Study on Electric Discharge Machining of Ceramics

本课题通过三个方面的研究来建立高精度、高强度的全瓷修复体的电火花加工技术，第一部分是研制牙科用小型电火花加工机，通过对电火花加工速度、电极损耗、粗糙度和精度的测量，研究了导电陶瓷的最佳加工条件;第二部分是研究了电火花加工技术在全瓷修复体中的应用，并对电火花加工技术在全瓷修复体中的应用进行了研究。研究了电火花加工电极的两种快速制造方法。其中之一是基于电铸铜的方法。为了获得厚而均匀的电铸膜，对电铸铜的银镜面液和镀液的组成进行了研究。另一种方法是采用含导电铜粉的牙科石模，并在其表面镀铜，方法简单新颖。第三，尝试研制电火花加工用白色或牙色导电陶瓷，通过这些研究，至少在技术上完成了电火花加工全瓷冠的制作。程序如下：TiBZ-TiC陶瓷块先用电火花加工成核，再将牙科陶瓷熔附到核上，但在此过程中，存在着加工时间和可加工陶瓷颜色美观等问题。它们是未来研究的主题。

This project was consisted of three studies for establishment of technique to make a all ceramic prosthetic appliance with high accuracy and strength by electric discharge machining (EDM).In the first study, the compact EDM machine for dental use was produced, and the optimum machining conditions for the ceramics with electric conductivity were researched through the measurement of machining speed, electrode loss, roughness and accuracy.In the second, two methods of rapid production of the electrode for EDM were investigated. One of them was the method on basis of copper electroforming. Silver mirror solution and the composition of the bath for copper electroforming were studied to get a thick and uniform film. And the other was the new and simple method to use the dental stone model containing the copper powder for electric conductivity, and plated with copper. As this was applied to EDM, it is appeared to be able to use for electrode of EDM.In the third, the development of white or tooth color ceramics with electric conductivity for EDM was tried.Through these studies, it was completed at least technically to produce the all ceramic crown by applying the EDM. The procedure are as follows; in first, a core is made by EDM from the TiBZ-TiC ceramic block, and then dental porcelain is fused to the ceramic core.In this procedure, however, there are some problems in regard to machining time and to aesthetic in color of machinable ceramic by EDM. They are the subjects for future studies.