Effect of chemical composition on hydrophobicity and zeta potential of plasma sprayed HA/CaO-P2O5 glass coatings

Multilayered plasma sprayed coatings on the surface of Ti-6Al-4V alloys hav e been prepared, which were composed of an underlayer of HA and a surface l ayer of a CaO-P2O5 glass-HA composite, with 2 or 4 wt% of glass. Contact an gle and surface tension variation with time, for both water and a protein s olution, were determined by the sessile and pendent drop methods respective ly using the ADSA-P software. Wettability studies showed that hydrophobicit y of the coatings increase with the glass addition. The work of adhesion of albumin was also altered in a controlled manner by the addition of the CaO -P2O5 glass, being lower on the composite coatings than on HA. Zeta potenti al (ZP) results showed that composite coatings presented a higher net negat ive charge than HA coatings and that ZP values were also influenced by the content of the glass. This study demonstrated that the surface properties o f those coatings may be modified by the addition of CaO-P2O5 glass. (C) 200 1 Published by Elsevier Science Ltd.