Study On Preparation And Wear Properties Of Wear-resistant Coatings Containing Diamond For Agricultural Machinery

In the field of agricultural machinery,some soil-touching working parts,such as plough,rotary tiller,rake blade,harvester blade,etc.,have severe abrasive wear,corrosion and adhesion due to their direct contact with hard and corrosive substances such as sand,soil,water and salt,resulting in shorter service life.Aiming at the problems of poor working environment and severe abrasive wear of agricultural machinery,the preparation of diamondcontaining wear-resistant coatings was proposed.Wear-resistant coatings containing diamonds of different particle size,concentration and plating state were prepared on Q235 steel by brazing and self-propagating methods respectively.The friction and abrasive wear properties of the coatings were compared with those of 65 Mn steel.Scanning electron microscopy(SEM)and X-ray diffraction(XRD)were used to characterize the surface of the coatings,the interface between the coatings and the steel matrix,the micro-morphology and phase structure of the coatings after wear.The wear law and mechanism of the wear-resistant diamond-containing coatings were analyzed.On the basis of the above research,the wear resistance of 65 Mn steel,brazed diamond coatings,self-propagating coatings were compared and studied.The main results are as follows:(1)The brazed diamond coating has good bonding with the steel matrix,and the diamond is evenly distributed in the coating.The thickness of the coating is between 350 and 380 microns.The wear resistance of brazed diamond coating is better than that of 65 Mn steel,and with the decrease of diamond particle size,the friction coefficient of brazed diamond coating decreases,and the wear resistance of brazed tungsten-plated diamond coating increases.The wear resistance and abrasive wear resistance of brazed tungsten-plated diamond coating are higher than those of brazed Non-brazed diamond coating.(2)The main phases of self-propagating diamond coatings are NiAl,Ni3 Al and TiC.The self-propagating hot-pressing diamond coating has good bonding with steel matrix,and the diamond distributes evenly in the coating,the thickness of the coating is between 800 and 1500 microns.With the increase of diamond concentration,the porosity of the coating increases.With the increase of diamond concentration,the friction coefficient and friction and wear resistance of the self-propagating diamond coating increase,and the friction and wear resistance is better than that of 65 Mn steel.Within a certain range,the hardness and abrasive wear resistance of self-propagating coatings increase with the increase of diamond concentration.When the critical value is exceeded,the hardness and abrasive wear resistance of self-propagating coatings decrease greatly.(3)The most worn parts of the rotary tiller are the front and back parts of the rotary tiller,the back parts near the side and the cutting edge parts.The wear resistance of brazed diamond coating and self-propagating coating without diamond is better than that of 65 Mn steel,and the best wear resistance is self-propagating diamond coating.(4)The essence of abrasive wear resistance of diamond wear-resistant coatings is that the diamond with high hardness and wear resistance in the coatings bears the action of abrasive particles in the process of abrasive wear,thus protecting the coatings to a certain extent.