(MoDTC) has received notable attention as an antifriction additive in engine oil. However, it has wear
accelerating effects on the sliding contact of DLC and
steel under boundary lubrication condition. MoDTC is a
degradable material and can change its structure into
MoS2, MoO3, Mo2C and Mo during friction test.
Whether MoDTC itself enhances the wear or its byproducts materials has still been unknown. Therefore, it
is important to clarify which elements actually give
severe effects on the wear acceleration. This paper
focuses on the wear properties of Si-DLC coatings and
SUJ2 ball with MoDTC and Mo2C particles as additives
in engine oil under boundary lubrication condition. It
shows that Mo2C gave severe effect on the wear
properties of Si-DLC coatings.