From insulator to oxide-ion conductor by a synergistic effect from defect chemistry and microstructure: acceptor-doped Bi-excess sodium bismuth titanate Na0.5Bi0.51TiO3.015

Low levels of acceptor-type dopants can introduce appreciable levels of oxide-ion conductivity into NB0.51T due to a synergistic effect from defect chemistry and ceramic microstructure.

Reutilization of the Solid Waste Materials Produced by a Ceramic Tiles Industry as a Raw Material for the Production of New Ceramic Tiles

The increasing demand for tiles to be used in civil construction has resulted in the development of industrial ceramic production in Brazil. However, a bigger production of tile means an increase in raw material consumption, which could increase the amount of industrial waste materials. One of the guidelines within the Brazilian law for solid waste materials (“Política Nacional dos Resíduos Sólidos”) is “Integrated Management”. The objective of this subcategory is to insure that research and application are being done in a way that will offer a solution and a use for the solid waste materials. Through laboratorial experiments regarding the ceramic microstructure, the properties of the ceramic waste materials were determined. These materials show great properties such as high mechanical resistance. New formulas were made that include the addition of waste materials and it was concluded that the maximum quantity of waste materials that can be added to the pre-existing formula is 4%, which will save around R$ 11,833.90 per month for the Porto Ferreira Ceramic Industry. In addition to helping the company financially, this change in the formula will also decrease the number of broken tiles and decrease the environmental damage.

Experimental study on rotary ultrasonic machining of alumina ceramic: Microstructure analysis and multi-response optimization

Excellent and superior properties of alumina ceramic make it a one of the highly demanded advanced ceramics in the present competitive scenario of manufacturing and industrial applications. However, its effective and economic processing is still a challenge. The present article has targeted to experimentally investigate the influence of several process variables, namely spindle speed, feed rate, coolant pressure, and ultrasonic power on different machining performances, i.e. surface roughness, and chipping thickness. Response surface methodology has been employed to design the experiments. Microstructure of the machined samples has been evaluated and analyzed through scanning electron microscope. This analysis has revealed and confirmed the presence of plastic deformation of work surface that caused the material removal along with the dominated brittle fracture in the processing of alumina ceramic with rotary ultrasonic machining. The multi-response optimization of machining responses has been done by using desirability approach. At the optimized parametric setting, the obtained experimental values for surface roughness and chipping thickness are found to be 0.215 µm and 0.159 mm, respectively.

Effects of M2+ (M = Ca, Sr, and Ba) Addition on Crystallization and Microstructure of SiO2-MgO-Al2O3-B2O3-K2O-F Glass

In understanding the effect of K+ substitution by M2+ (M = Ca, Sr, and Ba) on crystallization and microstructural properties of boroaluminosilicate glass system, the SiO2-MgO-Al2O3-B2O3-MgF2-K2O-Li2O-AlPO4 glasses were prepared by single-step melt-quenching at 1500°C. Density of base glass (2.64 g·cm−3) is found to be decreased in presence of CaO and SrO. Tg is increased by 5–10°C and Td decreased by 13–20°C on addition of M2+. The variation of Tg, Td and decrease of thermal expansion (CTE) from 7.55 to 6.67–6.97 (×10−6/K, at 50–500°C) in substituting K+ by M2+ are attributed to the higher field-strength of Ca2+, Sr2+, and Ba2+. Opaque mica glass-ceramics were derived from the transparent boroaluminosilicate glasses by controlled heat treatment at 1050°C (duration = 4 h); and the predominant crystalline phase was identified as fluorophlogopite (KMg3AlSi3O10F2) by XRD and FTIR study. Glass-ceramic microstructure reveals that the platelike mica flake crystals predominate in presence of K2O and CaO but restructured to smaller droplet like spherical shaped mica on addition of SrO and BaO. Wide range of CTE values (9.54–13.38 × 10−6/K at 50–800°C) are obtained for such glass-ceramics. Having higher CTE value after crystallization, the CaO containing SiO2-MgO-Al2O3-B2O3-MgF2-K2O-Li2O-AlPO4 glass can be useful as SOFC sealing material.