Zirconia

Zirconia special refractory with high temperature (2200~2400℃), a wide range of adaptability, a variety of furnace atmosphere, strong slag erosion resistance and other advantages, has become an extremely important furnace lining material for ultra-high temperature industrial applications.

Zirconia mud casting products, is the use of acid mud casting production process. High purity zirconia and high purity calcium hydroxide as raw materials, according to ZrO2:CaO=95:5, mixed fine grinding pressed into blocks, at 1250℃ insulation for 4h, for stabilization treatment. The stabilized material is crushed and mixed with 15% monoclinic zirconia. The strength of the fine membrane is less than 3 microns. If in the iron ball mill fine abrasive, but also pickling in addition to iron, metal iron content less than 0.01%.

Zirconia mud density is required to be 1.9~2.1g/cm3,pH value =1.7~1.9. Cast with gypsum mold, model size rate is 15%, the operation method is the same as that of alumina mud casting products. After demoulding, the product was immediately placed in the electric furnace and roasted at 850℃ for 2h. After cooling, sand paper was used to repair and shape the billet. Finally, it was fired in a high-temperature kiln at 1800 ~ 1850℃ for 4 ~ 6h.

Zirconia heating element can be used as heater for high temperature resistance furnace at 1700~2000℃. Using high purity calcium oxide zirconia, yttrium oxide, cerium oxide, as raw materials can be as follows: zirconia 87%, calcium oxide 13%; , 90% zirconia, 10% yttrium oxide; , zirconia 75%, cerium oxide 25% three ingredients. The ingredients are mixed in a ball mill for fine grinding with a force of less than 3 microns and over 80%. 6% polyvinyl alcohol solution (10% concentration) was added into the fine film powder, mixed evenly and then made into the billet with 100MPa and pressure through a 0.5mm sieve, and then made into the stable zirconia clinker after being kept at 1730℃ for 4h.

After stable clinker fine grinding strength less than 10 microns accounts for more than 95%, if the abrasive in the iron ball mill, also carry out pickling iron dry powder.

The preparation of wax paste is stable zirconia dry powder 85%, paraffin wax 13.5%, yellow wax 1%, mixed aliphatic acid 0.5%. Heat mixing is carried out at 70~80℃. Wax paste should be free of powder and air bubbles.

With the metal mold in the hot injection machine forming, wax slurry temperature maintained at 60~70℃, mold release rate of 13%~15%. The specific operation method is the same as that of alumina hot-pressed injection products. The hot pressing injection body was filled with industrial alumina in saggar and dewaxed at 1200℃ for 4 hours. The products are prepared by hanging method in a vacuum furnace with a vacuum degree of 1× 10-5kpa (1× 10-4mmhg) and heated at 1650℃ for 3h. Zirconia heating elements produced by a factory in shandong were fired in a tungsten rod furnace at 2000℃ for two hours.

After fine grinding, TZP and zirconia ceramic grinding medium balls were produced by dry pressing on isostatic press. This kind of medium ball has high density, good toughness, high strength, high grinding efficiency and good effect.

With isostatic pressing molding of steelmaking continuous casting with skateboards brick of the physical and chemical performance indicators: ZrO2 ≧ 94%, Y2O3 ≧ 1.5%, Y2O3 + CaO + MgO3 % ~ 5%, Al2O3 ﹤ 0.2%, stability of 70% ~ 80%, the volume density of 4.65 ~ 5.0 g/cm3, 15% ~ 20% porosity and compressive strength of 100 mpa, thermal shock resistance (1100 ℃ ↔ water-cooled) ≧ 3 times.

With electric melting stabilized zirconia as raw material, according to the machine press molding production process, at 1800℃ insulation 6~10h, burned into zirconia brick can be used for a variety of ultra-high temperature furnace lining, carbon black furnace lining, the use temperature can reach 2000~2400℃.

This product is mainly used in various low-alkali glass kilns, such as hard borosilicate glass kilns (laboratory glassware glass, cooking glass, enclosed headlamp glass and e-glass kilns), aluminosilicate glass kilns (photoelectric mask glass, glass ceramics and s-glass fiber kilns). This kind of melting casting brick sends density big, fight glass fluid erosive sex is strong, use effect is good, do not produce stripe and spot to all sorts of glass. The production process of this product is a three-phase electric arc furnace. After the zirconia is melted, the product is poured into a zirconium casting mold and then cooled slowly in an incubator or annealing furnace to prevent cracks.

(1) the properties of zirconia slurry casting products produced by shandong refractory factory are shown in table 14-36.

(2) the allowable deviation of zirconia crucible size is shown in table 14-37. The allowable sizes of zirconia thermocouple sleeves are shown in table 14-38. Zirconia crucible is used for smelting various precious metals and their alloys. Such as smelting platinum, platinum-rhodium, platinum-iridium, gold, silver and so on.

(3) properties of zirconia ceramic products produced by luoyang refractory research institute: chemical composition ZrO2+CaO, greater than 99%, main crystal phase is cubic phase, service temperature is 2300℃, apparent porosity is less than 1%, volume density is 5.4g/cm3. Properties of foreign zirconia ceramic products are shown in table 14-39 and table 14-40.

(4) the physical and chemical properties of zirconia heating elements used in a factory in shandong province are shown in table 14-41.

(5) physical and chemical properties of zirconia grinding medium balls produced by isostatic pressure forming method in shenzhen nanbo factory are shown in table 14-42.

(6) the properties of yttria stabilized zirconia products produced by luoyang refractories research institute by granulation powder pressing molding method are shown in table 14-43.

(7) the properties of zirconia bricks produced by shandong refractory factory are shown in table 14-44 and table 14-45.

(8) the performance comparison of zirconia products produced by luoyang refractory research institute and domestic and foreign products is shown in table 14-46.

(9) the physical and chemical properties of the fused cast zirconia bricks produced by a foreign company are shown in table 14-47. Zirconia melting point 2650℃, true density 5.63g/cm3, disregard hardness 6.5, temperature 20~1000℃, average linear expansion coefficient (℃-1) 10×10-6, thermal conductivity,3~4W(m·K). Zirconia material has excellent chemical stability, not easy to decompose, not easy to react with other oxides, strong resistance to corrosion of slag, molten steel and liquid glass. Zirconia products have a wide range of applications because of their conductivity at high temperature. Applications of zirconia products are shown in table 14-48.