Tribological behaviors of DLC films in sulfuric acid and sodium hydroxide solutions

Tribological behaviors of three typical kinds of diamond‐like carbon (DLC) films (a‐C, a‐C:Cr, and a‐C:H) in sulfuric acid and sodium hydroxide solutions were investigated. The a‐C film showed the lowest stable coefficients of friction (COF) in both sulfuric acid and sodium hydroxide solutions but the worst wear resistance in sulfuric acid solution. The a‐C:H film showed the highest COF in sulfuric acid solution and the best wear resistance in both sulfuric acid and sodium hydroxide solutions. The a‐C:Cr film exhibited superior comprehensive tribological performance in sulfuric acid solution, while in sodium hydroxide solution, high COF and very poor wear resistance was observed. What is more, friction and wear mechanism was revealed by investigating the friction‐induced material evolutions on the sliding surface.