密着性に優れたダイヤモンド被覆工具によるAl-18mass%Si合金の切削特性

抄録

Coated cutting tools with CVD diamond film requires high adhesion strength between the diamond film and substrate. We studied the adhesion strength of diamond-coated WC-Co tools using Microwave Plasma CVD (MWPCVD) and an Al-18%Si alloy cutting test using diamond cutting tools.
Diamond was coated onto tools using an MWPCVD apparatus. The reaction gas was a mixture of methane and hydrogen. Substrate temperature was varied from 673K to 1173K by controlling the microwave output power and growth pressure.
SEM observation revealed that grain size grew with increasing substrate temperature. All deposits were clear diamond crystals. XRD showed that deposits were cubic diamond. Raman spectroscopy showed that deposits synthesized at a lower substrate temperature (673K) were of higher quality than those synthesized at a higher substrate temperature (1173K). A scratch adhesion strength test, from 673K to 873K showed that adhesion strength increased from 873K to 1173K, but it decreased with increasing substrate temperature. Deposition synthesized at 873K showed the best adhesion strength. In Al-18%Si alloy cutting test of using diamond-coated tools synthesized at 873K, diamond film did not peel after a 800m cutting test and the surface of Al-Si work pieces turned with diamond coating tools synthesized at 873K presented uniform roughness.
The cutting performance of Al-18%Si alloys using diamond-coated WC-Co tools was related to adhesion strength.