分散剂反应直接凝固注模成型制备碳化硅陶瓷

Direct Coagulation Casting of Silicon Carbide Ceramics via Dispersant Reaction

分散剂反应直接凝固注模成型是一种新型陶瓷胶态成型方法。通过分散剂反应失效,实现碳化硅陶瓷悬浮体的原位固化。采用经碳酸铵((NH_4)_2CO_3)化学处理的碳化硅粉体,以质量分数0.2%的四甲基氢氧化铵(TMAH)为分散剂制备悬浮体,添加2 vol%的二乙酸甘油酯(GDA)作为固化剂,高温下GDA水解出乙酸与分散剂TMAH发生酸碱中和反应,使分散剂失去分散作用,达到原位固化的效果。70°C固化得到的碳化硅坯体抗压强度为1.13 MPa;样品在1950℃和0.1 MPa氩气气氛中无压烧结2 h,抗弯强度为697 MPa。

Direct coagulation casting via dispersant reaction is a novel colloidal forming method for ceramics.The well disperse silicon carbide suspension can be coagulated in-situ by DCC via dispersant reaction.Silicon carbide suspension was prepared using surface chemical treatment powder.Ammonium carbonate((NH_4)_2CO_3)was used to leach the silicon carbide powder.Tetramethyl ammonium hydroxide(TMAH)with content of 0.2 wt%was used as dispersant.2 vol%glycerol diacetate(GDA)was added as coagulation agent.Tetramethyl ammonium hydroxide reacted with acetic acid which hydrolyzed from glycerol diacetate at elevated temperature,and then desorbed from silicon carbide particles.Zeta potential of suspension decreased due to desorption of dispersant,and the suspension coagulated in-suit from the instability of the silicon carbide particle.The silicon carbide green body with compressive strength of 1.13 MPa was coagulated at 70°C.The silicon carbide ceramic with flexural strength of 697 MPa was pressureless sintered at 1950°C for 2 h under0.1 MPa argon atmosphere.