Enhancement of high temperature structural strength of carbon bonded ceramics by using nano materials

Abstract

Carbon bonded refractories are used for high temperature application in Iron & Steel, Non-ferrous & other industries. The main advantages of carbon are its non-wetting characteristic to liquid metal & slag and high thermal spalling resistance. One of the premier carbon bonded refractories is Sub-entry nozzle (SEN), which is used in the steel plant. It is used for shrouding the flow of steel from tundish to mould during continuous casting of steel. The body part of SEN is made of alumina-carbon and the slag band portion that remains immersed into the pool of mould powder, is made of zirconiacarbon. Zirconia has excellent corrosion resistance to nascent fluorides present in mould powder. This paper mostly focuses on how to enhance the life of SEN by incorporating the oxides in nano-form. This improves its physico-mechanical properties and induces properties like higher mechanical strength and low elasticity. Corrosion & erosion resistance also improves due to its dense texture. The most important thing to note is that due to high surface area of the particles, the sintering process starts at a low temperature with improved mechanical properties, thus lowering the energy consumption and cost of the product. Microscopic studies have been done to study the bonding patterns and co-relation has been made with actual field trials.