Method for preparing ZrN-Al2O3-ZrO2 multiphase ceramic material by aluminum nitride-zirconium dioxide reactive sintering

Abstract

The invention relates to a method for preparing a ZrN-aluminum nitride2O3-ZrO2 multiphase ceramic material by aluminum nitride-zirconium dioxide reactive sintering, belonging to the field of high-temperature ceramic materials. The multiphase material is prepared from the following raw materials in percentage by mass: 5-40% of aluminum nitride fine powder, 60-95% of monoclinic zirconium dioxide fine powder, and 1-1.5% of sintering accelerator (CaF2 or ZrB2 or MoSi2) fine powder (additional). The method comprises the following steps: dryly mixing the raw materials, adding anhydrous ethanol, and wetly mixing; removing ethanol from the slurry, adding a rosin ethanol solution, stirring, and standing in a sealed environment to obtain a blank; and molding the blank, drying, and keeping the temperature at 1400 DEG C for 6-8 hours in a dynamic nitrogen atmosphere to obtain the ZrN-Al2O3-ZrO2 multiphase ceramic material. The multiphase material has the advantages of high soaking capacity, small thermal expansion coefficient and favorable thermal shock resistance, is assisted by a microcrack toughening mechanism, and can provide a novel high-temperature ceramic material for the fields of steel and non-ferrous metallurgy, construction materials, electronics and the like.

Description

technical field [0001] The invention belongs to the field of high-temperature ceramic materials, in particular to the preparation of ZrN-Al by reaction sintering of aluminum nitride-zirconia 2 o 3 -ZrO 2 Methods for Composite Materials. Background technique [0002] ZrO 2 It has many excellent characteristics such as high melting point (2700°C), good chemical stability, high hardness, and is not easy to be wetted and eroded by metal solution. It is a high-temperature material that has attracted much attention. But due to ZrO 2 There are three crystal forms with different densities (cubic zirconia c-ZrO 2 6.27g / cm 3 , tetragonal zirconia t-ZrO 2 6.10g / cm 3 and monoclinic zirconia m-ZrO 2 5.68g / cm 3 ), in the temperature range from room temperature to 2700 °C, ZrO 2 m-ZrO 2 →t-ZrO 2 →c-ZrO 2 Crystal transformation, temperature drop ZrO 2 reverse transformation occurs, and in ZrO 2 When the crystal transformation occurs, it is accompanied by a large volume effe...

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Problems solved by technology

[0004] As a high-temperature structural material, although ZrO 2 The material has been widely used, but because of ZrO 2 The volume effect of crystal transformation is large, and the thermal conductivity is small (about 0.36-1.27W m -1 ·K -1 ), high coefficient of thermal expansion (α=8~11×10 -6 / °C), its poor thermal shock resistance is still an urgent problem to be solved.

For example, during metallurgical continuous casting and pouring steel, the zirconia sizing nozzle undergoes a high-temperature sudden change from 800°C (preheating temperature) to about 1650°C (molten steel temperature). Such harsh thermal shock conditions can easily cause the zirconia sizing nozzle to Thermal shock cracking occurs, which deteriorates the erosion resistance of the sizing nozzle to molten steel, and greatly reduces the service life of the zirconia sizing nozzle, and even interrupts the continuous casting process due to abnormal changes in the hole diameter, resulting in excessive flow of molten steel, or steel breakout , or damage the key continuous casting equipment "mold"

For this reason, Shandong Laiwu Iron and Steel Co., Ltd. has developed a domestically initiated and internationally leading continuous casting tundish pouring sizing nozzle quick replacement device, and proposed a continuous casting tundish sizing nozzle rapid replacement technology for continuous flow, which is used to solve the problem of oxidation. The service life of zirconium nozzle is short, the tundish is replaced frequently, there is a large amount of molten steel injection, the loss of cutting head and tail of continuous casting blank is large, and the casting speed is too fast due to the erosion of nozzle in the later stage of casting, which is not good for the quality of casting blank and may cause leakage. Problems such as steel accidents

Although this measure relieved the impediment brought by the short life of the zirconia nozzle to the rapid development of high-efficiency continuous casting technology, it did not fundamentally solve the inapplicability of the current sizing nozzle material to the existing high-efficiency rapid continuous casting process The problem