Jiewen Huang

Dry Sliding Tribological Behavior at Elevated Temperature of In SituAluminum Matrix Composites Fabricated by Al-ZrO2-C System withDifferent Mole Ratio of C/ZrO2

The tribological behavior of the composites fabricated by an Al-ZrO2-C system with different mole ratios of C/ZrO2 at elevated temperature in air atmosphere were investigated by using a pin-on-disc wear tester. The reinforcement amounts and kinds of the composites varied with molar ratio of C/ZrO2. With the increase of the molar ratio of C/ ZrO2 from 0 to 1, the Al3Zr blocks decrease gradually and almost disappear finally. On the contrary, the ZrC particles form and increases in its amount. At elevated temperature, the composites have similar variation trend in the mass loss varied with sliding velocity and applied load, respectively. When the test temperature is at 373 K, the mass loss increases with increasing the sliding velocity, and when the sliding velocity is around 0.6 m/s, the mass loss increases to a maximum value and then decreases with further increase in sliding velocity. However, the mass loss always decreases with increasing the sliding velocity at 473 K. With the increase of C/ZrO2 molar ratio, the wear resistance of the composite increases and its friction coefficient decreases. The metal flows and adhesive wear become the main wear modes with increasing the applied load and test temperature.

Microwave combustion synthesis of in situ Al{sub 2}O{sub 3} and Al{sub 3}Zr reinforced aluminum matrix composites

Al{sub 2}O{sub 3} and Al{sub 3}Zr reinforced aluminum matrix composites were fabricated from Al and ZrO{sub 2} powders by SiC assisted microwave combustion synthesis. The microstructure and reaction pathways were analyzed by using differential scanning calorimetry (DSC), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy dispersive spectroscopy (EDS). The results showed that the heating rate during microwave synthesis was very high and the entire process took several minutes and that the ignition temperature of the reaction was much lower than that of conventional methods. In addition, the resulting microstructure was found to be finer than that prepared by the conventional methods and no cracks can be seen in the Al{sub 3}Zr reinforcements. As such, the newly developed composites have potential for safety-critical applications where catastrophic failure is not tolerated.