Stduy On Properties Of Water-soluble Polymer Modified Silicon Carbide Powder And Its Slurry

Silicon carbide ceramic is an inorganic non-metal with excellent properties such as high temperature resistance,radiation resistance and high strength.It is widely used in machinery,aerospace and other important fields.Silicon carbide ceramics were prepared by grouting which was one of the most common molding methods have high density and uniform distribution.However,it requires highly for slurry.Only slurry with high solid content and low viscosity can be used for grouting.At present,the slurry prepared by silicon carbide powder produced in China has not reached the advanced level abroad,so the powder needs to be surface-modified to increase its solid phase content and reduce its viscosity.In this paper,pretreated polyacrylic acid,block copolymers HY-2000 and HY-168,and sodium polyacrylate were used to surface-treat silicon carbide powders,and three modified powders with different pH were prepared.The specific content was as follows:(1)The modified silicon carbide powder with pH=6 obtained by modification with polyacrylic acid pretreated with sodium hydroxide.The maximum solid content of the modified powder was 61.2 Vol%,and the slurry whose solid content was 50 Vol%viscosity was 0.438 Pa·s.The utilization rate of pre-treated polyacrylic acid was 16%higher than that of the untreated polyacrylic acid,which is due to molecular chain extension.The adsorption of the pretreated polyacrylic acid on the powder surface not only increased the maximum value of the absolute value of the Zeta potential of the modified SiC powder(63 mV),but also improved the sedimentation stability after being prepared into the slurry.It took 48 hours for the SiC slurry to reach sedimentation equilibrium and the relative sedimentation height was 94.8%.Through STM test,it was found that the modification effect was significant,the agglomeration of particles was significantly reduced,and the dispersibility is significantly improved.(2)The modified silicon carbide powder with pH=7 was obtained by using block copolymers HY-2000 and HY-168 through ball milling.By comparing the solid phase content and viscosity,it was concluded that the block copolymer HY-2000 had the best modification effect.The modified SiC powder with pH=7.08 was obtained by the block copolymer HY-2000,and the maximum solid content was 62.59 Vol%,and the slurry whose solid content was 50 Vol%viscosity was 0.80 Pa·s.It has been discovered that the powder dispersion modified by HY-168 only depended on steric hindrance,while HY-2000 was a synergistic effect of steric hindrance and electrostatic repulsion.(3)The modified silicon carbide powder with pH=8 was obtained by using Sodium polyacrylate through a simple stirring and heating method.Based on the analysis of the solid content and viscosity data,the optimal parameters of the sodium polyacrylate modification process were obtained:the addition amount of sodium polyacrylate was 0.6 wt%,the reaction time was 4 h,and the reaction temperature was 90?.The modified SiC powder with pH=8.08 was obtained by Sodium poly acry late,and the maximum solid content was 65.8 Vol%,and the slurry whose solid content was 50 Vol%viscosity was 0.183 Pa·s.It took 48 hours for the SiC slurry to reach sedimentation equilibrium and the relative sedimentation height was 96.3%.