Study On Preparation And Properties Of Diamond Coating Agricultural Machinery Soil-Engaging Components

Agricultural machinery soil-engaging components,as plowshare,digging share,rotary blade,rake blade,which directly contact with hard and corrosive substances such as sand,stone,acid and alkali soil,would be seriously damaged by abrasive wear and erosion wear,resulting in a short service life and low efficiency of agricultural machinery.In order to improve the wear and corrosion resistance of soil contact parts for agricultural machinery,a study on preparation of surface coating containing diamond gritswas put forward in this thesis.Firstly,the surface coatings containing diamond grits were prepared on 65Mn steel substrate by brazing,self-propagating high-temperature synthesis（SHS）and laser cladding respectively;the surface and interfacial microstructure of diamond coating were observed by scanning electron microscopy（SEM）,andthe phase structure was analyzed by X-ray diffraction（XRD）;the corrosion resistance of the diamond coating was also compared with65Mn Steel.Secondly,the abrasive wear resistance of diamond coatings was compared with that of 65Mn steel.The wear rule and mechanism of diamond coating and other abrasive particles（silica,alumina and silicon carbide）was discussed.Last but not least,t the diamond coatings was welded on flat iron（to simulate a spade）and rotary blade respectively,and the soil abrasive wear tests were carried out in a self-made soil tank comparing to 65Mn steel.The main conclusions were obtained as following:（1）The surface coatings containing diamond grits（brazing coating,,self propagating coating,and laser cladding coating）and 65Mn steel substrate combined well;the diamond grits are distributed evenly in the coating（about 1200-1900?m）;the main phases in the brazing coating are Cr₇C₃ and Cr₃C₂,the main phases in the self propagating coating are NiAl,Ni₃Al and TiC,and the main phases in the laser cladding coating are Cr₂₃C₆,Cr₃C₂and Mn₂B;the acid alkali corrosion resistance of coatings is better than that of the 65Mn steel,but a little amount of diamond grits fell off after corrosion.（2）The abrasive wear resistance of coatings containing diamond girts is better than the65Mn steel owing to the extremely hardness of diamond grits,which share a part of abrasive force in the abrasive wear process.Additional,the wear resistance of coatings was decreased with the increasing of hardness of the pair wear particles,owing to the relatively greater a plastic deformation.（3）The abrasive wear resistance of coatings containing diamond girts is superior to the65Mn steel,and the self-propagating coating is the best.The hard abrasive particles in the soil produce a three-body abrasive wear of flat iron and rotary blade.the diamond grits in the coatings share partly abrasive force,protect the steel substrate and increase the wear resistance.