The abrasion Experimental procedure of Composite Materials

In recent years, due to the trend in designing of machines and machine elements, polymers have taken a significant role as materials for parts like cams and gears, as a substitution for conventional materials . Additionally,polymers are extensively used as materials for manufacturing of parts for mining equipment, conveyor lines, rotary valves, etc. [2]. In all these applications, polymers are exposed to abrasive wear. For the selected specimens, the tests were performed using the ASTM G65 abrasion tester [19]. The decision was based on already available experiences, not only from literature(chapter 1) but as well from our own experimental work. Nevertheless, adjustments of the test system according to the application demands could be done easily to the ASTM G65 apparatus. Adjustment of the system consisted of retrofitting of the test rig with the new nozzle which was capable to maintain the sand flow within the limits defined by application. A schematic of the test rig can be seen in Figure 2. The tested samples were fixed to the sample holder lever, which was positioned in the tangential direction in relation to the rubber or steel wheel. The sample holder lever is connected to the load lever having the same pivot. The load was applied by positioning a calibrated dead weight at the end of the load lever. During testing, the examined samples were exposed to the influence of the abrasive. The abrasive was stored in the sand tank and fed into the contact zone through an appropriate nozzle[19]. After leaving the nozzle the abrasive was entrapped in and moved through the contact zone due to the relative motion of the wheel, which was rotating in direction of the sand flow (clockwise in the schematic). Tests were carried out at modified conditions with a load of 50 N, a rotational velocity of the wheel of 200 min-1, a sand flow rate of 3 litres/minute and testing times 1.5, 3, 4.5, and 6 hours, respectively. Both test setups – with rubber wheel and with a steel wheel – were used. Before and after testing, each test sample was cleaned in ethanol and dried.Mass loss was determined by weighing the samples before and after the tests with an analytical balance (RADWAG XA 210/X,0.01 mg to 210 g, RADWAG Balances & Scales, Radom, Poland). Each test was repeated at least two times, and for comparison the volume loss for each selected testing sample was calculated. Wear tracks on the wheel surfaces were measured by a confocal microscope (Leica DCM 3D, Ernst Leitz Wetzlar, GmbH, Germany) for noncontacting assessment of the microscale topography. The size of the scanned area was 0.96 mm × 1.3 mm.