Executive Summary : | Objective: To develop ultra-low expansion glass-ceramic product with linear thermal expansion coefficient: ~ (2 – 3) x 10-7 /K (0 - 600oC) based on Li2O-Al2O3-SiO2 ternary system for application as cooktop panel for LPG gas oven at lower cost.Waste material such as blast furnace slag as one of the raw materials will be used to prepare parent glassIn addition, the parent glass will be prepared at relatively lower temperature (1400oC - 1450oC Moreover, a value added property such as hydrophobic surface coating will be made on the top surface of the glass-ceramic material In addition, an attempt will be made to make the cooktop panel transparent Summary: Glass–ceramics are the ceramic material formed through the controlled nucleation and crystallization of the parent (parent) glass. It is worthy to note that lithia–alumina–silica ternary phase diagram provides important information regarding the crystal phase/phases formation that is/are useful for the development of low temperature glass–ceramic materials. This is one of the glass–ceramic systems which have been extensively investigated and the products developed from the system have been commercialized because of its ultra-low, zero or negative thermal expansion coefficients as well as excellent thermal, mechanical and chemical durability. Various types of glass–ceramic materials can be produced from conventional raw materials and there is a growing interest to produce glass–ceramic material from the industrial waste due to their great technological advantage, low cost and scientific importance with proper correction of the chemical composition. Ultra low and negative expansion glass–ceramic materials can be made from alumina-silicate minerals and blast furnace slag which are the low cost materials that can be suitable for various applications including the proposed application as cooktop plate of LPG gas oven. In this proposed work, the batch composition will be modified with the addition of lithium based raw materials, hydrated alumina, boric acid along with a suitable nucleating agent (titania/zirconia) and parent glass will be made by melt quenching technique using ceramic crucible like alumina crucible. On the other hand, an optimization of the batch composition of parent glass towards obtaining the desired volume fractions of glass and ceramics parts will be made through suitable nucleation and crystallization processes. This will enhance the formation of desired crystal phases such as ß-eucryptite (anisotropic crystals) and a/ß spodumene dispersed uniformly in the glass matrix. Microstructural, crystallinity/crystal phases, thermal expansion coefficient, thermal shock resistance, optical properties etc. will be characterized systematically. The properties will be co-related with the thermal expansion coefficient of the glass-ceramic materials. The final size of the plate will be ~600 mm (L) x ~ 300 mm (W) x ~15 mm (T) with the thermal expansion coefficient of ~ (2 – 3) x 10-7 /K (0 - 600oC) for application in cooktop plate of LPG gas oven. |
