Preparation Of Multilayer Ni Plated Diamond Grits And Study On Manufacturing Technology Of Wire Saw

The world today is facing a series of energy and environmental problems.The development of the photovoltaic industry can not only solve these problems,but also help my country successfully complete the"carbon peak and carbon neutrality".The diamond wire saw is used for slicing crystalline silicon in the photovoltaic industry.The abrasive prepared by the wire saw is mainly Ni-plated diamond powder.The traditional Ni-plating process:diamond→sensitization→activation→reduction→electroless plating→electroplating Ni,pretreatment of electroless plating The steps are cumbersome,especially the Sn Cl₂ sensitizing solution and the Pd Cl₂ activating solution have high cost and are not environmentally friendly.In this paper,the traditional Ni plating method is improved.The new Ni plating process adopts vacuum micro-evaporation plating to replace the pretreatment process of electroless plating in traditional Ni plating,and then prepares multi-layer Ni diamond plating through electroless plating and barrel plating.This process eliminates a large number of solution operations and rinsing processes in pretreatment,shortens the steps and time for preparing Ni-plated diamond,improves production efficiency,avoids the use of precious metal Pd,and is economical and environmentally friendly.In this paper,the phase,composition and morphology of all diamonds in the preparation process were analyzed.The surface coating of vacuum-plated Ti diamond was Ti C with a thickness of 244 nm.The newly added coating of electroless Ni diamond is Ni-P alloy,the thickness of the new coating is 167 nm,and the total thickness is 411 nm.The newly added coating of the multi-layer Ni-plated diamond is Ni,and the thickness of the new coating is 543 nm,and the total thickness is 954 nm.The electrochemical workstation was used to test different diamond sanding processes:after the multi-layer Ni diamond was added,the cathode open circuit potential shifted greatly,reaching 0.1 V,and the cathodic polarization and charge transfer resistance were both the smallest,indicating that the multi-layer plating Ni diamonds are easier to migrate to the cathode and adhere to the cathode interface,and have the strongest sanding ability.Different diamonds were tested on the wire saw sand.The multi-layer Ni-plated diamond wire saw has the highest abrasive density,reaching 68 pieces/mm,and has the strongest sanding ability,which proves the accuracy of the electrochemical evaluation.The electrochemical test is easier to choose.Sanded diamond provides an effective means.Subsequently,using multi-layer Ni-plated diamond as composite electroplating abrasive and copper-plated steel wire with a diameter of 110μm as busbar,electroplated diamond wire was prepared by suspension method on a self-made electroplating equipment and its optimal process parameters were explored.The electroplating layer of sulfamate nickel plating solution is intact after bending test,and it is suitable for the plating solution prepared by wire saw.The pre-plating current density is 3 A/dm²,the pre-plating layer has fine grains,no obvious pores,peeling and other defects,and the surface roughness is the smallest.The optimal process parameters for sanding are the current density of 3 A/dm₂,the sanding time of 150 s,the abrasive mass concentration of 6 g/L,and the Co SO₄concentration of 30 g/L.The number and diameter of the wire saw abrasive particles are moderate and uniform.There is no agglomeration.The addition of Co SO₄ not only improves the sanding efficiency,but also improves the hardness and corrosion resistance of the coating.When the thickening current density is 3 A/dm² and the time is 20 min,the prepared coating has good hardness and corrosion resistance.