Friction and wear behaviors of carbon derivative filled ultra high molecular weight polyethylene (PE) composite and hybrid composite coatings

The wear of ultra-high molecular weight polyethylene (PE) components is accepted as a major disadvantage leading to osteolysis and limiting the life of the implants. Therefore, the studies with regard to improve the tribological and mechanical properties of PE continues. For this aim, various carbon derivative additives (GNP, GO, CNT and GNP-GO) were used as fillers to produce PE based composites possessing advanced friction and wear properties. The PE/GNP, PE/GO, PE/CNT composite and PE/GNP-GO hybrid composite powders filled with different contents (0,1, 0,3, 1,0 and 2,0 wt.%) of GNP, GO, CNT and GNP-GO were fabricated by firstly liquid phase ultrasonic mixing. Then, these powders were coated on powder PE by hot press molding. The wear and friction behavior of composite and hybrid composite coatings were investigated in sliding against a stainless steel counterface (316L) and experiments carried out in a reciprocating friction testing machine in dry sliding and Hanks balanced salt solution environments. The microstructural analysis results of coatings confirmed that there was interaction between the all fillers and PE. The highest microhardness values were detected at composite coatings with 0,7wt.% CNT, 3,0 wt% GNP and 1,0 wt.% GO contents. The many majorities of coatings showed more stable and lower friction coefficient variation than the PE due to the lubricating effect of the fillers in dry sliding and Hanks solution environments. The coatings with 3,0 wt.% GNP and 1,0 wt.% GO under dry sliding condition and the coating with 0,7 wt.% CNT in the Hanks solution environment were the best filler amounts that improve wear resistance compared to PE. The synergistic effect of GNP and GO fillers were observed at the microstructural and tribological analysis results of PE/GNP-GO hybrid composite coatings, but any improvement was not achieved in their microhardness values and wear resistances. This study suggests the use of PE/0.7CNT composite coating that had high microhardness and the least wear debris as biomaterial instead of PE.