A Study On Metal Protection In Flowing Slurry Water System In Yangtze River

The Three Gorge Project is a world-famous project. For many components,the erosion resistance of slurry water at medium or high speed is a dominant factor. To reduce the erosion rate of metals,organic protective coatings are widely used. In this work,Mass loss tests have been carried out on eighteen types of modified epoxy coating materials and six kinds of mild steels in slurry water. A modified rotating disk test rig was used to simulate silt abrasion and erosion with different quart sands at different velocities. The synthesis of six wear-resistant epoxy coatings was performed. The resistances of the various epoxy coatings to silt abrasion had been measured and compared under specified test conditions. On the one hand,the effects of curing agents,fillers,lubricant and coupling agents of the epoxy coatings had been discussed. On the other hand,the effects of quart sand contents,diameter of the quart sands and flow velocity on the erosion resistance of the epoxy coatings had been studied through mass loss test and SEM observation. Among the selected materials,the results are as follows:1. Almost all of the modified epoxy coatings show good wear-resistance at different speeds,which illustrates that it is effective to use modified epoxy coatings to protect steel. Therefore,the lifetime of metal is prolonged.2. Under the erosion conditions of different sand diameters,not all of the coatings have the same order;Under the same erosion conditions,the data of all the coatings are relatively stable. With the increase of erosion particle diameter,the relative wear-resistance of coatings decreases. Moreover,the effect of flow velocity is much greater than that of particle diameter. In addition,with the increase of concentration,the relative wear-resistance of coatings has a slow tendency of decrease.3. With time going,the total erosion masses of coatings increase gradually,but the erosion masses of coatings in one unit of time decrease gradually,and the erosion rate tends to be stable. The erosion rate of epoxy coatings mainly comesfrom resin matrix because the erosion-resistance of resin matrix is much lower than that of the fillers. Furthermore,all of the addictives added have some effects on erosion-resistance of the coatings.4. Pure epoxy coating shows typical brittle erosion behavior,and the erosion is determined by both micro-cutting mechanism and fracture mechanism. Owning to the differences of particle diameters,the erosion mechanism may be different.Author:Zhou Jianlong (Material Science) Directed by:Prof. Xiao Yide...