Examination of tribological properties of plasma surface layer using special test equipment

Abstract

The hardness, adhesion, and tribological behaviour of magnetron-deposited coatings (TiN and (Ti, Al)N) have been determined and related to microstructure composition. To enhance the adhesion of the coating, plasma nitriding of substrates was employed. Wear behaviour, coefficient of friction and contact temperature were measured using computerized data acquisition and processing. The bonding force between the coated samples and counter material was monitored and controlled by newly designed and constructed equipment, to keep a constant level of load during sliding. With the new hardware and software, it was possible to monitor on-line the development of the wear process. The hardware consisted of PC computer, piezoelectric transducer, sensors with high sensitivity, microprocessor-controlled measuring system, AD/DA transformer, and multichannel plotter. The wear zone morphology and characteristics of the surface layer structure and other important properties were investigated using scanning electron microscopy (SEM) and X-ray diffraction analysis (XRD). Energy dispersive X-ray analysis (EDAX) of the wear scars on pins provided essential information on the wear characteristics. Based on the results, the correlations between the mechanical properties, the surface structure, and tribological characteristics are explained.