Preparation And Properties Of Diamond Coated High Carbon Steel Wire

Wire saw cutting technology has been widely used in the field of processes for hard-brittle materials,such as crystalline silicon,sapphire,precision ceramics and so on.Free diamond wire saw has gradually become obsolete,and been replaced by the fixed diamond wire saw,because of its low cutting efficiency,big kerf loss,short service life and serious pollution.With the advantages of high consolidation strength,long service life and high cutting efficiency,electroplated diamond wire saw is widely used in the cutting process of hard brittle materials.However,Electroplated diamond wire saw has long preparation cycle,high production cost and low efficiency of electroplating that greatly limits the its application expansion.In this paper,the composite electroplating technology of fixed diamond wire saw was studied according to the requirements of cutting hard brittle materials process and peculiarity of composite electroplating process.The brass plated high carbon steel wire with size of 115 μm in diameter was used as the basis wire.Diamond particles with Ni-P alloy coating and size of 15～20 μm was chosen as the second hard phase for the coating of wire.The anode was soluble nickel plate(purity of 99.9%).Designed pre-treatments were conducted on all materials.The Watts nickel plating liquid was used as the basic plating solution which composes of 280 g/L NiSO4·6 H2O,30 g/L NiCl2·6 H2O,35 g/L H3BO3,0.1 g/L lauryl sodium sulfate and 1 g/L 1,4-butynediol.Various electroplating additives were added according to the requirements of various electroplating processes.Based on the results of serious experiments conducted the factors which affect the microhardness of the wire coating were determined by using the technique of orthogonal test.The determined order was:concentration of CoS04,temperature of plating solution,pH value of plating solution,current density.The optimized process parameters obtained in this paper were:3 A/dm2 of current density,50℃ of plating temperature,4.5 of pH value and 30 g/L of CoS04 concentration.In addition,the electroplating efficiency under the condition of this paper was 85.8%,and the pre-plating time was determined to be 4 min.The experimental results showed that the leveling agent PPS can effectively restrain the agglomeration of diamond particles with Ni-P alloy coating in the process of composite electroplating.But,if the concentration of PPS was too high,it would hinder the co-deposition process of diamond particles and coating metal.When the concentration of PPS was150 mg/L,diamond particles evenly distributed on the surface of composite coating.Results of experiments showed that both CTAB and PVP have the effect of dispersing diamond particles in the plating solution,but PVP produced a molecular film on the surface of diamond,which affected the binding force between diamond and coating.In comparison with PVP,CTAB was more effective on improving the efficiency of composite electroplating.The synergistic effect of 100 mg/L CTAB and 150 mg/L PVP in the plating solution made the diamond composite plating more efficient and the diamond particles distribute more evenly on the coating.The internal stress of the coating can be eliminated by adding the BSI into the plating solution.Under the condition of this paper,the coating had no internal stress plated in the solution with 0.7 g/L BSI added.The addition of the BSI also has the effect on refining the microstructure as well as smoothing the surface of the coating.Under condition of this paper,the reasonable parameters of electroplating diamond wire saw are as follows:4 A/dm2 of current density,5 min of electroplating time,35～40 r/min of mechanical stirring rates,and using double anodic arrangement.The thickening plating used the same plating solution with pre-plating,with plating density of 3 A/dm2 and plating time of 17 min.The electroplated diamond wire saw manufactured in this work had no defects on the coating.The diamonds were evenly distributed and the deviation of the wire diameter was small.The results of property tests of the prepared wire saw showed that it would meet the basic requirements of application for cutting hard-brittle materials.