G0300903 Evaluation of fatigue strength of high adhesive DLC-coated SUS316 with notch

Abstract

It is unknown about the relationship between hardness of DLC film and fatigue strength in detail, though hard film coating method is applied everywhere. When hard film coating method is applied for industrial products, it's desirable to clarify the relationship between film and fatigue strength in terms of safety and strength. In the present study, we conducted to clarify a relationship between fatigue strength and DLC (diamond-like carbon)'s adhesion by using the DLC coating method that can control deposition condition, i.e. gas species, power and intermediate layer during deposition influenced on the property of DLC film. The specimens consisted of 4 steps; machining, polishing, applying a solution treatment, and DLC coating. We used INSTRON 8800 which is a servo hydraulic fatigue testing machine in fatigue testing. Fatigue testing was conducted under the condition of stress ratio: R=-1, repetition frequencies: f=7 Hz, at a room temperature. Based on the results of the fatigue testing, fatigue strength of the DLC-coated test pieces was 71% higher than that of solution treated specimens. Therefore, it can be expected that fatigue strength improves if highly-adhesive DLC is applied. It suggests that highly-adhesive film is effective to improve fatigue strength of substrate.