The effect of different metallic counterface materials and different surface treatments on the wear and friction of polyamide 66 and its composite in rolling-sliding contact

Original article can be found at: http://www.sciencedirect.com/science/journal/00431648 Copyright Elsevier B. V. DOI: 10.1016/S0043-1648(03)00054-1The effect of different metallic counterface materials and different surface treatments on the tribological behaviour of polymer and polymer composite under unlubricated, non-conformal and rolling-sliding contact has been investigated. The most widely used polymer materials - unreinforced polyamide 66 and its composite (RFL4036) – were tested. The metallic materials include aluminium, brass and steel and the surface treatments include Tufftride** treated (known as nitrocarbonising) and magnesium phosphate treated, etc. Tests were conducted over a range of slip ratios at a fixed load of 300 N, 1000 rpm rotational speed using a twin-disc test rig. The experimental results showed that the polyamide composite exhibited less friction and wear than the unreinforced polyamide 66 when running against steel and aluminium counterfaces. However, when tested against brass, polyamide 66 exhibited lower wear than the composite. The surface treatment of steel has a significant effect on the coefficient of friction and the wear rate, as well as on the tribological mechanism, of polyamide 66 composites. It has been observed that a thin film on the contact surface plays a dominant role in reducing the wear and friction of the composite and in suppressing the transverse cracks. This study clearly indicates that both the characteristics of the different counterface metallic materials and the surface treatment greatly control the wear behaviour of polyamide 66 and its composite.Peer reviewe

Processing of aluminum-graphite particulate metal matrix composites by advanced shear technology

Copyright @ 2009 ASM International. This paper was published in Journal of Materials Engineering and Performance 18(9) and is made available as an electronic reprint with the permission of ASM International. One print or electronic copy may be made for personal use only. Systematic or multiple reproduction, distribution to multiple locations via electronic or other means, duplications of any material in this paper for a fee or for commercial purposes, or modification of the content of this paper are prohibited.To extend the possibilities of using aluminum/graphite composites as structural materials, a novel process is developed. The conventional methods often produce agglomerated structures exhibiting lower strength and ductility. To overcome the cohesive force of the agglomerates, a melt conditioned high-pressure die casting (MC-HPDC) process innovatively adapts the well-established, high-shear dispersive mixing action of a twin screw mechanism. The distribution of particles and properties of composites are quantitatively evaluated. The adopted rheo process significantly improved the distribution of the reinforcement in the matrix with a strong interfacial bond between the two. A good combination of improved ultimate tensile strength (UTS) and tensile elongation (e) is obtained compared with composites produced by conventional processes.EPSR

Cast in situ Cu–TiC composites : synthesis by SHS route and characterization

Original article can be found at : http://www.sciencedirect.com/ Copyright Elsevier [Full text of this article is not available in the UHRA]The present investigation discusses observations pertaining to the synthesis of Cu-based composites containing TiC particles in the range of 45–50 volume % by self-propagating high temperature synthesis (SHS) process. A composite with 11–13 volume % TiC dispersion was also synthesized through remelting and dilution. The composites were observed to contain a copper matrix together with a Cu–Ti intermetallic compound, TiC dispersoid particles and partially reacted graphite. The regions showing partially reacted graphite (carbon) became less prominent in the diluted composites. Al addition led to the refinement of TiC particles, higher hardness, reduced density and improved degree of formation and better homogeneity of the distribution of TiC particles. Dilution caused reduced hardness, while the density followed a reverse trend.Peer reviewe