Synergistic impact of additives and ball milling on bismuth-based glass frit for automotive enamel coatings

Abstract

This study investigates the synergistic effects of various additives, including ethyl cellulose and molybdenum disulfide (MoS2), on the particle size reduction of bismuth-based glass frits during ball milling and their subsequent impact on glass enamel properties for automotive applications. The integration of jet milling and dry ball milling processes demonstrated economic feasibility, with MoS2 and ethyl cellulose significantly enhancing milling efficiency by reducing particle sizes and increasing the proportion of fine particles. MoS2's lubricating properties and ethyl cellulose's interaction with frit surfaces were identified as key factors contributing to improved grinding performance. The research further explores the thermal and optical behavior of enamel formulations incorporating carbon black, graphite, graphene, MoS2, and ethyl cellulose. MoS2 exhibited exceptional silver overprint hiding capabilities (Delta L = -0.3), achieving uniform aesthetic properties critical for automotive coatings. While high gloss enamels correlated with minimal crystallization, they exhibited reduced anti-stick properties, whereas low gloss enamels, particularly those with crystallized surfaces, provided enhanced anti-stick performance during press bending. Colorimetric analysis revealed that additives such as carbon black and graphite maintained color stability and gloss at elevated temperatures, while ethyl cellulose influenced surface roughness, delaying heat development during firing. These findings highlight the importance of balancing aesthetic qualities, such as gloss and color uniformity, with functional characteristics like anti-stick performance in enamel formulations. Overall, the study emphasizes the potential of optimizing frit compositions and milling techniques to achieve cost-effective, high-performance glass enamels for automotive applications, offering a balance between visual appeal and operational functionality.