Papers by Author: Hua Ling Deng

Abstract: Using electrochemical impedance spectroscopy (EIS), polarization curve and X-ray diffraction technique, electrochemical behavior of the transmission tower material Q460 galvanized layer was studied in simulated acid rain solution. The results show that: galvanized layers take place local corrosion in simulated acid rain solution, the corrosion products will fill the hole, and cover on galvanized layer surface, the generated white corrosion products mainly ZnSO₄ ·H₂O.The current generate in the process of corrosion, galvanized layer surface take place electrochemical corrosion. Galvanized layer solution at pH 2.4 and 3.8 of the simulated acid rain in the corrosion process is controlled by the charge transfer process, with the decrease of solution pH value, the corrosion rate increases. Zinc are more sensitive to H⁺ in the solution, in low pH value of solution, due to the strong hydrogen precipitation process, the zinc surface adsorption of hydrogen bubble around, its dissolution rate is higher than the surface of the other part of the zinc, namely in low pH value of acid rain solution, H⁺ by depolarization process not only directly accelerate the corrosion of zinc, can through the strong hydrogen evolution process at the same time accelerate the dissolution of zinc.

Abstract: The coatings for elevated temperature erosion resistance in circulating fluidized bed (CFB) boilers were fabricated by high velocity arc spraying process and CrB powder wire. The microstructure and phase component of the coating were examined by optical microscopy(OM) and Transmission electron microscopy (TEM). The properties including microhardness, adhesion strength and in-situ erosion rate of the coating were measured. The failure mechanism was also discussed based on the experimental data. The OM results showed that the coating consisted of individual flat lamella, thin oxide layer, porosity and very small amount of particle which characterized as different shape and color respectively. TEM results indicated that the phases within the lamella were mainly composed of α phase, amorphous phase and other nanosized particle phase of Fe23(C,B)6, Cr23C6 etc.. The amount of amorphous phase near the substrate was more than that in the other area indicating that the appearance of amorphous phase was related to the high cooling rate of the coating. The microhardness was about 860~1100HV0.2. The coating exhibited high erosion-corrosion resistance, which was about six times as 20G steel. The advantage of the coating with excellent performance, simple process and low cost made it possible to find potential application in power plants.

Abstract: The CrB Particles Reinforced MMC Coating was prepared by using high velocity arc spraying (HVAS) method. Through a series of experiments, including metallographic, SEM and EPMA investigation, the microstructure and composition of the coating were analyzed in details. Additionally, the abrasion resistance mechanism of the coating was studied through field test and observation on the abrasion surface of the coating under the SEM. The results show that the microstructure of the coating is characterized by typical compact laminated structure composed of successive metal matrix and hard particles mainly of borides of chromium and oxides of chromium. The abrasion resistance mechanism of the coating lies in two aspects. One is that the hard particles scatter evenly and dispersedly in the coating, which can reinforce the coating and play a barrier role to hinder the movement of the abrasion particles. The other is that the metal matrix with well ductility and toughness make a buffer action to the impact caused by the abrasion particles, thereby the waste rate of the coating can be greatly slowed down. The results also show that the hardness, shape and quantity of the reinforced particles have magnificent influence on the abrasion resistance of the coating made in this paper.

Abstract: An unequal interval grey forecast model GM (1, 1) was proposed based on the grey system theory and the measurement data of the rate of high temperature abrasion of water-wall tubes in circulating fluidized bed (CFB) boilers. According to the former part of measurement data, the latter part of high temperature abrasion rate of water-wall tubes was forecasted by using the GM (1, 1) model. Through comparing the computation values with the measurement values, the accuracy and the feasibility of the model were verified. The result shows that under small statistics conditions, the unequal interval grey forecast model can offer precisely prediction results, which can provide scientific basis and guidance for the condition-based maintenance of the water-wall tubes in CFB boilers.