Oxidation behaviour of high quality freestanding diamond films by high power arcjet operating at gas recycling mode

Oxidation may cause degradation of mechanical, thermal and optical properties of freestanding CVD diamond films at elevated temperatures, and thus may impose severe technical limitations for applications of freestanding diamond films. In the present investigation oxidation behaviour of high quality freestanding diamond films prepared by high power d.c. are plasma jet operating at gas recycling mode has been studied. It was found by thermogravimetry that the diamond films started to oxidize at approximately 650 degreesC, whilst the rate of oxidation increased substantially with increasing temperatures. Experimental observations confirmed that grain boundaries were the most preferred site for oxidation damage. Detailed studies were made on the influence of high temperature oxidation on the optical, thermal, and mechanical properties of high quality freestanding diamond films. Our results demonstrated that the high quality freestanding films prepared by high power d.c. arcjet can be safely used below 800 degreesC for a short time period of 180 s, which is more than enough for certain important IR applications. (C) 2004 Elsevier B.V. All rights reserved.