Preparation of diamond-coated tools and their cutting performance

摘要

Diamond growth using microwave plasma CVD and the adhesion strength between the diamond film and the WC-Co substrate were studied. A cutting test of Al-18 mass% Si (A390-T6) alloys using a diamond-coated tool was carried out. As a result, low-temperature growth was recognized on the scratched surface after Co removal from the WC-Co substrates. In the cutting test, using the tool that had been coated with diamond at high temperature (about 1173 K) after Co removal and scratch pre-treatment, the cutting length was less than 200 m and crater wear was severe. Using the tools coated with diamond at low temperatures (from 680 to 779 K) after Co removal and scratch pre-treatment, following increase of the substrate temperature, the cutting length became long and crater wear became mild. Compared with the tool that had been coated with diamond at high temperature after Co removal and scratch pre-treatment, the tools that had been coated diamond at low temperature after the same pre-treatment displayed improved cutting performance. Especially, the tool that had been coated with diamond at 779 K provided be more than 10 times longer life than the tool that had been coated at high temperature after same pre-treatment.