Microstructure And Properties Of Si₃N₄/Zn Al Matrix Composites Prepared By SPS

Because of its good mechanical properties,wear resistance and low cost,zinc aluminum alloy is widely used in bearing,sleeve,bearing bush and other wear resistant seals.Modern aviation,high-speed rail,aircraft carrier and auto mobile and other kinds of machinery manufacturing tools and mechanical trans mission devices for manufacturing materials increasingly demanding,zinc alumi num alloy in the hardness,mechanical strength and wear resistance and other aspects still need to be improved.Silicon nitride is a hexagonal crystal structur e compound with high strength,good stability,high hardness and other excelle nt properties.It can be used as the reinforcement of metal composite materials to prepare composites with more excellent comprehensive properties.In this paper,the main work with zinc alloy as substrate,the silicon nitri de as a strengthening body,the discharge plasma sintering process,the preparat ion of the zinc alloy material and silicon nitride/zinc aluminum matrix compos ites,the different sintering parameters affect the performance of zinc aluminum alloy material,determine the best preparation parameters,then the content of silicon nitride on silicon nitride/zinc aluminum matrix composites.The results are as follows:（1）The results of sintering process parameters of zinc-aluminum alloy sho w that different process parameters have obvious effects on the properties of z inc-aluminum alloy.The density and hardness show a trend of increasing first and then decreasing,while the friction coefficient and wear rate first decrease and then increase.by comparing the results,the preparation parameters of Si₃N₄/Zn-Al matrix composites prepared by SPS were determined as follows:sint ering temperature was 450℃,holding time was 9min,and heating rate was 100℃/min.At this point,the hardness of Zn-Al alloy is 102.44HV,the friction c oefficient is 0.4021,and the wear rate is 4.52×10^-3 mm³/N·m.（2）SEM and XRD were used to study the microstructure of the composit es.The results show that the Si₃N₄ is uniformly distributed in the matrix whe n the Si₃N₄ content is 20%（mass fraction）,and the Si₃N₄ part is agglomerated when the Si₃N₄ content is 25%.No new phase was found after sintering,and the density of the composite increased with the increase of Si₃N₄ addition am ount.（3）The influence of different content on Si₃N₄/Zn-Al matrix composites was studied.Through analysis,it was shown that when the mass fraction of Si₃N₄ was 20%,the composite had the best performance,Vickers hardness reac hed 162.56HV and tensile strength was 353MPa.Compared with Zn-Al alloy,t he hardness and tensile strength increased by 58.5%and 21%.The friction coe fficient is 0.2103,and the wear rate is 3.53×10^-3 mm³/N·m.The corrosion rat e of Si₃N₄/Zn-Al alloy material is significantly lower than that of Zn-Al allo y material,which is 0.114g.m^-2h^-1.