Indentation damage to boron carbide–DLC coatings with different compositions

Recently, a reactive sputtering process involving boron carbide (BC) targets and hydrocarbon gases has been used to produce novel, nano-composite thin films comprised of nano-sized amorphous BC regions embedded in a matrix of hydrogenated amorphous carbon (Diamond-like carbon, DLC). This paper discusses the results of Vickers indentation experiments carried out on four different BC–DLC composition coatings that were sputtered deposited onto 52 100 steel disks. The indentation depths ranged from less than 10% of the coating thickness to many times more than the coating thickness. In all cases, different coating compositions resulted in different indentation depths. Composite hardness curves have been generated for the different coatings. The indentations and the associated crack patterns were observed using scanning electron microscopy, and coating crack lengths were quantified.