Preparation Process And Properties Of Anti-coking Ceramics Coating On Heat-resistant Steel

In ascension pipe of coke oven,the pipe inner surface frequently tends to coke and en up as graphite.The graphitization is critical problem to be solved that seriously hinders the raw coke oven gas transmission and reduces production efficiency.In this article,the preparation of ceramic coating to reduce the number of bonding graphite in its surface,improve the production efficiency.In the research process,SiO₂ and Cr₂O₃ was identified as the major component of ceramic coating by the calculation of thermodynamic theory;frit was designed by following the principle which thermal expansion coefficient matching each other between ceramic coating and metal substrate,and adopting the way of liquid phase sintering in high temperature on the Cr20Ni25 heat-resistant alloy surface preparate ceramic coating.With the research method of the control variable,following the principle of single variable,the paper have discussed four aspects,the coating slurry,sintering temperature and mechanical properties as well as anti-coking properties of ceramic coating,to finish this research work.（1）It had important influence on the coating slurry and firing that Solid particle size,water content in slurry,chemical additive types and quantity.When the coating slurry in addition amount of 90%,milling 20 hours,adding a small amount of chemical additive（CMC,STPP）,the performance of slurry was optimal.（2）As the higher temperature,the ceramic coating sintering shrinkage was greater,the bonding effect was poorer between ceramic coating and metal substrate.When the ceramic coating contained 20% Cr₂O₃ and kept firing temperature 1090℃ for 20 min,the ceramic coating was smooth which firm combined with metal.（3）It was obviously that ceramic coating surface had the anility of inhibiting carbon coking.Compared with the metal surface coking layer,the carbon layer with the loose structure was easy to remove from ceramic coating surface.