No abstract

No abstract

In this study, the effects of artificial aging heat treatment on mechanical properties and corrosion behaviour of AA6XXX alloy were investigated. The effects of artificial aging time on microstructure and mechanical properties of alloy were analysed and at the same time corrosion behaviour was determined by corrosion tests. For experimental investigations, the alloy samples prepared in appropriate sizes were heated to 540°C (±0.5°C) with heating rate 10°C/min. by electrical resistance ceramic furnace. For the solution heat treatment, samples were kept in the furnace at this temperature for 4 h. The samples taken from the furnace were firstly poured into iced water at 10°C and then subjected to artificial aging at 190°C for 2, 4, 6, 10, 12 and 24 h. Finally, the samples taken from the furnace were left to cool down in stagnant air. The results show that the mechanical properties of the material were increased with increasing aging time. Corrosion tests have shown that the corrosion resistance of the alloy depends on the artificial aging time. The best value of corrosion resistance was obtained at a temperature of 190°C at 10-h aging period.

No abstract

The use of unfilled pure elastomer parts is limited in friction wheels, roller tires, sealing elements, and dynamic friction air suspension applications requiring high wear resistance. This study investigates the mechanical and tribological properties of new nanocomposites obtained by adding hydroxyl-functionalized graphene nanoplatelets at 1, 4, and 8 phr (parts per hundred rubber) ratios to the carbon black filled main rubber compound of sealing elements designed for axle hubs. The synergistic effect of nanofiller materials on the wear behavior of nanocomposites was tested with a block-on-ring wear tester under dry sliding conditions at 1000 rpm and 15 N normal load conditions. The worn surfaces were examined with scanning electron microscopy and circularly polarized light–differential interference contrast topology microscopy to reveal the wear mechanism. The addition of functionalized graphene nanoplatelets to the nanocomposite compound caused significant changes in tensile strength and elongation values by changing the cross-link density. The wear rate of nanocomposites prepared with graphene nanoplatelets at 1, 4, and 8 phr ratios was 11.15%, 25.24%, and 36.54% lower than the main rubber mixture used, respectively. While the hysteresis loss decreased by 14.83% at 1 phr, this value increased in other filler ratios. Significant differences in temperature change occurred as the amount of filler increased. After the test, the temperature values of nanocomposites with 1 and 4 phr filler ratios were between about 85–89°C, while it was measured as 99°C in nanocomposites with 8 phr filler ratios. It has been observed that the homogeneous distribution of two-dimensional carbon allotropes such as graphene nanoplatelet added to the rubber matrix at the optimum rate will improve tribological properties such as better surface lubrication, low wear rate, and low friction coefficient.