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Self-replenishing solid lubricant films on boron carbide

1999; Maney Publishing; Volume: 15; Issue: 4 Linguagem: Inglês

10.1179/026708499101516605

1743-2944

Ali Erdemir, O.L. Eryılmaz, G.R. Fenske,

Diamond and Carbon-based Materials Research

This study introduces a simple annealing procedure that leads to the formation of a self-replenishing solid lubricant film on bulk boron carbide (B 4 C) and its coatings. The procedure uses short duration annealing at 800°C for 15 min. Subsequently, the specimens are cooled to room temperature and tested in a pin on disc machine. During annealing, B 4 C reacts with oxygen in air and forms a glasslike boron oxide (B 2 O 3 ) layer on the exposed surface. Eventually, this layer reacts spontaneously with moisture in the surrounding air, thus forming a thin boric acid (H 3 BO 3 ) film. The friction coefficients of 440C steel and zirconia pins against this film are 0·04–0·06. Electron microscopy and Raman spectroscopy were used to elucidate the formation and self-lubricating mechanisms of this solid boundary film on sliding B 4 C surfaces.