The effect of nominal specimen contact area on the wear coefficient of A6061 aluminium matrix composite reinforced with alumina particles

Abstract

Earlier work with turning and pin-on-disc tests indicated that the wear coefficient values of tungsten carbide obtained could vary significantly due possibly to the different nominal contact areas used in the various testing processes [2–4]. This paper reports the results obtained from research work carried out earlier to determine the effect of nominal specimen contact area on the wear coefficient of A6061 aluminium matrix composite (MMC) containing 20% of alumina particles. The pin-on-disc testing method was used to conduct the wear tests with speeds of 200 and 275 m/min and loads of 74 and 98 N. Square pins with a length of 25 mm and with two different nominal contact areas of 6 × 6 mm 2 and 10 × 10 mm 2 were used. The discs were made of AISI-01 cold work tool steel with a hardness of about 62 HRC. Wear tests were carried out at distances from 250 to 12,000 m. It was found that the wear coefficient values obtained from the pins with a smaller nominal contact area were indeed lower by an average of about 12%, due to the availability of smaller asperity wear volumes. The results also agree with the adhesive wear theory. Hence one should exercise extreme care in the interpretation of wear coefficient data obtained from different testing methods, or from using different nominal specimen contact areas.