Papers by Author: Yun Jing Song

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Authors: Yun Jing Song, Hua Ling Deng, Shi Rong Xiao, Wen Hua Shi
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.
Authors: Hua Ling Deng, Guang Long Li, Yun Jing Song, Shi Rong Xiao
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.
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