Oxidation resistance of boronized CoCrMo alloy

Boronizing of CoCrMo alloy has been performed by means of a powder-pack method using commercial LSB powders at 850,900 and 950 degrees C for 8 h, respectively. In this study, the boronized CoCrMo alloy before and after oxidation tests were characterized using scanning electron microscopy (SEM) and X-ray diffraction (XRD). The distribution of alloy elements of boronized samples from surface to interior was determined using energy-dispersive X-ray spectroscopy (EDS). XRD study showed the boride layer formed at 950 degrees C/8 h consisted of the phases Co2B and CrB. Depending on boronizing temperature, the thickness of boride layer ranged from 2 to 11 mu m. Cyclic oxidation behavior of the boride layer has been investigated at an oxidation temperature of 950 degrees C with a total exposure time up to 50 h in air. The test results indicated that the boronized CoCrMo alloy had superior oxidation resistance compared to unboronized sample. (C) 2010 Elsevier Ltd. All rights reserved.