Damping Capacities Of Negative Thermal Expansion Inclusions/Al-Si Composites

Al-Si composites have good specific strength,wear resistance and excellent processing performance.Therefore,they are widely used in the processing and manufacturing of friction and braking parts in automobiles,machinery and other industries.These components have high requirements for structural stability and vibration attenuation,and the preparation of composites with high damping has become an urgent problem to be solved.In this paper,using the hot-press sintering process,the Al-Si composites was successfully prepared by adding introducing Y₂W₃O₁₂,Sc₂(WO₄)₃ and Pb Ti O₃negative thermal expansion inclusions.These inclusions have a wide negative thermal expansion temperature range,and prepared composites have low thermal expansion effect,high thermal stability and high damping capacitiesStudies have shown that the optimized hot-press sintering preparation process can make the negative thermal expansion inclusion particles have uniform distribution in composites,and form a large number of clear interface layers.Due to the huge coefficient of thermal expansion(CTE)difference between the inclusions and the matrix,a large number of dislocations are generated in the composites.Thermal expansion analysis results show that the thermal expansion coefficient of the composites conform to the mixing rule of the thermal expansion coefficient,which decrease with the content of inclusions increase and the thermal expansion coefficient of the inclusions decrease.In terms of the damping capacities,the damping capacities of the composite increases with content of inclusions increase and CTE of the inclusions decrease,and they are superior to the damping capacities of the Al-12Si alloy.The introduction of inclusions will also cause the generation of damping peaks in the composites.The thermal strain damping model is established by considering the dissipated energy of thermal strain at the interface between the inclusions and the matrix.The model shows that the contribution of thermal strain to the damping capacities of the composites will increase with the increase of temperature,and it will also increase with the CTE of the inclusions decreasing and the volume content of the inclusions increasing.Changing in the expansion coefficient of inclusions can cause damping peaks in the composite.The model can be used to analyze or predict the interface damping behavior and damping efficiency of composite damping materials.