The Research On Baiying Red Clay Of Their Character And Application

Gansu Baiyin pottery has a long history.With the need for high-quality development of the regional ceramic industry,the local government has proposed measures to develop the red pottery industry to add momentum to the regional industrial transformation and upgrading.This paper uses red clay in Baiyin,Gansu Province as the main raw material.We explore the physical and chemical properties of the selected red clay through ceramic technology experiments and modern detection methods and optimizes the ratio of raw materials for the preparation of red pottery products.This work has yielded fruitful results.The main details are as follows:（i）The selected red clay mineral materials are mainly SiO₂,Al₂O₃,Fe₂O₃,and K₂O.The main minerals of 1^#,3^#,and 4^#are quartz,kaolinite and illite,which are found under the transmission electron microscope.The typical characteristics of clay minerals,2^#mineral composition is mainly composed of quartz and kaolinite,and the four selected red clay iron-bearing phases are all hematite.（ii）The plasticity of the selected red clay mineral raw materials is high except that the 3^#raw material has low plasticity,which can give the terracotta good molding properties.The shrinkage rate generally increases with the increase of temperature,and the phenomenon of reverse expansion occurs after complete sintering.The maximum flexural strength is 93.4 MPa of 2^#raw material at 1100℃.The firing color of the selected red clay deepens with the increase of temperature,and the lightness value,redness value and yellowness value all decrease with the increase of temperature before overburning.（iii）The selected red clay mineral raw materials have an endothermic peak caused by the phase change of the clay minerals due to the removal of structural water between 517°C and 589°C.（iv）XRD characterization results show that the clay mineral has been completely decomposed,but the mullite phase appears when the temperature at 1060°C.During the entire firing process,quartz and hematite hardly undergo phase transitions,but their strength gradually decreases as the temperature increases.（v）The red pottery products of the selected 3 kinds of raw material ratios are better sintered at 1100℃.The main crystal phase of the prepared red pottery products is quartz phase,and the secondary crystal phase is mullite phase,which is the best raw material for red pottery products.The ratio 1^#:2^#:4^#is 1:1:3.After adding 3^#raw material,the mullite diffraction peak intensity of the XRD pattern increased.（vi）When the additive amount of 3^#red clay is 12 wt%,the red pottery products with a flexural strength of 89.17 MPa can be obtained at a sintering temperature of 1100°C;the process performance can meet the requirements of low-temperature fast firing,which can be used in the regional building ceramic industry and provide support for energy saving and consumption reduction.When the amount of 3^#red clay is 8wt%,the water absorption rate can reach 6.7%under the condition of 1100℃temperature and excellent performance.After burning,the color is deep red,which is conducive to the development of daily pottery,artistic pottery and colored pottery.