Anorthite production from fly ash with addition of boron

In this study, anorthite ceramic, used as base material of integrated circuit inelectronics industry, is tried to produce from fly ash of thermal power stationwith addition of boric acid by means of powder metallurgy. The specimens thatwas produced with addition of different amounts of boron (2%, 4% and 6%)and without boron were sintered between 900oC-1300oC and characterisedusing XRF, XRD and SEM. XRF results indicated that the composition of thespecimens were near to the anorthite composition but they also contained highamounts of impurities. These impurities were due to fly ash that was used in theanorthite production. XRD analysis revealed that anorthite is formed at 900oCand its amount is increased with temperature. However, no single phase ofanorthite was obtained eventhough it was about completely transformed toanorthite at 1200oC. Boric acid addition accelerated the formation of anorthitebut high levels of boron did not have a significant effect on anorthite formation.SEM analysis showed that boron added samples had more uniformmicrostructure than boron free samples. Nevertheless, as the boron content wasincreased, the partial meltings rised and at 1200oC both boron added and boronfree samples contained significant amount of glassy phase. Densitymeasurements of boron contained and boron free specimens indicated thatthere were no consistent relation between density and temparature and densityand boron content. The maximum relative density obtained in boron added andboron free samples was around 61%. In order to obtain higher density value,the specimens were subjected to further sintering at 1300oC and resulted inmelting. Therefore it was not possible to caracterise those specimens.