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The present study focusses to enhance the wear resistance of electroless Ni-P coatings with the co-deposition of selflubricating nano graphite particles synthesized by mechanical milling using a high energy planetary ball mill. The coatings were developed on an aluminum substrate and nano graphite particles were co-deposited (4 g/l) into the Ni-P matrix using alkaline hypophosphite reduced electroless bath. Changes in properties after heat treatment at 220 °C for 4 h in vacuum have been correlated with morphological and microstructural changes shown by field emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD) respectively. Energy dispersive analysis of X-ray (EDAX) determined the quality and elemental composition of coatings. Wear resistance, coefficient of friction (pin on disc) and microhardness of electroless Ni-P-graphite nanocomposite coatings were calculated and contrasted with Ni-P coatings. The outcomes reveal that the size of synthesized graphite nanoparticles is 20 nm. Microhardness and wear resistance of electroless coatings have improved after heat treatment. Excellent wear resistance has been observed at the cost of some hardness in Ni-P-graphite nanocomposite coatings over Ni-P coatings.

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Nano-sized bioceramic hydroxyapatite (HAp) reinforced with carbon nanotubes (CNT) is synthesized using the sol-gel technique with phosphoric acid and calcium nitrate tetrahydrate as a phosphorous and calcium precursor, respectively. The 'as synthesized' nanocomposite powder is characterized for phase and structural analysis using X-ray diffractometry, FTIR and Raman spectroscopy. The morphological analysis of HAp/CNT nanocomposite is done using field emission scanning electron microscopy. The tribological properties including wear rate and coefficient of friction are done by coating HAp and HAp/CNT nanocomposite on implant material (SS 316L) using spin coating technique. The wear is reduced by 24.57% for HAp-coated SS316L and 29.6% for HAp-5% CNT-coated SS316 substrate. The addition of CNT in HAp matrix leads to lowering of the coefficient of friction.