Xiao Mei Liu

Study on the Lubrication and Antifriction Mechanism of Low Frictional Self-Lubricating Wear-Resisting Coating

This paper is about the lubricating wear-resisting coating KF301/WS2 and round pit texturing modified coating KF301/WS2 which are prepared by supersonic plasma spraying, laser remelting and surface texturing technology, tribological characteristics of two kinds of coatings are studied under room temperature, according to this, it is discussed for lubrication antifriction mechanism. The research shows: round pit texture has a certain influence on friction factor of coating’s surface and abrasion loss. Friction coefficient of untextured surface is about 0.0138 in the initial stages, while friction coefficient of round pit texture is about 0.01, compared with the former, the latter decreases 27%; when wear time reaches to 1 hour, abrasion loss of untextured surface is 0.0026mg, while abrasion loss of round pit texture is about 0.013mg, compared with the former, the latter decreases 50%. The lubricant antifriction performance of round pit texture is higher than untextured surface, this is because friction coefficient of coating is decreased as the change of the third-body bed, and round pit micro moulding can collect abrasive particle, decreasing the influence of abrasive particle.

Effects of Interface on Wear Resistance in Fiber Reinforced Composites

The effects of the interface in alumina fiber reinforced Al-Si alloy composites prepared by squeeze casting on the wear resistance of the composites were studied. The results indicated that the fiber combined with the matrix well in the composites and had reinforcing effect on the alloy. The interface in the composites could hold back crack propagation, and the composites had the excellent wear resistance. The alloy elements in the matrix were favourable to forming the good interface to improve wear resistance of the composites.

Fractal Characteristics of Primary Phase Morphology in Semisolid A356 Alloy

Semisolid A356 alloy was prepared by low superheat pouring and slightly electro- magnetic stirring(LSPSES). The fractal dimensions of primary phase morphology in semisolid A356 alloy were researched by the calculating program written to calculate the fractal dimensions of box-counting in the image of primary phase morphology in semisolid A356 alloy. The results indicated that the primary phase morphology in the alloy was characterized by fractal dimension, and the morphology obtained by the different processing parameters had the different fractal dimension. The morphology at the different position of ingot had the different fractal dimensions, which reflected the effect of solidified conditions at different position in the same ingot on the morphology in the alloy. Solidification of the alloy was a course of change in fractal dimension.

Research on Wear Resistance of Mg2Si Reinforced Hypereutectic Al-Si Alloy Composite

Mg2Si particle reinforced hypereutectic Al-Si composite was prepared by casting, and the microstructure and wear resistance of the composite were researched. The results indicated that the morphology of Mg2Si obviously changed with Mg2Si contents increasing, in which the morphology of Mg2Si in the composite had changed from polygon block to characters like and finally became coarse dendrite. There were effects of Mg2Si content and morphology on the wear resistance in the composite, which had the higher hardness and better wear resistance at the suitable Mg2Si content.

Approach to Modified Mechanism of Eutectic Si in Alumina Fiber Reinforced Al-Si Alloy Composites

Alumina/Al-Si alloy composites were manufactured by squeeze casting. The morphology of eutectic Si in the composite was observed on scanning electronic microscope, and the modified mechanism of the eutectic Si in the composite was approached. The alumina fiber in the composite could trigger twin during the growth of Al-Si eutectic and lead to modification of the eutectic Si near the fiber.

Research on Segregation at Interface in Al2O3/Al-Cu Composites

Al2O3/Al-4%Cu alloy composites were manufactured by squeeze casting. Segregation at the interface between fiber and matrix in the composites was researched. The results indicated that at the end of solidification of the composites, the change of the solute in the surplus liquid phase resulted in the type of matrix alloy being changed because of the selecting crystallization, and the segregation at the interface was finally formed. There might be the dual effect of the segregation on structures and property of the composites.

Microstructure Refinement by Y2O3 in Semisolid A356 Alloy

The semisolid A356 alloy slurry, which was grain-refined by Y2O3, was manufactured by low superheat pouring. The effects of grain-refine on the morphology and the grain size of the primary phase in semisolid A356 alloy were researched. The results indicated that semisolid A356 alloy contained Y2O3 with particle-like and rosette-like primary phases could be prepared by low superheat pouring. The grain size and particle morphology of primary phase in semisolid A356 alloy were markedly improved by Y2O3. The refining mechanism of Y2O3 on the morphology and the grain size of the primary α phase in semisolid A356 alloy was delved.

Fractal Characteristics of Microstructure in Semisolid A356 Alloy

The fractal characteristic of microstructure in semisolid A356 alloy was researched by the calculating program written to calculate the fractal dimensions. The results indicated that the morphology of primary grain in semisolid A356 prepared by compound process is characterized by fractal dimension, and the morphology of primary grain at the different position of ingot had the different fractal dimensions, which reflected the effect of solidified conditions at different position in the same ingot on the morphology of semisolid primary grain.

Effects of Electromagnetic Stirring on Morphology Evolution of Primary Phase in Semisolid Alloy

The effects of electromagnetic stirring on the morphology evolution of primary phase in semisolid A356 alloy slurry prepared by low superheat pouring and slightly electromagnetic stirring (LSPSES) were studied. The results indicated that the slurry containing globular-like primary phase was prepared by LSPSES, and the electromagnetic stirring within range of stirring power studied had the obvious effect on the morphology of primary phase in the slurry. The morphology of primary phase with finer size slurry was evoluted to globullar-like with increase of stirring power.

Complex Modification on Microstructure and Properties in Mg2Si Reinforced Hypereutectic Al-Si Composite

The effects of complex modification which mainly consisted of mixed rare earth oxides and CaCO3 on microstructure and properties in Mg2Si reinforced hypereutectic A1-Si composite were researched. The results indicated that the morphology of Mg2Si particle changed from irregular or crosses to polygonal shape, and its size obviously decreased. The hardness and wear resistance of the composite were improved by the complex modification.