Influence of Load and Sliding Speed on Super-Low Friction of Nitinol 60 Alloy under Castor Oil Lubrication

摘要

In the present paper, the influence of load and sliding speed on super-low friction of Nitinol 60 alloy was investigated experimentally using Nitinol 60 alloy pin sliding over GCr15 steel disk under castor oil lubrication. Super-low coefficient of friction (COF) of Nitinol 60 alloy was achieved at the stable state, corresponding to so-called superlubricity regime in the presence of castor oil. The experimental results indicate that sliding speed employed in the friction tests plays great roles in the lubrication behaviors of Nitinol 60 alloy. When the friction tests are executed from low sliding speed to high sliding speed, COF decreases at the initial stage and on the contrary, COF increases at the stable stage. However, with the increase in load, COF firstly increases and then decreases at the initial stage. COF is unstable but still super low and remains almost the same value at the stable stage. These phenomena are explained and discussed in viewpoint of the characteristics of castor oil during the friction tests. It is found that the influence of sliding speed on the lubrication behaviors of Nitinol 60 alloy under castor oil lubrication is more obvious than that of load due to the characteristics structure of castor oil, therefore maintaining appropriate level of sliding speed to achieve super-low friction of Nitinol 60 alloy.