Anti-sand erosion and tribological performance of thick DLC coatings deposited by the filtered cathodic vacuum arc

In order to improve the abrasion and erosion resistance in severe environments, 50-mu m-thick diamond like carbon (DLC) films with a hardness of 27.3 GPa were fabricated using filtered cathodic vacuum arc technique coupled with a high-voltage pulse power. The microstructures, mechanical properties and tribological and anti-sand erosion performance of DLC coatings with different thicknesses were evaluated. The increase in thickness from 3 to 50 mu m, resulting the adhesion of the coatings increased from HF1 to above HF1 level. Radial cracks or delamination were not observed at the edge of the indentation of 50-mu m-thick coating. The coefficient of friction (COF) was decreased but wear rate was increased as coating growing thicker due to the stacking of graphited debris between the asperities. Mechanical polish was carried out on the 50-mu m-thick films, which lead to the COF and wear rate decreased from 0.079 to 0.067 and 14.7 to 6.78 x 10(-8) mm(3)/N.m at 20 N. The sand erosion test demonstrated that as the increase in thickness from 3 to 50 mu m, average mass loss rate significantly decreased from 0.81 to 0.035 mg/g. High load-bearing capacity and ability to restrain the initiation and propagation of cracks were responsible for the great erosion resistance for thick coating.