Effects of oxygen and nitrogen gases on the dynamics between the interfaces of self-mated titanium pairs

Yuh-Ping Chang,Huann-Ming Chou,Jin-Chi Wang,Li-Ming Chu

doi:10.1177/1687814016645065

Abstract

The chemical reactions of titanium in air include both TiO2 and TiN. The phenomena are quite complex, and the reaction mechanisms are still unclear. However, as titanium is in widespread use all over the world, it is important that the reaction mechanisms be thoroughly investigated. Therefore, in this study, the continuous variations in the electrical contact resistance and the friction coefficient are simultaneously measured to monitor the dynamics of self-mated titanium pairs in an air, O2 or N2 gas flow. When a large amount of TiO2 formed on the surface of the plate for Ti/Ti, the results showed the tribo-physical phenomena of higher electrical contact resistance, friction coefficient almost doubled and severe wear. When a large amount of TiN formed on the surface of the plate for Ti/Ti, the results showed the tribo-physical phenomena of lower electrical contact resistance, friction coefficient almost halved and mild wear with some lubrication. Therefore, variations in the electrical contact resistance can be applied to determine whether the chemical reaction on the surface was TiO2 or Ti with TiN. The unsymmetrical frictional models and wear mechanisms of the self-mated titanium pairs in the air, O2 or N2 gas flow were proposed.

Highlights

Titanium and its chemical reactions are widely applied in industry
A method which used the continuous variations of the electrical contact resistance (ECR) and the friction coefficient for monitoring the dynamics of self-mated titanium pairs in different atmospheres was investigated in the previous study.[17]
The responses of the ECR and the friction coefficient with a sliding distance produced by the self-mated titanium pairs (i.e. Ti/Ti) in an air, O2 or N2 gas flow were synchronously measured to investigate the relationships of the chemical reactions and tribological properties

Summary

Introduction

Titanium and its chemical reactions are widely applied in industry. the equilibrium phase diagrams of titanium and TiO2 are quite complex.[1]. A method which used the continuous variations of the electrical contact resistance (ECR) and the friction coefficient for monitoring the dynamics of self-mated titanium pairs in different atmospheres was investigated in the previous study.[17]. The interface of the plate comes into intermittent contact with the surface of the pin during the unsymmetrical friction process It is always interacting with the atmosphere, producing chemical reactions on the surface of the plate, even though its temperature is lower than the surface of the pin. The main parameter influencing the rise in surface temperature is the sliding speed.[19,20,21] the reciprocating speeds were set at lower than 600 cpm (cycles per minutes) in this study in order to investigate in depth the effects of oxygen and nitrogen gases on the dynamics between the interfaces of self-mated titanium pairs. The plates were polished by different grades of emery papers to an average surface roughness, Ra, in the range of 0.08– 0.13 mm

Experimental procedures

Experimental results and discussion

Declaration of conflicting interests

Conclusion