Study On Ni-P Composite Plating Of Heat Exchanger Units And Condensation Test Analysis

The loss of steel caused by corrosion totals 1 ton every 90 seconds. It is estimated that the corrosion loss in 2005 amounts to at least 500 billion RMB, and around 17.50 million tons of standard coal was consumed due to corrosive encrustation. Under this circumstance, it is imperative that effective measures of anti-corrosion and energy saving be taken. Surface treatment by chemical composite plating of low-grade materials has important economic and practical implications for reducing the initial investment in equipment and to prolong the service life in that corrosion resistance of low-grade materials is improved and thus can be used as an alternative to high-grade materials. On the other hand, composite chemical plating increases the surface energy of heat exchanger unit and enables drop-wise condensation of vapor, which may lead to higher efficiency of heat exchange rate. With these two objectives, an in-depth study on Ni-P composite plating of heat exchanger unit, together with condensation test analysis, is elaborated on in this paper.Taking the characteristics of composite chemical plating, alloy deposition mechanism, experiment conditions, technological requirements, and coating performance into consideration, the author obtains the major compositions of solution used for Ni-P composite plating from repeated experiments. More effort has been made to optimize the mol ratio of major compositions to reducing agent. The study on proper selection of various complexing agents, which have a vital impact on the performance of plating solution and service life and coating quality, solves the key problem of chemical plating. Meanwhile, the impact of stabilizing agents and other agents on the performance of plating solution and coating quality is also investigated. Compositions that meet the design requirements are determined on the basis of a great number of experiments.Basic processes of Ni-P composite plating and major procedures that may affect the Ni-P coating surface are investigated. The result indicates that the quality of coating surface is intimately connected to pre- and post-treatment and plating process. Therefore, quality coating surface can only be achieved by implementing Ni-P composite plating properly. Pre-treatment is a very important portion of composite plating. Procedures...