Papers by Keyword: Multiphase Ceramics

Abstract: TiB2-TiC multiphase ceramics were prepared through altering the molar ratio of Mg and C and leached with suitable acid by the combustion synthesis reaction of Mg, C, TiO2 and B2O3. The samples were investigated by XRD and SEM, and the results showed the diameter of the TiB2 was 1.5μm and the shape of the TiC was irregular spherical particles. The diameter and the proportion of the TiB2 were increased with the increase of Mg powder. The formation mechanism of TiB2 has been studied. The optimized proportioning of the molar ratio of Mg and C was 3:2.

Abstract: Mullite-aluminum titanate-cordierite multiphase ceramics were prepared by high alumina clinker, Aluminum Titanate and Cordierite. The sintering property and thermal shock resistance of composite materials were tested. The experimental results show that the sinter property and themal shock resistance of Mullite-aluminum titanate-cordierite multiphase ceramics are relatively preferably, which the materials composition are 30 wt.% high alumina clinker, 60 wt.% cordierite and 10 wt.% aluminum titanate. The component samples show porosity of 33.17%, volume density 1.9 % and normal temperature flexural strength 20.66 MPa. Thermal residual flexural strength of the samples is still as high as 10.29 Mpa by 5 times thermal residual tests, and there are only little flexural strength lower after three times earthquake test.

Abstract: The microstructure characteristics of Si3N4/nanometer SiC multiphase ceramics material was studied by electronic microscopy, and the different of the nanometer multiphase and the single-phase Si3N4 ceramics microstructure was analyzed. The relations of the multiphase ceramics material mechanical properties and the microstructure were discussed. The nanometer grain in material restrain Si3N4 crystallinity, improve the mechanical properties of material. Nanometer multiphase ceramics is a new kind of ceramics material which developed in several years, in which Nanometer crystalline grain is smaller than 500nm, because of its small crystalline grain and interface out of order, it has much better feature than that of traditional ceramics materials, it is one of directions on which ceramics material develop in future[1]. The study shows, the temperature indoor strength and toughness is higher 2-3 times than single set material in nanometer multiphase ceramics, at temperature indoors, toughness, strength and anti-creep etc improve a lot[2]. Use high resolving power analyzing technology and electron diffraction analyzing technology of transmission electron microscope can distinguish crystal size, appearance distribution form, dislocation and crystal boundary phase of different material in one sample, in the order to study deeply the relation between microcosmic structure feature of the material and mechanical properties and valuable information to improve material.

Abstract: Electroconductive TiN/O′-Sialon multiphase ceramics were prepared by pressureless sintering from TiN/O′-Sialon powders as the chief raw material which were synthesized by the carbothermal reduction nitridation method using high titania slag, silicon fume and bauxite chalmette. Phase compositions and were analyzed. The effect of microstructure and TiO₂ content in initial raw materials on electrical conductivity were studied by SEM and TEM. The electro-discharge machining (EDM) of the materials was carried out. The results show that the sintered samples consist of O′-Sialon and TiN. O′-Sialon grains exhibit equiaxied morphology and the particle sizes are about 1-3μm. TiN grains exhibit fine granular morphology and most of grains have lower size than 0.5μm. The minimum amount of TiO₂ in initial raw materials is 25wt% for the formation of electroconductive network in the multiphase ceramics, of which the electrical resistivity is 1.8×10^-2 Ω·cm and meets the requirement of electrical discharge machining.