Author(s)

S.-I. Nishida, N. Hattori, Y. Nakabaru & A. Tsuchiyama

Abstract

As is generally known, Titanium alloy has excellent properties for its lightweight, high strength ratio, high anti-corrosive resistance etc. On the other hand, as Ti alloy is not so good at wear resistance, there occasionally appear some problems at the contact area with the other metals. Therefore, surface treatment of Ti alloy would be one good solution for the above problems. Diamond-like carbon (DLC) would be one of the most practical methods for compensating the defect of Ti alloy’s properties due to its high hardness, electrical insulation, resistance to chemical attacks, superior smooth surface, excellent wear resistance etc. Rotating bending fatigue tests had been performed in order to investigate the effect of DLC coating on the fatigue properties of Ti-6Al-4V alloy. The DLC films have been deposited on Ti alloy specimens using an ionization deposition method. Four kinds of specimens coated for different coating times were prepared for the fatigue test. The result obtained in this test shows that the fatigue limit and internal hardness improved as the coating time becomes longer and the fatigue limit was improved by 100MPa as compared to the specimen without surface treatment. It is considered that this result would be due to compressive residual stress generated in the specimen’s surface during the process of the DLC coating. Keywords: Ti alloy, fatigue strength, DLC film, hardness, fatigue crack initiation and propagation.

Keywords

Ti alloy, fatigue strength, DLC film, hardness, fatigue crack initiation and propagation.