Comparison of tribological properties of CrN, CrTiN and CrTiBN coatings sliding against SiC and SUS440C balls in water

CrN, CrTiN and CrTiBN coatings were deposited on Si(100) and 316L stainless steel substrates by unbalanced magnetron sputtering system, and their microstructures, mechanical and tribological properties were characterized systematically. The results showed that CrN coatings consisted of CrN nanograins. After doping Ti and B elements, there mainly existed as TiN0.3 nanograins and amorphous BN phases for CrTiN coatings and CrTiBN coatings. When sliding against SiC balls in water, CrTiN coatings exhibited the best wear resistance among three kinds of coatings due to the great mechanical properties and the highest adhesion strength to substrates. Although the CrTiBN/SiC tribopair exhibited lower friction coefficient (0.18) than the CrTiN/SiC tribopair (0.26), the corresponding specific wear rate was higher due to the serious delamination. When three kinds of coatings slid against SUS440C balls, the CrTiBN coatings showed the lowest friction coefficient and the lowest specific wear rate simultaneously.