Effects Of Elements Silicon And T6 Treatment On Friction And Wear Properties Of High Aluminum Zinc Based Alloy

The low-cost high aluminum zinc based alloys have been systematically investigated by microstructure observing and properties test as the researching objects,to study the influence of Si alloying. And the influence of T6 treatment also has been tested for improving the properties of the high aluminum zinc based alloys more. In the experiment, universal test machine, hardness tester, M-2000 friction and wear testing machine, Optical Microscope(OM), Scanning Electron Microscope(SEM),and Energy Dispersive X-ray Detector(EDS) were used to observe the microstructures, worn surfaces and subsurface, and to test mechanical and wear properties. The influence mechanism of Si alloying and heat treatment on microstructure and properties of ZA alloys has been researched. Main conclusions are shown below:With 0.55% Si alloying, the microstructure of ZA27 and ZA38 alloys are refined most effectively. Dendrites in the microstructure of ZA27 alloy turns into chunky grains. The grain size of dendrites in ZA38 alloy decreases greatly, and considerable remelt of dendrites arms appeared in the microstructure. At the same time the comprehensive mechanical properties achieves the best. With solution and aging treatment, granular η phase are uniformly distributed in aluminum based solid solution. A remarkable increase of elongation and the tensile strength and hardness slightly improved by T6 heat-treatment.0.55%Si alloying enhanced the wear property of ZA27 and ZA38 alloy effectively under the 600 N load and 3 hours’ wear time. The wear mass losses of ZA27 and ZA38 alloys were reduced to only 97.3mg and 75.6mg in the wear test.Under the condition of 600 N load and 3 hours’ wear time, adhesive wear is the main wear mechanism of as-cast ZA27 alloy, and large amount of plastic deformation arises on the worn surface. With 0.55 Si alloying, abrasive wear is the main wear mechanism. For as-cast ZA38 alloy, abrasive wear and adhesive wear mixing mechanism is the main wear mechanism. The wear mechanism of ZA38 alloy with0.55Si% alloying is abrasive wear.With solution treatment, Wear properties of ZA27-0.55 Si and ZA38-0.55 Si alloys decreases actually compared with as-cast alloys with 0.55%Si alloying. With T6 heat treatment, wear mass loss are lower than wear resistances of the alloys are further increased than the as-cast alloys with 0.55%Si alloying. Fretting abrasive wear is the main wear mechanism of ZA27 and ZA38 alloy with T6 heat treatment.In same work conditions, wear resistance of ZA38 alloy is obviously better than ZA27 alloy under 600 N load, and slightly better than ZA27 alloy under 800 N load.