Instrumented-Indentation for Mechanical Characterization of Boron Carbide Nano-Composite Coatings

Abstract

AbstractBoron carbide (BC) is well known as a coating material that is important for a wide range of technological applications. The applicability of boron carbide stems from the fact that it is a very hard material with high lubricity, high elastic modulus, low specific gravity, and good chemical stability. Disadvantages, however, include extreme brittleness and sometimes poor adhesion. Recently, a reactive sputtering involving boron carbide targets and hydrocarbon gases has been used to produce novel nano-composite boron carbide thin films comprised of BC nano-crystals embedded in a matrix of hydrogenated amorphous carbon (DLC). The microstructure of these thin films is similar to that of other metal carbide/DLC nano-composite films. The present paper discusses the results of Vickers indentation experiments carried out on four different samples of boron carbide/DLC coatings that were sputtered deposited onto 52100 steel disks. The four different samples resulted from four different levels of hydrocarbon gas flow during processing. Acoustic emission data was recorded simultaneously with the indentation experiments. The indentations and the associated crack patterns were observed using scanning electron microscopy.