Effect of the addition of Si into V2O5 coatings: Structure and tribo-mechanical properties

Abstract Vanadium oxide (V 2 O 5 ) is one of the lubricious oxides with the potential to be used as a solid lubricant at elevated temperatures. However, the material itself is not hard wear-resistant, so most of the research has focused on adding V into hard nitride coatings that could lead to the formation of a self-lubricating V 2 O 5 layer when heated. The other possible solution, which has been less studied, is to look for mechanisms to enhance the hardness of the oxide coating. In this research, we investigate the effect of the addition of Si into the V 2 O 5 coatings, aiming to find conditions that lead to enhance hardness and/or reduced wear while keeping the high temperature lubricity of the V 2 O 5 structure. For this, Si modified V 2 O 5 coatings were deposited using a dual magnetron sputtering system. The results showed that small additions of Si ( 2 O 5 coatings up to 5 times while keeping the same temperature dependence of the coefficient of friction than V 2 O 5 . Dry sliding experiments using the pin-on-disc configuration against silicon nitride balls were performed at 25, 300 and 600 °C. Wear factors in the 10 −7  mm 3 /Nm range were obtained, indicating a good wear resistance. Further addition of Si into the V 2 O 5 structure led to a loss of the crystalline ordering and a significant reduction in the hardness.