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1.
Mechanical properties of Al2O3/ZrO2 composites 总被引:1,自引:0,他引:1
W. H. Tuan R. Z. Chen T. C. Wang C. H. Cheng P. S. Kuo 《Journal of the European Ceramic Society》2002,22(16):2827-2833
In the present study, both t-phase zirconia and m-phase zirconia particles are incorporated into an alumina matrix. Dense Al2O3/(t-ZrO2+m-ZrO2) composites were prepared by sintering pressurelessly at 1600 °C. The microstructure of the composites are characterized, the elastic modulus, strength and toughness determined. Because the ZrO2 inclusions are close to each other in the Al2O3 matrix, the yttrium ion originally in t-ZrO2 particles can diffuse to nearby m-ZrO2 particles during sintering, and the m-phase zirconia is thus stabilized after sintering. The strength of the Al2O3/(t-ZrO2+m-ZrO2) composites after surface grinding can reach values as high as 940 MPa, which is roughly three times that of Al2O3 alone. The strengthening effect is contributed by microstructural refinement together with the surface compressive stresses induced by grinding. The toughness of alumina is also enhanced by adding both t-phase and m-phase zirconia, which can reach values as high as two times that of Al2O3 alone. The toughening effect is attributed mainly to the zirconia t–m phase transformation. 相似文献
2.
Three techniques for the determination of KIc in Ce-stabilized ZrO2/Al2O3 composites have been evaluated: the single-edge-notched beam (SENB); the indentation strength in bending (ISB) and the indentation fracture (IF). Comparative measurements, performed on samples prepared by sintering uniaxially pressed powders obtained by a chemical route, showed that whatever the technique used, KIc increased as the Al2O3 grain size decreased.
The three methods give similar results if some procedural improvements are introduced, namely: (i) the polished samples are annealed prior to testing: (ii) a more reproducible notching technique would be developed for the SENB method; and (iii) the crack shape and length are known exactly in the IF technique.
In the IF test, the crack shape profile is of Palmquist type at low indentation loads while a transition to a half-penny-shaped crack occurs at higher loads. 相似文献
3.
A. Licciulli C. Esposito Corcione A. Greco V. Amicarelli A. Maffezzoli 《Journal of the European Ceramic Society》2004,24(15-16):3769-3777
Ceramic laser stereolithography is a manufacturing process suitable candidate for the production of complex shape technical ceramics. The green ceramic is produced layer by layer through laser polymerisation of UV curable ceramic suspensions. A number of critical issues deserve attention: high solid loading and low viscosity of the suspensions, high UV reactivity, prevention of interlayer delamination in the green and in the sintered body, good mechanical performance. In this work, ZrO2-reinforced Al2O3 components have been obtained from an acrylic modified zircon loaded with alumina powders. The zircon compound is effective as organic photoactivated resin and allows the dispersion of a high volume fraction of Al2O3 powder (up to 50 vol.%) while keeping viscosity at reasonable low values. The zircon compound also represents a liquid ceramic precursor that converts to oxide after burning out of the binder. Thank to the good dispersion of the alumina powder in the zircon acrylate, a uniform dispersion of ZrO2 submicron particles is obtained after pyrolysis. These are located at the grain boundaries between alumina grains. Formation of both monoclinic and tetragonal ZrO2 occurs as evidenced by XRD. No delamination occurs in bending tests as evidenced by SEM fractography, satisfactory modulus and strength values were concurrently found. 相似文献
4.
In this paper, Al2O3-Si3N4/ZrO2-Al2O3 laminated composites were fabricated by tape casting and hot press sintering, and the relationships between the process, microstructure, and mechanical properties of Al2O3-Si3N4/ZrO2-Al2O3 laminated composites were determined. The SiAlON phase was found in the Al2O3-Si3N4 layer, and liquid-phase sintering was proposed. Nano-scratch tests were carried out to investigate the interface bonding strength of the laminates. The distribution of residual stresses, generated due to the different coefficients of thermal expansion between the different layers, was estimated according to lamination theory and confirmed using Vickers indentation. When the sintering temperature was 1550 °C, the sintered laminated ceramics had good mechanical properties, with a maximum strength and toughness of 413 MPa and 6.2 MPa m1/2, respectively. The main toughness mechanics of laminated composites was residual stress. 相似文献
5.
Stefan Kbel Juliane Plüschke Ulrich Vogt Thomas J. Graule 《Ceramics International》2004,30(8):2105-2110
Al2O3–MoSi2 composites with MoSi2 volume fractions between 16 and 40% were fabricated from commercial ceramic Al2O3 and intermetallic MoSi2 powders by granulation, cold isostatic pressing and vacuum-sintering. The addition of MoSi2 had only a slight influence on the densification of the composites, with sintered densities of 98% for samples with 16 vol.% MoSi2 and 94% for samples with 40 vol.% MoSi2. Composites with MoSi2 contents of 20 vol.% and higher were electroconductive due to the formation of a three-dimensional percolating network of the conductive MoSi2 phase. 相似文献
6.
This study investigates the effect of the incorporation of alumina particles on the thermomechanical properties of polybutylene succinate (PBS)/Al2O3 composites. The alumina surface was modified with the carboxylic groups of maleic acid through simple acid-base and in situ polymerization reactions. Scanning electron microscope (SEM) results revealed the introduction of maleic acid treated alumina significantly affect the morphology of the PBS/Al2O3 composites as compared to the neat PBS. The thermal conductivity of the composite (0.411?W?m?1 K?1) was more than twice that of neat PBS. The composite containing polymerization-modified alumina showed a 50% increase in storage modulus compared with that of neat PBS. In addition, universal testing machine (UTM) and differential scanning calorimetry (DSC) measurements indicated an increase in the tensile strength and degree of crystallinity after the incorporation of modified alumina in the PBS/Al2O3 composite. 相似文献
7.
S. Santhosh Kumar M. Devaiah V. Seshu BaiT. Rajasekharan 《Ceramics International》2012,38(2):1139-1147
Silicon carbide particulate reinforced alumina matrix composites were fabricated using DIrected Metal OXidation (DIMOX) process. Continuous oxidation of an Al-Si-Mg-Zn alloy with appropriate dopants along with a preform of silicon carbide has led to the formation of alumina matrix surrounding silicon carbide particulates. SiCp/Al2O3 ceramic matrix composites fabricated by the DIMOX process, possess enhanced mechanical properties such as flexural strength, fracture toughness and wear resistance, all at an affordable cost of fabrication. SiCp/Al2O3 matrix composites were investigated for mechanical properties such as flexural strength, fracture toughness and hardness; the composite specimens were evaluated using standard procedures recommended by the ASTM. The SiCp/Al2O3 ceramic matrix composites with SiC volume fractions from 0.35 to 0.43 were found to possess average bend strength in range 158-230 MPa and fracture toughness was found to be in range of 5.61-4.01 MPa√m. The specimen fractured under three-point loading as observed under scanning electron microscope was found to fail in brittle manner being the dominant mode. Further the composites were found to possess lower levels of porosity, among those prepared by DIMOX process. 相似文献
8.
P. A. Tikhonov M. Yu. Arsentev M. V. Kalinina L. I. Podzorova A. A. Ilicheva V. P. Popov N. S. Andreeva 《Glass Physics and Chemistry》2008,34(3):319-323
Powder precursors in the ZrO2-CeO2-Al2O3 and ZrO2-Sc2O3-Al2O3 systems are prepared by the sol-gel synthesis. It is revealed that the electrical conductivity of the sample doped with scandium
oxide is higher than the electrical conductivity of the sample doped with cerium oxide despite the higher content of the nonconducting
phase Al2O3 (corundum). The thermal expansion coefficients are determined for all the ceramic samples under investigation. It is established
that the Al2O3 dopant affects the thermal expansion coefficient. The ceramic materials studied can be used as solid-electrolyte sensors.
Original Russian Text ? P.A. Tikhonov, M. Yu. Arsent’ev, M.V. Kalinina, L.I. Podzorova, A.A. Il’icheva, V.P. Popov, N.S. Andreeva,
2008, published in Fizika i Khimiya Stekla. 相似文献
9.
Ying Liu Yunlong Ai Wen He Weihua Chen Jianjun Zhang 《Ceramics International》2018,44(14):16421-16427
The grain growth kinetics and mechanical properties of graphene platelets(GPLs) reinforced ZrO2/Al2O3(ZTA) composites prepared by microwave sintering were investigated. The calculated grain growth kinetics exponent n indicated that the GPLs could accelerate the process of the Al2O3 columnar crystal growth. And the grain growth activation energy of the Al2O3 columnar crystal indicated that the grain growth activation energy of the GPLs doped ZTA composites is much higher than those of pure Al2O3 and ZTA in microwave sintering. The optimal mechanical properties were achieved with 0.4?vol% GPLs, whose relative density, Vickers hardness and fracture toughness were 98.76%, 18.10?GPa and 8.86?MPa?m1/2, respectively. The toughening mechanisms were crack deflection, bridging, branching and pull-out of GPLs. The results suggested that GPLs-doped are good for the Al2O3 columnar crystal growth in the ZTA ceramic and have a potentially improvement for the fracture toughness of the ceramics. 相似文献
10.
This study investigates the effect of ZrO2 on phase transformation of alumina. Alumina and alumina–zirconia composite powders were produced by the precipitation method from aluminum sulfate and zirconium sulfate precursors. Precipitates obtained at 15 °C were dried at 80 °C for 72 h, and then calcinated at four different temperatures; 1000 °C, 1100 °C, 1200 °C and 1300 °C for 1 h. Powders calcinated at 1300 °C were pressed uniaxially and sintered at 1600 °C for 1 h. XRD and DSC analyses showed that the presence of zirconia retarded the transformation to α-alumina. SEM studies on the powders calcinated at 1300 °C revealed that both alumina and alumina–zirconia particles were 100–300 nm in size and of near spherical shape. Zirconia additions inhibited abnormal grain growth of alumina and provided homogeneous, equaxied grain structure. 相似文献
11.
Eutectic compositions of Al2O3 and ZrO2 have been melted and rapidly solidified by shock-wave quenching, flame-pressure atomization and high-pressure water atomization. Quenching rates > 104 K/s resulted in amorphous particles which, on annealing, crystallized at 1310°C. Microcrystalline particles with tetragonal ZrO2 distributed in an ?-Al2O3 matrix formed at lower quenching rates. ?-Al2O3 transformed into α-Al2O3 on annealing at 953°C. 相似文献
12.
Al2O3/Cu-O composites fabricated by pressureless infiltration of paper-derived Al2O3 porous preforms
Stefan Pfeiffer Hannes Lorenz Zongwen Fu Tobias Fey Peter Greil Nahum Travitzky 《Ceramics International》2018,44(17):20835-20840
Al2O3/Cu-O composites were fabricated from the paper-derived alumina matrix infiltrated with a Cu-3.2?wt% O alloy. Paper-derived alumina preforms with an open porosity ranging from ~ 14 to ~ 25?vol% were prepared by sintering of alumina-loaded preceramic papers at 1600?°C for 4?h. Pressureless infiltration at 1320?°C for 4?h of the preforms with Cu–O alloy resulted in the nearly dense materials with good mechanical and electrical properties, e.g. fracture toughness up to 6?MPa?m0.5, four-point-bending strength up to 342?MPa, Young's modulus up to 281?GPa and electrical conductivity up to 2?MS/m depending on the volume fraction of copper alloy in the composites. The technological capability of this approach was demonstrated using prototypes in various engineering fields fabricated by lamination, corrugating and Laminated Object Manufacturing (LOM) methods. 相似文献
13.
Fully dense graphene nanosheet(GNS)/Al2O3 composites with homogeneously distributed GNSs of thicknesses ranging from 2.5 to 20 nm have been fabricated from ball milled expanded graphite and Al2O3 by spark plasma sintering. The percolation threshold of electrical conductivity of the as-prepared GNS/Al2O3 composites is around 3 vol.%, and this new composite outperforms most of carbon nanotube/Al2O3 composites in electrical conductivity. The temperature dependence of electrical conductivity indicated that the as-prepared composites behaved as a semimetal in a temperature range from 2 to 300 K. 相似文献
14.
Porous aluminum oxide (Al2O3) preforms were formed by sintering in air at 1200 °C for 2 h. A356, 6061, and 1050 aluminum alloys were infiltrated into the preforms by squeeze casting in order to fabricate Al2O3/A356, Al2O3/6061, and Al2O3/1050 composites, respectively, with different volumes of aluminum alloy content. The content of aluminum alloy in the composites was 10–40% by volume. The resistivity of Al2O3/A356, Al2O3/6061, and Al2O3/1050 composites decreased dramatically from 6.41 × 1012 to 9.77 × 10−4, 7.28 × 10−4, and 6.24 × 10−4 Ω m, respectively, the four-points bending strength increased from 397 to 443, 435.1, 407.2 MPa, respectively, and the deviations were smaller than 2%. From SEM microstructural analysis and TEM bright field images, the pore volume fraction and the relative density of the composites were the most important factors that affected the physical and mechanical properties. The ceramic phase and alloy phase in Al2O3/aluminum alloy composites were found to be homogenized and uniformly distributed using electrical and mechanical properties analysis, microstructure analysis, and image analysis. 相似文献
15.
A series of short-carbon-fiber/Al2O3 composites with MgO as sintering additive were fabricated by pressureless sintering process. The effects of short carbon fiber (Csf) content on the mechanical, dielectric and microwave absorbing properties of the composite were investigated. The results show that the addition of MgO enhances the density, hardness and the flexural strength of the alumina ceramic. However, these mechanical properties of the Csf/Al2O3–MgO composite decrease with increasing Csf content. Both the real and imaginary parts of the complex permittivity increase with increasing Csf content in the frequency range of 8.2–12.4 GHz, which is attributed to the increasing electron polarization and associated polarization relaxation, respectively. When the Csf content is 0.3 wt%, the reflection loss less than −10 dB and the minimum value of −27 dB are obtained with the coating thickness being 1.4 mm. The results indicate that the Csf/Al2O3 with MgO is an excellent candidate for microwave absorbing material with favorable mechanical property. 相似文献
16.
Al2O3/diopside ceramic composites with good mechanical properties were prepared by uniaxial hot-pressing and their biological activity in simulated body fluid was studied by SEM, XRD, FT-IR and EPMA. SEM micrographs showed a lath-like apatite layer to form on the soaked composite surface, whose good biological activity may be of some promise for biomedical application. 相似文献
17.
Antonio Licciulli Vincenzo ContaldiSanosh Kunjalukkal Padmanabhan Avinash BalakrishnanCristina Siligardi Daniela Diso 《Journal of the European Ceramic Society》2011,31(3):385-389
The present work describes the processing of alumina fiber reinforced alumina ceramic preforms consisting of chopped Al2O3 fibers (33 wt%) and Al2O3 (67 wt%) fine powders by slip casting. The preforms were pre-sintered in air at 1100 °C for 1 h. A lanthanum based glass was infiltrated into these preforms at 1250 °C for 90 min. Linear shrinkage (%) was studied before and after glass infiltration. Pre-sintered and infiltrated specimens were characterized by scanning electron microscopy, energy dispersive X-ray, X-ray diffraction, porosimetry and flexural strength. The alumina preforms showed a narrow pore size distribution with an average pore size of ∼50 nm. It was observed that introducing Al2O3 fibers into Al2O3 particulate matrix produced warp free preforms with minor shrinkage during pre-sintering and glass infiltration. It was observed that the infiltration process fills up the pores and considerably improves the strength and reliability of alumina preform. 相似文献
18.
The effect of Al2O3 on mechanical properties of Ti3SiC2/Al2O3 composite fabricated by SPS was studied systematically. The results show that the hardness of the Ti3SiC2/Al2O3 composite can reach 10.28 GPa, 50% higher than that of pure Ti3SiC2. However, slight decrease in the other mechanical properties was observed with Al2O3 addition higher than 5–10 vol.%, which is believed to be due to the agglomeration of Al2O3 in the composite. 相似文献
19.
Silicon carbide ceramics are very interesting materials to engineering applications because of their properties. These ceramics are produced by liquid phase sintering (LPS), where elevated temperature and time are necessary, and generally form volatile products that promote defects and damage their mechanical properties. In this work was studied the infiltration process to produce SiC ceramics, using shorter time and temperature than LPS, thereby reducing the undesirable chemical reactions. SiC powder was pressed at 300 MPa and pre-sintered at 1550 °C for 30 min. Unidirectional and spontaneous infiltration of this preform by Al2O3/Y2O3 liquid was done at 1850 °C for 5, 10, 30 and 60 min. The kinetics of infiltration was studied, and the infiltration equilibrium happened when the liquid infiltrated 12 mm into perform. The microstructures show grains of the SiC surrounded by infiltrated additives. The hardness and fracture toughness are similar to conventional SiC ceramics obtained by LPS. 相似文献
20.
Guy Ann Kim Vanmeensel Bram Neirinck Omer Van der Biest Jef Vleugels 《Journal of the European Ceramic Society》2006,26(16):3531-3537
Stable suspensions based on methylethylketone (MEK), n-butylamine and nitrocellulose were developed for the electrophoretic deposition (EPD) of Al2O3 and ZrO2 powder. Deposits with a high green density, smooth surface and high deposition yield were obtained upon adding 10–15 vol.% n-butylamine in combination with 1 wt.% nitrocellulose. The influence of the reaction between MEK and n-butylamine, forming water and imines, on the electrophoretic deposition behaviour was investigated. Experimental results revealed that the zeta potential is not a straightforward indication of the stability of these suspensions, since the maximum absolute zeta potential did not correspond with a maximum suspension stability, due to the additional electrosteric stabilisation of the adsorbed charged nitrocellulose. 相似文献