EXPERIMENTAL OPTIMISATION OF A N?CKEL OXIDE BASED PRE-TREATMENT TO ANALYSEGAS BUBBLE DISTRIBUTION AND FISHSCALE RESISTANCE IN ENAMELLED STEEL
S. Ali1, A. Hardwick1 and X. Yang1
1Permastore Ltd, Eye, Suffolk, IP23 7HS
1Institute for Materials Research, Holdsworth Building, University of Leeds. LS2 9JT
Vitreous enamelling is a process in which glass is fused onto the surface of steel at high temperatures to produce a composite material. The effects of processing conditions when applying a phosphate pre-treatment slip, rich in nickel oxide (NiO), to the surface of a hot-rolled steel substrate have been investigated. Interfacial reactions between the glass and the steel after fusion have been examined using scanning electron microscopy. Additional techniques including energy dispersive X-ray analysis and electron probe microanalysis were employed to evaluate oxide diffusion profiles. Decarburisation of the steel surface and changes in the viscosity of the interfacial glass contribute to the formation and distribution of gas bubbles in the enamel layer. Modifying the processing conditions of the pre-treatment application significantly alters the reaction kinetics at the glass-steel interface. This results in changes to the mechanisms that reduce and prevent fishscale, which have been quantified in this investigation.