Preparation of bioactive Ti and its alloys via simple chemical surface treatment

TLDR

A simple chemical method was developed to induce bioactivity in Ti and its alloys. The process treats the substrates in 10 M NaOH and 600 °C heat‑treatment to form a sodium titanate layer that, through ion exchange with simulated body fluid, generates hydrated titania that promotes graded apatite formation. The treated surfaces develop a dense, bone‑like apatite layer in simulated body fluid that bonds strongly to bone and provides a graded stress transfer, enabling load‑bearing artificial bone applications. © 1996 John Wiley & Sons, Inc.

Abstract

A simple chemical method was established for inducing bioactivity of Ti and its alloys. When pure Ti, Ti-6Al-4V, Ti-6Al-2Nb-Ta, and Ti-15Mo-5Zr-3Al substrates were treated with 10M NaOH aqueous solution and subsequently heat-treated at 600°C, a thin sodium titanate layer was formed on their surfaces. Thus, treated substrates formed a dense and uniform bonelike apatite layer on their surfaces in simulated body fluid (SBF) with ion concentrations nearly equal to those of human blood plasma. This indicates that the alkali- and heat-treated metals bond to living bone through the bonelike apatite layer formed on their surfaces in the body. The apatite formation on the surfaces of Ti and its alloys was assumed to be induced by a hydrated titania which was formed by an ion exchange of the alkali ion in the alkali titanate layer and the hydronium ion in SBF. The resultant surface structure changed gradually from the outermost apatite layer to the inner Ti and its alloys through a hydrated titania and titanium oxide layers. This provides not only the strong bonding of the apatite layer to the substrates but also a uniform gradient of stress transfer from bone to the implants. The present chemical surface modification is therefore expected to allow the use the bioactive Ti and its alloys as artificial bones even under load-bearing conditons. © 1996 John Wiley & Sons, Inc.