| Magnesium borate whisker (MBOw) is expected to widely used in aluminummatrix composites for its low price, high tensile strength, high elastic modulus,corrosion resistance and high temperature resistance. While, the wettability betweenliquid aluminum and MBOw is not good, the interfacial bonding strength is relativelylow. To further enhance the properties of composites, Al2O3coating is formed on thesurface of MBOw by sol-gel methods in this paper. MBOw/Al and MBOw/Al2O3/Alcomposites are fabricated via Hot-Pressing sintering (HPS).The influence of mixing methods, sintering temperature, sintering pressure onthe composite organization and performance are discussed by OM、density tests andhardness tests. The microstructure of Al2O3/MBOw and MBOw/Al2O3/Al compositesare investigated by SEM and XRD. The specific area of MBOw and Al2O3/MBOw aremeasured by specific area apparatus. The effects of coating on the properties ofcomposites are investigated by compressive tests、hardness tests and friction and weartests. The results are listed as follows:1. The best process for HPS is that powders are mixed by the hydro-ball-millingtechnique, the sintering temperature600℃and the sintering pressure50MPa.2. Al2O3coating can be uniformly coated on the surface of MBOw by sol-gelmethod. At the temperature of850℃, Al2O3coating do not react with MBOw. Thespecific area of MBOw are enhanced.3. The Al2O3coating can enhance the combination between whisker and matrix,and effectively increase the properties of composites. The compressive strength,compressive modulus and brinell hardness of MBOw/Al2O3/Al composites are37.5GPa、215MPa and134.3HB, which are enhanced by25.8%、49.3%and85.8%compared with MBOw/Al composites.4. Under the dry sliding conditions, the wear amount of MBOw/Al2O3/Alcomposite is the lowest one among the three materials. |
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