WorldWideScience

Sample records for ceramic particle reinforcement

  1. Effect of sintering temperatures on titanium matrix composites reinforced by ceramic particles

    Energy Technology Data Exchange (ETDEWEB)

    Romero, F.; Amigo, V.; Busquets, D.; Klyatskina, E. [Mechanical and Materials Engineering Department. Polytechnical University of Valencia, Valencia (Spain)

    2005-07-01

    Titanium and titanium composites have a potential use in aerospace and biotechnology industries, and nowadays in others like sports and fashion ones. In this work composite materials, based on titanium matrix reinforced with ceramic particles, have been developed. PM route is used to obtain compact and sintered samples. TiN and TiAl powders, are milled with Ti powder in different volumetric percentages in a ball mill. These mixtures are pressed in a uniaxial press and sintered in a vacuum furnace at different temperatures between 1180 to 1220 deg. C. Porosity of samples is analysed, before and after the sintering process, by Archimedes technique and by image analysis. Mechanical properties and the reinforcement particles influence in the titanium matrix are studied by flexion test in green and sintered states, and by hardness and microhardness tests. Complimentarily, a microstructural analysis is carried out by optical and electron microscopy, and the reactivity between the reinforce particles and titanium matrix are studied. (authors)

  2. Mechanical behavior of Al-Mg-Si alloys reinforced with ceramic and intermetallic particles

    Energy Technology Data Exchange (ETDEWEB)

    Costa, C.E. da [Dept. de Ingenieria Mecanica y de Materiales, Univ. Politecnica de Valencia (Spain); Martinez, N.; Amigo, V.; Salvador, M.D. [Univ. do Estado de Santa Catarina, Centro de Ciencias Tecnologicas, Dept. Ingenieria Mecanica, Joinville (Brazil)

    2003-07-01

    Aluminum matrix composites (AMCs) reinforced with ceramic and Ti-Al intermetallic particles were prepared in the laboratory by following a powder metallurgy route. Hot extrusion was used as consolidation processes. Different studies were carried out in the composites developed. The influence of production process was also estimated. To evaluate interfaces and possible reaction products between the matrix and reinforcement, heat treatments regarding time were carried out. Tests were developed in fabricated AMCs and in unreinforced aluminum matrix, to evaluate influence of reinforcement type. In this study, optical and scanning electron microscopy with X-ray microanalysis, were used to determine the possible reaction products in the matrix/reinforcement interface and its composition. Ultimate strength and strain to failure were studied. There were performed tests at room temperature and at high temperature of the material in different precipitation state. The type of damage was analyzed by scanning electron microscopy. Ultimate strength trends to grow with reinforcement addition in both T1 and T6 conditions for low temperature. Strain to failure remains the lowest on T6 state. The effect of reinforcement addition decrease for high temperature testing and matrix influence was demonstrated. (orig.)

  3. Nanoscale Reinforced, Polymer Derived Ceramic Matrix Coatings

    Energy Technology Data Exchange (ETDEWEB)

    Rajendra Bordia

    2009-07-31

    The goal of this project was to explore and develop a novel class of nanoscale reinforced ceramic coatings for high temperature (600-1000 C) corrosion protection of metallic components in a coal-fired environment. It was focused on developing coatings that are easy to process and low cost. The approach was to use high-yield preceramic polymers loaded with nano-size fillers. The complex interplay of the particles in the polymer, their role in controlling shrinkage and phase evolution during thermal treatment, resulting densification and microstructural evolution, mechanical properties and effectiveness as corrosion protection coatings were investigated. Fe-and Ni-based alloys currently used in coal-fired environments do not possess the requisite corrosion and oxidation resistance for next generation of advanced power systems. One example of this is the power plants that use ultra supercritical steam as the working fluid. The increase in thermal efficiency of the plant and decrease in pollutant emissions are only possible by changing the properties of steam from supercritical to ultra supercritical. However, the conditions, 650 C and 34.5 MPa, are too severe and result in higher rate of corrosion due to higher metal temperatures. Coating the metallic components with ceramics that are resistant to corrosion, oxidation and erosion, is an economical and immediate solution to this problem. Good high temperature corrosion protection ceramic coatings for metallic structures must have a set of properties that are difficult to achieve using established processing techniques. The required properties include ease of coating complex shapes, low processing temperatures, thermal expansion match with metallic structures and good mechanical and chemical properties. Nanoscale reinforced composite coatings in which the matrix is derived from preceramic polymers have the potential to meet these requirements. The research was focused on developing suitable material systems and

  4. Fracture Toughness Prediction for MWCNT Reinforced Ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Henager, Charles H.; Nguyen, Ba Nghiep

    2013-09-01

    This report describes the development of a micromechanics model to predict fracture toughness of multiwall carbon nanotube (MWCNT) reinforced ceramic composites to guide future experimental work for this project. The modeling work described in this report includes (i) prediction of elastic properties, (ii) development of a mechanistic damage model accounting for matrix cracking to predict the composite nonlinear stress/strain response to tensile loading to failure, and (iii) application of this damage model in a modified boundary layer (MBL) analysis using ABAQUS to predict fracture toughness and crack resistance behavior (R-curves) for ceramic materials containing MWCNTs at various volume fractions.

  5. Development of ceramic-reinforced photopolymers for SLA 3D printing technology

    Science.gov (United States)

    Yun, Ji Sun; Park, Tae-Wan; Jeong, Young Hun; Cho, Jeong Ho

    2016-06-01

    Al2O3 ceramic-reinforced photopolymer samples for SLA 3D printing technology were prepared using a silane coupling agent (VTES, vinyltriethoxysilane). Depending on the method used to coat the VTES onto the ceramic surface, the dispersion of ceramic particles in the photopolymer solution was remarkably improved. SEM, TEM and element mapping images showed Al2O3 particles well wrapped with VTES along with well-distributed Al2O3 particles overall on the cross-sectional surfaces of 3D-printed objects. The tensile properties (stress-strain curves) of 3D-printed objects of the ceramic-reinforced photopolymer were investigated as a function of the Al2O3 ceramic content when it ranged from 0 to 20 wt%. The results demonstrate that an Al2O3 ceramic content of 15 wt% resulted in enhanced tensile characteristics.

  6. Corrosion resistance of the sintered composite materials with the EN AW-AlCu4Mg1(a alloy matrix reinforced with ceramic particles

    Directory of Open Access Journals (Sweden)

    A. Włodarczyk-Fligier

    2010-09-01

    Full Text Available Purpose: the aim of the project was to evaluate of the effect of heat treatment and the reinforcing Al2O3 and Ti(C,N particles content on the corrosion resistance in the NaCl water solution environment on the EN AW-AlCu4Mg1(A aluminium alloy matrix composite.Design/methodology/approach: Powders of the starting materials were wet mixed in the laboratory vibratory ball mill to obtain the uniform distribution of the reinforcement particles in the matrix. The mixed powders were then dried in the air. The components were initially compacted at cold state in a die with the diameter of Ø 26 mm in the laboratory vertical unidirectional press – with a capacity of 350 kN. The selected compacting load was sufficient to obtain prepregs which would not crumble and at the same time would not be deformed too much, which would also have the adverse effect on their quality, as the excessive air pressure in the closed pores causes breaking the prepreg up when it is taken out from the die. The obtained PM compacts were heated to a temperature of 480-500˚C and finally extruded – with the extrusion pressure of 500 kN. Some of the composite materials were hyperquenched for 0.5 h at the temperature of 495ºC with the subsequent cooling in water, and were quench aged next for 6 h at 200°C. Corrosion tests were made in 5% water NaCl solution.Findings: Composite materials were examined without heat treatment and after heat treatment carried out to improve their corrosion resistance. The corrosion susceptibility of the investigated composite materials determined using the potentiodynamic method in the 3% water solution of NaCl depends on the volume fraction of the reinforcing particles and also on the heat treatment status.Practical implications: Tested composite materials can be applicate among the others in automotive industry but it requires additional researches.Originality/value: It was demonstrated corrosion resistance of the extruded composite materials with

  7. Hollow sphere ceramic particles for abradable coatings

    International Nuclear Information System (INIS)

    A hollow sphere ceramic flame spray powder is disclosed. The desired constituents are first formed into agglomerated particles in a spray drier. Then the agglomerated particles are introduced into a plasma flame which is adjusted so that the particles collected are substantially hollow. The hollow sphere ceramic particles are suitable for flame spraying a porous and abradable coating. The hollow particles may be selected from the group consisting of zirconium oxide and magnesium zirconate

  8. Microstructure and mechanical behavior of 6061Al reinforced with silicon nitride particles, processed by powder metallurgy

    Energy Technology Data Exchange (ETDEWEB)

    Amigo, V.; Ortiz, J.L.; Salvador, M.D.

    2000-01-31

    A critical step in the processing of Metal Matrix Composites (MMCs) reinforced with ceramic particles is the insertion of these particles into the metal matrix alloy. This greatly influences the strength of the composite since it is controlled by the metal-particle interfacial bond strength. Because of the difficulty in wetting ceramic particles with molten metal, the Powder Metallurgy or PM route was developed. Powder Extrusion consolidates the composite to over 98% dense, and can be carried out below the Solidus Temperature of the alloy. The most important aspect of the microstructure is the distribution of the reinforcing particles, and this depends on the processing and fabrication routes involved, as well as the relative size of the matrix and reinforcing particles. Extrusion can homogenize the structure to some extent, but minimizing reinforcement inhomogeneity during initial processing is important to achieve optimum properties.

  9. Mechanical properties of silver matrix composites reinfroced with ceramic particles

    Directory of Open Access Journals (Sweden)

    J. Śleziona

    2006-04-01

    Full Text Available Purpose: Silver, silver alloys, as well as silver matrix based composites have been well known and applied in the electrotechnical and electronics industry for several decades. For many applications in electrotechnology, including electric contacts and brushes, unreinforced sliver alloys do not meet the requirements concerning mainly durability and wear resistance, first of all to tribological and electroerosive wear. These wear processes may be prevented by introducing to silver reinforcement particles and alloys. The target of the research included basic mechanical properties determination of the silver matrix composites reinforced with ceramic particles, manufactured with the use of suspension methods.Design/methodology/approach: In the presented paper the authors demonstrate possibilities of manufacturing of silver matrix composites on the way of casting technology utilization.Findings: The results of the research prove that applied suspension technology, based on introducing of agglomerated foundry alloy which is the carrier for reinforcement particles (SiC lub Al2O3 allows to produce in an effective and, what is important, in an economically attractive way, sliver alloys based composites.Research limitations/implications: The researches on the structure of manufactured composites and their mechanical properties that are presented in the paper prove the possibilities of mechanical mixing technology application for producing mechanical and stable connection between silver matrix and ceramic particles of aluminium oxide and silicon carbide.Originality/value: The manufacturing of this type of composites is based most of all on the utilization of powder metallurgy techniques. However the obtained results of the research prove that there is a possibility of silver matrix composites forming in the casting and plastic working processes. Extrusion process carried out in the hydraulic press KOBO has its favourably influence on ceramic reinforcement

  10. Processing and properties of pressable ceramic with non-uniform reinforcement for selective-toughening

    Energy Technology Data Exchange (ETDEWEB)

    Yi, Wei [School of Mechanical and Chemical Engineering, The University of Western Australia, Perth, WA 6009 (Australia); School of Dentistry, The University of Western Australia, WA 6009 (Australia); Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), Northeastern University, Shenyang 110004 (China); Hu, Xiaozhi, E-mail: xiao.zhi.hu@uwa.edu.au [School of Mechanical and Chemical Engineering, The University of Western Australia, Perth, WA 6009 (Australia); Ichim, Paul [School of Dentistry, The University of Western Australia, WA 6009 (Australia); Sun, Xudong [Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), Northeastern University, Shenyang 110004 (China)

    2012-12-15

    Brittle low-strength and low-toughness pressable dental ceramic can be reinforced by ductile elongated gold-particles (GP). A customized crown structure can be adequately strengthened by distributing GP only in critical sections of the crown, where high tensile stresses are experienced. In the present study, a non-uniformly structured ceramic-matrix composite with excellent interfacial bonding, twofold fracture toughness and strength at desired locations, is fabricated using pressable dental ceramic and GP. The layout pattern and sequence of different GP/ceramic powder mixtures, high-temperature flow properties of these mixtures during hot-pressing and the sample mold geometry are used to control the distribution and locations of GP for selective toughening and strengthening. Nano-crystalline structures of the pressable ceramic-matrix and the nano-scaled interfacial region around GP have been revealed by high-magnification field-emission scanning electron microscopy. Toughening and strengthening mechanisms of the elongated GP including residual stresses from composite processing and ductile fracture of GP are discussed together with SEM observations. Bulk flexural strength and local micro-indentation fracture and deformation characteristics of the selective-toughened ceramic/metal composite have been compared to those of the monolithic pressable ceramic to validate the toughening and strengthening mechanisms.

  11. Surface treatments for repair of feldspathic, leucite - and lithium disilicate-reinforced glass ceramics using composite resin.

    Science.gov (United States)

    Neis, Christian Alencar; Albuquerque, Nadine Luísa Guimarães; Albuquerque, Ivo de Souza; Gomes, Erica Alves; Souza-Filho, Celso Bernardo de; Feitosa, Victor Pinheiro; Spazzin, Aloisio Oro; Bacchi, Atais

    2015-01-01

    The aim of this study was to evaluate the efficacy of different surface conditioning methods on the microtensile bond strength of a restorative composite repair in three types of dental ceramics: lithium disilicate-reinforced, leucite-reinforced and feldspathic. Twelve blocks were sintered for each type of ceramic (n=3) and stored for 3 months in distilled water at 37 °C. The bonding surface of ceramics was abraded with 600-grit SiC paper. Surface treatments for each ceramic were: GC (control) - none; GDB - diamond bur #30 µm; GHF - hydrofluoric acid (10%); GT- tribochemical silica coating (45-μm size particles). Treatments were followed by cleaning with phosphoric acid 37% for 20 s + silane + adhesive. The composite resin was used as restorative material. After repair, samples were subjected to thermocycled ageing (10,000 cycles between 5 °C and 55 °C for 30 s). Thereafter, the samples were sectioned into 1.0 mm2 sticks and tested for microtensile bond strength with 0.5 mm/min crosshead speed. Data were compared by two-way ANOVA and Tukey's test (α=0.05). The superficial wear with diamond bur proved to be suitable for feldspathic porcelain and for leucite-reinforced glass ceramic while hydrofluoric acid-etching is indicated for repairs in lithium disilicate-reinforced ceramic; tribochemical silica coating is applicable to leucite-reinforced ceramic. Predominance of adhesive failures was observed (>85% in all groups). In conclusion, the success of surface treatments depends on the type of ceramic to be repaired.

  12. Rapid Prototyping of Continuous Fiber Reinforced Ceramic Matrix Composites

    Science.gov (United States)

    Vaidyanathan, R.; Green, C.; Phillips, T.; Cipriani, R.; Yarlagadda, S.; Gillespie, J. W., Jr.; Effinger, M.; Cooper, K. C.

    2003-01-01

    For ceramics to be used as structural components in high temperature applications, their fracture toughness is improved by embedding continuous ceramic fibers. Ceramic matrix composite (CMC) materials allow increasing the overall operating temperature, raising the temperature safety margins, avoiding the need for cooling, and improving the damping capacity, while reducing the weight at the same time. They also need to be reliable and available in large quantities as well. In this paper, an innovative rapid prototyping technique to fabricate continuous fiber reinforced ceramic matrix composites is described. The process is simple, robust and will be widely applicable to a number of high temperature material systems. This technique was originally developed at the University of Delaware Center for Composite Materials (UD-CCM) for rapid fabrication of polymer matrix composites by a technique called automated tow placement or ATP. The results of mechanical properties and microstructural characterization are presented, together with examples of complex shapes and parts. It is believed that the process will be able to create complex shaped parts at an order of magnitude lower cost than current chemical vapor infiltration (CVI) and polymer impregnation and pyrolysis (PIP) processes.

  13. Fabrication Routes for Continuous Fiber-Reinforced Ceramic Composites (CFCC)

    Science.gov (United States)

    DiCarlo, James A.; Bansal, Narottam P.

    1998-01-01

    The primary approaches used for fabrication of continuous fiber-reinforced ceramic composite (CFCC) components have been reviewed. The CFCC fabrication issues related to fiber, interface, and matrix have been analyzed. The capabilities, advantages and limitations of the five matrix-infiltration routes have been compared and discussed. Today, the best fabrication route for the CFCC end-user is not clear and compromises need to be made depending on the details of the CFCC application. However, with time, this problem should be reduced as research continues to develop advanced CFCC constituents and fabrication routes.

  14. Ceramics reinforced metal base composite coatings produced by CO II laser cladding

    Science.gov (United States)

    Yang, Xichen; Wang, Yu; Yang, Nan

    2008-03-01

    Due to the excellent performance in high strength, anti-temperature and anti-wear, ceramics reinforced metal base composite material was used in some important fields of aircraft, aerospace, automobile and defense. The traditional bulk metal base composite materials are the expensive cost, which is limited in its industrial application. Development of laser coating of ceramics reinforced metal base composite is very interesting in economy. This paper is focused on three laser cladding ceramics coatings of SiC particle /Al matrix , Al IIO 3 powder/ Al matrix and WC + Co/mild steel matrix. Powder particle sizes are of 10-60μm. Chemical contents of aluminum matrix are of 3.8-4.0% Cu, 1.2-1.8% Mg, 0.3-0.99% Mn and balance Al. 5KW CO II laser, 5 axes CNC table, JKF-6 type powder feeder and co-axis feeder nozzle are used in laser cladding. Microstructure and performance of laser composite coatings have been respectively examined with OM,SEM and X-ray diffraction. Its results are as follows : Microstructures of 3C-,6H- and 5H- SiC particles + Al + Al 4SiC 4 + Si in SiC/Al composite, hexagonal α-Al IIO 3 + cubic γ-Al IIO 3 + f.c.c Al in Al IIO 3 powder/ Al composite and original WC particles + separated WC particles + eutectic WC + γ-Co solid solution + W IIC particles in WC + Co/steel coatings are respectively recognized. New microstructures of 5H-SiC in SiC/Al composite, cubic γ-Al IIO 3 in Al IIO 3 composite and W IIC in WC + Co/ steel composite by laser cladding have been respectively observed.

  15. Bond strength durability of a resin composite on a reinforced ceramic using various repair systems

    NARCIS (Netherlands)

    Ozcan, Mutlu; Valandro, Luiz Felipe; Amaral, Regina; Leite, Fabiola; Bottino, Marco Antonio

    2009-01-01

    Objectives. This study compared the durability of repair bond strength of a resin composite to a reinforced ceramic after three repair systems. Methods. Alumina-reinforced feldspathic ceramic blocks (Vitadur-alpha(R)) (N=30) were randomly divided into three groups according to the repair method: PR-

  16. Seating load parameters impact on dental ceramic reinforcement conferred by cementation with resin-cements.

    LENUS (Irish Health Repository)

    Addison, Owen

    2010-09-01

    Cementation of all-ceramic restorations with resin-cements has been demonstrated to reduce the incidence of fracture in service. The aim was to investigate the influence of loading force and loading duration applied during cementation on the reinforcement conferred by a resin-cement on a leucite reinforced glass-ceramic.

  17. Processing and Material Characterization of Continuous Basalt Fiber Reinforced Ceramic Matrix Composites Using Polymer Derived Ceramics.

    Science.gov (United States)

    Cox, Sarah B.

    2014-01-01

    The need for high performance vehicles in the aerospace industry requires materials which can withstand high loads and high temperatures. New developments in launch pads and infrastructure must also be made to handle this intense environment with lightweight, reusable, structural materials. By using more functional materials, better performance can be seen in the launch environment, and launch vehicle designs which have not been previously used can be considered. The development of high temperature structural composite materials has been very limited due to the high cost of the materials and the processing needed. Polymer matrix composites can be used for temperatures up to 260C. Ceramics can take much higher temperatures, but they are difficult to produce and form in bulk volumes. Polymer Derived Ceramics (PDCs) begin as a polymer matrix, allowing a shape to be formed and cured and then to be pyrolized in order to obtain a ceramic with the associated thermal and mechanical properties. The use of basalt in structural and high temperature applications has been under development for over 50 years, yet there has been little published research on the incorporation of basalt fibers as a reinforcement in the composites. In this study, continuous basalt fiber reinforced PDCs have been fabricated and tested for the applicability of this composite system as a high temperature structural composite material. The oxyacetylene torch testing and three point bend testing have been performed on test panels and the test results are presented.

  18. Nano polypeptide particles reinforced polymer composite fibers.

    Science.gov (United States)

    Li, Jiashen; Li, Yi; Zhang, Jing; Li, Gang; Liu, Xuan; Li, Zhi; Liu, Xuqing; Han, Yanxia; Zhao, Zheng

    2015-02-25

    Because of the intensified competition of land resources for growing food and natural textile fibers, there is an urgent need to reuse and recycle the consumed/wasted natural fibers as regenerated green materials. Although polypeptide was extracted from wool by alkaline hydrolysis, the size of the polypeptide fragments could be reduced to nanoscale. The wool polypeptide particles were fragile and could be crushed down to nano size again and dispersed evenly among polymer matrix under melt extrusion condition. The nano polypeptide particles could reinforce antiultraviolet capability, moisture regain, and mechanical properties of the polymer-polypeptide composite fibers.

  19. Passive vibration damping of carbon fiber reinforced plastic with PZT particles and SMA powder

    Science.gov (United States)

    Jung, Jaemin; Lee, Woo Il; Lee, Dasom; Park, Sungho; Moon, Sungnam

    2016-04-01

    Carbon fiber reinforced plastic (CFRP) has been used various industrial fields, because of high strength, light weight, corrosion resistance and other properties. In this study, lead zirconate titanate (PZT) ceramic particles which is one of typical piezoelectric material and shape memory alloy powder dispersed in CFRP laminate in order to improve the vibration damping by dissipating vibration energy quickly. The loss factor (tanδ) is measured in Dynamic mechanical analyzer (DMA) which is used to measure the viscoelastic behavior of a material to verify the change in vibration damping. The results show that there exists difference on vibration damping ability between CFRP with PZT ceramic particles and CFRP with SMA powder.

  20. The Influence of the Particle Size on the Adhesion Between Ceramic Particles and Metal Matrix in MMC Composites

    Science.gov (United States)

    Jarzabek, Dariusz M.; Chmielewski, Marcin; Dulnik, Judyta; Strojny-Nedza, Agata

    2016-08-01

    This study investigated the influence of the particle size on the adhesion force between ceramic particles and metal matrix in ceramic-reinforced metal matrix composites. The Cu-Al2O3 composites with 5 vol.% of ceramic phase were prepared by a powder metallurgy process. Alumina oxide powder as an electrocorundum (Al2O3) powder with different particle sizes, i.e., fine powder powder of 180 µm was used as a reinforcement. Microstructural investigations included analyses using scanning electron microscopy with an integrated EDS microanalysis system and transmission microscopy. In order to measure the adhesion force (interface strength), we prepared the microwires made of the investigated materials and carried out the experiments with the use of the self-made tensile tester. We have observed that the interface strength is higher for the sample with coarse particles and is equal to 74 ± 4 MPa and it is equal to 68 ± 3 MPa for the sample with fine ceramic particles.

  1. Modeling oxidation damage of continuous fiber reinforced ceramic matrix composites

    Institute of Scientific and Technical Information of China (English)

    Cheng-Peng Yang; Gui-Qiong Jiao; Bo Wang

    2011-01-01

    For fiber reinforced ceramic matrix composites (CMCs), oxidation of the constituents is a very important damage type for high temperature applications. During the oxidizing process, the pyrolytic carbon interphase gradually recesses from the crack site in the axial direction of the fiber into the interior of the material. Carbon fiber usually presents notch-like or local neck-shrink oxidation phenomenon, causing strength degradation. But, the reason for SiC fiber degradation is the flaw growth mechanism on its surface. A micromechanical model based on the above mechanisms was established to simulate the mechanical properties of CMCs after high temperature oxidation. The statistic and shearlag theory were applied and the calculation expressions for retained tensile modulus and strength were deduced, respectively. Meanwhile, the interphase recession and fiber strength degradation were considered. And then, the model was validated by application to a C/SiC composite.

  2. In-situ Formation of Reinforcement Phases in Ultra High Temperature Ceramic Composites

    Science.gov (United States)

    Stackpoole, Margaret M (Inventor); Gasch, Matthew J (Inventor); Olson, Michael W (Inventor); Hamby, Ian W. (Inventor); Johnson, Sylvia M (Inventor)

    2013-01-01

    A tough ultra-high temperature ceramic (UHTC) composite comprises grains of UHTC matrix material, such as HfB.sub.2, ZrB.sub.2 or other metal boride, carbide, nitride, etc., surrounded by a uniform distribution of acicular high aspect ratio reinforcement ceramic rods or whiskers, such as of SiC, is formed from uniformly mixing a powder of the UHTC material and a pre-ceramic polymer selected to form the desired reinforcement species, then thermally consolidating the mixture by hot pressing. The acicular reinforcement rods may make up from 5 to 30 vol % of the resulting microstructure.

  3. Fire resistance properties of ceramic wool fiber reinforced intumescent coatings

    Energy Technology Data Exchange (ETDEWEB)

    Amir, N., E-mail: norlailiamir@petronas.com.my; Othman, W. M. S. W., E-mail: wamosa@gmail.com; Ahmad, F., E-mail: faizahmad@petronas.com.my [Mechanical Engineering Department, Universiti Teknologi PETRONAS Bandar Seri Iskandar, 31750 Tronoh, Perak (Malaysia)

    2015-07-22

    This research studied the effects of varied weight percentage and length of ceramic wool fiber (CWF) reinforcement to fire retardant performance of epoxy-based intumescent coating. Ten formulations were developed using ammonium polyphosphate (APP), expandable graphite (EG), melamine (MEL) and boric acid (BA). The mixing was conducted in two stages; powdered materials were grinded in Rocklabs mortar grinder and epoxy-mixed using Caframo mixer at low speed mixing. The samples were applied on mild steel substrate and exposed to 500°C heat inside Carbolite electric furnace. The char expansion and its physical properties were observed. Scanning electron microscopy (SEM) analyses were conducted to inspect the fiber dispersion, fiber condition and the cell structure of both coatings and chars produced. Thermogravimetric analyses (TGA) were conducted to study the thermal properties of the coating such as degradation temperature and residual weight. Fire retardant performance was determined by measuring backside temperature of substrate in 1-hour, 1000°C Bunsen burner test according to UL 1709 fire regime. The results showed that intumescent coating reinforced with CWF produced better fire resistance performance. When compared to unreinforced coating, formulation S6-15 significantly reduced steel temperature at approximately 34.7% to around 175°C. However, higher fiber weight percentage had slightly decreased fire retardant performance of the coating.

  4. Damage analysis of the ceramic reinforced steel matrix composites sheets: experimental and numerical study

    Directory of Open Access Journals (Sweden)

    E. Bayraktar

    2011-11-01

    Full Text Available Purpose: of this paper reports damage analysis of TiB2 (ceramic particles reinforced steel matrix composite sheets. This new steel composite receives much attention as potential structural materials due to their high specific strength and stiffness. The goal of the research described in this paper is to study the usage of this new steel family in the manufacture of light structures.Design/methodology/approach: therefore in this study is focused to the titanium diboride TiB2 reinforced steel matrix composite sheets that they were characterized by optical and scanning electron microscopes after the mechanical tests carried out on the base metal and welded specimens under dynamic and static test conditions.Findings: The non homogeneity of the structure in this type of composites makes deeply complexity of their numerical and analytical modelling to predict their damage during the loading. For example, the interfaces essentially play a key role in determining mechanical and physical properties. For this reason, a Finite Element (FEM analysis is used for modelling to simulate the macroscopic behaviour of this material, taking into account the relevant microscopic scales.Practical implications: defined in this research is based on the impact dynamic behaviour of this steel sheets by using a special impact tensile test developed formerly that all details were published in this journal. This type of test gives more comprehensible information about special steel sheets (welded or base metal in case of dynamic crash conditions.Originality/value: The present research gives detail information on the new steel matrix composite sheets reinforced TiB2 ceramic particles. This new composite was developed by ARCELOR research group and impact dynamic behaviour and weldability of the welded parts and base metals from this composite steel are discussed here in order to give practical and useful solution for industrial applications.

  5. Statistical Analysis of Reinforcement Characterization in SiC Particle Reinforced Al Matrix Composites

    Institute of Scientific and Technical Information of China (English)

    Peng Zhang; Fuguo Li

    2009-01-01

    The characterization of reinforcement in 15% SiC particles reinforced Al matrix composites processed by powder metallurgy route was studied by statistical method. During the analysis, a new approach for the estimation of the characterization of reinforcement was presented. The mathematic software MATLAB was used to calculate the area and perimeter of reinforcement, in which the image processing technique was applied. Based on the calculation, the fractal dimension, shape factor, reinforcement size distribution and reinforcement distribution were investigated. The results show that the reinforcement shape is similar to rectangle; the reinforcement size distribution is broad with the range of 1-12μm; the topography of reinforcement is smooth; and the reinforcement distribution is inhomogeneous. Furthermore, the cell model based on the statistical characterization was established and tested.

  6. Modeling and simulation of continuous fiber-reinforced ceramic composites

    Science.gov (United States)

    Bheemreddy, Venkata

    Finite element modeling framework based on cohesive damage modeling, constitutive material behavior using user-material subroutines, and extended finite element method (XFEM), are developed for studying the failure behavior of continuous fiber-reinforced ceramic matrix composites (CFCCs) by the example of a silicon carbide matrix reinforced with silicon carbide fiber (SiC/SiCf) composite. This work deals with developing comprehensive numerical models for three problems: (1) fiber/matrix interface debonding and fiber pull-out, (2) mechanical behavior of a CFCC using a representative volume element (RVE) approach, and (3) microstructure image-based modeling of a CFCC using object oriented finite element analysis (OOF). Load versus displacement behavior during a fiber pull-out event was investigated using a cohesive damage model and an artificial neural network model. Mechanical behavior of a CFCC was investigated using a statistically equivalent RVE. A three-step procedure was developed for generating a randomized fiber distribution. Elastic properties and damage behavior of a CFCC were analyzed using the developed RVE models. Scattering of strength distribution in CFCCs was taken into account using a Weibull probability law. A multi-scale modeling framework was developed for evaluating the fracture behavior of a CFCC as a function of microstructural attributes. A finite element mesh of the microstructure was generated using an OOF tool. XFEM was used to study crack propagation in the microstructure and the fracture behavior was analyzed. The work performed provides a valuable procedure for developing a multi-scale framework for comprehensive damage study of CFCCs.

  7. Structure and properties of ceramic preforms based on Al2O3 particles

    OpenAIRE

    L.A. Dobrzański; M. Kremzer; Nagel, A.

    2009-01-01

    Purpose: The main goal of this project is to elaborate and optimize the method of manufacturing the porous, ceramic preforms based on Al2O3 particles used as the reinforcement in order to produce modern metal matrix composites by pressure infiltration method with liquid metal alloys.Design/methodology/approach: Ceramic preforms were manufactured by the sintering method of Al2O3 powder with addition of pore forming agent. The preform material consists of powder Alcoa Al2O3 CL 2500, however, as...

  8. Colloidal processing of Fe-based metal ceramic composites with high content of ceramic reinforcement

    Energy Technology Data Exchange (ETDEWEB)

    Escribano, J. A.; Ferrari, B.; Alvaredo, P.; Gordo, E.; Sanchez-Herencia, A. J.

    2013-07-01

    Major difficulties of processing metal-matrix composites by means of conventional powder metallurgy techniques are the lack of dispersion of the phases within the final microstructure. In this work, processing through colloidal techniques of the Fe-based metal-matrix composites, with a high content of a ceramic reinforcement (Ti(C,N) ), is presented for the first time in the literature. The colloidal approach allows a higher control of the powders packing and a better homogenization of phases since powders are mixed in a liquid medium. The chemical stability of Fe in aqueous medium determines the dispersion conditions of the mixture. The Fe slurries were formulated by optimising their zeta potential and their rheology, in order to shape bulk pieces by slip-casting. Preliminary results demonstrate the viability of this procedure, also opening new paths to the microstructural design of fully sintered Fe-based hard metal, with 50 vol. % of Ti(C,N) in its composition. (Author)

  9. Colloidal processing of Fe-based metal ceramic composites with high content of ceramic reinforcement

    International Nuclear Information System (INIS)

    Major difficulties of processing metal-matrix composites by means of conventional powder metallurgy techniques are the lack of dispersion of the phases within the final microstructure. In this work, processing through colloidal techniques of the Fe-based metal-matrix composites, with a high content of a ceramic reinforcement (Ti(C,N) ), is presented for the first time in the literature. The colloidal approach allows a higher control of the powders packing and a better homogenization of phases since powders are mixed in a liquid medium. The chemical stability of Fe in aqueous medium determines the dispersion conditions of the mixture. The Fe slurries were formulated by optimising their zeta potential and their rheology, in order to shape bulk pieces by slip-casting. Preliminary results demonstrate the viability of this procedure, also opening new paths to the microstructural design of fully sintered Fe-based hard metal, with 50 vol. % of Ti(C,N) in its composition. (Author)

  10. Microtensile bond strength of a resin cement to glass infiltrated zirconia-reinforced ceramic : The effect of surface conditioning

    NARCIS (Netherlands)

    Amaral, R; Ozcan, M; Bottino, MA; Valandro, LF

    2006-01-01

    Objectives. This study evaluated the effect of three surface conditioning methods on the microtensile bond strength of resin cement to a glass-infiltrated zirconia-reinforced alumina-based core ceramic. Methods. Thirty blocks (5 x 5 x 4 mm) of In-Ceram Zirconia ceramics (In-Ceram Zirconia-INC-ZR, VI

  11. Bond strength of a resin cement to high-alumina and zirconia-reinforced ceramics: The effect of surface conditioning

    NARCIS (Netherlands)

    Valandro, L.F.; Ozcan, M.; Bottino, M.C.; Bottino, M.A.; Scotti, R.; Della Bona, A.

    2006-01-01

    Purpose: The aim of this study was to evaluate the effect of two surface conditioning methods on the microtensile bond strength of a resin cement to three high-strength core ceramics: high alumina-based (In-Ceram Alumina, Procera AllCeram) and zirconia-reinforced alumina-based (in-Ceram Zirconia) ce

  12. Bond strength of a resin cement to high-alumina and zirconia-reinforced ceramics : The effect of surface conditioning

    NARCIS (Netherlands)

    Felipe Valandro, Luiz; Ozcan, Mutlu; Bottino, Marco Cicero; Bottino, Marco Antonio; Scotti, Roberto; Della Bona, Alvaro

    2006-01-01

    Purpose: The aim of this study was to evaluate the effect of two surface conditioning methods on the microtensile bond strength of a resin cement to three high-strength core ceramics: high alumina-based (In-Ceram Alumina, Procera AllCeram) and zirconia-reinforced alumina-based (in-Ceram Zirconia) ce

  13. ECAP – New consolidation method for production of aluminium matrix composites with ceramic reinforcement

    Directory of Open Access Journals (Sweden)

    Mateja Šnajdar Musa

    2013-06-01

    Full Text Available Aluminium based metal matrix composites are rapidly developing group of materials due to their unique combination of properties that include low weight, elevated strength, improved wear and corrosion resistance and relatively good ductility. This combination of properties is a result of mixing two groups of materials with rather different properties with aluminium as ductile matrix and different oxides and carbides added as reinforcement. Al2O3, SiC and ZrO2 are the most popular choices of reinforcement material. One of the most common methods for producing this type of metal matrix composites is powder metallurgy since it has many variations and also is relatively low-cost method. Many different techniques of compacting aluminium and ceramic powders have been previously investigated. Among those techniques equal channel angular pressing (ECAP stands out due to its beneficial influence on the main problem that arises during powder compaction and that is a non-uniform distribution of reinforcement particles. This paper gives an overview on ECAP method principles, advantages and produced powder composite properties.

  14. Slip casting nano-particle powders for making transparent ceramics

    Science.gov (United States)

    Kuntz, Joshua D.; Soules, Thomas F.; Landingham, Richard Lee; Hollingsworth, Joel P.

    2011-04-12

    A method of making a transparent ceramic including the steps of providing nano-ceramic powders in a processed or unprocessed form, mixing the powders with de-ionized water, the step of mixing the powders with de-ionized water producing a slurry, sonifing the slurry to completely wet the powder and suspend the powder in the de-ionized water, separating very fine particles from the slurry, molding the slurry, and curing the slurry to produce the transparent ceramic.

  15. Spark plasma sintering of silicon carbide, multi-walled carbon nanotube and graphene reinforced zirconium diboride ceramic composite

    Science.gov (United States)

    Balaraman Yadhukulakrishnan, Govindaraajan

    Scope and Method of Study: Space vehicles re-entering the earth's atmosphere experience very high temperatures due to aerodynamic heating. Ultra-high temperature ceramics (UHTC) with melting point higher than 3200°C are promising materials for thermal protection systems of such space vehicles re-entering the earth's atmosphere. Among several UHTC systems ZrB2 based ceramic composites are particularly important for thermal protection systems due to their better mechanical and thermoelectric properties and high oxidation resistance. In this study spark plasma sintering of SiC, carbon nanotubes (CNT) and graphene nano platelets (GNP) reinforced ZrB2 ultra-high temperature ceramic matrix composites is reported. Findings and Conclusions: Systematic investigations on the effect of reinforcement type (SiC, CNTs and GNP) and content (10-40 vol.% SiC, 2-6 vol.% CNTs and 2-6 vol.% GNP) on densification behavior, microstructure development, and mechanical properties (microhardness, bi-axial flexural strength, and indentation fracture toughness) are reported. With the similar SPS parameters near-full densification (>99% relative density) was achieved with 10-40 vol.% SiC, 4-6 vol.% CNT reinforced composites. Highly dense composites were obtained in 4-6 vol.% GNP reinforced composites. The SiC, CNT and GNP reinforcement improved the indentation fracture toughness of the composites through a range of toughening mechanisms, including particle shearing, crack deflection at the particle-matrix interface, and grain pull-outs for ZrB2-SiC composites, CNT pull-outs and crack deflection in ZrB2-CNT composites and crack deflection, crack bridging and GNP sheet pull-out for ZrB2 -GNP composites.

  16. Joining of the AMC Composites Reinforced with Ti3Al Intermetallic Particles by Resistance Butt Welding

    Directory of Open Access Journals (Sweden)

    Adamiak M.

    2016-06-01

    Full Text Available The introduction of new reinforcing materials continues to be investigated to improve the final behaviour of AMCs as well as to avoid some drawbacks of using ceramics as reinforcement. The present work investigates the structure, properties and ability of joining aluminium EN-AW 6061 matrix composite materials reinforced with Ti3Al particles by resistance butt welding as well as composite materials produced by mechanical milling, powder metallurgy and hot extrusion techniques. Mechanically milled and extruded composites show finer and better distribution of reinforcement particles, which leads to better mechanical properties of the obtained products. Finer microstructure improves mechanical properties of obtained composites. The hardness increases twice in the case of mechanically milled composites also, a higher reinforcement content results in higher particle dispersion hardening, for 15 wt.% of intermetallics reinforcement concentration composites reach about 400 MPa UTS. Investigation results of joints show that best hardness and tensile properties of joints can be achieved by altering soft conditions of butt welding process e.g. current flow time 1.2 s and current 1400 A. To improve mechanical properties of butt welding joints age hardening techniques can also be used.

  17. Particle-induced amorphization complex ceramic

    Energy Technology Data Exchange (ETDEWEB)

    Ewing, R.C.; Wang, Lu-Min

    1996-02-16

    The presently funded three-year research program, supported by the Division of Materials Sciences of the Office of Basic Energy Sciences, was initiated on August 1, 1993; during the period in which the grant will have been active, $249,561 of support have been provided to date with an additional $79,723 to be spent during the third, final year (ending July 30, 1996). The primary purpose of the program is to develop an understanding of heavy-particle radiation effects -- {alpha}-recoil nuclei, fission fragments, ion-irradiations -- on ceramic materials and the thermal annealing mechanisms by which crystallinity might be restored. During the past two years, we have completed major studies on zircon (ZrSiO{sub 4}), olivine (Mg{sub 2}SiO{sub 4} and ten other compositions), spinel (MgAl{sub 2}O{sub 4} and four other compositions), and silica polymorphs (quartz, coesite and stishovite), as well as berlinite (AlPO{sub 4}) which is isomorphous with quartz. In addition, based on the above research, we propose the use of zircon as a host phase for the immobilization of plutonium resulting from weapons dismantlement.

  18. Elastic Property Simulation of Nano-particle Reinforced Composites

    Directory of Open Access Journals (Sweden)

    He Jiawei

    2016-01-01

    Full Text Available A series of numerical micro-mechanical models for two kinds of particle (cylindrical and discal particle reinforced composites are developed to investigate the effect of microstructural parameters on the elastic properties of composites. The effects of both the degree of particle clustering and particle’s shape on the elastic mechanical properties of composites are investigated. In addition, single particle unit cell approximation is good enough for the analysis of the effect of averaged parameters when only linear elastic response is considered without considering the particle clustering in particle-reinforced composites.

  19. Manufacturing of aluminium matrix composite materials reinforced by Al2O3 particles

    OpenAIRE

    A. Włodarczyk-Fligier; L.A. Dobrzański; M. Kremzer; M. Adamiak

    2008-01-01

    Purpose: The purpose of the paper is to show and compare of modern method composite materials with aluminium alloy matrix reinforced by Al2O3 particles manufacturing.Design/methodology/approach: Material for investigation was manufactured by two methods: powder metallurgy (consolidation, pressing, hot extrusion of powder mixtures of aluminium EN AW-AlCu4Mg1(A) and ceramic particles Al2O3) and pressure infiltration of porous performs by liquid alloy EN AC AlSi12 (performs were prepared by sint...

  20. Laser modification of ceramic surfaces with micro- and nano- particles

    Science.gov (United States)

    Rohde, Magnus

    2007-02-01

    Laser supported processes can be used to modify the electrical and thermal properties of ceramic substrates locally. These processes are characterised by a strong thermal interaction between the laser beam and the ceramic surface which leads to localised melting. During the dynamic melting process metal particles are introduced into the melt pool in order to modify the physical properties. Different alumina samples were treated with metal powders of tungsten, copper, and oxides of these metals. The interface between the metal and the ceramic can be designed by using selected combinations of metal- and metal-oxide-powders and also by a thermal post-processing. The application of nano-particles during the laser-dispersing process resulted in completely different characteristics of the micro-structure and the electrical properties compared to the conventional metal powders with an average grain size of 5 - 15 microns. The micron sized metal particles are embedded within the ceramic matrix as particle agglomerates or as distinct metal phase the nano-particle phase covers the grain boundaries of the ceramics leading to network of nano-scaled electrically conducting "wires". The resulting resistance of the laser tracks can be adjusted from semi-conducting to metallic behavior with a resistivity down to 2x10 -6W/m. The modified ceramic can be used for heating elements working at operation temperatures of up to 1000 °C, high current resistances which can be loaded with currents of up to 100 A.

  1. Chairside Fabrication of an All-Ceramic Partial Crown Using a Zirconia-Reinforced Lithium Silicate Ceramic.

    Science.gov (United States)

    Rinke, Sven; Pabel, Anne-Kathrin; Rödiger, Matthias; Ziebolz, Dirk

    2016-01-01

    The chairside fabrication of a monolithic partial crown using a zirconia-reinforced lithium silicate (ZLS) ceramic is described. The fully digitized model-free workflow in a dental practice is possible due to the use of a powder-free intraoral scanner and the computer-aided design/computer-assisted manufacturing (CAD/CAM) of the restorations. The innovative ZLS material offers a singular combination of fracture strength (>370 Mpa), optimum polishing characteristics, and excellent optical properties. Therefore, this ceramic is an interesting alternative material for monolithic restorations produced in a digital workflow. PMID:27042362

  2. Chairside Fabrication of an All-Ceramic Partial Crown Using a Zirconia-Reinforced Lithium Silicate Ceramic

    Directory of Open Access Journals (Sweden)

    Sven Rinke

    2016-01-01

    Full Text Available The chairside fabrication of a monolithic partial crown using a zirconia-reinforced lithium silicate (ZLS ceramic is described. The fully digitized model-free workflow in a dental practice is possible due to the use of a powder-free intraoral scanner and the computer-aided design/computer-assisted manufacturing (CAD/CAM of the restorations. The innovative ZLS material offers a singular combination of fracture strength (>370 Mpa, optimum polishing characteristics, and excellent optical properties. Therefore, this ceramic is an interesting alternative material for monolithic restorations produced in a digital workflow.

  3. Chairside Fabrication of an All-Ceramic Partial Crown Using a Zirconia-Reinforced Lithium Silicate Ceramic

    Science.gov (United States)

    Pabel, Anne-Kathrin; Rödiger, Matthias

    2016-01-01

    The chairside fabrication of a monolithic partial crown using a zirconia-reinforced lithium silicate (ZLS) ceramic is described. The fully digitized model-free workflow in a dental practice is possible due to the use of a powder-free intraoral scanner and the computer-aided design/computer-assisted manufacturing (CAD/CAM) of the restorations. The innovative ZLS material offers a singular combination of fracture strength (>370 Mpa), optimum polishing characteristics, and excellent optical properties. Therefore, this ceramic is an interesting alternative material for monolithic restorations produced in a digital workflow. PMID:27042362

  4. Fabrication of Zirconia-Reinforced Lithium Silicate Ceramic Restorations Using a Complete Digital Workflow

    Directory of Open Access Journals (Sweden)

    Sven Rinke

    2015-01-01

    Full Text Available This case report describes the fabrication of monolithic all-ceramic restorations using zirconia-reinforced lithium silicate (ZLS ceramics. The use of powder-free intraoral scanner, generative fabrication technology of the working model, and CAD/CAM of the restorations in the dental laboratory allows a completely digitized workflow. The newly introduced ZLS ceramics offer a unique combination of fracture strength (>420 MPa, excellent optical properties, and optimum polishing characteristics, thus making them an interesting material option for monolithic restorations in the digital workflow.

  5. Fabrication of Zirconia-Reinforced Lithium Silicate Ceramic Restorations Using a Complete Digital Workflow.

    Science.gov (United States)

    Rinke, Sven; Rödiger, Matthias; Ziebolz, Dirk; Schmidt, Anne-Kathrin

    2015-01-01

    This case report describes the fabrication of monolithic all-ceramic restorations using zirconia-reinforced lithium silicate (ZLS) ceramics. The use of powder-free intraoral scanner, generative fabrication technology of the working model, and CAD/CAM of the restorations in the dental laboratory allows a completely digitized workflow. The newly introduced ZLS ceramics offer a unique combination of fracture strength (>420 MPa), excellent optical properties, and optimum polishing characteristics, thus making them an interesting material option for monolithic restorations in the digital workflow. PMID:26509088

  6. Fabrication of Zirconia-Reinforced Lithium Silicate Ceramic Restorations Using a Complete Digital Workflow

    Science.gov (United States)

    Rinke, Sven; Rödiger, Matthias; Ziebolz, Dirk; Schmidt, Anne-Kathrin

    2015-01-01

    This case report describes the fabrication of monolithic all-ceramic restorations using zirconia-reinforced lithium silicate (ZLS) ceramics. The use of powder-free intraoral scanner, generative fabrication technology of the working model, and CAD/CAM of the restorations in the dental laboratory allows a completely digitized workflow. The newly introduced ZLS ceramics offer a unique combination of fracture strength (>420 MPa), excellent optical properties, and optimum polishing characteristics, thus making them an interesting material option for monolithic restorations in the digital workflow. PMID:26509088

  7. Identification of effective properties of particle reinforced composite materials

    OpenAIRE

    Kushnevsky, V.; Morachkovsky, O.; Altenbach, H.

    1998-01-01

    For the determination of effective elastic properties an energy averaging procedure has been used for particle reinforced composite materials. This procedure is based on finite element calculations of the deformation energy of a characteristic volume element. The proposed approach allows the determination of effective properties of particle reinforced composite with acceptable precision. The calculated effective properties of the composite are found in range between upper and lower Hashin-Sht...

  8. Chairside Fabrication of an All-Ceramic Partial Crown Using a Zirconia-Reinforced Lithium Silicate Ceramic

    OpenAIRE

    Sven Rinke; Anne-Kathrin Pabel; Matthias Rödiger; Dirk Ziebolz

    2016-01-01

    The chairside fabrication of a monolithic partial crown using a zirconia-reinforced lithium silicate (ZLS) ceramic is described. The fully digitized model-free workflow in a dental practice is possible due to the use of a powder-free intraoral scanner and the computer-aided design/computer-assisted manufacturing (CAD/CAM) of the restorations. The innovative ZLS material offers a singular combination of fracture strength (>370 Mpa), optimum polishing characteristics, and excellent optical prop...

  9. The influence of reinforcing particles on mechanical and tribological properties and microstructure of the steel-TiB2 composites

    OpenAIRE

    I. Sulima; L. Jaworska; P. Wyżga; M. Perek-Nowak

    2011-01-01

    Purpose: The present work aims to investigate the effect of the reinforcing ceramic particles on the mechanical and tribological properties and microstructure of the steel-TiB2 composites.Design/methodology/approach: The austenitic AISI316L stainless steel reinforced with 10 vol.% and 20 vol.% TiB2 particles was produced using the high temperature-high pressure (HT-HP) method. The sintering process was carried out at pressure of 7.0±0.2 GPa and temperature of 1200°C for 60 seconds. Density of...

  10. Repair bond strength of a resin composite to alumina-reinforced feldspathic ceramic

    NARCIS (Netherlands)

    Goia, Tamiye Simone; Pereira Leite, Fabiola Pessoa; Valandro, Luiz Felipe; Oezcan, Mutlu; Bottino, Marco Antonio

    2006-01-01

    This study compared the microtensile bond strength of a repair resin to an alumina-reinforced feldspathic ceramic (Vitadur-alpha, Vita) after 3 surface conditioning methods: Group 1, etching with 9.6% hydrofluoric acid for 1 minute plus rinsing and drying, followed by application of silane for 5 min

  11. Static And Dynamic Characteristics Of Waste Ceramic Aggregate Fibre Reinforced Concrete

    Directory of Open Access Journals (Sweden)

    Cichocki Krzysztof

    2015-12-01

    Full Text Available There are multiple obstacles associated both with technology and properties of waste ceramic aggregate concrete preventing its wide production and application. In the research programme these limitations were addressed through utilizing steel fibre reinforcement and the phenomenon of internal curing. After laboratory tests of mechanical properties a numerical analysis of composites in question was conducted.

  12. Fiber reinforced glasses and glass-ceramics for high performance applications

    Science.gov (United States)

    Prewo, K. M.; Brennan, J. J.; Layden, G. K.

    1986-01-01

    The development of fiber reinforced glass and glass-ceramic matrix composites is described. The general concepts involved in composite fabrication and resultant composite properties are given for a broad range of fiber and matrix combinations. It is shown that composite materials can be tailored to achieve high levels of toughness, strength, and elastic stiffness, as well as wear resistance and dimensional stability.

  13. Selected mechanical properties of aluminum composite materials reinforced with SiC particles

    Directory of Open Access Journals (Sweden)

    A. Kurzawa

    2008-07-01

    Full Text Available This work presents the results of research concerning influence of ceramic particles’ content of silicon carbide on selected mechanical properties of type AW-AlCu4Mg2Mn - SiC composite materials. Composites produced of SiC particles with pressure infiltration method of porous preform and subject to hot plastic forming in the form of open die forging were investigated. The experimental samples contained from 5% up to 45% of reinforcing SiC particles of 8÷10μm diameter. Studies of strength properties demonstrated that the best results, in case of tensile strength as well as offset yield strength, might be obtained while applying reinforcement in the amount of 20-25% vol. of SiC. Application of higher than 25% vol. contents of reinforcing particles leads to gradual strength loss. The investigated composites were characterized by very high functional properties, such as hardness and abrasive wear resistance, whose values increase strongly with the increase of reinforcement amount. The presented results of the experiments shall allow for a more precise component selection of composite materials at the stage of planning and design of their properties.

  14. Development of Ceramic Fibers for Reinforcement in Composite Materials

    Science.gov (United States)

    Gates, L. E.; Lent, W. E.; Teague, W. T.

    1961-01-01

    the. testing apparatus for single fiber tensile strength increased the precision. of tests conducted on nine fibers. The highest mean tensile strength, a value of 295,000 pounds per square inch, was obtained with R-141 fibers. Treatment of R-74 fibers with anhydrous Linde A-1100 silane finish improved its mean fiber tensile strength by 25 percent. The lapse of time after fiber formation had no measurable effect on tensile strength. A static heating test conducted with various high melting fibers indicated that Fiberfrax and R-108 underwent no significant changes in bulk volume or resiliency on exposure to 2750 degrees Fahrenheit (1510 degrees Centigrade) in an oxidizing atmosphere. For fiber-resin composition fabrication, ten fiber materials were selected on the bases of high fiber yield, fusion temperature, and type of composition. Fiberfrax, a commercial ceramic fiber, was included for comparison. A new, more effective method of removing pellets from blown fibers was developed. The de-pelletized fibers were treated with a silane finish and felted into ten-inch diameter felts prior to resin impregnation. Composites containing 30 percent by weight of CTL 91-LD phenolic resin were molded under high pressure from the impregnated felts and post-cured to achieve optimum properties. Flexural strength, flexural modules of elasticity, and punch shear strength tests were conducted on the composite specimens. The highest average flexural strength obtained was 19,958 pounds per square inch with the R-74-fiber-resin composite. This compares very favorably with the military specification of 13,000 pounds per square inch flexural strength for randomly oriented fiber reinforced composites. The highest punch shear strength (11,509 pounds per square inch) was obtained with the R-89 fiber-resin composite. The effects of anhydrous fiber finishes on composite strength were not clearly indicated. Plasma arc tests at a heat flux of 550 British Thermal Units per square foot per second on

  15. Ensuring near-optimum homogeneity and densification levels in nano-reinforced ceramics

    Science.gov (United States)

    Dassios, Konstantinos G.; Barkoula, Nektaria-Marianthi; Alafogianni, Panagiota; Bonnefont, Guillaume; Fantozzi, Gilbert; Matikas, Theodore E.

    2016-04-01

    The development of a new generation of high temperature ceramic materials for aerospace applications, reinforced at a scale closer to the molecular level and three orders of magnitude less than conventional fibrous reinforcements, by embedded carbon nanotubes, has recently emerged as a uniquely challenging scientific effort. The properties of such materials depend strongly on two main factors: i) the homogeneity of the dispersion of the hydrophobic medium throughout the ceramic volume and ii) the ultimate density of the resultant product after sintering of the green body at the high-temperatures and pressures required for ceramic consolidation. The present works reports the establishment of two independent experimental strategies which ensure achievement of near perfect levels of tube dispersion homogeneity and fully dense final products. The proposed methodologies are validated across non-destructive evaluation data of materials performance.

  16. Mechanical behavior and properties of fiber reinforced ceramic matrix composites for high temperature use

    Institute of Scientific and Technical Information of China (English)

    Chongdu Cho; Qiang Pan; Sangkyo Lee

    2007-01-01

    Ceramics can keep their mechanical characteristics up to 2 000℃ or higher.In this paper,A model to predict ultimate strength of continuous fiber-reinforced brittle matrix composites is developed.A statistical theory for the strength of a uni-axially fiber-reinforced brittle matrix composite is presented.Also a semi-empirical frictional heating method for estimating in-situ interfacial shear in fiber-reinforced ceramic matrix composites was improved.Local uneven fiber packing variation as well as uneven micro-damage during fatigue can be expected to have effects on the composites:generation of frictional heating,thermal gradients,and residual stresses around local fiber breaks.This study examined those engineering interests by the finite element method.

  17. 晶须与颗粒混合增强陶瓷基复合材料的相平均应力及微区应力分布特征分析%ANALYSIS OF PHASE AVERAGE STRESSES AND THE DISTRIBUTION FEATURES OF LOCAL-STRESS ON THE HYBRID CERAMIC COMPOSITES REINFORCED WITH WHISKERS AND PARTICLE

    Institute of Scientific and Technical Information of China (English)

    罗冬梅; 汪文学; 周应龙

    2013-01-01

    The distribution features of local-stress for ceramic composites reinforced by the whiskers and panicle with different mechanical properties are simulated by the 3-dimensional finite element method ( FEM) ( MSC-MARC) , and the phase average stresses are calculated. For the purpose of comparison, a theoretical formula (effective Mori-Tanaka theory, EMT) combining the Eshelby' s theory with Mori-Tanaka method is derived to calculate the phase average stress. The results show that the phase average stresses obtained by EMT are in good agreement with those by FEM, and there is an obvious difference to share the average stress among reinforcements with different shapes and different mechanical properties. The whiskers are prior to the spherical particles to bear high stress, and to decrease the stress in the matrix, and to improve the strength of multi-phase hybrid ceramic composites. The results from FEM also show the influences of the change of positions, and the change of elastic modulus for whiskers on the distribution features of local stress, and it is beneficial to make a failure analysis for multi-phase hybrid ceramic composites. The spherical particles are effective to improve the distribution of local stress by adjusting the positions of the whiskers.%采用三维有限元法在MSC-MARC软件中模拟不同性质的晶须和颗粒混合增强陶瓷基复合材料时微区应力分布特征,并计算增强相及基体平均应力.结合Eshelby夹杂理论和Mori-Tanaka方法推导增强相及基体的平均应力的理论公式,将两种方法所得的结果进行比较.结果表明,理论模型与有限元法得到的各相平均应力非常吻合,不同形状的增强相分担的应力差异很大,晶须增强相能够分担大部分的平均应力,对降低基体应力、提高多相混合增强陶瓷基复合材料的强度起主要作用.数值模拟结果同时给出微区应力场分布特征,显示晶须位置变化和晶须弹性模量变化对微区

  18. Recent advances in understanding the reinforcing ability and mechanism of carbon nanotubes in ceramic matrix composites

    International Nuclear Information System (INIS)

    Since the discovery of carbon nanotubes (CNTs), commonly referred to as ultimate reinforcement, the main purpose for fabricating CNT–ceramic matrix composites has been mainly to improve the fracture toughness and strength of the ceramic matrix materials. However, there have been many studies reporting marginal improvements or even the degradation of mechanical properties. On the other hand, those studies claiming noticeable toughening measured using indentation, which is an indirect/unreliable characterization method, have not demonstrated the responsible mechanisms applicable to the nanoscale, flexible CNTs; instead, those studies proposed those classical methods applicable to microscale fiber/whisker reinforced ceramics without showing any convincing evidence of load transfer to the CNTs. Therefore, the ability of CNTs to directly improve the macroscopic mechanical properties of structural ceramics has been strongly questioned and debated in the last ten years. In order to properly discuss the reinforcing ability (and possible mechanisms) of CNTs in a ceramic host material, there are three fundamental questions to our knowledge at both the nanoscale and macroscale levels that need to be addressed: (1) does the intrinsic load-bearing ability of CNTs change when embedded in a ceramic host matrix?; (2) when there is an intimate atomic-level interface without any chemical reaction with the matrix, could one expect any load transfer to the CNTs along with effective load bearing by them during crack propagation?; and (3) considering their nanometer-scale dimensions, flexibility and radial softness, are the CNTs able to improve the mechanical properties of the host ceramic matrix at the macroscale when individually, intimately and uniformly dispersed? If so, how? Also, what is the effect of CNT concentration in such a defect-free composite system? Here, we briefly review the recent studies addressing the above fundamental questions. In particular, we discuss the new

  19. Recent advances in understanding the reinforcing ability and mechanism of carbon nanotubes in ceramic matrix composites

    Science.gov (United States)

    Estili, Mehdi; Sakka, Yoshio

    2014-12-01

    Since the discovery of carbon nanotubes (CNTs), commonly referred to as ultimate reinforcement, the main purpose for fabricating CNT-ceramic matrix composites has been mainly to improve the fracture toughness and strength of the ceramic matrix materials. However, there have been many studies reporting marginal improvements or even the degradation of mechanical properties. On the other hand, those studies claiming noticeable toughening measured using indentation, which is an indirect/unreliable characterization method, have not demonstrated the responsible mechanisms applicable to the nanoscale, flexible CNTs; instead, those studies proposed those classical methods applicable to microscale fiber/whisker reinforced ceramics without showing any convincing evidence of load transfer to the CNTs. Therefore, the ability of CNTs to directly improve the macroscopic mechanical properties of structural ceramics has been strongly questioned and debated in the last ten years. In order to properly discuss the reinforcing ability (and possible mechanisms) of CNTs in a ceramic host material, there are three fundamental questions to our knowledge at both the nanoscale and macroscale levels that need to be addressed: (1) does the intrinsic load-bearing ability of CNTs change when embedded in a ceramic host matrix?; (2) when there is an intimate atomic-level interface without any chemical reaction with the matrix, could one expect any load transfer to the CNTs along with effective load bearing by them during crack propagation?; and (3) considering their nanometer-scale dimensions, flexibility and radial softness, are the CNTs able to improve the mechanical properties of the host ceramic matrix at the macroscale when individually, intimately and uniformly dispersed? If so, how? Also, what is the effect of CNT concentration in such a defect-free composite system? Here, we briefly review the recent studies addressing the above fundamental questions. In particular, we discuss the new

  20. Mechanical Reinforcement and Piezoelectric Properties of PZT Ceramics Embedded with Nano-Crystalline

    International Nuclear Information System (INIS)

    The double-scale lead zirconate titanate (PZT) piezoelectric ceramics were prepared by the solid state processing with PZT nano-crystalline and micro-powder. The microstructures, electrical and mechanical properties of the double-scale PZT are investigated. All the sintered ceramics exhibit a single perovskite structure and the grain size of the double-scale PZT reduces due to the incorporation of PZT nano-crystalline. Compared to normal PZT, the mechanical properties increase significantly and the piezoelectric properties decrease slightly. Mechanisms responsible for the reinforcement of the double-scale PZT are discussed

  1. Colloidal processing of Fe-based metalceramic composites with high content of ceramic reinforcement

    OpenAIRE

    Escribano, J.A.; Ferrari, Begoña; Alvaredo Olmos, Paula; Gordo Odériz, Elena; Sánchez-Herencia, A. J.

    2013-01-01

    Major difficulties of processing metal-matrix composites by means of conventional powder metallurgy techniques are the lack of dispersion of the phases within the final microstructure. In this work, processing through colloidal techniques of the Fe-based metal-matrix composites, with a high content of a ceramic reinforcement (Ti(C,N) ), is presented for the first time in the literature. The colloidal approach allows a higher control of the powders packing and a better homogenization of phases...

  2. Approach to microstructure-behavior relationships for ceramic matrix composites reinforced by continuous fibers

    OpenAIRE

    Lamon Jacques

    2015-01-01

    Ceramic matrix composites (CMCs) reinforced with continuous fibers exhibit several features that differentiate them from homogeneous unreinforced materials. The microstructure consists of various distinct constituents: fibres, matrix, and fiber/matrix interfaces or interphases. Several entities at micro- and mesoscopic length scales can be defined depending on fiber arrangement. Furthermore, the CMCs contain flaw populations that govern matrix cracking and fiber failures. The paper describes ...

  3. Low Cost Fabrication of Silicon Carbide Based Ceramics and Fiber Reinforced Composites

    Science.gov (United States)

    Singh, M.; Levine, S. R.

    1995-01-01

    A low cost processing technique called reaction forming for the fabrication of near-net and complex shaped components of silicon carbide based ceramics and composites is presented. This process consists of the production of a microporous carbon preform and subsequent infiltration with liquid silicon or silicon-refractory metal alloys. The microporous preforms are made by the pyrolysis of a polymerized resin mixture with very good control of pore volume and pore size thereby yielding materials with tailorable microstructure and composition. Mechanical properties (elastic modulus, flexural strength, and fracture toughness) of reaction-formed silicon carbide ceramics are presented. This processing approach is suitable for various kinds of reinforcements such as whiskers, particulates, fibers (tows, weaves, and filaments), and 3-D architectures. This approach has also been used to fabricate continuous silicon carbide fiber reinforced ceramic composites (CFCC's) with silicon carbide based matrices. Strong and tough composites with tailorable matrix microstructure and composition have been obtained. Microstructure and thermomechanical properties of a silicon carbide (SCS-6) fiber reinforced reaction-formed silicon carbide matrix composites are discussed.

  4. PARTICULATE SIZE EFFECTS IN THE PARTICLE-REINFORCED METAL-MATRIX COMPOSITES

    Institute of Scientific and Technical Information of China (English)

    魏悦广

    2001-01-01

    The influences of particle size on the mechanical properties of the particulate metal matrix composite are obviously displayed in the experimental observations. However, the phenomenon can not be predicted directly using the conventional elastic-plastic theory. It is because that no length scale parameters are involved in the conventional theory. In the present research, using the strain gradient plasticity theory, a systematic research of the particle size effect in the particulate metal matrix composite is carried out. The roles of many composite factors, such as: the particle size, the Young's modulus of the particle, the particle aspect ratio and volume fraction, as well as the plastic strain hardening exponent of the matrix material,are studied in detail. In order to obtain a general understanding for the composite behavior, two kinds of particle shapes, ellipsoid and cylinder, are considered to check the strength dependence of the smooth or non-smooth particle surface. Finally,the prediction results will be applied to the several experiments about the ceramic particle-reinforced metal-matrix composites. The material length scale parameter is predicted.

  5. 颗粒补强Al2O3/SiC/(W,Ti)C复相陶瓷刀具材料的氧化行为与强度特性%OXIDATION BEHAVIOR AND STRENGTH CHARACTERISTICS OF PARTICLE REINFORCED Al2O3/SiC/(W, Ti)C COMPOSITE CERAMIC TOOL MATERIALS

    Institute of Scientific and Technical Information of China (English)

    许崇海; 黄传真; 邓建新; 艾兴

    2001-01-01

    研究了颗粒补强Al2O3/SiC(W,Ti)C复相陶瓷刀具材料的氧化行为及其对材料抗弯强度的影响,结果表明:该材料在空气中静态氧化时的氧化增重符合抛物线规律随弥散相SiC和(W,Ti)C的增加,其氧化活化能有不同程度的降低.由于SiC的添加,使得氧化膜在高温下能以粘性流动的方式缓解残余应力,降低氧化速度,从而使得材料的抗氧化性能有所提高.此外,适当的氧化处理可使Al2O3/SiC/(W,Ti)C陶瓷刀具材料的抗弯强度得到提高.%Oxidation behavior of the particle reinforced Al2O3/SiC/(W, Ti)C composite ceramic tool materials has been studied in detail, as well as the effect of the oxidation on the flexural strength of the material. It is shown that the weight gains in the static oxidation of the material under air atmosphere obey the parabolic law. The energy of activation of the material decreases with the increase in the content of SiC and (W, Ti)C. Residual stresses in the oxidation film can be released with the form of the viscous flowing at high temperature. Therefore, the speed of the oxidation is lowered, and then the oxidation resistance of the material can be enhanced to some extent. It is found that the appropriate oxidation is effective for the improvement of the flexural strength of Al2O3/SiC/(W, Ti)C ceramic tool material.

  6. Wetting in Al composites reinforced with SiC particles

    OpenAIRE

    A.C. Vieira; Rocha, L A; Gomes, J. R.

    2006-01-01

    Aluminium matrix composites have been wide used essentially due to the good relation between weight and mechanical resistance. To develop a ceramic particle/matrix interface with good characteristics, it is essential to control the interface reactivity, avoiding the formation of undesirable reaction products such as Al4C3. Essentially, there are three methods to prevent the Al4C3 formation: Si addition to Al matrix, coating of the SiC particles and to promote a passive oxidation of SiC pa...

  7. Particle size and particle-particle interactions on tensile properties and reinforcement of corn flour particles in natural rubber

    Science.gov (United States)

    Renewable corn flour has a significant reinforcement effect in natural rubber. The corn flour was hydrolyzed and microfluidized to reduce its particle size. Greater than 90% of the hydrolyzed corn flour had an average size of ~300 nm, a reduction of 33 times compared to unhydrolyzed corn flour. Comp...

  8. Microstructure, properties and application of YAl2 intermetallic compound as particle reinforcements

    International Nuclear Information System (INIS)

    An yttrium aluminum (YAl2) intermetallic compound ingot was prepared in an induction furnace under vacuum. The microstructure of YAl2 ingot was characterized by optical microscopy, scanning electron microscopy, and X-ray diffraction. The load bearing response of YAl2 intermetallic was investigated and compared with SiC ceramic by indentation combined with optical microscopy and scanning electron microscopy. Additionally, the tensile properties of the Mg–Li matrix composites reinforced with ultrafine YAl2 particles fabricated by planet ball milling were tested. The results show that the intermetallic compound ingot in this experiment is composed of a main face-centered-cubic structure YAl2 phase, a small amount of YAl phase, and minor Y and Al-rich phases. YAl2 intermetallic compound has excellent stability and shows better capability in crack resistance than SiC ceramic. The YAl2 intermetallic compound has better deformation compatibility with the Mg–14Li–3Al matrix than SiC reinforcement with the matrix, which leads to the superior resistance to crack for YAl2p/Mg–14Li–3Al composite compared to SiCp/Mg–14Li–3Al composite

  9. Laser cladding in-situ carbide particle reinforced Fe-based composite coatings with rare earth oxide addition

    Institute of Scientific and Technical Information of China (English)

    吴朝锋; 马明星; 刘文今; 钟敏霖; 张红军; 张伟明

    2009-01-01

    Particulate reinforced metal matrix composite(PR-MMC) has excellent properties such as good wear resistance,corrosion resistance and high temperature properties.Laser cladding is usually used to form PR-MMC on metal surface with various volume fractions of ceramic particles.Recent literatures showed that laser melting of powder mixture containing carbon and carbide-forming elements,was favorable for the formation of in-situ synthesized carbide particles.In this paper,rare earth oxide(RE2O3) was added into t...

  10. Reinforcing and toughening alumina/titania ceramic composites with nano-dopants from nanostructured composite powders

    International Nuclear Information System (INIS)

    Nanostructured alumina/titania composite powders were prepared using nanosized alumina and titania doped with nanosized zirconia and ceria through ball-milling, spray drying and heat treating. The nanostructured reconstituted powders were then cool isostatic pressed and pressureless sintered into bulk ceramic composites. The phase constitution and microstructures of as-prepared ceramic composites were characterized by using X-ray diffractometer and scanning electron microscope. The mechanical properties of the ceramic composites were evaluated by Vickers hardness test, flexural strength test and fracture toughness test. The effects of nano-dopants and sintering temperatures on the microstructures and mechanical properties of the composites were investigated. It was found that nano-dopants had the effects of lowering sintering temperature, accelerating densification, reinforcing and toughening the composites. The maximum flexural strength, fracture toughness and Vickers hardness of the composites with nano-dopants were 51, 20 and 56% higher than that of the composites without nano-dopants. The reinforcing and toughening mechanisms are discussed in detail.

  11. Processing and Characterization of Basalt Fiber Reinforced Ceramic Composites for High Temperature Applications Using Polymer Precursors

    Science.gov (United States)

    Cox, Sarah B.; Lui, Donovan; Gou, Jihua

    2014-01-01

    The development of high temperature structural composite materials has been very limited due to the high cost of the materials and the processing needed. Ceramics can take much higher temperatures, but they are difficult to produce and form in bulk volumes. Polymer Derived Ceramics (PDCs) begin as a polymer matrix, allowing a shape to be formed and cured and then to be pyrolized in order to obtain a ceramic with the associated thermal and mechanical properties. The two PDCs used in this development are polysiloxane and polycarbosilane. Polysiloxanes contain a silicon oxycarbide backbone when pyrolized up to 1000C. Polycarbosilane, an organosilicon polymer, contain a silicon-carbon backbone; around 1200C, beta-SiC begins to crystallize. The use of basalt in structural and high temperature applications has been under development for over 50 years, yet there has been little published research on the incorporation of basalt fibers as a reinforcement in composites. Basalt is a naturally occurring material found in volcanic rock. Continuous basalt fiber reinforced PDCs have been fabricated and tested for the applicability of this composite system as a high temperature structural composite material. Thermal and mechanical testing includes oxyacetylene torch testing and three point bend testing.

  12. Endocrown with Leucite-Reinforced Ceramic: Case of Restoration of Endodontically Treated Teeth

    Directory of Open Access Journals (Sweden)

    Leonardo Fernandes da Cunha

    2015-01-01

    Full Text Available A common problem encountered by dentists is the restorative treatment of nonvital teeth. When the pulp chamber presents appropriate conditions for retention, the endocrown is indicated. This monolithic, ceramic adhesive restoration is singularly used yet warrants wider recognition and use. The endocrown allows preservation of the tooth structure and is minimally invasive. Currently, this treatment option, of a core buildup and full coverage restoration, reduces tooth structure excessively. This treatment presents not only functional limitations but also aesthetic concerns. Recently, the VITA-PM9 system, a leucite-reinforced glass ceramic, has been increasingly used in a variety of clinical situations due to its satisfactory physical-mechanical and aesthetic properties. Therefore, the present study describes a case of surgical restoration of a nonvital tooth using the endocrown technique and the VITA-PM9.

  13. Recent trend and problems of whisker reinforced composite ceramics. Whisker fukugo ceramics no genjo to kadai

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Wonseung; Hayashi, K. (The Univ. of Tokyo, Tokyo (Japan). Inst. of Industrial Science)

    1994-03-01

    The maximum purpose of the whisker composite is to overcome a brittleness of the ceramics and to raise a reliability. In order to do so, it is required that a toughening mechanism by the whisker should be investigated, and that an addition effect of the whisker should be exhibited to be the maximum by an improvement of the process. For the sake of using the composite ceramics as the high temperature structural materials in a wide range, in addition, besides the mechanical properties such as a fracture toughness (K[sub IC]) and a flexural strength (FS), the various properties such as a resistance to oxidation, fatigue strength, creep strength, thermal shock resistance, wear and abrasion resistance and so forth are necessary to be investigated. Because the kinds of whisker used, kind and quantity of the sintering auxiliary, preparation condition, evaluation method of K[sub IC] and FS and so forth are currently different depending on the researchers, and moreover the test procedure, specimen dimension and test condition are often different even in the same evaluation method, the mutual comparison of data are rather difficult. By achieving the furthermore toughening, by establishing the design technology and complex molding technology, by reducing the price drastically and so forth, an expansion of their application is expected. 115 refs., 9 figs., 4 tabs.

  14. Columnar-to-Equiaxed Transition in Metal-Matrix Composites Reinforced with Silicon Carbide Particles

    Directory of Open Access Journals (Sweden)

    Alicia E. Ares

    2013-01-01

    Full Text Available The present work is focused on the study of the effect of directional heat extraction on the silicon-carbide (SiC distribution in zinc-aluminum matrix composites (MMCs and on the columnar-to-equiaxed (CET position in directionally solidified samples. To this end, a ZA-27 alloy matrix was reinforced with ceramic particles of SiC and vertically directionally solidified. The cooling rates, temperature gradients, and interphase velocities were then measured, and their influence on the solidification microstructure of the MMCs was analyzed. The recalescence detected and measured during the equiaxed transition was of the order of 3.5°C to 1.1°C. The values of the temperature gradients reached a minimum during the CET and were even negative in most cases (between −3.89 K and 0.06 K. The interphase velocities varied between 0.07 mm/s and 0.44 mm/s at the transition. Also, the presence of ceramic particles in ZA-27 alloys affected the thermodynamic local conditions and the kinetics of nucleation, producing a finer microstructure.

  15. Processing of continuous fiber reinforced ceramic composites for ultra high temperature applications using organosilicon polymer precursors

    Science.gov (United States)

    Nicholas, James Robert

    The current work is on the development of continuous fiber reinforced ceramic materials (CFCCs) for use in ultra high temperature applications. These applications subject materials to extremely high temperatures(> 2000°C). Monolithic ceramics are currently being used for these applications, but the tendency to fail catastrophically has driven the need for the next generation of material. Reinforcing with continuous fibers significantly improves the toughness of the monolithic materials; however, this is a manufacturing challenge. The development of commercial, low-viscosity preceramic polymers provides new opportunities to fabricate CFCCs. Preceramic polymers behave as polymers at low temperatures and are transformed into ceramics upon heating to high temperatures. The polymer precursors enable the adaptation of well-established polymer processing techniques to produce high quality materials at relatively low cost. In the present work, SMP-10 from Starfire Systems, and PURS from KiON Corp. were used to manufacture ZrB2-SiC/SiC CFCCs using low cost vacuum bagging process in conjunction with the polymer infiltration and pyrolysis process. The microstructure was investigated using scanning electron microscopy and it was determined that the initial greenbody cure produced porosity of both closed and open pores. The open pores were found to be more successfully re-infiltrated using neat resin compared to slurry reinfiltrate; however, the closed pores were found to be impenetrable during subsequent reinfiltrations. The mechanical performance of the manufactured samples was evaluated using flexure tests and found the fiber reinforcement prevented catastrophic failure behavior by increasing fracture toughness. Wedge sample were fabricated and evaluated to demonstrate the ability to produce CFCC of complex geometry.

  16. Friction Stir Processing of Particle Reinforced Composite Materials

    Directory of Open Access Journals (Sweden)

    Daniel Solomon

    2010-01-01

    Full Text Available The objective of this article is to provide a review of friction stir processing (FSP technology and its application for microstructure modification of particle reinforced composite materials. The main focus of FSP was on aluminum based alloys and composites. Recently, many researchers have investigated this technology for treating other alloys and materials including stainless steels, magnesium, titanium, and copper. It is shown that FSP technology is very effective in microstructure modification of reinforced metal matrix composite materials. FSP has also been used in the processing and structure modification of polymeric composite materials. Compared with other manufacturing processes, friction stir processing has the advantage of reducing distortion and defects in materials. The layout of this paper is as follows. The friction stir processing technology will be presented first. Then, the application of this technology in manufacturing and structure modification of particle reinforced composite materials will be introduced. Future application of friction stir processing in energy field, for example, for vanadium alloy and composites will be discussed. Finally, the challenges for improving friction stir processing technology will be mentioned.

  17. Silane primers rather than heat treatment contribute to adhesive bonding between tri-n-butylborane resin and a machinable leucite-reinforced ceramic

    OpenAIRE

    Sakai, Miyuki; Taira, Yohsuke; Sawase, Takashi

    2011-01-01

    The purpose of the present study was to evaluate the effects of silane primers with and without heat treatment on bonding between a resin and a leucite-reinforced ceramic (GN-Ceram). Six dental primers (GC Ceramic Primer, GP; Clearfl Ceramic Primer, CP; RelyX Ceramic Primer, RP; Tokuso Ceramic Primer, TP; Shofu Porcelain Primer, SP; and Porcelain Liner M, PM) and five experimental primers (MDS, MTS, MDES, MTES, and ATS) were evaluated. GN-Ceram specimen was primed, heated at 100°C for 60 min ...

  18. Finite Element Analysis of IPS –Empress II Ceramic Bridge Reinforced by Zirconia Bar

    Directory of Open Access Journals (Sweden)

    Allahyar Geramy

    2012-01-01

    Full Text Available Objective: The aim of this study was to determine the effect of trenched zirconia bar on the von Mises stress distribution of IPS –Empress II core ceramics.Material and Methods: The three-dimensional model including a three-unit bridge from the second premolar to the second molar was designed. The model was reinforced with zirconia bar (ZB, zirconia bar with vertical trench (VZB, and zirconia bar with horizontal trench (HZB (cross sections of these bars were circular. The model without zirconia bar was designed as the control. The bridges were loaded by 200 N and 500 N on the occlusal surface at the middle of the pontic component, and Von-Mises stresses were evaluated along a defined path.Result: In the connector area, VonMises stress in MPa were approximately identical in the specimens with ZB (at molar connector (MC: 4.75, and at premolar connector (PC: 6.40 and without ZB (MC: 5.50, PC: 6.68, and considerable differences were not recognized. Whereas, Von-Mises stress (MPa in the specimens with horizontal trenched Zirconia bar (HZB (MC: 3.91, PC: 2.44 and Vertical trenched Zirconia bar (VZB (MC: 2.53, PC: 2.56 was decreased considerably.Conclusion: Embeded trenched zirconia bar could reinforce IPS-Empress II at the connector area which is a main failure region in all ceramic fixed partial dentures.

  19. Amorphization of complex ceramics by heavy-particle irradiations

    International Nuclear Information System (INIS)

    Complex ceramics, for the purpose of this paper, include materials that are generally strongly bonded (mixed ionic and covalent), refractory and frequently good insulators. They are distinguished from simple, compact ceramics (e.g., MgO and UO2) by structural features which include: (1) open network structures, best characterized by a consideration of the shape, size and connectivity of coordination polyhedra; (2) complex compositions which characteristically lead to multiple cation sites and lower symmetry; (3) directional bonding; (4) bond-type variations within the structure. The heavy particle irradiations include ion-beam irradiations and recoil-nucleus damage resulting from a-decay events from constituent actinides. The latter effects are responsible for the radiation-induced transformation to the metamict state in minerals. The responses of these materials to irradiation are complex, as energy may be dissipated ballistically by transfer of kinetic energy from an incident projectile or radiolytically by conversion of radiation-induced electronic excitations into atomic motion. This results in isolated Frenkel defect pairs, defect aggregates, isolated collision cascades or bulk amorphization. Thus, the amorphization process is heterogeneous. Only recently have there been systematic studies of heavy particle irradiations of complex ceramics on a wide variety of structure-types and compositions as a function of dose and temperature. In this paper, we review the conditions for amorphization for the tetragonal orthosilicate, zircon [ZrSiO4]; the hexagonal orthosilicate/phosphate apatite structure-type [X10(ZO4)6(F,Cl,O)2]; the isometric pyrochlores [A1-2B2O6(O,OH,F)0-1pH2O] and its monoclinic derivative zirconotite [CaZrTi2O7]; the olivine (derivative - hcp) structure types, α-VIA2IVBO4, and spinel (ccp), γ-VIA2IVBO4

  20. Effects of particle size on the mechanical properties of particle-reinforced Sn-Ag composite solder joint

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Particulate size has significant influenced on the mechanical properties of particle-reinforced composite solder joints. In this current research, Cu or Ni reinforcement particles were mechanically added to the Sn-3.5Ag eutectic solder, and the effects of the particle size on the mechanical properties of particle-reinforced composite solder joint were systematically studied. This investigation touched on how mechanical properties of the solder joints are affected by particles size. A quantitative formula was set up to correlate the mechanical property of the solder joint with particle size in different processing conditions. Besides, the fracture mechanism of the composite solder joint was analyzed.

  1. Encapsulation of sacrificial silicon containing particles for SH oxide ceramics via a boehmite precursor route

    NARCIS (Netherlands)

    Carabat, A.L.; Van der Zwaag, S.; Sloof, W.G.

    2013-01-01

    Easy crack propagation in oxide ceramic coatings limits their application in high temperature environment (e.g. such as engines and gas turbine components) [1]. In order to overcome this problem, incorporation of sacrificial particles into an oxide ceramic coating may be a viable option. Particles o

  2. Micromechanics Fatigue Damage Analysis Modeling for Fabric Reinforced Ceramic Matrix Composites

    Science.gov (United States)

    Min, J. B.; Xue, D.; Shi, Y.

    2013-01-01

    A micromechanics analysis modeling method was developed to analyze the damage progression and fatigue failure of fabric reinforced composite structures, especially for the brittle ceramic matrix material composites. A repeating unit cell concept of fabric reinforced composites was used to represent the global composite structure. The thermal and mechanical properties of the repeating unit cell were considered as the same as those of the global composite structure. The three-phase micromechanics, the shear-lag, and the continuum fracture mechanics models were integrated with a statistical model in the repeating unit cell to predict the progressive damages and fatigue life of the composite structures. The global structure failure was defined as the loss of loading capability of the repeating unit cell, which depends on the stiffness reduction due to material slice failures and nonlinear material properties in the repeating unit cell. The present methodology is demonstrated with the analysis results evaluated through the experimental test performed with carbon fiber reinforced silicon carbide matrix plain weave composite specimens.

  3. Fatigue Hysteresis of Carbon Fiber-Reinforced Ceramic-Matrix Composites at Room and Elevated Temperatures

    Science.gov (United States)

    Li, Longbiao

    2016-02-01

    When the fiber-reinforced ceramic-matrix composites (CMCs) are first loading to fatigue peak stress, matrix multicracking and fiber/matrix interface debonding occur. Under fatigue loading, the stress-strain hysteresis loops appear as fiber slipping relative to matrix in the interface debonded region upon unloading/reloading. Due to interface wear at room temperature or interface oxidation at elevated temperature, the interface shear stress degredes with increase of the number of applied cycles, leading to the evolution of the shape, location and area of stress-strain hysteresis loops. The evolution characteristics of fatigue hysteresis loss energy in different types of fiber-reinforced CMCs, i.e., unidirectional, cross-ply, 2D and 2.5D woven, have been investigated. The relationships between the fatigue hysteresis loss energy, stress-strain hysteresis loops, interface frictional slip, interface shear stress and interface radial thermal residual stress, matrix stochastic cracking and fatigue peak stress of fiber-reinforced CMCs have been established.

  4. Marginal adaptation of 1 fiber-reinforced composite and 2 all-ceramic inlay fixed partial denture systems

    OpenAIRE

    Monaco, Carlo; Krejci, Ivo; Bortolotto Ibarra, Tissiana; Perakis, Nikolaos; Ferrari,Marco; Scotti, Roberto

    2006-01-01

    The aim of this in vitro study was to evaluate the marginal adaptation and retention of inlay fixed partial dentures (IFPDs) made with 1 fiber-reinforced composite and 2 different ceramic materials using quantitative scanning electron microscope analysis after thermal cycling and mechanical loading, which simulated approximately 5 years of oral service.

  5. Macroscopic response of particle-reinforced elastomers subjected to prescribed torques or rotations on the particles

    Science.gov (United States)

    Siboni, Morteza H.; Ponte Castañeda, Pedro

    2016-06-01

    Particle-reinforced rubbers are composite materials consisting of randomly distributed, stiff fibers/particles in a soft elastomeric material. Since the particles are stiff compared to the embedding rubber, their deformation can be ignored for all practical purposes. However, due to the softness of the rubber, they can undergo rigid body translations and rotations. Constitutive models accounting for the effect of such particle motions on the macroscopic response under prescribed deformations on the boundary have been developed recently. But, in some applications (e.g., magneto-active elastomers), the particles may experience additional torques as a consequence of an externally applied (magnetic) field, which, in turn, can affect the overall rotation of the particles in the rubber, and therefore also the macroscopic response of the composite. This paper is concerned with the development of constitutive models for particle-reinforced elastomers, which are designed to account for externally applied torques on the internally distributed particles, in addition to the externally applied deformation on the boundary of the composite. For this purpose, we propose a new variational framework involving suitably prescribed eigenstresses on the particles. For simplicity, the framework is applied to an elastomer reinforced by aligned, rigid, cylindrical fibers of elliptical cross section, which can undergo finite rotations in the context of a finite-deformation, plane strain problem for the composite. In particular, expressions are derived for the average in-plane rotation of the fibers as a function of the torques that are applied on them, both under vanishing and prescribed strain on the boundary. The results of this work will make possible the development of improved constitutive models for magneto-active elastomers, and other types of smart composite materials that are susceptible to externally applied torques.

  6. Effects of particle size on the mechanical properties of particle-reinforced Sn-Ag composite solder joint

    Institute of Scientific and Technical Information of China (English)

    TAI Feng; GUO Fu

    2009-01-01

    Particulate size has significant influenced on the mechanical properties of particle-reinforced compos-ite solder joints. In this current research, Cu or Ni reinforcement particles were mechanically added to the Sn-3.5Ag eutectic solder, and the effects of the particle size on the mechanical properties of parti-cle-reinforced composite solder joint were systematically studied. This investigation touched on how mechanical properties of the solder joints are affected by particles size. A quantitative formula was set up to correlate the mechanical property of the solder joint with particle size in different processing conditions. Besides, the fracture mechanism of the composite solder joint was analyzed.

  7. Porosity characterization of fiber-reinforced ceramic matrix composite using synchrotron X-ray computed tomography

    International Nuclear Information System (INIS)

    The pore structure and porosity of a continuous fiber reinforced ceramic matrix composite has been characterized using high-resolution synchrotron X-ray computed tomography (XCT). Segmentation of the reconstructed tomograph images reveals different types of pores within the composite, the inter-fiber bundle open pores displaying a 'node-bond' geometry, and the intra-fiber bundle isolated micropores showing a piping shape. The 3D morphology of the pores is resolved and each pore is labeled. The quantitative filtering of the pores measures a total porosity 8.9% for the composite, amid which there is about 7.1∼ 9.3% closed micropores

  8. Modeling of the mechanical behavior of fiber-reinforced ceramic composites using finite element method (FEM

    Directory of Open Access Journals (Sweden)

    Dimitrijević M.M.

    2014-01-01

    Full Text Available Modeling of the mechanical behavior of fiber-reinforced ceramic matrix composites (CMC is presented by the example of Al2O3 fibers in an alumina based matrix. The starting point of the modeling is a substructure (elementary cell which includes on a micromechanical scale the statistical properties of the fiber, matrix and fiber-matrix interface and their interactions. The numerical evaluation of the model is accomplished by means of the finite element method. The numerical results of calculating the elastic modulus of the composite dependance on the quantity of the fibers added and porosity was compared to experimental values of specimens having the same composition. [Projekat Ministarstva nauke Republike Srbije, br. ON174004 i TVH to project III45012

  9. Analysis of the solidification and microstructure of two aluminium alloys reinforced with TiB{sub 2} particles

    Energy Technology Data Exchange (ETDEWEB)

    Egizabal, Pedro; Garcia de Cortazar, Maider [Fundacion Inasmet E-20009 Donostia-San Sebastian (Spain); Torregaray, Amaia [University of Basque Country UPV/EHU E-48012, Bilbo-Bilbao (Spain); Veillere, Amelie; Silvain, Jean-Francois [CNRS, Universite de Bordeaux, ICMCB 87 Avenue du Docteur Albert Schweitzer, 33608 Pessac (France); Douin, Joel [CEMES-CNRS 29 Rue Jeanne Marvig, BP 94347, 31055 Toulouse Cedex 4 (France)

    2011-09-15

    Two aluminium alloys with 6 wt% TiB{sub 2} particles are studied for applications where increased wear resistance and mechanical strength at high temperature are required. The incorporation of hard ceramic particles has a strong influence on the microstructure and properties of the alloys. TiB{sub 2} particles play an important role in the nucleation of the different phases of the alloys during solidification, and in the reduction of grain size and porosity. The solidification patterns of Al-Si{sub 7}Mg{sub 0.3} + TiB{sub 2} (6 wt%) and Al-Cu{sub 5}MgTi+TiB{sub 2} (6 wt%) materials are compared to their corresponding non-reinforced alloys, and the microstructures are analyzed. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  10. Mode I Fracture Toughness Prediction for Multiwalled-Carbon-Nanotube Reinforced Ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen, Ba Nghiep; Henager, Charles H.

    2015-08-27

    This article develops a multiscale model to predict fracture toughness of multiwalled-carbon-nanotube (MWCNT) reinforced ceramics. The model bridges different scales from the scale of a MWCNT to that of a composite domain containing a macroscopic crack. From the nano, micro to meso scales, Eshelby-Mori-Tanaka models combined with a continuum damage mechanics approach are explored to predict the elastic damage behavior of the composite as a function of MWCNT volume fraction. MWCNTs are assumed to be randomly dispersed in a ceramic matrix subject to cracking under loading. A damage variable is used to describe matrix cracking that causes reduction of the elastic modulus of the matrix. This damage model is introduced in a modified boundary layer modeling approach to capture damage initiation and development at a tip of a pre-existing crack. Damage and fracture are captured only in a process window containing the crack tip under plane strain Mode I loading. The model is validated against the published experimental fracture toughness data for a MWCNT 3 mol% yttria stabilized zirconia composite system. In addition, crack resistance curves as a function of MWCNT content are predicted and fitted by a power law as observed in the experiments on zirconia.

  11. Fiber reinforced superalloys, ceramics, and refractory metals, and directionally solidified eutectics (heat-resistant composites)

    International Nuclear Information System (INIS)

    High-temperature composites have been shown to have excellent elevated-temperature tensile and stress-rupture strengths and specific strengths. Tungsten alloy fiber reinforced superalloys have been demonstrated to have stress rupture strengths at 20000F superior to superalloys and sufficient impact resistance for gas turbines. Recently developed tungsten alloy fibers should permit production of composites with use-temperatures (gas turbine blades, vanes) as high as 24000F. Their main problem is associated with the direction and perfection of growth of strong whiskers or lamina in irregularly shaped components. Artificially made whisker composites are believed to warrant serious consideration. Use-temperatures of refractory metal matrix composites can be as much as 25000F for Nb matrix composites and over 30000F for W matrix composites. Ceramic matrix composites with use-temperatures ranging from 18000F to over 30000F are possibilities. Stationary, large, turbines for power generation may make use of refractory fiber/superalloy matrix, ceramic matrix, and coated refractory matrix composites. Such an application may capitalize on the high-temperature strength and high use-temperatures of the composites, which, in turn, will enhance engine performance. (127 references, 62 fig, 22 tables) (U.S.)

  12. Thermal stability of segmented polyurethane elastomers reinforced by clay particles

    Directory of Open Access Journals (Sweden)

    Pavličević Jelena

    2009-01-01

    Full Text Available The aim of this work was to determine the influence of clay nanoparticles on thermal properties of segmented polyurethanes based on hexamethylene- diisocyanate, aliphatic polycarbonate diol and 1,4-butanediol as chain extender. The organically modified particles of montmorillonite and bentonite were used as reinforcing fillers. The structure of elastomeric materials was varied either by diol type or chain extender content. The ratio of OH groups from diol and chain extender (R was either 1 or 10. Thermal properties of prepared materials were determined using modulated differential scanning calorimetry (MDSC. Thermal stability of obtained elastomers has been studied by simultaneously thermogravimetry coupled with DSC. The glass transition temperature, Tg, of soft segments for all investigated samples was about -33°C. On the basis of DTG results, it was concluded that obtained materials were very stable up to 300°C.

  13. Microstructure and Dry-Sliding Wear Behavior of B4C Ceramic Particulate Reinforced Al 5083 Matrix Composite

    Directory of Open Access Journals (Sweden)

    Qian Zhao

    2016-09-01

    Full Text Available B4C ceramic particulate–reinforced Al 5083 matrix composite with various B4C content was fabricated successfully via hot-press sintering under Argon atmosphere. B4C particles presented relative high wettability, bonding strength and symmetrical distribution in the Al 5083 matrix. The hardness value, friction coefficient and wear resistance of the composite were higher than those of the Al 5083 matrix. The augment of the B4C content resulted in the increase of the friction coefficient and decrease of the wear mass loss, respectively. The 30 wt % B4C/Al 5083 composite exhibited the highest wear resistance. At a low load of 50 N, the dominant wear mechanisms of the B4C/Al 5083 composite were micro-cutting and abrasive wear. At a high load of 200 N, the dominant wear mechanisms were micro-cutting and adhesion wear associated with the formation of the delamination layer which protected the composite from further wear and enhanced the wear resistance under the condition of high load.

  14. Solid particle erosion of plasma sprayed ceramic coatings

    Directory of Open Access Journals (Sweden)

    José Roberto Tavares Branco

    2004-03-01

    Full Text Available Thermal spraying allows the production of overlay protective coatings of a great variety of materials, almost without limitations as to its components, phases and constituents on a range of substrates. Wear and corrosion resistant coatings account for significant utilization of thermal spray processes. Besides being a means to evaluate the coating tribological performance, erosion testing allows also an assessment of the coating toughness and adhesion. Nevertheless, the relationship between the erosion behavior of thermal sprayed coatings and its microstructural features is not satisfactorily understood yet. This paper examines room temperature solid particle erosion of zirconia and alumina-based ceramic coatings, with different levels of porosity and varying microstrucutre and mechanical properties. The erosion tests were carried out by a stream of alumina particles with an average size of 50 µm at 70 m/s, carried by an air jet with impingement angle 90°. The results indicate that current erosion models based on hardness alone cannot account for experimental results, and, that there is a strong relationship between the erosion rate and the porosity.

  15. Toughness enhancement in graphene nanoplatelet/SiC reinforced Al2O3 ceramic hybrid nanocomposites

    Science.gov (United States)

    Ahmad, Iftikhar; Islam, Mohammad; Subhani, Tayyab; Zhu, Yanqiu

    2016-10-01

    This paper elucidates the effect of silicon carbide nanoparticles (SiCNP) and graphene nanoplatelets (GNPs), on their own and together, on the densification behavior and fracture toughness of alumina (Al2O3) ceramic matrix. This was investigated by using the high-frequency induction heat sintering (HFIHS) process. While the addition of each nanostructure caused varying degrees of grain refinement and enhancement of mechanical properties, the incorporation of as little as 0.5 wt.% GNPs along with 5.0 wt.% SiCNP promoted uniform dispersion of the latter due to the lateral surface area of the graphene nanosheets with their two-dimensional morphology. There was an associated reduction in grain size from 1500 to 300 nm upon the addition of both types of nanoscale reinforcements. Extensive electron microscopy of the as-produced nanocomposites indicated the presence of SiCNP within, as well as at, the grain boundary areas whereas the 2D GNPs anchored between neighboring grains. Fractography of the samples revealed a transition from a mixed intergranular/transgranular mode for SiCNP or GNP-reinforced nanocomposites to transgranular fracture mode for the hybrid nanocomposites with improvements in fracture toughness and microhardness by 160 and 27%, respectively, largely due to the synergic role of the nanostructured reinforcements and their distinctly different toughening mechanisms. A new toughening model is proposed for the hybrid nanocomposites by taking into consideration crack deflection and pull-out effects due to SiCNP and the atomic level slip-stick driven GNPs inter-layer slithering. It was found that the addition of GNPs facilitates SiCNP dispersion that subsequently develops dense, fine-grained microstructures after a short-cycle, pressure-assisted consolidation process.

  16. Toughness enhancement in graphene nanoplatelet/SiC reinforced Al2O3 ceramic hybrid nanocomposites.

    Science.gov (United States)

    Ahmad, Iftikhar; Islam, Mohammad; Subhani, Tayyab; Zhu, Yanqiu

    2016-10-21

    This paper elucidates the effect of silicon carbide nanoparticles (SiCNP) and graphene nanoplatelets (GNPs), on their own and together, on the densification behavior and fracture toughness of alumina (Al2O3) ceramic matrix. This was investigated by using the high-frequency induction heat sintering (HFIHS) process. While the addition of each nanostructure caused varying degrees of grain refinement and enhancement of mechanical properties, the incorporation of as little as 0.5 wt.% GNPs along with 5.0 wt.% SiCNP promoted uniform dispersion of the latter due to the lateral surface area of the graphene nanosheets with their two-dimensional morphology. There was an associated reduction in grain size from 1500 to 300 nm upon the addition of both types of nanoscale reinforcements. Extensive electron microscopy of the as-produced nanocomposites indicated the presence of SiCNP within, as well as at, the grain boundary areas whereas the 2D GNPs anchored between neighboring grains. Fractography of the samples revealed a transition from a mixed intergranular/transgranular mode for SiCNP or GNP-reinforced nanocomposites to transgranular fracture mode for the hybrid nanocomposites with improvements in fracture toughness and microhardness by 160 and 27%, respectively, largely due to the synergic role of the nanostructured reinforcements and their distinctly different toughening mechanisms. A new toughening model is proposed for the hybrid nanocomposites by taking into consideration crack deflection and pull-out effects due to SiCNP and the atomic level slip-stick driven GNPs inter-layer slithering. It was found that the addition of GNPs facilitates SiCNP dispersion that subsequently develops dense, fine-grained microstructures after a short-cycle, pressure-assisted consolidation process. PMID:27623018

  17. Tensile and Compressive Responses of Ceramic and Metallic Nanoparticle Reinforced Mg Composites

    Directory of Open Access Journals (Sweden)

    Quy Bau Nguyen

    2013-05-01

    Full Text Available In the present study, room temperature mechanical properties of pure magnesium, Mg/ZrO2 and Mg/(ZrO2 + Cu composites with various compositions are investigated. Results revealed that the use of hybrid (ZrO2 + Cu reinforcements in Mg led to enhanced mechanical properties when compared to that of single reinforcement (ZrO2. Marginal reduction in mechanical properties of Mg/ZrO2 composites were observed mainly due to clustering of ZrO2 particles in Mg matrix and lack of matrix grain refinement. Addition of hybrid reinforcements led to grain size reduction and uniform distribution of hybrid reinforcements, globally and locally, in the hybrid composites. Macro- and micro- hardness, tensile strengths and compressive strengths were all significantly increased in the hybrid composites. With respect to unreinforced magnesium, failure strain was almost unchanged under tensile loading while it was reduced under compressive loading for both Mg/ZrO2 and Mg/(ZrO2 + Cu composites.

  18. Effect of reinforcement particle size on the tribological properties of nano-diamond filled polytetrafluoroethylene based coating.

    Science.gov (United States)

    Lim, D P; Lee, J Y; Lim, D S; Ahn, S G; Lyo, I W

    2009-07-01

    The tribological properties of PTFE composite coatings reinforced by nano-diamonds were investigated. Mechanical particle size reduction and dispersion of nano-diamond aggregates were performed by milling with ceramic beads in an organic solvent. Particle size was controlled by the milling time. Pastes comprising a PTFE solution mixed with nano-diamond having various sizes were coated on the aluminum substrate. Ball-on-plate type wear test was performed to investigate the friction and wear behavior. The results indicated that the addition of nano-diamonds effectively improved tribological performance of the PTFE coating. The reduction in nano-diamond sizes were not always improved the wear resistance of PTFE coating. This unexpected behavior was explained by observation on the worn surfaces and wear debris. PMID:19916429

  19. Synthesis of high performance ceramic fibers by chemical vapor deposition for advanced metallics reinforcing

    Science.gov (United States)

    Revankar, Vithal; Hlavacek, Vladimir

    1991-01-01

    The chemical vapor deposition (CVD) synthesis of fibers capable of effectively reinforcing intermetallic matrices at elevated temperatures which can be used for potential applications in high temperature composite materials is described. This process was used due to its advantage over other fiber synthesis processes. It is extremely important to produce these fibers with good reproducible and controlled growth rates. However, the complex interplay of mass and energy transfer, blended with the fluid dynamics makes this a formidable task. The design and development of CVD reactor assembly and system to synthesize TiB2, CrB, B4C, and TiC fibers was performed. Residual thermal analysis for estimating stresses arising form thermal expansion mismatch were determined. Various techniques to improve the mechanical properties were also performed. Various techniques for improving the fiber properties were elaborated. The crystal structure and its orientation for TiB2 fiber is discussed. An overall view of the CVD process to develop CrB2, TiB2, and other high performance ceramic fibers is presented.

  20. Modeling the Tensile Strength of Carbon Fiber - Reinforced Ceramic - Matrix Composites Under Multiple Fatigue Loading

    Science.gov (United States)

    Li, Longbiao

    2016-06-01

    An analytical method has been developed to investigate the effect of interface wear on the tensile strength of carbon fiber - reinforced ceramic - matrix composites (CMCs) under multiple fatigue loading. The Budiansky - Hutchinson - Evans shear - lag model was used to describe the micro stress field of the damaged composite considering fibers failure and the difference existed in the new and original interface debonded region. The statistical matrix multicracking model and fracture mechanics interface debonding criterion were used to determine the matrix crack spacing and interface debonded length. The interface shear stress degradation model and fibers strength degradation model have been adopted to analyze the interface wear effect on the tensile strength of the composite subjected to multiple fatigue loading. Under tensile loading, the fibers failure probabilities were determined by combining the interface wear model and fibers failure model based on the assumption that the fiber strength is subjected to two - parameter Weibull distribution and the loads carried by broken and intact fibers satisfy the Global Load Sharing criterion. The composite can no longer support the applied load when the total loads supported by broken and intact fibers approach its maximum value. The conditions of a single matrix crack and matrix multicrackings for tensile strength corresponding to multiple fatigue peak stress levels and different cycle number have been analyzed.

  1. Residual stress analysis in carbon fiber-reinforced SiC ceramics

    International Nuclear Information System (INIS)

    Systematic residual stress analyses are reported, carried out in long-fiber reinforced SiC ceramics. The laminated Cfiber/SiCmatrix specimens used were prepared by polymer pyrolysis, and the structural component specimens used are industrial products. Various diffraction methods have been applied for non-destructive evaluation of residual stress fields, so as to completely detect the residual stresses and their distribution in the specimens. The residual stress fields at the surface (μm) have been measured using characteristic X-radiation and applying the sin 2ψ method as well as the scatter vector method. For residual stress field analysis in the mass volume (cm), neutron diffraction has been applied. The stress fields in the fiber layers (approx. 250μm) have been measured as a function of their location within the laminated composite by using an energy-dispersive method and synchrotron radiation. By means of the systematic, process-accompanying residual stress and phase analyses, conclusions can be drawn as to possible approaches for optimization of fabrication parameters. (orig./CB)

  2. Influence of hard ceramic particles on structure and properties of TGM

    Directory of Open Access Journals (Sweden)

    L.A. Dobrzański

    2007-10-01

    Full Text Available Purpose: The Powder Metallurgy route has been chosen to fabricate tool gradient materials with high disproportion of cobalt matrix portion between core and surface layer. In the paper structure and properties of TGM have been shown.Design/methodology/approach: SEM, light microscope, microhardness tests, density examination.Findings: According to carried out researches it could be stated, that forming the gradient materials with highest amount of complex carbide (W,TiC 90-95%, using uniaxial unilateral pressing, could be possible after adding into each layer of mixes 2 % of paraffin lubricant. High diversification of cobalt matrix ratio in comparison to hard phases in subsequent layers of gradient materials leads to their deformation in as sintered state. In case of all gradient materials, mean hardness was equal about 1600 HV1. Whereas, hardness of lower cobalt matrix rich layers brought values about 1450 HV1 and increased up to 1800 HV1 for lower layer of material rich with hard carbide phases.Practical implications: Material presented in this paper is characterized by very high hardness of the surface and relative ductility of core. TGM is a smoothly varying distribution of phases element composition.Originality/value: In the paper the manufacturing of TGM on basis of different portion of cobalt reinforced with hard ceramics particles carried out in order to improve the abrasion resistance and ductility of tool cutting materials.

  3. Fabrication of Al-based composites reinforced with Al2O3-Tib2 ceramic composite particulates using vortex-casting method

    Directory of Open Access Journals (Sweden)

    Roshan M.R.

    2013-01-01

    Full Text Available Vortex casting is one of the simplest methods of producing metal matrix composites (MMCs. However, this simple method does have some drawbacks, which reduce the mechanical properties of the produced composites. In this study, we tried to modify the process of composite production before, during, and after the casting procedure. Low-cost Al2O3-TiB2 ceramic composite particles, which produced after combustion synthesis, were used as reinforcement. These powders, which are thermodynamically stable with molten aluminum below 900°C, were mixed with aluminum and magnesium powders before casting using ball milling and the mixed powders were injected into the molten metal (pure Al. This process was applied to enhance the wettability of ceramic particles with molten aluminum. After casting, warm equal channel angular pressing (ECAP and hot extrusion processes were applied to investigate their effects on the mechanical properties of the final composites. It was revealed that both warm ECAP and hot extrusion have a strong influence on increasing the mechanical properties mainly due to decreasing the amount of porosities.

  4. ON THE EFFECT OF NANO-PARTICLE CLUSTERING ON TOUGHENING OF NANO-COMPOSITE CERAMICS

    Institute of Scientific and Technical Information of China (English)

    董照旭; 方岱宁; 苏爱嘉

    2002-01-01

    In this paper, two and three-dimensional clustering models are developed to characterize the effect of nano-particle clustering on toughening of nanocomposite ceramics. It is found that crack pinning toughens the nano-composite ceramics because a higher stress intensity factor is needed for crack to propagate around or to pull-out the nano-particle. The nano-particle along the grain boundary steers the crack into the matrix grain due to the strong cohesion between the nanoparticle and the matrix. Since the fracture resistance of the grain boundary is lower than that of the grain lattice, the higher the probability of transgranular fracture induced by nano-particles, the tougher is the nano-composite. However, both crack pinning and transgranular fracture are affected by nano-particle clustering. Nanoparticle clustering, which increases with increasing volume fraction of nano-particles,leads to reduction of both the strength and toughness of the nano-composite ceramics. The larger the size of the clustered particle, and the more defects it contains, the easier it is for the crack to pass through the clustered particle, which means that the nano-particle clustering can reduce toughening induced by crack pinning and transgranular fracture. The theoretical prediction, based on the combination of the three mechanisms of nano-particles, is in agreement with the experimental data.

  5. Effect of SiC and GR Reinforcement Particles on the Structure and Functional Properties of Composite Casting E43 MMC Reinforced with SiC Particles

    Directory of Open Access Journals (Sweden)

    Boczkal S.

    2016-03-01

    Full Text Available The aim of the study was to describe the structure of composites based on the AlSi7Mg2Sr0.03 alloy matrix reinforced with SiC particles added in an amount of 10% and with a mixture of SiC and GR particles added in a total amount of 20%. Studies of the composite structure, were carried out by scanning electron microscopy (SEM. Based on the results of chemical analysis in microregions, an increased content of elements such as Mg, O and Si and of the precipitates was observed at the interface. In many places in the examined sample, GR particles formed partly disintegrated conglomerates with well developed boundaries. The effect of the content of particles of the reinforcing phase on the functional properties of the composite was investigated during studies of abrasion. The lowest mass loss of 5,33mg was obtained for the AlSi7Mg2Sr0.03 alloy reinforced with 10% SiC particles.

  6. Effects of Particle Size on the Shear Behavior of Coarse Grained Soils Reinforced with Geogrid

    Directory of Open Access Journals (Sweden)

    Daehyeon Kim

    2014-02-01

    Full Text Available In order to design civil structures that are supported by soils, the shear strength parameters of soils are required. Due to the large particle size of coarse-grained soils, large direct shear tests should be performed. In this study, large direct shear tests on three types of coarse grained soils (4.5 mm, 7.9 mm, and 15.9 mm were performed to evaluate the effects of particle size on the shear behavior of coarse grained soils with/without geogrid reinforcements. Based on the direct shear test results, it was found that, in the case of no-reinforcement, the larger the maximum particle size became, the larger the friction angle was. Compared with the no-reinforcement case, the cases reinforced with either soft geogrid or stiff geogrid have smaller friction angles. The cohesion of the soil reinforced with stiff geogrid was larger than that of the soil reinforced with soft geogrid. The difference in the shear strength occurs because the case with a stiff geogrid has more soil to geogrid contact area, leading to the reduction in interlocking between soil particles.

  7. Shear bond strength of a new self-adhering flowable composite resin for lithium disilicate-reinforced CAD/CAM ceramic material

    Science.gov (United States)

    Sancakli, Hande Sar; Sancakli, Erkan; Eren, Meltem Mert; Ozel, Sevda; Yucel, Taner; Yildiz, Esra

    2014-01-01

    PURPOSE The purpose of this study was to evaluate and compare the effects of different surface pretreatment techniques on the surface roughness and shear bond strength of a new self-adhering flowable composite resin for use with lithium disilicate-reinforced CAD/CAM ceramic material. MATERIALS AND METHODS A total of one hundred thirty lithium disilicate CAD/CAM ceramic plates with dimensions of 6 mm × 4 mm and 3 mm thick were prepared. Specimens were then assigned into five groups (n=26) as follows: untreated control, coating with 30 µm silica oxide particles (Cojet™ Sand), 9.6% hydrofluoric acid etching, Er:YAG laser irradiation, and grinding with a high-speed fine diamond bur. A self-adhering flowable composite resin (Vertise Flow) was applied onto the pre-treated ceramic plates using the Ultradent shear bond Teflon mold system. Surface roughness was measured by atomic force microscopy. Shear bond strength test were performed using a universal testing machine at a crosshead speed of 1 mm/min. Surface roughness data were analyzed by one-way ANOVA and the Tukey HSD tests. Shear bond strength test values were analyzed by Kruskal-Wallis and Mann-Whitney U tests at α=.05. RESULTS Hydrofluoric acid etching and grinding with high-speed fine diamond bur produced significantly higher surface roughness than the other pretreatment groups (P<.05). Hydrofluoric acid etching and silica coating yielded the highest shear bond strength values (P<.001). CONCLUSION Self-adhering flowable composite resin used as repair composite resin exhibited very low bond strength irrespective of the surface pretreatments used. PMID:25551002

  8. Selected properties of the aluminium alloy base composites reinforced with intermetallic particles

    OpenAIRE

    M. Adamiak

    2005-01-01

    Purpose: The main aim of this work is to investigate two types of intermetallics TiAl and Ti3Al as reinforcement and their influence on selected properties and microstructure of aluminium matrix composites.Design/methodology/approach: Aluminium matrix composites were produced employing the atomised aluminium alloy AA6061 as metal matrix, when as reinforcement TiAl and Ti3Al intermetallics particles were used. The powders were cold pressed and then hot extruded. To evaluate the effect of mecha...

  9. High-temperature mechanical properties of aluminium alloys reinforced with boron carbide particles

    Energy Technology Data Exchange (ETDEWEB)

    Onoro, J. [Dept. Ingenieria y Ciencia de los Materiales, ETSI Industriales, Universidad Politecnica de Madrid, c/Jose Gutierrez Abascal 2, 28006 Madrid (Spain)], E-mail: javier.onoro@upm.es; Salvador, M.D. [Dept. Ingenieria Mecanica y de Materiales, ETSI Industriales, Universidad Politecnica de Valencia, Camino de Vera s/n, 46071 Valencia (Spain); Cambronero, L.E.G. [Dept. Ingenieria de Materiales, ETSI Minas, Universidad Politecnica de Madrid, c/Rios Rosas 21, 28003 Madrid (Spain)

    2009-01-15

    The mechanical properties of particulate-reinforced metal-matrix composites based on aluminium alloys (6061 and 7015) at high temperatures were studied. Boron carbide particles were used as reinforcement. All composites were produced by hot extrusion. The tensile properties and fracture analysis of these materials were investigated at room temperature and at high temperature to determine their ultimate strength and strain to failure. The fracture surface was analysed by scanning electron microscopy.

  10. Laser melt injection of ceramic particles in metals : Processing, microstructure and properties

    NARCIS (Netherlands)

    Ocelík, V.; De Hosson, J.Th.M.

    2010-01-01

    The objective of this paper is to present an overview of the possibilities of the laser melt injection (LMI) methodology to enhance the surface of light-weighted metals by adding hard ceramic particles in the top layer, with the aim to enhance the wear resistance and to increase the hardness. In par

  11. SiC nanowires reinforced MAS joint of SiC coated carbon/carbon composites to LAS glass ceramics

    International Nuclear Information System (INIS)

    Graphical abstract: Schematic cross-section images of the samples with SiC nanowires and assembly sequence for the raw materials through the process of the hot-pressing method. Highlights: ► The SiC nanowires were firstly used as porous layer in the middle of the joint. ► The shear strength of the joint with SiC nanowires was largely improved. ► A new mode of fracture was proposed. - Abstract: In order to improve the shear strength of the joints of carbon/carbon (C/C) composites to lithium aluminum silicate (LAS) glass ceramics, SiC coating and magnesium aluminum silicate (MAS) glass ceramics were used as transition layer and middle layer, respectively, and high quality SiC nanowires were applied as the reinforcement materials in MAS. The SiC nanowires reinforced MAS joint of SiC coated C/C composites to LAS glass ceramics was prepared by a three-step technique of pack cementation, CVD and hot-pressing. The microstructures of the as-prepared joints were characterized by SEM and EDS, and the shear strength of the joints was also examined. The shear strength of the SiC–MAS joint increased from 24.0 ± 2.0 MPa to 35.5 ± 5.5 MPa after adding SiC nanowires in MAS. The load decreases in step-style but not perpendicularly after the maximum value, which demonstrates good toughness of the joint with SiC nanowire porous layer.

  12. Thermodynamic analysis of chemical compatibility of ceramic reinforcement materials with niobium aluminides

    Science.gov (United States)

    Misra, Ajay K.

    1990-01-01

    Chemical compatibility of several reinforcement materials with three niobium aluminides, Nb3Al, Nb2Al, and NbAl3, were examined from thermodynamic considerations. The reinforcement materials considered in this study include carbides, borides, nitrides, oxides, silicides, and Engel-Brewer compounds. Thermodynamics of the Nb-Al system were reviewed and activities of Nb and Al were derived at desired calculation temperatures. Criteria for chemical compatibility between the reinforcement material and Nb-Al compounds have been defined and several chemically compatible reinforcement materials have been identified.

  13. Dynamic Effects in Elastothermodynamic Damping of Hollow Particle Reinforced Metal-Matrix Composites

    Science.gov (United States)

    Srivastava, Sunil Kumar; Mishra, Bhanu Kumar

    2016-06-01

    The Metal-Matrix Composites (MMCs) containing hollow spherical reinforcements are under active development for the applications such as space structures, submarine hulls etc. where weight is of critical importance. When these materials are subjected to a time varying strain field, energy is dissipated because of the thermoelastic effect (Elastothermodynamic Damping or ETD). The quasi-static ETD analysis for the MMCs containing hollow spherical particles has been reported in literature. The entropic approach, which is better suited for composite materials with perfect or imperfect interfaces, is used for the analysis. In the present work, the effect of inertia forces is carried out on ETD of hollow particle-reinforced MMCs. For given particle volume fractions (V p ), the inertia forces are found to be more significant at higher value of thermal parameter (Ω T1) (alternatively, frequency of vibration if reinforcement radius is fixed), large cavity volume fraction (V h ) and low value of the parameter B1.

  14. Topographical Parameter Characteristics of Dry Sliding Surfaces of Particle-Reinforced Aluminum Composites

    Institute of Scientific and Technical Information of China (English)

    陈跃; 上官宝; 张永振; 孙乐民; 铁喜顺; 夏跃虹

    2004-01-01

    Generally, friction and wear occur on the surface of the materials.It is necessary to investigate the dry sliding friction and wear behavior of surface.In this paper, 3-D topographical parameters were used to investigate the topographical characteristics of dry sliding surfaces for particle-reinforced aluminum composites on semi-metallic friction material.The experimental results indicate that the surface topography of the particle-reinforced aluminum composites can be divided into two types, the flaking-off pit type and the groove type.The composites whose surface topography is the flaking-off pit type possess superior heat conductivity and bearing area, lower wear rate, and higher friction coefficient than the groove type.Consequently, the flaking-off pit type surface topography is much better than the groove type for particle-reinforced aluminum composites on semi-metallic friction materials in dry sliding.

  15. Characterization of Vc-Vb Particles Reinforced Fe-Based Composite Coatings Produced by Laser Cladding

    Science.gov (United States)

    Qu, K. L.; Wang, X. H.; Wang, Z. K.

    2016-03-01

    In situ synthesized VC-VB particles reinforced Fe-based composite coatings were produced by laser beam melting mixture of ferrovanadium (Fe-V) alloy, boron carbide (B4C), CaF2 and Fe-based self-melting powders. The results showed that VB particles with black regular and irregular blocky shape and VC with black flower-like shape were uniformly distributed in the coatings. The type, amount, and size of the reinforcements were influenced by the content of FeV40 and B4C powders. Compared to the substrate, the hardness and wear resistance of the composite coatings were greatly improved.

  16. Mechanical and thermal properties of sodium silicate treated moso bamboo particles reinforced PVC composites

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The main objective of this research was to study the potential of sodium silicate modification on moso bamboo particles as reinforcements for thermoplastic. Moso bamboo particles were modified with sodium silicate aqueous solutions (of 0.5%, 1%, 2%, 5% and 10% concentrations). The mechanical properties of sodium silicate treated moso bamboo particles reinforced PVC composites (BPPC) were calculated and compared with raw bamboo particles filled samples. The thermal characteristics of the BPPC were studied to investigate the feasibility of sodium silicate treatment on moso bamboo particles. The particle morphology and BPPC microstructure were investigated by scanning electron microscopy. Results showed that the tensile strength and modulus of elasticity of the BPPC increased before the concentration of sodium silicate solution reached 5% and got their maximum values of 15.72 MPa and 2956.80 MPa, respectively at 5% concentration. The modulus of rupture obtained the maximum value of 27.73 MPa at 2% concentration. The mechanical curve decreased as the concentration of solution went higher. Differential scanning calorimetric analysis illustrated that the sodium silicate solution treated BPPC possesses a better compatibility. More uniform dispersion of moso bamboo particles in PVC matrix was obtained after the sodium silicate treatment. Hence, the sodium silicate was a feasible and competitive agent of creating moso bamboo particles reinforced PVC composites.

  17. Selected properties of the aluminium alloy base composites reinforced with intermetallic particles

    Directory of Open Access Journals (Sweden)

    M. Adamiak

    2005-12-01

    Full Text Available Purpose: The main aim of this work is to investigate two types of intermetallics TiAl and Ti3Al as reinforcement and their influence on selected properties and microstructure of aluminium matrix composites.Design/methodology/approach: Aluminium matrix composites were produced employing the atomised aluminium alloy AA6061 as metal matrix, when as reinforcement TiAl and Ti3Al intermetallics particles were used. The powders were cold pressed and then hot extruded. To evaluate the effect of mechanical milling two types of ball mills were used: a low energy (horizontal ball mill and a high energy one (eccentric ball mill. Reinforcement contents for both processes 5, 10, 15 % by weight. To determine hardness Vickers tests were performed. Microstructure observations were made by optical microscopy and scanning electron microscopy SEM.Findings: Based on the examinations carried out one can state that the mechanical milling can produce composites powders with homogenous distribution of reinforcement particles. The mechanically milled and extruded composites show finer and better distribution of reinforcement particles what leads to better mechanical properties of obtained products.Research limitations/implications: In order to evaluate with more detail the possibility of applying these composite materials at practical application, further investigations should be concentrated on the interface reaction of the matrix and reinforcing particles during elevated temperature exposition and their influence on mechanical properties.Practical implications: The composites materials produced by this way have shown significant improvement of the mechanical properties in comparision with matrix materials. Good properties of the composites make them suitable for various technical and industrial applications.Originality/value: It should be stressed that the materials as intermetallic compounds with outstanding mechanical properties and good thermal stability were

  18. Structure and properties of porous ceramic preforms made of α-alumina particles

    Directory of Open Access Journals (Sweden)

    J. W. Kaczmar

    2010-01-01

    Full Text Available Properties of ceramic preforms made of α-alumina particles for strengthening of metal based composite materials manufactured by squeeze casting are discussed in the paper. Composite materials strengthened with ceramic particles can be then plastically worked in order to remove the residual porosity and give the final net shape. There was investigated the permeability of porous preforms as the measure of the open porosity making possible the infiltration process with the molten metal, compression strength, bending strength and shear strength determining the stability of porous ceramic preforms during infiltration. Performed investigations allow to ascertain the occurrence of the open porosity in the porous preforms and strong effect of porosity on permeability. The largest permeability of 19 m2/Pa·s showed porous preforms characterized by porosity the of 90%. The strength properties increased with the decrease of preforms porosity and the prerforms characterized by 60% of porosity were characterized by the largest strength properties (bending strength Rg =7 MPa, compression strength Rc = 11.5 MPa, shear strength Rt = 4.0 MPa. The microscopic observations of fractures surfaces allow to evaluate quality and forming phenomena of the binder bridges connecting the ceramic particles.

  19. Computational Simulation of Continuous Fiber-Reinforced Ceramic Matrix Composites Behavior

    Science.gov (United States)

    Murthy, Pappu L. N.; Chamis, Christos C.; Mital, Subodh K.

    1996-01-01

    This report describes a methodology which predicts the behavior of ceramic matrix composites and has been incorporated in the computational tool CEMCAN (CEramic Matrix Composite ANalyzer). The approach combines micromechanics with a unique fiber substructuring concept. In this new concept, the conventional unit cell (the smallest representative volume element of the composite) of the micromechanics approach is modified by substructuring it into several slices and developing the micromechanics-based equations at the slice level. The methodology also takes into account nonlinear ceramic matrix composite (CMC) behavior due to temperature and the fracture initiation and progression. Important features of the approach and its effectiveness are described by using selected examples. Comparisons of predictions and limited experimental data are also provided.

  20. Thermal shock resistance of core reinforced all-ceramic crown systems.

    Science.gov (United States)

    Mora, G P; O'Brien, W J

    1994-02-01

    The coefficient of thermal expansion of core and veneer porcelains for all ceramic crowns must be compatible to prevent formation of stresses during the firing cycles. The purpose of this study was to use a thermal shock test to evaluate the crazing resistance of six all-ceramic crown systems. The systems tested were: Vita In-Ceram, Vita Hi-Ceram, Dicor veneered with Vitadur N, magnesia core veneered with Ceramco II, magnesia core veneered with Silhouette, and magnesia core veneered with Vita VMK 68. A maxillary central incisor was prepared with 1.0 mm axial and 1.5 mm incisal reduction. Refractory dies were prepared and crowns were fabricated using the manufacturers' recommendations. Six specimens of each system were placed inside a beaker in a furnace at 90 degrees C. After 15 min heat soak, ice water was poured into the beaker through a funnel. The samples were dried in air, reheated, and inspected for crazing using light microscopy. If crazing was observed, this would constitute a failure at a temperature difference (delta T) of 90 degrees C. If no failure occurred, the test was repeated at increasing temperature increments of 10 degrees C until failure. The crazing resistance of each system, expressed as the mean delta T, was: > 200 (Hi-Ceram), 163 +/- 14 (In-Ceram), 152 +/- 19 (Dicor/Vitadur N), 143 +/- 5 (magnesia core/Vita VMK 68), 122 +/- 21 (magnesia core/Silhouette), and 118 +/- 10 (magnesia core/Ceramco II) degrees C. All systems tested resisted crazing due to quenching in ice cold water from 100 degrees C. Systems with lower coefficients of expansion showed significantly greater resistance to thermal shock using ANOVA. PMID:8207030

  1. A New Technology of Microcrystallizing Leucite to Reinforce Dental Glass Ceramics

    Institute of Scientific and Technical Information of China (English)

    ZHANG Biao; PENG Bin; DUAN Xing-long; QIAN Fa-tang; WU Bo-lin

    2004-01-01

    The key technology and the main mechanism of microcrystallizing leucite to reirforce dentalglass ceramics were investigated. The feedstock powders were selected, mixed according to the ratios of the theoreti-cal composition of leucite, ball - milled, melted at 1600℃ and then cooled to room temperature quickly. Thecooled clinkers were ball - milled again to 4 μm. After cold - isostatic pressure molded and air sintered at 1 500℃for 1 h, the dental glass ceramics were fabricated. They have following characteristics: excellent mechanical prop-erties ( mean compressive strength is 206.6 MPa ), low sintering temperature and good reoccurrence to keep steadyquality.

  2. Study on Processing Conditions of Aluminum Matrix Composites Reinforced with Boron Carbide Particles

    Institute of Scientific and Technical Information of China (English)

    Fu Xueying; Zhang Hong; Xi Huizhi; Yi Xiaosu

    2004-01-01

    Different pre-heating of boron carbide particles for reinforcement and different processing conditions were studied in this work. Being one of the most cost-effective industrial methods, conventional melt stir-casting route was utilized.Result showed that the boron carbide particles distributed well for a suitable pre-heating temperature and processed in air.No reaction product was found at the A1-B4C interfaces at the resolution limit of SEM used in that way.

  3. Microstructure and hardness of WC-Co particle reinforced iron matrix surface composite

    OpenAIRE

    Zhang Peng; Zeng Shaolian; Zhang Zhiguo

    2013-01-01

    In this study, a high Cr cast iron surface composite material reinforced with WC-Co particles 2-6 mm in size was prepared using a pressureless sand mold infiltration casting technique. The composition, microstructure and hardness were determined by means of energy dispersive spectrometry (EDS), electron probe microanalysis (EPMA), scanning electron microscope (SEM) and Rockwell hardness measurements. It is determined that the obtained composite layer is about 15 mm thick with a WC-Co particle...

  4. Microstructure and hardness of WC-Co particle reinforced iron matrix surface composite

    Directory of Open Access Journals (Sweden)

    Zhang Peng

    2013-11-01

    Full Text Available In this study, a high Cr cast iron surface composite material reinforced with WC-Co particles 2-6 mm in size was prepared using a pressureless sand mold infiltration casting technique. The composition, microstructure and hardness were determined by means of energy dispersive spectrometry (EDS, electron probe microanalysis (EPMA, scanning electron microscope (SEM and Rockwell hardness measurements. It is determined that the obtained composite layer is about 15 mm thick with a WC-Co particle volumetric fraction of ~38%. During solidification, interface reaction takes place between WC-Co particles and high chromium cast iron. Melting and dissolving of prefabricated particles are also found, suggesting that local Co melting and diffusion play an important role in promoting interface metallurgical bonding. The composite layer is composed of ferrite and a series of carbides, such as (Cr, W, Fe23C6, WC, W2C, M6C and M12C. The inhomogeneous hardness in the obtained composite material shows a gradient decrease from the particle reinforced metal matrix composite layer to the matrix layer. The maximum hardness of 86.3 HRA (69.5 HRC is obtained on the particle reinforced surface, strongly indicating that the composite can be used as wear resistant material.

  5. A new system for posterior restorations: a combination of ceramic optimized polymer and fiber-reinforced composite.

    Science.gov (United States)

    Rosenthal, L; Trinkner, T; Pescatore, C

    1997-01-01

    Due to the need for increased strength characteristics and enhanced aesthetic expectations of the patients, metal-free, aesthetic restorative systems for the anterior and posterior dentition are currently available. A new "space-age" restorative material has been developed that is a combination of a ceramic optimized polymer (Ceromer) (Targis/Vectris, Ivoclar Williams, Amherst, NY) and a fiber-reinforced composite framework material. The purpose of this article is to discuss the qualities that render this material particularly suitable for a variety of indications, including laboratory-fabricated restorations for the stress-bearing posterior regions. The material lends itself to diversification. Its indication for inlays, onlays, full-coverage crown restorations, and conservative single pontic inlay bridges is presented.

  6. The Influence of Yttrium Isopropoxide on the Mechanical Properties of SiCW-reinforced AlN Ceramics

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    By using self-made metal-alkoxide yttrium isopropoxide as a sintering additive and disperser of whisker,the SiC whisker reinforced AlN ceramics was prepared.Its apparent density is 99.5 percent of the theoretical density;its flexural strength and fracture toughness are 681 MPa and 5.21 MPa*m1/2 respectively.Comparing the result with that by applying Y2O3 powder as a sintering additive,the flexural strength is increased by 25% and the fracture toughness is increased by 33%.The dispersity of whisker by increased yttrium isopropoxide is significantly better than that by Triton X-100.

  7. Coatings with laser melt injection of ceramic particles

    NARCIS (Netherlands)

    de Hosson, J.T.M.; Ocelik, V.; de Oliveira, U.; Seal, S; Dahotre, NB; Moore, JJ; Suryanarayana, C; Agarwal, A

    2003-01-01

    The conditions for a successful Laser Melt Injection (LMI) of SiC and WC particles into the melt pool of Al8Si and Ti6Al4V alloys were studied experimentally and theoretically by FEM calculations. The laser employed is a high power Nd:YAG The formation of a relatively thick aluminium oxide layer on

  8. Nanopore fabrication by heating au particles on ceramic substrates

    NARCIS (Netherlands)

    Vreede, de Lennart J.; Berg, van den Albert; Eijkel, Jan C.T.

    2015-01-01

    We found that gold nanoparticles, when heated to close to their melting point on substrates of amorphous SiO2 or amorphous Si3N4, move perpendicularly into the substrate. Dependent on applied temperatures, particles can become buried or leave nanopores of extreme aspect ratio (diameter congruent to

  9. Life Limiting Behavior in Interlaminar Shear of Continuous Fiber-Reinforced Ceramic Matrix Composites at Elevated Temperatures

    Science.gov (United States)

    Choi, Sung R.; Calomino, Anthony M.; Bansal, Narottam P.; Verrilli, Michael J.

    2006-01-01

    Interlaminar shear strength of four different fiber-reinforced ceramic matrix composites was determined with doublenotch shear test specimens as a function of test rate at elevated temperatures ranging from 1100 to 1316 C in air. Life limiting behavior, represented as interlaminar shear strength degradation with decreasing test rate, was significant for 2-D crossplied SiC/MAS-5 and 2-D plain-woven C/SiC composites, but insignificant for 2-D plain-woven SiC/SiC and 2-D woven Sylramic (Dow Corning, Midland, Michigan) SiC/SiC composites. A phenomenological, power-law delayed failure model was proposed to account for and to quantify the rate dependency of interlaminar shear strength of the composites. Additional stress rupture testing in interlaminar shear was conducted at elevated temperatures to validate the proposed model. The model was in good agreement with SiC/MAS-5 and C/SiC composites, but in poor to reasonable agreement with Sylramic SiC/SiC. Constant shear stress-rate testing was proposed as a possible means of life prediction testing methodology for ceramic matrix composites subjected to interlaminar shear at elevated temperatures when short lifetimes are expected.

  10. Behavior of osteoblast-like cells on calcium-deficient hydroxyapatite ceramics composed of particles with different shapes and sizes.

    Science.gov (United States)

    Kamitakahara, Masanobu; Uno, Yuika; Ioku, Koji

    2014-01-01

    In designing the biomaterials, it is important to control their surface morphologies, because they affect the interactions between the materials and cells. We previously reported that porous calcium-deficient hydroxyapatite (HA) ceramics composed of rod-like particles had advantages over sintered porous HA ceramics; however, the effects of the surface morphology of calcium-deficient HA ceramics on cell behavior have remained unclear. Using a hydrothermal process, we successfully prepared porous calcium-deficient HA ceramics with different surface morphologies, composed of plate-like particles of 200-300, 500-800 nm, or 2-3 μm in width and rod-like particles of 1 or 3-5 μm in width, respectively. The effects of these surface morphologies on the behavior of osteoblast-like cells were examined. Although the numbers of cells adhered to the ceramic specimens did not differ significantly among the specimens, the proliferation rates of cells on the ceramics decreased with decreasing particle size. Our results reveal that controlling the surface morphology that is governed by particle shape and size is important for designing porous calcium-deficient HA ceramics.

  11. The characteristics and application of sludge-fly ash ceramic particles (SFCP) as novel filter media

    International Nuclear Information System (INIS)

    Novel filter media-sludge-fly ash ceramic particles (SFCP) were prepared using dewatered sludge, fly ash and clay with a mass ratio of 1:1:1. Compared with commercial ceramic particles (CCP), SFCP had higher total porosity, larger total surface area and lower bulk and apparent density. Tests of heavy metal elements in lixivium proved that SFCP were safe for wastewater treatment. A lab-scale upflow anaerobic bioreactor was employed to ascertain the application of SFCP in denitrification process using acetate as carbon source. The results showed that SFCP reactor brought a relative superiority to CCP reactor in terms of total nitrogen (TN) removal at the optimum C/N ratio of 4.03 when volumetric loading rates (VLR) ranged from 0.33 to 3.69 kg TN (m3 d)-1. Therefore, SFCP application, as a novel process of treating wastes with wastes, provided a promising way in sludge and fly ash utilization.

  12. Fracture Toughness of Carbon Nanotube-Reinforced Metal- and Ceramic-Matrix Composites

    Directory of Open Access Journals (Sweden)

    Y. L. Chen

    2011-01-01

    Full Text Available Hierarchical analysis of the fracture toughness enhancement of carbon nanotube- (CNT- reinforced hard matrix composites is carried out on the basis of shear-lag theory and facture mechanics. It is found that stronger CNT/matrix interfaces cannot definitely lead to the better fracture toughness of these composites, and the optimal interfacial chemical bond density is that making the failure mode just in the transition from CNT pull-out to CNT break. For hard matrix composites, the fracture toughness of composites with weak interfaces can be improved effectively by increasing the CNT length. However, for soft matrix composite, the fracture toughness improvement due to the reinforcing CNTs quickly becomes saturated with an increase in CNT length. The proposed theoretical model is also applicable to short fiber-reinforced composites.

  13. Relationship Between Hysteresis Dissipated Energy and Temperature Rising in Fiber-Reinforced Ceramic-Matrix Composites Under Cyclic Loading

    Science.gov (United States)

    Longbiao, Li

    2016-06-01

    In this paper, the relationship between hysteresis dissipated energy and temperature rising of the external surface in fiber-reinforced ceramic-matrix composites (CMCs) during the application of cyclic loading has been analyzed. The temperature rise, which is caused by frictional slip of fibers within the composite, is related to the hysteresis dissipated energy. Based on the fatigue hysteresis theories considering fibers failure, the hysteresis dissipated energy and a hysteresis dissipated energy-based damage parameter changing with the increase of cycle number have been investigated. The relationship between the hysteresis dissipated energy, a hysteresis dissipated energy-based damage parameter and a temperature rise-based damage parameter have been established. The experimental temperature rise-based damage parameter of unidirectional, cross-ply and 2D woven CMCs corresponding to different fatigue peak stresses and cycle numbers have been predicted. It was found that the temperature rise-based parameter can be used to monitor the fatigue damage evolution and predict the fatigue life of fiber-reinforced CMCs.

  14. Microstructural analysis and mechanical characterization of aluminum matrix nanocomposites reinforced with uncoated and Cu-coated alumina particles

    International Nuclear Information System (INIS)

    Aluminum matrix composites used in the aerospace, military and automotive industries are typically fabricated by a stir casting method. However, when nanoparticles are used for reinforcement, fabrication of composite materials by this method leads to the formation of a large number of structural defects. In this study, copper coating of alumina reinforcement particles is investigated as a technique for improving the structure of Al-Al2O3 composites. Microstructural investigations by optical microscopy (OM), scanning electron microscopy (SEM) equipped with energy dispersion spectroscopy (EDS) and transmission electron microscopy (TEM) showed that the alumina particles were coated uniformly with copper shells. Copper coating of the reinforcing particles significantly increased their wettability in the molten aluminum alloy, strengthened the matrix-particle interfaces and improved the distribution of reinforcing particles within the matrix. Due to these microstructural improvements, the hardness, compressive strength, yield stress, tensile strength and elongation of the composites were enhanced by copper coating of the alumina particles

  15. Mechanical strength of ceramic scaffolds reinforced with biopolymers is comparable to that of human bone

    DEFF Research Database (Denmark)

    Henriksen, S S; Ding, M; Vinther Juhl, M;

    2011-01-01

    Eight groups of calcium-phosphate scaffolds for bone implantation were prepared of which seven were reinforced with biopolymers, poly lactic acid (PLA) or hyaluronic acid in different concentrations in order to increase the mechanical strength, without significantly impairing the microarchitecture...

  16. Effect of electroless coating parameters and ceramic particle size on fabrication of a uniform Ni–P coating on SiC particles

    OpenAIRE

    Beigi Khosroshahi, N.; Azari Khosroshahi, R.; Taherzadeh Mousavian, R.; Brabazon, Dermot

    2014-01-01

    The formation of a uniform nickel phosphorous (Ni–P) electroless (EL) coating on micronsized SiC particles was investigated in this study. Metal coated ceramic particles could be used in applications including as the fabrication of cast metal matrix composites.Such ceramic particles have a better wettability in molten metal. In this work, the effects of EL coating parameters, SiC particle size and morphology on the coating uniformity and mechanical bonding at the SiC/Ni–P interface were studi...

  17. Creep behavior on Ag particle reinforced SnCu based composite solder joints

    Institute of Scientific and Technical Information of China (English)

    YAN Yan-fu; ZHU Jin-hong; CHEN Fu-xiao; HE Jun-guang; YANG Di-xin

    2006-01-01

    SnCu solder is one of the most promising substitutes of SnPb solder, but its creep resistance is worse than that of the other lead-free solders. Particle-reinforcement is a way to improve the creep resistance of solder alloys and cause much more attention than before. A novel Ag particles reinforced SnCu based composite solder is formed and the influence of stress on creep behavior of the composite solder is investigated. Results indicate that the creep resistance of solder joints is superior to that of the SnCu solder joints. Creep rupture lifetime of solder joints decreases gradually with stress increasing. And the creep rupture lifetime of the composite solder joints falls down faster than that of the matrix solder joints.

  18. Human fetal bone cells associated with ceramic reinforced PLA scaffolds for tissue engineering

    OpenAIRE

    Montjovent, Marc-Olivier; Mark, Silke; Mathieu, Laurence; Scaletta, Corinne; Scherberich, Arnaud; Delabarde, Claire; Zambelli, Pierre-Yves; Bourban, Pierre-Etienne; Applegate, Lee Ann; Pioletti, Dominique P.

    2008-01-01

    Fetal bone cells were shown to have an interesting potential for therapeutic use in bone tissue engineering due to their rapid growth rate and their ability to differentiate into mature osteoblasts in vitro. We describe hereafter their capability to promote bone repair in vivo when combined with porous scaffolds based on poly(L-lactic acid) (PLA) obtained by supercritical gas foaming and reinforced with 5 wt% β-tricalcium phosphate (TCP). Bone regeneration was assessed by radiogra...

  19. Preparation and biocompatibility of poly (methyl methacrylate reinforced with bioactive particles

    Directory of Open Access Journals (Sweden)

    Pereira Marivalda de Magalhães

    2003-01-01

    Full Text Available Calcium phosphates and bioactive glasses have been used in many biomedical applications for more than 30 years due basically to their bioactive behavior. However, ceramics are too brittle for applications that require high levels of toughness and easy processability. In this work, a biphasic calcium phosphate (BCP and a bioactive glass composition (BG were combined with polymers to produce composites with tailorable properties and processability. The BCP particles were synthesized by a precipitation technique. The BG particles were produced by sol-gel processing. The BCP particles were treated with a silane agent to improve the compatibility between particles and the polymer matrix. Dense samples were produced by hot pressing (200 °C a mixture of 30 wt.% of particles in poly (methyl methacrylate. The samples produced were characterized by X-ray diffraction, infrared spectroscopy and scanning electron microscopy. Mechanical properties were evaluated by a three point bending test. Samples were also submitted to in vitro bioactivity test and in vivo toxicity test. Results showed that the production of the composites was successfully achieved, yielding materials with particles well dispersed within the matrices. Evaluation of the in vivo inflammatory response showed low activity levels for all composites although composites with silane treated BCP particles led to milder inflammatory responses than composites with non-treated particles.

  20. Cavitation-erosion mechanism of laser cladded SiC particle reinforced metal matrix composite

    Institute of Scientific and Technical Information of China (English)

    ZHANG Chun-hua; ZHANG Song; YANG Hong-gang; ZHU Sheng-long; MAN Hau-chung; CAI Qing-kui

    2005-01-01

    With 2 kW continuous wave Nd-YAG laser,SiC ceramic powder was laser-cladded on the AA6061 aluminium alloy surface.Within the range of process parameters investigated,the parameters were optimized to produce the SiCp reinforced metal matrix composites(MMC) modified layer on AA6061 alloy surface.After being treated,the modified layer is crack-free,porosity free,and has good metallurgical bond with the substrate.The microstructure and chemical composition of the modified layer were analyzed by such detection devices as scanning electronic microscope(SEM-EDX) and X-ray diffractometer(XRD).The performance of electrochemical corrosion and cavitation erosion and their mechanism were estimated by the microhardness tester,potentiostat and ultrasonicinduced cavitation device.

  1. Experimental Investigation into Shaping Particle-reinforced Material by WEDM-H

    Institute of Scientific and Technical Information of China (English)

    T; M; Yue

    2002-01-01

    Al 2O 3 particle-reinforced material (6061 alloy ), which is one of new composites and characterized by high strength and small spe cific gravity, good wear resistance and corrosion resistance, has been widel y used in industry. But it is difficult to machine. Because of electric conducti vity, it can be shaped and processed by electro-machining means. However, this kind of material is mixed with the electrically conductive substances and the di electrically conductive substances, its machining proces...

  2. Research on Vibration Cutting Performance of Particle Reinforced Metallic Matrix Composites SiC_p/Al

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The cutting performance of particle reinforced meta ll ic matrix composites (PRMMCs) SiC p/Al in ultrasonic vibration cutting and comm on cutting with carbide tools and PCD tools was experimentally researched in the paper. The changing rules of chip shape, deformation coefficient, shear angle a nd surface residual stress were presented by ultrasonic vibration cutting. Resul ts show: when adopting common cutting, spiral chip with smaller curl radius will be obtained. The chip with zigzag contour is short ...

  3. In-flight behavior of dissimilar co-injected particles in the spraying of metal-ceramic functionally gradient materials

    Energy Technology Data Exchange (ETDEWEB)

    Fincke, J.R.; Swank, W.D.; Haggard, D.C. [Idaho National Engineering Lab., Idaho Falls, ID (United States)

    1997-12-31

    In the spraying of functionally gradient coatings the particle ensemble delivered to the substrate can vary from a relatively low melting point metallic particle to a significantly higher melting point ceramic particle. At various stages in the spray process the particle ensemble can be either predominantly metallic, ceramic, or an intermediate combination. For co-injected particles the mixtures do not behave as a simple linear superposition of the spray patterns of the individual particle types. The particle temperature, velocity, size distributions, and pattern characteristics of the resulting spray fields is examined for all ceramic particle sprays (ZrO{sub 2}), all metallic particle sprays (NiCrAlY), and for a 1:1 mixture. The major particle-particle interaction occurs in the injector itself and results in a modified spray pattern which is different from that of either material sprayed alone. The particle velocity distributions generally exhibit a bimodal nature which is dependent on the size and density of the injected particles.

  4. Flexible high-loading particle-reinforced polyurethane magnetic nanocomposite fabrication through particle-surface-initiated polymerization

    Science.gov (United States)

    Guo, Zhanhu; Park, Sung; Wei, Suying; Pereira, Tony; Moldovan, Monica; Karki, Amar B.; Young, David P.; Hahn, H. Thomas

    2007-08-01

    Flexible high-loading nanoparticle-reinforced polyurethane magnetic nanocomposites fabricated by the surface-initiated polymerization (SIP) method are reported. Extensive field emission scanning electron microscopic (SEM) and atomic force microscopic (AFM) observations revealed a uniform particle distribution within the polymer matrix. X-ray photoelectron spectrometry (XPS) and differential thermal analysis (DTA) revealed a strong chemical bonding between the nanoparticles and the polymer matrix. The elongation of the SIP nanocomposite under tensile test was about four times greater than that of the composite fabricated by a conventional direct mixing fabrication method. The nanocomposite shows particle-loading-dependent magnetic properties, with an increase of coercive force after the magnetic nanoparticles were embedded into the polymer matrix, arising from the increased interparticle distance and the introduced polymer-particle interactions.

  5. Flexible high-loading particle-reinforced polyurethane magnetic nanocomposite fabrication through particle-surface-initiated polymerization

    International Nuclear Information System (INIS)

    Flexible high-loading nanoparticle-reinforced polyurethane magnetic nanocomposites fabricated by the surface-initiated polymerization (SIP) method are reported. Extensive field emission scanning electron microscopic (SEM) and atomic force microscopic (AFM) observations revealed a uniform particle distribution within the polymer matrix. X-ray photoelectron spectrometry (XPS) and differential thermal analysis (DTA) revealed a strong chemical bonding between the nanoparticles and the polymer matrix. The elongation of the SIP nanocomposite under tensile test was about four times greater than that of the composite fabricated by a conventional direct mixing fabrication method. The nanocomposite shows particle-loading-dependent magnetic properties, with an increase of coercive force after the magnetic nanoparticles were embedded into the polymer matrix, arising from the increased interparticle distance and the introduced polymer-particle interactions

  6. Modification of Magnesium Alloys by Ceramic Particles in Gravity Die Casting

    Directory of Open Access Journals (Sweden)

    Urs Haßlinger

    2014-01-01

    Full Text Available A critical drawback for the application of magnesium wrought alloys is the limited formability of semifinished products that arises from a strong texture formation during thermomechanical treatment. The ability of second phase particles embedded into the metal matrix to alter this texture evolution is of great interest. Therefore, the fabrication of particle modified magnesium alloys (particle content 0.5–1 wt.-% by gravity die casting has been studied. Five different types of micron sized ceramic powders (AlN, MgB2, MgO, SiC, and ZrB2 have been investigated to identify applicable particles for the modification. Agglomeration of the particles is revealed to be the central problem for the fabrication process. The main factors that influence the agglomerate size are the particle size and the intensity of melt stirring. Concerning handling, chemical stability in the Mg-Al-Zn alloy system, settling and wetting in the melt, and formation of the microstructure in most cases, the investigated powders show satisfying properties. However, SiC is chemically unstable in aluminum containing alloys. The high density of ZrB2 causes large particles to settle subsequent to stirring resulting in an inhomogeneous distribution of the particles over the cast billet.

  7. Deformation behavior of SiC particle reinforced Al matrix composites based on EMA model

    Institute of Scientific and Technical Information of China (English)

    CHENG Nan-pu; ZENG Su-min; YU Wen-bin; LIU Zhi-yi; CHEN Zhi-qian

    2007-01-01

    Effects of the matrix properties, particle size distribution and interfacial matrix failure on the elastoplastic deformation behavior in Al matrix composites reinforced by SiC particles with an average size of 5 μm and volume fraction of 12% were quantitatively calculated by using the expanded effective assumption(EMA) model. The particle size distribution naturally brings about the variation of matrix properties and the interfacial matrix failure due to the presence of SiC particles. The theoretical results coincide well with those of the experiment. The current research indicates that the load transfer between matrix and reinforcements, grain refinement in matrix, and enhanced dislocation density originated from the thermal mismatch between SiC particles and Al matrix increase the flow stress of the composites, but the interfacial matrix failure is opposite. It also proves that the load transfer, grain refinement and dislocation strengthening are the main strengthening mechanisms, and the interfacial matrix failure and ductile fracture of matrix are the dominating fracture modes in the composites. The mechanical properties of the composites strongly depend on the metal matrix.

  8. Modeling of Size-Dependent Strengthening in Particle-Reinforced Aluminum Composites with Strain Gradient Plasticity

    International Nuclear Information System (INIS)

    This study proposes finite element modeling of dislocation punching at cooling after consolidation in order to calculate the strength of particle-reinforced aluminum composites. The Taylor dislocation model combined with strain gradient plasticity around the reinforced particle is adopted to take into account the size-dependency of different volume fractions of the particle. The strain gradients were obtained from the equivalent plastic strain calculated during the cooling of the spherical unit cell, when the dislocation punching due to CTE (Coefficient of Thermal Expansion) mismatch is activated. The enhanced yield stress was observed by including the strain gradients, in an average sense, over the punched zone. The tensile strength of the SiCp/Al 356-T6 composite was predicted through the finite element analysis of an axisymmetric unit cell for various sizes and volume fractions of the particle. The predicted strengths were found to be in good agreement with the experimental data. Further, the particle-size dependency was clearly established

  9. Enhancement of Compatibility between Ultrahigh-Molecular-Weight Polyethylene Particles and Butadiene.Nitrile Rubber Matrix with Nanoscale Ceramic Particles and Characterization of Evolving Layer

    Energy Technology Data Exchange (ETDEWEB)

    Shadrinov, Nikolay V.; Sokolova, Marina D.; Cho, Jinho [Institute of Oil and Gas Issues, Yakutsk (Russian Federation); Okhlopkova, A. A. [North-Eastern Federal Univ., Yakutsk (Russian Federation); Lee, Jungkeun; Jeong, Daeyong [Myongji Univ., Seoul (Korea, Republic of)

    2013-12-15

    This article examines the modification of surface properties of ultrahigh-molecular-weight polyethylene (UHMWPE) with nanoscale ceramic particles to fabricate an improved composite with butadiene.nitrile rubber (BNR). Adhesion force data showed that ceramic zeolite particles on the surface of UHMWPE modulated the surface state of the polymer and increased its compatibility with BNR. Atomic force microscopy phase images showed that UHMWPE made up the microphase around the zeolite particles and formed the evolving layer with a complex interface. The complex interface resulted in improvements in the mechanical properties of the composite, especially its low-temperature resistance coefficients, thereby improving its performance in low-temperature applications.

  10. Microstructural characterization and mechanical properties of self-reinforced Si3N4 ceramics containing high oxynitride glass

    Institute of Scientific and Technical Information of China (English)

    Xuetao Luo; Lifu Chen; Qianjun Huang; Litong Zhang

    2004-01-01

    Self-reinforced Si3N4 ceramics containing high oxynitride glass have been fabricated by the control of microstructure evolution and a-Si3N4 grain growth. The effects of the size distribution of the elongated a-Si3N4 grains, and the a-Si3N4 grain growth as well as the oxynitride glass chemical characteristic on the microstructure and mechanical properties were investigated. The experimental results show that the a-Si3N4 grains in high oxynitride glass grow to elongated rod-like crystals and form the stereo-network structure. Under the sintering conditions of 1800℃ and 60 min, a quite uniform microstructure with an average aspect ratio of 6.5temperature fracture toughness because of its high softening temperature and high viscosity. In the present material, the crack deflection and pullout of the elongated rod-like a-Si3N4 grains are the primary toughening mecl anisms.

  11. Fatigue Life Prediction of Fiber-Reinforced Ceramic-Matrix Composites with Different Fiber Preforms at Room and Elevated Temperatures

    Directory of Open Access Journals (Sweden)

    Longbiao Li

    2016-03-01

    Full Text Available In this paper, the fatigue life of fiber-reinforced ceramic-matrix composites (CMCs with different fiber preforms, i.e., unidirectional, cross-ply, 2D (two dimensional, 2.5D and 3D CMCs at room and elevated temperatures in air and oxidative environments, has been predicted using the micromechanics approach. An effective coefficient of the fiber volume fraction along the loading direction (ECFL was introduced to describe the fiber architecture of preforms. The statistical matrix multicracking model and fracture mechanics interface debonding criterion were used to determine the matrix crack spacing and interface debonded length. Under cyclic fatigue loading, the fiber broken fraction was determined by combining the interface wear model and fiber statistical failure model at room temperature, and interface/fiber oxidation model, interface wear model and fiber statistical failure model at elevated temperatures, based on the assumption that the fiber strength is subjected to two-parameter Weibull distribution and the load carried by broken and intact fibers satisfies the Global Load Sharing (GLS criterion. When the broken fiber fraction approaches the critical value, the composites fatigue fracture.

  12. Modeling for Fatigue Hysteresis Loops of Carbon Fiber-Reinforced Ceramic-Matrix Composites under Multiple Loading Stress Levels

    Science.gov (United States)

    Longbiao, Li

    2015-12-01

    In this paper, the fatigue hysteresis loops of fiber-reinforced ceramic-matrix composites (CMCs) under multiple loading stress levels considering interface wear has been investigated using micromechanical approach. Under fatigue loading, the fiber/matrix interface shear stress decreases with the increase of cycle number due to interface wear. Upon increasing of fatigue peak stress, the interface debonded length would propagate along the fiber/matrix interface. The difference of interface shear stress existed in the new and original debonded region would affect the interface debonding and interface frictional slipping between the fiber and the matrix. Based on the fatigue damage mechanism of fiber slipping relative to matrix in the interface debonded region upon unloading and subsequent reloading, the interface slip lengths, i.e., the interface debonded length, interface counter-slip length and interface new-slip length, are determined by fracture mechanics approach. The fatigue hysteresis loops models under multiple loading stress levels have been developed. The effects of single/multiple loading stress levels and different loading sequences on fatigue hysteresis loops have been investigated. The fatigue hysteresis loops of unidirectional C/SiC composite under multiple loading stress levels have been predicted.

  13. Modeling the Effect of Oxidation on Tensile Strength of Carbon Fiber-Reinforced Ceramic-Matrix Composites

    Science.gov (United States)

    Longbiao, Li

    2015-12-01

    An analytical method has been developed to investigate the effect of oxidation on the tensile strength of carbon fiber - reinforced ceramic - matrix composites (CMCs). The Budiansky - Hutchinson - Evans shear - lag model was used to describe the micro stress field of the damaged composite considering fibers failure. The statistical matrix multicracking model and fracture mechanics interface debonding criterion were used to determine the matrix crack spacing and interface debonded length. The fiber strength degradation model and oxidation region propagation model have been adopted to analyze the oxidation effect on tensile strength of the composite, which is controlled by diffusion of oxygen gas through matrix cracks. Under tensile loading, the fibers failure probabilities were determined by combining oxidation model and fiber statistical failure model based on the assumption that fiber strength is subjected to two-parameter Weibull distribution and the loads carried by broken and intact fibers statisfy the global load sharing criterion. The composite can no longer support the applied load when the total loads supported by broken and intact fibers approach its maximum value. The conditions of a single matrix crack and matrix multicrackings for tensile strength considering oxidation time and temperature have been analyzed.

  14. Solid ceramic SiCO microspheres and porous rigid siloxane microspheres from swellable polysiloxane particles

    International Nuclear Information System (INIS)

    Solid silicon oxycarbide (SiCO) ceramic microspheres and rigid porous siloxane microspheres were obtained in a two step process. First, polysiloxane microspheres with a large number of Si–OH groups in their bulk and on their surface were synthesized from polyhydromethylsiloxane (PHMS) using a recently developed process. The process included a combination of three reactions of Si–H groups of PHMS occurring in aqueous emulsion and catalyzed by the same Karstedt Pt(0) complex: (i) hydrosilylation of 1,3-divinyltetramethyldisiloxane (DVTMDS), (ii) hydrolysis, (iii) dehydrogenocondensation involving the SiOH groups formed during the hydrolysis. DVTMDS was grafted on PHMS prior to emulsification. Microspheres had a loose structure and were able to absorb a significant amount of organic solvents. In the second step the microspheres were subjected to pyrolysis with heating in the argon atmosphere at following temperatures: 400, 700 and 1000 °C. These heated at 400 °C had micro and mezopores, while those heated at 700 and 1000 °C gave spherical solid SiCO ceramic particles. Polysiloxane microspheres and microspheres obtained by pyrolysis of the former were analyzed by 29Si and 13C MAS NMR, FTIR, SEM, and N2 gas adsorption. - Highlights: • Thermal properties of cross-linked polysiloxane microspheres are studied. • New route to solid silicon oxycarbide microspheres is worked out. • New method of preparation of mezoporous siloxane microspheres is shown. • Role of silanol side groups on polysiloxane in its ceramization is explained

  15. Mechanical and thermal properties of phthalonitrile resin reinforced with silicon carbide particles

    International Nuclear Information System (INIS)

    Highlights: • SiC microparticles improve the mechanical properties of phthalonitrile resin. • Excellent thermal stability achieved by adding SiC particles in phthalonitrile resin. • Adding 20 wt.% of SiC microparticles increases the Tg by 38 °C. • Silane coupling agent can enhance the adhesion and dispersion of particles/matrix. - Abstract: A new type of composite based on phthalonitrile resin reinforced with silicon carbide (SiC) microparticles was prepared. For various weight ratios ranging between 0% and 20%, the effect of the micro-SiC particles on the mechanical and thermal properties has been studied. Results from thermal analysis revealed that the starting decomposition temperature and the residual weight were significantly improved upon adding the reinforcing phase. At the maximum micro-SiC loading, dynamic mechanical analysis (DMA) showed an important enhancement in both the storage modulus and glass transition temperature (Tg), reaching 3.1 GPa and 338 °C, respectively. The flexural strength and modulus as well as the microhardness were significantly enhanced by adding the microfillers. Tensile test revealed enhancements in the composites toughness upon adding the microparticles. Polarization optical microscope (POM) and scanning electron microscope (SEM) analysis confirmed that mechanical and thermal properties improvements are essentially attributed to the good dispersion and adhesion between the particles and the resin

  16. Progressive failure processes of reinforced slopes based on general particle dynamic method

    Institute of Scientific and Technical Information of China (English)

    赵毅; 周小平; 钱七虎

    2015-01-01

    In order to resolve grid distortions in finite element method (FEM), the meshless numerical method which is called general particle dynamics (GPD) was presented to simulate the large deformation and failure of geomaterials. The Mohr-Coulomb strength criterion was implemented into the code to describe the elasto-brittle behaviours of geomaterials while the solid-structure (reinforcing pile) interaction was simulated as an elasto-brittle material. The Weibull statistical approach was applied to describing the heterogeneity of geomaterials. As an application of general particle dynamics to slopes, the interaction between the slopes and the reinforcing pile was modelled. The contact between the geomaterials and the reinforcing pile was modelled by using the coupling condition associated with a Lennard-Jones repulsive force. The safety factor, corresponding to the minimum shear strength reduction factor “R”, was obtained, and the slip surface of the slope was determined. The numerical results are in good agreement with those obtained from limit equilibrium method and finite element method. It indicates that the proposed geomaterial-structure interaction algorithm works well in the GPD framework.

  17. Analysis of Self-Adhesive Resin Cement Microshear Bond Strength on Leucite-Reinforced Glass-Ceramic with/without Pure Silane Primer or Universal Adhesive Surface Treatment

    Directory of Open Access Journals (Sweden)

    Yoon Lee

    2015-01-01

    Full Text Available Objective. To evaluate the microshear bond strength (μSBS of self-adhesive resin (SA cement on leucite-reinforced glass-ceramic using silane or universal adhesive. Materials and Methods. Ceramic blocks were etched with 9.5% hydrofluoric acid and divided into three groups (n=16: (1 negative control (NC without treatment; (2 Single Bond Universal (SBU; (3 RelyX Ceramic Primer as positive control (PC. RelyX Unicem resin cement was light-cured, and μSBS was evaluated with/without thermocycling. The μSBS was analyzed using one-way analysis of variance. The fractured surfaces were examined using stereomicroscopy and scanning electron microscopy (SEM. Results. Without thermocycling, μSBS was highest for PC (30.50 MPa ± 3.40, followed by SBU (27.33 MPa ± 2.81 and NC (20.18 MPa ± 2.01 (P0.05. PC and NC predominantly fractured by cohesive failure within the ceramic and mixed failure, respectively. Conclusion. SBU treatment improves μSBS between SA cement and glass ceramics, but to a lower value than PC, and the improvement is eradicated by thermocycling. NC exhibited the lowest μSBS, which remained unchanged after thermocycling.

  18. Analysis of Self-Adhesive Resin Cement Microshear Bond Strength on Leucite-Reinforced Glass-Ceramic with/without Pure Silane Primer or Universal Adhesive Surface Treatment

    Science.gov (United States)

    Lee, Yoon; Kim, Jae-Hoon; Woo, Jung-Soo; Yi, Young-Ah; Hwang, Ji-Yun; Seo, Deog-Gyu

    2015-01-01

    Objective. To evaluate the microshear bond strength (μSBS) of self-adhesive resin (SA) cement on leucite-reinforced glass-ceramic using silane or universal adhesive. Materials and Methods. Ceramic blocks were etched with 9.5% hydrofluoric acid and divided into three groups (n = 16): (1) negative control (NC) without treatment; (2) Single Bond Universal (SBU); (3) RelyX Ceramic Primer as positive control (PC). RelyX Unicem resin cement was light-cured, and μSBS was evaluated with/without thermocycling. The μSBS was analyzed using one-way analysis of variance. The fractured surfaces were examined using stereomicroscopy and scanning electron microscopy (SEM). Results. Without thermocycling, μSBS was highest for PC (30.50 MPa ± 3.40), followed by SBU (27.33 MPa ± 2.81) and NC (20.18 MPa ± 2.01) (P 0.05). PC and NC predominantly fractured by cohesive failure within the ceramic and mixed failure, respectively. Conclusion. SBU treatment improves μSBS between SA cement and glass ceramics, but to a lower value than PC, and the improvement is eradicated by thermocycling. NC exhibited the lowest μSBS, which remained unchanged after thermocycling. PMID:26557660

  19. Characterization of aluminium matrix composites reinforced by Al–Cu–Fe quasicrystalline particles

    Energy Technology Data Exchange (ETDEWEB)

    Lityńska-Dobrzyńska, L.; Dutkiewicz, J.; Stan-Głowińska, K.; Wajda, W. [Institute of Metallurgy and Materials Science Polish Academy of Sciences, 30-059 Kraków, 25 Reymonta St. (Poland); Dembinski, L.; Langlade, C.; Coddet, C. [Universite de Technologie de Belfort-Montbeliard, Site de Sevenans 90010, Belfort (France)

    2015-09-15

    Highlights: • Al powder and atomised Al{sub 65}Cu{sub 20}Fe{sub 15} powder were consolidated by vacuum hot pressing. • No changes in microstructure of Al{sub 65}Cu{sub 20}Fe{sub 15} powder in 20% and 40% composites. • Al{sub 2}Cu precipitates at the interfaces and inside the matrix in the 60% composite. • Increase of microhardness and compressive strength with content of reinforcement. • The friction coefficient were in the range 0.5–0.7. - Abstract: Aluminium matrix composites were consolidated from elemental Al powder and atomised Al{sub 65}Cu{sub 20}Fe{sub 15} particles by vacuum hot pressing technique. The spherical Al{sub 65}Cu{sub 20}Fe{sub 15} particles consisted of icosahedral quasicrystalline dendrites or cells and cubic τ-AlCu(Fe) phase located in interdendritic areas. The composites with different content of the reinforcement particles (20, 40 and 60 wt%) were prepared. All composites showed density about 99% and a good bonding between the Al{sub 65}Cu{sub 20}Fe{sub 15} particles and the matrix. It was shown that the phase composition of the atomised particles did not change after consolidation for the composite containing 20% and 40% added particles while Al{sub 2}Cu precipitates formed at the Al/Al{sub 65}Cu{sub 20}Fe{sub 15} interfaces and inside the matrix in the composite with 60% of Al{sub 65}Cu{sub 20}Fe{sub 15} particles. With the increase of the volume fraction of the reinforcement in the composite the hardness as well as compressive strength increased reaching the value of 173 HV{sub 0.5} and 370 MPa, respectively for 60% of Al{sub 65}Cu{sub 20}Fe{sub 15} particles. The friction coefficient slightly varied in the range 0.5–0.7 depending on the composition.

  20. Precipitation Sequence of a SiC Particle Reinforced Al-Mg-Si Alloy Composite

    Science.gov (United States)

    Shen, Rujuan; Wang, Yihan; Guo, Baisong; Song, Min

    2016-10-01

    In this study, the precipitation sequence of a 5 vol.% SiC particles reinforced Al-1.12 wt.%Mg-0.77 wt.%Si alloy composite fabricated by traditional powder metallurgy method was investigated by transmission electron microscopy and hardness measurements. The results indicated that the addition of SiC reinforcements not only suppresses the initial aging stage but also influences the subsequent precipitates. The precipitation sequence of the composite aged at 175 °C can be described as: Guinier-Preston (G.P.) zone → β″ → β' → B', which was confirmed by high-resolution transmission electron microscopy. This work might provide the guidance for the design and fabrication of hardenable automobile body sheet by Al-based composites with enhanced mechanical properties.

  1. Reinforced magnetic properties of Ni-doped BiFeO3 ceramic

    CERN Document Server

    Hwang, J S; Kang, J -H; Lee, K H; Lee, B W; Park, S Y; Lee, Y P

    2016-01-01

    Multiferroic materials attract considerable interest because of the wide range of potential applications such as spintronic devices, data storage and sensors. As a strong candidate for the applications among the limited list of single-phase multiferroic materials, BiFeO3 (BFO) is a quite attractive material due to its multiferroic properties at room temperature (RT). However, BFO is widely known to have large leakage current and small spontaneous polarization due to the existence of crystalline defects such as oxygen vacancies. Furthermore, the magnetic moment of pure BFO is very weak owing to its antiferromagnetic nature. In this paper, the effects of Ni2+ substitution on the magnetic properties of bulk BFO have been investigated. BFO, and BiFe0.99Ni0.01O3, BiFe0.98Ni0.02O3 and BiFe0.97Ni0.03O3 (BFNO: Ni-doped BFO) ceramics were prepared by solid-state reaction and rapid sintering, and analyzed by structural and magnetic-property measurements. The leakage current density was measured at RT by using a standar...

  2. Reinforced magnetic properties of Ni-doped BiFeO3 ceramic

    Science.gov (United States)

    Hwang, J. S.; Yoo, Y. J.; Lee, Y. P.; Kang, J.-H.; Lee, K. H.; Lee, B. W.; Park, S. Y.

    2016-08-01

    Multiferroic materials attract considerable interest because of the wide range of potential applications such as spintronic devices, data storage devices and sensors. As a strong candidate for the applications among the limited list of single-phase multiferroic materials, BiFeO3 (BFO) is a quite attractive material due to its multiferroic properties at room temperature (RT). However, BFO is widely known to have large leakage current and small spontaneous polarization due to the existence of crystalline defects such as oxygen vacancies. Furthermore, the magnetic moment of pure BFO is very weak owing to its antiferromagnetic nature. In this paper, the effects of Ni2+ substitution on the magnetic properties of bulk BFO were investigated. BFO, and BiFe0.99Ni0.01O3, BiFe0.98Ni0.02O3 and BiFe0.97Ni0.03O3 (BFNO: Ni-doped BFO) ceramics were prepared by solid-state reaction and rapid sintering, and analyzed by structural and magnetic-property measurements. The leakage current density was measured at RT by using a standard ferroelectric tester. All the Ni-doped BFO samples exhibited the similar rhombohedral perovskite structure ( R3c) to that of BFO. The magnetic properties of Ni-doped BFO were much enhanced with respect to BFO prepared at the same conditions, because the enhanced ferromagnetic interaction is caused by the Fe/Ni coupling.

  3. Prediction of fracture characteristic of particle-reinforced alumina-based composites

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Residual microstresses in particle reinforced alumina/SiC and alumina/mullite composites were calcu- lated. The results indicated that there existed a linear relation between matrix microstresses and the particle contents in the composites. The influence of stress state on crack propagating and grain boundary strengthening was analyzed. Ratios of grain boundary toughness to grain toughness of these composites were calculated in view of microstress analysis, and percentage of transgranular fracture (PTF) that increases with the microstress in the alumina matrix was then deduced. The relationship between microstructure, component, matrix microstresses, and PTF was established. Therefore, the fracture characteristic was predicted on basis of the particle content and distribution in addition to the microstructure of the composites.

  4. Large Scale FEM of the effective elastic properties of particle reinforced composites

    DEFF Research Database (Denmark)

    Rauhe, Jens Christian; Pyrz, Ryszard; Lund, Erik

    2004-01-01

    three-dimensional finite element models of the microstructure. The models contain a large number of elements, up to 1 million, and are solved iteratively using an element-by-element formalism. Models containing 100 particles have been statistically generated and the material properties of each particle......Over the years several methods have been proposed for the determination of the effective elastic properties of particle reinforced composites. The material microstructures used in the present analysis is a real microstructure and a numerically generated microstructure. X-ray microtomography is used...... to determine the material microstructure and with this method the interior microstructure is determined in a non-destructive way. Using the commercially available equipment, SkyScan 1072, the maximum resolution is approximately 5 microns. The data obtained from the tomographic examination is used to generate...

  5. Specimen Preparation for Metal Matrix Composites with a High Volume Fraction of Reinforcing Particles for EBSD Analysis

    Science.gov (United States)

    Smirnov, A. S.; Belozerov, G. A.; Smirnova, E. O.; Konovalov, A. V.; Shveikin, V. P.; Muizemnek, O. Yu.

    2016-07-01

    The paper deals with a procedure of preparing a specimen surface for the EBSD analysis of a metal matrix composite (MMC) with a high volume fraction of reinforcing particles. Unlike standard procedures of preparing a specimen surface for the EBSD analysis, the proposed procedure is iterative with consecutive application of mechanical and electrochemical polishing. This procedure significantly improves the results of an indexed MMC matrix in comparison with the standard procedure of specimen preparation. The procedure was verified on a MMC with pure aluminum (99.8% Al) as the matrix, SiC particles being used as reinforcing elements. The average size of the SiC particles is 14 μm, and their volume fraction amounts to 50% of the total volume of the composite. It has been experimentally found that, for making the EBSD analysis of a material matrix near reinforcing particles, the difference in height between the particles and the matrix should not exceed 2 µm.

  6. The high frequency fatigue behavior of continuous-fiber-reinforced ceramic matrix composites

    Science.gov (United States)

    Chawla, Nikhilesh

    Many potential applications for continuous fiber ceramic matrix composites (CFCMCs), such as gas turbines and heat exchangers, will involve high frequency cyclic loading (75 Hz or higher). While most of the work in the area of fatigue of CFCMCs has concentrated on low frequency behavior, it has been shown that fatigue at high frequencies can exacerbate the accumulation of microstructural damage and significantly decrease fatigue life. "Soft" matrix composites with strong interface bonding provided superior resistance to high frequency fatigue damage. Nicalon/SiCON composites with strong interfacial bonding between the fibers and matrix exhibited very little internal heating during high frequency fatigue loading. This composite system exhibited excellent fatigue life, with fatigue runout at 10sp7 cycles occurring for stresses close to 80% of the ultimate strength (at a loading frequency of 100 Hz). Thick fiber coatings may be more effective in reducing the amount of fiber wear and damage which occur during high frequency fatigue. More effective lubrication at the fiber/matrix interface was achieved with thicker carbon coatings in Nicalon/C/SiC composites subjected to high frequency fatigue loading. Composites with thicker coatings exhibited substantially lower frictional heating and had much higher fatigue lives. The effect of laminate stacking sequence had a significant effect on the high frequency fatigue behavior of CFCMCs. In SCS-6/Sisb3Nsb4 composites, frictional heating in angle-ply laminates (±45) was substantially higher than that in cross-ply laminates (0/90). Since the angle-ply had a lower stiffness, matrix microcracking in this composite was more predominant. Finally, preliminary fatigue damage mechanism maps for CFCMCs were developed. These maps provided a means to identify which fatigue mechanisms were operating at a given stress level and number of cycles.

  7. Effect of mechanical and thermal loading on boron carbide particles reinforced Al-6061 alloy

    Energy Technology Data Exchange (ETDEWEB)

    Manjunatha, B., E-mail: manjunathab.ait@gmail.com [Department of Mechanical Engineering, Acharya Institute of Technology, Soldevanahalli, Hesaraghatta Main Road, Bangalore 560090 (India); Niranjan, H.B., E-mail: girija_hb@hotmail.com [Department of Mechanical Engineering, Sambhram Institute of Technology, Lakshmipura Cross, MS Palya, Jalahalli East, Bangalore 560097 (India); Satyanarayana, K.G., E-mail: gundsat42@hotmail.com [Poornaprajna Institute of Scientific Research (PPISR), Sy. No. 167, Poornaprajnapura, Bidalur Post, Devanahalli, Bangalore 562110, Karnataka (India)

    2015-04-24

    Metal Matrix Composites (MMC) considered as one of the ‘advanced materials’ have evoked growing interest during the last three decades due to their high performance and applications in strategic sectors. These composites exhibit unique and attractive properties over the monolithic alloys, but suffer from low ductility, which makes them not so attractive for some of the applications where high toughness is one of the design criteria. This limitation of MMCs has been overcome by resorting to various treatments such as mechanical and thermal loading. Considering very limited reports available on Al alloy reinforced with boron carbide (B{sub 4}C) particles, this paper presents (i) preparation of Al-6061 alloy reinforced with 1.5–10 wt% B{sub 4}C, (ii) subjecting them to mechanical and thermal treatments and (iii) characterization of all the above samples. Specific ultimate tensile strength and hardness of all the composites were higher than those of matrix. Also, these values increased with increasing amount of particles, with composites containing 8 wt% B{sub 4}C showing the maximum values in all the three conditions. These observations are supported by the uniform distribution of particles in the matrix as observed in their microstructure.

  8. Particle Board and Oriented Strand Board Prepared with Nanocellulose-Reinforced Adhesive

    Directory of Open Access Journals (Sweden)

    Stefan Veigel

    2012-01-01

    Full Text Available Adhesives on the basis of urea-formaldehyde (UF and melamine-urea-formaldehyde (MUF are extensively used in the production of wood-based panels. In the present study, the attempt was made to improve the mechanical board properties by reinforcing these adhesives with cellulose nanofibers (CNFs. The latter were produced from dissolving grade beech pulp by a mechanical homogenization process. Adhesive mixtures with a CNF content of 0, 1, and 3 wt% based on solid resin were prepared by mixing an aqueous CNF suspension with UF and MUF adhesives. Laboratory-scale particle boards and oriented strand boards (OSBs were produced, and the mechanical and fracture mechanical properties were investigated. Particle boards prepared with UF containing 1 wt% CNF showed a reduced thickness swelling and better internal bond and bending strength than boards produced with pure UF. The reinforcing effect of CNF was even more obvious for OSB where a significant improvement of strength properties of 16% was found. For both, particle board and OSB, mode I fracture energy and fracture toughness were the parameters with the greatest improvement indicating that the adhesive bonds were markedly toughened by the CNF addition.

  9. Particle-Based Geometric and Mechanical Modelling of Woven Technical Textiles and Reinforcements for Composites

    Science.gov (United States)

    Samadi, Reza

    affecting the textile geometry and constitutive behaviour under evolving loading; 5) validating simulation results with experimental trials; and 6) demonstrating the applicability of the simulation procedure to textile reinforcements featuring large numbers of small fibres as used in PMCs. As a starting point, the effects of reinforcement configuration on the in-plane permeability of textile reinforcements, through-thickness thermal conductivity of PMCs and in-plane stiffness of unidirectional and bidirectional PMCs were quantified systematically and correlated with specific geometric parameters. Variability was quantified for each property at a constant fibre volume fraction. It was observed that variability differed strongly between properties; as such, the simulated behaviour can be related to variability levels seen in experimental measurements. The effects of the geometry of textile reinforcements on the aforementioned processing and performance properties of the textiles and PMCs made from these textiles was demonstrated and validated, but only for simple cases as thorough and credible geometric models were not available at the onset of this work. Outcomes of this work were published in a peer-reviewed journal [101]. Through this thesis it was demonstrated that predicting changes in textile geometry prior and during loading is feasible using the proposed particle-based modelling method. The particle-based modelling method relies on discrete mechanics and offers an alternative to more traditional methods based on continuum mechanics. Specifically it alleviates issues caused by large strains and management of intricate, evolving contact present in finite element simulations. The particle-based modelling method enables credible, intricate modelling of the geometry of textiles at the mesoscopic scale as well as faithful mechanical modelling under load. Changes to textile geometry and configuration due to the normal compaction pressure, stress relaxation, in-plane shear

  10. Human fetal bone cells associated with ceramic reinforced PLA scaffolds for tissue engineering.

    Science.gov (United States)

    Montjovent, Marc-Olivier; Mark, Silke; Mathieu, Laurence; Scaletta, Corinne; Scherberich, Arnaud; Delabarde, Claire; Zambelli, Pierre-Yves; Bourban, Pierre-Etienne; Applegate, Lee Ann; Pioletti, Dominique P

    2008-03-01

    Fetal bone cells were shown to have an interesting potential for therapeutic use in bone tissue engineering due to their rapid growth rate and their ability to differentiate into mature osteoblasts in vitro. We describe hereafter their capability to promote bone repair in vivo when combined with porous scaffolds based on poly(l-lactic acid) (PLA) obtained by supercritical gas foaming and reinforced with 5 wt.% beta-tricalcium phosphate (TCP). Bone regeneration was assessed by radiography and histology after implantation of PLA/TCP scaffolds alone, seeded with primary fetal bone cells, or coated with demineralized bone matrix. Craniotomy critical size defects and drill defects in the femoral condyle in rats were employed. In the cranial defects, polymer degradation and cortical bone regeneration were studied up to 12 months postoperatively. Complete bone ingrowth was observed after implantation of PLA/TCP constructs seeded with human fetal bone cells. Further tests were conducted in the trabecular neighborhood of femoral condyles, where scaffolds seeded with fetal bone cells also promoted bone repair. We present here a promising approach for bone tissue engineering using human primary fetal bone cells in combination with porous PLA/TCP structures. Fetal bone cells could be selected regarding osteogenic and immune-related properties, along with their rapid growth, ease of cell banking and associated safety. PMID:18178142

  11. Effects of Surface Treatments on the Bond Strength Between Resin Cement and a New Zirconia-reinforced Lithium Silicate Ceramic.

    Science.gov (United States)

    Sato, T P; Anami, L C; Melo, R M; Valandro, L F; Bottino, M A

    2016-01-01

    This study evaluated the effects of surface treatments on the bond strength between the new zirconia-reinforced lithium silicate ceramic (ZLS) and resin cement. VITA Suprinity blocks were crystallized according to the manufacturer's instructions and randomly assigned to six groups (N=36; n=6), according to the surface treatment to be performed and aging conditions: HF20, 10% hydrofluoric acid for 20 seconds, baseline (control); HF20tc, 10% hydrofluoric acid for 20 seconds, aging; HF40, 10% hydrofluoric acid for 40 seconds, baseline; HF40tc, 10% hydrofluoric acid for 40 seconds, aging; CJ, CoJet sandblasting (25 seconds, 2.5 bar, 15-mm distance), baseline; and CJtc, CoJet sandblasting (25 seconds, 2.5 bar, 15-mm distance), aging. All specimens were silanized (Monobond S) and cemented with Panavia F to newly polymerized Z250 resin blocks. After specimens were immersed for 24 hours in distilled water at 37° C, 1-mm(2) cross-section microbars were obtained by means of a cutting machine under constant cooling. Baseline groups were immediately tested, whereas "tc" groups were used to analyze the effect of aging on bond strength (10,000 thermal cycles, 5/55°C, 30-second bath). The microtensile bond strength test was performed with a universal testing machine (0.5 mm/min), and bond strength (MPa) was calculated when the load-to-failure (N) was divided by the adhesive area (mm(2)). We also evaluated the surface roughness (Sa, average roughness; Str, texture aspect ratio; Sdr, developed interfacial area ratio) and the contact angle resulting from the treatments. Data were statistically analyzed by one- or two-way analysis of variance and Tukey's test (all α=5%). The failure mode of each specimen was evaluated by stereomicroscopy, and representative specimens were analyzed by scanning electron microscopy. The microtensile bond strength was affected by the surface conditioning (p<0.0001), storage condition (p<0.0001), and the interaction between them (p=0.0012). The

  12. Microstructure and wear properties of the electroslag remelting layer reinforced by TiC particles

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The electroslag remelting (ESR) layer reinforced by TiC particles was obtained by electroslag remelting.The microstructure and wear properties of the ESR layer were studied by means of scanning electron microscopy (SEM),X-ray diffraction (XRD),and wear test.The results indicate that TiC particles are synthesized by self-propagating high-temperature synthesis (SHS) reaction during the electroslag remelting process.The size of TiC particles is in the range of 1-10 μm,and the distribution of TiC particles is uniform,from outside to inside of the ESR layer,and the volume fraction and the size of TiC particles decrease gradually.Molten iron and slag flow into porosity due to the SHS process leading to rapid densification and the elimination of porosity in the ESR layer during the ESR process.TiC particles enhance the wear resistance of the ESR layer,whereas CaF2 can improve the high temperature lubricating property of the ESR layer.

  13. An Investigation of Laser Assisted Machining of Al_2O_3 Particle Reinforced Aluminum Matrix Composite

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The Al 2O 3 particles reinforced aluminum matrix composite (Al 2O 3p/Al) are more and more widely used for their excellent physical and chemical properties. However, their poor machinability leads to severe tool wear and bad machined surface. In this paper laser assisted machining is adopted in machining Al 2O 3p/Al composite and good result was obtained. The result of experiment shows in machining Al 2O 3p/Al composites the cutting force is reduced in 30%~50%, the tool wear is reduced in 20%~30% an...

  14. Abrasive wear response of aluminium alloy-sillimanite particle reinforced composite under low stress condition

    Energy Technology Data Exchange (ETDEWEB)

    Singh, M. [Regional Research Laboratory (CSIR), Hoshangabad Road, Near Habibganj Naka, Bhopal 462 026 (India)]. E-mail: mulayam_singh@hotmail.com; Mondal, D.P. [Regional Research Laboratory (CSIR), Hoshangabad Road, Near Habibganj Naka, Bhopal 462 026 (India); Das, S. [Regional Research Laboratory (CSIR), Hoshangabad Road, Near Habibganj Naka, Bhopal 462 026 (India)

    2006-03-15

    The abrasive wear behaviour of aluminium alloy-sillimanite particle reinforced composite under low stress condition has been reported and the results have been compared with the corresponding matrix alloy which was produced and cast under similar conditions. The study showed that wear resistance (inverse of wear rate) of the composite was higher than the matrix alloy. The wear rate decreased with sliding distance and increased with applied load irrespective of materials. The worn surfaces and subsurfaces of the tested samples were examined in the scanning electron microscope in order to understand the material removal mechanism during low stress abrasive wear process.

  15. Characteristics and fabrication of cermet spent nuclear fuel casks: ceramic particles embedded in steel

    Energy Technology Data Exchange (ETDEWEB)

    Forsberg, C.W.; Swaney, P.M.; Tiegs, T.N. [Oak Ridge National Lab., Oak Ridge, TN (United States)

    2004-07-01

    Cermets are being investigated as an advanced material of construction for casks that can be used for storage, transport, or disposal of spent nuclear fuel (SNF). Cermets, which consist of ceramic particles embedded in steel, are a method to incorporate brittle ceramics with highly desirable properties into a strong ductile metal matrix with a high thermal conductivity, thus combining the best properties of both materials. Traditional applications of cermets include tank armor, vault armor, drill bits, and nuclear test-reactor fuel. Cermets with different ceramics (DUO{sub 2}, Al{sub 2}O{sub 3}, Gd{sub 2}O{sub 3}, etc.) are being investigated for the manufacture of SNF casks. Cermet casks offer four potential benefits: greater capacity (more SNF assemblies) for the same gross weight cask, greater capacity (more SNF assemblies) for the same external dimensions, improved resistance to assault, and superior repository performance. These benefits are achieved by varying the composition, volume fraction, and particulate size of the ceramic particles in the cermet with position in the cask body. Addition of depleted uranium dioxide (DUO{sub 2}) to the cermet increases shielding density, improves shielding effectiveness, and increases cask capacity for a given cask weight or size. Addition of low-density aluminium oxide (Al{sub 2}O{sub 3}) to the outer top and bottom sections of the cermet cask, where the radiation levels are lower, can lower cask weight without compromising shielding. The use of Al2O3 and other oxides, in appropriate locations, can increase resistance to assault. Repository performance may be improved by compositional control of the cask body to (1) create a local geochemical environment that slows the long-term degradation of the SNF and (2) enables the use of DUO{sub 2} for longterm criticality control. While the benefits of using cermets follow directly from their known properties, the primary challenge is to develop low-cost methods to fabricate

  16. In situ fabrication and microstructure of Al2O3 particles reinforced aluminum matrix composites

    International Nuclear Information System (INIS)

    Al2O3p/Al composites were prepared by direct melt reaction process. The thermodynamics of in situ chemical reactions between molten aluminum and CeO2 powder was studied. The XRD results show that the components of the as-prepared composites consist of Al2O3 and Al phases. For the as-cast composite specimens, SEM, EDX, TEM and SAD were used to analyze the reinforcement phases and interface characters of composites. The results show that the in situ generated Al2O3 particles, whose sizes are 100-200 nm, have various irregular shapes and disperse uniformly in matrix. TEM observation shows that the interface between particle and matrix is clean. Furthermore, there is no fixed orientation relationship between Al2O3 particles and aluminum matrix. Only [12-bar 10]//[111] orientation parallel relationship with low exponent is found. Therefore, the composites have isotropic properties. Besides characters mentioned above, there are large amount of high density dislocations and the generated extensive fine subgrains around Al2O3 particles. These features are favorable for improving composite performances. As a result, the composites are comprehensively strengthened not only by Al2O3 particles, but also by the high density dislocations and fine subgrains.

  17. Solid Particle Erosion of Date Palm Leaf Fiber Reinforced Polyvinyl Alcohol Composites

    Directory of Open Access Journals (Sweden)

    Jyoti R. Mohanty

    2014-01-01

    Full Text Available Solid particle erosion behavior of short date palm leaf (DPL fiber reinforced polyvinyl alcohol (PVA composite has been studied using silica sand particles (200 ± 50 μm as an erodent at different impingement angles (15–90° and impact velocities (48–109 m/s. The influence of fiber content (wt% of DPL fiber on erosion rate of PVA/DPL composite has also been investigated. The neat PVA shows maximum erosion rate at 30° impingement angle whereas PVA/DPL composites exhibit maximum erosion rate at 45° impingement angle irrespective of fiber loading showing semiductile behavior. The erosion efficiency of PVA and its composites varies from 0.735 to 16.289% for different impact velocities studied. The eroded surfaces were observed under scanning electron microscope (SEM to understand the erosion mechanism.

  18. Microstructure of Fe-Based Alloy Hardfacing Coating Reinforced by TiC-VC Particles

    Institute of Scientific and Technical Information of China (English)

    WANG Xin-hong; ZOU Zeng-da; QU Shi-yao

    2006-01-01

    Microstructure of the Fe-based alloy hardfacing coating reinforced by TiC-VC particles was investigated by means of SEM, TEM, XRD and EPMA. The thermodynamics and effect of elements on the carbides were discussed. The result shows that TiC-VC carbides can be formed during arc welding. Carbides with particle size of 2-4 μm are uniformly dispersed in the matrix. Evidently the covering components and their amount affect the microstructure and hardness of the coatings. An excellent microstructure and hardness of hardfacing coating were obtained, while the amount of graphite, FeTi and FeV was controlled within the range of 8%-10%, 15%-18% and 8%-12%, respectively.

  19. Low-level measurement of alpha-particle emitting nuclei in ceramics and lead

    International Nuclear Information System (INIS)

    Nearly all natural materials contain trace quantities of uranium (U) and thorium (Th) and their daughter nuclides, many of which emit α-particles in their decay. Lead, at the end of the U-decay chain, typically contains some radioactive 210Pb which is chemically inseparable from the other Pb isotopes. α-particle emission from these decays can affect sensitive electronic components, such as memory chips or processors. Measurement of α-particle emitters can be accomplished by direct detection of the α-particles (which typically provides no positive identification of the emitting isotope because of energy loss in the sample) or by low-background γ-ray spectroscopy (which does provide positive identification via characteristic γ-rays). The latter is by far the best method for screening kg-sized samples of materials like ceramics, aluminum, iron, or copper. The difference between α counting and γ-ray spectroscopy is less for measuring 210Pb in Pb since the 46.5 keV characteristic γ-rays directly following the 210Pb decay are strongly absorbed and both methods are limited to thin layers. This paper discusses these two cases and concludes that a large n-type germanium γ-ray spectrometer is probably the best overall system for both measurements. (author)

  20. Influences of interphase on dynamic effective properties of composites reinforced by dispersed spherical particles

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The influences of interphase on dynamic effective properties of composites reinforced by randomly dispersed spherical particles were studied. A thin homogeneous elastic interphase with different shear and bulk moduli, located between the reinforced particle and the host matrix, was introduced to model the interfacial bonding state. The effects of such an interphase on the coherent plane waves were studied numerically. Numerical simulations were carried out for SiC-Al composites with four typical cases of interphase. It was found that the property of interphase has significant influences on the effective propagation constants of coherent waves and the dynamic effective elastic moduli of the composites. The influences on the coherent longitudinal wave and the coherent shear waves were different and dependent upon the frequency range. Moreover, several imperfect interface models, i.e., the spring model, mass model, and spring-mass model, were studied numerically and compared with the interphase model. It was found that the spring model is a more suitable model than the mass model for the light and weak interphase whereas the mass model is a more suitable model than the spring model for the heavy and strong interphase.

  1. Morphology and Shear Strength of Lead-Free Solder Joints with Sn3.0Ag0.5Cu Solder Paste Reinforced with Ceramic Nanoparticles

    Science.gov (United States)

    Yakymovych, A.; Plevachuk, Yu.; Švec, P.; Švec, P.; Janičkovič, D.; Šebo, P.; Beronská, N.; Roshanghias, A.; Ipser, H.

    2016-08-01

    To date, additions of different oxide nanoparticles is one of the most widespread procedures to improve the mechanical properties of metals and metal alloys. This research deals with the effect of minor ceramic nanoparticle additions (SiO2, TiO2 and ZrO2) on the microstructure and mechanical properties of Cu/solder/Cu joints. The reinforced Sn3.0Ag0.5Cu (SAC305) solder alloy with 0.5 wt.% and 1.0 wt.% of ceramic nanoparticles was prepared through mechanically stirring. The microstructure of as-solidified Cu/solder/Cu joints was studied using scanning electron microscopy. The additions of ceramic nanoparticles suppressed the growth of the intermetallic compound layer Cu6Sn5 at the interface solder/Cu and improved the microstructure of the joints. Furthermore, measurements of mechanical properties showed improved shear strength of Cu/composite solder/Cu joints compared to joints with unreinforced solder. This fact related to all investigated ceramic nanoinclusions and should be attributed to the adsorption of nanoparticles on the grain surface during solidification. However, this effect is less pronounced on increasing the nanoinclusion content from 0.5 wt.% to 1.0 wt.% due to agglomeration of nanoparticles. Moreover, a comparison analysis showed that the most beneficial influence was obtained by minor additions of SiO2 nanoparticles into the SAC305 solder alloy.

  2. Aluminium EN AW-2124 alloy matrix composites reinforced with Ti(C,N), BN and Al2O3 particles

    International Nuclear Information System (INIS)

    Investigation results of the aluminium alloy EN AW-2124 matrix composite materials with particles of the powders Ti(C,N), BN and Al2O3 (15 wt.%) are presented in the paper. In order to obtain uniform distribution of reinforcement particles in aluminium alloy matrix powders of composite components have been milled in the rotary ball-bearing pulverizer. The composites have been pressed in laboratory vertical press at room temperature under the pressure of 500 kN. Obtained die samplings have been heated to the temperature 520-550 oC and extruded. Bars of diameter 8 mm have been received as a final product. Metallographic examination of the composites materials' structure shows non-uniform distribution of reinforced powders in the aluminium alloy matrix banding of reinforcements particles corresponds to the extrusion direction. Particles of reinforcement distribution in aluminium alloy matrix is irregular, some agglomerations of powder of aluminium oxide and porosity of different size have been noticed. Investigations of hardness and ultimate compressive strength show that the particles of reinforcement improve mechanical properties of composite materials. Investigations of compressive strength, carried out at room temperature, enable to compare mechanical properties of matrix and composite. (author)

  3. Computer Simulation of the Indentation Creep Tests on Particle-Reinforced Composites

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    A systematical simulation has been carried out on the indentation creep test on particle-reinforced composites. The deformation, failure mechanisms and life are analyzed by three reasonable models. The following five factors have been considered simultaneously: creep property of the particle, creep property of the matrix, the shape of the particle,the volume fraction of the particle and the size (relative size to the particle) of the indentation indenter. For all the cases, the power law respecting to the applied stress can be used to model the steady indentation creep depth rate of the indenter, and the detail expressions have been presented. The computer simulation precision is analyzed by the two-phase model and the three-phase model. Two places of the stress concentration are found in the composites.One is ahead of the indentation indenter, where the high stress state is deduced by the edge of the indenter and will decrease rapidly near to a steady value with the creep time. The other one is at the interface, where the high stress state is deduced by the misfit of material properties between the particles and matrix. It has been found that the creep dissipation energy density other than a stress parameter can be used to be the criterion to model the debonding of the interfaces. With the criterion of the critical creep dissipation energy density, a power law to the applied stress with negative exponent can be used to model the failure life deduced by the debonding of interfaces. The influences of the shape of the particles and the matching of creep properties of particle and matrix can be discussed for the failure. With a crack model, the further growth of interface crack is analyzed, and some important experimental phenomena can be predicted. The failure mechanism which the particle will be punched into matrix has been also discussed. The critical diflerences between the creep properties of the particles and matrix have been calculated,after a parameter has

  4. Effects of silica and calcium levels in nanobioglass ceramic particles on osteoblast proliferation

    International Nuclear Information System (INIS)

    At nanoscale, bioglass ceramic (nBGC) particles containing calcium oxide (lime), silica and phosphorus pentoxide promote osteoblast proliferation. However, the role of varied amounts of calcium and silica present in nBGC particles on osteoblast proliferation is not yet completely known. Hence, the current work was aimed at synthesizing two different nBGC particles with varied amounts of calcium oxide and silica, nBGC-1: SiO2:CaO:P2O5; mol% ∼ 70:25:5 and nBGC-2: SiO2:CaO:P2O5; mol% ∼ 64:31:5, and investigating their role on osteoblast proliferation. The synthesized nBGC particles were characterized by transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS), Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD) studies. They exhibited their size at nanoscale and were non-toxic to human osteoblastic cells (MG-63). The nBGC-2 particles were found to have more effect on stimulation of osteoblast proliferation and promoted entering of more cells into G2/M cell cycle phase compared to nBGC-1 particles. There was a differential expression of cyclin proteins in MG-63 cells by nBGC-1 and nBGC-2 treatments, and the expression of cyclin B1 and E proteins was found to be more by nBGC-2 treatment. Thus, these results provide us a new insight in understanding the design of various nBGC particles by altering their ionic constituents with desirable biological properties thereby supporting bone augmentation. - Highlights: • nBGC particles with varied amounts of calcium and silica were synthesized. • They were non-toxic to human osteoblastic cells. • nBGC-2 particles had more effect on stimulation of osteoblast proliferation. • nBGC-2 particles promoted entering of osteoblasts into G2/M cell cycle phase. • Expression of cyclin B1 and E proteins was found to be more by nBGC-2 treatment

  5. Effect of particle size on microstructure and strength of porous spinel ceramics prepared by pore-forming in situ technique

    Indian Academy of Sciences (India)

    Wen Yan; Nan Li; Yuanyuan Li; Guangping Liu; Bingqiang Han; Juliang Xu

    2011-08-01

    The porous spinel ceramics were prepared from magnesite and bauxite by the pore-forming in situ technique. The characterization of porous spinel ceramics was determined by X-ray diffractometer (XRD), scanning electron microscopy(SEM), mercury porosimetry measurement etc and the effects of particle size on microstructure and strength were investigated. It was found that particle size affects strongly on the microstructure and strength. With decreasing particle size, the pore size distribution occurs from multi-peak mode to bi-peak mode, and lastly to mono-peak mode; the porosity decreases but strength increases. The most apposite mode is the specimens from the grinded powder with a particle size of 6.53 m, which has a high apparent porosity (40%), a high compressive strength (75.6MPa), a small average pore size (2.53 m) and a homogeneous pore size distribution.

  6. Recovery and Modification of Waste Tire Particles and Their Use as Reinforcements of Concrete

    Directory of Open Access Journals (Sweden)

    Eduardo Sadot Herrera-Sosa

    2015-01-01

    Full Text Available Environmental pollution caused by solid wastes is increasing in the last decades; one of these is referred to automotive tires, which are recycled by different methods, including mechanical grinding. One of the most recurrent applications is to use recycled particles as fillers in building materials, as hydraulic concrete. Nevertheless, detrimental values on the mechanical properties are obtained when they are added. For solving these problems, in this work, a novel proposal is to modify the physicochemical properties of the waste automotive tire particles, previously obtained by grinding process, by using gamma irradiation in order to use them as reinforcements of hydraulic concrete. The results show that improvements on the mechanical properties depend of gamma irradiation as well as concentration and size of waste tire particles. Moreover, SEM images are related to mechanical properties; for instance, rough surface of the tire particles changes when applying irradiation; more smooth surfaces are created, due to the cross-linking of polymer chains. Nevertheless, for higher doses, cracks are observed which are produced by scission of the polymer chains.

  7. Compression Creep Behavior of High Volume Fraction of SiC Particles Reinforced Al Composite Fabricated by Pressureless Infiltration

    Institute of Scientific and Technical Information of China (English)

    XU Fu-min; WU Lawrence Chi-man; HAN Guang-wei; TAN Yi

    2007-01-01

    The compression creep deformation of the high volume fraction of SiC particles reinforced Al-Mg-Si composite fabricated by pressure-less infiltration was investigated. The experimental results show that the creep stress exponents are very high at temperatures of 673 K, 723 K and 773 K, and if taking the threshold stress into account, the true stress exponent of minimum creep strain rate is still approximately 5, although the volume fraction of reinforcements is very high. The creep strain rate in the high volume fraction reinforced aluminum alloy matrix composites is controlled by matrix lattice diffusion. It is found that the creep-strengthening effect of high volume fraction of silicon carbide particles is significant, although the particles do not form effective obstacles to dislocation motion.

  8. Impact of Particle Size of Ceramic Granule Blends on Mechanical Strength and Porosity of 3D Printed Scaffolds

    OpenAIRE

    Sebastian Spath; Philipp Drescher; Hermann Seitz

    2015-01-01

    3D printing is a promising method for the fabrication of scaffolds in the field of bone tissue engineering. To date, the mechanical strength of 3D printed ceramic scaffolds is not sufficient for a variety of applications in the reconstructive surgery. Mechanical strength is directly in relation with the porosity of the 3D printed scaffolds. The porosity is directly influenced by particle size and particle-size distribution of the raw material. To investigate this impact, a hydroxyapatite gran...

  9. Effects of different lasers and particle abrasion on surface characteristics of zirconia ceramics.

    Directory of Open Access Journals (Sweden)

    Sakineh Arami

    2014-04-01

    Full Text Available The aim of this study was to assess the surface of yttrium-stabilized tetragonal zirconia (Y-TZP after surface treatment with lasers and airborne-particle abrasion.First, 77 samples of presintered zirconia blocks measuring 10 × 10 × 2 mm were made, sintered and polished. Then, they were randomly divided into 11 groups (n=7 and received surface treatments namely, Er:YAG laser irradiation with output power of 1.5, 2 and 2.5 W, Nd:YAG laser with output power of 1.5, 2 and 2.5 W, CO2 laser with output power of 3, 4 and 5 W, AL2O3 airborne-particle abrasion (50μ and no treatment (controls. Following treatment, the parameters of surface roughness such as Ra, Rku and Rsk were evaluated using a digital profilometer and surface examination was done by SEM.According to ANOVA and Tukey's test, the mean surface roughness (Ra after Nd:YAG laser irradiation at 2 and 2.5 W was significantly higher than other groups. Roughness increased with increasing output power of Nd:YAG and CO2 lasers. Treated surfaces by Er:YAG laser and air abrasion showed similar surface roughness. SEM micrographs showed small microcracks in specimens irradiated with Nd:YAG and CO2 lasers.Nd:YAG laser created a rough surface on the zirconia ceramic with many microcracks; therefore, its use is not recommended. Air abrasion method can be used with Er:YAG laser irradiation for the treatment of zirconia ceramic.

  10. Development of Thermal Spraying and Coating Techniques by Using Thixotropic Slurries Including Metals and Ceramics Particles

    International Nuclear Information System (INIS)

    Thermal nanoparticles coating and microlines patterning were newly developed as novel technologies to fabricate fine ceramics layers and geometrical intermetallics patterns for mechanical properties modulations of practical alloys substrates. Nanometer sized alumina particles were dispersed into acrylic liquid resins, and the obtained slurries were sputtered by using compressed air jet. The slurry mists could blow into the arc plasma with argon gas spraying. On stainless steels substrates, the fine surface layers with high wear resistance were formed. In cross sectional microstructures of the coated layers, micromater sized cracks or pores were not observed. Subsequently, pure aluminum particles were dispersed into photo solidified acrylic resins, and the slurry was spread on the stainless steel substrates by using a mechanical knife blade. On the substrates, microline patterns with self similar fractal structures were drawn and fixed by using scanning of an ultra violet laser beam. The patterned pure metal particles were heated by the argon arc plasma spray assisting, and the intermetallics or alloys phases with high hardness were created through reaction diffusions. Microstructures in the coated layers and the patterned lines were observed by using a scanning electron microscopy.

  11. Metallic nano-particles in lustre glazed ceramics from the 15th century in Seville studied by PIXE and RBS

    Science.gov (United States)

    del Rio, A. Polvorinos; Castaing, J.; Aucouturier, M.

    2006-08-01

    Lustre ceramics, found in a workshop located in Triana (Sevilla), have been analysed to determine the composition of glazes including the metallic particle layers giving rise to the lustre effect. PIXE and RBS were used for the elemental composition and the sub-surface concentration profiles, respectively. Copper and silver at the origin of the lustre are detected by PIXE. RBS gives access to the detailed distribution of the elements in the surface layers. The simulation of RBS spectra confirms the occurrence of thin layers (less than 300 nm) containing metallic silver and/or copper. The results are compared with those obtained on other types of lustre ceramics.

  12. Metallic nano-particles in lustre glazed ceramics from the 15th century in Seville studied by PIXE and RBS

    Energy Technology Data Exchange (ETDEWEB)

    Polvorinos del Rio, A. [Departamento de Cristallografia, Mineralogia y Quimica Agricola, Universidad de Sevilla, avenida Reina Mercedes s/n (Spain); Castaing, J. [Laboratoire du centre de recherche et de restauration des musees de France C2RMF CNRS UMR 171, Plais du Louvre, 14 quai Francois Mitterrand, 75001 Paris (France)]. E-mail: jacques.castaing@culture.fr; Aucouturier, M. [Laboratoire du centre de recherche et de restauration des musees de France C2RMF CNRS UMR 171, Plais du Louvre, 14 quai Francois Mitterrand, 75001 Paris (France)

    2006-08-15

    Lustre ceramics, found in a workshop located in Triana (Sevilla), have been analysed to determine the composition of glazes including the metallic particle layers giving rise to the lustre effect. PIXE and RBS were used for the elemental composition and the sub-surface concentration profiles, respectively. Copper and silver at the origin of the lustre are detected by PIXE. RBS gives access to the detailed distribution of the elements in the surface layers. The simulation of RBS spectra confirms the occurrence of thin layers (less than 300 nm) containing metallic silver and/or copper. The results are compared with those obtained on other types of lustre ceramics.

  13. Metallic nano-particles in lustre glazed ceramics from the 15th century in Seville studied by PIXE and RBS

    International Nuclear Information System (INIS)

    Lustre ceramics, found in a workshop located in Triana (Sevilla), have been analysed to determine the composition of glazes including the metallic particle layers giving rise to the lustre effect. PIXE and RBS were used for the elemental composition and the sub-surface concentration profiles, respectively. Copper and silver at the origin of the lustre are detected by PIXE. RBS gives access to the detailed distribution of the elements in the surface layers. The simulation of RBS spectra confirms the occurrence of thin layers (less than 300 nm) containing metallic silver and/or copper. The results are compared with those obtained on other types of lustre ceramics

  14. Strength properties and fracture behavior of ZrC particle-reinforced tungsten composite

    Institute of Scientific and Technical Information of China (English)

    王玉金; 宋桂明; 孟庆昌; 周玉

    2001-01-01

    The flexural strength of 30 % (volume fraction) ZrC particle-reinforced tungsten composite (ZrCp/W) at 20~1 200℃ were measured using three-point bending, and the fracture behaviors of the samples at 20 ℃ and 1000 ℃ were studied with a scanning electron microscope. As temperature increases, the strength of the composite increases firstly and the highest strength value, 829 MPa, is measured at 1 000 ℃, and then the strength decreases when temperature is over 1000 ℃. The fracture of the composite at 20 ℃, which is controlled by the crack initiating process, is brittle, and the corresponding stress-deflection curve is linear. There is a metastable growth and coalescence of the initial cracks during the fracture process of the samples at 1 000 ℃, and the stress-deflection curve displays a nonlinear characteristic. The good elevated strength of the composite is partly attributed to the W grain interior strength and ZrCp/W interface strength. The reinforcement at high temperature is mainly attributed to the load transfer of ZrCp/W interface and dislocation strengthening.

  15. Micromechanical and macroscopic models of ductile fracture in particle reinforced metallic materials

    Science.gov (United States)

    Hu, Chao; Bai, Jie; Ghosh, Somnath

    2007-06-01

    This paper is aimed at developing two modules contributing to the overall framework of multi-scale modelling of ductile fracture of particle reinforced metallic materials. The first module is for detailed micromechanical analysis of particle fragmentation and matrix cracking of heterogeneous microstructures. The Voronoi cell FEM for particle fragmentation is extended in this paper to incorporate ductile failure through matrix cracking in the form of void growth and coalescence using a non-local Gurson-Tvergaard-Needleman (GTN) model. In the resulting enriched Voronoi cell finite element model (VCFEM) or E-VCFEM, the assumed stress-based hybrid VCFEM formulation is overlaid with narrow bands of displacement based elements to accommodate strain softening in the constitutive behaviour. The second module develops an anisotropic plasticity-damage model in the form of the GTN model for macroscopic analysis in the multi-scale material model. Parameters in this model are calibrated from results of homogenization of microstructural variables obtained by E-VCFEM analysis of microstructural representative volume element. Numerical examples conducted yield satisfactory results.

  16. Damping Mechanism of SiC Particle Reinforced Al Matrix Composites

    Directory of Open Access Journals (Sweden)

    Li Xiao

    2016-01-01

    Full Text Available The low-frequency internal friction behavior of SiC particle reinforced Al matrix composites was studied over a temperature range from 23°C to 550°C at frequencies of 0.1, 1 and 5 Hz. The experimental data were analyzed in terms of the K-G-L dislocation theory and the anelastic relaxation of grain boundary sliding. Two internal friction peaks of the composites were respectively observed over the temperature ranges of 100~250°C and 200~500°C. The dislocation motion is the important damping mechanism of the composites at low temperatures, while the grain boundary relaxation plays a dominant role at high temperatures. The activation energies for dislocation relaxation and grain boundary sliding are 1.2 eV and 1.57 eV, respectively.

  17. Wear Resistance of Aluminum Matrix Composites Reinforced with Al2O3 Particles After Multiple Remelting

    Science.gov (United States)

    Klasik, Adam; Pietrzak, Krystyna; Makowska, Katarzyna; Sobczak, Jerzy; Rudnik, Dariusz; Wojciechowski, Andrzej

    2016-01-01

    Based on previous results, the commercial composites of A359 (AlSi9Mg) alloy reinforced with 22 vol.% Al2O3 particles were submitted to multiple remelting by means of gravity casting and squeeze-casting procedures. The studies were focused on tribological tests, x-ray phase analyses, and microstructural examinations. More promising results were obtained for squeeze-casting method mainly because of the reduction of the negative microstructural effects such as shrinkage porosity or other microstructural defects and discontinuities. The results showed that direct remelting may be treated as economically well-founded and alternative way compared to other recycling processes. It was underlined that the multiple remelting method must be analyzed for any material separately.

  18. Weibull Probability Model for Fracture Strength of Aluminium (1101)-Alumina Particle Reinforced Metal Matrix Composite

    Institute of Scientific and Technical Information of China (English)

    A.Suresh Babu; V.Jayabalan

    2009-01-01

    In recent times, conventional materials are replaced by metal matrix composites (MMCs) due to their high specific strength and modulus.Strength reliability, one of the key factors restricting wider use of composite materials in various applications, is commonly characterized by Weibull strength distribution function.In the present work, statistical analysis of the strength data of 15% volume alumina particle (mean size 15 μm)reinforced in aluminum alloy (1101 grade alloy) fabricated by stir casting method was carried out using Weibull probability model.Twelve tension tests were performed according to ASTM B577 standards and the test data, the corresponding Weibull distribution was obtained.Finally the reliability of the composite behavior in terms of its fracture strength was presented to ensure the reliability of composites for suitable applications.An important implication of the present study is that the Weibull distribution describes the experimentally measured strength data more appropriately.

  19. Wear Resistance of Aluminum Matrix Composites Reinforced with Al2O3 Particles After Multiple Remelting

    Science.gov (United States)

    Klasik, Adam; Pietrzak, Krystyna; Makowska, Katarzyna; Sobczak, Jerzy; Rudnik, Dariusz; Wojciechowski, Andrzej

    2016-08-01

    Based on previous results, the commercial composites of A359 (AlSi9Mg) alloy reinforced with 22 vol.% Al2O3 particles were submitted to multiple remelting by means of gravity casting and squeeze-casting procedures. The studies were focused on tribological tests, x-ray phase analyses, and microstructural examinations. More promising results were obtained for squeeze-casting method mainly because of the reduction of the negative microstructural effects such as shrinkage porosity or other microstructural defects and discontinuities. The results showed that direct remelting may be treated as economically well-founded and alternative way compared to other recycling processes. It was underlined that the multiple remelting method must be analyzed for any material separately.

  20. Assessment of microcapsule—catalyst particles healing system in high performance fibre reinforced polymer composite

    Science.gov (United States)

    Bolimowski, P. A.; Wass, D. F.; Bond, I. P.

    2016-08-01

    Autonomous self-healing in carbon fibre reinforced polymer (CFRP) is demonstrated using epoxy resin filled microcapsules and a solid-state catalyst. Microcapsules filled with oligomeric epoxy resin (20-450 μm) and particles of Sc(OTf)3 are embedded in an interleave region of a unidirectional CFRP laminate and tested under mode I loading. Double cantilever beam (DCB) test specimens containing variable concentrations of microcapsules and catalyst were prepared, tested and compared to those healed by manual injection with corresponding healing resin formulation. The healing efficiency was evaluated by comparing the maximum peak load recorded on load-displacement curves for pristine and healed specimens. A 44% maximum recovery was observed for specimens containing 10 wt% of solid phase catalyst and 11 wt% of epoxy microcapsules. However, a significant (80%) decrease in initial strain energy release rate (G IC) was observed for specimens with the embedded healing chemistries.

  1. Assessment of microcapsule—catalyst particles healing system in high performance fibre reinforced polymer composite

    Science.gov (United States)

    Bolimowski, P. A.; Wass, D. F.; Bond, I. P.

    2016-08-01

    Autonomous self-healing in carbon fibre reinforced polymer (CFRP) is demonstrated using epoxy resin filled microcapsules and a solid-state catalyst. Microcapsules filled with oligomeric epoxy resin (20–450 μm) and particles of Sc(OTf)3 are embedded in an interleave region of a unidirectional CFRP laminate and tested under mode I loading. Double cantilever beam (DCB) test specimens containing variable concentrations of microcapsules and catalyst were prepared, tested and compared to those healed by manual injection with corresponding healing resin formulation. The healing efficiency was evaluated by comparing the maximum peak load recorded on load–displacement curves for pristine and healed specimens. A 44% maximum recovery was observed for specimens containing 10 wt% of solid phase catalyst and 11 wt% of epoxy microcapsules. However, a significant (80%) decrease in initial strain energy release rate (G IC) was observed for specimens with the embedded healing chemistries.

  2. Damage analysis for particle reinforced metal matrix composite by ultrasonic method

    Institute of Scientific and Technical Information of China (English)

    YANG Zhi-guo; LONG Shi-guo

    2006-01-01

    The damage characteristic of particle reinforced metal matrix composite (PMMC) was studied by ultrasonic non-destructive evaluation method. After the sample was damaged induced by tensile load,the ultrasonic wave that propagated in the sample were collected. The damage parameter was defined by ultrasonic parameter and the wave signals were analyzed by correlation method. The results show that with the increase of tensile load,the damage parameter increases and the correlation coefficient decreases. The fracture section morphologies of PMMC under tensile load were observed by SEM. It is found that there are many concaves in the metal matrix. Therefore the damage evolution can be concluded. The initial damage is induced by void nucleation,growth and subsequent coalescence in the matrix or interface separation.

  3. Microstructure and mechanical properties of aluminum alloy matrix composite reinforced with nano-particle MgO

    Energy Technology Data Exchange (ETDEWEB)

    Yar, A. Ansary, E-mail: arash_ansaryyar@yahoo.co [Department of Materials, Islamic Azad University, South Tehran Branch, P.O. Box 11365-4435, Tehran (Iran, Islamic Republic of); Montazerian, M.; Abdizadeh, H. [School of Metallurgy and Materials Engineering, University of Tehran, P.O. Box 11365-4563, Tehran (Iran, Islamic Republic of); Baharvandi, H.R. [Malek Ashtar University of Technology, P.O. Box 16765-3454, Tehran (Iran, Islamic Republic of)

    2009-09-18

    In this research, aluminum alloy (A356.1) matrix composites reinforced with 1.5, 2.5 and 5 vol% nano-particle MgO were fabricated via stir casting method. Fabrication was performed at various casting temperatures, viz. 800, 850 and 950 deg. C. Optimum amount of reinforcement and casting temperature were determined by evaluating the density, microstructure and mechanical properties of composites. The composites were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). Hardness and compression tests were carried out in order to identify mechanical properties. The results reveal that the composites containing 1.5 vol% reinforcement particle fabricated at 850 deg. C have homogenous microstructure as well as improved mechanical properties.

  4. Continuous Fiber Ceramic Composites

    Energy Technology Data Exchange (ETDEWEB)

    None

    2002-09-01

    Fiber-reinforced ceramic composites demonstrate the high-temperature stability of ceramics--with an increased fracture toughness resulting from the fiber reinforcement of the composite. The material optimization performed under the continuous fiber ceramic composites (CFCC) included a series of systematic optimizations. The overall goals were to define the processing window, to increase the robustinous of the process, to increase process yield while reducing costs, and to define the complexity of parts that could be fabricated.

  5. Development of Al2O3/TiN Ceramic Cutting Tool Materials by Artificial Neural Networks

    Institute of Scientific and Technical Information of China (English)

    Ning FAN; Xiangbo ZE; Zihui GAO

    2004-01-01

    The artificial neural networks (ANN) which have broad application were proposed to develop multiphase ceramic cutting tool materials. Based on the back propagation algorithm of the forward multilayer perceptron, the models to predict volume content of composition in particle reinforced ceramics are established. The Al2O3/TiNl ceramic cutting tool material was developed by ANN, whose mechanical properties fully satisfy the cutting requirements.

  6. Sliding Wear Properties of Hybrid Aluminium Composite Reinforced by Particles of Palm Shell Activated Carbon and Slag

    Directory of Open Access Journals (Sweden)

    Zamri Yusoff

    2011-09-01

    Full Text Available In present work, dry sliding wear tests were conducted on hybrid composite reinforced with natural carbon based particles such as palm shell activated carbon (PSAC and slag. Hybrid composites containing 5 -20 wt.% of both reinforcements with average particles sizes about 125μm were prepared by conventional powder metallurgy technique, which involves the steps of mixing, compacting and sintering. Dry sliding experiments were conducted in air at room temperature using a pin-on-disc self-built attach to polisher machine. The disc which acted as the mating surface material was made of mild steel (120 HV cut from commercial mild steel sheet (2 mm thickness into 100mm diameter. The influence of the applied load was investigated under a constant sliding velocity of 0.1m/s with the applied loads at 3N, 11N and 51N. The contribution of the reinforcement content and the applied load as well as the sliding distance on the wear process and the wear rate have been investigated. The contribution of synergic factors such as applied load, sliding distance and reinforcement content (wt.% have been studied using analysis of variance (ANOVA. All synergic factors contribute to the wear process of all tested composites. Among synergic factors, the applied load is the highest contribution to wear process on both composites (Al/PSAC and Al/Slag and hybrid composite. The degree of improvement of wear resistance of hybrid composite is strongly dependent on the reinforcement content.

  7. Characterization of High-Velocity Single Particle Impacts on Plasma-Sprayed Ceramic Coatings

    Science.gov (United States)

    Kiilakoski, Jarkko; Lindroos, Matti; Apostol, Marian; Koivuluoto, Heli; Kuokkala, Veli-Tapani; Vuoristo, Petri

    2016-06-01

    High-velocity impact wear can have a significant effect on the lifetime of thermally sprayed coatings in multiple applications, e.g., in the process and paper industries. Plasma-sprayed oxide coatings, such as Cr2O3- and TiO2-based coatings, are often used in these industries in wear and corrosion applications. An experimental impact study was performed on thermally sprayed ceramic coatings using the High-Velocity Particle Impactor (HVPI) at oblique angles to investigate the damage, failure, and deformation of the coated structures. The impact site was characterized by profilometry, optical microscopy, and scanning electron microscopy (SEM). Furthermore, the connection between the microstructural details and impact behavior was studied in order to reveal the damage and failure characteristics at a more comprehensive level. Differences in the fracture behavior were found between the thermally sprayed Cr2O3 and TiO2 coatings, and a concept of critical impact energy is presented here. The superior cohesion of the TiO2 coating inhibited interlamellar cracking while the Cr2O3 coating suffered greater damage at high impact energies. The HVPI experiment has proven to be able to produce valuable information about the deformation behavior of coatings under high strain rates and could be utilized further in the development of wear-resistant coatings.

  8. Characterization of High-Velocity Single Particle Impacts on Plasma-Sprayed Ceramic Coatings

    Science.gov (United States)

    Kiilakoski, Jarkko; Lindroos, Matti; Apostol, Marian; Koivuluoto, Heli; Kuokkala, Veli-Tapani; Vuoristo, Petri

    2016-08-01

    High-velocity impact wear can have a significant effect on the lifetime of thermally sprayed coatings in multiple applications, e.g., in the process and paper industries. Plasma-sprayed oxide coatings, such as Cr2O3- and TiO2-based coatings, are often used in these industries in wear and corrosion applications. An experimental impact study was performed on thermally sprayed ceramic coatings using the High-Velocity Particle Impactor (HVPI) at oblique angles to investigate the damage, failure, and deformation of the coated structures. The impact site was characterized by profilometry, optical microscopy, and scanning electron microscopy (SEM). Furthermore, the connection between the microstructural details and impact behavior was studied in order to reveal the damage and failure characteristics at a more comprehensive level. Differences in the fracture behavior were found between the thermally sprayed Cr2O3 and TiO2 coatings, and a concept of critical impact energy is presented here. The superior cohesion of the TiO2 coating inhibited interlamellar cracking while the Cr2O3 coating suffered greater damage at high impact energies. The HVPI experiment has proven to be able to produce valuable information about the deformation behavior of coatings under high strain rates and could be utilized further in the development of wear-resistant coatings.

  9. Finite element analysis of the interaction between an AWJ particle and a polycrystalline alumina ceramic

    Directory of Open Access Journals (Sweden)

    P.K.D.V. Yarlagadda

    2007-07-01

    Full Text Available Purpose: Abrasive waterjet cutting involves use of a high pressure, abrasive laden waterjet at trans-sonic speeds to cut difficult-to-machine materials. The jet-material interaction depends on the nature of the material being cut, such as ductile or brittle. The brittle regime involves the generation and propagation of microcracks due to impact and many theories have been proposed in this regard. We aim to resolve the nature of the generation and propagation of cracks in such phenomena using the finite element analysis methodology.Design/methodology/approach: A 3-dimensional FE model was set up using PATRAN. The alumina ceramic was modelled as a 1-mm cube while a 0.1mm diameter half sphere was used to model a single abrasive particle. The system was imported into ABAQUS and an explicit analysis was performed. The element deletion method was used after invoking a failure criterion to estimate the number of elements removed due to a single impact. The aggregate volume of eroded material was then calculated by multiplying the number of elements removed with the volume of each element. The results of the FEA were compared with the brittle model proposed by Kim & Zeng [12].Findings: The results of the FEA indicate that mixed-mode failure is the most common form of failure in such interactions. The volume of material removed per impact from the FE results is close to 16% of those predicted by Kim & Zeng’s model.Research limitations/implications: The finite element framework presented is idealized for the case of regular cubes based on a set of assumptions.Originality/value: This finite element approach is a good tool to study the nature of interaction between a microscopic particle and a brittle material and accurately predict the erosion mechanisms in such interactions.

  10. Thermo-mechanical characterization of siliconized E-glass fiber/hematite particles reinforced epoxy resin hybrid composite

    Science.gov (United States)

    V. R., Arun prakash; Rajadurai, A.

    2016-10-01

    In this present work hybrid polymer (epoxy) matrix composite has been strengthened with surface modified E-glass fiber and iron(III) oxide particles with varying size. The particle sizes of 200 nm and process has been done on both fiber and filler by an amino functional silane 3-Aminopropyltrimethoxysilane (APTMS). Crystalline and functional groups of siliconized iron(III) oxide particles were characterized by XRD and FTIR spectroscopy analysis. Fixed quantity of surface treated 15 vol% E-glass fiber was laid along with 0.5 and 1.0 vol% of iron(III) oxide particles into the matrix to fabricate hybrid composites. The composites were cured by an aliphatic hardener Triethylenetetramine (TETA). Effectiveness of surface modified particles and fibers addition into the resin matrix were revealed by mechanical testing like tensile testing, flexural testing, impact testing, inter laminar shear strength and hardness. Thermal behavior of composites was evaluated by TGA, DSC and thermal conductivity (Lee's disc). The scanning electron microscopy was employed to found shape and size of iron(III) oxide particles adhesion quality of fiber with epoxy matrix. Good dispersion of fillers in matrix was achieved with surface modifier APTMS. Tensile, flexural, impact and inter laminar shear strength of composites was improved by reinforcing surface modified fiber and filler. Thermal stability of epoxy resin was improved when surface modified fiber was reinforced along with hard hematite particles. Thermal conductivity of epoxy increased with increase of hematite content in epoxy matrix.

  11. Effect of silica particles modified by in-situ and ex-situ methods on the reinforcement of silicone rubber

    International Nuclear Information System (INIS)

    Highlights: • In-situ and ex-situ methods were applied to modify silica particles. • In-situ method was more beneficial to preparing silica particles with high BET surface area. • Silicone rubber filled with in-situ modified silica exhibits excellent mechanical and thermal properties. - Abstract: In-situ and ex-situ methods were applied to modify silica particles in order to investigate their effects on the reinforcement of silicone rubber. Surface area and pore analyzer, laser particle size analyzer, Fourier-transform infrared spectroscopy (FTIR), contact-angle instrument, and transmission electron microscope (TEM) were utilized to investigate the structure and properties of the modified silica particles. Dynamic mechanical thermal analyzer (DMTA) was employed to characterize the vulcanizing behavior and mechanical properties of the composites. Thermogravimetric analysis (TGA) was performed to test the thermal stability of the composites. FTIR and contact angle analysis indicated that silica particles were successfully modified by these two methods. The BET surface area and TEM results reflected that in-situ modification was more beneficial to preparing silica particles with irregular shape and higher BET surface area in comparison with ex-situ modification. The DMTA and TGA data revealed that compared with ex-situ modification, the in-situ modification produced positive influence on the reinforcement of silicone rubber

  12. Effect of kaolin particle size and loading on the characteristics of kaolin ceramic support prepared via phase inversion technique

    OpenAIRE

    Siti Khadijah Hubadillah; Zawati Harun; Mohd Hafiz Dzarfan Othman; A. F. ISMAIL; Paran Gani

    2016-01-01

    In this study, low cost ceramic supports were prepared from kaolin via phase inversion technique with two kaolin particle sizes, which are 0.04–0.6 μm (denoted as type A) and 10–15 μm (denoted as type B), at different kaolin contents ranging from 14 to 39 wt.%, sintered at 1200 °C. The effect of kaolin particle sizes as well as kaolin contents on membrane structure, pore size distribution, porosity, mechanical strength, surface roughness and gas permeation of the support were investigated. Th...

  13. Impact of Particle Size of Ceramic Granule Blends on Mechanical Strength and Porosity of 3D Printed Scaffolds

    Directory of Open Access Journals (Sweden)

    Sebastian Spath

    2015-07-01

    Full Text Available 3D printing is a promising method for the fabrication of scaffolds in the field of bone tissue engineering. To date, the mechanical strength of 3D printed ceramic scaffolds is not sufficient for a variety of applications in the reconstructive surgery. Mechanical strength is directly in relation with the porosity of the 3D printed scaffolds. The porosity is directly influenced by particle size and particle-size distribution of the raw material. To investigate this impact, a hydroxyapatite granule blend with a wide particle size distribution was fractioned by sieving. The specific fractions and bimodal mixtures of the sieved granule blend were used to 3D print specimens. It has been shown that an optimized arrangement of fractions with large and small particles can provide 3D printed specimens with good mechanical strength due to a higher packing density. An increase of mechanical strength can possibly expand the application area of 3D printed hydroxyapatite scaffolds.

  14. Thermal Conductivity Measurement and Analysis of Fully Ceramic Microencapsulated fuel

    Energy Technology Data Exchange (ETDEWEB)

    Lee, H. G.; Kim, D. J.; Park, J. Y.; Kim, W. J. [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Lee, S. J. [KEPCO Nuclear Fuel, Daejeon (Korea, Republic of)

    2015-10-15

    FCM nuclear fuel is composed of tristructural isotropic(TRISO) fuel particle and SiC ceramic matrix. SiC ceramic matrix play an essential part in protecting fission product. In the FCM fuel concept, fission product is doubly protected by TRISO coating layer and SiC ceramic matrix in comparison with the current commercial UO2 fuel system of LWR. In addition to a safety enhancement of FCM fuel, thermal conductivity of SiC ceramic matrix is better than that of UO2 fuel. Because the centerline temperature of FCM fuel is lower than that of the current UO2 fuel due to the difference of thermal conductivity of fuel, an operational release of fission products from the fuel can be reduced. SiC ceramic has attracted for nuclear fuel application due to its high thermal conductivity properties with good radiation tolerant properties, a low neutron absorption cross-section and a high corrosion resistance. Thermal conductivity of ceramic matrix composite depends on the thermal conductivity of each component and the morphology of reinforcement materials such as fibers and particles. There are many results about thermal conductivity of fiber-reinforced composite like as SiCf/SiC composite. Thermal conductivity of SiC ceramics and FCM pellets with the volume fraction of TRISO particles were measured and analyzed by analytical models. Polycrystalline SiC ceramics and FCM pellets with TRISO particles were fabricated by hot press sintering with sintering additives. Thermal conductivity of the FCM pellets with TRISO particles of 0 vol.%, 10 vol.%, 20 vol.%, 30 vol.% and 40 vol.% show 68.4, 52.3, 46.8, 43.0 and 34.5 W/mK, respectively. As the volume fraction of TRISO particles increased, the measured thermal conductivity values closely followed the prediction of Maxwell's equation.

  15. Microstructure and strain rate effects on the mechanical behavior of particle reinforced epoxy-based reactive materials

    Science.gov (United States)

    White, Bradley William

    The effects of reactive metal particles on the microstructure and mechanical properties of epoxy-based composites is investigated in this work. Particle reinforced polymer composites show promise as structural energetic materials that can provide structural strength while simultaneously being capable of releasing large amounts of chemical energy through highly exothermic reactions occurring between the particles and with the matrix. This advanced class of materials is advantageous due to the decreased amount of high density inert casings needed for typical energetic materials and for their ability to increase payload expectancy and decrease collateral damage. Structural energetic materials can be comprised of reactive particles that undergo thermite or intermetallic reactions. In this work nickel (Ni) and aluminum (Al) particles were chosen as reinforcing constituents due to their well characterized mechanical and energetic properties. Although, the reactivity of nickel and aluminum is well characterized, the effects of their particle size, volume fractions, and spatial distribution on the mechanical behavior of the epoxy matrix and composite, across a large range of strain rates, are not well understood. To examine these effects castings of epoxy reinforced with 20--40 vol.% Al and 0--10 vol.% Ni were prepared, while varying the aluminum nominal particle size from 5 to 50 mum and holding the nickel nominal particle size constant at 50 mum. Through these variations eight composite materials were produced, possessing unique microstructures exhibiting different particle spatial distributions and constituent makeup. In order to correlate the microstructure to the constitutive response of the composites, techniques such as nearest-neighbor distances, and multiscale analysis of area fractions (MSAAF) were used to quantitatively characterize the microstructures. The composites were investigated under quasi-static and dynamic compressive loading conditions to characterize

  16. Effects of incorporating nanosized calcium phosphate particles on properties of whisker-reinforced dental composites.

    Science.gov (United States)

    Xu, Hockin H K; Sun, Limin; Weir, Mike D; Takagi, Shozo; Chow, Laurence C; Hockey, Bernard

    2007-04-01

    Clinical data indicate that secondary caries and restoration fracture are the most common problems facing tooth restorations. Our ultimate goal was to develop mechanically-strong and caries-inhibiting dental composites. The specific goal of this pilot study was to understand the relationships between composite properties and the ratio of reinforcement filler/releasing filler. Nanoparticles of monocalcium phosphate monohydrate (MCPM) were synthesized and incorporated into a dental resin for the first time. Silicon carbide whiskers were fused with silica nanoparticles and mixed with the MCPM particles at MCPM/whisker mass ratios of 1:0, 2:1, 1:1, 1:2, and 0:1. The composites were immersed for 1-56 days to measure Ca and PO4 release. When the MCPM/whisker ratio was changed from 0:1 to 1:2, the composite flexural strength (mean +/- SD; n = 5) decreased from 174 +/- 26 MPa to 138 +/- 9 MPa (p < 0.05). A commercial nonreleasing composite had a strength of 112 +/- 14 MPa. When the MCPM/whisker ratio was changed from 1:2 to 1:1, the Ca concentration at 56 days increased from 0.77 +/- 0.04 mmol/L to 1.74 +/- 0.06 mmol/L (p < 0.05). The corresponding PO4 concentration increased from 3.88 +/- 0.21 mmol/L to 9.95 +/- 0.69 mmol/L (p < 0.05). Relationships were established between the amount of release and the MCPM volume fraction v(MCPM) in the resin: [Ca]= 42.9 v(MCPM) (2.7), and [PO4] = 48.7 v(MCPM) (1.4). In summary, the method of combining nanosized releasing fillers with reinforcing fillers yielded Ca- and PO4-releasing composites with mechanical properties matching or exceeding a commercial stress-bearing, nonreleasing composite. This method may be applicable to the use of other Ca-PO4 fillers in developing composites with high stress-bearing and caries-preventing capabilities, a combination not yet available in any dental materials.

  17. Study on dry friction and wear resistance of a WC-Co particle reinforced iron matrix composite material

    OpenAIRE

    Zhang Peng; Zeng Shaolian; Zhang Zhiguo

    2013-01-01

    In order to select a suitable material for the rolling mill guide application, the dry sliding friction and wear resistance of a tungsten carbide combining cobalt (WC-Co) particle reinforced chromium cast iron composite material were studied. In particular, the wear resistance was discussed in detail. The results showed that the composite material demonstrates 25 times the wear resistance of high Cr cast iron, and 9 times the wear resistance of heat resistant steel. However, the average frict...

  18. Composite materials based on AlMg1SiCu aluminium alloy reinforced with halloysite particles

    OpenAIRE

    Tomiczek, B.; L.A. Dobrzański

    2013-01-01

    Purpose: The present work describes microstructure and technological, as well as mechanical properties of AlMg1SiCu matrix composite materials reinforced with halloysite particles by powder metallurgy techniques and hot extrusion. Design/methodology/approach: Mechanical milling, compacting and hot extrusion successively are considering as a method for manufacturing metal composite powders with a controlled fine microstructure and enhanced mechanical properties. Findings:...

  19. Microstructures and Mechanical Properties of TiC Particle Reinforced TiAl Composites by Spark Plasma Sintering

    Institute of Scientific and Technical Information of China (English)

    YUE Yunlong; WU Haitao; WU Bo; WANG Zhijie; YIN Haiyan; SU Tong

    2007-01-01

    Using spark plasma sintering(SPS) technique, TiC particle reinforced γ-TiAl composites were prepared with varying weight fraction of TiC powders. The effects of the TiC fractions and distributions on the properties of the composites were investigated. The composite containing 7wt% TiC had the optimum three-point bending strength of 842 MPa,which was 200 MPa greater than that of the unreinforced γ-TiAl intermetallic. The degradation of the bending strength occurred in the composites containing more than 7wt% TiC and this was believed to be attributed to agglomerated particles of TiC, which acted as crack initiation and propagation sites. The increase of strength in TiC reinforced IMCs came from the grain refinement and the interaction of dislocations with the reinforcing particles. The bending strength of the IMC containing 7wt% TiC was theoretically estimated to increase by 85 MPa and 200 MPa, respectively, by the grain refinement and dislocation strengthening, the total of which was almost in accordance with the improvement in that of the unreinforced γ-TiAl intermetallic when considering normal estimation errors.

  20. Polymer matrix composite materials reinforced by Tb0.3Dy0.7Fe1.9 magnetostrictive particles

    Directory of Open Access Journals (Sweden)

    L.A. Dobrzański

    2009-11-01

    Full Text Available The goal of this work was to describe manufacturing process of polymer matrix composite materials reinforced by Tb0.3Dy0.7Fe1.9 particles and to observe changes of physical properties (magnetic properties and magnetostriction of samples with randomly oriented magnetostrictive particles in epoxy matrix and with aligning these particles in the matrix during fabrication process.Design/methodology/approach: Polymer matrix composite materials reinforced by the Tb0.3Dy0.7Fe1.9 magnetostrictive particles fabricating method was developed during the investigations, making it possible to obtain materials with good physical properties. The influence of the concentration of the Td0.3Dy0.7Fe1.9 particles on magnetic and magnetostrictive properties was estimated. Metallographic examination of powder’s morphology as well as EDS and XRD analysis and observations the structure of composite materials were made.Findings: The influence of magnetic particle alignment is observed in the magnetic and magnetostriction responses. The magnetostrictive response improves when the magnetic particles are oriented in magnetic fields and reaches approximately 184 ppm for oriented composite materials with 25% volume fraction of Td0.3Dy0.7Fe1.9 particles.Practical implications: For potential applications in technological devices, such as sensors and actuators, it is desirable to form composite systems by combining magnetostrictive phases with matrix, in order to have giant magnetostrictive effect and, at the same time, to reduce disadvantages of monolithic material.Originality/value: The originality of this work is based on manufacturing process, especially of applying magnetic alignment for ordering Td0.3Dy0.7Fe1.9 particles during polymerization of epoxy matrix.

  1. Long-term changes in amphetamine-induced reinforcement and aversion in rats following exposure to 56Fe particle

    Science.gov (United States)

    Rabin, B. M.; Joseph, J. A.; Shukitt-Hale, B.

    Exposing rats to heavy particles produces alterations in the functioning of dopaminergic neurons and in the behaviors that depend upon the integrity of the dopaminergic system. Two of these dopamine-dependent behaviors include amphetamine-induced reinforcement, measure using the conditioned place preference procedure, and amphetamine-induced reinforcement, measured using the conditioned place preference procedure, and amphetamine-induced aversion, measured using the conditioned taste aversion. Previous research has shown that exposing rats to 1.0 Gy of 1GeV/n 56Fe particles produced a disruption of an amphetamine-induced taste aversion 3 days following exposure, but produced an apparent enhancement of the aversion 112 days following exposure. The present experiments were designed to provide a further evaluation of these results by examining taste aversion learning 154 days following exposure to 1.0Gy 56Fe particles and to establish the convergent validity of the taste aversion results by looking at the effects of exposure on the establishment of an amphetamine-induced conditioned place preference 3, 7, and 16 weeks following irradiation. The taste aversion results failed to confirm the apparent enhancement of the amphetamine-induced CTA observed in the prior experiment. However, exposure to 56Fe particles prevented the acquisition of amphetamine-induced place preference at all three-time intervals. The results are interpreted as indicating that exposure to heavy particles can produce long-term changes in behavioral functioning.

  2. Optimization of the Infrastructure of Reinforced Concrete Reservoirs by a Particle Swarm Algorithm

    Directory of Open Access Journals (Sweden)

    Kia Saeed

    2015-03-01

    Full Text Available Optimization techniques may be effective in finding the best modeling and shapes for reinforced concrete reservoirs (RCR to improve their durability and mechanical behavior, particularly for avoiding or reducing the bending moments in these structures. RCRs are one of the major structures applied for reserving fluids to be used in drinking water networks. Usually, these structures have fixed shapes which are designed and calculated based on input discharges, the conditions of the structure's topology, and geotechnical locations with various combinations of static and dynamic loads. In this research, the elements of reservoir walls are first typed according to the performance analyzed; then the range of the membrane based on the thickness and the minimum and maximum cross sections of the bar used are determined in each element. This is done by considering the variable constraints, which are estimated by the maximum stress capacity. In the next phase, based on the reservoir analysis and using the algorithm of the PARIS connector, the related information is combined with the code for the PSO algorithm, i.e., an algorithm for a swarming search, to determine the optimum thickness of the cross sections for the reservoir membrane’s elements and the optimum cross section of the bar used. Based on very complex mathematical linear models for the correct embedding and angles related to achain of peripheral strengthening membranes, which optimize the vibration of the structure, a mutual relation is selected between the modeling software and the code for a particle swarm optimization algorithm. Finally, the comparative weight of the concrete reservoir optimized by the peripheral strengthening membrane is analyzed using common methods. This analysis shows a 19% decrease in the bar’s weight, a 20% decrease in the concrete’s weight, and a minimum 13% saving in construction costs according to the items of a checklist for a concrete reservoir at 10,000 m3.

  3. Effect of Silane Treatment on Hybridized Use of Short Cellulose Fibers and Silica Particles for Natural Rubber Reinforcement

    Science.gov (United States)

    Lopattananon, Natinee; Jitkalong, Dolmalik; Seadan, Manus; Sakai, Tadamoto

    Processability, swelling and tensile properties of natural-rubber-based hybrid composites prepared by mixing short cellulose fibers and fine silica particles of equal contents with total loading of 20 phr using a two-roll mill were analyzed. Their properties were compared with those of natural rubber reinforced with single filler (silica or cellulose fiber) and corresponding unfilled natural rubber. The tensile test showed the reinforcing effect of both single filler system and hybrid filler system in relation to natural rubber. The tensile modulus and tensile strength of hybrid composites generally laid between those of fiber-reinforced and silica-reinforced natural rubber composites, whereas the elongation at break of hybrid composites was equal to that of single filler reinforcement system. The Mooney viscosity of silica-filled compound was much higher than that of unfilled natural rubber and short fiber-filled compounds, and was significantly reduced when hybridized fillers were used. Furthermore, a silane coupling agent, Si 69, was used to modify the surface properties of cellulose fibers and silica particles. Three microscopic evaluation techniques, that is, elemental X-ray mapping (EDX), 3D microfocus X-ray scanning, and N-ARC methods were applied to investigate the filler dispersion/mixing effects. It was found that both of the fillers were more homogeneously dispersed in the hybrid composites, and the affinity between the fillers and natural rubber was improved after the silane treatment. The results from this work suggested that the better dispersion of short cellulose fiber/silica hybrid fillers had great advantages in rubber processing, and allowed for equal or higher composite strength compared to a simply silica-filled composite system.

  4. Nanoparticle Capture During Directional Solidification of Nano-Sized SiC Particle-Reinforced AZ91D Composites.

    Science.gov (United States)

    Zhu, Qiaobo; Liu, Hongchang; Li, Wenzhen; Gao, Weiming; Li, Qiushu

    2015-05-01

    The capture/push behavior of a particle in front of a solidification interface was analyzed theoretically and experimentally in this work. Van der Waals force, viscous force, and force due to interfacial energy played important roles in the particle capture/push process. Directional solidification experiments were conducted with nano-sized SiC particle-reinforced AZ91D composites to observe the distribution of nanoparticles in different solidification morphologies under varied cooling rates. When the composite solidified with plane manner, the nanoparticles could be captured by the solidification front and distributed uniformly in the matrix. When solidified with columnar or equiaxial manners, the nanoparticles could be captured by the solidification front but distributed uniformly only in the grain boundary as a result of the difference in interfacial energy and wettability between SiC/α-Mg and SiC/eutectic phase. Theoretical prediction of particle capture was in agreement with the experiment results.

  5. Corrosion resistance of enamel coating modified by calcium silicate and sand particle for steel reinforcement in concrete

    Science.gov (United States)

    Tang, Fujian

    Porcelain enamel has stable chemical property in harsh environments such as high temperature, acid and alkaline, and it can also chemically react with substrate reinforcing steel resulting in improved adherence strength. In this study, the corrosion resistances of enamel coating modified by calcium silicate and sand particles, which are designed for improved bond strength with surrounding concrete, were investigated in 3.5 wt% NaCl solution. It consists of two papers that describe the results of the study. The first paper investigates the corrosion behavior of enamel coating modified by calcium silicate applied to reinforcing steel bar in 3.5 wt% NaCl solution by OCP, electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization. The coatings include a pure enamel, a mixed enamel that consists of 50% pure enamel and 50% calcium silicate by weight, and a double enamel that has an inner pure enamel layer and an outer mixed enamel layer. Electrochemical tests demonstrates that both pure and double enamel coatings can significantly improve corrosion resistance, while the mixed enamel coating offers very little protection due to connected channels. The second paper is focused on the electrochemical characteristics of enamel coating modified by sand particle applied to reinforcing steel bar in 3.5 wt% NaCl solution by EIS. Six percentages by weight are considered including 5%, 10%, 20%, 30%, 50%, and 70%. Results reveal that addition of sand particle does not affect its corrosion resistance significantly. Most of the sand particles can wet very well with enamel body, while some have a weak zone which is induced during the cooling stage due to different coefficient of thermal expansion. Therefore, quality control of sand particle is the key factor to improve its corrosion resistance.

  6. Effect of Nano-SiC Particles on the Performance and Microstructure of Si3N4/SiC Composite Ceramics%纳米SiC对Si3N4/SiC复相陶瓷性能及显微结构的影响

    Institute of Scientific and Technical Information of China (English)

    张伟儒; 李勇; 陈文

    2007-01-01

    In this paper, Si3 N4/SiC composite ceramics were prepared from two different raw materials with nano-SiC particles or organic precursor. Effect of nano-SiC particles on the performance and microstructure of the Si3 N4/SiC ceramics was studied, and the relation between reinforced mechanism and microstructure of materials was also investigated.%本研究通过采用纳米SiC粉体及有机前驱体两种途径,制备了Si3N4/SiC粒子(Si3 N4/纳米SiC)复相陶瓷,研究了纳米SiC对Si3 N4/SiC复相陶瓷性能及显微结构的影响,讨论了材料强化的机制与显微结构的关系.

  7. Effect of particle size on the in vitro bioactivity, hydrophilicity and mechanical properties of bioactive glass-reinforced polycaprolactone composites

    International Nuclear Information System (INIS)

    Polycaprolactone (PCL) composite films containing 5 wt.% bioactive glass (BG) particles of different sizes (6 μm, 250 nm, 3) and sodium calcium silicate (Na2CaSiO4) phases were formed. The introduction of submicron BG particles (250 nm) was shown to improve the bioactivity of PCL films. In contrast to BG microparticles, the submicron BG particles were distributed on the film surfaces, providing a high surface exposure to SBF with an improved nanotopography. A notable increase in the stiffness and elastic modulus of the composite was also obtained. As compared to submicron BG particles, lower bioactivity and elastic modulus were acquired for PCL/BG nanoparticles. It was also shown that in spite of high specific surface area of the nanoparticles, partial crystallization during mechanical milling and agglomeration of the nanoparticles during processing decrease the bioactivity, hydrophilicity and mechanical response of the BG-reinforced PCL composites. Highlights: → The effect of Bioglass particle size on the in vitro bioactivity of polycaprolactone/Bioglass composites was studied. → Partial crystallization of bioactive glass particles during high-energy mechanical milling was shown. → The submicron BG particles (250 nm) were shown to improve the bioactivity of PCL films. → Lower bioactivity was acquired for the nanocomposite due to agglomeration and partial crystallization. → The hydrophilicity and elastic modulus of the composites were shown to depend on the size of Bioglass particles.

  8. Study on dry friction and wear resistance of a WC-Co particle reinforced iron matrix composite material

    Directory of Open Access Journals (Sweden)

    Zhang Peng

    2013-05-01

    Full Text Available In order to select a suitable material for the rolling mill guide application, the dry sliding friction and wear resistance of a tungsten carbide combining cobalt (WC-Co particle reinforced chromium cast iron composite material were studied. In particular, the wear resistance was discussed in detail. The results showed that the composite material demonstrates 25 times the wear resistance of high Cr cast iron, and 9 times the wear resistance of heat resistant steel. However, the average friction factor in the stable friction stage showed a relationship of μComposites/45 # steel > μHigh chromium cast iron/45 # steel > μHeat resistant steel/45 # steel. The wear resistance mechanism of the composite material was associated with the reinforcing particles, which protruded from the worn surface to bear the friction load when the matrix material surface was worn, thereby reducing the abrasive and adhesive wear. In addition, the matrix material possessed suitable hardness and toughness, providing a support to the reinforcements.

  9. Crack initiation and propagation behavior of WC particles reinforced Fe-based metal matrix composite produced by laser melting deposition

    Science.gov (United States)

    Wang, Jiandong; Li, Liqun; Tao, Wang

    2016-08-01

    It is generally believed that cracks in metal matrix composites (MMC) parts manufacturing are crucial to the reliable material properties, especially for the reinforcement particles with high volume fraction. In this paper, WC particles (WCp) reinforced Fe-based metal matrix composites (WCp/Fe) were manufactured by laser melting deposition (LMD) technology to investigate the characteristics of cracks formation. The section morphology of composites were analyzed by optical microscope (OM), and microstructure of WCp, matrix and interface were analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM), in order to study the crack initiation and propagation behavior under different laser process conditions. The temperature of materials during the laser melting deposition was detected by the infrared thermometer. The results showed that the cracks often appeared after five layers laser deposition in this experiment. The cracks crossed through WC particles rather than the interface, so the strength of interface obtained by the LMD was relatively large. When the thermal stress induced by high temperature gradient during LMD and the coefficient of thermal expansion mismatch between WC and matrix was larger than yield strength of WC, the cracks would initiate inside WC particle. Cracks mostly propagated along the eutectic phases whose brittleness was very large. The obtained thin interface was beneficial to transmitting the stress from particle to matrix. The influence of volume fraction of particles, laser power and scanning speed on cracks were investigated. This paper investigated the influence of WC particles size on cracks systematically, and the smallest size of cracked WC in different laser processing parameters was also researched.

  10. Method Developed for the High-Temperature Nondestructive Evaluation of Fiber-Reinforced Silicon Carbide Ceramic Matrix Composites

    Science.gov (United States)

    Goldsby, Jon C.

    1998-01-01

    Ceramic matrix composites have emerged as candidate materials to allow higher operating temperatures (1000 to 1400 C) in gas turbine engines. A need, therefore, exists to develop nondestructive methods to evaluate material integrity at the material operating temperature by monitoring thermal and mechanical fatigue. These methods would also have potential as quality inspection tools. The goal of this investigation at the NASA Lewis Research Center is to survey and correlate the temperature-dependent damping and stiffness of advanced ceramic composite materials with imposed thermal and stress histories that simulate in-service turbine engine conditions. A typical sample size of 100 by 4 by 2 cubic millimeters, along with the specified stiffness and density, placed the fundamental vibration frequencies between 100 and 2000 Hz. A modified Forster apparatus seemed most applicable to simultaneously measure both damping and stiffness. Testing in vacuum reduced the effects of air on the measurements. In this method, a single composite sample is vibrated at its fundamental tone; then suddenly, the mechanical excitation is removed so that the sample's motion freely decays with time. Typical results are illlustrated in this paper.

  11. Study on preparation and properties of molybdenum alloys reinforced by nano-sized ZrO{sub 2} particles

    Energy Technology Data Exchange (ETDEWEB)

    Cui, Chaopeng; Gao, Yimin; Zhou, Yucheng [Xi' an Jiaotong University, State Key Laboratory for Mechanical Behavior of Materials, Xi' an, Shaanxi Province (China); Wei, Shizhong [Henan University of Science and Technology, School of Materials Science and Engineering, Luoyang (China); Henan University of Science and Technology, Engineering Research Center of Tribology and Materials Protection, Ministry of Education, Luoyang (China); Zhang, Guoshang; Zhu, Xiangwei; Guo, Songliang [Henan University of Science and Technology, School of Materials Science and Engineering, Luoyang (China)

    2016-03-15

    The nano-sized ZrO{sub 2}-reinforced Mo alloy was prepared by a hydrothermal method and a subsequent powder metallurgy process. During the hydrothermal process, the nano-sized ZrO{sub 2} particles were added into the Mo powder via the hydrothermal synthesis. The grain size of Mo powder decreases obviously with the addition of ZrO{sub 2} particles, and the fine-grain sintered structure is obtained correspondingly due to hereditation. In addition to a few of nano-sized ZrO{sub 2} particles in grain boundaries or sub-boundaries, most are dispersed in grains. The tensile strength and yield strength have been increased by 32.33 and 53.76 %. (orig.)

  12. Aluminium AA6061 Matrix Composite Reinforced with Spherical Alumina Particles Produced by Infiltration: Perspective on Aerospace Applications

    Directory of Open Access Journals (Sweden)

    Claudio Bacciarini

    2014-01-01

    Full Text Available Metal matrix composites, based on AA6061 reinforced with 60 vol% Al2O3 spherical particles, were produced by gas pressure infiltration and characterized for hardness, impulse excitation modulus, tensile properties (at room temperature and at 250°C, and machining. It was experimentally demonstrated that the novel alumina powder used in the present work does not react with the liquid Mg-containing matrix during the infiltration process. The AA6061 matrix therefore retains its ability to be strengthened by precipitation heat treatment. The latter behaviour combined with the spherical particle shape confers the studied material higher strength and better machinability in comparison with similar composites produced using standard angular alumina particles. The overall features are promising for applications in the aerospace industry, where light and strong materials are required.

  13. Study on preparation and properties of molybdenum alloys reinforced by nano-sized ZrO2 particles

    International Nuclear Information System (INIS)

    The nano-sized ZrO2-reinforced Mo alloy was prepared by a hydrothermal method and a subsequent powder metallurgy process. During the hydrothermal process, the nano-sized ZrO2 particles were added into the Mo powder via the hydrothermal synthesis. The grain size of Mo powder decreases obviously with the addition of ZrO2 particles, and the fine-grain sintered structure is obtained correspondingly due to hereditation. In addition to a few of nano-sized ZrO2 particles in grain boundaries or sub-boundaries, most are dispersed in grains. The tensile strength and yield strength have been increased by 32.33 and 53.76 %. (orig.)

  14. Study on preparation and properties of molybdenum alloys reinforced by nano-sized ZrO2 particles

    Science.gov (United States)

    Cui, Chaopeng; Gao, Yimin; Wei, Shizhong; Zhang, Guoshang; Zhou, Yucheng; Zhu, Xiangwei; Guo, Songliang

    2016-03-01

    The nano-sized ZrO2-reinforced Mo alloy was prepared by a hydrothermal method and a subsequent powder metallurgy process. During the hydrothermal process, the nano-sized ZrO2 particles were added into the Mo powder via the hydrothermal synthesis. The grain size of Mo powder decreases obviously with the addition of ZrO2 particles, and the fine-grain sintered structure is obtained correspondingly due to hereditation. In addition to a few of nano-sized ZrO2 particles in grain boundaries or sub-boundaries, most are dispersed in grains. The tensile strength and yield strength have been increased by 32.33 and 53.76 %.

  15. Fabrication of Al5083 surface composites reinforced by CNTs and cerium oxide nano particles via friction stir processing

    Energy Technology Data Exchange (ETDEWEB)

    Hosseini, S.A. [Department of Materials Science and Engineering, Faculty of Engineering, Shahid Chamran University of Ahvaz (Iran, Islamic Republic of); Ranjbar, Khalil, E-mail: k_ranjbar@scu.ac.ir [Department of Materials Science and Engineering, Faculty of Engineering, Shahid Chamran University of Ahvaz (Iran, Islamic Republic of); Dehmolaei, R. [Department of Materials Science and Engineering, Faculty of Engineering, Shahid Chamran University of Ahvaz (Iran, Islamic Republic of); Amirani, A.R. [12th Ghaem Street, Bld. Hashemzadeh, Shahrak Golestan, Tehran (Iran, Islamic Republic of)

    2015-02-15

    Highlights: • Using friction stir processing, an effect of CNTs and CeO{sub 2} reinforcements on mechanical and corrosion properties of Al5083 alloy is reported. • The strength of Al5083 was increased by 42%, its matrix grain size reduced five times, and hardness was doubled by the incorporation of CNTs-CeO{sub 2} mixture in the volume ratio of 75-25 respectively. • Unlike the CNTs, incorporation of nanosized CeO{sub 2} particles resulted in remarkable increase in pitting resistance of the alloy. - Abstract: In the present investigation, friction stir processing (FSP) was utilized to incorporate Multi Walled Carbon Nano Tubes (MWCNT) and nanosized cerium oxide particles into the matrix of Al5083 alloy to form surface reinforced composites. The effect of these nanosized reinforcements either separately or in the combined form, on microstructural modification, mechanical properties and corrosion resistance of FSPed Al5083 surface composites was studied. A threaded cylindrical hardened steel tool was used with the rotation speeds of 600 and 800 rpm and travel speeds of 35 and 45 mm/min and a tilt angle of 5°. Mechanical properties and corrosion resistance of FSPed samples were evaluated and compared with the base alloy. The maximum tensile strength and hardness value were achieved for the hybrid composite containing a mixture of CNTs and cerium oxide in the volume ratio of 75-25, respectively, whereas a significant increase in pitting resistance of the base alloy was obtained when cerium oxide alone was incorporated. The corrosion behavior of the samples was investigated by potentiodynamic polarization tests and assessed in term of pitting potential and passivation range. Microstructural analysis carried out by using optical and electron microscopes showed that reinforcements are well dispersed inside the nugget zone (NZ), and remarkable grain refinement is gained. The study was aimed to fabricate surface composites with improved mechanical properties and

  16. Pyrochlore free 0.67PMN-0.33PT ceramics prepared by particle-coating method

    Energy Technology Data Exchange (ETDEWEB)

    Chu, Ruiqing; Li, Yan [College of Materials Science and Engineering, Liaocheng University, Liaocheng 252059 (China); Gong, Shuwen [College of Chemistry and Chemical Engineering, Liaocheng University, Liaocheng 252059 (China); Liu, Yong [College of Materials Science and Engineering, Liaocheng University, Liaocheng 252059 (China); Li, Guorong [The State Key Lab of High Performance Ceramics and Superfinemicrostructure, Shanghai Institute of Ceramics, Chinese Academy of Science, Shanghai 200050 (China); Xu, Zhijun, E-mail: zhjxu@lcu.edu.cn [College of Materials Science and Engineering, Liaocheng University, Liaocheng 252059 (China)

    2012-08-20

    Highlights: Black-Right-Pointing-Pointer Pyrochlore-free PMN-PT powders were obtained by two-step particle-coating method. Black-Right-Pointing-Pointer Mg-citric acid polymeric complex coatings avoid the formation of pyrochlore phase. Black-Right-Pointing-Pointer Pyrochlore-free PMN-PT powders have been successfully prepared at 800 Degree-Sign C. Black-Right-Pointing-Pointer The PMN-PT ceramics sintered at 1150 Degree-Sign C exhibited excellent electrical properties. - Abstract: In present study, pyrochlore-free 0.67Pb(Mg{sub 1/3}Nb{sub 2/3})O{sub 3}-0.33PbTiO{sub 3} (0.67PMN-0.33PT) powders and ceramics have been successfully prepared. Using oxides as raw materials, pyrochlore-free 0.67PMN-0.33PT powders were obtained by two-step particle-coating method. The XRD and EDS results confirmed that the Mg-citric acid polymeric complex coatings effectively prevent the direct contact between PbO and Nb{sub 2}O{sub 5} and thus avoid the formation of pyrochlore phase. The obtained pyrochlore-free 0.67PMN-0.33PT powders at 800 Degree-Sign C showed uniform and even grain size. The 0.67PMN-0.33PT ceramics sintered at 1150 Degree-Sign C for 2 h exhibited 99% of relative density and a piezoelectric coefficient (d{sub 33}) of 576pC/N, a remnant polarization (P{sub r}) of 28.4 {mu}C/cm{sup 2}, a planar electromechanical coupling factor (k{sub p}) of 0.55 and a mechanical quality factor (Q{sub m}) of 90.

  17. Effect of kaolin particle size and loading on the characteristics of kaolin ceramic support prepared via phase inversion technique

    Directory of Open Access Journals (Sweden)

    Siti Khadijah Hubadillah

    2016-06-01

    Full Text Available In this study, low cost ceramic supports were prepared from kaolin via phase inversion technique with two kaolin particle sizes, which are 0.04–0.6 μm (denoted as type A and 10–15 μm (denoted as type B, at different kaolin contents ranging from 14 to 39 wt.%, sintered at 1200 °C. The effect of kaolin particle sizes as well as kaolin contents on membrane structure, pore size distribution, porosity, mechanical strength, surface roughness and gas permeation of the support were investigated. The support was prepared using kaolin type A induced asymmetric structure by combining macroporous voids and sponge-like structure in the support with pore size of 0.38 μm and 1.05 μm, respectively, and exhibited ideal porosity (27.7%, great mechanical strength (98.9 MPa and excellent gas permeation. Preliminary study shows that the kaolin ceramic support in this work is potential to gas separation application at lower cost.

  18. Improvement in the Design of Metal-Ceramic High Voltage Feedthroughs for use in High Energy Particle Accelerators

    CERN Document Server

    Weterings, W

    1999-01-01

    Large high-voltage devices operate in particle accelerators to steer charged particles in the desired direction. Solid and hollow rods of sintered alumina are used as insulating supports and high-voltage feedthroughs to power the electrodes of these electrostatic systems. The performance of the systems is often limited by voltage breakdown along the surface of the ceramic insulator (so-called surface flashover) or discharge between feedthrough and vacuum tank, which can lead to significant disruptions in terms of overall machine efficiency. Available results on the influence of the mechanical preparation, thermal history and particular cleaning techniques on commercially obtainable alumina samples have been studied in order to investigate possibilities for better preparation methodology of the insulating supports. Also the influence of the relative position of the feedthrough inside the vacuum tank on the high-voltage breakdown behaviour has been studied. This paper describes the theoretical and practical bac...

  19. Microstructure and mechanical properties of aluminum alloy matrix composites reinforced with Fe-based metallic glass particles

    International Nuclear Information System (INIS)

    Highlights: • Al-2024/FMG composites have been prepared by powder metallurgy method. • Mechanical milling resulted in significant grain refinement of the Al matrix. • The high strength is attributed to the refined microstructure and FMG particles. - Abstract: Fe-based metallic glass (FMG) particles reinforced Al-2024 matrix composites were fabricated by using the powder metallurgy method successfully. Mechanical alloying result in nanostructured Al-2024 matrix with a grain size of about 30 nm together with a good distribution of the FMG particles in the Al matrix. The consolidation of the composites was performed at a temperature in the super-cooled liquid region of the FMG particles, where the FMG particles act as a soft liquid-like binder, resulting in composites with low or zero porosity. The microstructure and mechanical properties of the composites were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and compression test. The yield and fracture strength of the composites are 403 MPa and 660 MPa, respectively, while retaining a considerable fracture deformation of about 12%. The strengthening mechanism is associated with the grain refinement of the matrix and uniform distribution of the FMG particles

  20. Investigations of the effects of particle properties on the wear resistance of the particle reinforced composites using a novel wear model

    Science.gov (United States)

    Prabhu, T. Ram

    2016-08-01

    A wear model is developed based on the discrete lattice spring-mass approach to study the effects of particle volume fraction, size, and stiffness on the wear resistance of particle reinforced composites. To study these effects, we have considered three volume fractions (10%, 20% and 30%), two sizes (10 × 10 and 4 × 4 sites), and two different stiffness of particles embedded in the matrix in a regular pattern. In this model, we have discretized the composite system (400 × 100 sites) into the lumped masses connected with interaction spring elements in two dimensions. The interaction elements are assumed as linear elastic and ideal plastic under applied forces. Each mass is connected to its first and second nearest neighbors by springs. The matrix and particles sites are differentiated by choosing the different stiffness values. The counter surface is simulated as a rigid body that moves on the composite material at a constant sliding speed along the horizontal direction. The governing equations are formed by equating the spring force between the pair of sites given by Hooke’s law plus external contact forces and the force due to the motion of the site given by the equation of motion. The equations are solved for the plastic strain accumulated in the springs using an explicit time stepping procedure based on a finite difference form of the above equations. If the total strain accumulated in the spring elements connected to a lump mass site exceeds the failure strain, the springs are considered to be broken, and the mass site is removed or worn away from the lattice and accounts as a wear loss. The model predicts that (i) increasing volume fraction, reducing particle size and increasing particle stiffness enhance the wear resistance of the particle reinforced composites, (ii) the particle stiffness is the most significant factor affecting the wear resistance of the composites, and (iii) the wear resistance reduced above the critical volume fraction (Vc), and Vc

  1. Fabrication of an r-Al2Ti intermetallic matrix composite reinforced with α-Al2O3 ceramic by discontinuous mechanical milling for thermite reaction

    Science.gov (United States)

    Mosleh, A.; Ehteshamzadeh, M.; Taherzadeh Mousavian, R.

    2014-10-01

    In this study, a powder mixture with an Al/TiO2 molar ratio of 10/3 was used to form an r-Al2Ti intermetallic matrix composite (IMC) reinforced with α-Al2O3 ceramic by a novel milling technique, called discontinuous mechanical milling (DMM) instead of milling and ignition of the produced thermite. The results of energy dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD) of samples with varying milling time indicate that this fabrication process requires considerable mechanical energy. It is shown that Al2Ti-Al2O3 IMC with small grain size was produced by DMM after 15 h of ball milling. Peaks for γ-TiAl as well as Al2Ti and Al2O3 are observed in XRD patterns after DMM followed by heat treatment. The microhardness of the DMM-treated composite produced after heat treatment was higher than Hv 700.

  2. Fabrication of an r-Al2Ti intermetallic matrix composite reinforced withα-Al2O3 ceramic by discontinuous mechanical milling for thermite reaction

    Institute of Scientific and Technical Information of China (English)

    A.Mosleh; M.Ehteshamzadeh; R.Taherzadeh Mousavian

    2014-01-01

    In this study, a powder mixture with an Al/TiO2 molar ratio of 10/3 was used to form an r-Al2Ti intermetallic matrix composite (IMC) reinforced withα-Al2O3 ceramic by a novel milling technique, called discontinuous mechanical milling (DMM) instead of milling and ignition of the produced thermite. The results of energy dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD) of samples with varying milling time indicate that this fabrication process requires considerable mechanical energy. It is shown that Al2Ti-Al2O3 IMC with small grain size was produced by DMM after 15 h of ball milling. Peaks forγ-TiAl as well as Al2Ti and Al2O3 are observed in XRD patterns after DMM followed by heat treatment. The microhardness of the DMM-treated composite produced after heat treatment was higher than Hv 700.

  3. Use of the Materials Genome Initiative (MGI approach in the design of improved-performance fiber-reinforced SiC/SiC ceramic-matrix composites (CMCs

    Directory of Open Access Journals (Sweden)

    Jennifer S. Snipes

    2016-07-01

    Full Text Available New materials are traditionally developed using costly and time-consuming trial-and-error experimental efforts. This is followed by an even lengthier material-certification process. Consequently, it takes 10 to 20 years before a newly-discovered material is commercially employed. An alternative approach to the development of new materials is the so-called materials-by-design approach within which a material is treated as a complex hierarchical system, and its design and optimization is carried out by employing computer-aided engineering analyses, predictive tools and available material databases. In the present work, the materials-by-design approach is utilized to design a grade of fiber-reinforced (FR SiC/SiC ceramic matrix composites (CMCs, the type of materials which are currently being used in stationary components, and are considered for use in rotating components, of the hot sections of gas-turbine engines. Towards that end, a number of mathematical functions and numerical models are developed which relate CMC constituents’ (fibers, fiber coating and matrix microstructure and their properties to the properties and performance of the CMC as a whole. To validate the newly-developed materials-by-design approach, comparisons are made between experimentally measured and computationally predicted selected CMC mechanical properties. Then an optimization procedure is employed to determine the chemical makeup and processing routes for the CMC constituents so that the selected mechanical properties of the CMCs are increased to a preset target level.

  4. Particle migration using local variation of the viscosity (LVOV) model in flow of a non-Newtonian fluid for ceramic tape casting

    DEFF Research Database (Denmark)

    Jabbaribehnam, Mirmasoud; Spangenberg, Jon; Hattel, Jesper Henri

    2016-01-01

    In this paper, the migration of secondary particles in a non-Newtonian ceramic slurry inthe tape casting process is investigated with the purpose of understanding the particle distribution patterns along the casting direction. The Ostwald-de Waele power law model for the non-Newtonian flow...... changes the particle distribution pattern from being a constant distribution to a semi-layered one. The presence of such layered structure is highly affecting the subsequent sintering process, which in turn causes anisotropic shrinkage of the dried tapes. Moreover, it is found that increasing...... the substratevelocity (casting speed) leads to a more uniform distribution of the particles inside the ceramic slurry, in which case the shear induced particle migration is dominating over the gravity induced one....

  5. Synthesis of HAP nano rods and processing of nano-size ceramic reinforced poly(L)lactic acid composites

    Science.gov (United States)

    Flanigan, Kyle Yusef

    2000-09-01

    Bone is unique among the various connective tissues in that it is a composite of organic and inorganic components. Calcium phosphates occur principally in the form of hydroxyapatite crystals {Ca10(PO4) 6(OH)2}. Secreted apatite crystals are integral to the structural rigidity of the bone. When a bone breaks, there is often a need to implant an orthotic device to support the broken bone during remodeling. Current technologies use either metal pins and screws that need to be removed (by surgery) once the healing is complete or polymeric materials that either get resorbed or are porous enough to allow bone ingrowth. Poly(L)Lactic acid and copolymers of polyglycolic acid (PGA) are thermoplastics which show promise as the matrix material in biosorbable/load bearing implants. In service this material is hydrolyzed generating water and L-lactate. Orthoses composed of neat PLLA resins require greater than three years for complete resorbtion, however; 95% of strength is lost in 2 to 3 weeks in-vitro. This has limited the deployment of load bearing PLLA to screws, pins or short bracing spans. There exists a need for the development of an implantable and biosorbable orthotic device which will retain its structural integrity long enough for remodeling and healing process to generate new bone material, about 10 weeks. The scope of this dissertation is the development of HAP nano-whisker reinforcement and a HAP/PLLA thermoplastic composite. As proof of the feasibility of generating nano-reinforcement PLLA-composites, the surface of a galleried clay, montmorillonite, was modified and clay/PLLA composites processed and then characterized. Hydroxyapatite nano-whiskers were synthesized and functionalized using organosilanes and Menhaden fish-oil (common organic dispersant). The functionalized nano-fibers were used to process HAP/PLLA composites. Characterization techniques included thermal analysis, magnetic spectroscopy, XRD and ICP analysis and electron microscopy. The

  6. Wear Characteristics of Hybrid Composites Based on Za27 Alloy Reinforced With Silicon Carbide and Graphite Particles

    Directory of Open Access Journals (Sweden)

    S. Mitrović

    2014-06-01

    Full Text Available The paper presents the wear characteristics of a hybrid composite based on zinc-aluminium ZA27 alloy, reinforced with silicon-carbide and graphite particles. The tested sample contains 5 vol.% of SiC and 3 vol.% Gr particles. Compocasting technique has been used to prepare the samples. The experiments were performed on a “block-on-disc” tribometer under conditions of dry sliding. The wear volumes of the alloy and the composite were determined by varying the normal loads and sliding speeds. The paper contains the procedure for preparation of sample composites and microstructure of the composite material and the base ZA27 alloy. The wear surface of the composite material was examined using the scanning electronic microscope (SEM and energy dispersive spectrometry (EDS. Conclusions were obtained based on the observed impact of the sliding speed, normal load and sliding distance on tribological behaviour of the observed composite.

  7. Spherically shaped micron-size particle-reinforced PMMA and PC composites for improving energy absorption capability

    Science.gov (United States)

    Kim, Hyung-ick; Kang, Eung-Chun; Jang, Jae-Soon; Suhr, Jonghwan

    2011-04-01

    The focus of this study was to experimentally investigate spherically shaped micron-size particles reinforced polymethyl methacrylate (PMMA) and polycarbonate (PC) polymer composites for improving energy absorbing capabilities such as toughness and low-velocity impact resistance. In this study, a solution mixing method was developed to fabricate both PMMA and PC polymer composites with spherically shaped micron-size polyamide- nylon 6 (PA6) particles inclusions. The morphology of the fracture surfaces of polymer composites was examined by using optical microscopy and scanning electron microscopy. Strain-rate dependent response of both PMMA and PC polymer composites was investigated by characterizing tensile and flexural properties. Low-velocity penetration testing was performed for both polymer composites and the key results observed for energy absorption capabilities are discussed in this study.

  8. Numerical Simulation of Dynamic Response of Fiber Reinforced Ceramic Matrix Composite Beam with Matrix Cracks Using Multiscale Modeling

    Institute of Scientific and Technical Information of China (English)

    Gao Xiguang; Song Yingdong; Sun Zhigang; Hu Xuteng

    2010-01-01

    A multiscale method for simulating the dynamic response of ceramic matrix composite (CMC) with matrix cracks is developed.At the global level,the finite element method is employed to simulate the dynamic response ofa CMC beam.While at the local level,the multiscale mechanical method is used to estimate the stress/strain response of the material.A distributed computing system is developed to speed up the simulation.The simulation of dynamic response of a Nicalon/CAS-Ⅱ beam being subjected to harmonic loading is performed as a numerical example.The results show that both the stress/strain responses under tension and compressive loading are nonlinear.These conditions result in a different response compared with that of elastic beam,such as:1) the displacement response is not symmetric about the axis of time;2) in the condition of small external load,the response at first order natural frequency is limited within a finite range;3) decreasing the matrix crack space will increase the displacement response of the beam.

  9. Microstructural study and densification analysis of hot work tool steel matrix composites reinforced with TiB{sub 2} particles

    Energy Technology Data Exchange (ETDEWEB)

    Fedrizzi, A., E-mail: anna.fedrizzi@ing.unitn.it [Department of Industrial Engineering, University of Trento, Via Mesiano 77, 38123 Trento (Italy); Pellizzari, M. [Department of Industrial Engineering, University of Trento, Via Mesiano 77, 38123 Trento (Italy); Zadra, M. [K4Sint, Start-up of the University of Trento, Viale Dante 300, 38057 Pergine Valsugana (Italy); Marin, E. [Department of Chemistry, Physics and Environment, University of Udine, Via Cotonificio 108, 33100 Udine (Italy)

    2013-12-15

    Hot work tool steels are characterized by good toughness and high hot hardness but are less wear resistant than other tooling materials, such as high speed steel. Metal matrix composites show improved tribological behavior, but not much work has been done in the field of hot work tool steels. In this paper TiB{sub 2}-reinforced hot work tool steel matrix composites were produced by spark plasma sintering (SPS). Mechanical alloying (MA) was proposed as a suited process to improve the composite microstructure. Density measurements and microstructure confirmed that MA promotes sintering and produces a fine and homogeneous dispersion of reinforcing particles. X-ray diffraction patterns of the sintered composites highlighted the formation of equilibrium Fe{sub 2}B and TiC, as predicted by thermodynamic calculations using Thermo-Calc® software. Scanning electron microscopy as well as scanning Kelvin probe force microscopy highlighted the reaction of the steel matrix with TiB{sub 2} particles, showing the formation of a reaction layer at the TiB{sub 2}-steel interface. Phase investigations pointed out that TiB{sub 2} is not chemically stable in steel matrix because of the presence of carbon even during short time SPS. - Highlights: • TiB{sub 2} reinforced steel matrix composites were produced by spark plasma sintering. • TiB{sub 2} was successfully dispersed in the steel matrix by mechanical alloying. • Steel and TiB{sub 2} react during sintering forming equilibrium Fe{sub 2}B and TiC. • The new phases were investigated by means of AFM, Volta potential and XRD analyses.

  10. Effect of particle size on the in vitro bioactivity, hydrophilicity and mechanical properties of bioactive glass-reinforced polycaprolactone composites

    Energy Technology Data Exchange (ETDEWEB)

    Tamjid, E. [Institute for Nanoscience and Nanotechnology (INST), Sharif University of Technology, Azadi Ave. P.O. Box: 11365-9466, 14588 Tehran (Iran, Islamic Republic of); Bagheri, R., E-mail: rezabagh@sharif.edu [Department of Materials Science and Engineering, Sharif University of Technology, Azadi Ave. P.O. Box: 11365-9466, 14588 Tehran (Iran, Islamic Republic of); Vossoughi, M. [Institute for Nanoscience and Nanotechnology (INST), Sharif University of Technology, Azadi Ave. P.O. Box: 11365-9466, 14588 Tehran (Iran, Islamic Republic of); Department of Chemical and Petroleum Engineering, Sharif University of Technology, Azadi Ave. P.O. Box: 11365-9466, 14588 Tehran (Iran, Islamic Republic of); Simchi, A., E-mail: simchi@sharif.edu [Institute for Nanoscience and Nanotechnology (INST), Sharif University of Technology, Azadi Ave. P.O. Box: 11365-9466, 14588 Tehran (Iran, Islamic Republic of); Department of Materials Science and Engineering, Sharif University of Technology, Azadi Ave. P.O. Box: 11365-9466, 14588 Tehran (Iran, Islamic Republic of)

    2011-10-10

    Polycaprolactone (PCL) composite films containing 5 wt.% bioactive glass (BG) particles of different sizes (6 {mu}m, 250 nm, < 100 nm) were prepared by solvent casting methods. The ultra-fine BG particles were prepared by high-energy mechanical milling of commercial 45S5 Bioglass (registered) particles. The characteristics of bioactive glass particles were studied by field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), dynamic light scattering (DLS), and X-ray diffraction (XRD) methods. In vitro bioactivity of the PCL/BG composite films was evaluated through immersion in the simulated body fluid (SBF). The films were analyzed by FE-SEM, energy dispersive spectrometry (EDS), XRD, and atomic force microscopy (AFM). The mechanical properties of highly-porous PCL/BG composites were examined on cylindrical specimens under quasi-static compression load. It was found that partial crystallization of amorphous BG particles during a prolonged mechanical milling occurred and calcium silicate (CaSiO{sub 3}) and sodium calcium silicate (Na{sub 2}CaSiO{sub 4}) phases were formed. The introduction of submicron BG particles (250 nm) was shown to improve the bioactivity of PCL films. In contrast to BG microparticles, the submicron BG particles were distributed on the film surfaces, providing a high surface exposure to SBF with an improved nanotopography. A notable increase in the stiffness and elastic modulus of the composite was also obtained. As compared to submicron BG particles, lower bioactivity and elastic modulus were acquired for PCL/BG nanoparticles. It was also shown that in spite of high specific surface area of the nanoparticles, partial crystallization during mechanical milling and agglomeration of the nanoparticles during processing decrease the bioactivity, hydrophilicity and mechanical response of the BG-reinforced PCL composites. Highlights: {yields} The effect of Bioglass particle size on the in vitro bioactivity of

  11. Particle Board and Oriented Strand Board Prepared with Nanocellulose-Reinforced Adhesive

    OpenAIRE

    Stefan Veigel; Jörn Rathke; Martin Weigl; Wolfgang Gindl-Altmutter

    2012-01-01

    Adhesives on the basis of urea-formaldehyde (UF) and melamine-urea-formaldehyde (MUF) are extensively used in the production of wood-based panels. In the present study, the attempt was made to improve the mechanical board properties by reinforcing these adhesives with cellulose nanofibers (CNFs). The latter were produced from dissolving grade beech pulp by a mechanical homogenization process. Adhesive mixtures with a CNF content of 0, 1, and 3 wt% based on solid resin were prepared by mixing ...

  12. Spatial Gradients in Particle Reinforced Polymers Characterized by X-Ray Attenuation and Laser Confocal Microscopy

    Energy Technology Data Exchange (ETDEWEB)

    LAGASSE,ROBERT R.; THOMPSON,KYLE R.

    2000-06-12

    The goal of this work is to develop techniques for measuring gradients in particle concentration within filled polymers, such as encapsulant. A high concentration of filler particles is added to such materials to tailor physical properties such as thermal expansion coefficient. Sedimentation and flow-induced migration of particles can produce concentration gradients that are most severe near material boundaries. Therefore, techniques for measuring local particle concentration should be accurate near boundaries. Particle gradients in an alumina-filled epoxy resin are measured with a spatial resolution of 0.2 mm using an x-ray beam attenuation technique, but an artifact related to the finite diameter of the beam reduces accuracy near the specimen's edge. Local particle concentration near an edge can be measured more reliably using microscopy coupled with image analysis. This is illustrated by measuring concentration profiles of glass particles having 40 {micro}m median diameter using images acquired by a confocal laser fluorescence microscope. The mean of the measured profiles of volume fraction agrees to better than 3% with the expected value, and the shape of the profiles agrees qualitatively with simple theory for sedimentation of monodisperse particles. Extending this microscopy technique to smaller, micron-scale filler particles used in encapsulant for microelectronic devices is illustrated by measuring the local concentration of an epoxy resin containing 0.41 volume fraction of silica.

  13. Effect of the Addition MgO Nano Particle to Mechanical Properties and Microstructure of ZTA Ceramic Composite

    International Nuclear Information System (INIS)

    The mechanical properties and microstructure of zirconia-toughened alumina ceramic composite doped with nano particle of MgO is investigated. The nano-MgO weight percent was varied from 0 wt% to 1.3 wt%. Each batch of composition was mixed using ultrasonic cleaning and mechanical stirrer, uniaxially pressed and sintered at 1600 degree Celsius for 4 h in pressureless conditions. Analysis of bulk density, Vickers hardness, fracture toughness and microstructural observation has been carried out. Results of Vickers hardness increased linearly with addition of more nano-MgO until a certain composition. Maximum Vickers hardness obtained was 1740HV with 1.1 wt % MgO. (author)

  14. Engineered emissivity of textile fabrics by the inclusion of ceramic particles.

    Science.gov (United States)

    Pooley, Matthew A; Anderson, David M; Beckham, Haskell W; Brennan, James F

    2016-05-16

    Composite textile materials, created from a blend of different fibers, have long been used to engineer the properties and performance of fabrics to combine comfort with functionality, such as to create materials with differing optical properties. Some changes to the optical properties of materials in the infrared are subtle and difficult to measure. We present a measurement technique, experimental apparatus, and associated data analysis procedure for detecting small changes in the emissivity of fabrics in the mid-infrared wavelength range (7.5-14 µm). Using this technique, we demonstrate that the emissivity of polyester fabric can be engineered controllably via the inclusion of ceramic microparticles within the fabric fibers.

  15. Preparation and properties of TiB{sub 2} particles reinforced Cu–Cr matrix composite

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Pengchao [School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024 (China); Jie, Jinchuan, E-mail: jiejc@dlut.edu.cn [Laboratory of Special Processing of Raw Materials, Dalian University of Technology, Dalian 116024 (China); Gao, Yuan; Li, Hang; Cao, Zhiqiang [School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024 (China); Wang, Tongmin, E-mail: tmwang@dlut.edu.cn [School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024 (China); Li, Tingju [Laboratory of Special Processing of Raw Materials, Dalian University of Technology, Dalian 116024 (China)

    2015-08-26

    Cu–0.5Cr–1.5TiB{sub 2} composites prepared by different melting processes were investigated in the present study. The optimum reaction temperature for the dispersed distribution of TiB{sub 2} particles is 1300 °C and a higher temperature is not appropriate due to the high loss of solute elements. Holding time should be 10 min to make TiB{sub 2} particles exhibit a relatively homogeneous distribution in the matrix. An argon shield is necessary to ensure obtaining the desired chemistry. The typical TiB{sub 2} particles with equiaxed and symmetric morphology are observed in the matrix, while particles with irregular morphology are obtained when the growth process is inhibited by adjacent particles. After aging, the better mechanical properties are obtained by composite prepared at the optimum melting process. Strengthening is comprised of a dislocation pile-up mechanism of TiB{sub 2} particles, precipitation strengthening of Cr particles and strain strengthening. TiB{sub 2} particles slightly decrease the electrical conductivity, which indicates a minor contribution from interface scattering. The conductivity exhibits an obvious increase after aging because of the sharp decline of impurity scattering.

  16. Reinforced SiC/Al composite layer produced by laser particle injection

    NARCIS (Netherlands)

    Vreeling, J.A.; Ocelik, V.; Pei, Y.T.; de Hosson, J.T.M.; Brebbia, CA; Kenny, JM

    1999-01-01

    SiC particles with a mean size of 80 mu m were injected into Al substrate:by the laser particle injection process with the aim to improve the surface properties of aluminium. Experimental difficulties induced by the big difference in absorptivity of laser energy between Al and SiC lead to an extreme

  17. Effect of particle concentration on the structure and tribological properties of submicron particle SiC reinforced Ni metal matrix composite (MMC) coatings produced by electrodeposition

    Science.gov (United States)

    Gül, H.; Kılıç, F.; Uysal, M.; Aslan, S.; Alp, A.; Akbulut, H.

    2012-03-01

    In the present work, a nickel sulfate bath containing SiC submicron particles between 100 and 1000 nm was used as the plating electrolyte. The aim of this work is to obtain Ni-SiC metal matrix composites (MMCs) reinforced with submicron particles on steel surfaces with high hardness and wear resistance for using in anti-wear applications such as dies, tools and working parts for automobiles and vehicles. The influence of the SiC content in the electrolyte on particle distribution, microhardness and wear resistance of nano-composite coatings was studied. During the electroplating process, the proper stirring speed was also determined for sub-micron SiC deposition with Ni matrix. The Ni films were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis. The depositions were controlled to obtain a specific thickness (between 50 and 200 μm) and volume fraction of the particles in the matrix (between 0.02 and 0.10). The hardness of the coatings was measured to be 280-571 HV depending on the particle volume in the Ni matrix. The tribological behaviors of the electrodeposited SiC nanocomposite coatings sliding against an M50 steel ball (Ø 10 mm) were examined on a tribometer. All the friction and wear tests were performed without lubrication at room temperature and in the ambient air (with a relative humidity of 55-65%). The results showed that the wear resistance of the nanocomposites was approximately 2-2.2 times more than those of unreinforced Ni.

  18. Fabrication and characterization of hybrid structured Al alloy matrix composites reinforced by high volume fraction of B4C particles

    International Nuclear Information System (INIS)

    In the present paper, hybrid structured B4C particles reinforced Al2024 matrix composites were prepared by the powder metallurgy method. The composites made from 100% mechanical milled composite powders have fracture strength of 670 MPa. With the addition of un-milled Al2024 powder increased from 10 vol% to 40 vol%, the room temperature compression strength decreased from 1115 MPa to 739 MPa, without any visible plastic deformation. However, when the fraction of un-milled Al2024 powder increased to 50 vol%, the compression strength was decreased to 580 MPa, while retaining a remarkable fracture strain up to 10%. The microstructures of the composites with different composition were examined by a scanning electron microscope and a transmission electron microscope. The contribution from different strengthening mechanisms was discussed. The hybrid structures are proved to account for the dramatic change of the fracture mechanism of the composites

  19. Research on Spatial Distribution of Reinforcements in Si Particle Reinforced Aluminum Matrix Composites%硅颗粒增强铝基复合材料增强体分布均匀性研究

    Institute of Scientific and Technical Information of China (English)

    宁晓兵; 杨永顺; 杨茜; 郭俊卿; 陈超群

    2013-01-01

    利用行星球磨机和Y型混料机混料,对两种混料方法得到的混合金属粉末,分别采用粉末冶金工艺制备硅颗粒增强铝基复合材料,研究了混料方法对硅颗粒增强体在铝基体中分布均匀性的影响.结果表明,利用行星球磨机混料可以改变粉末颗粒的表面形状和粒度大小,并使硅颗粒均匀分布在铝基体中,是实现增强体颗粒与基体颗粒均匀混合的有效方法.利用Y型混料机混料不能改变粉末颗粒的形貌及粒度大小,制备的铝基复合材料中有硅颗粒偏聚的情况.%Silicon particulate reinforced aluminum matrix composites (Al MMCs) were prepared by powder metallurgical (P/M) method.The effect of two kinds of ball milling methods of Y type mixer mixing and high energy ball milling on the spatial distribution of reinforcements in Al MMCs was investigated.The results show that,using high energy ball milling can improve the surface shape of reinforcements,change the particle size and make reinforcements uniform distribution,which is an effective method to achieve the uniform mixture of reinforced particles and matrix particle.There are clusters of silicon particles in the aluminum matrix composites using Y type mixer mixing.

  20. Wear resistance and corrosion resistance of VCp particle reinforced stainless steel composites

    Institute of Scientific and Technical Information of China (English)

    YAO Xiu-rong; HAN Jie-cai; ZUO Hong-bo; LIU Zhao-jing; LI Feng-zhen; REN Shan-zhi

    2005-01-01

    The VCp reinforced stainless steel composite was produced by in-situ reaction casting. The composite was tested for its wear resistance under the wet abrasive condition and corrosion resistance, compared with the wear-resistant white iron and stainless steel. The results show that the wear resistance of the composite is slightly inferior to that of the white iron, but much better than that of the stainless steel under the wet grinding abrasive condition. The corrosion resistance of the composite is much better than that of the white iron in the acid medium,and a little worse than that of the stainless steel. Thus the composite exhibits superior properties of wear resistance and corrosion resistance.

  1. ANL-1(A) - Development of nondestructive evaluation methods for structural ceramics

    International Nuclear Information System (INIS)

    This section includes the following papers: Development of Nondestructive Evaluation Methods for Structural Ceramics; Effects of Flaws on the Fracture Behavior of Structural Ceramics; Design, Fabrication, and Interface Characterization of Ceramic Fiber-Ceramic Matrix Composites; Development of Advanced Fiber-Reinforced Ceramics; Modeling of Fibrous Preforms for CVD Infiltration; NDT of Advanced Ceramic Composite Materials; Joining of Silicon Carbide Reinforced Ceramics; Superconducting Film Fabrication Research; Short Fiber Reinforced Structural Ceramics; Structural Reliability and Damage Tolerance of Ceramic Composites for High-Temperature Applications; Fabrication of Ceramic Fiber-Ceramic Matrix Composites by Chemical Vapor Infiltration; Characterization of Fiber-CVD Matrix interfacial Bonds; Microwave Sintering of Superconducting Ceramics; Improved Ceramic Composites Through Controlled Fiber-Matrix Interactions; Evaluation of Candidate Materials for Solid Oxide Fuel Cells; Ceramic Catalyst Materials: Hydrous Metal Oxide Ion-Exchange Supports for Coal Liquefaction; and Investigation of Properties and Performance of Ceramic Composite Components

  2. Novel titanium particles reinforced Zr-based bulk metallic glass composites prepared by infiltration casting

    Institute of Scientific and Technical Information of China (English)

    Cuimei Zhang; Xidong Hui; Meiling Wang; Guoliang Chen

    2008-01-01

    A novel Ti/Zr41.2Ti13.8Cu12.5Ni10.0Be22.5 composite was successfully prepared by infiltrating the melt into sintered Ti preform. It shows that the introduction of Ti particles into the composite results in an increase in elastic strain to 3% and an enhancement of the strength up to 2.1 GPa. High specific strength has been obtained because of the decrease in density of the composite. It is suggested that an improvement in the mechanical properties of the composite may be attributed to the generation of multiple shear bands and some deformation in the Ti particles.

  3. Improving the ballistic performance of ultra high molecular weight polyethylene fiber reinforced composites using conch particles

    International Nuclear Information System (INIS)

    A new method was proposed to improve ballistic impact performance of unidirectional ultra high molecular weight polyethylene (UHMWPE) fiber plate (UD plate) by adding shell particles in matrix. The complex micro-laminate structure of these bio-composite materials was studied. It was revealed by Scanning Electron Microscopy (SEM) and Fourier Transform Infrared Spectroscopy (FT-IR) spectra that modified shell particles were uniformly dispersed in the matrix. The results of ballistic tests and temperature adaptation tests demonstrated that the bulletproof property of the modified UD plate was improved by 20%.

  4. Development of Particle Reinforced Copper Matrix Composites%颗粒增强铜基复合材料的发展

    Institute of Scientific and Technical Information of China (English)

    秦改元

    2011-01-01

    Particle reinforced copper matrix composites have excellent comprehensive properties, and recently become a hot spot of research and development. This paper discussed the preparation method of particle reinforced copper matrix composites, the selection of reinforced phase and strengthening method, prospected the development trend of copper matrix composites.%颗粒增强铜基复合材料有着优良的综合性能,成为了近期研究开发的热点.本文论述了颗粒增强铜基复合材料的制备方法,增强相的选择及强化方法,展望了铜基复合材料的发展趋势.

  5. The Microstructure-Processing-Property Relationships in an Al Matrix Composite System Reinforced by Al-Cu-Fe Alloy Particles

    Energy Technology Data Exchange (ETDEWEB)

    Fei Tang

    2004-12-19

    Metal matrix composites (MMC), especially Al matrix composites, received a lot of attention during many years of research because of their promise for the development of automotive and aerospace materials with improved properties and performance, such as lighter weight and better structural properties, improved thermal conductivity and wear resistance. In order to make the MMC materials more viable in various applications, current research efforts on the MMCs should continue to focus on two important aspects, including improving the properties of MMCs and finding more economical techniques to produce MMCs. Solid state vacuum sintering was studied in tap densified Al powder and in hot quasi-isostatically forged samples composed of commercial inert gas atomized or high purity Al powder, generated by a gas atomization reaction synthesis (GARS) technique. The GARS process results in spherical Al powder with a far thinner surface oxide. The overall results indicated the enhanced ability of GARS-processed Al and Al alloy powders for solid state sintering, which may lead to simplification of current Al powder consolidation processing methods. Elemental Al-based composites reinforced with spherical Al-Cu-Fe alloy powders were produced by quasi-isostatic forging and vacuum hot pressing (VHP) consolidation methods. Microstructures and tensile properties of AYAl-Cu-Fe composites were characterized. It was proved that spherical Al-Cu-Fe alloy powders can serve as an effective reinforcement particulate for elemental Al-based composites, because of their high hardness and a preferred type of matrix/reinforcement interfacial bonding, with reduced strain concentration around the particles. Ultimate tensile strength and yield strength of the composites were increased over the corresponding Al matrix values, far beyond typical observations. This remarkable strengthening was achieved without precipitation hardening and without severe strain hardening during consolidation because of

  6. Preparation and properties of CaO-Al2O3-SiO2 glass-ceramics by sintered frits particle from mining wastes

    Directory of Open Access Journals (Sweden)

    He F.

    2014-01-01

    Full Text Available The paper reports on some experimental results obtained from the production of glass-ceramics containing gold tailings powder (GTP. Frits particle sintered technology was used to prepare glass ceramic products. SiO2, CaO, ZnO, BaO and B2O3 were selected to adjust the composition of the glass. Based on the results of differential thermal analysis (DTA, the nucleation and crystallization temperature of parent glass samples with different schedule were identified, respectively. X-ray diffraction (XRD analysis of the produced glass-ceramics materials revealed that the main crystalline phase was β-wollastonite. With the increasing of CaO content, the intensity of crystal diffractive peaks also increases. The formation of β-wollastonite crystal could be accelerated by the increasing of CaO. The glass-ceramics with fine microstructure showed better physical, mechanical properties and chemical resistance. Overall results indicated that it was a feasible attempt to produce glass-ceramics for building and decorative materials from waste materials. The amount of GTP used in the glass batches was more than 65 wt% of the whole raw.

  7. CROWDED HYBRID PANEL MANUFACTURED WITH PEANUT HULLS REINFORCED WITH ITAÚBA WOOD PARTICLES

    Directory of Open Access Journals (Sweden)

    Guilherme Barbirato

    2014-09-01

    Full Text Available http://dx.doi.org/10.5902/1980509815726In this paper, it was considered the study of the potential use of peanut hulls and wood particles of itaúba (Mezilaurus itauba species in order to add value to these materials through the manufacture of hybrid particle board in order to compare the physical and mechanical performances as well as durability. For these procedures, it was used the bi-component polyurethane resin based on castor beans (mammon oil and urea-formaldehyde. The product quality was evaluated based on the requirements of the standards NBR 14.810:2006 APA PRP and 108, through physico-mechanical and microstructural durability. The results indicate that the incorporation of wood particles warrants an increase in physical-mechanical properties of the particleboard manufactured with peanut hulls, the polyurethane resin based on castor oil was effective as a particle adhesive binder and the durability assay indicated that the material should be used under conditions of low exposure to moisture.

  8. Tungsten particle reinforced Al 5083 composite with high strength and ductility

    Energy Technology Data Exchange (ETDEWEB)

    Bauri, Ranjit, E-mail: rbauri@iitm.acin; Yadav, Devinder; Shyam Kumar, C.N.; Balaji, B.

    2015-01-03

    Tungsten particles were incorporated into an Al 5083 matrix by friction stir processing (FSP). FSP resulted in uniform dispersion of the tungsten particles with excellent interfacial bonding and more importantly without the formation of any harmful intermetallics. For the first time, the particles penetrated to a depth equal to the full pin length of the tool. A novel aspect of the 5083 Al–W composite is that it showed an improvement of more than 100 MPa in the UTS and at the same time exhibited a high ductility (30%). The ductility was also evident from the well defined dimples in the fracture surface which also revealed the superior bonding between the particles and the matrix. FSP also resulted in substantial grain refinement of the Al matrix. Electron backscatter diffraction (EBSD) and transmission electron microscopy analysis revealed that the fine grains formed by dynamic recrystallization. A gradual transformation from sub-grain to high-angle grain boundaries was observed from EBSD analysis pointing towards the occurrence of a continuous type of dynamic recrystallization process.

  9. Tungsten particle reinforced Al 5083 composite with high strength and ductility

    International Nuclear Information System (INIS)

    Tungsten particles were incorporated into an Al 5083 matrix by friction stir processing (FSP). FSP resulted in uniform dispersion of the tungsten particles with excellent interfacial bonding and more importantly without the formation of any harmful intermetallics. For the first time, the particles penetrated to a depth equal to the full pin length of the tool. A novel aspect of the 5083 Al–W composite is that it showed an improvement of more than 100 MPa in the UTS and at the same time exhibited a high ductility (30%). The ductility was also evident from the well defined dimples in the fracture surface which also revealed the superior bonding between the particles and the matrix. FSP also resulted in substantial grain refinement of the Al matrix. Electron backscatter diffraction (EBSD) and transmission electron microscopy analysis revealed that the fine grains formed by dynamic recrystallization. A gradual transformation from sub-grain to high-angle grain boundaries was observed from EBSD analysis pointing towards the occurrence of a continuous type of dynamic recrystallization process

  10. Synthesis and Characterization of SiC Reinforced HE-30 Al Alloy Particulate MMCs

    OpenAIRE

    Pradyumna Phutane; VijayKumar S. Jatti; Ravi Sekhar; Singh, T.P.

    2013-01-01

    Metal matrix composites have evoked a keen interest in recent times for potential applications in many areas, especially aerospace & automotive industries owing to their superior strength to weight ratio. A particle reinforced metal matrix composite consists of uniform distribution of strengthening ceramic particles embedded within metal matrix. Manufacturing of aluminum alloy based composites via stir casting is one of the prominent and economical routes for processing of metal matrix compos...

  11. Estimation of Biocompatibility of Nano-Sized Ceramic Particles with Osteoblasts, Osteosarcomas and Hepatocytes by Static and Time-Lapse Observation.

    Science.gov (United States)

    Abe, Shigeaki; Seitoku, Eri; Iwadera, Nobuki; Hamba, Yusuke; Yamagata, Shuichi; Akasaka, Tsukasa; Kusaka, Teruo; Inoue, Satoshi; Yawaka, Yasutaka; Iida, Junichiro; Sano, Hidehiko; Yonezawa, Tetsu; Yoshida, Yasuhiro

    2016-03-01

    We assessed the biocompatibility of nano-sized ceramic particles with several cells types. Though these particles have less than 100 nm in diameter, they act as submicron-sized particles in saline by aggregation that was estimated using laser diffraction particle size analysis (LDS). they act as submicro-sized particles in saline by aggregation based on laser diffraction particle size analysis (LDS). Several types of cells (osteoblasts, osteosarcoma and hepatocyte cells) were exposed to these particles and their cytocompatibility was estimated. Not only the cytotoxic assay but also their static and dynamic morphology under nanoparticles exposure were investigated. The intercellular uptake of particles was determined using a confocal fluorescence microscope. The particles used in this study did not inhibit cellular activity or growth even when their concentrations were high. Only copper oxide particles caused acute cytotoxicity depending on the particle size. The cytotoxicity assay, dynamic behavior of the nanoparticle-exposed cells and their examination under a confocal fluorescence microscope suggests that the irritative reaction was induced by contact between the cells and particles, whereas eluted copper ions are not dominant factor. These results indicate that nano-sized particles used in this study have excellent biocompatibility except copper oxide ones.

  12. The use of nano-particles to produce iridescent metallic effects on ancient ceramic objects.

    Science.gov (United States)

    Fermo, P; Padeletti, G

    2012-11-01

    Nano-sized materials have been often used in the past to realize objects with particular characteristics. One of the most outstanding examples is represented by luster pottery, showing shining surfaces with particular optical properties. Luster was one of the most sophisticated technique for the decoration of majolicas. It consists of a thin metallic film containing silver, copper and other substances, like iron oxide and cinnabar, applied in a reducing atmosphere on a previously glazed ceramic. In such a way, beautiful iridescent reflections of different colours (in particular gold and ruby-red) are obtained. This technique, at first developed in Iraq, was introduced in Italy from Spain. In Italy the potters of the two centres of Gubbio and Deruta, in central Italy, became so expert that nowadays modern artisans are not able to reproduce the wonderful effects obtained during Renaissance. A complete characterization by means of numerous techniques has been carried out on a great number of shards and precious work of arts conserved in many important museums. This allowed to draw some correlations between the preparation technique and the obtained nano-structure. PMID:23421282

  13. Cytocompatibility of HeLa Cells to Nano-Sized Ceramics Particles.

    Science.gov (United States)

    Seitoku, Eri; Abe, Shigeaki; Kusaka, Teruo; Nakamura, Mariko; Inoue, Satoshi; Yoshida, Yasuhiro; Sano, Hidehiko

    2016-04-01

    In this study, we investigated the behaviors and cytocompatibility response of human cervical carcinoma (HeLa) cells expose to nano-sized particles. Cultivated cells exposed to titanium oxide and indium oxide nanoparticles remained highly viable. In the presence of copper oxide (CuO); however, the cells became seriously inflamed. To understand the mechanism by which CuO causes cell death, we evaluated cell death and apoptosis cytometry. CuO induced cells apoptosis more strongly than exposure to titania nanoparticles. Confocal fluorescence microscopy revealed that the nano-sized particles penetrate the cells.

  14. Recovery and Modification of Waste Tire Particles and Their Use as Reinforcements of Concrete

    OpenAIRE

    Eduardo Sadot Herrera-Sosa; Gonzalo Martínez-Barrera; Carlos Barrera-Díaz; Epifanio Cruz-Zaragoza; Fernando Ureña-Núñez

    2015-01-01

    Environmental pollution caused by solid wastes is increasing in the last decades; one of these is referred to automotive tires, which are recycled by different methods, including mechanical grinding. One of the most recurrent applications is to use recycled particles as fillers in building materials, as hydraulic concrete. Nevertheless, detrimental values on the mechanical properties are obtained when they are added. For solving these problems, in this work, a novel proposal is to modify the ...

  15. Experimental investigation of viscosity and thermal conductivity of suspensions containing nanosized ceramic particles

    Directory of Open Access Journals (Sweden)

    H.P. Schuchmann

    2008-12-01

    Full Text Available Purpose: In this study we report measurements of effective thermal conductivity by using 3ω methodand effective viscosity by vibro-viscometer for SiO2-water and Al2O3-water nanofluids at different particleconcentrations and temperatures.Design/methodology/approach: The effective thermal conductivity of nanofluids is measured by a techniquebased on a hot wire thermal probe with ac excitation and 3ω lock-in detection. There is presented an experimentalstudy of thermal conductivity and viscosity of nanofluids. It was investigated Alumina and Silica nanoparticles inwater with different particle concentrations.Findings: Measured results showed that the effective thermal conductivity of nanofluids increase as theconcentration of the particles increase but not anomalously as indicated in the majority of the literature and thisenhancement is very close to Hamilton-Crosser model, also this increase is independent of the temperature. Theeffective viscosities of these nanofluids increased by the increasing particle concentration and decrease by theincrease in temperature, and can not be predicted by Einstein model.Practical implications: The results show that for our samples, thermal conductivity values are inside the limitsof (moderately lower than Hamilton-Crosser model.Originality/value: Experiments at different temperatures show that relative thermal conductivity of nanofluidsis not related with the temperature of the fluid.

  16. Glass/Ceramic Composites for Sealing Solid Oxide Fuel Cells

    Science.gov (United States)

    Bansal, Narottam P.; Choi, Sung R.

    2007-01-01

    A family of glass/ceramic composite materials has been investigated for use as sealants in planar solid oxide fuel cells. These materials are modified versions of a barium calcium aluminosilicate glass developed previously for the same purpose. The composition of the glass in mole percentages is 35BaO + 15CaO + 5Al2O3 + 10B2O3 + 35SiO2. The glass seal was found to be susceptible to cracking during thermal cycling of the fuel cells. The goal in formulating the glass/ ceramic composite materials was to (1) retain the physical and chemical advantages that led to the prior selection of the barium calcium aluminosilicate glass as the sealant while (2) increasing strength and fracture toughness so as to reduce the tendency toward cracking. Each of the composite formulations consists of the glass plus either of two ceramic reinforcements in a proportion between 0 and 30 mole percent. One of the ceramic reinforcements consists of alumina platelets; the other one consists of particles of yttria-stabilized zirconia wherein the yttria content is 3 mole percent (3YSZ). In preparation for experiments, panels of the glass/ceramic composites were hot-pressed and machined into test bars.

  17. Comparative Evaluation of the Antibacterial Efficacy of Type II Glass lonomer Cement, Type IX Glass lonomer Cement, and AMALGOMER™ Ceramic Reinforcement by Modified “Direct Contact Test”: An in vitro Study

    Science.gov (United States)

    Assudani, Harsha G; Patil, Vidyavathi; Kukreja, Pratibha; Uppin, Chaitanya; Thakkar, Prachi

    2016-01-01

    ABSTRACT Background: Streptococcus mutans (ATCC25175) has a profound effect on the incidence of dental decay in the human population. Many studies have been performed to assess the antimicrobial activity of different cements. However, little or no information is available about the antibacterial properties of Type II glass ionomer cement (GIC), Type IX GIC, and AMALGOMER™ ceramic reinforcement (CR). Aim: To comparatively evaluate the antibacterial activity of Type II GIC, Type IX GIC, and AMALGOMER™ CR by modified direct contact test. Materials and methods: The total sample size was 72 which was divided into four study groups. Six wells were coated by each: Type II GIC, Type IX GIC, AMALGOMER™ CR, and control group (only S. mutans). Statistical analysis was done using analysis of variance and the intergroup comparison was done using post hoc Tukey test. Results: AMALGOMER™ CR was found to have a better antibacterial effect as compared with Type II and IX GIC. Conclusion: AMALGOMER™ CR can serve as a valuable cement in pediatric dentistry due to its anticariogenic property. How to cite this article: Hugar SM, Assudani HG, Patil V, Kukreja P, Uppin C, Thakkar P. Comparative Evaluation of the Antibacterial Efficacy of Type II Glass lonomer Cement, Type IX Glass Ionomer Cement, and AMALGOMER™ Ceramic Reinforcement by Modified “Direct Contact Test”: An in vitro Study. Int J Clin Pediatr Dent 2016;9(2):114-117. PMID:27365930

  18. Influence of SiC reinforcement particles on the tribocorrosion behaviour of Al-SiC{sub p} FGMs in 0.05M NaCl solution

    Energy Technology Data Exchange (ETDEWEB)

    Vieira, A C; Rocha, L A [Centre for Mechanical and Materials Technologies (CT2M) and Department of Mechanical Engineering, University of Minho, Azurem, 4800-058 Guimaraes (Portugal); Mischler, S, E-mail: catarina.vieira@engmateriais.eng.uminho.pt [Ecole Polytechnique Federale de Lausanne (EPFL), Tribology and Interface Chemistry Group, 1015 Lausanne (Switzerland)

    2011-05-11

    The main aim of this work was to study and understand the influence of SiC particles on the corrosion and tribocorrosion of Al-matrix composite materials. For that, Al-SiC{sub p} functionally graded composites were produced by centrifugal casting and different SiC{sub p} contents were achieved. Their mechanical properties were improved by age-hardening heat treatments. The tribocorrosion behaviour was studied in 0.05M NaCl solutions using a reciprocating motion tribometer involving an alumina ball sliding against the Al-based samples. Above critical SiC particles' content the matrix alloy surface was found to be protected against wear by SiC particles protruding from the surface. Below this threshold content, the SiC reinforcement was inefficient and the wear rate of the composite was the same as the non-reinforced alloy.

  19. Influence of SiC reinforcement particles on the tribocorrosion behaviour of Al-SiCp FGMs in 0.05M NaCl solution

    Science.gov (United States)

    Vieira, A. C.; Rocha, L. A.; Mischler, S.

    2011-05-01

    The main aim of this work was to study and understand the influence of SiC particles on the corrosion and tribocorrosion of Al-matrix composite materials. For that, Al-SiCp functionally graded composites were produced by centrifugal casting and different SiCp contents were achieved. Their mechanical properties were improved by age-hardening heat treatments. The tribocorrosion behaviour was studied in 0.05M NaCl solutions using a reciprocating motion tribometer involving an alumina ball sliding against the Al-based samples. Above critical SiC particles' content the matrix alloy surface was found to be protected against wear by SiC particles protruding from the surface. Below this threshold content, the SiC reinforcement was inefficient and the wear rate of the composite was the same as the non-reinforced alloy.

  20. Effect of Al2O3 Ceramic Particles on Corrosion Behaviour and Tribological Properties of Nickel Composite Coatings

    Directory of Open Access Journals (Sweden)

    Nowak M.

    2016-03-01

    Full Text Available The paper presents a study on corrosion behaviour and tribological properties of nickel composite coatings deposited by electrochemical method on aluminium alloy from 2xxx series (AlCu4MgSi. The nickel composite coatings were produced in a Watts bath of the following chemical composition: NiSO4·7H2O 150 g/l, NiCl2·6H2O 30 g/l, H3BO3 30 g/l with the addition of saccharin in an amount of 2 g/l. As hard ceramic dispersed particles embedded in the coating, alumina (Al2O3 was used in an amount of 12,5; 25; 50 and 75 g/l. Coatings were produced using cathodic current density of 6 A/dm2, bath temperature of 60°C, pH 4, and the time 60 minutes. The electroplating bath was stirred with a mechanical stirrer (350 rpm.

  1. Investigation on silver electric adhesive doped with Al{sub 2}O{sub 3} ceramic particles for sealing planar solid oxide fuel cell

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Xiaoliang [Science Research Center, Academy of Fundamental and Interdisciplinary Sciences, Harbin Institute of Technology, Harbin 150080 (China); School of Municipal and Environmental Engineering, Harbin Institute of Technology, Harbin 150090 (China); Department of Applied Chemistry, Harbin Institute of Technology, No. 92 of West Dazhi Street, P.O. Box 211, Harbin 150001 (China); Sun, Kening; Le, Shiru; Zhang, Naiqing [Science Research Center, Academy of Fundamental and Interdisciplinary Sciences, Harbin Institute of Technology, Harbin 150080 (China); Department of Applied Chemistry, Harbin Institute of Technology, No. 92 of West Dazhi Street, P.O. Box 211, Harbin 150001 (China); Yan, Yan; Sun, Wang [Department of Applied Chemistry, Harbin Institute of Technology, No. 92 of West Dazhi Street, P.O. Box 211, Harbin 150001 (China); Wang, Peng [School of Municipal and Environmental Engineering, Harbin Institute of Technology, Harbin 150090 (China)

    2009-07-15

    The silver electric adhesive doped with Al{sub 2}O{sub 3} ceramic particles is used as sealing material for planar solid oxide fuel cell (SOFC). The sealing temperature of this sealing material is 600 C with the heating rate of 2 C min{sup -1}, and the minimal leak rate ranges from 0.030 sccm cm{sup -1} to 0.040 sccm cm{sup -1}. When doping 15 mass% Al{sub 2}O{sub 3} ceramic particles into this sealing material, the thermal expansion coefficient of this material decreases from 20 ppm K{sup -1} to 15 ppm K{sup -1}, which improves the thermal matching performance and the long-term stability of the material significantly. When using the gradient sealing method with the pure silver electric adhesive and the silver electric adhesive doped with Al{sub 2}O{sub 3} ceramic particles to seal the interface of Ni-YSZ/SUS430 in the simulating cell, the minimal leak rate of 0.035 sccm cm{sup -1} is obtained for the cell. Furthermore, the simulating cell sealed with the compound silver electric adhesive presents good heat-resistant impact ability. Therefore, this compound sealing technique is a very promising sealing method for SOFC. (author)

  2. Friction and wear behavior of TiC particle reinforced ZA43 matrix composites

    Institute of Scientific and Technical Information of China (English)

    谢贤清; 张荻; 刘金水; 吴人洁

    2001-01-01

    TiC/ZA43 composites were fabricated by XDTM and stirring-casting techniques. The tribology properties of the unreinforced ZA43 alloy and the composites were studied by using a block-on-ring apparatus. Experimental results show that the incorporation of TiC particles improves the microstructure of ZA43 matrix alloy. The coefficient of friction μ and the width of worn groove decrease with the increase of TiC volume fraction φ(TiC). The width of worn groove and μ of the composite during wear testing increase with increasing the applied load. Metallographic examinations reveal that unreinforced ZA43 alloy has deep ploughing grooves with obvious adhesion phenomenon, whereas TiC/ZA43 composites have smooth worn surface. Delamination formation is related to the fatigue cracks and the shear cracks on the surface.

  3. Microstructure and performance of reactive plasma clad high chromium iron based ceramic reinforcing wear-resistance coating%反应等离子熔覆高铬铁基金属陶瓷增强耐磨涂层组织与性能

    Institute of Scientific and Technical Information of China (English)

    王立梅

    2011-01-01

    利用反应等离子熔覆技术、以Fe-Cr-C-W-Ni合金粉末为原料,在Q235钢表面制得了Cr7C3高铬铁基金属陶瓷增强耐磨复合涂层.利用SEM、EDS和X射线衍射分析了涂层的显微组织,在室温干滑动磨损试验条件下测试了涂层的耐磨性.结果表明:反应等离子熔覆CE7C3高铬铁基金属陶瓷增强耐磨复合涂层硬度高、组织均匀、与基材之间为完全冶金结合;涂层在室温干滑动磨损试验条件下表现出优异的耐磨性,涂层磨损的质量损失随载荷增加十分缓慢,涂层具有优异的载荷特性.%A wear resistant high chromium iron based ceramic reinforcing wear-resistance coating was fabricated on substrate of a Q235 steel by plasma cladding using the Fe-Cr-C-W-Ni alloy powders. Microstructure of the coating was characterized by OM, SEM, EDS and XRD. Wear resistance of the coating was tested under dry sliding wear condition at room temperature. Results indicate that the plasma clad high chromium iron based ceramic reinforced wear-resistance composite coating has a rapidly solidified homogeneous microstructure consisting of Cr7C3 ceramal primary particles uniformly distributed in the Cr7C3/γ-Fe eutectic matrix and is metallurgically bonded to the Q235 steel substrate. The plasma clad composite coating has high hardness and excellent wear resistance under dry sliding wear test conditions. Wear mass loss of the coating is increased slowly with the load increased and it has excellent load characteristic.

  4. A statistical analysis on erosion wear behaviour of A356 alloy reinforced with in situ formed TiB2 particles

    International Nuclear Information System (INIS)

    Solid particle erosion wear behaviour of A356 and A356/TiB2in situ composites has been studied. A356 alloy reinforced with in situ TiB2 particles was fabricated by the reaction of halide salts with aluminium melt and the formation of Al3Ti brittle phase is completely suppressed. The composites show good grain refinement of α-Al and modification of eutectic Si. These in situ composites show high hardness and better erosion resistance than the base alloy. Though the sizes of in situ formed TiB2 reinforcement particles are smaller than the erodent SiC particles, TiB2 particles are able to effectively resist the erodent particles. Design of experiment has been used to run the solid particle erosion experiment. An attempt has also been made to develop a mathematical model by using regression analysis. Analysis of variance (ANOVA) technique is applied to check the validity of the developed model. Student's t-test is utilized to find out the significance of factors. The wear mechanism has been studied by analyzing the surface of the worn specimen using scanning electron microscopy and energy dispersive X-ray microanalysis

  5. Welding of SiC particle reinforced 6061 Al matrix composite with pulsed TIG

    Institute of Scientific and Technical Information of China (English)

    陈茂爱; 武传松; 高进强

    2002-01-01

    SiCp/6061Al alloy composite was welded by using TIG and pulsed-TIG welding (P-TIG) without addition of filler metal, or with addition of Al-Si or Al-Mg filler metal. The microstructure and properties of the weld were investigated with XRD, OM, TEM, and MTS-810 testing system was used to observe the effect of different welding procedure and filler metals on the microstructure and properties of the weld. Thermodynamic of SiC-Al reaction was used to analyze the tendency of the reaction between SiC particle and Al matrix during welding. The results showed that the P-TIG tends to produce less plate-like Al4C3 precipitates than TIG; when welding with P-TIG, addition of Al-Si filler metal can not only prevent from formation of Al4C3, but also decrease hot crack sensitivity of weld; the tensile strength of joint of adding Al-Si filler metal is higher than that of adding Al-Mg filler metal. The SiCp/6061Al composite can be successfully welded by P-TIG with addition of Al-Si filler metal.

  6. Investigation on the Effects of Titanium Diboride Particle Size on Radiation Shielding Properties of Titanium Diboride Reinforced Boron Carbide-Silicon Carbide Composites

    Directory of Open Access Journals (Sweden)

    A.O. Addemir

    2012-03-01

    Full Text Available Composite materials have wide application areas in industry. Boron Carbide is an important material for nuclear technology. Silicon carbide is a candidate material in the first wall and blankets of fusion power plants. Titanium diboride reinforced boron carbide-silicon carbide composites which were produced from different titanium diboride particle sizes and ratios were studied for searching of the behaviour against the gamma ray. Cs-137 gamma radioisotope was used as gamma source in the experiments which has a single gamma-peak at 0.662 MeV. Gamma transmission technique was used for the measurements. The effects of titanium diboride particle size on radiation attenuation of titanium diboride reinforced boron carbide-silicon carbide composites were evaluated in related with gamma transmission and the results of the experiments were interpreted and compared with each other. Composite materials have wide application areas in industry. Boron Carbide is an important material for nuclear technology. Silicon carbide is a candidate material in the first wall and blankets of fusion power plants. Titanium diboride reinforced boron carbide-silicon carbide composites which were produced from different titanium diboride particle sizes and ratios were studied for searching of the behaviour against the gamma ray. Cs-137 gamma radioisotope was used as gamma source in the experiments which has a single gamma-peak at 0.662 MeV. Gamma transmission technique was used for the measurements. The effects of titanium diboride particle size on radiation attenuation of titanium diboride reinforced boron carbide-silicon carbide composites were evaluated in related with gamma transmission and the results of the experiments were interpreted and compared with each other. Composite materials have wide application areas in industry. Boron Carbide is an important material for nuclear technology. Silicon carbide is a candidate material in the first wall and blankets of fusion

  7. Preparation and characterization of squeeze cast-Al–Si piston alloy reinforced by Ni and nano-Al2O3 particles

    Directory of Open Access Journals (Sweden)

    Hashem F. El-Labban

    2016-07-01

    Full Text Available Al–Si base composites reinforced with different mixtures of Ni and nano-Al2O3 particles have been fabricated by squeeze casting and their metallurgical and mechanical characterization has been investigated. A mixture of Ni and nano-Al2O3 particles of different ratios was added to the melted Al–Si piston alloy at 700 °C and stirred under pressure. After the Al-base-nano-composites were fabricated by squeeze casting, the microstructure and the particle distribution inside the matrix have been investigated using optical and scanning electron microscopes. Moreover, the hardness and the tensile properties of the resulted Al-base-nano-composites were evaluated at room temperature by using Vickers hardness and universal tensile testers, respectively. As a result, in most cases, it was found that the matrix showed a fine eutectic structure of short silicon constituent which appeared in the form of islands in the α-phase around some added particle agglomerations of the nano-composite structures. The tendency of this structure formation increases with the increase of Ni particle addition. As the ratio of the added particles increases, the tendency of these particles to be agglomerated also increases. Regarding the tensile properties of the fabricated Al-base-nano-composites, ultimate tensile strength is increased by adding the Ni and nano-Al2O3 particles up to 10 and 2 wt.%, respectively. Moreover, the ductility of the fabricated composites is significantly improved by increasing the added Ni particles. The composite material reinforced with 5 wt.% Ni and 2 wt.% nano-Al2O3 particles showed superior ultimate tensile strength and good ductility compared with any other added particles in this investigation.

  8. Hard magnetic composite materials with polymer matrix reinforced Nd-Fe-B hard magnetic particles

    International Nuclear Information System (INIS)

    Investigation results of the polymer matrix hard magnetic composite materials with particles of the powered rapid quenched Nd-Fe-B strip quenched Nd-Fe-B strip are presented at this paper. The Nd-Fe-B powder was doped (10 wt.%) with powder of iron, aluminium, CuSn10 casting copper alloy with tin, high alloy steel X2CrNiNo17-12-2 and aluminium oxide. Epoxy resin has been used as a matrix (2.5 wt.%). The pressure of 800-900 MPa and cured afterwards for 2 hours at 180 oC. The influence of dopes' materials kind on magnetic and mechanical composites were unilaterally and uniaxially pressed at room temperature under properties of composite materials was estimated. Metallographic examination of the composite materials' structure and XRD analysis has been made. Investigations of magnetic properties of composite materials show the influence of the addition material. It was estimated that dopes of soft magnetic material decrease coercive force HcB and slightly reduce remanence Br of composite. The addition of non-magnetic material decreases coercive force HcB and reduces remanence Br. Metallographic examination of the structure shows uniform distribution of Nd-Fe-B powder in the polymer matrix, grains are irregular elongated in the direction. Dopes distribution in a polymer matrix is irregular, agglomerations of powders of aluminium, iron and copper casting alloy with tin have noticed. Ultimate compressive strength of composite materials is improved for all the addition material, except powder of aluminium oxide. XRD analysis has identified the hard magnetic phase Nd2Fe14B. (author)

  9. Effect of Milling Time and the Consolidation Process on the Properties of Al Matrix Composites Reinforced with Fe-Based Glassy Particles

    Directory of Open Access Journals (Sweden)

    Özge Balcı

    2015-04-01

    Full Text Available Al matrix composites reinforced with 40 vol% Fe50.1Co35.1Nb7.7B4.3Si2.8 glassy particles have been produced by powder metallurgy, and their microstructure and mechanical properties have been investigated in detail. Different processing routes (hot pressing and hot extrusion are used in order to consolidate the composite powders. The homogeneous distribution of the glassy reinforcement in the Al matrix and the decrease of the particle size are obtained through ball milling. This has a positive effect on the hardness and strength of the composites. Mechanical tests show that the hardness of the hot pressed samples increases from 51–155 HV, and the strength rises from 220–630 MPa by extending the milling time from 1–50 h. The use of hot extrusion after hot pressing reduces both the strength and hardness of the composites: however, it enhances the plastic deformation significantly.

  10. Early stages of sliding wear behaviour of Al2O3 and SiC reinforced aluminium

    International Nuclear Information System (INIS)

    Al matrix composites reinforced by 10 vol.% Al2O3 and SiC particles were subjected to dry sliding tests against steel using a slider-on-cylinder tribometer. Damage mechanisms were 'micro-machining' of the steel carried out by ceramic particles, plastic deformation and oxidation of the metal matrix, as well as abrasion. The results were discussed on the basis of the third-body wear model. (orig.)

  11. Research on Heat Treatment Schedule of Leucite-reinforced Dental Glass Ceramics%白榴石增强的牙科玻璃陶瓷的热处理制度研究

    Institute of Scientific and Technical Information of China (English)

    李莺; 姜通; 郭瑞松

    2012-01-01

    本文研究了白榴石增强的牙科玻璃陶瓷的热处理制度对白榴石晶体的生成、玻璃陶瓷的耐腐蚀性和力学性能的影响,采用热分析、X射线衍射分析、力学性能表征及金相显微观察等方法对热处理后的牙科玻璃陶瓷进行测试和分析.热分析表明,玻璃陶瓷晶核的生成温度为760℃,晶核的成长温度为1010℃.试验采用阶梯式升温热处理制度,成功地在玻璃陶瓷中析出白榴石晶体,随着白榴石含量的增加,材料的力学性能也获得了提高,热处理后材料的三点弯曲强度为102.2 MPa,显微硬度为5.45 GPa,断裂韧性为2.41 MPa·m1/2,强度达到ISO6872牙科陶瓷材料的标准.%The effects of heat treatment schedule of leucite-reinforced dental glass ceramics on the formation of leucite crystals, corrosion resistance and mechanical properties were studied. The dental glass ceramics after heat treatment were analyzed by thermal analysis, X ray diffraction analysis, mechanical property characterization and metallographic examination. Thermal analysis showed that the temperature of nucleation and crystallization was about 760 ℃ and 1010 ℃ , respectively. Leucite crystals were successfully obtained from the glass by heat treatment with stepped heating system. The existence of leucite crystals improved the mechanical properties of the dental glass ceramics. The three-point bending strength was 102.2 MPa, microhardness reached 5.45 GPa and fracture toughness was 2. 41 MPa ·m1/2. The strength of leucited-reinforced dental glass ceramics met the ISO 6872 standard.

  12. Growth mechanism, distribution characteristics and reinforcing behavior of (Ti, Nb)C particle in laser cladded Fe-based composite coating

    International Nuclear Information System (INIS)

    Highlights: • Reinforced (Ti, Nb)Cp can be synthesized in the molten pool during laser cladding. • Formation mechanism of (Ti, Nb)Cp are impacted by Ti/Nb atomic ratio. • Appropriate Ti element can improve the precipitation of carbide particle. • Excess Ti weakens this effect above-mentioned. • The wear resistance of the coating was improved when Ti/Nb = 1. - Abstract: Over the past decade, researchers have demonstrated much interest in laser cladded metal matrix composite coatings for its good wear resistance, corrosion resistance, and high temperature properties. In this paper, in-situ (Ti, Nb)C particle reinforced Fe-based composite coatings were produced by laser cladding. The effects of Ti/Nb(atomic ratio) in the cladding powder on the formation mechanism and distribution characteristics of multiple particle were investigated. The results showed that when Ti/Nb > 1, Ti had a stronger ability to bond with C compared with Nb. (Ti, Nb)C multiple particles with TiC core formed in the molten pool. With the decrease of Ti/Nb, core-shell structure disappeared, the structure of particle got close to that of NbC gradually. It is found that the amount, area ratio and distribution of the reinforced particle in the coating containing Ti and Nb elements were improved, compared with these in the coating containing equal Nb element. When Ti/Nb = 1, the effects above-mentioned is most prominent, and the wear resistance of the coating is promoted obviously

  13. Growth mechanism, distribution characteristics and reinforcing behavior of (Ti, Nb)C particle in laser cladded Fe-based composite coating

    Energy Technology Data Exchange (ETDEWEB)

    Li, Qingtang, E-mail: liqingtang123@126.com; Lei, Yongping, E-mail: yplei@bjut.edu.cn; Fu, Hanguang

    2014-10-15

    Highlights: • Reinforced (Ti, Nb)Cp can be synthesized in the molten pool during laser cladding. • Formation mechanism of (Ti, Nb)Cp are impacted by Ti/Nb atomic ratio. • Appropriate Ti element can improve the precipitation of carbide particle. • Excess Ti weakens this effect above-mentioned. • The wear resistance of the coating was improved when Ti/Nb = 1. - Abstract: Over the past decade, researchers have demonstrated much interest in laser cladded metal matrix composite coatings for its good wear resistance, corrosion resistance, and high temperature properties. In this paper, in-situ (Ti, Nb)C particle reinforced Fe-based composite coatings were produced by laser cladding. The effects of Ti/Nb(atomic ratio) in the cladding powder on the formation mechanism and distribution characteristics of multiple particle were investigated. The results showed that when Ti/Nb > 1, Ti had a stronger ability to bond with C compared with Nb. (Ti, Nb)C multiple particles with TiC core formed in the molten pool. With the decrease of Ti/Nb, core-shell structure disappeared, the structure of particle got close to that of NbC gradually. It is found that the amount, area ratio and distribution of the reinforced particle in the coating containing Ti and Nb elements were improved, compared with these in the coating containing equal Nb element. When Ti/Nb = 1, the effects above-mentioned is most prominent, and the wear resistance of the coating is promoted obviously.

  14. In-situ Fabricated TiB2 Particle-whisker Synergistically Toughened Ti(C, N)-based Ceramic Cutting Tool Material

    Institute of Scientific and Technical Information of China (English)

    LIU Hanlian; SHI Qiang; HUANG Chuanzhen; ZOU Bin; XU Liang; WANG Jun

    2015-01-01

    The mechanical properties of ceramic cutting tool materials can be modified by introducing proper content of nanoparticles or whiskers. However, the process of adding whiskers or nanoparticles has the disadvantages of high cost and health hazard as well as the agglomeration;although a new in-situ two-step sintering process can solve the above problems to some extent, yet the problems of low conversion ratio of the raw materials and the abnormal grain growth exist in this process. In this paper, an in-situ one-step synthesis technology is proposed, which means the growth of whiskers or nanoparticles and the sintering of the compact can be accomplished by one time in furnace. A kind of Ti(C, N)-based ceramic cutting tool material synergistically toughened by TiB2 particles and whiskers is fabricated with this new process. The phase compositions, relationships between microstructure and mechanical properties as well as the toughening mechanisms are analyzed by means of X-ray diffraction (XRD) and scanning electron microscopy (SEM). The composite which is sintered under a pressure of 32 MPa at a temperature of 1700℃ in vacuum holding for 60 min can get the optimal mechanical properties. Its flexural strength, fracture toughness and Vickers hardness are 540 MPa, 7.81 MPa•m1/2 and 20.42 GPa, respectively. The composite has relatively high density, and the in-situ synthesized TiB2 whiskers have good surface integrity, which is beneficial for the improvement of the fracture toughness. It is concluded that the main toughening mechanisms of the present composite are whiskers pulling-out and crack deflection induced by whiskers, crack bridging by whiskers/particles and multi-scale particles synergistically toughening. This study proposes an in-situ one-step synthesis technology which can be well used for fabricating particles and whiskers synergistically toughened ceramic tool materials.

  15. Tribological properties of laser cladding TiB2 particles reinforced Ni-base alloy composite coatings on aluminum alloy

    Institute of Scientific and Technical Information of China (English)

    Long He; Ye-Fa Tan; Xiao-Long Wang; Qi-Feng Jing; Xiang Hong

    2015-01-01

    To improve the wear resistance of aluminum alloy frictional parts,TiB2 particles reinforced Ni-base alloy composite coatings were prepared on aluminum alloy 7005 by laser cladding.The microstructure and tribological properties of the composite coatings were investigated.The results show that the composite coating contains the phases of NiAl,Ni3Al,Al3Ni2,TiB2,TiB,TiC,CrB,and Cr23C6.Its microhardness is HV0.5 855.8,which is 15.4 % higher than that of the Ni-base alloy coating and is 6.7 times as high as that of the aluminum alloy.The friction coefficients of the composite coatings are reduced by 6.8 %-21.6 % and 13.2 %-32.4 % compared with those of the Ni-base alloy coatings and the aluminum alloys,while the wear losses are 27.4 %-43.2 % less than those of the Ni-base alloy coatings and are only 16.5 %-32.7 % of those of the aluminum alloys at different loads.At the light loads ranging from 3 to 6 N,the calculated maximum contact stress is smaller than the elastic limit contact stress.The wear mechanism of the composite coatings is micro-cutting wear,but changes into multi-plastic deformation wear at 9 N due to the higher calculated maximum contact stress than the elastic limit contact stress.As the loads increase to 12 N,the calculated flash temperature rises to 332.1 ℃.The composite coating experiences multi-plastic deformation wear,micro-brittle fracture wear,and oxidative wear.

  16. Mechanical properties of in-situ prepared SiC whisker- and nano particle-reinforced Si{sub 3}N{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Yamada, S.; Nagasaka, M.; Natsume, T. [Teikyo Univ. of Sci. and Technol., Yamanashi (Japan); Niihara, K. [Osaka Univ., Ibaraki (Japan). Inst. of Scientific and Industrial Research; Nakahira, A. [Kyoto Inst. of Tech. (Japan)

    1999-03-01

    In-situ preparation of SiC whisker- and nano particle-reinforced Si{sub 3}N{sub 4} was carried out. Bending strength showed higher values by adding the nano particles `after` the in-situ whiskerizing reaction than `before,` although the improvement was not so remarkable. With regard to fracture toughness, a slightly higher value was observed in the case of adding the particles `before` than `after` the in-situ reaction, where the form of whiskers looked constricted due to the co-existence of particles. Relative density was not so high enough, around 94% to the theoretical value, that HIP apparatus was employed for its densification. A relationship between density and preliminary hot-pressing condition was obtained; however, the effect was not so high enough, up to only 95.5%. (orig.) 3 refs.

  17. BEHAVIOR STUDY OF ORDER NANO-PARTICLES IN POROUS CERAMICS%纳米颗粒在有序多孔陶瓷中的行为研究

    Institute of Scientific and Technical Information of China (English)

    伍协; 陈振华; 冯延林; 刘小磐

    2011-01-01

    本文详细研究了纳米颗粒在有序多孔陶瓷中形成协同体的过程.实验结果表明:纳米TiO2和炭黑(CB)能比较容易进入到有序多孔陶瓷中形成具有特定功能的协同体.当纳米TiO2的浓度增加到5wt%和炭黑浓度增加到15 wt%时,有序多孔陶瓷的孔壁上粘附纳米TiO2和炭黑颗粒的量最大从而形成大量的活性点.浓度对两种纳米颗粒的渗透力具有很大的影响,炭黑粒子的渗透能力比纳米纳米TiO2颗粒强.%This study is focused on the fabrication of nano-particles and order porous ceramics association. The experimental results show that the nano-TiO2 and carbon black(CB) enter the pores of order porous ceramics smoothly and forming commonwealth which maybe come out many magical functions; when the concentration of nano-TiO2 added up to 5 wt % and carbon black added up to 15 wt %, many nano-TiO2 or CB adhere to the order porous ceramics pores and walls coming into being functional dots; different concentration of the two nano-particles affect on the process and carbon black particles have better ability than nano-TiO2.

  18. Effect of graphite particle size on wear property of graphite and Al2O3 reinforced AZ91D-0.8%Ce composites

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The graphite particles and Al2O3 short fibers reinforced AZ91D-0.8%Ce composites were fabricated by squeeze-infiltration technique.The researches about the effects of different graphite particle sizes on the microstructure and wear property of the composites were performed under the condition of constant contents of graphite particles and Al2O3 short fibers.The results reveal that the grain size of the composites changes less when the graphite particle size descends.Moreover,Ce enriches around the graphite particle and Al2O3 short fibers and forms Al3Ce phase with A1 element.The graphite that works as lubricant decreases the wear loss.The wear resistance of the composites increases as the graphite particle size increases.At low load the composites have similar wear loss;at high load the composite with the largest graphite particle size has the best wear resistance.The wear mechanism of all the composites at low load is abrasive wear and oxidation wear;at high load,except the composites with the particle size of 240 μm whose wear mechanism is still abrasive wear and oxicIation wear,the wear mechanism of othcrs changes to delamination wear.

  19. Improve Wear Resistance on Al 332 Alloy Matrix- Micro -Nano Al2O3 Particles Reinforced Composite

    Directory of Open Access Journals (Sweden)

    Rawnaq Ahmed Mohamed

    2014-03-01

    Full Text Available The wear behavior of alumina particulate reinforced A332 aluminium alloy composites produced by a stir casting process technique were investigated. A pin-on-disc type apparatus was employed for determining the sliding wear rate in composite samples at different grain size (1 µm, 12µm, 50 nm and different weight percentage (0.05-0.1-0.5-1 wt% of alumina respectively. Mechanical properties characterization which strongly depends on microstructure properties of reinforcement revealed that the presence of ( nano , micro alumina particulates lead to simultaneous increase in hardness, ultimate tensile stress (UTS, wear resistances. The results revealed that UTS, Hardness, Wear resistances increases with the increase in the percentage of reinforcement of Al2O3 when compared to the base alloy A332. The wear rates of the composites were considerably less than that of the aluminum alloy at all applied loads with increasing percentage of reinforcement when compared to the base alloy A332.

  20. Portfolio: Ceramics.

    Science.gov (United States)

    Hardy, Jane; And Others

    1982-01-01

    Describes eight art activities using ceramics. Elementary students created ceramic tiles to depict ancient Egyptian and medieval European art, made ceramic cookie stamps, traced bisque plates on sketch paper, constructed clay room-tableaus, and designed clay relief masks. Secondary students pit-fired ceramic pots and designed ceramic Victorian…

  1. 氧化锆纤维增强的氧化铝陶瓷的抗热震性能%Thermal Shock Resistance of Zirconia Fiber Reinforced Alumina Ceramics

    Institute of Scientific and Technical Information of China (English)

    冯帅; 王志; 丁寅森; 史国普

    2013-01-01

    Preparation of zirconia fiber reinforced alumina ceramic composite at sintering temperature of 1 650℃ and effect of zir-conia fiber content on thermal shock resistance of composite were studied. Results showed that the introduction of zirconia fiber can increase the air-cooling time of ceramic composite at the temperature difference of 1 400 ℃. When mass fraction of zirconia fiber was 15% ,the thermal shock time of the composite was 30,more than 10 times of monolithic alumina ceramics. The flexural strength and fracture toughness of the composite increased by 62.2% and 38.9% respectively than that of monolithic alumina ceramics,and its porosity was 6.71%. Increasing of mechanical properties and proper porosity contributed to the improvement of thermal shock resistance.%在1 650℃下制备氧化锆纤维增强的氧化铝陶瓷复合材料,研究氧化锆纤维添加量对氧化铝陶瓷抗热震性能的影响.结果表明,在温差为1 400℃的循环空冷条件下,加入氧化锆纤维可以明显提高氧化铝陶瓷的热震次数.当添加纤维质量分数为15%时,复合材料热震次数达到最高为30次,比纯氧化铝陶瓷提高20次;复合材料的抗弯强度和断裂韧性分别比纯氧化铝陶瓷提高62.2%和38.9%,气孔率为6.71%.复合材料力学性能的提高以及适当的气孔率是其抗热震性提高的主要原因.

  2. Fabrication of mullite-bonded porous SiC ceramics from multilayer-coated SiC particles through sol-gel and in-situ polymerization techniques

    Science.gov (United States)

    Ebrahimpour, Omid

    In this work, mullite-bonded porous silicon carbide (SiC) ceramics were prepared via a reaction bonding technique with the assistance of a sol-gel technique or in-situ polymerization as well as a combination of these techniques. In a typical procedure, SiC particles were first coated by alumina using calcined powder and alumina sol via a sol-gel technique followed by drying and passing through a screen. Subsequently, they were coated with the desired amount of polyethylene via an in-situ polymerization technique in a slurry phase reactor using a Ziegler-Natta catalyst. Afterward, the coated powders were dried again and passed through a screen before being pressed into a rectangular mold to make a green body. During the heating process, the polyethylene was burnt out to form pores at a temperature of about 500°C. Increasing the temperature above 800°C led to the partial oxidation of SiC particles to silica. At higher temperatures (above 1400°C) derived silica reacted with alumina to form mullite, which bonds SiC particles together. The porous SiC specimens were characterized with various techniques. The first part of the project was devoted to investigating the oxidation of SiC particles using a Thermogravimetric analysis (TGA) apparatus. The effects of particle size (micro and nano) and oxidation temperature (910°C--1010°C) as well as the initial mass of SiC particles in TGA on the oxidation behaviour of SiC powders were evaluated. To illustrate the oxidation rate of SiC in the packed bed state, a new kinetic model, which takes into account all of the diffusion steps (bulk, inter and intra particle diffusion) and surface oxidation rate, was proposed. Furthermore, the oxidation of SiC particles was analyzed by the X-ray Diffraction (XRD) technique. The effect of different alumina sources (calcined Al2O 3, alumina sol or a combination of the two) on the mechanical, physical, and crystalline structure of mullite-bonded porous SiC ceramics was studied in the

  3. Electrical Resistivity, Tribological Behaviour of Multiwalled Carbon Nanotubes and Nanoboron Carbide Particles Reinforced Copper Hybrid Composites for Pantograph Application

    Directory of Open Access Journals (Sweden)

    N. Selvakumar

    2016-01-01

    Full Text Available This work focuses on the influence and contribution of multiwalled carbon-nanotube (MWCNT–boron carbide (B4C to the mechanical and tribological properties of copper matrix composites. Different weight fractions of nano- B4C-containing fixed-weight fractions of MWCNT-reinforced copper composites were prepared using the entrenched cold-press sintering method of powder metallurgy. The wear losses of sintered Cu–MWCNT–B4C composites were investigated by conducting sliding tests in a pin-on-disc apparatus. The addition of reinforcements showed enhancements in the hardness and wear properties of the composites due to the uniform dispersion of the secondary reinforcement in the copper matrix and the self-lubricating effect of the MWCNTs. The effects of the nanoparticle distribution in the matrix, the worn surface morphology, and the elemental composition of the composites were characterized using high-resolution scanning electron microscopy and X-ray diffraction analysis. The electrical resistivity of the fabricated copper hybrid composite preforms was evaluated using a four-point probe tester. Our results highlight the use of experiential reinforcing limits of B4C on the wear and electrical and mechanical behaviour of copper composites.

  4. Production and Characterization of Brass-matrix Composites Reinforced with Ni59Zr20Ti16Si2Sn3 Glassy Particles

    Directory of Open Access Journals (Sweden)

    Bum Sung Kim

    2012-05-01

    Full Text Available Brass-matrix composites reinforced with 40 and 60 vol.% of Ni59Zr20Ti16Si2Sn3 glassy particles were produced by powder metallurgy. The crystallization behavior and the temperature dependence of the viscosity of the glass reinforcement were studied in detail to select the proper sintering parameters in order to avoid crystallization of the glassy phase during consolidation. The brass-glass powder mixtures were prepared through manual blending as well as by ball milling to analyze the effect of the matrix ligament size on the mechanical properties of the composites. The powder mixtures were then consolidated into highly-dense bulk specimens at temperatures within the supercooled liquid region by hot pressing followed by hot extrusion. The preparation of the powder mixtures has a strong influence on the mechanical behavior of the composites. The strength increases from 500 MPa for pure brass to 740 and 925 MPa for the blended composites with 40 and 60vol.% of glass reinforcement, while the strength increases to 1,240 and 1,640 MPa for the corresponding composites produced by ball milling. Modeling of the mechanical properties indicates that this behavior is related to the reduced matrix ligament size characterizing the milled composites.

  5. The influence of nominal stress on wear factors of carbon fibre-reinforced polyetheretherketone (PEEK-OPTIMA® Wear Performance) against zirconia toughened alumina (Biolox® delta ceramic).

    Science.gov (United States)

    Evans, Andrew; Horton, Henrietta; Unsworth, Anthony; Briscoe, Adam

    2014-06-01

    Carbon fibre-reinforced polyetheretherketone is an attractive alternative to ultra-high-molecular-weight polyethylene in artificial joints, but little has been published on the influence of stress on the wear factor. We know that in ultra-high-molecular-weight polyethylene, the wear factor reduces as the normal stress increases, which is counter-intuitive but very helpful in the case of non-conforming contacts. In this study, carbon fibre-reinforced polyetheretherketone (PEEK-OPTIMA(®) Wear Performance) has been investigated in a pin-on-plate machine under steady loads and under stresses typical of hip and knee joints. At stresses below about 6 MPa, wear factors are between 10 and a 100 times lower than for ultra-high-molecular-weight polyethylene but at higher stresses the wear factors increase substantially.

  6. Fabrication and mechanical properties of AlCoNiCrFe high-entropy alloy particle reinforced Cu matrix composites

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Jian, E-mail: chenjian@xatu.edu.cn [School of Materials Science and Chemical Engineering, Xi' an Technological University, Xi' an, Shaanxi 710021 (China); Niu, Pengyun; Wei, Ting [School of Materials Science and Chemical Engineering, Xi' an Technological University, Xi' an, Shaanxi 710021 (China); Hao, Liang [College of Architecture and Civil Engineering, Xi' an University of Science and Technology, Xi' an 710054 (China); Liu, Yunzi [School of Materials Science and Chemical Engineering, Xi' an Technological University, Xi' an, Shaanxi 710021 (China); Wang, Xianhui, E-mail: xhwang693@xaut.edu.cn [School of Materials Science and Engineering, Xi' an University of Technology, Xi' an, Shaanxi 710048 (China); Peng, Yuli [School of Materials Science and Chemical Engineering, Xi' an Technological University, Xi' an, Shaanxi 710021 (China)

    2015-11-15

    The AlCoNiCrFe high-entropy alloy was prepared by mechanical alloying and the AlCoNiCrFe high-entropy alloy reinforced Cu matrix composites were subsequently fabricated by powder metallurgy. The phase constituents and morphology of the alloying powders were characterized by X-ray diffractometer and scanning electron microscope, the microstructures of the Cu base composites were characterized by scanning electron microscope and transmission electron microscope, and the compression tests were made as well. The results show that the AlCoNiCrFe high-entropy alloy can form after milling for 24 h. During sintering process, no grain growth occurs and no intermetallic phases present in the AlCoNiCrFe high-entropy alloy in the Cu base composite. Compression tests show that the AlCoNiCrFe high-entropy alloy has a better strengthening effect than metallic glasses and the yield strength of the Cu matrix composite reinforced with the AlCoNiCrFe high-entropy alloy is close to the value predicted by the Voigt model based on the equal strain assumption. - Graphical abstract: AlCoNiCrFe HEA has a better strengthening effect than metallic glasses for particulate reinforced metal matrix composites. The yield strength of the Cu base composite reinforced with the AlCoNiCrFe HEA is close to the upper bound calculated by Voigt model. - Highlights: • AlCoNiCrFe high-entropy alloy was prepared by mechanical alloying. • A novel Cu base composite reinforced with AlCoNiCrFe was fabricated. • No grain growth and no intermetallic phase present in AlCoNiCrFe during sintering. • AlCoNiCrFe has a better strengthening effect than metallic glassy in composites.

  7. Actively Cooled Ceramic Composite Nozzle Material Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The Phase I Project demonstrated the capability of the Pyrowave? manufacturing process to produce fiber-reinforced ceramics (FRCs) with integral metal features,...

  8. Synthesis and Characterization of Multi Wall Carbon Nanotubes (MWCNT) Reinforced Sintered Magnesium Matrix Composites

    Science.gov (United States)

    Vijaya Bhaskar, S.; Rajmohan, T.; Palanikumar, K.; Bharath Ganesh Kumar, B.

    2016-04-01

    Metal matrix composites (MMCs) reinforced with ceramic nano particles (less than 100 nm), termed as metal matrix nano composites (MMNCs), can overcome those disadvantages associated with the conventional MMCs. MMCs containing carbon nanotubes are being developed and projected for diverse applications in various fields of engineering like automotive, avionic, electronic and bio-medical sectors. The present investigation deals with the synthesis and characterization of hybrid magnesium matrix reinforced with various different wt% (0-0.45) of multi wall carbon nano tubes (MWCNT) and micro SiC particles prepared through powder metallurgy route. Microstructure and mechanical properties such as micro hardness and density of the composites were examined. Microstructure of MMNCs have been investigated by scanning electron microscope, X-ray diffraction and energy dispersive X-ray spectroscopy (EDS) for better observation of dispersion of reinforcement. The results indicated that the increase in wt% of MWCNT improves the mechanical properties of the composite.

  9. Nanostructured composite reinforced material

    Science.gov (United States)

    Seals, Roland D.; Ripley, Edward B.; Ludtka, Gerard M.

    2012-07-31

    A family of materials wherein nanostructures and/or nanotubes are incorporated into a multi-component material arrangement, such as a metallic or ceramic alloy or composite/aggregate, producing a new material or metallic/ceramic alloy. The new material has significantly increased strength, up to several thousands of times normal and perhaps substantially more, as well as significantly decreased weight. The new materials may be manufactured into a component where the nanostructure or nanostructure reinforcement is incorporated into the bulk and/or matrix material, or as a coating where the nanostructure or nanostructure reinforcement is incorporated into the coating or surface of a "normal" substrate material. The nanostructures are incorporated into the material structure either randomly or aligned, within grains, or along or across grain boundaries.

  10. Improved performance of diatomite-based dental nanocomposite ceramics using layer-by-layer assembly

    Directory of Open Access Journals (Sweden)

    Lu X

    2012-04-01

    Full Text Available Xiaoli Lu1,2, Yang Xia1, Mei Liu1, Yunzhu Qian3, Xuefeng Zhou4, Ning Gu4, Feimin Zhang1,41Institute of Stomatology, Nanjing Medical University, Nanjing, 2Nantong Stomatological Hospital, Nantong, 3Center of Stomatology, The Second Affiliated Hospital of Suzhou University, Suzhou, 4Suzhou Institute, Southeast University, Suzhou, People's Republic of ChinaAbstract: To fabricate high-strength diatomite-based ceramics for dental applications, the layer-by-layer technique was used to coat diatomite particles with cationic [poly(allylamine hydrochloride] and anionic [poly(sodium 4-styrenesulfonate] polymers to improve the dispersion and adsorption of positively charged nano-ZrO2 (zirconia as a reinforcing agent. The modified diatomite particles had reduced particle size, narrower size distribution, and were well dispersed, with good adsorption of nano-ZrO2. To determine the optimum addition levels for nano-ZrO2, ceramics containing 0, 20, 25, 30, and 35 wt% nano-ZrO2 were sintered and characterized by the three-point bending test and microhardness test. In addition to scanning electron microscopy, propagation phase-contrast synchrotron X-ray microtomography was used to examine the internal structure of the ceramics. The addition of 30 wt% nano-ZrO2 resulted in the highest flexural strength and fracture toughness with reduced porosity. Shear bond strength between the core and veneer of our diatomite ceramics and the most widely used dental ceramics were compared; the shear bond strength value for the diatomite-based ceramics was found to be significantly higher than for other groups (P < 0.05. Our results show that diatomite-based nanocomposite ceramics are good potential candidates for ceramic-based dental materials.Keywords: layer-by-layer, diatomite, nanoceramics, zirconia (ZrO2, dental materials

  11. Microstructure and Wear Resistance of in situ NbC Particles Reinforced Ni-based Alloy Composite Coating by Laser Cladding

    Institute of Scientific and Technical Information of China (English)

    DONG Gang; YAN Biao; DENG Qilin; YU Ting

    2012-01-01

    The in situ synthesized NbC particles reinforced Ni-based alloy composite coating was produced by laser cladding a precursor mixture of Ni-based alloy powder,graphite and niobium powders on a steel substrate.The microstructure,phase composition and wear property of the composite coating were investigated by means of scanning electron microscopy (SEM),X-ray diffraction (XRD) and dry sliding wear test.The experiment results show that the composite coating is homogeneous and free from cracks,and about 0.8 mm thick.The microstructure of the composite coating is mainly composed of NbC particles,CrB type chromium borides,γ-Ni primary dendrites,and interdendritic eutectics.CrB phases often nucleate and grow on the surface of NbC particles or in their close vicinity.NbC particles are formed via in situ reaction between niobium and graphite in the molten pool during the laser cladding process and they are commonly precipitated in three kinds of morphologies,such as quadrangle,cluster,and flower-like shape.Compared with the pure Nibased alloy coating,the microhardness of the composite coating is increased about 38%,giving a high average hardness of HV0.21000,and the wear rate of the composite coating is decreased by about 32%,respectively.These are attributed to the presence of in situ synthesized NbC particles and their well distribution in the coating.

  12. High-temperature mechanical properties and fracture mechanisms of Al–Si piston alloy reinforced with in situ TiB2 particles

    International Nuclear Information System (INIS)

    In order to assess the high-temperature performance of aluminum–silicon alloy reinforced with titanium diboride particles as potential piston material, the tensile behaviors and fracture mechanisms of in situ 4 wt% TiB2/Al–Si composite were investigated in the temperature range 25–350 °C. The tensile results revealed that the composite exhibited higher modulus than the matrix alloy at all testing temperatures, but both the matrix alloy and the composite presented similar strength levels above 200 °C. The ductility of the composite was found to be lower than that of the unreinforced matrix alloy at 25 and 200 °C, but no obvious distinction was observed at 350 °C. The effects of temperature and the presence of TiB2 particles on tensile properties of the composite had been evaluated. Fractographic morphology studies were done using scanning electron microscope, which indicated that the fracture of the composite altered from brittle to ductile mode with temperature increasing. At 25 and 200 °C, fracture was dominated by cracked silicon particles and separated TiB2 particles, while decohesion at particle–matrix interface was prevalent at 350 °C. Analysis of the fracture surfaces also showed that regions of clustered TiB2 particles were found to be the locations prone to damage in the composite at both room and high temperatures

  13. High-temperature mechanical properties and fracture mechanisms of Al–Si piston alloy reinforced with in situ TiB{sub 2} particles

    Energy Technology Data Exchange (ETDEWEB)

    Han, Gang [School of Mechanical Engineering, Beijing Institute of Technology, 5 South Zhongguancun Street, Haidian District, Beijing 100081 (China); Zhang, Weizheng, E-mail: zhangwz@bit.edu.cn [School of Mechanical Engineering, Beijing Institute of Technology, 5 South Zhongguancun Street, Haidian District, Beijing 100081 (China); Zhang, Guohua; Feng, Zengjian; Wang, Yanjun [Shandong Binzhou Bohai Piston Co., Ltd., Binzhou 256602 (China)

    2015-05-01

    In order to assess the high-temperature performance of aluminum–silicon alloy reinforced with titanium diboride particles as potential piston material, the tensile behaviors and fracture mechanisms of in situ 4 wt% TiB{sub 2}/Al–Si composite were investigated in the temperature range 25–350 °C. The tensile results revealed that the composite exhibited higher modulus than the matrix alloy at all testing temperatures, but both the matrix alloy and the composite presented similar strength levels above 200 °C. The ductility of the composite was found to be lower than that of the unreinforced matrix alloy at 25 and 200 °C, but no obvious distinction was observed at 350 °C. The effects of temperature and the presence of TiB{sub 2} particles on tensile properties of the composite had been evaluated. Fractographic morphology studies were done using scanning electron microscope, which indicated that the fracture of the composite altered from brittle to ductile mode with temperature increasing. At 25 and 200 °C, fracture was dominated by cracked silicon particles and separated TiB{sub 2} particles, while decohesion at particle–matrix interface was prevalent at 350 °C. Analysis of the fracture surfaces also showed that regions of clustered TiB{sub 2} particles were found to be the locations prone to damage in the composite at both room and high temperatures.

  14. Steady- and transient-state analysis of fully ceramic microencapsulated fuel with randomly dispersed tristructural isotropic particles via two-temperature homogenized model-I: Theory and method

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Yoon Hee; Cho, Bum Hee; Cho, Nam Zin [Dept. of Nuclear and Quantum Engineering, Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of)

    2016-06-15

    As a type of accident-tolerant fuel, fully ceramic microencapsulated (FCM) fuel was proposed after the Fukushima accident in Japan. The FCM fuel consists of tristructural isotropic particles randomly dispersed in a silicon carbide (SiC) matrix. For a fuel element with such high heterogeneity, we have proposed a two-temperature homogenized model using the particle transport Monte Carlo method for the heat conduction problem. This model distinguishes between fuel-kernel and SiC matrix temperatures. Moreover, the obtained temperature profiles are more realistic than those of other models. In Part I of the paper, homogenized parameters for the FCM fuel in which tristructural isotropic particles are randomly dispersed in the fine lattice stochastic structure are obtained by (1) matching steady-state analytic solutions of the model with the results of particle transport Monte Carlo method for heat conduction problems, and (2) preserving total enthalpies in fuel kernels and SiC matrix. The homogenized parameters have two desirable properties: (1) they are insensitive to boundary conditions such as coolant bulk temperatures and thickness of cladding, and (2) they are independent of operating power density. By performing the Monte Carlo calculations with the temperature-dependent thermal properties of the constituent materials of the FCM fuel, temperature-dependent homogenized parameters are obtained.

  15. Strengthening of steels by ceramic phases

    OpenAIRE

    Feng, Yujie

    2013-01-01

    Production of ceramic reinforced thin sheet steel composites for automotive application with low density, high elastic modulus and strength is the aim of current study. Within this work, potential of various ceramic phases and possible processing routes were studied, summarized and compared through literature research. Laboratory production of TiC, TiB2 and Fe2B reinforced steel composites through conventional melting-casting route, twin roller route and powder metallurgy method were carried ...

  16. Research on the Surface Micro-configuration in Vibration Cutting Particle Reinforced Metallic Matrix Composites SiC_p/Al

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The cutting performance of particulate reinforced me tallic matrix composites(PRMMCs) SiC p/Al in ultrasonic vibration cutting and c ommon cutting with carbide tools and PCD tools was researched in the paper. Mic rostructure of machined surface was described, the relation between cutting para meters and surface roughness was presented, and characteristic of the surface re mained stress was also presented. Furthermore, wear regularity and abrasion resi stance ability of tools in ultrasonic vibration cut...

  17. Fatigue Life Prediction of Carbon Fiber-Reinforced Ceramic-Matrix Composites at Room and Elevated Temperatures. Part I: Experimental Analysis

    Science.gov (United States)

    Longbiao, Li

    2016-04-01

    This paper presents an experimental analysis on the fatigue behavior in C/SiC ceramic-matrix composites (CMCs) with different fiber preforms, i.e., unidirectional, cross-ply and 2.5D woven, at room and elevated temperatures in air atmosphere. The experimental fatigue life S - N curves of C/SiC composites corresponding to different stress levels and test conditions have been obtained. The damage evolution processes under fatigue loading have been analyzed using fatigue hysteresis modulus and fatigue hysteresis loss energy. By comparing the experimental fatigue hysteresis loss energy with theoretical computational values, the interface shear stress corresponding to different peak stress, fiber preforms and test conditions have been estimated. It was found that the degradation of interface shear stress and fibres strength caused by oxidation markedly decreases the fatigue life of C/SiC composites at elevated temperature.

  18. High pressure ceramic heat exchanger

    Science.gov (United States)

    Harkins, Bruce D.; Ward, Michael E.

    1998-01-01

    Many recuperators have components which react to corrosive gases and are used in applications where the donor fluid includes highly corrosive gases. These recuperators have suffered reduced life, increased service or maintenance, and resulted in increased cost. The present header assembly when used with recuperators reduces the brittle effect of a portion of the ceramic components. Thus, the present header assembly used with the present recuperator increases the life, reduces the service and maintenance, and reduces the increased cost associated with corrosive action of components used to manufacture recuperators. The present header assembly is comprised of a first ceramic member, a second ceramic member, a strengthening reinforcing member being in spaced relationship to the first ceramic member and the second ceramic member. The header assembly is further comprised of a refractory material disposed in contacting relationship with the first ceramic member, the second ceramic member and the strengthening reinforcing member. The present header assembly provides a high strength load bearing header assembly having good thermal cycling characteristics, good resistance to a corrosive environment and good steady state strength at elevated temperatures.

  19. Application and advantages of novel clay ceramic particles (CCPs) in an up-flow anaerobic bio-filter (UAF) for wastewater treatment.

    Science.gov (United States)

    Han, Wei; Yue, Qinyan; Wu, Suqing; Zhao, Yaqin; Gao, Baoyu; Li, Qian; Wang, Yan

    2013-06-01

    Utilization of clay ceramic particles (CCPs) as the novel filter media employed in an up-flow anaerobic bio-filter (UAF) was investigated. After a series of tests and operations, CCPs have presented higher total porosity and roughness, meanwhile lower bulk and grain density. When CCPs were utilized as fillers, the reactor had a shorter start up period of 45 days comparing with conventional reactors, and removal rate of chemical oxygen demand (COD) still reached about 76% at a relatively lower temperature during the stable state. In addition, degradation of COD and ammonia nitrogen (NH4-N) at different media height along the reactor was evaluated, and the dates showed that the main reduction process happened within the first 30 cm media height from the bottom flange. Five phases were observed according to different organic loadings during the experiment period, and the results indicated that COD removal increased linearly when the organic loading was increased.

  20. Novel processing of bioglass ceramics from silicone resins containing micro- and nano-sized oxide particle fillers.

    Science.gov (United States)

    Fiocco, L; Bernardo, E; Colombo, P; Cacciotti, I; Bianco, A; Bellucci, D; Sola, A; Cannillo, V

    2014-08-01

    Highly porous scaffolds with composition similar to those of 45S5 and 58S bioglasses were successfully produced by an innovative processing method based on preceramic polymers containing micro- and nano-sized fillers. Silica from the decomposition of the silicone resins reacted with the oxides deriving from the fillers, yielding glass ceramic components after heating at 1000°C. Despite the limited mechanical strength, the obtained samples possessed suitable porous architecture and promising biocompatibility and bioactivity characteristics, as testified by preliminary in vitro tests.

  1. Tensile creep characteristics of Sn–3.5Ag–0.5Cu (SAC355) solder reinforced with nano-metric ZnO particles

    International Nuclear Information System (INIS)

    Recently, nano-composite solders have been developed in the electronic packaging materials industry to improve the mechanical response of solder joints to be used in service under different conditions. In this study mechanical mixing has been used to disperse nano-metric ZnO particles in Sn–3.5Ag–0.5Cu (SAC355) solder at 420 °C for 2 h. In comparison with SAC355 solder, addition of nano-metric ZnO particles effectively suppressed the formation and restricted the volume fraction of the Ag3Sn and Cu6Sn5 intermetallic compound particles, lowering grain sizes and controlled the growth of β-Sn grains in the matrix. An improvement in tensile creep resistance of the reinforced SAC355 composite is noticed. This improvement seems to be due to its effect in structural refinement and makes the composite solder to display a large creep life time. The addition of nano-metric ZnO particles keeps the melting temperature nearly at the SAC355 level, indicating that the composite solder is fit for the existing soldering process

  2. In vitro comparative bond strength of contemporary self-adhesive resin cements to zirconium oxide ceramic with and without air-particle abrasion.

    Science.gov (United States)

    Blatz, Markus B; Phark, Jin-Ho; Ozer, Fusun; Mante, Francis K; Saleh, Najeed; Bergler, Michael; Sadan, Avishai

    2010-04-01

    This study compared shear bond strengths of six self-adhesive resin cements to zirconium oxide ceramic with and without air-particle abrasion. One hundred twenty zirconia samples were air-abraded (group SB; n = 60) or left untreated (group NO). Composite cylinders were bonded to the zirconia samples with either BisCem (BC), Maxcem (MC), G-Cem (GC), RelyX Unicem Clicker (RUC), RelyX Unicem Applicator (RUA), or Clearfil SA Cement (CSA). Shear bond strength was tested after thermocycling, and data were analyzed with analysis of variance and Holm-Sidak pairwise comparisons. Without abrasion, RUA (8.0 MPa), GC (7.9 MPa), and CSA (7.6 MPa) revealed significantly higher bond strengths than the other cements. Air-particle abrasion increased bond strengths for all test cements (p CSA (18.4 MPa) revealed the highest bond strengths in group SB. Bond strengths of self-adhesive resin cements to zirconia were increased by air-particle abrasion. Cements containing adhesive monomers (MDP/4-META) were superior to other compositions. PMID:19415350

  3. Effect of heat treatment on microstructure and mechanical properties of ZrC particles reinforced tungsten-matrix composites

    International Nuclear Information System (INIS)

    A 20 vol.% ZrCp/W composite is fabricated by hot-pressing, and its mechanical properties can be significantly improved by the addition of ZrC particles. On the other side, the residual pores within ZrC particles clustering regions which are some latent microcrack sources are mainly caused by the relative low sinterability of ZrC particles. In order to eliminate the pores within the particle clusters, the as-sintered composite is annealed at 2300 deg. C for 1 h. The microstructure of the annealed composite becomes more uniform and densified. Components of the as-sintered and annealed composites are composed of a dilute solid solution tungsten-matrix, (Zr, W)C solid solution particles and a new W2C phase, but the content of W2C phase in the annealed composite increases. After annealing, the strength properties of the composite decrease, but its plasticity increases.

  4. How Sensitive Is the Elasticity of Hydroxyapatite-Nanoparticle-Reinforced Chitosan Composite to Changes in Particle Concentration and Crystallization Temperature?

    Directory of Open Access Journals (Sweden)

    Kean Wang

    2015-10-01

    Full Text Available Hydroxyapatite (HA nanoparticle-reinforced chitosan composites are biocompatible and biodegradable structural materials that are used as biomaterials in tissue engineering. However, in order for these materials to function effectively as intended, e.g., to provide adequate structural support for repairing damaged tissues, it is necessary to analyse and optimise the material processing parameters that affect the relevant mechanical properties. Here we are concerned with the strength, stiffness and toughness of wet-spun HA-reinforced chitosan fibres. Unlike previous studies which have addressed each of these parameters as singly applied treatments, we have carried out an experiment designed using a two-factor analysis of variance to study the main effects of two key material processing parameters, namely HA concentration and crystallization temperature, and their interactions on the respective mechanical properties of the composite fibres. The analysis reveals that significant interaction occurs between the crystallization temperature and HA concentration. Starting at a low HA concentration level, the magnitude of the respective mechanical properties decreases significantly with increasing HA concentration until a critical HA concentration is reached, at around 0.20–0.30 (HA mass fraction, beyond which the magnitude of the mechanical properties increases significantly with HA concentration. The sensitivity of the mechanical properties to crystallization temperature is masked by the interaction between the two parameters—further analysis reveals that the dependence on crystallization temperature is significant in at least some levels of HA concentration. The magnitude of the mechanical properties of the chitosan composite fibre corresponding to 40 °C is higher than that at 100 °C at low HA concentration; the reverse applies at high HA concentration. In conclusion, the elasticity of the HA nanoparticle-reinforced chitosan composite fibre is

  5. Influence of the Sr and Mg Alloying Additions on the Bonding Between Matrix and Reinforcing Particles in the AlSi7Mg/SiC-Cg Hybrid Composite

    Directory of Open Access Journals (Sweden)

    Dolata A. J.

    2016-06-01

    Full Text Available The aim of the work was to perform adequate selection of the phase composition of the composite designated for permanent - mould casting air compressor pistons. The hybrid composites based on AlSi7Mg matrix alloy reinforced with mixture of silicon carbide (SiC and glassy carbon (Cg particles were fabricated by the stir casting method. It has been shown that the proper selection of chemical composition of matrix alloy and its modification by used magnesium and strontium additions gives possibility to obtain both the advantageous casting properties of composite suspensions as well as good bonding between particles reinforcements and matrix.

  6. Elaboration of silicon carbides nano particles (SiC): from the powder synthesis to the sintered ceramic; Elaboration de ceramiques nanostructurees en carbure de silicium (SiC): de la synthese de poudre a la ceramique frittee

    Energy Technology Data Exchange (ETDEWEB)

    Reau, A. [CEA Saclay, Dept. des Materiaux pour le Nucleaire (DEN/DANS/DMN/SRMA), 91 - Gif-sur-Yvette (France)

    2008-07-01

    Materials for the reactor cores of the fourth generation will need materials supporting high temperatures with fast neutrons flux. SiC{sub f}/SiC ceramics are proposed. One of the possible elaboration process is to fill SiC fiber piece with nano particles SiC powder and to strengthen by sintering. The aim of this thesis is to obtain a nano structured SiC ceramic as a reference for the SiC{sub f}/SiC composite development and to study the influence of the fabrication parameters. (A.L.B.)

  7. Supported microporous ceramic membranes

    Science.gov (United States)

    Webster, E.; Anderson, M.

    1993-12-14

    A method for the formation of microporous ceramic membranes onto a porous support includes placing a colloidal suspension of metal or metal oxide particles on one side of the porous support and exposing the other side of the porous support to a drying stream of gas or a reactive gas stream so that the particles are deposited on the drying side of the support as a gel. The gel so deposited can be sintered to form a supported ceramic membrane useful for ultrafiltration, reverse osmosis, or molecular sieving having mean pore sizes less than 100 Angstroms. 4 figures.

  8. Ceramic fiber filter technology

    Energy Technology Data Exchange (ETDEWEB)

    Holmes, B.L.; Janney, M.A.

    1996-06-01

    Fibrous filters have been used for centuries to protect individuals from dust, disease, smoke, and other gases or particulates. In the 1970s and 1980s ceramic filters were developed for filtration of hot exhaust gases from diesel engines. Tubular, or candle, filters have been made to remove particles from gases in pressurized fluidized-bed combustion and gasification-combined-cycle power plants. Very efficient filtration is necessary in power plants to protect the turbine blades. The limited lifespan of ceramic candle filters has been a major obstacle in their development. The present work is focused on forming fibrous ceramic filters using a papermaking technique. These filters are highly porous and therefore very lightweight. The papermaking process consists of filtering a slurry of ceramic fibers through a steel screen to form paper. Papermaking and the selection of materials will be discussed, as well as preliminary results describing the geometry of papers and relative strengths.

  9. Recrystallization texture and Young`s modulus of ceramic particle dispersed ferrite steel bars; Ceramics ryushi wo bisai bunsan saseta ferrite bo ko no saikessho shugo soshiki to Young ritsu

    Energy Technology Data Exchange (ETDEWEB)

    Yamamoto, S.; Asabe, K.; Nishiguchi, M.; Maehara, Y. [Sumitomo Metal Industries, Ltd., Osaka (Japan)

    1996-09-01

    Relation was examined between Young`s modulus and the formation behavior of recrystallization texture, in regard to the material in which ferrite steel powders with ceramic particles dispersed were hot-extruded and heat-treated under various conditions. In making samples on an experimental basis, a mechanical alloying method was employed using an electrolytic iron powder and the reagent powder of Cr, Al and Y2O3 as raw materials. The mechanical alloying process was performed by ball mill in the Ar atmosphere at 173Ks. After encapsulation and after heating to 1,323K or 1,423K, hot extrusion was performed. The following results were obtained by the experiment. The Young`s modulus increased about 30% in the extruding direction by applying a heat treatment in a specific temperature range, and 282GPa was obtained which was close to the maximum theoretical value. This was due to the change from (110) extrusion texture to (111) texture. At the heat treatment temperature higher than this, (311) recrystallization texture became the principal azimuth, resulting in lowering of the Young`s modulus. 12 refs., 8 figs., 1 tab.

  10. Retarding the electromigration effects to the eutectic SnBi solder joints by micro-sized Ni-particles reinforcement approach

    International Nuclear Information System (INIS)

    Research highlights: → We used a revised solder joints with one-dimension geometry that can help us to investigate the true failure mechanisms of solder joints induced by EM. → One of possible solutions to inhibit the EM effect to solder joint can be achieved by adding micro- or nano-sized metal particles into it. → Micro-sized Ni particles were selected as the reinforcement to retard the phase segregation in the eutectic SnBi solder joints under high current density (104 A/cm2). It has been approved in this study that Ni particles can act as obstacles to obstruct the fast diffusion channel along the phase boundaries in the eutectic SnBi system. - Abstract: Electromigration (EM) has become one of the reliability concerns to the electronic solder joint due to its increasing capacity to bear the high current density (104 A/cm2). Although the failure induced by EM can trigger a large void across the entire cathode interface, no effective solutions are presented throughout years of effort on this problem. Here, the composite solder joints are addressed to demonstrate their potential roles on solving the EM issue in the eutectic SnBi solder joints. Micro-sized Ni particles were selected to intentionally add into the solder matrix due to their extensive application as a barrier layer in the under-bump-metallization (UBM) of flip chip solder joints. The ultimate results illustrated that the Ni particles can react with Sn to form the cluster-type Sn-Ni intermetallic compounds (IMCs) inside the solder matrix after the first reflow. Accordingly, the phase segregation of Sn and Bi was significantly inhibited during the current stressing, demonstrating the Sn-Ni IMCs can act as the obstacles to obstruct the movement of dominant diffusion entity (Bi atoms/ions) along the phase boundaries.

  11. 关于莫来石陶瓷焊补颗粒熔融时间模拟计算的探讨%Discussion on the simulated calculation of mullite ceramic welding particle melting time

    Institute of Scientific and Technical Information of China (English)

    龚卫凯; 张贤新; 舒敬海

    2015-01-01

    Building the heat transmission model of single gunning particle by the analysis of heat transmission of mullite ceramic welding,calculating the melting time of different gunning particle by means of stable heat transmission formula.It is an important theoretical basis of the particle proportio-ning and operating instruction for mullite ceramic welding.%通过对莫来石陶瓷焊补传热过程剖析,建立了单个喷补颗粒传热过程模型,借助于稳定态传热公式,计算出不同喷补颗粒加热熔融时间,这为莫来石陶瓷焊补颗粒配比及其操作规程的制订提供了重要的理论依据。

  12. Properties of Al2O3 nano-particle reinforced copper matrix composite coatings prepared by pulse and direct current electroplating

    International Nuclear Information System (INIS)

    Highlights: → The influence of Al2O3 is studied on morphologies of the DC and PC applied coatings. → The influence of Al2O3 is studied on the DC and PC coating thicknesses. → The influence of Al2O3 is studied on wear resistance. → The effect of Al2O3 is studied on the porosity and corrosion resistance. -- Abstract: Cu-Al2O3 nano-composite coatings have high potential for use in applications in which high mechanical properties together with high corrosion resistance are required. In the present study it is intended to produce copper nano-alumina composite coatings with various nano-alumina contents in order to investigate the effect of alumina reinforcement particles on corrosion resistance and mechanical properties such as hardness and wear resistance. The composite coatings were deposited using direct current (DC) and pulse current (PC) plating. The microstructures of the coatings produced from both methods were examined via scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques. The wear behaviors, micro hardness, coating thickness, corrosion rate and coating porosity were examined using appropriate methods. Compared to DC deposition, PC plating facilitated higher amounts of particle incorporation with more uniform distribution. The results indicated that the mechanical properties of the applied coatings with incorporated nano-alumina reinforcement were far more superior as compared to its own matrix as well as non-composite copper coatings. It was also found out that increasing the amount of nano-alumina content in the coating, led to enhanced general properties of the coatings.

  13. On Ceramics.

    Science.gov (United States)

    School Arts, 1982

    1982-01-01

    Presents four ceramics activities for secondary-level art classes. Included are directions for primitive kiln construction and glaze making. Two ceramics design activities are described in which students make bizarrely-shaped lidded jars, feet, and footwear. (AM)

  14. Study of new CaO-SiO/sub 2/-P/sub 2/O/sub 5/CaF/sub 2/ bioactive ceramic

    International Nuclear Information System (INIS)

    A new bioactive glass ceramic having, composition 48CaO-32SiO/sub 2/-16P/sub 2/O/sub 5/-4CaF/sub 2/ has been developed and studied for its physical and biological properties. Like the natural bone in which spastic particles are reinforced by collagen, in the present glass-ceramic, fine grained ceramic particles embedded in a glass matrix. X-ray diffraction analysis reveals wollastonite and oxyfluorapatite as the crystalline part of the glass-ceramic. Scanning electron microscopy of the samples has been carried out to see the grain size and grain distribution. Bending and compressive strength of the glass ceramic have been carried out to measured and found to be 208.60 m.Pa and 788.61 M.Pa respectively. Growth of apatite layer, which is responsible for bonding the broken part of a natural bone, on a bioactive glass-ceramic in a simulated body fluid has been studied. A small rectangular piece of this glass-ceramic has also been implanted successfully in a dog's tibia. (author)

  15. The effect of particle addition and fibrous reinforcement on epoxy-matrix composites for severe sliding conditions

    DEFF Research Database (Denmark)

    Larsen, Thomas Ricco Ølholm; Løgstrup Andersen, Tom; Thorning, Bent;

    2008-01-01

    This paper reports production and tribological testing of epoxy-matrix composites for dry-sliding conditions. The examined composites are produced using the following components: epoxy resin (EP), glass fiber weave (G), carbon/aramid hybrid weave (CA), PTFE particles and nano-scale CuO particles...... are seen when the fibers are parallel and anti-parallel (P-AP) to the sliding direction compared to normal and parallel (N-P). Experiments with incorporating micro-scale PTFE particles and nano-scale CuO particles, respectively, into the epoxy resin along with the carbon/aramid weave shows no difference...... in friction but minor improvements in wear. When micro-scale PTFE particles are incorporated into the neat epoxy resin, i.e. without fibers, an increase in and a decrease in A are measured. When the same is done with nano-CuO a deterioration of both friction and wear properties are seen. At the three roughest...

  16. PIXE (particle induced X-ray emission): A non-destructive analysis method adapted to the thin decorative coatings of antique ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Leon, Y. [CNRS, CEMES, BP 94347, 29 rue J. Marvig, F-31055 Toulouse (France); Universite de Toulouse, UPS, INSA, CEMES, F-31055 Toulouse (France); Sciau, Ph., E-mail: philippe.sciau@cemes.fr [CNRS, CEMES, BP 94347, 29 rue J. Marvig, F-31055 Toulouse (France); Universite de Toulouse, UPS, INSA, CEMES, F-31055 Toulouse (France); Bouquillon, A.; Pichon, L. [C2RMF, 14 quai F. Mitterrand, F-75001 Paris Cedex 01 (France); Parseval, Ph. de [Universite de Toulouse, CNRS, IRD, GET, 14 av. E. Belin, F-31400 Toulouse (France)

    2012-11-15

    Recent trends in study of Greek and Roman potteries have been to develop non-abrasive methods to determine the elemental composition of their thin coatings. This paper investigates the potential of PIXE (particle induced X-ray emission) in this field. This technique has been currently used to determine the bulk elemental composition of several types of artifacts because of its fast and simultaneous ability to measure a large number of elements with good accuracy and without any damage to the sample. However, until now it has never been applied to the measurement of the composition of thin layers owing to the difficulty in limiting the depth of analysis to the layer thickness. In this paper, we show, through a comparative study of reference clay pellets and thin coatings of Terra Sigillata ceramics that reducing the energy of the particle beam the problem can be solved. The decrease of proton energy from 3 MeV (standard condition) to 1.5 MeV allowed us to limit the analyzed depth to the coating thickness without significant alteration of the results. Quantitative elemental analysis remains possible and the quality of results is similar to the one obtained from electron microprobe.

  17. Fatigue Life Prediction of Carbon Fiber-Reinforced Ceramic-Matrix Composites at Room and Elevated Temperatures. Part II: Experimental Comparisons

    Science.gov (United States)

    Longbiao, Li

    2015-12-01

    This paper follows on from the earlier study (Part I) which investigated the fatigue behavior of unidirectional, cross-ply and 2.5D C/SiC composites at room and elevated temperatures. In this paper, a micromechanics approach to predict the fatigue life S-N curves of fiber-reinforced CMCs has been developed considering the fatigue damage mechanism of interface wear or interface oxidation. Upon first loading to fatigue peak stress, matrix multicracking and fiber/matrix interface debonding occur. The two-parameter Weibull model is used to describe fibers strength distribution. The stress carried by broken and intact fibres on the matrix crack plane under fatigue loading is determined based on the Global Load Sharing (GLS) criterion. The fibres failure probabilities under fatigue loading considering the degradation of interface shear stress and fibres strength have been obtained. When the broken fibres fraction approaches critical value, the composite would fatigue fail. The fatigue life S-N curves of unidirectional, cross-ply and 2.5D C/SiC composites at room and elevated temperatures have been predicted. The predicted results agreed with experimental data.

  18. Y-TZP ceramic processing from coprecipitated powders : A comparative study with three commercial dental ceramics

    NARCIS (Netherlands)

    Lazar, Dolores R. R.; Bottino, Marco C.; Ozcan, Mutlu; Valandro, Luiz Felipe; Amaral, Regina; Ussui, Valter; Bressiani, Ana H. A.

    2008-01-01

    Objectives. (1) To synthesize 3 mol% yttria-stabilized zirconia (3Y-TZP) powders via coprecipitation route, (2) to obtain zirconia ceramic specimens, analyze surface characteristics, and mechanical properties, and (3) to compare the processed material with three reinforced dental ceramics. Methods.

  19. Advanced Ceramics

    International Nuclear Information System (INIS)

    The First Florida-Brazil Seminar on Materials and the Second State Meeting about new materials in Rio de Janeiro State show the specific technical contribution in advanced ceramic sector. The others main topics discussed for the development of the country are the advanced ceramic programs the market, the national technic-scientific capacitation, the advanced ceramic patents, etc. (C.G.C.)

  20. Microstructure of a Ni Matrix Composite Coating Reinforced by In-situ TiC Particles Using Plasma Cladding

    Institute of Scientific and Technical Information of China (English)

    WUYu-ping; WANGZe-hua; LINPing-hua

    2004-01-01

    Plasma cladding process was used to prepare the TiC/Ni composite coating on the mild steel substrates. The TiC particles were synthesized in-situ. Microstructure and properties of the coating were investigated by optical microscopy, X-Ray diffraction, SEM, TEM and microhardness tester. The results show that the interface between the coating and the substrate is metallurgically bonded. The coating was uniform and almost defect-free when [Ti+C] varied from 10% to 20% after ball milling. The microstructure of the coating is mainly composed of γ-Ni dendrite, interdendritic eutectic (γ-Ni austenite, M23C6 and CrB) and TiC particles. Most of the TiC particles are spherical and a small fraction is blocky in size of 1-2μm. The TiC particles are smaller at the bottom than near the top of the coating. The coating has a gradient microstructure and a highest hardness of 1000Hv0.1.

  1. Aluminium composite casting dispersion reinforced with iron-aluminium and silicon carbide phases

    Directory of Open Access Journals (Sweden)

    B. Formanek

    2010-10-01

    Full Text Available Aluminium matrix composite with dispersion-reinforced, made by similar to stircasting process was characterised. The mixture of powders was produced by the process of mechanical agglomeration of powdered FexAly and SiC with aluminium. The chemical composition ofagglomerates was selected in a way such as to obtain 25 wt.% reinforcement of the AlSi9Cu4 silumin matrix. Applying thermal analysis ATD, the alloy solidification process was determined, reading out the typical solidification parameters. The methods of light and scanning microscopy were used to reveal the structure of composite casting. Changes in chemical composition and phase composition of particles of the FeAl intermetallic phase in aluminium matrix were confirmed. The structure of silumin casting with matrix containing microregions of ceramic and intermetallic phases, typical of hybrid reinforcements, was obtained.

  2. Ni-Al{sub x}Ni{sub y} core–shell structured particle reinforced Al-based composites fabricated by in-situ powder metallurgy technique

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Wenqian; Guo, Baisong; Xue, Yang; Shen, Rujuan; Ni, Song; Song, Min, E-mail: msong@csu.edu.cn

    2015-06-15

    Ni-Al{sub x}Ni{sub y} core–shell structured particle reinforced aluminum based composites were fabricated using in-situ powder metallurgy method. Scanning electron microscope, X-ray diffraction, density analysis, hardness and compressive tests were used to investigate the effects of volume fraction of Ni particles and sintering atmosphere on the microstructures and mechanical properties of the composites. It has been shown that compared to Ar sintering atmosphere, N{sub 2} atmosphere is active sintering atmosphere for fabricating the composites. The AlN formed during the sintering process, which can substantially increase the density and hardness of the composites. The strength of the composites sintered under N{sub 2} atmosphere is higher than that of the composites sintered under Ar, while the ductility is slightly lower. It can be confirmed that the Ni-Al{sub x}Ni{sub y} core–shell structures are of great benefit not only to increase the strength but also to remain the plasticity of the composites. - Highlights: • A new metal matrix composite (MMC) has been developed. • The developed MMC has a matrix/shell/core structure. • The developed MMC has both high strength and plasticity.

  3. Ni-AlxNiy core–shell structured particle reinforced Al-based composites fabricated by in-situ powder metallurgy technique

    International Nuclear Information System (INIS)

    Ni-AlxNiy core–shell structured particle reinforced aluminum based composites were fabricated using in-situ powder metallurgy method. Scanning electron microscope, X-ray diffraction, density analysis, hardness and compressive tests were used to investigate the effects of volume fraction of Ni particles and sintering atmosphere on the microstructures and mechanical properties of the composites. It has been shown that compared to Ar sintering atmosphere, N2 atmosphere is active sintering atmosphere for fabricating the composites. The AlN formed during the sintering process, which can substantially increase the density and hardness of the composites. The strength of the composites sintered under N2 atmosphere is higher than that of the composites sintered under Ar, while the ductility is slightly lower. It can be confirmed that the Ni-AlxNiy core–shell structures are of great benefit not only to increase the strength but also to remain the plasticity of the composites. - Highlights: • A new metal matrix composite (MMC) has been developed. • The developed MMC has a matrix/shell/core structure. • The developed MMC has both high strength and plasticity

  4. Laser melt injection of hard ceramic particles into Al and Ti alloys - processing, microstructure and mechanical behavior

    NARCIS (Netherlands)

    Ocelik, V; Nijman, S; van Ingen, R; Oliveira, U; De Hosson, J Th M

    2003-01-01

    The conditions for a successful Laser Melt Injection (LMI) of SiC and WC particles into the melt pool of Al8Si and Ti6Al4V alloys were studied exptl. and theor. by FEM calcns. The laser employed is a high power Nd:YAG. The formation of a relatively thick aluminum oxide layer on the Al melt surface w

  5. Laser melt injection of hard ceramic particles into Al and Ti alloys - processing, microstructure and mechanical behaviour

    NARCIS (Netherlands)

    Ocelik, V.; Nijman, S.; van Ingen, R.; Oliveira, U.; de Hosson, J.T.M.; Brebbia, CA; DeHosson, JTM; Nishida, SI

    2003-01-01

    The conditions for a successful Laser Melt Injection (LMI) of SiC and WC particles into the melt pool of Al8Si and Ti6A14V alloys were studied experimentally and theoretically by FEM calculations. The laser employed is a high power Nd:YAG. The formation of a relatively thick aluminium oxide layer on

  6. Kinetics of nitrification in a fixed biofilm reactor using dewatered sludge-fly ash composite ceramic particle as a supporting medium.

    Science.gov (United States)

    Lee, Mong-Chuan; Lin, Yen-Hui; Yu, Huang-Wei

    2014-11-01

    A mathematical model system was derived to describe the kinetics of ammonium nitrification in a fixed biofilm reactor using dewatered sludge-fly ash composite ceramic particle as a supporting medium. The model incorporates diffusive mass transport and Monod kinetics. The model was solved using a combination of the orthogonal collocation method and Gear's method. A batch test was conducted to observe the nitrification of ammonium-nitrogen ([Formula: see text]-N) and the growth of nitrifying biomass. The compositions of nitrifying bacterial community in the batch kinetic test were analyzed using PCR-DGGE method. The experimental results show that the most staining intensity abundance of bands occurred on day 2.75 with the highest biomass concentration of 46.5 mg/L. Chemostat kinetic tests were performed independently to evaluate the biokinetic parameters used in the model prediction. In the column test, the removal efficiency of [Formula: see text]-N was approximately 96 % while the concentration of suspended nitrifying biomass was approximately 16 mg VSS/L and model-predicted biofilm thickness reached up to 0.21 cm in the steady state. The profiles of denaturing gradient gel electrophoresis (DGGE) of different microbial communities demonstrated that indigenous nitrifying bacteria (Nitrospira and Nitrobacter) existed and were the dominant species in the fixed biofilm process.

  7. Improving the strength of ceramics by controlling the interparticle forces and rheology of the ceramic suspensions

    CERN Document Server

    Chou, Y P

    2001-01-01

    This thesis describes a study of the modification of the interparticle forces of colloidal ceramic particles in aqueous suspensions in order to improve the microstructural homogeneity, and hence the reliability and mechanical performances, of subsequently formed ceramic compacts. A concentrated stable fine ceramic powder suspension has been shown to be able to generate a higher density of a ceramic product with better mechanical, and also electrical, electrochemical and optical, properties of the ceramic body. This is because in a colloidally stable suspension there are no aggregates and so defect formation, which is responsible for the ceramic body performance below its theoretical maximum, is reduced. In order to achieve this, it is necessary to form a well dispersed ceramic suspension by ensuring the interparticle forces between the particles are repulsive, with as a high a loading with particles as possible. By examining the rheological behaviour and the results of Atomic Force Microscope, the dispersion ...

  8. Ceramic joining

    Energy Technology Data Exchange (ETDEWEB)

    Loehman, R.E. [Sandia National Lab., Albuquerque, NM (United States)

    1996-04-01

    This paper describes the relation between reactions at ceramic-metal interfaces and the development of strong interfacial bonds in ceramic joining. Studies on a number of systems are described, including silicon nitrides, aluminium nitrides, mullite, and aluminium oxides. Joints can be weakened by stresses such as thermal expansion mismatch. Ceramic joining is used in a variety of applications such as solid oxide fuel cells.

  9. Ceramic Processing

    Energy Technology Data Exchange (ETDEWEB)

    EWSUK,KEVIN G.

    1999-11-24

    Ceramics represent a unique class of materials that are distinguished from common metals and plastics by their: (1) high hardness, stiffness, and good wear properties (i.e., abrasion resistance); (2) ability to withstand high temperatures (i.e., refractoriness); (3) chemical durability; and (4) electrical properties that allow them to be electrical insulators, semiconductors, or ionic conductors. Ceramics can be broken down into two general categories, traditional and advanced ceramics. Traditional ceramics include common household products such as clay pots, tiles, pipe, and bricks, porcelain china, sinks, and electrical insulators, and thermally insulating refractory bricks for ovens and fireplaces. Advanced ceramics, also referred to as ''high-tech'' ceramics, include products such as spark plug bodies, piston rings, catalyst supports, and water pump seals for automobiles, thermally insulating tiles for the space shuttle, sodium vapor lamp tubes in streetlights, and the capacitors, resistors, transducers, and varistors in the solid-state electronics we use daily. The major differences between traditional and advanced ceramics are in the processing tolerances and cost. Traditional ceramics are manufactured with inexpensive raw materials, are relatively tolerant of minor process deviations, and are relatively inexpensive. Advanced ceramics are typically made with more refined raw materials and processing to optimize a given property or combination of properties (e.g., mechanical, electrical, dielectric, optical, thermal, physical, and/or magnetic) for a given application. Advanced ceramics generally have improved performance and reliability over traditional ceramics, but are typically more expensive. Additionally, advanced ceramics are typically more sensitive to the chemical and physical defects present in the starting raw materials, or those that are introduced during manufacturing.

  10. POROSITY CALCULATION OF MIXTURES OF FIBROUS PARTICLES

    Institute of Scientific and Technical Information of China (English)

    Ruping Zou; Aibing Yu

    2003-01-01

    The initial forming of fiber blend to high green density, i.e. the packing of fibrous particles, is important to the reinforcement of composite materials. It is very useful to develop a general predictive method for the optimum selection of particle mixtures for the property control of ceramic or composite products. This paper presents such a mathematical model developed on the basis of the similarity analysis between the spherical and non-spherical particle packings and assesses its applicability to the packing of fibrous particles with discrete and/or continuous length distributions. The results indicate that the model can predict this packing system well and hence provide an effective way to solve various packing problems in the composite materials processing.

  11. Al2O3-Coated Nano-SiC Particles Reinforced Al2O3 Matrix Composites

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Properties of Al2O3-coated nano-SiC have been compared with those of as-received SiC. The isoelectric point (IEP)of SiC changed from pH3.4 to pH7.3 after coating with the alumina precursor, which is close to that of alumina.Because both surfaces of coated SiC and Al2O3 possess higher positive charge at pH=4.5~5.0, they are uniformly dispersed in the two-phase aqueous suspensions, Then a mixed powder containing nano-SiC dispersed homogeneously into the Al2O3 matrix was achieved from flocculating the two-phase suspension. Finally, Al2O3/SiC nanocomposites were obtained by coating nano-SiC with Al2O3, in which the majority of SiC particles were located within the Al2O3 grains. The observation by transmission electron microscopy (TEM) and the analysis by the X-ray photoelectron spectroscopy (XPS) showed that cracks propagated towards the intragranular SiC rather than along grain boundaries.

  12. Preparation of ZrC nano-particles reinforced amorphous carbon composite coating by atmospheric pressure chemical vapor deposition

    International Nuclear Information System (INIS)

    To eliminate cracks caused by thermal expansion mismatch between ZrC coating and carbon-carbon composites, a kind of ZrC/C composite coating was designed as an interlayer. The atmospheric pressure chemical vapor deposition was used as a method to achieve co-deposition of ZrC and C from ZrCl4-C3H6-H2-Ar source. Zirconium tetrachloride (ZrCl4) powder carrier was especially made to control accurately the flow rate. The microstructure of ZrC/C composite coating was studied using analytical techniques. ZrC/C coating shows same morphology as pyrolytic carbon. Transmission electron microscopy (TEM) shows ZrC grains with size of 10-50 nm embed in turbostratic carbon. The formation mechanism is that the growth of ZrC crystals was inhibited by surrounding pyrolytic carbon and kept as nano-particles. Fracture morphologies imply good combination between coating and substrate. The ZrC crystals have stoichiometric proportion near 1, with good crystalline but no clear preferred orientation while pyrolytic carbon is amorphous. The heating-up oxidation of ZrC/C coating shows 11.58 wt.% loss. It can be calculated that the coating consists of 74.04 wt.% ZrC and 25.96 wt.% pyrolytic carbon. The average density of the composite coating is 5.892 g/cm3 by Archimedes' principle.

  13. Microstructure and Wear Resistance of Plasma-Sprayed Molybdenum Coating Reinforced by MoSi2 Particles

    Science.gov (United States)

    Yan, Jianhui; He, Zheyu; Wang, Yi; Qiu, Jingwen; Wang, Yueming

    2016-08-01

    Mo coatings with or without incorporated MoSi2 were fabricated by atmospheric plasma spraying, and their microstructure, microhardness, bond strength, and wear resistance were compared. Two kinds of spray powder, i.e., pure Mo and a blend of Mo and MoSi2, were sprayed onto low-carbon steel. Microstructural analysis of the MoSi2-Mo coating showed MoSi2 homogeneously distributed in a Mo matrix. Addition of MoSi2 particles increased the microhardness of the as-sprayed Mo coating. The adhesion strength of the Mo coating was better than that of the MoSi2-Mo coating. Wear test results showed that the wear rate and friction coefficient of the two coatings increased with increasing load, and the friction coefficient of the MoSi2-Mo coating was lower than that of the Mo coating. The MoSi2-Mo composite coating exhibited better wear resistance than the Mo coating. The wear failure mechanisms of the two coatings were local plastic deformation, delamination, oxidation, and adhesion wear.

  14. Metal/ceramic interface structures and segregation behavior in aluminum-based composites

    International Nuclear Information System (INIS)

    Trimodal Al alloy (AA) matrix composites consisting of ultrafine-grained (UFG) and coarse-grained (CG) Al phases and micron-sized B4C ceramic reinforcement particles exhibit combinations of strength and ductility that render them useful for potential applications in the aerospace, defense and automotive industries. Tailoring of microstructures with specific mechanical properties requires a detailed understanding of interfacial structures to enable strong interface bonding between ceramic reinforcement and metal matrix, and thereby allow for effective load transfer. Trimodal AA metal matrix composites typically show three characteristics that are noteworthy: nanocrystalline grains in the vicinity of the B4C reinforcement particles; Mg segregation at AA/B4C interfaces; and the presence of amorphous interfacial layers separating nanocrystalline grains from B4C particles. Interestingly, however, fundamental information related to the mechanisms responsible for these characteristics as well as information on local compositions and phases are absent in the current literature. In this study, we use high-resolution transmission electron microscopy, energy-dispersive X-ray spectroscopy, electron energy-loss spectroscopy, and precession assisted electron diffraction to gain fundamental insight into the mechanisms that affect the characteristics of AA/B4C interfaces. Specifically, we determined interfacial structures, local composition and spatial distribution of the interfacial constituents. Near atomic resolution characterization revealed amorphous multilayers and a nanocrystalline region between Al phase and B4C reinforcement particles. The amorphous layers consist of nonstoichiometric AlxOy, while the nanocrystalline region is comprised of MgO nanograins. The experimental results are discussed in terms of the possible underlying mechanisms at AA/B4C interfaces

  15. Production of Al nanocomposite reinforced by Fe-Al intermetallic, Al{sub 4}C{sub 3} and nano-Al{sub 2}O{sub 3} particles using wet milling in toluene

    Energy Technology Data Exchange (ETDEWEB)

    Razavi-Tousi, S.S., E-mail: ser105@mail.usask.ca [Islamic Azad University, Shahrood Branch, Shahrood (Iran, Islamic Republic of); Yazdani-Rad, R. [Materials and Energy Research Center, P.O. Box 31787/316, Karaj (Iran, Islamic Republic of); Manafi, S.A. [Islamic Azad University, Shahrood Branch, Shahrood (Iran, Islamic Republic of)

    2011-06-02

    Highlights: > Production of Al nanocomposite reinforced by Fe-Al intermetallic, Al{sub 4}C{sub 3} and nano-Al{sub 2}O{sub 3} particles using wet milling in toluene. > Production of Al{sub 4}C{sub 3} particles from mechanochemical reaction of Al with PCA. > Effect of second phase particles on sintering. - Abstract: Al matrix nanocomposites were produced by wet milling of Al and nano-alumina powders in a toluene media. X-ray diffraction patterns, inductively coupled plasma, carbon measurement analysis and scanning electron microscopy show that impurities introduced by decomposition of toluene and abrasion of balls and vials are uniformly dispersed in the Al matrix as Al{sub 4}C{sub 3} and Fe-Al intermetallic particles. Though producing homogenous nanocomposites, these second phase particles seem to have a retarding effect on densification of nanocomposite powders.

  16. 基于SPD法颗粒增强铝基复合材料研究综述%REVIEW ON PARTICLE REINFORCED ALUMINUM MATRIX COMPOSITES BASED ON SEVERE PLASTIC DEFORMATION

    Institute of Scientific and Technical Information of China (English)

    李晓; 李萍; 王成; 张倩倩

    2011-01-01

    The paper is about the severe plastic deformation method for particle reinforced aluminum matrix composites fabrication. The current status of research on particle reinforced aluminum matrix composites by Equal Channel Angular Pressing, High Pressure Torsion,Twist Extrusion is reviewed. The prospects of future development are introduced.%简单介绍了利用几种大塑性变形工艺(Severe plastic deformation)制备颗粒增强铝基复合材料的研究概况,叙述了等径角挤压法、高压扭转法、挤扭法制备颖粒增强铝基复合材料的国内外研究现状,并对今后大塑性变形方法制备颗粒增强金属基复合材料的发展进行了展望.

  17. Anchor reinforcements

    Energy Technology Data Exchange (ETDEWEB)

    Levkovich, P.Ye.; Sal' nikov, V.K.; Savich, N.S.

    1980-11-30

    An anchor reinforcement includes an anchor shaft, an elastic jig with a separator wall having compartments placed parallely along it and filled with reinforcement material and a device for destroying the jig wall separator. To quickly put the anchor in place and increase the reliability of the reinforcement by mixing the reinforcement material components better, the device for destroying the jig separator wall was made in the shape of a shovel, fastened to the anchor shaft and the separator wall has a longitudinal hollow for holding the anchor shaft/shovel.

  18. Synthesis, microstructural and mechanical properties of ex situ zircon particles (ZrSiO4 reinforced Metal Matrix Composites (MMCs: a review

    Directory of Open Access Journals (Sweden)

    Satish Kumar Thandalam

    2015-07-01

    This review article details the current development on the synthesis, microstructure and mechanical properties of zircon reinforced MMCs, with specific attention on the abrasive wear behavior of the composites. This review also summarizes the work done by various research groups on zircon reinforced MMCs in achieving higher hardness and wear resistance in these composites.

  19. Research status on SiC and Si hybrid particle reinforced Al matrix composites%SiC和Si混合颗粒增强铝基复合材料的研究现状

    Institute of Scientific and Technical Information of China (English)

    韩辉辉; 王爱琴; 谢敬佩

    2015-01-01

    SiC颗粒增强含Si铝基复合材料在制备过程中由于Si颗粒的析出,使其成为SiC和Si混合颗粒增强铝基复合材料.SiC和Si混合颗粒增强铝基复合材料具有比强度和比刚度高、耐磨性和耐疲劳性好、尺寸稳定性强、轻质等性能,广泛应用于航空、航天、电子电器等工业领域.主要介绍了SiC和Si混合颗粒增强铝基复合材料的研究现状及几种制备工艺,分析了其显微组织中存在的缺陷及复合材料性能的影响因素;展望了SiC和Si混合颗粒增强铝基复合材料的应用前景.%Due to the precipitation of Si particles in the preparation process SiC particle reinforced aluminum ma-trix composites containing Si, the composite turns into SiC and Si hybrid particle reinforced composites. SiC and Si hybrid particle reinforced aluminum matrix composites have high specific strength and stiffness, good wear re-sistance and fatigue resistance, good dimensional stability, lightweight and other excellent properties. It is widely used in aviation, aerospace, electronic appliances industries. The research status on SiC and Si hybrid particle rein-forced aluminum matrix composites and several preparation methods of the composites were introduced. The de-fects existing in the microstructure and influencing factors of composite performance were analyzed. The applica-tion prospect of SiC and Si particle reinforced aluminium matrix composites was also proposed.

  20. Application of pressure infiltration to the manufacturing of aluminium matrix composite materials with different reinforcement shape

    Directory of Open Access Journals (Sweden)

    L.A. Dobrzański

    2007-10-01

    Full Text Available Purpose: The purpose of this work is to investigate the influence of reinforcing phase’s shape on structure and properties of composite materials with aluminium alloy matrix.Design/methodology/approach: The material for studies was produced by a method of pressure infiltration of the porous ceramic framework. In order to investigate the influence of reinforcing phase’s shape the comparison was made between the properties of the composite material based on preforms obtained by Al2O3 Alcoa CL 2500 powder sintered with addition of pore forming agent in form of carbon fibres Sigrafil C 10 M250 UNS from Carbon Group company and composite materials based on much more expensive commercial fibrous preforms. The matrix consisted of cast aluminium alloy EN AC – AlSi12. The observations of the structure were made on the light microscope and in the scanning electron microscope. The strength properties were established on the basis of static tensile tests.Findings: The composite materials, obtained on the basis of ceramic preforms consisted of Al2O3 particles, are showing better strength properties in comparison to materials obtained by the fibrous preform infiltration.Practical implications: The composite materials made by the developed method can find application as the elements of devices where beside the benefits from utilizable properties the small weight is required (mainly in aircraft and motorization industries.Originality/value: The obtained results show the possibility of manufacturing the composite materials by the method of porous sintered framework pressure infiltration based on the ceramic particles, characterized with the better properties than similar composites reinforced with fibres.

  1. Compound characterization of laser brazed SiC-steel joints using tungsten reinforced SnAgTi-alloys

    Science.gov (United States)

    Südmeyer, I.; Rohde, M.; Fürst, T.

    2010-02-01

    With the help of a CO2-laser (λ = 10.64 μm) Silicon carbide (Trade name: Ekasic-F, Comp: ESK Ceramics) has been brazed to commercial steel (C45E, Matnr. 1.1191) using SnAgTi-filler alloys. The braze pellets were dry pressed based on commercially available powders and polished to a thickness of 300 μm. The SnAgTi-fractions were varied with the objective of improving the compound strength. Furthermore, tungsten reinforced SnAgTi-fillers were examined with regard to the shear strength of the ceramic/steel joints. Polished microsections of SnAgTi-pellets were investigated before brazing in order to evaluate the particle distribution and to detect potential porosities using optical microscopy. The brazing temperature and the influence of the reinforcing particles on the active braze filler were determined by measurements with a differential scanning calorimeter (DSC). After brazing. the ceramic-steel joints were characterized by scanning electron micrographs and EDX-analysis. Finally the mechanical strength of the braze-joints was determined by shear tests.

  2. Engineering ceramics

    CERN Document Server

    Bengisu, Murat

    2001-01-01

    This is a comprehensive book applying especially to junior and senior engineering students pursuing Materials Science/ Engineering, Ceramic Engineering and Mechanical Engineering degrees. It is also a reference book for other disciplines such as Chemical Engineering, Biomedical Engineering, Nuclear Engineering and Environmental Engineering. Important properties of most engineering ceramics are given in detailed tables. Many current and possible applications of engineering ceramics are described, which can be used as a guide for materials selection and for potential future research. While covering all relevant information regarding raw materials, processing properties, characterization and applications of engineering ceramics, the book also summarizes most recent innovations and developments in this field as a result of extensive literature search.

  3. Effect of surface treatments on the bond strength of a zirconia-reinforced ceramic to composite resin Efeito de tratamentos de superfície sobre a resistência de união entre cerâmica reforçada por zircônia e resina composta

    Directory of Open Access Journals (Sweden)

    Alvaro Della Bona

    2007-03-01

    Full Text Available The objective of this study was to evaluate the tensile (sigmat and shear bond strength (sigmas of a glass-infiltrated alumina-based zirconia-reinforced ceramic (IZ - Vita In-Ceram Zirconia to a composite resin, testing the hypothesis that silica coating (SC - Cojet, 3M-Espe produces higher bond strength values than other ceramic surface treatments. Specimens were fabricated and tested according to the manufacturers' instructions, and to ISO6872 and ISO11405 specifications. Sixty IZ disk specimens were polished through 1 µm and divided into 3 groups (n = 20 according to the following surface treatments: HF - 9.5% hydrofluoric acid (Ultradent for 1 min; SB - sandblasting with 25-µm aluminum oxide particles for 10 s; SC - silica coating for 10 s. Silane (3M-Espe, adhesive (Single Bond, 3M-Espe and a composite resin cylinder (Z100, 3M-Espe were applied and polymerized to the treated bonding area (3.5 mm in diameter. Ten specimens from each group (n = 10 were tested for sigmat and ten specimens were tested for sigmas, using a universal testing machine (EMIC DL 2000 at a crosshead speed of 1 mm/min. The data were statistically analyzed by ANOVA and Tukey tests (alpha = 0.05. The mean and standard deviation values (MPa and statistical groupings for sigmat were: HF - 3.5 ± 1.0a; SB - 7.6 ± 1.2b; and SC - 10.4 ± 1.8c. For sigmas, the values were: HF - 10.4 ± 3.1A; SB - 13.9 ± 3.1B; and SC - 21.6 ± 1.7C (p O objetivo deste estudo foi avaliar a resistência adesiva à tração (sigmat e ao cisalhamento (sigmas de uma cerâmica à base de alumina infiltrada por vidro e reforçada com zircônia (IZ- Vita In-Ceram Zircônia à resina composta, testando a hipótese de que o sistema de silicatização (SC- Cojet, 3M-ESPE produz valores maiores de resistência adesiva do que demais tratamentos de superfície utilizados. Sessenta corpos-de-prova (cp em forma de disco da IZ foram fabricados e testados de acordo com as instruções dos fabricantes e as

  4. Tailored ceramics

    International Nuclear Information System (INIS)

    In polyphase tailored ceramic forms two distinct modes of radionuclide immobilization occur. At high waste loadings the radionuclides are distributed through most of the ceramic phases in dilute solid solution, as indicated schematically in this paper. However, in the case of low waste loadings, or a high loading of a waste with low radionuclide content, the ceramic can be designed with only selected phases containing the radionuclides. The remaining material forms nonradioactive phases which provide a degree of physical microstructural isolation. The research and development work with polyphase ceramic nuclear waste forms over the past ten years is discussed. It has demonstrated the critical attributes which suggest them as a waste form for future HLW disposal. From a safety standpoint, the crystalline phases in the ceramic waste forms offer the potential for demonstrable chemical durability in immobilizing the long-lived radionuclides in a geologic environment. With continued experimental research on pure phases, analysis of mineral analogue behavior in geochemical environments, and the study of radiation effects, realistic predictive models for waste form behavior over geologic time scales are feasible. The ceramic forms extend the degree of freedom for the economic optimization of the waste disposal system

  5. 陶瓷纤维增强混凝土高温损伤的超声特性%Ultrasonic properties of fire damage of ceramic fiber reinforced concrete

    Institute of Scientific and Technical Information of China (English)

    许金余; 孙广坦; 任韦波; 白二雷

    2013-01-01

    The damaged characteristics of ceramic fiber reinforced concrete (CFRC) after elevated temperature were studied by ultrasonic testing and compressive strength testing. The influences of the temperature and the cooling methods on the compressive strength, longitudinal wave velocity and main frequency were analyzed. The results indicate that the properties of CFRC deteriorate, and that the compressive strength, the longitudinal wave velocity, and the main frequency decrease with the rising of temperature. The critical temperature of CFRC is 400 ℃. The degree of deterioration of CFRC is relatively lower before 400℃ , the longitudinal wave velocity and the main frequency increase in 400 ℃ , and the rate of deterioration and the properties of CFRC decrease sharply above 400 ℃. The properties of specimens cooled by spraying water are worse than those of specimens cooled naturally. When the longitudinal wave velocity ranges from 1. 0 to 3. 5 km/s, there is a positive correlation between it and the compressive strength, and this relationship becomes uncertain when it is in 3. 5-4. 5 km/s. The damage factor defined by the longitudinal wave velocity can well reflect the regularity of the damage evolution of CFRC after elevated temperature.%通过超声波检测和抗压强度试验对高温后陶瓷纤维增强混凝土(CFRC)的损伤特性进行了研究,分析了加热温度和冷却方式对抗压强度、纵波波速和主频带来的影响.分析表明,随着温度的升高,CFRC性能不断劣化,抗压强度、纵波波速及主频总体呈下降趋势;400℃为CFRC性能突变的临界温度,400℃之前,其劣化程度较小,且抗压强度与主频在400℃时有所回升,400℃之后,劣化速率明显增大,结构性能急剧下降;同自然冷却情况相比,浇水冷却后CFRC各项性能指标下降更为严重;纵波波速在1.0~3.5 km/s内与抗压强度具有正相关性,在3.5~4.5 km/s内两者相关性不确定.利用纵波波速定义

  6. Synthesis and Characterization of SiC Reinforced HE-30 Al Alloy Particulate MMCs

    Directory of Open Access Journals (Sweden)

    Pradyumna Phutane

    2013-06-01

    Full Text Available Metal matrix composites have evoked a keen interest in recent times for potential applications in many areas, especially aerospace & automotive industries owing to their superior strength to weight ratio. A particle reinforced metal matrix composite consists of uniform distribution of strengthening ceramic particles embedded within metal matrix. Manufacturing of aluminum alloy based composites via stir casting is one of the prominent and economical routes for processing of metal matrix composites. An attempt has been made to synthesize HE-30 Al Alloy-SiC particulate metal matrix composite by liquid metallurgy route. Micro-structural characterization revealed fairly uniform distribution of SiC particles in the matrix. The prepared composite was subjected to the mechanical testing as per ASTM standards. The mechanical tests revealed an increase in hardness and tensile strength of the developed composites over the base metal alloy.

  7. Structural Ceramics Database

    Science.gov (United States)

    SRD 30 NIST Structural Ceramics Database (Web, free access)   The NIST Structural Ceramics Database (WebSCD) provides evaluated materials property data for a wide range of advanced ceramics known variously as structural ceramics, engineering ceramics, and fine ceramics.

  8. Influence of ceramic particulate type on microstructure and tensile strength of aluminum matrix composites produced using friction stir processing

    Directory of Open Access Journals (Sweden)

    I. Dinaharan

    2016-06-01

    Full Text Available Friction stir processing (FSP was applied to produce aluminum matrix composites (AMCs. Aluminum alloy AA6082 was used as the matrix material. Various ceramic particles, such as SiC, Al2O3, TiC, B4C and WC, were used as reinforcement particle. AA6082 AMCs were produced using a set of optimized process parameters. The microstructure was studied using optical microscopy, filed emission scanning electron microscopy and electron back scattered diagram. The results indicated that the type of ceramic particle did not considerably vary the microstructure and ultimate tensile strength (UTS. Each type of ceramic particle provided a homogeneous dispersion in the stir zone irrespective of the location and good interfacial bonding. Nevertheless, AA6082/TiC AMC exhibited superior hardness and wear resistance compared to other AMCs produced in this work under the same set of experimental conditions. The strengthening mechanisms and the variation in the properties are correlated to the observed microstructure. The details of fracture mode are further presented.

  9. Metallic and intermetallic-bonded ceramic composites

    Energy Technology Data Exchange (ETDEWEB)

    Plucknett, K.P.; Tiegs, T.N.; Alexander, K.B. [Oak Ridge National Laboratory, TN (United States)] [and others

    1995-05-01

    The purpose of this task is to establish a framework for the development and fabrication of metallic-phase-reinforced ceramic matrix composites with improved fracture toughness and damage resistance. The incorporation of metallic phases that plastically deform in the crack tip region, and thus dissipate strain energy, will result in an increase in the fracture toughness of the composite as compared to the monolithic ceramic. It is intended that these reinforced ceramic matrix composites will be used over a temperature range from 20{degrees}C to 800-1200{degrees}C for advanced applications in the industrial sector. In order to systematically develop these materials, a combination of experimental and theoretical studies must be undertaken.

  10. Steady- and transient-state analysis of fully ceramic microencapsulated fuel with randomly dispersed tristructural isotropic particles via two-temperature homogenized model-II: Applications by coupling with COREDAX

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Yoon Hee; Cho, Bum Hee; Cho, Nam Zin [Dept. of Nuclear and Quantum Engineering, Korea Advanced Institute of Science and Technology, Daejeon (Korea, Republic of)

    2016-06-15

    In Part I of this paper, the two-temperature homogenized model for the fully ceramic microencapsulated fuel, in which tristructural isotropic particles are randomly dispersed in a fine lattice stochastic structure, was discussed. In this model, the fuel-kernel and silicon carbide matrix temperatures are distinguished. Moreover, the obtained temperature profiles are more realistic than those obtained using other models. Using the temperature-dependent thermal conductivities of uranium nitride and the silicon carbide matrix, temperature-dependent homogenized parameters were obtained. In Part II of the paper, coupled with the COREDAX code, a reactor core loaded by fully ceramic microencapsulated fuel in which tristructural isotropic particles are randomly dispersed in the fine lattice stochastic structure is analyzed via a two-temperature homogenized model at steady and transient states. The results are compared with those from harmonic- and volumetric-average thermal conductivity models; i.e., we compare keff eigenvalues, power distributions, and temperature profiles in the hottest single channel at a steady state. At transient states, we compare total power, average energy deposition, and maximum temperatures in the hottest single channel obtained by the different thermal analysis models. The different thermal analysis models and the availability of fuel-kernel temperatures in the two-temperature homogenized model for Doppler temperature feedback lead to significant differences.

  11. Silica reinforced triblock copolymer gels

    DEFF Research Database (Denmark)

    Theunissen, E.; Overbergh, N.; Reynaers, H.;

    2004-01-01

    The effect of silica and polymer coated silica particles as reinforcing agents on the structural and mechanical properties of polystyrene-poly(ethylene/butylene)-polystyrene (PS-PEB-PS) triblock gel has been investigated. Different types of chemically modified silica have been compared in order...... to evaluate the influence of the compatibility between gel and filler. Time-resolved SANS and small-angle X-ray scattering (SAXS) shows that the presence of silica particles affects the ordering of the polystyrene domains during gelsetting. The scattering pattern of silica-reinforced gels reveals strong...... scattering at very low q, but no structure and formfactor information. However, on heating above the viscoelastic to plastic transition, the 'typical' scattering pattern of the copolymer gel builds-up. All reinforced gels are strengthened by the addition of the reinforcing agent. The transitions from...

  12. 3种树脂加强型玻璃离子与氧化锆陶瓷粘接性能的研究%Study of bonding property among 3 kinds of resin-reinforced glass ionomer and zirconia ceramics

    Institute of Scientific and Technical Information of China (English)

    林艺华; 宋晓萌; 张玮

    2013-01-01

    Objective To study the bonding efficiency of zirconia ceramics with 3 kinds of resin-reinforced glass ionomer. Methods Blocks of sintered zirconia ceramics were cut and randomly divided into 3 groups with 20 slices each. They were treated with sandblasting and bonded with 3 kinds of resin-reinforced glass ionomer respectively. Af-ter preserved in distilled-water for 24 hours and aged by thermocycling 5 000 times, the shear bond strength of these specimens was tested and data were analyzed by SPSS 11.5 system for windows. The bonding face was observed by scanning electron microscope. Results The shear bond strength of the ceramic and 3 kinds of resin-reinforced glass ionomer was(15.1±3.2),(16.1±4.0),(18.6±3.4)MPa(after preserved in distilled-water for 24 hours) respectively, and decreased greatly to(5.1±2.1),(7.5±2.9),(8.7±2.6)MPa(after thermocycling 5 000 times). There was obvious statistical difference before and after thermocycling(P<0.05). Conclusion Resin-reinforced glass ionomer can get good initial bond strength with zirconia ceramics, but the bonding durability is poor.%  目的探讨3种树脂加强型玻璃离子用于口腔科氧化锆陶瓷的粘接效果。方法将烧结成型的氧化锆陶瓷片分为3组,每组20片,分别采用3种树脂加强型玻璃离子粘接剂与喷砂后的氧化锆陶瓷片粘接,在水浴24 h和冷热循环5000次后测试其粘接剪切强度,数据用SPSS 11.5软件加以统计分析,粘接断面及剖面用扫描电子显微镜观察。结果3种粘接剂与氧化锆陶瓷的粘接剪切强度分别为:(15.1±3.2)、(16.1±4.0)、(18.6±3.4)MPa(水浴24 h后),(5.1±2.1)、(7.5±2.9)、(8.7±2.6)MPa(冷热循环5000次后)。冷热循环后各组的粘接剪切强度均有明显下降(P<0.05)。结论树脂加强型玻璃离子粘接剂可以与氧化锆陶瓷产生良好的初期粘接强度,但效果不能持久。

  13. The influence of reinforcement shape on wear behaviour of aluminium matrix composite materials

    Directory of Open Access Journals (Sweden)

    L.A. Dobrzański

    2010-09-01

    Full Text Available urpose: The purpose of this paper is to present the research results of modern metal matrix composite materials. The matrix material was EN AC - AlSi12 alloy while the reinforcement ceramic performs. In order to investigate the influence of reinforcing phase’s shape on tribological properties the comparison was made between the composite material based on preforms obtained by Al2O3 Alcoa CL 2500 powder sintered with addition of pore forming agent in form of carbon fibres Sigrafil C 10 M250 UNS from Carbon Group company and composite materials based on much more expensive commercial fibrous preforms.Design/methodology/approach: The composite was produced by the use of porous material pressure infiltration method. Obtained composite materials were examined with light and scanning electron microscopy. Hardness test was carried out with Rockwell method in A scale. Additionally, the wear resistance was measured by the use of device designed in the Institute of Engineering Materials and Biomaterials. The device realize dry friction wear mechanism of reciprocating movement conditions.Findings: The obtained results show the possibility of manufacturing the new composite materials by the method of porous sintered framework pressure infiltration based on the ceramic particles, with desired microstructure and properties, being a cheaper alternative for materials with base of ceramic fibers.Practical implications: Tested composite materials can be apply among the others in automotive and aircraft industries.Originality/value: Worked out technology of composite materials manufacturing can be used in the production of near net shape and locally reinforced elements

  14. Effect of Ceramic Thickness and Luting Agent Shade on the Color Masking Ability of Laminate Veneers

    OpenAIRE

    Begum, Zubeda; Chheda, Pratik; Shruthi, C. S.; Sonika, Radhika

    2014-01-01

    The main objective of the study was to recognize the effect of ceramic thickness and luting agent on the extent to which the restoration masks color variations that may be present in the underlying dental structure. Two pressable ceramics were used: Lithium disilicate reinforced (IPS e.max- Ivoclar Vivadent) and Leucite reinforced (Cergo- Dentsply). Fifteen ceramic discs were manufactured from each ceramic and divided into three groups, according to the thickness (0.5, 1, 1.5 mm). To simulate...

  15. Fabrication of transparent ceramics using nanoparticles

    Science.gov (United States)

    Cherepy, Nerine J; Tillotson, Thomas M; Kuntz, Joshua D; Payne, Stephen A

    2012-09-18

    A method of fabrication of a transparent ceramic using nanoparticles synthesized via organic acid complexation-combustion includes providing metal salts, dissolving said metal salts to produce an aqueous salt solution, adding an organic chelating agent to produce a complexed-metal sol, heating said complexed-metal sol to produce a gel, drying said gel to produce a powder, combusting said powder to produce nano-particles, calcining said nano-particles to produce oxide nano-particles, forming said oxide nano-particles into a green body, and sintering said green body to produce the transparent ceramic.

  16. Effect of ageing on the mechanical behaviour of aluminium alloy AA2009 reinforced with SIC particles; Influencia del estado de envejecimiento en el comportamiento mecanico de una aleacion de aluminio AA2009 reforzada con particulas de SiC

    Energy Technology Data Exchange (ETDEWEB)

    Rodrigo, P.; Poza, P.; Utrilla, M. v.; Urena, A.

    2005-07-01

    A study of the mechanical behaviour of an aluminium matrix composite (AA2009) reinforced with 15 volume percent of SiC particles has been carried out. The ageing kinetic for this material has been evaluated at two different ageing temperatures (170 and 190 degree centigree). The hardness peaks for the two different precipitation sequences existing in the matrix alloy have been identified. The mechanical behaviour of the composite was also evaluated for the different thermal conditions (as-received and aged). This research has been completed with the identification of the fracture mechanisms by means of observation with scanning electron microscopy (SEM) both of the fracture surface and transversal sections of them. In addition, transmission electron microscopy (TEM) of the treated composites has been used to determine the influence of the SiC particles on the distribution of strengthening phases precipitated in the matrix. (Author) 14 refs.

  17. 多层喷射沉积颗粒增强铝基复合材料的研究现状与发展趋势%Current State and Developing Trends of Multiinlayer Spray Deposited Aluminium Matrix Composites Reinforced with Particles

    Institute of Scientific and Technical Information of China (English)

    贺毅强; 陈志钢

    2012-01-01

    Multi-layer spray deposition technology employed to make particle reinforced aluminum matrix composites can promote the effect of fast cooling, refine and homogenize microstructure, narrow the particle size distribution and optimize the particles and matrix bonding. In this paper, the current situations of R~D of spray deposited aluminum matrix composites, the principles and processing parameters of multi-layer spray deposition are reviewed. The developments of spray deposited A1-Zn-Mg, A1-Fe and A1-Si matrix composites are summarized. Densification methods for spray deposited aluminum matrix composites, especially novel methods including wedge pressing, cage rolling, ceramics rolling, and hot pressing for bulk preform compacted on a light tonnage equipment are emphasized. Developing trends of multi-layer spray deposited aluminum matrix composites are also presented. It is Considered that the bonding of the interface between the reinforcement particles and the aluminum matrix needs to be optimized. Multi-layer spray deposition has been invented to preparing bulk parts with uniform and high density in a programmable control. Densifieation methods are also developed towards light tonnage compact bulk preform. And the forming ability of the bulk deposits can be enhanced effectively by hot and wedge pressing, and then benefitting the deformation in next step.%通过多层喷射沉积技术制备颗粒增强铝基复合材料,强化了冷却效果,能获得细小均匀的显微组织,优化复合材料中增强相的分布及其与基体的结合状态。本文综述了喷射沉积颗粒增强铝基复合材料的发展现状;介绍了多层喷射沉积技术的原理与工艺参数;概述了喷射沉积颗粒增强Al-Zn—Mg系、Al—Fe系与Al-Si系复合材料;并介绍喷射沉积颗粒增强铝基复合材料的致密化技术,着重介绍在小吨位设备上致密大块多孔材料的楔形压制工艺、外框限制轧制、陶粒包覆轧制工

  18. 激光熔注中增强相颗粒对晶粒生长影响的CA模拟∗%Simulation of effect of reinforcement particles on grain growth during laser melt inj ection based on CA

    Institute of Scientific and Technical Information of China (English)

    赵明娟; 邓志成; 赵龙志

    2015-01-01

    基于元胞自动机法,结合 Moore 型邻居定义和晶粒生长理论,建立了增强相颗粒 SiC 对镁合金激光熔注中表层316L不锈钢晶粒生长的影响模型,模型考虑了晶界迁移率和晶界能等因素,实现了不同增强相颗粒体积分数和颗粒尺寸对晶粒生长影响的计算机模拟.结果表明,所建立的模型能较好的模拟晶粒生长过程,所得晶粒生长指数为0.42;增强相颗粒体积分数含量越高,晶粒生长越慢,晶粒尺寸越小;增强相颗粒尺寸越小,晶粒生长的越慢,晶粒尺寸越小,组织越均匀.%Based on the cellular automaton method,the definition of Moore neighbor type and the grain growth theory,a model of simulation for the grain growth process was established,which simulated the influence of the SiC reinforcement particles and 316L stainless steel reinforced the surface of magnesium alloy by laser melt inj ection.Many factors such as grain boundary mobility and grain boundary energy were considered in the mod-el.Simulated the influence of different volume fraction and size of reinforcement particles on the grain growth process were obtained.The results show that:the grain growth process can be simulated very well by the meth-od,the grain growth index can be obtained as 0.42;the higher volume fraction of the particles,the slower the speed of the grain growth,the smaller grain size;the smaller the particles size is,the slower the grain grows, the smaller grain size and the microstructure is more uniform.

  19. Recycled ABS Resin Toughened and Reinforced by Elastomer/Inorganic Nano-Particle Composite System%弹性体/无机纳米粒子复合体系增强增韧回收ABS树脂

    Institute of Scientific and Technical Information of China (English)

    孔雪松

    2013-01-01

    The toughening of elastomer and inorganic nano-particle to recycled ABS was studied respectively.The results show that elastomer restores the toughness of recycles ABS,but leads to decrease of rigidity,meanwhile inorganic nano-particle can increase the toughness partly,also leads to increases of rigidity.Finally recycled ABS is modified by elastomer/inorganic nano-particle composite system.When 5%~8% ABS rubber powder and 2% ~3% inorganic particle are added,the recycled ABS resin is toughened and reinforced.%分别研究了弹性体和无机纳米粒子对回收丙烯腈-丁二烯-苯乙烯共聚物(ABS)的增韧.结果表明:弹性体能使回收ABS树脂的韧性得到恢复,但导致刚性下降;无机纳米粒子对ABS树脂的增韧能力有限,但能增加ABS的刚性.最后采用弹性体/无机纳米粒子复合体系改性回收ABS树脂,添加质量分数5%~8%的高胶粉和质量分数2%~3%无机纳米粒子时,实现了对回收ABS树脂的增强增韧.

  20. Thermal Expansion of Sintered Glass Ceramics in the System BaO-SrO-ZnO-SiO2 and Its Dependence on Particle Size.

    Science.gov (United States)

    Thieme, Christian; Schlesier, Martin; Bocker, Christian; Buzatto de Souza, Gabriel; Rüssel, Christian

    2016-08-10

    The thermal expansion behavior of sintered glass-ceramics containing high concentrations of Ba1-xSrxZn2Si2O7, a phase with very low and highly anisotropic thermal expansion behavior, was investigated. The observed phase has the crystal structure of the high-temperature phase of BaZn2Si2O7, which can be stabilized by the introduction of Sr(2+) into this phase. The high anisotropy leads to microcracking within the volume of the samples, which strongly affects the dilatometric thermal expansion. However, these cracks also have an influence on the nominal thermal expansion of the as-mentioned phase, which decreases if the cracks appear. Below a grain size of approximately 80 μm, the sintered glass-ceramics have almost no cracks and show positive thermal expansion. Hence, coefficients of thermal expansion between -5.6 and 6.5 × 10(-6) K(-1) were measured. In addition to dilatometric studies, the effect of the microstructure on the thermal expansion was also measured using in situ X-ray diffraction at temperatures up to 1000 °C. PMID:27433854

  1. Thermal Expansion of Sintered Glass Ceramics in the System BaO-SrO-ZnO-SiO2 and Its Dependence on Particle Size.

    Science.gov (United States)

    Thieme, Christian; Schlesier, Martin; Bocker, Christian; Buzatto de Souza, Gabriel; Rüssel, Christian

    2016-08-10

    The thermal expansion behavior of sintered glass-ceramics containing high concentrations of Ba1-xSrxZn2Si2O7, a phase with very low and highly anisotropic thermal expansion behavior, was investigated. The observed phase has the crystal structure of the high-temperature phase of BaZn2Si2O7, which can be stabilized by the introduction of Sr(2+) into this phase. The high anisotropy leads to microcracking within the volume of the samples, which strongly affects the dilatometric thermal expansion. However, these cracks also have an influence on the nominal thermal expansion of the as-mentioned phase, which decreases if the cracks appear. Below a grain size of approximately 80 μm, the sintered glass-ceramics have almost no cracks and show positive thermal expansion. Hence, coefficients of thermal expansion between -5.6 and 6.5 × 10(-6) K(-1) were measured. In addition to dilatometric studies, the effect of the microstructure on the thermal expansion was also measured using in situ X-ray diffraction at temperatures up to 1000 °C.

  2. Processes for fabricating composite reinforced material

    Energy Technology Data Exchange (ETDEWEB)

    Seals, Roland D.; Ripley, Edward B.; Ludtka, Gerard M.

    2015-11-24

    A family of materials wherein nanostructures and/or nanotubes are incorporated into a multi-component material arrangement, such as a metallic or ceramic alloy or composite/aggregate, producing a new material or metallic/ceramic alloy. The new material has significantly increased strength, up to several thousands of times normal and perhaps substantially more, as well as significantly decreased weight. The new materials may be manufactured into a component where the nanostructure or nanostructure reinforcement is incorporated into the bulk and/or matrix material, or as a coating where the nanostructure or nanostructure reinforcement is incorporated into the coating or surface of a "normal" substrate material. The nanostructures are incorporated into the material structure either randomly or aligned, within grains, or along or across grain boundaries.

  3. Porosity and mechanical properties of zirconium ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Buyakova, S., E-mail: sbuyakova@ispms.tsc.ru; Kulkov, S. [Tomsk State University (Russian Federation); Tomsk Polytechnic University (Russian Federation); Institute of Strength Physics and Materials Science RAS (Russian Federation); Sablina, T. [Institute of Strength Physics and Materials Science RAS (Russian Federation)

    2015-11-17

    Has been studied a porous ceramics obtained from ultra-fine powders. Porous ceramic ZrO{sub 2}(MgO), ZrO{sub 2}(Y{sub 2}O{sub 3}) powder was prepared by pressing and subsequent sintering of compacts homologous temperatures ranging from 0.63 to 0.56 during the isothermal holding duration of 1 to 5 hours. The porosity of ceramic samples was from 15 to 80%. The structure of the ceramic materials produced from plasma-sprayed ZrO{sub 2} powder was represented as a system of cell and rod structure elements. Cellular structure formed by stacking hollow powder particles can be easily seen at the images of fracture surfaces of obtained ceramics. There were three types of pores in ceramics: large cellular hollow spaces, small interparticle pores which are not filled with powder particles and the smallest pores in the shells of cells. The cells generally did not have regular shapes. The size of the interior of the cells many times exceeded the thickness of the walls which was a single-layer packing of ZrO{sub 2} grains. A distinctive feature of all deformation diagrams obtained in the experiment was their nonlinearity at low deformations which was described by the parabolic law. It was shown that the observed nonlinear elasticity for low deformation on deformation diagrams is due to mechanical instability of the cellular elements in the ceramic carcass.

  4. Porosity and mechanical properties of zirconium ceramics

    Science.gov (United States)

    Buyakova, S.; Sablina, T.; Kulkov, S.

    2015-11-01

    Has been studied a porous ceramics obtained from ultra-fine powders. Porous ceramic ZrO2(MgO), ZrO2(Y2O3) powder was prepared by pressing and subsequent sintering of compacts homologous temperatures ranging from 0.63 to 0.56 during the isothermal holding duration of 1 to 5 hours. The porosity of ceramic samples was from 15 to 80%. The structure of the ceramic materials produced from plasma-sprayed ZrO2 powder was represented as a system of cell and rod structure elements. Cellular structure formed by stacking hollow powder particles can be easily seen at the images of fracture surfaces of obtained ceramics. There were three types of pores in ceramics: large cellular hollow spaces, small interparticle pores which are not filled with powder particles and the smallest pores in the shells of cells. The cells generally did not have regular shapes. The size of the interior of the cells many times exceeded the thickness of the walls which was a single-layer packing of ZrO2 grains. A distinctive feature of all deformation diagrams obtained in the experiment was their nonlinearity at low deformations which was described by the parabolic law. It was shown that the observed nonlinear elasticity for low deformation on deformation diagrams is due to mechanical instability of the cellular elements in the ceramic carcass.

  5. 无压浸渗法制备氧化态SiC颗粒增强铝基复合材料%Fabrication of Oxidized SiC Particles Reinforced Aluminum Matrix Composite by Pressureless Infiltration Technique

    Institute of Scientific and Technical Information of China (English)

    张强; 姜龙涛; 武高辉

    2012-01-01

    The oxidation behavior of SiC particles in the temperature range from l000℃ to 1200℃ was investi-gated. The dependence of weight gain and oxidation time was parabolic and the oxidation behavior was controlled by diffusion process, with a oxidation activation energy of 219 kJ/mol. Using oxidized SiC particles as reinforce-ment and aluminum alloy containing Si and Mg as matrix, a SiCp/Al composite was fabricated by pressureless infil-tration technique. The microstructure and interfacial morphology were analyzed and the pressureless infiltration mechanisms were discussed. The particles were distributed uniformly in the composite, without particles agglom-eration. Interfacial reactions were found in the composite and the product was identified as MgAl2O4, formed by the reactions between surface oxide layer of SiC particles and Mg, Al in the matrix. The interfacial reactions enhanced the wettability and promoted the spontaneous infiltration process.%研究了SiC颗粒在1000~1200℃的氧化行为,其氧化增重率与保温时间符合抛物线规律,氧化增重受扩散过程控制,氧化激活能为219 kJ/mol.采用预氧化处理的SiC颗粒为增强体,含Si、Mg的铝合金为基体,通过无压浸渗方法制备了SiCp/Al复合材料,分析了复合材料的微观组织与界面形貌,探讨了无压浸渗机理.复合材料中颗粒分布均匀,无偏聚现象.材料制备过程中存在界面反应,SiC颗粒表面的氧化层与铝合金中的Mg、Al反应形成了一定数量的MgAl2O4.界面反应的存在提高了润湿性,促进了无压自发浸渗.

  6. Fretting wear damage-I: numerical study of composite steel sheets reinforced with TiB2

    Directory of Open Access Journals (Sweden)

    F. Ayari

    2011-09-01

    Full Text Available Purpose: of this paper is based on the damage analysis by fretting wearing occurred on the composite steel sheets reinforced with TiB2 ceramic particles. There is a real lack to find a reliable data and detail research in literature that makes the purpose of this manuscript.Design/methodology/approach: Fretting is a surface degradation process in which removal of material is induced by small amplitude oscillatory movement between contacting components, such as flexible coupling joint structures etc. The main parameters affecting fretting wear are reported to be normal load, slip amplitude, frequency of the oscillatory movement, contact geometry, surface roughness and material properties. In this study, a finite element-based method is presented for simulating the contact of a rigid cylinder on flat fretting wear for the composite steel sheets reinforced with TiB2 ceramic particles.Findings: The general purpose commercial code ABAQUS was employed; this model can be used to facilitate generalization of the present approach to more complex applications. In this study a particular mesh technique was used to optimize the computation time, especially when dynamic analysis is used. In fact, two-dimensional, four-node, plane strain (linear elements are employed throughout. The mesh (element size in the contact area is very fine to capture the complicated variation of the surface and subsurface stresses and relative slip. The contact surface is constituted with a rigid hard steel cylinder material and a flat plate of composite steel sheets reinforced with TiB2 ceramic particles.Practical implications: This manuscript concerns a typical contact with the cylindrical plan geometry as it models the major problems and also stress distribution due to the contact was well defined. Our assembly is then, composed with a cylindrical contact with a plan substrate. An elastic - plastic analysis of fretting stress using a finite element ABAQUS is enhanced. The

  7. Preparation of Iron Matrix Composite Reinforced by In-situ Al203 Particles%自生氧化铝颗粒增强铁基复合材料的制备

    Institute of Scientific and Technical Information of China (English)

    周玉成; 魏世忠; 王利敏; 徐流杰

    2011-01-01

    Ethanol was used as reaction media, the ammonia was slowly dropped, constantly stirring into aluminum nitrate ethanol solution to neutralize. By washing with ethanol, filtering and drying, some aluminum hydroxide was obtained. Aluminum hydroxide powder and iron powder, in a certain proportion, were fully mixed. By pressing and sintering, iron matrix composite reinforced with in-situ A12O3 particle was prepared.%采用乙醇作为反应介质,将氨水滴入硝酸铝乙醇溶液中进行中和反应,经洗涤、过滤和烘干后得到氢氧化铝超细粉.将制得的超细氢氧化铝粉与铁粉按一定比例充分混合,经压制、烧结制得氧化铝颗粒增强铁基复合材料.

  8. The synthesis and applications of nano sized ceramic membranes

    International Nuclear Information System (INIS)

    Inorganic membranes composed of particles having sizes below 50 A were produced with oxides of TiO2, ZrO2, and SiO2. This presentation stresses the necessary physical chemical phenomena associated with the particle synthesis and the aggregation behavior of these particles as they are incorporated into the final membrane body. Uses of ceramic membranes in separations, ceramic membrane reactors, and the photocatalytic degradation of organic waste materials are briefly reviewed

  9. Basal Reinforced Piled Embankments

    NARCIS (Netherlands)

    Van Eekelen, S.J.M.

    2015-01-01

    A basal reinforced piled embankment consists of a reinforced embankment on a pile foundation. The reinforcement consists of one or more horizontal layers of geosynthetic reinforcement (GR) installed at the base of the embankment. The design of the GR is the subject of this thesis. A basal reinforce

  10. Impact Behavior of Three Notched All-Ceramic Restorations after Soaking in Artificial Saliva

    OpenAIRE

    Min Yan; Chung-Kai Wei; Yuh-Yih Lin; Suh-Woan Hu; Shinn-Jyh Ding

    2015-01-01

    Biomechanics play a critical role in influencing the clinical applications of all-ceramic dental restorations. The restorative biomaterials have to demonstrate mechanical durability in the oral environment because they are always exposed to a variety of oral environments. This study was designed to evaluate the effect of soaking time, notch and saliva pH values on the impact energy of three commonly used all-ceramic materials for CAD/CAM. The leucite-reinforced glass ceramic (ProCAD), lithiu...

  11. CAD/CAM fabricated single-unit all-ceramic post–core–crown restoration

    OpenAIRE

    Thilla Sekar Vinothkumar; Deivanayagam Kandaswamy; Pallavi Chanana

    2011-01-01

    This case report explains about an innovative treatment strategy for the management of damaged anterior teeth with reduced incisal clearance by means of a single-unit all-ceramic post-core-crown zirconia ceramic restoration fabricated by Computer-aided designing and computer-aided manufacturing (CAD/CAM) technology. The reinforced zirconia ceramics allow fabrication of durable esthetic restorations in cases with high functional loading and the unification of the post, core, and crown in a sin...

  12. Dental ceramics: An update

    OpenAIRE

    Shenoy Arvind; Shenoy Nina

    2010-01-01

    In the last few decades, there have been tremendous advances in the mechanical properties and methods of fabrication of ceramic materials. While porcelain-based materials are still a major component of the market, there have been moves to replace metal ceramics systems with all ceramic systems. Advances in bonding techniques have increased the range and scope for use of ceramics in dentistry. In this brief review, we will discuss advances in ceramic materials and fabrication techniques. Examp...

  13. High elastic modulus nanopowder reinforced resin composites for dental applications

    Science.gov (United States)

    Wang, Yijun

    2007-12-01

    Dental restorations account for more than $3 billion dollars a year on the market. Among them, all-ceramic dental crowns draw more and more attention and their popularity has risen because of their superior aesthetics and biocompatibility. However, their relatively high failure rate and labor-intensive fabrication procedure still limit their application. In this thesis, a new family of high elastic modulus nanopowder reinforced resin composites and their mechanical properties are studied. Materials with higher elastic modulus, such as alumina and diamond, are used to replace the routine filler material, silica, in dental resin composites to achieve the desired properties. This class of composites is developed to serve (1) as a high stiffness support to all-ceramic crowns and (2) as a means of joining independently fabricated crown core and veneer layers. Most of the work focuses on nano-sized Al2O3 (average particle size 47 nm) reinforcement in a polymeric matrix with 50:50 Bisphenol A glycidyl methacrylate (Bis-GMA): triethylene glycol dimethacrylate (TEGDMA) monomers. Surfactants, silanizing agents and primers are examined to obtain higher filler levels and enhance the bonding between filler and matrix. Silane agents work best. The elastic modulus of a 57.5 vol% alumina/resin composite is 31.5 GPa compared to current commercial resin composites with elastic modulus alumina, diamond/resin composites are studied. An elastic modulus of about 45 GPa is obtained for a 57 vol% diamond/resin composite. Our results indicate that with a generally monodispersed nano-sized high modulus filler, relatively high elastic modulus resin-based composite cements are possible. Time-dependent behavior of our resin composites is also investigated. This is valuable for understanding the behavior of our material and possible fatigue testing in the future. Our results indicate that with effective coupling agents and higher filler loading, viscous flow can be greatly decreased due to the

  14. Glasses, ceramics, and composites from lunar materials

    Science.gov (United States)

    Beall, George H.

    1992-01-01

    A variety of useful silicate materials can be synthesized from lunar rocks and soils. The simplest to manufacture are glasses and glass-ceramics. Glass fibers can be drawn from a variety of basaltic glasses. Glass articles formed from titania-rich basalts are capable of fine-grained internal crystallization, with resulting strength and abrasion resistance allowing their wide application in construction. Specialty glass-ceramics and fiber-reinforced composites would rely on chemical separation of magnesium silicates and aluminosilicates as well as oxides titania and alumina. Polycrystalline enstatite with induced lamellar twinning has high fracture toughness, while cordierite glass-ceramics combine excellent thermal shock resistance with high flexural strengths. If sapphire or rutile whiskers can be made, composites of even better mechanical properties are envisioned.

  15. The compression strength investigations of AW-AlCu4Mg2Mn alloy based composites reinforced with SiC particles

    Directory of Open Access Journals (Sweden)

    A. Kurzawa

    2011-04-01

    Full Text Available In this paper strength tests of composite materials based on AW-AlCu4Mg2Mn obtained in uniaxial compression test was studied.Materials used for examination were made from AW-AlCu4Mg2Mn alloy and porous preforms of SiC particles (grain size 6÷10μm bypressure infiltration (squeeze casting. The stress-strain curves of the materials with 10% vol., 20% vol., 30% vol. particles of SiC, as well unreinforcement alloy and microstructure of scrap surface samples in a plane parallel to the compressive force were analyzed. The investigated metal matrix composites are characterized by marked reduced the plastic strain values with increasing particle strengthening while the unreinforcement materials throughout the range of deformation show considerable plasticity. In the case of the material containing 10% vol of SiC the plastic strain is a slight strengthening of the material. With increasing of the particle content the plasticity decreases. Materials with 20%vol and 30%vol of SiC particles were brittle cracked at much higher values of stress σ.

  16. Durabilidade de peças cerâmicas vermelhas com adição de rejeito de rocha ornamental isenta de granalha Durability of red ceramic samples with addition of ornamental rock waste free of steel particles

    Directory of Open Access Journals (Sweden)

    D. V. Rodrigues

    2012-09-01

    Full Text Available Para avaliação da degradação acelerada em laboratório sofrida pelos corpos de prova de cerâmica vermelha com adição de rejeito de rocha ornamental isento de granalha, foi utilizado um equipamento que lixivia com água quente e fria em tempos controlados, e também, congela a amostra em até -4 ºC. Os corpos de prova cerâmicos foram confeccionados com até 10% em massa de rejeito de rocha ornamental a seco, e em seguida, umedecidos e moldados por extrusão. Os materiais produzidos foram calcinados nas temperaturas de 700 ºC, 800 ºC e 900 ºC. Após 1060 h de degradação acelerada em equipamento de laboratório, analisaram-se as propriedades cerâmicas do material. Os resultados das resistências mecânicas foram comparados através da distribuição de Weibull, antes e depois da degradação. Nota-se que o material com adição de 10% de rejeito de rocha ornamental na massa cerâmica é mais confiável quando queimada a 900 ºC após a degradação, quando comparados com as amostras sem adição de rejeito, proporcionando maior durabilidade.For the evaluation of the accelerated degradation in laboratory of red ceramic specimens with addition of ornamental rock waste free from steel particles, an equipment that leach with hot and cool water and time control, and also freezing the specimen at -4 ºC was used,. The ceramic samples were made with up to 10 wt.% of the dry ornamental rock waste, and after humidifying and molding by extrusion. The specimens were fired at 700 ºC, 800 ºC and 900 ºC. After 1060 h of accelerated degradation lab test, ceramic properties were evaluated. The results of the strength were compared for Weibull distribution, before and after degradation. The specimens with addition of 10 wt.% waste is more durable and reliable when fired to 900 ºC after the degradation.

  17. DC conductivity of silicon nitride based carbon-ceramic composites

    Directory of Open Access Journals (Sweden)

    B. Fényi

    2007-12-01

    Full Text Available The silicon nitride ceramics are usually known as strongly refractory and enduring materials and have typical electrically insulating properties. If the reinforcing phase of ceramic composite (that is mainly put in the material to improve mechanical properties is a good electrical conductor, it is worth to investigate the composite in electrical aspect. In this work carbon nanotubes, black-carbon and graphite were added to the basic silicon nitride ceramic and the electrical conductivity of the prepared carbon-ceramic composites was determined. The conductivity of the ceramic composites with different type and concentration of the carbon additives was observed by applying four point DC resistance measurements. Insulator and conductor composites in a wide conductivity range can be produced depending on the type and quantity of the additives. The additive types as well as the sintering parameters have influence on the basic electrical properties of the conductor composites.

  18. Fundamental alloy design of oxide ceramics and their composites

    Energy Technology Data Exchange (ETDEWEB)

    Chen, I.W.

    1992-01-01

    The main research was on microstructural development of oxide ceramics. Projects were completed and the publications given. Abstracts are given on: Reactive CeO[sub 2]powders by homogeneous precipitation, SiC whisker-reinforced lithium aluminosilicate composite, solute drag on grain boundary in ionic solids (space charge effect), in-situ alumina/aluminate platelet composites, exaggerated texture and grain growth of superplastic silicon nitride (SiAlON), hot extrusion of ceramics, control of grain boundary pinning in Al[sub 2]O[sub 3]/ZrO[sub 2] composites with Ce[sup 3+]/Ce[sup 4+] doping, superplastic forming of ceramic composites, computer simulation of final stage sintering (model, kinetics, microstructure, effect of initial pore size), development of superplastic structural ceramics, and superplastic flow of two-phase ceramics containing rigid inclusions (zirconia/mullite composites). A proposed research program is outlined: materials, solute drag, densification and coarsening, and grain boundary electrical behavior.

  19. Dual-nanoparticulate-reinforced aluminum matrix composite materials

    Science.gov (United States)

    Kwon, Hansang; Cho, Seungchan; Leparoux, Marc; Kawasaki, Akira

    2012-06-01

    Aluminum (Al) matrix composite materials reinforced with carbon nanotubes (CNT) and silicon carbide nanoparticles (nano-SiC) were fabricated by mechanical ball milling, followed by hot-pressing. Nano-SiC was used as an active mixing agent for dispersing the CNTs in the Al powder. The hardness of the produced composites was dramatically increased, up to eight times higher than bulk pure Al, by increasing the amount of nano-SiC particles. A small quantity of aluminum carbide (Al4C3) was observed by TEM analysis and quantified using x-ray diffraction. The composite with the highest hardness values contained some nanosized Al4C3. Along with the CNT and the nano-SiC, Al4C3 also seemed to play a role in the enhanced hardness of the composites. The high energy milling process seems to lead to a homogeneous dispersion of the high aspect ratio CNTs, and of the nearly spherical nano-SiC particles in the Al matrix. This powder metallurgical approach could also be applied to other nanoreinforced composites, such as ceramics or complex matrix materials.

  20. Effect of the percentage of reinforcement on the wear in the metal matrix composites sintered with abnormal glow discharge

    International Nuclear Information System (INIS)

    In this study an analysis of the behavior of dry wear coefficient of a Metal Matrix Composite (MMC) in 316 stainless steel reinforced with particles of titanium carbide (TiC) according to ASTM G 99 standards, in a pin-on-disk test. In this research it is tested the effect of the percentage of reinforcement in the MMC manufactured with 3, 6 y 9% (vol.) of TiC, in samples compacted at 800 MPa, generating different values of grain size, hardness and density, they are sintered with abnormal glow discharge, at a temperature of 1200 degree centigrade ±5 degree centigrade, with a protection atmosphere H2 - N2 and a permanence time of 30 minutes. According to the results obtained it is concluded that the best condition for the MMC manufacturing, in relation to the reinforcement percentage, is the one obtained when the mixture contains 6% of TiC compacted at 800 MPa. In these conditions, it was obtained: achieving smaller grain size, the greater hardness and the lowest coefficient of friction. In this respect, it was observed that the incorporation of the ceramic particles (TiC) in a matrix of austenitic steel (316) shows significant improvements in the resistance to the wear. (Author)

  1. Reinforcement effect of biomass carbon and protein in elastic biocomposites

    Science.gov (United States)

    Biomass carbon and soy protein were used to reinforce natural rubber biocomposites. The particle size of biomass carbon were reduced and characterized with elemental analysis, x-ray diffraction, infrared spectroscopy, and particle size analysis. The rubber composite reinforced with the biomass carbo...

  2. Radiation Effects in Nuclear Ceramics

    Directory of Open Access Journals (Sweden)

    L. Thomé

    2012-01-01

    Full Text Available Due to outstanding physicochemical properties, ceramics are key engineering materials in many industrial domains. The evaluation of the damage created in ceramics employed in radiative media is a challenging problem for electronic, space, and nuclear industries. In this latter field, ceramics can be used as immobilization forms for radioactive wastes, inert fuel matrices for actinide transmutation, cladding materials for gas-cooled fission reactors, and structural components for fusion reactors. Information on the radiation stability of nuclear materials may be obtained by simulating the different types of interactions involved during the slowing down of energetic particles with ion beams delivered by various types of accelerators. This paper presents a review of the radiation effects occurring in nuclear ceramics, with an emphasis on recent results concerning the damage accumulation processes. Energetic ions in the KeV-GeV range are used to explore the nuclear collision (at low energy and electronic excitation (at high energy regimes. The recovery by electronic excitation of the damage created by ballistic collisions (SHIBIEC process is also addressed.

  3. Effect of Ceramic Thickness and Luting Agent Shade on the Color Masking Ability of Laminate Veneers.

    Science.gov (United States)

    Begum, Zubeda; Chheda, Pratik; Shruthi, C S; Sonika, Radhika

    2014-12-01

    The main objective of the study was to recognize the effect of ceramic thickness and luting agent on the extent to which the restoration masks color variations that may be present in the underlying dental structure. Two pressable ceramics were used: Lithium disilicate reinforced (IPS e.max- Ivoclar Vivadent) and Leucite reinforced (Cergo- Dentsply). Fifteen ceramic discs were manufactured from each ceramic and divided into three groups, according to the thickness (0.5, 1, 1.5 mm). To simulate the color of a dark underlying dental structure, background discs, color C3, with 20 mm diameter, were made using resin composite. The ceramic discs with varying thicknesses were seated on the dark background of the resin composite with either resinous opaque cement or resinous cement. The color parameters were determined by the CIE Lab system of colors using a spectrophotometer and color differences (ΔE) were calculated. The results were then statistically analyzed, using ANOVA test and Tukey HSD test. The ΔE values of both ceramic systems were affected by both the luting agent and the ceramic thickness (P veneers, higher values in the color parameters were obtained for both ceramic materials. The color masking ability of ceramics used for laminate veneers is significantly affected by the thickness of the ceramic and the shade of the luting agent used. PMID:26199491

  4. INVESTIGATION OF MULTIPHASE-REINFORCED Si3N4 COMPOSITE MATERIAL

    Institute of Scientific and Technical Information of China (English)

    曾鸣; 丁博; 郭梦熊

    1995-01-01

    By means of whisker reinforce and paricle dispersion, the routes of property improvement on Si3N4 ceramic material have been studied. The mecihaniacl properties of Siw/Si3N4 and Siw/Si3N4TiC material was compared, which proved that multiphase reinforce had overlap effect. Microstructure of the material was investigated by means of SEM and the mechanisms of SiCw and TiCP reinforces had been disussed.

  5. Effect of airborne particle abrasion protocols on surface topography of Y-TZP ceramic Efeito do protocolo de jateamento com partículas na topografia da superfície de uma cerâmica Y-TZP

    Directory of Open Access Journals (Sweden)

    J. R. C. Queiroz

    2012-06-01

    Full Text Available This study aimed to evaluate Y-TZP surface after different airborne particle abrasion protocols. Seventy-six Y-TZP ceramic blocks (5×4×4 mm³ were sintered and polished. Specimens were randomly divided into 19 groups (n=4 according to control group and 3 factors: a protocol duration (2 and 4 s; b particle size (30 µm, alumina coated silica particle; 45 µm, alumina particle; and 145 µm, alumina particle and; c pressure (1.5, 2.5 and 4.5 bar. Airborne particle abrasion was performed following a strict protocol. For qualitative and quantitative results, topography surfaces were analyzed in a digital optical profilometer (Interference Microscopic, using different roughness parameters (Ra, Rq, Rz, X-crossing, Mr1, Mr2 and Sdr and 3D images. Surface roughness also was analyzed following the primer and silane applications on Y-TZP surfaces. One-way ANOVA revealed that treatments (application period, particle size and pressure of particle blasting provided significant difference for all roughness parameters. The Tukey test determined that the significant differences between groups were different among roughness parameters. In qualitative analysis, the bonding agent application reduced roughness, filing the valleys in the surface. The protocols performed in this study verified that application period, particle size and pressure influenced the topographic pattern and amplitude of roughness.O objetivo deste estudo foi avaliar a superfície de uma cerâmica à base de zircônia tetragonal estabilizada por ítria (Y-TZP após diferentes protocolos de jateamento com partículas. Setenta e seis blocos cerâmicos de Y-TZP (5 x 4 x 4 mm³ foram sinterizados e polidos. As amostras foram randomicamente divididas em 19 grupos (n=4 sendo um controle e 18 grupos utilizando 3 fatores: a tempo (2 e 4 s; b tamanho de partícula (30 µm - partículas de alumina revestida por sílica; 45 µm - partículas de alumina; 145 µm - partículas de alumina e; c pressão (1

  6. Preparation and Properties of Macroporous Silicon Nitride Ceramics by Gelcasting and Carbonthermal Reaction

    Institute of Scientific and Technical Information of China (English)

    Wen ZHANG; Hongjie WANG; Zhihao JIN

    2005-01-01

    Macroporous silicon nitride (Si3N4) ceramics with high strength, uniform structure and relatively high porosity were obtained by gelcasting and carbonthermal reaction in a two-step sintering technique. Microstructure and composition were investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction(XRD). Open porosity, pore size distribution and basic mechanical performance were measured by Archimedes method,mercury intrusion porosimetry and three-point bending methods, respectively. SEM and TEM results revealed that pores were formed by elongated β-Si3N4. SADP measurement proved the formation of SiC particles. The SiC granules were beneficial for the formation of high ratio elongated β-Si3N4, and at proper amount, they also acted as reinforcement phase. Thermodynamic analysis indicated that the mechanisms of the reactions were mainly associated with liquid-solid reaction and gas-liquid reaction.

  7. Microstructural and sliding wear behavior of SiC-particle reinforced copper matrix composites fabricated by sintering and sinter-forging processes

    OpenAIRE

    Mohammadmehdi Shabani; Mohammad Hossein Paydar; Reza Zamiri; Maryam Goodarzi; Mohammad Mohsen Moshksar

    2016-01-01

    Cu and Cu/SiCp composite compacts were prepared through sintering and sinter-forging processes. Influence of SiC particles and fabrication type on the tribological behavior of pure Cu and Cu/SiCp composites was investigated. Dry sliding wear tests represented that the sinter-forged Cu composite compacts with 60 vol.% SiC exhibit the lowest wear loss compared to other compacts. Moreover, the results indicated that applying compressive force during sintering process of Cu and Cu/SiCp compacts h...

  8. Ceramic Laser Materials

    Directory of Open Access Journals (Sweden)

    Guillermo Villalobos

    2012-02-01

    Full Text Available Ceramic laser materials have come a long way since the first demonstration of lasing in 1964. Improvements in powder synthesis and ceramic sintering as well as novel ideas have led to notable achievements. These include the first Nd:yttrium aluminum garnet (YAG ceramic laser in 1995, breaking the 1 KW mark in 2002 and then the remarkable demonstration of more than 100 KW output power from a YAG ceramic laser system in 2009. Additional developments have included highly doped microchip lasers, ultrashort pulse lasers, novel materials such as sesquioxides, fluoride ceramic lasers, selenide ceramic lasers in the 2 to 3 μm region, composite ceramic lasers for better thermal management, and single crystal lasers derived from polycrystalline ceramics. This paper highlights some of these notable achievements.

  9. Fatigue of dental ceramics

    OpenAIRE

    Zhang, Yu; Sailer, Irena; lawn, brian

    2013-01-01

    Clinical data on survival rates reveal that all-ceramic dental prostheses are susceptible to fracture from repetitive occlusal loading. The objective of this review is to examine the underlying mechanisms of fatigue in current and future dental ceramics

  10. The Reinforcement Hierarchy

    Science.gov (United States)

    Forness, Steven R.

    1973-01-01

    Reinforcement hierarchy implies movement along a continuum from top to bottom, from primitive levels of reinforcement to more sophisticated levels. Unless it is immediately obvious that a child cannot function without the use of lower-order reinforcers, we should approach him as though he responds to topmost reinforcers until he demonstrates…

  11. Tribo-Mechanical Properties of HVOF Deposited Fe3Al Coatings Reinforced with TiB2 Particles for Wear-Resistant Applications

    Directory of Open Access Journals (Sweden)

    Mahdi Amiriyan

    2016-02-01

    Full Text Available This study reveals the effect of TiB2 particles on the mechanical and tribological properties of Fe3Al-TiB2 composite coatings against an alumina counterpart. The feedstock was produced by milling Fe3Al and TiB2 powders in a high energy ball mill. The high-velocity oxy-fuel (HVOF technique was used to deposit the feedstock powder on a steel substrate. The effect of TiB2 addition on mechanical properties and dry sliding wear rates of the coatings at sliding speeds ranging from 0.04 to 0.8 m·s−1 and loads of 3, 5 and 7 N was studied. Coatings made from unreinforced Fe3Al exhibited a relatively high wear rate. The Vickers hardness, elastic modulus and wear resistance of the coatings increased with increasing TiB2 content in the Fe3Al matrix. The wear mechanisms strongly depended on the sliding speed and the presence of TiB2 particles but were less dependent on the applied load.

  12. Fabrication of A356 composite reinforced with micro and nano Al{sub 2}O{sub 3} particles by a developed compocasting method and study of its properties

    Energy Technology Data Exchange (ETDEWEB)

    Sajjadi, S.A., E-mail: sajjadi@um.ac.ir [Department of Materials Science and Metallurgical Engineering, Engineering Faculty, Ferdowsi University of Mashhad, Mashhad (Iran, Islamic Republic of); Torabi Parizi, M. [Department of Materials Science and Engineering, Saveh Branch, Islamic Azad University, Saveh (Iran, Islamic Republic of); Ezatpour, H.R. [Department of Materials Science and Metallurgical Engineering, Engineering Faculty, Ferdowsi University of Mashhad, Mashhad (Iran, Islamic Republic of); Sedghi, A. [Department of Materials Science and Metallurgical Engineering, Engineering Faculty, Imam Khomeini International University of Qazvin, Qazvin (Iran, Islamic Republic of)

    2012-01-15

    Highlights: > In the current research micro and nano-composites of A356/Al{sub 2}O{sub 3} were produced by compocasting method in various conditions. > The effects of different fabrication parameters on the microstructure and some physical and mechanical properties of the composites have been investigated. > The results revealed that application of the compocasting process leads to a transformation of a dendritic to a nondendritic structure of the matrix alloy. - Abstract: Aluminum/alumina composites are used in automotive and aerospace industries due to their low density and good mechanical strength. In this study, compocasting was used to fabricate aluminum-matrix composite reinforced with micro and nano-alumina particles. Different weight fractions of micro (3, 5 and 7.5 wt.%) and nano (1, 2, 3 and 4 wt.%) alumina particles were injected by argon gas into the semi-solid state A356 aluminum alloy and stirred by a mechanical stirrer with different speeds of 200, 300 and 450 rpm. The microstructure of the composite samples was investigated by Optical and Scanning Electron Microscopy. Also, density and hardness variation of micro and nano composites were measured. The microstructure study results revealed that application of compocasting process led to a transformation of a dendritic to a nondendritic structure of the matrix alloy. The SEM micrographs revealed that Al{sub 2}O{sub 3} nano particles were surrounded by silicon eutectic and inclined to move toward inter-dendritic regions. They were dispersed uniformly in the matrix when 1, 2 and 3 wt.% nano Al{sub 2}O{sub 3} or 3 and 5 wt.% micro Al{sub 2}O{sub 3} was added, while, further increase in Al{sub 2}O{sub 3} (4 wt.% nano Al{sub 2}O{sub 3} and 7.5 wt.% micro Al{sub 2}O{sub 3}) led to agglomeration. The density measurements showed that the amount of porosity in the composites increased with increasing weight fraction and speed of stirring and decreasing particle size. The hardness results indicated that the

  13. Ceramic art in sculpture

    OpenAIRE

    Rokavec, Eva

    2014-01-01

    Diploma seminar speaks of ceramics as a field of artistic expression and not just as pottery craft. I presented short overview of developing ceramic sculpture and its changing role. Clay inspires design and touch more than other sculpture media. It starts as early as in prehistory. Although it sometimes seems that was sculptural ceramics neglected in art history overview, it was not so in actual praxis. There is a rich tradition of ceramics in the East and also in Europe during the renaissanc...

  14. Ceramic Laser Materials

    OpenAIRE

    Guillermo Villalobos; Jasbinder Sanghera; Ishwar Aggarwal; Bryan Sadowski; Jesse Frantz; Colin Baker; Brandon Shaw; Woohong Kim

    2012-01-01

    Ceramic laser materials have come a long way since the first demonstration of lasing in 1964. Improvements in powder synthesis and ceramic sintering as well as novel ideas have led to notable achievements. These include the first Nd:yttrium aluminum garnet (YAG) ceramic laser in 1995, breaking the 1 KW mark in 2002 and then the remarkable demonstration of more than 100 KW output power from a YAG ceramic laser system in 2009. Additional developments have included highly doped microchip lasers,...

  15. Estructura y propiedades del material compuesto de base cobre reforzado con partículas intermetálicas de TiB2. // Structure and properties of copper base reinforced with intermetallic particles of TiB2 material.

    Directory of Open Access Journals (Sweden)

    M. López J.

    2002-09-01

    copper base reinforced alloy by means ofdispersion of TiB2 intermetalic ceramic is carried out. The copper-ceramic mechanical mixture was obtainedalloying powdered copper of 140 mm size with 1% and 2% of TiB2 in volume, dispers e in a planetary mill ofmartens itic stainless of high energy, with 12 and 36 hours milling in argon atmosphere using reason ofbolls/mass load in 10:1 powder. The powdered alloy consolidation was carried out in two stages.The objective of the study, is to investigate the evolution of mechanical and electric properties associated tomicroestructure changes taken place by compactacion process and hot lamination.Key words. Copper alloy, mechanical properties, microestructure, hot rolling.

  16. Al-Ti Particulate Composite: Processing and Studies on Particle Twinning, Microstructure, and Thermal Stability

    Science.gov (United States)

    Yadav, Devinder; Bauri, Ranjit; Kauffmann, Alexander; Freudenberger, Jens

    2016-08-01

    The present investigation shows that alternate to the ceramic particles, hard metallic particles can be used as reinforcement in an aluminum matrix to achieve a good strength-ductility combination in a composite. Titanium particles were incorporated into aluminum by friction stir processing (FSP) to process an Al-Ti particulate composite. FSP led to uniform distribution of the particles in the stir zone without any particle-matrix reaction, thereby retaining the particles in their elemental state. Fracture and twinning of the Ti particles with different frequency of occurrence on the advancing and retreating sides of the stir zone was observed. Twinning of the particles was studied by focused ion beam-assisted transmission electron microscopy. The processed Al-Ti composite exhibited a significant improvement in strength and also retained appreciable amount of ductility. The thermal stability of the fine-grained structure against abnormal grain growth (AGG) was improved by the Ti particles. The AGG in the Al-Ti composite occurred at 713 K (440 °C) compared to 673 K (400 °C) in the unreinforced aluminum processed under the same conditions. On the other hand, the particle-matrix reaction occurred only at 823 K (550 °C), and hence the Ti particles were thermally more stable compared to the matrix grain structure.

  17. Fiber-reinforced composites in fixed partial dentures

    Directory of Open Access Journals (Sweden)

    Vallittu P

    2006-08-01

    Full Text Available Fiber-reinforced composite resin (FRC prostheses offer the advantages of good esthetics, minimal invasive treatment, and an ability to bond to the abutment teeth, thereby compensating for less-than-optimal abutment tooth retention and resistance form. These prostheses are composed of two types of composite materials: fiber composites to build the framework and hybrid or microfill particulate composites to create the external veneer surface. This review concentrates on the use of fiber reinforcement in the fabrication of laboratory or chairside-made composite-fixed partial dentures of conventional preparation. Other applications of FRC in dentistry are briefly mentioned. The possibilities fiber reinforcement technology offers must be emphasized to the dental community. Rather than limiting discussion to whether FRC prostheses will replace metal-ceramic or full-ceramic prostheses, attention should be focused on the additional treatment options brought by the use of fibers. However, more clinical experience is needed.

  18. 粉末注射成形制备Si_3N_4颗粒增强316L不锈钢%Si_3N_4 particle-reinforced 316L stainless steel prepared by powder injection molding

    Institute of Scientific and Technical Information of China (English)

    田常娟; 何新波; 梅敏; 曲选辉

    2011-01-01

    Si3N4 particle-reinforced 316L stainless steel composites were prepared by powder injection molding(PIM) using water-soluble binders.It is shown that a water-soluble binder mainly consisting of polyoxymethylene(PEG),polyvinyl butyral(PVB) and stearic acid(SA) exhibits a better water-soluble degreasing performance.After degreasing injection parts in water for 6 h,the total binder removal rate is 55% and the PEG removal rate is 78.6%.The sintered composites have a uniform microstructure and excellent properties with a relative density of 95.2%,a hardness of HRB 79.8 and a tensile strength of 620 MPa.And the hardness and tensile strength are 5% and 20.4% higher than the Si3N4 particle-reinforced 316L stainless steel produced by PIM with a paraffin wax-based binder,respectively.%以多组元水溶性黏结剂为黏结剂,采用粉末注射成形工艺成功制备出了Si3N4颗粒增强316L不锈钢复合材料.研究表明:以聚乙二醇(PEG)、聚乙烯醇缩丁醛(PVB)和硬脂酸(SA)为主要成分的水溶性黏结剂表现出较好的水溶脱脂性能,注射坯在蒸馏水中脱脂6 h后,黏结剂总脱除率约为55%,其中PEG的脱除率约为78.6%;复合材料经烧结后组织均匀致密,性能良好,其致密度、硬度和拉伸强度分别为97.5%、HRB 81.7和620 MPa,其硬度和拉伸强度分别比采用石蜡基黏结剂制备的PIM--Si3N4增强316L不锈钢复合材料提高5%和20.4%.

  19. Thermal oxidation of medical Ti6Al4V blasted with ceramic particles: Effects on the microstructure, residual stresses and mechanical properties.

    Science.gov (United States)

    Lieblich, M; Barriuso, S; Multigner, M; González-Doncel, G; González-Carrasco, J L

    2016-02-01

    Roughening of Ti6Al4V by blasting with alumina or zirconia particles improves the mechanical fixation of implants by increasing the surface area available for bone/implant apposition. Additional thermal oxidation treatments of the blasted alloy have already shown to be a complementary low-cost solution to enhancing the in vitro biocompatibility and corrosion resistance of the alloy. In this work, the effects of oxidation treatment on a grit blasted Ti6Al4V biomedical alloy have been analysed in order to understand the net effect of the combined treatments on the alloy fatigue properties. Synchrotron radiation diffraction experiments have been performed to measure residual stresses before and after the treatments and microstructural and hardness changes have been determined. Although blasting of Ti6Al4V with small spherical zirconia particles increases the alloy fatigue resistance with respect to unblasted specimens, fatigue strength after oxidation decreases below the unblasted value, irrespective of the type of particle used for blasting. Moreover, at 700°C the as-blasted compressive residual stresses (700MPa) are not only fully relaxed but even moderate tensile residual stresses, of about 120MPa, are found beneath the blasted surfaces. Contrary to expectations, a moderate increase in hardness occurs towards the blasted surface after oxidation treatments. This can be attributed to the fact that grit blasting modifies the crystallographic texture of the Ti6Al4V shifting it to a random texture, which affects the hardness values as shown by additional experiments on cold rolled samples. The results indicate that the oxidation treatment performed to improve biocompatibility and corrosion resistance of grit blasted Ti6Al4V should be carried out with caution since the alloy fatigue strength can be critically diminished below the value required for high load-bearing components. PMID:26458115

  20. REINFORCED COMPOSITE PANEL

    DEFF Research Database (Denmark)

    2003-01-01

    A composite panel having front and back faces, the panel comprising facing reinforcement, backing reinforcement and matrix material binding to the facing and backing reinforcements, the facing and backing reinforcements each independently comprising one or more reinforcing sheets, the facing rein...... by matrix material, the facing and backing reinforcements being interconnected to resist out-of-plane relative movement. The reinforced composite panel is useful as a barrier element for shielding structures, equipment and personnel from blast and/or ballistic impact damage.......A composite panel having front and back faces, the panel comprising facing reinforcement, backing reinforcement and matrix material binding to the facing and backing reinforcements, the facing and backing reinforcements each independently comprising one or more reinforcing sheets, the facing...... reinforcement being located on or embedded in matrix material adjacent to the front face of the panel, the backing reinforcement being located in a plane or planes substantially parallel to the plane or planes of the facing reinforcement, and being substantially coextensive therewith, and spaced therefrom...

  1. Flash sintering of ceramic materials

    Science.gov (United States)

    Dancer, C. E. J.

    2016-10-01

    During flash sintering, ceramic materials can sinter to high density in a matter of seconds while subjected to electric field and elevated temperature. This process, which occurs at lower furnace temperatures and in shorter times than both conventional ceramic sintering and field-assisted methods such as spark plasma sintering, has the potential to radically reduce the power consumption required for the densification of ceramic materials. This paper reviews the experimental work on flash sintering methods carried out to date, and compares the properties of the materials obtained to those produced by conventional sintering. The flash sintering process is described for oxides of zirconium, yttrium, aluminium, tin, zinc, and titanium; silicon and boron carbide, zirconium diboride, materials for solid oxide fuel applications, ferroelectric materials, and composite materials. While experimental observations have been made on a wide range of materials, understanding of the underlying mechanisms responsible for the onset and latter stages of flash sintering is still elusive. Elements of the proposed theories to explain the observed behaviour include extensive Joule heating throughout the material causing thermal runaway, arrested by the current limitation in the power supply, and the formation of defect avalanches which rapidly and dramatically increase the sample conductivity. Undoubtedly, the flash sintering process is affected by the electric field strength, furnace temperature and current density limit, but also by microstructural features such as the presence of second phase particles or dopants and the particle size in the starting material. While further experimental work and modelling is still required to attain a full understanding capable of predicting the success of the flash sintering process in different materials, the technique non-etheless holds great potential for exceptional control of the ceramic sintering process.

  2. Mechanical properties of microwave sintered Si3N4-based ceramics

    Directory of Open Access Journals (Sweden)

    Getman O.I.

    2002-01-01

    Full Text Available The mechanical properties and microstructure formation processes in Si3N4+3% AI2O3+5% Y2O3(Yb2O3 ceramic compacts sintered under microwave heating (MWH and under traditional heating (TH were investigated. The initial ceramic materials were powder blends of silicon nitride with oxides. The mean powder particle sizes were 0.5-1.0 mim. The content of alfa-phase in the Si3N4 powder was more than 95 %. The samples were sintered at 1800BC in nitrogen at normal pressure, the heating rate in all experiments was 60BC/min. The Vickers hardness (HV, fracture toughness (K1C and bending strength (on were determined. The microstructures of fracture surfaces of samples were studied by SEM. Quantitative microstructure analysis was carried out. It was shown that the values of HV and Kic of ceramic samples sintered under MWH at 1800BC rose steadily with the sintering time. This caused an increase in density, which reached maximum as fast as after 30 min of the MWH sintering; the mass loss at that time amounted to 3-4 %. The porosity of sintered samples with an addition of yttria was less than 1 %, that of ytterbia was greater, 2.4 %. For similar values of relative density, the hardness and fracture toughness of ceramic samples produced under MWH were higher as compared with those of samples sintered under TH. The microstructure of samples had the form of elongated grains in a matrix of polyhedral grains of the beta-Si3N4 phase. Measurements showed the mean size of grains in samples produced by MWH to be greater that in samples produced by TH. A larger number of elongated grains were formed. It was concluded that for sintering under MWH of Si3N4-based ceramics the growth of elongated beta-Si3N4 grains and formation of a "reinforced" microstructure were promoted and thereby improved the mechanical properties of such ceramics.

  3. Thin film ceramic thermocouples

    Science.gov (United States)

    Gregory, Otto (Inventor); Fralick, Gustave (Inventor); Wrbanek, John (Inventor); You, Tao (Inventor)

    2011-01-01

    A thin film ceramic thermocouple (10) having two ceramic thermocouple (12, 14) that are in contact with each other in at least on point to form a junction, and wherein each element was prepared in a different oxygen/nitrogen/argon plasma. Since each element is prepared under different plasma conditions, they have different electrical conductivity and different charge carrier concentration. The thin film thermocouple (10) can be transparent. A versatile ceramic sensor system having an RTD heat flux sensor can be combined with a thermocouple and a strain sensor to yield a multifunctional ceramic sensor array. The transparent ceramic temperature sensor that could ultimately be used for calibration of optical sensors.

  4. Aluminium EN AC-AlSi12 alloy matrix composite materials reinforced by Al2O3 porous preforms

    OpenAIRE

    Nagel, A.; M. Kremzer; L.A. Dobrzański,

    2007-01-01

    Purpose: The purpose of this work is to elaborate the method of manufacturing of composite materials based on porous ceramic preforms infiltrated by eutectic aluminium alloy.Design/methodology/approach: The material for investigations was fabricated by pressure infiltration method of ceramic porous preforms. The eutectic aluminium alloy EN AC – AlSi12 was use as a matrix while as reinforcement were used ceramic preforms fabricated by sintering of Al2O3 Alcoa CL 2500 powder with addition of po...

  5. MECHANICAL STRENGTH OF HIGHLY POROUS CERAMICS

    NARCIS (Netherlands)

    VANDENBORN, IC; SANTEN, A; HOEKSTRA, HD; DEHOSSON, JTM; Born, I.C. van den

    1991-01-01

    This paper reports on the mechanical strength of highly porous ceramics in terms of the Weibull and Duxbury-Leath distributions. More than 1000 side-crushing strength tests on silica-catalyst carriers of various particle sizes have been performed in series. Within a series, preparation conditions we

  6. Fabrication of hexagonal boron nitride based ceramics by combustion synthesis

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Pure h-BN (hexagonal boron nitride) and h-BN based ceramic parts were fabricated by combustion synthesis technique, i.e. self-propagating high-temperature synthesis (SHS). Components were manufactured by the combustion reaction of 80  MPa nitrogen and the compact made by cool isostatic pressing. In h-BN based ceramic parts, h-BN powder was used as diluent and SiO2 powder as reinforcing phase. The density of pure h-BN and h-BN-based ceramic parts were 58% and 78% of theoretical density, respectively. With XRD and SEM, phases and microstructures of ceramic parts were analyzed. Mechanical properties were also tested.

  7. Manufacturing of Porous Ceramic Preforms Based on Halloysite Nanotubes (Hnts

    Directory of Open Access Journals (Sweden)

    Kujawa M.

    2016-06-01

    Full Text Available The aim of this study was to determine the influence of manufacturing conditions on the structure and properties of porous halloysite preforms, which during pressure infiltration were soaked with a liquid alloy to obtain a metal matrix composite reinforced by ceramic, and also to find innovative possibilities for the application of mineral nanotubes obtained from halloysite. The method of manufacturing porous ceramic preforms (based on halloysite nanotubes as semi-finished products that are applicable to modern infiltrated metal matrix composites was shown. The ceramic preforms were manufactured by sintering of halloysite nanotubes (HNT, Natural Nano Company (USA, with the addition of pores and canals forming agent in the form of carbon fibres (Sigrafil C10 M250 UNS SGL Group, the Carbon Company. The resulting porous ceramic skeletons, suggest innovative application capabilities mineral nanotubes obtained from halloysite.

  8. Considerations for ceramic inlays in posterior teeth: a review

    Directory of Open Access Journals (Sweden)

    Hopp CD

    2013-04-01

    Full Text Available Christa D Hopp,1 Martin F Land2 1Section of Operative Dentistry, 2Section of Fixed Prosthodontics, Southern Illinois University, Alton, IL, USA Abstract: This review of ceramic inlays in posterior teeth includes a review of the history of ceramic restorations, followed by common indications and contraindications for their use. A discussion on the potential for tooth wear is followed by a review of recommended preparation design considerations, fabrication methods, and material choices. Despite the improved materials available for fabrication of porcelain inlays, fracture remains a primary mode of inlay failure. Therefore, a brief discussion on strengthening methods for ceramics is included. The review concludes with a section on luting considerations, and offers the clinician specific recommendations for luting procedures. In conclusion, inlay success rates and longevity, as reported in the literature, are summarized. Keywords: inlays, ceramic, posterior, review, CAD/CAM, leucite reinforced, lithium disilicate, longevity, esthetics, luting, wear, stress, selection

  9. Influence of in situ formed ZrB2 particles on microstructure and mechanical properties of AA6061 metal matrix composites

    International Nuclear Information System (INIS)

    Highlights: → In situ fabrication of aluminium metal matrix composite reinforced ZrB2 particles. → Colour metallography of composites. → Improvement of matrix properties by ZrB2 particles. → Sliding wear behaviour of in situ composites. - Abstract: Particulate reinforced metal matrix composites (PMMCs) have gained considerable amount of research emphasis and attention in the present era. Research is being carried out across the globe to produce new combination of PMMCs. PMMCs are prepared by adding a variety of ceramic particles with monolithic alloys using several techniques. An attempt has been made to produce aluminium metal matrix composites reinforced with zirconium boride (ZrB2) particles by the in situ reaction of K2ZrF6 and KBF4 salts with molten aluminium. The influence of in situ formed ZrB2 particles on the microstructure and mechanical properties of AA6061 alloy was studied in this work. The in situ formed ZrB2 particles significantly refined the microstructure and enhanced the mechanical properties of AA6061 alloy. The weight percentage of ZrB2 was varied from 0 to 10 in steps of 2.5. Improvement of hardness, ultimate tensile strength and wear resistance of AA6061 alloy was observed with the increase in ZrB2 content.

  10. Radiation stability test on multiphase glass ceramic and crystalline ceramic waste forms

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Ming; Kossoy, Anna; Jarvinen, G. D.; Crum, Jarrod V.; Turo, Laura A.; Riley, Brian J.; Brinkman, Kyle; Fox, Kevin M.; Amoroso, Jake; Marra, James C.

    2014-02-03

    A radiation stability study was performed on glass ceramic and crystalline ceramic waste forms. These materials are candidate host materials for immobilizing alkali/alkaline earth (Cs/Sr-CS) + lanthanide (LN) + transition metal (TM) fission product waste streams from nuclear fuel reprocessing. In this study, glass ceramics were fabricated using a borosilicate glass as a matrix in which to incorporate CS/LN/TM combined waste streams. The major phases in these multiphase materials are powellite, oxyaptite, pollucite, celsian, and durable residual glass phases. Al2O3 and TiO2 were combined with these waste components to produce multiphase crystalline ceramics containing hollandite-type phases, perovskites, pyrochlores and other minor metal titanate phases. For the radiation stability test, selected glass ceramic and crystalline ceramic samples were exposed to different irradiation environments including low fluxes of high-energy (~1–5 MeV) protons and alpha particles generated by an ion accelerator, high fluxes of low-energy (hundreds of keV) krypton particles generated by an ion implanter, and in-situ electron irradiations in a transmission electron microscope. These irradiation experiments were performed to simulate self-radiation effects in a waste form. Ion irradiation-induced microstructural modifications were examined using X-ray diffraction and transmission electron microscopy. Our preliminary results reveal different radiation tolerance in different crystalline phases under various radiation damage environments. However, their stability may be rate dependent which may limit the waste loading that can be achieved.

  11. Radiation stability test on multiphase glass ceramic and crystalline ceramic waste forms

    Science.gov (United States)

    Tang, Ming; Kossoy, Anna; Jarvinen, Gordon; Crum, Jarrod; Turo, Laura; Riley, Brian; Brinkman, Kyle; Fox, Kevin; Amoroso, Jake; Marra, James

    2014-05-01

    A radiation stability study was performed on glass ceramic and crystalline ceramic waste forms. These materials are candidate host materials for immobilizing alkali/alkaline earth (Cs/Sr-CS) + lanthanide (LN) + transition metal (TM) fission product waste streams from nuclear fuel reprocessing. In this study, glass ceramics were fabricated using a borosilicate glass as a matrix in which to incorporate CS/LN/TM combined waste streams. The major phases in these multiphase materials are powellite, oxyaptite, pollucite, celsian, and durable residual glass phases. Al2O3 and TiO2 were combined with these waste components to produce multiphase crystalline ceramics containing hollandite-type phases, perovskites, pyrochlores and other minor metal titanate phases. For the radiation stability test, selected glass ceramic and crystalline ceramic samples were exposed to different irradiation environments including low fluxes of high-energy (∼1-5 MeV) protons and alpha particles generated by an ion accelerator, high fluxes of low-energy (hundreds of keV) krypton particles generated by an ion implanter, and in-situ electron irradiations in a transmission electron microscope. These irradiation experiments were performed to simulate self-radiation effects in a waste form. Ion irradiation-induced microstructural modifications were examined using X-ray diffraction and transmission electron microscopy. Our preliminary results reveal different radiation tolerance in different crystalline phases under various radiation damage environments. However, their stability may be rate dependent which may limit the waste loading that can be achieved.

  12. Simultaneous determination of Si, Al and Na concentrations by particle induced gamma-ray emission and applications to reference materials and ceramic archaeological artifacts

    Energy Technology Data Exchange (ETDEWEB)

    Dasari, K.B. [Radiochemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India); GITAM Institute of Science, GITAM University, Visakhapatnam 530045 (India); Chhillar, S. [Radiochemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India); Acharya, R., E-mail: racharya@barc.gov.in [Radiochemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India); Ray, D.K.; Behera, A. [Ion Beam Laboratory, Institute of Physics, Bhubaneswar 751005 (India); Lakshmana Das, N. [GITAM Institute of Science, GITAM University, Visakhapatnam 530045 (India); Pujari, P.K. [Radiochemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India)

    2014-11-15

    A particle induced gamma ray emission (PIGE) method using 4 MeV proton beam was standardized for simultaneous determination of Si, Al and Na concentrations and has been applied for non-destructive analysis of several reference materials and archaeological clay pottery samples. Current normalized count rates of gamma-rays for the three elements listed above were obtained by an in situ method using Li as internal standard. The paper presents application of the in situ current normalized PIGE method for grouping study of 39 clay potteries, obtained from Rajasthan and Andhra Pradesh states of India. Grouping of artifacts was carried out using the ratios of SiO{sub 2} to Al{sub 2}O{sub 3} concentrations, due to their non volatile nature. Powder samples and elemental standards in pellet forms (cellulose matrix) were irradiated using the 4 MeV proton beam (∼10 nA) from the 3 MV tandem accelerator at IOP Bhubaneswar, and assay of prompt gamma rays was carried out using a 60% relative efficiency HPGe detector coupled to MCA. The concentration ratio values of SiO{sub 2}/Al{sub 2}O{sub 3} indicated that pottery samples fell into two major groups, which are in good agreement with their collection areas. Reference materials from IAEA and NIST were analyzed for quantification of Si, Al and Na concentrations as a part of validation as well as application of PIGE method.

  13. Resistance to bond degradation between dual-cure resin cements and pre-treated sintered CAD-CAM dental ceramics

    Science.gov (United States)

    Osorio, Raquel; Monticelli, Francesca; Osorio, Estrella; Toledano, Manuel

    2012-01-01

    Objective: To evaluate the bond stability of resin cements when luted to glass-reinforced alumina and zirconia CAD/CAM dental ceramics. Study design: Eighteen glass-infiltrated alumina and eighteen densely sintered zirconia blocks were randomly conditioned as follows: Group 1: No treatment; Group 2: Sandblasting (125 µm Al2O3-particles); and Group 3: Silica-coating (50 µm silica-modified Al2O3-particles). Composite samples were randomly bonded to the pre-treated ceramic surfaces using different resin cements: Subgroup 1: Clearfil Esthetic Cement (CEC); Subgroup 2: RelyX Unicem (RXU); and Subgroup 3: Calibra (CAL). After 24 h, bonded specimens were cut into 1 ± 0.1 mm2 sticks. One-half of the beams were tested for microtensile bond strength (MTBS). The remaining one-half was immersed in 10 % NaOCl aqueous solution (NaOClaq) for 5 h before testing. The fracture pattern and morphology of the debonded surfaces were assessed with a field emission gun scanning electron microscope (FEG-SEM). A multiple ANOVA was conducted to analyze the contributions of ceramic composition, surface treatment, resin cement type, and chemical challenging to MTBS. The Tukey test was run for multiple comparisons (p < 0.05). Results: After 24 h, CEC luted to pre-treated zirconia achieved the highest MTBS. Using RXU, alumina and zirconia registered comparable MTBS. CAL failed prematurely, except when luted to sandblasted zirconia. After NaOClaq storage, CEC significantly lowered MTBS when luted to zirconia or alumina. RXU decreased MTBS only when bonded to silica-coated alumina. CAL recorded 100 % of pre-testing failures. Micromorphological alterations were evident after NaOClaq immersion. Conclusions: Resin-ceramic interfacial longevity depended on cement selection rather than on surface pre-treatments. The MDP-containing and the self-adhesive resin cements were both suitable for luting CAD/CAM ceramics. Despite both cements being prone to degradation, RXU luted to zirconia or untreated or

  14. SiC颗粒增强铁基合金复合涂层的组织%Microstructure of SiC particles reinforced Fe-based alloy composite coating

    Institute of Scientific and Technical Information of China (English)

    宋自力; 杜晓东; 李连颖; 王家庆; 叶诚

    2011-01-01

    采用等离子堆焊—SiC后送粉技术制备了SiC颗粒增强铁基合金复合涂层,利用扫描电子显微镜(SEM)、X射线衍射仪(XRD)和能谱仪(EDS)对涂层的显微组织、相组成和元素分布进行了观察和测试。试验结果表明:SiC分布于马氏体基体上,原始形态保持完好,没有发生明显溶解,复合效果较好。SiC与基体界面层由预覆层、近基体区和絮状区构成。SiC边缘为CrSi2、CrSi3;近基体区耐腐蚀性相对基体较强,组织难以显示;絮状区由大量(Fe,Cr)7 C3、(Fe,Cr)23 C6碳化物和α-(Fe,Cr)固溶体组成。%Iron-based alloy coating reinforced by precoated SiC particles was prepared by plasma surfacing process with SiC back-feeding model.SEM,XRD and EDS were used to analyse microstructure,phases and elemental distribution of the coating.The results show that the precoated SiC particles were not dissolved significantly.They retained original shape in martensitic matrix.The interface layer between SiC particles and the matrix can be divided into precoated film,near-matrix region and cotton-like region.The precoated film contains CrSi2 and CrSi3.The microstructure in the near-matrix region isn't easy to be indentified because of its excellent corrosion resistance.Whereas,the microstructure of the cotton-like region can be seen obviously by SEM,which is consists of α-(Fe,Cr) solid solution and a large amount of(Fe,Cr)7C3 and(Fe,Cr)23C6 carbides dispersing between α-(Fe,Cr) phase.

  15. Reinforcement, Expectancy, and Learning

    Science.gov (United States)

    Bolles, Robert

    1972-01-01

    Surveys some of the difficulties currently confronting the reinforcement concept and cosiders some alternatives to reinforcement as the fundamental basis of learning. Two specific alternatives considered are: an incentive motivation approach and a cognitive approach. (Author)

  16. Shear Reinforcements in the Reinforced Concrete Beams

    Directory of Open Access Journals (Sweden)

    Moayyad M. Al-Nasra

    2013-10-01

    Full Text Available - This study focuses on the use of different types of shear reinforcement in the reinforced concrete beams. Four different types of shear reinforcement are investigated; traditional stirrups, welded swimmer bars, bolted swimmer bars, and u-link bolted swimmer bars. Beam shear strength as well as beam deflection are the main two factors considered in this study. Shear failure in reinforced concrete beams is one of the most undesirable modes of failure due to its rapid progression. This sudden type of failure made it necessary to explore more effective ways to design these beams for shear. The reinforced concrete beams show different behavior at the failure stage in shear compare to the bending, which is considered to be unsafe mode of failure. The diagonal cracks that develop due to excess shear forces are considerably wider than the flexural cracks. The cost and safety of shear reinforcement in reinforced concrete beams led to the study of other alternatives. Swimmer bar system is a new type of shear reinforcement. It is a small inclined bars, with its both ends bent horizontally for a short distance and welded or bolted to both top and bottom flexural steel reinforcement. Regardless of the number of swimmer bars used in each inclined plane, the swimmer bars form plane-crack interceptor system instead of bar-crack interceptor system when stirrups are used. Several reinforced concrete beams were carefully prepared and tested in the lab. The results of these tests will be presented and discussed. The deflection of each beam is also measured at incrementally increased applied load.

  17. Management of Reinforcement Corrosion

    DEFF Research Database (Denmark)

    Küter, André; Geiker, Mette Rica; Møller, Per

    Reinforcement corrosion is the most important cause for deterioration of reinforced concrete structures, both with regard to costs and consequences. Thermodynamically consistent descriptions of corrosion mechanisms are expected to allow the development of innovative concepts for the management...... of reinforcement corrosion....

  18. Reinforcement of Learning

    Science.gov (United States)

    Jones, Peter

    1977-01-01

    A company trainer shows some ways of scheduling reinforcement of learning for trainees: continuous reinforcement, fixed ratio, variable ratio, fixed interval, and variable interval. As there are problems with all methods, he suggests trying combinations of various types of reinforcement. (MF)

  19. Management of Reinforcement Corrosion

    DEFF Research Database (Denmark)

    Küter, André; Geiker, Mette Rica; Møller, Per

    Reinforcement corrosion is the most important cause for deterioration of reinforced concrete structures, both with regard to costs and consequences. Thermodynamically consistent descriptions of corrosion mechanisms are expected to allow the development of innovative concepts for the management of...... reinforcement corrosion....

  20. Ceramic tamper-revealing seals

    Science.gov (United States)

    Kupperman, David S.; Raptis, Apostolos C.; Sheen, Shuh-Haw

    1992-01-01

    A flexible metal or ceramic cable with composite ceramic ends, or a u-shaped ceramic connecting element attached to a binding element plate or block cast from alumina or zirconium, and connected to the connecting element by shrink fitting.

  1. Analyses of fine paste ceramics

    International Nuclear Information System (INIS)

    Four chapters are included: history of Brookhaven fine paste ceramics project, chemical and mathematical procedures employed in Mayan fine paste ceramics project, and compositional and archaeological perspectives on the Mayan fine paste ceramics

  2. Analyses of fine paste ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Sabloff, J A [ed.

    1980-01-01

    Four chapters are included: history of Brookhaven fine paste ceramics project, chemical and mathematical procedures employed in Mayan fine paste ceramics project, and compositional and archaeological perspectives on the Mayan fine paste ceramics. (DLC)

  3. Analysis of interface interaction and tensile properties of CaCO3 nano particle reinforced PVC composites%纳米CaCO3增韧聚氯乙烯复合材料的界面作用和拉伸性能探析

    Institute of Scientific and Technical Information of China (English)

    邓渊林

    2015-01-01

    with the development of the continued ascent speed in our country in the field of composite materials and composite gradually,has been more and more research of nano CaCO3 particle reinforced PVC composites.This paper expounded through the interface function of CaCO3 nano particle reinforced PVC composites,tensile properties of nano CaCO3 particle reinforced PVC composites are analyzed.%随着我国复合材料领域发展速度的持续提升和复合材料研究的逐渐深入,纳米CaCO3增韧聚氯乙烯复合材料得到了越来越多的研究。本文通过对纳米CaCO3增韧聚氯乙烯复合材料的界面作用进行阐述,对纳米CaCO3增韧聚氯乙烯复合材料的拉伸性能进行了分析。

  4. Measuring Fracture Times Of Ceramics

    Science.gov (United States)

    Shlichta, Paul J.; Bister, Leo; Bickler, Donald G.

    1989-01-01

    Electrical measurements complement or replace fast cinematography. Electronic system measures microsecond time intervals between impacts of projectiles on ceramic tiles and fracture tiles. Used in research on ceramics and ceramic-based composite materials such as armor. Hardness and low density of ceramics enable them to disintegrate projectiles more efficiently than metals. Projectile approaches ceramic tile specimen. Penetrating foil squares of triggering device activate display and recording instruments. As ceramic and resistive film break oscilloscope plots increase in electrical resistance of film.

  5. Defect production in ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Zinkle, S.J. [Oak Ridge National Lab., TN (United States); Kinoshita, C. [Kyushu Univ. (Japan)

    1997-08-01

    A review is given of several important defect production and accumulation parameters for irradiated ceramics. Materials covered in this review include alumina, magnesia, spinel silicon carbide, silicon nitride, aluminum nitride and diamond. Whereas threshold displacement energies for many ceramics are known within a reasonable level of uncertainty (with notable exceptions being AIN and Si{sub 3}N{sub 4}), relatively little information exists on the equally important parameters of surviving defect fraction (defect production efficiency) and point defect migration energies for most ceramics. Very little fundamental displacement damage information is available for nitride ceramics. The role of subthreshold irradiation on defect migration and microstructural evolution is also briefly discussed.

  6. Microstructural studies on some silicate and phosphate based glass-ceramics

    International Nuclear Information System (INIS)

    Recent developments have made it possible to make a new class of ceramic materials called glass-ceramics with tailored expansion coefficients and improved thermo-mechanical and corrosion resistance properties. Since these are formed by controlled crystallization in which crystallites are embedded in the glassy matrix, it is possible to make nano glass-ceramics having pronounced effect of particle size on various properties such as transparency, bioactivity, etc. In this talk, some of the recent results on micro-structural properties of a few glass-ceramic-to-metal sealants and bio-glass-ceramics are discussed

  7. Ceramic fragments and metal-free full crowns: a conservative esthetic option for closing diastemas and rehabilitating smiles.

    Science.gov (United States)

    Miranda, M E; Olivieri, K A; Rigolin, F J; Basting, R T

    2013-01-01

    Dental ceramics make it possible to restore anterior teeth that have been esthetically compromised, presenting a high resistance to wear, biocompatibility, color stability, and low thermal conductivity. The development of different types of ceramic and techniques for adhesive cementation have made it possible to produce more conservative restorations without involving the healthy dental structure and with minimally invasive preparation, such as the bonding of ceramic fragments. The purpose of this article is to describe a clinical case in which diastemas were closed by using nanofluorapatite ceramic (e.max Ceram, Ivoclar-Vivadent) fragments on teeth 7 and 10 with minimal tooth preparation and metal-free ceramic crowns (e-max Ceram) reinforced with zirconia copings through a computer-aided design/computer-aided manufacturing system (Lava, 3M-ESPE) on teeth 8 and 9.

  8. 粉料的粒度分布对TiAl合金熔模精密铸造用氧化锆陶瓷型壳性能的影响%Effect of particle size distribution on properties of zirconia ceramic mould for TiAl investment casting

    Institute of Scientific and Technical Information of China (English)

    陈艳飞; 肖树龙; 田竟; 徐丽娟; 陈玉勇

    2011-01-01

    研究粉料的粒度分布对TiAl合金熔模精密铸造用氧化锆陶瓷性能的影响.对粉料粒度分布、粉末形貌、浆料黏度、型壳抗弯强度和断裂形貌之间的关系进行研究;通过测量氧化锆粉末和粘结剂构成的浆料的黏度来考察粉末粒度分布对浆料黏的影响;对不同粒度分布氧化锆陶瓷型壳断口形貌进行观察.结果表明:粉料粒度分布对未焙烧和焙烧后氧化锆陶瓷型壳的强度影响行为相似;粉料粒度分布对氧化锆陶瓷型壳的质量能产生很大的影响并进而影响到熔模精密铸造制备TiAl合金构件的质量.%The effect of particle size distributions (PSDs) on the properties of zirconia ceramic mould for TiAl investment casting was described.The relationship between the zirconia powder characteristics and properties of the ceramic moulds was investigated.The particle size distribution,morphology of particles,viscosity of slurries,mechanical properties and tracture surfaces of ceramic moulds were examined.The effect of PSDs on the viscosity was observed through the measurement of slurries prepared from zirconia and binder.The morphology of the fracture surface of the zirconia moulds with different PSDs was also investigated.The measurement of bend strength shows that the mechanical behaviors of the green and fired zirconia ceramic moulds are comparable for all systems.The preliminary results illustrate that the PSDs play an important role in determining the quality of ceramic moulds and thus on the metallurgical quality of TiAl components produced by investment casting process.

  9. Fractal analysis on high-speed grinding surface of particle-reinforced titanium matrix composites%颗粒增强钛基复合材料高速磨削表面分形分析

    Institute of Scientific and Technical Information of China (English)

    奚欣欣; 丁文锋; 傅玉灿; 赵盟月; 李学文

    2014-01-01

    High-speed grinding experiments were carried out on particle-reinforced titanium matrix composites.The fractal dimension of the planar micro region within the machined surface was calculated to evaluate the surface quality of the ground samples.The result revealed that the wheel speed had some influences on the ground surface quality.Different wheel speed (i.e.,80 m/s,120 m/s,150 m/s) corresponded to the different fractal dimension values of the planar micro region(i.e., 2.004 30,2.005 56,2.006 52) respectively.A linear relationship has been established between the fractal dimension and the wheel speed in grinding.It was confirmed that the method could evaluate the surface quality of the ground samples by means of the fractal dimension of the planar micro region.%开展了颗粒增强钛基复合材料高速磨削实验,分析了平面微小区域的分形维数,进而对磨削表面形貌进行了评价。结果显示,磨削速度对磨削表面微观形貌具有一定影响。三种磨削速度条件下(80、120、150 m/s)所对应的磨削平面微小区域分形维数分别为2.00430、2.00556、2.00652,与磨削速度呈线性关系,表明了应用表面微小区域分形维数评价磨削表面质量的可行性。

  10. 高速磨削颗粒增强钛基复合材料的热分配分析%Energy partition in high-speed grinding of particle reinforced titanium matrix composites

    Institute of Scientific and Technical Information of China (English)

    奚欣欣; 丁文锋; 刘敏; 王训扬

    2015-01-01

    A calculation method of the energy partition to the workpiece material based on uniform thermal source was presented•High-speed grinding experiments were conducted on the particle reinforced titanium matrix composites(PTMCs)using an electroplated cubic boron nitride(CBN)wheels with grinding speeds of 80- 160 m∕s•A linear relationship was found between the specific grinding energy and the parameters combination d s 1∕4 a p -3∕4 v w -1∕2 ,by which the energy partition to the workpiece was calculated,which was 52•0%-79•5% in the present study•Additionally,the temperature distribution in high-speed grinding of PTMCs was explored based on finite element analysis.%针对颗粒增强钛基复合材料(PTMCs)高速磨削的特征,以均匀热源为模型,提出了一种计算磨削过程中热分配比例的新方法。采用CBN超硬磨料砂轮在80~160 m/s的速度范围内进行了高速磨削验证,试验结果表明:PTMCs高速磨削热传递过程中比能e s 与d s 1/4 a p-3/4 v w-1/2呈直线关系,与理论分析相一致,并基于此得到电镀CBN砂轮高速磨削PTMCs 进入工件的热量比例为52.0%~79.5%。同时,进行了电镀砂轮高速磨削温度场仿真,探明了其温度分布特征。

  11. Mechanically-reinforced electrospun composite silk fibroin nanofibers containing hydroxyapatite nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hyunryung [School of Mechanical Engineering, Yonsei University, Seoul 120-749 (Korea, Republic of); Che, Lihua; Ha, Yoon [Department of Neurosurgery, College of Medicine, Yonsei University, Seoul 120-749 (Korea, Republic of); Ryu, WonHyoung, E-mail: whryu@yonsei.ac.kr [School of Mechanical Engineering, Yonsei University, Seoul 120-749 (Korea, Republic of)

    2014-07-01

    Electrospun silk fibroin (SF) scaffolds provide large surface area, high porosity, and interconnection for cell adhesion and proliferation and they may replace collagen for many tissue engineering applications. Despite such advantages, electrospun SF scaffolds are still limited as bone tissue replacement due to their low mechanical strengths. While enhancement of mechanical strengths by incorporating inorganic ceramics into polymers has been demonstrated, electrospinning of a mixture of SF and inorganic ceramics such as hydroxyapatite is challenging and less studied due to the aggregation of ceramic particles within SF. In this study, we aimed to enhance the mechanical properties of electrospun SF scaffolds by uniformly dispersing hydroxyapatite (HAp) nanoparticles within SF nanofibers. HAp nanoaprticles were modified by γ-glycidoxypropyltrimethoxysilane (GPTMS) for uniform dispersion and enhanced interfacial bonding between HAp and SF fibers. Optimal conditions for electrospinning of SF and GPTMS-modified HAp nanoparticles were identified to achieve beadless nanofibers without any aggregation of HAp nanoparticles. The MTT and SEM analysis of the osteoblasts-cultured scaffolds confirmed the biocompatibility of the composite scaffolds. The mechanical properties of the composite scaffolds were analyzed by tensile tests for the scaffolds with varying contents of HAp within SF fibers. The mechanical testing showed the peak strengths at the HAp content of 20 wt.%. The increase of HAp content up to 20 wt.% increased the mechanical properties of the composite scaffolds, while further increase above 20 wt.% disrupted the polymer chain networks within SF nanofibers and weakened the mechanical strengths. - Highlights: • Electrospun composite silk fibroin scaffolds were mechanically-reinforced. • GPTMS enhanced hydroxyapatite distribution in silk fibroin nanofibers. • Mechanical property of composite scaffolds increased up to 20% of hydroxyapatite. • Composite

  12. Fabrication of lanthanum doped yttria transparent ceramics

    Institute of Scientific and Technical Information of China (English)

    HUANG YiHua; JIANG DongLiang; ZHANG JingXian; LIN QingLing

    2009-01-01

    Yttria nanocrystalline powder doped with 9% lanthanum was synthesized by co-precipitation method using ammonia for pH adjusting. After calcinations, finer particles with narrow distribution and large surface area were obtained. After dry pressing, samples were sintered at 1500℃-1700℃ for 4 h in vacuum to produce transparent polycrystalline ceramics with uniform grains. Samples with 9 mol%lanthanum were transparent in visible light after being sintered at 1500℃ for 4 h. The grain sizes increased with lanthanum doping compared with those of pure yttria transparent ceramic sintered at the same conditions. Relative density of the transparent ceramic was 99.7%. The in-line transmittance was 73% at 580 nm wavelength after milling and polishing.

  13. Habituation of reinforcer effectiveness

    Directory of Open Access Journals (Sweden)

    David R Lloyd

    2014-01-01

    Full Text Available In this paper we propose an integrative model of habituation of reinforcer effectiveness (HRE that links behavioral and neural based explanations of reinforcement. We argue that habituation of reinforcer effectiveness (HRE is a fundamental property of reinforcing stimuli. Most reinforcement models implicitly suggest that the effectiveness of a reinforcer is stable across repeated presentations. In contrast, an HRE approach predicts decreased effectiveness due to repeated presentation. We argue that repeated presentation of reinforcing stimuli decreases their effectiveness and that these decreases are described by the behavioral characteristics of habituation (McSweeney and Murphy, 2009;Rankin et al., 2009. We describe a neural model that postulates a positive association between dopamine neurotransmission and HRE. We present evidence that stimulant drugs, which artificially increase dopamine neurotransmission, disrupt (slow normally occurring HRE and also provide evidence that stimulant drugs have differential effects on operant responding maintained by reinforcers with rapid vs. slow HRE rates. We hypothesize that abnormal HRE due to genetic and/or environmental factors may underlie some behavioral disorders. For example, recent research indicates that slow-HRE is predictive of obesity. In contrast ADHD may reflect ‘accelerated-HRE’. Consideration of HRE is important for the development of effective reinforcement based treatments. Finally, we point out that most of the reinforcing stimuli that regulate daily behavior are non-consumable environmental/social reinforcers which have rapid-HRE. The almost exclusive use of consumable reinforcers with slow-HRE in pre-clinical studies with animals may have caused the importance of HRE to be overlooked. Further study of reinforcing stimuli with rapid-HRE is needed in order to understand how habituation and reinforcement interact and regulate behavior.

  14. Glass fiber-reinforced abutments for dental implants. A pilot study.

    Science.gov (United States)

    Behr, M; Rosentritt, M; Lang, R; Handel, G

    2001-04-01

    Titanium abutments in dental implants shine through all-ceramic crowns and therefore limit excellent esthetic results. Prototypes of tooth-colored fiber-reinforced abutments were investigated to avoid the shining-through effect. In vitro, the fracture strength was determined after thermal cycling and mechanical loading of all-ceramic single crowns and four-unit bridges made of a fiber-reinforced composite. The suprastructures were adhesively fixed onto fiber-reinforced implant abutments and compared with those fixed on standard titanium abutments. The median of the fracture strength of the titanium-supported all-ceramic crowns was significantly higher than the median of crowns fixed onto the prototypes. But this value was still more than twice as high as the maximum loading force under oral conditions. No statistical difference was found between four-unit bridges made by fiber-reinforced composite inserted onto titanium abutments and those inserted onto fiber-reinforced abutments. Fiber-reinforced abutment prototypes for dental implants avoided the shining-through effect associated with metal abutments. Their load-bearing capacity after in vitro stress simulation was higher than the maximum oral loading force. With some improvements, the fiber-reinforced implant abutments are therefore a promising alternative to titanium abutments. PMID:11251668

  15. Ceramic Technology Project

    Energy Technology Data Exchange (ETDEWEB)

    1992-03-01

    The Ceramic Technology Project was developed by the USDOE Office of Transportation Systems (OTS) in Conservation and Renewable Energy. This project, part of the OTS's Materials Development Program, was developed to meet the ceramic technology requirements of the OTS's automotive technology programs. Significant accomplishments in fabricating ceramic components for the USDOE and NASA advanced heat engine programs have provided evidence that the operation of ceramic parts in high-temperature engine environments is feasible. These programs have also demonstrated that additional research is needed in materials and processing development, design methodology, and data base and life prediction before industry will have a sufficient technology base from which to produce reliable cost-effective ceramic engine components commercially. A five-year project plan was developed with extensive input from private industry. In July 1990 the original plan was updated through the estimated completion of development in 1993. The objective is to develop the industrial technology base required for reliable ceramics for application in advanced automotive heat engines. The project approach includes determining the mechanisms controlling reliability, improving processes for fabricating existing ceramics, developing new materials with increased reliability, and testing these materials in simulated engine environments to confirm reliability. Although this is a generic materials project, the focus is on the structural ceramics for advanced gas turbine and diesel engines, ceramic bearings and attachments, and ceramic coatings for thermal barrier and wear applications in these engines. To facilitate the rapid transfer of this technology to US industry, the major portion of the work is being done in the ceramic industry, with technological support from government laboratories, other industrial laboratories, and universities.

  16. Nanocrystalline magnetic alloys and ceramics

    Indian Academy of Sciences (India)

    M Pal; D Chakravorty

    2003-02-01

    Magnetic properties of materials in their nanocrystalline state have assumed significance in recent years because of their potential applications. A number of techniques have been used to prepare nanocrystalline magnetic phases. Melt spinning, high energy ball milling, sputtering, glassceramization and molecular beam epitaxy are some of the physical methods used so far. Among the chemical methods, sol-gel and co-precipitation routes have been found to be convenient. Ultrafine particles of both ferro- and ferrimagnetic systems show superparamagnetic behaviour at room temperature. Coercivity $(H_c)$ and maximum energy product $(BH)_{\\text{max}}$ of the magnetic particles can be changed by controlling their sizes. The present paper reviews all these aspects in the case of nanocrystalline magnetic systems — both metallic and ceramics.

  17. Verification of ceramic structures

    NARCIS (Netherlands)

    Behar-Lafenetre, S.; Cornillon, L.; Rancurel, M.; Graaf, D. de; Hartmann, P.; Coe, G.; Laine, B.

    2012-01-01

    In the framework of the "Mechanical Design and Verification Methodologies for Ceramic Structures" contract [1] awarded by ESA, Thales Alenia Space has investigated literature and practices in affiliated industries to propose a methodological guideline for verification of ceramic spacecraft and instr

  18. USTUR case 0259 whole body donation: a comprehensive test of the current ICRP models for the behavior of inhaled 238PuO2 ceramic particles. U.S. Transuranium and Uranium Registries.

    Science.gov (United States)

    James, A C; Filipy, R E; Russell, J J; McInroy, J F

    2003-01-01

    An analysis of 238Pu in the whole body donation to the U.S. Transuranium and Uranium Registries (USTUR) is presented. This donor accidentally inhaled an unusual physical form of plutonium, predominantly the 238Pu isotope in the form of a highly insoluble ceramic. Along with six other workers accidentally exposed at the same time, this donor excreted little or no 238Pu in his urine for several months. Subsequently, however, and, with no further intakes, the urinary excretion of 238Pu by all of these workers increased progressively. Such a pattern of increasing urinary excretion of plutonium resulting from a single acute inhalation was unknown at the time. The subject of this study provided a unique opportunity to analyze not only the pattern of urinary excretion for 17 y following this unusual intake but also the complete distribution of 238Pu in his donated body tissues and skeleton at death. Radiochemical analyses of tissues from this whole body donation were used to perform critical tests of the applicability and accuracy of the respiratory tract model and the systemic biokinetic models for plutonium currently recommended by the International Commission on Radiological Protection. The respiratory tract model was applied to analyze the donor's long-term urinary excretion pattern. The facility provided by this model to represent progressive transformation of insoluble particles in the lungs into a more soluble form, applied in conjunction with the systemic biokinetic model, predicted the total amount of 238Pu measured in the donor's body to within 17% accuracy. The measured division of 238Pu between the donor's lungs and systemic organs was predicted to within 10%. Small adjustments to several rate constants in these models provided precise predictions of the absolute amounts of 238Pu in the lungs, thoracic lymph nodes, liver, red bone marrow, skeleton (including the distribution of 238Pu between trabecular and cortical bone matrices derived from the radiochemical

  19. Performance studies of scintillating ceramic samples exposed to ionizing radiation

    CERN Document Server

    Dissertori, G; Nessi-Tedaldi, F; Wallny, R

    2014-01-01

    Scintillating ceramics are a promising, new development for various applications in science and industry. Their application in calorimetry for particle physics experiments is expected to involve an exposure to high levels of ionizing radiation. In this paper, changes in performance have been measured for scintillating ceramic samples of different composition after exposure to penetrating ionizing radiation up to a dose of 38 kGy. 2012 IEEE Nuclear Science Symposium Conference Record

  20. Performance studies of scintillating ceramic samples exposed to ionizing radiation

    CERN Document Server

    Dissertori, G; Nessi-Tedaldi, F; Pauss, F; Wallny, R

    2012-01-01

    Scintillating ceramics are a promising, new development for various applications in science and industry. Their application in calorimetry for particle physics experiments is expected to involve an exposure to high levels of ionizing radiation. In this paper, changes in performance have been measured for scintillating ceramic samples of different composition after exposure to penetrating ionizing radiation up to a dose of 38 kGy.

  1. Ceramics As Materials Of Construction

    OpenAIRE

    Zaki, A.; Eteiba, M. B.; Abdelmonem, N.M.

    1988-01-01

    This paper attempts to review the limitations for using the important ceramics in contact with corrosive media. Different types of ceramics are included. Corrosion properties of ceramics and their electrical properties are mentioned. Recommendations are suggested for using ceramics in different media.

  2. Radiation Effects in Ceramics II.A Comparison of the Effects of Neutron and other Radiation Sources on the Properties of Ceramic Insulators

    OpenAIRE

    Pells, G.P.; Shikama, T.

    1994-01-01

    The interaction of various types of radiation with matter is briefly summarized with particular emphasis on those effects peculiar to polyatomic ceramic insulators. A comparison is amde between neutron and other energetic particles on the swelling behavior of alumina(Al2O3), which is the strongest candidate ceramic for fusion reactor applications.

  3. Bond strength of resin cements to leucitereinforced ceramics

    Directory of Open Access Journals (Sweden)

    Rubens Nazareno Garcia

    2012-06-01

    Full Text Available Objective: The aim of this study was to evaluate the shear bond strength (SBS of two resin cements to four leucite-reinforced ceramics. Material and methods: Forty ceramic blocks (4 mm wide, 14 mm length and 2 mm thick were used and the samples abraded with aluminum oxide (90 µm. The samples were divided into eight groups (n = 5. Two resin cements (conventional RelyX ARC and self-adhesive RelyX U100 – 3M ESPE were bonded to Creapress (CRE-Creation/Klema, Finesse All-Ceramic (FIN-Dentsply/ Ceramco, IPS Empress Esthetic (IEE-Ivoclar Vivadent and Vita PM9 (PM9-Vita. For all groups and in each ceramic block, after application of 10% hydrofluoric acid and silanation, three Tygon tubings were positioned over the ceramics, which were filled in with the resin cements (light-cure for 40 s. The tubings were removed to expose the specimens in format of cylinders (area: 0.38 mm2 and samples were stored in relative humidity at 24±2 °C for one week. After this period, each sample was attached to testing machine and the specimens were submitted to shear bond test (applied at the base of the specimen/cement cylinder with a thin wire/0.2 mm at speed of 0.5 mm/ min, until failure. The results were analyzed by two-way ANOVA (resin cements and ceramic systems and Tukey test (p<0.05. Results: The means (SD were (in MPa: ARC + CRE = 32.1±4.3; ARC + FIN = 28.3±3.7; ARC + IEE = 25.9±4.4; ARC + PM9 = 22.2±2.1; U100 + CRE = 38.0±5.2; U100 + FIN = 36.9±2.8; U100 + IEE = 38.4±2.9; U100 + PM9 = 34.3 ±7.3. U100 showed higher SBS to ceramics than ARC. U100 had higher SBS when applied on IEE ceramic than on PM9. For ARC, SBS obtained with CRE was higher than with IEE and PM9. Conclusion: RelyX U100 can provide higher SBS to leucite-reinforced ceramics than conventional resin cement. The resin cements applied on the PM9 ceramic surface resulted in lower SBS.

  4. Choice and multiple reinforcers

    OpenAIRE

    Moore, Jay

    1982-01-01

    Pigeons chose between equivalent two-component mixed and multiple terminal-link schedules of reinforcement in the concurrent-chains procedure. The pigeons preferred the multiple schedule over the mixed when the components of the compound schedules were differentiated in terms of density of reinforcement, but the pigeons were indifferent when the components were differentiated in terms of number of reinforcers per cycle. Taken together, these results indicate that a local variable, the interva...

  5. Additive Manufacturing of SiC Based Ceramics and Ceramic Matrix Composites

    Science.gov (United States)

    Halbig, Michael Charles; Singh, Mrityunjay

    2015-01-01

    Silicon carbide (SiC) ceramics and SiC fiber reinforcedSiC ceramic matrix composites (SiCSiC CMCs) offer high payoff as replacements for metals in turbine engine applications due to their lighter weight, higher temperature capability, and lower cooling requirements. Additive manufacturing approaches can offer game changing technologies for the quick and low cost fabrication of parts with much greater design freedom and geometric complexity. Four approaches for developing these materials are presented. The first two utilize low cost 3D printers. The first uses pre-ceramic pastes developed as feed materials which are converted to SiC after firing. The second uses wood containing filament to print a carbonaceous preform which is infiltrated with a pre-ceramic polymer and converted to SiC. The other two approaches pursue the AM of CMCs. The first is binder jet SiC powder processing in collaboration with rp+m (Rapid Prototyping+Manufacturing). Processing optimization was pursued through SiC powder blending, infiltration with and without SiC nano powder loading, and integration of nanofibers into the powder bed. The second approach was laminated object manufacturing (LOM) in which fiber prepregs and laminates are cut to shape by a laser and stacked to form the desired part. Scanning electron microscopy was conducted on materials from all approaches with select approaches also characterized with XRD, TGA, and bend testing.

  6. Influence of resin cement shade on the color and translucency of ceramic veneers

    Science.gov (United States)

    HERNANDES, Daiana Kelly Lopes; ARRAIS, Cesar Augusto Galvão; de LIMA, Erick; CESAR, Paulo Francisco; RODRIGUES, José Augusto

    2016-01-01

    ABSTRACT Objective This in vitro study evaluated the effect of two different shades of resin cement (RC- A1 and A3) layer on color change, translucency parameter (TP), and chroma of low (LT) and high (HT) translucent reinforced lithium disilicate ceramic laminates. Material and Methods One dual-cured RC (Variolink II, A1- and A3-shade, Ivoclar Vivadent) was applied to 1-mm thick ceramic discs to create thin RC films (100 µm thick) under the ceramics. The RC was exposed to light from a LED curing unit. Color change (ΔE) of ceramic discs was measured according to CIEL*a*b* system with a standard illuminant D65 in reflectance mode in a spectrophotometer, operating in the light range of 360-740 nm, equipped with an integrating sphere. The color difference between black (B) and white (W) background readings was used for TP analysis, while chroma was calculated by the formula C* ab=(a*2+b*2)½. ΔE of 3.3 was set as the threshold of clinically unacceptable. The results were evaluated by two-way ANOVA followed by Tukey's post hoc test. Results HT ceramics showed higher ΔE and higher TP than LT ceramics. A3-shade RC promoted higher ΔE than A1-shade cement, regardless of the ceramic translucency. No significant difference in TP was noted between ceramic discs with A1- and those with A3-shade cement. Ceramic with underlying RC showed lower TP than discs without RC. HT ceramics showed lower chroma than LT ceramics, regardless of the resin cement shade. The presence of A3-shade RC resulted in higher chroma than the presence of A1-shade RC. Conclusions Darker underlying RC layer promoted more pronounced changes in ceramic translucency, chroma, and shade of high translucent ceramic veneers. These differences may not be clinically differentiable. PMID:27556211

  7. Current Progress in Bioactive Ceramic Scaffolds for Bone Repair and Regeneration

    Directory of Open Access Journals (Sweden)

    Chengde Gao

    2014-03-01

    Full Text Available Bioactive ceramics have received great attention in the past decades owing to their success in stimulating cell proliferation, differentiation and bone tissue regeneration. They can react and form chemical bonds with cells and tissues in human body. This paper provides a comprehensive review of the application of bioactive ceramics for bone repair and regeneration. The review systematically summarizes the types and characters of bioactive ceramics, the fabrication methods for nanostructure and hierarchically porous structure, typical toughness methods for ceramic scaffold and corresponding mechanisms such as fiber toughness, whisker toughness and particle toughness. Moreover, greater insights into the mechanisms of interaction between ceramics and cells are provided, as well as the development of ceramic-based composite materials. The development and challenges of bioactive ceramics are also discussed from the perspective of bone repair and regeneration.

  8. Fabrication and characterization of spark plasma sintered Ce:LuAG ceramic for scintillation application

    Science.gov (United States)

    Kumar, S. Arun; Senthilselvan, J.

    2016-05-01

    Rare earth Cerium doped Lutetium Aluminum Garnet (Ce:LuAG) ceramics are widely used as phosphor material in medical imaging and high-energy physics. Due to its technological importance, an attempt has been made to fabricate Ce:LuAG ceramics by using spark plasma sintering (SPS) technique. XRD patterns of SPS sintered Ce:LuAG ceramics reveals a mixed LuAG and CeO2 (antisite defect) phases. The microstructures of SPS sintered Ce:LuAG ceramics shows limited densification, inappropriate compaction of particles and existence of residual pores, voids between the grain boundaries affects the transparency of Ce:LuAG ceramics. Relative density and hardness of post sintered Ce:LuAG ceramic is also determined. The effect of Ce3+ doping concentration and sintering temperature on optical luminescence behavior of Ce:LuAG ceramic is presented.

  9. Application of pressure infiltration to the manufacturing of aluminium matrix composite materials with different reinforcement shape

    OpenAIRE

    L.A. Dobrzański; M. Kremzer; Nagel, A.

    2007-01-01

    Purpose: The purpose of this work is to investigate the influence of reinforcing phase’s shape on structure and properties of composite materials with aluminium alloy matrix.Design/methodology/approach: The material for studies was produced by a method of pressure infiltration of the porous ceramic framework. In order to investigate the influence of reinforcing phase’s shape the comparison was made between the properties of the composite material based on preforms obtained by Al2O3 Alcoa CL...

  10. Reinforcement of Conducting Silver-based Materials

    Directory of Open Access Journals (Sweden)

    Heike JUNG

    2014-09-01

    Full Text Available Silver is a well-known material in the field of contact materials because of its high electrical and thermal conductivity. However, due to its bad mechanical and switching properties, silver alloys or reinforcements of the ductile silver matrix are required. Different reinforcements, e. g. tungsten, tungsten carbide, nickel, cadmium oxide or tin oxide, are used in different sectors of switches. To reach an optimal distribution of these reinforcements, various manufacturing techniques (e. g. powder blending, preform infiltration, wet-chemical methods, internal oxidation are being used for the production of these contact materials. Each of these manufacturing routes offers different advantages and disadvantages. The mechanical alloying process displays a successful and efficient method to produce particle-reinforced metal-matrix composite powders. This contribution presents the obtained fine disperse microstructure of tungsten-particle-reinforced silver composite powders produced by the mechanical alloying process and displays this technique as possible route to provide feedstock powders for subsequent consolidation processes. DOI: http://dx.doi.org/10.5755/j01.ms.20.3.4889

  11. High pressure ceramic joint

    Science.gov (United States)

    Ward, Michael E.; Harkins, Bruce D.

    1993-01-01

    Many recuperators have components which react to corrosive gases and are used in applications where the donor fluid includes highly corrosive gases. These recuperators have suffered reduced life, increased service or maintenance, and resulted in increased cost. The present joint when used with recuperators increases the use of ceramic components which do not react to highly corrosive gases. Thus, the present joint used with the present recuperator increases the life, reduces the service and maintenance, and reduces the increased cost associated with corrosive action of components used to manufacture recuperators. The present joint is comprised of a first ceramic member, a second ceramic member, a mechanical locking device having a groove defined in one of the first ceramic member and the second ceramic member. The joint and the mechanical locking device is further comprised of a refractory material disposed in the groove and contacting the first ceramic member and the second ceramic member. The present joint mechanically provides a high strength load bearing joint having good thermal cycling characteristics, good resistance to a corrosive environment and good steady state strength at elevated temperatures.

  12. Ceramic matrix composites (continuous fiber reinforced) thermal protection systems

    Science.gov (United States)

    Riccitiello, Salvatore R.

    1993-01-01

    Concluded remarks are: (1) advanced carbon-carbon (ACC) substrate fabrication technology in good shape; (2) ACC coating improvements satisfactory but additional work needed; (3) non-destructive test techniques to monitor hardware during operational life needed; and (4) cost reduction approaches a high priority.

  13. Residual stress and wear resistance of WC particle reinforced Ni-based coating%W C颗粒增强 Ni基涂层的残余应力及耐磨性能

    Institute of Scientific and Technical Information of China (English)

    郭华锋; 李菊丽; 孙涛; 杨海峰

    2014-01-01

    Microstructure of WC particle reinforced Ni-based plasma-sprayed coating was observed by scanning electron microscope (SEM). Surface residual stress of the coating with different WC content and the bonding layer were tested by X -ray diffraction ( XRD) method. Microhardness and wear mechanism of the coating were studied by friction and wear test machine and confocal laser scanning microscope .The results show that the surface residual stress of the coatings are compressive stress and decreased with the increase of WC content .However, residual stress increase with the increase of thickness of coatings and when thickness is 1000 μm, the coating appears delamination failure . The thermal stress is the largest contributive factor to residual stress of the bonding layer .A certain amplitude of compressive stress is beneficial to improve abrasion resistance of the coating .The wear loss of the coating is only about 0.135 times of that of the substrate under the same loading .The wear mechanism of the coating is mainly abrasive wear .%用扫描电子显微镜( SEM)观察了等离子喷涂WC颗粒增强Ni涂层的显微结构,用X射线衍射法( XRD)测试了不同WC含量下涂层及粘结层表面残余应力,利用摩擦磨损试验机和共聚焦激光扫描显微镜研究了涂层的磨损机制。结果表明:涂层表面残余应力为压应力,且随着WC含量的增加先增大后减小,随着涂层厚度的增加而增大,厚度为1000μm时出现分层失效,热应力对粘结层残余应力的贡献最大。一定幅值的压应力有利于涂层耐磨性的提高,同载荷下磨损量仅为基体的0.135倍,涂层磨损机制主要为磨粒磨损。

  14. Studying the Effect of Addition Particles of Alumina (Al2O3

    Directory of Open Access Journals (Sweden)

    Sarmad I. Ibrahim

    2011-01-01

    Full Text Available This study is concerned with the effect of adding two kinds of ceramic materials on the mechanical properties of (Al-7%Si- 0.3%Mg alloy, which are zirconia with particle size (20?m > P.S ? 0.1?m and alumina with particle size (20?m > P.S ? 0.1?m and adding them to the alloy with weight ratios (0.2, 0.4, 0.6, 0.8 and 1%. Stirring casting method has been used to make composite material by using vortex technique which is used to pull the particles to inside the melted metals and distributed them homogenously.After that solution treatment was done to the samples at (520ºC and artificial ageing at (170ºC in different times, it has been noticed that the values of hardness is increased with the aging time of the original alloy and reached its highest value after (8hr.Mechanical tests were done to the original alloy and the composite material at the maximum hardness value and represented by tensile, hardness, and wear tests. It was found that the hardness value is increased with increment of the amount of added particles; also the increment in the hardness of the alloy which is reinforced with alumina is more than that reinforced with zirconia.Regarding the tensile test, results show that the strength and yield resistance of the composite material are more than that in the original alloy and these values are increased with increasing the amount of the added particles and they reached maximum values at (0.6%. Then they are decreased but these values remain at higher values than those in the original alloy. However, the ductility is decreased as compared with the original alloy and this decrement was more obvious with the increasing amount of the added particles. The increment of strength and yield resistance of the alloy reinforced by alumina was higher than that reinforced with zirconia, while the ductility of the alloy reinforced by zirconia was higher than that happened by the addition of alumina. Also zirconia and alumina addition to the original

  15. Refractory ceramics to silicon carbide. 5. tot. rev. ed

    Energy Technology Data Exchange (ETDEWEB)

    Elvers, B. (ed.); Hawkins, S. (ed.); Russey, W. (ed.); Schulz, G. (ed.)

    1993-01-01

    This volume contains 28 contributions to the following topics: Refractory Ceramics, Reinforced Plastics; Release Agents; Resins, Natural; Resins, Synthetic; Resorcinol; Resources of Oil and Gas; Rhenium and Rhenium Compounds; Rodenticides; Rubber (1. Survey, 2. Natural, 3. Synthetic, 4. Chemicals, 5. Technology, 6. Testing); Rubidium and Rubidium Compounds; Salicylic Acid; Saponins; Sealing Materials; Seasonings; Sedatives; Selenium and Selenium Compounds; Semiconductors; Shoe Polishes; Silica; Silicates; Silicon; Silicon Carbide. (orig.)

  16. Study on Microstructure of Alumina Based Rare Earth Ceramic Composite

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Analysis techniques such as SEM, TEM and EDAX were used to investigate the microstructure of rare earth reinforced Al2O3/(W, Ti)C ceramic composite. Chemical and physical compatibility of the composite was analyzed and interfacial microstructure was studied in detail. It is found that both Al2O3 and (W, Ti)C phases are interlaced with each other to form the skeleton structure in the composite. A small amount of pores and glass phases are observed inside the material which will inevitably influence the physical and mechanical property of the composite. Thermal residual stresses resulted from thermal expansion mismatch can then lead to the emergence of dislocations and microcracks. Interfaces and boundaries of different types are found to exist inside the Al2O3/(W, Ti)C rare earth ceramic composite, which is concerned with the addition of rare earth element and the extent of solid solution of ceramic phases.

  17. CAD/CAM fabricated single-unit all-ceramic post-core-crown restoration

    Directory of Open Access Journals (Sweden)

    Thilla Sekar Vinothkumar

    2011-01-01

    Full Text Available This case report explains about an innovative treatment strategy for the management of damaged anterior teeth with reduced incisal clearance by means of a single-unit all-ceramic post-core-crown zirconia ceramic restoration fabricated by Computer-aided designing and computer-aided manufacturing (CAD/CAM technology. The reinforced zirconia ceramics allow fabrication of durable esthetic restorations in cases with high functional loading and the unification of the post, core, and crown in a single unit decreases the frequency of failure by creating a monobloc effect. In addition, the use of CAD/CAM technology for designing and fabricating ceramic restorations offers the option of expeditiously preparing these high-strength all-ceramic restorations.

  18. CAD/CAM fabricated single-unit all-ceramic post–core–crown restoration

    Science.gov (United States)

    Vinothkumar, Thilla Sekar; Kandaswamy, Deivanayagam; Chanana, Pallavi

    2011-01-01

    This case report explains about an innovative treatment strategy for the management of damaged anterior teeth with reduced incisal clearance by means of a single-unit all-ceramic post–core–crown zirconia ceramic restoration fabricated by Computer-aided designing and computer-aided manufacturing (CAD/CAM) technology. The reinforced zirconia ceramics allow fabrication of durable esthetic restorations in cases with high functional loading and the unification of the post, core, and crown in a single unit decreases the frequency of failure by creating a monobloc effect. In addition, the use of CAD/CAM technology for designing and fabricating ceramic restorations offers the option of expeditiously preparing these high-strength all-ceramic restorations. PMID:21691515

  19. The APS ceramic chambers

    Energy Technology Data Exchange (ETDEWEB)

    Milton, S.; Warner, D.

    1994-07-01

    Ceramics chambers are used in the Advanced Photon Source (APS) machines at the locations of the pulsed kicker and bumper magnets. The ceramic will be coated internally with a resistive paste. The resistance is chosen to allow the low frequency pulsed magnet field to penetrate but not the high frequency components of the circulating beam. Another design goal was to keep the power density experienced by the resistive coating to a minimum. These ceramics, their associated hardware, the coating process, and our recent experiences with them are described.

  20. Oxygen Transport Ceramic Membranes

    Energy Technology Data Exchange (ETDEWEB)

    S. Bandopadhyay; T. Nithyanantham; X.-D Zhou; Y-W. Sin; H.U. Anderson; Alan Jacobson; C.A. Mims

    2005-08-01

    The present quarterly report describes some of the investigations on the structural properties of dense OTM bars provided by Praxair and studies on newer composition of Ti doped LSF. In the previous research, the reference point of oxygen occupancy was determined and verified. In the current research, the oxygen occupancy was investigated at 1200 C as a function of oxygen activity and compared with that at 1000 C. The cause of bumps at about 200 C was also investigated by using different heating and cooling rates during TGA. The fracture toughness of LSFT and dual phase membranes at room temperature is an important mechanical property. Vicker's indentation method was used to evaluate this toughness. Through this technique, a K{sub Ic} (Mode-I Fracture Toughness) value is attained by means of semi-empirical correlations between the indentation load and the length of the cracks emanating from the corresponding Vickers indentation impression. In the present investigation, crack propagation behavior was extensively analyzed in order to understand the strengthening mechanisms involved in the non-transforming La based ceramic composites. Cracks were generated using Vicker's indenter and used to identify and evaluate the toughening mechanisms involved. Preliminary results of an electron microscopy study of the origin of the slow kinetics on reduction of ferrites have been obtained. The slow kinetics appear to be related to a non-equilibrium reduction pathway that initially results in the formation of iron particles. At long times, equilibrium can be reestablished with recovery of the perovskite phase. Modeling of the isotopic transients on operating membranes (LSCrF-2828 at 900 C) and a ''frozen'' isotope profile have been analyzed in conjunction with a 1-D model to reveal the gradient in oxygen diffusivity through the membrane under conditions of high chemical gradients.

  1. Effect of Microstructure of Composite Powders on Microstructure and Properties of Microwave Sintered Alumina Matrix Ceramics

    Institute of Scientific and Technical Information of China (English)

    Hanmin Bian; Yong Yang; You Wang; Wei Tian; Haifu Jiang; Zhijuan Hu; Weimin Yu

    2013-01-01

    Two kinds of different structured alumina-titania composite powders were used to prepare alumina matrix ceramics by microwave sintering.One was powder mixture of alumina and titania at a micron-submicron level,in which fused-and-crushed alumina particles (micrometers) was clad with submicron-sized titania.The other was powder mixture of alumina and titania at nanometer-nanometer level,in which nano-sized alumina and nano-sized titania particles were homogeneously mixed by ball-milling and spray dried to prepare spherical alumina-titania composite powders.The effect of the microstructure of composite powders on microstructure and properties of microwave sintered alumina matrix ceramics were investigated.Nano-sized composite (NC) powder showed enhanced sintering behavior compared with micro-sized composite (MC) powders.The asprepared NC ceramic had much denser,finer and more homogenous microstructure than MC ceramic.The mechanical properties of NC ceramic were significantly higher than that of MC ceramic,e.g.the flexural strength,Vickers hardness and fracture toughness of NC ceramic were 85.3%,130.3% and 25.7% higher than that of MC ceramic,respectively.The improved mechanical properties of NC ceramic compared with that of MC ceramic were attributed to the enhanced densification and the finer and more homogeneous microstruc.ture through the use of the nanostructured composite powders.

  2. High volume intermetallics reinforced Ti-based composites in situ synthesized from Ti-Si-Sn ternary system

    International Nuclear Information System (INIS)

    Research highlights: → Ti-based composites reinforced with 20-40 vol.% eutectic Ti5Si3 or Ti3Sn + Ti5Si3 intermetallics were in situ synthesized. → Significant increase of Young's modulus and ultimate compressive strength was obtained. → Modification of the shape and interface of the intermetallic particles can further improve the mechanical properties. - Abstract: Ti-based alloys or composites reinforced with high fraction of intermetallic or ceramic phases may be good candidate for aerospace components operating under vibration and extremely difficult environments that require high strength, elasticity and damping capacity. In the present work, Ti-based composites reinforced with eutectic Ti5Si3 or Ti3Sn + Ti5Si3 intermetallics with volume fraction up to 20-40% have been synthesized from the Ti-Si-Sn ternary system, through non-consumable vacuum arc melting. The composites exhibit a hyporeutectic microstructure with primary Ti solid solution or/and Ti3Sn phases, plus an (α-Ti + Ti5Si3) eutectic. The results of room-temperature compressive test show that the composites exhibit significant increase of Young's modulus and higher ultimate compressive strength (UCS) than the Ti-Si hypoeutectic alloy, which can be attributed to the presence of intermetallics i.e. Ti5Si3 or (Ti3Sn + Ti5Si3) and the solute atom Sn in the Ti matrix. It is implied from the fractography that modification of the shape and interface of the intermetallics particles can further improve the mechanical properties of the Ti-based composites.

  3. Application of the analysis of variance for the determination of reinforcement structure homogeneity in MMC

    OpenAIRE

    K. Gawdzińska; S. Berczyński; M. Pelczar; J. Grabian

    2010-01-01

    These authors propose a new definition of homogeneity verified by variance analysis. The analysis aimed at quantitative variables describing the homogeneity of reinforcement structure, i.e. surface areas, reinforcement phase diameter and percentage of reinforcement area contained in a circle within a given region. The examined composite material consisting of silicon carbide reinforcement particles in AlSi11 alloy matrix was made by mechanical mixing.

  4. Composite Intersection Reinforcement

    Science.gov (United States)

    Misciagna, David T. (Inventor); Fuhrer, Jessica J. (Inventor); Funk, Robert S. (Inventor); Tolotta, William S. (Inventor)

    2013-01-01

    An assembly and method for manufacturing a composite reinforcement for unitizing a structure are provided. According to one embodiment, the assembly includes a base having a plurality of pins extending outwardly therefrom to define a structure about which a composite fiber is wound to define a composite reinforcement preform. The assembly also includes a plurality of mandrels positioned adjacent to the base and at least a portion of the composite reinforcement preform, and a cap that is positioned over at least a portion of the plurality of mandrels. The cap is configured to engage each of the mandrels to support the mandrels and the composite reinforcement preform during a curing process to form the composite reinforcement.

  5. "Reinforcement" in behavior theory.

    Science.gov (United States)

    Schoenfeld, W N

    1978-01-01

    In its Pavlovian context, "reinforcement" was actually a descriptive term for the functional relation between an unconditional and a conditional stimulus. When it was adopted into operant conditioning, "reinforcement" became the central concept and the key operation, but with new qualifications, new referents, and new expectations. Some behavior theorists believed that "reinforcers" comprise a special and limited class of stimuli or events, and they speculated about what the essential "nature of reinforcement" might be. It is now known that any stimulus can serve a reinforcing function, with due recognition of such parameters as subject species characteristics, stimulus intensity, sensory modality, and schedule of application. This paper comments on these developments from the standpoint of reflex behavior theory.

  6. Ceramic Solar Receiver

    Science.gov (United States)

    Robertson, C., Jr.

    1984-01-01

    Solar receiver uses ceramic honeycomb matrix to absorb heat from Sun and transfer it to working fluid at temperatures of 1,095 degrees and 1,650 degrees C. Drives gas turbine engine or provides heat for industrial processes.

  7. Advanced Ceramics Property Measurements

    Science.gov (United States)

    Salem, Jonathan; Helfinstine, John; Quinn, George; Gonczy, Stephen

    2013-01-01

    Mechanical and physical properties of ceramic bodies can be difficult to measure correctly unless the proper techniques are used. The Advanced Ceramics Committee of ASTM, C-28, has developed dozens of consensus test standards and practices to measure various properties of a ceramic monolith, composite, or coating. The standards give the "what, how, how not, and why" for measurement of many mechanical, physical, thermal, and performance properties. Using these standards will provide accurate, reliable, and complete data for rigorous comparisons with other test results from your test lab, or another. The C-28 Committee has involved academics, producers, and users of ceramics to write and continually update more than 45 standards since the committee's inception in 1986. Included in this poster is a pictogram of the C-28 standards and information on how to obtain individual copies with full details or the complete collection of standards in one volume.

  8. Making Ceramic Cameras

    Science.gov (United States)

    Squibb, Matt

    2009-01-01

    This article describes how to make a clay camera. This idea of creating functional cameras from clay allows students to experience ceramics, photography, and painting all in one unit. (Contains 1 resource and 3 online resources.)

  9. Effect of SiC particles on crack susceptivity in laser direct forming Al2O3 ceramic%SiC颗粒掺杂对激光直接成形Al2O3陶瓷裂纹敏感性的影响

    Institute of Scientific and Technical Information of China (English)

    吴东江; 杨策; 吴楠; 郭玉泉; 马广义; 郭东明

    2012-01-01

    The toughening effect of SiC particles was applied to inhibition of the cracks in A12O3 ceramic for Laser Direct Forming (LDF). The experiments of coaxial laser cladding A12O3 ceramic added SiC particles were performed on the Ti-6A1-4V alloy substrate to investigate the feasibility of A12O3 + SiC composite ceramic by LDF and explore the factors effecting on the crack susceptivity. The cracks, microstructures and the combining of the two compositions were observed by an optical microscopy, and the phase transitions were detected by X-ray diffraction. The results show that some complete SiC particles contained in the A12O3 ceramic can inhibit the cracks, and the Al2O3+SiC composite ceramic without serious chemical reactions or combining defects can be prepared. The crack susceptivity is significantly affected by the proportion of SiC (f), laser power (P), scanning velocity (v) and the pow-der flow rate (n). Finally, a thin-wall Al2O3+SiC composite ceramic block(17 mm×6 mm×2 mm) without the obvious defects was formed with the parameters of f,P, v and n in 10%(weight proportion) , 186 W, 300 mm/min and 1. 78 g/min, respectively.%为抑制激光直接成形Al2O3陶瓷过程中的裂纹,利用SiC未熔颗粒的增韧原理,在Ti-6Al-4V合金基底上进行添加SiC颗粒的Al2O3同轴送粉激光直接成形实验,分析了激光直接成形Al2O3+ SiC复相陶瓷的可行性以及成形件裂纹敏感性的影响因素.利用光学显微镜观察薄壁成形试样的裂纹扩展、显微组织和两相结合情况,并使用X射线衍射仪(XRD)进行相分析.结果表明:SiC颗粒可在激光直接成形Al2O3+SiC陶瓷中起到抑制裂纹的作用,并可形成各成分结合良好,无明显化学反应,含有较完整SiC未熔颗粒的复相陶瓷材料.单因素实验显示:SiC比例f、激光功率P、扫描速度v和送粉率n对裂纹敏感性均有显著影响,最后采用工艺参数:f =10%(重量百分比)、P=186 W、v=300 mm/min及n=1.78 g/min成形了

  10. Selecting Ceramics - Introduction

    OpenAIRE

    Cassidy, M.

    2002-01-01

    AIM OF PRESENTATION: To compare a number of materials for extracoronal restoration of teeth with particular reference to CAD-CAM ceramics. CASE DESCRIPTION AND TREATMENT CARRIED OUT: This paper will be illustrated using clinical examples of patients treated using different ceramic restorations to present the advantages and disadvantages and each technique. The different requirements of tooth preparation, impression taking and technical procedures of each system will be presented and compar...

  11. Radiation stability test on multiphase glass ceramic and crystalline ceramic waste forms

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Ming, E-mail: mtang@lanl.gov [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Kossoy, Anna; Jarvinen, Gordon [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Crum, Jarrod; Turo, Laura; Riley, Brian [Pacific Northwest National Laboratory, Richland, WA 99352 (United States); Brinkman, Kyle; Fox, Kevin; Amoroso, Jake; Marra, James [Savannah River National Laboratory, Aiken, SC 29808 (United States)

    2014-05-01

    A radiation stability study was performed on glass ceramic and crystalline ceramic waste forms. These materials are candidate host materials for immobilizing alkali/alkaline earth (Cs/Sr-CS) + lanthanide (LN) + transition metal (TM) fission product waste streams from nuclear fuel reprocessing. In this study, glass ceramics were fabricated using a borosilicate glass as a matrix in which to incorporate CS/LN/TM combined waste streams. The major phases in these multiphase materials are powellite, oxyaptite, pollucite, celsian, and durable residual glass phases. Al{sub 2}O{sub 3} and TiO{sub 2} were combined with these waste components to produce multiphase crystalline ceramics containing hollandite-type phases, perovskites, pyrochlores and other minor metal titanate phases. For the radiation stability test, selected glass ceramic and crystalline ceramic samples were exposed to different irradiation environments including low fluxes of high-energy (∼1–5 MeV) protons and alpha particles generated by an ion accelerator, high fluxes of low-energy (hundreds of keV) krypton particles generated by an ion implanter, and in-situ electron irradiations in a transmission electron microscope. These irradiation experiments were performed to simulate self-radiation effects in a waste form. Ion irradiation-induced microstructural modifications were examined using X-ray diffraction and transmission electron microscopy. Our preliminary results reveal different radiation tolerance in different crystalline phases under various radiation damage environments. However, their stability may be rate dependent which may limit the waste loading that can be achieved.

  12. Wetting and dispersion in ceramic/polymer melt injection molding systems

    Energy Technology Data Exchange (ETDEWEB)

    Sacks, M.D. (Florida Univ., Gainesville, FL (United States). Dept. of Materials Science and Engineering); Williams, J.W. (Florida Univ., Gainesville, FL (United States). Dept. of Materials Science and Engineering 3M Co., St. Paul, MN (United States))

    1993-01-01

    This program had two major areas of emphasis: (1) factors influencing state of particulate dispersion and rheological properties of ceramic powder/polymer melt mixtures, and (2) effect of interfacial bonding strength on mechanical and rheological properties of ceramic particle/polymer composites. Alumina and silica in various polyethylenes were used.

  13. Wetting and dispersion in ceramic/polymer melt injection molding systems. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Sacks, M.D. [Florida Univ., Gainesville, FL (United States). Dept. of Materials Science and Engineering; Williams, J.W. [Florida Univ., Gainesville, FL (United States). Dept. of Materials Science and Engineering]|[3M Co., St. Paul, MN (United States)

    1993-05-01

    This program had two major areas of emphasis: (1) factors influencing state of particulate dispersion and rheological properties of ceramic powder/polymer melt mixtures, and (2) effect of interfacial bonding strength on mechanical and rheological properties of ceramic particle/polymer composites. Alumina and silica in various polyethylenes were used.

  14. Technology Implementation Plan. Fully Ceramic Microencapsulated Fuel for Commercial Light Water Reactor Application

    Energy Technology Data Exchange (ETDEWEB)

    Snead, Lance Lewis [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Terrani, Kurt A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Powers, Jeffrey J. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Worrall, Andrew [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Robb, Kevin R. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Snead, Mary A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2015-04-01

    This report is an overview of the implementation plan for ORNL's fully ceramic microencapsulated (FCM) light water reactor fuel. The fully ceramic microencapsulated fuel consists of tristructural isotropic (TRISO) particles embedded inside a fully dense SiC matrix and is intended for utilization in commercial light water reactor application.

  15. Clinical application of bio ceramics

    Science.gov (United States)

    Anu, Sharma; Gayatri, Sharma

    2016-05-01

    Ceramics are the inorganic crystalline material. These are used in various field such as biomedical, electrical, electronics, aerospace, automotive and optical etc. Bio ceramics are the one of the most active areas of research. Bio ceramics are the ceramics which are biocompatible. The unique properties of bio ceramics make them an attractive option for medical applications and offer some potential advantages over other materials. During the past three decades, a number of major advances have been made in the field of bio ceramics. This review focuses on the use of these materials in variety of clinical scenarios.

  16. Ceramic electrolyte coating and methods

    Science.gov (United States)

    Seabaugh, Matthew M.; Swartz, Scott L.; Dawson, William J.; McCormick, Buddy E.

    2007-08-28

    Aqueous coating slurries useful in depositing a dense coating of a ceramic electrolyte material (e.g., yttrium-stabilized zirconia) onto a porous substrate of a ceramic electrode material (e.g., lanthanum strontium manganite or nickel/zirconia) and processes for preparing an aqueous suspension of a ceramic electrolyte material and an aqueous spray coating slurry including a ceramic electrolyte material. The invention also includes processes for depositing an aqueous spray coating slurry including a ceramic electrolyte material onto pre-sintered, partially sintered, and unsintered ceramic substrates and products made by this process.

  17. Effect of the percentage of reinforcement on the wear in the metal matrix composites sintered with abnormal glow discharge; Efecto del porcentaje de refuerzo frente al desgaste en compuestos de matriz metalica sinterizados con descarga luminiscente anormal

    Energy Technology Data Exchange (ETDEWEB)

    Perez-Velasquez, S.; Pineda-Triana, Y.; Aguilar-Castro, Y.; Vera-Lopez, E.

    2016-05-01

    In this study an analysis of the behavior of dry wear coefficient of a Metal Matrix Composite (MMC) in 316 stainless steel reinforced with particles of titanium carbide (TiC) according to ASTM G 99 standards, in a pin-on-disk test. In this research it is tested the effect of the percentage of reinforcement in the MMC manufactured with 3, 6 y 9% (vol.) of TiC, in samples compacted at 800 MPa, generating different values of grain size, hardness and density, they are sintered with abnormal glow discharge, at a temperature of 1200 degree centigrade ±5 degree centigrade, with a protection atmosphere H{sub 2} - N{sub 2} and a permanence time of 30 minutes. According to the results obtained it is concluded that the best condition for the MMC manufacturing, in relation to the reinforcement percentage, is the one obtained when the mixture contains 6% of TiC compacted at 800 MPa. In these conditions, it was obtained: achieving smaller grain size, the greater hardness and the lowest coefficient of friction. In this respect, it was observed that the incorporation of the ceramic particles (TiC) in a matrix of austenitic steel (316) shows significant improvements in the resistance to the wear. (Author)

  18. Chemisorption and catalytic decrease of sintering temperature for ceramics

    International Nuclear Information System (INIS)

    An explanation is suggested for a sintering temperature decrease in oxide ceramics (76%ZrO2, 19.8%Al2O3, 4.2Y2O3) during ceramic powder processing with carbon tetrachloride. It is shown that chemisorption on surface of powders to be compacted can affect both the density of compacts through a decrease of friction factor between powder particles and the kinetics of sintering through formation of additional vacancies in the process of chemisorbed substance dissolution over the bulk of particles. 6 refs

  19. Dielectric silicone elastomers with mixed ceramic nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Stiubianu, George, E-mail: george.stiubianu@icmpp.ro [“Petru Poni” Institute of Macromolecular Chemistry, Aleea Gr. Ghica Voda 41A, Iasi 700487 (Romania); Bele, Adrian; Cazacu, Maria; Racles, Carmen; Vlad, Stelian [“Petru Poni” Institute of Macromolecular Chemistry, Aleea Gr. Ghica Voda 41A, Iasi 700487 (Romania); Ignat, Mircea [National R& D Institute for Electrical Engineering ICPE-CA Bucharest, Splaiul Unirii 313, District 3, Bucharest 030138 (Romania)

    2015-11-15

    Highlights: • Composite ceramics nanoparticles (MCN) with zirconium dioxide and lead zirconate. • Dielectric elastomer films wDith PDMS matrix and MCN as dielectric filler. • Hydrophobic character—water resistant and good flexibility specific to siloxanes. • Increased value of dielectric constant with the content of MCN in dielectric films. • Increased energy output from uniaxial deformation of the dielectric elastomer films. - Abstract: A ceramic material consisting in a zirconium dioxide-lead zirconate mixture has been obtained by precipitation method, its composition being proved by wide angle X-ray powder diffraction and energy-dispersive X-ray spectroscopy. The average diameter of the ceramic particles ranged between 50 and 100 nm, as revealed by transmission electron microscopy images. These were surface treated and used as filler for a high molecular mass polydimethylsiloxane-α,ω-diol (Mn = 450,000) prepared in laboratory, the resulted composites being further processed as films and crosslinked. A condensation procedure, unusual for polydimethylsiloxane having such high molecular mass, with a trifunctional silane was approached for the crosslinking. The effect of filler content on electrical and mechanical properties of the resulted materials was studied and it was found that the dielectric permittivity of nanocomposites increased in line with the concentration of ceramic nanoparticles.

  20. Alumina reinforced tetragonal zirconia (TZP) composites. Final technical report, July 1, 1993--December 31, 1996

    International Nuclear Information System (INIS)

    This final technical report summarizes the significant research results obtained during the period July 1, 1993 through December 31, 1996 in the DOE-supported research project entitled, open-quotes Alumina Reinforced Tetragonal Zirconia (TZP) Compositesclose quotes. The objective of the research was to develop high-strength and high-toughness ceramic composites by combining mechanisms of platelet, whisker or fiber reinforcement with transformation toughening. The approach used included reinforcement of Celia- or yttria-partially-stabilized zirconia (Ce-TZP or Y-TZP) with particulates, platelets, or continuous filaments of alumina