Study On Laser Cladding Process And Properties Of Wear-resistant Layer Of Ball Valve Sealing Surface

During the use of the ball valve,the sealing surface is prone to wear and lose its sealing performance.In order to ensure the sealing of the ball valve and increase the service life,the surface modification methods such as overlay welding and spraying are commonly used in the industry,but there are shortcomings such as low coating adhesion and large thermal deformation of parts.Laser cladding,as an advanced material surface modification methods,has the advantages of high energy density,low thermal impact,low dilution rate,good binding of the cladding layer,and ease of automated production,etc.,It has been widely used in the fields of high-performance surface preparation and failed part repair.At present,laser cladding technology is rarely applied to the preparation of wear-resistant layers on the sealing surface of ball valves.It is still in the trial and promotion stage,and the relevant application results are rare.In this paper,the goal is to prepar e a cladding layer with wear resistance of the ball valve sealing surface.The following research work has been carried out i n terms of platform construction,process realization,and performance assurance:(1)For the needs of laser cladding and numerically controlled machining of spherical parts,a set of laser cladding processing platform was developed.Semiconductor lasers as heat sources,a rotary-disk feeder for coaxial feed,and a five-axis,four-linkage mechanism as a follow-up cladding actuator.The laser cladding processing platform adopts computer and PLC as the core numerical control system,which digital control of heat source,powder feeding,and feed.Ensures the process requirements for laser cladding of flat and spherical parts.(2)Explored the realization process of the laser cladding process of sphere parts.According to the space spiral trajectory when the sph ere parts are covered,developed algorithms and procedures including parameters provision,part positioning and feed amount calculation,program control for the laser cladding processing is achieved.Using width,height,and hardness as evaluation indexes for the formation and hardness of cladding layers,the influence of laser power,cladding speed and powder feed rate on the formation and hardness of the cladding layer was explored to determine the best process.The parameters provide a theoretical basis.(3)The effect of adding ceramic particles on the microstructure and properties of the cladding layer was studied.Three different types of WC ceramic particles were added to the Ni60 powder,and the microstructure of the cladding layer was investigated,and the microhardness,wear resistance,corrosion resistance,and bonding properties were measured.Studies have shown that the added fl ake-like WC is evenly distributed in the cladding layer,inhibiting the growth of dendrite,produced Cr_x C_y-type hard phase with block and floccular.Compared with spherical WC and shaped WC,the cladding layer of flake-like WC has better wear resistance,corrosion resistance and bonding.Ball valve life test shows that laser cladding fl ake-like WC can effectively improve the service life of the ball valve.