Study On The Structure And Soft Magnetic Properties Of Electroless Deposition Cobalt-base Alloy Film With Rare Earth Joined

The structure and soft magnetic properties of the electroless deposition cobalt-base alloy film with rare earth joined were studied. The basic formulation and optimum formulation of process of electroless deposition Co-Ni-B-RE alloys were designed and tested using perpenpular method. The samples were prepared. The structure and micromorphology were observed. The electrochemical characterristic, mechanical and magnetic properties were measured. The different kinds of rare earth elements were added to electroless deposition Co-Ni-B alloy coating. The mechanism of action and influence mode on the process, structure and properties of Co-Ni-B alloy coating were discussed in order to obtain the electroless deposition cobalt-base alloy film with excellent over-all soft magnetic properties. The results showed that after the rare earth elements are added to bath, the plating rate is increased obviously. In some range, plating rate increases at firt, then decreases with increase of amount added of RE. Because of RE being added to bath, the stability of bath, bonding force of coating and surface quality are improved. The rare earth elements RE can codeposit with cobalt-base alloy, and with increase of amout added of RE in solution, the content of Co, Ni, Ce in alloy increases and the content of B decreases. The structure of alloys changes into microcrystalline from amorphous. The crystal grains are thin and the structure is homogeneous. The rare earth elements La, Ce, Dy make microhardness of alloy coating improve. In some range, microhardness increases at firt, then decreases with increase of content of RE. The effects of the different rare earths: Dy is the first, then Ce, and La is the least. The rare earth elements improve the magnetic properties of Co-Ni-B(Fe)-RE alloys. The saturated magnetization(Ms), initial permeability(μ₀) and maximum (μ_max) are increased. The coercitive force(Hc) is decreased. Comparing with Co-Fe-B-RE alloys, Ms of Co-Ni-B-RE alloys is lower. However, μ₀, μ_max are higher and Mr, Hc are lower. Over-all properties are more excellent. The modifying action of the rare earth elements with 4f electron and light rare earth elements on the properties of alloy coating are more remarkable comparing with the rare earth elements without 4f electron and heavy rare earth elements. Electroless deposition Co-Ni-B-RE alloys with excellent soft magnetic properties are obtained.