Research On Preparation And Performance Of WC Reinforced Composite Coatings On The Surface Of Steel

WC reinforced composite coatings were prepared on the surface of45steel by hotpressing sintering. The microstructure and performance of coatings with the differenttire body were researched.Based on the results of analysis, the coatings of WC-EXD602were prepared by high frequency induction cladding device. The effect on the coatingsby process parameters, the content of WC and additives were studied were studied. Themechanism of wear and the deformation of coatings were discussed.The microstructure and composition were investigated by metallographic andscanning electron microscopy with energy spectrometer as well as X-ray diffractometer.The performance of coatings were tested by means of hardness tester, friction and wearmachine and the electrochemical systems etc.The results show that the density of WC-Cu-Ni coating is the best comparing withWC-Cu and WC-Ni. With the increasing of Ni, the number of holes decreasesfirstly,then gradually increase. The porosity of40%Ni coating is the lowest, and theholes of coatings are expanding significantly when above40%Ni. The best hot pressingsintering process for WC-Cu-Sn coating is47%WC,850℃×1min,2MPa. It contributeto the formation of CuSn phase under extending the time of milling and sinteringappropriately. The wear mechanism of coatings is priority to abrasive wear andadhesive wear is secondary. The porosity of WC-EXD602coating is0.84%, and theinterface fix tightly and the property meets requirements. The porosity of coatingsreduces by32%after adding10%La2O3, and the peak of hardness is54.8HRC,increasing by10%. The relative wear resistant coefficient is9.76, the performance ofwear-resisting enhances significantly, with the increase of WC, the corrosion resistantperformance is worse and it is superior to WC-EXDNi105coating. The best process ofhigh frequency induction cladding for WC-EXD602is1.0mm thickness of coatings,1.5mm induction clearance,300A preheated for20s,700Acladded for100s(cooling for3s after20s). It is favorable for the formation of the diffusion zone on the interface of coatings after phosphating for1.5h, it inhibits oxidation foaming of coatings.Comparing with sodium silicate, the turpentine and rosin saturated solution is contributeto improving the microstructure of coatings. With the increasing of WC, the porosity ofincreases after take the lead in reducing. The wear-resisting ability of50%WC coatingis the best. The minimum of void fraction is24.13%under three kinds of particle size,with1:3:1grading of WC particles. The microstructure of coatings are well-distributedand density. while the load is0~400KN/m2, wear rate of coatings begin to decease afterincreasing, WC and tire body wear alternately. The dissolve, burning, bridging andcrack of WC particles are mainly caused by the factors that the surface chemicalreaction of atoms and molecules, elements diffusion, the growing of sintering neck anddynamics.