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研究了六方氮化硼作为钛合金熔模精密铸造中面层造型材料的可行性。以高温高压下预处理的氮化硼作为型壳面层中的主要耐火材料,钇溶胶作为黏结剂并适当加入少量氧化钇,制备氮化硼基复合型壳。研究了氰化硼涂料的密度、黏度等性质,通过热重分析探讨了氮化硼基复合型壳的烧结工艺。研究表明:面层涂料具有剪切稀释性,涂料的表观黏度随剪切速率的升高而降低。当型壳焙烧温度高于800℃时应采用N_2保护加热。TiNi合金与型壳的反应较小,在TiNi合金铸件中没有出现夹杂氧化钇颗粒。
The feasibility of using hexagonal boron nitride as the surface modeling material for precision casting of titanium alloy was studied. Boron nitride-based composite shell was prepared by using boron nitride pretreated under high temperature and high pressure as the main refractory in the shell surface layer, yttrium sol as a binder and a small amount of yttrium oxide as appropriate. The density, viscosity and other properties of boron cyanide coatings were studied. The sintering process of boron nitride matrix composite shells was discussed by thermogravimetric analysis. The results show that the surface coating has shear thinning property, and the apparent viscosity of coating decreases with the increase of shear rate. When the shell roasting temperature higher than 800 ℃ should be used N_2 protection heating. The reaction of TiNi alloy with the shell is small, and there is no inclusion of yttrium oxide particles in the TiNi alloy castings.