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Home » News » Knowledge » Study on Fine Crystal Mullite Ceramics

Study on Fine Crystal Mullite Ceramics

Author:Site Editor     Publish Time: 27-07-2017      Origin:Site

Mullite is a widely used material, chemical stability to the better. In the high temperature environment, mullite creep resistance is good, excellent mechanical properties, at the same time, mullite antioxidant and corrosion resistance is also better, is the ideal high-grade refractory materials, in the traditional high-temperature structural ceramics Is widely used. In addition, the dielectric constant of mullite is low, in the high temperature environment also has good through the infrared performance, so in the field of optics and electronics mullite has also been widespread concern.

In the industry, the application is more with ordinary mullite as a raw material, the use of traditional sintering method to prepare mullite ceramics. Although the cost of this mullite relatively low, the scope of application is also very broad, but can not mullite ceramic itself unique performance is fully demonstrated, so the scope of application has yet to be expanded. The use of ... to start mullite is a more extensive use of materials, chemical stability to the better. In the high temperature environment, mullite creep resistance is good, excellent mechanical properties, at the same time, mullite antioxidant and corrosion resistance is also better, is the ideal high-grade refractory materials, in the traditional high-temperature structural ceramics Is widely used.

In addition, the dielectric constant of mullite is low, in the high temperature environment also has good through the infrared performance, so in the field of optics and electronics mullite has also been widespread concern. In the industry, the application is more with ordinary mullite as a raw material, the use of traditional sintering method to prepare mullite ceramics. Although the cost of this mullite relatively low, the scope of application is also very broad, but can not mullite ceramic itself unique performance is fully demonstrated, so the scope of application has yet to be expanded. The mullite precursor powder can be prepared by chemical synthesis method. The precursor powder has high purity and the grain size is small and uniform. The use of advanced technology can be sintered to prepare fine grain, excellent performance of mullite ceramics. In this experiment, the high purity and ultrafine mullite precursor powder was prepared by sol-gel method, and the sintering activity was high. The sparkling gel (SPS) technique was used to prepare mullite with high density and fine grain ceramics. And the mullite / TiB2 composite ceramic material was prepared by sintering to prepare TiB2 powder with good sintering activity of mullite precursor powder, which could improve the high temperature oxidation resistance of TiB2 without affecting the thermal conductivity of the ceramic itself, Conductivity.

In this paper, mordenite precursor powder was prepared by sol-gel method using TEOS (tetraethyl orthosilicate) and Al (NO3) 3 · 9H2O (aluminum nitrate hexahydrate) as raw materials, and sintered by SPS rapid sintering High density, fine grain mullite ceramic. The results show that the sintering temperature is reduced in the later stage of sintering, the defects induced by DC current are reduced, the driving force of grain growth is reduced, the grain growth is inhibited, and the density of the sample can be increased by increasing the holding time. High density, fine grain of ceramic. In this paper, through the experimental study to determine the choice of heating rate turning point of 1300 ℃, that is, after 1300 ℃ to reduce the heating rate of sintering. In the SPS sintering process, the sintering process is optimized as follows: the sintering temperature is 1400 ℃, the heating rate before the turning rate is 100 ℃ / min, the heating rate after the turning rate is 20 ℃ / min, the holding time is 20min, Pressure 80MPa, pressure temperature 1150 ℃. Using this sintering process, the mullite ceramics with fine grain and high density can be sintered to have a density of 99.55% and an average grain size of 98nm. The same time as

This paper also explored the preparation of mullite / titanium diboride composite ceramic materials. The mullite precursor powder and TiB2 powder were homogeneously mixed in a volume ratio of 3: 7. The mixed powder was sintered to 1400 ° C under Ar atmosphere in a high temperature tube furnace. It was found that the two powders were found at high temperature Under argon atmosphere does not react. The sintered molybdenum / titanium diboride powder was sintered. When the sintering temperature reached 1600 ℃, the heating rate was 100 ℃ / min, the holding time was 3min, the sintering pressure was 30MPa, Density of 99.03%, indicating that mullite precursor powder can improve the sintering activity of TiB2. The static oxidation test was carried out at 500 ℃, 800 ℃ and 1100 ℃ with the sintering temperature of 1500 ℃ and the density of 94.17% of the mullite / titanium diboride composite material. The holding time was 4h. By comparing the mass change of the sample before and after oxidation (accurate to 10-4g) and comparing with the oxidation experiment of pure TiB2 ceramics, it was found that the oxidation resistance of the composite material was improved obviously after adding mullite, especially at high temperature The effect is more obvious.


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