Diamond Synthesis in a 50kW Inductively Coupled Atmospheric Pressure Plasma Torch

摘要

Polycrystalline diamond coatings have been deposited on metal substrates using a50 kW atmospheric pressure inductively coupled plasma torch. The argon-hydrogen-methane plasma generated has a free stream active area of 35 sq. cm. and a temperature of approximately 5000 K. Growth rates obtained for a highly diluted plasma are of the order of 10 um/hour. In this work, a flat plate boundary layer flow reactor is used to generate diamond growth at a surface in a well understood fluid dynamic situation. The growth morphology is found to vary significantly with reactor processing conditions and location downstream of the leading edge. Scanning electron microscopy indicates that well faceted crystals are obtained with growth along the 100 and 111 planes. Nearly continuous films are also formed and found to be lower quality. The results are compared to the predictions of a two-dimensional boundary layer model of the reacting flow environment. Measured and predicted growth rates show good agreement. (jhd)