| With China's growing demand for power and complex electromechanical equipment,and the reliability and safety of electrical and mechanical equipment required is high,failure analysis and prediction is of great significance to improve the economic efficiency of enterprises and the management level of electromechanical equipment development.The main steam pipe is a key component of the power plant,running for a long time in high temperature and high pressure under the worst conditions,prone to material aging and damage accumulation,sudden accidents also occur frequently,to the enterprise staff's life safety and property of the country poses a serious threat,so the main steam pipeline failure analysis and prevention is urgent and important.In this paper,the author combined with the engineering example,the main steam pipeline failure mode,effects of the life of the main factors and prevention methods are analyzed systematically,which provides theoretical basis and analysis method for the life management of main steam pipeline of power,in order to prevent and reduce accidents and reduce the loss of purpose.As one of the nano composite plating surface protection technology,due to its advantages of simple equipment,convenient operation,fast speed,low temperature,low price,easy to control,not only can improve the metal surface corrosion resistance,wear resistance,oxidation resistance and other properties,and can save material,reduce manufacturing cost,so it has been widely used in aviation and electronics,machinery,chemical industry,metallurgy and nuclear power etc..The content of metal elements in the alloy coating is an important factor to determine the properties of Ni-Fe alloy coating.How to improve the content of nano particles in the composite coatings has become a hot spot in the research of composite electroplating.In this paper,Ni-Fe alloy coating was prepared on the surface of 20#? steel by the method of direct current electrodeposition and pulse electrodeposition:Study on the parameters of iron sulfate concentration,current density,stirring speed,pH value and temperature effect on the iron content of the coating,the optimum process parameters were chosen: in electroplating solution concentration of ferric sulfate 20 g/L;current density of 1.5 A/dm2;the stirring speed of 300 rpm;pH3.5;the temperature of 40 DEG C.To characterize the surface morphology,coating microstructure and element distribution,and discusses the coating corrosion and hightemperature oxidation resistance mechanism,the results show that the pulse electrodeposition of Ni-Fe alloy coatings prepared by the strong corrosion resistance in DC electrodeposition method,in the same corrosion medium,the corrosion potential of Ni-Fe alloy coating the increase,while the corrosion current decreases.The deposited iron atoms reduce the porosity of the coating,increase the compactness of the coating,effectively reduce the diffusion of the corrosion products into the interior,and improve the corrosion resistance of the coating.Prepared by pulsed electrodeposition of Ni-Fe alloy coating is 700 ? and 1.5 h after high temperature oxidation,the oxidation resistance than the pure nickel coating is about two times higher than that under the same conditions with DC composite coating prepared by electrodeposition method to improve the half.The products of pure nickel coating and Ni-Fe alloy coating after high temperature oxidation are mainly NiO and Fe2O3.After high temperature oxidation,the formation of pure nickel coating particles is obviously coarsening,and the deposition of nickel iron atoms inhibit the growth of nickel grains,the coating is also more smooth.With a pulse of Ni-Fe alloy coatings prepared by electrodeposition,due to high iron content,reduce the actual contact area of the nickel matrix oxidation,reduce the stress of coating and hinder the generation and proliferation of cracks,thus improving the oxidation resistance of coating. |
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