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Summary
On this paper, diamond coatings with totally different microstructure had been ready on cemented carbide substrates by HFCVD method. The adjustments of grain progress mode and dimension of diamond coating below totally different substrate temperature (800 °C, 850 °C, 900 °C) and carbon supply focus (2%, 4%, 6%) had been studied, and the variations of coating efficiency had been explored. Each substrate temperature and carbon supply focus affect grain dimension. When the grain dimension is in micron scale (0.5 ∼ 6 μm), the expansion mode is columnar crystal competing progress. When the substrate temperature reaches 900 °C and the carbon supply focus is 6%, the diamond grain might be absolutely secondary nucleated, and the grain dimension will scale back to the nanometer scale (20 ∼ 50 nm). The expansion mode is particle cluster accumulation progress and the speed of progress will increase considerably. The rise of grain dimension will enhance the adhesion of the coating and its resistance to put on and exterior loading. Nonetheless, it could result in bigger friction coefficient, which is about 0.1. As a result of small grain dimension, the adhesion pressure of nanocrystalline diamond coating is clearly smaller than micrystalline diamond coating, however the friction coefficient is barely 0.03.
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