蒸馏水润滑下Si_3N_4-白口铸铁摩擦面上表面膜形成过程的观察

为了观察蒸馏水润滑下的Ｓｉ３Ｎ４—白口铸铁摩擦面上表面膜的形成过程，在环—块磨损试验机上进行了不同磨程的磨损试验，通过扫描电镜（ＳＥＭ）对不同磨程的铸铁磨面进行了观察，对表面膜的形成机理进行了初步探讨。结果表明，当Ｓｉ３Ｎ４与白口铸铁配副摩擦时，由于铸铁中碳化物的剥落而形成剥落坑，Ｓｉ３Ｎ４磨屑嵌入剥落坑并氧化和水解，其反应产物富集于剥落坑中，脱水聚合后形成硅胶，从而在磨面形成了含硅胶的表面膜。表面膜的形成保护了陶瓷和铸铁磨面，使其变得很光滑，从而使摩擦系数降至０．０２，并使陶瓷和铸铁的磨损几乎接近于零。

Observation on the Process of Tribofilm Formation for Si 3N 4-White Iron Pair Lubricated with Distilled Water

In order to observe the tribofilm on the worn surface of white iron for Si 3N 4-white iron pair lubricated with distilled water, the tests with different sliding distances were carried out on a wear tester type M 200. Then the worn surfaces were detected by means of SEM. Furthermore, the formation mechanism of the trbofilm was explored simply. The reason for the tribofilm formation is that the carbides in cast iron spall off during the wearing tests and the spalling pits are formed on the wearing surface of cast iron. Then, the debris of Si 3N 4 are embedded into the pits and are oxidized and hydrolyzed in situ. The products of reactions are concentrated in the pits and polycondensed into silicagel. So the silicagel film is formed on the wearing surface. The formation of the tribofilm facilitates the surfaces of Si 3N 4 and iron to smooth. As a result, the friction coeffictent of the pair is lowered to 0.02, and the wear rates of Si 3N 4 and iron are near zero.