牙用Ti-Zr合金铸件表面反应层结构的研究

A Surface Reacted Layer Study of Titanium-Zicornium Alloy after Dental Casting

目的 :观察铸模温度对牙用Ti Zr合金铸件表面反应层结构的影响。方法 :在 3种铸模温度下 (室温 ,30 0℃ ,6 0 0℃ )进行牙用Ti_Zr合金的铸造。对牙用Ti Zr合金的铸件表面粗糙度以及表面反应层的厚度及显微硬度进行测试 ;采用SEM观察及元素线分析对铸件的表面反应层结构进行分析。结果 :随着铸模温度的提高 ,Ti Zr合金铸件表面粗糙度明显增加 ,表面反应层的厚度增加 ,硬度值增大。Ti Zr合金铸件表面反应层结构可分为 3层 ,主要元素为O ,Si,Al,Zr,且随着铸模温度的提高 ,Si的渗透深度及渗透量均有所增加。结论 :为了减少Ti Zr合金铸件表面反应层的厚度 ,应尽量降低铸模温度 ,同时应选择无Si的包埋材料。

Objective:To investigate the influence of the mold temperature on the surface reacted layer of Ti Zr alloy castings. Methods: Ti Zr alloy was casted into a mold which was made of a zircon (ZrO\-2·SiO\-2) for inner coating and a phosphate bonded material for outer investing with a casting machine (China) designed as vacuum, pressure and centrifuge. At three mold temperatures (room temperature, 300℃, 600℃) the Ti Zr alloy was casted separately. The surface roughness of the castings was calculated by instrument of smooth finish (China). From the surface to the inner part the Knoop hardness and thickness in reacted layer of Ti Zr alloy casting was measured. The structure of the surface reacted layer was analysed by SEM. Elemental analyses of the interfacial zone of the casting was made by element line scanning observation.Results: The surface roughness of the castings was increased significantly with the mold temperature increasing. At a higher mold temperature the Knoop hardness of the reactive layer was increased. At the three mold temperature the outmost surface was very hard, and microhardness data decreased rapidly where they reached constant values. The thickness was about 85μm for castings at room temperature and 300℃, 105μm for castings at 600℃. From the SEM micrograph of the Ti Zr alloy casting, the surface reacted layer could be divided into three different layers. The first layer was called non structure layer,which thickness was about 10μm for room temperature group, 20μm for 300℃ and 25μm for 600℃. The second layer was characterized by coarse grained acicular crystal, which thickness was about 50μm for three mold temperatures. The third layer was Ti Zr alloy. The element line scanning showed non structure layer with higher level of element of O, Al, Si and Zr, The higher the mold temperature during casting, the deeper the Si permeating and in the second layer the element Si could also be found.Conclusion: The mold temperature is one of the major factors influencing to casting quality.In order to reduce the surface reacted layer of Ti Zr alloy castings, the lower mold temperature and the investment without Si should be chosed.\;