Study On Preparation Technology The Self-releasing Glaze Of R₂O-RO-Al₂O₃-SiO₂ System

With the progress of the times,the ceramic manufacturing industry has been rapidly innovating.In recent years,China's output of artistic porcelain and porcelain production is the first in the world.However,the high yield is accompanied by high pollution,high consumption and high cost,so energy saving,emission reduction and material saving in the ceramic industry have become an urgent task.The self-releasing glaze studied in this topic can reduce the consumption of raw materials by eliminating the glazing process.This topic mainly studies the preparation and formation mechanism of R₂O-RO-Al₂O₃-SiO₂ system self-releasing glaze,and explores the influence of different formulations and different preparation processes on the formation of self-releasing glaze.The glossiness of the sample surface is measured by a gloss meter,the phase composition of the sample is analyzed by XRD,the physical and chemical changes of the green body during heating are analyzed by DSC,and the microstructure and element distribution of the sample are analyzed by SEM and EDS,Based on the influence of process factors on the performance of self-release glaze and the optimization of formula,different types of self-releasing glaze samples were prepared by different processes.The main research contents and results are as follows:?1?Through orthogonal experiments and single-factor experiments,the formulation and firing process of water-soluble self-releasing glaze?Na₂O-K₂O-Al₂O₃-SiO₂ system?are studied,and the raw materials and firing temperature,holding time and self-releasing agent are explored.Then explore the concentration of the self-releasing agent in different positions of the green body and different drying time in the drying stage,and study the effect and mechanism of the self-releasing agent in the formation process of the self-releasing glaze.The results show that: in a water-soluble self-releasing glaze system,when 5wt.% Of self-releasing agent is added and fired at 1200 ? for 30 minutes,the self-releasing glaze with a gloss of 60.7 and smooth surface without obvious defects can be obtained.As the temperature increases,the holding time increases,and the content of the self-releasing agent increases,the effect of the self-releasing glaze increases,but the sample undergoes a large deformation.In the water-soluble self-releasing glaze system,the diffusion of the self-releasing agent is divided into two stages.The first stage is to diffuse to the surface layer of the green body through water during the drying period,and the second stage is in the firing stage,the self-releasing agent melt or the eutectic melt formed by the self-releasing agent and the green body reaches the surface of the green body under the action of capillary force,and the two stages work together to form a self-releasing glaze.?2?Through orthogonal experiments and single factor experiments,the composition of the in-situ system self-releasing glaze?K2O-Ca O-Al₂O₃-SiO₂ system?formula and firing process were studied,and the formula composition,firing temperature and holding time were investigated.For the effect of self-releasing glaze,XRD,SEM and other detection methods were used to analyze the phase composition and micro-morphology of the sample,and the phase diagram was used to explore the formation mechanism of self-releasing glaze.The results show that the cristobalite precipitated in the high-temperature glaze melt constitutes the capillary force.Due to the precipitation of cristobalite,the melt viscosity decreases,and the capillary force causes the melt to migrate to the surface of the green body to form a glaze layer.When the content of kaolin and quartz is increased,the gloss of the sample gradually decreases,and the effect of self-releasing glaze becomes poor;when the content of wollastonite is increased,the firing temperature and the holding time are increased,the gloss of the sample increases,but a large deformation occurs.When SiO₂ is 60? 70%,Al₂O₃ is 10?20%,Ca O is 5?15%,K2 O is 0?5%,under the condition of 1250 ? and 30 min heat preservation,the transparent glaze can be obtained without obvious defects.The self-releasing glazed ceramics without deformation of the body have a gloss of 57,compressive strength of 28.7MPa,and a water absorption rate of 0.1%.?3?On the basis of optimizing the preparation process parameters,a water-soluble self-releasing glaze formulation was adopted,and the dry-press molding process was used to obtain an exterior wall tile with a gloss of 56.7,a firing shrinkage rate of 5.7%,and a water absorption rate of 0.1% by holding at 1200 ? for 30 minutes.Using the in-situ method of self-releasing glaze formula,the green body is obtained by compression molding,and the porcelain plate is decorated with ceramic painting and fired in a reducing atmosphere at a firing temperature of 1250? to obtain a full-color blue and white porcelain plate painting.In addition,with the in-situ method of self-releasing glaze formula,using the grouting molding process,firing at 1250? can produce a self-releasing glaze vase with high gloss.