Bioactive glass suspensions preparation for suspension plasma spraying

Abstract

A bioactive glass was dry-milled and sieved in order to obtain powders with particle size finer than 63 μm. Two suspensions, with different particle size distribution (D50 = 8.3 μm and D50 = 2.2 μm), were subsequently obtained from milling those powders in an organic solvent (dipropylene glycol methyl ether) by using two different grinding steps. The obtained suspensions were characterised and stabilised to produce adequate feedstocks to be used in suspension plasma spraying technique. For that purpose, sedimentation tests as well as rheological characterisation were carried out on both suspensions.

Only the suspension feedstock containing the finest particle size, managed to produce a coating with suitable thickness and adherence on the substrate when a TiO2 bond coat was used. Besides X-ray diffraction findings confirmed the amorphous nature of the obtained coatings. However coating microstructure displayed many round, closed pores and surface observation revealed the presence of abundant non-deformed splats.