Grown of superlubricity a-C:H/MoS2 film on 9Cr18Mo steel for industrial application

Abstract

Abstract For the purpose of extensive application of superlubritic solid films material, the steel substrate as the most widely used engineering material should be taken into consideration instead of lab-used Si substrates. In present work, the bilayer a-C:H/MoS2 film was grown on a 9Cr18Mo steel substrate with a Ti/TiN/TiCN transition layer to assure strong interfacial adhesion. A steady state of superlubricity (friction coefficient ~ 0.008) was obtained under high normal loads (beyond 15 N) in open atmosphere not only on Si substrate but also on 9Cr18Mo steel substrate, though the roughness of which is 10 times higher than that of the Si substrates. Compared to the naked 9Cr18Mo steel, the introduction of the a-C:H/MoS2 film can reduce the friction coefficient and wear rate to nearly 1/50 and 1/6, respectively. Detailed experimental studies reveal that realization of ultralow friction is attributed to low contacting stress (5 N and 11 N) induced structure of oriented molybdenum disulfide in wear debris. Further, amorphous molybdenum disulfide accelerates the formation of oriented graphene ribbon under high contacting stress (15 N and 20 N) at the contact interfaces helping to achieve superlubricity. Thus, our work here provides a strategy for design an industrial scale superlubricity friction system.