Wear properties and mechanisms of nylon and carbon-fiber-reinforced nylon in dry and wet conditions

A microinjection machine was used to prepare specimens of nylon 1010 and carbon fiber (CF)-reinforced nylon 1010 composites. The friction and wear properties were investigated with a ring-block wear tester in wet and dry conditions. The wear rate of nylon 1010 increased, but the friction coefficient decreased in water in comparison to that in dry sliding. The wear resistance of CF-nylon increased remarkably by two orders of magnitude due to the reinforcement of the CF. The minimum wear rate was obtained with a 20 vol % content of CF filled in nylon in wet lubrication. The wear rate of CF-nylon in dry sliding friction was as much as approximately eight times, and the friction coefficient decreased to approximately half its value compared with that in water under a load of 200 N. The morphologies and the wear mechanisms of worn surfaces were also examined with Fourier transform infrared spectroscopy and scanning electron microscopy. The results show that the hydrolization of amide groups and the resulting decrease in hydrogen bonds between the molecules of nylon 1010 were important factors that led to a high wear rate of nylon in water. We concluded that the fiber, protruding out of the rubbing surface and carrying the main load between the contacting surfaces, held up the swelling properties and improved the mechanical strength of nylon, which would account for the evident reduction of wear in the nylon composites. (C) 2004 Wiley Periodicals, Inc.