Plasma sprayed hydroxyapatite adhesion strength

The procedure to evaluate adhesion strength of plasma-sprayed hydroxyapatite coatings has been described earlier. The presence of a thin plasma-sprayed titania bond coat (see Chapter 6.3.2.2) considerably enhances the adhesion strength to a Ti6Al4V substrate of titania/HAp tandem coatings compared to HAp coatings without a bond coat. 

Figure 7.32 Peel adhesion strength of plasma-sprayed hydroxyapatite coating on a Ti6AI4V foil without (circles) and with a titania bond coat (crosses). The size of the symbols reflect the statistical error of the measurements. Extension of the regression...

Figure 7.34 Grit-blasted titanium surface (a) and laser gas-nitrided Ti surface, etched to form a dendritic microstructure that promotes enhanced adhesion strength of a plasma-sprayed hydroxyapatite layer (b) (Yang et al., 2009). ( With permission by Elsevier.)...

Figure 7.40 Development of all-through cracks in a plasma-sprayed hydroxyapatite coating of about 200 pm thickness, 10 0.5 pm average surface roughness (fta), 5 1% porosity and 50 9 MPa tensile adhesion strength (Heimann et at., 2001).

Yang, S., Man, H.C., Xing, W., and Zheng, X.B. (2009) Adhesion strength of plasma-sprayed hydroxyapatite coatings on laser gas nitrided pure titanium. Surf. Coat. Technol., 203 (20-21), 3116-3122. 

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