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2 Bulletin of the Polish Academy of Sciences. Technical Sciences

2 2018

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Microstructural, electrical, thermal and tribological studies of copper-fly ash composites through powder metallurgy

Thanga_Kasi_Rajan S., Balaji A. N., Narayanasamy P., Vettivel S. C.

Bulletin of the Polish Academy of Sciences. Technical Sciences

2018

Vol. 66, nr 6

935--940

This research work address the fabrication of copper (Cu) matrix composites, reinforced with fly ash (FA) particulates with 3, 6, 9 and 12 wt.% using the powder metallurgy route. The microstructural, physical, electrical, thermal, mechanical and tribological properties of thus fabricated Cu-FA composites have been studied. Optical microstructural characterization of the composites exposed persuasively uniform distribution of FA reinforcement with minimum porosity. The mixed powder SEM images revealed the homogeneous dispersion of fly ash particulates in the copper matrix. The hardness values showed improvement with increase in the weight percentage of FA in the Cu matrix. Electrical conductivity was measured using the four-point probe method at room temperature. Thermal conductivity was measured with a thermal diffusivity analyzer at room temperature. The fly ash addition leads to weakening the conductivity of Cu-FA composites. The tribological properties of Cu-FA composite specimens were investigated using a Pin-on-disc tribo testing machine against an EN81 steel contour disc. The specific wear rate of the composites tended first to decrease, which was attributed mainly to the formation of a mechanically mixed layer on the worn surface. Then it would increase as the FA content increased because of reduction in ductility and brittle oxide cracks associated with adding more FA particulates. It seems that composites with FA percentages below 9wt.% have optimum properties of microstructure, hardness and wear resistance, which is suitable for applications such as electrical sliding contacts, electrical discharge machining and spot welding electrodes.

Mechanical and wear behaviour of the Al-Mg-nano ZrC composite obtained by means of the powder metallurgy method

Sankaranarayanan G., Balaji A. N., Velmanirajan K., Gangatharan K.

Bulletin of the Polish Academy of Sciences. Technical Sciences

2018

Vol. 66, nr 5

729--735

This work concentrates on the impact and contribution of zirconium carbide (ZrC) and magnesium to the mechanical and tribological properties of aluminium matrix composites. Distinctive weight portions of zirconium carbide, containing fixed weight fractions of magnesium and strengthening aluminium composites, were prepared utilising the entrenched cold-press sintering technique used in powder metallurgy. The uniform powder mixture was obtained by using planetary ball milling and it was then observed by using the scanning electron microscope technique. The hardness of the hybrid composite increased along with increase in the amount of the ZrC particle. The wear losses of sintered Al-Mg-ZrC composites were explored by directing sliding tests in pin-on-disc equipment. Hybridisation of reinforcements also decreased the wear loss of the composites at high sliding load and speed. This study reveals that the hybrid aluminium composite can be considered a unique material with high strength, low weight and wear resistance that will find their application in components to be used in the automobile and aero space engineering sectors.