The Study On The Green Common Technology Of QPQ Instead Of Chrome Plating

Hard chromium plating technology is a kind of traditional surface modification technology.On the one side,it dose improve the metal surface hardness,wear resistance,anti-corrosion,high temperature resistance and so on,on the other side,it can be used to repair some damaged parts.But it can produce chromium fog and wasted water with highly toxic hexavelant chromium(Cr VI),which is harmful for environment and seriously influences human health when chrome anhydride is utilized in the electroplating process.Although trivalent chromium has replaced the Cr VI so far,the trivalent chromium electroplating technology still has many defects,such as the thin hard chromium plating layer,complicated plating solution,poor coating quality and stability,etc.So,the electroplating technology needs to get further researches and development.The QPQ complex salt bath treatment technology is also applied for surface modification,and mainly composed of salt bath nitridation and salt bath oxidization,and the permeated layer can significantly enhance metal surface hardness,wear and corrosion resistance.Importantly,QPQ technology is a kind of non-poisonous,environment protecting and energy saving new complex surface modification technology.QPQ complex salt bath treatment technology is mainly composed by salt bath nitridation and salt bath oxidization,and the permeated layer produced can improve the anti-corrosion and anti-wear of metal surface.And the salt bath permeation solution is nontoxic cyanate,which effectively solves the pollution problems and realizes the zero emissions of nontoxic waste-water.At present,the QPQ technology with high hardness,high wear resistant corrosion,deformation,fatigue resistance,etc,has qualified itself to replace the hard chromium plating technology.So,the systematic experiment contrast about hard chromium plating technology and QPQ salt bath complex treatment technology is the research focus,and mainly studying the formation mechanism of surface modification layer,the discipline of surface wear-resistant and anti-corrosion,and the performance differences.The piston rod materials with quenched and tempered 45 steel and 40Cr,and non-tempered steel are respectively treated by QPQ salt bath treatment technology and hard chromium plating technology in this paper.Besides,the effective hardness layer and wear-resistant of the samples treated by different processes be compared with vickers microhardness tester and friction and wear tester.The law of hardness variation and the wear mechanism get researched.The neutral salt spray test and electrochemical experiment are used to detect the treated samples corrosion resistance,and explore the discipline of corrosion.The metallographic microscope,X-ray diffraction(XRD),scanning electron microscopy(SEM)and energy spectrometer(EDS)are utilized to observe the microstructure of the surface modification organizations,analyze the phase composition of surface layer and element distribution.In addition,discussing the strengthen mechanism of modified layer.The research results show that the surface hardness of hard chromium plating samples is all approximately 810HV0.1,and the surface hardness of QPQ samples is different with the variation of alloy elements.Besides,the complex permeated layer produced on the surface of metal because of the permeated N and O elements,the effective hardening layer depth of QPQ permeation layer is far more than the hard chromium plating layer;The QPQ layer has a layer of oil-storing porous layer and a dense crack-free compound layer,which effectively reduces the surface activity and prevents direct contact between the corrosive medium and the metal substrate,so the corrosion-resistant of QPQ permeating layer is 200%more than hard chromium plating layer;the active N,O elements penetrate into the metal matrix to form Fe3O4 and Fe2-3N,with low coefficient of friction and high hardness,so the wear-resistant is 100%more than that.