Oxidation behaviour of silicon carbide bonded diamond materials

Diamond bonded materials can be produced without pressure by infiltration with liquid Si. They are very wear-resistant and show high chemical resistance in water, acids and alkaline solutions. However, there are no reliable data on the oxidation resistance of these materials. The oxidation resistance has been investigated by thermal analysis and by long-term ageing at 900 - 1000°C up to 100 h. It is shown that not only the surface diamonds are oxidized, but the oxidation of the diamond reaches deep into the volume of the materials. The analysis of the mass changes and the corrosion depth shows that the oxidation rate is probably determined by the diffusion of the reaction gases. The application limits regarding the temperature of the material under oxidizing conditions are therefore in a similar range as those of diamond materials produced under high pressure.