Indian Journal of Science and Technology

Abstract

Objectives: To study the effect of Zn powder content (0-40 wt%) on low firing metallic composite glaze on earthenware fabricated at 1100°C under oxidizing and partially reducing firing atmosphere. Methods/Statistical Analysis: The raw glaze was characterized by TGA-DSC. The fired glaze was characterized by XRD (X-Ray Diffraction) and SEM (Scanning Electron Microscopy). The chemical resistance and water contact angle of fired glaze were also investigated. Findings: The glaze made with 10% Zn powder has green color and some dark green stripes of CuO and Fe2 O3 in oxidizing firing atmosphere. Contrary, the glaze has shiny violet-green aspect of the mixture of the deep blue color of FeO and CuO, and some Zn metallic luster after firing in a reducing atmosphere. The glazes appear has rough surfaces with the greenish brown color. when more Zn powder is added (20-40 wt%) by firing in an oxidizing atmosphere, light brown and opaque appearance is observed after firing in partially reducing conditions. This was attributed to the formation of Fe3 O4 . The shiny crystals of Zn2 SiO4 and a small amount of metallic Zn are formed in the fired glaze prepared in reducing atmosphere. The fired glaze surface can be corroded by both acidic and basic solutions. Finally, the fabricated fired glaze surface is easyto-clean with water contact angle of ≈56°. Application/Improvements: These results could be applied to the local clay earthenware for luster decoration providing an added value to the products.

Keywords: Low Firing, Oxidizing Atmosphere, Partially Reducing Atmosphere, Tapoh Clay, Zn Metallic Composite Glazes.