High Temperature Erosion-Corrosion of Wear Protection Materials

Solid particle erosion at high temperatures (HT) is a serious issue in various industrial applications, like ventilators, exhaust systems of HT reactors, incineration plants. Due to HT and process gases, erosion is accompanied with oxidation/corrosion. When erosive wear emerges as a lifetime-limiting process, wear protective materials are applied. The combined HT erosive and oxidative attack on these is of major interest and not sufficiently understood for typical wear protection materials. Thereto, we selected three standard wear protection materials and investigated their erosive-corrosive behaviour at 650 °C. Herein used solutions include an alumina, a hypereutectic metal matrix composite (MMC) and an oxidation resistant austenitic steel. Each material was tested in a HT centrifugal solid particle erosion test rig applying 45° and 90° impingement angle. Additional comparative tests were performed at room temperature. A high particle velocity of 65 m/s, as is typical in exhaust pipes, was selected for this study. Extensive post-test analyses of the surface changes and oxidation behaviour were performed to identify the main wear mechanisms. It was found that the alumina exhibited highest wear loss at all conditions investigated, due to its brittle behaviour. Oxidation played no role for this material. The MMC showed pronounced oxidation intensifying the wear loss at HT. Also, the austenite showed extensive tribo-oxidative behaviour, albeit due to erosive particle embedding and formation of an in situ wear protective tribo-layer, the most favourable results were obtained. At oblique impact it showed 3-times less volumetric wear loss than the alumina, and at normal impact 11-times less.