Development of ceramic plasma sprayed coatings against slag attack for the steel industry

Refractory linings and components in the steel industry are subjected to very uneven wear rates depending on whether steel or the much more aggressive slag is the corrosive medium. To improve the service life it would be desirable to protect the slag contacting zones by ceramics of the highest possible quality. To this end research was carried out to develop plasma sprayed ceramic coatings of high slagging resistance using conventional refractory bricks as substrates. The parameters investigated were composition of coatings and substrate preheating and spraying conditions. The testing program comprised bond strength, thermal shock and abrasive wear behaviour of the coatings as well as wetting and resistance to slagging using a commercial blast furnace slag. As a result several coatings were found with superior resistance to slag attack. It was ascertained that porosity rather than composition played the leading role in controlling the wear resistance of the coatings.