| Besides the excellence in wearing and corrosion resistance, Ni-P electroless plating deposits have good properties in conductivity, magnetism, solederability, and thermal stability, etc., so that they are widely applied in the electronic industries, magnetic recording material, the ultra large scale integration (ULSI) technology of integrated circuits (ICs) and microelectro- mechanical systems (MEMS) etc. With the development of nano-technology, electroless deposition has revealed its peculiar advantage in manufacturing of nano-materials, for example, in the production of carbon nanotube catalyzer and nano-rod or nano-thread with "template method".The operation temperature in electroless nickel plating is usually high. The lower temperature will not only enhance the stability of plating solution, save energy source and reduce production cost, but also decrease the volatilization of solution and relieve environment pollution. The most promising choice is the use of appropriate ligands or additives to design the procedures of electroless plating at medium or low temperature. A number of additives have been used and they evidently influence the deposition rate and deposits performance. However, the mechanisms of their actions are not thoroughly investigated. At the same time, since the activation procedure has been related to the occurrence of electroless plating, deposition rate and quality of deposits, that to explore the mechanism of activation and to develop new activation methods would become the key for innovation of electroless plating.In this work, the electrochemical and modem physical techniques, such as scanning electron microscopy (SEM), energy disperse spectroscopy (EDS), X-ray diffraction (XRD) etc, were used to detect the effect of additives on the electroless deposition rate, composition, surface morphology and structure of deposits, respectively. And the action mechanism of additives was further analyzed with Raman and Infrared reflectance spectroscopy. At the same time, the initial stages of electroless plating on metal substrates, the electroless plating without Pd activation on carbon nanotubes and ceramics surface, direct electroless deposition on single crystal silicon were investigated. Moreover, the corrosion resistance of electroless deposit of Ni-P with high P content and its relation to the deposit's microstructure were studied. Main results are summarized as below:1 Influences of Additives on Deposition Rate and Morphology of DepositsThe function of solution composition and additives in the electroless Ni-P and Ni-W-P plating solutions was explored. It was found that in the Ni-P plating solution without additives, deposition rate rises with Ni2+ NaH2PO2 concentration and pH value increased. The higher Ni2+ concentration and pH are favorable to Ni deposition , and the higher NaH2PO2 concentration benefits to P deposition. In the solution containing of additives, theresults show that thiourea (TU) helps Ni2+ for reduction but retards NaH2PO2 oxidation, that propionic acid accelerates both Ni2+ reduction and NaH2PO2 oxidation, and that La2O3 is favorable to NaH2PO2 oxidation.There are obvious differences on the morphology of deposits from the solutions with and without TU. The surface panicles are fine and a great deal of gaps exist in the deposits obtained from the solution without TU, contrarily, the particles are large and fewer gaps exist in the deposits from the solution with TU, which is attributed to the inhibition of TU to metal nucleation and hydrogen ion reduction. In the deposits of Ni-W-P, many big grains are composed from the little ones, and these little ones contain more fine particles. Lads can refine the grains by reducing W content in the deposits.In the electroless Ni-W-P and Ni-P systems, the effects of LaCI3, lactic acid, Fe2(SO4)3, propionic acid, thiourea, La2O3 and 2,2'-dipyridine on deposition rates were systematically investigated. The results show that the deposition rates influenced by these additives present in a consistent regularity, that is, t...
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