Effect of Hydrothermal Treatment in Calcium Phosphate Solution on SUS304 Substrate

SUS 304 stainless steel is known to be a biocompatible material and is widely used as screws or plates. However, issues regarding iron ion release after implantation become a concern which limits the application of SUS304. Therefore, to overcome these shortcomings, surface modification on SUS304 by forming calcium layer is needed to disable iron release from the substrate and also to encourage cell attachment. In this study, initially SUS 304 substrate are subjected to electrolysis process in sodium chloride solution to form pitting corrosion. These pitting corrosion will give the anchoring effect for the calcium ions to attach. Then the substrate are subjected to hydrothermal treatment at 200°C in calcium phosphate solution for 24, 36, 48, and 60 hours for deposition of calcium ions on the pitted SUS304 surface. Surface morphology observed by scanning electron microscope (SEM) shows that the calcium ions were deposited on the surface of the SUS304 substrate regardless hydrothermal treatment time. Rockwell hardness values shows that as hydrothermal treatment time increased the hardness value decreases. Therefore, hydrothermal treatment method enables the deposition of calcium ions layer on the surface of SUS304 which will inhibit the release of iron ions and enhanced bone attachment with the implant due to the bonding of the calcium ions with the bone.