Ceramics play a significant role in various industries, including the production of ceramic ware, sanitary ware, tableware, tiles, and more. A crucial element in the formulation of high-quality ceramic glazes and enamels is the use of borates. Borates, such as colemanite, ulexite, and specialty borates, offer numerous benefits, ranging from efficient production processes to enhanced protection against external elements. This article explores the role of borates in ceramics, highlighting their impact on appearance, firing times, viscosity, surface tension, durability, and mechanical strength.

 

Improving Appearance and Performance with Borates:

 

Enhancing Glaze Appearance:

Borates, when incorporated into ceramic glazes and enamels, contribute to the production of high gloss and brilliance. By reducing surface tension, borates facilitate the formation of a flat glaze surface, ensuring a smooth and lustrous finish. This effect is particularly crucial as crystalline phases in glazes can diminish surface flatness and gloss.

 

Chemical and Mechanical Durability:

Borate compounds, when used correctly in ceramic glazes and enamels, significantly enhance chemical durability. They resist chemical and aqueous attacks, ensuring the longevity of the finished product. Additionally, borates improve mechanical strength and scratch resistance, making the ceramics more robust and long-lasting.

 

Optimizing Production Efficiency:

 

Reducing Firing Times:

The inclusion of borates in ceramic glazes and enamels helps reduce firing times, enabling more efficient production processes. By inhibiting glass formation during the initial stages of melting, borates facilitate quicker maturation of the glaze or enamel, resulting in improved production efficiency.

 

Controlling Glass Viscosity and Surface Tension:

Borates play a crucial role in controlling the viscosity of the glass during firing. Lowering glass viscosity allows for smoother flow and even distribution of the glaze or enamel, enhancing its appearance. Moreover, borates reduce surface tension, aiding in the formation of a uniform and flawless surface.

 

Types of Borates Used in Glazes and Enamels:

 

Colemanite, Ulexite, and Specialty Borates:

Common borates used in ceramic glazes and enamels include colemanite, ulexite, borax pentahydrate and decahydrate, boric acid, and anhydrous borax. The choice of borate depends on various factors, such as the specific ceramic product, its processing conditions, the desired glaze composition, and cost considerations.

 

Formulating Glazes with New Boron Raw Materials:

Recent developments in borate materials have introduced new possibilities for glaze formulations. For instance, the introduction of calcined borate material, E4972, containing silica, alumina, boron oxide, calcium oxide, and sodium oxide, allows for glaze compositions without traditional frits. These new glazes have demonstrated good chemical and mechanical properties, as well as appealing aesthetics.

 

Standard Production Processes:

 

Ceramic Glaze Production:

Ceramic glazes are typically composed of frits, coloring or oxide additives, and processing aids. These ingredients are fused into an insoluble frit before being applied to the ceramic substrate. The firing temperature and duration determine the maturity of the glaze, ensuring a smooth and defect-free surface.

 

Ceramic Frits for Glazes:

Ceramic frits are created by melting a mixture of crystalline materials, primarily silica, along with fluxes, opacifiers, and colorants. The specific composition of the frits depends on the desired product and firing temperature.

 

Borates in Ceramic Tiles Production:

Enhancing Strength and Efficiency:

Borates are incorporated into ceramic tiles to improve their strength and reduce energy consumption during production. By adding a small amount of boric acid, a transparent phase with low viscosity can be formed, enhancing the overall performance of the tiles. Borates can significantly increase the dry mechanical strength of the tiles.

 

Adaptation to Firing Processes:

As firing times and temperatures have evolved, the selection of borates for ceramic tiles has also changed. Single firing processes, which save energy and labor costs, require non-sodium borates due to the high sodium oxide content. On the other hand, sodium borates are still used in low viscosity frits for enameling metals.

 

Borates in Tableware Glaze Production:

Versatility in Glaze Formulation:

Tableware glazes, used in stoneware, earthenware, porcelain, or bone china, often contain boron in the form of boric acid. These glazes offer high crystallization ability, excellent mechanical strength, and resistance to acids and alkalis.

 

Firing and Application:

Tableware glazes are typically applied by spraying and undergo single or double firing processes. The firing temperature is carefully controlled to fuse the glaze without causing deformation, ensuring a durable and attractive finish.

 

Porcelain Enamel Production:

Applications and Benefits:

Porcelain enamels find extensive use in enhancing the appearance and corrosion resistance of metal products, including domestic appliances, sanitaryware, and architectural panels. Enamel coatings on cast iron and sheet-steel baths, as well as chemical plants and cooking utensils, provide both functional and aesthetic advantages.

 

Distinctions from Ceramic Frits:

Porcelain enamel frits differ from ceramic frits in their firing temperature and composition. Enamel frits, fired at lower temperatures, incorporate higher amounts of boron to reduce viscosity. Enameled steel, the primary substrate for enamel frits, offers lower viscosity and higher thermal expansion, requiring the use of sodium borates.

 

Borates play a vital role in the production of ceramics, particularly in the formulation of glazes and enamels. By improving appearance, reducing firing times, controlling glass viscosity and surface tension, and enhancing durability, borates contribute to the overall quality and efficiency of ceramic production processes. With ongoing developments in borate materials, new possibilities are emerging for glaze formulations, allowing for greater creativity and improved performance in various ceramic applications.