Tribology;
Research;
Institute,;
Traction;
Power;
State;
Key;
Laboratory,;
Southwest;
Jiaotong;
University,;
Chengdu;
610031,;
China;
Sichuan;
Province;
Key;
Laboratory;
for;
Corrosion;
and;
Protection;
of;
Materials,;
Sichuan;
University;
of;
Science;
and;
Engineering,;
Zigong;
643000,;
China;