Polyamide-imide (PAI) polymer is a high-temperature resistant polymer, which is used as contact breaker material because of its high electrical insulation property. The working conditions of contact breakers arise from the wear and friction problem conditions of these materials. Therefore, the tribological behavior of PAI polymer is important. In this study, the friction and wear performance of pure PAI polymer and PAI composite [PAI+12% graphite+3% polytetrafluoroethylene (PTFE)] were studied in two different cooling environmental conditions (with and without air cooling). Wear tests were carried out with the configuration of a polymer pin, on a rotating AISI 316 L stainless steel disc. Test conditions were atmospheric conditions, 50 N, 100 N, and 150 N loads and 0.5, 1.0, 2.0 and 3.0 m/s sliding speeds. For sliding without air cooling and sliding with air cooling, the results show that the coefficient of friction and wear rates for pure PAI and PAI+12% graphite+3% PTFE composite, slightly decrease and increase with the increase in applied load and sliding speed values, respectively. In addition, for the range of loads and sliding speeds of this study, low coefficients of friction and high specific wear rates are registered at sliding under air cooling conditions. Finally, the wear mechanism includes adhesive and abrasive processes.

A new combinatorial optimization problem, the Bandpass problem, was defined in Bell and Babayev (2004) [4]. Recently, this problem was investigated in detail in Babayev et al. (2009) [5]. In this paper, we first present some new mathematical models of the Bandpass problem. Then related to this problem, we introduce a software called OrderMatic which is very useful for teaching permutations

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In the present study, we attempt to use powder of glass spheres filler and reinforce material in HDPE to produce composite structure and then evaluate its mechanical properties to study the effect of welding parameters and filler content on mechanical properties of HDPE. The effect of welding parameters (tool rotational speed, the plunge depth and the dwell time) on friction stir spot welding properties of high density polyethylene/glass spheres (hollow) polymer composites sheets was studied.