Effects of Co/Fe Sulfate Pigments on the Colour and Phase of Porcelain

초록

In this study, an Co/Fe coated porcelain using a cobalt and ferrous sulfate was sintered at 1,250 oC. The specimens were investigated by HR-XRD, FE-SEM (EDS), Dilatometer, and UV-vis spectrophotometer. The surface of the porcelain was uniformly fused with the pigment, and white ware and celadon body specimens were densely fused to a certain thickness from the surface. Other new compounds were produced by the chemical reaction of cobalt/ferrous sulfate with the porcelain body during the sintering process. These compounds were identified as cobalt ferrite spinel phases for white ware and white mixed ware, and an andradite phase for the celadon body, and the amorphous phase, respectively. As for the color of the specimens coated with cobalt and ferrous mixed pigments, it was found that the L* value was greatly affected by the white ware, and the a* and b* values were significantly changed in the celadon body. The L* values of the specimens fired with pure white ware, celadon body, and white mix ware were 72.1, 60.92, 82.34, respectively. The C7F3 pigment coated porcelain fired at 1,250 oC had L* values of 39.91, 50.17, and 40.53 for the white ware, celadon body, and white mixed ware, respectively; with a* values of -1.07, -2.04, and -0.19, and at b* values of 0.46 and 6.01, it was found to be 4.03. As a new cobalt ferrite spinel phase was formed, it seemed to have had a great influence on the color change of the ceramic surface.

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