Colouring Research Of Transition Metal Oxides On R₂O-CaO-SiO₂-F System Glass-ceramics

The features of R2O-CaO-SiO2-F glass-ceramics are rolling forming, a continuous production process with low molding temperature, low viscosity, high fracture toughness, good processibility and low energy consumption.This paper is mainly prepared pigment by simulating forehearth coloring, discussed the diffusing speed of pigment in white glass and prepared the level coloring of glass-ceramic by stirring process. The surface of the colored glass-ceramic is without streaks, color soft and homogeneous, is a high potential of decorative panel material.Two kinds of colorants Co2O3 and K2Cr2O7 are separately doped into the glass system:using DTA, UV-3600, XRD, SEM and other testing means to study situations of coloring and crystallization. The results show that:K2Cr2O7 colored glass was yellow-green,while Co2O3 colored was blue. K2Cr2O7 promoted heterogeneous nucleation of calcium stone base a-Si precipitation; the suitable introduction amount of chromium oxide is about 0.2wt%, excess chromium is not conducive to the precipitation of calcium stone phase; the appropriate introduction of cobalt oxide is about 0.08wt%, Co2O3 coloring agent content can not exceed 0.1 wt%.In this paper, the pigment directly put into the molten glass, by means of adjusting and determining the composition of pigment by comparing the density of pigment and the spread depth in white glass.The results showed that:the composition of better pigment are as follows; the composition of chrome pigment: SiO240wt%, Li2O 0.5wt%, Na2O 14.5wt%, K2O 6.4 wt%, CaO 2wt%, CaF24wt%, Na2SiF64wt%, B2O315wt%, Cr2O3 10wt%. The composition of Cobalt pigment SiO2 42.1 wt%, Li2O 0.57 wt%, Na2O 15.22 wt%, K2O 6.73 wt%, CaO 2.1 wt%, CaF24.21 wt%, Na2SiF64.21 wt%, B2O3 15.79 wt%, Co2O3 5.27 wt%. The ratio of pigment and white glass are as follows; chrome pigment:white glass 1:50. Cobalt pigments: white glass 1:66.This paper simulate forehearth coloring and discuss the diffusion rate by adding pigment into the molten glass at different temperatures and in the different time. Finally the colored glass-ceramics are prepared by operation similar to stirring, using UV-3600 and EPR to discuss the mechanism of coloring glass. The results show that: the diffusion rate of Chrome pigment increased with the temperature in glass at 1100℃to 1250℃, but the larger increasing rate occurred at 1200℃. At 1200℃, the diffusion rate of chromium pigment R1 is 0.283mm/min.At 1200℃, the diffusion speed 01 of cobalt pigment in the longitudinal direction is 0.3415mm/min. At 1200℃lateral diffusion rate of 0.273mm/min. The diffusion depth of Cobalt pigment in white glass increases with increasing temperature increasing, when the temperature rose from 1150℃to 1200℃, the increase is more evident.In the colored R2O-CaO-SiO2-F glass-ceramics, the cobalt pigment promote canasite precipitation; chrome pigment can also promote heterogeneous nucleation of A-canasite precipitation, chromium oxide is used as a nucleating agent in glass In the chromium glass, a part of Cr3+ turn into Cr6+ after the heat treatment.