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Effect of rare earth oxide ceramic foam performance



Effect of rare earth oxide ceramic foam performance. With the increase of rare earth oxides. Sintering temperature. The sintering time is shortened. Bulk density ceramics, flexural strength and thermal shock resistance also increases.



Because SiC and-Al2O3 is typically covalent compound. At elevated temperatures remain high bonding strength. Diffusion rate is low temperature sintering. Easy sintering. Rare earth oxide having a high surface activity energy. Generates liquid eutectic material with SiO2 and SiC surface of SiO2 or impurities in raw materials. So that the presence of liquid phase during sintering particles are relatively easy rearrangement. And the sintered material composed of a single solid phase into solid and liquid phases simultaneously. Increased pipeline and transfer the amount of substance. Thus reducing the sintering temperature. Reduce the sintering time.


After the addition of rare earth oxide. Improved mullite - wetting properties of silicon carbide materials. Lowering the melting point of the ceramic material. Added to the material of rare earth oxides can promote Al2O3, SiO2 and impurities in the material chemical reaction. Easy to form a low-melting liquid phase. Coupled with capillary action between the particles. Promote inter-particle material to fill voids at. The porosity of the material is reduced. Density increase.


Since SiC reticulated foam structure for communicating with each other. Quenched in water. Heat transfer products mainly through the center of the surface of the water convection in the mesh pore penetration. The faster penetration, thermal stress relaxation is also faster. Thermal shock resistance is also better. Therefore, a high porosity ceramic foam. Silicon carbide material and a low coefficient of expansion. Are making silicon carbide ceramic foam has good thermal shock resistance. Adding rare earth oxides can be offset ceramics produced cristobalite volume change. Reduce the thermal stress of the material changes in temperature. Thus improving the thermal shock resistance of the material allows to improve the thermal shock resistance of ceramics. Due to the addition of rare earth oxide ceramics can be offset generated cristobalite change in volume and density of the ceramics increase. Thus bending strength of the ceramic increases.