Preparation And Performance Of Electroless Ni-Fe-P Alloys

In this paper the influence of solution composition on deposition rate, platingcomposition, the coating surface morphology, and cathodic polarization curves ofplating solution are studied, while electroless plating Ni-Fe-P alloy. After this theoptimum process was determined. The plating obtained under the best process erosionresistance in suspension liquid the mass fraction of NaCl is3.5%containing siliconcarbide particles, mass fraction of NaOH is5%containing silicon carbide particlesand the volume fraction suspension of HCl is5%containing silicon carbide werestudied. The characterization of the plating was represented through SEM, EDS andXRD. The best process conditions is:NiSO4·6H2O20g/L,FeSO4.7H2O12g/L,NaH2PO2.H2O30g/L,(NH4)2·SO420g/L,C3H6O320mL/L,the pH value is9.0,theplating temperature is80℃.The corrosion resistance of the coatings in3.5%NaClsolution is more excellent than Ni-P coating obtained under the same process condition.Plating solution composition has great influence on the plating solution cathodicpolarization curve, with the increasing of FeSO4.7H2O the deposition potential reduced,with the increasing of concentration of C6H5Na3O7.H2O the deposition potential negativeshifted, with the increasing of pH value of deposition potential negative shifted. X-raydiffraction analysis indicates that, the form of the electroless plating Ni-Fe-P alloy onthe state is amorphous and nickel microcrystalline. The coating have crystalprecipitation after400℃heat treatment, and with the increase of heat treatmenttemperature the crystallinity of crystal become higher. The tafel curves of samplesafter different heat treatment temperature shows that the heat treatment temperature is200℃and300℃, with the increase of heat treatment temperature coating corrosionresistance in3.5%solution increase, and is superior to the corrosion resistance of theuntreated plating. We continue to increase the temperature of the heat treatment,coating corrosion resistance drops rapidly. When the heat treatment temperature wasincreased to400℃, the corrosion resistance of the plating is markedly lower than theuntrated plating. When the heat treatment temperature come to600℃, although coatingcorrosion resistance of the sample increased compared with400℃heat treatmentsample, but corrosion resistance also lowe than untrated plating. With the increasion ofheat treatment temperature the coating hardness increase slowly, the coating hardnessincrease to the largest of all when the heat treatment temperature come to400℃.Afterthis with the temperature continue to rise, the hardness of coating decrease. Erosion experiment found that coating erosion in suspension liquid the mass fraction of NaCl is3.5%containing silicon carbide particles, mass fraction of NaOH is5%containingsilicon carbide particles have good erosion resistance, in the suspension liquid volumefraction suspension of HCl is5%containing silicon carbide have poor erosionresistance. Coating erosion in suspension liquid the mass fraction of NaCl is3.5%containing silicon carbide particles, mass fraction of NaOH is5%containing siliconcarbide particles almost identical to the same erosion law. Under different velocity andimpact Angle, the coating mass loss is the largest of all, while the grain size is120mesh, when the grain size is240mesh quality loss is the leastest of all. The HCl hasstronger corrosion effect on the samples, so the erosion laws of the samples erosion thesuspension liquid volume fraction suspension of HCl is5%containing silicon carbidebecome more complex.