Yufu Wang

Sliding Speed and Load Dependence of Tribological Properties of Ti3SiC2/TiAl Composite

The tribological properties of Ti3SiC2/TiAl composite (TTC) slid against a GCr15 steel counterface were investigated at sliding speeds in the range of 0.2–0.8 ms−1 and loads that ranged from 2 to 8 N. The results showed that the tribological properties of TTC strongly depended on the covering percentage of tribofilm on the TTC worn surface, which varied with changes in sliding speed and load. The tribofilm mainly consisted of Al-Ti-Si oxides, which provided a self-antifriction action that resulted in a reduction in the friction coefficient and an increase in the wear rate.

Effect of graphene nanoplate addition on the tribological performance of Ni3Al matrix composites

The main objective of this work has been the characterization of wear behavior of the graphene nanoplates (GNPs) in Ni3Al matrix composites (NMC). The friction and wear behaviors of NMC with the addition of 1 wt.% GNPs against Si3N4 ball are tested under different loads using a constant speed of 0.2 m/s. Tribological test results have revealed that small amounts of GNPs are able to drastically improve the antifriction and antiwear properties of NMC. A possible explanation for these results is that, the GNPs not only provide an enhanced effect for NMC to produce better wear resistance, but also form a local protective layer on the contact surfaces to reduce the friction. The investigation shows that GNPs hold great potential applications as an effective solid lubricant for Ni3Al matrix composites and possibly other alloys.

Fabrication and properties of tungsten-copper alloy reinforced by titanium-coated silicon carbide whiskers

Titanium-coated silicon carbide whiskers were prepared by vacuum slow vapor deposition process. W-20Cu composite powder was fabricated by spray drying and calcining-continuous reduction technology. The paper adopted hot-press sintering to prepare titanium-coated silicon carbide whiskers/W-20Cu composites. Effects of addition amount of titanium-coated silicon carbide whiskers on the phases, microstructures, and properties of the composites were investigated. Titanium-coated silicon carbide whiskers/W-20Cu composites with improved mechanical properties and thermal conductivities were fabricated by hot-press sintering at 1350℃ under a pressure of 30 MPa for 2 h in pure Ar atmosphere. The transverse rupture strength and thermal conductivity of the 0.6 wt% titanium-coated silicon carbide whiskers/W-20Cu composite when compared with W-20Cu-based alloy were enhanced by 22% and 26%, respectively. With reasonable addition amount of titanium-coated silicon carbide whiskers, the composites without graphite, tungsten carbide, and silicon phases were obtained.

Effect of elastic and plastic deformations on tribological behavior of graphene-reinforced Ni3Al matrix composites

The elastic and plastic deformations have significant effect on the tribological properties of the graphene-reinforced Ni3Al matrix self-lubricating composites. The primary purpose of this study is to investigate the tribological behavior and wear mechanisms of graphene-reinforced Ni3Al matrix self-lubricating composites by researching the effects of different loads and the corresponding friction heat on the elastic or plastic deformation. The dry sliding tribology tests of graphene-reinforced Ni3Al matrix self-lubricating composites are carried out at the loads of 7, 10, 13, and 16N, respectively. The elastic or plastic deformation is judged by comparing the yield stress with the contact stress analyzed by the numerical simulation method. It is found that graphene-reinforced Ni3Al matrix self-lubricating composites exhibit good tribological properties at 13 N due to the elastic deformation, leading to the formation of relatively stable wear resistant layer. Graphene-reinforced Ni3Al matrix self-lubricating composites show poor tribological performance at 16 N for the plastic deformation, resulting in the destruction of the wear resistant layer and the generation of surface cracks and material spalling. From the mechanical mechanism of wear, the plastic deformation and thermal stress are the important factors to lead to the material spalling. The results could be used to guide the selection of suitable working conditions for having good tribological performance of low wear and long service life.

A study of the friction layer of TiAl-10 wt.% Ag composite and the prediction model of friction and wear behaviors:

It was significant to study the longevity of mechanical component by analyzing the effect of friction layer on the predicting models of wear rates and friction coefficients. In this study, based on the changes in applied load F and testing temperature T, the friction and wear behaviors of TiAl-10 wt.% Ag were carried out sliding against Si3N4 ball (6 mm in diameter). At 0–80 min, the prediction models of friction coefficients and wear rates were constructed by the method of bivariate rational interpolation. The predicting accuracies of Pcomp-f: 94–98.7% (friction coefficient) and Pcomp-w: 87.7–98.5% (wear rate) indicated that the constructed prediction model was able to evaluate the friction coefficients and wear rates of TiAl-10 wt.% Ag. The high predicting accuracies were mainly attributed to the excellent plastic fluidity of silver, the smooth morphology of wear scar, and the friction layer of low grain strain.