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A kind of Si-doped modified moalb ceramics and preparation method thereof

A ceramic and modification technology, which is applied in the field of Si-doped modified MoAlB ceramics and its preparation, can solve the problems of restricting the application and promotion of structural materials, endangering the mechanical properties of bulk materials, and poor overall toughness of bulk materials, and achieve high hardness and flexural strength, grain refinement, simple method

Active Publication Date: 2022-04-22
XI AN JIAOTONG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0003] However, although MoAlB ceramics have broad application prospects, the problems of low strength and poor toughness greatly limit its application and promotion as structural materials.
The reason is that MoB exists in MoAlB ceramics 2 、Al 8 Mo 3 and other impurities, which greatly endanger the mechanical properties of the bulk material; in addition, the toughness and strength of MoAlB ceramics are low, resulting in poor overall toughness of the bulk material

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  • A kind of Si-doped modified moalb ceramics and preparation method thereof

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preparation example Construction

[0028] The present invention is a kind of Si-doped modified MoAlB ceramics and its preparation method, the Si-doped modified MoAlB ceramics with excellent performance is obtained after the raw materials are ball-milled and sintered, comprising the following steps:

[0029] S1, mixing

[0030] Be that the ratio of 107:(1.4~4.2):35 is 107:(1.4~4.2):35 by weighing the MoB powder that purity is 99.9%, the Al powder that purity is 99.9%, the Si powder that purity is 99.9%, the particle size of MoB powder is 0.1~50 μm, The particle size of the Al powder is 5-50 μm, and the particle size of the Si powder is 0.1-50 μm. The weighed MoB powder is mixed with the Al powder and stored in a vacuum environment to prevent oxidation, and the weighed Si powder is stored in a vacuum environment for future use.

[0031] S2, a ball mill

[0032] Before ball milling, vacuumize the ball mill tank, dry mix the mixed MoB powder and Al powder, that is, one ball mill, the mass ratio of agate balls to ...

Embodiment 1

[0043] Weigh 50g of MoB powder, Si powder, and Al powder according to the mass ratio of 107:1.4:35, mix the MoB powder and Al powder, and perform ball milling. The mass ratio of the ball and the powder is 3:1, and the ball milling time is 40h. The ball milling speed is 200r / min. After the ball milling, Si powder was added, and a second ball milling was carried out. The ball milling time was 10 h, and the ball milling speed was 150 r / min. After the ball milling, heat preservation was carried out at a high temperature, the heating rate was 10°C / min, the heat preservation temperature was 300°C, and the heat preservation time was 60 minutes. Finally, hot pressing sintering is carried out, and the vacuum degree is always kept at 10 -2 Below Pa. The sintering pressure is 20MPa, the sintering temperature is 1200°C, the heating rate between 600°C and 700°C is 2°C / min, and the rest time is 30°C / min. After the temperature reaches 1200°C, keep it warm for 2 hours. Then it was cooled ...

Embodiment 2

[0046] Weigh 50g of MoB powder, Si powder, and Al powder according to the mass ratio of 107:2.8:35, mix the MoB powder and Al powder, and perform ball milling. The mass ratio of the ball and the powder is 5:1, and the ball milling time is 50h. The ball milling speed is 180r / min. After the ball milling, Si powder was added, and a second ball milling was carried out. The ball milling time was 10 h, and the ball milling speed was 120 r / min. Carry out high-temperature heat preservation after the ball milling is finished, the heating rate is 8°C / min, the heat preservation temperature is 300°C, and the heat preservation time is 50min. Finally, hot pressing sintering is carried out, and the vacuum degree is always kept at 10 -2 Below Pa. The sintering pressure is 30MPa, the sintering temperature is 1200°C, the heating rate between 600°C and 700°C is 2°C / min, and the rest time is 30°C / min. After the temperature reaches 1200°C, keep it warm for 2 hours. Then it was cooled to room t...

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Abstract

The invention discloses a Si-doped modified MoAlB ceramic and a preparation method thereof. High-purity MoB powder, Al powder, and Si powder are mixed according to a certain ratio and in a certain order, and then ball milled twice, and after the ball milling is completed, the powder is placed in a tube furnace. Carry out high-temperature heat preservation to remove impurities, and then use a high-temperature sintering furnace to carry out vacuum hot-pressing sintering after the heat preservation is completed. After the sintering is completed, it is cooled to room temperature with the furnace to obtain Si-doped modified MoAlB ceramics. The MoAlB ceramic prepared by the invention has smaller crystal grains and higher mechanical properties, such as high fracture toughness, high hardness, high bending strength and the like.

Description

technical field [0001] The invention belongs to the technical field of cermets, and in particular relates to a Si-doped modified MoAlB ceramic and a preparation method thereof. Background technique [0002] MoAlB is a MAX-like ternary boride ceramic, which is composed of MoB atomic layers and Al atomic layers alternately laminated. Previous studies have shown that thanks to its unique crystal structure, MoAlB ceramics not only have high electrical conductivity and thermal conductivity similar to metals, but also exhibit high hardness, high temperature oxidation resistance, thermal shock resistance and ablation resistance similar to ceramics. Such high-temperature mechanical properties are expected to be applied to high-temperature resistant and wear-resistant parts inside aviation and aerospace engines. [0003] However, although MoAlB ceramics have broad application prospects, the problems of low strength and poor toughness greatly limit its application and promotion as st...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C04B35/58C04B35/622C04B35/63C04B35/645
CPCC04B35/5805C04B35/622C04B35/6303C04B35/645C04B2235/3813C04B2235/402C04B2235/428C04B2235/656C04B2235/6562C04B2235/6567C04B2235/6581C04B2235/786C04B2235/96
Inventor 皇志富孔寒冰坚永鑫宁海玥
Owner XI AN JIAOTONG UNIV