Investigation on High-Temperature Wear Resistance of Co-Based Superalloys Modified by Chromium-Aluminizing Coatings

This study systematically explores and expands upon the research questions, revealing the scientific principles and engineering value of chromium-aluminum (Cr-Al) co-diffusion coatings in enhancing high-temperature friction performance. This study addresses the critical need for wear resistance in GH5188 cobalt-based alloy stator bushings operating in high-temperature environments. The high-temperature wear resistance mechanism of aluminized coatings modified with Cr elements on the GH5188 alloy, based on thermal diffusion technology, was investigated. The experimental results indicate that the high-temperature wear resistance of the samples was directly related to the type and content of oxides in the wear scars and debris. After friction at 700 °C, the aluminized coating on the GH5188 alloy showed the lowest oxide content in the wear scars, primarily composed of CoAl₂O₄. The oxides in the wear scars of the GH5188 alloy and Al-Cr co-aluminized coatings were mainly CoCr₂O₄ and Cr₂O₃, with the Al-Cr co-aluminized coating showing the highest amount of wear debris. The Cr-rich oxide debris not only has high thermodynamic stability but also exhibits relatively low high-temperature growth stress, making it difficult to spall. Additionally, the higher diffusion coefficient of Cr³⁺ accelerates the reoxidation of wear debris pits, resulting in excellent high-temperature wear resistance. The wear rate of the Al-Cr co-aluminized coating was reduced by 30% compared with the GH5188 substrate and by 69% compared with the aluminized coating. In summary, the key findings are not only applicable to cobalt-based alloys but can also be extended to a broader range of material systems and engineering applications. This provides new perspectives and methodologies for the design of high-temperature coatings, the development of materials for extreme conditions, and interdisciplinary applications.