The wear classification of MoDTC-derived particles on silicon and hydrogenated diamond-like carbon at room temperature

Molybdenum dithiocarbamate (MoDTC) is well-known as a friction-modifier in engine oil but has wear accelerating effects on DLC/steel sliding contact. Since MoDTC was reported degradable to other materials, the effect of each material on wear acceleration has not been clarified yet. Therefore, it is necessary to divide which Mo-derived compound has a major role to enhance wear. Thus, powder-type MoDTC, MoO₃, Mo₂C, MoS_2, and Mo were dispersed into Poly-alpha-olefin (PAO), and tested on a-C:H and Si-DLC against steel ball at room temperature. For Mo₂C, MoDTC, and MoO₃, the specific wear rate of a-C:H was approximately 3.4 × 10⁻⁵, 3.2 × 10⁻⁶ and 1.5 × 10⁻⁶ mm³/Nm, respectively. MoDTC indicated higher affection than MoO₃ regardless of the particles’ hardness. Si-DLC showed better wear prevention compared to a-C:H.