Effect of Sintering Temperature on Adhesion Strength of Hydroxyapatite Coating Layer of Titanium TNTZ Prepared by Dip Coating Method

Abstract This study investigates the effect of sintering temperatures on the adhesion strength of hydroxyapatite (HA)-coated Ti–29Nb–13Ta-4.6Zr (TNTZ) prepared using the dip coating method. TNTZ samples were coin-type specimens with a diameter of 15 mm and a thickness of 4 mm, and polished surfaces. The sol-gel, which is used to help the hydroxyapatite adhere to the metal surface of the material, was prepared by mixing KH 2 PO 4 liquid, Ca(NO 3 ) 2 liquid, and NH 4 OH as a catalyst. The coating process uses the dip coating method with an immersion time of 30 seconds and a withdrawal speed of 4 mm/s. The sintering process was carried out at a temperature of 700 °C, 800 °C, and 900 °C for 1 hour, respectively. The surface morphologies were then examined using optical and scanning electron microscopes. Coating layer thickness, covered surface, and addition strength were then measured by using related equipment. The results show that the measured surface properties depend significantly on the sintering temperatures. The additional strength decreases with increasing temperature although layer thickness increases. The higher sintering temperatures seem to lead to more cracks and detachment of the hydroxyapatite layer, reducing the covered surface area and adhesion strength. The low sintering temperature of 700°C achieves better coating characteristics and adhesion strength of titanium TNTZ.