铸模温度对铸钛机械性能及表面反应层结构的影响

The effect of the mold temperature on the mechanical properties and reaction layer structure of the titanium castings

钛在高温状态下化学性能活泼，易氧化且与包埋料发生化学反应。我们采用拉伸试验及现代表面分析技术，研究了不同铸模温度对铸钛机械性能及表面反应层结构的影响。结果表明，随着铸模温度升高，铸钛件的抗拉强度、屈服强度增加而延伸率下降，同时，铸钛表面硬化层增厚。用室温铸模铸造时钛铸件表面硬化层厚５０μｍ，用８５０℃铸模铸造时钛铸件表面硬化层厚１２５μｍ。ＳＸｍａｃｒｏ电子探针微区成分分析显示，锆、铝二元素在钛铸件表面扩散深度不随铸模温度增高而加深，但硅元素的扩散则随铸模温度升高而加深。室温铸造时硅元素的扩散深度为３０μｍ，８５０℃铸造时已达９０μｍ。研究结果提示，临床制作铸钛修复体时，必须考虑铸模温度对铸件质量的影响。

Titanium is very reactive at the high temperature, easily oxidized, and reacts with investment components. The mold temperature is an important factor on the quality of the titanium castings. The paper investigated the effect of the mold temperature on the mechanical properties and reaction layer structure of the titanium castings with the tensile test and modern surface analysis technique. The results indicated that the tensile strength and yield strength of titanium castings increased but elongation rate decreased, and the hardness layer become thicker when the mold temperature raised. The hardness layer of titanium castings was 50 μm for the room temperature mold, 125 μm for the 850℃ mold. SXmacro electric probe analysis indicated the spreading depth of Zr, Al elements on the surface of titanium castings was not increased when the mold temperature raised, but, the spreading depth of Si element became deeper on the surface of titanium casting, Si layer was about 30 μm for the room temperature mold, 40 μm for the 250℃ mold, 50 μm for the 450℃ mold, 70 μm for the 650℃ mold, 90 μm for the 850℃ mold. So, it is necessary to consider the effect of the mold temperature on the qualities of titanium castings when titanium castings for prosthodontics were made in clinic.