Study Of Green Body Made By Slip Casting Method With High Dispersion SiC

The recrystallized Silicon Carbide(R-SiC) ceramic was significtantly applied in high temperature, wear resistant and corrosion resistant areas as it has excellently properties on physicals and chamicals.There are many small particle size(2.9-4.5μm) and low-purity (the content of SiC was93-95%) SiC-dust collecting power which was made in the process of silicon wafer cutting blade material and SiC-abrasive with smash method.The SiC-dust collecting power was only to smelt, except it was used as additive in refractory materials by only a few companies.In this paper, SiC-dust collecting power was used as main raw materials, the impurity was emililated after SiC-dust collecting power was treatment by oxidation and acid-washing processes. The silane coupling agent YDH-560andG3were the best coating modification system of SiC-dust collecting power.The temperature was80℃,pH=6.5,and the reaction time was two hours were the reaction conditions of coating modification. The maximum absolute value of Zeta value of SiC-dust collect power was increased from27.57mv to45.42mv after coating modification, the dispersion properties in aqueous medium of SiC-dust collecting power was increased.After research, silane coupling agent and alcohol-ethers coating modification agent were used in this paper, the coated SiC-dust collecting power was steric stabilization method in aqueous medium, it was different of1.2μm coated SiC which was electrostatic stabilization in aqueous medium was made by Saint-Gobain company. The3.5μm SiC-dust collecting grading power was made with0.6μm SiC and3.5μm SiC-dust collecting power as the ration of1:4, and it’s d50was1.17μm. The mian reason of viscosity was decreased and it was caused by the smooth surface of coarse SiC particles. Partialmolar volume of large SiC particles was smaller than that of small SiC particles. Therefore, large SiC particles were more densely packed than small SiC particles in all the range of mixing. The viscosity of suspensions were decreased as40-60wt%Mutankiang100μm SiC was added in the suspension.When the Mutankiang100μm SiC was added at the content of55wt%, the microstrture was highly uniformity and the density was maximum of green body, the density of green body was up to2.70g/cm3.The SiC powers were well dipersed in aqueous medium when composite dispersant was added in the suspention.The composite dispersant was made by polyethyleneimine (PEI) and tetramethylammonium hydroxide (TMAH) as the ration of1:1.The effort of bubble stabilizion made by polymer chain and deflated reaction made by silicon and OH-in aqueous medium were decreased after composite dipersant was added in suspension. The bubble was well eliminated and restrained when the NXZ was used as antifoaming agent, the viscosity of suspension was decreased at shear rate at20-50s-1with NXZ as antifomaing agent.The main reason of bubble could not be eliminated were bubble stabilized by polymer chain and deflated reaction by silicon in suspensions.The bubble in suspension of Saint-Gobain1.2μm coated SiC could not be eliminated with NXZ as antifomaing agent.The viscosity of suspension was increased at high shear rate and decreased at low shear rate when0.5wt%AES-60was added as rheological agent. The separated phenomenon of coarse and small SiC particles were decreased and the bubble was easily eliminated when0.5wt%AES-60was added as rheological agent. The microstructure of green body was significantly uniformity, and it’s density was up to2.72g/cm3, it was achieved the level of Germany FCT company.