Interaction of diamond with molybdenum during ion plasma deposition

Abstract

Interaction of high energy molybdenum atoms generated by cathode sputtering and carbon is studied in the process of metallization of diamond grains. X-ray diffraction and differential thermal analysis (DTA) of metallized diamond powders show that high energy atoms of the carbide-forming metal excite the surface carbon atoms, and several types of carbide are formed depending on the condensation temperature: a carbide with a structure amorphous to X-rays, cubic Mo 2C, hexagonal MoC, and β-Mo 2C. DTA of the Mo-metallized ACM-grade diamond powders (of 28-20 μm grit size) demonstrates that the carbides formed are the high temperature phases when annealing the powders with cubic Mo 2C or hexagonal MoC layers which are exothermic processes which occur in the temperature range 500–850°C. This effect, as is evident from the X-ray phase analysis data, corresponds to the recrystallization of these phases into a lower temperature carbide, i.e. β-Mo 2C. When the formation behaviour of different carbides at various condensation temperatures of the high energy molybdenum atoms is examined, the conditions of rapid cooling to the condensation temperature need to be considered.