| LAser Shock Adhesion Testing (LASATesting) of Plasma-Sprayed Hydroxyapatite (HAP) Coating of Ti-Based Substrates | ||
| Dr. Vincent Guipont1, Dr. Michel Jeandin1, Mr. Francois Borit1, Dr. Sophie Barradas2, Prof. Rui Vilar2, Mr. Tolga Tavsanoglu3, Prof. A. Addemir3, Dr. Sebastien Bansard4, Prof. Khiam A. Khor4, Mr. Yuji Ichikawa5, Prof. Kazuhiro Ogawa5, Ms. Mariette Nivart6 and Mr. Laurent Berthe6, 1Center for Plasma Processing, CNRS UMR 7633, ECOLE DES MINES DE PARIS / C2P, BP 87, Evry, 91003, France, 2Departamento de Materiais, INSTITUTO SUPERIOR TECNICO, Avenida Rovisco Pais, Lisbon, 1049-001, Portugal, 3Metallurgical and Materials Engineering Department, ISTANBUL TECHNICAL UNIVERSITY, 80626 Maslak, Istanbul, Turkey, 4School of Mechanical & Aerospace Engineering, NANYANG TECHNOLOGICAL UNIVERSITY, 50 Nanyang Avenue, Singapore, 639798, Singapore, 5Fracture & Reliability Research Institute, TOHOKU UNIVERSITY, 6-6-11-718, Aoba, Aramaki, Aoba-ku, Sendai, 980-8579, Japan, 6UPR CNRS 1578, LALP (Laboratoire pour l'Application des Lasers de Puissance), 16 bis, Avenue Prieur de la Côte d'Or, Arcueil, 94114, France The coating-substrate adhesion strength is a key factor which does characterize the quality of hydroxyapatite (HAP) coatings such as those for biomedical applications. In the present work, adhesion was studied using the recently-developed advanced Laser Shock Adhesion Test, namely LASAT. Before spraying, spraying conditions were investigated as a function of the type of powder, in particular. Three types of HAP powders, i.e. a commercial powder and two lab-scale-produced powders obtained by mechanical grinding and by spray-drying respectively, were studied. The study involved optical and scanning electron microscopy and X-ray diffraction analysis in addition to direct observation of the sprayed particles in the jet using a "SprayWatch" system. LASATests showed the influence of substrate surface preparation especially. Various grit blasting conditions and the influence of a thin PVD bond-coat prior to HAP spraying. First, adhesion was all the higher because substrate roughness was great. Second, PVD pre-metallization with Au-Pd was shown to improve adhesion dramatically. All the results were discussed in the light of the microstructural study of coating-substrate interface cross-sections before and after LASATesting. These led to the conclusion that further improvements in current HAP coating can still be done and that LASAT can be claimed to be a powerful tool to help in this. | ||