Authors: A A Ahmad A M Alsaad
Publish Date: 2007/10/25
Volume: 30, Issue: 4, Pages: 301-308
Abstract
The longterm failure of the total hip and knee prostheses is attributed to the production of wear particles at the articulating interface between the metals ceramics and polymers used for surgical implants and bonefixtures Therefore finding an adhesive and inert coating material that has low frictional coefficient should dramatically reduce the production of wear particles and hence prolong the life time of the surgical implants The novel properties of the nontoxic diamondlike carbon DLC coatings have proven to be excellent candidates for biomedical applications However they have poor adhesion strength to the alloys and biomaterials The addition of a thin interfacial layer such as Si Ti TiN Mo and Cu/Cr and/or adding additives such as Si F N O W V Co Mo Ti or their combinations to the DLC films has been found to increase the adhesion strength substantially In our study grade 316L stainless steel and grade 5 titanium alloy Ti6Al4V were used as biomaterial substrates They were coated with DLC films containing boron additives at various levels using various Si interfacial layer thicknesses The best film adhesion was achieved at 8 and 20 on DLC coated Ti6Al4V and grade 316L substrates respectively It has been demonstrated that doping the DLC with boron increases their adhesion strength to both substrates even without silicon interfacial layer and increases it substantially with optimum silicon layer thickness The adhesion strength is also correlated with the hydrogen contents in the BDLC films It is found to reach its maximum value of 700 kg/cm2 and 390 kg/cm2 at 2/7 and 3/6 for CH4/Ar partial pressures in mTorr ratio for Ti6Al4V and 316L substrates respectively
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