The Research On The Mechanics Properties And Friction-wear Properties Of A New Type Of Cu-Mn-Al Alloy

The new Cu-Mn-Al alloy has high strength and excellent anti-friction and wear resistance,which can be used to manufacture important parts,such as sliding bearings,sliders,ball valves and etc.It shows greater potential especially in many cases with heavy load,high-temperature,a little oil or without oil.In this paper,by means of tensile test,thermal simulation,friction and wear test,scanning electron microscope,microhardness tester,etc.,the mechanical properties,the evolution law of stress and strain in hot deformation at high temperature,and the friction and wear properties in different corrosion media about the alloy were studied.Meanwhile,the friction and wear behavior of the Cu-Mn-Al/graphite composites sintered by SPS powder sintering under dry friction and oil film lubrication was investigated,which provides basic data and theoretical guidance for the application of the alloy.The conclusions are as follows:(1)The Cu-Mn-Al alloy is a single-phase solid solution with coarse grain size,which belongs to ordered face centered cubic lattic.its hardness is 317.4 HV_2N.When the temperature is below 350?,the tensile strength of the alloy is higher than 850 MPa but its elongation ratio is low close to zero,showing obvious brittle fracture.When the experimental temperature is higher than 350?,the tensile strength of the alloy begins to decrease signicantly and the plasticity increases,and the alloy changes from brittle fracture to ductile fracture,the transition temperature of the alloy from brittle to ductile is 365.84?.(2)Based on the thermal simulation test data and Arrhenius equation,the constitutive equation of hot compression deformation of the alloy was established.The stress-strain relati-onship of the alloy conforms to power exponent in the range of 500?600?.(3)The dry friction coefficients of Cu-Mn-Al alloy against stainless steel and alumina ceramic ball is less than 0.2,the friction process is very stable,the wear surface of the alloy is smooth,and the wear mechanism is slight grinding and oxidation.In Na Cl,Na OH and H₂SO₄solution,the friction coefficient of Cu-Mn-Al alloy against stainless steel ball is greater than that of dry friction,but the corresponding wear rate is close to that of dry friction,their wear mechanisms are brittle spalling caused by chlorine embrittlement,uniform corrosion wear,and adhesive wear respectively.The friction coefficient of the alloy against alumina ball in three kinds of corrosive media is less than the dry friction coefficient,the wear rate of the alloy in Na OH solution is close to that at dry friction condition,but the wear rate in Na Cl and H₂SO₄ solution decreases significantly.(4)The density and microhardness of Cu-Mn-Al/graphite composite sintered by SPS technology are significantly higher than those of the materials sintered by hydrogen reduction technology.Under the dry sliding friction condition,when the load is below 20N,the Cu-Mn-Al/graphite composite exhibits low friction coefficient and wear rate,its friction and wear properties are much higher than those of Cu-Mn-Al alloy,the friction coefficient of composites with 6wt.%?8wt.%graphite is only 0.07,which can be used to manufacture sliding friction parts under low load,oil-free or poor lubrication conditions.When the load increases to 30N,the friction coefficient and wear rate of the material increase obviously,and the friction process is unstable.Under the condition of oil film lubrication,the friction factor and wear rate of Cu-Mn-Al/graphite composite are higher than that of Cu-Mn-Al alloy at the same lubrication condition,and Cu-Mn-Al alloy has more performance and economic advantages.