Optimizing of Coating Layers Parameters of (Nano Hydroxyapatite/TiO2 NPs) on Nitinol SMAs by Electrophoretic Deposition

Abstract

This study aims to obtain the optimal variable for depositing (HA, TiO2 and Composite) Nanomaterial on NiTi SMAs. Taguchi approach (with L9 array) was used to obtain the optimal conditions for coating produced by Electrophoretic deposition (EPD) techniques. The deposition process was done in different conditions (voltage, time, concentration and degree of grinding). Voltages were used (20, 40 and 60) volts, the time is (2, 4 and 6) min, the degree of the surface roughness (180, 500 and 1200) μm while the concentration of HA and TiO2 are (2, 4, and 6) g/L for each one. Chitosan (biopolymer) was used as binder material to the ceramic materials. The result of the Taguchi approach detected that the best conditions of HA layer are (20 V, 4 min, 2%C and the degree of surface 180), TiO2 is (20 V, 4 min, 4%C and the degree of surface 180) and composite layer is (60 V, 4 min, 4%C and the degree of surface 180). Solutions stability was measured by utilizing Zeta potential tests; which clarified good stability for all of them. Optical microscope and scanning electron microscopy were used to characterize and study the surface of the coating layers. The bonding adhesion was measured using a tape test in order to evaluate the adhesion bonding between the coating and substrate. It found that the percentage of removal coating area for samples were (8.8%for HA, 4.9% for TiO2 and 6.9% of the composite layer.

Keywords

• coating
• electrophoretic deposition
• hydroxyapatite
• chitosan؛ taguchi approach