纯钛铸造包埋材料成分对铸型力学性能的影响

Effect of investment composition ratio for pure titanium crown and bridge on some mechanical properties of mould

目的通过测量铸型性能进一步优化自行研制包埋材料各组分的配比。方法使用自行研制的包埋材料，根据L9（3^4）正交实验设计9个实验组和1个商品化纯钛包埋材料对照组，每组包埋材料制备80mm×20mm×20mm的条状试样15个，测量试样常温抗折强度、高温抗折强度及残余抗折强度。9个实验组制备直径5mm、高25mm的圆柱状试样各1个，测定室温至1150℃的热膨胀曲线。结果粉料占耐火材料总重的百分含量和粉液比对3种抗折强度的影响较大，当粉料占耐火材料总重的35％，粉液比为7．5：1时可获得较高的常温抗折强度和高温抗折强度，残余抗折强度适中。9个实验组的热膨胀曲线基本一致，平均线膨胀系数为（4～5）×10-6／℃。结论通过控制粉液比、粉料占耐火材料总重的百分含量等指标，自行研制包埋料制备的铸型各项抗折性能可与商品化材料接近。

Objective To determine the optimal composition of a self-developing investment material by measuring physical and mechanical properties of mould. Methods L9 （ 3^4 ） orthogonal design was adopted. One hundred and fifty specimens with the size of 80 mmx 20 mmx 20 mm were prepared to measure the atmospheric temperature bending strength, high temperature bending strength and residual bending strength. Nine specimens with the size of 5 mm diameter 25 mm heigh were prepared to survey the thermal expansion curve from ambient temperature to 1150 ℃. Results Strengths were greatly affected by fine powder proportion in refractory and water/powder ratio. When the content of fine powder was 35 % and water/powder ratio was 1 ： 7.5, adequate atmospheric temperature strength and high temperature strength could be achieved. Moreover, the residual strength was moderate. The thermal extension curves of specimens in experiment group were almost similar. And the average linear expansion coefficient was （4 - 5 ） × 10-6/℃. Conclusions The three kinds of bending strength of self-developing investment material are compared with commercialized investment material for titanium casting when water/powder ratio and the content of fine powder are carefully controlled.