Wear testing of hybrid epoxy nanocomposites

Abstract

Polymer composites containing different fillers and/or reinforcements are frequently used for applications like automotive parts, gear assemblies etc., in which friction and wear are critical issues. In particular, they are now being used as sliding elements, which were formerly composed of metallic materials only. The extremely large surface area is one of the most attractive characteristics of nano-particles because it facilitates creating a strong interaction between fillers. These also have been found to improve the wear properties. Various nano-particles have been incorporated in polymer matrices for this purpose and there have been positive results. Epoxy and hybrid epoxy nano-composites are developed by in situ polymerisation. Specific wear rate of the nano-composites developed for wear applications have been presented in this work. The study of variation of different parameters like loading and velocity and their consequent effects on the specific wear rate is done. A number of tests are conducted on a pin-on-disc type machine. Different sliding velocities for conducting the wear tests are 105, 209 and 314 cm/s. Different normal loading conditions for consideration in the experiment are 20 N, 30 N and 40 N. It is evident from the tests that for every sample, the specific wear rate increases with the increase in the normal loading. However, in case of variation in velocity, it is initially higher at 105 cm/sec, significantly drops at 209 cm/sec and rises to the maximum value at 314 cm/sec. Firstly, variation of a single nanoparticle Cloisite 30B is done in order to find its optimum concentration. It is varied from 1% to 4% and the tests present that 2% Cloisite 30B exhibits the minimum specific wear rate. Then, addition of TiO2 is done. It is varied from 2% to 6% and the tests show that of all the samples the hybrid sample of 2% Cloisite 30-B and 2% TiO2 shows the least specific wear rate. This reduction in specific wear rate is quite significant when compared with specific wear rate of the neat sample. This indicates that hybridisation of organo-modified nano-clay (Cloisite 30B) and TiO2 is a justified combination for enhancing the wear properties of epoxy hybrid nano-composites.