieve coatings with good metallurgical bonding and little dilution. The microstructural and mechanical properties, chemical composition and bio-activities of the produced coatings were studied with optical microscopy, scanning electron microscope equipped with energy dispersive X-ray spectroscopy, and Vickers hardness machine, and by immersion test in Hanks' solution. The results showed that the choice of the laser power has much influence on the evolving microstructure, the mechanical properties and the retainment of HAP on the surface of the coating. Also, the choice of laser power of 750 W led to no dilution. The microhardness results inferred a strong intermetallic–ceramic interfacial bonding; which meant that the 750 W coating could survive long in service. Also, the coating was softer at the surface and stronger in the heat affected zones. Hence, this process parameter setting can be considered as an optimal setting. The soak tests revealed that the surface of the coating had unmelted crystals of HAP. The CaP ratio conducted on the soaked coating was 2.00 which corresponded to tetra calcium phosphate. This coating seems attractive for metallic implant applications. - Highlights: • Characteristics of HAP coatings produced on Ti-6Al-4V achieved with direct laser melting are reported. • Optimal process parameters necessary to achieve biocompatible coating are reported. • The SEM micrograph of the soaked HAP coating revealed partially melted crystals of HAP. • The HAP coating was retained at the surface of

  13. Diamond like carbon coatings deposited by microwave plasma CVD ...

    Indian Academy of Sciences (India)

    WINTEC

    Diamond-like carbon (DLC) films were deposited by microwave assisted chemical vapour deposi- tion system using d.c. bias voltage ... Diamond like carbon films; microwave assisted CVD; X-ray photoelectron spectroscopy; spectro- scopic ellipsometry. 1. .... The electrical resistivity of these films was higher than 200 MΩ ...

  14. Life Prediction Issues in Thermal/Environmental Barrier Coatings in Ceramic Matrix Composites

    Science.gov (United States)

    Shah, Ashwin R.; Brewer, David N.; Murthy, Pappu L. N.

    2001-01-01

    Issues and design requirements for the environmental barrier coating (EBC)/thermal barrier coating (TBC) life that are general and those specific to the NASA Ultra-Efficient Engine Technology (UEET) development program have been described. The current state and trend of the research, methods in vogue related to the failure analysis, and long-term behavior and life prediction of EBCITBC systems are reported. Also, the perceived failure mechanisms, variables, and related uncertainties governing the EBCITBC system life are summarized. A combined heat transfer and structural analysis approach based on the oxidation kinetics using the Arrhenius theory is proposed to develop a life prediction model for the EBC/TBC systems. Stochastic process-based reliability approach that includes the physical variables such as gas pressure, temperature, velocity, moisture content, crack density, oxygen content, etc., is suggested. Benefits of the reliability-based approach are also discussed in the report.

  15. Phase of Photothermal Emission Analysis as a Diagnostic Tool for Thermal Barrier Coatings on Serviceable Engine Components

    Science.gov (United States)

    Kakuda, Tyler

    Power generation and aircraft companies are continuously improving the efficiency of gas turbines to meet economic and environmental goals. The trend towards higher efficiency has been achieved in part by raising the operating temperature of engines. At elevated temperatures, engine components are subject to many forms of degradation including oxidation, creep deformation and thermal cycle fatigue. To minimize these harmful effects, ceramic thermal barrier coatings (TBCs) are routinely used to insulate metal components from excessive heat loads. Efforts to make realistic performance assessments of current and candidate coating materials has led to a diverse battery of creative measurement techniques. While it is unrealistic to envision a single measurement that would provide all conceivable information about the TBC, it is arguable that the capability for the single most important measurement is still lacking. A quantitative and nondestructive measurement of the thermal protection offered by a coating is not currently among the measurements one can employ on a serviceable engine part (or even many experimental specimens). In this contribution, phase of photothermal emission analysis (PopTea) is presented as a viable thermal property measurement for serviceable engine components. As it will be shown, PopTea has the versatility to make measurements on gas turbine parts in situ, with the goal of monitoring TBCs over the lifetime of the engine. The main challenges toward this goal are dealing with changes that occur to the TBC during service. Several of the main degradations seen on engine equipment include: aging, surface contamination and infiltration of foreign deposits. Measuring coatings under these conditions, is the impetus of this work. Furthermore, it is demonstrated that PopTea can be used on real engine equipment with measurements made on an actual turbine blade.

  16. The emissivity of W coatings deposited on carbon materials for fusion applications

    Energy Technology Data Exchange (ETDEWEB)

    Ruset, C., E-mail: ruset@infim.ro [National Institute for Laser, Plasma and Radiation Physics, 077125 Bucharest (Romania); Falie, D.; Grigore, E.; Gherendi, M.; Zoita, V. [National Institute for Laser, Plasma and Radiation Physics, 077125 Bucharest (Romania); Zastrow, K.-D.; Matthews, G. [Culham Centre for Fusion Energy (CCFE), Culham Science Centre, Abingdon (United Kingdom); Courtois, X.; Bucalossi, J. [IRFM, CEA Cadarache, F-13108 SAINT PAUL LEZ DURANCE (France); Likonen, J. [VTT Technical Research Centre of Finland, P.O. Box 1000, FI-02044 VTT (Finland)

    2017-01-15

    Highlights: • The emissivity of tungsten coatings deposited on carbon substrates such as CFC and fine grain graphite was measured at the wavelengths of 1.064 μm, 1.75 μm, 3.75 μm and 4.0 μm in the temperature range of 400 °C–1200 °C. • The emissivity of other materials of interest for nuclear fusion such as tungsten and beryllium was measured as well. • The influence of substrate structure and of the viewing angle on the emissivity of W coatings was investigated in detail. - Abstract: Tungsten coatings deposited on carbon materials such as carbon fiber composite (CFC) or fine grain graphite are currently used in fusion devices as amour for plasma facing components (PFC). More than 4000 carbon tiles were W-coated by Combined Magnetron Sputtering and Ion Implantation technology for the ITER-like Wall at JET, ASDEX Upgrade and WEST tokamaks. The emissivity of W coatings is a key parameter required by protection systems of the W-coated PFC and also by the diagnostic tools in order to get correct values of temperature and heat loading. The emissivity of tungsten is rather well known, but the literature data refer to bulk tungsten or tungsten foils and not to coatings deposited on carbon materials. The emissivity was measured at the wavelengths of 1.064 μm, 1.75 μm, 3.75 μm and 4.0 μm. It was found that the structure of the substrate has a significant influence on the emissivity values. The temperature dependence of the emissivity in the range of 400 °C–1200 °C and the influence of the viewing angle were investigated as well. The results are given in a table for W coatings and for other materials of interest for fusion such as bulk W and bulk Be.

  17. Synergistic effect between nano-ceramic lubricating additives and electroless deposited Ni-W-P coating

    Science.gov (United States)

    Chen, Min; Cheng, Wushan; Zhao, Zuxin; Huang, Xiaobo

    2013-01-01

    The major solving ways for the material wear are surface modification and lubrication. Currently, the researches at home and abroad are all limited to the single study of either nano-lubricating oil additive or electroless deposited coating. The surface coating has high hardness and high wear resistance, however, the friction reduction performance of the coating with high hardness is not good, the thickness of the coating is limited, and the coating can not regenerate after wearing. The nano-lubricating additives have good tribological performance and self-repair function, but under heavy load, the self-repair rate to the worn surface with the nano-additives is smaller than the wearing rate of the friction pair. To solve the above problems, the Ni-W-P alloy coating and deposition process with excellent anti-wear, and suitable for industrial application were developed, the optimum bath composition and process can be obtained by studying the influence of the bath composition, temperature and PH value to the deposition rate and the plating solution stability. The tribological properties as well as anti-wear and friction reduction mechanism of wear self-repair nano-ceramic lubricating additives are also studied. The ring-block abrasion testing machine and energy dispersive spectrometer are used to explore the internal relation between the coating and the nano-lubricating oil additives, and the tribology mechanism, to seek the synergetic effect between the two. The test results show that the wear resistance of Ni-W-P alloy coating (with heat treatment and in oil with nano-ceramic additives) has increased hundreds times than 45 steel as the metal substrate in basic oil, the friction reduction performance is improved. This research breaks through the bottleneck of previous separate research of the above-mentioned two methods, and explores the combination use of the two methods in industrial field.

  18. Tungsten coatings electro-deposited on CFC substrates from oxide molten salt

    Science.gov (United States)

    Sun, Ningbo; Zhang, Yingchun; Lang, Shaoting; Jiang, Fan; Wang, Lili

    2014-12-01

    Tungsten is considered as plasma facing material in fusion devices because of its high melting point, its good thermal conductivity, its low erosion rate and its benign neutron activation properties. On the other hand, carbon based materials like C/C fiber composites (CFC) have been used for plasma facing materials (PFMs) due to their high thermal shock resistance, light weight and high strength. Tungsten coatings on CFC substrates are used in the JET divertor in the frame of the JET ITER-like wall project, and have been prepared by plasma spray (PS) and other techniques. In this study, tungsten coatings were electro-deposited on CFC from Na2WO4-WO3 molten salt under various deposition parameters at 900 °C in air. In order to obtain tungsten coatings with excellent performance, the effects of pulse duration ratio and pulse current density on microstructures and crystal structures of tungsten coatings were investigated by X-ray diffraction (XRD, Rigaku Industrial Co., Ltd., D/MAX-RB) and a scanning electron microscope (SEM, JSM 6480LV). It is found that the pulsed duration ratio and pulse current density had a significant influence on tungsten nucleation and electro-crystallization phenomena. SEM observation revealed that intact, uniform and dense tungsten coatings formed on the CFC substrates. Both the average grain size and thickness of the coating increased with the pulsed current density. The XRD results showed that the coatings consisted of a single phase of tungsten with the body centered cubic (BCC) structure. The oxygen content of electro-deposited tungsten coatings was lower than 0.05%, and the micro-hardness was about 400 HV.

  19. The emissivity of W coatings deposited on carbon materials for fusion applications

    International Nuclear Information System (INIS)

    Ruset, C.; Falie, D.; Grigore, E.; Gherendi, M.; Zoita, V.; Zastrow, K.-D.; Matthews, G.; Courtois, X.; Bucalossi, J.; Likonen, J.

    2017-01-01

    Highlights: • The emissivity of tungsten coatings deposited on carbon substrates such as CFC and fine grain graphite was measured at the wavelengths of 1.064 μm, 1.75 μm, 3.75 μm and 4.0 μm in the temperature range of 400 °C–1200 °C. • The emissivity of other materials of interest for nuclear fusion such as tungsten and beryllium was measured as well. • The influence of substrate structure and of the viewing angle on the emissivity of W coatings was investigated in detail. - Abstract: Tungsten coatings deposited on carbon materials such as carbon fiber composite (CFC) or fine grain graphite are currently used in fusion devices as amour for plasma facing components (PFC). More than 4000 carbon tiles were W-coated by Combined Magnetron Sputtering and Ion Implantation technology for the ITER-like Wall at JET, ASDEX Upgrade and WEST tokamaks. The emissivity of W coatings is a key parameter required by protection systems of the W-coated PFC and also by the diagnostic tools in order to get correct values of temperature and heat loading. The emissivity of tungsten is rather well known, but the literature data refer to bulk tungsten or tungsten foils and not to coatings deposited on carbon materials. The emissivity was measured at the wavelengths of 1.064 μm, 1.75 μm, 3.75 μm and 4.0 μm. It was found that the structure of the substrate has a significant influence on the emissivity values. The temperature dependence of the emissivity in the range of 400 °C–1200 °C and the influence of the viewing angle were investigated as well. The results are given in a table for W coatings and for other materials of interest for fusion such as bulk W and bulk Be.

  20. Deposition of multilayer optical coatings using closed-field magnetron sputtering

    Science.gov (United States)

    Gibson, D. R.; Brinkley, I.; Hall, G. W.; Waddell, E. M.; Walls, J. M.

    2006-08-01

    "Closed field" magnetron (CFM) sputtering offers a flexible and high throughput deposition process for optical coatings and thin films required in display technologies. CFM sputtering uses two or more different metal targets to deposit multilayers comprising a wide range of dielectrics, metals and conductive oxides. Moreover, CFM provides a room temperature deposition process with high ion current density, low bias voltage and reactive oxidation in the entire volume around the rotating substrate drum carrier, thereby producing films over a large surface area at high deposition rate with excellent and reproducible optical properties. Machines based on the Closed Field are scaleable to meet a range of batch and in-line size requirements. Typically, thin film thickness control to < +/-1% is accomplished simply using time, although optical monitoring can be used for more demanding applications. Fine layer thickness control and deposition of graded index layers is also assisted with a specially designed rotating shutter mechanism. This paper presents data on optical properties for CFM deposited optical coatings, including anti-reflection, IR blocker and colour control and thermal control filters, graded coatings, narrowband filters as well as conductive transparent oxides such as indium tin oxide. Benefits of the CFM sputter process are described.

  1. Hybrid Plasma-Sprayed Thermal Barrier Coatings Using Powder and Solution Precursor Feedstock

    Science.gov (United States)

    Joshi, S. V.; Sivakumar, G.; Raghuveer, T.; Dusane, R. O.

    2014-04-01

    A novel approach of hybridizing the conventional atmospheric plasma spraying (APS) technique with the solution precursor plasma spray (SPPS) route to achieve thermal barrier coatings (TBCs) with tailored configurations is presented. Such a hybrid process can be conveniently adopted for forming composite, multi-layered and graded coatings employing simultaneous and/or sequential feeding of solution precursor as well as powder feedstock, yielding distinct TBC microstructures that bear promise to further extend coating durability. TBC specimens generated using conventional APS technique, the SPPS method and through APS-SPPS hybrid processing have been comprehensively characterized for microstructure, phase constitution, hardness and thermal cycling life, and the results were compared to demonstrate the advantages that can ensue from hybrid processing.

  2. Environmental/Thermal Barrier Coatings for Ceramic Matrix Composites: Thermal Tradeoff Studies

    Science.gov (United States)

    Murthy, Pappu L. M.; Brewer, David; Shah, Ashwin R.

    2007-01-01

    Recent interest in environmental/thermal barrier coatings (EBC/TBCs) has prompted research to develop life-prediction methodologies for the coating systems of advanced high-temperature ceramic matrix composites (CMCs). Heat-transfer analysis of EBC/TBCs for CMCs is an essential part of the effort. It helps establish the resulting thermal profile through the thickness of the CMC that is protected by the EBC/TBC system. This report documents the results of a one-dimensional analysis of an advanced high-temperature CMC system protected with an EBC/TBC system. The one-dimensional analysis was used for tradeoff studies involving parametric variation of the conductivity; the thickness of the EBC/TBCs, bond coat, and CMC substrate; and the cooling requirements. The insight gained from the results will be used to configure a viable EBC/TBC system for CMC liners that meet the desired hot surface, cold surface, and substrate temperature requirements.

  3. Electrophoretic deposition of chitosan/45S5 bioactive glass composite coatings doped with Zn and Sr

    Directory of Open Access Journals (Sweden)

    Marta eMiola

    2015-10-01

    Full Text Available In this research work the original 45S5 bioactive glass (BG was modified by introducing zinc and/or strontium oxide (6% mol in place of calcium oxide. Sr was added for its ability to stimulate bone formation, Zn for its role in bone metabolism, antibacterial properties and anti-inflammatory effect. The glasses were produced by means of melting and quenching process. SEM and XRD analyses evidenced that Zr and Sr introduction did not modify the glass structure and morphology, while compositional analysis (EDS demonstrated the effective addition of these elements inside the glass network. Bioactivity test in simulated body fluid (SBF up to one month evidenced a reduced bioactivity kinetics for Zn-doped glasses. Doped glasses were combined with chitosan to produce organic/inorganic composite coatings on stainless steel AISI 316L by electrophoretic deposition (EPD. Two EPD processes were considered for coating development, namely direct current EPD (DC-EPD and alternating current EPD (AC-EPD. The stability of the suspension was analysed and the deposition parameters were optimized. Tape and bending tests demonstrated a good coating-substrate adhesion for coatings containing 45S5-Sr and 45S5-ZnSr glasses, while the adhesion to the substrate decreased by using 45S5-Zn glass. FTIR analyses demonstrated the composite nature of coatings and SEM observations indicated that glass particles were well integrated in the polymeric matrix, the coatings were fairly homogeneous and free of cracks; moreover the AC-EPD technique provided better results than DC-EPD in terms of coating quality. SEM, XRD analyses and Raman spectroscopy, performed after bioactivity test in SBF solution, confirmed the bioactive behaviour of 45S5-Sr containing coating, while coatings containing Zn exhibited no hydroxyapatite formation.

  4. Method and Process Development of Advanced Atmospheric Plasma Spraying for Thermal Barrier Coatings

    Science.gov (United States)

    Mihm, Sebastian; Duda, Thomas; Gruner, Heiko; Thomas, Georg; Dzur, Birger

    2012-06-01

    Over the last few years, global economic growth has triggered a dramatic increase in the demand for resources, resulting in steady rise in prices for energy and raw materials. In the gas turbine manufacturing sector, process optimizations of cost-intensive production steps involve a heightened potential of savings and form the basis for securing future competitive advantages in the market. In this context, the atmospheric plasma spraying (APS) process for thermal barrier coatings (TBC) has been optimized. A constraint for the optimization of the APS coating process is the use of the existing coating equipment. Furthermore, the current coating quality and characteristics must not change so as to avoid new qualification and testing. Using experience in APS and empirically gained data, the process optimization plan included the variation of e.g. the plasma gas composition and flow-rate, the electrical power, the arrangement and angle of the powder injectors in relation to the plasma jet, the grain size distribution of the spray powder and the plasma torch movement procedures such as spray distance, offset and iteration. In particular, plasma properties (enthalpy, velocity and temperature), powder injection conditions (injection point, injection speed, grain size and distribution) and the coating lamination (coating pattern and spraying distance) are examined. The optimized process and resulting coating were compared to the current situation using several diagnostic methods. The improved process significantly reduces costs and achieves the requirement of comparable coating quality. Furthermore, a contribution was made towards better comprehension of the APS of ceramics and the definition of a better method for future process developments.

  5. Electrophoretic deposition of PEEK-TiO 2 composite coatings on stainless steel

    KAUST Repository

    Seuß, Sigrid

    2012-03-01

    Electrophoretic deposition (EPD) has been successfully used to deposit composite coatings composed of polyetheretherketone (PEEK) and titanium dioxide (TiO 2) nanoparticles on 316L stainless steel substrates. The suspensions of TiO2 nanoparticles and PEEK microparticles for EPD were prepared in ethanol. PEEK-TiO 2 composite coatings were optimized using suspensions containing 6wt% PEEK-TiO 2 in ethanol with a 3:1 ratio of PEEK to TiO 2 in weight and by applying a potential difference of 30 V for 1 minute. A heat-treatment process of the optimized PEEK-TiO 2 composite coatings was erformed at 335°C for 30 minutes with a heating rate of 10°Cmin -1 to densify the deposits. The EPD coatings were microstructurally evaluated by scanning electron microscopy (SEM). It was demonstrated that EPD is a convenient and rapid method to fabricate PEEK/TiO 2 coatings on stainless steel which are interesting for biomedical applications. © (2012) Trans Tech Publications, Switzerland.

  6. Nanocomposite Coatings Codeposited with Nanoparticles Using Aerosol-Assisted Chemical Vapour Deposition

    Directory of Open Access Journals (Sweden)

    Xianghui Hou

    2013-01-01

    Full Text Available Incorporating nanoscale materials into suitable matrices is an effective route to produce nanocomposites with unique properties for practical applications. Due to the flexibility in precursor atomization and delivery, aerosol-assisted chemical vapour deposition (AACVD process is a promising way to synthesize desired nanocomposite coatings incorporating with preformed nanoscale materials. The presence of nanoscale materials in AACVD process would significantly influence deposition mechanism and thus affect microstructure and properties of the nanocomposites. In the present work, inorganic fullerene-like tungsten disulfide (IF-WS2 has been codeposited with Cr2O3 coatings using AACVD. In order to understand the codeposition process for the nanocomposite coatings, chemical reactions of the precursor and the deposition mechanism have been studied. The correlation between microstructure of the nanocomposite coatings and the codeposition mechanism in the AACVD process has been investigated. The heterogeneous reaction on the surface of IF-WS2 nanoparticles, before reaching the substrate surface, is the key feature of the codeposition in the AACVD process. The agglomeration of nanoparticles in the nanocomposite coatings is also discussed.

  7. Atomic Layer Deposition for Coating of High Aspect Ratio TiO2 Nanotube Layers

    Science.gov (United States)

    2016-01-01

    We present an optimized approach for the deposition of Al2O3 (as a model secondary material) coating into high aspect ratio (≈180) anodic TiO2 nanotube layers using the atomic layer deposition (ALD) process. In order to study the influence of the diffusion of the Al2O3 precursors on the resulting coating thickness, ALD processes with different exposure times (i.e., 0.5, 2, 5, and 10 s) of the trimethylaluminum (TMA) precursor were performed. Uniform coating of the nanotube interiors was achieved with longer exposure times (5 and 10 s), as verified by detailed scanning electron microscopy analysis. Quartz crystal microbalance measurements were used to monitor the deposition process and its particular features due to the tube diameter gradient. Finally, theoretical calculations were performed to calculate the minimum precursor exposure time to attain uniform coating. Theoretical values on the diffusion regime matched with the experimental results and helped to obtain valuable information for further optimization of ALD coating processes. The presented approach provides a straightforward solution toward the development of many novel devices, based on a high surface area interface between TiO2 nanotubes and a secondary material (such as Al2O3). PMID:27643411

  8. Characterization and antibacterial performance of ZrCN/amorphous carbon coatings deposited on titanium implants

    Energy Technology Data Exchange (ETDEWEB)

    Lai, Chih-Ho [School of Medicine, China Medical University, Taichung, 404 Taiwan (China); Chang, Yin-Yu, E-mail: yinyu@mail2000.com.tw [Department of Mechanical and Computer-Aided Engineering, National Formosa University, Yunlin, Taiwan (China); Huang, Heng-Li [School of Dentistry, China Medical University, Taichung, Taiwan (China); Kao, Ho-Yi [Department of Materials Science and Engineering, Mingdao University, Changhua, Taiwan (China)

    2011-12-30

    Titanium (Ti)-based materials have been used for dental/orthopedic implants due to their excellent biological compatibility, superior mechanical strength and high corrosion resistance. The osseointegration of Ti implants is related to their composition and surface treatment. Better biocompatibility and anti-bacterial performances of Ti implant are beneficial for the osseointegration and for avoiding the infection after implantation surgery. In this study, nanocomposite ZrCN/amorphous carbon (a-C) coatings with different carbon contents were deposited on a bio-grade pure Ti implant material. A cathodic-arc evaporation system with plasma enhanced duct equipment was used for the deposition of ZrCN/a-C coatings. Reactive gas (N{sub 2}) and C{sub 2}H{sub 2} activated by the zirconium plasma in the evaporation process were used to deposit the ZrCN/a-C coatings. To verify the susceptibility of implant surface to bacterial adhesion, Actinobacillus actinomycetemcomitans (A. actinomycetemcomitans), one of the major pathogen frequently found in the dental implant-associated infections, was chosen for in vitro anti-bacterial analyses. In addition, the biocompatibility of human gingival fibroblast (HGF) cells on coatings was also evaluated by a cell proliferation assay. The results suggested that the ZrCN/a-C coatings with carbon content higher than 12.7 at.% can improve antibacterial performance with excellent HGF cell compatibility as well.

  9. Characterization and antibacterial performance of ZrCN/amorphous carbon coatings deposited on titanium implants

    International Nuclear Information System (INIS)

    Lai, Chih-Ho; Chang, Yin-Yu; Huang, Heng-Li; Kao, Ho-Yi

    2011-01-01

    Titanium (Ti)-based materials have been used for dental/orthopedic implants due to their excellent biological compatibility, superior mechanical strength and high corrosion resistance. The osseointegration of Ti implants is related to their composition and surface treatment. Better biocompatibility and anti-bacterial performances of Ti implant are beneficial for the osseointegration and for avoiding the infection after implantation surgery. In this study, nanocomposite ZrCN/amorphous carbon (a-C) coatings with different carbon contents were deposited on a bio-grade pure Ti implant material. A cathodic-arc evaporation system with plasma enhanced duct equipment was used for the deposition of ZrCN/a-C coatings. Reactive gas (N 2 ) and C 2 H 2 activated by the zirconium plasma in the evaporation process were used to deposit the ZrCN/a-C coatings. To verify the susceptibility of implant surface to bacterial adhesion, Actinobacillus actinomycetemcomitans (A. actinomycetemcomitans), one of the major pathogen frequently found in the dental implant-associated infections, was chosen for in vitro anti-bacterial analyses. In addition, the biocompatibility of human gingival fibroblast (HGF) cells on coatings was also evaluated by a cell proliferation assay. The results suggested that the ZrCN/a-C coatings with carbon content higher than 12.7 at.% can improve antibacterial performance with excellent HGF cell compatibility as well.

  10. Microstructural Evolution of (Ti,W,CrB2 Coatings Deposited on Steel Substrates during Annealing

    Directory of Open Access Journals (Sweden)

    Aleksandra Newirkowez

    2014-05-01

    Full Text Available The topic of the present experiments are transition metal diboride coatings of composition (Ti0.49W0.51B2 and (Ti0.44W0.30Cr0.26B2. The coatings were deposited on steel substrates using dc magnetron sputtering. We investigated how annealing in argon at elevated temperatures modifies microstructure. The as-deposited films are amorphous. Annealing between 700 and 1100 °C results in the formation of nano-crystalline precipitates with average grain diameters of about 10–50 nm. A TiC phase (Fm-3m; a ≈ 4.3 Å is observed as the dominating precipitate phase. In addition, small amounts (10%–20% of a Cr23C6 phase (Fm-3m; a ≈ 10.6 Å are observed. In contrast to literature data on the same coatings deposited on silicon substrates, the formation of boride precipitate phases is strongly suppressed here. From investigations with X-ray diffractometry, electron microscopy and secondary ion mass spectrometry we conclude that the nanostructure of the coatings is formed by reactive phase formation of the boride coating with the carbon containing steel substrate.

  11. Prospects of chemically deposited CoS-CU2S coatings for solar ...

    African Journals Online (AJOL)

    Moreover, the coating of the glass substrates with a thin layer of CoS prior to Cu2S film deposition was found to improve the mechanical stability of the Cu2S thin films, offering the choice of different shades of colours for the same integrated transmittance in the visible region in solar control applications. The possibility ...

  12. Corrosion resistant Zn–Co alloy coatings deposited using saw-tooth ...

    Indian Academy of Sciences (India)

    Optimal configuration, represented as (Zn–Co)2.0/4.0/300 was found to exhibit ∼ 89 times better corrosion resistance compared to monolithic (Zn–Co)3.0 alloy deposited for same time, from same bath. The better corrosion resistance of CMMA coatings was attributed to changed interfacial dielectric properties, evidenced by ...

  13. The electrochemical deposition of tin-nickel alloys and the corrosion properties of the coating

    DEFF Research Database (Denmark)

    Jellesen, Morten Stendahl; Møller, Per

    2005-01-01

    The electrodeposition of tin/nickel (65/35 wt%) is a unique coating process because of the deposition of an intermetallic phase of nickel and tin, which cannot be formed by any pyrometallurgical process. From thermodynamic calculations it can be shown that intermetallic phases can be formed throu...

  14. Fabrication of Antireflection Nanodiamond Particle Film by the Spin Coating Deposition Technique

    Directory of Open Access Journals (Sweden)

    Chii-Ruey Lin

    2014-01-01

    Full Text Available Diamond-based antireflective (AR coatings were fabricated using a spin coating of diamond suspension at room temperature as nucleation enhancement procedure and microwave plasma enhanced chemical vapour deposition. Various working pressures were used to investigate their effect on the optical characterization of the as-deposited diamond films. Scanning electron microscopy (SEM and atomic forced microscopy (AFM were employed to analyze the surface properties of the diamond films. Raman spectra and transmission electron microscopy (TEM also were used for analysis of the microstructure of the films. The results showed that working pressure had a significant effect on thickness, surface roughness, and wettability of the as-deposited diamond films. Deposited under 35 Torr or working pressure, the film possessed a low surface roughness of 13.8 nm and fine diamond grain sizes of 35 nm. Reflectance measurements of the films also were carried out using UV-Vis spectrometer and revealed a low reflectance value of the diamond films. The achievement demonstrated feasibility of the proposed spin-coating procedure for large scale production and thus opens up a prospect application of diamond film as an AR coating in industrial optoelectronic device.

  15. Tribological properties of duplex MAO/DLC coatings on magnesium alloy using combined microarc oxidation and filtered cathodic arc deposition

    International Nuclear Information System (INIS)

    Liang Jun; Wang Peng; Hu Litian; Hao Jingcheng

    2007-01-01

    The combined microarc oxidation (MAO) and filtered cathode arc deposition process was used to deposit duplex MAO/DLC coating on AM60B magnesium alloy. The microstructure and composition of the resulting duplex coating were analyzed by Raman spectroscopy, X-ray photoelectron spectroscope (XPS) and scanning electron microscope (SEM). The tribological behaviors of the duplex coating were studied by ball-on-disk friction testing. It is found that the Ti-doped DLC thin film could be successfully deposited onto the polished MAO coating. The duplex MAO/DLC coating exhibits a better tribological property than the DLC or MAO monolayer on Mg alloy substrate, owing to the MAO coating served as an intermediate layer provides improved load support for the soft Mg alloy substrate and the DLC top coating exhibits low friction coefficient

  16. Influence of relative humidity during coating on polymer deposition and film formation.

    Science.gov (United States)

    Macchi, Elena; Felton, Linda A

    2016-08-20

    The influence of relative humidity in the pan during coating on polymer deposition and film formation was investigated. Four tablet substrates, differing in hydrophobicity, porosity, and surface roughness, were prepared and coated with Eudragit(®) RS/RL 30 D (8:2 ratio). The spray rate and atomization air pressure were varied to create two distinct micro-environmental conditions in the coating pan. PyroButton data logging devices placed directly in the pan were found to more accurately reflect the relative humidity to which tablets were exposed in comparison to measurements taken at the exhaust. Polymer deposition was shown to be influenced by the properties of the substrate, rather than the processing conditions used during coating, with higher polymer weight gains observed for the more porous tablets. Differences in the film-tablet interface and in the release performance of the coated products, however, were attributed to both the relative humidity in the pan and tablet porosity. Overall, this study demonstrated that a more humid coating process (86% vs 67%) promoted surface dissolution and physical mixing of the tablet ingredients with the forming film and the extent of this phenomenon was dependent on the tablet porosity. Copyright © 2016 Elsevier B.V. All rights reserved.

  17. Structure and corrosion properties of Cr coating deposited on aerospace bearing steel

    Science.gov (United States)

    Wang, Fangfang; Zhang, Fengxiang; Zheng, Lijing; Zhang, Hu

    2017-11-01

    The corrosion protection of chromium coating deposited on aerospace bearing steels by using the Filtered Cathodic Vacuum Arc deposition- Metal Evaporation Vacuum Arc duplex technique (MEVVA-FCVA) had been investigated. The protection efficiency of chromium coating on different substrate materials had also been evaluated. The chromium coating was mainly composed of nanocrystallineα-Cr in a range of 50-200 nm. The orientation distributions of α-Cr film on substrates with different composition had a certain difference to each other. Electrochemical experimental results indicated that the chromium coating significantly improved the corrosion resistance of experimental bearing steels in 3.5% NaCl solution. The protective efficiency of chromium films were all over 98%. The corrosion resistance of chromium coating was influenced by the chemical composition of substrate material. The chromium coatings on higher Cr-containing substrate displayed lower corrosion current density and more positive corrosion potential. The increase of passive film thickness and the formation of a mass of chromium oxide and hydroxide on the surface are responsible for the improved corrosion properties.

  18. Nanostructured Photocatalytic TiO2 Coating Deposited by Suspension Plasma Spraying with Different Injection Positions

    Science.gov (United States)

    Liu, Xuezhang; Wen, Kui; Deng, Chunming; Yang, Kun; Deng, Changguang; Liu, Min; Zhou, Kesong

    2018-02-01

    High plasma power is beneficial for the deposition efficiency and adhesive strength of suspension-sprayed photocatalytic TiO2 coatings, but it confronts two challenges: one is the reduced activity due to the critical phase transformation of anatase into rutile, and the other is fragmented droplets which cannot be easily injected into the plasma core. Here, TiO2 coatings were deposited at high plasma power and the position of suspension injection was varied with the guidance of numerical simulation. The simulation was based on a realistic three-dimensional time-dependent numerical model that included the inside and outside of torch regions. Scanning electron microscopy was performed to study the microstructure of the TiO2 coatings, whereas x-ray diffraction was adopted to analyze phase composition. Meanwhile, photocatalytic activities of the manufactured TiO2 coatings were evaluated by the degradation of an aqueous solution of methylene blue dye. Fragmented droplets were uniformly injected into the plasma jet, and the solidification pathway of melting particles was modified by varying the position of suspension injection. A nanostructured TiO2 coating with 93.9% anatase content was obtained at high plasma power (48.1 kW), and the adhesive coating bonding to stainless steel exhibited the desired photocatalytic activity.

  19. Sealing of hard CrN and DLC coatings with atomic layer deposition.

    Science.gov (United States)

    Härkönen, Emma; Kolev, Ivan; Díaz, Belén; Swiatowska, Jolanta; Maurice, Vincent; Seyeux, Antoine; Marcus, Philippe; Fenker, Martin; Toth, Lajos; Radnoczi, György; Vehkamäki, Marko; Ritala, Mikko

    2014-02-12

    Atomic layer deposition (ALD) is a thin film deposition technique that is based on alternating and saturating surface reactions of two or more gaseous precursors. The excellent conformality of ALD thin films can be exploited for sealing defects in coatings made by other techniques. Here the corrosion protection properties of hard CrN and diamond-like carbon (DLC) coatings on low alloy steel were improved by ALD sealing with 50 nm thick layers consisting of Al2O3 and Ta2O5 nanolaminates or mixtures. In cross sectional images the ALD layers were found to follow the surface morphology of the CrN coatings uniformly. Furthermore, ALD growth into the pinholes of the CrN coating was verified. In electrochemical measurements the ALD sealing was found to decrease the current density of the CrN coated steel by over 2 orders of magnitude. The neutral salt spray (NSS) durability was also improved: on the best samples the appearance of corrosion spots was delayed from 2 to 168 h. On DLC coatings the adhesion of the ALD sealing layers was weaker, but still clear improvement in NSS durability was achieved indicating sealing of the pinholes.

  20. Pulsed laser deposition of antimicrobial silver coating on Ormocer (registered) microneedles

    Energy Technology Data Exchange (ETDEWEB)

    Gittard, S D; Narayan, R J; Jin, C; Monteiro-Riviere, N A [Joint Department of Biomedical Engineering, North Carolina State University, Raleigh, NC 27695 (United States); Ovsianikov, A; Chichkov, B N [Laser Zentrum Hannover, Hollerithallee 8, 30419 Hannover (Germany); Stafslien, S; Chisholm, B, E-mail: roger_narayan@msn.co [Center for Nanoscale Science and Engineering, North Dakota State University, 1805 Research Park Drive, Fargo, ND 58102 (United States)

    2009-12-15

    One promising option for transdermal delivery of protein- and nucleic acid-based pharmacologic agents involves the use of microneedles. However, microneedle-generated pores may allow microorganisms to penetrate the stratum corneum layer of the epidermis and cause local or systemic infection. In this study, microneedles with antimicrobial functionality were fabricated using two-photon polymerization-micromolding and pulsed laser deposition. The antibacterial activity of the silver-coated organically modified ceramic (Ormocer (registered) ) microneedles was demonstrated using an agar diffusion assay. Human epidermal keratinocyte viability on the Ormocer (registered) surfaces coated with silver was similar to that on uncoated Ormocer (registered) surfaces. This study indicates that coating microneedles with silver thin films using pulsed laser deposition is a useful and novel approach for creating microneedles with antimicrobial functionality. (communication)

  1. Pulsed laser deposition of antimicrobial silver coating on Ormocer (registered) microneedles

    International Nuclear Information System (INIS)

    Gittard, S D; Narayan, R J; Jin, C; Monteiro-Riviere, N A; Ovsianikov, A; Chichkov, B N; Stafslien, S; Chisholm, B

    2009-01-01

    One promising option for transdermal delivery of protein- and nucleic acid-based pharmacologic agents involves the use of microneedles. However, microneedle-generated pores may allow microorganisms to penetrate the stratum corneum layer of the epidermis and cause local or systemic infection. In this study, microneedles with antimicrobial functionality were fabricated using two-photon polymerization-micromolding and pulsed laser deposition. The antibacterial activity of the silver-coated organically modified ceramic (Ormocer (registered) ) microneedles was demonstrated using an agar diffusion assay. Human epidermal keratinocyte viability on the Ormocer (registered) surfaces coated with silver was similar to that on uncoated Ormocer (registered) surfaces. This study indicates that coating microneedles with silver thin films using pulsed laser deposition is a useful and novel approach for creating microneedles with antimicrobial functionality. (communication)

  2. Chemical vapor deposition of aluminide coatings on iron, nickel and superalloys

    International Nuclear Information System (INIS)

    John, John T.; De, P.K.; Dubey, Vivekanand; Srinivasa, Raman

    2009-08-01

    Aluminide coatings are a class of intermetallic coatings applied on nickel and cobalt base superalloys and steels to protect them from different forms of environmental degradation at high temperatures. In this report a CVD system that can produce the aluminide coatings on iron, nickel and nickel base alloys has been described and the result of chemical vapor deposition of aluminide coatings on iron specimens, their characterization, and property evaluation have been presented. The CVD system consists of an AlCl 3 bath, a stainless steel retort as a hot-wall reacto, cold traps and vacuum system. Aluminium chloride vapor was carried in a stream of hydrogen gas at a flow rate of 150 SCCM (standard cubic centimeter per minute) into the CVD reactor maintained in the temperature range of 1173 - 1373 K and at a pressure of 1.33 kPa (10 Torr). Aluminum deposition takes place from aluminium subchlorides produced by reaction between AlCl 3 and pure aluminum kept in the CVD reactor. The aluminum diffuses into the iron samples and iron aluminide phases are formed at the surface. The coatings were shining bright and showed good adherence to the substrate. The coatings consisted of FeAl phase over a wide range of experimental conditions. The growth kinetics of the coating followed a parabolic rate law and the mean activation energy was 212 ±16 kJ/mol. Optical microscopic studies on the transverse section of the coating showed that the aluminide coating on iron consisted of two layers. The top layer had a thickness in the range of 20-50 μm, and the under layer had thickness ranging from 35 to 250 μm depending on coating temperature in two hours. The thickness of the aluminide layer increased with coating duration and temperature. Electron microprobe studies (EPMA) showed that the aluminum concentration decreased steadily as distance from the surface increased. TEM studies showed that the outer most layer had a B2 order (of the FeAl phase), which extended even into the under

  3. Influence of average ion energy and atomic oxygen flux per Si atom on the formation of silicon oxide permeation barrier coatings on PET

    Science.gov (United States)

    Mitschker, F.; Wißing, J.; Hoppe, Ch; de los Arcos, T.; Grundmeier, G.; Awakowicz, P.

    2018-04-01

    The respective effect of average incorporated ion energy and impinging atomic oxygen flux on the deposition of silicon oxide (SiO x ) barrier coatings for polymers is studied in a microwave driven low pressure discharge with additional variable RF bias. Under consideration of plasma parameters, bias voltage, film density, chemical composition and particle fluxes, both are determined relative to the effective flux of Si atoms contributing to film growth. Subsequently, a correlation with barrier performance and chemical structure is achieved by measuring the oxygen transmission rate (OTR) and by performing x-ray photoelectron spectroscopy. It is observed that an increase in incorporated energy to 160 eV per deposited Si atom result in an enhanced cross-linking of the SiO x network and, therefore, an improved barrier performance by almost two orders of magnitude. Furthermore, independently increasing the number of oxygen atoms to 10 500 per deposited Si atom also lead to a comparable barrier improvement by an enhanced cross-linking.

  4. Multi objective optimization of wear resistant TiAlN and TiN coatings deposite by PVD techniques

    OpenAIRE

    A. Zarychta; J. Ratajski; Ł. Szparaga

    2011-01-01

    Purpose: The goal of this paper is to determine, the optimal layer thickness of deposited coatings, in respect of thermal strain and stresses.Design/methodology/approach: For physical modelling purposes Cr, TiN and TiAlN layers were treated as a continuous medium, so the physical phenomena, occurring in the coating, are modelled based on a classical theory of stiffness. Computer model of the object (coating + substrate) describing strains and thermal stresses states in layers, after deposit...

  5. Development of Reliability Based Life Prediction Methods for Thermal and Environmental Barrier Coatings in Ceramic Matrix Composites

    Science.gov (United States)

    Shah, Ashwin

    2001-01-01

    Literature survey related to the EBC/TBC (environmental barrier coating/thermal barrier coating) fife models, failure mechanisms in EBC/TBC and the initial work plan for the proposed EBC/TBC life prediction methods development was developed as well as the finite element model for the thermal/stress analysis of the GRC-developed EBC system was prepared. Technical report for these activities is given in the subsequent sections.

  6. Dielectric properties and resistance to fatigue failure of different barrier layers prepared on flexible stainless-steel foils by ion-beam assisted deposition

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yu-qiong [National Microgravity Laboratory (NML), Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190 (China); School of Optoelectronics, Beijing Institute of Technology, Beijing 100081 (China); Yu, Zhi-nong, E-mail: znyu@bit.edu.cn [School of Optoelectronics, Beijing Institute of Technology, Beijing 100081 (China); Leng, Jian [Tianjin Key Laboratory of Optical Thin Films, Tianjin Jinhang Institute of Technical Physics, Tianjin 300192 (China); Wang, Hua-qing [Optical Thin Film Center, Daheng New Epoch Technology Inc., Beijing 100070 (China); Chen, She; Dong, Yu-hui [National Microgravity Laboratory (NML), Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190 (China); Jin, Gang, E-mail: gajin@imech.ac.cn [National Microgravity Laboratory (NML), Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190 (China)

    2012-08-31

    A stainless-steel foil is an attractive candidate for the substrate of flexible display devices and integrated solar modules. For electrical insulation and ion diffusion reduction, a barrier layer should be coated on the stainless-steel foil surface. In this study, different barrier layers such as SiO{sub x}, TaO{sub x}, TiO{sub x} and TaO{sub x}/SiO{sub x} were prepared on the flexible stainless-steel foils (SUS 304) by ion-beam assisted deposition. The dielectric properties of the barrier layers, including resistance, reactance, leakage current density, breakdown field strength and performance index, were investigated. The resistance to fatigue failure of the barrier layers was evaluated by insulating tests after the specimen foils were flattened. The results show that the dielectric properties and the resistance to fatigue failure of the TaO{sub x}/SiO{sub x} composite barrier layer are better than those of the SiO{sub x} or the TaO{sub x} barrier layer. The best dielectric properties and resistance to fatigue failure are achieved with the 4-{mu}m thick TaO{sub x}/SiO{sub x} composite barrier layer. - Highlights: Black-Right-Pointing-Pointer SiO{sub x}, TaO{sub x}, TiO{sub x} and TaO{sub x}/SiO{sub x} barrier layers are prepared on stainless-steel. Black-Right-Pointing-Pointer Barriers layers prepared by ion-beam assisted deposition. Black-Right-Pointing-Pointer Dielectric properties and resistance to fatigue failure performance are compared. Black-Right-Pointing-Pointer 4-{mu}m thick TaO{sub x}/SiO{sub x} layers show good dielectric properties and resistance to fatigue failure.

  7. Microstructure and Corrosion Resistance of Aluminium and Copper Composite Coatings Deposited by LPCS Method

    Directory of Open Access Journals (Sweden)

    Winnicki M.

    2016-12-01

    Full Text Available The paper presents the study of microstructure and corrosion resistance of composite coatings (Al+Al2O3 and Cu+Al2O3 deposited by Low Pressure Cold Spraying method (LPCS. The atmospheric corrosion resistance was examined by subjecting the samples to cyclic salt spray and Kesternich test chambers, with NaCl and SO2 atmospheres, respectively. The selected tests allowed reflecting the actual working conditions of the coatings. The analysis showed very satisfactory results for copper coatings. After eighteen cycles, with a total time of 432 hours, the samples show little signs of corrosion. Due to their greater susceptibility to chloride ions, aluminium coatings have significant corrosion losses.

  8. Design and Performance Optimizations of Advanced Erosion-Resistant Low Conductivity Thermal Barrier Coatings for Rotorcraft Engines

    Science.gov (United States)

    Zhu, Dongming; Miller, Robert A.; Kuczmarski, Maria A.

    2012-01-01

    Thermal barrier coatings will be more aggressively designed to protect gas turbine engine hot-section components in order to meet future rotorcraft engine higher fuel efficiency and lower emission goals. For thermal barrier coatings designed for rotorcraft turbine airfoil applications, further improved erosion and impact resistance are crucial for engine performance and durability, because the rotorcraft are often operated in the most severe sand erosive environments. Advanced low thermal conductivity and erosion-resistant thermal barrier coatings are being developed, with the current emphasis being placed on thermal barrier coating toughness improvements using multicomponent alloying and processing optimization approaches. The performance of the advanced thermal barrier coatings has been evaluated in a high temperature erosion burner rig and a laser heat-flux rig to simulate engine erosion and thermal gradient environments. The results have shown that the coating composition and architecture optimizations can effectively improve the erosion and impact resistance of the coating systems, while maintaining low thermal conductivity and cyclic oxidation durability

  9. Temperature measurement involving nanostructured thermal barrier coating using a multiwavelength pyrometer

    Science.gov (United States)

    Ng, Daniel

    1996-01-01

    It has been reported that erroneous results were obtained when a conventional pyrometer was used to measure the surface temperature of turbine engine components. Temperatures discrepancies were observed in components which were identical, except that one had its measured surface covered by a nanostructured thermal barrier coating (TBC) whereas the other component's surface was not so coated. These components were placed in an identical environment, receiving identical heat fluxes. A pyrometer measured the TBC covered surface hundreds degrees lower. These coatings were about 25 (mu)m thick, consisting of hundreds of layers of finer structures. The TBC's had very low thermal conductivity, heat flux calculations indicated that the temperatures of the coated surface should exhibit much higher temperature than the uncoated surface. Because these coatings were transparent to radiation from the visible to the infrared region, the temperatures measured by the pyrometer should be the temperature of the covered surface. Turbo components' performance and service life depend critically on the temperatures that it would experience; it is therefore important to know accurately and confidently the real surface temperature. Out of these concerns, an investigation into the measurement of nanostructured material surface temperature was carried out.

  10. The Development of Environmental Barrier Coating Systems for SiC-SiC Ceramic Matrix Composites: Environment Effects on the Creep and Fatigue Resistance

    Science.gov (United States)

    Zhu, Dongming; Ghosn, Louis J.

    2014-01-01

    Topics covered include: Environmental barrier coating system development: needs, challenges and limitations; Advanced environmental barrier coating systems (EBCs) for CMC airfoils and combustors; NASA EBC systems and material system evolutions, Current turbine and combustor EBC coating emphases, Advanced development, processing, testing and modeling, EBC and EBC bond coats: recent advances; Design tool and life prediction of coated CMC components; Advanced CMC-EBC rig demonstrations; Summary and future directions.

  11. Effect of the deposition temperature on corrosion resistance and biocompatibility of the hydroxyapatite coatings

    Science.gov (United States)

    Vladescu, A.; Braic, M.; Azem, F. Ak; Titorencu, I.; Braic, V.; Pruna, V.; Kiss, A.; Parau, A. C.; Birlik, I.

    2015-11-01

    Hydroxyapatite (HAP) ceramics belong to a class of calcium phosphate-based materials, which have been widely used as coatings on titanium medical implants in order to improve bone fixation and thus to increase the lifetime of the implant. In this study, HAP coatings were deposited from pure HAP targets on Ti6Al4V substrates using the radio-frequency magnetron sputtering technique at substrate temperatures ranging from 400 to 800 °C. The surface morphology and the crystallographic structure of the films were investigated by atomic force microscopy (AFM), scanning electron microscopy (SEM) and X-ray diffraction (XRD). The corrosion resistance of the coatings in saliva solution at 37 °C was evaluated by potentiodynamic polarization. Additionally, the human osteosarcoma cell line (MG-63) was used to test the biocompatibility of the coatings. The results showed that all of the coatings grown uniformly and that the increasing substrate temperature induced an increase in their crystallinity. Corrosion performance of the coatings was improved with the increase of the substrate temperature from 400 °C to 800 °C. Furthermore, all the coatings support the attachment and growth of the osteosarcoma cells with regard to the in vitro test findings.

  12. Transparent Pullulan/Mica Nanocomposite Coatings with Outstanding Oxygen Barrier Properties

    Directory of Open Access Journals (Sweden)

    Ilke Uysal Unalan

    2017-09-01

    Full Text Available This study presents a new bionanocomposite coating on poly(ethylene terephthalate (PET made of pullulan and synthetic mica. Mica nanolayers have a very high aspect ratio (α, at levels much greater than that of conventional exfoliated clay layers (e.g., montmorillonite. A very small amount of mica (0.02 wt %, which is ϕ ≈ 0.00008 in pullulan coatings dramatically improved the oxygen barrier performance of the nanocomposite films under dry conditions, however, this performance was partly lost as the environmental relative humidity (RH increased. This outcome was explained in terms of the perturbation of the spatial ordering of mica sheets within the main pullulan phase, because of RH fluctuations. This was confirmed by modelling of the experimental oxygen transmission rate (OTR data according to Cussler’s model. The presence of the synthetic nanobuilding block (NBB led to a decrease in both static and kinetic coefficients of friction, compared with neat PET (≈12% and 23%, respectively and PET coated with unloaded pullulan (≈26% reduction in both coefficients. In spite of the presence of the filler, all of the coating formulations did not significantly impair the overall optical properties of the final material, which exhibited haze values below 3% and transmittance above 85%. The only exception to this was represented by the formulation with the highest loading of mica (1.5 wt %, which is ϕ ≈ 0.01. These findings revealed, for the first time, the potential of the NBB mica to produce nanocomposite coatings in combination with biopolymers for the generation of new functional features, such as transparent high oxygen barrier materials.

  13. Optical and microstructural properties of Au alloyed Al–O sputter deposited coatings

    Energy Technology Data Exchange (ETDEWEB)

    Figueiredo, N.M., E-mail: nuno.figueiredo@dem.uc.pt [SEG-CEMUC, Department of Mechanical Engineering, University of Coimbra (Portugal); Vaz, F.; Cunha, L. [Center of Physics, University of Minho (Portugal); Pei, Y.T.; De Hosson, J.T.M. [Materials Innovation Institute M2i, Department of Applied Physics, Zernike Institute for Advanced Materials, University of Groningen (Netherlands); Cavaleiro, A. [SEG-CEMUC, Department of Mechanical Engineering, University of Coimbra (Portugal)

    2016-01-01

    This research is focused on the microstructure and optical properties of an Al–O dielectric matrix incorporated with increasing Au contents up to 11 at.%. For the as-deposited coatings, the Au atoms appear to be alloyed into the amorphous oxide matrix, although a small fraction of Au atoms can also be incorporated in the form of very small nanoparticles (< 1–2 nm). Precipitation of Au nanoparticles was found in the coatings after annealing at increasing temperatures. Au clustering in the dielectric matrix was able to promote the surface plasmon resonance (SPR) effect, a desirable effect for applications in decorative and sensors fields. - Highlights: • Au-Al{sub 2}O{sub 3} nanocomposites with Au contents between 0 and 11 at.% were deposited by reactive co-sputtering. • For the as-deposited coatings, the Au atoms appear to be alloyed into the amorphous oxide matrix. • Precipitation of Au nanoparticles was found in the coatings after annealing at increasing temperatures. • Surface Plasmon Resonance effect was noted only after thermal annealing at 500 °C.

  14. Recent Advances in the Deposition of Diamond Coatings on Co-Cemented Tungsten Carbides

    Directory of Open Access Journals (Sweden)

    R. Polini

    2012-01-01

    Full Text Available Co-cemented tungsten carbides, namely, hard metals are largely used to manufacture high wear resistant components in several manufacturing segments. Coating hard metals with superhard materials like diamond is of utmost interest as it can further extend their useful lifespan. The deposition of diamond coatings onto WC-Co can be extremely complicated as a result of poor adhesion. This can be essentially ascribed to (i the mismatch in thermal expansion coefficients between diamond and WC-Co, at the typical high temperatures inside the chemical vapour deposition (CVD chamber, generates large residual stresses at the interface; (ii the role of surface Co inside the WC-Co matrix during diamond CVD, which promotes carbon dissolution and diffusion. The present investigation reviews the techniques by which Co-cemented tungsten carbides can be treated to make them prone to receive diamond coatings by CVD. Further, it proposes interesting ecofriendly and sustainable alternatives to further improve the diamond deposition process as well as the overall performance of the coated hard metals.

  15. Bacterial adherence on fluorinated carbon based coatings deposited on polyethylene surfaces

    International Nuclear Information System (INIS)

    Terriza, A; Del Prado, G; Perez, A Ortiz; Martinez, M J; Puertolas, J A; Manso, D Molina; Gonzalez-Elipe, A R; Yubero, F; Barrena, E Gomez; Esteban, J

    2010-01-01

    Development of intrinsically antibacterial surfaces is of key importance in the context of prostheses used in orthopaedic surgery. In this work we present a thorough study of several plasma based coatings that may be used with this functionality: diamond like carbon (DLC), fluorine doped DLC (F-DLC) and a high fluorine content carbon-fluor polymer (CF X ). The study correlates the surface chemistry and hydrophobicity of the coating surfaces with their antibacterial performance. The coatings were deposited by RF-plasma assisted deposition at room temperature on ultra high molecular weight polyethylene (UHMWPE) samples. Fluorine content and relative amount of C-C and C-F bond types was monitored by X-ray photoelectron spectroscopy and hydrophobicity by water contact angle measurements. Adherence of Staphylococcus aureus and Staphylococcus epidermidis to non-coated and coated UHMWPE samples was evaluated. Comparisons of the adherence performance were evaluated using a paired t test (two materials) and a Kruskall Wallis test (all the materials). S. aureus was statistically significant (p< 0.001) less adherent to DLC and F-DLC surfaces than S. epidermidis. Both bacteria showed reduction of adherence on DLC/UHMWPE. For S. aureus, reduction of bacterial adherence on F-DLC/UHMWPE was statistically significant respect to all other materials.

  16. PLASMA THERMAL BARRIER COATINGS BASED ON ZIRCONIUM DIOXIDE WITH HIGH THERMAL STABILITY

    Directory of Open Access Journals (Sweden)

    O. G. Devoino

    2015-01-01

    Full Text Available The paper presents optimization of  processes for obtaining maximum content of tetragonal phase in the initial material and thermal barrier coatings (TBC based on zirconium dioxide and hafnium oxide.  Results of the investigations on phase composition of oxide HfO2 – ZrO2 – Y2O3  system have been given in the paper. The system represents  a microstructure which is similar to  zirconia dioxide and  transformed for its application at 1300 °C. The paper explains a mechanism of hafnium oxide influence on formation of the given microstructure. The research methodology has been based on complex metallography, X – ray diffraction and electron microscopic investigations of  structural elements of the composite plasma coating HfO2 – ZrO2 – Y2O system.In order to stabilize zirconium dioxide  dopant oxide should not only have an appropriate size of  metal ion, but also form a solid solution with the zirconia. This condition severely limits the number of possible stabilizers. In fact, such stabilization is possible only with the help of rare earth oxides (Y2O3, Yb2O3, CeO2, HfO2. Chemical purity of the applied materials plays a significant role for obtaining high-quality thermal barrier coatings. Hafnium oxide has been selected as powder for thermal barrier coatings instead of zirconium dioxide due to their similarities in structural modification, grating, chemical and physical properties and its high temperature structural transformations. It has been established that plasma thermal barrier HfO2 – ZrO2 – Y2O3 coatings consist of  one tetragonal phase. This phase is equivalent to a non-equilibrium tetragonal t' phase in the “zirconium dioxide stabilized with yttrium oxide” system. Affinity of  Hf+4 and Zr+4 cations leads to the formation of identical metastable phases during rapid quenching.

  17. Epitaxial solution deposition of YBa2Cu3O7-6 coated conductors.

    Energy Technology Data Exchange (ETDEWEB)

    Overmyer, Donald L.; Clem, Paul Gilbert; Siegal, Michael P.; Holesinger, Terry A. (Los Alamos National Laboratory, Los Alamos, NM); Voigt, James A.; Richardson, Jacob J.; Dawley, Jeffrey Todd

    2004-11-01

    A variety of solution deposition routes have been reported for processing complex perovskite-based materials such as ferroelectric oxides and conductive electrode oxides, due to ease of incorporating multiple elements, control of chemical stoichiometry, and feasibility for large area deposition. Here, we report an extension of these methods toward long length, epitaxial film solution deposition routes to enable biaxially oriented YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} (YBCO)-coated conductors for superconducting transmission wires. Recent results are presented detailing an all-solution deposition approach to YBCO-coated conductors with critical current densities J{sub c} (77 K) > 1 MA/cm{sup 2} on rolling-assisted, biaxially textured, (200)-oriented Ni-W alloy tapes. Solution-deposition methods such as this approach and those of other research groups appear to have promise to compete with vapor phase methods for superconductor electrical properties, with potential advantages for large area deposition and low cost/kA {center_dot} m of wire.

  18. Bovine serum albumin adsorption to iron-oxide coated sands can change microsphere deposition mechanisms.

    Science.gov (United States)

    Flynn, Raymond M; Yang, Xinyao; Hofmann, Thilo; von der Kammer, Frank

    2012-03-06

    Particulate colloids often occur together with proteins in sewage-impacted water. Using Bovine Serum Albumin (BSA) as a surrogate for protein in sewage, column experiments investigating the capacity of iron-oxide coated sands to remove latex microspheres from water revealed that microsphere attenuation mechanisms depended on antecedent BSA coverage. Dual pulse experiment (DPE) results suggested that where all BSA was adsorbed, subsequent multiple pore volume microsphere breakthrough curves reflected progressively reduced colloid deposition rates with increasing adsorbed BSA content. Modeling colloid responses suggested adsorption of 1 μg BSA generated the same response as blockage by between 7.1 × 10(8) and 2.3 × 10(9) deposited microspheres. By contrast, microsphere responses in DPEs where BSA coverage of the deposition sites approached/reached saturation revealed the coated sand maintained a finite capacity to attenuate microspheres, even when incapable of further BSA adsorption. Subsequent microsphere breakthrough curves demonstrated the matrix's colloid attenuation capacity progressively increased with continued microsphere deposition. Experimental findings suggested BSA adsorption on the sand surface approaching/reaching saturation generated attractive deposition sites for colloids, which became progressively more attractive with further colloid deposition (filter ripening). Results demonstrate that adsorption of a single type of protein may either enhance or inhibit colloid mobility in saturated porous media.

  19. Optimizing the vacuum plasma spray deposition of metal, ceramic, and cermet coatings using designed experiments

    Science.gov (United States)

    Kingswell, R.; Scott, K. T.; Wassell, L. L.

    1993-06-01

    The vacuum plasma spray (VPS) deposition of metal, ceramic, and cermet coatings has been investigated using designed statistical experiments. Processing conditions that were considered likely to have a significant influence on the melting characteristics of the precursor powders and hence deposition efficiency were incorporated into full and fractional factorial experimental designs. The processing of an alumina powder was very sensitive to variations in the deposition conditions, particularly the injection velocity of the powder into the plasma flame, the plasma gas composition, and the power supplied to the gun. Using a combination of full and fractional factorial experimental designs, it was possible to rapidly identify the important spraying variables and adjust these to produce a deposition efficiency approaching 80 percent. The deposition of a nickel-base alloy metal powder was less sensitive to processing conditions. Generally, however, a high degree of particle melting was achieved for a wide range of spray conditions. Preliminary experiments performed using a tungsten carbide/cobalt cermet powder indicated that spray efficiency was not sensitive to deposition conditions. However, microstructural analysis revealed considerable variations in the degree of tungsten carbide dissolution. The structure and properties of the optimized coatings produced in the factorial experiments are also discussed.

  20. Corrosion resistance and characterization of metallic coatings deposited by thermal spray on carbon steel

    International Nuclear Information System (INIS)

    Sá Brito, V.R.S.; Bastos, I.N.; Costa, H.R.M.

    2012-01-01

    Highlights: ► Five combinations of metallic coatings and intermediate bonds were deposited on carbon steels. ► High strength was reached in adhesion tests. ► Epoxy sealing of coatings improves corrosion resistance. -- Abstract: Carbon steels are not resistant to corrosion and several methods are used in surface engineering to protect them from aggressive environments such as marine. The main objective of this work is the evaluation of mechanical and metallurgical properties of five metallic coatings produced by thermal spray on carbon steel. Five chemical compositions were tested in order to give a large panel of possibility. Coatings were characterized by several methods to result in a screening of their performance. At first, the assessment of microstructural morphology by optical microscopy (OM) and by scanning electron microscopy (SEM) was made. OM and SEM results showed uniformity of deposited layer, low amount of oxides and porosity. The physical properties of coatings were also evaluated by microhardness measurement, adhesion and porosity quantification. The corrosion resistance was analyzed in salt spray and electrochemical polarization tests. In the polarization test, as well as in the salt spray, all sealed conditions presented low corrosion. A new intermediate 78.3Ni20Cr1.4Si0.3Fe alloy was studied in order to reduce pores and microcracks that are frequently found in ordinary 95Ni5Al alloy. Based on the performed characterizations, the findings suggested that the FeCrCo deposition, with an epoxy sealing, is suitable to be used as an efficient coating of carbon steel in aggressive marine environments.

  1. Bioactivity response of Ta1-xOx coatings deposited by reactive DC magnetron sputtering

    International Nuclear Information System (INIS)

    Almeida Alves, C.F.; Cavaleiro, A.; Carvalho, S.

    2016-01-01

    The use of dental implants is sometimes accompanied by failure due to periimplantitis disease and subsequently poor esthetics when soft–hard tissue margin recedes. As a consequence, further research is needed for developing new bioactive surfaces able to enhance the osseous growth. Tantalum (Ta) is a promising material for dental implants since, comparing with titanium (Ti), it is bioactive and has an interesting chemistry which promotes the osseointegration. Another promising approach for implantology is the development of implants with oxidized surfaces since bone progenitor cells interact with the oxide layer forming a diffusion zone due to its ability to bind with calcium which promotes a stronger bond. In the present report Ta-based coatings were deposited by reactive DC magnetron sputtering onto Ti CP substrates in an Ar + O 2 atmosphere. In order to assess the osteoconductive response of the studied materials, contact angle and in vitro tests of the samples immersed in Simulated Body Fluid (SBF) were performed. Structural results showed that oxide phases where achieved with larger amounts of oxygen (70 at.% O). More compact and smooth coatings were deposited by increasing the oxygen content. The as-deposited Ta coating presented the most hydrophobic character (100°); with increasing oxygen amount contact angles progressively diminished, down to the lowest measured value, 63°. The higher wettability is also accompanied by an increase on the surface energy. Bioactivity tests demonstrated that highest O-content coating, in good agreement with wettability and surface energy values, showed an increased affinity for apatite adhesion, with higher Ca/P ratio formation, when compared to the bare Ti substrates. - Highlights: • Ta 1-x O x coatings were deposited by reactive DC magnetron sputtering. • Amorphous oxide phases were achieved with higher oxygen amounts. • Contact angles progressively diminished, with increasing oxygen content. • Ta oxide surface

  2. Thermal Cycling and High-Temperature Corrosion Tests of Rare Earth Silicate Environmental Barrier Coatings

    Science.gov (United States)

    Darthout, Émilien; Gitzhofer, François

    2017-12-01

    Lutetium and yttrium silicates, enriched with an additional secondary zirconia phase, environmental barrier coatings were synthesized by the solution precursor plasma spraying process on silicon carbide substrates. A custom-made oven was designed for thermal cycling and water vapor corrosion testing. The oven can test four specimens simultaneously and allows to evaluate environmental barrier performances under similar corrosion kinetics compared to turbine engines. Coatings structural evolution has been observed by SEM on the polished cross sections, and phase composition has been analyzed by XRD. All coatings have been thermally cycled between 1300 °C and the ambient temperature, without spallation, due to their porosity and the presence of additional secondary phase which increases the thermal cycling resistance. During water vapor exposure at 1200 °C, rare earth disilicates showed a good stability, which is contradictory with the literature, due to impurities—such as Si- and Al-hydroxides—in the water vapor jets. The presence of vertical cracks allowed the water vapor to reach the substrate and then to corrode it. It has been observed that thin vertical cracks induced some spallation after 24 h of corrosion.

  3. Electrophoretic Deposition of α-Fe2O3/Chitosan Nanocomposite Coatings for Functional and Biomedical Applications.

    Science.gov (United States)

    Cabanas-Polo, S; Distaso, M; Peukert, W; Boccaccini, A R

    2015-12-01

    Promising composite coatings based on hematite (α-Fe2O3) mesocrystals of size 110 nm and chitosan (CHT) molecules for different biotechnological applications have been successfully obtained by electrophoretic deposition (EPD). Homogeneous and reproducible coatings have been obtained by studying and controlling the chemical interactions between both phases (α-Fe2O3 and CHT). A voltage of 25 V and a deposition time of 5 min were chosen as best deposition conditions, which resulted in highly homogeneous coatings with well-distributed α-Fe2O3 particles. According to TGA measurements, the content of α-Fe2O3 and chitosan in the final composite coating were found to be 74 and 26 wt%, respectively. The presence of both phases in the composite coating was determined by XRD analysis and the coatings microstructure was observed by SEM.

  4. Improving Barrier Properties of PET by Depositing a Layer of DLC Films on Surface

    Directory of Open Access Journals (Sweden)

    Zhiguo Zhang

    2013-01-01

    Full Text Available The diamond-like carbon films (DLC films depositing on the Poly (ethylene terephthalate (PET surface are obtained by plasma-enhanced chemical vapor deposition (PECVD, and the working gases are acetylene and argon gas. Surface morphology and the internal structure of DLC films are investigated by using Raman and FESEM, and the barrier properties of PET films which have been deposited the DLC films are tested in this paper. The results show that the deposition process parameters have an important effect on structure and performance of DLC films. It is shown that the diamond-like carbon films prepared by PECVD system are an amorphous carbon films which mixed with sp3 bond and sp2 bond. The best oxygen barrier property and water vapor barrier property of PET films are increased by 11 times and 12 times, respectively, in which the ID/IG ratio of the DLC film is nearly 0.76, and the sp3 content is about 40%.

  5. Structure and mechanical properties of Ti-Si-C coatings deposited by magnetron sputtering

    International Nuclear Information System (INIS)

    Koutzaki, S.H.; Krzanowski, J.E.; Nainaparampril, J.J.

    2001-01-01

    Nanostructured coatings consisting of mixed carbide phases can provide a potential means to developing superhard coatings. Heterogeneous nanostructured coatings can be obtained by either deposition of multilayer structures or by depositing film compositions that undergo a natural phase separation due to thermodynamic immiscibility. In the present work, we have taken the latter approach, and deposited films by radio frequency cosputtering from dual carbide targets. We have examined a number of ternary carbide systems, and here we report the results obtained on Ti-Si-C films with a nominal (Ti 1-x Si x )C stoichiometry and with x≤0.31. It was found that the nanoindentation hardness increased with Si content, and the maximum hardness achieved was nearly twice that of sputter-deposited TiC. We further analyzed these films using high-resolution transmission electron microscopy (TEM), x-ray photoelectron spectroscopy (XPS), and x-ray diffraction. Since cubic SiC has an x-ray pattern almost identical to that of TiC, the extent of phase separation could not be determined by that method. However, XRD did demonstrate a general disordering of the films with increasing SiC content. In addition, a mottled structure was observed in high-resolution TEM images of the Si-containing films, confirming microstructural effects due to the Si additions

  6. Superhydrophobic photocatalytic PTFE – Titania coatings deposited by reactive pDC magnetron sputtering from a blended powder target

    Energy Technology Data Exchange (ETDEWEB)

    Ratova, Marina, E-mail: marina_ratova@hotmail.com; Kelly, Peter J.; West, Glen T.

    2017-04-01

    The production of photocatalytic coatings with superhydrophobic properties, as opposed to the conventional hydrophilic properties, is desirable for the prevention of adhesion of contaminants to photocatalytic surfaces with subsequent deterioration of photocatalytic properties. In this work polytetrafluoroethylene (PTFE) – TiO{sub 2} composite thin films were deposited using a novel method of reactive pulsed direct current (pDC) magnetron sputtering of a blended PTFE – titanium oxide powder target. The surface characteristics and photocatalytic properties of the deposited composite coatings were studied. The as-deposited coatings were annealed at 523 K in air and analysed with Raman spectroscopy, optical profilometry and scanning electron microscopy. Hydrophobicity was assessed though measurements of water contact angles, and photocatalytic properties were studied via methylene blue dye degradation under UV irradiation. It was found that variations of gas flow and, hence, process pressures allowed deposition of samples combining superhydrophobicity with stable photocatalytic efficiency under UV light irradiation. Reversible wettability behaviour was observed with the alternation of light-dark cycles. - Highlights: • PTFE-TiO{sub 2} coatings were deposited by pDC reactive magnetron sputtering. • Blended powder target was used for coatings deposition. • Deposited coatings combined superhydrophobic and photocatalytic properties. • Under UV irradiation coatings exhibited reversible wettability.

  7. Microstructural Effects and Properties of Non-line-of-Sight Coating Processing via Plasma Spray-Physical Vapor Deposition

    Science.gov (United States)

    Harder, Bryan J.; Zhu, Dongming; Schmitt, Michael P.; Wolfe, Douglas E.

    2017-08-01

    Plasma spray-physical vapor deposition (PS-PVD) is a unique processing method that bridges the gap between conventional thermal spray and vapor phase methods, and enables highly tailorable coatings composed of a variety of materials in thin, dense layers or columnar microstructures with modification of the processing conditions. The strengths of this processing technique are material and microstructural flexibility, deposition speed, and potential for non-line-of-sight (NLOS) capability by vaporization of the feedstock material. The NLOS capability of PS-PVD is investigated here using yttria-stabilized zirconia and gadolinium zirconate, which are materials of interest for turbine engine applications. PS-PVD coatings were applied to static cylindrical substrates approximately 6-19 mm in diameter to study the coating morphology as a function of angle. In addition, coatings were deposited on flat substrates under various impingement configurations. Impingement angle had significant effects on the deposition mode, and microscopy of coatings indicated that there was a shift in the deposition mode at approximately 90° from incidence on the cylindrical samples, which may indicate the onset of more turbulent flow and PVD-like growth. Coatings deposited at non-perpendicular angles exhibited a higher density and nearly a 2× improvement in erosion performance when compared to coatings deposited with the torch normal to the surface.

  8. The protection of alloys against high temperature sulphidation by SiO@#2@#-coatings deposited by MOCVD

    NARCIS (Netherlands)

    Hofman, R.; Hofman, R.; Westheim, J.G.F.; Westheim, J.G.F.; Fransen, T.; Gellings, P.J.

    1992-01-01

    Silica coatings have been deposited on various alloys by MOCVD (Metal Organic Chemical Vapor Deposition) to protect them against high temperature corrosion in coal gasification environments. DiAcetoxyDitertiaryButoxySilane (DADBS) has been used as a metal organic precursor at deposition temperatures

  9. Ion-Bombardment of X-Ray Multilayer Coatings - Comparison of Ion Etching and Ion Assisted Deposition

    NARCIS (Netherlands)

    Puik, E. J.; van der Wiel, M. J.; Zeijlemaker, H.; Verhoeven, J.

    1991-01-01

    The effects of two forms of ion bombardment treatment on the reflectivity of multilayer X-ray coatings were compared: ion etching of the metal layers, taking place after deposition, and ion bombardment during deposition, the so-called ion assisted deposition. The ion beam was an Ar+ beam of 200 eV,

  10. SiC fiber and yttria-stabilized zirconia composite thick thermal barrier coatings fabricated by plasma spray

    Science.gov (United States)

    Ma, Rongbin; Cheng, Xudong; Ye, Weiping

    2015-12-01

    Approximately 4 mm-thick SiC fiber/yttria-stabilized zirconia (YSZ) composite thermal barrier coatings (TBCs) were prepared by atmospheric plasma spray (APS). The composite coatings have a 'reinforced concrete frame structure', which can protect the coating from failure caused by increasing thickness of coating. The SiC fiber plays an important role in reducing the residual stress level of the composite coatings. The thermal conductivity (TC) value of the composite coatings is 0.632 W/m K, which is about 50% reduction compared to that of typical APS YSZ TBCs. And the composite coatings have higher fracture toughness and better thermal shock resistance than the YSZ TBCs.

  11. Stability of tritium permeation prevention barrier with TiC and TiN + TiC coating

    International Nuclear Information System (INIS)

    Shan Changqi; Chen Qingwang; Dai Shaoxia; Jiang Weisheng

    1999-01-01

    The stability of tritium permeation prevention barrier of 316L stainless steel with coating TiC and TiN + TiC under the conditions of very large thermal gradient, thermal cycling and plasma irradiation is researched. The research includes two aspects: one is the study on the stability resisting H + plasma irradiation; another is on the ability of two coating materials when they are used in long term under the condition of very large thermal gradient and cycling. The results show that TiC and TiN + TiC composite coating materials, after chemical heat treatment and forming tritium permeation prevention barrier, can resist H + ion irradiation, and also can resist very large thermal gradient and thermal cycling. The long time experiments show that tritium permeation prevention barrier of those coating materials is stable when they are used in long term

  12. A solid-state nuclear magnetic resonance study of post-plasma reactions in organosilicone microwave plasma-enhanced chemical vapor deposition (PECVD) coatings.

    Science.gov (United States)

    Hall, Colin J; Ponnusamy, Thirunavukkarasu; Murphy, Peter J; Lindberg, Mats; Antzutkin, Oleg N; Griesser, Hans J

    2014-06-11

    Plasma-polymerized organosilicone coatings can be used to impart abrasion resistance and barrier properties to plastic substrates such as polycarbonate. Coating rates suitable for industrial-scale deposition, up to 100 nm/s, can be achieved through the use of microwave plasma-enhanced chemical vapor deposition (PECVD), with optimal process vapors such as tetramethyldisiloxane (TMDSO) and oxygen. However, it has been found that under certain deposition conditions, such coatings are subject to post-plasma changes; crazing or cracking can occur anytime from days to months after deposition. To understand the cause of the crazing and its dependence on processing plasma parameters, the effects of post-plasma reactions on the chemical bonding structure of coatings deposited with varying TMDSO-to-O2 ratios was studied with (29)Si and (13)C solid-state magic angle spinning nuclear magnetic resonance (MAS NMR) using both single-pulse and cross-polarization techniques. The coatings showed complex chemical compositions significantly altered from the parent monomer. (29)Si MAS NMR spectra revealed four main groups of resonance lines, which correspond to four siloxane moieties (i.e., mono (M), di (D), tri (T), and quaternary (Q)) and how they are bound to oxygen. Quantitative measurements showed that the ratio of TMDSO to oxygen could shift the chemical structure of the coating from 39% to 55% in Q-type bonds and from 28% to 16% for D-type bonds. Post-plasma reactions were found to produce changes in relative intensities of (29)Si resonance lines. The NMR data were complemented by Fourier transform infrared (FTIR) spectroscopy. Together, these techniques have shown that the bonding environment of Si is drastically altered by varying the TMDSO-to-O2 ratio during PECVD, and that post-plasma reactions increase the cross-link density of the silicon-oxygen network. It appears that Si-H and Si-OH chemical groups are the most susceptible to post-plasma reactions. Coatings produced at a

  13. SiO{sub 2} coating of silver nanoparticles by photoinduced chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Boies, Adam M; Girshick, Steven L [Department of Mechanical Engineering, University of Minnesota, 111 Church Street SE, Minneapolis, MN 55455 (United States); Roberts, Jeffrey T [Department of Chemistry, University of Minnesota, 207 Pleasant Street SE, Minneapolis, MN 55455 (United States); Zhang Bin; Nakamura, Toshitaka; Mochizuki, Amane, E-mail: jtrob@umn.ed, E-mail: slg@umn.ed [Nitto Denko Technical Corporation, 501 Via Del Monte, Oceanside, CA 92058 (United States)

    2009-07-22

    Gas-phase silver nanoparticles were coated with silicon dioxide (SiO{sub 2}) by photoinduced chemical vapor deposition (photo-CVD). Silver nanoparticles, produced by inert gas condensation, and a SiO{sub 2} precursor, tetraethylorthosilicate (TEOS), were exposed to vacuum ultraviolet (VUV) radiation at atmospheric pressure and varying temperatures. The VUV photons dissociate the TEOS precursor, initiating a chemical reaction that forms SiO{sub 2} coatings on the particle surfaces. Coating thicknesses were measured for a variety of operation parameters using tandem differential mobility analysis and transmission electron microscopy. The chemical composition of the particle coatings was analyzed using energy dispersive x-ray spectrometry and Fourier transform infrared spectroscopy. The highest purity films were produced at 300-400 {sup 0}C with low flow rates of additional oxygen. The photo-CVD coating technique was shown to effectively coat nanoparticles and limit core particle agglomeration at concentrations up to 10{sup 7} particles cm{sup -3}.

  14. Hydroxyapatite coating on cobalt alloys using electrophoretic deposition method for bone implant application

    Science.gov (United States)

    Aminatun; M, Shovita; I, Chintya K.; H, Dyah; W, Dwi

    2017-05-01

    Damage on bone due to osteoporosis and cancer triggered high demand for bone implant prosthesis which is a permanent implant. Thus, a prosthesis coated with hydroxyapatite (HA) is required because it is osteoconductive that can trigger the growth of osteoblast cells. The purpose of this study is to determine the optimum concentration of HA suspension in terms of the surface morphology, coating thickness, adhesion strength and corrosion rate resulting in the HA coating with the best characteristics for bone implant. Coating using electrophoretic deposition (EPD) method with concentrations of 0.02M, 0.04M, 0.06M, 0.08M, and 0.1M was performed on the voltage and time of 120V and 30 minutes respectively. The process was followed by sintering at the temperature of 900 °C for 10 minutes. The results showed that the concentration of HA suspension influences the thickness and the adhesion of layer of HA. The higher the concentration of HA-ethanol suspension the thicker the layer of HA, but its coating adhesion strength values became lower. The concentration of HA suspension of 0.04 M is the best concentration, with characteristics that meet the standards of the bone implant prosthesis. The characteristics are HA coating thickness of 199.93 ± 4.85 μm, the corrosion rate of 0.0018 mmpy and adhesion strength of 4.175 ± 0.716 MPa.

  15. Facile approach in the development of icephobic hierarchically textured coatings as corrosion barrier

    Science.gov (United States)

    Momen, G.; Farzaneh, M.

    2014-04-01

    An anti-corrosion superhydrophobic film with water contact angle greater than 160° on aluminum alloy 6061 substrate was fabricated simply through the spin-coating method applied to Al2O3 nanoparticles doped in silicone rubber solution. The as-obtained sample was characterized by scanning electron microscopy (SEM) and water contact angle/surface energy measurement. The corrosion behaviour of such coating in the NaCl solutions was investigated using the potentiodynamic polarization. The results show that the corrosion resistance of the developed superhydrophobic surface is improved greatly due to the composite wetting states or interfaces with numerous air pockets between its surface and the NaCl solution. This superhydrophobic coating could serve as an effective barrier against aggressive medium. Ice adhesion strength of the as-prepared superhydrophobic coating was also evaluated by measuring its ice adhesion force which was found to have reduced by 4.8 times compared to that of aluminum substrate as reference test.

  16. Neutron and X-ray diffraction of plasma-sprayed zirconia-yttria thermal barrier coatings

    Science.gov (United States)

    Shankar, N. R.; Herman, H.; Singhal, S. P.; Berndt, C. C.

    1984-01-01

    ZrO2-7.8mol. pct. YO1.5, a fused powder, and ZrO2-8.7mol. pct. YO1.5, a prereacted powder, were plasma-sprayed onto steel substrates. Neutron diffraction and X-ray diffraction of the as-received powder, the powder plasma sprayed into water, as-sprayed coatings, and coatings heat-treated for 10 and 100 h were carried out to study phase transformations and ordering of the oxygen ions on the oxygen sublattice. The as-received fused powder has a much lower monoclinic percentage than does the pre-reacted powder, this resulting in a much lower monoclinic percentage in the coating. Heat treatment increases the percentages of the cubic and monoclinic phases, while decreasing the tetragonal content. An ordered tetragonal phase is detected by the presence of extra neutron diffraction peaks. These phase transformations and ordering will result in volume changes. The implications of these transformations on the performance of partially stabilized zirconia thermal barrier coatings is discussed.

  17. Mueller matrix polarimetry on plasma sprayed thermal barrier coatings for porosity measurement.

    Science.gov (United States)

    Luo, David A; Barraza, Enrique T; Kudenov, Michael W

    2017-12-10

    Yttria-stabilized zirconia (YSZ) is the most widely used material for thermal plasma sprayed thermal barrier coatings (TBCs) used to protect gas turbine engine parts in demanding operation environments. The superior material properties of YSZ coatings are related to their internal porosity level. By quantifying the porosity level, tighter control on the spraying process can be achieved to produce reliable coatings. Currently, destructive measurement methods are widely used to measure the porosity level. In this paper, we describe a novel nondestructive approach that is applicable to classify the porosity level of plasma sprayed YSZ TBCs via Mueller matrix polarimetry. A rotating retarder Mueller matrix polarimeter was used to measure the polarization properties of the plasma sprayed YSZ coatings with different porosity levels. From these measurements, it was determined that a sample's measured depolarization ratio is dependent on the sample's surface roughness and porosity level. To this end, we correlate the depolarization ratio with the samples' surface roughness, as measured by a contact profilometer, as well as the total porosity level, in percentage measured using a micrograph and stereological analysis. With the use of this technique, a full-field and rapid measurement of porosity level can be achieved.

  18. Atomic-layer-deposited WNxCy thin films as diffusion barrier for copper metallization

    International Nuclear Information System (INIS)

    Kim, Soo-Hyun; Oh, Su Suk; Kim, Ki-Bum; Kang, Dae-Hwan; Li, Wei-Min; Haukka, Suvi; Tuominen, Marko

    2003-01-01

    The properties of WN x C y films deposited by atomic layer deposition (ALD) using WF 6 , NH 3 , and triethyl boron as source gases were characterized as a diffusion barrier for copper metallization. It is noted that the as-deposited film shows an extremely low resistivity of about 350 μΩ cm with a film density of 15.37 g/cm 3 . The film composition measured from Rutherford backscattering spectrometry shows W, C, and N of ∼48, 32, and 20 at. %, respectively. Transmission electron microscopy analyses show that the as-deposited film is composed of face-centered-cubic phase with a lattice parameter similar to both β-WC 1-x and β-W 2 N with an equiaxed microstructure. The barrier property of this ALD-WN x C y film at a nominal thickness of 12 nm deposited between Cu and Si fails only after annealing at 700 deg. C for 30 min

  19. Environmental Barrier Coating Development for SiC/SiC Ceramic Matrix Composites: Recent Advances and Future Directions

    Science.gov (United States)

    Zhu, Dongming

    2016-01-01

    This presentation briefly reviews the SiC/SiC major environmental and environment-fatigue degradations encountered in simulated turbine combustion environments, and thus NASA environmental barrier coating system evolution for protecting the SiC/SiC Ceramic Matrix Composites for meeting the engine performance requirements. The presentation will review several generations of NASA EBC materials systems, EBC-CMC component system technologies for SiC/SiC ceramic matrix composite combustors and turbine airfoils, highlighting the temperature capability and durability improvements in simulated engine high heat flux, high pressure, high velocity, and with mechanical creep and fatigue loading conditions. This paper will also focus on the performance requirements and design considerations of environmental barrier coatings for next generation turbine engine applications. The current development emphasis is placed on advanced NASA candidate environmental barrier coating systems for SiC/SiC CMCs, their performance benefits and design limitations in long-term operation and combustion environments. The efforts have been also directed to developing prime-reliant, self-healing 2700F EBC bond coat; and high stability, lower thermal conductivity, and durable EBC top coats. Major technical barriers in developing environmental barrier coating systems, the coating integrations with next generation CMCs having the improved environmental stability, erosion-impact resistance, and long-term fatigue-environment system durability performance will be described. The research and development opportunities for turbine engine environmental barrier coating systems by utilizing improved compositions, state-of-the-art processing methods, and simulated environment testing and durability modeling will be briefly discussed.

  20. Multilayer Thermal Barrier Coating (TBC) Architectures Utilizing Rare Earth Doped YSZ and Rare Earth Pyrochlores

    Science.gov (United States)

    Schmitt, Michael P.; Rai, Amarendra K.; Bhattacharya, Rabi; Zhu, Dongming; Wolfe, Douglas E.

    2014-01-01

    To allow for increased gas turbine efficiencies, new insulating thermal barrier coatings (TBCs) must be developed to protect the underlying metallic components from higher operating temperatures. This work focused on using rare earth doped (Yb and Gd) yttria stabilized zirconia (t' Low-k) and Gd2Zr2O7 pyrochlores (GZO) combined with novel nanolayered and thick layered microstructures to enable operation beyond the 1200 C stability limit of current 7 wt% yttria stabilized zirconia (7YSZ) coatings. It was observed that the layered system can reduce the thermal conductivity by approximately 45 percent with respect to YSZ after 20 hr of testing at 1316 C. The erosion rate of GZO is shown to be an order to magnitude higher than YSZ and t' Low-k, but this can be reduced by almost 57 percent when utilizing a nanolayered structure. Lastly, the thermal instability of the layered system is investigated and thought is given to optimization of layer thickness.

  1. Study on Stress Development in the Phase Transition Layer of Thermal Barrier Coatings

    Directory of Open Access Journals (Sweden)

    Yijun Chai

    2016-09-01

    Full Text Available Stress development is one of the significant factors leading to the failure of thermal barrier coating (TBC systems. In this work, stress development in the two phase mixed zone named phase transition layer (PTL, which grows between the thermally grown oxide (TGO and the bond coat (BC, is investigated by using two different homogenization models. A constitutive equation of the PTL based on the Reuss model is proposed to study the stresses in the PTL. The stresses computed with the proposed constitutive equation are compared with those obtained with Voigt model-based equation in detail. The stresses based on the Voigt model are slightly higher than those based on the Reuss model. Finally, a further study is carried out to explore the influence of phase transition proportions on the stress difference caused by homogenization models. Results show that the stress difference becomes more evident with the increase of the PTL thickness ratio in the TGO.

  2. Time history of diesel particle deposition in cylindrical dielectric barrier discharge reactors

    Energy Technology Data Exchange (ETDEWEB)

    Talebizadeh, P.; Rahimzadeh, H., E-mail: rahimzad@aut.a