Wear behavior and self tribofilm formation of hot-pressed Al₂O₃/TiC/CaF₂ ceramic composites sliding against cemented carbide

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• 作者：Jianxin Deng ; Tongkun Cao ; Xuefeng Yang ; Jianhua Liu ; Junlong Sun ; Jinlong Zhao
• 关键词：B. Composites ; C. Wear resistance ; D. Al₂O₃ ; Self-lubrication
• 刊名：Ceramics International
• 出版年：2007
• 期刊代码：13_02728842
• 类别：ms
• 出版时间：March 2007
• 卷：33
• 期：2
• 页码：213-220
• 文件大小：1272 K

摘要

Al₂O₃/TiC ceramic composites with the additions of CaF₂ solid lubricants were produced by hot pressing. Sliding wear tests against cemented carbide were performed on these ceramic composites using the ring-block method. The friction coefficient and wear rates were measured. Results showed that the friction coefficient and the specific wear rate decreased with the increase of CaF₂ content up to 10 vol.%, with further increases in CaF₂ content, both the friction coefficient and the wear rate increased rapidly. SEM observations showed that self tribofilms were consistently formed on the wear surfaces. Two types of tribofilms are present on the worn surface depending on the CaF₂ content. A dense self tribofilm with a smooth surface associated with small friction coefficient and low wear rate was formed by the releasing and smearing of CaF₂ solid lubricants on the wear surface when with low CaF₂ content (less than 10 vol.%). This dense self tribofilm acted as solid lubricant film between the sliding couple, protected the ceramics from severe wear by brittle microfracture, and thus significantly reduced the friction coefficient and the wear rate. A broken tribofilm associated with high friction coefficient and large wear rate was formed when with high CaF₂ content (more than 10 vol.%). The reason is that large degradation of mechanical properties occurred in samples with high CaF₂ contents.