Nanoscale alloy coatings

This chapter presents the current trends in this area with emphasis on load-bearing orthopaedic and dental implants. A detailed account on the general and the localized corrosion of conventional metalhc implants is provided. Novel fabrication strategies of nanostructured hydroxyapatite-based coatings and their roles as barrier coatings are presented. Impacts of nanoscale surface modifications on the corrosion resistance of permanent implants and novel bioresorbable implants based on magnesium alloys are highhghted. 

There are no comprehensive standards or literature available on the corrosion behaviour of such nanostmctured implants. Figure 15.4 schematically represents a few likely outcomes. The following sections discuss the effeets of these modifications on the corrosion resistance of orthopaedic and dental implants More specifically, Section 15.4 discusses the effect of nanoscale surface modifications on the corrosion behaviour of titanium based alloys. Section 15.5 discusses nanoceramic coatings with emphasis on HA coatings. Current approaches in making nanostmctured coatings and nanocomposites for Mg based resorbable implants are presented in Section 15.6. 

Co, Mo and Pd [7], In addition, the activity of the Pd catalyst for the oxidative dehydrogenation of sodium lactate to pyruvate was improved by the addition of Te [8], Recently, sihca-coated Pt-Co alloys and Pt-Pd alloys covered with silica layers were prepared and used as catalysts for ethylene decomposition to form CNTs [6], The structure of the graphene that forms the walls of the CNTs was different for the two catalysts. This result indicates that the nanoscale carbon structure formed by hydrocarbon decomposition was influenced by the type of metal species in the silica-coated metal alloys. Therefore, further research on the hydrocarbon decomposition of sihca-coated alloys using other metal species is needed because it is possible to develop nanocomposites using the silica-coated metal alloy catalyst and nanoscale carbon structures. 

Supported Ni is known to be an effective catalyst for hydrocarbon decomposition [9]. In this study, silica-coated Pt-Ni alloys were prepared using a microemulsion and they were used as catalysts for ethylene decomposition to form nanoscale carbon structures. The influence of sihca-coated Pt-Ni alloy thermal treatment on the formation of the nanoscale carbon structures was also investigated. 

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