Effect of MoO₃ Tabular Crystals on TiAl Matrix Composites under Different Test Loads

ABSTRACT

The friction and wear behavior of TiAl matrix self-lubricating composites (TMSCs) with MoO₃ tabular crystals (MTCs) sliding against a GCr15 steel ball is tested using a constant speed of 0.2 m/s at room temperature under different loads from 6.65 to 16.65 N. The result reveals that TMSCs show a consistently lower friction coefficient in a certain range from 0.2 to 0.6 and less wear rate from 0.29 × 10⁻⁴ mm³ N⁻¹ m⁻¹ to 0.49 × 10⁻⁴ mm³ N⁻¹ m⁻¹ compared to TiAl-based alloy. Moreover, the friction coefficient and wear rate of TMSCs decrease with an increase in test load. MTCs in the deformed layer will be refined to produce interfacial shear slip and reduce the shear stress because of the weak binding force of MTCs in the sliding process, which can facilitate the formation of a deformed layer and protect the deformed layer from spalling failure. In addition, MTCs on the worn surface of TMSCs can reduce the shear stress directly. Hence, MTCs can promote antiwear of the deformed layer and reduce the friction on the worn surface of TMSCs. MTCs can play a better role in antiwear and antifriction when the test load is higher.

KEYWORDS:

• Tabular crystal
• tribological properties
• deformed layer
• shear stress

Acknowledgments

The authors thank the Material Research and Testing Center of Wuhan University of Technology for their assistance. The authors are grateful to M. J. Yang, S. L. Zhao, and W. T. Zhu of the Material Research and Test Center of WUT for their kind help with electron probe microanalysis and FESEM.

Funding

This work was supported by the National Natural Science Foundation of China (51275370) and the Fundamental Researceh Funds for the Central Universities (2015-zy-051 and 2015-yb-008).