Preparation, Microstructure And Property Of Electroless Ni-B Alloy Deposits

Based on an overview on the development history and current researches of electroless plating, a detailed discussion is made regarding the research and development of electroless plating Ni-B alloy. Based on the experiment result, the basic processing parameter of electroless plating Ni-B alloy was determined and five kinds of electroless plating Ni-B layer was obtained after the mount of reducing agent KBH4 was adjusted.The microstructure and performance of five kinds of electroless Ni-B deposit are systematicly researched in this theme. The effect of heat treatment on the microstructure and performance of the electroless Ni-B deposit is also studied in this paper.It is necessary to analyse the deposit with TEM, because the analyzing result of XRD is not accurate. It is suggested in this paper that the structure of electroless deposit would experience the transform of nanometer state→mischcrystal state→noncrystal state by using XRD and TEM. With the increasing of the temperature of heat treatment, the crystallization degree of the deposit continuously increased, but Ni2B and Ni3B first appeared and then disappeared, this phenomenon was not found in related papers. When the heating temperature reached 350℃, the sorts of Ni2B and Ni3B were the most.The morphology of deposit was analysed with SEM. It was founded that the structure of the deposit would transform from miscrystal to noncrystal state with the increasing of temperature. The distribution of elements in the deposit was also analysed.with line by line scanning.Measuring and analyzing the microscopic Vickers hardness of the electroless, it indicates that the contents of KBH4 affects the electroless deposit's hardness. When the contents of KBH4 is 0.9g/L, the highest hardness is 720HV0.2. If the contents of the KBH4 in the plating bath increases, the hardness of the electroless doposit decreases, at the same time, the color of the electroless became gloomy and lost its color of metal. The results of Vickers hardness is corresponding to the results of XRD analysis. The electroless deposit's hardness reaches the highest value(1135HV0.2) at 350℃.Each kind of electroless's phase transition temperature was measured with DSC, They became crystallized at 300℃.If heated below 300℃, there will be a diffusion peak in most sample's DSC curve.It was possibly affected by the precipitation of the Ni3B.The electroless is. paramagnetism or diamagnetism, but its affecting laws are not clear.Heat treatment can not only increase the adhesive attraction between electroless and basal body but also increase the toughness of the electroless.