Effects Of Cu-Sn Double Coating And Si On Microstructure And Wear Resistance Of Cf/Al Composites

Cf/Al composites have broad application prospects in automotive bearings and engine pistons due to their high specific strength,specific stiffness and lightweight properties.However,the manufacturing difficulty of composites are increased because the poor wettability and the interfacial reaction at high temperature of the carbon fiber and aluminum matrix.The research shows that metal coatings and alloying elements was used to improve wettability and inhibit interfacial reaction between the carbon fiber and aluminum matrix.However,the copper coating is easy to be oxidized in daily preservation and preparation of composite,which deteriorates the quality of copper coating.The Al₂Cu brittle phase was formed between copper coating and aluminum matrix at high temperature,the properties of composites were deteriorated.In addition,the Si element is enriched around carbon fiber,which affect the microstructure and properties of Cf/Al.In this paper,the Cu-Sn double coating was prepared on carbon fiber surface by electroless.The microstructure and properties of Cf were respectively improved from the perspectives of adding high-quality coatings and alloying elements.The effects of Cu-Sn double coating and Si elements on the microstructure and wear resistance of Cf/Al composites were prepared by vacuum pressure infiltration method,which were analyzed by scanning electron microscopy（SEM）energy dispersive spectrometer（EDS）,electronic universal testing machine and rotating reciprocating test machine.The results show that:（1）The fall off between Cu coating and carbon fiber was significantly improved with the increase of electroless plating time.The electroless plating time was 20min-25min and the thickness of Cu-Sn double coating was 1.31μm-1.55μm,the adhesion between Cu-Sn double coating and carbon fiber was the best.（2）The microstructure and properties of Cf/Al-12Si composites was analyzed without and Cu-Sn double coating on carbon fiber surface.The carbon fibers were uniformly dispersed in the matrix,and the interfacial reaction was inhibited between the carbon fibers and aluminum matrix.The friction coefficients of the two composites were respectively close to1.386 and 1.415.（3）The microstructure and properties were compared of Cf/Al composites with four Si contents（0wt.%,7wt.%,12wt.%,20wt.%）.The interfacial and mechanical properties of Cf/Al composites were improved with Si content.The yield strength is 53 MPa of the Cf/Al composites,the furrow and spalling pits on the wear surface are deeper.The highest yield strength is 146 MPa and good wear surface morphology of Cf/Al-12Si composite.（4）The friction coefficient were 1.752,1.491,1.415,1.548 of Cf/Al composites with four Si content（0wt.%,7wt.%,12wt.%,20wt.%）.The friction coefficient was the largest of Cf/Al composites and smallest of Cf/Al-12Si composite.The wear surface roughness was 35.605,17.844,14.690 and 28.301.The wear mechanism of Cf/Al and Cf/Al-7Si composites is adhesive wear,and the wear mechanism of Cf/Al-12Si and Cf/Al-20Si composites is abrasive wear.