Impact of Pyrotechnics over the Architectonic Heritage

Directory of Open Access Journals (Sweden)

Angel T. Lloret

2017-01-01

Full Text Available The use of pyrotechnics near to the historical heritage such as walls, facades, church, or fortifications of a city is nowadays a topic of discussion. There is not a clear legislation about the use of pyrotechnics near to these buildings and how they can be affected by the expansive wave generated by the use of harquebusiers, fireworks, and cannons during the simulation of a battle. For this reason, this paper presents some practical tests that measure the vibroacoustic effect when these types of pyrotechnics are used near to the architectonical heritage. In order to collect these data, we have used several sound level meters and accelerometers placed on two different scenarios. The first one was placed near to the beach and the other one was placed in a building of a narrow alley. The tests were carried out during the festival of Moors and Christians of Villajoyosa (Spain which is a famous festival. Along these tests, we reproduce the worse cases that may affect the building, using harquebusiers shots, fireworks, and cannons shots. Results show that the house placed near to the beach does not suffer important vibroacoustic impacts. However, the old building placed in the alley is very affected.

Optimized Analytical Method to Determine Gallic and Picric Acids in Pyrotechnic Samples by Using HPLC/UV (Reverse Phase)

International Nuclear Information System (INIS)

Garcia Alonso, S.; Perez Pastor, R. M.

2013-01-01

A study on the optimization and development of a chromatographic method for the determination of gallic and picric acids in pyrotechnic samples is presented. In order to achieve this, both analytical conditions by HPLC with diode detection and extraction step of a selected sample were studied. (Author)

Non-destructive visualization of linear explosive-induced Pyroshock using phase arrayed laser-induced shock in a space launcher composite

International Nuclear Information System (INIS)

Jang, Jae Kyeong; Lee, Jung Ryul

2015-01-01

Separation mechanism of Space launch vehicles are used in various separation systems and pyrotechnic devices. The operation of these pyrotechnic devices generates Pyroshock that can cause failures in electronic components. The prediction of high frequency structural response, especially the shock response spectrum (SRS), is important. This paper presents a non-destructive visualization and simulation of linear explosive-induced Pyroshock using phase arrayed Laser-induced shock. The proposed method includes a laser shock test based on laser beam and filtering zone conditioning to predict the SRS of Pyroshock. A ballistic test based on linear explosive and non-contact Laser Doppler Vibrometers and a nondestructive Laser shock measurement using laser excitation and several PZT sensors, are performed using a carbon composite sandwich panel. The similarity of the SRS of the conditioned laser shock to that of the real explosive Pyroshock is evaluated with the Mean Acceleration Difference. The average of MADs over the two training points was 33.64%. And, MAD at verification point was improved to 31.99%. After that, experimentally found optimal conditions are applied to any arbitrary points in laser scanning area. Finally, it is shown that linear explosive-induced real Pyroshock wave propagation can be visualized with high similarity based on the proposed laser technology. (paper)

76 FR 37876 - Hours of Service (HOS) of Drivers; Renewal of American Pyrotechnics Association (APA) Exemption...

Science.gov (United States)

2011-06-28

...-28043] Hours of Service (HOS) of Drivers; Renewal of American Pyrotechnics Association (APA) Exemption... announces the renewal of the exemption of specified members of the American Pyrotechnics Association (APA... of this exemption in effect, designated APA-member motor carriers will maintain a level of safety...

76 FR 30232 - Hours of Service (HOS) of Drivers; Application of American Pyrotechnics Association (APA) for...

Science.gov (United States)

2011-05-24

...-28043] Hours of Service (HOS) of Drivers; Application of American Pyrotechnics Association (APA) for... American Pyrotechnics Association (APA) has applied for a limited exemption from FMCSA's regulation that... exemption would apply solely to the operation of CMVs by 9 designated APA-member motor carriers in...

77 FR 38378 - Hours of Service (HOS) of Drivers; Revision of Exemption; American Pyrotechnics Association (APA)

Science.gov (United States)

2012-06-27

...-28043] Hours of Service (HOS) of Drivers; Revision of Exemption; American Pyrotechnics Association (APA... Pyrotechnics Association (APA) that were granted an exemption from FMCSA's prohibition on driving commercial...-July 8, inclusive, in 2011 and 2012. The exemption covered renewal of 53 APA-member motor carriers and...

76 FR 37880 - Hours of Service (HOS) of Drivers; Granting of Exemption; American Pyrotechnics Association (APA)

Science.gov (United States)

2011-06-28

...-28043] Hours of Service (HOS) of Drivers; Granting of Exemption; American Pyrotechnics Association (APA... exemption from the American Pyrotechnics Association (APA) on behalf of 9 member motor carriers seeking... such exemption'' (49 U.S.C. 31315(b)(1)). The initial APA application for waiver or exemption relief...

Towards decomposition of live chemical agents by pyrotechnic mixtures

NARCIS (Netherlands)

Bouma, R.H.B.; Noort, D.

2012-01-01

The aim of this study is to contribute to improved EOD neutralisation techniques against improvised explosive devices (IEDs) containing chemical agents. The decomposition of dimethyl methylphosphonate (DMMP) when exposed to a burning aluminum/potassium nitrate pyrotechnic mixture is studied

Pyrotechnic Smoke Compositions Containing Boron Carbide

Science.gov (United States)

2012-06-10

smoke. Experimentation and thermodynamic modeling were used in conjunction to develop the compositions which were then evaluated both visually and by...fuel to produce thick clouds of white smoke. Experimentation and thermodynamic modeling were used in conjunction to develop the compositions which...Transmittance-based measurements may be used to quantify the effectiveness of screening smokes. The Beer -Lambert law is used to define the figures of merit

Low hygroscopicity of ambient fresh carbonaceous aerosols from pyrotechnics smoke

Science.gov (United States)

Carrico, Christian M.; Gomez, Samantha L.; Dubey, Manvendra K.; Aiken, Allison C.

2018-04-01

Pyrotechnics (fireworks) displays are common for many cultures worldwide, with Independence Day celebrations occurring annually on July 4th as the most notable in the U.S. Given an episodic nature, fireworks aerosol properties are poorly characterized. Here we report observations of optical properties of fresh smoke emissions from Independence Day fireworks smoke sampled at Los Alamos National Laboratory, New Mexico U.S.A. on 4-5 July 2016. Aerosol optical properties were measured with a photoacoustic extinctiometer (PAX, DMT, Inc., Model 870 nm) at low RH laboratory testing with ground-level sparklers showed that pyrotechnics smoke can generate a strong hygroscopic response, however. As confirmed with chemical analysis, the chemistry of the fireworks was key to defining the hygroscopic response. Sparkler smoke was dominated by salt species such as hygroscopic potassium chloride while it lacked the black powder explosives in aerial fireworks that contribute organic and elemental carbon to its non-hygroscopic smoke.

Combustion of powdery tungsten in pyrotechnic mixtures

International Nuclear Information System (INIS)

Ivanov, G.V.; Reshetov, A.A.; Viktorenko, A.M.; Surkov, V.G.; Karmadonov, L.N.

1982-01-01

The basic regularities of tungsten burning (powder 2-5 μm) with oxidizers most typical for pyrotechnics: nitrates, lead and barium peroxides (powder, 2-8 μm) and potassium perchlorate (powder, 2-8 μm) are studied. Dependences of burning rate as a function of pressure and ratio of components are established. It is supposed that tungsten burning in mixtures with the mentioned nitrates is a complex and multistage process the rate of which is determined by tungsten dissolution in nitrate melts. Analysis of burning products using available methods is complex

Laser-generated shock wave attenuation aimed at microscale pyrotechnic device design

Directory of Open Access Journals (Sweden)

Hyeonju Yu

2016-05-01

Full Text Available To meet the rising demand for miniaturizing the pyrotechnic device that consists of donor/acceptor pair separated by a bulkhead or a thin gap, the shock initiation sensitivity in the microscale gap test configuration is investigated. For understanding the shock attenuation within a gap sample (304 stainless steel thickness of 10∼800 μm, the laser-generated shock wave in water confinement is adopted. The shock properties are obtained from the free surface velocity by making use of a velocity interferometer system for any reflector (VISAR. Analytical models for plasma generation in a confined geometry and for evolution and decay of shock waves during the propagation are considered. The shape and amplitude of the laser-driven initial pressure load and its attenuation pattern in the gap are effectively controlled for targeting the microscale propagation distance and subsequent triggering pressure for the acceptor charge. The reported results are important in the precise controlling of the shock strength during the laser initiation of microscale pyrotechnic devices.

Pyrotechnical production of labelled aerosols and their use in the ground atmosphere

International Nuclear Information System (INIS)

Kuehn, W.K.G.; Alps, W.

1977-01-01

As the emission of radioactive substances in the atmosphere is only allowed for a few short-lined radionuclides, the possibility of producing aerosols pyrotechnically and to simultaneously label them with easily activated tracers was investigated. It has the following advantages: 1) The activation analysis guarantees a high detection sensitivity with a tracer element of large cross section. 2) There is no danger to the environment due to radioactivity during testing. 3) In general, there are no limits to the amount of indicator substance used. 4) The pyrotechnically produced aerosol can be used at any position of the atmosphere whereby line sources, point sources and pulse sources can be produced with the generator. The generator can be shot by a signal pistol to the desired height in order to label harmful substances or other (emission) points as well. 5) The source is extremely mobile due to the small measurements and uncomplicated construction of the generator. (orig./RW) [de

A survey of combustible metals, thermites, and intermetallics for pyrotechnic applications

Energy Technology Data Exchange (ETDEWEB)

Fischer, S.H.; Grubelich, M.C.

1996-08-01

Thermite mixtures, intermetallic reactants, and metal fuels have long been used in pyrotechnics. Advantages include high energy density, impact insensitivity, high combustion temperature, and a wide range of gas production. They generally exhibit high temperature stability and possess insensitive ignition properties. This paper reviews the applications, benefits, and characteristics of thermite mixtures, intermetallic reactants, and metal fuels. 50 refs, tables.

Illicit utilization of arsenic compounds in pyrotechnics? An analysis of the suspended particle emission during Vienna’s New Year fireworks

International Nuclear Information System (INIS)

Sterba, J.H.; Georg Steinhauser; Fritz Grass

2013-01-01

In the course of an investigation of an electrostatic precipitation technique as a sampling method for airborne dust particles, elevated concentrations of As were found in the data collected during New Years Eve celebrations in Vienna. The original study confirmed the applicability of the new sampling device as a useful sampling method, showing elevated values for the elements Na, Mg, Al, Si, S, K, Cu, As, Br, Rb, Sr, Sb, Te and Ba, all associated with the use of pyrotechnics. The measured values for As could not be explained as a impurity in some other substances used. Thus, several unburned pyrotechnic products were investigated to find the source of As in the dust collected. The results showed only one product with higher than expected As contents (1.4 μg g -1 ), leading to the assumption of intentional - but illicit - use of arsenic compounds in pyrotechnics as a colouring agent for the production of blue light. (author)

Ignition and combustion of pyrotechnics at low pressures and at temperature extremes

Directory of Open Access Journals (Sweden)

Clive Woodley

2017-06-01

Full Text Available Rapid and effective ignition of pyrotechnic countermeasure decoy flares is vitally important to the safety of expensive military platforms such as aircraft. QinetiQ is conducting experimental and theoretical research into pyrotechnic countermeasure decoy flares. A key part of this work is the development and application of improved models to increase the understanding of the ignition processes occurring for these flares. These models have been implemented in a two-dimensional computational model and details are described in this paper. Previous work has conducted experiments and validated the computational model at ambient temperature and pressure. More recently the computational model has been validated at pressures down to that equivalent to 40,000 feet but at ambient temperature (∼290 K. This paper describes further experimental work in which the ignition delays of the priming material in inert countermeasure decoy flares were determined for pressures down to 40,000 feet and at temperature extremes of −40 °C and 100 °C. Also included in this paper is a comparison of the measured and predicted ignition delays at low pressures and temperature extremes. The agreement between the predicted and measured ignition delays is acceptable.

Behaviour modelling of two aluminas in divergent spherical pyrotechnical experiments

International Nuclear Information System (INIS)

Malaise, F.; Tranchet, J.Y.; Collombet, F.

1997-01-01

Two pure aluminas of different characteristics have been subjected to the propagation of a longitudinal divergent spherical shock wave through pyrotechnical experiments. An approach combining a phenomenological analysis and numerical 1D-calculations is proposed to study the behaviour of these aluminas submitted to that type of wave loading. The modelling, proposed in a previous paper, is refined and gives satisfying experimentation-calculation correlations. An analysis of the influence exerted by the various encountered phenomena (plastic activity, pore closure, microcracking) is performed. The significant consequence of the activation of damage with an extension criterion is also underlined. (orig.)

78 FR 26690 - Hours of Service (HOS) of Drivers; Application for Renewal and Expansion of American Pyrotechnics...

Science.gov (United States)

2013-05-07

... Association (APA) Exemption From the 14-Hour Rule During Independence Day Celebrations AGENCY: Federal Motor... exemption; request for comments. SUMMARY: The American Pyrotechnics Association (APA) has requested a renewal of its exemption for 48 APA member-companies from FMCSA's regulation that drivers of commercial...

Composite Repair System, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — GTL has developed an innovative composite repair methodology known as the Composite Repair System (CRS). In this phase I effort, CRS is being developed for the...

On Inclusion-Matrix Interfacial Stresses in Composites Containing Phase-Transforming Phases

International Nuclear Information System (INIS)

Wang, Y.-C.; Ko, C.-C.

2010-01-01

Recent development in composites containing phase-transforming particles, such as vanadium dioxide or barium titanate, reveals the overall stiffness and viscoelastic damping of the composites may be unbounded. Negative stiffness is induced from phase transformation predicted by the Landau phase transformation theory. Although this unbounded phenomenon is theoretically supported with the composite homogenization theory, detailed stress analyses of the composites are still lacking. In this work, we analyze the two-dimensional plane stress elasticity problem of a square plate containing a circular inclusion, under the assumption that the Young's modulus of the inclusion is negative. Assumption of negative stiffness is a priori in the present analysis. A static loading condition is adopted to estimate the effective modulus of the composites by the ratio of applied stress to averaged strain on the loading edges. It is found that the interfacial stresses between the circular inclusion and matrix increase dramatically when the negative stiffness is so tuned that overall stiffness is unbounded. Furthermore, it is found that stress distributions in the inclusion are not uniform, contrary to Eshelby's theorem, which states, for two-phase, infinite composites, the inclusion's stress distribution is uniform when the shape of the inclusion has higher symmetry than an ellipse. The rationale for this nonuniform stress distributions is due to nonlocal effects induced from negative stiffness.

Pyrotechnic countermeasures: IV. Radiometric performance of a sulphur-based Flare composition

Energy Technology Data Exchange (ETDEWEB)

Koch, Ernst-Christian [NATO Munitions Safety Information Analysis Center (MSIAC), Brussels (Belgium)

2008-10-15

Radiometric performance of a sulphur-based flare composition has been investigated. Composition comprising sulphur, potassium perchlorate and antimony sulphide has acceptable band ratio but an order of magnitude weaker spectral efficiency than typical carbon-based compositions. The use of other sulphur compounds with potential for increased performance is discussed. For part III see Ref. [1]. (Abstract Copyright [2008], Wiley Periodicals, Inc.)

The development of laser ignited deflagration-to-detonation transition (DDT) detonators and pyrotechnic actuators

Energy Technology Data Exchange (ETDEWEB)

Merson, J.A.; Salas, F.J.; Harlan, J.G.

1993-11-01

The use of laser ignited explosive components has been recognized as a safety enhancement over existing electrical explosive devices (EEDs). Sandia has been pursuing the development of optical ordnance for many years with recent emphasis on developing optical deflagration-to-detonation (DDT) detonators and pyrotechnic actuators. These low energy optical ordnance devices can be ignited with either a semiconductor diode laser, laser diode arrays or a solid state rod laser. By using a semiconductor laser diode, the safety improvement can be made without sacrificing performance since the input energy required for the laser diode and the explosive output are similar to existing electrical systems. The use of higher powered laser diode arrays or rod lasers may have advantages in fast DDT applications or lossy optical environments such as long fiber applications and applications with numerous optical connectors. Recent results from our continued study of optical ignition of explosive and pyrotechnic materials are presented. These areas of investigation can be separated into three different margin categories: (1) the margin relative to intended inputs (i.e. powder performance as a function of laser input variation), (2) the margin relative to anticipated environments (i.e. powder performance as a function of thermal environment variation), and (3) the margin relative to unintended environments (i.e. responses to abnormal environments or safety).

Using the Chemistry of Fireworks to Engage Students in Learning Basic Chemical Principles: A Lesson in Eco-Friendly Pyrotechnics

Science.gov (United States)

Steinhauser, Georg; Klapotke, Thomas M.

2010-01-01

Fascination with fireworks and pyrotechnics can be used for educational purposes. Several aspects of pyrochemistry such as redox reactions, flame colors, or the theory of combustion can be incorporated in the curriculum to illustrate some basic chemical principles, guaranteeing a lesson that will be engaging and memorable. Beyond classic…

Nuclear prehistory influence on irradiated metallic iron phase composition

International Nuclear Information System (INIS)

Alekseev, I.E.

2007-01-01

With application of different Moessbauer spectroscopy applications the phase composition of metallic iron after irradiation by both neutrons and charged particles were studied. Irradiation conditions, method of targets examination and phase composition of samples after irradiation were presented in tabular form. It is shown, that phase composition of irradiated metal is defined by nuclear prehistory. So, in a number of cases abnormals (stabilization of high- and low-temperature structural phases of iron at room temperature after irradiation end) were revealed

Implications of Dynamic Pressure Transducer Mounting Variations on Measurements in Pyrotechnic Test Apparatus

Science.gov (United States)

Dibbern, Andreas; Crisafulli, Jeffrey; Hagopia, Michael; McDougle, Stephen H.; Saulsberry, Regor L.

2009-01-01

Accurate dynamic pressure measurements are often difficult to make within small pyrotechnic devices, and transducer mounting difficulties can cause data anomalies that lead to erroneous conclusions. Delayed initial pressure response followed by data ringing has been observed when using miniaturized pressure transducer mounting adapters required to interface transducers to small test chambers. This delayed pressure response and ringing, combined with a high data acquisition rate, has complicated data analysis. This paper compares the output signal characteristics from different pressure transducer mounting options, where the passage distance from the transducer face to the pyrotechnic chamber is varied in length and diameter. By analyzing the data and understating the associated system dynamics, a more realistic understanding of the actual dynamic pressure variations is achieved. Three pressure transducer mounting configurations (elongated, standard, and face/flush mount) were simultaneously tested using NASA standard initiators in closed volume pressure bombs. This paper also presents results of these pressure transducer mounting configurations as a result of a larger NASA Engineering and Safety Center pyrovalve test project. Results from these tests indicate the improved performance of using face/flush mounted pressure transducers in this application. This type of mounting improved initial pressure measurement response time by approximately 19 s over standard adapter mounting, eliminating most of the lag time; provided a near step-function type initial pressure increase; and greatly reduced data ringing in high data acquisition rate systems. The paper goes on to discuss other issues associated with the firing and instrumentation that are important for the tester to understand.

High-Nitrogen-Based Pyrotechnics: Longer- and Brighter-Burning, Perchlorate-Free, Red-Light Illuminants for Military and Civilian Applications

Science.gov (United States)

2011-01-01

combustion of these materials. To address the aforementioned perchlorate issues, an effort was initiated by ARDEC to remove potassium per- chlorate ...with acceptable burn times for pyrotechnic applications by using potassium nitrate– amorphous boron–crystalline boron/boron carbide–epoxy binder mixtures...3,4] Moreover, it was discovered by ARDEC that a potassium nitrate–boron carbide–epoxy binder mix- ture alone was able to generate suitable green

A DSC analysis of inverse salt-pair explosive composition

Energy Technology Data Exchange (ETDEWEB)

Babu, E. Suresh; Kaur, Sukhminder [Central Forensic Science Laboratory, Explosives Division, Ramanthapur, Hyderabad 500013 (India)

2004-02-01

Alkali nitrates are used as an ingredient in low explosive compositions and pyrotechnics. It has been suggested that alkali nitrates can form inverse salt-pair explosives with the addition of ammonium chloride. Therefore, the thermal behavior of low explosive compositions containing potassium nitrate mixed with ammonium chloride has been studied using Differential Scanning Calorimetry (DSC). Results provide information about the ion exchange reaction between these two chemical substances and the temperature region at which the formation of a cloud of salt particles of potassium chloride takes place. Furthermore, the addition of ammonium chloride quenches the flame of deflagrating compositions and causes the mixture to undergo explosive decomposition at relatively low temperatures. (Abstract Copyright [2004], Wiley Periodicals, Inc.)

Searching for Next Single-Phase High-Entropy Alloy Compositions

Directory of Open Access Journals (Sweden)

David E. Alman

2013-10-01

Full Text Available There has been considerable technological interest in high-entropy alloys (HEAs since the initial publications on the topic appeared in 2004. However, only several of the alloys investigated are truly single-phase solid solution compositions. These include the FCC alloys CoCrFeNi and CoCrFeMnNi based on 3d transition metals elements and BCC alloys NbMoTaW, NbMoTaVW, and HfNbTaTiZr based on refractory metals. The search for new single-phase HEAs compositions has been hindered by a lack of an effective scientific strategy for alloy design. This report shows that the chemical interactions and atomic diffusivities predicted from ab initio molecular dynamics simulations which are closely related to primary crystallization during solidification can be used to assist in identifying single phase high-entropy solid solution compositions. Further, combining these simulations with phase diagram calculations via the CALPHAD method and inspection of existing phase diagrams is an effective strategy to accelerate the discovery of new single-phase HEAs. This methodology was used to predict new single-phase HEA compositions. These are FCC alloys comprised of CoFeMnNi, CuNiPdPt and CuNiPdPtRh, and HCP alloys of CoOsReRu.

Method of non-interacting thermodynamic calculation of binary phase diagrams containing p disordered phases with variable composition and q phases with constant composition at (p, q) ≤ 10

International Nuclear Information System (INIS)

Udovskij, A.L.; Karpushkin, V.N.; Nikishina, E.A.

1991-01-01

Method of non-interacting thermodynamic calculation of state diagram of binary systems contacting p disordered phases with variable composition and q phases with constant composition for (p, q) ≤ 10 case is developed. Determination of all possible solutions of phase equilibrium equations is realized in the method. Certain application examples of computer-realized method of T-x thermodynamic calculation using PC for Cr-W, Ni-W, Ni-Al, Ni-Re binary systems are given

Oxygen exchange and transport in dual phase ceramic composite electrodes.

Science.gov (United States)

Druce, John; Téllez, Helena; Ishihara, Tatsumi; Kilner, John A

2015-01-01

Composites consisting of a perovskite-based electronic or mixed conductor with a fluorite-structured ionic conductor are often used as electrodes in solid oxide electrochemical energy conversion devices. After sintering the materials, there is often evidence for inter-reaction between the two phases, or inter-diffusion of cations or impurities between the two phases. We studied the (18)O exchange properties of a composite consisting of CGO and LSCF in a 50 : 50 ratio. High resolution ToF-SIMS mapping reveals that the (18)O fraction at the very outer surface of grains of the CGO phase is much higher than expected from D* and k* values for the single-phase parent material. Surface compositional analysis by ToF-SIMS and low energy ion scattering (LEIS) spectroscopy suggests that the surfaces of the CGO grains in the composite do not show the impurities which typically segregate to the surface in single-phase CGO. Thus, the "cleaning" of impurities from the CGO surface by dissolution into the perovskite phase may be one explanation for the apparent enhanced surface exchange for CGO in these composites.

Progress in Dual (Piezoelectric-Magnetostrictive Phase Magnetoelectric Sintered Composites

Directory of Open Access Journals (Sweden)

Rashed Adnan Islam

2012-01-01

Full Text Available The primary aims of this review article are (a to develop the fundamental understanding of ME behavior in perovskite piezoelectric-spinel magnetostrictive composite systems, (b to identify the role of composition, microstructural variables, phase transformations, composite geometry, and postsintering heat treatment on ME coefficient, and (c to synthesize, characterize, and utilize the high ME coefficient composite. The desired range of ME coefficient in the sintered composite is 0.5–1 V/cm⋅Oe. The studies showed that the soft piezoelectric phase quantified by smaller elastic modulus, large grain size of piezoelectric phase (~1 μm, and layered structures yields higher magnitude of ME coefficient. It is also found that postsintering thermal treatment such as annealing and aging alters the magnitude of magnetization providing an increase in the magnitude of ME coefficient. A trilayer composite was synthesized using pressure-assisted sintering with soft phase [0.9 PZT–0.1 PZN] having grain size larger than 1 μm and soft ferromagnetic phase of composition Ni0.8Cu0.2Zn0.2Fe2O4 [NCZF]. The composite showed a high ME coefficient of 412 and 494 mV/cm⋅Oe after sintering and annealing, respectively. Optimized ferrite to PZT thickness ratio was found to be 5.33, providing ME coefficient of 525 mV/cm⋅Oe. The ME coefficient exhibited orientation dependence with respect to applied magnetic field. Multilayering the PZT layer increased the magnitude of ME coefficient to 782 mV/cm⋅Oe. Piezoelectric grain texturing and nanoparticulate assembly techniques were incorporated with the layered geometry. It was found that with moderate texturing, d33 and ME coefficient reached up to 325 pC/N and 878 mV/cm⋅Oe, respectively. Nanoparticulate core shell assembly shows the promise for achieving large ME coefficient in the sintered composites. A systematic relationship between composition, microstructure, geometry, and properties is

Optimized Analytical Method to Determine Gallic and Picric Acids in Pyrotechnic Samples by Using HPLC/UV (Reverse Phase); Optimizacion del Metodo Analitico mediante HPLC/UV Operando en Fase Inversa para la Determinacion de Acido Galico y Acido Picrico en Muestras de Origen Pirotecnico

Energy Technology Data Exchange (ETDEWEB)

Garcia Alonso, S.; Perez Pastor, R. M.

2013-10-01

A study on the optimization and development of a chromatographic method for the determination of gallic and picric acids in pyrotechnic samples is presented. In order to achieve this, both analytical conditions by HPLC with diode detection and extraction step of a selected sample were studied. (Author)

Thermal decomposition of phase-stabilised ammonium nitrate (PSAM), HTPB based propellants. The effect of iron(III)oxide burning-rate catalyst

NARCIS (Netherlands)

Carvalheira, P.; Gadiot, G.M.H.J.L.; Klerk, W.P.C. de

1995-01-01

Phase-stabilised ammonium nitrate (PSAN) and hydroxyl-terminated polybutadiene (HTPB) are the main ingredients of propellants used with success in some pyrotechnic igniter components of the VULCAIN liquid rocket engine for the ARIANE 5. Small amounts of selected additives play an important role in

Microstructure characterization of multi-phase composites and utilization of phase change materials and recycled rubbers in cementitious materials

Science.gov (United States)

Meshgin, Pania

2011-12-01

This research focuses on two important subjects: (1) Characterization of heterogeneous microstructure of multi-phase composites and the effect of microstructural features on effective properties of the material. (2) Utilizations of phase change materials and recycled rubber particles from waste tires to improve thermal properties of insulation materials used in building envelopes. Spatial pattern of multi-phase and multidimensional internal structures of most composite materials are highly random. Quantitative description of the spatial distribution should be developed based on proper statistical models, which characterize the morphological features. For a composite material with multi-phases, the volume fraction of the phases as well as the morphological parameters of the phases have very strong influences on the effective property of the composite. These morphological parameters depend on the microstructure of each phase. This study intends to include the effect of higher order morphological details of the microstructure in the composite models. The higher order statistics, called two-point correlation functions characterize various behaviors of the composite at any two points in a stochastic field. Specifically, correlation functions of mosaic patterns are used in the study for characterizing transport properties of composite materials. One of the most effective methods to improve energy efficiency of buildings is to enhance thermal properties of insulation materials. The idea of using phase change materials and recycled rubber particles such as scrap tires in insulation materials for building envelopes has been studied.

The Theoretical Basis of the Concept of Using the Controlled Pyrotechnical Reaction Method as an Energy Source in Transportation from the Sea Bed

Directory of Open Access Journals (Sweden)

Wiktor Filipek

2017-12-01

Full Text Available In recent years we have observed the global growing interest in undersea exploitation of mineral deposits. Research on various concepts of operating systems on the seabed has been conducted, where different methods of transporting excavated material from the bottom to the surface are used. Great depths, where there are the most interesting resources (eg. IOM lot for the Clarion-Clipperton 4500 m set very high technical and technological demands which results in intensive search for solutions. The authors of the paper want to explain the concept of the use of pyrotechnic materials for transportation in the aquatic environment. The presented method is designed for the cyclic transport from great depths (less than 200 m from the seabed. The principle of operation of the relay unit is based on the change in the average density of the entire module which is inseparably connected with the force of buoyancy acting on the submerged body. Changing the density of the whole module to the given depth of immersion is strictly dependent on the amount of energy supplied to the system by a power source in the form of a controlled pyrotechnic reaction. However, during the ascent energy demand decreases. The problem of transport of spoil from depth not only boils down to such considerations as initiation of the process of ascent. One should also consider how to use the excess energy occurring during the movement of the object toward the surface. The authors of the paper present the concept of making the transport of cyclic depths (less than 200 m from the seabed taking into account the optimal use of energy from controlled pyrotechnic reaction.

Tethered Nanoparticle–Polymer Composites: Phase Stability and Curvature

KAUST Repository

Srivastava, Samanvaya; Agarwal, Praveen; Archer, Lynden A.

2012-01-01

different small-angle X-ray scattering signatures in comparison to phase-separated composites comprised of bare or sparsely grafted nanoparticles. A general diagram for the dispersion state and phase stability of polymer tethered nanoparticle-polymer

Ductile-phase toughening in V-V3Si in situ composites

International Nuclear Information System (INIS)

Henshall, G.; Strum, M.J.; Bewlay, B.P.; Sutliff, J.A.

1997-01-01

This article describes the room-temperature fracture behavior of ductile-phase-toughened V-V 3 Si in situ composites that were produced by arc melting (AM), cold-crucible induction melting (IM), and cold-crucible directional solidification (DS). Composites were produced containing a wide range of microstructures, interstitial impurity contents, and volume fractions of the ductile V-Si solid solution phase, denoted (V). The fracture toughness of these composites generally increases as the volume fraction of (V) increases, but is strongly influenced by the microstructure, the mechanical properties of the component phases, and the crystallographic orientation of the (V) phase with respect to the maximum principal stress direction. For eutectic composites that have a (V) volume fraction of about 50 pct, the fracture toughness increases with decreasing ''''effective'''' interstitial impurity concentration, [I] = [N] + 1.33 [O] + 9 [H]. As [I] decreases from 1,400 ppm (AM) to 400 ppm (IM), the fracture toughness of the eutectic composites increases from 10 to 20 MPa √m. Further, the fracture toughness of the DS eutectic composites is greater when the crack propagation direction is perpendicular, rather than parallel, to the composite growth direction. These results are discussed in light of conventional ductile-phase bridging theories, which alone cannot fully explain the fracture toughness of V-Si in situ composites

Composition-microstructure-property relationships in dual phase bulk magnetoelectric composite

Science.gov (United States)

Islam, Rashed Adnan

The coexistence of coupled electrical and magnetic properties in the "magnetoelectric" material has led to the possibility of developing smarter and smaller electronic components. In order to make this possibility a reality, significant efforts are required to understand the science of magnetoelectric (ME) behavior and apply this understanding to develop higher sensitivity material. The primary aims of this thesis are to identify the role of composition, microstructural variables, composite geometry, texturing, post sintering heat treatment, and nanoscale assembly on ME coefficient. The overall objective is to synthesize, characterize and utilize a high ME coefficient composite. The desired range of ME coefficient in the sintered composite is more than 1.5 V/cm.Oe. At first, a piezoelectric composition in the system of Pb(Zr,Ti)O 3 - Pb[(Zn,Ni)1/3Nb2/3]O3 was designed and synthesized which has high energy density (d.g) parameter of 18456.2 x 10-15m2/N and high g constant of 83.1 V-m/N in order to use it as the matrix in piezoelectric---magnetostrictive composite. Secondly it was found that soft piezoelectric phase shows much better magnetoelectric response. The magnetoelectric coefficient for Pb(Zr 0.52Ti0.48)O3 - 15% Pb(Zn1/3Nb 2/3)O3 [PZT - 15 PZN] - 20% Ni0.8Zn 0.2Fe2O4 was found to be around 186 mV/cm.Oe. Thridly, soft magnetic phase with lower coercivity and higher magnetization was found to be suitable for high ME coefficient. Zinc doped Ni-ferrite has higher resistivity, permeability, magnetization and it was found that with increasing Zn concentration the ME coefficient increases exhibiting maxima near 30 at% Zn (138 mV/cm.Oe). Fourthly, if the connectivity was changed from (0-3) to (2-2) which is a bilayer geometry, improved piezoelectric (d33 ˜ 80 pC/N), ferroelectric (polarization = 60 muC/cm2), magnetization (25 emu/gm) and lower coercive field (2.8 Oe) were measured. The bilayer shows an enhancement of 67% increase in ME coefficient compared to bulk

Literature survey on phase composition of hardened cement paste containing fly ash

International Nuclear Information System (INIS)

Otsuka, Taku; Yamamoto, Takeshi

2015-01-01

The purpose of this literature survey is to collect the knowledge on the effect of fly ash in hardened cement paste and the information about evaluation of physicochemical performance based on phase composition of hardened cement paste. The performance of hardened cement paste containing fly ash is affected by the property of fly ash, hydration of cement and pozzolanic reaction of fly ash. Some properties of fly ash such as density and chemical composition are reflected in phase composition, showing the progress of cement hydration and pozzolanic reaction. Therefore clarification of the relationship of phase composition and performance will lead to appropriate evaluation of the property of fly ash. The amount of pore, chemical shrinkage, pore solution, compressive strength, Young modulus and alkali silica reaction have relations to the phase composition of hardened cement paste. It is considered as future subject to clarify the relationship of phase composition and performance for various properties of fly ash. (author)

Microstructural effects of ductile phase toughening of Nb-Nb silicide composites

International Nuclear Information System (INIS)

Lewandowski, J.J.; Dimiduk, D.; Kerr, W.; Menddiratta, M.G.

1988-01-01

In the Nb-Si system, the terminal Nb phase and Nb 5 Si 3 phase are virtually immiscible up to approximately 2033k. This system offers the potential of producing composites consisting of a ductile refractory metal phase and a strong intermetallic phase. In-situ composites containing different volume fractions of the ductile Nb phase were produced via vacuum arc-casting. Microhardness testing as well as smooth bend bar testing was conducted at temperatures ranging from 298k to 1673k in an attempt to determine microstructural effects on the yield strength and smooth bar fracture strength. Notched bend specimens were similarly tested to determine the effects of the ductile phase (i.e. Nb) on enhancing the notched bend toughness. It is shown that Nb phase often behaves in a ductile manner during testing, thereby toughening the in-situ composite. The mechanism of toughening appears to be due to crack bridging

Size effect for phase stability on Au–Cd–Ag of phase boundary composition

International Nuclear Information System (INIS)

Matsuoka, Yuki; Suzuki, Keiko; Kudo, Natsuko

2013-01-01

Highlights: ► Size and heat treatment effects of phase boundary composition Au 52.5−x Cd 47.5 Ag x were studied. ► The transformation temperature T 0 increases by quench. It is investigated that disordering of atoms and lattice defects make β-phase unstable. ► Downsizing sample decreased T 0 in β-phase, showed a tendency of increase in coexistent phase. ► Downsizing is supposed to make difficult nucleation for martensitic transformation. ► Increasing of surface ratio by downsizing of powder sample is estimated to make easy to transform from unstable β-phase to martensite phase. -- Abstract: Size and heat treatment effects on martensitic transformation of phase boundary composition Au 52.5−x Cd 47.5 Ag x were studied. Au 52.5−x Cd 47.5 Ag x has coexistent phase of β-phase and α-phase of fcc structure at x > 42 at.%. The transformation temperature T 0 decreases as Au is substituted on Ag over phase boundary. T 0 increases by quench in both case of bulk and powder. This behavior is investigated that disordering of atoms and lattice defects make β-phase (L2 1 , B2 or bcc) unstable. Size effect was also inspected. Downsizing sample decreased the transformation temperature in β-phase. On the contrary, the transformation temperature of the coexistent phase showed a tendency of increase. Downsizing is supposed to make difficult nucleation for martensitic transformation because of reduction of β-phase ordered volume. Increasing of surface (disorder structure) ratio by downsizing of powder sample is estimated to make easy to transform from unstable β-phase to martensite phase

Tethered Nanoparticle–Polymer Composites: Phase Stability and Curvature

KAUST Repository

Srivastava, Samanvaya

2012-04-17

Phase behavior of poly(ethylene glycol) (PEG) tethered silica nanoparticles dispersed in PEG hosts is investigated using small-angle X-ray scattering. Phase separation in dispersions of densely grafted nanoparticles is found to display strikingly different small-angle X-ray scattering signatures in comparison to phase-separated composites comprised of bare or sparsely grafted nanoparticles. A general diagram for the dispersion state and phase stability of polymer tethered nanoparticle-polymer composites incorporating results from this as well as various other contemporary studies is presented. We show that in the range of moderate to high grafting densities the dispersion state of nanoparticles in composites is largely insensitive to the grafting density of the tethered chains and chemistry of the polymer host. Instead, the ratio of the particle diameter to the size of the tethered chain and the ratio of the molecular weights of the host and tethered polymer chains (P/N) are shown to play a dominant role. Additionally, we find that well-functionalized nanoparticles form stable dispersions in their polymer host beyond the P/N limit that demarcates the wetting/dewetting transition in polymer brushes on flat substrates interacting with polymer melts. A general strategy for achieving uniform nanoparticle dispersion in polymers is proposed. © 2012 American Chemical Society.

Microencapsulated Phase Change Composite Materials for Energy Efficient Buildings

Science.gov (United States)

Thiele, Alexander

This study aims to elucidate how phase change material (PCM)-composite materials can be leveraged to reduce the energy consumption of buildings and to provide cost savings to ratepayers. Phase change materials (PCMs) can store thermal energy in the form of latent heat when subjected to temperatures exceeding their melting point by undergoing a phase transition from solid to liquid state. Reversibly, PCMs can release this thermal energy when the system temperature falls below their solidification point. The goal in implementing composite PCM walls is to significantly reduce and time-shift the maximum thermal load on the building in order to reduce and smooth out the electricity demand for heating and cooling. This Ph.D. thesis aims to develop a set of thermal design methods and tools for exploring the use of PCM-composite building envelopes and for providing design rules for their practical implementation. First, detailed numerical simulations were used to show that the effective thermal conductivity of core-shell-matrix composites depended only on the volume fraction and thermal conductivity of the constituent materials. The effective medium approximation reported by Felske (2004) was in very good agreement with numerical predictions of the effective thermal conductivity. Second, a carefully validated transient thermal model was used to simulate microencapsulated PCM-composite walls subjected to diurnal or annual outdoor temperature and solar radiation flux. It was established that adding microencapsulated PCM to concrete walls both substantially reduced and delayed the thermal load on the building. Several design rules were established, most notably, (i) increasing the volume fraction of microencapsulated PCM within the wall increases the energy savings but at the potential expense of mechanical properties [1], (ii) the phase change temperature leading to the maximum energy and cost savings should equal the desired indoor temperature regardless of the climate

Constitutive modeling of two-phase metallic composites with application to tungsten-based composite 93W–4.9Ni–2.1Fe

International Nuclear Information System (INIS)

Lu, W.R.; Gao, C.Y.; Ke, Y.L.

2014-01-01

The two-phase metallic composites, composed by the metallic particulate reinforcing phase and the metallic matrix phase, have attracted a lot of attention in recent years for their excellent material properties. However, the constitutive modeling of two-phase metallic composites is still lacking currently. Most used models for them are basically oriented for single-phase homogeneous metallic materials, and have not considered the microstructural evolution of the components in the composite. This paper develops a new constitutive model for two-phase metallic composites based on the thermally activated dislocation motion mechanism and the volume fraction evolution. By establishing the relation between microscopic volume fraction and macroscopic state variables (strain, strain rate and temperature), the evolution law of volume fraction during the plastic deformation in two-phase composites is proposed for the first time and introduced into the new model. Then the new model is applied to a typical two-phase tungsten-based composite – 93W–4.9Ni–2.1Fe tungsten heavy alloy. It has been found that our model can effectively describe the plastic deformation behaviors of the tungsten-based composite, because of the introduction of volume fraction evolution and the connecting of macroscopic state variables and micromechanical characteristics in the constitutive model. The model's validation by experimental data indicates that our new model can provide a satisfactory prediction of flow stress for two-phase metallic composites, which is better than conventional single-phase homogeneous constitutive models including the Johnson–Cook (JC), Khan–Huang–Liang (KHL), Nemat-Nasser–Li (NNL), Zerilli–Armstrong (ZA) and Voyiadjis–Abed (VA) models

Local structure, composition, and crystallization mechanism of a model two-phase “composite nanoglass”

Energy Technology Data Exchange (ETDEWEB)

Chattopadhyay, Soma; Shibata, Tomohiro [CSRRI-IIT, MRCAT, Sector 10, Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Kelly, S. D. [EXAFS Analysis, Bolingbrook, Illinois 60440 (United States); Balasubramanian, M. [Sector 20 XOR, Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Srinivasan, S. G.; Du, Jincheng; Banerjee, Rajarshi [Department of Materials Science and Engineering, University of North Texas, Denton, Texas 76203-5017 (United States); Ayyub, Pushan, E-mail: pushan@tifr.res.in [Department of Condensed Matter Physics and Materials Science, Tata Institute of Fundamental Research, Mumbai 400005 (India)

2016-02-14

We report a detailed study of the local composition and structure of a model, bi-phasic nanoglass with nominal stoichiometry Cu{sub 55}Nb{sub 45}. Three dimensional atom probe data suggest a nanoscale-phase-separated glassy structure having well defined Cu-rich and Nb-rich regions with a characteristic length scale of ≈3 nm. However, extended x-ray absorption fine structure analysis indicates subtle differences in the local environments of Cu and Nb. While the Cu atoms displayed a strong tendency to cluster and negligible structural order beyond the first coordination shell, the Nb atoms had a larger fraction of unlike neighbors (higher chemical order) and a distinctly better-ordered structural environment (higher topological order). This provides the first experimental indication that metallic glass formation may occur due to frustration arising from the competition between chemical ordering and clustering. These observations are complemented by classical as well as ab initio molecular dynamics simulations. Our study indicates that these nanoscale phase-separated glasses are quite distinct from the single phase nanoglasses (studied by Gleiter and others) in the following three respects: (i) they contain at least two structurally and compositionally distinct, nanodispersed, glassy phases, (ii) these phases are separated by comparatively sharp inter-phase boundaries, and (iii) thermally induced crystallization occurs via a complex, multi-step mechanism. Such materials, therefore, appear to constitute a new class of disordered systems that may be called a composite nanoglass.

Identification of sigma and OMEGA phases in AA2009/SiC composites

Energy Technology Data Exchange (ETDEWEB)

Rodrigo, P., E-mail: pilar.rodrigo@urjc.e [Departamento de Ciencia e Ingenieria de Materiales, Escuela Superior de Ciencias Experimentales y Tecnologia, Universidad Rey Juan Carlos, c/Tulipan s/n, 28933 Mostoles, Madrid (Spain); Poza, P.; Utrilla, M.V.; Urena, A. [Departamento de Ciencia e Ingenieria de Materiales, Escuela Superior de Ciencias Experimentales y Tecnologia, Universidad Rey Juan Carlos, c/Tulipan s/n, 28933 Mostoles, Madrid (Spain)

2009-08-12

The microstructure evolution during ageing treatment at 170 and 190 deg. C of AA2009/SiC composites, reinforced with 15 vol.% particulates and whiskers, was studied by transmission electron microscopy. Besides theta' and S' phases, the typical hardening precipitates on Al-Cu-Mg alloys, it was found the presence of OMEGA and sigma (Al{sub 5}Cu{sub 6}Mg{sub 2}) phases in the matrix. sigma phase was only found in the matrix of particulate composite, while OMEGA phase appeared in both. This phase has not been previously observed in Al matrix composites based on conventional Al-Cu-Mg alloys.

Study on paraffin/expanded graphite composite phase change thermal energy storage material

International Nuclear Information System (INIS)

Zhang Zhengguo; Fang Xiaoming

2006-01-01

A paraffin/expanded graphite composite phase change thermal energy storage material was prepared by absorbing the paraffin into an expanded graphite that has an excellent absorbability. In such a composite, the paraffin serves as a latent heat storage material and the expanded graphite acts as the supporting material, which prevents leakage of the melted paraffin from its porous structure due to the capillary and surface tension forces. The inherent structure of the expanded graphite did not change in the composite material. The solid-liquid phase change temperature of the composite PCM was the same as that of the paraffin, and the latent heat of the paraffin/expanded graphite composite material was equivalent to the calculated value based on the mass ratio of the paraffin in the composite. The heat transfer rate of the paraffin/expanded graphite composite was obviously higher than that of the paraffin due to the combination with the expanded graphite that had a high thermal conductivity. The prepared paraffin/expanded graphite composite phase change material had a large thermal storage capacity and improved thermal conductivity and did not experience liquid leakage during its solid-liquid phase change

Spheroidization behavior of dendritic b.c.c. phase in Zr-based モ-phase composite

Directory of Open Access Journals (Sweden)

Sun Guoyuan

2013-03-01

Full Text Available The spheroidization behavior of the dendritic b.c.c. phase dispersed in a bulk metallic glass (BMG matrix was investigated through applying semi-solid isothermal processing and a subsequent rapid quenching procedure to a Zr-based モ-phase composite. The Zr-based composite with the composition of Zr56.2Ti13.8Nb5.0Cu6.9Ni5.6Be12.5 was prefabricated by a water-cooled copper mold-casting method and characterized by X-ray diffraction (XRD and scanning electron microscope (SEM. The results show that the composite consists of a glassy matrix and uniformly distributed fine dendrites of the モ-Zr solid solution with the body-centered-cubic (b.c.c. structure. Based on the differential scanning calorimeter (DSC examination results, and in view of the b.c.c. モ-Zr to h.c.p. メ-Zr phase transition temperature, a semi-solid holding temperature of 900 ìC was determined. After reheating the prefabricated composite to the semi-solid temperature, followed by an isothermal holding process at this temperature for 5 min, and then quenching the semi-solid mixture into iced-water; the two-phase microstructure composed of a BMG matrix and uniformly dispersed spherical b.c.c. モ-Zr particles with a high degree of sphericity was achieved. The present spheroidization transition is a thermodynamically autonomic behavior, and essentially a diffusion process controlled by kinetic factors; and the formation of the BMG matrix should be attributed to the rapid quenching of the semi-solid mixture as well as the large glass-forming ability of the remaining melt in the semi-solid mixture.

Phase-Separated Polyaniline/Graphene Composite Electrodes for High-Rate Electrochemical Supercapacitors.

Science.gov (United States)

Wu, Jifeng; Zhang, Qin'e; Zhou, An'an; Huang, Zhifeng; Bai, Hua; Li, Lei

2016-12-01

Polyaniline/graphene hydrogel composites with a macroscopically phase-separated structure are prepared. The composites show high specific capacitance and excellent rate performance. Further investigation demonstrates that polyaniline inside the graphene hydrogel has low rate performance, thus a phase-separated structure, in which polyaniline is mainly outside the graphene hydrogel matrix, can enhance the rate performance of the composites. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Phase composition of yttrium-doped zirconia ceramics

Energy Technology Data Exchange (ETDEWEB)

Hennig, Christoph; Scheinost, Andreas C. [Helmholtz-Zentrum Dresden-Rossendorf e.V., Dresden (Germany). Molecular Structures; Weiss, Stephan [Helmholtz-Zentrum Dresden-Rossendorf e.V., Dresden (Germany). Surface Processes; Ikeda-Ohno, Atsushi [Helmholtz-Zentrum Dresden-Rossendorf e.V., Dresden (Germany). Chemistry of the F-Elements; Gumeniuk, R. [Technische Univ. Bergakademie Freiberg (Germany). Inst. fuer Experimentelle Physik

2017-06-01

Ceramic material might be an alternative to borosilicate glass for the immobilization of nuclear waste. The crystallinity of ceramic material increases the corrosion resistance over several magnitudes in relation to amorphous glasses. The stability of such ceramics depend on several parameters, among them the crystal phase composition. A reliable quantitative phase analysis is necessary to correlate the macroscopic material properties with structure parameters. We performed a feasibility study based on yttrium-doped zirconia ceramics as analogue for trivalent actinides to ascertain that the nanosized crystal phases in zirconia ceramics can be reliably determined.

Novel Formulations of Phase Change Materials—Epoxy Composites for Thermal Energy Storage

Directory of Open Access Journals (Sweden)

Maria Elena Arce

2018-01-01

Full Text Available This research aimed to evaluate the thermal properties of new formulations of phase change materials (PCMs-epoxy composites, containing a thickening agent and a thermally conductive phase. The composite specimens produced consisted of composites fabricated using (a inorganic PCMs (hydrated salts, epoxy resins and aluminum particulates or (b organic PCM (paraffin, epoxy resins, and copper particles. Differential Scanning Calorimetry (DSC was used to analyze the thermal behavior of the samples, while hardness measurements were used to determine changes in mechanical properties at diverse PCM and conductive phase loading values. The results indicate that the epoxy matrix can act as a container for the PCM phase without hindering the heat-absorbing behavior of the PCMs employed. Organic PCMs presented reversible phase transformations over multiple cycles, an advantage that was lacking in their inorganic counterparts. The enthalpy of the organic PCM-epoxy specimens increased linearly with the PCM content in the matrix. The use of thickening agents prevented phase segregation issues and allowed the fabrication of specimens containing up to 40% PCM, a loading significantly higher than others reported. The conductive phase seemed to improve the heat transfer and the mechanical properties of the composites when present in low percentages (<10 wt %; however, given its mass, the enthalpy detected in the composites was reduced as their loading further increased. The conductive phase combination (PCM + epoxy resin + hardener + thickening agent presents great potential as a heat-absorbing material at the temperatures employed.

Microstructure and phase composition of sputter-deposited zirconia-yttria films

International Nuclear Information System (INIS)

Knoll, R.W.; Bradley, E.R.

1983-11-01

Thin ZrO 2 -Y 2 O 3 coatings ranging in composition from 3 to 15 mole % Y 2 O 3 were produced by rf sputter deposition. This composition range spanned the region on the equilibrium ZrO 2 -Y 2 O 3 phase diagram corresponding to partially stabilized zirconia (a mixture of tetragonal ZrO 2 and cubic solid solution). Microstructural characteristics and crystalline phase composition of as-deposited and heat treated films (1100 0 C and 1500 0 C) were determined by transmission electron microscopy (TEM) and by x-ray diffraction (XRD). Effects of substrate bias (0 approx. 250 volts), which induced ion bombardment of the film during growth, were also studied. The as-deposited ZrO 2 -Y 2 O 3 films were single phase over the composition range studied, and XRD data indicated considerable local atomic disorder in the lattice. Films produced at low bias contained intergranular voids, pronounced columnar growth, and porosity between columns. At high bias, the microstructure was denser, and films contained high compressive stress. After heat treatment, all deposits remained single phase, therefore a microstructure and precipitate distribution characteristic of toughened, partially stabilized zirconia appear to be difficult to achieve in vapor deposited zirconia coatings

Phase spectral composition of wind generated ocean surface waves

Digital Repository Service at National Institute of Oceanography (India)

Varkey, M.J.

A study of the composition of the phase spectra of wind generated ocean surface waves is carried out using wave records collected employing a ship borne wave recorder. It is found that the raw phase spectral estimates could be fitted by the Uniform...

Isotopic separation of nitrogen 15. Influence of the gaseous phase composition

International Nuclear Information System (INIS)

Lacoste, Germain; Routie, Rene; Mahenc, Jean

1977-01-01

A study has been made on the gas phase composition effect on the isotopic separation of nitrogen 15 for the two HNO 3 -NO and N 2 O 3 -NO systems. It was shown that the changes in composition of the gas phases could account for the increase in the overall separation; most accuracy, measurements of isotopic concentration along the separation column and of total enrichment exhibit how important are the reactions of oxydo-reduction between the two phases in such process [fr

Novel Formulations of Phase Change Materials-Epoxy Composites for Thermal Energy Storage.

Science.gov (United States)

Arce, Maria Elena; Alvarez Feijoo, Miguel Angel; Suarez Garcia, Andres; Luhrs, Claudia C

2018-01-26

This research aimed to evaluate the thermal properties of new formulations of phase change materials (PCMs)-epoxy composites, containing a thickening agent and a thermally conductive phase. The composite specimens produced consisted of composites fabricated using (a) inorganic PCMs (hydrated salts), epoxy resins and aluminum particulates or (b) organic PCM (paraffin), epoxy resins, and copper particles. Differential Scanning Calorimetry (DSC) was used to analyze the thermal behavior of the samples, while hardness measurements were used to determine changes in mechanical properties at diverse PCM and conductive phase loading values. The results indicate that the epoxy matrix can act as a container for the PCM phase without hindering the heat-absorbing behavior of the PCMs employed. Organic PCMs presented reversible phase transformations over multiple cycles, an advantage that was lacking in their inorganic counterparts. The enthalpy of the organic PCM-epoxy specimens increased linearly with the PCM content in the matrix. The use of thickening agents prevented phase segregation issues and allowed the fabrication of specimens containing up to 40% PCM, a loading significantly higher than others reported. The conductive phase seemed to improve the heat transfer and the mechanical properties of the composites when present in low percentages (material at the temperatures employed.

Novel Formulations of Phase Change Materials—Epoxy Composites for Thermal Energy Storage

Science.gov (United States)

Alvarez Feijoo, Miguel Angel

2018-01-01

This research aimed to evaluate the thermal properties of new formulations of phase change materials (PCMs)-epoxy composites, containing a thickening agent and a thermally conductive phase. The composite specimens produced consisted of composites fabricated using (a) inorganic PCMs (hydrated salts), epoxy resins and aluminum particulates or (b) organic PCM (paraffin), epoxy resins, and copper particles. Differential Scanning Calorimetry (DSC) was used to analyze the thermal behavior of the samples, while hardness measurements were used to determine changes in mechanical properties at diverse PCM and conductive phase loading values. The results indicate that the epoxy matrix can act as a container for the PCM phase without hindering the heat-absorbing behavior of the PCMs employed. Organic PCMs presented reversible phase transformations over multiple cycles, an advantage that was lacking in their inorganic counterparts. The enthalpy of the organic PCM-epoxy specimens increased linearly with the PCM content in the matrix. The use of thickening agents prevented phase segregation issues and allowed the fabrication of specimens containing up to 40% PCM, a loading significantly higher than others reported. The conductive phase seemed to improve the heat transfer and the mechanical properties of the composites when present in low percentages (phase combination (PCM + epoxy resin + hardener + thickening agent) presents great potential as a heat-absorbing material at the temperatures employed. PMID:29373538

Composition-Driven Phase Boundary and Piezoelectricity in Potassium-Sodium Niobate-Based Ceramics.

Science.gov (United States)

Zheng, Ting; Wu, Jiagang; Xiao, Dingquan; Zhu, Jianguo; Wang, Xiangjian; Lou, Xiaojie

2015-09-16

The piezoelectricity of (K,Na)NbO3 ceramics strongly depends on the phase boundary types as well as the doped compositions. Here, we systematically studied the relationships between the compositions and phase boundary types in (K,Na) (Nb,Sb)O3-Bi0.5Na0.5AO3 (KNNS-BNA, A=Hf, Zr, Ti, Sn) ceramics; then their piezoelectricity can be readily modified. Their phase boundary types are determined by the doped elements. A rhombohedral-tetragonal (R-T) phase boundary can be driven in the compositions range of 0.035≤BNH≤0.040 and 0.035≤BNZ≤0.045; an orthorhombic-tetragonal (O-T) phase boundary is formed in the composition range of 0.005≤BNT≤0.02; and a pure O phase can be only observed regardless of BNS content (≤0.01). In addition, the phase boundary types strongly affect their corresponding piezoelectricities. A larger d33 (∼440-450 pC/N) and a higher d33* (∼742-834 pm/V) can be attained in KNNS-BNA (A=Zr and Hf) ceramics due to the involvement of R-T phase boundary, and unfortunately KNNS-BNA (A=Sn and Ti) ceramics possess a relatively poor piezoelectricity (d33≤200 and d33*piezoelectricity and phase boundary types were also discussed. We believe that comprehensive research can design more excellent ceramic systems concerning potassium-sodium niobate.

Novel Formulations of Phase Change Materials—Epoxy Composites for Thermal Energy Storage

OpenAIRE

Maria Elena Arce; Miguel Angel Alvarez Feijoo; Andres Suarez Garcia; Claudia C. Luhrs

2018-01-01

This research aimed to evaluate the thermal properties of new formulations of phase change materials (PCMs)-epoxy composites, containing a thickening agent and a thermally conductive phase. The composite specimens produced consisted of composites fabricated using (a) inorganic PCMs (hydrated salts), epoxy resins and aluminum particulates or (b) organic PCM (paraffin), epoxy resins, and copper particles. Differential Scanning Calorimetry (DSC) was used to analyze the thermal behavior of the sa...

Enhancement of polar crystalline phase formation in transparent PVDF-CaF{sub 2} composite films

Energy Technology Data Exchange (ETDEWEB)

Lee, Sang Goo; Ha, Jong-Wook, E-mail: jongwook@krict.re.kr; Sohn, Eun-Ho; Park, In Jun; Lee, Soo-Bok

2016-12-30

Highlights: • The crystalline phase in transparent PVDF-CaF{sub 2} composite films was investigated. • CaF{sub 2} promoted the formation of polar crystalline phases in PVDF matrix. • Ordered γ-phase was obtained by thermal treatment of as-cast films at the vicinity of its melting temperature. - Abstract: We consider the influence of calcium fluoride (CaF{sub 2}) nanoparticles on the crystalline phase formation of poly(vinylidene fluoride) (PVDF) for the first time. The transparent PVDF-CaF{sub 2} composite films were prepared by casting on PET substrates using N,N-dimethylacetamide (DMAc) as a solvent. It was found that CaF{sub 2} promoted the formation of polar crystalline phase of PVDF in composites, whereas nonpolar α-phase was dominant in the neat PVDF film prepared at the same condition. The portion of polar crystalline phase increased in proportional to the weight fraction of CaF{sub 2} in the composite films up to 10 wt%. Further addition of CaF{sub 2} suppressed completely the α-phase formation. Polar crystalline phase observed in as-cast composite films was a mixture of β- and γ-polymorph structures. It was also shown that much ordered γ-phase could be obtained through thermal treatment of as-cast PVDF-CaF{sub 2} composite film at the temperatures above the melting temperature of the composite films, but below that of γ-phase.

State of the art of durability-performance evaluation of hardened cement based on phase compositions

International Nuclear Information System (INIS)

Kurashige, Isao; Imoto, Harutake; Yamamoto, Takeshi; Hironaga, Michihiko

2006-01-01

Upgrading durability-performance evaluation technique for concrete is urgently demanded in connection to its application to radio-active waste repository which needs ultra long-term durability. Common concrete structures also require an advanced method for minimizing the life-cycle cost. The purpose of this research is to investigate current problems and future tasks on durability-performance evaluation of hardened cement from the view point of phase composition. Although the phase composition of hardened cement has not fully been reflected to durability-performance evaluation, it influences concrete durability as well as its pore structure. This report reviews state of the art of the factors affecting phase composition, analytical and experimental evaluation techniques for phase composition, and durability-performance evaluation methods of hardened cement based on phase composition. (author)

No-Oven, No-Autoclave, Composite Processing, Phase II

Data.gov (United States)

National Aeronautics and Space Administration — Cornerstone Research Group Inc. (CRG) proposes to continue the efforts from the 2010 NASA SBIR Phase I topic X5.03, "No-Oven, No-Autoclave (NONA) Composite...

Negative Saturation Approach for Non-Isothermal Compositional Two-Phase Flow Simulations

NARCIS (Netherlands)

Salimi, H.; Wolf, K.H.; Bruining, J.

2011-01-01

This article deals with developing a solution approach, called the non-isothermal negative saturation (NegSat) solution approach. The NegSat solution approach solves efficiently any non-isothermal compositional flow problem that involves phase disappearance, phase appearance, and phase transition.

X-ray analysis of phase coexistence and electric poling processing in alkaline niobate-based compositions

International Nuclear Information System (INIS)

Fu Jian; Zuo Ruzhong; Liu Yi

2010-01-01

The characteristic and origin of two-phase coexistence and the content of each phase in typical alkaline niobate-based lead-free compositions were investigated through the refinement of X-ray diffraction peaks and the measurement of dielectric constant versus temperature curves. The diffuse nature of polymorphic phase transition has resulted in the coexistence of two ferroelectric phases within a wide composition and temperature range. As a result, the optimum piezoelectric properties appear in the composition rich in tetragonal phases and there is a remarkable poling temperature effect. Discussions on the difference between morphotropic phase boundary and polymorphic phase boundary were made in combination with the variation of electrical properties.

Speeding up compositional reservoir simulation through an efficient implementation of phase equilibrium calculation

DEFF Research Database (Denmark)

Belkadi, Abdelkrim; Yan, Wei; Moggia, Elsa

2013-01-01

Compositional reservoir simulations are widely used to simulate reservoir processes with strong compositional effects, such as gas injection. The equations of state (EoS) based phase equilibrium calculation is a time consuming part in this type of simulations. The phase equilibrium problem can....... Application of the shadow region method to skip stability analysis can further cut the phase equilibrium calculation time. Copyright 2013, Society of Petroleum Engineers....

Modeling two-phase ferroelectric composites by sequential laminates

International Nuclear Information System (INIS)

Idiart, Martín I

2014-01-01

Theoretical estimates are given for the overall dissipative response of two-phase ferroelectric composites with complex particulate microstructures under arbitrary loading histories. The ferroelectric behavior of the constituent phases is described via a stored energy density and a dissipation potential in accordance with the theory of generalized standard materials. An implicit time-discretization scheme is used to generate a variational representation of the overall response in terms of a single incremental potential. Estimates are then generated by constructing sequentially laminated microgeometries of particulate type whose overall incremental potential can be computed exactly. Because they are realizable, by construction, these estimates are guaranteed to conform with any material constraints, to satisfy all pertinent bounds and to exhibit the required convexity properties with no duality gap. Predictions for representative composite and porous systems are reported and discussed in the light of existing experimental data. (paper)

Sol-Gel Manufactured Energetic Materials

Science.gov (United States)

Simpson, Randall L.; Lee, Ronald S.; Tillotson, Thomas M.; Hrubesh, Lawrence W.; Swansiger, Rosalind W.; Fox, Glenn A.

2005-05-17

Sol-gel chemistry is used for the preparation of energetic materials (explosives, propellants and pyrotechnics) with improved homogeneity, and/or which can be cast to near-net shape, and/or made into precision molding powders. The sol-gel method is a synthetic chemical process where reactive monomers are mixed into a solution, polymerization occurs leading to a highly cross-linked three dimensional solid network resulting in a gel. The energetic materials can be incorporated during the formation of the solution or during the gel stage of the process. The composition, pore, and primary particle sizes, gel time, surface areas, and density may be tailored and controlled by the solution chemistry. The gel is then dried using supercritical extraction to produce a highly porous low density aerogel or by controlled slow evaporation to produce a xerogel. Applying stress during the extraction phase can result in high density materials. Thus, the sol-gel method can be used for precision detonator explosive manufacturing as well as producing precision explosives, propellants, and pyrotechnics, along with high power composite energetic materials.

Thermal performance study of form-stable composite phase change material with polyacrylic

Science.gov (United States)

Kee, Shin Yiing; Munusamy, Yamuna; Ong, Kok Seng; Chee, Swee Yong; Sanmuggam, Shimalaa

2017-04-01

Phase change material (PCM) is one of the most popular and widely used as thermal energy storage material because it is able to absorb and release a large amount of latent heat during a phase change process over a narrow temperature range. In this work, the form-stable composite PCM was prepared by blending of PMMA and myristic acid in different weight percentage. PMMA was used as a supporting material while myristic acid was used as PCM. Theoretically, PCM can be encapsulated in the support material after blending. However, a small amount of liquid PCMs can leak out from supporting material due to the volume change in phase change process. Therefore, a form-stable composite PCM with polyacrylic coating was studied. Leakage test was carried out to determine the leakage percentage of the form-stable composite PCM. Fourier transform infrared spectroscopy (FTIR) was used to characterize the chemical compatibility of the form-stable PCM composite while differential scanning calorimetry (DSC) was used to study the melting, freezing point and the latent heat of melting and freezing for the form-stable composite PCM.

Thermal conductivity of an organic phase change material/expanded graphite composite across the phase change temperature range and a novel thermal conductivity model

International Nuclear Information System (INIS)

Ling, Ziye; Chen, Jiajie; Xu, Tao; Fang, Xiaoming; Gao, Xuenong; Zhang, Zhengguo

2015-01-01

Highlights: • Expanded graphite can improve thermal conductivity of RT44HC by 20–60 times. • Thermal conductivity of PCM/EG composites keeps constant before/after melting. • Thermal conductivity of PCMs nearly doubled during phase changing. • Thermal conductivity of composite PCM increases with density and percentage of EG. • The simple model predicts thermal conductivity of EG-based composites accurately. - Abstract: This work studies factors that affect the thermal conductivity of an organic phase change material (PCM), RT44HC/expanded graphite (EG) composite, which include: EG mass fraction, composite PCM density and temperature. The increase of EG mass fraction and bulk density will both enhance thermal conductivity of composite PCMs, by up to 60 times. Thermal conductivity of RT44HC/EG composites remains independent on temperature outside the phase change range (40–45 °C), but nearly doubles during the phase change. The narrow temperature change during the phase change allows the maximum heat flux or minimum temperature for heat source if attaching PCMs to a first (constant temperature) or second (constant heat flux) thermal boundary. At last, a simple thermal conductivity model for EG-based composites is put forward, based on only two parameters: mass fraction of EG and bulk density of the composite. This model is validated with experiment data presented in this paper and in literature, showing this model has general applicability to any composite of EG and poor thermal conductive materials

DETERMINATION OF PHASE COMPOSITION OF SEALING COATING BASED ON APC (ALUMINOPHOSPHATE COMPOUNDS

Directory of Open Access Journals (Sweden)

BOLSHAKOV V. I.

2017-02-01

Full Text Available Summary. Goal. To investigate the phase composition of the obtained sealing coatings based on aluminophosphate compound (APC and the impact of temperature rise on it. Methods. Qualitative X-ray phase analysis (XRPA and differential thermal analysis (DTA are used as the methods of research. Roentgenograms for structural analysis were obtained on a DRON-4-07 using filtered copper radiation in the secondary beam. Registration and initial processing of diffraction patterns was performed using the software package PDOS with the output of the diffraction patterns on the screen. Using the "loupe" option allowed to identify weak interference lines, which increased the accuracy of the method of qualitative XRPA. The thermograms for DTA received on the device type Termoskan-2. The results. It is revealed that base of coating is X-ray amorphous phase. There are following crystalline phases: Al, AlPO4, Al (PO3 3, BN found in the coating. It is revealed that annealing doesn’t make a significant influence on the phase composition of the crystalline phases and the coating doesn’t lose properties after annealing during repeated thermal stress. Scientific novelty. The phase composition of the proposed sealing coatings based on APC and produced by plasma spraying, and the effect of annealing on the phase composition of the coating are investigated. The reaction of synthesis of primary material forming on the basis of APC for coating is offered. Practical significance. The results can be used in aviation technology in the development of gas turbine engines (GTE and the design of the compressors. The sealing coating may be used to improve the reliability of the compressor and to increase the efficiency ratio of turbine engine. During the operation the compressor’s blades touch the sealing coating of compressor’s stator and grooves it without causing locking and destruction of the rotor. Therefore, the development of new sealing coating compositions that

Performance evaluation on solar still integrated with nano-composite phase change materials

International Nuclear Information System (INIS)

Rajasekhar, G.; Eswaramoorthy, M.

2015-01-01

This paper communicates the performance evaluation of single slope solar still integrated with nano-composite phase change materials and compare with the experimental results of with and without phase change materials. A solar still with 1 m"2 surface area is developed with non-selective coating of absorber sheet with the provision of thermal energy storage materials. The solar still is tested on typical days with and without thermal energy storage materials. It is found that from the experimental studies that nano-materials (Al_2O_3) dispersed in paraffin wax is giving better cumulative yield of distillate than paraffin wax alone and without paraffin wax thermal storage. The daily efficiency of the solar still is computed for solar still with nano-composite phase change materials is 45% and solar still paraffin wax alone thermal storage is 40% and solar still without any thermal storage is 38%. It is concluded from the experimental studies; solar still integrated with nano-composite phase change materials gives better performance than with and without phase change material alone. (authors)

Phase Change Insulation for Energy Efficiency Based on Wax-Halloysite Composites

International Nuclear Information System (INIS)

Zhao, Yafei; Thapa, Suvhashis; Weiss, Leland; Lvov, Yuri

2014-01-01

Phase change materials (PCMs) have gained extensive attention in thermal energy storage. Wax can be used as a PCM in solar storage but it has low thermal conductivity. Introducing 10% halloysite admixed into wax yields a novel composite (wax-halloysite) which has a thermal conductivity of 0.5 W/mK. To increase the base conductivity, graphite and carbon nanotubes were added into the PCM composite improving its thermal energy storage. Thermal conductivity of wax-halloysite-graphite (45/45/10%) composite showed increased conductivity of 1.4 W/mK (3 times higher than the base wax-halloysite composite). Wax- halloysite-graphite-carbon nanotubes (45/45/5/5%) composite showed conductivity of 0.85 W/mK while maintaining the original shape perfectly until 91 °C (above the original wax melting point). Thermal conductivity can be further increased with higher doping of carbon nanotubes. This new composites are promising heat storage material due to good thermal stability, high thermal/electricity conductivity and ability to preserve its shape during phase transitions

Cermet anode compositions with high content alloy phase

Science.gov (United States)

Marschman, Steven C.; Davis, Norman C.

1989-01-01

Cermet electrode compositions comprising NiO-NiFe.sub.2 O.sub.4 -Cu-Ni, and methods for making, are disclosed. Addition of nickel metal prior to formation and densification of a base mixture into the cermet allows for an increase in the total amount of copper and nickel that can be contained in the NiO-NiFe.sub.2 O.sub.4 oxide system. Nickel is present in a base mixture weight concentration of from 0.1% to 10%. Copper is present in the alloy phase in a weight concentration of from 10% to 30% of the densified composition. Such cermet electrodes can be formed to have electrical conductivities well in excess of 100 ohm.sup.-1 cm.sup.-1. Other alloy and oxide system cermets having high content metal phases are also expected to be manufacturable in accordance with the invention.

Carbon nanotube/paraffin/montmorillonite composite phase change material for thermal energy storage.

Science.gov (United States)

Li, Min; Guo, Qiangang; Nutt, Steven

2017-04-01

A composite phase change material (PCM) comprised of organic montmorillonite (OMMT)/paraffin/grafted multi-walled nanotube (MWNT) is synthesized via ultrasonic dispersion and liquid intercalation. The microstructure of the composite PCM has been characterized to determine the phase distribution, and thermal properties (latent heat and thermal conductivity) have been measured by differential scanning calorimetry (DSC) and a thermal constant analyzer. The results show that paraffin molecules are intercalated in the montmorillonite layers and the grafted MWNTs are dispersed in the montmorillonite layers. The latent heat is 47.1 J/g, and the thermal conductivity of the OMMT/paraffin/grafted MWNT composites is 34% higher than that of the OMMT/paraffin composites and 65% higher than that of paraffin.

Phase composition and catalytic properties of oxide multicomponent molybdenum-containing catalysts for partial oxidation of propylene

International Nuclear Information System (INIS)

Malakhov, V.V.; Vlasov, A.A.; Boldyreva, N.N.; Dovlitova, L.S.; Plyasova, L.M.; Andrushkevich, T.V.; Kuznetsova, T.G.

1996-01-01

The catalytic properties and phase composition of multicomponent molybdenum-containing catalyst treated under various redox conditions have been studied. The phase composition has been considered by the methods of X-ray phase analysis and noncalibrated methods of differentiating dissolution (DD). Using the DD method the data on element composition, stoichiometry and quantitative content of phases of complex molybdates have been obtained for the first time. Data on modification of basic phases of the catalyst-cobalt and iron molybdates - by other cations from its composition suggest that the mechanism of action of the multicomponent catalyst is defined by the properties of one or several formed modified phases combining all the functions of an effective catalyst. 18 refs., 7 figs., 2 tabs

Phase formation, dielectric and magnetic properties of bismuth ferrite–lead magnesium niobate multiferroic composites

Energy Technology Data Exchange (ETDEWEB)

Wongmaneerung, R., E-mail: re_nok@yahoo.com [Faculty of Science, Maejo University, Chiang Mai 50290 (Thailand); Padchasri, J.; Tipakontitikul, R. [Department of Physics, Ubonratchathani University, Ubonratchathani 31490 (Thailand); Loan, T.H. [International Training Institute for Materials Science (ITIMS), Hanoi University of Science and Technology, No. 1, Dai Co Viet, Hanoi (Viet Nam); Jantaratana, P. [Department of Physics, Kasetsart University, Bangkok 10900 (Thailand); Yimnirun, R. [School of Physics, Institute of Science, and NANOTEC-SUT Center of Excellence of Advanced Functional Nanomaterials, Suranaree University of Technology, Nakhon Ratchasima 30000 (Thailand); Ananta, S. [Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand)

2014-09-01

Highlights: • A bimodal particle size concept was designed in the production of BF–PMN composites. • A very abnormal diffuse dielectric pattern is observed during the heating process. • BF–PMN composites show highly saturated magnetization. - Abstract: Binary multiferroic composites (1−x)BiFeO{sub 3}–xPb(Mg{sub 1/3}Nb{sub 2/3})O{sub 3} (BF–PMN; x = 0.0–50 wt%) were fabricated through a traditional ceramic process. The effect of the PMN contents on the phase assemblage, microstructure, dielectric and magnetic properties of the samples were investigated by X-ray diffraction (XRD), scanning electron microscope (SEM), LCR meter and vibrating sample magnetometer (VSM), respectively. The results indicate that all composites show that perovskite structure and PMN phase is compatible with the BF phase. The microstructure displays the mix phases between BF, PMN, Bi-rich BF and Fe-rich BF phases. Dielectric anomalies of these composites are totally different from BiFeO{sub 3} single phase. Moreover, the dielectric constant is found to increase as the content of PMN decreases. Magnetic transition temperatures are in the range of 270–440 °C. Interestingly, the M–H hysteresis loop measurements indicated that all composites exhibited weak ferromagnetism behavior at room temperature. The maximum remanent magnetization M{sub r} is observed for x = 30 wt% and then decreases when the PMN content is more than 40 wt%.

Preparation and Properties of Paraffin/TiO2/Active-carbon Composite Phase Change Materials

Directory of Open Access Journals (Sweden)

HAO Yong-gan

2016-11-01

Full Text Available A novel composite phase change materials (PCMs of paraffin/TiO2/active-carbon was prepared by a microemulsion method, where paraffin acted as a PCM and titanium dioxide (TiO2 as matrix material, and a small amount of active carbon was added to improve the thermal conductivity. The compositions, morphology and thermal properties of the paraffin/TiO2/active-carbon composite PCMs were characterized by XRD, SEM, TGA and DSC respectively. The shape stability during phase change process of this composite was also tested. The results show that paraffin is well encapsulated by TiO2 matrix, and thus exhibiting excellent shape-stabilized phase change feature. Besides, this composite PCM also presents superhydrophobic property. Therefore, these multifunctional features will endow PCMs with important application potential in energy efficient buildings.

Synthesis and characterization of interpenetrating phase ceramic metal composites

International Nuclear Information System (INIS)

Kanwal, T.

2011-01-01

Alumina powder was sintered in MW furnace under vacuum, without vacuum and conventional sintering furnace at different temperatures followed by characterization to observe the effect of sintering mode. Zirconia-Nickel and Alumina-Nickel systems were selected to study the effect of metallic phase interconnectivity on the electrical and thermal behavior in interpenetrating phase composites (IPCs). In order to obtain the homogenous mixture of Alumina and Nick powders, a detailed investigation was performed on the de-agglomeration and prop mixing of powders. Sintering parameters were optimized for the homogenization o Alumina with Nickel in planetary ball mill without sticking of powders with jar.- Homogenization of Zirconia-Nickel and Alumina-Nickel powders was perform using planetary ball mill as well as pestle mortar. Compaction of composites was performed uniaxially and sintering was carried in microwave furnace, tubular furnace with Argon environment and in vacuum sintering furnace. Electrical and thermal behavior of microwave as well as conventionally sintered ZrO/sub 2/-Ni and Al/sub 2/O/sub 3/-Ni IPCs was also observed. Electrical behavior of Composites was characterized b determining the impedance of the composites. To find the percolation limit for both Alumina-Nickel and Zirconia-Nickel composite systems the real part of impedance was used. On the basis of electrical characterization, samples were selected for SEM, BET surface area and CTE analysis. SEM of selected samples was performed t observe the connectivity of Nickel in composites. Finally, the effect of percolation limit on thermal behavior of IPCs was investigated with the help of CTE. (author)

Fabrication and characterization of nanofiber-nanoparticle-composites with phase change materials by electrospinning

International Nuclear Information System (INIS)

Babapoor, Aziz; Karimi, Gholamreza; Khorram, Mohammad

2016-01-01

Highlights: • Form-stable nanofibers with phase change material are produced by electrospinning. • PA6 and PEG are used as the supporting matrix and phase change material. • Various nanoparticles are used to enhance thermal properties of the fibers. • The nanofiber-nanoparticle composites exhibited desirable thermal stability. • Al 2 O 3 nanoparticles improved thermal conductivity of the composites considerably. - Graphical Abstract: Display Omitted - Abstract: Thermal energy storage has been recognized as one of the most important technologies for the utilization of renewable energy sources and conserving energy. In this investigation, through combination of polyethylene glycol (PEG) as a phase change material (PCM), polyamid6 (PA6) and various nanoparticles (SiO 2 , Al 2 O 3 , Fe 2 O 3 and ZnO) as supporting materials, novel form-stable PCMs-based composites were fabricated by single nozzle electrospinning. The structure, morphology and thermal properties of the prepared nanofiber-nanocomposite-enhanced phase change materials (NEPCMs) were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy and differential scanning calorimeter, respectively. Based on the results, nanocomposites-nanofibers were successfully fabricated with high thermal stability and reliability. It is observed that in all composites, the fiber diameter is decreased by increasing the nanoparticles loading. The lowest average diameter obtained was for Fe 2 O 3 composite. Al 2 O 3 composite showed the maximum thermal conductivity enhancement. This study suggests that the fabricated nanocomposite-PCMs offer proper phase transition temperature range and high heat enthalpy values and hence, have potential for thermal energy storage applications.

Mineral and chemical composition of rock core and surface gas composition in Horonobe Underground Research Laboratory project. Phase 1

International Nuclear Information System (INIS)

Hiraga, Naoto; Ishii, Eiichi

2008-02-01

The following three kinds of analyses were conducted for the 1st phase of the Horonobe Underground Research Laboratory Project. Mineral composition analysis of core sample. Whole rock chemical composition analysis of core sample. Surface gas composition analysis. This document summarizes the results of these analyses. (author)

Phase composition and magnetic properties in nanocrystalline permanent magnets based on misch-metal

Science.gov (United States)

Ma, Q.; Wang, J.; Zhang, Z. Y.; Zhang, X. F.; Liu, F.; Liu, Y. L.; Jv, X. M.; Li, Y. F.; Wang, G. F.

2017-09-01

The magnetic properties and phase composition of magnets based on misch-metal (MM) with nominal composition of MM13+xFe84-xB6.5 with x = 0.5, 1, 1.5, 2 and 2.5 using melt-spinning method were investigated. For x = 1.5, it could exhibit best magnetic properties (Hcj = 753.02 kA m-1, (BH)max = 70.77 kJ m-3). X-ray diffraction and energy dispersive spectroscopy show that the multi hard magnetic phase of RE2Fe14B (RE = La, Ce, Pr, Nd) existed in the magnets. The domain wall pinning effect and the exchange coupling interaction between grains are dependent on the abnormal RE-rich phase composition. Optimizing the phase constitution is necessary to improve magnetic properties in MM-Fe-B magnets for utilizing the rare earth resource in a balanced manner.

Composite Structure Monitoring using Direct Write Sensors, Phase II

Data.gov (United States)

National Aeronautics and Space Administration — This NASA SBIR Phase II project seeks to develop and demonstrate a suite of sensor products to monitor the health of composite structures. Sensors will be made using...

Organic vapor phase composition of sidestream and environmental tobacco smoke from cigarettes

International Nuclear Information System (INIS)

Higgins, C.E.; Jenkins, R.A.; Guerin, M.R.

1987-01-01

Environmental tobacco smoke (ETS) has received considerable attention because of its contribution to indoor air pollution. While some studies have attempted to estimate the exposure of humans to ETS constituents by extrapolating from information gleaned from investigations of sidestream smoke (SS), few studies have reported a direct comparison between the composition of SS and that of ETS. In the study reported here, the authors describe the relative compositional similarities and differences between the vapor phase of SS and that of ETS. SS was generated under different conditions. Both a new laminar flow chamber, which prevents significant alteration of the near-cigarette environment, and a modified Neurath chamber were used for SS generation. ETS samples were collected from an office environment. Vapor phase samples were collected on multi-media resin sorbent traps and analyzed using thermal desorption gas/liquid chromatography employing flame ionization, nitrogen-specific, and mass selective detection. Influences on the compositional profiles by the manner in which the SS is generated are described, as well as the differences between SS and ETS composition resulting from phase transition

Phase Composition Maps integrate mineral compositions with rock textures from the micro-meter to the thin section scale

Science.gov (United States)

Willis, Kyle V.; Srogi, LeeAnn; Lutz, Tim; Monson, Frederick C.; Pollock, Meagen

2017-12-01

Textures and compositions are critical information for interpreting rock formation. Existing methods to integrate both types of information favor high-resolution images of mineral compositions over small areas or low-resolution images of larger areas for phase identification. The method in this paper produces images of individual phases in which textural and compositional details are resolved over three orders of magnitude, from tens of micrometers to tens of millimeters. To construct these images, called Phase Composition Maps (PCMs), we make use of the resolution in backscattered electron (BSE) images and calibrate the gray scale values with mineral analyses by energy-dispersive X-ray spectrometry (EDS). The resulting images show the area of a standard thin section (roughly 40 mm × 20 mm) with spatial resolution as good as 3.5 μm/pixel, or more than 81 000 pixels/mm2, comparable to the resolution of X-ray element maps produced by wavelength-dispersive spectrometry (WDS). Procedures to create PCMs for mafic igneous rocks with multivariate linear regression models for minerals with solid solution (olivine, plagioclase feldspar, and pyroxenes) are presented and are applicable to other rock types. PCMs are processed using threshold functions based on the regression models to image specific composition ranges of minerals. PCMs are constructed using widely-available instrumentation: a scanning-electron microscope (SEM) with BSE and EDS X-ray detectors and standard image processing software such as ImageJ and Adobe Photoshop. Three brief applications illustrate the use of PCMs as petrologic tools: to reveal mineral composition patterns at multiple scales; to generate crystal size distributions for intracrystalline compositional zones and compare growth over time; and to image spatial distributions of minerals at different stages of magma crystallization by integrating textures and compositions with thermodynamic modeling.

Flexible composite material with phase change thermal storage

Science.gov (United States)

Buckley, Theresa M. (Inventor)

2001-01-01

A highly flexible composite material having a flexible matrix containing a phase change thermal storage material. The composite material can be made to heat or cool the body or to act as a thermal buffer to protect the wearer from changing environmental conditions. The composite may also include an external thermal insulation layer and/or an internal thermal control layer to regulate the rate of heat exchange between the composite and the skin of the wearer. Other embodiments of the PCM composite also provide 1) a path for evaporation or direct absorption of perspiration from the skin of the wearer for improved comfort and thermal control, 2) heat conductive pathways within the material for thermal equalization, 3) surface treatments for improved absorption or rejection of heat by the material, and 4) means for quickly regenerating the thermal storage capacity for reuse of the material. Applications of the composite materials are also described which take advantage of the composite's thermal characteristics. The examples described include a diver's wet suit, ski boot liners, thermal socks, ,gloves and a face mask for cold weather activities, and a metabolic heating or cooling blanket useful for treating hypothermia or fever patients in a medical setting and therapeutic heating or cooling orthopedic joint supports.

Phase field study of interfacial diffusion-driven spheroidization in a composite comprized of two mutually insoluble phases

Energy Technology Data Exchange (ETDEWEB)

Tian, Liang [Ames Laboratory; Russell, Alan [Ames Laboratory

2014-03-27

The phase field approach is a powerful computational technique to simulate morphological and microstructural evolution at the mesoscale. Spheroidization is a frequently observed morphological change of mesoscale heterogeneous structures during annealing. In this study, we used the diffuse interface phase field method to investigate the interfacial diffusion-driven spheroidization of cylindrical rod structures in a composite comprised of two mutually insoluble phases in a two-dimensional case. Perturbation of rod radius along a cylinder's axis has long been known to cause the necessary chemical potential gradient that drives spheroidization of the rod by Lord Rayleigh's instability theory. This theory indicates that a radius perturbation wavelength larger than the initial rod circumference would lead to cylindrical spheroidization. We investigated the effect of perturbation wavelength, interfacial energy, volume diffusion, phase composition, and interfacial percentage on the kinetics of spheroidization. The results match well with both the Rayleigh's instability criterion and experimental observations.

Pulsed cathodoluminescence of nanoscale aluminum oxide with different phase compositions

International Nuclear Information System (INIS)

Kortov, V.S.; Zvonarev, S.V.; Medvedev, A.I.

2011-01-01

The methods of pulsed cathodoluminescence have been used to study compacted powders and ceramics containing different phases of aluminum oxide. An intensive luminescence of the samples under study in the visible, NIR, and UV regions of the spectrum has been found. The luminescence bands are very broad and include a few components. The number of the bands depends on the phase composition of the samples. The oxygen vacancies, which capture one or two electrons, produce luminescence centers in the near UV region. The most probable in the visible region is the luminescence of aggregate defects, impurities, and surface centers. - Highlights: → We investigate pulsed cathodoluminescence spectra of nanoscale alumina. → We found the intensive luminescence in the visible, NIR, and UV regions. → The transformation of R-line structure depends on phase composition of alumina. → We substantiate the relation of luminescence bands with concrete centers.

FORMATION REGULARITIES OF PHASE COMPOSITION, STRUCTURE AND PROPERTIES DURING MECHANICAL ALLOYING OF BINARY ALUMINUM COMPOSITES

Directory of Open Access Journals (Sweden)

F. G. Lovshenko

2015-01-01

Full Text Available The paper presents investigation results pertaining to  ascertainment of formation regularities of phase composition and structure during mechanical alloying of binary aluminium composites/substances. The invetigations have been executed while applying a wide range of methods, devices and equipment used in modern material science. The obtained data complement each other. It has been established that presence of oxide and hydro-oxide films on aluminium powder  and introduction of surface-active substance in the composite have significant effect on mechanically and thermally activated phase transformations and properties of semi-finished products.  Higher fatty acids have been used as a surface active substance.The mechanism of mechanically activated solid solution formation has been identified. Its essence is  a formation of  specific quasi-solutions at the initial stage of processing. Mechanical and chemical interaction between components during formation of other phases has taken place along with dissolution  in aluminium while processing powder composites. Granule basis is formed according to the dynamic recrystallization mechanism and possess submicrocrystal structural type with the granule dimension basis less than 100 nm and the grains are divided in block size of not more than 20 nm with oxide inclusions of 10–20 nm size.All the compounds  with the addition of  surface-active substances including aluminium powder without alloying elements obtained by processing in mechanic reactor are disperse hardened. In some cases disperse hardening is accompanied by dispersive and solid solution hardnening process. Complex hardening predetermines a high temperature of recrystallization in mechanically alloyed compounds,  its value exceeds 400 °C.

Core-shell particle composition by liquid phase infrared spectroscopy

International Nuclear Information System (INIS)

Ribeiro, Luiz F.B.; Machado, Ricardo A.F.; Goncalves, Odinei H.; Bona, Evandro

2011-01-01

Polymeric particles with core-shell morphology can offer advantages over conventional particles improving properties like mechanical and chemical resistance. However, particle composition must be known due to its influence on the final properties. In this work liquid phase infrared spectroscopy was used to determine the overall composition of core-shell particles composed by polystyrene (core) and poly(methyl methacrylate) (shell). Results were in agreement with those obtained with H 1 Nuclear Magnetic Resonance data (Goncalves et al, 2008). (author)

Composition of Surface Adsorbed Layer of TiO2 Stored in Ambient Air

Directory of Open Access Journals (Sweden)

Zakharenko V.S.

2017-11-01

Full Text Available The processes of dark, UV, and visible light promoted desorption of surface species were investigated for three different TiO2 samples: TiO2 prepared by dispersion of the titania single crystal, TiO2 prepared by combustion of a pyrotechnic mixture in air, and commercial TiO2 P25. The composition of the adsorbed layer was identified in the dark and under UV and visible light irradiation. The composition of desorption products showed the dependence of the adsorption layer state on the TiO2 nature. Methane photodesorption was detected only for the commercial TiO2 P25. Possible reasons for methane emission include the capturing of complete molecules during the TiO2 production process and photocatalytic hydrogenation of CO2 under UV-light.

Influence of interface conditions on laser diode ignition of pyrotechnic mixtures: application to the design of an ignition device

Energy Technology Data Exchange (ETDEWEB)

Opdebeck, Frederic; Gillard, Philippe [Laboratoire Energetique Explosions et Structures de l' Universite d' Orleans, 63 boulevard de Lattre de Tassigny, 18020 cedex, Bourges (France); Radenac, D' Erwann [Laboratoire de combustion et de detonique, ENSMA, BP 109, 86960 cedex, Futuroscope (France)

2003-01-01

This paper treats of numerical modelling which simulates the laser ignition of pyrotechnic mixtures. The computation zone is divided into two fields. The first is used to take account of the heat loss with the outside. It can represent an optical fibre or a sapphire protective porthole. The second field represents the reactive tablet which absorbs the laser diode's beam. A specific feature of the model is that it incorporates a thermal contact resistance R{sub c} between the two computation fields. Through knowledge of the thermal, optical and kinetic properties, this code makes it possible to compute the ignition conditions. The latter are defined by the energy E{sub 50} and the time t{sub i} of ignition of any pyrotechnic mixture and for various ignition systems.This work was validated in the case of an ignition system consisting of a laser diode with an optical lens re-focussing system. The reactive tablet contains 62% by mass of iron and 38% by mass of KClO{sub 4}. Its porosity is 25.8%. After an evaluation of the laser's coefficient of absorption, the variations of the ignition parameters E{sub 50} and t{sub i} are studied as a function of the thermal contact resistance R{sub c}. Temperature profiles are obtained as a function of time and for various values of the thermal contact resistance R{sub c}. More fundamental observations are made concerning the position of the hot spot corresponding to priming. From this study, which concerns the heat exchange between the two media, several practical conclusions are given concerning the design of an ignition device. By evaluation of the thermal contact resistance R{sub c}, comparison with test results becomes possible and the results of the computations are in reasonable agreement with the test measurements. (authors)

Preparation and characterization of form-stable paraffin/polyurethane composites as phase change materials for thermal energy storage

International Nuclear Information System (INIS)

Chen, Keping; Yu, Xuejiang; Tian, Chunrong; Wang, Jianhua

2014-01-01

Highlights: • Paraffin/polyurethane composite as form-stable phase change material was prepared by bulk polymerization. • Paraffin/polyurethane composite possesses typical character of dual phase transition. • Total latent heat of n-eicosane/PUPCM is as high as 141.2 J/g. • Maximum encapsulation ratio for n-octadecane/PUPCM composites is 25% w/w. - Abstract: Polyurethane phase change material (PUPCM) has been demonstrated to be effective solid–solid phase change material for thermal energy storage. However, the high cost and complex process on preparation of PUPCMs with high enthalpy and broad phase transition temperature range can prohibit industrial-scale applications. In this work, a series of novel form-stable paraffin/PUPCMs composites (n-octadecane/PUPCM, n-eicosane/PUPCM and paraffin wax/PUPCM) with high enthalpy and broad phase transition temperature range (20–65 °C) were directly synthesized via bulk polymerization. The composites were prepared at different mass fractions of n-octadecane (10, 20, 25, 30% w/w). The results indicated that the maximum encapsulation ratio for n-octadecane/PUPCM10000 composites was around 25% w/w. The chemical structure and crystalline properties of these composites were characterized by Fourier transform infrared spectroscopy (FT-IR), polarizing optical microscopy (POM), wide-angle X-ray diffraction (WAXD). Thermal properties and thermal reliability of the composites were determined using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). From DSC analysis, the composites showed a typical dual phase change temperature. The enthalpy for the composite with 25% w/w n-eicosane was as high as 141.2 J/g. TGA analysis indicated that the composites degraded at considerably high temperatures. The process of preparation of PUPCMs and their composites was very simple, inexpensive, environmental friendly and easy to process into desired shapes, which could find the promising applications in solar

Multifunctional Metal/Polymer Composite Fiber for Space Applications, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — In this Small Business Innovation Research Phase I Program, Syscom Technology, Inc. (STI) will fabricate a metallized multifunctional composite fiber from a...

Thermal buffering performance of composite phase change materials applied in low-temperature protective garments

Science.gov (United States)

Yang, Kai; Jiao, Mingli; Yu, Yuanyuan; Zhu, Xueying; Liu, Rangtong; Cao, Jian

2017-07-01

Phase change material (PCM) is increasingly being applied in the manufacturing of functional thermo-regulated textiles and garments. This paper investigated the thermal buffering performance of different composite PCMs which are suitable for the application in functional low-temperature protective garments. First, according to the criteria selecting PCM for functional textiles/garments, three kinds of pure PCM were selected as samples, which were n-hexadecane, n-octadecane and n-eicosane. To get the adjustable phase change temperature range and higher phase change enthalpy, three kinds of composite PCM were prepared using the above pure PCM. To evaluate the thermal buffering performance of different composite PCM samples, the simulated low-temperature experiments were performed in the climate chamber, and the skin temperature variation curves in three different low temperature conditions were obtained. Finally composite PCM samples’ thermal buffering time, thermal buffering capacity and thermal buffering efficiency were calculated. Results show that the comprehensive thermal buffering performance of n-octadecane and n-eicosane composite PCM is the best.

Lightweight, High Strength Nano-Composite Magnesium for Radiators, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — In this Phase I SBIR, Terves will develop processing routes to produce high thermal conductivity magnesium composites for use in heat transfer applications such as...

Body composition, symptoms, and survival in advanced cancer patients referred to a phase I service.

Science.gov (United States)

Parsons, Henrique A; Baracos, Vickie E; Dhillon, Navjot; Hong, David S; Kurzrock, Razelle

2012-01-01

Body weight and body composition are relevant to the outcomes of cancer and antineoplastic therapy. However, their role in Phase I clinical trial patients is unknown. We reviewed symptom burden, body composition, and survival in 104 patients with advanced cancer referred to a Phase I oncology service. Symptom burden was analyzed using the MD Anderson Symptom Assessment Inventory(MDASI); body composition was evaluated utilizing computerized tomography(CT) images. A body mass index (BMI)≥25 kg/m² was considered overweight. Sarcopenia, severe muscle depletion, was assessed using CT-based criteria. Most patients were overweight (n = 65, 63%); 53 patients were sarcopenic (51%), including 79% of patients with a BMIbody composition: 215 (71-358) (BMIcancer diagnosis predicted longer survival in multivariate analysis after controlling for age, gender, performance status, and fat index. Patients referred to a Phase I clinic had a high frequency of sarcopenia and a BMI≥25 kg/m², independent of symptom burden. Body composition variables were predictive of clinically relevant survival differences, which is potentially important in developing Phase I studies.

Design, fabrication, and properties of 2-2 connectivity cement/polymer based piezoelectric composites with varied piezoelectric phase distribution

International Nuclear Information System (INIS)

Dongyu, Xu; Xin, Cheng; Shifeng, Huang; Banerjee, Sourav

2014-01-01

The laminated 2-2 connectivity cement/polymer based piezoelectric composites with varied piezoelectric phase distribution were fabricated by employing Lead Zirconium Titanate ceramic as active phase, and mixture of cement powder, epoxy resin, and hardener as matrix phase with a mass proportion of 4:4:1. The dielectric, piezoelectric, and electromechanical coupling properties of the composites were studied. The composites with large total volume fraction of piezoelectric phase have large piezoelectric strain constant and relative permittivity, and the piezoelectric and dielectric properties of the composites are independent of the dimensional variations of the piezoelectric ceramic layer. The composites with small total volume fraction of piezoelectric phase have large piezoelectric voltage constant, but also large dielectric loss. The composite with gradually increased dimension of piezoelectric ceramic layer has the smallest dielectric loss, and that with the gradually increased dimension of matrix layer has the largest piezoelectric voltage constant. The novel piezoelectric composites show potential applications in fabricating ultrasonic transducers with varied surface vibration amplitude of the transducer

Rapid Construction of Fe-Co-Ni Composition-Phase Map by Combinatorial Materials Chip Approach.

Science.gov (United States)

Xing, Hui; Zhao, Bingbing; Wang, Yujie; Zhang, Xiaoyi; Ren, Yang; Yan, Ningning; Gao, Tieren; Li, Jindong; Zhang, Lanting; Wang, Hong

2018-03-12

One hundred nanometer thick Fe-Co-Ni material chips were prepared and isothermally annealed at 500, 600, and 700 °C, respectively. Pixel-by-pixel composition and structural mapping was performed by microbeam X-ray at synchrotron light source. Diffraction images were recorded at a rate of 1 pattern/s. The XRD patterns were automatically processed, phase-identified, and categorized by hierarchical clustering algorithm to construct the composition-phase map. The resulting maps are consistent with corresponding isothermal sections reported in the ASM Alloy Phase Diagram Database, verifying the effectiveness of the present approach in phase diagram construction.

Effect of Iron Impurity on the Phase Composition, Structure and Properties of Magnesium Alloys Containing Manganese and Aluminum

Science.gov (United States)

Volkova, E. F.

2017-07-01

Results of a study of the interaction between iron impurity and manganese and aluminum alloying elements during formation of phase composition in alloys of the Mg - Mn, Mg - Al, Mg - Al - Mn, and Mg - Al - Zn - Mn systems are presented. It is proved that this interaction results in introduction of Fe into the intermetallic phase. The phase compositions of model magnesium alloys and commercial alloys MA2-1 and MA5 are studied. It is shown that both manganese and aluminum may bind the iron impurity into phases. Composite Fe-containing intermetallic phases of different compositions influence differently the corrosion resistance of magnesium alloys.

Phase-alternated composite π/2 pulses for solid state quadrupole echo NMR spectroscopy

International Nuclear Information System (INIS)

Ramamoorthy, A.; Narasimhan, P.T.

1991-01-01

Phase-alternated composite π/2 pulses have been constructed for spin I=1 to overcome quadrupole interaction effects in solid state nuclear magnetic resonance(NMR) spectroscopy. Magnus expansion approach is used to design these sequences in a manner similar to the NMR coherent averaging theory. It is inferred that the symmetric phase-alternated composite π/2 pulses reported here are quite successful in producing quadrupole echo free phase distortions. This effectiveness of the present composite pulses is due to the fact that most of them are of shorter durations as compared to the ones reported in literature. In this theoretical procedure, irreducible spherical tensor operator formalism is employed to simplify the complexity involved in the evaluation of Magnus expansion terms. It has been argued in this paper that composite π/2 pulse sequences for this purpose can also be derived from the broadband inversion π pulses which are designed to compensate electric field gradient(efg) inhomogeniety in spin I=1 nuclear quadrupole resonance(NQR) spectroscopy. (author). 28 refs

Superplastic flow of two-phase ceramics containing rigid inclusions-zirconia/mullite composites

International Nuclear Information System (INIS)

Yoon, C.K.; Chen, I.W.

1990-01-01

A continuum theory for non-newtonian flow of a two-phase composite containing rigid inclusions is presented. It predicts flow suppression by a factor of (1 - V) q , where V is the volume fraction of the rigid inclusion and q depends on the stress exponent and the inclusion shape. Stress concentrations in the rigid inclusion have also been evaluated. As the stress exponent increases, flow suppression is more pronounced even though stress concentration is less severe. To test this theory, superplastic flow of zirconia/mullite composites, in which zirconia is a soft, non-Newtonian super-plastic matrix and mullite is a rigid phase of various size, shape, and amount, is studied. The continuum theory is found to describe the two-phase superplastic flow reasonably well

Designing dual phase sensing materials from polyaniline filled styrene–isoprene–styrene composites

International Nuclear Information System (INIS)

Sadasivuni, Kishor Kumar; Ponnamma, Deepalekshmi; Kasak, Peter; Krupa, Igor; Ali S A Al-Maadeed, Mariam

2014-01-01

The demand for developing oil detectors is ever increasing since the cleanup and recovery from oil spill usually take long time. Here we propose oil sensors made of polyaniline (PANI) filled poly(styrene–isoprene–styrene) (SIS) block copolymer composite films with good uniformity and dispersion. The changes in resistivity of the samples in presence of both oil and water media reveal the good sensing ability of SIS–PANI films towards oil in water (dual phase). The morphology and chemical composition of the developed products are characterized by scanning electron microscopy and Fourier transformation infrared spectroscopy. Swelling studies are performed to correlate the sensing response to the structural variations and based on it a mechanism is derived for the dual phase sensing. Contact angle measurements confirm the behavior further. The thermal properties and crystallinity of the composites are also addressed by the thermogravimetric and differential scanning calorimetric studies. The developed oil sensor material is able to withstand extreme temperature condition as well. - Highlights: • We model a dual phase sensor capable of detecting oil in water. • A mechanism is proposed to correlate sensing with diffusion. • In situ polymerization helps in the uniform distribution of filler. • Polymer composite sensor could be used as stickers on oil pipelines

Designing dual phase sensing materials from polyaniline filled styrene–isoprene–styrene composites

Energy Technology Data Exchange (ETDEWEB)

Sadasivuni, Kishor Kumar, E-mail: kishor_kumars@yahoo.com [Centre for Advanced Materials, Qatar University, Doha (Qatar); Ponnamma, Deepalekshmi [School of Chemical Sciences, Mahatma Gandhi University, Kottayam 686560, Kerala (India); Kasak, Peter; Krupa, Igor; Ali S A Al-Maadeed, Mariam [Centre for Advanced Materials, Qatar University, Doha (Qatar)

2014-10-15

The demand for developing oil detectors is ever increasing since the cleanup and recovery from oil spill usually take long time. Here we propose oil sensors made of polyaniline (PANI) filled poly(styrene–isoprene–styrene) (SIS) block copolymer composite films with good uniformity and dispersion. The changes in resistivity of the samples in presence of both oil and water media reveal the good sensing ability of SIS–PANI films towards oil in water (dual phase). The morphology and chemical composition of the developed products are characterized by scanning electron microscopy and Fourier transformation infrared spectroscopy. Swelling studies are performed to correlate the sensing response to the structural variations and based on it a mechanism is derived for the dual phase sensing. Contact angle measurements confirm the behavior further. The thermal properties and crystallinity of the composites are also addressed by the thermogravimetric and differential scanning calorimetric studies. The developed oil sensor material is able to withstand extreme temperature condition as well. - Highlights: • We model a dual phase sensor capable of detecting oil in water. • A mechanism is proposed to correlate sensing with diffusion. • In situ polymerization helps in the uniform distribution of filler. • Polymer composite sensor could be used as stickers on oil pipelines.

Preparation and thermal properties characterization of carbonate salt/carbon nanomaterial composite phase change material

International Nuclear Information System (INIS)

Tao, Y.B.; Lin, C.H.; He, Y.L.

2015-01-01

Highlights: • Nanocomposite phase change materials were prepared and characterized. • Larger specific surface area is more efficient to enhance specific heat. • Columnar structure is more efficient to enhance thermal conductivity. • Thermal conductivity enhancement is the key. • Single walled carbon nanotube is the optimal nanomaterial additive. - Abstract: To enhance the performance of high temperature salt phase change material, four kinds of carbon nanomaterials with different microstructures were mixed into binary carbonate eutectic salts to prepare carbonate salt/nanomaterial composite phase change material. The microstructures of the nanomaterial and composite phase change material were characterized by scanning electron microscope. The thermal properties such as melting point, melting enthalpy, specific heat, thermal conductivity and total thermal energy storage capacity were characterized. The results show that the nanomaterial microstructure has great effects on composite phase change material thermal properties. The sheet structure Graphene is the best additive to enhance specific heat, which could be enhanced up to 18.57%. The single walled carbon nanotube with columnar structure is the best additive to enhance thermal conductivity, which could be enhanced up to 56.98%. Melting point increases but melting enthalpy decreases with nanomaterial specific surface area increase. Although the additives decrease the melting enthalpy of composite phase change material, they also enhance the specific heat. As a combined result, the additives have little effects on thermal energy storage capacity. So, for phase change material performance enhancement, more emphasis should be placed on thermal conductivity enhancement and single walled carbon nanotube is the optimal nanomaterial additive

Phase composition of rapidly solidified Ag-Sn-Cu dental alloys

International Nuclear Information System (INIS)

Lecong Dzuong; Do Minh Nghiep; Nguyen van Dzan; Cao the Ha

1996-01-01

The phase composition of some rapidly solidified Ag-Sn-Cu dental alloys with different copper contents (6.22 wtpct) has been studied by XRD, EMPA and optical microscopy. The samples were prepared from melt-spun ribbons. The microstructure of the as-quenched ribbons was microcrystalline and consisted of the Ag sub 3 Sn, Ag sub 4 Sn, Cu sub 3 Sn and Cu sub 3 Sn sub 8 phases. Mixing with mercury (amalgamation) led to formation of the Ag sub 2 Hg sub 3, Sn sub 7 Hg and Cu sub 6 Sn sub 5 phases. The amount of copper atoms in the alloys played an important role in phase formation in the amalgams

Two-phase quasi-equilibrium in β-type Ti-based bulk metallic glass composites

Science.gov (United States)

Zhang, L.; Pauly, S.; Tang, M. Q.; Eckert, J.; Zhang, H. F.

2016-01-01

The microstructural evolution of cast Ti/Zr-based bulk metallic glass composites (BMGCs) containing β-Ti still remains ambiguous. This is why to date the strategies and alloys suitable for producing such BMGCs with precisely controllable volume fractions and crystallite sizes are still rather limited. In this work, a Ti-based BMGC containing β-Ti was developed in the Ti-Zr-Cu-Co-Be system. The glassy matrix of this BMGC possesses an exceptional glass-forming ability and as a consequence, the volume fractions as well as the composition of the β-Ti dendrites remain constant over a wide range of cooling rates. This finding can be explained in terms of a two-phase quasi-equilibrium between the supercooled liquid and β-Ti, which the system attains on cooling. The two-phase quasi-equilibrium allows predicting the crystalline and glassy volume fractions by means of the lever rule and we succeeded in reproducing these values by slight variations in the alloy composition at a fixed cooling rate. The two-phase quasi-equilibrium could be of critical importance for understanding and designing the microstructures of BMGCs containing the β-phase. Its implications on the nucleation and growth of the crystalline phase are elaborated. PMID:26754315

Composite phase change materials prepared by encapsuling paraffin in PVC macrocapsules

International Nuclear Information System (INIS)

Chen, Yingbo; Zhang, Shifeng; Zhang, Qi; Chen, Yusheng; Zhang, Yufeng

2014-01-01

Highlights: • PVC macrocapsules coated with SiO 2 were synthesized. • Paraffin was encapsuled in the capsules. • The composite PCM has high heat capacity. • The composite PCM has no surpercooling. - Abstract: A novel phase change material capsules with SiO 2 in their surface was prepared by absorbing paraffin into PVC hollow capsules and by the polycondensation reaction of TEOS in different conditions. X-ray photoelectron spectroscopy (XPS) analysis and scanning electronic microscope (SEM) were used to determine chemical composition and microstructure of the composite capsules, respectively. Enthalpy capacity and thermal stability of the composite capsules are systematically characterized by using differential scanning calorimeter (DSC), thermogravimetric analyzer (TGA) and thermocycling tests. The composite has high heat capacity with good stability and absence of supercooling phenomena

Same-strand overlapping genes in bacteria: compositional determinants of phase bias

Directory of Open Access Journals (Sweden)

Landan Giddy

2008-08-01

Full Text Available Abstract Background Same-strand overlapping genes may occur in frameshifts of one (phase 1 or two nucleotides (phase 2. In previous studies of bacterial genomes, long phase-1 overlaps were found to be more numerous than long phase-2 overlaps. This bias was explained by either genomic location or an unspecified selection advantage. Models that focused on the ability of the two genes to evolve independently did not predict this phase bias. Here, we propose that a purely compositional model explains the phase bias in a more parsimonious manner. Same-strand overlapping genes may arise through either a mutation at the termination codon of the upstream gene or a mutation at the initiation codon of the downstream gene. We hypothesized that given these two scenarios, the frequencies of initiation and termination codons in the two phases may determine the number for overlapping genes. Results We examined the frequencies of initiation- and termination-codons in the two phases, and found that termination codons do not significantly differ between the two phases, whereas initiation codons are more abundant in phase 1. We found that the primary factors explaining the phase inequality are the frequencies of amino acids whose codons may combine to form start codons in the two phases. We show that the frequencies of start codons in each of the two phases, and, hence, the potential for the creation of overlapping genes, are determined by a universal amino-acid frequency and species-specific codon usage, leading to a correlation between long phase-1 overlaps and genomic GC content. Conclusion Our model explains the phase bias in same-strand overlapping genes by compositional factors without invoking selection. Therefore, it can be used as a null model of neutral evolution to test selection hypotheses concerning the evolution of overlapping genes. Reviewers This article was reviewed by Bill Martin, Itai Yanai, and Mikhail Gelfand.

Fabrication of fiber composites with a MAX phase matrix by reactive melt infiltration

International Nuclear Information System (INIS)

Lenz, F; Krenkel, W

2011-01-01

Due to the inherent brittleness of ceramics it is very desirable to increase the damage tolerance of ceramics. The ternary MAX phases are a promising group of materials with high fracture toughness. The topic of this study is the development of ceramic matrix composites (CMCs) with a matrix containing MAX phases, to achieve a damage tolerant structural composite material. For this purpose carbon fiber reinforced preforms with a carbon-titanium carbide matrix (C/C-TiC) were developed and infiltrated with silicon by a pressureless reactive melt infiltration. Finally liquid silicon caused the formation of SiC, TiSi 2 and Ti 3 SiC 2 in the matrix of the composite.

Polymeric compositions incorporating polyethylene glycol as a phase change material

Science.gov (United States)

Salyer, Ival O.; Griffen, Charles W.

1989-01-01

A polymeric composition comprising a polymeric material and polyethylene glycol or end-capped polyethylene glycol as a phase change material, said polyethylene glycol and said end-capped polyethylene glycol having a molecular weight greater than about 400 and a heat of fusion greater than about 30 cal/g; the composition is useful in making molded and/or coated materials such as flooring, tiles, wall panels and the like; paints containing polyethylene glycols or end-capped polyethylene glycols are also disclosed.

Structure and phase composition of titanium nitride coating on austenitic steel

International Nuclear Information System (INIS)

Dubovitskaya, N.V.; Kolenchenko, L.D.; Larikov, L.N.

1989-01-01

Structure and phase composition of titanium nitride coating deposited on 08Kh18N10T steel substrate using ''Bulat'' device are studied. Use of complex investigation methods permitted despite small coating thickness (1μm) to aquire information on hardness, porosity, to study phase composition in all coating thickness. The surface layer (∼0.1 μm) consists of ε-Ti 2 N, TiN 0.6 , TiC 0.35 , that is formed with carbon participation from oil vacuum. In more deeper layers beside ε-Ti 2 N TiC 0.14 N 0.77 is present. Effect of carbon diffusion from substrate to forming coating is stated. Gradient of element concentrations in the substrate-coating interface causes recrystallization of austenite

Compositional modeling of three-phase flow with gravity using higher-order finite element methods

KAUST Repository

Moortgat, Joachim

2011-05-11

A wide range of applications in subsurface flow involve water, a nonaqueous phase liquid (NAPL) or oil, and a gas phase, such as air or CO2. The numerical simulation of such processes is computationally challenging and requires accurate compositional modeling of three-phase flow in porous media. In this work, we simulate for the first time three-phase compositional flow using higher-order finite element methods. Gravity poses complications in modeling multiphase processes because it drives countercurrent flow among phases. To resolve this issue, we propose a new method for the upwinding of three-phase mobilities. Numerical examples, related to enhanced oil recovery and carbon sequestration, are presented to illustrate the capabilities of the proposed algorithm. We pay special attention to challenges associated with gravitational instabilities and take into account compressibility and various phase behavior effects, including swelling, viscosity changes, and vaporization. We find that the proposed higher-order method can capture sharp solution discontinuities, yielding accurate predictions of phase boundaries arising in computational three-phase flow. This work sets the stage for a broad extension of the higher-order methods for numerical simulation of three-phase flow for complex geometries and processes.

Supercooling suppression of microencapsulated phase change materials by optimizing shell composition and structure

International Nuclear Information System (INIS)

Cao, Fangyu; Yang, Bao

2014-01-01

Highlights: • A new method for supercooling suppression of microPCMs by optimizing the structure of the microcapsule shell. • Large effective latent heat (up to 213 J/g) of the microPCMs, much higher than those using additive as nucleating agents. • Change of shell composition and structure significantly affects the phase transition processes of the encapsulated PCMs. • The latent heat of the shell-induced phase transition is maximized, reaching 83.7% of the latent heat of bulk octadecane. • Hollow spheres with porous rather than solid resin shell are also formed when the SDS concentration is very high. - Abstract: A new method for supercooling suppression of microencapsulated phase change materials (PCMs) has been developed by optimizing the composition and structure of the microcapsule resin shell. The microcapsules comprising paraffin octadecane encapsulated in melamine–formaldehyde resin shell were synthesized with the use the oil-in-water emulsion technique. These PCM microcapsules are 5–15 μm in diameter. The supercooling of these octadecane microcapsules can be as large as 13.6 °C, when the homogeneous nucleation is dominant during the melt crystallization into the thermodynamically stable triclinic phase. It is discovered that the homogeneous nucleation can be mediated by shell-induced nucleation of the triclinic phase and the metastable rotator phase when the shell composition and structure are optimized, without need of any nucleating additives. The effects of synthesis parameters, such as ratio of melamine to formaldehyde, pH of pre-polymer, and pH of emulsion, on the phase transition properties of the octadecane microcapsules have been investigated systemically. The optimum synthesis conditions have been identified in terms of minimizing the supercooling while maintaining heat capacity. Potential applications of this type of phase changeable microcapsules include high heat capacity thermal fluids, thermal management in smart buildings

The influence of glass composition on crystalline phase stability in glass-ceramic wasteforms

International Nuclear Information System (INIS)

Maddrell, Ewan; Thornber, Stephanie; Hyatt, Neil C.

2015-01-01

Highlights: • Crystalline phase formation shown to depend on glass matrix composition. • Zirconolite forms as the sole crystalline phase only for most aluminous glasses. • Thermodynamics indicate that low silica activity glasses stabilise zirconolite. - Abstract: Zirconolite glass-ceramic wasteforms were prepared using a suite of Na 2 O–Al 2 O 3 –B 2 O 3 –SiO 2 glass matrices with variable Al:B ratios. Zirconolite was the dominant crystalline phase only for the most alumina rich glass compositions. As the Al:B ratio decreased zirconolite was replaced by sphene, zircon and rutile. Thermodynamic data were used to calculate a silica activity in the glass melt below which zirconolite is the favoured crystalline phase. The concept of the crystalline reference state of glass melts is then utilised to provide a physical basis for why silica activity varies with the Al:B ratio

Preparation and thermal energy storage properties of paraffin/calcined diatomite composites as form-stable phase change materials

International Nuclear Information System (INIS)

Sun, Zhiming; Zhang, Yuzhong; Zheng, Shuilin; Park, Yuri; Frost, Ray L.

2013-01-01

Highlights: ► Composite phase change material (PCM) was prepared by blending composite paraffin and calcined diatomite. ► The optimum mixed proportion was obtained through differential scanning calorimetry. ► Thermal energy storage properties of the composite PCMs were determined by DSC. ► Thermal cycling test showed that the prepared PCMs are thermally reliable and chemically stable. - Abstract: A composite paraffin-based phase change material (PCM) was prepared by blending composite paraffin and calcined diatomite through the fusion adsorption method. In this study, raw diatomite was purified by thermal treatment in order to improve the adsorption capacity of diatomite, which acted as a carrier material to prepare shape-stabilized PCMs. Two forms of paraffin (paraffin waxes and liquid paraffin) with different melting points were blended together by the fusion method, and the optimum mixed proportion with a suitable phase-transition temperature was obtained through differential scanning calorimetry (DSC) analysis. Then the prepared composite paraffin was adsorbed in calcined diatomite. The prepared paraffin/calcined diatomite composites were characterized by the scanning electron microscope (SEM) and Fourier transformation infrared (FT-IR) analysis techniques. Thermal energy storage properties of the composite PCMs were determined by DSC method. DSC results showed that there was an optimum adsorption ratio between composite paraffin and calcined diatomite and the phase-transition temperature and the latent heat of the composite PCMs were 33.04 °C and 89.54 J/g, respectively. Thermal cycling test of composite PCMs showed that the prepared material is thermally reliable and chemically stable. The obtained paraffin/calcined diatomite composites have proper latent heat and melting temperatures, and show practical significance and good potential application value

Preparation and thermal energy storage properties of paraffin/calcined diatomite composites as form-stable phase change materials

Energy Technology Data Exchange (ETDEWEB)

Sun, Zhiming [School of Chemical and Environmental Engineering, China University of Mining and Technology, Beijing 100083 (China); Chemistry Discipline, Faculty of Science and Technology, Queensland University of Technology, 2 George Street, GPO Box 2434, Brisbane, Queensland 4001 (Australia); Zhang, Yuzhong [School of Chemical and Environmental Engineering, China University of Mining and Technology, Beijing 100083 (China); Zheng, Shuilin, E-mail: shuilinzh@yahoo.com.cn [School of Chemical and Environmental Engineering, China University of Mining and Technology, Beijing 100083 (China); Park, Yuri [Chemistry Discipline, Faculty of Science and Technology, Queensland University of Technology, 2 George Street, GPO Box 2434, Brisbane, Queensland 4001 (Australia); Frost, Ray L., E-mail: r.frost@qut.edu.au [Chemistry Discipline, Faculty of Science and Technology, Queensland University of Technology, 2 George Street, GPO Box 2434, Brisbane, Queensland 4001 (Australia)

2013-04-20

Highlights: ► Composite phase change material (PCM) was prepared by blending composite paraffin and calcined diatomite. ► The optimum mixed proportion was obtained through differential scanning calorimetry. ► Thermal energy storage properties of the composite PCMs were determined by DSC. ► Thermal cycling test showed that the prepared PCMs are thermally reliable and chemically stable. - Abstract: A composite paraffin-based phase change material (PCM) was prepared by blending composite paraffin and calcined diatomite through the fusion adsorption method. In this study, raw diatomite was purified by thermal treatment in order to improve the adsorption capacity of diatomite, which acted as a carrier material to prepare shape-stabilized PCMs. Two forms of paraffin (paraffin waxes and liquid paraffin) with different melting points were blended together by the fusion method, and the optimum mixed proportion with a suitable phase-transition temperature was obtained through differential scanning calorimetry (DSC) analysis. Then the prepared composite paraffin was adsorbed in calcined diatomite. The prepared paraffin/calcined diatomite composites were characterized by the scanning electron microscope (SEM) and Fourier transformation infrared (FT-IR) analysis techniques. Thermal energy storage properties of the composite PCMs were determined by DSC method. DSC results showed that there was an optimum adsorption ratio between composite paraffin and calcined diatomite and the phase-transition temperature and the latent heat of the composite PCMs were 33.04 °C and 89.54 J/g, respectively. Thermal cycling test of composite PCMs showed that the prepared material is thermally reliable and chemically stable. The obtained paraffin/calcined diatomite composites have proper latent heat and melting temperatures, and show practical significance and good potential application value.

Phase composition and microstructure of WC-Co alloys obtained by selective laser melting

Science.gov (United States)

Khmyrov, Roman S.; Shevchukov, Alexandr P.; Gusarov, Andrey V.; Tarasova, Tatyana V.

2018-03-01

Phase composition and microstructure of initial WC, BK8 (powder alloy 92 wt.% WC-8 wt.% Co), Co powders, ball-milled powders with four different compositions (1) 25 wt.% WC-75 wt.% Co, (2) 30 wt.% BK8-70 wt.% Co, (3) 50 wt.% WC-50 wt.% Co, (4) 94 wt.% WC-6 wt.% Co, and bulk alloys obtained by selective laser melting (SLM) from as-milled powders in as-melted state and after heat treatment were investigated by scanning electron microscopy and X-ray diffraction analysis. Initial and ball-milled powders consist of WC, hexagonal α-Co and face-centered cubic β-Co. The SLM leads to the formation of major new phases W3Co3C, W4Co2C and face-centered cubic β-Co-based solid solution. During the heat treatment, there occurs partial decomposition of the face-centered cubic β-Co-based solid solution with the formation of W2C and hexagonal α-Co solid solution. The microstructure of obtained bulk samples, in general, corresponds to the observed phase composition.

Phase composition of Al-Ti-Nb-Mo γ alloys in the heat-treatment temperature range: Calculation and experiment

Science.gov (United States)

Belov, N. A.; Dashkevich, N. I.; Bel'tyukova, S. O.

2015-07-01

The phase composition of TNM-type Al-Ti-Nb-Mo γ alloys at heat-treatment temperatures is quantitatively studied using the Thermo-Calc program package and experimental methods. Isothermal cross sections are calculated and the joint influence of two alloying elements on the phase composition of the alloy is determined at the mean concentration of a third component. Based on the calculations of vertical cross sections, the boundaries of the four-phase eutectoid reaction α → α2 + β + γ are found. The temperature is shown to significantly influence the phase compositions of the γ alloys, among them the mass fractions of various phases (α, β, γ,α2) and the element concentration in them.

COMPOSITION OF MINERAL PHASES OF THE GHIDIRIM DIATOMITE

Directory of Open Access Journals (Sweden)

Vasile Rusu

2007-06-01

Full Text Available Studies of the mineralogical composition of diatomite from the Ghidirim location of RM, as well as of the extracted clay phase are presented. The mineral phase of the diatomite contains a number of clay minerals, like montmorillonite (in a mixture with insignificant quantities of slightly chloritized montmorillonite, illite and kaolinite. Diatomite contains also non-clay components as fine-dispersed quartz and amorphous material, the more probable sources of which are opal, amorphous alumosilicates, aluminum and iron hydroxides. The applied procedure for separation of clay fractions by sizing settling in liquid media proves to be very useful, enabling possibilities for more accurate identification of the clay constituents of diatomic material. Procedure allows to separate very clean clay fraction especially rich in montmorillonite, which can be utilized itself as mineral adsorbent for practical purposes.

Experimental and numerical investigation of form-stable dodecane/hydrophobic fumed silica composite phase change materials for cold energy storage

International Nuclear Information System (INIS)

Chen, Jiajie; Ling, Ziye; Fang, Xiaoming; Zhang, Zhengguo

2015-01-01

Highlights: • Form-stable dodecane/fumed silica composite for cold storage is prepared. • A suggesting hypothesis that explains infiltration mechanism is proposed. • The performance of the composite phase change material is investigated. • Numerical simulation of system is carried out and results fit well. - Abstract: A kind of form-stable composite phase change materials used for cold thermal energy storage is prepared by absorbing dodecane into the hydrophobic fumed silica. With relatively suitable pore diameter and hydrophobic groups, hydrophobic fumed silica is beneficial to the penetration and infiltration of dodecane and the leakage problem solving. Scanned by electron micrographs and Fourier transformation infrared, the composite phase change material is characterized to be just physical penetration. Besides, the differential scanning calorimeter and thermo gravimetric analysis reveals the high enthalpy, good thermal stability and cycling performance of this composite phase change material. What’s more, Hot-Disk thermal constants analyzer demonstrates that the composite phase change material has low thermal conductivity which is desired in cold storage application. In the experiment, a cold energy storage system is set up and the results from the experiment show that the system has excellent performance of cold storage by incorporating composite phase change material. Apart from that, the experimental data is found to have a great agreement with the numerical simulation which is carried out by using the commercial computational fluid dynamics software FLUENT.

Aqueous preparation of polyethylene glycol/sulfonated graphene phase change composite with enhanced thermal performance

International Nuclear Information System (INIS)

Li, Hairong; Jiang, Ming; Li, Qi; Li, Denian; Chen, Zongyi; Hu, Waping; Huang, Jing; Xu, Xizhe; Dong, Lijie; Xie, Haian; Xiong, Chuanxi

2013-01-01

Highlights: • We report an aqueous preparation technique of PEG/graphene phase change composite. • Hydrophilic sulfonated graphene (SG) nanosheets were synthesized. • Large increase in thermal conductivity is attained at low SG loading. • High latent heat is retained due to the low filler loading. • Affinity between SG and PEG contributes to the enhanced thermal performance. - Abstract: A polyethylene glycol (PEG)/sulfonated graphene (SG) phase change composite with enhanced thermal performance was prepared by solution processing in aqueous medium. It is remarkable that the addition of only 4 wt.% of SG to PEG could lead to a four times higher increase in thermal conductivity and a slight decrease in the phase change enthalpy, which is attributed to the formation of efficient thermal conductive network within the PEG matrix relevant to the excellent thermal property and unique 2-dimensional morphology of graphene as well as strong interface affinity between PEG matrix and SG nanosheets. The aqueous preparation technique is expected to pioneer a new way to prepare environment friendly organic phase change materials, and the production of PEG/SG composites is potentially scalable due to the facile fabricating process

Methods of chemical and phase composition analysis of gallstones

Science.gov (United States)

Suvorova, E. I.; Pantushev, V. V.; Voloshin, A. E.

2017-11-01

This review presents the instrumental methods used for chemical and phase composition investigation of gallstones. A great body of data has been collected in the literature on the presence of elements and their concentrations, obtained by fluorescence microscopy, X-ray fluorescence spectroscopy, neutron activation analysis, proton (particle) induced X-ray emission, atomic absorption spectroscopy, high-resolution gamma-ray spectrometry, electron paramagnetic resonance. Structural methods—powder X-ray diffraction, infrared spectroscopy, Raman spectroscopy—provide information about organic and inorganic phases in gallstones. Stone morphology was studied at the macrolevel with optical microscopy. Results obtained by analytical scanning and transmission electron microscopy with X-ray energy dispersive spectrometry are discussed. The chemical composition and structure of gallstones determine the strategy of removing stone from the body and treatment of patients: surgery or dissolution in the body. Therefore one chapter of the review describes the potential of dissolution methods. Early diagnosis and appropriate treatment of the disease depend on the development of clinical methods for in vivo investigation, which gave grounds to present the main characteristics and potential of ultrasonography (ultrasound scanning), magnetic resonance imaging, and X-ray computed tomography.

Phase 2B experimental design for the INEEL glass composition variation study

International Nuclear Information System (INIS)

Peeler, D.

2000-01-01

The U.S. Department of Energy's (DOE's) Offices of Science and Technology (through the Tanks Focus Area [TFA]) and Waste Management are sponsoring a partnership among Idaho National Engineering and Environmental Laboratory (INEEL), Pacific Northwest National Laboratory (PNNL), and the Savannah River Technology Center (SRTC) for a collaborative glass composition variation study (CVS). The purpose of the CVS is to investigate property - composition relationships within a glass-composition region compatible with the expected range of Idaho Nuclear Technology and Engineering Center (INTEC) high-activity wastes (HAWs). The CVS has been conducted in phases to allow INEEL, PNNL, and SRTC researchers to adjust the glass composition region of interest as flowsheet options are refined and/or waste-stream compositions become more defined

Study of phase changing characteristics of granular composites using differential scanning calorimetry

International Nuclear Information System (INIS)

Rady, Mohamed

2009-01-01

Characterization of the phase changing behavior of granular materials is an important issue for design and optimization of latent heat thermal energy storage (LHTES) systems. In the present work, differential scanning calorimetry (DSC) has been used to study the phase changing behavior of granular composites consisting of ceramic encapsulated phase change material (EPCM) with particle diameters of 1-3 mm. The obtained DSC curves characterizing melting and solidification of the composite material are shown to be dependent upon the values of heating and cooling rates. Direct utilization of the measured DSC curves could result in an inexact representation of the sample enthalpy change. A simple procedure has been advised to obtain accurate quantitative results from the DSC measurements based on the estimation of the thermal resistance between the sample and its enclosure. Analysis of the evolution of latent heat of EPCM with temperature at different values of cooling/heating rates is presented.

Mass flow discharge and total temperature characterisation of a pyrotechnic gas generator formulation for airbag systems

Energy Technology Data Exchange (ETDEWEB)

Neutz, Jochen; Koenig, Andreas [Fraunhofer Institut fuer Chemische Technologie ICT, Pfinztal (Germany); Knauss, Helmut; Jordan, Sebastian; Roediger, Tim; Smorodsky, Boris [Universitaet Stuttgart (Germany). Institut fuer Aerodynamik und Gasdynamik; Bluemcke, Erich Walter [AUDI AG, Department I/EK-523, Ingolstadt (Germany)

2009-06-15

The mass flow characteristics of gas generators for airbag applications have to comply with a number of requirements for an optimal deployment of the airbag itself. Up to now, the mass flow was determined from pressure time histories of so-called can tests. This procedure suffers from the missing knowledge on the temperature of the generated gas entering the can. A new test setup described in this paper could overcome this problem by providing highly time resolved information on the gas's total temperature and the mass flow of the generator. The test setup consisted of a combustion chamber with a specially designed Laval nozzle in combination with a temperature sensor of high time resolution. The results showed a high time resolved temperature signal, which was disturbed by the formation of a slag layer on the sensor. Plausibility considerations with experimentally and thermodynamically determined combustion temperatures led to satisfying results for the overall temperature as characteristic parameter of airbag inflating gases flows from pyrotechnics. (Abstract Copyright [2009], Wiley Periodicals, Inc.)

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.

Stearic-acid/carbon-nanotube composites with tailored shape-stabilized phase transitions and light–heat conversion for thermal energy storage

International Nuclear Information System (INIS)

Li, Benxia; Nie, Shibin; Hao, Yonggan; Liu, Tongxuan; Zhu, Jinbo; Yan, Shilong

2015-01-01

Highlights: • A facile preparation of shape-stabilized composite PCMs for thermal energy storage. • The composite PCMs present tunable phase change temperatures and enthalpy. • Sunlight-driven phase change for photothermal conversion and storage. - Abstract: The development of functional materials with both light–heat conversion and thermal energy storage properties is of crucial importance for efficient utilization of sunlight to meet the growing demand for sustainable energy. In this work, the shape-stabilized phase change composites were designed and prepared by integration of stearic acid (SA) and acid-treated carbon nanotubes (a-CNTs). The a-CNTs not only acted as a flexible matrix but also endowed the composites high light–heat conversion ability. The reversible phase transitions shifted from high temperatures (T m = 74 °C, T f = 57 °C) of pure SA to near room temperature (T m = ∼30 °C, T f = ∼22 °C) of SA/a-CNTs composites, probably resulting from the strong interface confinement effect. The phase change enthalpy of the SA/a-CNTs composite could also be tailored by changing the mass ratio of SA and a-CNTs. The composites containing SA of 54.2 wt.%, 67.8 wt.% and 79.5 wt.% presented the melting enthalpy of 76.3 J/g, 98.8 J/g and 111.8 J/g, respectively. Moreover, the phase transition of SA/a-CNTs composite could be driven by sunlight for the energy storage/release. Therefore, this research provides a new platform for improving solar utilization, and understanding the phase transition behaviors of organic PCMs in dimensionally confined environments as well

Cold storage condensation heat recovery system with a novel composite phase change material

International Nuclear Information System (INIS)

Xia, Mingzhu; Yuan, Yanping; Zhao, Xudong; Cao, Xiaoling; Tang, Zhonghua

2016-01-01

Highlights: • Cold storage condensation heat recovery system using PCM was proposed. • CW with a phase change temperature of nearly 80 °C was selected as the potential PCM. • The optimal mass ratio between the CW and EG was 10:1. • The thermal and physical performances of the CW/EG were investigated. • The thermal reliability was demonstrated by 1000 cycles. - Abstract: Using condensation heat from cold storage refrigeration systems to provide heat for domestic hot water preparation and industrial hot water supply promotes energy conservation. However, few studies have investigated cold storage condensation heat recovery using phase change materials (PCMs). In this study, a cold storage condensation heat recovery system that uses PCMs has been designed and analysed. According to the principle of energy cascade recycling, different operation modes could be effectively switched to recycle condensation heat. Furthermore, a novel and suitable phase change composite material is developed for cold storage condensation heat recovery, which has a relatively large latent heat, high thermal conductivity, and an appropriate phase change temperature (i.e. 80 °C). With carnauba wax (CW) as the PCM and expanded graphite (EG) as the additive, a composite was developed with an optimal mass ratio of CW:EG = 10:1. The thermal and physical properties and the interior structure of the composite were then investigated using a scanning electron microscope (SEM), thermal constants analyser (Hot Disk), differential scanning calorimeter (DSC), and Fourier transform infrared spectrometer (FT-IR). Furthermore, experiments on the melting and solidification processes and accelerated thermal cycling were also conducted. It was found that at the optimal mass ratio of 10:1, the temperatures of the CW/EG composite in the melting and solidification processes were 81.98 °C and 80.43 °C, respectively, while the corresponding latent heats were 150.9 J/g and 142.6 J/g, respectively

A functional form-stable phase change composite with high efficiency electro-to-thermal energy conversion

International Nuclear Information System (INIS)

Wu, Wenhao; Huang, Xinyu; Li, Kai; Yao, Ruimin; Chen, Renjie; Zou, Ruqiang

2017-01-01

Graphical abstract: The thermal conductivity of PU was enhanced to 43 times of the pristine value by encapsulation in a PGF, PU@PGF can be used for highly efficient electro-to-heat energy conversion and storage with the highest energy storage efficiency up to 85%. - Highlights: • The composite exhibits an in-situ solid-solid phase change behavior. • The enthalpy of polyurethane is enhanced within the matrix. • The thermal conductivity of the composite is 43 times as much as that of the polyurethane. • Supercooling of polyurethane is greatly reduced. • The composite is applied to cold protection as a wear layer. - Abstract: A novel solid-to-solid phase change composite brick was prepared by combination of polyurethane (PU) and pitch-based graphite foam (PGF). The carbonaceous support, which can be used for mass production, not only greatly improves the thermal conductivity but promote electro-to-heat conversion efficiency of organic phase change materials (PCMs). Our composite retained the enthalpy of PCM and exhibited a greatly reduced supercooling temperature. The novel composite was investigated by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and scanning electron microscope (SEM). The enthalpy of polyurethane has increased about 8.6% after infiltrating into graphite foam. The composite was very stable during thermal cycle test, and the electro-to-heat conversion efficiency achieves to 85% at lower voltages (1.5–1.8 V), which can vastly reduce energy consumption. The as-prepared composite was used in a wear layer to test its performance comparing with normal fabric.

MAX Phase Modified SiC Composites for Ceramic-Metal Hybrid Cladding Tubes

International Nuclear Information System (INIS)

Jung, Yang-Il; Kim, Sun-Han; Park, Dong-Jun; Park, Jeong-Hwan; Park, Jeong-Yong; Kim, Hyun-Gil; Koo, Yang-Hyun

2015-01-01

A metal-ceramic hybrid cladding consists of an inner zirconium tube, and an outer SiC fiber-matrix SiC ceramic composite with surface coating as shown in Fig. 1 (left-hand side). The inner zirconium allows the matrix to remain fully sealed even if the ceramic matrix cracks through. The outer SiC composite can increase the safety margin by taking the merits of the SiC itself. In addition, the outermost layer prevents the dissolution of SiC during normal operation. On the other hand, a ceramic-metal hybrid cladding consists of an outer zirconium tube, and an inner SiC ceramic composite as shown in Fig. 1 (right-hand side). The outer zirconium protects the fuel rod from a corrosion during reactor operation, as in the present fuel claddings. The inner SiC composite, additionally, is designed to resist the severe oxidation under a postulated accident condition of a high-temperature steam environment. Reaction-bonded SiC was fabricated by modifying the matrix as the MAX phase. The formation of Ti 3 SiC 2 was investigated depending on the compositions of the preform and melt. In most cases, TiSi 2 was the preferential phase because of its lowest melting point in the Ti-Si-C system. The evidence of Ti 3 SiC 2 was the connection with the pressurizing

Application of Ultrasonic Phased Array Technology to the Detection of Defect in Composite Stiffened-structures

Science.gov (United States)

Zhou, Yuan-Qi; Zhan, Li-Hua

2016-05-01

Composite stiffened-structure consists of the skin and stringer has been widely used in aircraft fuselage and wings. The main purpose of the article is to detect the composite material reinforced structure accurately and explore the relationship between defect formation and structural elements or curing process. Based on ultrasonic phased array inspection technology, the regularity of defects in the manufacture of composite materials are obtained, the correlation model between actual defects and nondestructive testing are established. The article find that the forming quality of deltoid area in T-stiffened structure is obviously improved by pre-curing, the defects of hat-stiffened structure are affected by the mandrel. The results show that the ultrasonic phased array inspection technology can be an effectively way for the detection of composite stiffened-structures, which become an important means to control the defects of composite and improve the quality of the product.

Chemical and phase composition of powders obtained by electroerosion dispersion from alloys WC-Co

International Nuclear Information System (INIS)

Putintseva, M.N.

2004-01-01

A consideration is given to the dependence of chemical and phase compositions of dispersed powders on the conditions, the medium of electroerosion dispersing and the content of cobalt in an initial alloy. It is shown that dissociation of carbon from tungsten carbide proceeds even on dispersing in liquid hydrocarbon-containing media (kerosene and machine oil). The phase composition is determined to a large extent by a medium of dispersing and a cobalt content in the initial alloy. In all powders complex tungsten-cobalt carbides and even Co 7 W 6 intermetallic compounds are found [ru

Chemical and Phase Composition of Powders Obtained by Electroerosion Dispersion from WC - Co Alloys

Science.gov (United States)

Putintseva, M. N.

2004-03-01

The dependence of the chemical and phase composition of dispersed powders on the mode and medium of electroerosion dispersion and the content of cobalt in the initial alloy is considered. It is shown that the dissociation of carbon from tungsten carbide occurs even in dispersion in liquid hydrocarbon-bearing media (kerosene and industrial oils). The phase composition is primarily determined by the dispersion medium and the content of cobalt in the initial alloy. Compound tungsten-cobalt carbides and even a Co7W6 intermetallic are determined in all the powders.

Preparation and properties of lauric acid/silicon dioxide composites as form-stable phase change materials for thermal energy storage

International Nuclear Information System (INIS)

Fang Guiyin; Li Hui; Liu Xu

2010-01-01

Form-stable lauric acid (LA)/silicon dioxide (SiO 2 ) composite phase change materials were prepared using sol-gel methods. The LA was used as the phase change material for thermal energy storage, with the SiO 2 acting as the supporting material. The structural analysis of these form-stable LA/SiO 2 composite phase change materials was carried out using Fourier transformation infrared spectroscope (FT-IR). The microstructure of the form-stable composite phase change materials was observed by a scanning electronic microscope (SEM). The thermal properties and thermal stability were investigated by a differential scanning calorimeter (DSC) and a thermogravimetric analysis apparatus (TGA), respectively. The SEM results showed that the LA was well dispersed in the porous network of SiO 2 . The DSC results indicated that the melting latent heat of the form-stable composite phase change material is 117.21 kJ kg -1 when the mass percentage of the LA in the SiO 2 is 64.8%. The results of the TGA showed that these materials have good thermal stability. The form-stable composite phase change materials can be used for thermal energy storage in waste heat recovery and solar heating systems.

Probing the phase composition of silicon films in situ by etch product detection

International Nuclear Information System (INIS)

Dingemans, G.; Donker, M. N. van den; Gordijn, A.; Kessels, W. M. M.; Sanden, M. C. M. van de

2007-01-01

Exploiting the higher etch probability for amorphous silicon relative to crystalline silicon, the transiently evolving phase composition of silicon films in the microcrystalline growth regime was probed in situ by monitoring the etch product (SiH 4 ) gas density during a short H 2 plasma treatment step. Etch product detection took place by the easy-to-implement techniques of optical emission spectroscopy and infrared absorption spectroscopy. The phase composition of the films was probed as a function of the SiH 4 concentration during deposition and as a function of the film thickness. The in situ results were corroborated by Raman spectroscopy and solar cell analysis

Role of the polymer phase in the mechanics of nacre-like composites

Science.gov (United States)

Niebel, Tobias P.; Bouville, Florian; Kokkinis, Dimitri; Studart, André R.

2016-11-01

Although strength and toughness are often mutually exclusive properties in man-made structural materials, nature is full of examples of composite materials that combine these properties in a remarkable way through sophisticated multiscale architectures. Understanding the contributions of the different constituents to the energy dissipating toughening mechanisms active in these natural materials is crucial for the development of strong artificial composites with a high resistance to fracture. Here, we systematically study the influence of the polymer properties on the mechanics of nacre-like composites containing an intermediate fraction of mineral phase (57 vol%). To this end, we infiltrate ceramic scaffolds prepared by magnetically assisted slip casting (MASC) with monomers that are subsequently cured to yield three drastically different polymers: (i) poly(lauryl methacrylate) (PLMA), a soft and weak elastomer; (ii) poly(methyl methacrylate) (PMMA), a strong, stiff and brittle thermoplastic; and (iii) polyether urethane diacrylate-co-poly(2-hydroxyethyl methacrylate) (PUA-PHEMA), a tough polymer of intermediate strength and stiffness. By combining our experimental data with finite element modeling, we find that stiffer polymers can increase the strength of the composite by reducing stress concentrations in the inorganic scaffold. Moreover, infiltrating the scaffolds with tough polymers leads to composites with high crack initiation toughness KIC. An organic phase with a minimum strength and toughness is also required to fully activate the mechanisms programmed within the ceramic structure for a rising R-curve behavior. Our results indicate that a high modulus of toughness is a key parameter for the selection of polymers leading to strong and tough bioinspired nacre-like composites.

A novel phase-change cement composite for thermal energy storage: Fabrication, thermal and mechanical properties

International Nuclear Information System (INIS)

Zhang, He; Xing, Feng; Cui, Hong-Zhi; Chen, Da-Zhu; Ouyang, Xing; Xu, Su-Zhen; Wang, Jia-Xin; Huang, Yi-Tian; Zuo, Jian-Dong; Tang, Jiao-Ning

2016-01-01

Highlights: • A novel flaky graphite-doped phase-change microcapsule (FGD-MPCM) was prepared. • FGD-MPCM has substantial latent heat storage capacity (135.8 J/g). • FGD-MPCMs/cement composite is capable of reducing indoor temperature fluctuation. • Compressive strength of cement composite with 30% FGD-MPCMs can reach to 14.2 MPa. - Abstract: Facing upon the increasingly severe energy crisis, one of the key issues for reducing the building energy consumption is to pursue high-performance thermal energy storage technologies based on phase-change materials. In this study, a novel cement composite incorporated with flaky graphite-doped microencapsulated phase-change materials (FGD-MPCMs) was developed. Various techniques, such as field emission-scanning electron microscopy (FE-SEM), optical microscopy (OM), X-ray diffraction (XRD), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were used to analyse the composite structure and thermal performances. The results indicate that the spherical microcapsules are well dispersed in the cement matrix. When combined within the cement, the thermal stability of the microcapsules was highly improved, and the inclusion of greater amounts of FGD-MPCMs further increased the latent heat of the composite. The mechanical properties of the cement composites were affected with the increase of FGD-MPCMs dosage and the porosity of the composites. In spite of this, the compressive strength and flexural strength of the cement composite with 30% FGD-MPCM could still reach to as high as 14.2 MPa and 4.1 MPa, respectively. Results from the infrared thermography and the model room test suggested that the composite filled with FGD-MPCMs is capable of reducing indoor temperature fluctuation and exhibits good potential for application in buildings to enhance energy savings and thermal comfort.

Study on polyethylene glycol/epoxy resin composite as a form-stable phase change material

International Nuclear Information System (INIS)

Fang Yutang; Kang Huiying; Wang Weilong; Liu Hong; Gao Xuenong

2010-01-01

Form-stable polyethylene glycol (PEG)/epoxy resin (EP) composite as a novel phase change material (PCM) was prepared using casting molding method. In this new material, PEG acts as the latent heat storage material and EP polymer serves as the supporting material, which provides structural strength and prevents the leakage of the melted PEG. The structure and morphology of the novel composite were observed using Fourier transformation infrared spectroscope (FTIR) and scanning electronic microscope (SEM). The thermo-mechanical property and transition behavior were characterized by polarizing optical microscope (POM), static thermo-mechanical analysis (TMA) and differential scanning calorimeter (DSC). The experimental results show that, as a result of the physical tangled function of the epoxy resin carrier to the PEG segment, the composite macroscopically presents the solid-solid phase change characteristic.

Thermophysical properties estimation of paraffin/graphite composite phase change material using an inverse method

International Nuclear Information System (INIS)

Lachheb, Mohamed; Karkri, Mustapha; Albouchi, Fethi; Mzali, Foued; Nasrallah, Sassi Ben

2014-01-01

Highlights: • Preparation of paraffin/graphite composites by uni-axial compression technique. • Measurement of thermophysical properties of paraffin/graphite using the periodic method. • Measurement of the experimental densities of paraffin/graphite composites. • Prediction of the effective thermal conductivity using analytical models. - Abstract: In this paper, two types of graphite were combined with paraffin in an attempt to improve thermal conductivity of paraffin phase change material (PCM): Synthetic graphite (Timrex SFG75) and graphite waste obtained from damaged Tubular graphite Heat Exchangers. These paraffin/graphite phase change material (PCM) composites are prepared by the cold uniaxial compression technique and the thermophysical properties were estimated using a periodic temperature method and an inverse technique. Results showed that the thermal conductivity and thermal diffusivity are greatly influenced by the graphite addition

Calcium phosphate composite cements based on simple mixture of brushite and apatite phases

Science.gov (United States)

Egorov, A. A.; Fedotov, A. Yu; Pereloma, I. S.; Teterina, A. Yu; Sergeeva, N. S.; Sviridova, I. K.; Kirsanova, V. A.; Akhmedova, S. A.; Nesterova, A. V.; Reshetov, I. V.; Barinov, S. M.; Komlev, V. S.

2018-04-01

The composite cements based on simple mixtures brishite and apatite with ratio 70/30, 50/50, 30/70 were developed. The processes of phase formation, microstructure and mechanical properties were studied. The kinetics of degradation in simulated body fluid depending on the microstructure and the materials phase composition was carried out. The biological test in vitro were performed using the MTT-test on the human fibroblast immortalized (hFB) cell line and the human osteosarcoma cell line MG-63. The materials didn’t have acute cytoxicity and possessed surface matrix properties. It was determined that the both line of cells actively proliferated, with viable cells values higher 20-60 % then control at all observation periods.

IDENTIFICATION OF PHASE COMPOSITION OF BINDERS FROM ALKALI-ACTIVATED MIXTURES OF GRANULATED BLAST FURNACE SLAG AND FLY ASH

Directory of Open Access Journals (Sweden)

JOZEF VLČEK

2014-03-01

Full Text Available The prepared alkali-activated binders (AAB and composites using suitable latent hydraulic raw materials represent an alternative to materials based on Portland cements. This paper deals with ways how to influence the functional parameters of AAB by setting up mixtures of granulated blast furnace slag (GBFS and fly ash with selected chemical compositions. In this way the course of hydration process is modified and the phase composition of products of alkali activation is changed as well as their final properties. The amorphous character of the hydration products makes evaluation of the phase composition of hardened AAB difficult and significantly limits the number of experimental techniques suitable to characterise their phase composition. It was observed that measuring the pH of water extracts obtained from the alkali-activated mixtures can give supplementary information about the process of hardening of alkali-activated mixtures of GBFS and fly ash.

Evaluation of calcination temperature and phase composition ratio for new hyroxyapatite

Science.gov (United States)

Salimi, M. N. Ahmad; Chin, H. S.

2017-10-01

The demand of production of hydroxyapatite (HA) has been increasing for the purpose of medical and dental application. HA possesses the excellent properties leads to the priority choice for ceramic bone replacement. Synthesis route by wet chemical precipitation is commonly practised in industrial scale. Calcium hydroxide and Orthophosphoric acid are the precursors for production scale. The synthesis of HA is conducted by varying the synthetic condition: stirring rate, calcium-phosphate and calcination temperature. This paper is focused on the properties of HA produced by regulating the synthetic condition so that the qualities of HA can be well performed. Characterization studies were also carried out by Fourier Transform Infrared Spectroscopy (FT-IR) for functional group identification, Scanning Electron Microscope (SEM) for surface morphology analysis and X-Ray Diffraction (XRD) for phase composition and crystallinity respectively. Narrow particle size distribution contributed to better quality of hydroxyapatite for bone replacement. Both calcium-phosphate ratio and calcination temperature would affect the phase composition of calcium phosphate.

In-situ studies of stress- and magnetic-field-induced phase transformation in a polymer-bonded Ni-Co-Mn-In composite

International Nuclear Information System (INIS)

Liu, D.M.; Nie, Z.H.; Wang, G.; Wang, Y.D.; Brown, D.E.; Pearson, J.; Liaw, P.K.; Ren, Y.

2010-01-01

A polymer-bonded Ni 45 Co 5 Mn 36.6 In 13.4 ferromagnetic shape-memory composite was fabricated, having magnetic-field-driven shape recovery properties. The thermo-magnetization curves of the composite suggested that the magnetic-field-induced reverse martensitic transformation occurs in the composite. The effects of temperature, stress, and magnetic-field on the phase transformation properties were systematically investigated using an in-situ high-energy X-ray diffraction technique. A temperature-induced reversible martensitic phase transformation was confirmed within the composite, showing a broad phase transformation interval. Stress-induced highly textured martensite was observed in the composite during uniaxial compressive loading, with a residual strain after unloading. The origin of the textured martensite can be explained by the grain-orientation-dependent Bain distortion energy. A recovery strain of ∼1.76% along the compression direction was evidenced in the pre-strained composite with an applied magnetic-field of 5 T. This recovery was caused by the magnetic-field-induced reverse martensitic phase transformation. The phase transformation properties of the ferromagnetic shape-memory composite, different from its bulk alloys, can be well explained by the Clausius-Clapeyron relation. The large magnetic-field-induced strain, together with good ductility and low cost, make the polymer-bonded Ni-Co-Mn-In composites potential candidates for magnetic-field-driven actuators.

The effect of dolomite type and Al2O3 content on the phase composition in aluminous cements containing spinel

Directory of Open Access Journals (Sweden)

R. Naghizadeh

2011-06-01

Full Text Available In this paper, the effect of dolomite type and Al2O3 content on the phase composition in aluminous cements containing MA spinel is investigated. For this reason, the raw and calcined dolomites are used as raw materials along with calcined alumina in the preparation of the cement. Then, different compositions are prepared at 1350°C using the sintering method and their mineralogical compositions are investigated using the diffractometric technique. Also, their microstructures arre evaluated. The results indicate that raw materials used have great effect on the type and amount of formed phases in cement composition. Independently of the dolomite type used, a mixed phase product consisting of spinel accompanied by CA and CA2 is obtained. The content of CA phase in the cement composition is decreased with increasing of Al2O3 in the raw materials composition. On the other hand, the content of CA2 phase is increased with the addition of Al2O3. In addition, the results show that the formation of C12A7 is favored by use of calcined dolomite.

Body composition, symptoms, and survival in advanced cancer patients referred to a phase I service.

Directory of Open Access Journals (Sweden)

Henrique A Parsons

Full Text Available Body weight and body composition are relevant to the outcomes of cancer and antineoplastic therapy. However, their role in Phase I clinical trial patients is unknown.We reviewed symptom burden, body composition, and survival in 104 patients with advanced cancer referred to a Phase I oncology service. Symptom burden was analyzed using the MD Anderson Symptom Assessment Inventory(MDASI; body composition was evaluated utilizing computerized tomography(CT images. A body mass index (BMI≥25 kg/m² was considered overweight. Sarcopenia, severe muscle depletion, was assessed using CT-based criteria.Most patients were overweight (n = 65, 63%; 53 patients were sarcopenic (51%, including 79% of patients with a BMI<25 kg/m² and 34% of those with BMI≥25 kg/m². Sarcopenic patients were older and less frequently African-American. Symptom burden did not differ among patients classified according to BMI and presence of sarcopenia. Median (95% confidence interval survival (days varied according to body composition: 215 (71-358 (BMI<25 kg/m²; sarcopenic, 271 (99-443 (BMI<25 kg/m²; non-sarcopenic, 484 (286-681 (BMI≥25 kg/m²; sarcopenic; 501 d (309-693 (BMI≥25 kg/m²; non-sarcopenic. Higher muscle index and gastrointestinal cancer diagnosis predicted longer survival in multivariate analysis after controlling for age, gender, performance status, and fat index.Patients referred to a Phase I clinic had a high frequency of sarcopenia and a BMI≥25 kg/m², independent of symptom burden. Body composition variables were predictive of clinically relevant survival differences, which is potentially important in developing Phase I studies.

Electromagnetic absorption behaviour of ferrite loaded three phase carbon fabric composites

Science.gov (United States)

Jagatheesan, Krishnasamy; Ramasamy, Alagirusamy; Das, Apurba; Basu, Ananjan

2018-02-01

This article investigates the electromagnetic absorption behaviours of carbon helical yarn fabric reinforced composites and manganese-zinc (Mn-Zn) ferrite particles loaded 3 phase fabric composites. A carbon helical yarn having stainless steel core was prepared and made into single jersey knitted fabric. The composite was prepared by sandwiching a fabric with polypropylene films and thermal pressed. The absorption values of helical yarn fabric composite was observed to be less in the C band region (4-8 GHz). For improving the absorption coefficients of composite, Mn-Zn ferrite particles were dispersed in the polypropylene (PP) composite. The ferrite loaded PP composites exhibited better permittivity and permeability values, hence the absorption loss of the composite was improved. The helical yarn fabric reinforced with Mn-Zn ferrite/PP composite showed larger absorption coefficients than virgin PP/fabric composite. The change in thermal stability and particle size distribution in the Mn-Zn ferrite/PP composite was also analyzed. At higher ferrite concentration, bimodal particle distribution was observed which increased the conductivity and shielding effectiveness (SE) of the composite. In addition, complex permittivity value was also increased for higher incident frequency (4-8 GHz). As the ferrite content increases, the dielectric loss and magnetic permeability of PP/ferrite increases due to increased magnetic loss. Hence, ferrite loaded PP composite showed the total SE of -14.2 dB with the absorption coefficients of 0.717. The S1C7 fabric composite having ferrite dispersion showed the better absorption loss and lower reflection coefficient of 14.2 dB and 0.345 respectively compared to virgin PP/helical yarn fabric composite. The increasing ferrite content (45 wt%) improved the absorption loss and total SE. Though, ferrite based fabric composite exhibits moderate absorptive shielding, it can be used as shielding panels in the electronic industries.

Study on preparation of montmorillonite-based composite phase change materials and their applications in thermal storage building materials

International Nuclear Information System (INIS)

Fang Xiaoming; Zhang Zhengguo; Chen Zhonghua

2008-01-01

Three composite phase change materials (PCMs) were prepared by blending butyl stearate, dodecanol and RT20 with an organically modified montmorillonite (MMT), respectively. After the three composite PCMs were characterized by DSC, it was indicated that the RT20/MMT composite PCM was a good candidate for building applications due to its large latent heat, suitable phase change temperature and good performance stability. Compared with RT20, the RT20/MMT composite PCM exhibited higher heat transfer efficiency and had good compatibility with gypsum due to the combination with MMT. The composite gypsum boards containing RT20/MMT composite PCM had the function of reducing building energy consumption by reducing the indoor temperature variation, and the function was enhanced with the increase in the mass ratio of the RT20/MMT composite PCM

Characterisation of phase composition, microstructure and microhardness of electroless nickel composite coating co-deposited with SiC on casting aluminium LM24 alloy substrate

OpenAIRE

Franco, M.; Sha, Wei; Malinov, Savko

2013-01-01

Electroless Ni-P (EN) and composite Ni-P-SiC (ENC) coatings were developed on cast aluminium alloy, LM24. The coating phase composition, microstructure and microhardness were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM) and microhardness tester, respectively, on as-plated and heat-treated specimens. The original microstructure of the Ni-P matrix is not affected by the inclusion of the hard particles SiC. No formation of Ni-Si phase was observed upto 500°C of ...

Competing magnetic interactions and low temperature magnetic phase transitions in composite multiferroics

International Nuclear Information System (INIS)

Borkar, Hitesh; Singh, V N; Kumar, Ashok; Choudhary, R J; Tomar, M; Gupta, Vinay

2015-01-01

Novel magnetic properties and magnetic interactions in composite multiferroic oxides Pb[(Zr 0.52 Ti 0.48 ) 0.60 (Fe 0.67 W 0.33 ) .40 ]O 3 ] 0.80 –[CoFe 2 O 4 ] 0.20 (PZTFW–CFO) have been studied from 50 to 1000 Oe field cooled (FC) and zero field cooled (ZFC) probing conditions, and over a wide range of temperatures (4–350 K). Crystal structure analysis, surface morphology, and high resolution transmission electron microscopy images revealed the presence of two distinct phases, where micro- and nano-size spinel CFO were embedded in tetragonal PZTFW matrix and applied a significant built-in compressive strain (∼0.4–0.8%). Three distinct magnetic phase transitions were observed with the subtle effect of CFO magnetic phase on PZTFW magnetic phase transitions below the blocking temperature (T B ). Temperature dependence magnetic property m(T) shows a clear evidence of spin freezing in magnetic order with lowering in thermal vibration. Chemical inhomogeneity and confinement of nanoscale ferrimagnetic phase in paramagnetic/antiferromagnetic matrix restrict the long range interaction of spin which in turn develop a giant spin frustration. A large divergence in the FC and ZFC data and broad hump in ZFC data near 200 (±10) K were observed which suggests that large magnetic anisotropy and short range order magnetic dipoles lead to the development of superparamagnetic states in composite. (paper)

Influence of the composition of the aqueous phase on the behavior of the system FeCl3-HCl-DPE

International Nuclear Information System (INIS)

Ramirez, F. de M.; Jimenez-Reyes, M.

1981-07-01

We studied the influence of the aqueous phase composition upon an extraction system in which, at room temperature (20 0 C +- 3 0 C) using the dissolvents FeCl 3 -HCl-di-isopropyl ether the third phase phenomena is present after one minute of agitation. Our results showed that principally the hydrochloric acid dissolvent produced each of the three phases at given concentration levels as well as determined the nature of the chemical composition in each phase. (author)

Investigation of metal-matrix composite containing liquid-phase dispersion

Czech Academy of Sciences Publication Activity Database

Strunz, Pavel; Mukherji, D.; Gilles, R.; Geue, T.; Rösler, J.

2012-01-01

Roč. 340, 012098 (2012), s. 1-15 ISSN 1742-6588. [5th European Conference on Neutron Scattering. Praha, 17.07.2011-21.07.2011] R&D Projects: GA MPO FR-TI1/378 Grant - others:European Commission(XE) RII3-CT-2003-505925 Program:FP6 Institutional support: RVO:61389005 Keywords : metal-matrix composite * liquid-phase dispersion * strengthening * neutron diffraction Subject RIV: BM - Solid Matter Physics ; Magnetism http://iopscience.iop.org/1742-6596/340/1/012098

Effect of Strontium Nitrate on Extremely Slow Strobe Compositions

Science.gov (United States)

2017-01-01

Kauzlarich RESEARCH AND TECHNOLOGY DIRECTORATE January 2017 Approved for public release; distribution unlimited. Disclaimer The...g of a nitrate-based starter mixture was included on the top of each cube, with 3 in. of quick match (Precocious Pyrotechnics, Inc., Belgrade, MN

Ceramic fiber-reinforced monoclinic celsian phase glass-ceramic matrix composite material

Science.gov (United States)

Bansal, Narottam P. (Inventor); Dicarlo, James A. (Inventor)

1994-01-01

A hyridopolysilazane-derived ceramic fiber reinforced monoclinic celsian phase barium aluminum silicate glass-ceramic matrix composite material is prepared by ball-milling an aqueous slurry of BAS glass powder and fine monoclinic celsian seeds. The fibers improve the mechanical strength and fracture toughness and with the matrix provide superior dielectric properties.

Preparation, characterization and thermal properties of binary nitrate salts/expanded graphite as composite phase change material

Energy Technology Data Exchange (ETDEWEB)

Xiao, Junbing [School of Materials and Energy, Guangdong University of Technology, 510006 Guangzhou (China); Huang, Jin, E-mail: huangjiner@126.com [School of Materials and Energy, Guangdong University of Technology, 510006 Guangzhou (China); Zhu, Panpan; Wang, Changhong [School of Materials and Energy, Guangdong University of Technology, 510006 Guangzhou (China); Li, Xinxi [School of Materials and Energy, Guangdong University of Technology, 510006 Guangzhou (China); Center for Nanochemistry, Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Structural Chemistry of Unstable and Stable Species, College of Chemistry and Molecular Engineering, Peking University, Beijing (China)

2014-07-01

Highlights: • The expanded graphite enhanced thermal conductivity coefficient greatly. • The aqueous solution method adopting ultrasonic was utilized to disperse EG. • The combination of composite was physical without chemical reaction. • The reduction on total latent heat was slight after the adding EG. - Abstract: The binary nitrate salts/expanded graphite (EG) composite phase change material (PCM) were prepared via adding different mass rate of EG to binary nitrate salts consisting of NaNO{sub 3} and KNO{sub 3} (6:4) by aqueous solution method adopting ultrasonic. The morphology and chemical composition of EG and the composite PCM were characterized and investigated by X-ray diffraction (XRD), scan electron microscope (SEM), energy dispersive spectrometer (EDS), transmission electron microscope (TEM), respectively. Laser thermal conductivity instrument and differential scanning calorimeter (DSC) were employed to measure thermo physical properties. Drawing the conclusion from investigation, that EG had enhanced thermal conductivity coefficient which largely increased to 4.884 W/(m K) and reduced total latent heat by mostly 11.0%. The morphology and phase structure results indicated that EG were well dispersed into and physically combined with molten salts. In general, the prepared composite PCM could be a suitable phase change material for thermal energy storage.

Preparation, characterization and thermal properties of binary nitrate salts/expanded graphite as composite phase change material

International Nuclear Information System (INIS)

Xiao, Junbing; Huang, Jin; Zhu, Panpan; Wang, Changhong; Li, Xinxi

2014-01-01

Highlights: • The expanded graphite enhanced thermal conductivity coefficient greatly. • The aqueous solution method adopting ultrasonic was utilized to disperse EG. • The combination of composite was physical without chemical reaction. • The reduction on total latent heat was slight after the adding EG. - Abstract: The binary nitrate salts/expanded graphite (EG) composite phase change material (PCM) were prepared via adding different mass rate of EG to binary nitrate salts consisting of NaNO 3 and KNO 3 (6:4) by aqueous solution method adopting ultrasonic. The morphology and chemical composition of EG and the composite PCM were characterized and investigated by X-ray diffraction (XRD), scan electron microscope (SEM), energy dispersive spectrometer (EDS), transmission electron microscope (TEM), respectively. Laser thermal conductivity instrument and differential scanning calorimeter (DSC) were employed to measure thermo physical properties. Drawing the conclusion from investigation, that EG had enhanced thermal conductivity coefficient which largely increased to 4.884 W/(m K) and reduced total latent heat by mostly 11.0%. The morphology and phase structure results indicated that EG were well dispersed into and physically combined with molten salts. In general, the prepared composite PCM could be a suitable phase change material for thermal energy storage

Study of the formation of secondary phases in the composite LSM/YSZ

International Nuclear Information System (INIS)

Rodrigues, Ranieri Andrade

2007-01-01

The composite of strontium-doped lanthanum manganite (La 1-x SrxMnO 3 - LSM) and Yttria-stabilized zirconia (ZrO 2 /Y 2 O 3 - YSZ), is indicated as cathode of the Solid Oxide Fuel Cells (SOFC). It presents better acting as cathode due to the Triple Phase Boundary (TPB) formed in the interface area between the cathode and the electrolyte. For the temperatures up to 1100 deg C, LSM and YSZ can react producing lanthanum zirconate (La 2 Zr 2 O 7 - LZO) and strontium zirconate (SrZrO 3 - SZO). In this sense, the present work intends to contribute in the study of the formation of phases LZO and SZO, studying different massic proportions between LSM and YSZ with sintering temperatures varying between 1000 deg C and 1400 deg C. For the obtention of the precursory powders the co-precipitation routes were adopted to obtain YSZ and conventional powder mixture for the preparation of LSM. The composite LSM/YSZ, studied in this work, is prepared with two concentrations of Sr for LSM (30 mol por cent - LSM7 and 40 mol por cent - LSM6) and one concentration of Yttria for YSZ (10 mol por cent). The results obtained by X-ray fluorescence showed that the routes adopted for synthesis of powders were effective in the obtention of the compositions LSM6, LSM7 and YSZ, with close values to the stoichiometric. The studied massic proportions were: 50 por cent of LSM and 50 por cent of YSZ (1:1), 25 por cent of LSM and 75 por cent of YSZ (1:3), and 75 por cent of LSM and 25 por cent of YSZ (3:1). Such proportions of mixtures were conformed and submitted at different conditions of temperatures and times of sintering: 1000 deg C, 1200 deg C, 1300 deg C, 1350 deg C and 1400 deg C for 4 and 8 hours. The values of medium size of the particles and the specific surface area values for the mixture of LSM6/YSZ and LSM7/YSZ, are of the same order of largeness after the mixture in a attrition mill and in different massic proportions. Secondary phases like LZO and SZO were not found in the analysis for

Shape-stabilized phase change materials with high thermal conductivity based on paraffin/graphene oxide composite

International Nuclear Information System (INIS)

Mehrali, Mohammad; Latibari, Sara Tahan; Mehrali, Mehdi; Metselaar, Hendrik Simon Cornelis; Silakhori, Mahyar

2013-01-01

Highlights: ► The composite PCM was prepared with impregnation method. ► Shapes stabilized phase change material made with paraffin and GO composite. ► Determine effects of GO composite on shape stabilized PCM properties. ► The composite PCM has good thermal stability and form-stability. ► The composite PCM has much higher thermal conductivity than that of paraffin. - Abstract: This paper mainly focuses on the preparation, characterization, thermal properties and thermal stability and reliability of new form-stable composite phase change materials (PCMs) prepared by vacuum impregnation of paraffin within graphene oxide (GO) sheets. SEM and FT-IR techniques and TGA and DSC analysis are used for characterization of material and thermal properties. The composite PCM contained 48.3 wt.% of paraffin without leakage of melted PCM and therefore this composite found to be a form-stable composite PCM. SEM results indicate that the paraffin bounded into the pores of GO. FT-IR analysis showed there was no chemical reaction between paraffin and GO. Temperatures of melting and freezing and latent heats of the composite were 53.57 and 44.59 °C and 63.76 and 64.89 kJ/kg, respectively. Thermal cycling tests were done by 2500 melting/freezing cycling for verification of the form-stable composite PCM in terms of thermal reliability and chemical stability. Thermal conductivity of the composite PCM was highly improved from 0.305 to 0.985 (W/mk). As a result, the prepared paraffin/GO composite is appropriate PCM for thermal energy storage applications because of their acceptable thermal properties, good thermal reliability, chemical stability and thermal conductivities

Preparation of sulfur/multiple pore size porous carbon composite via gas-phase loading method for lithium-sulfur batteries

International Nuclear Information System (INIS)

Li, Long-Yan; Chen, Yan-Xiao; Guo, Xiao-Dong; Zhong, Ben-He; Zhong, Yan-Jun

2014-01-01

A porous carbon with multiple pore size distribution was synthesized, and regarded as a carrier to obtain the sulfur/carbon (S/C) composite via a gas-phase loading method. We proposed this novel gas-phase loading method by using a specially designed fluid-bed reactor to encapsulate and sequester gas-phase sulfur molecules into the porous carbon in current study. The nitrogen Brunauer-Emmett-Teller (BET), scanning electron microscopy (SEM) and X-ray powder diffraction (XRD) characterizations were investigated on both the porous carbon and the sulfur/carbon composite. The results show that the gas-phase loading method contributes to the combination of sulfur molecules and matrix porous carbon. Furthermore, the sulfur/multiple pore size distribution carbon composite based on the gas-phase loading method demonstrate an excellent electrochemical property. The initial specific discharge capacity is 795.0 mAh g −1 at 800 mA g −1 , with a capacity retention of 86.3% after 100 cycles

Benefit Analysis of Hybrid CNT/CFRP Composites in Future Aircraft Structures, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — During Phase I, Aurora Flight Sciences and N12 Technologies propose to conduct a comprehensive analysis of the benefits of hybrid composites in future aircraft...

Analysis and Testing of a Composite Fuselage Shield for Open Rotor Engine Blade-Out Protection

Science.gov (United States)

Pereira, J. Michael; Emmerling, William; Seng, Silvia; Frankenberger, Charles; Ruggeri, Charles R.; Revilock, Duane M.; Carney, Kelly S.

2016-01-01

The Federal Aviation Administration is working with the European Aviation Safety Agency to determine the certification base for proposed new engines that would not have a containment structure on large commercial aircraft. Equivalent safety to the current fleet is desired by the regulators, which means that loss of a single fan blade will not cause hazard to the Aircraft. The NASA Glenn Research Center and The Naval Air Warfare Center (NAWC), China Lake, collaborated with the FAA Aircraft Catastrophic Failure Prevention Program to design and test lightweight composite shields for protection of the aircraft passengers and critical systems from a released blade that could impact the fuselage. LS-DYNA® was used to predict the thickness of the composite shield required to prevent blade penetration. In the test, two composite blades were pyrotechnically released from a running engine, each impacting a composite shield with a different thickness. The thinner shield was penetrated by the blade and the thicker shield prevented penetration. This was consistent with pre-test LS-DYNA predictions. This paper documents the analysis conducted to predict the required thickness of a composite shield, the live fire test from the full scale rig at NAWC China Lake and describes the damage to the shields as well as instrumentation results.

HYSSOP COMPOSITION DEPENDING ON AGE AND PLANTS DEVELOPMENT PHASES

Directory of Open Access Journals (Sweden)

L. A. Kotyuk

2015-10-01

Full Text Available The aim of the paper is to research biochemical composition of Hyssopus officinalis L. (Lamiaceae in relation to plant age and phenological growth stage under conditions of Ukrainian Polissya, bin order to determine the optimal harvest dates of the herbal material and its application spheres. The raw material samples under analysis were cut at various growth stages: the vegetative, budding, blooming, ripening stages. To study the hyssop oil composition, areal parts of H. officinalis were used. The composition analysis was aimed at determining absolute dry matter (by drying samples at 105 °C up to the constant mass, “crude” cellulose, amounts of protein, fats, calcium, potassium, phosphorus, ascorbic acid, carotene, discernible sugars and tannins and essential oil. The present study has proved that in the plant ontogenesis the amount of essential oil, obtained from H. officinalis areal parts, does not markedly decrease: volatile oil yield in plants of the first, second and third years of life amounted to 1.007%, 0.75% and 0.71% respectively. The composition of volatile oil in the plants of the first year of life reveals 46 components, of which pinocampone (53.73%, isopinocampone (4.66% myrtenol (9.35% and camphor (3.86% prevailed. In H. officinalis volatile oil of the third year 30 components were identified, the prevailing of which were isopinocampone (44.43%, pinocampone (35.49%, myrtenol (5.26%, germacrene D (3.15%, pulegone (2.93% and bicyclogermacrene (1.35%. We could observe the change in the quantitative and qualitative composition of H. officinalis volatile oil throughout the entire vegetation period. Thus, in the phase of vegetative growth one can identify 25 compounds, the most predominant being elemol (33.25%, germacren D (21.59% and bicyclogermacrene (15.78%. In the phase of blossoming 30 components can be identified, a high amount of isopinocampone and pinocampone (44.43% and 35.49% and somewhat lover amount of myrtenol (5

Study on thermal property of lauric–palmitic–stearic acid/vermiculite composite as form-stable phase change material for energy storage

Directory of Open Access Journals (Sweden)

Nan Zhang

2015-09-01

Full Text Available The form-stable composite phase change material of lauric–palmitic–stearic acid ternary eutectic mixture/vermiculite was prepared by vacuum impregnation method for thermal energy storage. The maximum mass fraction of lauric–palmitic–stearic acid ternary eutectic mixture retained in vermiculite was determined as 50 wt% without melted phase change material seepage from the composite phase change material. Fourier transformation infrared spectroscope and scanning electron microscope were used to characterize the structure and morphology of the prepared lauric–palmitic–stearic acid ternary eutectic mixture/vermiculite form-stable composite phase change material, and the results indicate that lauric–palmitic–stearic acid ternary eutectic mixture was well confined into the layer porous structure of vermiculite by physical reaction. The melting and freezing temperatures and latent heats were measured by differential scanning calorimeter as 31.4°C and 30.3°C, and 75.8 and 73.2 J/g, respectively. Thermal cycling test showed that there was no significant change in the thermal properties of lauric–palmitic–stearic acid ternary eutectic mixture/vermiculite form-stable composite phase change material after 1000 thermal cycles. Moreover, 2 wt% expanded graphite was added to improve the thermal conductivity of lauric–palmitic–stearic acid ternary eutectic mixture/vermiculite form-stable composite phase change material. All results indicated that the prepared lauric–palmitic–stearic acid ternary eutectic mixture/vermiculite form-stable composite phase change material had suitable thermal properties and good thermal reliability for the application of thermal energy storage in building energy efficiency.

Understanding pyrotechnic shock dynamics and response attenuation over distance

Science.gov (United States)

Ott, Richard J.

Pyrotechnic shock events used during stage separation on rocket vehicles produce high amplitude short duration structural response that can lead to malfunction or degradation of electronic components, cracks and fractures in brittle materials, local plastic deformation, and can cause materials to experience accelerated fatigue life. These transient loads propagate as waves through the structural media losing energy as they travel outward from the source. This work assessed available test data in an effort to better understand attenuation characteristics associated with wave propagation and attempted to update a historical standard defined by the Martin Marietta Corporation in the late 1960's using out of date data acquisition systems. Two data sets were available for consideration. The first data set came from a test that used a flight like cylinder used in NASA's Ares I-X program, and the second from a test conducted with a flat plate. Both data sets suggested that the historical standard was not a conservative estimate of shock attenuation with distance, however, the variation in the test data did not lend to recommending an update to the standard. Beyond considering attenuation with distance an effort was made to model the flat plate configuration using finite element analysis. The available flat plate data consisted of three groups of tests, each with a unique charge density linear shape charge (LSC) used to cut an aluminum plate. The model was tuned to a representative test using the lowest charge density LSC as input. The correlated model was then used to predict the other two cases by linearly scaling the input load based on the relative difference in charge density. The resulting model predictions were then compared with available empirical data. Aside from differences in amplitude due to nonlinearities associated with scaling the charge density of the LSC, the model predictions matched the available test data reasonably well. Finally, modeling best

PHYSICOCHEMICAL PROPERTIES OF THE SOLID COMPONENT OF WELDING AEROSOL. I. PHASE COMPOSITION

Directory of Open Access Journals (Sweden)

T. L. Rakitskaya

2015-02-01

Full Text Available The phase composition of the solid component of welding aerosol (SCWA obtained as a result of metal welding with electrodes of ANO-4 and TsL-11 types manufactured according to ISO 2560 E432R 21 and ISO E19.9NbB20 standards, respectively, and differing in com-position of their wires and coatings was determined with the help of a Siemens D500 diffrac- a Siemens D500 diffrac-tometer supplied with the manufacturer’s software. Four and thirteen phases were identified in SCWA-ANO-4 and SCWA-TsL-11, respectively. Evaluation of crystallite sizes by the use of the Scherer equation showed that the crystallites formed in the course of welding with a TsL-11 type electrode are larger than those in the case of an ANO-4 type one: 65-89 nm and 30-49 nm, respectively.

Phase composition of iron-rich R-Fe-Si (R=Dy, Ho, Er) alloys

International Nuclear Information System (INIS)

Ivanova, G.V.; Makarova, G.M.; Shcherbakova, E.V.; Belozerov, E.V.

2005-01-01

Phase composition is studied in iron-rich alloys of R-Fe-Si (R=Dy, Ho, Er). In the as-cast state R 2 (Fe, Si) 17 of type Th 2 Ni 17 and R(Fe, Si) 12 compounds are observed; in the alloys of rated composition of R(Fe 0.85 Si 0.15 ) 8.5 (R=Dy, Er) a compound R 2 (Fe, Si) 17 of Th 2 Zn 17 -type is revealed as well. The annealing at 1273 K results in formation of Dy 3 (Fe, Si) 29 and also the compounds with the presumed composition of Dy 4 (Fe, Si) 41 and Ho 4 (Fe, Si) 41 . As this takes place the alloys contain a transition structure as well that represents a set of small-sized areas with various type short-range order in mutual displacement of Fe-Fe(Si) dumpbell chains. The process of phase formation at 1273 K is faced with difficulties. Even the annealing for 1000 h does not result in the state of equilibrium [ru

Enhanced laminated composite phase change material for energy storage

Energy Technology Data Exchange (ETDEWEB)

Darkwa, J.; Zhou, T. [Centre for Sustainable Energy Technologies (CSET), The University of Nottingham Ningbo, 199 Taikang East Road, Ningbo 315100 (China)

2011-02-15

This paper summarises studies undertaken towards the development of a laminated composite aluminium/hexadecane phase change material (PCM) drywall based on previous analytical work. The study also covered the selection and testing of various types of adhesive materials and identified Polyvinyl acetate (PVA) material as a suitable bonding material. For the purpose of comparison pure hexadecane and composite aluminium/hexadecane samples were developed and tested. The test results revealed faster thermal response by the aluminium/hexadecane sample regarding the rate of heat flux and also achieved about 10% and 15% heat transfer enhancements during the charging and discharging periods respectively. Its measured effective thermal conductivity also increased remarkably to 1.25 W/mK as compared with 0.15 W/mK for pure hexadecane. However there was about 5% less total cumulative thermal energy discharged at the end of the test which indicates that its effective thermal capacity was reduced by the presence of the aluminium particles. The study has shown that some of the scientific and technical barriers associated with the development of laminated composite PCM drywall systems can be overcome but further investigations of effects of adhesive materials are needed. (author)

Influence of the phase composition on the catalytic properties of ammonia synthesis catalysts

International Nuclear Information System (INIS)

Peev, T.M.; Bojinova, A.I.; Krylova, A.V.

1981-01-01

The phase composition of CA-1-type catalysts for ammonia synthesis was investigated by means of Moessbauer spectroscopy. A correlation was found between the catalytic activity of the samples and their wuestite content. (author)

Novel Magnetic-to-Thermal Conversion and Thermal Energy Management Composite Phase Change Material

Directory of Open Access Journals (Sweden)

Xiaoqiao Fan

2018-05-01

Full Text Available Superparamagnetic materials have elicited increasing interest due to their high-efficiency magnetothermal conversion. However, it is difficult to effectively manage the magnetothermal energy due to the continuous magnetothermal effect at present. In this study, we designed and synthesized a novel Fe3O4/PEG/SiO2 composite phase change material (PCM that can simultaneously realize magnetic-to-thermal conversion and thermal energy management because of outstanding thermal energy storage ability of PCM. The composite was fabricated by in situ doping of superparamagnetic Fe3O4 nanoclusters through a simple sol–gel method. The synthesized Fe3O4/PEG/SiO2 PCM exhibited good thermal stability, high phase change enthalpy, and excellent shape-stabilized property. This study provides an additional promising route for application of the magnetothermal effect.

Preparation and hygrothermal properties of composite phase change humidity control materials

International Nuclear Information System (INIS)

Chen, Zhi; Qin, Menghao

2016-01-01

Highlights: • A new kind of phase change humidity control material (PCHCM) was prepared. • The PCHCM can moderate both the indoor temperature and humidity. • The silicon dioxide shell can improve the thermal properties of the composite. • The PCM microcapsules can improve the moisture buffer ability of the composite. • The CPCM/vesuvianite composite has a better hygrothermal performance than pure hygroscopic material. - Abstract: A novel phase change humidity control material (PCHCM) was prepared by using PCM microcapsules and different hygroscopic porous materials. The PCHCM composite can regulate the indoor hygrothermal environment by absorbing or releasing both heat and moisture. The PCM microcapsules were synthesized with methyl triethoxysilane by the sol–gel method. The vesuvianite, sepiolite and zeolite were used as hygroscopic materials. The scanning electron microscopy (SEM) was used to measure the morphology profiles of the microcapsules and PCHCM. The differential scanning calorimetry (DSC) and the thermal gravimetric analysis (TGA) were used to determine the thermal properties and thermal stability. Both the moisture transfer coefficient and moisture buffer value (MBV) of different PCHCMs were measured by the improved cup method. The DSC results showed that the SiO 2 shell can reduce the super-cooling degree of PCM. The super-cooling degrees of microcapsules and PCHCM are lower than that of the pure PCM. The onset temperature of thermal degradation of the microcapsules and PCHCMs is higher than that of pure PCM. Both the moisture transfer coefficient and MBV of PCHCMs are higher than that of the pure hygroscopic materials. The results indicated the PCHCMs have better thermal properties and moisture buffer ability.

A Study of Phase Composition and Structure of Alloys of the Al - Mg - Si - Fe System

Science.gov (United States)

Mailybaeva, A. D.; Zolotorevskii, V. S.; Smagulov, D. U.; Islamkulov, K. M.

2017-03-01

The Thermo-Calc software is used to compute the phase transformations occurring during cooling of alloys. Polythermal and isothermal sections of the phase diagram of the Al - Mg - Si - Fe system are plotted. The phase composition and the structure of aluminum alloys in cast condition and after a heat treatment are studied experimentally.

Phase composition and microhardness of rapidly quenched Al-Fe alloys after high pressure torsion deformation

Energy Technology Data Exchange (ETDEWEB)

Tcherdyntsev, V.V.; Kaloshkin, S.D.; Gunderov, D.V.; Afonina, E.A.; Brodova, I.G.; Stolyarov, V.V.; Baldokhin, Yu.V.; Shelekhov, E.V.; Tomilin, I.A

2004-07-15

Aluminium-based Al-Fe alloys with Fe content of 2, 8, and 10 wt.% were prepared by rapid quenching (RQ) from the melt at a rate of 10{sup 6} K/s. Structure of the alloys was examined by X-ray diffraction (XRD) and Moessbauer spectroscopy. Phase transformations of RQ alloys by high pressure torsion (HPT) were studied. Dependences of phase composition on the intensity of HPT were investigated. Microhardness measurements of HPT alloys show a considerable structural heterogeneity of specimens, the dependence of microhardness on the radius of the pills was found out. Phase composition and microhardness during the heating were investigated. At the initial step of heating (120-150 deg. C), an increase in microhardness was observed, whereas further heating leads to a decrease in the microhardness.

On the crystallography and composition of topologically close-packed phases in ATI 718Plus®

International Nuclear Information System (INIS)

Krakow, Robert; Johnstone, Duncan N.; Eggeman, Alexander S.; Hünert, Daniela; Hardy, Mark C.; Rae, Catherine M.F.; Midgley, Paul A.

2017-01-01

ATI 718Plus ® is a nickel-based superalloy developed to replace Inconel 718 in aero engines for static and rotating applications. Here, the long-term stability of the alloy was studied and it was found that topologically close-packed (TCP) phases can form at the γ-η interface or, less frequently, at grain boundaries. Conventional and scanning transmission electron microscopy techniques were applied to elucidate the crystal structure and composition of these TCP precipitates. The precipitates were found to be tetragonal sigma phase and hexagonal C14 Laves phase, both being enriched in Cr, Co, Fe and Mo though sigma has a higher Cr and lower Nb content. The precipitates were observed to be heavily faulted along multiple planes. In addition, the disorientations between the TCP phases and neighbouring η/γ were determined using scanning precession electron diffraction and evaluated in axis-angle space. This work therefore provides a series of compositional and crystallographic insights that may be used to guide future alloy design.

Fatty acid esters-based composite phase change materials for thermal energy storage in buildings

International Nuclear Information System (INIS)

Sarı, Ahmet; Karaipekli, Ali

2012-01-01

In this study, fatty acid esters-based composite phase change materials (PCMs) for thermal energy storage were prepared by blending erythritol tetrapalmitate (ETP) and erythritol tetrastearate (ETS) with diatomite and expanded perlite (EP). The maximum incorporation percentage for ETP and ETS into diatomite and EP was found to be 57 wt% and 62 wt%, respectively without melted PCM seepage from the composites. The morphologies and compatibilities of the composite PCMs were structurally characterized using scanning electron microscope (SEM) and Fourier transformation infrared (FT–IR) analysis techniques. Thermal energy storage properties of the composite PCMs were determined by differential scanning calorimetry (DSC) analysis. The DSC analyses results indicated that the composite PCMs were good candidates for building applications in terms of their large latent heat values and suitable phase change temperatures. The thermal cycling test including 1000 melting and freezing cycling showed that composite PCMs had good thermal reliability and chemical stability. TG analysis revealed that the composite PCMs had good thermal durability above their working temperature ranges. Moreover, in order to improve the thermal conductivity of the composite PCMs, the expanded graphite (EG) was added to them at different mass fractions (2%, 5%, and 10%). The best results were obtained for the composite PCMs including 5wt% EG content in terms of the increase in thermal conductivity values and the decrease amount in latent heat capacity. The improvement in thermal conductivity values of ETP/Diatomite, ETS/Diatomite, ETP/EP and ETS/EP were found to be about 68%, 57%, 73% and 75%, respectively. Highlights: ► Fatty acid esters-based composite PCMs were prepared by blending ETP and ETS with diatomite and expanded perlite. ► The composite PCMs were characterized by using SEM, FT–IR, DSC and TG analysis methods. ► The DSC results indicated that the composites PCMs had good thermal

Electroactive Phase Induced Bi4Ti3O12-Poly(Vinylidene Difluoride) Composites with Improved Dielectric Properties

Science.gov (United States)

Bhardwaj, Sumit; Paul, Joginder; Chand, Subhash; Raina, K. K.; Kumar, Ravi

2015-10-01

Lead-free ceramic-polymer composite films containing Bi4Ti3O12 (BIT) nanocrystals as the active phase and poly(vinylidene difluoride) as the passive matrix were synthesized by spin coating. The films' structural, morphological, and dielectric properties were systemically investigated by varying the weight fraction of BIT. Formation of electroactive β and γ phases were strongly affected by the presence of BIT nanocrystals. Analysis was performed by Fourier-transform infrared and Raman spectroscopy. Morphological studies confirmed the homogeneous dispersion of BIT particles within the polymer matrix. The composite films had dielectric constants as high as 52.8 and low dielectric loss of 0.1 at 100 Hz when the BIT content was 10 wt.%. We suggest that the enhanced electroactive phase content of the polymer matrix and interfacial polarization may contribute to the improved dielectric performance of these composite films. Dielectric modulus analysis was performed to enable understanding of the dielectric relaxation process. Non-Debye-type relaxation behavior was observed for the composite films at high temperature.

Effect of reinforced fiber on morphology of Si phases in Al2O3/AI-Si alloy composite

Directory of Open Access Journals (Sweden)

Zheng LIU

2005-05-01

Full Text Available Alumina/aluminum-silicon alloy composite is manufactured by squeeze casting. The effect of the reinforcement on the morphology of the silicon phase in aluminum-silicon alloy is studied. The results indicate that an alumina fiber can serve as propitious sites for the heterogeneous nucleation of the silicon phase, and the primary silicon in the composite can nucleate on the surface of the fiber. The fiber in the composite can trigger twin during the coupled growth of the aluminum-silicon eutectic and lead to modification of the eutectic silicon near the fiber.

The Effects of a Macromolecular Charring Agent with Gas Phase and Condense Phase Synergistic Flame Retardant Capability on the Properties of PP/IFR Composites

Science.gov (United States)

Chen, Hongda; Wang, Jihui; Ding, Anxin; Han, Xia; Sun, Ziheng

2018-01-01

In order to improve the efficiency of intumescent flame retardants (IFRs), a novel macromolecular charring agent named poly(ethanediamine-1,3,5-triazine-p-4-amino-2,2,6,6-tetramethylpiperidine) (PETAT) with gas phase and condense phase synergistic flame-retardant capability was synthesized and subsequently dispersed into polypropylene (PP) in combination with ammonium polyphosphate (APP) via a melt blending method. The chemical structure of PETAT was investigated by Fourier transform infrared spectroscopy (FTIR), and 1H nuclear magnetic resonance (NMR) spectroscopy. Thermal properties of the PETAT and IFR systems were tested by thermogravimetric-derivative thermogravimetric analysis (TGA-DTG) and thermogravimetry–Fourier transform infrared spectroscopy (TG-FTIR). The mechanical properties, thermal stability, flame-retardant properties, water resistance, and structures of char residue in flame-retardant composites were characterized using tensile and flexural strength property tests, TGA, limiting oxygen index (LOI) values before and after soaking, underwritten laboratory-94 (UL-94) vertical burning test, cone calorimetric test (CCT), scanning electron microscopy with energy dispersive X-ray spectrometry (SEM-EDXS), and FTIR. The results indicated that PETAT was successfully synthesized, and when the ratio of APP to PETAT was 2:1 with 25 wt % loading, the novel IFR system could reduce the deterioration of tensile strength and enhance the flexural strength of composites. Meanwhile, the flame-retardant composite was able to pass the UL-94 V-0 rating with an LOI value of 30.3%, and the peak of heat release rate (PHRR), total heat release (THR), and material fire hazard values were considerably decreased compared with others. In addition, composites also exhibited excellent water resistance properties compared with traditional IFR composites. SEM-EDXS and FTIR analyses of the char residues, as well as TG-FTIR analyses of IFR were used to investigate the flame

The Effects of a Macromolecular Charring Agent with Gas Phase and Condense Phase Synergistic Flame Retardant Capability on the Properties of PP/IFR Composites

Directory of Open Access Journals (Sweden)

Hongda Chen

2018-01-01

Full Text Available In order to improve the efficiency of intumescent flame retardants (IFRs, a novel macromolecular charring agent named poly(ethanediamine-1,3,5-triazine-p-4-amino-2,2,6,6-tetramethylpiperidine (PETAT with gas phase and condense phase synergistic flame-retardant capability was synthesized and subsequently dispersed into polypropylene (PP in combination with ammonium polyphosphate (APP via a melt blending method. The chemical structure of PETAT was investigated by Fourier transform infrared spectroscopy (FTIR, and 1H nuclear magnetic resonance (NMR spectroscopy. Thermal properties of the PETAT and IFR systems were tested by thermogravimetric-derivative thermogravimetric analysis (TGA-DTG and thermogravimetry–Fourier transform infrared spectroscopy (TG-FTIR. The mechanical properties, thermal stability, flame-retardant properties, water resistance, and structures of char residue in flame-retardant composites were characterized using tensile and flexural strength property tests, TGA, limiting oxygen index (LOI values before and after soaking, underwritten laboratory-94 (UL-94 vertical burning test, cone calorimetric test (CCT, scanning electron microscopy with energy dispersive X-ray spectrometry (SEM-EDXS, and FTIR. The results indicated that PETAT was successfully synthesized, and when the ratio of APP to PETAT was 2:1 with 25 wt % loading, the novel IFR system could reduce the deterioration of tensile strength and enhance the flexural strength of composites. Meanwhile, the flame-retardant composite was able to pass the UL-94 V-0 rating with an LOI value of 30.3%, and the peak of heat release rate (PHRR, total heat release (THR, and material fire hazard values were considerably decreased compared with others. In addition, composites also exhibited excellent water resistance properties compared with traditional IFR composites. SEM-EDXS and FTIR analyses of the char residues, as well as TG-FTIR analyses of IFR were used to investigate the flame

The Effects of a Macromolecular Charring Agent with Gas Phase and Condense Phase Synergistic Flame Retardant Capability on the Properties of PP/IFR Composites.

Science.gov (United States)

Chen, Hongda; Wang, Jihui; Ni, Aiqing; Ding, Anxin; Han, Xia; Sun, Ziheng

2018-01-11

In order to improve the efficiency of intumescent flame retardants (IFRs), a novel macromolecular charring agent named poly(ethanediamine-1,3,5-triazine-p-4-amino-2,2,6,6-tetramethylpiperidine) (PETAT) with gas phase and condense phase synergistic flame-retardant capability was synthesized and subsequently dispersed into polypropylene (PP) in combination with ammonium polyphosphate (APP) via a melt blending method. The chemical structure of PETAT was investigated by Fourier transform infrared spectroscopy (FTIR), and ¹H nuclear magnetic resonance (NMR) spectroscopy. Thermal properties of the PETAT and IFR systems were tested by thermogravimetric-derivative thermogravimetric analysis (TGA-DTG) and thermogravimetry-Fourier transform infrared spectroscopy (TG-FTIR). The mechanical properties, thermal stability, flame-retardant properties, water resistance, and structures of char residue in flame-retardant composites were characterized using tensile and flexural strength property tests, TGA, limiting oxygen index (LOI) values before and after soaking, underwritten laboratory-94 (UL-94) vertical burning test, cone calorimetric test (CCT), scanning electron microscopy with energy dispersive X-ray spectrometry (SEM-EDXS), and FTIR. The results indicated that PETAT was successfully synthesized, and when the ratio of APP to PETAT was 2:1 with 25 wt % loading, the novel IFR system could reduce the deterioration of tensile strength and enhance the flexural strength of composites. Meanwhile, the flame-retardant composite was able to pass the UL-94 V-0 rating with an LOI value of 30.3%, and the peak of heat release rate (PHRR), total heat release (THR), and material fire hazard values were considerably decreased compared with others. In addition, composites also exhibited excellent water resistance properties compared with traditional IFR composites. SEM-EDXS and FTIR analyses of the char residues, as well as TG-FTIR analyses of IFR were used to investigate the flame

Mineral and Nutrient Leaf Composition of Two Cassava (Manihot esculenta Crantz Cultivars Defoliated at Varying Phenological Phases

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Oyeyemi Adigun DADA

2010-12-01

Full Text Available The effect of defoliation on mineral and food value of two cassava varieties defoliated at varying phenological phases was studied to ascertain the appropriate phenological phase when harvested leaves would contain the optimum mineral and proximate composition, gross energy and the least cyanide content. Two cassava cultivars were subjected to defoliation at varying phenological stages including logarithmic, vegetative and physiological maturity phases. The mineral content was highest at the logarithmic phase than any other phases. The proximate composition of the cassava leaves showed that crude protein was highest at physiological maturity, while the least HCN was observed in cassava defoliated at logarithmic phase. Analysis of mineral and proximate content showed that leaf of the �TMS30572� cultivar had the highest mineral content, fat, fibre, ash, dry matter and gross energy at the logarithm phase while �Oko-Iyawo� had the highest crude protein and HCN at physiological maturity. This study indicates the high potential of cassava leaf as an unconventional source of protein for both humans and animals when defoliated at logarithmic growth phase.

Non-linear temperature-dependent curvature of a phase change composite bimorph beam

Science.gov (United States)

Blonder, Greg

2017-06-01

Bimorph films curl in response to temperature. The degree of curvature typically varies in proportion to the difference in thermal expansion of the individual layers, and linearly with temperature. In many applications, such as controlling a thermostat, this gentle linear behavior is acceptable. In other cases, such as opening or closing a valve or latching a deployable column into place, an abrupt motion at a fixed temperature is preferred. To achieve this non-linear motion, we describe the fabrication and performance of a new bilayer structure we call a ‘phase change composite bimorph (PCBM)’. In a PCBM, one layer in the bimorph is a composite containing small inclusions of phase change materials. When the inclusions melt, their large (generally positive and  >1%) expansion coefficient induces a strong, reversible step function jump in bimorph curvature. The measured jump amplitude and thermal response is consistent with theory, and can be harnessed by a new class of actuators and sensors.

Effects of SiC amount on phase compositions and properties of Ti3SiC2-based composites

Institute of Scientific and Technical Information of China (English)

蔡艳芝; 殷小玮; 尹洪峰

2015-01-01

The phase compositions and properties of Ti3SiC2-based composites with SiC addition of 5%−30% in mass fraction fabricated by in-situ reaction and hot pressing sintering were studied. SiC addition effectively prevented TiC synthesis but facilitated SiC synthesis. The Ti3SiC2/TiC−SiC composite had better oxidation resistance when SiC added quantity reached 20% but poorer oxidation resistance with SiC addition under 15%than Ti3SiC2/TiC composite at higher temperatures. There were more than half of the original SiC and a few Ti3SiC2 remaining in Ti3SiC2/TiC−SiC with 20% SiC addition, but all constituents in Ti3Si2/TiC composite were oxidized after 12 h in air at 1500 °C. The oxidation scale thickness of TS30, 1505.78μm, was near a half of that of T, 2715μm, at 1500 °C for 20 h. Ti3SiC2/TiC composite had a flexural strength of 474 MPa, which was surpassed by Ti3SiC2/TiC−SiC composites when SiC added amount reached 15%. The strength reached the peak of 518 MPa at 20%SiC added amount.

The effect of the ceramic core initial phase composition on the Ag-sheathed Bi-2223 tapes critical properties

International Nuclear Information System (INIS)

Nikulin, A.D.; Shikov, A.K.; Khlebova, N.E.; Antipova, E.V.; Dontsova, E.V.; Kazakov, E.G.; Medvedev, M.I.; Kozlenkova, N.I.; Shishov, V.N.; Akimov, I.I.

1993-01-01

Ag - sheathed superconducting tapes were fabricated using ''powder-in-tube'' method with powders of Bi 1.6 Pb 0.4 Sr 2 Ca 2 Cu 3.2 O x chemical composition prepared by the ''freeze-drying'' tecnique and taken as a core materials. The effect of ceramic core initial phase composition: the mixture of oxide non-superconducting phases - OP (typeI) and 50% OP + 50% OP ''2212''- phase (type II) on the critical current density was investigated as well as the ''annealing - cold pressing'' parameters. Multifilamentary superconducting tapes and the pancake coils were fabricated. (orig.)

Preparation and characterization of form-stable paraffin/polycaprolactone composites as phase change materials for thermal energy storage

Directory of Open Access Journals (Sweden)

Aludin M.S.

2017-01-01

Full Text Available Paraffin is Phase Change Materials (PCM that possesses desirable properties such as high thermal energy storage and thermal stability to make it suitable for thermal energy storage applications. However, paraffin has been reported to leak out during the melting process. In this study, composites were prepared by dissolving paraffin and polycaprolactone (PCL at varied mass percent compositions in chloroform and then purified through precipitation techniques. The leakage test was conducted by placing the composite samples on a set of four-layer filter papers and left in a furnace at 90°C for 1 hour. By incorporating PCL into paraffin phase, the leakage mass percentage was drastically reduced. The PCL polymer matrix in the composites may have trapped the paraffin molecules during melting process thus prevent it from leaking.

Phase composition of EhK 990-ID steel

International Nuclear Information System (INIS)

Rabinovich, A.V.; Milova, I.M.; Zaslavskij, Yu.B.; Neklyudov, I.M.; Chernyj, B.P.; Vanzha, A.F.; Zejdlits, M.P.; Kurasov, A.N.; Shmelev, Yu.S.

1990-01-01

The microstructure and phase composition of EhK99 steel have been investigated. It is shown that the scandium absolute concentration in solid solution of hot-deformed metal is directly proportional to their total content. It was established that the ratio between the scandium concentration in solid solution and the total content [Sc] ss/[Sc] s is not the function of the latter and constitutes (24.5±5.5) rel.%. The limiting scandium solubility in the EhK99 steel at temperature 1270 deg C was determined. It constitutes 0.07±0.005 mass%. In this paper proposed is the mechanism of intermetallide-and-second phase nucleation and growth during crystallization and homogenizing annealing. The recommendation for regimes of homogenizing annealing (1270 deg C, 12 hours) are given. It is shown that the homogenizing vacuum annealing may have an appreciable influence on the technique plasticity and production of good tubes of EhK99 steel with scandium content no more than 0.07wt%. 2 refs., 10 figs., 2 tabs

Phase separation over an extended compositional range: Studies of the Ca1-xBixMnO3 (x≤0.25) phase diagram

International Nuclear Information System (INIS)

Santhosh, P. N.; Goldberger, J.; Woodward, P. M.; Vogt, T.; Lee, W. P.; Epstein, A. J.

2000-01-01

Phase transitions on the electron-doped side of the Ca 1-x Bi x MnO 3 system (x≤0.25) have been investigated using high-resolution synchrotron x-ray and neutron powder-diffraction techniques, electrical transport and magnetic susceptibility measurements. At room temperature all samples investigated were single phase, paramagnetic conductors (ρ 3 (space group Pnma). The Mn-O-Mn angles remain nearly constant from x=0 to x=0.25, while the Mn-O distances steadily increase with the Mn 3+ content. Three distinct phases are observed at 25 K. The first one, observed from 0.15≥x≥0.03, is characterized by the absence of charge and orbital ordering, a canted G-type antiferromagnetic spin structure, and delocalized electron transport. The second phase, observed from 0.25≥x≥0.12 (single phase at x=0.18), is characterized by pronounced orbital ordering, a C-type antiferromagnetic spin structure, and insulating behavior. The third low-temperature phase, observed for x≥0.20, is characterized by orbital and magnetic ordering similar to the Wigner crystal structure previously observed for Ca 0.67 La 0.33 MnO 3 , but with a 4axbx2c unit cell. The most striking feature of the phase diagram is the wide compositional range over which low-temperature phase separation is observed. Only those samples with x<0.12 and x=0.18 did not undergo phase separation upon cooling. We show that this behavior cannot be attributed to compositional variations, and therefore, propose that anisotropic strain interactions between crystallites may be partially responsible for this behavior

Applications of graphite-enabled phase change material composites to improve thermal performance of cementitious materials

Science.gov (United States)

Li, Mingli; Lin, Zhibin; Wu, Lili; Wang, Jinhui; Gong, Na

2017-11-01

Enhancing the thermal efficiency to decrease the energy consumption of structures has been the topic of much research. In this study, a graphite-enabled microencapsulated phase change material (GE-MEPCM) was used in the production of a novel thermal energy storage engineered cementitious composite feathering high heat storage capacity and enhanced thermal conductivity. The surface morphology and particle size of the microencapsulated phase change material (MEPCM) were investigated by scanning electron microscopy (SEM). Thermal properties of MEPCM was determined using differential scanning calorimetry (DSC). In addition, thermal and mechanical properties of the cementitious mortar with different admixtures were explored and compared with those of a cementitious composite. It was shown that the latent heat of MEPCM was 162 J/g, offering much better thermal energy storage capacity to the cementitious composite. However, MEPCM was found to decrease the thermal conductivity of the composite, which can be effectively solved by adding natural graphite (NG). Moreover, the incorporation of MEPCM has a certain decrease in the compressive strength, mainly due to the weak interfaces between MEPCM and cement matrix.

Heat transfer characteristics of thermal energy storage of a composite phase change materials: Numerical and experimental investigations

International Nuclear Information System (INIS)

Aadmi, Moussa; Karkri, Mustapha; El Hammouti, Mimoun

2014-01-01

In the present study, phase change materials based on epoxy resin paraffin wax with the melting point 27 °C were used as a new energy storage system. Thermophysical properties and the process of melting of a PCM (phase change material) composite were investigated numerically and experimentally. DSC (differential scanning calorimetry) has been used for measurement of melting enthalpy and determination of PCM heat capacity. The thermophysical properties of the prepared composite have been characterized by using a new transient hot plate apparatus. The results have shown that the most important thermal properties of these composites at the solid and liquid states are like the “apparent” thermal conductivity, the heat storage capacity and the latent heat of fusion. These experimental results have been simulated by using numerical Comsol ® Multiphysiques 4.3 based models with success. The results of the experimental investigation compare favorably with the numerical results and thus serve to validate the numerical approach. - Highlights: • Phase change materials based on paraffin spheres used as new energy storage system. • Thermophysical properties and the melting process of composites were investigated. • All experimental results have been simulated using Comsol ® Multiphysiques. • The ability to store and release the thermal energy were investigated. • A very thin molten PCM (phase change material) exists which is apparently visible in the spheres

High dielectric permittivity and improved mechanical and thermal properties of poly(vinylidene fluoride) composites with low carbon nanotube content: effect of composite processing on phase behavior and dielectric properties.

Science.gov (United States)

Kumar, G Sudheer; Vishnupriya, D; Chary, K Suresh; Patro, T Umasankar

2016-09-23

The composite processing technique and nanofiller concentration and its functionalization significantly alter the properties of polymer nanocomposites. To realize this, multi-walled carbon nanotubes (CNT) were dispersed in a poly(vinylidene fluoride) (PVDF) matrix at carefully selected CNT concentrations by two illustrious methods, such as solution-cast and melt-mixing. Notwithstanding the processing method, CNTs induced predominantly the γ-phase in PVDF, instead of the commonly obtained β-phase upon nanofiller incorporation, and imparted significant improvements in dielectric properties. Acid-treatment of CNT improved its dispersion and interfacial adhesion significantly with PVDF, and induced a higher γ-phase content and better dielectric properties in PVDF as compared to pristine CNT. Further, the γ-phase content was found to be higher in solution-cast composites than that in melt-mixed counterparts, most likely due to solvent-induced crystallization in a controlled environment and slow solvent evaporation in the former case. However, interestingly, the melt-mixed composites showed a significantly higher dielectric constant at the onset of the CNT networked-structure as compared to the solution-cast composites. This suggests the possible role of CNT breakage during melt-mixing, which might lead to higher space-charge polarization at the polymer-CNT interface, and in turn an increased number of pseudo-microcapacitors in these composites than the solution-cast counterparts. Notably, PVDF with 0.13 vol% (volume fraction, f c  = 0.0013) of acid-treated CNTs, prepared by melt-mixing, displayed the relative permittivity of ∼217 and capacitance of ∼5430 pF, loss tangent of ∼0.4 at 1 kHz and an unprecedented figure of merit of ∼10(5). We suggest a simple hypothesis for the γ-phase formation and evolution of the high dielectric constant in these composites. Further, the high-dielectric composite film showed marked improvements in mechanical and thermal

Using CCT Diagrams to Optimize the Composition of an As-Rolled Dual-Phase Steel

Science.gov (United States)

Coldren, A. Phillip; Eldis, George T.

1980-03-01

A continuous-cooling transformation (CCT) diagram study was conducted for the purpose of optimizing the composition of a Mn-Si-Cr-Mo as-rolled dual-phase (ARDP) steel. The individual effects of chromium, molybdenum, and silicon on the allowable cooling rates were determined. On the basis of the CCT diagram study and other available information, an optimum composition was selected. Data from recent mill trials at three steel companies, involving steels with compositions in or near the newly recommended range, are presented and compared with earlier mill trial data. The comparison shows that the optimized composition is highly effective in making the steel's properties more uniform and reproducible in the as-rolled condition.

Current injection phase thermography for low-velocity impact damage identification in composite laminates

International Nuclear Information System (INIS)

Grammatikos, S.A.; Kordatos, E.Z.; Matikas, T.E.; David, C.; Paipetis, A.S.

2014-01-01

Highlights: • A novel Current injection phase thermography NDE method has been developed. • Blind impact damage has been successfully detected in composite laminates. • Carbon nanotubes enhance detection by improving of through thickness conductivity. • Detection is feasible with considerably less energy than for IR excited thermography. - Abstract: An innovative non-destructive evaluation (NDE) technique is presented based on current stimulated thermography. Modulated electric current is injected to Carbon Fibre Reinforced Plastics (CFRP) laminates as an external source of thermal excitation. Pulsed Phase Thermography (PPT) is concurrently employed to identify low velocity impact induced (LVI) damage. The efficiency of the proposed method is demonstrated for both plain and with Carbon Nanotubes (CNTs) modified laminates, which are subjected to low-velocity impact damaged composite laminates at different energy levels. The presence of the nano reinforcing phase is important in achieving a uniform current flow along the laminate, as it improves the through thickness conductivity. The acquired thermographs are compared with optical PPT, C-scan images and Computer Tomography (CT) representations. The typical energy input for successful damage identification with current injection is three to four orders of magnitude less compared to the energy required for optical PPT

Effects of silicon carbide on the phase developments in mullite-carbon ceramic composite

Directory of Open Access Journals (Sweden)

Fatai Olufemi ARAMIDE

2017-12-01

Full Text Available The effects of the addition of silicon carbide and sintering temperatures on the phases developed, in sintered ceramic composite produced from kaolin and graphite was investigated. The kaolin and graphite of known mineralogical composition were thoroughly blended with 4 and 8 vol % silicon carbide. From the homogeneous mixture of kaolin, graphite and silicon carbide, standard samples were prepared via uniaxial compaction. The test samples produced were subjected to firing (sintering at 1300°C, 1400°C and 1500°C. The sintered samples were characterized for the developed phases using x‐ray diffractometry analysis, microstructural morphology using ultra‐high resolution field emission scanning electron microscope (UHRFEGSEM. It was observed that microstructural morphology of the samples revealed the evolution of mullite, cristobalite and microcline. The kaolinite content of the raw kaolin undergoes transformation into mullite and excess silica, the mullite and the silica phases contents increased with increased sintering temperature. It is also generally observed that the graphite content progressively reduced linearly with increased sintering temperature. It is concluded that silicon carbide acts as anti-oxidant for the graphite, this anti-oxidant effect was more effective at 4 vol % silicon carbide.

Phase composition of murataite ceramics for excess weapons plutonium immobilization

International Nuclear Information System (INIS)

Sobolev, I.A.; Stefanovsky, S.V.; Myasoedov, B.F.; Kullako, Y.M.; Yudintsev, S.V.

2000-01-01

Among the host phases for actinides immobilization, murataite (cubic, space group Fm3m) with the general formula A 4 B 2 C 7 O 22-x (A=Ca, Mn, Na, Ln, An; B=Mn, Ti, Zr, An IV ; C=Ti, Al, Fe; 0< x<1.5) is a promising matrix due to high isomorphic capacity and low leaching of actinides. One feature of murataite actinide zoning is an order-of-magnitude difference in concentration between the core and the rim. [1,2] Investigation of murataite ceramics in detail has shown occurrence of several murataite varieties with three-, five-, and eight-fold fluorite unit cells. [1-3] The goal of the present step of work is to study an effect of waste elements on phase composition of murataite ceramic and isomorphic capacity of waste elements

Design and Preparation of Carbon Based Composite Phase Change Material for Energy Piles.

Science.gov (United States)

Yang, Haibin; Memon, Shazim Ali; Bao, Xiaohua; Cui, Hongzhi; Li, Dongxu

2017-04-07

Energy piles-A fairly new renewable energy concept-Use a ground heat exchanger (GHE) in the foundation piles to supply heating and cooling loads to the supported building. Applying phase change materials (PCMs) to piles can help in maintaining a stable temperature within the piles and can then influence the axial load acting on the piles. In this study, two kinds of carbon-based composite PCMs (expanded graphite-based PCM and graphite nanoplatelet-based PCM) were prepared by vacuum impregnation for potential application in energy piles. Thereafter, a systematic study was performed and different characterization tests were carried out on two composite PCMs. The composite PCMs retained up to 93.1% of paraffin and were chemically compatible, thermally stable and reliable. The latent heat of the composite PCM was up to 152.8 J/g while the compressive strength of cement paste containing 10 wt % GNP-PCM was found to be 37 MPa. Hence, the developed composite PCM has potential for thermal energy storage applications.

Design and Preparation of Carbon Based Composite Phase Change Material for Energy Piles

Science.gov (United States)

Yang, Haibin; Memon, Shazim Ali; Bao, Xiaohua; Cui, Hongzhi; Li, Dongxu

2017-01-01

Energy piles—A fairly new renewable energy concept—Use a ground heat exchanger (GHE) in the foundation piles to supply heating and cooling loads to the supported building. Applying phase change materials (PCMs) to piles can help in maintaining a stable temperature within the piles and can then influence the axial load acting on the piles. In this study, two kinds of carbon-based composite PCMs (expanded graphite-based PCM and graphite nanoplatelet-based PCM) were prepared by vacuum impregnation for potential application in energy piles. Thereafter, a systematic study was performed and different characterization tests were carried out on two composite PCMs. The composite PCMs retained up to 93.1% of paraffin and were chemically compatible, thermally stable and reliable. The latent heat of the composite PCM was up to 152.8 J/g while the compressive strength of cement paste containing 10 wt % GNP-PCM was found to be 37 MPa. Hence, the developed composite PCM has potential for thermal energy storage applications. PMID:28772752

SiC/SiC composites through transient eutectic-phase route for fusion applications

International Nuclear Information System (INIS)

Katoh, Y.; Kohyama, A.; Nozawa, T.; Sato, M.

2004-01-01

Factors that may limit attractiveness of silicon-carbide-based ceramic composites to fusion applications include thermal conductivity, applicable design stress, chemical compatibility, hermeticity, radiation stability and fabrication cost. A novel SiC/SiC composite, which has recently been developed through nano-infiltration and transient eutectic-phase (NITE) processing route, surpasses conventional materials in many of these properties. In this paper, the latest development, property evaluation and prospect of the NITE SiC/SiC composites are briefly reviewed. The topics range from fundamental aspects of process development to industrial process development. Elevated temperature strength, fracture behavior, and thermo-physical properties in various environments are summarized. Future directions of materials and application technology development are also discussed

Preparation and performance of novel polyvinylpyrrolidone/polyethylene glycol phase change materials composite fibers by centrifugal spinning

Science.gov (United States)

Zhang, Xiaoguang; Qiao, Jiaxin; Zhao, Hang; Huang, Zhaohui; Liu, Yangai; Fang, Minghao; Wu, Xiaowen; Min, Xin

2018-01-01

Currently, phase change materials (PCMs) composite fibers are typically prepared by electrospinning. However, electrospinning exhibits safety concerns and a low production rate, which limit its practical applications as a cost-effective fiber fabrication approach. Therefore, a novel, and simple centrifugal spinning technology is employed to extrude fibers from composite solutions using a high-speed rotary and perforated spinneret. The composite fibers based on polyvinylpyrrolidone (PVP) and polyethylene glycol (PEG) were prepared by centrifugal spinning. The SEM of PVP/PEG composite fibers indicated that the fibrous morphology is well preserved. The DSC and TGA indicated that PVP/PEG composite fibers exhibit good thermal properties.

Research & Development of Materials/Processing Methods for Continuous Fiber Ceramic Composites (CFCC) Phase 2 Final Report.

Energy Technology Data Exchange (ETDEWEB)

Szweda, A.

2001-01-01

The Department of Energy's Continuous Fiber Ceramic Composites (CFCC) Initiative that begun in 1992 has led the way for Industry, Academia, and Government to carry out a 10 year R&D plan to develop CFCCs for these industrial applications. In Phase II of this program, Dow Corning has led a team of OEM's, composite fabricators, and Government Laboratories to develop polymer derived CFCC materials and processes for selected industrial applications. During this phase, Dow Corning carried extensive process development and representative component demonstration activities on gas turbine components, chemical pump components and heat treatment furnace components.

Composition/Property Relationships for the Phase 2 Am-Cm Glass Variability Study

Energy Technology Data Exchange (ETDEWEB)

Peeler, D.

2000-06-09

The objective of this research was to evaluate the effect of compositional uncertainties on the primary processing and product performance criteria for potential glasses to stabilize the Tank 17.1 Am-Cm solution and to identify the AGCR in which glasses simultaneously meet both process and product performance criteria as defined for Phase 2.

Melting of corrosion-resistant steel of martensite class with given phase composition

International Nuclear Information System (INIS)

Grashchenkov, P.M.; Kachanov, E.B.; Stetsenko, N.V.; Moshkevich, E.I.; Bunina, T.I.

1979-01-01

Introduced is a melting procedure for the EhP410U (vacuum arc remelted) and VNC-2M (electroslag remelted) stainless steels with carbon (carbon ferrochrome) and nickel additions to ensure a present phase composition. Magnetizability of cold specimens of the EhP410U steel should be within the limits 17.0-19.5 mV by a special device. During melting of the second steel controlled are not only cold specimens magnetizability of which should be not less than 16 mV, but hot as well (at 25O-400 deg C) by the level of magnetizability not higher than 0.5 mV. During vacuum arc remelting nitrogen content reduces in general by 0.014% and manganese content - by 0.23%; correspondingly the magnetizability of specimens insceases approximately by 1 mV. During electroslag remelting chemical and phase composition practically are not changed. Total and diffusible hydrogen contents in the vacuum remelted steel is rather low (1-5 and 0.03-0.35 cm 3 /100 gs), which provides increased reliability of the articles

Micromechanics of transformation fields in ageing linear viscoelastic composites: effects of phase dissolution or precipitation

Science.gov (United States)

Honorio, Tulio

2017-11-01

Transformation fields, in an affine formulation characterizing mechanical behavior, describe a variety of physical phenomena regardless their origin. Different composites, notably geomaterials, present a viscoelastic behavior, which is, in some cases of industrial interest, ageing, i.e. it evolves independently with respect to time and loading time. Here, a general formulation of the micromechanics of prestressed or prestrained composites in Ageing Linear Viscoelasticity (ALV) is presented. Emphasis is put on the estimation of effective transformation fields in ALV. The result generalizes Ageing Linear Thermo- and Poro-Viscoelasticity and it can be used in approaches coping with a phase transformation. Additionally, the results are extended to the case of locally transforming materials due to non-coupled dissolution and/or precipitation of a given (elastic or viscoelastic) phase. The estimations of locally transforming composites can be made with respect to different morphologies. As an application, estimations of the coefficient of thermal expansion of a hydrating alite paste are presented.

Structure, phases, and mechanical response of Ti-alloy bioactive glass composite coatings

Energy Technology Data Exchange (ETDEWEB)

Nelson, G.M.; Nychka, J.A. [Department of Chemical and Materials Engineering, University of Alberta, 7th Floor, Electrical and Computer Engineering Research Facility, Edmonton, Alberta T6G 2V4 (Canada); McDonald, A.G., E-mail: andre2@ualberta.ca [Department of Mechanical Engineering, University of Alberta, 4-9 Mechanical Engineering Building, Edmonton, Alberta T6G 2G8 (Canada)

2014-03-01

Porous titanium alloy-bioactive glass composite coatings were manufactured via the flame spray deposition process. The porous coatings, targeted for orthodontic and bone-fixation applications, were made from bioactive glass (45S5) powder blended with either commercially pure titanium (Cp-Ti) or Ti-6Al-4V alloy powder. Two sets of spray conditions, two metallic particle size distributions, and two glass particle size distributions were used for this study. Negative control coatings consisting of pure Ti-6Al-4V alloy or Cp-Ti were sprayed under both conditions. The as-sprayed coatings were characterized through quantitative optical cross-sectional metallography, X-ray diffraction (XRD), and ASTM Standard C633 tensile adhesion testing. Determination of the porosity and glassy phase distribution was achieved by using image analysis in accordance with ASTM Standard E2109. Theoretical thermodynamic and heat transfer modeling was conducted to explain experimental observations. Thermodynamic modeling was performed to estimate the flame temperature and chemical environment for each spray condition and a lumped capacitance heat transfer model was developed to estimate the temperatures attained by each particle. These models were used to establish trends among the choice of alloy, spray condition, and particle size distribution. The deposition parameters, alloy composition, and alteration of the feedstock powder size distribution had a significant effect on the coating microstructure, porosity, phases present, mechanical response, and theoretical particle temperatures that were attained. The most promising coatings were the Ti-6Al-4V-based composite coatings, which had bond strength of 20 ± 2 MPa (n = 5) and received reinforcement and strengthening from the inclusion of a glassy phase. It was shown that the use of the Ti-6Al-4V-bioactive glass composite coatings may be a superior choice due to the possible osteoproductivity from the bioactive glass, the potential ability to

Effect of composition and heat treatment on carbide phases in Ni-Mo alloys

International Nuclear Information System (INIS)

Svistunova, T.V.; Tsvigunov, A.N.; Stegnukhina, L.V.; Sakuta, N.D.

1984-01-01

The investigation results of vanadium, iron, carbon and silicon effect and heat treatment regime on the type and composition of carbides in Ni-(26...31)%Mo alloys are presented. It is shown that type, composition and quantity of carbide phases forming in alloys are determined not only by molybdenum and carbon content, but presence of other elements (V, Fe), admixtures (C, Si) and reducers as well as by regime of thermal treatment. In the alloy, containing 26...31% Mo, 0.01...0.03% C ( 12 C type with a=1.083...1.089 nm lattice parameter, in which V and Ti, Fe and Si are presented besides Mo and Ni. In the temperature range of 600-800 deg C high dispersed carbides segregate on grain boundaries. Silicon initiates segregation of the carbide phases among them by grain boundaries at the temperatures of 800 deg C as well as regulates carbide of M 12 C type with a=1.094...1.098 nm lattice parameter

Properties of form-stable paraffin/silicon dioxide/expanded graphite phase change composites prepared by sol–gel method

International Nuclear Information System (INIS)

Li, Min; Wu, Zhishen; Tan, Jinmiao

2012-01-01

Highlights: ► Paraffin/SiO 2 /EG composite PCM was prepared with sol–gel method. ► The thermal conductivity of SiO 2 /paraffin/EG is 94.7% higher than paraffin. ► The latent heat of paraffin/SiO 2 /EG composite is 104.4 J/g. -- Abstract: A form-stable paraffin/silicon dioxide (SiO 2 )/expanded graphite (EG) composite phase change material (PCM) was prepared by sol–gel method. Silica gel acts as the supporting material and EG is used to increase the thermal conductivity. The mass fractions of silicon oxide and graphite are 20.8% and 7.2%, respectively. The composite PCM was characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Fourier transformation infrared spectroscopy (FTIR) method. Thermal properties and thermal stability of the composite PCM were studied using differential scanning calorimetry (DSC). The result shows that paraffin was well dispersed in the network of silica gel and there is no chemical reaction between them. The phase change temperature of the paraffin/SiO 2 composite and the paraffin/SiO 2 /EG composite are 27.53 °C and 27.72 °C, respectively. The latent heat of the paraffin/SiO 2 composite and the paraffin/SiO 2 /EG composite are 112.8 J/g and 104.4 J/g, respectively. The thermal conductivity of the SiO 2 /paraffin composite and the SiO 2 /paraffin/EG composite are 28.2% and 94.7% higher than that of paraffin.

Vibration measurement on composite material with embedded optical fiber based on phase-OTDR

Science.gov (United States)

Franciscangelis, C.; Margulis, W.; Floridia, C.; Rosolem, J. B.; Salgado, F. C.; Nyman, T.; Petersson, M.; Hallander, P.; Hällstrom, S.; Söderquist, I.; Fruett, F.

2017-04-01

Distributed sensors based on phase-optical time-domain reflectometry (phase-OTDR) are suitable for aircraft health monitoring due to electromagnetic interference immunity, small dimensions, low weight and flexibility. These features allow the fiber embedment into aircraft structures in a nearly non-intrusive way to measure vibrations along its length. The capability of measuring vibrations on avionics structures is of interest for what concerns the study of material fatigue or the occurrence of undesirable phenomena like flutter. In this work, we employed the phase-OTDR technique to measure vibrations ranging from some dozens of Hz to kHz in two layers of composite material board with embedded polyimide coating 0.24 numerical aperture single-mode optical fiber.

Changes in phase composition and stress state of surface layers of VK20 hard alloy after ion bombardment

International Nuclear Information System (INIS)

Platonov, G.L.; Leonov, E.Yu.; Anikin, V.N.; Anikeev, A.I.

1988-01-01

Titanium ion bombardment of the surface of the hard VK20 alloy is studied for its effect on variations in the phase and chemical composition of its surface layers. It is stated that ion treatment results in the appearance of the η-phase of Co 6 W 6 C composition in the surface layer of the VK20 alloy, in the increase of distortions and decrease of coherent scattering blocks of the hard alloy carbide phase. Such a bombardment is found to provoke a transition of the plane-stressed state of the hard alloy surface into the volume-stressed state. It is established that ion treatment does not cause an allotropic transition of the cobalt phase α-modification, formed during grinding of the hard alloy, into the β-modification

A study of the diffusional behavior of a two-phase metal matrix composite exposed to a high temperature environment

Science.gov (United States)

Tenney, D. R.

1974-01-01

The progress of diffusion-controlled filament-matrix interaction in a metal matrix composite where the filaments and matrix comprise a two-phase binary alloy system was studied by mathematically modeling compositional changes resulting from prolonged elevated temperature exposure. The analysis treats a finite, diffusion-controlled, two-phase moving-interface problem by means of a variable-grid finite-difference technique. The Ni-W system was selected as an example system. Modeling was carried out for the 1000 to 1200 C temperature range for unidirectional composites containing from 6 to 40 volume percent tungsten filaments in a Ni matrix. The results are displayed to show both the change in filament diameter and matrix composition as a function of exposure time. Compositional profiles produced between first and second nearest neighbor filaments were calculated by superposition of finite-difference solutions of the diffusion equations.

Thermal conductivity and latent heat thermal energy storage properties of LDPE/wax as a shape-stabilized composite phase change material

International Nuclear Information System (INIS)

Trigui, Abdelwaheb; Karkri, Mustapha; Krupa, Igor

2014-01-01

Highlights: • This study deals with the comparison of experimental results for different PCM composite to be used in passive solar walls. • This paper reports on the successful use of a specific experimental method in order to characterize the phase change effects. • The results have shown that most important thermal properties of these composites at the solid and liquid states. • Results indicate the thermal effectiveness of phase change material and significant amount of energy saving can be achieved. • Heat flux measurements are a very interesting experimental source of data which comes to complete the calorimetric device (DSC). - Abstract: Phase change material (PCM) composites based on low-density polyethylene (LDPE) with paraffin waxes were investigated in this study. The composites were prepared using a meltmixing method with a Brabender-Plastograph. The LDPE as the supporting matrix kept the molten waxes in compact shape during its phase transition from solid to liquid. Immiscibility of the PCMs (waxes) and the supporting matrix (LDPE) is a necessary property for effective energy storage. Therefore, this type paraffin can be used in a latent heat storage system without encapsulation. The objective of this research is to use PCM composite as integrated components in a passive solar wall. The proposed composite TROMBE wall allows daily storage of the solar energy in a building envelope and restitution in the evening, with a possible control of the air flux in a ventilated air layer. An experimental set-up was built to determine the thermal response of these composites to thermal solicitations. In addition, a DSC analysis was carried out. The results have shown that most important thermal properties of these composites at the solid and liquid states, like the “apparent” thermal conductivity, the heat storage capacity and the latent heat of fusion. Results indicate the performance of the proposed system is affected by the thermal effectiveness of

Design and Preparation of Carbon Based Composite Phase Change Material for Energy Piles

Directory of Open Access Journals (Sweden)

Haibin Yang

2017-04-01

Full Text Available Energy piles—A fairly new renewable energy concept—Use a ground heat exchanger (GHE in the foundation piles to supply heating and cooling loads to the supported building. Applying phase change materials (PCMs to piles can help in maintaining a stable temperature within the piles and can then influence the axial load acting on the piles. In this study, two kinds of carbon-based composite PCMs (expanded graphite-based PCM and graphite nanoplatelet-based PCM were prepared by vacuum impregnation for potential application in energy piles. Thereafter, a systematic study was performed and different characterization tests were carried out on two composite PCMs. The composite PCMs retained up to 93.1% of paraffin and were chemically compatible, thermally stable and reliable. The latent heat of the composite PCM was up to 152.8 J/g while the compressive strength of cement paste containing 10 wt % GNP-PCM was found to be 37 MPa. Hence, the developed composite PCM has potential for thermal energy storage applications.

Quantitative phase analysis of alumina/calcium-hexaluminate composites using neutron diffraction data and the Rietveld method

International Nuclear Information System (INIS)

Asmi, D.; Low, I.M.; O'Connor, B.H.; Kennedy, S.J.

2000-01-01

Full text: The Al 2 O 3 -CaO system is the basis of an important class of high-temperature refractories in the steel industry. It contains a number of stable intermediate compounds which include C 3 A, C 12 A 7 , CA, CA 2 , and CA 6 . These calcium aluminates are also important constituents of high alumina cement and have been used to produce high-strength and high-toughness ceramic-polymer composite materials. More recently, alumina composites containing 30 wt% CA 6 platelets have been developed by An et al which show characteristics of self-reinforcement and enhanced toughening through crack-bridging. In this paper, we describe the use of high-temperature neutron diffraction to monitor the in-situ phase formation and abundances of calcium aluminates (CA, CA 2 , and CA 6 ) in alumina composites containing 5-50 wt % CA 6 .at temperatures in the range 1000 - 1600 deg C. These composites were produced using reaction sintering of alumina and calcium oxide. For comparison purposes, control samples of pure α-alumina and CA 6 were also produced. Determination of relative phase abundances in these materials has been performed using the standardless Rietveld refinement method. Results show that the relative phase abundance of calcium aluminates in the composites increased with temperature and in proportion with the amount of calcium oxide present. The formation temperatures of CA, CA 2 , and CA 6 have been observed to occur at 1000 deg , 1200 deg, and ∼1350 deg C respectively, which agree well with results obtained from x-ray diffraction, synchrotron radiation diffraction and differential thermal analysis

Influence of load type on power factor and harmonic composition of three-phase rectifier current

Science.gov (United States)

Nikolayzin, N. V.; Vstavskaya, E. V.; Konstantinov, V. I.; Konstantinova, O. V.

2018-05-01

This article is devoted to research of the harmonic composition of the three-phase rectifier current consumed when it operates with different types of load. The results are compared with Standard requirements.

Versatile Boron Carbide-Based Visual Obscurant Compositions for Smoke Munitions

Science.gov (United States)

2015-04-17

volatilize and disperse reaction products and inert diluents. Unlike the refractory oxides of common pyrotechnic fuels such as magnesium and aluminum, boron...peaks marked. [1] Akagi, R.; Ohtori, N.; Umesaki, N. Raman spectra of K2O–B2O3 glasses and melts. Journal of Non-Crystalline Solids. 2001

Effect of elemental composition of ion beam on the phase formation and surface strengthening of structural materials

International Nuclear Information System (INIS)

Avdienko, K.I.; Avdienko, A.A.; Kovalenko, I.A.

2001-01-01

The investigation results are reported on the influence of ion beam element composition on phase formation, wear resistance and microhardness of surface layers of titanium alloys VT-4 and VT-16 as well as stainless steel 12Kh18N10T implanted with nitrogen, oxygen and boron. It is stated that ion implantation into structural materials results in surface hardening and is directly dependent on element composition of implanted ion beam. The presence of oxygen in boron or nitrogen ion beams prevents the formation of boride and nitride phases thus decreasing a hardening effect [ru

Continuous fiber ceramic composite. Phase I final report, April 1992--April 1993

Energy Technology Data Exchange (ETDEWEB)

Goettler, R.W.

1995-04-01

Babcock and Wilcox assembled a team to develop the Continuous Fiber Ceramic Composite (CFCC) processing technology, identify the industrial applications, generate design and life prediction software, and to begin the necessary steps leading to full commercialization of CFCC components. Following is a summary of Phase I activities on this program. B&W has selected an oxide-oxide composite system for development and optimization in this program. This selection was based on the results of exposure tests in combustion environments typical of the boiler and heat exchanger applications. Aluminum oxide fiber is the selected reinforcement, and both aluminum oxide and zirconium oxide matrices were selected, based on their superior resistance to chemical attack in hostile industrial service.

Green colorants based on energetic azole borates.

Science.gov (United States)

Glück, Johann; Klapötke, Thomas M; Rusan, Magdalena; Stierstorfer, Jörg

2014-11-24

The investigation of green-burning boron-based compounds as colorants in pyrotechnic formulations as alternative for barium nitrate, which is a hazard to health and to the environment, is reported. Metal-free and nitrogen-rich dihydrobis(5-aminotetrazolyl)borate salts and dihydrobis(1,3,4-triazolyl)borate salts have been synthesized and characterized by NMR spectroscopy, elemental analysis, mass spectrometry, and vibrational spectroscopy. Their thermal and energetic properties have been determined as well. Several pyrotechnic compositions using selected azolyl borate salts as green colorants were investigated. Formulations with ammonium dinitramide and ammonium nitrate as oxidizers and boron and magnesium as fuels were tested. The burn time, dominant wavelength, spectral purity, luminous intensity, and luminous efficiency as well as the thermal and energetic properties of these compositions were measured. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Liquid Phase Plasma Synthesis of Iron Oxide/Carbon Composite as Dielectric Material for Capacitor

Directory of Open Access Journals (Sweden)

Heon Lee

2014-01-01

Full Text Available Iron oxide/carbon composite was synthesized using a liquid phase plasma process to be used as the electrode of supercapacitor. Spherical iron oxide nanoparticles with the size of 5~10 nm were dispersed uniformly on carbon powder surface. The specific capacitance of the composite increased with increasing quantity of iron oxide precipitate on the carbon powder up to a certain quantity. When the quantity of the iron oxide precipitate exceeds the threshold, however, the specific capacitance was rather reduced by the addition of precipitate. The iron oxide/carbon composite containing an optimum quantity (0.33 atomic % of iron oxide precipitate exhibited the smallest resistance and the largest initial resistance slope.

Fracture and fatigue considerations in the development of ductile-phase reinforced intermetallic-matrix composites

International Nuclear Information System (INIS)

Venkateswara Rao, K.T.; Ritchie, R.O.

1994-01-01

The salient microstructural factors influencing fracture and fatigue-crack growth resistance of ductile-particle reinforced intermetallic-matrix composites at ambient temperature are reviewed through examples from the Nb/MoSi 2 , TiNb/TiAl, Nb/TiAl and Nb/Nb 3 Al systems; specific emphasis is placed on properties and morphology of the reinforcement and its interfacial properties with the matrix. It is shown that composites must be fabricated with a high aspect ratio ductile-reinforcement morphology in order to promote crack-particle interception and resultant crack bridging for improved fracture and fatigue properties. Concurrently, however, the ductile phases have contrasting effects on crack growth under monotonic vs. cyclic loading suggesting that composite microstructures tailored for optimal toughness may not necessarily yield optimal fatigue resistance. Perspectives for the future development of damage-tolerant intermetallic-composite microstructures are discussed

Composite of wood-plastic and micro-encapsulated phase change material (MEPCM) used for thermal energy storage

International Nuclear Information System (INIS)

Jamekhorshid, A.; Sadrameli, S.M.; Barzin, R.; Farid, M.M.

2017-01-01

Highlights: • A composite of wood–plastic-MEPCM has been produced. • Compression molding has been used for the composite preparation. • Thermal and properties were investigated using DSC analysis and cycling test. • Leakage test has been performed for the encapsulated PCM. • The composites can be used as a building material for thermal energy management. - Abstract: Application of phase change materials (PCMs) in lightweight building is growing due to the high latent heat of fusion of PCMs and their ability to control temperature by absorbing and releasing heat efficiently. Wood-plastic composites (WPC) are materials used in the interior parts of buildings that have improved properties compared to conventional materials. However, these materials have low energy storage capacity, which can be improved by incorporating PCM in them. Leakage of PCM is a major obstacle to the industrial applications, which can be solved through the use of microencapsulated PCM (MEPCM). This paper presents the performance tests conducted for a composite of wood-plastic-MEPCM for using in buildings for thermal storage. The wood-plastic-MEPCM composites were produced in this project using compression molding and their thermal and mechanical properties were investigated using DSC analysis, cycling test, leakage test, and three point bending analysis. The results showed that there is no leakage of PCM during phase change. The results also indicated that the composite has reasonable thermal properties, but its mechanical properties need to be improved by increasing the pressure during the molding process or by using extrusion method. The produced composites can be used as a building material for thermal energy management of building.

One-step triple-phase interfacial synthesis of polyaniline-coated polypyrrole composite and its application as electrode materials for supercapacitors

Science.gov (United States)

Lei, Wen; He, Ping; Zhang, Susu; Dong, Faqin; Ma, Yongjun

2014-11-01

We first present an alternative one-step route for constructing a novel polyaniline (PANI)-coated polypyrrole (PPy) composite in an ingenious triple-phase interface system, where PPy and PANI are prepared in individual non-interference interfaces and, in the middle aqueous phase, smaller PANI particles are uniformly coated on the surface of PPy particles, forming a core-shell structure. The prepared PPy/PANI composite electrode shows a superior capacitance behavior that is more suitable for supercapacitor application.

The mechanism of hard metal TiC-TiNi composite liquid-phase sintering

International Nuclear Information System (INIS)

Akimov, V.V.

2006-01-01

The sintering conditions are investigated for hard alloys on their production from powders of titanium nickelide with particle size of 10-25 μ and titanium carbide with particles of 5-10 μ at temperatures of 1280-1350 deg C under pressure of 0.1 MPa with holding at heat for 180-900 s. The analysis of experimental data shows that optimum sintering conditions are determined by the quantity of a binding phase TiNi. In the systems with a binding phase content no more than 40 % a heterogeneous structure with nonuniform aggregates of TiC and TiNi phases is observed. With increasing a binding phase amount up to 50-70 % and a temperature up to 1350 deg C, titanium nickelide melts and spreads uniformly among carbide grains. This results in a low porosity of the composite material and in an increase of thermodynamic stability of the system [ru

Preparation and Performance Analysis of Na2SO4·10H2O/EG Composite Phase-change Materials

Directory of Open Access Journals (Sweden)

LENG Cong-bin

2017-01-01

Full Text Available Sodium sulfate decahydrate/expanded graphite composite phase-change material (Na2SO4·10H2O/EG was prepared by vacuum adsorption method.The thermal properties of Na2SO4·10H2O/EG,such as melting-solidification,phase separation,supercooling and latent heat were tested and analyzed.The results show that with the addition of 2%(mass fraction borax and 8% EG,the composite phase-change materials Na2SO4·10H2O/EG obtain ideal properties.The phase separation is eliminated,the supercooling degree of Na2SO4·10H2O is reduced from 13.6℃ to below 0.6℃,the latent heat and the energy storage density of the phase-change materials reach 225.77kJ·kg-1 and 218.09MJ·m-3 respectively.The thermal conductivity is also greatly improved.Compared with Na2SO4·10H2O with the addition of the nucleating agent borax only,the time for heat storage is shortened by 52.6%,and the time for heat release is shortened by 55.1%.Even after 500 times of rapid heating and cooling cycles,the performance of Na2SO4·10H2O/EG does not deteriorate.The novel composite phase-change material has better storage/exothermic properties.

Determination of enthalpy–temperature–composition relations in incongruent-melting phase change materials

International Nuclear Information System (INIS)

Desgrosseilliers, Louis; Allred, Paul; Groulx, Dominic; White, Mary Anne

2013-01-01

This paper demonstrates that liquidus line (T-x) data can be obtained from calorimetric determinations of phase transition enthalpy profiles (H-T) for incongruent-melting phase change materials (PCMs) more efficiently than using traditional cooling curves. An accurate and reliable equilibrium mixture enthalpy model bridges the H-T and T-x gap to provide a full suite of high density H-T-x data to assist latent heat energy storage researchers to evaluate composition-dependent two-phase equilibrium processes. The proposed method is validated for T-history method H-T determinations of 1:1 diluted sodium acetate trihydrate in water, and can also be used with other laboratory calorimetric techniques used to determine the phase transition enthalpy profiles of incongruent-melting compounds. -- Highlights: • H-T data can also be used to obtain valuable liquidus region T-x data. • Applies to all incongruent-melting compounds with known thermodynamic properties. • Reduces the effort and cost of assessing full suite H-T-x data for PCMs. • Uses existing T-x or H-T data of incongruent-melting PCMs to determine the other

Iron and silicon effect on the phase composition of nickel-beryllium bronzes

International Nuclear Information System (INIS)

Zakharov, A.M.; Zakharov, M.V.; Ajvaz'yan, N.G.

1977-01-01

In order to specify phase composition and strengthening heat treatment conditions for nickel beryllium bronzes that are promising electrode materials for welding of high strength steels and nickel-base superalloys, the primary section of the quinternary Cu-Ni-Be-Fe-S system was studied at constant nickel and beryllium concentration and varying silicon and iron concentration (max. 4% of every element). The study was made using the metallographic and x-ray phase techniques, determination of alloy solidus temperature, and exessphase microhardness testing. Silicon additions are shown to decrease abruptly and those of iron, in contrast, somewhat to raise the solidus temperature of ternary Cu + 2% Ni + 0.3% Be alloy. When added concurrently, iron compensates for the damaging silicon effect on the solidus temperature of Cu-Ni-Be alloys. The excess phases formed can be used as strengthening agents of Cu-Ni-Be-Si-Fe alloys during quenching and subsequent aging

Insight into the Effects of Reinforcement Shape on Achieving Continuous Martensite Transformation in Phase Transforming Matrix Composites

Science.gov (United States)

Zhang, Xudong; Ren, Junqiang; Wang, Xiaofei; Zong, Hongxiang; Cui, Lishan; Ding, Xiangdong

2017-12-01

A continuous martensite transformation is indispensable for achieving large linear superelasticity and low modulus in phase transforming metal-based composites. However, determining how to accurately condition the residual martensite in a shape memory alloy matrix though the reinforcement shape to achieve continuous martensite transformation has been a challenge. Here, we take the finite element method to perform a comparative study of the effects of nanoinclusion shape on the interaction and martensite phase transformation in this new composite. Two typical samples are compared: one reinforced by metallic nanowires and the other by nanoparticles. We find that the residual martensite within the shape memory alloy matrix after a pretreatment can be tailored by the reinforcement shape. In particular, our results show that the shape memory alloy matrix can retain enough residual martensite phases to achieve continuous martensite transformation in the subsequent loading when the aspect ratio of nanoreinforcement is larger than 20. In contrast, the composites reinforced with spherical or low aspect ratio reinforcement show a typical nonlinear superelasticity as a result of a low stress transfer-induced discontinuous martensite transformation within the shape memory alloy matrix.

The composition and character of oxycarbide phase in uranium metal

International Nuclear Information System (INIS)

Liu Kezhao; Lai Xinchun; Yu Yong; Ni Ranfu

1999-08-01

The oxide layer of uranium metal formed by vacuum heating were examined with X-ray photoelectron spectroscopy (XPS) and Auger Electron Spectroscopy (AES). XPS results indicated that the air-exposed surface of the oxide layer were mainly consisted of UO 2 and free carbon. After the air-exposed surface were removed by low energy argon ion sputtering, C1s spectra shifted from 284.8 eV to 281.8 eV, indicating the existence of carbide phase. AES results of C(KVV) Auger transitions confirmed this result. Resolved and fitted using a combination of Gaussian and Lorentzian peak shape, U4f 7/2 spectra showed that three uranium chemical states existed in the layer, there were uranium dioxide, uranium carbide (or oxycarbide, UC x O 1-x ) and uranium metal phase. Calculated the AES data by relatively sensitive factor, the composition of oxycarbide was given as UC 0.41+-0.04 O 0.62+-0.01

Controlling the length scale and distribution of the ductile phase in metallic glass composites through friction stir processing.

Science.gov (United States)

Arora, Harpreet Singh; Mridha, Sanghita; Grewal, Harpreet Singh; Singh, Harpreet; Hofmann, Douglas C; Mukherjee, Sundeep

2014-06-01

We demonstrate the refinement and uniform distribution of the crystalline dendritic phase by friction stir processing (FSP) of titanium based in situ ductile-phase reinforced metallic glass composite. The average size of the dendrites was reduced by almost a factor of five (from 24 μ m to 5 μ m) for the highest tool rotational speed of 900 rpm. The large inter-connected dendrites become more fragmented with increased circularity after processing. The changes in thermal characteristics were measured by differential scanning calorimetry. The reduction in crystallization enthalpy after processing suggests partial devitrification due to the high strain plastic deformation. FSP resulted in increased hardness and modulus for both the amorphous matrix and the crystalline phase. This is explained by interaction of shear bands in amorphous matrix with the strain-hardened dendritic phase. Our approach offers a new strategy for microstructural design in metallic glass composites.

Study on preparation and thermal property of binary fatty acid and the binary fatty acids/diatomite composite phase change materials

International Nuclear Information System (INIS)

Li, Min; Kao, Hongtao; Wu, Zhishen; Tan, Jinmiao

2011-01-01

This study prepared a series of binary phase change materials by mixing decanoic acid, dodecanoic acid, hexadecanoic acid and octadecanoic acid each other. The phase-transition temperature of binary fatty acid and its corresponding mixing proportion are calculated with phase diagram thermodynamic method. The results are verified by the experimental result of the heat absorption curve and the Differential Scanning Calorimetry (DSC) analysis curve. The results show that the calculation method of phase diagram thermodynamic calculation can be taken as a basis for mixing proportion of binary fatty acid phase change materials. In addition, the decanoic-dodecanoic acid/diatomite composite phase change material (PCM) are prepared and its microstructure, thermal property and thermal reliability are characterized. The result shows that the decanoic-dodecanoic acid is uniformly adsorbed into diatomite and the form-stable PCM are formed. The phase-transition temperature and the latent heat of the decanoic-dodecanoic acid/diatomite composite PCMs is 16.74 o C and 66.8114 J/g, respectively.

Metallic composite materials

International Nuclear Information System (INIS)

Frommeyer, G.

1987-01-01

The structure and properties of metallic composite materials and composite materials with metallic matrix are considered. In agreement with the morphology of constituent phases the following types of composite materials are described: dispersion-strengthened composite materials; particle-reinforced composite materials; fibrous composite materials; laminar composite materials. Data on strength and electric properties of the above-mentioned materials, as well as effect of the amount, location and geometric shape of the second phase on them, are presented

Experimental research on the influence of system parameters on the composition shift for zeotropic mixture (isobutane/pentane) in a system occurring phase change

International Nuclear Information System (INIS)

Bao, Junjiang; Zhao, Li

2016-01-01

Highlights: • The influence of system parameters on the composition shift for zeotropic mixture is studied. • Zeotropic mixture isobutane/pentane is selected as the working fluids. • Circulating composition and charge have the inverse proportion relationship. • The relationship between circulating composition and charge composition is linear. - Abstract: Zeotropic mixture can improve the performance of the thermodynamic cycle ascribed to the better temperature match during the heat transfer process with the characteristics of temperature glide during evaporation and condensing processes. Another characteristic of zeotropic mixture is composition shift. Composition shift means that the circulating composition and charge composition is different and is mainly caused by the two-phase hold-up and different solubility in lubricating oil. The existence of composition shift will affect the design and operation of thermodynamic system. The previous study gave little information about the influence of system parameters on the composition shift in a system occurring phase change. This paper mainly discuss the influence of system parameters on the composition shift for zeotropic mixture in a system occurring phase change as well as the validation of the linear relationship between the circulating composition and the charge composition and the inverse proportion relationship between the circulating composition and the charge mass found based on our previous theory study (Zhao and Bao, 2014). With isobutane and pentane as the research object, the impact of the key system parameters (hot water temperature, mass flow rate of hot water, feed pump frequency, cold water temperature and evaporator length) on composition shift are experimentally carried out. The results show that when the hot water temperature, mass flow rate of hot water and evaporator length increase and cold water temperature decreases, circulating composition will increase. For feed pump frequency, when

Determination of phase compositions in ceramics from Gobi desert using complementary diffraction techniques

International Nuclear Information System (INIS)

Gilles, R.; Hoelzel, M.; Siouris, I.M.; Katsavounis, S.; Visser, D.; Brunelli, M.

2013-01-01

The city Khara Khoto is located in the Gobi desert in Inner Mongolia. This city was deserted in the late 14th century and rediscovered in the beginning of the 20th century. In the present study, ceramic sherds typical for the Khara Khoto area have been analysed using neutrons, laboratory X-ray diffraction, synchrotron radiation X-ray diffraction as well as optical microscopy as complementary probes in extracting information on the mineral phase compositions as well as on the firing conditions during the pottery production. The data evaluation was performed with the standard diffraction analysis package GSAS and the new developed program AmPhOrAe. The dominating phase is mullite (∼60 %) compared to a variable mixture of SiO 2 quartz and cristobalite phases (∼35 %) and feldspar as a minority phase. Refiring experiments on one of the sherds allow estimating the firing temperatures of the ceramics within the region of 1,150 and 1,250 deg C. (author)

Preparation and thermal energy storage properties of paraffin/expanded graphite composite phase change material

International Nuclear Information System (INIS)

Zhang, Zhengguo; Zhang, Ni; Peng, Jing; Fang, Xiaoming; Gao, Xuenong; Fang, Yutang

2012-01-01

Highlights: ► EG was obtained by microwave irradiation to prepare the paraffin/EG composite PCM. ► Composite PCM was characterized by XRD to investigate the chemical compatibility. ► Temperature profiles of the composite PCM were obtained during thermal energy storage. -- Abstract: The paraffin/expanded graphite (EG) composite phase change material (PCM) was prepared by absorbing liquid paraffin into EG, in which paraffin was chosen as the PCM. EG was produced by microwave irradiation performed at room temperature. It was found that the EG prepared at 800 W irradiation power for 10 s exhibited the maximum sorption capacity of 92 wt% for paraffin. Scanning electron microscopy images showed that paraffin was uniformly dispersed in the pores of EG. Differential scanning calorimeter analysis indicated that the melting temperature of the composite PCM was close to that of paraffin, and its latent heat was equivalent to the calculated value based on the mass fraction of paraffin in the composite. X-ray diffraction analysis showed that the composite PCM was just a combination of paraffin with EG, and no new substance was produced. Thermal energy storage performance of the composite PCM was tested in a latent thermal energy storage (LTES) system. Transients of axial and radial temperature profiles were obtained in the LTES for the composite PCM and paraffin. The thermal energy storage charging duration for the composite PCM was reduced obviously compared to paraffin.

Dielectric and piezoelectric properties of percolative three-phase piezoelectric polymer composites

Science.gov (United States)

Sundar, Udhay

Three-phase piezoelectric bulk composites were fabricated using a mix and cast method. The composites were comprised of lead zirconate titanate (PZT), aluminum (Al) and an epoxy matrix. The volume fraction of the PZT and Al were varied from 0.1 to 0.3 and 0.0 to 0.17, respectively. The influences of three entities on piezoelectric and dielectric properties: inclusion of an electrically conductive filler (Al), poling process (contact and Corona) and Al surface treatment, were observed. The piezoelectric strain coefficient, d33, effective dielectric constant, epsilon r, capacitance, C, and resistivity were measured and compared according to poling process, volume fraction of constituent phases and Al surface treatment. The maximum values of d33 were 3.475 and 1.0 pC/N for Corona and contact poled samples respectively, for samples with volume fractions of 0.40 and 0.13 of PZT and Al (surface treated) respectively. Also, the maximum dielectric constant for the surface treated Al samples was 411 for volume fractions of 0.40 and 0.13 for PZT and Al respectively. The percolation threshold was observed to occur at an Al volume fraction of 0.13. The composites achieved a percolated state for Al volume fractions >0.13 for both contact and corona poled samples. In addition, a comparative time study was conducted to examine the influence of surface treatment processing time of Al particles. The effectiveness of the surface treatment, sample morphology and composition was observed with the aid of SEM and EDS images. These images were correlated with piezoelectric and dielectric properties. PZT-epoxy-aluminum thick films (200 mum) were also fabricated using a two-step spin coat deposition and annealing method. The PZT volume fraction were varied from 0.2, 0.3 and 0.4, wherein the Aluminum volume fraction was varied from 0.1 to 0.17 for each PZT volume fraction, respectively. The two-step process included spin coating the first layer at 500 RPM for 30 seconds, and the second

Formation of soft magnetic high entropy amorphous alloys composites containing in situ solid solution phase

Science.gov (United States)

Wei, Ran; Sun, Huan; Chen, Chen; Tao, Juan; Li, Fushan

2018-03-01

Fe-Co-Ni-Si-B high entropy amorphous alloys composites (HEAACs), which containing high entropy solid solution phase in amorphous matrix, show good soft magnetic properties and bending ductility even in optimal annealed state, were successfully developed by melt spinning method. The crystallization phase of the HEAACs is solid solution phase with body centered cubic (BCC) structure instead of brittle intermetallic phase. In addition, the BCC phase can transformed into face centered cubic (FCC) phase with temperature rise. Accordingly, Fe-Co-Ni-Si-B high entropy alloys (HEAs) with FCC structure and a small amount of BCC phase was prepared by copper mold casting method. The HEAs exhibit high yield strength (about 1200 MPa) and good plastic strain (about 18%). Meanwhile, soft magnetic characteristics of the HEAs are largely reserved from HEAACs. This work provides a new strategy to overcome the annealing induced brittleness of amorphous alloys and design new advanced materials with excellent comprehensive properties.

Phase selection controlled by sodium ions in the synthesis of FAU/LTA composite zeolite

Directory of Open Access Journals (Sweden)

Linyan Hu, Sujuan Xie, Qingxia Wang, Shenglin Liu and Longya Xu

2009-01-01

Full Text Available Zeolite faujasite (FAU, Linde type A (LTA and FAU/LTA composite have been synthesized using tetramethylammonium cation (TMA + as template, by adjusting only the concentration of Na + ions in the initial solution (1.00 Al2 O3 4.36 SiO2 : 2.39 (TMA2 O : β Na2 O : 249.00H2 O. Na + ions alter the phase composition of the product more than TMA+ or OH− ions. When Na2 O concentration [Na2 O] increases from 0.024 to 0.168, the product gradually changes from pure FAU to pure LTA via the formation of FAU/LTA composite with increasing LTA fraction. Interestingly, the induction periods of FAU and LTA in the FAU/LTA composite zeolite ([Na2 O] is 0.072 are both 13 h, quite different from the induction periods of their individual pure phases—45 h for FAU and 4 h for LTA. During the crystallization, the LTA/(FAU + LTA fraction in the composite zeolite decreases in a nearly linear fashion. Scanning electron microscopy, thermogravimetry and differential thermal analysis indicate some difference between the properties of the FAU/LTA composite zeolite and of the mechanical mixture.

Swift heavy ion irradiation induced phase transformation in undoped and niobium doped titanium dioxide composite thin films

Energy Technology Data Exchange (ETDEWEB)

Gautam, Subodh K., E-mail: subodhkgtm@gmail.com [Inter University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 110 067 (India); Chettah, Abdelhak [LGMM Laboratory, Université 20 Août 1955-Skikda, BP 26, 21000 Skikda (Algeria); Singh, R.G. [Department of Physics, Bhagini Nivedita College, Delhi University, Delhi 110043 (India); Ojha, Sunil; Singh, Fouran [Inter University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 110 067 (India)

2016-07-15

Study reports the effect of swift heavy ion (SHI) irradiation induced phase transformation in undoped and Niobium doped anatase TiO{sub 2} composite thin films. Investigations were carried out at different densities of electronic excitations (EEs) using 120 MeV Ag and 130 MeV Ni ions irradiations. Films were initially annealed at 900 °C and results revealed that undoped films were highly stable in anatase phase, while the Nb doped films showed the composite nature with the weak presence of Niobium penta-oxide (Nb{sub 2}O{sub 5}) phase. The effect at low density of EEs in undoped film show partial anatase to rutile phase transformation; however doped film shows only further growth of Nb{sub 2}O{sub 5} phase beside the anatase to rutile phase transformation. At higher density of EEs induced by Ag ions, registered continuous ion track of ∼3 nm in lattice which leads to nano-crystallization followed by decomposition/amorphization of rutile TiO{sub 2} and Nb{sub 2}O{sub 5} phases in undoped and doped films, respectively. However, Ni ions are only induced discontinuous sequence of ion tracks with creation of damage and disorder and do not show amorphization in the lattice. The in-elastic thermal spike calculations were carried out for anatase TiO{sub 2} phase to understand the effect of EEs on anatase to rutile phase transformation followed by amorphization in NTO films in terms of continuous and discontinuous track formation by SHI irradiation.

Vapour-phase method in the synthesis of polymer-ibuprofen sodium-silica gel composites.

Science.gov (United States)

Kierys, Agnieszka; Krasucka, Patrycja; Grochowicz, Marta

2017-11-01

The study discusses the synthesis of polymer-silica composites comprising water soluble drug (ibuprofen sodium, IBS). The polymers selected for this study were poly(TRIM) and poly(HEMA- co -TRIM) produced in the form of permanently porous beads via the suspension-emulsion polymerization method. The acid and base set ternary composites were prepared by the saturation of the solid dispersions of drug (poly(TRIM)-IBS and/or poly(HEMA- co -TRIM)-IBS) with TEOS, and followed by their exposition to the vapour mixture of water and ammonia, or water and hydrochloric acid, at autogenous pressure. The conducted analyses reveal that the internal structure and total porosity of the resulting composites strongly depend on the catalyst which was used for silica precursor gelation. The parameters characterizing the porosity of both of the acid set composites are much lower than the parameters of the base set composites. Moreover, the basic catalyst supplied in the vapour phase does not affect the ibuprofen sodium molecules, whereas the acid one causes transformation of the ibuprofen sodium into the sodium chloride and a derivative of propanoic acid, which is poorly water soluble. The release profiles of ibuprofen sodium from composites demonstrate that there are differences in the rate and efficiency of drug desorption from them. They are mainly affected by the chemical character of the polymeric carrier but are also associated with the restricted swelling of the composites in the buffer solution after precipitation of silica gel.

Vapour-phase method in the synthesis of polymer-ibuprofen sodium-silica gel composites

Directory of Open Access Journals (Sweden)

Agnieszka Kierys

2017-11-01

Full Text Available The study discusses the synthesis of polymer-silica composites comprising water soluble drug (ibuprofen sodium, IBS. The polymers selected for this study were poly(TRIM and poly(HEMA-co-TRIM produced in the form of permanently porous beads via the suspension-emulsion polymerization method. The acid and base set ternary composites were prepared by the saturation of the solid dispersions of drug (poly(TRIM-IBS and/or poly(HEMA-co-TRIM-IBS with TEOS, and followed by their exposition to the vapour mixture of water and ammonia, or water and hydrochloric acid, at autogenous pressure. The conducted analyses reveal that the internal structure and total porosity of the resulting composites strongly depend on the catalyst which was used for silica precursor gelation. The parameters characterizing the porosity of both of the acid set composites are much lower than the parameters of the base set composites. Moreover, the basic catalyst supplied in the vapour phase does not affect the ibuprofen sodium molecules, whereas the acid one causes transformation of the ibuprofen sodium into the sodium chloride and a derivative of propanoic acid, which is poorly water soluble. The release profiles of ibuprofen sodium from composites demonstrate that there are differences in the rate and efficiency of drug desorption from them. They are mainly affected by the chemical character of the polymeric carrier but are also associated with the restricted swelling of the composites in the buffer solution after precipitation of silica gel.

Composition and property measurements for PHA Phase 4 glasses

International Nuclear Information System (INIS)

Edwards, T.B.

2000-01-01

The results presented in this report are for nine Precipitate Hydrolysis Aqueous (PHA) Phase 4 glasses. Three of the glasses contained HM sludge at 22, 26, and 30 wt% respectively, 10 wt% PHA and 1.25 wt% monosodium titanate (MST), all on an oxide basis. The remaining six glasses were selected from the Phase 1 and Phase 2 studies (Purex sludge) but with an increased amount of MST. The high-end target for MST of 2.5 wt% oxide was missed in Phases 1 and 2 due to ∼30 wt% water content of the MST. A goal of this Phase 4 study was to determine whether this increase in titanium concentration from the MST had any impact on glass quality or processibility. Two of the glasses, pha14c and pha15c, were rebatched and melted due to apparent batching errors with pha14 and pha15. The models currently in the Defense Waste Processing Facility's (DWPF) Product Composition Control System (PCCS) were used to predict durability, homogeneity, liquidus, and viscosity for these nine glasses. All of the HM glasses and half of the Purex glasses were predicted to be phase separated, and consequently prediction of glass durability is precluded with the cument models for those glasses that failed the homogeneity constraint. If one may ignore the homogeneity constraint, the measured durabilities were within the 95% prediction limits of the model. Further efforts will be required to resolve this issue on phase separation (inhomogeneity). The liquidus model predicted unacceptable liquidus temperatures for four of the nine glasses. The approximate, bounding liquidus temperatures measured for all had upper limits of 1,000 C or less. Given the fact that liquidus temperatures were only approximated, the 30 wt% loading of Purex may be near or at the edge of acceptability for liquidus. The measured viscosities were close to the predictions of the model. For the Purex glasses, pha12c and pha15c, the measured viscosities of 28 and 23 poise, respectively, indicate that DWPF processing may be compromised

Electroless Ni-P/Nano-SiO2 Composite Plating on Dual Phase Magnesium-Lithium Alloy

Science.gov (United States)

Zou, Y.; Zhang, Z. W.; Zhang, M. L.

The application of Mg-Li alloys is restricted in practice due to mainly poor corrosion resistance and wear resistance. Electroless nickel plating is one of the common and effective ways to protect alloys from corrosion. In this study, nano-SiO2 particles with Ni-P matrix have been successfully co-deposited onto dual phase Mg-8Li base alloy through electroless plating, generating homogeneously Ni-P/nano-SiO2 composite coating. The morphology, elemental composition and structures of coatings were investigated. Coating performances were evaluated using hardness tests and electrochemical analysis. The results indicate that the Ni-P/nano-SiO2 composite coating can significantly improve the wear and corrosion resistance.

Thermodynamic modelling of phase equilibrium in system Ti-B-Si-C, synthesis and phases composition of borides and carbides layers on titanic alloyVT-1 at electron beam treatment in vacuum

Science.gov (United States)

Smirnyagina, N. N.; Khaltanova, V. M.; Lapina, A. E.; Dasheev, D. E.

2017-01-01

Composite layers on the basis of carbides and borides the titan and silicon on titanic alloy VT-1 are generated at diffused saturation in vacuum. Formation in a composite of MAX phase Ti3SiC2 is shown. Thermodynamic research of phase equilibrium in systems Ti-Si-C and Ti-B-C in the conditions of high vacuum is executed. The thermodynamics, formation mechanisms of superfirm layers borides and carbides of the titan and silicon are investigated.

ZnO nanorod array polydimethylsiloxane composite solid phase micro-extraction fiber coating: fabrication and extraction capability.

Science.gov (United States)

Wang, Dan; Wang, Qingtang; Zhang, Zhuomin; Chen, Guonan

2012-01-21

ZnO nanorod array coating is a novel kind of solid-phase microextraction (SPME) fiber coating which shows good extraction capability due to the nanostructure. To prepare the composite coating is a good way to improve the extraction capability. In this paper, the ZnO nanorod array polydimethylsiloxane (PDMS) composite SPME fiber coating has been prepared and its extraction capability for volatile organic compounds (VOCs) has been studied by headspace sampling the typical volatile mixed standard solution of benzene, toluene, ethylbenzene and xylene (BTEX). Improved detection limit and good linear ranges have been achieved for this composite SPME fiber coating. Also, it is found that the composite SPME fiber coating shows good extraction selectivity to the VOCs with alkane radicals.

Body composition measurement using computed tomography: Does the phase of the scan matter?

Science.gov (United States)

Rollins, Katie E; Javanmard-Emamghissi, Hannah; Awwad, Amir; Macdonald, Ian A; Fearon, Kenneth C H; Lobo, Dileep N

2017-09-01

The aim of this study was to determine, from the methodologic standpoint, the effect of the presence or absence of intravenous contrast on body composition variables obtained by analysis of computed tomography (CT) images. Triphasic abdominal (noncontrast, arterial phase, and portovenous phase contrast) CT scans from 111 patients were analyzed by two independent assessors at the third lumbar vertebral level using SliceOmatic software (version 5.0, TomoVision, Montreal, Canada). Variables included skeletal muscle index (SMI), fat and fat-free mass (FM and FFM, respectively), and mean skeletal muscle Hounsfield units (SMHU). Mean SMHU was lowest in the noncontrast phase (29.4, standard deviation [SD] 8.9 HU), followed by arterial (32.4, SD 9.3 HU) then portovenous phases (34.9, SD 9.4 HU). The mean skeletal muscle attenuation was significantly different depending on the phase of the scan in which the images were obtained. Calculated FM was significantly lower in both arterial (28.6, SD 8.8 kg, P definition of myosteatosis should include a standardized phase of CT for analysis and this should be incorporated within its definition. However, as the magnitudes of the differences were relatively small, the effect of the phase of the scan on predicting outcome needs to be determined. Copyright © 2017 Elsevier Inc. All rights reserved.

Process optimization in Nd:YAG laser microdrilling of alumina–aluminium interpenetrating phase composite

Directory of Open Access Journals (Sweden)

Ranjib Biswas

2015-07-01

Full Text Available In laser beam micromachining process, the quality of the drilled hole is of great importance. The quality of the microdrilled hole mainly depends on appropriate selection of process parameters. Predefined diameter of hole with minimum taper is of today's demand. The composite used for microdrilling operation is alumina–aluminium (Al2O3–Al interpenetrating phase composite (IPC, which is widely used in aircraft and space stations. Until date, no experimental study has been done to obtain microdrilled hole of desired diameter. In the present paper three hole qualities such as hole diameter at entry, at exit and hole taper have been optimized individually as well as simultaneously using a central composite design (CCD based on response surface methodology (RSM during pulsed Nd:YAG laser microdrilling operation on alumina–aluminium IPC sheet of 1.14 mm thickness. The analysis of variance (ANOVA test has also been done to identify the process parameters that contributed the most to get desired hole quality.

Phase composition and saturated liquid properties in binary and ternary systems containing carbon dioxide, n-decane, and n-tetradecane

International Nuclear Information System (INIS)

Kariznovi, Mohammad; Nourozieh, Hossein; Abedi, Jalal

2013-01-01

Highlights: ► Binary and ternary systems of (carbon dioxide + n-decane + n-tetradecane) at 323.2 K. ► Isothermal phase properties measurements over wide range of pressure (1 to 6) MPa. ► Experimental measurements, density, viscosity, and composition, using a designed PVT apparatus. ► The experimental data were correlated using two equations of state. ► The interaction parameters and the volume shift values from the experimental data on the binary pairs. - Abstract: Experimental phase equilibrium data have been measured for the binary and ternary systems containing (carbon dioxide, n-decane, and n-tetradecane) at 323.2 K over the pressure range (1 to 6) MPa using a designed PVT apparatus. The measurements presented in this paper were undertaken to determine liquid phase composition and liquid saturated properties (density and viscosity) when a liquid hydrocarbon (n-decane, n-tetradecane, and their mixtures) was saturated with carbon dioxide. The generated data for compositions and densities were correlated with the Soave–Redlich–Kwong (SRK) and Peng–Robinson (PR) equations of state (EOS). The adjustment of binary interaction parameters and volume translation technique has been employed to correlate the experimental compositions and densities. The adjusted binary parameters from the data of binary pairs (carbon dioxide + n-decane) and (carbon dioxide + n-tetradecane) were used to correlate the generated ternary data. The calculated ternary compositions were found to be in good agreement with the experimental data using the binary parameters from the data of binary pairs for both EOSs. The results for the density of saturated liquid phase indicated that the volume translation should be applied to all components in the binary and ternary systems to describe accurately the saturated liquid densities for mixtures.

Preparation and characterization of hydrated salts/silica composite as shape-stabilized phase change material via sol–gel process

International Nuclear Information System (INIS)

Wu, Yuping; Wang, Tao

2014-01-01

Highlights: • A mixture of hydrated salts were adopted as phase change materials. • Phase segregation of the hydrated salts was inhibited. • Subcooling was slightly mitigated. • Thermal cycling performance was greatly improved after PVP coating. - Abstract: A novel shape-stabilized phase change material composite was prepared by impregnating the mixture of hydrated salts (Na 2 SO 4 ·10H 2 O–Na 2 HPO 4 ·12H 2 O) into porous silica matrix obtained by sol–gel process and further coated with polyvinylpyrrolidone (PVP) to improve the thermal cycling performance. The chemical compatibility, morphology and phase change properties were investigated by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM), hot-stage polarizing optical microscope (HS-POM) and differential scanning calorimetry (DSC). Confined in the silica matrix, phase segregation of the hydrated salts was inhibited and subcooling was slightly mitigated. No leakage was observed during the solid–liquid phase transition even when the mass ratio of hydrated salts to silica was as high as 70:30. Results showed that the melting enthalpy of the composite can reach 106.2 kJ/kg with the melting temperature at 30.13 °C and there was no significant enthalpy loss after 30 thermal cycles

Characterization of SiCf/SiC and CNT/SiC composite materials produced by liquid phase sintering

International Nuclear Information System (INIS)

Lee, J.K.; Lee, S.P.; Cho, K.S.; Byun, J.H.; Bae, D.S.

2011-01-01

This paper dealt with the microstructure and mechanical properties of SiC based composites reinforced with different reinforcing materials. The composites were fabricated using reinforcing materials of carbon nanotubes (CNT) and Tyranno Lox-M SiC chopped fibers. The volume fraction of carbon nanotubes was also varied in this composite system. An Al 2 O 3 -Y 2 O 3 powder mixture was used as a sintering additive in the consolidation of the SiC matrix. The characterization of the composites was investigated by means of SEM and three point bending tests. These composites showed a dense morphology of the matrix region, by the creation of a secondary phase. The composites reinforced with SiC chopped fibers possessed a flexural strength of about 400 MPa at room temperature. The flexural strength of the carbon nanotubes composites had a tendency to decrease with increased volume fraction of the reinforcing material.

Evaluation of the phase composition of (NH4)2SO4 + (NH4)H2PO4 mixtures by X-ray diffractometry

International Nuclear Information System (INIS)

Ortiz, Angel L.; Cumbrera, Francisco L.; Perez, Jose; Vas, Beatriz del; Perez, Eduardo

2009-01-01

The phase composition of standard (NH 4 ) 2 SO 4 + (NH 4 )H 2 PO 4 mixtures was investigated by X-ray diffractometry (XRD) using the internal-standard, reference-intensity-ratio, and Rietveld methods. It was found that the Rietveld method yields the most accurate phase-composition measurements, with an average error of ∼2 wt.%. It was also found that the internal-standard method is only effective in determining the phase composition if the calibration curve for (NH 4 )H 2 PO 4 is used, giving an average error of ∼6.5 wt.%. On the contrary, the internal-standard method with the calibration curve of the (NH 4 ) 2 SO 4 phase and the reference-intensity-ratio method are not valid. The inappropriateness of these two methods was attributed to graininess in the (NH 4 ) 2 SO 4 phase, with the attendant deviation of its diffracted intensities from the theoretical values. Direct scanning electron microscopy observations of the morphology of the powder particles in the mixtures showed clear evidence of the large agglomerates formed because the individual powder particles are partially sintered together during milling, thus corroborating the graininess determined by the XRD analyses. Finally, the implications of the present study for the quantitative phase-composition analysis of (NH 4 ) 2 SO 4 + (NH 4 )H 2 PO 4 mixtures, which are of great technological importance for the fire prevention industry, are discussed.

Preparation and thermal properties of form-stable palmitic acid/active aluminum oxide composites as phase change materials for latent heat storage

International Nuclear Information System (INIS)

Fang, Guiyin; Li, Hui; Cao, Lei; Shan, Feng

2012-01-01

Form-stable palmitic acid (PA)/active aluminum oxide composites as phase change materials were prepared by adsorbing liquid palmitic acid into active aluminum oxide. In the composites, the palmitic acid was used as latent heat storage materials, and the active aluminum oxide was used as supporting material. Fourier transformation infrared spectroscope (FT-IR), X-ray diffractometer (XRD) and scanning electronic microscope (SEM) were used to determine the chemical structure, crystalloid phase and microstructure of the composites, respectively. The thermal properties and thermal stability were investigated by a differential scanning calorimeter (DSC) and a thermogravimetry analyzer (TGA). The FT-IR analyses results indicated that there is no chemical interaction between the palmitic acid and active aluminum oxide. The SEM results showed that the palmitic acid was well adsorbed into porous network of the active aluminum oxide. The DSC results indicated that the composites melt at 60.25 °C with a latent heat of 84.48 kJ kg −1 and solidify at 56.86 °C with a latent heat of 78.79 kJ kg −1 when the mass ratio of the PA to active aluminum oxide is 0.9:1. Compared with that of the PA, the melting and solidifying time of the composites CPCM5 was reduced by 20.6% and 21.4% because of the increased heat transfer rate through EG addition. The TGA results showed that the active aluminum oxide can improve the thermal stability of the composites. -- Highlights: ► Form-stable PA/active aluminum oxide composites as PCMs were prepared. ► Chemical structure, crystalloid phase and microstructure of composites were determined. ► Thermal properties and thermal stability of the composites were investigated. ► Expanded graphite can improve thermal conductivity of the composites.

Local composition shift of mixed working fluid in gas–liquid flow with phase transition

International Nuclear Information System (INIS)

Xu Xiongwen; Liu Jinping; Cao Le; Li Zeyu

2012-01-01

Local composition shift is an important characteristic of gas-liquid mixture flow with phase transition. It affects the heat transfer process, stream sonic velocity and the mixture distribution in the thermodynamic cycle. Presently, it is mainly calculated through the empirical models of the void fraction from pure fluid experiments. In this paper, we made efforts to obtain it and its rules basing on conservation equations derivation. The result calculated with propane/i-butane binary mixture was verified by the experiment in the evaporator of a refrigerator. As an extending, it was applied to a ternary mixture with components of methane, propane and butane and more information was presented and analyzed. The calculation approach presented in this paper can be applied any multicomponent mixture, and the rules will be helpful to improve the composition shift theory. - Highlights: ► Local composition shift of mixed working fluid in gas–liquid flow was modelled. ► A solution method for local composition of gas–liquid flow was proposed. ► The solution method was verified by the experimental result. ► Local composition shift mechanism of gas–liquid flow was studied

Study of the effects of the interconnectivity of the metallic phase on the electrical and thermal behavior in alumina-ni and zirconia-ni interpenetrating phase composites (IPCs)

International Nuclear Information System (INIS)

Shahid, R.N.; Awais, H.B.; Mehmood, M.; Tariq, N.H.

2007-01-01

The addition of metallic inclusion in ceramic matrix can enhance the electrical and magnetic properties of the composite. Connectivity of conducting phase in an insulating matrix can be studied using electrical conductivity, thermal expansion, Hall Effect and by microscopic techniques. The wide range of application of such studies include, susceptor materials for induction heating, thin film resistors, gel formation permeability in porous structure and electromagnetic behavior of composites. The main phenomenon to be investigated is the insulating to conducting transition by the determination to of percolation range. This phenomenon depends on the concentration, shape, dimension and the crystallographic direction of the imbedded conducting particles. In this investigation variable concerning the percolation range of alumina- Ni and zirconia-Ni composites have been studied. The results provided the role of the size ratio of particles of matrix and the conducting phase, variation of resistance in terms of real part of impedance and thermal expansion on percolation effect. Scanning electron image have been used to study the percolation microscopically. (author)

Concurrent topological design of composite structures and materials containing multiple phases of distinct Poisson's ratios

Science.gov (United States)

Long, Kai; Yuan, Philip F.; Xu, Shanqing; Xie, Yi Min

2018-04-01

Most studies on composites assume that the constituent phases have different values of stiffness. Little attention has been paid to the effect of constituent phases having distinct Poisson's ratios. This research focuses on a concurrent optimization method for simultaneously designing composite structures and materials with distinct Poisson's ratios. The proposed method aims to minimize the mean compliance of the macrostructure with a given mass of base materials. In contrast to the traditional interpolation of the stiffness matrix through numerical results, an interpolation scheme of the Young's modulus and Poisson's ratio using different parameters is adopted. The numerical results demonstrate that the Poisson effect plays a key role in reducing the mean compliance of the final design. An important contribution of the present study is that the proposed concurrent optimization method can automatically distribute base materials with distinct Poisson's ratios between the macrostructural and microstructural levels under a single constraint of the total mass.

Effective properties of dispersed phase reinforced composite materials with perfect and imperfect interfaces

Science.gov (United States)

Han, Ru

This thesis focuses on the analysis of dispersed phase reinforced composite materials with perfect as well as imperfect interfaces using the Boundary Element Method (BEM). Two problems of interest are considered, namely, to determine the limitations in the use of effective properties and the analysis of failure progression at the inclusion-matrix interface. The effective moduli (effective Young's modulus, effective Poisson's ratio, effective shear modulus, and effective bulk modulus) of composite materials can be determined at the mesoscopic level using three-dimensional parallel BEM simulations. By comparing the mesoscopic BEM results and the macroscopic results based on effective properties, limitations in the effective property approach can be determined. Decohesion is an important failure mode associated with fiber-reinforced composite materials. Analysis of failure progression at the fiber-matrix interface in fiber-reinforced composite materials is considered using a softening decohesion model consistent with thermodynamic concepts. In this model, the initiation of failure is given directly by a failure criterion. Damage is interpreted by the development of a discontinuity of displacement. The formulation describing the potential development of damage is governed by a discrete decohesive constitutive equation. Numerical simulations are performed using the direct boundary element method. Incremental decohesion simulations illustrate the progressive evolution of debonding zones and the propagation of cracks along the interfaces. The effect of decohesion on the macroscopic response of composite materials is also investigated.

Structure-phase composition and nano hardness of chrome-fullerite-chrome films irradiated by boron ions

International Nuclear Information System (INIS)

Baran, L.V.

2015-01-01

By methods of atomic force microscopy, X-ray diffraction and nano indentation the research of change of structure phase composition and nano hardness of the chrome - fullerite - chrome films, subjected to implantation by B + ions (E = 80 keV, F = 5*10 17 ions/cm 2 ) are submitted. It is established, that as a result of Boron ion implantation of the chrome - fullerite - chrome films, chrome and fullerite inter fusion on sues, that is the solid-phase interaction and as a result of which forms the heterophase with increased nano hardness. (authors)

An intriguing oscillating combustion phenomenon

NARCIS (Netherlands)

Corbel, J.M.L.; Lingen, J.N.J.; Zevenbergen, J.F.; Gijzeman, O.L.J.; Meijerink, A.

2012-01-01

Strobes are pyrotechnic compositions that emit bright flashes of white or colored light at regular time intervals. The strobe effect has applications in various fields, most notably in the fireworks industry and in the military area (signaling – missile decoys – crowd control). However, the chemical

Phononic band gaps and phase singularities in the ultrasonic response from toughened composites

Science.gov (United States)

Smith, Robert A.; Nelson, Luke J.; Mienczakowski, Martin J.

2018-04-01

Ultrasonic 3D characterization of ply-level features in layered composites, such as out-of-plane wrinkles and ply drops, is now possible with carefully applied analytic-signal analysis. Study of instantaneous amplitude, phase and frequency in the ultrasonic response has revealed some interesting effects, which become more problematic for 3D characterization as the inter-ply resin-layer thicknesses increase. In modern particle-toughened laminates, the thicker resin layers cause phase singularities to be observed; these are locations where the instantaneous amplitude is zero, so the instantaneous phase is undefined. The depth at which these occur has been observed experimentally to vary with resin- layer thickness, such that a phase-singularity surface is formed; beyond this surface, the ultrasonic response is reduced and significantly more difficult to interpret, so a method for removing the effect would be advantageous. The underlying physics has been studied using an analytical one-dimensional multi-layer model. This has been sufficient to determine that the cause is linked to a phononic band gap in the ultrasound transmitted through multiple equally-spaced partial reflectors. As a result, the phase singularity also depends on input-pulse center frequency and bandwidth. Various methods for overcoming the confusing effects in the data have been proposed and subsequently investigated using the analytical model. This paper will show experimental and modelled evidence of phase-singularities and phase-singularity surfaces, as well as the success of methods for reducing their effects.

Thermal properties and heat storage analysis of palmitic acid-TiO_2 composite as nano-enhanced organic phase change material (NEOPCM)

International Nuclear Information System (INIS)

Sharma, R.K.; Ganesan, P.; Tyagi, V.V.; Metselaar, H.S.C.; Sandaran, S.C.

2016-01-01

Highlights: • Novel composite of palmitic acid and TiO_2 nanoparticles with enhanced thermal energy storage capabilities • The composite is thermally reliable and chemically stable. • Thermal conductivity of the composite increases significantly with the loading. - Graphical Abstract: - Abstract: In the present study, the phase change behavior of prepared novel composites of palmitic acid and solid nanoparticles of titanium dioxide (TiO_2) for thermal energy storage has been investigated. The nanoparticles are dispersed into the base fluid in various mass fractions (0.5, 1, 3, and 5%), and their effects on the thermo-physical properties have been investigated. Structural analysis has been carried out by using FESEM, and crystallography was checked by XRD technique. The chemical/functional groups of the base fluid and composite PCMs have been analyzed by using FT-IR spectrum. The observations showed that the TiO_2 nanoparticles do not affect the chemical structure of palmitic acid; however they improve the chemical stability. The phase transition temperature and latent heat of fusion has shown the significant stability with the increase in nanoparticle weight fractions. The accelerated thermal cycle test of the composite shows good thermal reliability for 1500 melt/freeze cycles. Thermal conductivity of palmitic acid increased gradually by 12.7, 20.6, 46.6, and 80% for the nanoparticle weight fractions of 0.5, 1, 3, and 5% respectively. Based on the results, it can be mentioned that the prepared palmitic acid based nano-enhanced organic phase change composite materials can be very well used as potential solar thermal energy storage materials.

Three-Phase Carbon Fiber Amine Functionalized Carbon Nanotubes Epoxy Composite: Processing, Characterisation, and Multiscale Modeling

Directory of Open Access Journals (Sweden)

Kamal Sharma

2014-01-01

Full Text Available The present paper discusses the key issues of carbon nanotube (CNT dispersion and effect of functionalisation on the mechanical properties of multiscale carbon epoxy composites. In this study, CNTs were added in epoxy matrix and further reinforced with carbon fibres. Predetermined amounts of optimally amine functionalised CNTs were dispersed in epoxy matrix, and unidirectional carbon fiber laminates were produced. The effect of the presence of CNTs (1.0 wt% in the resin was reflected by pronounced increase in Young’s modulus, inter-laminar shear strength, and flexural modulus by 51.46%, 39.62%, and 38.04%, respectively. However, 1.5 wt% CNT loading in epoxy resin decreased the overall properties of the three-phase composites. A combination of Halpin-Tsai equations and micromechanics modeling approach was also used to evaluate the mechanical properties of multiscale composites and the differences between the predicted and experimental values are reported. These multiscale composites are likely to be used for potential missile and aerospace structural applications.

In situ studies of uranium-plutonium mixed oxides. Influence of composition on phase equilibria and thermodynamic properties

International Nuclear Information System (INIS)

Strach, Michal

2015-01-01

Due to their physical and chemical properties, mixed uranium-plutonium oxides are considered for fuel in 4. generation nuclear reactors. In this frame, complementary experimental studies are necessary to develop a better understanding of the phenomena that take place during fabrication and operation in the reactor. The focus of this work was to study the U-Pu-O phase diagram in a wide range of compositions and temperatures to ameliorate our knowledge of the phase equilibria in this system. Most of experiments were done using in situ X-ray diffraction at elevated temperatures. The control of the oxygen partial pressure during the treatments made it possible to change the oxygen stoichiometry of the sample, which gave us an opportunity to study rapidly different compositions and the processes involved. The experimental approach was coupled with thermodynamic modeling using the CALPHAD method, to precisely plan the experiments and interpret the obtained results. This approach enabled us to enhance the knowledge of phase equilibria in the U-Pu-O system. (author) [fr

Palmitic acid/polypyrrole composites as form-stable phase change materials for thermal energy storage

International Nuclear Information System (INIS)

Silakhori, Mahyar; Metselaar, Hendrik Simon Cornelis; Mahlia, Teuku Meurah Indra; Fauzi, Hadi; Baradaran, Saeid; Naghavi, Mohammad Sajad

2014-01-01

Highlights: • A novel phase change composite of palmitic acid–polypyrrole(PA–PPy) was fabricated. • Thermal properties of PA–PPy are characterized in different mass ratios of PA–PPy. • Thermal cycling test showed that form stable PCM had a favorable thermal reliability. - Abstract: In this study a novel palmitic acid (PA)/polypyrrole (PPy) form-stable PCMs were readily prepared by in situ polymerization method. PA was used as thermal energy storage material and PPy was operated as supporting material. Form-stable PCMs were investigated by SEM (scanning electron microscopy) and FTIR (Fourier transform infrared spectrometer) analysis that illustrated PA Particles were wrapped by PPy particles. XRD (X-ray diffractometer) was used for crystalline phase of PA/PPy composites. Thermogravimetry analysis (TGA) and differential scanning calorimetry (DSC) were used for investigating Thermal stability and thermal energy storage properties of prepared form-stable PCMs. According to the obtained results the form stable PCMs exhibited favorable thermal stability in terms of their phase change temperature. The form-stable PCMs (79.9 wt% loading of PA) were considered as the highest loading PCM with desirable latent heat storage of 166.3 J/g and good thermal stability. Accelerated thermal cycling tests also showed that form stable PCM had an acceptable thermal reliability. As a consequence of acceptable thermal properties, thermal stability and chemical stability, we can consider the new kind of form stable PCMs for low temperature solar thermal energy storage applications

Ceramic composite resistors of B4C modified by TIO2 and glass phase

International Nuclear Information System (INIS)

Klimiec, E.; Zaraska, W.; Stobiecki, T.

1998-01-01

Technical progress in the manufacturing technology of composite materials resulted in arising of new generation of bulk resistors, resistant to high levels of overloads and high temperature. These resistors can be applied in extremely heavy working conditions, for instance in cooperation with ignition circuits. The resistors investigated in our research were performed on the basis of ceramic composite consisted of semiconductor boron carbide B 4 C as conductive phase, aluminium oxide Al 2 O 3 and non-alkali glass as insulators and titanium dioxide TiO 2 . The technological procedure of the fabrication of resistors and the results of the tests, such as temperature dependence of the electrical resistance exploitation trials, are presented. (author)

Investigation of properties and performance of ceramic composite components: Final report on Phases 3 and 4

Energy Technology Data Exchange (ETDEWEB)

Curtin, W.A.; Halverson, H.; Carter, R.H.; Miraj, N.; Reifsnider, K.L. [Virginia Polytechnic Inst. and State Univ., Blacksburg, VA (United States)

1998-01-15

The objective of the Fossil Energy Advanced Research and Technology Development (AR and TD) Materials Program is to conduct research and development on materials for longer-term fossil energy applications as well as for generic needs of various fossil fuel technologies. The research program of the Materials Response Group at Virginia Tech addresses the need for reliable and durable structural ceramic composites to perform in high temperature environments. The research effort provides an experimental and analytical basis for the transition from properties of materials to performance of actual component structures. Phases 1 and 2 of the present program focused on the development of test capabilities, initial studies of component mechanical response under various conditions and the development of a life prediction methodology. These efforts have been described in previous reports. This report summarizes the major tasks completed under Phases 3 and 4 of the project. Overall, the authors have made significant progress in a broad spectrum of tasks in this program. Their efforts have encompassed component evaluation, assessment of new SiC-based composites with improved high-temperature potential, development of oxide coating materials for SiC, and the extension and development of new models for predicting the durability of composite components under specific operating conditions for various CMC applications. Each of these areas of work is an important area for achieving the ultimate goal of usable SiC-based composites in high-temperature corrosive environments typical of fossil energy applications.

Effect of applied voltage on phase components of composite coatings prepared by micro-arc oxidation

Energy Technology Data Exchange (ETDEWEB)

Zhu, Wenjun [Department of Prosthodontics, Guanghua School of Stomatology, Sun Yat-sen University, Guangzhou 510055 (China); Fang, Yu-Jing [Department of Colorectal Surgery, State Key Laboratory of Oncology in South China, Sun Yat-sen University Cancer Center, Guangzhou 510060 (China); Zheng, Huade [College of Materials Science and Engineering, South China University of Technology, Guangzhou 510641 (China); Tan, Guoxin [Guangdong University of Technology, Guangdong Province 510006 (China); Cheng, Haimei [College of Materials Science and Engineering, South China University of Technology, Guangzhou 510641 (China); Ning, Chengyun, E-mail: imcyning@scut.edu.cn [College of Materials Science and Engineering, South China University of Technology, Guangzhou 510641 (China)

2013-10-01

In this report, we present results from our experiments on composite coatings formed on biomedical titanium substrates by micro-arc oxidation (MAO) in constant-voltage mode. The coatings were prepared on the substrates in an aqueous electrolyte containing calcium acetate and β-glycerol phosphate disodium salt pentahydrate (β-GP). We analyzed the element distribution and phase components of the coatings prepared at different voltages by X-ray diffraction, thin-coating X-ray diffraction, electron-probe microanalysis, and Fourier-transform infrared spectroscopy. The results show that the composite coatings formed at 500 V consist of titania (TiO{sub 2}), hydroxylapatite (HA), and calcium carbonate (CaCO{sub 3}). Furthermore, the concentration of Ca, P, and Ti gradually changes with increasing applied voltage, and the phase components of the composite coatings gradually change from the bottom of the coating to the top: the bottom layer consists of TiO{sub 2}, the middle layer consists of TiO{sub 2} and HA, and the top layer consists of HA and a small amount of CaCO{sub 3}. The formation of HA directly on the coating surface by MAO technique can greatly enhance the surface bioactivity. - Highlights: • Coatings prepared on biomedical titanium substrate by micro-arc oxidation • Coatings composed of titania, hydroxyapatite and calcium carbonate • Hydroxyapatite on the coating surface can enhance the surface bioactivity.

Decomposition of Composite Electric Field in a Three-Phase D-Dot Voltage Transducer Measuring System

Directory of Open Access Journals (Sweden)

Xueqi Hu

2016-10-01

Full Text Available In line with the wider application of non-contact voltage transducers in the engineering field, transducers are required to have better performance for different measuring environments. In the present study, the D-dot voltage transducer is further improved based on previous research in order to meet the requirements for long-distance measurement of electric transmission lines. When measuring three-phase electric transmission lines, problems such as synchronous data collection and composite electric field need to be resolved. A decomposition method is proposed with respect to the superimposed electric field generated between neighboring phases. The charge simulation method is utilized to deduce the decomposition equation of the composite electric field and the validity of the proposed method is verified by simulation calculation software. With the deduced equation as the algorithm foundation, this paper improves hardware circuits, establishes a measuring system and constructs an experimental platform for examination. Under experimental conditions, a 10 kV electric transmission line was tested for steady-state errors, and the measuring results of the transducer and the high-voltage detection head were compared. Ansoft Maxwell Stimulation Software was adopted to obtain the electric field intensity in different positions under transmission lines; its values and the measuring values of the transducer were also compared. Experimental results show that the three-phase transducer is characterized by a relatively good synchronization for data measurement, measuring results with high precision, and an error ratio within a prescribed limit. Therefore, the proposed three-phase transducer can be broadly applied and popularized in the engineering field.

Strain-Detecting Composite Materials

Science.gov (United States)

Wallace, Terryl A. (Inventor); Smith, Stephen W. (Inventor); Piascik, Robert S. (Inventor); Horne, Michael R. (Inventor); Messick, Peter L. (Inventor); Alexa, Joel A. (Inventor); Glaessgen, Edward H. (Inventor); Hailer, Benjamin T. (Inventor)

2016-01-01

A composite material includes a structural material and a shape-memory alloy embedded in the structural material. The shape-memory alloy changes crystallographic phase from austenite to martensite in response to a predefined critical macroscopic average strain of the composite material. In a second embodiment, the composite material includes a plurality of particles of a ferromagnetic shape-memory alloy embedded in the structural material. The ferromagnetic shape-memory alloy changes crystallographic phase from austenite to martensite and changes magnetic phase in response to the predefined critical macroscopic average strain of the composite material. A method of forming a composite material for sensing the predefined critical macroscopic average strain includes providing the shape-memory alloy having an austenite crystallographic phase, changing a size and shape of the shape-memory alloy to thereby form a plurality of particles, and combining the structural material and the particles at a temperature of from about 100-700.degree. C. to form the composite material.

Composition dependence of phase transformation behavior and shape memory effect of Ti(Pt, Ir)

International Nuclear Information System (INIS)

Yamabe-Mitarai, Y.; Hara, T.; Kitashima, T.; Miura, S.; Hosoda, H.

2013-01-01

Highlights: ► The partial isothemal section at 1523 K was determined in Ti–Pt–Ir. ► The high-temperature shape memory effect of Ti(Pt, Ir) was investigated. ► The shape recovery ratio was 72% in Ti–10Pt–32Ir after deformation at 1123 K. ► Ir addition to TiPt is effective to improve shape memory effect of TiPt. -- Abstract: The phase transformation and high-temperature shape memory effect of Ti(Pt, Ir) were investigated. First, the Ti-rich phase boundary of Ti(Pt, Ir) was investigated by phase composition analysis by secondary electron microscopy (SEM) using an electron probe X-ray micro analyzer (EPMA), X-ray diffraction analysis and transmission electron microscopy (TEM). Then, the three alloys Ti–35Pt–10Ir, Ti–22Pt–22Ir, and Ti–10Pt–32Ir (at%) close to the phase boundary but in the single phase of Ti(Pt, Ir) were prepared by the arc melting method. The shape memory effect and crystal structure were investigated by compression loading–unloading tests and high-temperature X-ray diffraction analysis, respectively

Preparation and thermal characterization of oxalic acid dihydrate/bentonite composite as shape-stabilized phase change materials for thermal energy storage

Science.gov (United States)

Han, Lipeng; Xie, Shaolei; Sun, Jinhe; Jia, Yongzhong

2017-03-01

Oxalic acid dihydrate (OAD) which has very high initial phase transition enthalpy is a promising phase change material (PCM). In this paper, shape-stabilized composite PCMs composed of OAD and bentonite were prepared by a facile blending method to overcome the problem of leakage. FT-IR results indicated the interactions between OAD and bentonite, such as the capillary force and the hydrogen bonding, resulting in the confined crystallization process. As a result, the OAD was confined to be amorphous. The thermogravimetric analysis and scanning electron microscope results showed that sample had the best coating effect when the amount of bentonite was 17.7%. The differential scanning calorimetry analyses demonstrated that a decrease in the OAD content was accompanied by a continuous decrease in the melting point and phase change enthalpy of the composites.

The change of NiCrBSi alloys’ phase composition after plasma spraying

Directory of Open Access Journals (Sweden)

A. Dudek

2008-08-01

Full Text Available Material for investigations was NiCrBSi powder for components’ coatings which improve their corrosion resistance as well as resistance to friction wear and erosion. Plasma spraying method was used to produce a coating with thickness of 300 μm on low-alloy steel which was then remelted with the base material. Using X-ray quality analysis, phase composition was determined for: NiCrBSi powder, obtained coating and the alloyed surface layer. Crystallinity degree was also calculated for NiCrBSi layer sprayed on the base material.

Exergy analysis of the solar still integrated nano composite phase change materials

International Nuclear Information System (INIS)

Methre, V.K.; Eswaramoorthy, M.

2015-01-01

This paper communicates the exergy analysis of solar still integrated with nano composite phase change materials for design and operating parameters. Al_2O_3 nano materials (50 nm) is dispersed by weight ratio in paraffin wax at melting state and its thermophysical properties are evaluated using developed correlation. Exergy balance equation for basin liner, thermal energy storage, glass cover and saline water is developed and exergy efficiency is analysed. It is found that exergy efficiency is improved by higher weight ratio of Al_2O_3 nano materials with paraffin wax alone. (author)

Interphase and intergranular stress generation in composites exhibiting plasticity in both phases

International Nuclear Information System (INIS)

Daymond, Mark R; Hartig, Christian; Mecking, Heinrich

2005-01-01

The internal stress state of Fe-Cu composites has been measured by in situ deformation studies using neutron diffraction. A range of volume fractions from 17% Fe to 83% Fe (remainder Cu) have been investigated. Both phase specific and grain family specific elastic strains have been determined. The results are compared with predictions from a multiphase elasto-plastic self-consistent model, and are found to be in good agreement. The selection of parameters used in the model to improve agreement between experimental and predicted results is suggested to be due to changing geometrical constraint

Phase transformations on the surface of YAG composite ceramics under the action of directed laser treatment

Energy Technology Data Exchange (ETDEWEB)

Vlasova, M., E-mail: vlasovamarina@inbox.ru; Márquez Aguilar, P.A.; Escobar Martinez, A.; Kakazey, M.; Guardian Tapia, R.; Trujillo Estrada, A.

2016-07-30

Highlights: • During directed laser treatment of the surface of the composite ceramics consisting of predominantly Y{sub 3}Al{sub 5}O{sub 12} and Al{sub 2}O{sub 3}, the oriented crystallization of YAG and Al{sub 2}O{sub 3} takes place. • As a result of high-temperature heating, in the surface layer of tracks, the partial dissociation of Y{sub 3}Al{sub 5}O{sub 12}, Y{sub 2}Ti{sub 2}O{sub 7}, and Al{sub 2}Y{sub 4}O{sub 9} and enrichment in YAlO{sub 3} occur. • The content of YAlO{sub 3}, the size of YAG crystallites, and their crystallographic texturing depend on the irradiation mode. • After laser treatment, the ceramic material transforms into a three-layer macrostructure consisting of the basic ceramic material, near-surface textured layer, and surface layer. - Abstract: The laser treatment of composite ceramics based on Y{sub 3}Al{sub 5}O{sub 12} with Y{sub 2}Ti{sub 2}O{sub 7}, Al{sub 2}Y{sub 4}O{sub 9}, and Al{sub 2}O{sub 3} additives is accompanied by the melting of the surface layer and formation of tracks. In the volume of tracks, the partial dissociation of Y{sub 3}Al{sub 5}O{sub 12}, Y{sub 2}Ti{sub 2}O{sub 7}, and Al{sub 2}Y{sub 4}O{sub 9}, and the formation of new phases such as YAlO{sub 3} of orthorhombic and hexagonal modifications along with the appearance of additional content of Y{sub 3}Al{sub 5}O{sub 12} and Al{sub 2}O{sub 3} are observed. The content of all these phases depends on the irradiation mode and the phase composition of the ceramics. With increase in the corundum content in ceramic specimens, in the tracks, the Al{sub 2}O{sub 3} content increases, and the Y{sub 3}Al{sub 5}O{sub 12} content decreases. In the volume of tracks, Y{sub 3}Al{sub 5}O{sub 12} crystallites are textured. The size of YAG crystallites and their crystallographic texturing depend on the irradiation mode and Y{sub 3}Al{sub 5}O{sub 12}/Al{sub 2}O{sub 3} phase ratio. On the surface of tracks, a layer enriched in YAlO{sub 3} forms. Thus, as a result of laser

Enhanced performance and interfacial investigation of mineral-based composite phase change materials for thermal energy storage.

Science.gov (United States)

Li, Chuanchang; Fu, Liangjie; Ouyang, Jing; Yang, Huaming

2013-01-01

A novel mineral-based composite phase change materials (PCMs) was prepared via vacuum impregnation method assisted with microwave-acid treatment of the graphite (G) and bentonite (B) mixture. Graphite and microwave-acid treated bentonite mixture (GBm) had more loading capacity and higher crystallinity of stearic acid (SA) in the SA/GBm composite. The SA/GBm composite showed an enhanced thermal storage capacity, latent heats for melting and freezing (84.64 and 84.14 J/g) was higher than those of SA/B sample (48.43 and 47.13 J/g, respectively). Addition of graphite was beneficial to the enhancement in thermal conductivity of the SA/GBm composite, which could reach 0.77 W/m K, 31% higher than SA/B and 196% than pure SA. Furthermore, atomic-level interfaces between SA and support surfaces were depicted, and the mechanism of enhanced thermal storage properties was in detail investigated.

The microstructure and composition of equilibrium phases formed in hypoeutectic Te-In alloy during solidification

Energy Technology Data Exchange (ETDEWEB)

Wang, Baoguang [Department of Materials Physics and Chemistry, University of Science and Technology Beijing, Beijing 100083 (China); Hu, Jinwu [Center of Failure Analysis, Central Iron and Steel Research Institute, Beijing 100081 (China); Wang, Chongyun; Yang, Wenhui [Department of Materials Physics and Chemistry, University of Science and Technology Beijing, Beijing 100083 (China); Tian, Wenhuai, E-mail: wenhuaitian@ustb.edu.cn [Department of Materials Physics and Chemistry, University of Science and Technology Beijing, Beijing 100083 (China)

2017-03-15

As a key tellurium atoms evaporation source for ultraviolet detection photocathode, the hypoeutectic Te{sub 75}In{sub 25} alloy was prepared by employing a slow solidification speed of about 10{sup −2} K/s. The microstructure and chemical composition of the equilibrium phases formed in the as-prepared alloy were studied in this research work. The experimental results show that the as-prepared Te-In alloy was constituted by primary In{sub 2}Te{sub 5} phase and eutectic In{sub 2}Te{sub 5}/Te phases. The eutectic In{sub 2}Te{sub 5}/Te phases are distributed in the grain boundaries of primary In{sub 2}Te{sub 5} phase. With the slow solidification speed, a pure eutectic Te phase without any excessive indium solute was obtained, where Te content of eutectic Te phase is 100 mass%. Moreover, it can be considered that the stress between the In{sub 2}Te{sub 5} and Te phases plays an important role in reducing the tellurium vapor pressure in Te{sub 75}In{sub 25} alloy. - Highlights: • The microstructure of Te-In alloy as an evaporation source was analyzed. • A pure eutectic Te phase was obtained by using a slow solidification speed method. • The relation between vapor pressure and inner-stress in the alloy was discussed.

Surface plasmon resonance induced reduction of high quality Ag/graphene composite at water/toluene phase for reduction of H2O2

International Nuclear Information System (INIS)

Zhang Fengjun; Zhang Kehua; Xie Fazhi; Liu Jin; Dong Hongfei; Zhao Wei; Meng Zeda

2013-01-01

Highlights: ► The Ag/graphene composites have been successfully synthesized in two-phase solvent. ► The surface plasmon resonance of Ag can reduce GO with high deoxygenation and low defect. ► The Ag particles were uniformly distributed on graphene surface. ► The Ag/graphene composites obtained show high superior electrical properties for reduction of H 2 O 2 . - Abstract: Surface plasmon resonance induced synthesis of Ag/graphene composites from Ag/graphene oxide (Ag/GO) in a two-phase (water–toluene) solvent was reported. Transmission electron microscopy (TEM) results revealed that the Ag nanoparticles with size of 5–8 nm were trimly distributed on reduced graphene oxide sheets. Raman and X-ray photoelectron spectroscopy (XPS) have demonstrated low defect density and high deoxygenation degree of graphene in Ag/graphene composite. The excellent structure and morphology of Ag/graphene composites contributed to superior electrical properties for reduction of H 2 O 2 .

Thermal Performance Study of Composite Phase Change Material with Polyacrylicand Conformal Coating.

Science.gov (United States)

Kee, Shin Yiing; Munusamy, Yamuna; Ong, Kok Seng; Cornelis Metselaar, Hendrik Simon; Chee, Swee Yong; Lai, Koon Chun

2017-07-28

The composite PCM was prepared by blending polymethyl methacrylate (PMMA) and myristic acid (MA) in different weight percentages. The MA and PMMA were selected as PCM and supporting material, respectively. As liquid MA may leak out during the phase transition, this study proposes the use of two coatings, namely a polyacrylic coating and a conformal coating to overcome the leakage problem. Both coatings were studied in terms of the leakage test, chemical compatibility, thermal stability, morphology, and reliability. No leakage was found in the PCMs with coatings compared to those without under the same proportions of MA/PMMA, thus justifying the use of coatings in the present study. The chemically compatibility was confirmed by FTIR spectra: the functional groups of PCMs were in accordance with those of coatings. DSC showed that the coatings did not significantly change the melting and freezing temperatures, however, they improved the thermal stability of composite PCMs as seen in TGA analysis. Furthermore, the composite PCMs demonstrated good thermal reliability after 1000 times thermal cycling. The latent heat of melting reduced by only 0.16% and 1.02% for the PCMs coated with conformal coating and polyacrylic coating, respectively. Therefore, the proposed coatings can be considered in preparing fatty acid/PMMA blends attributed to the good stability, compatibility and leakage prevention.

The global influence of dust mineralogical composition on heterogeneous ice nucleation in mixed-phase clouds

International Nuclear Information System (INIS)

Hoose, C; Lohmann, U; Erdin, R; Tegen, I

2008-01-01

Mineral dust is the dominant natural ice nucleating aerosol. Its ice nucleation efficiency depends on the mineralogical composition. We show the first sensitivity studies with a global climate model and a three-dimensional dust mineralogy. Results show that, depending on the dust mineralogical composition, coating with soluble material from anthropogenic sources can lead to quasi-deactivation of natural dust ice nuclei. This effect counteracts the increased cloud glaciation by anthropogenic black carbon particles. The resulting aerosol indirect effect through the glaciation of mixed-phase clouds by black carbon particles is small (+0.1 W m -2 in the shortwave top-of-the-atmosphere radiation in the northern hemisphere)

Green material composites from renewable resources: Polymorphic transitions and phase diagram of beeswax/rosin resin

Energy Technology Data Exchange (ETDEWEB)

Gaillard, Yves [Mines-ParisTech., CEMEF, UMR CNRS 7635, 1 rue Claude Daunesse 06904 Sophia Antipolis cedex (France); Mija, Alice [University of Nice-Sophia Antipolis, Thermokinetic Group, Laboratory of Chemistry of Organic and Metallic Materials C.M.O.M., 06108 Nice Cedex 2 (France); Burr, Alain; Darque-Ceretti, Evelyne; Felder, Eric [Mines-ParisTech., CEMEF, UMR CNRS 7635, 1 rue Claude Daunesse 06904 Sophia Antipolis cedex (France); Sbirrazzuoli, Nicolas, E-mail: sbirrazz@unice.fr [University of Nice-Sophia Antipolis, Thermokinetic Group, Laboratory of Chemistry of Organic and Metallic Materials C.M.O.M., 06108 Nice Cedex 2 (France)

2011-07-10

Highlights: {yields} Blends of Rosin and beeswax are studied by DSC, XRD, and optical microscopy. {yields} The first phase diagram beeswax/rosin is established. {yields} Polymorphic transitions are identified and appear to be highly related to rosin content. - Abstract: Rosin and beeswax are two complex natural materials presenting numerous applications in paints, adhesives, varnishes or inks. Melted, they are particularly interesting for their adhesion properties. This paper establishes the first phase diagram beeswax/rosin blends. A systematic approach using X-ray diffraction (XRD), differential scanning calorimetry (DSC) and polarised optical microscopy (POM) has been performed in order to describe the crystallographic structure and the thermal properties of two materials, beeswax and rosin, and their blends. Indeed, melting, softening and crystallisation temperatures, polymorphic transitions but also crystalline index has been investigated. The resulting phase diagram reveals a complex behaviour in terms of phase transformation and time-dependent phenomenon mainly representative of the complex composition of beeswax.

Formation, Phase, and Elemental Composition of Micro- and Nano-Dimensional Particles of the Fe-Ti System

Science.gov (United States)

Dresvyannikov, A. F.; Kolpakov, M. E.

2018-05-01

X-ray fluorescence, X-ray phase analysis, and transmission Mössbauer and NGR spectrometry are used to study the formation, phase, and elemental composition of Fe-Ti particles. The interaction between Fe(III) ions and dispersed titanium in an aqueous solution containing chloride ions and HF is studied. It is shown that the resulting Fe-Ti samples are a set of core-shell microparticles with titanium cores coated with micro- and nanosized α-Fe nucleation centers with the thinness outer layer of iron(III) oxide characterized by a developed surface.

Determination of equilibrium phase composition in the Hg-HgTe-CdTe system by ''dew point'' method

International Nuclear Information System (INIS)

Vanyukov, A.V.; Krotov, I.I.; Ermakov, A.I.

1978-01-01

Using the ''dew point'' method a study has been made of the equilibrium composition of the solid and liquid phases in the Hg-HgTe-CdTe system at 404, 435 and 454 deg C. It has been pointed out that crystallization of cadmium-rich solid solutions of Cdsub(x)Hgsub(1-x) Te takes place from a liquid phase with a much higher concentration of Hg. The activity of Hg in the liquid phase increases along the liquidus isotherm in the direction from section Hg-HgTe to section HgCdTe in accordance with the increase of its concentration. An increase in activity of Hg in the solid phase of Cdsub(x)Hgsub(1-x)Te has been noted with the reduction of its concentration

Multifunctional Composite Materials, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — Polymeric composite materials that are currently utilized in aircraft structures are susceptible to significant damage from lightning strikes. Enhanced electrical...

Structure, phase composition and microhardness of vacuum-arc multilayered Ti/Al, Ti/Cu, Ti/Fe, Ti/Zr nano-structures with different periods

Energy Technology Data Exchange (ETDEWEB)

Demchishin, A.V., E-mail: ademch@meta.ua [Institute of Problems in Material Science, NASU, Kiev (Ukraine); Gnilitskyi, I., E-mail: iaroslav.gnilitskyi@unimore.it [DISMI – Department of Sciences and Methods for Engineering, University of Modena and Reggio Emilia, Reggio Emilia (Italy); Orazi, L., E-mail: leonardo.orazi@unimore.it [DISMI – Department of Sciences and Methods for Engineering, University of Modena and Reggio Emilia, Reggio Emilia (Italy); Ascari, A., E-mail: a.ascari@unibo.it [DIN – Department of Industrial Engineering, University of Bologna, Bologna (Italy)

2015-07-01

Highlights: • Multilayer coatings of Ti/Fe, Ti/Al, Ti/Cu and Ti/Zr are generated. • Microstructure and morphology of the different systems are investigated. • XR diffraction analysis was performed to investigate phases composition. • Effects of inter metallic phases on microhardess are investigated. • Correlations between parameters and layer thickness are outlined. - Abstract: The microstructure, phase composition and microhardness of multilayered Ti/Al, Ti/Cu, Ti/Fe and Ti/Zr condensates produced on stainless steel substrates via vacuum-arc evaporation of pure metals were studied. The sublayer periods (Λ) were regulated in the range 80–850 nm by varying the vacuum discharge current and the duration of the successive depositions of metallic plasma onto the substrates while maintaining the total deposition time constant. The regularity of the obtained nanostructures was investigated by scanning and transmission electron microscopy while phase compositions were identified with X-ray diffraction (XRD) analysis in order to evidence the presence of interdiffusion and the amount of intermetallics. Condensates cross sections were mechanically characterized by means of microhardness tests. Measurements were correlated to the periods and to the presence of intermetallics.

Structure, phase composition and microhardness of vacuum-arc multilayered Ti/Al, Ti/Cu, Ti/Fe, Ti/Zr nano-structures with different periods

International Nuclear Information System (INIS)

Demchishin, A.V.; Gnilitskyi, I.; Orazi, L.; Ascari, A.

2015-01-01

Highlights: • Multilayer coatings of Ti/Fe, Ti/Al, Ti/Cu and Ti/Zr are generated. • Microstructure and morphology of the different systems are investigated. • XR diffraction analysis was performed to investigate phases composition. • Effects of inter metallic phases on microhardess are investigated. • Correlations between parameters and layer thickness are outlined. - Abstract: The microstructure, phase composition and microhardness of multilayered Ti/Al, Ti/Cu, Ti/Fe and Ti/Zr condensates produced on stainless steel substrates via vacuum-arc evaporation of pure metals were studied. The sublayer periods (Λ) were regulated in the range 80–850 nm by varying the vacuum discharge current and the duration of the successive depositions of metallic plasma onto the substrates while maintaining the total deposition time constant. The regularity of the obtained nanostructures was investigated by scanning and transmission electron microscopy while phase compositions were identified with X-ray diffraction (XRD) analysis in order to evidence the presence of interdiffusion and the amount of intermetallics. Condensates cross sections were mechanically characterized by means of microhardness tests. Measurements were correlated to the periods and to the presence of intermetallics

Preparation and thermal conductivity enhancement of composite phase change materials for electronic thermal management

International Nuclear Information System (INIS)

Wu, Weixiong; Zhang, Guoqing; Ke, Xiufang; Yang, Xiaoqing; Wang, Ziyuan; Liu, Chenzhen

2015-01-01

Highlights: • A kind of composite phase change material board (PCMB) is prepared and tested. • PCMB presents a large thermal storage capacity and enhanced thermal conductivity. • PCMB displays much better cooling effect in comparison to natural air cooling. • PCMB presents different cooling characteristics in comparison to ribbed radiator. - Abstract: A kind of phase change material board (PCMB) was prepared for use in the thermal management of electronics, with paraffin and expanded graphite as the phase change material and matrix, respectively. The as-prepared PCMB presented a large thermal storage capacity of 141.74 J/g and enhanced thermal conductivity of 7.654 W/(m K). As a result, PCMB displayed much better cooling effect in comparison to natural air cooling, i.e., much lower heating rate and better uniformity of temperature distribution. On the other hand, compared with ribbed radiator technology, PCMB also presented different cooling characteristics, demonstrating that they were suitable for different practical application

Phase-field modeling of mixing/demixing of regular binary mixtures with a composition-dependent viscosity

Science.gov (United States)

Lamorgese, A.; Mauri, R.

2017-04-01

We simulate the mixing (demixing) process of a quiescent binary liquid mixture with a composition-dependent viscosity which is instantaneously brought from the two-phase (one-phase) to the one-phase (two-phase) region of its phase diagram. Our theoretical approach follows a standard diffuse-interface model of partially miscible regular binary mixtures wherein convection and diffusion are coupled via a nonequilibrium capillary force, expressing the tendency of the phase-separating system to minimize its free energy. Based on 2D simulation results, we discuss the influence of viscosity ratio on basic statistics of the mixing (segregation) process triggered by a rapid heating (quench), assuming that the ratio of capillary to viscous forces (a.k.a. the fluidity coefficient) is large. We show that, for a phase-separating system, at a fixed value of the fluidity coefficient (with the continuous phase viscosity taken as a reference), the separation depth and the characteristic length of single-phase microdomains decrease monotonically for increasing values of the viscosity of the dispersed phase. This variation, however, is quite small, in agreement with experimental results. On the other hand, as one might expect, at a fixed viscosity of the dispersed phase both of the above statistics increase monotonically as the viscosity of the continuous phase decreases. Finally, we show that for a mixing system the attainment of a single-phase equilibrium state by coalescence and diffusion is retarded by an increase in the viscosity ratio at a fixed fluidity for the dispersed phase. In fact, for large enough values of the viscosity ratio, a thin film of the continuous phase becomes apparent when two drops of the minority phase approach each other, which further retards coalescence.

Effects of insulating vanadium oxide composite in concomitant mixed phases via interface barrier modulations on the performance improvements in metal-insulator-metal diodes

Directory of Open Access Journals (Sweden)

Kaleem Abbas

2018-03-01

Full Text Available The performance of metal-insulator-metal diodes is investigated for insulating vanadium oxide (VOx composite composed of concomitant mixed phases using the Pt metal as the top and the bottom electrodes. Insulating VOx composite in the Pt/VOx/Pt diode exhibits a high asymmetry of 10 and a very high sensitivity of 2,135V−1 at 0.6 V. The VOx composite provides Schottky-like barriers at the interface, which controls the current flow and the trap-assisted conduction mechanism. Such dramatic enhancement in asymmetry and rectification performance at low applied bias may be ascribed to the dynamic control of the insulating and metallic phases in VOx composites. We find that the nanostructure details of the insulating VOx layer can be critical in enhancing the performance of MIM diodes.

Titanium Matrix Composite Pressure Vessel, Phase II

Data.gov (United States)

National Aeronautics and Space Administration — For over 15 years, FMW Composite Systems has developed Metal Matrix Composite manufacturing methodologies for fabricating silicon-carbide-fiber-reinforced titanium...

Crystal structure and phase composition of aluminium thin films with holmium additions

International Nuclear Information System (INIS)

Koleshko, V.M.; Belitskij, V.F.; Obukhov, V.E.; Rumak, N.V.; Urban, T.P.

1984-01-01

The effect of holmium additions on the crystal structure and phase composition of thin aluminium films has been studied. A regularity in grain size changes in aluminium thin films versus the holmium content in them is established. The holmium introduction is shown to result in the appearance of axial texture in the aluminium films, the texture axis being determined by the quantity of the addition. During heat treatment of the aluminium films, containing holmium additions, in the range of low ( approximately 100-200 deg C) annealing temperatures holmium monohydroxide is formed, and at annealing temperatures 300 deg C 0 3 is formed

Densification, phase stability and in vitro biocompatibility property of hydroxyapatite-10 wt% silver composites.

Science.gov (United States)

Nath, Shekhar; Kalmodia, Sushma; Basu, Bikramjit

2010-04-01

In this paper, we demonstrate how a simple fabrication route, i.e., pressureless sintering of mechanically mixed powders can be employed to develop hydroxyapatite (HAp, Ca(10)(PO(4))(6)(OH)(2))-silver (Ag) bioceramic composites with superior combination of physical (hardness, toughness), non-cytotoxicity, cytocompatiblity and anti-microbial property. The densification results show that such composites can be sintered at 1200 degrees C for 2 h near to theoretical density (>98% rho(th).) An important observation is that the dissociation of HAp phase can be prevented during sintering up to 1300 degrees C for 2 h in HAp-10 wt% Ag composites. The stability of HAp in presence of silver is discussed in reference to the results obtained using XRD, FTIR and Raman spectroscopy. The hardness values of the composites are comparable (approximately 6.5 GPa) to that of pure HAp, despite of the presence of softer Ag particles. The sintered composites exhibit modest crack growth resistance property and their toughness varies in the range of 0.9-1.2 MPa m(0.5), depending on sintering temperature. For selected samples, the in vitro characterization was performed using mouse fibroblast (L929) and human osteosarcoma (MG63) cell lines. The combination of biochemical assays (MTT, ALP and osteocalcin) confirm that HAp-10 wt% Ag biocomposites have comparable or even better cellular viability, osteogenic differentiation and bone mineralization as well as osteoinduction property. Antibacterial experiments involving gram-negative bacteria, Escherichia coli confirm excellent bactericidal property of HAp-10 wt% Ag composites, sintered using mechanically mixed powders.

Phase separation and formation of omega phase in the beta matrix of a Ti-V-Cu alloy

Energy Technology Data Exchange (ETDEWEB)

Ng, H.P. [ARC Centre of Excellence for Design in Light Metals, Department of Materials Engineering, Monash University, Victoria 3800 (Australia); Devaraj, A.; Nag, S. [Center for Advanced Research and Technology, Department of Materials Science and Engineering, University of North Texas, Denton, TX (United States); Bettles, C.J. [ARC Centre of Excellence for Design in Light Metals, Department of Materials Engineering, Monash University, Victoria 3800 (Australia); Gibson, M. [CSIRO Process Science and Engineering, Locked Bag 10, Clayton South, Victoria 3169 (Australia); Fraser, H.L. [Center for the Accelerated Maturation of Materials, Department of Materials Science and Engineering, The Ohio State University, Columbus, OH (United States); Muddle, B.C. [ARC Centre of Excellence for Design in Light Metals, Department of Materials Engineering, Monash University, Victoria 3800 (Australia); Banerjee, R., E-mail: rajarshi.banerjee@unt.edu [Center for Advanced Research and Technology, Department of Materials Science and Engineering, University of North Texas, Denton, TX (United States)

2011-05-15

The formation of the {omega} phase in the presence of simultaneous development of compositional modulations (or phase separation) within the body-centered cubic {beta} matrix phase of a Ti-10V-6Cu (wt.%) alloy during continuous cooling has been investigated using a combination of transmission electron microscopy and atom probe tomography. While a water quench from the high-temperature {beta} phase field allows apparently athermal formation of {omega} domains without any significant partitioning of solute or modulation in matrix composition, subsequent annealing at 500 {sup o}C for just 60 s leads to unusually rapid growth of the {omega} domains concurrent with, but apparently independent of, a slower development of finer-scale modulations in solute composition occurring apparently uniformly across both {omega} and {beta} phases. In contrast, on slower air cooling from the solution treatment temperature, there are pronounced compositional fluctuations within the {beta} phase, presumably as a product of spinodal decomposition, that are detectable prior to the formation of {omega} phase. The {omega} phase subsequently forms preferentially in solute-depleted regions of the matrix {beta}, with a composition reflecting the local matrix composition and a solute content significantly lower than the average matrix composition. As a result, it has a cuboidal morphology, distinguishably different from the elliposoidal form that is observed in samples water-quenched and annealed at 500 deg. C.

Intermetallic phases in the iron-rich region of the Zr-Fe phase diagram

International Nuclear Information System (INIS)

Granovsky, M.S.; Arias, D.

1996-01-01

Intermetallic phases in the Fe-rich region of the Zr-Fe system are studied by X-ray diffraction and optical and electron microscopy. The chemical composition of each phase has been quantitatively measured in a electron microprobe. The stable phases found in this region are ZrFe 2 , Zr 6 Fe 23 and (αFe). ZrFe 2 is identified as a cubic Laves type phase (C15) and the ZrFe 2 /ZrFe 2 +Zr 6 Fe 23 boundary composition is 73±1 at.% Fe. Zr 6 Fe 23 is a cubic phase of the Th 6 Mn 23 type and its composition is 80.0±1.5 at.% Fe. The eutectic L↔Zr 6 Fe 23 +τ-Fe transformation temperature and composition are 1325 C and 91±1 at.% Fe, respectively. The solubility of Zr in τ-Fe at 1012 C is 500±50 appm and 1000±100 appm close to the eutectic temperature. (orig.)

Hydroxyapatite and zirconia composites: Effect of MgO and MgF2 on the stability of phases and sinterability

International Nuclear Information System (INIS)

Evis, Zafer; Usta, Metin; Kutbay, Isil

2008-01-01

Composites of hydroxyapatite with cubic zirconia with MgO or MgF 2 were pressureless sintered at temperatures from 1000 to 1300 deg. C. The reactions and transformations of phases were monitored with X-ray diffraction. For the hydroxyapatite and zirconia composites with MgO, calcium diffused from hydroxyapatite into the zirconia, and hydroxyapatite decomposed to tri-calcium phosphate at sintering temperatures higher than 1000 deg. C. Above about 1200 deg. C, CaZrO 3 was formed. Composites containing the MgF 2 decomposed slower than the composites with MgO which was verified by the changes in the lattice volume of the hydroxyapatite left in the composites. Fluorine ions in MgF 2 diffused into hydroxyapatite which resulted in thermal stability at high sintering temperatures. Composites with MgF 2 had higher hardness than those with MgO. The lowest porosity was found in a composite initially containing 10 wt% cubic zirconia and 5 wt% MgF 2

Multilayer Electroactive Polymer Composite Material

Science.gov (United States)

Harrison, Joycelyn S. (Inventor); Holloway, Nancy M. (Inventor); Park, Cheol (Inventor); Draughon, Gregory K. (Inventor); Ounaies, Zoubeida (Inventor)

2011-01-01

An electroactive material comprises multiple layers of electroactive composite with each layer having unique dielectric, electrical and mechanical properties that define an electromechanical operation thereof when affected by an external stimulus. For example, each layer can be (i) a 2-phase composite made from a polymer with polarizable moieties and an effective amount of carbon nanotubes incorporated in the polymer for a predetermined electromechanical operation, or (ii) a 3-phase composite having the elements of the 2-phase composite and further including a third component of micro-sized to nano-sized particles of an electroactive ceramic incorporated in the polymer matrix.

Pyrotechnic Shock Analysis Using Statistical Energy Analysis

Science.gov (United States)

2015-10-23

SEA subsystems. A couple of validation examples are provided to demonstrate the new approach. KEY WORDS : Peak Ratio, phase perturbation...Ballistic Shock Prediction Models and Techniques for Use in the Crusader Combat Vehicle Program,” 11th Annual US Army Ground Vehicle Survivability

Nickel-cadmium batteries: effect of electrode phase composition on acid leaching process.

Science.gov (United States)

Nogueira, C A; Margarido, F

2012-01-01

At the end of their life, Ni-Cd batteries cause a number of environmental problems because of the heavy metals they contain. Because of this, recycling of Ni-Cd batteries has been carried out by dedicated companies using, normally, pyrometallurgical technologies. As an alternative, hydrometallurgical processes have been developed based on leaching operations using several types of leachants. The effect of factors like temperature, acid concentration, reaction time, stirring speed and grinding of material on the leaching yields of metals contained in anodic and cathodic materials (nickel, cadmium and cobalt) using sulphuric acid, is herein explained based on the structural composition of the electrode materials. The nickel, cobalt and cadmium hydroxide phases, even with a small reaction time (less than 15 minutes) and low temperature (50 degrees C) and acid concentration (1.1 M H2SO4), were efficiently leached. However, leaching of the nickel metallic phase was more difficult, requiring higher values of temperature, acid concentration and reaction time (e.g. 85 degrees C, 1.1 M H2SO4 and 5 h, respectively) in order to obtain a good leaching efficiency for anodic and cathodic materials (70% and 93% respectively). The stirring speed was not significant, whereas the grinding of electrode materials seems to promote the compaction of particles, which appears to be critical in the leaching of Ni degrees. These results allowed the identification and understanding of the relationship between the structural composition of electrode materials and the most important factors that affect the H2SO4 leaching of spent Ni-Cd battery electrodes, in order to obtain better metal-recovery efficiency.

Study of the structure and phase composition of nanocrystalline silicon oxynitride films synthesized by ICP-CVD

International Nuclear Information System (INIS)

Fainer, N.I.; Kosinova, M.L.; Maximovsky, E.A.; Rumyantsev, Yu.M.; Kuznetsov, F.A.; Kesler, V.G.; Kirienko, V.V.

2005-01-01

Thin nanocrystalline silicon oxynitride films were synthesized for the first time at low temperatures (373-750 K) by inductively coupled plasma chemical vapor deposition (ICP-CVD) using gas mixture of oxygen and hexamethyldisilazane Si 2 NH(CH 3 ) 6 (HMDS) as precursors. Single crystal Si (1 0 0) wafers 100 mm in diameter were used as substrates. Physicochemical properties of the thin films were examined using ellipsometry, IR spectroscopy, Auger electron and X-ray photoelectron spectroscopy and XRD using synchrotron radiation (SR). The studies of the phase composition of nanocrystalline films of silicon oxynitride showed that in the case of oxygen excess in the initial gas mixture, they contain a mixture of hexagonal phases: h-SiO 2 and α-Si 3 N 4 . These phases consist of oriented nanocrystals of 2-3 nm size. In case of decrease of oxygen concentration in the initial gas mixture, the fraction of the α-Si 3 N 4 phase increases

Study of the structure and phase composition of nanocrystalline silicon oxynitride films synthesized by ICP-CVD

Energy Technology Data Exchange (ETDEWEB)

Fainer, N.I. [Nikolaev Institute of Inorganic Chemistry SB RAS, 3, Acad. Lavrentjev Pr., Novosibirsk 630090 (Russian Federation)]. E-mail: nadezhda@che.nsk.su; Kosinova, M.L. [Nikolaev Institute of Inorganic Chemistry SB RAS, 3, Acad. Lavrentjev Pr., Novosibirsk 630090 (Russian Federation); Maximovsky, E.A. [Nikolaev Institute of Inorganic Chemistry SB RAS, 3, Acad. Lavrentjev Pr., Novosibirsk 630090 (Russian Federation); Rumyantsev, Yu.M. [Nikolaev Institute of Inorganic Chemistry SB RAS, 3, Acad. Lavrentjev Pr., Novosibirsk 630090 (Russian Federation); Kuznetsov, F.A. [Nikolaev Institute of Inorganic Chemistry SB RAS, 3, Acad. Lavrentjev Pr., Novosibirsk 630090 (Russian Federation); Kesler, V.G. [Institute of Semiconductor Physics SB RAS, Acad. Lavrentjev pr., 13, Novosibirsk 630090 (Russian Federation); Kirienko, V.V. [Institute of Semiconductor Physics SB RAS, Acad. Lavrentjev pr., 13, Novosibirsk 630090 (Russian Federation)

2005-05-01

Thin nanocrystalline silicon oxynitride films were synthesized for the first time at low temperatures (373-750 K) by inductively coupled plasma chemical vapor deposition (ICP-CVD) using gas mixture of oxygen and hexamethyldisilazane Si{sub 2}NH(CH{sub 3}){sub 6} (HMDS) as precursors. Single crystal Si (1 0 0) wafers 100 mm in diameter were used as substrates. Physicochemical properties of the thin films were examined using ellipsometry, IR spectroscopy, Auger electron and X-ray photoelectron spectroscopy and XRD using synchrotron radiation (SR). The studies of the phase composition of nanocrystalline films of silicon oxynitride showed that in the case of oxygen excess in the initial gas mixture, they contain a mixture of hexagonal phases: h-SiO{sub 2} and {alpha}-Si{sub 3}N{sub 4}. These phases consist of oriented nanocrystals of 2-3 nm size. In case of decrease of oxygen concentration in the initial gas mixture, the fraction of the {alpha}-Si{sub 3}N{sub 4} phase increases.

Phases of variable composition in the system Ba3-xSrxEr(BO3)3 (0≤x≤3.0)

International Nuclear Information System (INIS)

Khamaganova, T.N.

2008-01-01

The possibility of preparing two series of solid solutions in the system Ba 3-x Sr x Er(BO 3 ) 3 (0 ≤ x ≤ 3.0), crystallizing in different structural types, was examined. Samples of the phases of variable composition were synthesized by solid-phase reactions over the temperature range 500-1000 deg C, and their X-ray diffraction characteristics were determined. It is found that the triple phases prepared form two series of substitutional solid solutions in the system studied [ru

Preparation and properties of shape-stabilized phase change materials based on fatty acid eutectics and cellulose composites for thermal energy storage

International Nuclear Information System (INIS)

Cao, Lei; Tang, Yaojie; Fang, Guiyin

2015-01-01

Shape-stabilized fatty acid eutectics/carboxy methyl cellulose-1 composites as phase change materials (PCMs) were synthesized by absorbing liquid eutectics into the carboxy methyl cellulose-1 fibers. The chemical structure, crystalloid phase and morphology were determined by the Fourier transformation infrared spectroscope, X-ray diffractometer and scanning electronic microscope. The thermal properties and thermal stability were measured by the differential scanning calorimeter, thermogravimetric analyzer and the thermal cycling test, respectively. The results indicate that the eutectics are well adsorbed in the porous structure of the carboxy methyl cellulose-1. According to the DSC (differential scanning calorimeter) results, the composites melt at 32.2 °C with latent heat of 114.6 kJ/kg and solidify at 29.2 °C with latent heat of 106.8 kJ/kg. The thermal cycling test proves that the composites have good thermal reliability. It is envisioned that the prepared shape-stabilized PCMs have considerable potential for developing their roles in thermal energy storage. - Highlights: • The fatty acid eutectic/carboxy methyl cellulose-1 composites as PCMs were prepared. • Chemical structure and microstructure of composites were determined by FT-IR and SEM. • Thermal properties and stabilities were investigated by DSC and TGA. • The thermal cycling test confirmed that the composite has good thermal reliability

Nano-composite stainless steel

Science.gov (United States)

Dehoff, Ryan R.; Blue, Craig A.; Peter, William H.; Chen, Wei; Aprigliano, Louis F.

2015-07-14

A composite stainless steel composition is composed essentially of, in terms of wt. % ranges: 25 to 28 Cr; 11 to 13 Ni; 7 to 8 W; 3.5 to 4 Mo; 3 to 3.5 B; 2 to 2.5 Mn; 1 to 1.5 Si; 0.3 to 1.7 C; up to 2 O; balance Fe. The composition has an austenitic matrix phase and a particulate, crystalline dispersed phase.

Chiral separation of aryloxyphenoxy-propionate herbicides in a permethyl-β-cyclodextrin based column. Influence of temperature and mobile phase composition on enantioselectivity.

Science.gov (United States)

Lubomirsky, Ester; Padró, Juan M; Di Loreto, Héctor; Castells, Cecilia B

2017-08-01

We used a permethyl-β-cyclodextrin chiral stationary phase under reversed-phase conditions for the chiral separation of four aryloxyphenoxy-propionate herbicides (fenoxaprop-p-ethyl, quizalofop-p-ethyl and tefuryl, and haloxyfop-p-methyl) with mixtures of methanol, ethanol, 2-propanol, n-propanol, tert-butanol, or acetonitrile and water as mobile phases and investigated the influence of mobile phase composition and column temperature (from 0 to 50°C) on the separation. The retention factors (k) and selectivity factors (α) of all the herbicides investigated decreased with increasing temperature. The lnα versus 1/T and lnk versus 1/T plots for the enantiomers of the chiral pesticides were linear within the range of 0-50°C with all alcohol/water mixtures constituting the mobile phase, but the lnk versus 1/T plots were nonlinear for all the enantiomers chromatographed in acetonitrile/water mixtures. The thermodynamic parameters based on linear van't Hoff plots were calculated. The influence of temperature and mobile phase composition on the enantioseparation of the solutes has rarely been considered simultaneously. The temperature and the solvents used in the mobile phase, however, were found to have a profound effect on the enantioseparation of these herbicides. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Preparation, morphology and thermal properties of electrospun fatty acid eutectics/polyethylene terephthalate form-stable phase change ultrafine composite fibers for thermal energy storage

International Nuclear Information System (INIS)

Cai Yibing; Ke Huizhen; Lin Liang; Fei Xiuzhu; Wei Qufu; Song Lei; Hu Yuan; Fong Hao

2012-01-01

Highlights: ► Electrospun binary fatty acid eutectics/PET ultrafine composite fibers were prepared. ► Fatty acid eutectics had appropriate phase transition temperature and heat enthalpy. ► Their morphological structures and thermal properties were different from each other. ► Composite fibers could be innovative form-stable PCMs for thermal energy storage. - Abstract: The ultrafine composite fibers based on the composites of binary fatty acid eutectics and polyethylene terephthalate (PET) with varied fatty acid eutectics/PET mass ratios (50/100, 70/100, 100/100 and 120/100) were fabricated using the technique of electrospinning as form-stable phase change materials (PCMs). The five binary fatty acid eutectics including LA–MA, LA–PA, MA–PA, MA–SA and PA–SA were prepared according to Schrader equation, and then were selected as an innovative type of solid–liquid PCMs. The results characterized by differential scanning calorimeter (DSC) indicated that the prepared binary fatty acid eutectics with low phase transition temperatures and high heat enthalpies for climatic requirements were more suitable for applications in building energy storage. The structural morphologies, thermal energy storage and thermal stability properties of the ultrafine composite fibers were investigated by scanning electron microscope (SEM), DSC and thermogravimetric analysis (TGA), respectively. SEM images revealed that the electrospun binary fatty acid eutectics/PET ultrafine composite fibers possessed the wrinkled surfaces morphologies compared with the neat PET fibers with cylindrical shape and smooth surfaces; the grooves or ridges on the corrugated surface of the ultrafine composite fibers became more and more prominent with increasing fatty acid eutectics amount in the composite fibers. The fibers with the low mass ratio maintained good structural morphologies while the quality became worse when the mass ratio is too high (more than 100/100). DSC measurements

Intermetallic phases in the iron-rich region of the Zr-Fe phase diagram

Energy Technology Data Exchange (ETDEWEB)

Granovsky, M.S. [Comision Nacional de Energia Atomica, Buenos Aires (Argentina). Dept. de Materiales; Arias, D. [Comision Nacional de Energia Atomica, Buenos Aires (Argentina). Dept. de Materiales

1996-04-01

Intermetallic phases in the Fe-rich region of the Zr-Fe system are studied by X-ray diffraction and optical and electron microscopy. The chemical composition of each phase has been quantitatively measured in a electron microprobe. The stable phases found in this region are ZrFe{sub 2}, Zr{sub 6}Fe{sub 23} and ({alpha}Fe). ZrFe{sub 2} is identified as a cubic Laves type phase (C15) and the ZrFe{sub 2}/ZrFe{sub 2}+Zr{sub 6}Fe{sub 23} boundary composition is 73{+-}1 at.% Fe. Zr{sub 6}Fe{sub 23} is a cubic phase of the Th{sub 6}Mn{sub 23} type and its composition is 80.0{+-}1.5 at.% Fe. The eutectic L{r_reversible}Zr{sub 6}Fe{sub 23}+{tau}-Fe transformation temperature and composition are 1325 C and 91{+-}1 at.% Fe, respectively. The solubility of Zr in {tau}-Fe at 1012 C is 500{+-}50 appm and 1000{+-}100 appm close to the eutectic temperature. (orig.).

Impact of metabolism and growth phase on the hydrogen isotopic composition of microbial fatty acids

Science.gov (United States)

Heinzelmann, Sandra M.; Villanueva, Laura; Sinke-Schoen, Danielle; Sinninghe Damsté, Jaap S.; Schouten, Stefan; van der Meer, Marcel T. J.

2015-01-01

Microorganisms are involved in all elemental cycles and therefore it is important to study their metabolism in the natural environment. A recent technique to investigate this is the hydrogen isotopic composition of microbial fatty acids, i.e., heterotrophic microorganisms produce fatty acids enriched in deuterium (D) while photoautotrophic and chemoautotrophic microorganisms produce fatty acids depleted in D compared to the water in the culture medium (growth water). However, the impact of factors other than metabolism have not been investigated. Here, we evaluate the impact of growth phase compared to metabolism on the hydrogen isotopic composition of fatty acids of different environmentally relevant microorganisms with heterotrophic, photoautotrophic and chemoautotrophic metabolisms. Fatty acids produced by heterotrophs are enriched in D compared to growth water with εlipid/water between 82 and 359‰ when grown on glucose or acetate, respectively. Photoautotrophs (εlipid/water between −149 and −264‰) and chemoautotrophs (εlipid/water between −217 and −275‰) produce fatty acids depleted in D. Fatty acids become, in general, enriched by between 4 and 46‰ with growth phase which is minor compared to the influence of metabolisms. Therefore, the D/H ratio of fatty acids is a promising tool to investigate community metabolisms in nature. PMID:26005437

Experimental evidence for several spheroid growth mechanisms in the liquid-phase sintered tungsten-base composites

International Nuclear Information System (INIS)

Zukas, E.G.; Rogers, P.S.Z.; Rogers, R.S.

1976-01-01

The generally accepted mechanism for spheroid growth during sintering of tungsten-base composites in the presence of a liquid phase is the dissolution of the small spheroids with simultaneous precipitation of tungsten from the molten matrix onto the larger spheroids, the process being driven by the difference in surface energy between the larger and smaller spheroids. From theoretical considerations, the slope of the straight line of log diameter versus log time should be 1 / 3 for this process. The experimental evidence for the dissolution and reprecipitation mechanism is meager, being based primarily on the spheroid growth rate during the latter stages of liquid-phase sintering. Experimental evidence is presented that shows spheroid growth taking place in systems where the tungsten and the matrix are mutually insoluble thereby making dissolution and reprecipitation impossible. Furthermore, the results from these studies and others using the usual matrix compositions indicate that spheroid growth takes place predominantly by the combination or coalescence of two or more spheroids. Deposition of tungsten from the molten matrix also occurs, although not necessarily on spheroid surfaces which have the lowest surface energy. Thus, many mechanisms, each depending on temperature and other variables, operate simultaneously. A satisfactory theoretical treatment must include them all

Quantitative characterization of the formation of an interpenetrating phase composite in polystyrene from the percolation of multiwalled carbon nanotubes

International Nuclear Information System (INIS)

Kota, Arun K; Cipriano, Bani H; Powell, Dan; Raghavan, Srinivasa R; Bruck, Hugh A

2007-01-01

For the first time, an interpenetrating phase polymer nanocomposite formed by the percolation of multiwalled carbon nanotubes (MWCNTs) in polystyrene (PS) has been quantitatively characterized through electrical conductivity measurements and melt rheology. Both sets of measurements, in conjunction with scanning electron microscopy (SEM) images, indicate the presence of a continuous phase of percolated MWCNTs appearing at particle concentrations exceeding 2 vol% MWCNTs in PS. To quantify the amount of this continuous phase present in the PS/MWCNT composite, electrical conductivity data at various MWCNT concentrations, β, are correlated with a proposed degree of percolation, C-bar(β), developed using a conventional power-law formula with and without a percolation threshold. To quantify the properties of the interpenetrating phase polymer nanocomposite, the PS/MWCNT composite is treated as a combination of two phases: a continuous phase consisting of a pseudo-solid-like network of percolated MWCNTs, and a continuous PS phase reinforced by non-interacting MWCNTs. The proposed degree of percolation is used to quantify the distribution of MWCNTs among the phases, and is then used in a rule-of-mixtures formulation for the storage modulus, G'(β, C-bar(β), ω), and the loss modulus, G''(β, C-bar(β), ω), to quantify the properties of the continuous phase consisting of percolated MWCNTs and the continuous PS phase reinforced by non-interacting MWCNTs from the experimental melt rheology data. The properties of the continuous phase of percolated MWCNTs are indicative of a scaffold-like microstructure exhibiting an elastic behavior with a complex modulus of 360 kPa at lower frequencies and viscoplastic behavior with a complex viscosity of 6 kPa s rad -1 at higher frequencies, most likely due to a stick-slip friction mechanism at the interface of the percolated MWCNTs. Additional evidence of this microstructure was obtained via scanning electron microscopy. This research

Data on a Laves phase intermetallic matrix composite in situ toughened by ductile precipitates.

Science.gov (United States)

Knowles, Alexander J; Bhowmik, Ayan; Purkayastha, Surajit; Jones, Nicholas G; Giuliani, Finn; Clegg, William J; Dye, David; Stone, Howard J

2017-10-01

The data presented in this article are related to the research article entitled "Laves phase intermetallic matrix composite in situ toughened by ductile precipitates" (Knowles et al.) [1]. The composite comprised a Fe 2 (Mo, Ti) matrix with bcc (Mo, Ti) precipitated laths produced in situ by an aging heat treatment, which was shown to confer a toughening effect (Knowles et al.) [1]. Here, details are given on a focused ion beam (FIB) slice and view experiment performed on the composite so as to determine that the 3D morphology of the bcc (Mo, Ti) precipitates were laths rather than needles. Scanning transmission electron microscopy (S(TEM)) micrographs of the microstructure as well as energy dispersive X-ray spectroscopy (EDX) maps are presented that identify the elemental partitioning between the C14 Laves matrix and the bcc laths, with Mo rejected from the matrix into laths. A TEM selected area diffraction pattern (SADP) and key is provided that was used to validate the orientation relation between the matrix and laths identified in (Knowles et al.) [1] along with details of the transformation matrix determined.

Data on a Laves phase intermetallic matrix composite in situ toughened by ductile precipitates

Directory of Open Access Journals (Sweden)

Alexander J. Knowles

2017-10-01

Full Text Available The data presented in this article are related to the research article entitled “Laves phase intermetallic matrix composite in situ toughened by ductile precipitates” (Knowles et al. [1]. The composite comprised a Fe2(Mo, Ti matrix with bcc (Mo, Ti precipitated laths produced in situ by an aging heat treatment, which was shown to confer a toughening effect (Knowles et al. [1]. Here, details are given on a focused ion beam (FIB slice and view experiment performed on the composite so as to determine that the 3D morphology of the bcc (Mo, Ti precipitates were laths rather than needles. Scanning transmission electron microscopy (S(TEM micrographs of the microstructure as well as energy dispersive X-ray spectroscopy (EDX maps are presented that identify the elemental partitioning between the C14 Laves matrix and the bcc laths, with Mo rejected from the matrix into laths. A TEM selected area diffraction pattern (SADP and key is provided that was used to validate the orientation relation between the matrix and laths identified in (Knowles et al. [1] along with details of the transformation matrix determined.

Development of SiC Nanoparticles and Second Phases Synergistically Reinforced Mg-Based Composites Processed by Multi-Pass Forging with Varying Temperatures

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Kaibo Nie

2018-01-01

Full Text Available In this study, SiC nanoparticles were added into matrix alloy through a combination of semisolid stirring and ultrasonic vibration while dynamic precipitation of second phases was obtained through multi-pass forging with varying temperatures. During single-pass forging of the present composite, as the deformation temperature increased, the extent of recrystallization increased, and grains were refined due to the inhibition effect of the increasing amount of dispersed SiC nanoparticles. A small amount of twins within the SiC nanoparticle dense zone could be found while the precipitated phases of Mg17Al12 in long strips and deformation bands with high density dislocations were formed in the particle sparse zone after single-pass forging at 350 °C. This indicated that the particle sparse zone was mainly deformed by dislocation slip while the nanoparticle dense zone may have been deformed by twinning. The yield strength and ultimate tensile strength of the composites were gradually enhanced through increasing the single-pass forging temperature from 300 °C to 400 °C, which demonstrated that initial high forging temperature contributed to the improvement of the mechanical properties. During multi-pass forging with varying temperatures, the grain size of the composite was gradually decreased while the grain size distribution tended to be uniform with reducing the deformation temperature and extending the forging passes. In addition, the amount of precipitated second phases was significantly increased compared with that after multi-pass forging under a constant temperature. The improvement in the yield strength of the developed composite was related to grain refinement strengthening and Orowan strengthening resulting from synergistical effect of the externally applied SiC nanoparticles and internally precipitated second phases.

Method for Forming Fiber Reinforced Composite Bodies with Graded Composition and Stress Zones

Science.gov (United States)

Singh, Mrityunjay (Inventor); Levine, Stanley R. (Inventor); Smialek, James A. (Inventor)

1999-01-01

A near-net, complex shaped ceramic fiber reinforced silicon carbide based composite bodies with graded compositions and stress zones is disclosed. To provide the composite a fiber preform is first fabricated and an interphase is applied by chemical vapor infiltration, sol-gel or polymer processes. This first body is further infiltrated with a polymer mixture containing carbon, and/or silicon carbide, and additional oxide, carbide, or nitride phases forming a second body. One side of the second body is spray coated or infiltrated with slurries containing high thermal expansion and oxidation resistant. crack sealant phases and the other side of this second body is coated with low expansion phase materials to form a third body. This third body consisting of porous carbonaceous matrix surrounding the previously applied interphase materials, is then infiltrated with molten silicon or molten silicon-refractory metal alloys to form a fourth body. The resulting fourth body comprises dense composites consisting of fibers with the desired interphase which are surrounded by silicon carbide and other second phases materials at the outer and inner surfaces comprising material of silicon, germanium, refractory metal suicides, borides, carbides, oxides, and combinations thereof The resulting composite fourth body has different compositional patterns from one side to the other.

Final Report For The Initial Solid Phase Characterization Of The 2011 Grab Samples And Composite For The C-109 Hard Heel Study

International Nuclear Information System (INIS)

Page, J.S.; Cooke, G.A.; Pestovich, J.A.

2011-01-01

On May 3, 2011, solid phase characterization subsamples were taken from six of the eight grab samples that had been collected from tank 241-C-109 in April, 2011 and delivered to the 222-S Laboratory. These subsamples were characterized in order to guide the creation of the composite for the C-109 hard heel study. Visual observation showed that there was a large variability in the physical characteristics of the eight individual grab samples. Several of the grab samples consisted of 'stone-like' cobbles (several > 25 mm in diameter) while the other grab samples were of a finer granular composition referred to as 'bulk material'. Half of the six subsamples taken for this initial SPC were of crushed cobbles and half were of the bulk material. Scanning electron microscopy was performed on all six subsamples, and X-ray diffraction was performed on all three of the 'bulk material' samples and one of the crushed cobble samples. The crushed cobbles were found to be composed primarily of gibbsite (Al(OHh) 3 ). Analysis by X-ray diffraction indicated gibbsite to be the only crystalline phase detected, and scanning electron microscopy showed the crushed cobbles to consist primarily of aggregates of euhedral to subhedral gibbsite crystals that were 20 to 100 μm in size. The aggregates, having a moderate amount of pore space, were cemented primarily by recrystallized gibbsite making them resistant to crushing. The bulk material consisted of coarse to fine-grained pebble-sized (2 to 20 mm) particles. The X-ray diffraction analysis showed them to be a mixture of natrophosphate (Na 7 (PO 4 ) 2 F·19(H 2 O)) and gibbsite crystals in varying amounts in each of the three subsamples (i.e., some grab samples were primarily natrophosphate while others were mixed with gibbsite). The scanning electron microscopy analysis of the bulk material showed the crystals to be euhedral to anhedral (rounded) in shape. Trace phases, too minor to be detected by XRD, were observed in the SEM analysis

Numerical simulation of phase change material composite wallboard in a multi-layered building envelope

International Nuclear Information System (INIS)

Zwanzig, Stephen D.; Lian, Yongsheng; Brehob, Ellen G.

2013-01-01

Highlights: ► A numerical method to study the heat transfer through a PCM composite wallboard is presented. ► PCM wallboard can reduce energy consumption and shift peak electricity load. ► There is an optimal location for the PCM wallboard in the building envelop. ► The PCM wallboard performance depends on weather conditions. - Abstract: Phase change materials (PCMs) have the capability to store/release massive latent heat when undergoing phase change. When impregnated or encapsulated into wallboard or concrete systems, PCMs can greatly enhance their thermal energy storage capacity and effective thermal mass. When used in the building envelope PCM wallboard has the potential to improve building operation by reducing the energy requirement for maintaining thermal comfort, downsizing the AC/heating equipment, and shifting the peak load from the electrical grid. In this work we numerically studied the potential of PCM on energy saving for residential homes. For that purpose we solved the one-dimensional, transient heat equation through the multi-layered building envelope using the Crank–Nicolson discretization scheme. A source term is incorporated to account for the thermal-physical properties of the composite PCM wallboard. Using this code we examined a PCM composite wallboard incorporated into the walls and roof of a typical residential building across various climate zones. The PCM performance was studied under all seasonal conditions using the latest typical meteorological year (TMY3) data for exterior boundary conditions. Our simulations show that PCM performance highly depends on the weather conditions, emphasizing the necessity to choose different PCMs at different climate zones. Comparisons were also made between different PCM wallboard locations. Our work shows that there exists an optimal location for PCM placement within building envelope dependent upon the resistance values between the PCM layer and the exterior boundary conditions. We further

Superhydrophobic ceramic coatings enabled by phase-separated nanostructured composite TiO2–Cu2O thin films

International Nuclear Information System (INIS)

Aytug, Tolga; Paranthaman, Parans M; Simpson, John T; Christen, David K; Bogorin, Daniela F; Mathis, John E

2014-01-01

By exploiting phase-separation in oxide materials, we present a simple and potentially low-cost approach to create exceptional superhydrophobicity in thin-film based coatings. By selecting the TiO 2 –Cu 2 O system and depositing through magnetron sputtering onto single crystal and metal templates, we demonstrate growth of nanostructured, chemically phase-segregated composite films. These coatings, after appropriate chemical surface modification, demonstrate a robust, non-wetting Cassie–Baxter state and yield an exceptional superhydrophobic performance, with water droplet contact angles reaching to ∼172° and sliding angles <1°. As an added benefit, despite the photo-active nature of TiO 2 , the chemically coated composite film surfaces display UV stability and retain superhydrophobic attributes even after exposure to UV (275 nm) radiation for an extended period of time. The present approach could benefit a variety of outdoor applications of superhydrophobic coatings, especially for those where exposure to extreme atmospheric conditions is required. (papers)

Preparation, Mechanical and Thermal Properties of Cement Board with Expanded Perlite Based Composite Phase Change Material for Improving Buildings Thermal Behavior

Directory of Open Access Journals (Sweden)

Rongda Ye

2015-11-01

Full Text Available Here we demonstrate the mechanical properties, thermal conductivity, and thermal energy storage performance of construction elements made of cement and form-stable PCM-Rubitherm® RT 28 HC (RT28/expanded perlite (EP composite phase change materials (PCMs. The composite PCMs were prepared by adsorbing RT28 into the pores of EP, in which the mass fraction of RT28 should be limited to be no more than 40 wt %. The adsorbed RT28 is observed to be uniformly confined into the pores of EP. The phase change temperatures of the RT28/EP composite PCMs are very close to that of the pure RT28. The apparent density and compression strength of the composite cubes increase linearly with the mass fraction of RT28. Compared with the thermal conductivity of the boards composed of cement and EP, the thermal conductivities of the composite boards containing RT28 increase by 15%–35% with the mass fraction increasing of RT28. The cubic test rooms that consist of six boards were built to evaluate the thermal energy storage performance, it is found that the maximum temperature different between the outside surface of the top board with the indoor temperature using the composite boards is 13.3 °C higher than that of the boards containing no RT28. The thermal mass increase of the built environment due to the application of composite boards can contribute to improving the indoor thermal comfort and reducing the energy consumption in the buildings.

Preparation, Mechanical and Thermal Properties of Cement Board with Expanded Perlite Based Composite Phase Change Material for Improving Buildings Thermal Behavior.

Science.gov (United States)

Ye, Rongda; Fang, Xiaoming; Zhang, Zhengguo; Gao, Xuenong

2015-11-13

Here we demonstrate the mechanical properties, thermal conductivity, and thermal energy storage performance of construction elements made of cement and form-stable PCM-Rubitherm® RT 28 HC (RT28)/expanded perlite (EP) composite phase change materials (PCMs). The composite PCMs were prepared by adsorbing RT28 into the pores of EP, in which the mass fraction of RT28 should be limited to be no more than 40 wt %. The adsorbed RT28 is observed to be uniformly confined into the pores of EP. The phase change temperatures of the RT28/EP composite PCMs are very close to that of the pure RT28. The apparent density and compression strength of the composite cubes increase linearly with the mass fraction of RT28. Compared with the thermal conductivity of the boards composed of cement and EP, the thermal conductivities of the composite boards containing RT28 increase by 15%-35% with the mass fraction increasing of RT28. The cubic test rooms that consist of six boards were built to evaluate the thermal energy storage performance, it is found that the maximum temperature different between the outside surface of the top board with the indoor temperature using the composite boards is 13.3 °C higher than that of the boards containing no RT28. The thermal mass increase of the built environment due to the application of composite boards can contribute to improving the indoor thermal comfort and reducing the energy consumption in the buildings.

Phased Array Imaging of Complex-Geometry Composite Components.

Science.gov (United States)

Brath, Alex J; Simonetti, Francesco

2017-10-01

Progress in computational fluid dynamics and the availability of new composite materials are driving major advances in the design of aerospace engine components which now have highly complex geometries optimized to maximize system performance. However, shape complexity poses significant challenges to traditional nondestructive evaluation methods whose sensitivity and selectivity rapidly decrease as surface curvature increases. In addition, new aerospace materials typically exhibit an intricate microstructure that further complicates the inspection. In this context, an attractive solution is offered by combining ultrasonic phased array (PA) technology with immersion testing. Here, the water column formed between the complex surface of the component and the flat face of a linear or matrix array probe ensures ideal acoustic coupling between the array and the component as the probe is continuously scanned to form a volumetric rendering of the part. While the immersion configuration is desirable for practical testing, the interpretation of the measured ultrasonic signals for image formation is complicated by reflection and refraction effects that occur at the water-component interface. To account for refraction, the geometry of the interface must first be reconstructed from the reflected signals and subsequently used to compute suitable delay laws to focus inside the component. These calculations are based on ray theory and can be computationally intensive. Moreover, strong reflections from the interface can lead to a thick dead zone beneath the surface of the component which limits sensitivity to shallow subsurface defects. This paper presents a general approach that combines advanced computing for rapid ray tracing in anisotropic media with a 256-channel parallel array architecture. The full-volume inspection of complex-shape components is enabled through the combination of both reflected and transmitted signals through the part using a pair of arrays held in a yoke

Silver Matrix Composites - Structure and Properties

Directory of Open Access Journals (Sweden)

Wieczorek J.

2016-03-01

Full Text Available Phase compositions of composite materials determine their performance as well as physical and mechanical properties. Depending on the type of applied matrix and the kind, amount and morphology of the matrix reinforcement, it is possible to shape the material properties so that they meet specific operational requirements. In the paper, results of investigations on silver alloy matrix composites reinforced with ceramic particles are presented. The investigations enabled evaluation of hardness, tribological and mechanical properties as well as the structure of produced materials. The matrix of composite material was an alloy of silver and aluminium, magnesium and silicon. As the reinforcing phase, 20-60 μm ceramic particles (SiC, SiO2, Al2O3 and Cs were applied. The volume fraction of the reinforcing phase in the composites was 10%. The composites were produced using the liquid phase (casting technology, followed by plastic work (the KOBO method. The mechanical and tribological properties were analysed for plastic work-subjected composites. The mechanical properties were assessed based on a static tensile and hardness tests. The tribological properties were investigated under dry sliding conditions. The analysis of results led to determination of effects of the composite production technology on their performance. Moreover, a relationship between the type of reinforcing phase and the mechanical and tribological properties was established.

Uncontrolled re-entry of satellite parts after finishing their mission in LEO: Titanium alloy degradation by thermite reaction energy

Science.gov (United States)

Monogarov, K. A.; Pivkina, A. N.; Grishin, L. I.; Frolov, Yu. V.; Dilhan, D.

2017-06-01

Analytical and experimental studies conducted at Semenov Institute of Chemical Physics for investigating the use of pyrotechnic compositions, i.e., thermites, to reduce the risk of the fall of thermally stable parts of deorbiting end-of-life LEO satellites on the Earth are described. The main idea was the use of passive heating during uncontrolled re-entry to ignite thermite composition, fixed on the titanium surface, with the subsequent combustion energy release to be sufficient to perforate the titanium cover. It is supposed, that thus destructed satellite parts will lose their streamline shape, and will burn out being aerodynamically heated during further descending in atmosphere (patent FR2975080). On the base of thermodynamic calculations the most promising thermite compositions have been selected for the experimental phase. The unique test facilities have been developed for the testing of the efficiency of thermite charges to perforate the titanium TA6V cover of 0.8 mm thickness under temperature/pressure conditions duplicated the uncontrolled re-entry of titanium tank after its mission on LEO. Experiments with the programmed laser heating inside the vacuum chamber revealed the only efficient thermite composition among preliminary selected ones to be Al/Co3O4. Experimental searching of the optimal aluminum powder between spherical and flaked nano- and micron-sized ones revealed the possibility to adjust the necessary ignition delay time, according to the titanium cover temperature dependency on deorbiting time. For the titanium tank the maximum temperature is 1100 °C at altitude 68 km and pressure 60 Pa. Under these conditions Al/Co3O4 formulations with nano-Al spherical particles provide the ignition time to be 13.3 s, and ignition temperature as low as 592±5 °C, whereas compositions with the micron-sized spherical Al powder reveal these values to be much higher, i.e., 26.3 s and 869±5 °C, respectively. The analytical and experimental studies described

Structural properties and stability of the bcc and omega phases in the Zr-Nb system. Pt. II. Composition dependence of the lattice parameters

International Nuclear Information System (INIS)

Grad, G.B.; Guillermet, A.F.; Pieres, J.J.; Cuello, G.J.; Consejo Nacional de Investigaciones Cientificas y Tecnicas, Buenos Aires; Universidad Nacional del Comahue

1996-01-01

For pt.I see Guillermet, A.F., J. Nucl. Mater., vol.218, p.236-46, 1995. This paper deals with the composition dependence of the lattice parameters of the bcc and omega phases of the Zr-Nb system. The experimental part of the work comprises neutron scattering experiments on a Zr-10 at.% Nb alloy in the as-quenched state and after successive aging treatments at 773 K. This new information is combined with an extensive review of the available data, and a detailed analysis is performed of the effects of composition and heat-treatment upon the lattice parameters a Ω and c Ω of the omega phase and the lattice-parameter relations between bcc and omega. A striking behaviour is detected in the variation of a Ω with composition in low-Nb alloys. (orig.)

Bias voltage effect on electron tunneling across a junction with a ferroelectric–ferromagnetic two-phase composite barrier

International Nuclear Information System (INIS)

Wang Jian; Ju Sheng; Li, Z.Y.

2012-01-01

The effect of bias voltage on electron tunneling across a junction with a ferroelectric–ferromagnetic composite barrier is investigated theoretically. Because of the inversion symmetry breaking of the spontaneous ferroelectric polarization, bias voltage dependence of the electron tunneling shows significant differences between the positive bias and the negative one. The differences of spin filtering or tunnel magnetoresistance increase with the increasing absolute value of bias voltage. Such direction preferred electron tunneling is found intimately related with the unusual asymmetry of the electrical potential profile in two-phase composite barrier and provides a unique change to realize rectifying functions in spintronics. - Highlights: ► Electron tunneling across a ferroelectric–ferromagnetic composite barrier junction. ► TMR effect is different under the same value but opposite direction bias voltage. ► This directionality of the electron tunneling enhances with increasing bias voltage.

Design of Low-Melting Point Compositions Suitable for Transient Liquid Phase Sintering of PM Steels Based on a Thermodynamic and Kinetic Study

Science.gov (United States)

Bernardo, Elena; de Oro, Raquel; Campos, Mónica; Torralba, José Manuel

2014-04-01

The possibility of tailoring the characteristics of a liquid metal is an important asset in a wide number of processing techniques. For most of these processes, the nature and degree of the interaction between liquid and solid phases are usually a focus of interest since they determine liquid properties such as wettability and infiltration capacity. Particularly, within the powder metallurgy (PM) technology, it is considered one of the key aspects to obtain high performance steels through liquid phase sintering. In this work, it is proved how thermodynamic and kinetics software is a powerful tool to study the liquid/solid interactions. The assessment of different liquid phase promoters for transient liquid phase sintering is addressed through the use of ThermoCalc and DICTRA calculations. Besides melting temperatures, particular attention is given to the solubility phenomena between the phases and the kinetics of these processes. Experimental validation of thermodynamic results is carried out by wetting and infiltration experiments at high temperatures. Compositions presenting different liquid/solid solubility are evaluated and directly correlated to the behavior of the liquid during a real sintering process. Therefore, this work opens the possibility to optimize liquid phase compositions and predict the liquid behavior from the design step, which is considered of high technological value for the PM industry.

Retention of nucleic acids in ion-pair reversed-phase high-performance liquid chromatography depends not only on base composition but also on base sequence.

Science.gov (United States)

Qiao, Jun-Qin; Liang, Chao; Wei, Lan-Chun; Cao, Zhao-Ming; Lian, Hong-Zhen

2016-12-01

The study on nucleic acid retention in ion-pair reversed-phase high-performance liquid chromatography mainly focuses on size-dependence, however, other factors influencing retention behaviors have not been comprehensively clarified up to date. In this present work, the retention behaviors of oligonucleotides and double-stranded DNAs were investigated on silica-based C 18 stationary phase by ion-pair reversed-phase high-performance liquid chromatography. It is found that the retention of oligonucleotides was influenced by base composition and base sequence as well as size, and oligonucleotides prone to self-dimerization have weaker retention than those not prone to self-dimerization but with the same base composition. However, homo-oligonucleotides are suitable for the size-dependent separation as a special case of oligonucleotides. For double-stranded DNAs, the retention is also influenced by base composition and base sequence, as well as size. This may be attributed to the interaction of exposed bases in major or minor grooves with the hydrophobic alky chains of stationary phase. In addition, no specific influence of guanine and cytosine content was confirmed on retention of double-stranded DNAs. Notably, the space effect resulted from the stereostructure of nucleic acids also influences the retention behavior in ion-pair reversed-phase high-performance liquid chromatography. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Nanocarbon materials obtained of coniferous trees in the composition of black powder

Directory of Open Access Journals (Sweden)

Zulkhair Mansurov

2012-03-01

Full Text Available Obtained black powders from coniferous wood. The carbon content of up to 90% can be used in warfare, pyrotechnics and industries. In the Republic of Kazakhstan does not produce gunpowder. In the energy-intensive materials laboratory, developed industrial black powders (ordinary, composed of components produced in the republic of Kazakhstan. Sulfur, activated carbon, based on apricot seeds and rice husks, softwood sawdust, which have lower costs than their foreign counterparts.

Electric field-induced phase transitions and composition-driven nanodomains in rhombohedral-tetragonal potassium-sodium niobate-based ceramics

KAUST Repository

Lv, Xiang

2017-08-07

The mechanisms behind the high piezoelectricity of (K,Na)NbO3-based lead-free ceramics were investigated, including electric field-induced phase transitions and composition-driven nanodomains. The construction of a rhombohedral-tetragonal (R-T) phase boundary, confirmed using several advanced techniques, allowed a large piezoelectric constant (d33) of 450 ± 5 pC/N to be obtained in (1-x)K0.4Na0.6Nb0.945Sb0.055O3-xBi0.5Na0.5(Hf1-ySny)O3 (0 ≤ x ≤ 0.06 and 0 ≤ y ≤ 0.5) ceramics possessing an ultralow ΔUT-R of 7.4 meV. More importantly, the existence of an intermediate phase, i.e., the electric-induced phase (EIP), bridging the rhombohedral R [Ps//(111)] and tetragonal T [Ps//(001)] phases during the polarization rotation was demonstrated. Striped nanodomains (∼40 nm) that easily responded to external stimulation were also observed in the ceramics with an R-T phase. Thus, the enhanced piezoelectric properties originated from EIP and the striped nanodomains.

GASCON and MHDGAS: FORTRAN IV computer codes for calculating gas and condensed-phase compositions in the coal-fired open-cycle MHD system

Energy Technology Data Exchange (ETDEWEB)

Blackburn, P E

1977-12-01

Fortran IV computer codes have been written to calculate the equilibrium partial pressures of the gaseous phase and the quantity and composition of the condensed phases in the open-cycle MHD system. The codes are based on temperature-dependent equilibrium constants, mass conservation, the mass action law, and assumed ideal solution of compounds in each of two condensed phases. It is assumed that the phases are an oxide-silicate phase and a sulfate-carbonate-hydroxide phase. Calculations are iterated for gas and condensate concentrations while increasing or decreasing the total moles of elements, but keeping mole ratios constant, to achieve the desired total pressure. During iteration the oxygen partial pressure is incrementally changed. The decision to increase or decrease the oxygen pressure in this process depends on comparison of the oxygen content calculated in the gas and condensate phases with the initial amount of oxygen in the ash, coal, seed, and air. This process, together with a normalization step, allows the elements to converge to their initial quantities. Two versions of the computer code have been written. GASCON calculates the equilibrium gas partial pressures and the quantity and composition of the condensed phases in steps of thirteen temperature and pressure combinations in which the condensate is removed after each step, simulating continuous slag removal from the MHD system. MHDGAS retains the condensate for each step, simulating flow of condensate (and gas) through the MHD system.

Rhodium and Hafnium Influence on the Microstructure, Phase Composition, and Oxidation Resistance of Aluminide Coatings

OpenAIRE

Maryana Zagula-Yavorska; Małgorzata Wierzbińska; Jan Sieniawski

2017-01-01

A 0.5 μm thick layer of rhodium was deposited on the CMSX 4 superalloy by the electroplating method. The rhodium-coated superalloy was hafnized and aluminized or only aluminized using the Chemical vapour deposition method. A comparison was made of the microstructure, phase composition, and oxidation resistance of three aluminide coatings: nonmodified (a), rhodium-modified (b), and rhodium- and hafnium-modified (c). All three coatings consisted of two layers: the additive layer and the interdi...

Effect of composition and heat treatment on the phase formation of mechanically alloyed Cr-B and Mo-B powders

International Nuclear Information System (INIS)

Wu, H M; Hu, C J; Pai, K Y

2009-01-01

Blended elemental Cr-B and Mo-B powders in atomic ratio of 67:33, 50:50, and 20:80 were subjected to mechanical alloying up to 60 h and subsequent heat treatment to investigate effect of composition and heat treatment on the phase formation of Cr-B and Mo-B powders. It was studied by X-ray diffraction and differential thermal analysis. Mechanical alloying these powder mixtures for 60 h leads essentially to a amorphous structure except for the Mo 20 B 80 powder, which creates a partially amorphous MoB 4 structure. Annealing at lower temperatures relieves the strains cumulative in the milled powders and creates no new phase. The structures obtained after annealing the milled powders at higher temperature vary and depend on the overall composition of the powder mixtures. Annealing the milled Mo-B powders having greater Mo content ends up with a dissociation reaction at higher temperature.

Phase Composition of a CrMo0.5NbTa0.5TiZr High Entropy Alloy: Comparison of Experimental and Simulated Data

OpenAIRE

Fan Zhang; Oleg N. Senkov; Jonathan D. Miller

2013-01-01

Microstructure and phase composition of a CrMo0.5NbTa0.5TiZr high entropy alloy were studied in the as-solidified and heat treated conditions. In the as-solidified condition, the alloy consisted of two disordered BCC phases and an ordered cubic Laves phase. The BCC1 phase solidified in the form of dendrites enriched with Mo, Ta and Nb, and its volume fraction was 42%. The BCC2 and Laves phases solidified by the eutectic-type reaction, and their volume fractions were 27% and 31%, respectively....

Body composition and phase angle in Russian children in remission from acute lymphoblastic leukemia

Science.gov (United States)

Tseytlin, G. Ja; Khomyakova, I. A.; Nikolaev, D. V.; Konovalova, M. V.; Vashura, A. Yu; Tretyak, A. V.; Godina, E. Z.; Rudnev, S. G.

2010-04-01

Elevated degree of body fatness and changes in other body composition parameters are known to be common effects of treatment for acute lymphoblastic leukemia (ALL) in children. In order to study peculiarities of somatic growth and development in ALL survivors, we describe the results of BIA body composition analysis of 112 boys and 108 girls aged 5-18 years in remission from ALL (remission time range 1-13 years) compared to data from the same number of age- and sex-matched healthy controls (n=220). Detrimental effect on height in ALL boys was observed, whereas girls experienced additional weight gain compared to healthy subjects. In ALL patients, resistance, body fat, and percent body fat were significantly increased. The reactance, phase angle, absolute and relative values of skeletal muscle and body cell mass were significantly decreased. Principal component analysis revealed an early prevalence of adiposity traits in the somatic growth and development of ALL girls compared to healthy controls.

Evolution of the structure and the phase composition of a bainitic structural steel during plastic deformation

Science.gov (United States)

Nikitina, E. N.; Glezer, A. M.; Ivanov, Yu. F.; Aksenova, K. V.; Gromov, V. E.; Kazimirov, S. A.

2017-10-01

The evolution of the phase composition and the imperfect substructure of the 30Kh2N2MFA bainitic structural steel subjected to compressive deformation by 36% is quantitatively analyzed. It is shown that deformation is accompanied by an increase in the scalar dislocation density, a decrease in the longitudinal fragment sizes, an increase in the number of stress concentrators, the dissolution of cementite particles, and the transformation of retained austenite.

Infrared transient-liquid-phase joining of SCS-6/{beta}21S titanium matrix composite

Energy Technology Data Exchange (ETDEWEB)

Blue, C.A.; Sikka, V.K. [Oak Ridge National Lab., TN (United States). Materials Processing Group; Blue, R.A.; Lin, R.Y. [Univ. of Cincinnati, OH (United States). Dept. of Materials Science and Engineering

1996-02-01

Fiber-reinforced titanium matrix composites (TMCs) are among the advanced materials being considered for use in the aerospace industry due to their light weight, high strength, and high modulus. A rapid infrared joining process has been developed for the joining of composites and advanced materials. Rapid infrared joining has been shown not to have many of the problems associated with conventional joining methods. Two models were utilized to predict the joint evolution and fiber reaction zone growth. TMC, 16-ply SCS-6/{beta}21S, has been successfully joined with total processing times of under 2 min utilizing the rapid infrared joining technique. The process utilizes a 50 C/sec ramping rate, 17-{micro}m Ti-15Cu-15Ni wt % filler material between the faying surfaces; a joining temperature of 1,100 C; and 120 sec of time to join the composite material. Joint shear strength testing of the rapid infrared joints at temperatures as high as 800 C has revealed no joint failures. Also, due to the rapid cooling of the process, no poststabilization of the matrix material is necessary to prevent the formation of a brittle omega phase during subsequent use of the TMC at intermediate temperatures, 270 to 430 C, for up to 20 h.

Fast Cure Repair Kit for Composites, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — NASA has a need for technologies that will enable them to repair damage to composite structures. Fiber-reinforced polymer composite materials are fast gaining ground...

Self-Deploying, Composite Habitats, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — Cornerstone Research Group, Inc. (CRG), proposes to develop self-deploying, composite structures for lunar habitats, based on CRG's VeritexTM materials. These...

Structural models of increasing complexity for icosahedral boron carbide with compositions throughout the single-phase region from first principles

Science.gov (United States)

Ektarawong, A.; Simak, S. I.; Alling, B.

2018-05-01

We perform first-principles calculations to investigate the phase stability of boron carbide, concentrating on the recently proposed alternative structural models composed not only of the regularly studied B11Cp (CBC) and B12(CBC), but also of B12(CBCB) and B12( B4 ). We find that a combination of the four structural motifs can result in low-energy electron precise configurations of boron carbide. Among several considered configurations within the composition range of B10.5C and B4C , we identify in addition to the regularly studied B11Cp (CBC) at the composition of B4C two low-energy configurations, resulting in a new view of the B-C convex hull. Those are [B12 (CBC)]0.67[B12(B4)] 0.33 and [B12 (CBC)]0.67[ B12 (CBCB)]0.33, corresponding to compositions of B10.5C and B6.67C , respectively. As a consequence, B12(CBC) at the composition of B6.5C , previously suggested in the literature as a stable configuration of boron carbide, is no longer part of the B -C convex hull. By inspecting the electronic density of states as well as the elastic moduli, we find that the alternative models of boron carbide can provide a reasonably good description for electronic and elastic properties of the material in comparison with the experiments, highlighting the importance of considering B12(CBCB) and B12( B4 ), together with the previously proposed B11Cp (CBC) and B12(CBC), as the crucial ingredients for modeling boron carbide with compositions throughout the single-phase region.

Magnetoelectricity in composites

CERN Document Server

Bichurin, Mirza

2011-01-01

Magnetoelectric composites, which simultaneously exhibit ferroelectricity and ferromagnetism, have recently stimulated a sharply increasing number of research activities for their scientific interest and significant technological promise in the novel multifunctional devices. Natural single-phase compounds are rare, and their magnetoelectric responses are either relatively weak or occurs at temperatures too low for practical applications. In contrast, composites, which incorporate both ferroelectric and ferri-/ferromagnetic phases, typically yield giant magnetoelectric coupling response above r

Effect of phase composition on the corrosion properties of alloys of the magnesium-yttrium system in neutral solutions

International Nuclear Information System (INIS)

Krasnoyarskii, V.V.; Petrova, L.M.; Dobatkina, T.V.; Korol'kova, I.G.

1992-01-01

A study is made of the effect of phase composition on the corrosive dissolution of binary alloys of the system magnesium-8.2% yttrium. It is shown that the appearance of the intermetallide Mg 24 Y 5 - being the effective cathode - intensifies self-dissolution of the alloy under conditions of anodic galvanostatic polarization

A novel CO>2- and SO>2-tolerant dual phase composite membrane for oxygen separation

DEFF Research Database (Denmark)

Cheng, Shiyang; Søgaard, Martin; Han, Li

2015-01-01

A novel dual phase composite oxygen membrane (Al0.02Ga0.02Zn0.96O1.02 – Gd0.1Ce0.9O1.95-δ) was successfully prepared and tested. The membrane shows chemical stability against CO2 and SO2, and a stable oxygen permeation over 300 hours in CO2 was demonstrated. ZnO is cheap and non-toxic...... and is therefore highly advantageous compared to other common materials used for the purpose....

Study of the phase composition of nanostructures produced by the local anodic oxidation of titanium films

International Nuclear Information System (INIS)

Avilov, V. I.; Ageev, O. A.; Konoplev, B. G.; Smirnov, V. A.; Solodovnik, M. S.; Tsukanova, O. G.

2016-01-01

The results of experimental studies of the phase composition of oxide nanostructures formed by the local anodic oxidation of a titanium thin film are reported. The data of the phase analysis of titanium-oxide nanostructures are obtained by X-ray photoelectron spectroscopy in the ion profiling mode of measurements. It is established that the surface of titanium-oxide nanostructures 4.5 ± 0.2 nm in height possesses a binding energy of core levels characteristic of TiO_2 (458.4 eV). By analyzing the titanium-oxide nanostructures in depth by X-ray photoelectron spectroscopy, the formation of phases with binding energies of core levels characteristic of Ti_2O_3 (456.6 eV) and TiO (454.8 eV) is established. The results can be used in developing the technological processes of the formation of a future electronic-component base for nanoelectronics on the basis of titanium-oxide nanostructures and probe nanotechnologies.

Friction and wear characteristics of Al-Cu/C composites synthesized using partial liquid phase casting process

International Nuclear Information System (INIS)

Ng, W.B.; Gupta, M.; Lim, S.C.

1997-01-01

During the sliding of aluminium alloys dispersed with graphite particulates, a layer of graphite is usually present at the sliding interface. This tribo-layer significantly reduces the amount of direct metal-to-metal contact, giving rise to low friction and a low rate of wear, making these composites useful candidate materials for anti-friction applications. Such self-lubricating composites are commonly fabricated via the squeeze casting, slurry casting or powder metallurgy route. These processes are expensive while the less-expensive conventional casting route is limited by the agglomeration of graphite particles in the composites, giving rise to poor mechanical properties. In this work, graphite particulate-reinforced Al-4.5 wt.% Cu composites with two effective graphite contents (Al-4.5 Cu/4.2 wt.% C and Al-4.5 Cu/6.8 wt.% C) were synthesized through an innovative partial liquid phase casting (rheocasting) technique, which is a modification of the conventional casting process. Unlubricated (without the use of conventional liquid lubrication) friction and wear performance of these composites as well as the un-reinforced aluminium alloy was determined using a pin-on-disk tester. The results revealed that the graphite-reinforced composites have a higher wear rate than the un-reinforced matrix alloy while their frictional characteristics are very similar within the range of testing conditions. Combining these with the information gathered from worn-surface examinations and wear-debris analysis, it is suggested that there exists a certain threshold for the amount and size of graphite particulates in these composites to enable them to have improved tribological properties. (Copyright (c) 1997 Elsevier Science B.V., Amsterdam. All rights reserved.)

Stability analysis of whirling composite shells partially filled with two liquid phases

Energy Technology Data Exchange (ETDEWEB)

Sahebnasagh, Mohammad [Department of Mechanical Engineering, University of Tehran, Tehran (Iran, Islamic Republic of); Nikkhah-Bahrami, Mansour; Firouz-Abadi, Roohollah [Department of Aerospace Engineering, Sharif University, Tehran (Iran, Islamic Republic of)

2017-05-15

In this paper, the stability of whirling composite cylindrical shells partially filled with two liquid phases is studied. Using the first-order shear shell theory, the structural dynamics of the shell is modeled and based on the Navier-Stokes equations for ideal liquid, a 2D model is developed for liquid motion at each section of the cylinder. In steady state condition, liquids are supposed to locate according to mass density. In this study, the thick shells are investigated. Using boundary conditions between liquids, the model of coupled fluid-structure system is obtained. This coupled fluid-structure model is employed to determine the critical speed of the system. The effects of the main variables on the stability of the shell are studied and the results are investigated.

Investigation into isomolar series of Al(NO3)3, Na3VO4 solution mixture and composition of solid phases

International Nuclear Information System (INIS)

Chernysh, L.F.; Nakhodnova, A.P.; Makarova, R.A.

1979-01-01

Conducted is investigation of properties of isomolar series of aluminium nitrate and sodiUm vanadate solutions at pH of the latter 12.5; 10.0; 7.0 and the temperature of 25 deg C using the methods of pH-metry, conductometry, ''seeming'' volume of precipitations, residual concentration of aluminium and vanadium. It is shown, that the composition property diagram of the system investigated does not reflect the true composition of solid-phase products of the reaction, which depends on the component ratio in solution. Bottom phases of isomolar series are mainly heterogeneous. At the excess of sodium vanadate solution and its high pH values conditions for the basic salt formation are created. At pH of the Na 3 VO 4 solution of 12.5 and 10.0 and Al(NO 3 ) 3 : Na 3 VO 4 ratios 4:6 and 3:7 respectively obtained are the basic aluminium vanadates of the (AlOH) 3 (VO 4 ) 2 x 7.5H 2 O and (AlOH) 2 V 2 O 7 x5H 2 O composition, some of their physicochemical properties being investigated

Solidifying incongruently melting intermetallic phases as bulk single phases using the example of Al{sub 2}Cu and Q-phase in the Al-Mg-Cu-Si system

Energy Technology Data Exchange (ETDEWEB)

Loeffler, Andrea [Institute of Materials Science and Technology, Friedrich-Schiller-University, Jena (Germany); Groebner, Joachim; Hampl, Milan [Institute of Metallurgy, Clausthal University of Technology, Clausthal-Zellerfeld (Germany); Engelhardt, Hannes [Institute of Materials Science and Technology, Friedrich-Schiller-University, Jena (Germany); Schmid-Fetzer, Rainer [Institute of Metallurgy, Clausthal University of Technology, Clausthal-Zellerfeld (Germany); Rettenmayr, Markus, E-mail: M.Rettenmayr@uni-jena.de [Institute of Materials Science and Technology, Friedrich-Schiller-University, Jena (Germany)

2012-02-25

Highlights: Black-Right-Pointing-Pointer Samples consisting of pure Al{sub 2}Cu and 95% Q-phase respectively were prepared. Black-Right-Pointing-Pointer The Q-phase composition is Al{sub 17}Cu{sub 9}Mg{sub 44}Si{sub 30}, its solubility range is negligible. Black-Right-Pointing-Pointer The Q-phase peritectic temperature was determined by DSC measurements as 703 Degree-Sign C. Black-Right-Pointing-Pointer A new thermodynamic dataset for the Q-phase has been assessed. - Abstract: Plane front directional solidification experiments were carried out for preparing incongruently melting intermetallic phases in the quaternary alloy system Al-Cu-Mg-Si, particularly the binary Al{sub 2}Cu phase and the quaternary phase ('Q-phase'). By this method, bulk samples that consist of only a single phase are generated. Sample sections consisting of 100% single phase Al{sub 2}Cu and of 95% Q-phase, respectively, were obtained. The composition of the Q-phase was measured by Energy Dispersive X-ray Spectroscopy (EDX). The measured concentrations are close to the Al{sub 3}Cu{sub 2}Mg{sub 9}Si{sub 7} composition that has recently been predicted as most stable by ab initio calculations. A peritectic temperature of 703 Degree-Sign C for the reaction Q {yields} L + Mg{sub 2}Si + (Si) was determined by differential scanning calorimetry (DSC). An optimization of the Calphad database was performed considering the measured composition and peritectic temperature. For validating the optimized database, Scheil calculations were performed and compared with the experimentally determined sequence of solidifying phases.

Gas Phase Sensing of Alcohols by Metal Organic Framework–Polymer Composite Materials

Science.gov (United States)

2017-01-01

Affinity layers play a crucial role in chemical sensors for the selective and sensitive detection of analytes. Here, we report the use of composite affinity layers containing Metal Organic Frameworks (MOFs) in a polymeric matrix for sensing purposes. Nanoparticles of NH2-MIL-53(Al) were dispersed in a Matrimid polymer matrix with different weight ratios (0–100 wt %) and drop-casted on planar capacitive transducer devices. These coated devices were electrically analyzed using impedance spectroscopy and investigated for their sensing properties toward the detection of a series of alcohols and water in the gas phase. The measurements indicated a reversible and reproducible response in all devices. Sensor devices containing 40 wt % NH2-MIL-53(Al) in Matrimid showed a maximum response for methanol and water. The sensor response time slowed down with increasing MOF concentration until 40 wt %. The half time of saturation response (τ0.5) increased by ∼1.75 times for the 40 wt % composition compared to devices coated with Matrimid only. This is attributed to polymer rigidification near the MOF/polymer interface. Higher MOF loadings (≥50 wt %) resulted in brittle coatings with a response similar to the 100 wt % MOF coating. Cross-sensitivity studies showed the ability to kinetically distinguish between the different alcohols with a faster response for methanol and water compared to ethanol and 2-propanol. The observed higher affinity of the pure Matrimid polymer toward methanol compared to water allows also for a higher uptake of methanol in the composite matrices. Also, as indicated by the sensing studies with a mixture of water and methanol, the methanol uptake is independent of the presence of water up to 6000 ppm of water. The NH2-MIL-53(Al) MOFs dispersed in the Matrimid matrix show a sensitive and reversible capacitive response, even in the presence of water. By tuning the precise compositions, the affinity kinetics and overall affinity can be tuned, showing

Hydrothermal transformation of titanate nanotubes into single-crystalline TiO2 nanomaterials with controlled phase composition and morphology

International Nuclear Information System (INIS)

Xu, Yuanmei; Fang, Xiaoming; Xiong, Jian; Zhang, Zhengguo

2010-01-01

Single-crystalline TiO 2 nanomaterials were synthesized by hydrothermally treating suspensions of H-titanate nanotubes and characterized by XRD, TEM, and HRTEM. The effects of the pH values of the suspensions and the hydrothermal temperatures on the phase composition and morphology of the obtained TiO 2 nanomaterials were systematically investigated. The H-titanate nanotubes were predominately transformed into anatase nanoparticle with rhombic shape when the pH value was greater than or equal to 1.0, whereas primarily turned into rutile nanorod with two pyramidal ends at the pH value less than or equal to 0.5. We propose a possible mechanism for hydrothermal transformation of H-titanate nanotubes into single-crystalline TiO 2 nanomaterials. While the H-titanate nanotubes transform into tiny anatase nanocrystallites of ca. 3 nm in size, the formed nanocrystallites as an intermediate grow into the TiO 2 nanomaterials with controlled phase composition and morphology. This growth process involves the steps of protonation, oriented attachment, and Ostwald ripening.

Preparation and thermal performance of polystyrene/n-tetradecane composite nanoencapsulated cold energy storage phase change materials

International Nuclear Information System (INIS)

Fang, Yutang; Yu, Huimin; Wan, Weijun; Gao, Xuenong; Zhang, Zhengguo

2013-01-01

Highlights: • Average particle size of Tet/PS nanocapsules is smaller than the same type composite. • Latent heat of Tet/PS nanocapsules is as high as the same type composite. • Freeze–thaw cycle test and centrifugal sedimentation method are employed. • Tet/PS nanocapsules can be a candidate for cold thermal energy storage. - Abstract: In this paper, a novel polystyrene/n-tetradecane composite nanoencapsulated phase change material as latent functionally thermal fluid (LFTF) for cold thermal energy storage was synthesized by ultrasonic-assistant miniemulsion in situ polymerization. The morphology, chemical structure and thermal performances of the nanoencapsulated phase change material (NEPCM) were measured by particle size analyzer, transmission electron microscope (TEM), Fourier transform infrared (FT-IR), differential scanning calorimetry (DSC) and thermogravimetric analysis (TG), respectively. The thermo-physical properties of the cool storage media were tested as well. The results showed that, a uniform spherical NEPCM with average diameter of 132 nm was prepared. The melting and freezing points and the latent heats of the NEPCMs was measured as 4.04 °C and −3.43 °C, 98.71 J g −1 and 91.27 J g −1 , respectively. The specific heat of its latex were determined as the maximum value of 4.822 J g −1 K −1 . The freeze–thaw cycle test indicated that the NEPCMs have good mechanical stability, and most capsules were still complete except some broken individuals from TEM images. Due to its good thermal properties and mechanical stability, the polystyrene/n-tetradecane NEPCM displays a good potential for cool energy storage

MC3T3-E1 cell response of amorphous phase/TiO{sub 2} nanocrystal composite coating prepared by microarc oxidation on titanium

Energy Technology Data Exchange (ETDEWEB)

Zhou, Rui [Department of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Wei, Daqing, E-mail: daqingwei@hit.edu.cn [Department of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Yang, Haoyue; Feng, Wei [Department of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Cheng, Su [Department of Mechanical Engineering, School of Architecture and Civil Engineering, Harbin University of Science and Technology, Harbin 150001 (China); Li, Baoqiang; Wang, Yaming; Jia, Dechang; Zhou, Yu [Department of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China)

2014-06-01

Bioactive amorphous phase/TiO{sub 2} nanocrystal (APTN) composite coatings were fabricated by microarc oxidation (MAO) on Ti. The APTN coatings are composed of much amorphous phase with Si, Na, Ca, Ti and O elements and a few TiO{sub 2} nanocrystals. With increasing applied voltage, the micropore density of the APTN coating decreases and the micropore size of the APTN coating increases. The results indicate that less MC3T3-E1 cells attach on the APTN coatings as compared to Ti. However, the APTN coatings greatly enhance the cell proliferation ability and the activity of alkaline phosphatase. The amorphous phase and the concentrations of the released Ca and Si from the APTN coatings during cell culture have significant effects on the cell response. - Highlights: • Amorphous phase/TiO2 nanocrystal (APTN) composite coatings were fabricated. • The MC3T3-E1 cell response of the APTN coatings was evaluated. • The APTN coatings greatly enhanced the cell proliferation ability.

Size effects on structural and dielectric properties of PZT thin films at compositions around the morpho tropic phase boundary

International Nuclear Information System (INIS)

Lima, Elton Carvalho; Araujo, Eudes Borges; Souza Filho, Antonio Gomes de; Bdikin, Igor

2011-01-01

Full text: The demand for portability in consumer electronics has motivated the understanding of size effects on ferroelectric thin films. The actual comprehension of these effects in ferroelectrics is unsatisfactory, since the polarization interacts more strongly than other order parameters such as strain and charge. As a result, extrinsic effects are produced if these variables are uncontrolled and problems such as ferroelectric paraelectric phase transition at nanometers scale remains an unsolved issue. In the present work, the effects of thickness and compositional fractions on the structural and dielectric properties of PbZr 1-x Ti x O 3 (PZT) thin films were studied at a composition around the morphotropic phase boundary (x = 0.50). For this purpose, thin films with different thicknesses and different PbO excess were deposited on Si(100) and Pt=T iO 2 =SiO 2 =Si substrates by a chemical method and crystallized in electric furnace at 700 deg C for 1 hour. The effects of substrate, pyrolysis temperature and excess lead addition in the films are reported. For films with 10 mol% PbO in excess, the pyrolysis in the regime of 300 deg C for 30 minutes was observed to yield PZT pyrochlore free thin films deposited on Pt=T iO 2 =SiO 2 =Si substrate. Out this condition, the transformation from amorphous to the pyrochlore metastable phase is kinetically more favorable that a transformation to the perovskite phase, which is thermodynamically stable. Rietveld refinements based on X-ray diffraction results showed that films present a purely tetragonal phase and that this phase does not change when the film thickness decreases. The dielectric permittivity measurements showed a monoclinic → tetragonal phase transition at 198K. Results showed that the dielectric permittivity (ε) increases continuously from 257 to 463, while the thickness of the PZT films increases from 200 to 710 nm. These results suggests that interface pinning centers can be the responsible mechanism by

Fabrication and characterization of stearic acid/polyaniline composite with electrical conductivity as phase change materials for thermal energy storage

International Nuclear Information System (INIS)

Wang, Yi; Ji, Hui; Shi, Huan; Zhang, Ting; Xia, TianDong

2015-01-01

Highlights: • Stearic acid/polyaniline composite PCM with electrical conductivity was fabricated. • Stearic acid acted as thermal energy storage media and doping acid. • Latent heats of SA/PANI are as high as the same type composites. • Improved electrical conductivity of capsules is 0.7042 S cm −1 . - Abstract: This paper presents the experimental investigation on the thermal properties and electrical conductivity of the new microencapsulated phase change material by entrapping of stearic acid (SA) into PANI (polyaniline) shell through self-assembly method. Experimental results reveal that PANI nuclei grew on the surface of SA, and then copied its original morphological structure and finally exhibited peony flower-like morphology. The two components have good compatibility and have no chemical reaction both in the process of fabrication and subsequent use, while hydrogen bondings between the imino groups and carboxyl groups exist. The maximum mass fraction of stearic acid loaded in SA/PANI is determined as high as 62.1 wt% without seepage of melted SA from capsules. Due to the secondary doping with carboxyl group, the composite phase change material embedded with SA exhibits improved electrical conductivity from 0.3968 S cm −1 to 0.7042 S cm −1 when compared to PANI. The phase change temperatures and latent heats of SA/PANI are measured to be 55.6 °C and 113.02 J/g for melting and, 50.8 °C and 112.58 J/g for freezing, respectively. TG analysis test revealed that the prepared SA/PANI composite PCM has high thermal durability in working temperature range. Moreover, the results of DSC, FT-IR, TG, conductivity investigation and thermal cycling test are all show that the thermal reliability and electrical conductivity of the SA/APNI have imperceptible changes. In total, the additional electrical conductivity, high heat storage potential and good thermal reliability and stability facilitated SA/PANI to be considered as a viable candidate for thermal

Effect of borojo (Borojoa patinoi Cuatrecasas) three-phase composition and gum arabic on the glass transition temperature.

Science.gov (United States)

Rodríguez-Bernal, Jenny M; Tello, Edisson; Flores-Andrade, Enrique; Perea-Flores, Maria de Jesús; Vallejo-Cardona, Alba A; Gutiérrez-López, Gustavo F; Quintanilla-Carvajal, Maria X

2016-02-01

The search for natural, novel, high-quality, stable food ingredients is an ongoing practice in the food industry. Pulp of borojo (Borojoa patinoi Cuatrecasas), which is a fruit of the Colombian Pacific region, can be separated into three phases: liquid (LP), medium (MP) and solid (SP) phases. The objective of this work was to evaluate the effect of the three-phase composition and gum arabic on their glass transitions temperatures (T(g)). The best mixture, LP-MP, MP-SP and LP-SP and gum arabic (GA) was identified by response surface methodology. When adding GA to SP borojo phase in a 1:1 proportion, the resulting T(g) of the mixture was 132.27 °C whereas Tg for GA and SP-phase were 154.89 °C and 79.86 °C respectively, which supported this combination as attractive from a processing perspective and supports an industrial advantage of using borojo as food ingredient. Phases were characterized by high-performance liquid chromatography, Fourier transform infrared spectroscopy, confocal laser scanning microscopy and mass spectrometry. Low molecular weight compounds such as fructose for MP lowered T(g) whereas the presence of lignin increased T(g) of the mixtures as with the SP. The addition of GA significantly increased T(g) of borojo phases so leading to propose them as novel food processing materials. © 2015 Society of Chemical Industry.

Thermal and electrical conductivity enhancement of graphite nanoplatelets on form-stable polyethylene glycol/polymethyl methacrylate composite phase change materials

International Nuclear Information System (INIS)

Zhang, Lei; Zhu, Jiaoqun; Zhou, Weibing; Wang, Jun; Wang, Yan

2012-01-01

Graphite nanoplatelets (GnPs), obtained by sonicating the expanded graphite, were employed to simultaneously enhance the thermal (k) and electrical (σ) conductivity of organic form-stable phase change materials (FSPCMs). Using the method of in situ polymerization upon ultrasonic irradiation, GnPs serving as the conductive fillers and polyethylene glycol (PEG) acting as the phase change material (PCM) were uniformly dispersed and embedded inside the network structure of polymethyl methacrylate (PMMA), which contributed to the well package and self-supporting properties of composite FSPCMs. X-ray diffraction and Fourier transform infrared spectroscopy results indicated that the GnPs were physically combined with PEG/PMMA matrix and did not participate in the polymerization. The GnPs additives were able to effectively enhance the k and σ of organic FSPCM. When the mass ratio of GnP was 8%, the k and σ of FSPCM changed up to 9 times and 8 orders of magnitude over that of PEG/PMMA matrix, respectively. The improvements in both k and σ were mainly attributed to the well dispersion and large aspect ratio of GnPs, which were endowed with benefit of forming conducting network in polymer matrix. It was also confirmed that all the prepared specimens possessed available thermal storage density and thermal stability. -- Highlights: ► GnPs were employed to simultaneously enhance the k and σ of organic FSPCMs. ► PEG/PMMA/GnPs composite FSPCMs were prepared by in situ polymerization method. ► The composite FSPCMs exhibited well package and self-supporting properties. ► GnPs additives effectively enhanced the k and σ of composite FSPCMs. ► All the composites possessed available thermal storage density and thermal stability.

EFFECT OF THE PHASE STRUCTURE EVOLUTION ON THE PROPERTIES OF FILMS FORMED FROM PBA/P(ST-CO-MMA)COMPOSITE LATEX

Institute of Scientific and Technical Information of China (English)

无

2008-01-01

A group of heterogeneous latexes poly(butyl acrylate)/poly(styrene-co-methyl methacrylate)(PBA/P(St-co-MMA))were prepared by a semi-continuous seeded emulsion polymerization process under monomer starved conditions.The glass transition temperature(Tg)and the mechanical properties of the film formed from the composite latex changed with the evolution of the particle morphology.A photon transmission method was used to monitor the phase structure evolution of films which were prepared from core-shell PBA/P(St-co-MMA)latex at room temperature and annealed at 383 K above Tg of the polymers.In addition,the changes of the surface of the film formed from the composite latex with time at 383 K were observed by AFM.The evidence illustrated that the film formed from the core-shell latex particles was metastable.The rearrangement of the phases could occur under proper conditions.

[DNA complexes, formed on aqueous phase surfaces: new planar polymeric and composite nanostructures].

Science.gov (United States)

Antipina, M N; Gaĭnutdinov, R V; Rakhnianskaia, A A; Sergeev-Cherenkov, A N; Tolstikhina, A L; Iurova, T V; Kislov, V V; Khomutov, G B

2003-01-01

The formation of DNA complexes with Langmuir monolayers of the cationic lipid octadecylamine (ODA) and the new amphiphilic polycation poly-4-vinylpyridine with 16% of cetylpyridinium groups (PVP-16) on the surface of an aqueous solution of native DNA of low ionic strength was studied. Topographic images of Langmuir-Blodgett films of DNA/ODA and DNA/PVP-16 complexes applied to micaceous substrates were investigated by the method of atomic force microscopy. It was found that films of the amphiphilic polycation have an ordered planar polycrystalline structure. The morphology of planar DNA complexes with the amphiphilic cation substantially depended on the incubation time and the phase state of the monolayer on the surface of the aqueous DNA solution. Complex structures and individual DNA molecules were observed on the surface of the amphiphilic monolayer. Along with quasi-linear individual bound DNA molecules, characteristic extended net-like structures and quasi-circular toroidal condensed conformations of planar DNA complexes were detected. Mono- and multilayer films of DNA/PVP-16 complexes were used as templates and nanoreactors for the synthesis of inorganic nanostructures via the binding of metal cations from the solution and subsequent generation of the inorganic phase. As a result, ultrathin polymeric composite films with integrated DNA building blocks and quasi-linear arrays of inorganic semiconductor (CdS) and iron oxide nanoparticles and nanowires were obtained. The nanostructures obtained were characterized by scanning probe microscopy and transmission electron microscopy techniques. The methods developed are promising for investigating the mechanisms of structural organization and transformation in DNA and polyelectrolyte complexes at the gas-liquid interface and for the design of new extremely thin highly ordered planar polymeric and composite materials, films, and coatings with controlled ultrastructure for applications in nanoelectronics and

Electric-field-induced strain contributions in morphotropic phase boundary composition of (Bi{sub 1/2}Na{sub 1/2})TiO{sub 3}-BaTiO{sub 3} during poling

Energy Technology Data Exchange (ETDEWEB)

Khansur, Neamul H.; Daniels, John E. [School of Materials Science and Engineering, UNSW Australia, New South Wales 2052 (Australia); Hinterstein, Manuel [School of Materials Science and Engineering, UNSW Australia, New South Wales 2052 (Australia); Institute for Applied Materials, Karlsruhe Institute for Technology, P.O. Box 3640, 76021 Karlsruhe (Germany); Wang, Zhiyang [School of Materials Science and Engineering, UNSW Australia, New South Wales 2052 (Australia); The Australian Synchrotron, Clayton, Victoria 3168 (Australia); Groh, Claudia [Institute of Materials Science, Technische Universität Darmstadt, Alarich-Weiss-Straße 2, 64287 Darmstadt (Germany); Jo, Wook [School of Materials Science and Engineering, Ulsan National Institute of Science and Technology, Ulsan 44919 (Korea, Republic of)

2015-12-14

The microscopic contributions to the electric-field-induced macroscopic strain in a morphotropic 0.93(Bi{sub 1/2}Na{sub 1/2}TiO{sub 3})−0.07(BaTiO{sub 3}) with a mixed rhombohedral and tetragonal structure have been quantified using full pattern Rietveld refinement of in situ high-energy x-ray diffraction data. The analysis methodology allows a quantification of all strain mechanisms for each phase in a morphotropic composition and is applicable to use in a wide variety of piezoelectric compositions. It is shown that during the poling of this material 24%, 44%, and 32% of the total macroscopic strain is generated from lattice strain, domain switching, and phase transformation strains, respectively. The results also suggest that the tetragonal phase contributes the most to extrinsic domain switching strain, whereas the lattice strain primarily stems from the rhombohedral phase. The analysis also suggests that almost 32% of the total strain is lost or is a one-time effect due to the irreversible nature of the electric-field-induced phase transformation in the current composition. This information is relevant to on-going compositional development strategies to harness the electric-field-induced phase transformation strain of (Bi{sub 1/2}Na{sub 1/2})TiO{sub 3}-based lead-free piezoelectric materials for actuator applications.

Observation of Kosterlitz-Thouless phase transition in the composite superconductor (NbTi)-Cu

International Nuclear Information System (INIS)

Fischer, E.; Khukhareva, I.S.

1989-01-01

Results are reported of an experimental investigation of the resistive behavior of a composite superconductor carrying a current perpendicular to the superconducting filaments. The sample resistance exhibits in this case, depending on the temperature and on the measurement current, a number of peculiarities, and in particular a two-step transition to the superconducting state. On the basis of an analysis of the laws governing these peculiarities, a model is developed for topological Kosterlitz-Thouless phase transitions in bulk systems. Topological defects of a new type, current-stimulated excitations, are considered. The deduced empirical relations scale with var-epsilon = I/I c . A correlation is established between the characteristic values for two- and three-dimensional systems

Nano-Scale Interpenetrating Phase Composites (IPC S) for Industrial and Vehicle Applications

Energy Technology Data Exchange (ETDEWEB)

Hemrick, James Gordon [ORNL; Hu, Michael Z. [ORNL

2010-06-01

A one-year project was completed at Oak Ridge National Laboratory (ORNL) to explore the technical and economic feasibility of producing nano-scale Interpenetrating Phase Composite (IPC) components of a usable size for actual testing/implementation in a real applications such as high wear/corrosion resistant refractory shapes for industrial applications, lightweight vehicle braking system components, or lower cost/higher performance military body and vehicle armor. Nano-scale IPC s with improved mechanical, electrical, and thermal properties have previously been demonstrated at the lab scale, but have been limited in size. The work performed under this project was focused on investigating the ability to take the current traditional lab scale processes to a manufacturing scale through scaling of these processes or through the utilization of an alternative high-temperature process.

The Gaseous Phase as a Probe of the Astrophysical Solid Phase Chemistry

Energy Technology Data Exchange (ETDEWEB)

Abou Mrad, Ninette; Duvernay, Fabrice; Isnard, Robin; Chiavassa, Thierry; Danger, Grégoire, E-mail: gregoire.danger@univ-amu.fr [Aix-Marseille Université, PIIM UMR-CNRS 7345, F-13397 Marseille (France)

2017-09-10

In support of space missions and spectroscopic observations, laboratory experiments on ice analogs enable a better understanding of organic matter formation and evolution in astrophysical environments. Herein, we report the monitoring of the gaseous phase of processed astrophysical ice analogs to determine if the gaseous phase can elucidate the chemical mechanisms and dominant reaction pathways occurring in the solid ice subjected to vacuum ultra-violet (VUV) irradiation at low temperature and subsequently warmed. Simple (CH{sub 3}OH), binary (H{sub 2}O:CH{sub 3}OH, CH{sub 3}OH:NH{sub 3}), and ternary ice analogs (H{sub 2}O:CH{sub 3}OH:NH{sub 3}) were VUV-processed and warmed. The evolution of volatile organic compounds in the gaseous phase shows a direct link between their relative abundances in the gaseous phase, and the radical and thermal chemistries modifying the initial ice composition. The correlation between the gaseous and solid phases may play a crucial role in deciphering the organic composition of astrophysical objects. As an example, possible solid compositions of the comet Lovejoy are suggested using the abundances of organics in its comae.

Composition-dependent phase separation effects of organic solar cells using P3HT:PCBM as active layer and chromium oxide as hole transporting layer

International Nuclear Information System (INIS)

Qin Pingli; Fang Guojia; Sun Nanhai; Fan Xi; Zheng Qiao; Chen Fei; Wan Jiawei; Zhao Xingzhong

2011-01-01

Phase separation of the poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) active layer (ATL) was investigated by varying their relative ratio in the organic solar cells (OSCs). With the help of the UV/visible spectrophotometer, optical microscopy and scanning electron microscope, we found that the cluster of PCBM at the interface or surface was affected by Al cathode, the composition of the blends and thermal annealing. The disc-like shape crystals of PCBM substituted for the needle-like ones at higher PCBM compositions at the ATL/Al interface, which led to stronger contacts and bigger contact area. It could make short circuit current density increase, but may affect the blend morphology and result in parallel resistance and open circuit voltage decreased with the PCBM ratio increasing from 40 to 60%. The microstructure of the P3HT:PCBM ATL, determined by the composition dependent phase separation, supported the optimized performance of the OSCs with the composition of 40-50% PCBM.

Effect of air humidity on microstructure and phase composition of lithium deuteride corrosion products

International Nuclear Information System (INIS)

Liu, Xiaobo; Liu, Jiping

2017-01-01

Highlights: • Lithium deuteride samples are corroded by air with different relative humidity. • Show the structure and composition of fracture surface of corrosion particle. • The lithium carbonate formation is related to air humidity. • The lithium carbonate only exists in the surface of lithium hydroxide layer. • There is a concentration gradient of H 2 O across the lithium hydroxide layer. - Abstract: Lithium deuteride (LiD) was exposed to air for 600 min to determine the effect of air humidity on its microstructure and phase composition. XRD and XPS results revealed that LiOH and Li 2 CO 3 formed at relative humidity values of >30%, whereas only LiOH formed at values <20%. SEM and EDS images showed a clear LiOH layer; Li 2 CO 3 was confined to the surface of this layer. The schematic illustration revealed that the concentration gradient of H 2 O across the LiOH layer resulted in little Li 2 CO 3 formed in the layer. This work will contribute to increase understanding of LiD corrosion in air.

Electroactive properties of flexible piezoelectric composites

Directory of Open Access Journals (Sweden)

Sakamoto Walter Katsumi

2001-01-01

Full Text Available A flexible piezoelectric composite with 0-3 connectivity, made from Lead Zirconate Titanate (PZT powder and vegetable-based polyurethane (PU, was doped with small amount of semiconductor powder. As a result a composite with 0-0-3 connectivity was obtained. The nature of absorption and steady state electrical conduction and the dielectric behaviour have been studied for this ceramic/polymer composite. The dielectric loss processes of the composite were observed to be dominated by those the polymer. Adding a semiconductor phase in the composite the electrical conductivity can be controlled and a continuous electric flux path could be created between the PZT grains. This composite may be poled at low voltage and in shorter time compared with composites without a conductive phase.

Efficient and robust compositional two-phase reservoir simulation in fractured media

Science.gov (United States)

Zidane, A.; Firoozabadi, A.

2015-12-01

Compositional and compressible two-phase flow in fractured media has wide applications including CO2 injection. Accurate simulations are currently based on the discrete fracture approach using the cross-flow equilibrium model. In this approach the fractures and a small part of the matrix blocks are combined to form a grid cell. The major drawback is low computational efficiency. In this work we use the discrete-fracture approach to model the fractures where the fracture entities are described explicitly in the computational domain. We use the concept of cross-flow equilibrium in the fractures (FCFE). This allows using large matrix elements in the neighborhood of the fractures. We solve the fracture transport equations implicitly to overcome the Courant-Freidricks-Levy (CFL) condition in the small fracture elements. Our implicit approach is based on calculation of the derivative of the molar concentration of component i in phase (cαi ) with respect to the total molar concentration (ci ) at constant volume V and temperature T. This contributes to significant speed up of the code. The hybrid mixed finite element method (MFE) is used to solve for the velocity in both the matrix and the fractures coupled with the discontinuous Galerkin (DG) method to solve the species transport equations in the matrix, and a finite volume (FV) discretization in the fractures. In large scale problems the proposed approach is orders of magnitude faster than the existing models.

Phase equilibria and phase structures of polymer blends

International Nuclear Information System (INIS)

Chalykh, Anatolii E; Gerasimov, Vladimir K

2004-01-01

Experimental, methodical and theoretical studies dealing with phase equilibria and phase structures of polymer blends are generalised. The general and specific features of the change in solubility of polymers with changes in the molecular mass and copolymer composition and upon the formation of three-dimensional cross-linked networks are described. The results of the effect of the prehistory on the phase structure and the non-equilibrium state of polymer blends are considered in detail.

Quantitative analysis of aqueous phase composition of model dentin adhesives experiencing phase separation

Science.gov (United States)

Ye, Qiang; Park, Jonggu; Parthasarathy, Ranganathan; Pamatmat, Francis; Misra, Anil; Laurence, Jennifer S.; Marangos, Orestes; Spencer, Paulette

2013-01-01

There have been reports of the sensitivity of our current dentin adhesives to excess moisture, for example, water-blisters in adhesives placed on over-wet surfaces, and phase separation with concomitant limited infiltration of the critical dimethacrylate component into the demineralized dentin matrix. To determine quantitatively the hydrophobic/hydrophilic components in the aqueous phase when exposed to over-wet environments, model adhesives were mixed with 16, 33, and 50 wt % water to yield well-separated phases. Based upon high-performance liquid chromatography coupled with photodiode array detection, it was found that the amounts of hydrophobic BisGMA and hydrophobic initiators are less than 0.1 wt % in the aqueous phase. The amount of these compounds decreased with an increase in the initial water content. The major components of the aqueous phase were hydroxyethyl methacrylate (HEMA) and water, and the HEMA content ranged from 18.3 to 14.7 wt %. Different BisGMA homologues and the relative content of these homologues in the aqueous phase have been identified; however, the amount of crosslinkable BisGMA was minimal and, thus, could not help in the formation of a crosslinked polymer network in the aqueous phase. Without the protection afforded by a strong crosslinked network, the poorly photoreactive compounds of this aqueous phase could be leached easily. These results suggest that adhesive formulations should be designed to include hydrophilic multimethacrylate monomers and water compatible initiators. PMID:22331596

Thermal characteristics of expanded perlite/paraffin composite phase change material with enhanced thermal conductivity using carbon nanotubes

International Nuclear Information System (INIS)

Karaipekli, Ali; Biçer, Alper; Sarı, Ahmet; Tyagi, Vineet Veer

2017-01-01

Highlights: • Expanded perlite/n-eicosane composite for thermal energy storage was prepared. • Addition of CNTs increases considerably the thermal conductivity of the composite. • The composite PCM including 1 wt% CNTs is promising material. - Abstract: Paraffins constitute a class of solid-liquid organic phase change materials (PCMs). However, low thermal conductivity limits their feasibility in thermal energy storage (TES) applications. Carbon nano tubes (CNTs) are one of the best materials to increase the thermal conductivity of paraffins. In this regard, the present study is focus on the preparation, characterization, and improvement of thermal conductivity using CNTs as well as determination of TES properties of expanded perlite (ExP)/n-eicosane (C20) composite as a novel type of form-stable composite PCM (F-SCPCM). It was found that the ExP could retain C20 at weight fraction of 60% without leakage. The SEM and FTIR analyses were carried out to characterize the microstructure and chemical properties of the composite PCM. The TES properties of the prepared F-SCPCM were determined using DSC and TG analyses. The analysis results showed that the components of the composite are in good compatibleness and C20 used as PCM are well-infiltrated into the structure of ExP/CNTs matrix. The DSC analysis indicated that the ExP/C20/CNTs (1 wt%) composite has a melting point of 36.12 °C and latent heat of 157.43 J/g. The TG analysis indicated that the F-SCPCM has better thermal durability compared with pure C20 and also it has good long term-TES reliability. In addition, the effects of CNTs on the thermal conductivity of the composite PCM were investigated. Compared to ExP/C20 composite, the use of CNTs has apparent improving effect for the thermal conductivity without considerably affecting the compatibility of components, TES properties, and thermal stability.

Equivalence of two models in single-phase multicomponent flow simulations

KAUST Repository

Wu, Yuanqing

2016-02-28

In this work, two models to simulate the single-phase multicomponent flow in reservoirs are introduced: single-phase multicomponent flow model and two-phase compositional flow model. Because the single-phase multicomponent flow is a special case of the two-phase compositional flow, the two-phase compositional flow model can also simulate the case. We compare and analyze the two models when simulating the single-phase multicomponent flow, and then demonstrate the equivalence of the two models mathematically. An experiment is also carried out to verify the equivalence of the two models.

Equivalence of two models in single-phase multicomponent flow simulations

KAUST Repository

Wu, Yuanqing; Sun, Shuyu

2016-01-01

In this work, two models to simulate the single-phase multicomponent flow in reservoirs are introduced: single-phase multicomponent flow model and two-phase compositional flow model. Because the single-phase multicomponent flow is a special case of the two-phase compositional flow, the two-phase compositional flow model can also simulate the case. We compare and analyze the two models when simulating the single-phase multicomponent flow, and then demonstrate the equivalence of the two models mathematically. An experiment is also carried out to verify the equivalence of the two models.

Composition-induced structural phase transitions in the (Ba1-xLax)2In2O5+x (0=

International Nuclear Information System (INIS)

Tenailleau, C.; Pring, A.; Moussa, S.M.; Liu, Y.; Withers, R.L.; Tarantino, S.; Zhang, M.; Carpenter, M.A.

2005-01-01

Composition-induced structural phase changes across the high temperature, fast oxide ion conducting (Ba 1-x La x ) 2 In 2 O 5+x , 0= orthorhombic transition, while the cubic->tetragonal transition could be continuous. Differences between the variation with composition of spectral parameters and of macroscopic strain parameters are consistent with a substantial order/disorder component for the transitions. There is also evidence for precursor effects within the cubic structure before symmetry is broken

Modeling precipitation thermodynamics and kinetics in type 316 austenitic stainless steels with varying composition as an initial step toward predicting phase stability during irradiation

Energy Technology Data Exchange (ETDEWEB)

Shim, Jae-Hyeok, E-mail: jhshim@kist.re.kr [Department of Nuclear Engineering, University of Tennessee, Knoxville, TN 37996 (United States); High Temperature Energy Materials Research Center, Korea Institute of Science and Technology, Seoul 136-791 (Korea, Republic of); Povoden-Karadeniz, Erwin [Christian Doppler Laboratory for Early Stages of Precipitation, Vienna University of Technology, A-1040 Vienna (Austria); Kozeschnik, Ernst [Institute of Materials Science and Technology, Vienna University of Technology, A-1040 Vienna (Austria); Wirth, Brian D. [Department of Nuclear Engineering, University of Tennessee, Knoxville, TN 37996 (United States)

2015-07-15

Highlights: • We model the precipitation kinetics in irradiated 316 austenitic stainless steels. • Radiation-induced phases are predicted to form at over 10 dpa segregation conditions. • The Si content is the most critical for the formation of radiation-induced phases. - Abstract: The long-term evolution of precipitates in type 316 austenitic stainless steels at 400 °C has been simulated using a numerical model based on classical nucleation theory and the thermodynamic extremum principle. Particular attention has been paid to the precipitation of radiation-induced phases such as γ′ and G phases. In addition to the original compositions, the compositions for radiation-induced segregation at a dose level of 5, 10 or 20 dpa have been used in the simulation. In a 316 austenitic stainless steel, γ′ appears as the main precipitate with a small amount of G phase forming at 10 and 20 dpa. On the other hand, G phase becomes relatively dominant over γ′ at the same dose levels in a Ti-stabilized 316 austenitic stainless steel, which tends to suppress the formation of γ′. Among the segregated alloying elements, the concentration of Si seems to be the most critical for the formation of radiation-induced phases. An increase in dislocation density as well as increased diffusivity of Mn and Si significantly enhances the precipitation kinetics of the radiation-induced phases within this model.

CARBON-CONTAINING COMPOSITES BASED ON METALS

Directory of Open Access Journals (Sweden)

VAGANOV V. E.

2015-10-01

Full Text Available Problem statement Among the developed technologies metal-composites production,a special place takes powder metallurgy, having fundamental differences from conventionally used foundry technologies. The main advantages of this technology are: the possibility of sensitive control, the structure and phase composition of the starting components, and ultimately the possibility of obtaining of bulk material in nanostructured state with a minimum of processing steps. The potential reinforcers metals include micro and nano-sized oxides, carbides, nitrides, whiskers. The special position is occupied with carbon nanostructures (CNS: С60 fullerenes, single-layer and multi-layer nanotubes, onions (spherical "bulbs", nano-diamonds and graphite,their properties are being intensively studied in recent years. These objects have a high thermal and electrical conductivity values, superelasticity, and have a strength approximate to the theoretical value, which can provide an obtaining composite nanomaterial with a unique set of physical and mechanical properties. In creation of a metal matrix composite nanomaterials (CM, reinforced by various CNS, a special attention should be given to mechanical activation processes (MA already at the stage of preparation of the starting components affecting the structure, phase composition and properties of aluminum-matrix composites. Purpose. To investigate the influence of mechanical activation on the structure and phase composition of aluminum-matrix composites. Conclusion. The results of the study of the structure and phase composition of the initial and mechanically activated powders and bulk-modified metal-composites are shown, depending on the type and concentration of modifying varieties CNS, regimes of MA and parameters of compaction. The study is conducted of tribological properties of Al-CNS OF nanostructured materials.

Phase-change materials handbook

Science.gov (United States)

Hale, D. V.; Hoover, M. J.; Oneill, M. J.

1972-01-01

Handbook describes relationship between phase-change materials and more conventional thermal control techniques and discusses materials' space and terrestrial applications. Material properties of most promising phase-change materials and purposes and uses of metallic filler materials in phase-change material composites are provided.

Transmission electron microscopy observations on phase transformations during aluminium/mullite composites formation by gas pressure infiltration

Energy Technology Data Exchange (ETDEWEB)

Pawlyta, M., E-mail: miroslawa.pawlyta@polsl.pl [Silesian University of Technology, Institute of Engineering Materials and Biomaterials, Konarskiego 18A, 44-100 Gliwice (Poland); Tomiczek, B.; Dobrzański, L.A.; Kujawa, M. [Silesian University of Technology, Institute of Engineering Materials and Biomaterials, Konarskiego 18A, 44-100 Gliwice (Poland); Bierska-Piech, B. [Silesian Centre for Education and Interdisciplinary Research, 75 Pułku Piechoty 1A, 41-500 Chorzów (Poland)

2016-04-15

The porous ceramic preforms were manufactured using the powder metallurgy technique. First, the start-up material (halloysite with the addition of carbon fibres as the pore-forming agent) was slowly heated to 800 °C and then sintered at 1300 °C. Degradation of the carbon fibres enabled the open canals to form. At the end of the sintering process, the porous ceramic material consisting mainly of two phases (mullite and cristobalite) was formed, without any residual carbon content. During infiltration, the liquid metal filled the empty spaces (pores) effectively and formed the three-dimensional network of metal in the ceramic. The cristobalite was almost entirely decomposed. In the areas of its previous occurrence, there are new pores, only in the ceramic grains. The mullite, which was formed from halloysite during annealing, crystallized in the Pbam orthorhombic space group, with the (3Al{sub 2}O{sub 3}·2SiO{sub 2}) stoichiometric composition. The mullite structure does not change during the infiltration. The composite components are tightly connected. A transition zone between the ceramics and the metal, having the thickness of about 200 nm, was formed. The nanocrystalline zone, identified as γ-Al{sub 2}O{sub 3}, was formed by diffusing the product of the cristobalite decomposition into the aluminium alloy matrix. There is an additional, new phase, identified as (Mg,Si)Al{sub 2}O{sub 4} in the outer parts of the transition zone. - Highlights: • Phase changes after the infiltration of aluminium into porous mullite preforms were observed by TEM. • TEM observations confirm that during infiltration cristobalite was decomposed and the structure of mullite did not change. • Between the ceramic and the metal, a transition zone comprising a layer of γ-Al{sub 2}O{sub 3} and (Mg,Si)Al{sub 2}O{sub 4} was formed.

Colossal magnetoresistance of bulk Ag-doped Nd{sub 0.7}Sr{sub 0.3}MnO{sub 3} two-phase composites

Energy Technology Data Exchange (ETDEWEB)

Cui Xugao [National Laboratory of Solid State Microstructures, Department of Physics, Nanjing University, Nanjing 210093 (China); Hu Xiukun [National Laboratory of Solid State Microstructures, Department of Physics, Nanjing University, Nanjing 210093 (China); Xia Hongxu [National Laboratory of Solid State Microstructures, Department of Physics, Nanjing University, Nanjing 210093 (China); Yu Jiangying [National Laboratory of Solid State Microstructures, Department of Physics, Nanjing University, Nanjing 210093 (China); Zhang Shiyuan [National Laboratory of Solid State Microstructures, Department of Physics, Nanjing University, Nanjing 210093 (China)]. E-mail: zsy@netra.nju.edu.cn

2005-05-17

We have prepared a series of bulk polycrystalline manganites with the nominal compositions, Nd{sub 0.7}Sr{sub 0.3}MnO{sub 3}-Ag {sub x} (x is the molar fraction) with x = 0.1, 0.2, 0.3, 0.4, 0.5 by conventional solid-state reaction. The X-ray diffraction patterns show that the sample Nd{sub 0.7}Sr{sub 0.3}MnO{sub 3} (x = 0) is a single-phase compound with the pseudocubic perovskite structure, while the Ag-doped samples are two-phase composites consisting of a ferromagnetic perovskite phase and a nonmagnetic Ag metal phase. For all the samples, the Curie temperature, T {sub C}, remains nearly the same (228 {+-} 2 K), but the maximum magnetoresistance in a magnetic field of 1 T at 222 K is enhanced strongly due to the addition of Ag, namely, from 45% for the Nd{sub 0.7}Sr{sub 0.3}MnO{sub 3} sample to 188, 277, 142, 158 and 151% for the Nd{sub 0.7}Sr{sub 0.3}MnO{sub 3}-Ag {sub x} samples with x = 0.1, 0.2, 0.3, 0.4, and 0.5, respectively. This magnetoresistance-enhancement phenomenon can be attributed to the spin-dependent scattering of the spin-polarized electrons at the interfaces between the perovskite grains and the Ag granules.

Influence of composition of the raw materials on phase formation in solid compounds based on slag and clay minerals

International Nuclear Information System (INIS)

Galkin, A.V.; Tolebaev, T.; Omarova, V.I.; Burkitbaev, M.; Blynskiy, A.P.; Bachilova, N.V.; Matsynina, V.I.

2003-01-01

Full text: Activation of solidification processes in a compound formed on the basis of slag and clay minerals using sodium hydroxide - the output product from processing the BN-350 sodium coolant it is expedient to form the final product with a phase composition representing (in terms of long term storage) hydro-alumino-silicates incorporating Na-22 and Cs-137 radionuclides, which isomorphly replace other atoms in the crystal lattice sites. Combination of mineral phases, such as alkaline and alkaline-earth hydro-alumino-silicates with zeolite-like structure, providing sorptive properties, and the tobermorite like low-base hydro silicates of calcium defining the physico-mechanical properties of compound is the necessary condition for the compound stability. Investigations of phase formation in the mixtures of Kazakhstan clay, slag materials and alkali have been conducted targeted to control the physico-chemical properties of solid compound. The mixtures of alkali, thermal power plant ashes and clays of various mineralogical genesis (kaolinite, bentonite, Ca-Na-smectite montmorillonite) have been studied. The ashes and phosphorous slag while interacting with alkali are determined to form the non-alkaline hydro-silicates of stavrolite and indianite (anortite) type with free alkali being found in an unbound state. Both alkaline and alkaline-alkaline-earth hydro-silicates of Na 2 Ca 2 Si 2 O 7 H 2 O type are only formed in a compounds containing metallurgical slag. Formation of alkaline hydro-alumino-silicates of NaAlSiO 4 H 2 0 type as well as tomsonite (Na 4 Ca 8 [Al 20S i 20 O 80 ] 24H 2 O) - the zeolite like mineral have been detected in a two-component alkali-clay mixtures. Besides the quantity of tomsonite was determined to be not only dependent on Al 2 O 3 content in clay component but is also defined by stoichiometric composition of the mixture, because zeolite synthesis takes place under conditions of gels co-deposition and high pH value. Maximum quantity of

Méthodes d'éléments finis pour le problème de changement de phase en milieux composites

OpenAIRE

Mint Brahim , Maimouna

2016-01-01

In this thesis we aim to develop a numerical tool that allow to solve the unsteady heatconduction problem in a composite media with a graphite foam matrix infiltrated witha phase change material such as salt, in the framework of latent heat thermal energystorage.In chapter 1, we start by explaining the model that we are studying which is separated in three sub-parts : a heat conduction problem in the foam, a phase change problem in the pores of the foam which are filled with salt and a contac...

A new Class of Extremal Composites

DEFF Research Database (Denmark)

Sigmund, Ole

2000-01-01

microstructure belonging to the new class of composites has maximum bulk modulus and lower shear modulus than any previously known composite. Inspiration for the new composite class comes from a numerical topology design procedure which solves the inverse homogenization problem of distributing two isotropic......The paper presents a new class of two-phase isotropic composites with extremal bulk modulus. The new class consists of micro geometrics for which exact solutions can be proven and their bulk moduli are shown to coincide with the Hashin-Shtrikman bounds. The results hold for two and three dimensions...... and for both well- and non-well-ordered isotropic constituent phases. The new class of composites constitutes an alternative to the three previously known extremal composite classes: finite rank laminates, composite sphere assemblages and Vigdergauz microstructures. An isotropic honeycomb-like hexagonal...

Effect of a Controlled Volume Fraction of Dendritic Phases on Tensile and Compressive Ductility in La-Based Metallic Glass Matrix Composites

National Research Council Canada - National Science Library

Lee, M

2004-01-01

A systematic study has been carried out to identify the effect of crystalline 2nd phase reinforcements on the mechanical properties of amorphous alloys based on the composition La(sub 86-y)Al(sub 14)(Cu, Ni)y (y=l to 24...

25th Anniversary Article: Polymer-Particle Composites: Phase Stability and Applications in Electrochemical Energy Storage

KAUST Repository

Srivastava, Samanvaya

2013-12-09

Polymer-particle composites are used in virtually every field of technology. When the particles approach nanometer dimensions, large interfacial regions are created. In favorable situations, the spatial distribution of these interfaces can be controlled to create new hybrid materials with physical and transport properties inaccessible in their constituents or poorly prepared mixtures. This review surveys progress in the last decade in understanding phase behavior, structure, and properties of nanoparticle-polymer composites. The review takes a decidedly polymers perspective and explores how physical and chemical approaches may be employed to create hybrids with controlled distribution of particles. Applications are studied in two contexts of contemporary interest: battery electrolytes and electrodes. In the former, the role of dispersed and aggregated particles on ion-transport is considered. In the latter, the polymer is employed in such small quantities that it has been historically given titles such as binder and carbon precursor that underscore its perceived secondary role. Considering the myriad functions the binder plays in an electrode, it is surprising that highly filled composites have not received more attention. Opportunities in this and related areas are highlighted where recent advances in synthesis and polymer science are inspiring new approaches, and where newcomers to the field could make important contributions. Polymer-particle composites are used in virtually every field of technology. When the particles approach nanometer dimensions, large interfacial regions are created that can be exploited for applications. The fundamental approaches and bottom-up synthesis strategies for understanding and controlling nanoparticle dispersion in polymers are reviewed. Applications of these approaches for creating polymer-particle composite electrolytes and electrodes for energy storage are also considered. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Composite Materials

DEFF Research Database (Denmark)

Nielsen, Lauge Fuglsang

This book deals with the mechanical and physical behavior of composites as influenced by composite geometry. "Composite Materials" provides a comprehensive introduction for researchers and students to modern composite materials research with a special emphasis on the significance of phase geometry......, viscoelastic behavior, and internal stress states. Other physical properties considered are thermal and electrical conductivities, diffusion coefficients, dielectric constants and magnetic permeability. Special attention is given to the effect of pore shape on the mechanical and physical behavior of porous....... The book enables the reader to a better understanding of the behavior of natural composites, improvement of such materials, and design of new materials with prescribed properties. A number of examples are presented: Special composite properties considered are stiffness, shrinkage, hygro-thermal behavior...

Multilayer Electroactive Polymer Composite Material Comprising Carbon Nanotubes

Science.gov (United States)

Ounaies, Zoubeida (Inventor); Park, Cheol (Inventor); Harrison, Joycelyn S. (Inventor); Holloway, Nancy M. (Inventor); Draughon, Gregory K. (Inventor)

2009-01-01

An electroactive material comprises multiple layers of electroactive composite with each layer having unique dielectric, electrical and mechanical properties that define an electromechanical operation thereof when affected by an external stimulus. For example, each layer can be (i) a 2-phase composite made from a polymer with polarizable moieties and an effective amount of carbon nanotubes incorporated in the polymer for a predetermined electromechanical operation, or (ii) a 3-phase composite having the elements of the 2-phase composite and further including a third component of micro-sized to nano-sized particles of an electroactive ceramic incorporated in the polymer matrix.

Electromechanical response of (2–2) layered piezoelectric composites

International Nuclear Information System (INIS)

Kar-Gupta, Ronit; Venkatesh, T A

2013-01-01

Analytical and finite element models are developed to systematically characterize the effects of phase volume fraction and the relative orientations of the poling directions in two phases on the effective elastic, dielectric and piezoelectric properties of layered piezoelectric composites. Four classes of layered piezoelectric composites are identified based on the relative orientation of the poling directions in the two piezoelectric phases. Upon verifying that the results of the finite model compare well with that of analytical models for select layered composite systems, the finite element model is extended to characterize the electromechanical response of all four classes of piezoelectric composites. It is generally observed that the electromechanical properties of the layered composite along a direction perpendicular to the layer interface is largely influenced by the properties of the ‘softer’ phase whereas the in-plane response is modulated more by the ‘rule-of-mixtures’ theory. It is also observed that variations in the poling directions of the constituents can significantly influence the symmetry of the composite with composites that belong to Classes II and III (where the poling directions of the two phases are orthogonal to each other) exhibiting a relatively lower degree of material symmetry while the composites that belong to Classes I and IV (where the poling directions of the two phases are parallel to each other) exhibit a higher order symmetry. Furthermore, the best combination of figures of merit, i.e., enhanced coupling constant and reduced acoustic impedance, in a direction parallel to the layer interface is exhibited by Class I and Class II types of composite (where the piezoelectrically stiffer phase is poled along the layer interface). (paper)

Effect of alloying by lanthanum and high rhenium superalloys on the basis of Ni-Al-Cr on the structure and phase composition

Energy Technology Data Exchange (ETDEWEB)

Kozlov, Eduard, E-mail: kozlov@tsuab.ru; Tsedrik, Elena, E-mail: tsedrik@sibmail.ru; Koneva, Nina, E-mail: koneva@tsuab.ru [Tomsk State University of Architecture and Building, 2, Solyanaya Sq., 634003, Tomsk (Russian Federation); Popova, Natalya, E-mail: natalya-popova-44@mail.ru [Tomsk State University of Architecture and Building, 2, Solyanaya Sq., 634003, Tomsk (Russian Federation); Institute of Strength Physics and Materials Science, SB RAS, 2/4, Academicheskii Av., 634055, Tomsk (Russian Federation); Nikonenko, Elena, E-mail: vilatomsk@mail.ru [Tomsk State University of Architecture and Building, 2, Solyanaya Sq., 634003, Tomsk (Russian Federation); National Research Tomsk Polytechnic University, 30, Lenin Av., 634050, Tomsk (Russian Federation); Fedoricheva, Marina, E-mail: fed-mv@mail.ru [Institute of Strength Physics and Materials Science, SB RAS, 2/4, Academicheskii Av., 634055, Tomsk (Russian Federation); National Research Tomsk Polytechnic University, 30, Lenin Av., 634050, Tomsk (Russian Federation)

2016-01-15

This paper presents transmission and scanning electronic microscope investigations of Ni-Al-Cr superalloy alloyed with additional Re and La elements. This superalloy is obtained by the directional solidification method and subsequently is subjected to two-stage high-temperature annealing: 1) at T = 1150°C, the test time is 1 hour; 2) at T = 1100°C, the testing time is 1430 hours. It was found that the γ- and γ′-phases are the main phases in the two states on the basis of fcc lattice. Where γ is the disordered fcc solid solution and γ′-phase is the main phase with an ordered arrangement of atoms having the L1{sub 2} superstructure. It is shown that such additional elements as Re and La result in the formation of new phases in Ni-Al-Cr accompanied by considerable modifications of quasi-cuboid structure in its γ′-phase. The phase composition and morphology of the phases are studied.

Fabrication and characterization of dual-functional ultrafine composite fibers with phase-change energy storage and luminescence properties.

Science.gov (United States)

Xi, Peng; Zhao, Tianxiang; Xia, Lei; Shu, Dengkun; Ma, Menjiao; Cheng, Bowen

2017-01-09

Ultrafine composite fibers consisting of a thermoplastic polyurethane solid-solid phase-change material and organic lanthanide luminescent materials were prepared through a parallel electrospinning technique as an innovative type of ultrafine, dual-functional fibers containing phase-change and luminescent properties. The morphology and structure, thermal energy storage, and luminescent properties of parallel electrospun ultrafine fibers were investigated. Scanning electron microscopy (SEM) images showed that the parallel electrospun ultrafine fibers possessed the desired morphologies with smaller average fiber diameters than those of traditional mixed electrospun ultrafine fibers. Transmission electron microscopy (TEM) images revealed that the parallel electrospun ultrafine fibers were composed of two parts. Polymeric phase-change materials, which can be directly produced and spun, were used to provide temperature stability, while a mixture of polymethyl methacrylate and an organic lanthanide complex acted as the luminescent unit. Differential scanning calorimetry (DSC) and luminescence measurements indicated that the unique structure of the parallel electrospun ultrafine fibers provides the products with good thermal energy storage and luminescence properties. The fluorescence intensity and the phase-change enthalpy values of the ultrafine fibers prepared by parallel electrospinning were respectively 1.6 and 2.1 times those of ultrafine fibers prepared by mixed electrospinning.

A review of creep behavior of high temperature composites in relation to molybdenum disilicide composites

International Nuclear Information System (INIS)

Sadananda, K.; Feng, C.R.

1993-01-01

A brief review of creep behavior of composites is presented. It is shown that even for a two component system, creep of a composite depends on complex combination of several factors, including the constitutive behavior of the component phases at stress and temperature, and mechanical, chemical, diffusional and thermodynamic stability of the two-phase interfaces. The existing theoretical models based on continuum mechanics are presented. These models are evaluated using the extensive experimental data on molydisilicide--silicon carbide composites by the authors. The analysis shows that the rule of mixture based on isostrain and isostress provides two limiting bounds wherein all other predictions fall. For molydisilicide, the creep is predominantly governed by the creep of the majority phase, i.e. the matrix while fibers deform predominately elastically

Measurement of residual stress in plasma-sprayed composite coatings with graded and uniform compositions

Energy Technology Data Exchange (ETDEWEB)

Kesler, O.; Suresh, S. [Massachusetts Inst. of Tech., Cambridge, MA (United States); Matejicek, J.; Sampath, S.

1999-10-01

Residual stresses in plasma sprayed composite coatings were studied experimentally by both curvature and neutron diffraction measurements. Graded and uniform composite coatings, consisting of nickel + alumina and NiCrAlY + yttria-stabilized zirconia, were investigated. This paper briefly summarizes our recent work dealing with the effects of coating thickness, composition, and material properties on the evolution of residual stresses in coatings. Analysis of the results allowed in some cases the separation of the quenching stress and thermal stress contributions to the final residual stress, as well as the determination of the through-thickness stress profile from measurements of different thickness specimens. In the ceramic-metal composites, it was found that the thermal mismatch stress plays a dominant role in the ceramic phase, whereas the stress in the metallic phase is mostly dominated by quenching stress. The residual stress measurement methods employed here were found to be complementary, in that each can provide unique information about the stress state. Through-thickness stress profiles in graded coatings were determined with high spatial resolution by the curvature method, and determination of the stress in each separate phase of a composite was made by neutron diffraction. (orig.) 14 refs.

Preparation of fine powdered composite for latent heat storage

Energy Technology Data Exchange (ETDEWEB)

Fořt, Jan, E-mail: jan.fort.1@fsv.cvut.cz; Trník, Anton, E-mail: anton.trnik@fsv.cvut.cz; Pavlíková, Milena, E-mail: milena.pavlikova@fsv.cvut.cz; Pavlík, Zbyšek, E-mail: pavlikz@fsv.cvut.cz [Department of Materials Engineering and Chemistry, Faculty of Civil Engineering, Czech Technical University in Prague, Thákurova 7, 166 29 Prague (Czech Republic); Pomaleski, Marina, E-mail: marina-pomaleski@fsv.cvut.cz [Faculty of Civil Engineering, Architecture and Urbanism, University of Campinas, R. Saturnino de Brito 224, 13083-889 Campinas – SP (Brazil)

2016-07-07

Application of latent heat storage building envelope systems using phase-change materials represents an attractive method of storing thermal energy and has the advantages of high-energy storage density and the isothermal nature of the storage process. This study deals with a preparation of a new type of powdered phase change composite material for thermal energy storage. The idea of a composite is based upon the impregnation of a natural silicate material by a reasonably priced commercially produced pure phase change material and forming the homogenous composite powdered structure. For the preparation of the composite, vacuum impregnation method is used. The particle size distribution accessed by the laser diffraction apparatus proves that incorporation of the organic phase change material into the structure of inorganic siliceous pozzolana does not lead to the clustering of the particles. The compatibility of the prepared composite is characterized by the Fourier transformation infrared analysis (FTIR). Performed DSC analysis shows potential of the developed composite for thermal energy storage that can be easily incorporated into the cement-based matrix of building materials. Based on the obtained results, application of the developed phase change composite can be considered with a great promise.

Influence of composition on phase occurrence during charge process of AB5+x Ni-MH negative electrode materials

International Nuclear Information System (INIS)

Vivet, S.; Latroche, M.; Chabre, Y.; Joubert, J.-M.; Knosp, B.; Percheron-Guegan, A.

2005-01-01

Multi-substituted LaNi 5 -type alloys (AB 5+ x ) are widely used as negative electrode materials in commercial Ni-MH batteries. Cobalt substitution on Ni sites allows to enhance battery cycle life by reducing alloy pulverization induced by hydrogen cycling. This improvement is attributed to the occurrence of a three-phase process (α, β and γ) during electrochemical hydrogen loading. In order to better understand the effect of the composition on the phase occurrence and to reduce the rate of costly cobalt, an in situ neutron diffraction study has been performed at room temperature during electrochemical charge of two different electrode materials MmNi 4.07 Mn 0.63 Al 0.2 M 0.4 with M=Fe and Mn and B/A=5.3. These cobalt free compounds show cycle life comparable to that of commercial materials. The results show that three phases are also observed for these samples. The γ-phase content depends on M and is higher for M=Fe than for M=Mn. These results are related to the improved cycle lives and to the alloy pulverization process

A study of the oxidation of nickel-titanium intermetallics. II. Phase composition of the scale

Energy Technology Data Exchange (ETDEWEB)

Chuprina, V G [Institut Problem Materialovedeniia, Kiev (Ukrainian SSR)

1989-06-01

The phase composition of the scale formed on NiTi during oxidation in air in the temperature range 600-1000 C was investigated by X-ray diffraction and layer-by-layer metallographic analyses. The scale was found to contain NiO, NiO.TiO2, TiO2, Ti2O3, Ti3O5, Ni, and Ni(Ti) solid solution; an Ni3Ti sublayer was present at the scale-alloy boundary. Oxygen diffusion in the scale toward the sublayer and counterdiffusion of Ni(+2) were found to be the principal processes responsible for NiTi oxidation. 8 refs.

Micromechanical modelling of shape memory alloy composites

Energy Technology Data Exchange (ETDEWEB)

Wang, Y.F.; Wang, X.M.; Yue, Z.F. [School of Mechanic, Civil Engineering and Architecture, Northwestern Polytechnical University, Xian, 710072 (China)

2004-03-01

An isothermal finite element method (FEM) model has been applied to study the behavior of two kinds of shape memory alloy (SMA) composites. For SMA-fiber reinforced normal metal composites, the FEM analysis shows that the mechanical behavior of the composites depends on the SMA volume fraction. For normal metal-fiber reinforced SMA matrix composites, the SMA phase transformation is affected by the increasing Young's modulus of the metal fiber. The phase transformation was also treated using a simple numerical analysis, which assumes that there are uniform stresses and strains distributions in the fiber and the matrix respectively. It is found that there is an obvious difference between the FEM analysis and the simple numerical assessment. Only FEM can provide reasonable predictions of phase transformations in SMA/normal metal composites. (Abstract Copyright [2004], Wiley Periodicals, Inc.)

Preparation and properties studies of halogen-free flame retardant form-stable phase change materials based on paraffin/high density polyethylene composites

International Nuclear Information System (INIS)

Cai Yibing; Wei Qufu; Huang Fenglin; Gao Weidong

2008-01-01

The halogen-free flame retardant form-stable phase change materials (PCM) based on paraffin/high density polyethylene (HDPE) composites were prepared by using twin-screw extruder technique. The structures and properties of the form-stable PCM composites based on intumescent flame retardant system with expandable graphite (EG) and different synergistic additives, such as ammonium polyphosphate (APP) and zinc borate (ZB) were characterized by scanning electronic microscope (SEM), thermogravimetric analyses (TGA), dynamic Fourier-transform infrared (FTIR) spectra, differential scanning calorimeter (DSC) and Cone calorimeter test. The TGA results showed that the halogen-free flame retardant form-stable PCM composites produced a larger amount of charred residue at 700 deg. C, although the onset of weight loss of the halogen-free flame retardant form-stable PCM composites occurred at a lower temperature due to the thermal decomposition of flame retardant. The DSC measurements indicated that the additives of flame retardant had little effect on the thermal energy storage property, and the temperatures of phase change peaks and the latent heat of the paraffin showed better occurrence during the freezing process. The dynamic FTIR monitoring results revealed that the breakdowns of main chains (HDPE and paraffin) and formations of various residues increased with increasing thermo-oxidation temperature. It was also found from the Cone calorimeter tests that the peak of heat release rate (PHRR) decreased significantly. Both the decrease of the PHRR and the structure of charred residue after combustion indicated that there was a synergistic effect between the EG and APP, contributing to the improved flammability of the halogen-free flame retardant form-stable PCM composites

Measuring the noble metal and iodine composition of extracted noble metal phase from spent nuclear fuel using instrumental neutron activation analysis

International Nuclear Information System (INIS)

Palomares, R.I.; Dayman, K.J.; Landsberger, S.; Biegalski, S.R.; Soderquist, C.Z.; Casella, A.J.; Brady Raap, M.C.; Schwantes, J.M.

2015-01-01

Masses of noble metal and iodine nuclides in the metallic noble metal phase extracted from spent fuel are measured using instrumental neutron activation analysis. Nuclide presence is predicted using fission yield analysis, and radionuclides are identified and the masses quantified using neutron activation analysis. The nuclide compositions of noble metal phase derived from two dissolution methods, UO 2 fuel dissolved in nitric acid and UO 2 fuel dissolved in ammonium-carbonate and hydrogen-peroxide solution, are compared. - Highlights: • The noble metal phase was chemically extracted from spent nuclear fuel and analyzed non-destructively. • Noble metal phase nuclides and long-lived iodine were identified and quantified using neutron activation analysis. • Activation to shorter-lived radionuclides allowed rapid analysis of long-lived fission products in spent fuel using gamma spectrometry

Study of the formation of secondary phases in the composite LSM/YSZ; Estudo da formacao de fases secundarias no composito LSM/YSZ

Energy Technology Data Exchange (ETDEWEB)

Rodrigues, Ranieri Andrade

2007-07-01

The composite of strontium-doped lanthanum manganite (La{sub 1-x}SrxMnO{sub 3} - LSM) and Yttria-stabilized zirconia (ZrO{sub 2}/Y{sub 2}O{sub 3} - YSZ), is indicated as cathode of the Solid Oxide Fuel Cells (SOFC). It presents better acting as cathode due to the Triple Phase Boundary (TPB) formed in the interface area between the cathode and the electrolyte. For the temperatures up to 1100 deg C, LSM and YSZ can react producing lanthanum zirconate (La{sub 2}Zr{sub 2}O{sub 7} - LZO) and strontium zirconate (SrZrO{sub 3} - SZO). In this sense, the present work intends to contribute in the study of the formation of phases LZO and SZO, studying different massic proportions between LSM and YSZ with sintering temperatures varying between 1000 deg C and 1400 deg C. For the obtention of the precursory powders the co-precipitation routes were adopted to obtain YSZ and conventional powder mixture for the preparation of LSM. The composite LSM/YSZ, studied in this work, is prepared with two concentrations of Sr for LSM (30 mol por cent - LSM7 and 40 mol por cent - LSM6) and one concentration of Yttria for YSZ (10 mol por cent). The results obtained by X-ray fluorescence showed that the routes adopted for synthesis of powders were effective in the obtention of the compositions LSM6, LSM7 and YSZ, with close values to the stoichiometric. The studied massic proportions were: 50 por cent of LSM and 50 por cent of YSZ (1:1), 25 por cent of LSM and 75 por cent of YSZ (1:3), and 75 por cent of LSM and 25 por cent of YSZ (3:1). Such proportions of mixtures were conformed and submitted at different conditions of temperatures and times of sintering: 1000 deg C, 1200 deg C, 1300 deg C, 1350 deg C and 1400 deg C for 4 and 8 hours. The values of medium size of the particles and the specific surface area values for the mixture of LSM6/YSZ and LSM7/YSZ, are of the same order of largeness after the mixture in a attrition mill and in different massic proportions. Secondary phases like LZO and

Ionic Liquid Epoxy Composite Cryotanks, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — The objective of this work is to determine the optimal process for manufacturing lightweight linerless cryogenic storage tanks using ionic liquid epoxy composite...

Integrated Composite Rocket Nozzle Extension, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — ORBITEC proposes to develop and demonstrate an Integrated Composite Rocket Nozzle Extension (ICRNE) for use in rocket thrust chambers. The ICRNE will utilize an...

Phase composition and in vitro bioactivity of porous implants made of bioactive glass S53P4.

Science.gov (United States)

Fagerlund, S; Massera, J; Moritz, N; Hupa, L; Hupa, M

2012-07-01

This work studied the influence of sintering temperature on the phase composition, compression strength and in vitro properties of implants made of bioactive glass S53P4. The implants were sintered within the temperature range 600-1000°C. Over the whole temperature range studied, consolidation took place mainly via viscous flow sintering, even though there was partial surface crystallization. The mechanical strength of the implants was low but increased with the sintering temperature, from 0.7 MPa at 635°C to 10 MPa at 1000°C. Changes in the composition of simulated body fluid (SBF), the immersion solution, were evaluated by pH measurements and ion analysis using inductively coupled plasma optical emission spectrometry. The development of a calcium phosphate layer on the implant surfaces was verified using scanning electron microscopy-electron-dispersive X-ray analysis. When immersed in SBF, a calcium phosphate layer formed on all the samples, but the structure of this layer was affected by the surface crystalline phases. Hydroxyapatite formed more readily on amorphous and partially crystalline implants containing both primary Na(2)O·CaO·2SiO(2) and secondary Na(2)Ca(4)(PO(4))(2)SiO(4) crystals than on implants containing only primary crystals. Copyright © 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Damage growth in aerospace composites

CERN Document Server

2015-01-01

This book presents novel methods for the simulation of damage evolution in aerospace composites that will assist in predicting damage onset and growth and thus foster less conservative designs which realize the promised economic benefits of composite materials. The presented integrated numerical/experimental methodologies are capable of taking into account the presence of damage and its evolution in composite structures from the early phases of the design (conceptual design) through to the detailed finite element method analysis and verification phase. The book is based on the GARTEUR Research Project AG-32, which ran from 2007 to 2012, and documents the main results of that project. In addition, the state of the art in European projects on damage evolution in composites is reviewed. While the high specific strength and stiffness of composite materials make them suitable for aerospace structures, their sensitivity to damage means that designing with composites is a challenging task. The new approaches describ...

Recent Advances in Nb-silicide in-situ composites

International Nuclear Information System (INIS)

Bewlay, B.P.; Jackson, M.R.; Subramanian, P.R.; Briant, C.L.

2001-01-01

In-situ composites based on Nb silicides have great potential for future high-temperature applications. These Nb-silicide composites combine a ductile Nb-based matrix with high-strength silicides. With the appropriate combination of alloying elements, such as Ti, Hf, Cr, AI, it is possible to achieve a promising balance of fracture toughness, high-temperature creep performance, and oxidation resistance. This paper will describe the effect of volume fraction of silicide on microstructure, high-temperature creep performance, and oxidation resistance. The ratio of Nb:(W+Ti) is critical in determining both creep rate and oxidation performance. If this ratio goes below ∼1.5, the creep rate increases substantially. In more complex silicide-based systems, other intermetallics, such as laves phases and a boron-rich T-2 phase, are added for oxidation resistance. To understand the role of each phase on the creep resistance and oxidation performance of these composites, we determined the creep and oxidation behavior of the individual phases and composites at temperatures up to 1200 o C. These data allow quantification of the load-bearing capability of the individual phases in the Nb-silicide based in-situ composites. (author)

Lightweight, Composite Cryogenic Tank Structures, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — Microcosm has developed and qualified strong, all-composite LOX tanks for launch vehicles. Our new 42-inch diameter tank design weighs 486 lbs and burst without...

Energetic conditions of effective recycling of composite castings

OpenAIRE

J. Jackowski

2009-01-01

The most reasonable way of recycling the metal composite materials consists in separation of the components. In case of the composites with saturated reinforcement it is the only recycling method. The process of separation of the components always undergoes in the presence of an additional liquid phase called a recycling medium. In a three-phase system including the material of composite reinforcement – liquid composite matrix – liquid recycling medium, an important role for the recycling pro...

Heterogeneous coarsening of Pb phase and the effect of Cu addition on it in a nanophase composite of Al-10 wt%Pb alloy prepared by mechanical alloying

International Nuclear Information System (INIS)

Zhu, M.; Liu, X.; Wu, Z.F.; Ouyang, L.Z.; Zeng, M.Q.

2009-01-01

A nanophase composite of Al-10 wt%Pb alloy was prepared by mechanical alloying. The coarsening behavior of Pb phase in the composite during heating process was investigated by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and nanoindentation test. The present work shows that the Pb phase grew substantially and had two different size distributions when the heating temperature was above 823 K. The different size distributions of Pb phase were owing to different grain size ranges of Al matrix in different regions, which led to the different growth rates of the Pb phase in those regions. It has been proposed that the different size ranges of Al grain appeared upon heating were originated from a statistical size distribution of Al grains in the as-milled powder. With the addition of a small amount of Cu, the heterogeneous growth of Pb phase can be suppressed, and the coarsening of Pb phase shows two distinct rates. This indicates that the coarsening is mainly governed by grain boundary diffusion and lattice diffusion of Al matrix in the initial stage and the later one, respectively

Novel concept of recycling sludge and dust to BOF converter through dispersed in-situ phase induced by composite ball explosive reaction

Science.gov (United States)

Tang, Fu-ping; Yu, Shu-juan; Fei, Peng; Hou, Hou-yu; Qian, Feng; Wang, Xiao-feng

2017-08-01

Recycling of iron and steelmaking dusts is a key issue in environmental protection efforts and to ensure efficient utilization. In this investigation, we developed a novel recovery process that uses a dispersed in-situ phase induced by an explosive reaction of composite balls of iron and steelmaking dusts. We designed and prepared composite balls for this function using a laboratory model batch-type balling disc (at 12 r/min) and optimized the feeding modes in 180-t and 260-t basic oxygen furnace (BOF) converters. The results indicate that feeding composite balls into BOF converters is an effective novel technology for recovering iron and steelmaking dusts. The period after hot metal charging and prior to the oxygen-blowing process is the most reasonable time to feed composite balls. Composite ball treatment is not appropriate for steel production with sulfur requirements lower than 80 ppm. The maximum composite ball feeding amount is 40 kg/t and the iron yield rate is better than 95%. Compared with the conventional recycling process of sludge and dust, this novel technology is more convenient and efficient, saving up to 309 RMB per ton of steel. Further investigation of this novel recycling technology is merited.

Ferrous Ion and Medium Composition Effects on Acidogenic Phase in Biobutanol Production from Molasses

Science.gov (United States)

Restiawaty, E.; Grinanda, D.

2017-07-01

Clostridium acetobutylicum B530 has ability to convert sugar into biobutanol through two phases, i.e. acidogenic and solventogenic. This fermentation process is often hampered by high raw material cost and low product yield. In order to suppress the production cost, the molasses, a byproduct of sugar cane process production, was used as carbon source in this research. Molasses has nitrogen content in a small amount, thus could be negating the beef extract component, which is expected not to affect the growth of C. acetobutylicum B530 and also can reduce the production cost. In addition, a certain amount of Fe2+ (ferrous ion), a precursor in the formation of the enzyme ferredoxin, was added to the fermentation medium to contribute in the synthesis of acetyl-CoA, so that the formation of acidogenic products such as butyric acid and acetic acid is affected. This study aimed to investigate the effect of ferrous ion and the medium composition in acidogenic phase. The addition of 20 ppm FeSO4.7H2O in the fermentation medium without beef extract can increase the concentration of butyric acid by 20% at a temperature of 35°C, while acetic acid concentration decreased by 6%. According to those results, it is expected that the product selectivity of butanol will increase in solventogenic phase. In addition, the removal of beef extract in the fermentation medium does not affect the kinetics of growth of C. acetobutylicum B530.

Effect of beta phase composition and surface machining on the oxidation behavior of Zr-2.5Nb pressure tube material

International Nuclear Information System (INIS)

Nouduru, S.K.; Kiran Kumar, M.; Kain, V.; Khanna, A.S.

2015-01-01

Zr-2.5Nb is commonly used as the pressure tube material in pressurized heavy water reactors. it is also the pressure tube material for Advanced Heavy Water Reactor (AHWR) being developed indigenously in India with light water as coolant and water chemistry similar to Boiling Water Reactors (BWR). Oxidation of the pressure tube depends on various factors like material composition, microstructure, fabrication route, and water chemistry. In the present research, the role of the composition and morphology of second phase β on the high temperature and pressure oxidation behavior of Zr-2.5Nb pressure tube material in steam was systematically studied. The as-received pressure tube material (fabricated through cold worked and stress relieved, CWSR route) was subjected to selective heat treatments to generate microstructures containing predominantly β(Zr) (∼ 20% Nb) and β(Nb) (∼ 80% Nb) phases. The presence of such phases was characterized by X-ray diffraction and transmission electron microscopy-energy dispersive spectroscopy. Subsequently both the heat treated materials were subjected to surface machining. The Zr-2.5Nb material in different microstructural conditions was subjected to accelerated oxidation exposures in steam at 400 C. degrees, and 10 MPa pressure up to 30 days. Raman spectroscopy was carried out on the oxide surfaces to observe the variation in tetragonal versus monoclinic phase fractions with oxidation duration. The microstructure consisting of predominantly β(Nb) showed a relatively improved oxidation resistance as compared to the one with predominantly β(Zr). The tetragonal phase fraction in the oxide film decreased with oxidation time in all microstructural conditions and was found to be the least in the microstructure containing β(Zr) after 10 days of exposures. The explanation for the observed higher oxidation resistance of β(Nb) microstructure lies in the context of depleted matrix Nb content in the case of β(Nb). Surface machining

Compilation and Preliminary Analysis of Sensitivity Data for Pyrotechnics. Phase 1