The Relationship Between the Composition,Melt Structure and High Temperature Viscosity of Longquan Celadon Glaze
Based on the chemical composition of plum green glaze in Longquan kiln,2%of various oxides were used instead of 2%SiO2 in preparing seven kinds of glazes.The initial melting temperature,full melting temperature and flow temperature of the glaze melt were determined by glaze melting experiments.The glaze appearance quality,glaze bubbles and crystal changes,glaze layer glaze degree and earthworm pattern distribution at the bottom of the product were observed through the firing experiments of the glazed products.Combined with the theory of molten molecular structure of the melt,the effect of seven oxides,namely SiO2,Al2O3,K2O,Na2O,CaO,of MgO and Fe2O3 on the high temperature viscosity of the glaze melt was revealed.Increase of the SiO2 or Al2O3 content will increase the high temperature viscosity of the melt,of which the influence of Al2O3 is greater.In-crease of the content of any of the monoxides in K2O,Na2O,CaO,MgO,Fe2O3 reduces the high temperature viscosity of the glaze melt,of which CaO has the greatest degree of influence,and MgO has the least effect,and K2O makes the melting range of the glaze expand while CaO makes the melting range of the glaze narrow.
Longquan celadon porcelainplum glazeoxideglaze melthigh temperature viscosity