Cathodic alkaline treatment of zirconium to give the ability to form calcium phosphate

The cathodic polarization technique to form an alkaline environment on a zirconium (Zr) surface, discussed in the present study, is unique, and gives the ability to form calcium phosphate in a simulated body fluid to Zr; on the other hand, many previous studies have been conducted using immersion in alkaline solutions. In this study, two discrete techniques were investigated. Zr was cathodically polarized in an electrolyte without calcium and phosphate ions, and Zr was cathodically polarized in another electrolyte containing calcium and phosphate ions, Hanks' solution, to directly form a calcium phosphate layer. The surface was characterized using X-ray photoelectron spectroscopy, and the performance of the material was evaluated by immersion in Hanks' solution. As a result, the ability to form calcium phosphate in Hanks' solution was given by cathodic polarization in the Na₂SO₄ solution containing H₂O₂. In addition, a cathodic potential under -1.5 V _SCE is required to form hydroxyapatite directly in Hanks' solution. This research clearly reveals useful surface modification techniques giving the ability to form calcium phosphate in a simulated body fluid by cathodic polarization.