Research On Synthesis Of Spinel Pigment And Its Colour Stability And Uniformity Of Brown Glaze For Porcelain Insulator

The raw material of electric porcelain brown glaze compounded naturally has the advantages of being resourceful, simply prepared, low cost and applied widely. However, the fluctuation of raw material composition and preparation always cause instability of colouration and obvious chromatism. Using synthetic pigment to compound glaze can somehow solve this problem.First, chemical materials of Fe2O3、MnO2and Cr2O3were used to synthesize brown spinel pigment with the conditions of electric heating. Triangle ingredients method was used to determine the pigment recipe. Relationship among the content in various oxides, pigment color values and glaze color change was studied. Result shows that when the ratio of chemical materials equals Fe2O3:Cr2O3:MnO2=l:1:3, pigment presents best color values. The addition of MgO is helpful for the colouration of reddish brown in glaze. Particularly the best colouration could be obtained when the MgO content of0.05mol.Second, microwave sintering and electric heating sintering techniques were used to prepare the brown spinel pigment whose component, microstructure and coloration were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and color difference meter, etc. The results show that the microwave sintering method can decrease the sintering temperature about200℃and cut down the sintering time to about1/12th and can en hance the coloration properties. The pigment synthesized by microwave heating present the features of fine, regular and uniform grain and ideal colouration result as well. The stability of porcelain insulator colouration can be increased and the chromatism or other defects can be reduced by using synthesized pigment.The color values of pigment increased with the increasing of milling particle size of pigment, and D50reaches2.95μm after the particles are grinded for3hour.Third, the glaze body fit and colour uniformity of brown glaze was investigated. The results show that by adding brown spinel pigment, the glaze body fits better than the traditional brown glaze. Comparde with unglazed strip, the bending strength of the pigment-glaze was increased by27.8%, and compared with the traditional brown glaze, the pigment-glaze bending strength was also enhanced by9.86%. The colour uniformity of porcelain insulator colouration can be increased and the chromatism or other defects can be reduced by using synthesized pigment.