Effects of heat treatment, quartz additions and particle size on the properties of enamel with low-alloy steel substrate

Abstract

Abstract A vitreous enamel coat is a thin layer of glass, typically a few hundred microns in thickness, which is fused onto a metal substrate. The glass used for vitreous enamelling is referred to as the ‘frit’ and is formulated from a wide range of inorganic raw materials including quartz, borax and titania. This research called for the preparation and development of a mixture of ceramic materials, consisting of various metal oxides, for coating low-alloy steel plates with a carbon percentage of 0.18%. A single coating layer was used with a dipping method. Before dipping, the samples were treated with sand blasting. The effects of heat treatment temperature and time, the percentage of quartz additions and coating powder particle sizes were all studied. It was found that crystalline phases (such as (SiO2), (Na2O-Al2O3-TiO2-SiO2), (Li5AlSi2O8), (TiO2)) were developed in the structure of the coating after heat treatment processing. The results showed significant improvement in all properties of coating hardness, adhesion, thermal stability and chemical resistance by increase in the heat-treating temperature and time; the best results were obtained in the properties of the coating with the treatment temperature at 650 ° C, a time of 120 minutes and 15% quartz addition. The results also showed a clear effect of the particle size of powder coating on the properties of hardness and adhesion. When the particle size decreased, the mechanical properties (hardness, adhesion) and thermal stability improved. The results indicated that the increase in coating particles’ size led to an increase in the coating thickness.