Research on Anti-corrosion and Wear-resistance Coating Used on Wet-process Desulfurization in Coal-fired Chimney
|School||Hefei University of Technology|
|Keywords||Desulfurisation Composite Coating Anti-corrosion Wear erosionresistance and heat resistance|
The chemical and physical performances of the generation station flue gas haschanged a lot after wet desulfurisation. Flue gas changes, in the other word from the dryflue gas to low temperature, high humidity corrosive wet flue gas. Requirements are putforward to the steel flue liner material to improve the abilities of anti-corrosion,wearerosion resistance and heat resistance.To solve the problems above, we developed a neworganic composite coating which is room temperature curing, high temperature resistant,corrosion resistance, resistance to wear erosion, the coating consists of three layers:(1)the first layer, epoxy resin has been choosed as main film former of prime coat choosefor its convenient curing, resistance to chemical corrosion, solvent resistance and otherexcellent properties;(2) high temperature resistance, corrosion resistance performanceof vinyl phenolic epoxy resin is choosed as main film forming material of surfacecoating in order to adapt to the demands of defeating with the corrosive flue gas, byadding reinforced materials such as short aramid fiber, organic silicon to improve theperformance of surface coating;(3) a layer of carbon fiber is added between coating andsurface coating as an intermediary to enhance cohesive force between the prime coatingand surface coating, and further enhance the anti-corrosion ability of coatings;(4) glasspowder, talcum powder and other silicates are added as filler, the fillers not onlyincrease the heat performance of coating but also improve the mechanical properties ofthe coating. Experiments on various influence factors of the composite paintcoat arecarried out to analysis the formulation mechanism and optimized design program of thecomposite paintcoat, by testing the thermal shock resistance of composite coating,corrosion resistance, tensile strength between bottom coating and the matrix steel and soon, the results follows:(1) When the surface roughness Ra of steel substrate is within the scope of0.8~1microns, the tensile bond strength of the bottom coating of epoxy and the steel substratewill up to6Mpa which is much higher than the national standard2.5Mpa; The higherthe tensile strength of epoxy resin and matrix steel, the more difficult from the substratesurface spalling, foaming(2) When the percentage of short aramid fiber is4%, the quality loss of the coatingin the angle of30°of erosive wear is the minimum, the cover coating is not broken andthe base steel is not revealed after the erosive wear test; At the same time, the content oforganic silicon resin impact the quality of erosive wear. (3) In terms of acid corrosion, after soaking in sulfric acid solution of20%,30%,40%for53days, the compact structure of the surface coating samples are not damaged,no blistering, or desquamating phenomena, through the SEM analysis, there is nointernal corrosion either; Epoxy coating samples are soaked in20%,30%and40%sulfric acid solution for10days, surface pitting, acid erosion to the internal coating,corrosion of steel substrates have happened to the prime coating. Once again, it provesthat vinyl phenolic epoxy resin has better anti-corrosion ability compared with epoxyresin..(4) When the mass fraction of organic silicon is between4%and7%, through theTG curve we can see that the thermal decomposition rate is smaller; Organic siliconmass fraction is7%, we get the best bending strength.