Material removal during the sliding of hydroxyapatite against UHMWPE.
Hydroxyapatite has been rubbed against ultra-high-molecular-weight-polyethylene (UHMWPE) under calcium-containg aqueous solutions. Further, hardness tests were carried out in air and in calcium-containing solutions whose pH ranged from pH 5 to pH 9. Hardness was found to vary with pH with a peak at around pH 7, i.e. - a chemomechanical effect was observed. Wear tests consisted in sliding hydroxyapatite samples against a UHMWPE disk for eight hours when lubricated by the same solutions as those used for the hardness tests. Volume loss, pH and calcium concentration were measured for up to 8 hours of sliding. Linking wear tests results with hardness results and supersaturation levels, it was concluded that two wear mechanisms occurred. A chemical mechanism depending on supersaturation occurred at the early stages of sliding. The wear rate was essentially independent of hardness during this stage. After a few hours, depending on the supersaturation of the lubricant, the chemical mechanism turned into a chemomechanical mechanism dependant on hardness.
Mazeau
G
G
La Formation d'Ingenieurs de l'Université Paris-Sud-Orsay, Plateau du Mallon, Bat. 620, 91140 Orsay, France.
Czernuszka
J T
JT
D001672:Biocompatible Materials / Q000737:chemistry* / Q000592:standards*; D001696:Biomechanical Phenomena; D004347:Drug Interactions; D017886:Durapatite / Q000737:chemistry* / Q000592:standards*; D019544:Equipment Failure Analysis; D006245:Hardness Tests; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008153:Lubrication; D008422:Materials Testing; D011095:Polyethylenes / Q000737:chemistry* / Q000592:standards*; D013997:Time Factors
D001672:Biocompatible Materials; D011095:Polyethylenes; C111601:ultra-high molecular weight polyethylene; D017886:Durapatite