| Summary: | 碩士 === 長庚大學 === 機械工程學系 === 105 === The electroplated diamond millers, which were fabricated through electroplating Ni-Cr-C-diamond composite coatings on a medium carbon steel (S45C) rod with a diameter of 5.7 mm and the average of diamond particles size is 50 μm. There are two methods for Cr-C-diamond composite coatings after Ni undercoat on a medium carbon steel (S45C). One is Cr-C-diamond composite coatings with intermittent stirring in the Cr-diamond plating, but the diamond particles were only deposited on the bottom of specimen, and the other is co-electroplating with Ni undercoat which was prepared in a typical Ni-Watt plating bath at 50oC; then Cr-C electroplating was conducted with the Ni-diamond deposited steel rod in a trivalent Cr-plating bath at 30oC. By using this method, the uniform Cr-C-diamond composite coatings can be obtained on the specimen surface and produced multilayer of Cr-C-diamond composite coating.
The hardness of Cr-C-diamond composite coating can be highly increased by annealing at 500℃ for 30 minute. The milling ability of as-plated diamond miller and annealed diamond miller was studied by milling test on the Al2O3 at 3000 rpm, milling thickness of 1.5 mm, feed rate 1 mm/min. After milling 30 mm long on the Al2O3 plate, the milling ability of as-plated diamond miller was lost because the coating was failed. On the other hand, the diamond miller has high milling ability after annealing, which can mill 1070 mm long on the Al2O3 plate. The Cr-C-diamond composite coating was consumed during milling process and diamond particles were partially embedded in the Ni coating at the same time. In this situation, the diamond miller still has milling ability. Once diamond particles were fully embedded in the Ni coating, the milling ability of diamond miller will lost.
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