Friction behavior of amorphous-BN-cubic-BN dual-layered film

Abstract

In a tribological comparison in which two kinds of BN films, i.e., cubic BN (c-BN) and amorphous BN (a-BN), were chosen as the test films, cubic BN film was found to have excellent tribological properties such as low friction coefficient and good wear resistance in air. Compared with c-BN film, the amorphous BN film was found to have a lower wear resistance, although it showed a lower friction coefficient. Therefore, it is highly desirable to combine these two excellent properties of c-BN and a-BN films, i.e., the good wear resistance of c-BN and the low friction property of a-BN. In order to achieve such a combination of properties, we conceived the idea of fabricating a dual-layered BN film having amorphous-cubic structure. More specifically, a first layer of c-BN is deposited onto a Si substrate by means of ion plating, and then a second layer of a-BN is deposited onto the c-BN layer with a gradient interlayer formed between the two BN layers. The tribological property of this film has been examined using a reciprocating tribometer under a wide load range of 0.1–4.9 N. The result shows that this combined c- and a-BN film has a superior low friction property and good wear resistance.