J.P. Pathak

Wear characteristics of Al-Si alloys

Abstract The wear characteristics of Al-Si alloys containing 2–20 wt.% have been studied using a pin-on-disc type wear testing machine at room temperature. The effects of alloy composition, sliding distance, sliding speed and load on wear rate of Al-Si alloys have been investigated. It has been found that the wear rate is strongly dependent on alloy composition, applied load and sliding speed. The wear rate decreases and the load-bearing capacity of the alloy increases with increasing silicon content. The nature of the wear process changes with alloy composition and experimental conditions.

On the wear characteristics of leaded aluminium bearing alloys

Abstract The wear characteristics of a series of leaded aluminium bearing alloys have been studied under dry sliding conditions under a room atmosphere using a pin-on-disc-type wear testing machine. The wear volume has been measured as a function of the alloy composition, sliding distance, normal load and sliding velocity. Optical and scanning electron microscopic examinations of the test specimen, wear track and wear debris have been carried out to aid in the elucidation of the wear mechanisms. It has been observed generally that the wear rate decreases with increasing lead content and hardness of aluminium-based alloys.

On wear characteristics of leaded aluminium-silicon alloys

Abstract Wear characteristics of Al-Si-Pb alloys with silicon content from 2 to 20 wt% and lead from 2 to 10 wt% have been studied using a pin-on-disc type wear testing machine at room temperature. The effects of applied load, sliding velocity and alloy composition on wear rate of Al-Si-Pb alloys have been investigated. It has been found that wear rate is strongly dependent on alloy composition, applied load and sliding speed. Wear rate decreases and load bearing capacity of the alloy increases with increase in lead content. Wear rate of Al-Si-Pb alloys initially decreases and then increases with increase in sliding speed. Wear mechanism map predicting nature of the wear processes can be prepared for aluminium alloys.

On the mechanical and wear properties of copper-lead bearing alloys

Abstract Copper-lead alloys varying in lead content from 5 to 40 wt.% were prepared by stirring and chill casting. The room temperature ultimate tensile strength, 0.2% compressive and tensile proof stresses, and the hardness and percentage elongation, decrease progressively with increasing lead content. Wear tests carried out at room temperature using a pin-on-disc wear testing machine revealed that increasing lead content improves the wear resistance of these alloys. The frictional resistance, measured in terms of an increase in the temperature rise of the test specimen, decreases with increasing lead content of the alloy up to 35 wt.%, beyond which it increases with increasing lead content.

Friction and wear properties of bushing bearing of graphite filled short glass fibre composites in dry sliding

Abstract The paper discusses the effect of particulate additions on the friction and wear of short glass fibre reinforced epoxy resin composites. Particles of graphite were mixed with the epoxy resin prior to composing with short glass fibre. Bushing samples were prepared with varying graphite contents and percentage of glass fibre. Tests were performed on bushing samples to obtain the friction and wear for the composites with varying applied load and sliding time. It was foumd that graphite has an important impact on the wear and friction properties of glass fibre reinforced epoxy resin composites. It is clear that after an incubation period, there is a nearly linear relationship between wear load and sliding time. Wear increases with load and time, but as the amount of graphite in the composite increases, its value decreases irrespective of the applied load and sliding time, due to increase of wear resistance in matrix materials. However, friction increases only with sliding time but decreases with the increase of graphite particles irrespective of time.

Tribological behaviour of conventional Al-Sn and equivalent Al-Pb alloys under lubrication

Two compositions of conventional aluminium base alloys were selected and equal amounts of tin and lead as a soft phase were incorporated separately. Impeller mixing and chill casting technique were employed for the preparation of the alloys. Mechanical properties of as cast alloys were evaluated at room temperature. Frictional behaviour of the alloys was studied in detail under lubrication while creating different frictional states by imposing 5–60 kg of normal load on the bearing (bush) mating surface. It was found that aluminium tin and leaded aluminium alloys slightly differ in mechanical properties. Frictional states created during sliding against steel shaft (hardness 55–60 Rc) under oil lubrication were not much different. Leaded aluminium alloy bushes show marginally lower friction than the conventional ones.

Wear characteristics of HSLA steel

HSLA steel being a promising material in numerous applications, was subjected to wear studies under dry sliding conditions at varying conditions of loads and sliding speeds. Wear debris were extensively studied under optical, stereo- and scanning electron microscopes and also by X-ray diffraction. In order to understand the wear mechanism, wear tracks were examined under optical and scanning electron microscopes. In addition, depth of strain hardened zone below sliding surface was measured under different conditions of loads. This study showed that wear rate initially increased either with increased load or sliding speed and debris generated was a mixture of oxide and metal powders, but after attaining a peak in wear rate, a decreasing trend was observed for load as well as sliding speed studied. This decreasing trend has been attained due to domination of oxidation process as a result of rise in temperature at higher values of loads and sliding speeds. These oxides formed with temperature rise covered the wear tracks and wear rate decreased. Finally, depth of strain hardened zone beneath the sliding surface was observed to increase with load.

Wear and friction characteristics of mica-filled fibre-reinforced epoxy resin composites

Abstract The aim of the present paper is to improve the friction and wear properties of unidirectional E-glass fibre reinforced epoxy resin by adding mica particles. The experimental observations show that mica particles increase the hardness and compressive strength of unidirectional E-glass fibre reinforced epoxy resin composites, which gives better tribological application of fibre composites in industry.

Wear behaviour of graphitic aluminium composite sliding under dry conditions

Abstract A modified mixing and casting procedure was used for the preparation of Al-1.2 Si-0.8 Fe–Gr composite (wt.%). Graphite and gray cast iron powders were blended and dispersed in Al-1.2 Si matrix alloy melt and poured in a cast iron mould. Gray cast iron powder worked as carrier for graphite particles. The presence of graphite improves the ultimate tensile strength, tensile and compressive stress but beyond 1 % of graphite all properties deteriorate. However, hardness continuously increases and percentage elongation reduces with graphite. In wear studies, different mechanisms: mild-oxidative, oxidative-metallic and severe-metallic, are operative in the different combinations of sliding velocities and applied loads.

Room temperature wear characteristics of Al-Si-Cd bearing alloys

Abstract The aim of the present work is to assess the behaviour of aluminium-silicon-cadmium bearing alloys, particularly the role of cadmium as a solid lubricant during wear testing at room temperature. Compositions of Al-Si-Cd alloy containing 3 wt.% and 5 wt.% silicon and 1–5 wt.% cadmium were prepared by a special plunging and stirring technique. Wear characteristics of as-cast alloy were studied under dry sliding conditions at a relative humidity of about 68% and an ambient temperature of 304 K. The wear volume was measured as a function of sliding distance, applied load, sliding velocity and alloy compositions by using a pin-on-disc wear test machine. Optical microscopy of wear debris and scanning electron microscopy of worn test pin surfaces revealed the interaction of the debris with mating surfaces and the mode of wear. It was found that cadmium worked as a solid lubricant and reduced wear and friction of the matrix alloy.