Research On Ceramic Color Sand

The various kinds of industrial solid wastes have done great harm to our environment, and their amounts keep growing. So, the disposal of them becomes more and more important. Red mud is one of the largest pollutants. Red mud, fly ash and coal gangue were used as the main raw materials of the body of color sand, and glaze firing method was used to prepare color sand in this paper.The red mud body of color sand was formed to small balls by hand, and fired during 1060¹140℃. The Water absorption (Wa), Porosity (Pa), Bulk density (D) and crushing strength, acid resistance, alkali resistance have been tested. The factors affecting performances of the body, the mechanism of erosion by acid or alkali and the reaction mechanism occuring on firing were studied. Then, the optimal formula and optimal preparation technology were confirmed.In the initial stage of the research work, frit 2004, a kind of frit in market was introduced to be made semi-fritted glaze. The results showed that the firing temperature was during 1020¹050℃ for the optimal sample. More over, two kinds of frits were melted in order to decrease the glaze firing temperature further. A large amount of borax was added as the fusing agent. One kind of the frit used zirconite as the opacifying agent, and the other used TiO₂. The optimal formula and the appropriate melting technology were researched. Fritted glaze were made using the two kinds of frits, and the glaze firing temperature was during 850¹000℃. The coefficient of linear expansion of the body and glaze, the melting temperature range, the whiteness, the microhardness and the heat stability of glaze were tested. The microstructures and properties of the two kinds of glaze were discussed, as well as the opaque mechanism and the reaction mechanism.The modern testing techniques such as XRD, SEM and EPMA were used to analyze the crystal phase composition and the microstructures. The results indicated that, the main crystal phases in the body were anorthite and diopside, zirconite and diopside in the boron and zirconium fritted glaze, sphene in boron and titanium fritted glaze. Part of the glass phase in the body was eroded by acid or alkali, and the size of pores became bigger after being eroded. There were many pores in the glaze,and a great mount of small crystal grains scattered in it. The glass phase separation existed in both of the two kinds of opaque glaze, the opaque mechanisms could be concluded to be liquated out-separated phase. In the glaze -body interface, the glass infiltrated to the body, while the crystals in body enriched in the interface.Some kinds of pigments were added to the two optimal fritted glazes to prepare color sand. The technologies to glaze the body and to generate color were discussed, and found that the method to wrap the body with dried glaze powder was best. The chroma value and the physical & chemical performances of color sand were test, and the factors effecting the generation of color and firmness of color sand were analyzed.