Ceramics

The essential property of talc feedstock for ceramic products is its ability to provide solid and extremely durable ‘crock’, as specialists call it. Talc-based ceramics are distinguished by low water absorption capacity and shrinkage, high chemical resistance, very low thermal expansion, thermal conductivity and electrical conductivity – the latter is especially important for, particularly, manufacturing saggers, cordierite plates, insulators, and many other products.

Talc is highly temperature-resistant and, therefore, it improves thermal resistance of ceramics and allows reducing cracks.

Talc is chemically inert. It has an extremely low reactivity to acids, thus making ceramics acid-resistant.

Talc has been used in the production of ceramics for a long time. Finely dispersed talc is used in the production of various types of ceramics such as:

• household ceramics: dishes, ceramic tiles, roof tiles, sanitary ware, etc.
• technical ceramics: catalysts, electroporcelain, insulators, etc.

In manufacturing household ceramics, up to 60% of fine talc powder is added to the slip composition, which enables:

• firing products at lower temperatures than usual – t < 1150 С to obtain products with reduced porosity and increased strength characteristics;
• to hold the shape of the finished products after firing and glazing better.

In manufacturing technical ceramics, the talc content in the slip composition sometimes reaches 80%, replacing pegmatites, feldspars and expensive clays.

The most common technical ceramics using talc include:

• Steatite ceramics: manufacture of electric insulators. Talc is mixed with 10% of finely-grinded barium carbonate and 10% of finely-grinded kaolin. Such slip composition allows delivering robust thin-walled products with minimum firing shrinkage at low temperatures.
• Cordierite ceramics: manufacture of car plugs, catalysts, etc. For this purpose, the slip formulation contains up to 45-50% of talc plus 40% of kaolin clay and 10-15% of aluminum oxide. The composition is fired at t=1340 С, which also allows delivering products with an improved strength performance in bending and a lower weight.
• Chlorite ceramics: refractory manufacture. The name says it all – for this purpose, low-quality talc/chlorite feedstock with 50% to 60% content by weight is used. However, with fine grinding, the final products are also thin-walled boasting with very high bending resistance figures.

Adding talc allows:

• firing products at lower temperatures;
• delivering products with lower porosity and improved strength performance;
• having finished products hold their form better after firing and glazing.

Reduced firing cycles and processing temperatures in ceramics manufacturing due to adding talc have a positive impact on the product cost.