Study On Surface Modification And Application Of Synthetic Diamond Micro-powder For Wire Saw

Electroplated diamond wire saws are widely used in the cutting and processing industry of hard and brittle materials.The diamond micro-powder used needs to be plated with a metal layer on its surface first.The commonly used plating methods are electroless nickel plating and nickel plating.In this paper,the influence of composite complexing agent on the deposition rate of electroless nickel plating coatings and the stability of the electroless plating solution of diamond micro-powder at low temperature was studied,and selects the best composite complexing agent.With this composite complexing agent,the single factor experiment method was used to study the influence of the p H value and temperature of the electroless plating solution on the deposition rate of electroless nickel plating coatings and the P content of the coating at low temperature of diamond micro-powder,and the effect of the P content of the coating on the acid corrosion resistance and impact toughness of the coating was further studied;In the process of nickel plating on diamond micro-powder,the influence of the rotation speed of the plating bottle on the motion state of the diamond micro-powder and the influence of the plating current on the weight gain rate,morphology and density of the coating were studied,and the best process conditions were obtained;The diamond wire saw composite electroplating device was designed and built by myself,and the diamond wire saw pre-plating and composite electroplating process were specifically studied.The main results of this paper are as follows:1.By studying on the influencing factors on the quality of low temperature electroless nickel plating of diamond micro-powder with particle size of 4～8μm,it can be obtained:(1)With 20 g/L citric acid added with 5 g/L succinic acid as the best composite complexing agent.The deposition rate of electroless nickel plating coating is faster,the stability of electroless plating solution is good,and the coating is complete.(2)When the bath temperature is 35℃and the p H value is 3～13,as the p H value increases,the deposition rate of electroless nickel plating coatings gradually increases,and the P content of the coating gradually decreases.When the bath p H is 5 and the temperature is 30～50℃,the deposition rate of electroless nickel plating coatings and the P content of the coating increase with the increase of temperature.(3)With the increase of P content of the coating,the acid corrosion resistance of the coating gradually increases,and the impact toughness gradually decreases.2.The optimum process conditions of nickel plating on diamond micro-powder with particle size of 20～30μm are as follows:Nickel plating of diamond micro-powder is carried out by using the method of low rotating speed and low current,and gradually increasing the rotating speed of the electroplating bottle.When the rotation speed of the plating bottle is1～7 r/min and the plating current is 1.5～2.5 A,the quality of nickel plating on diamond micro-powder is better.The rotation speed of the plating bottle and the influence of the plating current on the quality of nickel plating on diamond micro-powder are as follows:(1)The rotation speed of the plating bottle is gradually increased from small to large within the range of 1～7 r/min,and the plating current does not exceed 3 A,which can realize nickel plating on diamond micro-powder.(2)When the plating current is 0.5 A,the coating is weightless and stripping occurs.When the plating current is 1 A,a small part of the coating is leaked.When the plating current is 1.5 A,the coating is complete.(3)When the plating current is 1～2.5 A,as the plating current increases,the weight gain rate of the coating gradually increases,and the coating density gradually decreases.3.Through the experimental research on the diamond wire saw composite electroplating device,pre-plating and composite electroplating process,it can be obtained:(1)When the concentration of nickel sulfamate is 450 g/L and the pre-plating current density is 3～9 A/dm~2,the coating is flat and smooth.(2)The best composite electroplating process for the cathode rotary type composite electroplating device using electroless nickel plating diamond micro-powder is:the diamond micro-powder loading capacity is 17 g/L,the current density is 4 A/dm~2,the composite electroplating time is 15 s,and the composite electroplating temperature is 45℃;(3)The best composite electroplating process for the sand-sweeping tube type composite electroplating device using electroless nickel plating diamond micro-powder is:the composite electroplating temperature is 45℃,the current density is 3 A/dm~2,the composite electroplating time is 15 s,and the diamond micro-powder loading is 15 g/L.Under the same conditions,the composite electroplating time of nickel plating diamond micro-powder is 12 s,and the composite electroplating rate is faster,but it is more prone to agglomeration.