The Preparation Of Low Firing Enamel Coating On Carbon Steel And Its Performance

Steels coated with vitreous enamels have good corrosion resistance to acid and alkali while still retains its excellent physical and mechanical properties.However,problems like high sintering temperature,complex process and strict steel selection exist during the preparation of enamel coating.Therefore,developing simple enamel preparation process which fires at low temperature on common carbon steel has strong practical significance.This thesis studied a kind of low firing enamel coating on common carbon steel.By adjusting the ratio of flux and refractory compounds and refining the particle size of frits,the firing temperature has been reduced effectively.The interface between enamel coating and plain steel substrate was characterized by SEM and EDS.The change of the micro-morphology was observed by adding different adherence promoters.The adherence property was measured by drop-ball test method.The hardness of enamel coating was measured by micro-hardness tester.The influence on enamel coating after adding appropriate amount of Al2O3 was studied and the phases change in the enamel coating was analyzed by XRD.The resistance of enamel coating to thermal shock and corrosion resistance were determined according to the relevant standards.The optimum parameters of the enamel preparation are as follows:firing time 8min,firing temperature 780 C and the thickness of enamel between 0.35-0.45mm.The result of SEM show that adding adherence promoters NiO and CoO contribute to form excellent adherence strength between enamel coating and plain steel substrate.The result of dropping ball test show that adherence strength increased with the increase of firing time and firing temperature under the appropriate sintering conditions.The result of XRD shows that new phase Al2TiO5 is formed after adding adjunct agent Al2O3.The result of corrosion resistance tests shows adding Al2O3 improves the citric acid resistance.The hardness of enamel coating increases and the resistance to thermal shock also improves from 390? to 435 ?with the Al2O3 addition.