Micro-structural, electrical, and tribological properties of SiC/DLC composite coating grown by PLD on steel

Abstract

Protective diamond-like carbon (DLC) composite coating was grown on cylindrical steel surface in a simple inclined pulsed laser deposition (PLD) process. Based on this kind of flexible film-synthesis method, mixed deposition was used to generate the gradient interface that could enhance adhesive strength in Ti/SiC interface, and periodic SiC/DLC layers were grown to reduce residual stress of the pure DLC film. This kind of PLD-grown SiC/DLC composite coating on the curved thin steel that was imitated as piston cylinder showed excellent adhesive property and toughness. Compared with the bare steel, DLC-filmed steel strip had a much lower friction coefficient, higher nano-hardness, and enhanced elastic modulus. Raman spectroscopies showed transform of the micro-structure in DLC layers during friction process, revealing the important reason for reducing friction coefficient. Electrical conductivity test displayed the DLC-filmed steel strip was in high resistance state, although its thickness was only 1.27 μm. Further on, good adhesive strength, excellent toughness and high resistance state of SiC/DLC composite coating could be applied in the MEMS advices.