Analysis of application of rare earth in electroplating

Rare earth elements include atomic number from 57 to 71 15 lanthanide: lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium and erbium, thulium, ytterbium and lutetium and similar with lanthanides in the chemical properties of scandium and yttrium, a total of 17 elements. Rare earth elements unique 4f layer electronic structure and chemical properties of the rare earth metal and rare earth alloy has unique features: high catalytic activity, high magnetic, superconducting, photoelectric conversion, magnetic memory, storage with high hydrogen content, corrosion and abrasion resistance, so that the rare earth elements and their compounds are applied in the field of materials science more widely, become indispensable to modern science and technology of functional materials, is in the field of materials science is a hot research topic by researchers all over the world a great deal of attention.

The early development of chromium plating rare earth additive is mainly cerium, lanthanum and other single rare earth simple salt, in recent years, the research of rare earth chromium plating additive has made a big step, developed a variety of rare earth compound additives. In particular, the research and application of rare earth in the electrodeposition process is becoming more and more deeply. After adding a small amount of rare earth compounds in electroplating solution, it can improve the dispersion ability and deep plating ability, improve the current efficiency, increase the hardness and corrosion resistance of the coating [2]. Not only the performance has been greatly improved, and has been transferred from the test to a large batch of industrial production, forming a series of products. Through years of production practice shows that this is a low temperature, low cost, low cost, low pollution, high quality, high stability, high efficiency, significant economic benefits of the new technology. The research results show that the addition of rare earth elements in chromium plating technology has the following functions: [3]: improve the performance of the coating, improve the process conditions, improve the performance of the plating solution, improve the economic efficiency.

The application of rare earth in zinc and zinc based alloys is more successful. The micro amount of rare earth added to the plating solution can make the coating grain small, uniform and compact, so as to improve the corrosion resistance of the zinc coating. In Zn Ni alloy electroplating, add small amounts (less than 1.0 g / L) cerium sulfate can improve the plating liquid of current efficiency, so that the coating of nickel content increased, cerium and to increase the value of the cathodic polarization of zinc nickel alloy containing cerium coating has excellent corrosion resistance [4] in the high temperature and high pressure brine. In the application of nickel plating on aluminum alloy substrate, the effect of rare earth elements on the bonding strength between the substrate and the coating was measured by thermal shock method [5].

Nickel with a small amount of 40% (mass) in the sulfate system. Cobalt alloy coating, the deposition process is "abnormal Co deposition". Addition of a small amount of rare earth compounds in the base plating solution, the cathodic polarization of the alloy electrodeposition process is reduced because of the characteristic adsorption of the rare earth compound on the cathode surface. In KOH solution, the alloy as the cathode, in the high current density of hydrogen evolution overpotential, and Fe electrodes than Ni Co electrode reduces the overpotential of about 200 mV, and Ni, CO (RE) electrode reduce about 250Mv, visible on the hydrogen evolution reaction has higher catalytic activity [6].

Study on the application of rare earth in nickel iron alloy electroplating, [7] effect of rare earth element on sulfate type Ni Fe alloy plating bath. Adding Sm2O3 and (PrNd) O3 in the bath, the obtained results show that the addition of rare earth oxides can broaden the range of current density of Ni-Fe alloy. The results of this experiment on a variety of rare earth oxides are generally the same. It can be found that the addition of rare earth compounds can increase the cathodic current efficiency and the dispersion ability of the plating solution, but the different rare earth elements are not the same. The addition of rare earth compounds play a role in stabilizing the plating solution. Cathodic polarization curves and scanning electron microscope analysis, it is found that the addition of rare earth compounds in the plating solution in increases the cathodic polarization of electrodeposition of Ni Fe alloy, and the crystallization of Ni Fe alloy coating of fine, smooth, bright, so it can improve the coating protective and decorative properties.

The silver lanthanum oxide composites developed by the Department of Applied Chemistry, Tianjin University, Guo Hetong, have the advantages of high hardness, low contact resistance, high resistance to corrosion, high chemical stability, and high chemical stability. [8].

The mechanical properties of rare earth elements on the influence of diamond tools, wear tool performance and cutting performance, and the implications of the main factors for these properties, the effects of rare earth elements on copper matrix hardness has slowly rising trend, the wear weight loss with lanthanum content increase and increase and decrease the wear resistance of the matrix. 1) of La and CE is similar to the effect, but a slight difference in the amount of La, CE, both can strengthen the matrix and improve of diamond and matrix binding force. 2) Ce, La to reduce the wear resistance of the bond, the wear resistance of the tool is not. For tools, the bond strength of bond and diamond appears to be more important. 3) La, Ce rare earth elements can improve the tool's cutting speed, improve the tool on the cutting edge of diamond, and ultimately to improve the cutting performance of the tool. All of these are based on the premise of the bond of the appropriate wear, otherwise, other performance will not happen [9].

The rare earth in the hard alloy application experience of transplanted into the matrix materials of diamond tools in the hot pressing sintering diamond tool matrix. At the same time, Co medium matrix materials of diamond tools in all Fe based instead of. The success of rare earth Fe bond diamond tools and materials, the actual performance of the test, the bending strength, hardness and impact toughness were greatly improved, porosity, significantly reduce