| Summary: | 碩士 === 國立臺灣科技大學 === 機械工程系 === 90 === Diamond Tools always play a important role of removing the superhard materials. They are intensively used for traditional rock cutting and grinding, and drilling for oil and gas field. In addition, diamond tools are used for processing on superhard material tools like tungsten carbide cutting tools. Furthermore, diamond tools are also used for cutting of diamond and other kinds of jewels, micro-drilling on IC board in high-tech electrical industry, dicing of silicon wafer, LED, and other kinds of micro size devices. In recent high-order semiconductor process, diamond tools are used for diamond conditioner for polishing pads used on chemical mechanical polishing. Diamond tools are always the best or only choice in related fields.
Cu-Ti-Sn pre-alloy brazing material is successful on micrometer size diamond grits vacuum brazing. But there are cracks on the diamond grits which are brazed in the same brazing condition. It is exact that high quality diamond grits can prevent failure of diamond tools. But high quality diamond grits also mean high cost and low competition. Thus, how to stop defect growth will be the most important thing if we want to improve the efficiency and cost down.
The brazing process is executing at 850℃ using Ag-Cu-TiH2-Sn. TiC layer compounded of titanium and carbon in the diamond grits on the surface of diamond grits keeps them located on the diamond tools substrate. Lower brazing temperature prevent the diamond grits graphitization and defect growth. We substitute titanium powder with titanium hydride to be the source of active metal. Titanium hydride is hard to be oxidized at room temperature, so it is easy to preserve. The hydrogen will be released in the brazing process to keep the reduction atmosphere. Ag-Cu-Ti-Sn four elements brazing alloy will lower the reaction between the brazing materials and diamond grits. According to the experiments, proper quantity of silver can keep the brazing temperature between 820℃ and 850℃. Low brazing temperature results in low failure opportunity. Covering the diamond grits with brazing materials thoroughly can prevent affection of expansion and contraction stress which are caused by interlayer of brazing materials, diamond grits, and environment.
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