Reactive sintering method for preparing magnesia alumina spinel

Abstract

The invention discloses a reactive sintering method for preparing magnesia alumina spinel, which is characterized by comprising the following steps: heating a dry green compact to 1250-1550 DEG C in a resistance furnace at the rate of 4-16 DEG C / minute, and keeping the temperature for 0.5-16 hours; heating to 1550-1750 DEG C at the rate of 4-16 DEG C / minute, and keeping the temperature for not more than 1.5 hours; and cooling to 1300-1600 DEG C at the rate of 10-70 DEG C / minute, keeping the temperature for 0.5-16 hours, and naturally cooling to room temperature to obtain the uniform-microstructure high-density magnesia alumina spinel. The method is beneficial to lowering the sintering temperature and shortening the holding time at high temperature, thereby lowering the energy consumption. The method improves the microstructure of the magnesia alumina spinel ceramic material, and enhances the mechanical properties of the magnesia alumina spinel ceramic material. The method improves the melt permeation resistance and corrosion resistance of the magnesia alumina spinel.

Description

Technical field [0001] The invention belongs to the technical field of powder metallurgy, and specifically relates to a reaction sintering method for preparing magnesium aluminum spinel. Background technique [0002] MgAl 2 O 4 Spinel (MAS) has a face-centered cubic crystal structure, so MAS has some important properties, such as high melting point (2135°C), high mechanical strength, good chemical resistance, good thermal shock resistance, and good Electrical insulation, high relative density (3.58g·cm -3 ). MAS is widely used in metallurgy, electrochemistry, chemistry and other fields. However, pure natural Al-Mg spinel is very rare, and the Al-Mg spinel used in industry is synthesized by artificial synthesis. According to different production processes, it is divided into: sintered spinel and fused spinel. Since the electrofusion method is mainly an intermittent operation, the cooling of the pouring block causes the uneven microstructure, which is difficult to meet the indus...

AI Technical Summary

Problems solved by technology

Due to the need for a two-step calcination process, the power consumption is high, resulting in high production costs

For this reason, some new sintering methods have been tried before to shorten the sintering time or lower the sintering temperature, such as microwave sintering, vacuum sintering, spark plasma sintering, etc. However, these sintering methods require some high-end equipment, so it is difficult to produce on a large scale application

Generally speaking, the shortcomings of these solid-phase methods are that impurities are easily introduced during the preparation process, the purity of the sintered product is low, the particles are uneven, and the shape is difficult to control. In addition, the calcination temperature is high and the production cost is high.

Therefore, the design of sintering temperature control degree will significantly affect the sintering performance and microstructure uniformity of ceramics.

If the sintering temperature is too low or the sintering time is too short, the reaction cannot occur or the reaction cannot be completed; if the temperature is too high or the time is too long, the resulting product particles are likely to be coarse, and too high a temperature may cause the raw materials to evaporate or the product to decompose

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