The utilization of boron containing waste in hard porcelain body and its characterization

In this study the utilization of boron oxide, B2O3, containing waste from the tincal processing for the production of borax and boric acid (obtained from Eti Mining Kirka plant) , as a fluxing agent to compensate for potassium feldspar in hard porcelain bodies was investigated. The raw materilas used were characterized by XRF and AAS methods. The porcelain body compositions were prepared in various flux ratios. Instead of potassium feldspar as a flux boron oxide containing waste was used in ratios 5 to 25%. For comparison purposes a composition which did not include waste material was designed as the reference composition. The green body specimens were shaped with dry powder pressing. In order to achieve green bodies at maximum density the particle size distribution was calculated according to Furnas and Adreasen equation, and the same distribution used for all of the specimens. The prepared green specimenss were sintered at temperatures in a range from 1000oC to 1350oC. The mechanical and physical properties of the sintered specimens were determinedby three point bending (strength), impact resistance (charpy test), He-picnometry (open and closed porosity determination), water absorption, shrinkage, Lab (for fired color) tests, methods and measurements. SEM, XRD, methods were used for the microstructural characterization of the fired specimens while0 optical dilatometry, TG-DTA methods were used to determine the sintering behavior of the green specimens. The sintering temperature was 200oC lower on teh average for the specimens including the waste containing B2O3. In teh specimens containing the waste material the closed porosity increased while the open porosity decreased by the increasing sintering temperature. At sintering temperatures lower than 1150oC, the 10% waste containing specimens were exhibited higher impact resistance while their bending strength values were comparable to the specimens that did not contain the waste material. Especially at lower sintering temperatures the firing color of the waste containing specimens was determined to be whiter (with higher L values). It was concluded that the boron oxide containing waste from the tincal processing could be used as a fluxing agent in the hard porcelain bodies.