Key Engineering Materials
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Vols. 280-283
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Vols. 270-273
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Paper Title Page
Abstract: Graphite is introduced into Al2O3 ceramic with copper matrix. The influence of graphite content to friction factor and wear and tear of Al2O3 ceramic with copper matrix has been studied in this paper. Friction factor of ceramic with copper matrix decreases with the increase of graphite content at first. After graphite content exceeds more than 3%, friction factor stops reduction. Wear and tear decrease with the increase of graphite content from the beginning. After graphite content
surpasses more than 3%, it increases instead with the increase of graphite content. When graphite content is 3%, Wear and tear locates the lowest point. Solid lubrication film formed by graphite on the friction surface is the cause that makes friction factor drop.
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Abstract: The high temperature abrasive wear resistant of the composites with different Al2O3
volume fractions, particle coating and size were investigated and the failure action of composites under different conditions at high temperature was analyzed. The results showed that the high temperature abrasive wear resistant of composite with Ni coating and wide size and 39% volume fraction of particle is the best among all composites examined.
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Abstract: Based on the CuO+Al system with the additives of additional aluminum and Al2O3 +
13%TiO2, the SHS Flame Spraying coatings were produced on the surface of the steel substrate. The wear quality of the coatings was measured and the micro fabric of the coatings was analyzed. It was shown that by using the 3-6% additional aluminum, high reactive transfer rate and coatings with good micro-fabric and high abrasion quality were acquired. Adding the Al2O3 + 13%TiO2 additive could
increase the content of the ceramics, but too much additive would lead to the coarse fabric and make the porosity of the coatings improve, which made the abiding strength and the wearing resistance decrease. 10% Al2O3 + 13%TiO2 additive is suitable to produce the coatings with good properties, and adding 6%(Ti+C) additive gives rise to coatings of high abrasion performance.
1123
Abstract: An Al2O3 matrix composites, i.e. partially stabilized zirconia toughening alumina (ZTA) reinforced by SiC particle (ZTA-SiCP), was prepared by hot pressing (HP). Fatigue behavior of ZTA-SiCP under cyclic compressive loads was investigated on different loading conditions. The application of cyclic compressive loads to a notched specimen led to a stable crack growth along the notch plane in a
direction normal to the far-field compressive axis. Irreversible damages in the main form of microcrack were induced at the stress concentration zone during compression loading, and it led to high residual tensile stresses ahead of the notch root upon unloading. Nucleation and growth of a model I fatigue crack were caused by the residual tensile stresses at the notch root. Along with propagation of the fatigue crack, a gradual decrease in crack growth rate was shown due to the crack closure caused by accumulating of debris particles within the wake of growing crack, and thus led to the crack arrested at last. The fatigue crack length was investigated as a function of notch length, the maximum compressive stress, stress range and load frequency.
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Abstract: Dense aluminum oxynitride-titanium nitride (AlON-TiN) composites with 3~15wt% TiN were fabricated by hot pressing technique. The effect of the content of a dispersion-toughening aid, TiN, on the mechanical properties, oxidation resistance and wear resistance were studied and related to the microstructure. The composites with a content of 15wt% were characterized with the highest
strength, 487 MPa, and the highest wear resistance properties. Oxidation behavior was studied and the results showed that AlON-TiN composites have excellent oxidation resistance.
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Abstract: Aluminium oxynitride-vanadium nitride (AlON-VN) composite ceramic was fabricated based on thermodynamic analysis of V-Al-O-N systems. The results indicated that the VN dispersed homogeneously in AlON matrix and can reinforce AlON matrix. Oxidation behavior was studied and the results showed that it belongs to self-protective oxidation due to the good adherence of oxidation product.
Therefore, AlON-VN composites have excellent oxidation resistance.
1139
Abstract: A novel technique was developed to synthesize porous silica–matrix ceramics from silicon carbide and alumina with an Y2O3 addition, using pine sawdust as a pore former. The porous ceramics were fabricated at temperatures of 1300–1500 oC in air by a reaction–bonding process based on two reactions: (1)SiC+2O2→SiO2+CO2 (Oxidation) and (2)2SiO2+3Al2O3→3Al2O3·2SiO2 (Mullitization). Reaction–bonding behavior, mechanical property and open porosity were investigated as a function of Y2O3 content as well as sintering temperature and holding time. Moreover, phase composition and microstructure of the porous silica–matrix ceramics were studied by X–ray diffraction (XRD) and scanning electron microscopy (SEM).
1143
Abstract: The thin-film of silicon deposited by RTCVD on pressureless sintered SiC substrate with the size of 30mm×20mm, which is cleaned by ultrasonic method and chemical treatment. The crystal size of silicon columnar grain can reach 190 µm and its preferred orientation is [111] after ZMR process.
1147
Abstract: The silica colloidal crystal multilayers were deposited from ethanol suspensions with
different particle concentrations by vertical deposition method. The microstructures and thicknesses of silica colloidal multilayers were characterized by scanning electron micrography. The thicknesses of colloidal crystal multilayers increased with the particle concentration increasing within a certain range of particles concentrations. When the particle concentration exceeded 2.48wt%, the thicknesses of colloidal crystal multilayers didn’t increased with the concentration increasing. Colloidal crystal multilayers with few defects could be deposited from the suspensions with the particle concentration 2.48wt%. The optical properties of the silica colloidal multilayers were investigated by a UV-Vis scanning spectrophotometer in normal incidence. They corresponded well to the microstructure obtained by SEM images.
1149
Abstract: Monodispersed mesoporous silicon dioxide microspheres were prepared by polymerization-induced colloid aggregation (PICA) method and calcined at 850oC. The prepared samples were characterized with scanning electron microscopy (SEM), thermogravimetry (TG) and BET surface areas.
The results showed that the obtained SiO2 microspheres had an average diameter of about 2.0 µm, a surface area of 253.3 m2g-1, an average pore volume of 0.62 mLg-1, and an average pore diameter of 7.9 nm. The formation mechanism of SiO2 spherical particles was discussed.
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