AFM observation of diamond indenters after oxidation at elevated temperatures

Use of diamond indenter tips at elevated temperatures can cause oxidation and thermomechanical damage, leading to changes in their topography. A Berkovich diamond indenter has been exposed to 450 °C in air, followed by 750 °C and 900 °C in 1 bar of static, commercial purity argon (30–45 ppm O2). The effects of oxidation on the geometry of the indenter were investigated using atomic force microscopy. A Berkovich and a 10 μm tip radius conospheroidal indenter were also examined, after being subjected to 5 years of intermittent use at elevated temperatures (≤ 400 °C). Significant changes in tip topography were observed, suggesting that commercial purity argon may be an unsuitable atmosphere for high temperature indentation testing. Finally, a mechanism of oxidative etching, which may have potential as a method of sharpening indenters, is also reported.