E!ect of chemical composition on hydrophobicity and zeta potential of plasma sprayed HA/CaO}P O glass coatings

Multilayered plasma sprayed coatings on the surface of Ti}6Al}4V alloys have been prepared, which were composed of an underlayer of HA and a surface layer of a CaO}P O glass}HA composite, with 2 or 4wt% of glass. Contact angle and surface tension variation with time, for both water and a protein solution, were determined by the sessile and pendent drop methods respectively using the ADSA-P software. Wettability studies showed that hydrophobicity 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}P O glass, being lower on the composite coatings than on HA. Zeta potential (ZP) results showed that composite coatings presented a higher net negative charge than HA coatings and that ZP values were also in#uenced by the content of the glass. This study demonstrated that the surface properties of those coatings may be modi"ed by the addition of CaO}P O glass. 2001 Published by Elsevier Science Ltd.