Research Of High-strength Ceramic Plate

China is one of the countries which produce, cousume and export abundant constraction ceramics. Constraction ceramics industry has always been considered of high pollution, high energy consumption industries, over the past decade of rapid development has led to so many ceramic raw materials such as kaolin faces mining excessive and depletion, environmental issues are increasingly being people's attention, so developing green constraction ceramics has become the target of the whole industry. Ceramic plate is larger and thinner than traditional constraction ceramics, has the advantages of raw materials saving such as kaolin and energy saving due to rapid firing, is the direction of the future development of constraction ceramics.In this paper, Erdos kaolin, Erdos quartz, Erdos feldspar, Yingde albite, Ordos talc were used as raw materials to prepare the constraction ceramic plate. Erdos purple knar clay and Xinjiang andalusite were added separately to enhance constraction ceramic plate. Purple knar clay improve plasticity of body so that the materials have a higher green strength, at high temperatures, it will converte into mullite, mullite formed as reticulation and increase strength of the materials.Andalusite at high temperatures also can transforme into mullite, while the volume of micro-expansion occurs, it can offset shrinkage of the materials after firing and ensure the stability of the sample's size. Selected the formula with overall best performance, plus a small amount of silicon carbide to lose the bulk density of the ceramic plate, and wish to generate uniformly distributed small-sized closed pores in the sample, so the bulk density of the sample reduced but also insure the mechanical strength of the sample measure up the GB/T 23266-2009. XRF, TG-DSC, XRD, SEM and other modern testing methods were used to study the relationship of preparation,phase composition, microstructure and properties of the materials, and explore the mechanism of reinforced and weight loss materials, and choose the best formula for pilotscale experiment, the results are as follows:(1) The chemical composition, phase composition and microstructure of Ordos raw materials were analyzed firstly, the results showed that the purple knar clay andkaolin have large loss on ignition, kaolin has less content of Fe2O3, TiO2, CaO and MgO, is a high-quality clay. The content of Al2O3 in purple knar clay is up to 42.33%,the appearance of it is brown for higher content of Fe2O3, TiO2. The quartz contain98.32% SiO2. feldspar contain 14.46% K2 O and Na2 O, is a good flux material. Talc contain 31.27% MgO and 1.85% CaO. The purple knar clay apart from kaolinite phase, there are a small amount of quartz and boehmite. The SEM topography of kaolin and purple knar clay are similar, have small particle size about 1?m.(2) In order to enhance the ceramic plate, different amount of the purple knar clay was added to the base formula, with the amount of purple knar clay increasing,samples' green strength improved, and the sintering temperature rised. Physical and chemical properties of the samples were tested and the results showed that the sample A2 added amount of 5% purple knar clay fired at 1140? had the best performance,total shrinkage is 10.46%, water absorption is 0.03%, porosity is 0.07%, bulk density is 2.43g/cm3, the bending strength is 74.95 MPa, compared to the basic formula samples A1 enhanced 23.4%. XRD showed that the main phase are mullite and quartz.SEM topography revealed samples of A series have high density and low porosity its size is about 5?m. there are plenty of short columnar and needle rod mullite generated,the length is about 1?m, and residual quartz grains are distributed in the matrix.Enhancement mechanism showed boehmite break down into alumina at about 500?,silica react with alumina to mullite, mullite can toughen ceramic plate. With the content of purple knar clay increasing, the content of silica increased, the limited capacity of the high temperature liquid molten quartz, quartz particles uniformly distributed in the liquid phase enhanced the samples.(3) For the sake of enhancing the ceramic plate continuely, different amount of the Xinjiang andalusite was added to the base formula. Physical and chemical properties of the samples were tested, and found that, the sample with andalusite of5% fired at 1120 ? had a superior properties, total shrinkage is 10.33%, water absorption is 0.34%, porosity is 0.81%, bulk density is 2.43g/cm3, and bending strength is 90.23 MPa, compared to the basic formula samples B1 enhanced 54.1%,had a significant effect. When added a large amount of andalusite, the bending strength decreased, but the bulk density also reduced. XRD showed that the main phase are quartz, andalusite and mullite. SEM topography revealed with the amountof andalusite increasing, the content of the needle rod mullite significantly reduced,B2 and B3 samples added less amount of andalusite had fewer stomata and high density. The samples B4 and B5 added large amount of andalusite had more pores its size is about 10~20?m, a large number of lath-shaped andalusite distributed in the samples. Enhancement mechanism showed andalusite began to decompose at about1200?, is inert in 1120?~1200?, andalusite evenly distributed in the liquid phase can improve the strength of the samples. With the content of andalusite increasing,the content of silica increased, it can enhance the samples without decreasing the density of samples.(4) To lose weight of ceramic plate, and ensure the bending strength and water absorption, a small amount of silicon carbide was added to the formula A2 and B2. In order to explore how the added amount of silicon carbide, the firing temperature and holding time affect the properties of samples, the silicon carbide could significantly reduce the bulk density of the samples, bulk density of C8 sample fired at 1200? for60 min is low to 1g/cm3. The samples C4 and C8 which added 0.5% silicon carbide were fired at 1140? for 30 min, respectively, the water absorption are 0.11% and0.33%, bending strength are 65.51 MPa and 68.72 MPa, bulk density are 2.25 g/cm3 and 2.17g/cm3, compared with the densification of the samples A2 and B2 reduced by7.4% and 10.7%. XRD showed there is no significant influence to the phase composition after the addition of silicon carbide, are mullite, quartz and andalusite.SEM topography revealed with the content of silicon carbide, firing temperature and holding time increasing, the pore size in the samples became larger. Sample C4 fired at 1140? for 30 min and sample C8 fired at 1180? for 15 min have small pore size about 5?m. Small pores uniformly distributed into the samples could reduce the bulk density and had little impact on bending strength of the samples. Weight loss mechanism showed that high temperature liquid of feldspar destroyed the protective film of silicon which formed by oxidation of silicon carbide after 1000 ~1100 ?,promoted a large number of silicon carbide reacting, the carbon dioxide gas wrapped by liquid and formed a lot of independent closed pores after cooling and solidifying,therefore declined the density of the samples. With the Increasing of addition of silicon carbide, the firing temperature and holding time, the number of pores increased for the reaction of silicon carbide. on the other hand, the merging ofbubbles increase the size of pores owing to the high-temperature viscosity of the liquid phase reduced.Taken water absorption, bending strength and bulk density into consideration,bulk density as small as possible without water absorption and bending strength meet the requirements of GB/T 23266-2009, choose the best formula for reducing pyroplastic deformation experiment. Samples C4 and C8 fired at 1140? for 30 min had a low deformation about 5mm, this two formulas were suitable for pilotscale experiments. Pilotscale experiment had shown that the appearance of samples were smooth and had no deformation, cracks and other defects, the results could be used for the preparation of ceramic plate for decoration.