| In metal finishing industry,nickel plating has been applied for decorative and functional surface treatments.But the nickel plating layer in the air is easy to corrode,so the development of chrome free,non-toxic and environmentally friendly anti discoloration agent in nickel electroplating industry caused great concern.On the basis of understanding the preparation process of electroless nickel plating,electroless nickel plating was selected and the effect of fatty acids on the anti-tarnishing of nickel coating was studied.As a new type of two-dimensional materials,Graphene has its unique physical and chemical properties and has been paid much attention in recent years.The combination of the graphene and fatty acid compound as anti-tarnishing agents for electroless nickel was conducted and its antitarnish effect was studied.This study may be broad the application of graphene should reference range and extend of electroless nickel plating on the service life of the.The research work of this paper mainly includes the following aspects.?1?By using different chain length of fatty acid?lauric acid,myristic acid,palmitic acid and stearic acid?,the electroless nickel plating layer was treated for anti-tarnishing under different pH conditions.The effect of treatments was analyzed by polarization curve and AC impedance.The results showed that the length of the carbon chain and the pH value were all affected the anti-tarnishing effect.In pH 8-9,The myristic acid group have the best treatment effect.The corrosion rate is 3.77×10-4mm/year.compared to the untreated electroless nickel layer(its corrosion rate is 2.35×10-1mm/year),the corrosion rate is significantly slowed down.The ability to prevent discoloration is.?2?The method of preparing graphene was studied in laboratory scale.Two-step oxidation method was used for preparation of graphene oxide,and the mixed alkali reduction method was for the preparation of graphene.The different temperature?150?,180?,220?,300??and different mixed alkali?NaOH:KOH=3:7,NaOH:KOH=7:3,NaOH:KOH=1:1?ratio were investigated for the reduction effect.The study found that mixed alkali can effectively realize graphene oxide reduction,the higher the temperature,the deoxidation effect of graphene oxide stronger.At 220?,the mixed base ratio of 1:1 was prepared by the preparation of graphene soluble in water.The infrared spectra test revealed that,the resulting graphene surface has a certain number of hydroxyl groups,which may have a good dispersion in the water.?3?The effect of the combination of graphite and alkyl acid on the anti tarnishing of electroless nickel plating layer was studied.The preliminary results show that the presence of graphene has a tendency to reduce the effect of the alkyl acid.Experimental results show that addition of graphene anti-tarnishing solution in the experimental group anti discoloration effect best at pH 8-9.Electroless nickel plating on corrosion rate of basic at about6×10-2mmˇyear.Compared to untreated electroless nickel layer(corrosion rate in the2.35×10-1mm/year),can see anti tarnishing capability is enhanced.But compared with saturated fatty acid treatment reduced the antitarnish treatment effect,the presence of the graphene surface and the nickel plating cell reaction takes place on the surface layer,accelerated the corrosion of the surface.How to make proper use of the graphene electroless nickel plating layer to improve the anti tarnishing capability needs further study. |
PDF Full Text Request