Abstract
Three kinds of processing procedure, including conventional sintering, hot-isostatic pressing, and their combination, were explored to prepare hydroxyapatite-silver composites with high density and improved ceramic-metal interface properties. Optimizing the densification procedure, which allowed the desired fraction of Ag to remain within the apatite matrix after densification, has solved a problem related to the low wettability of Ag on hydroxyapatite. The major outcome of this study is that hot-isostatic pressing enables to reinforce the interface between hydroxyapatite and silver, thus improving the structural consistency of the prepared composite. Results are supported by investigations on microscopic fracture mechanisms. It is shown, that a toughening effect arose from the microscopic crack-bridging mechanism operated by the elasto-plastic stretching of unbroken Ag ligaments along the crack wake. A Raman piezo-spectroscopic technique enabled the in situ quantitative assessment of this bridging toughening mechanism.
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