Wear-resistant and stable low-friction nanodiamond composite superhard coatings against Al2O3 counter-body in dry condition

Conventional machining lubricants pose environmental hazards and increase production costs. This study addresses this challenge by investigating nanodiamond composite (NDC) coatings deposited on WC–Co substrates as a lubricant-free alternative for sustainable machining. The NDC films show superior hardness (65 GPa) compared to the substrate (22 GPa) and enhanced adhesion (HF2). The NDC's unique self-lubrication results in a low and stable friction coefficient (COF ≤ 0.095) and exceptional wear resistance (7.45 × 10 −8 mm 3 /N·m) in dry tesing against Al 2 O 3 counter-body. Compared to CVD diamond, NDC coatings show a 47.8 % reduction in COF and a 31.65 % enhancement in wear resistance, promoting environmentally friendly machining practices. • Eco-friendly CAPD deposits 10 μm thick NDC films on WC−Co at 3.5 μm/h rate. • High-performance NDC films boast 65 GPa hardness and 688 GPa Young's modulus. • NDC films show superior adhesion compared to CVD diamond (HF2 vs. HF6). • NDC maintains stable, low friction (0.095 CoF) against Al 2 O 3 in dry conditions. • NDC films exhibit wear resistance (7.45 × 10^-8 mm 3 /N·m) for harsh environments • NDC coatings reduce COF by 47.8 % and enhance wear resistance by 31.65 % vs diamond.