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Low-temperature method for manufacturing nano-MgO crystal whisker

A whisker and nano technology is applied in the field of low-temperature preparation of nano-MgO whiskers, which can solve the problem of requiring a long time and achieve the effect of increasing the stay.

Inactive Publication Date: 2008-07-16
TIANJIN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0006] But the problem that the above-mentioned technology exists is: the formation of Mg vapor needs to pass MgB 2 The thermal decomposition is achieved, while MgB 2 The decomposition temperature of MgO is higher than 750°C, and it needs a long time of heat preservation treatment to react with oxygen to form enough MgO saturated vapor pressure to grow MgO whiskers.

Method used

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  • Low-temperature method for manufacturing nano-MgO crystal whisker
  • Low-temperature method for manufacturing nano-MgO crystal whisker
  • Low-temperature method for manufacturing nano-MgO crystal whisker

Examples

Experimental program
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Effect test

Embodiment 1

[0023] Mix the magnesium powder with a purity of 99.5% and the amorphous boron powder with a purity of 99% according to the atomic ratio of Mg:B=1:2, and grind them in an agate mortar for 120 minutes to make them fully mixed. Mix the powder with a press at 5kg / cm 3 Press it into a sintered block under a certain pressure and put it into a BN crucible, then put the crucible vertically into the heating zone of the vacuum tube furnace, then seal the tube furnace and vacuumize it to 1Pa, then fill it with 5% oxygen The argon gas is used, and the flow rate of the mixed gas is controlled at 5 lit. / min. Finally, set the temperature program, heat the sample to 750°C at a heating rate of 5K / min, and immediately lower it to room temperature at the same rate without heat preservation treatment. 2 Nano-MgO whiskers are generated on the grain surface as shown in Figure 1, and the generated nano-MgO whiskers are scattered as shown in Figure 3.

Embodiment 2

[0025] The analytically pure magnesium powder and the amorphous analytically pure boron powder were mixed according to the atomic ratio of Mg:B=1.2:2, and ground in a corundum mortar for 60 minutes to make them fully mixed. Mix the powder with a press at 8kg / cm 3 Press it into a sintered block under a certain pressure and put it into a corundum crucible, then put the crucible into the heating zone of the vacuum tube furnace, then seal the tube furnace and evacuate it to 5Pa, then fill it with argon gas mixed with 3% oxygen , the mixed gas flow rate is controlled at 10lit. / min. Finally, set the temperature program, heat the sample to 720°C at a heating rate of 10K / min, keep it for 30 minutes, and then lower it to room temperature at the same rate. 2 Linear nano-MgO whiskers are generated on the grain surface, as shown in Figure 4.

Embodiment 3

[0027] The analytically pure magnesium powder and the amorphous analytically pure boron powder were mixed according to the atomic ratio of Mg:B=1.5:2, and ground in an agate mortar for 120 minutes to make them fully mixed. Mix the powder with a press at 10kg / cm 3 Press it into a sintered block under a certain pressure and put it into a graphite crucible, then put the crucible into the heating zone of the vacuum tube furnace, then seal the tube furnace and evacuate it to 10Pa, then fill it with argon gas mixed with 2% oxygen , the mixed gas flow rate is controlled at 20 liters / min. Finally, the temperature program was set, and the sample was heated to 650 °C at a heating rate of 20 K / min, then kept for 120 min, and then lowered to room temperature at the same rate, and rod-shaped nano-MgO whiskers could be formed on the surface of the sample, as shown in Figure 5.

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Abstract

The invention relates to a method for preparing nanometer MgO whiskers at the low temperature and the method is that magnesium powders and amorphous boron powders are mixed according to atomic ratio of MG:B being equal to 1 to 1.5:2 and the mixture is grinded for 30 to 120 minutes for thorough mixing, and after the mixed powders are made into a lump sinter under the pressure of 5 to 10 kg / cm<3> by a press machine, the lump sinter is put into a crucible which is put into a heating zone of an evacuated tubular furnace. The evacuated tubular furnace is sealed, vacuumized to 1 to 10 Pa and filled with argon the oxygen content of which is 2 percent to 5 percent and the flow rate of the mixed gas is 5 to 20 lit. per minute to heat the sample up to 650 to 750 DEG C at the heating rate of 5 to 20 K per minute, and the sample is decreased to the room temperature at the same heating rate after the temperature is kept for 0 to 120 minutes. The surface of the sample forms nanometer MgO whiskers with various appearances and sizes. When reaching 650 DEG C, magnesium evaporates and reacts with the little filled oxygen to produce MgO vapour, and under the lower over-saturation state, MgO whiskers are deposited on a substrate. The method for preparing MgO whiskers needs temperature much lower than the previous and greatly increases the practicality of preparing MgO whiskers.

Description

technical field [0001] The invention belongs to the technical field of composite materials, in particular to a low-temperature preparation method of nanometer MgO whiskers. Background technique [0002] As a very important material, magnesium oxide (MgO) is widely used as catalyst, toxic substance adsorbent and additive for refractory materials, coatings and superconducting materials. In addition, as a typical wide-band (gap) insulator, the electronic and optical properties of MgO bulk materials have received extensive attention and have been continuously studied in depth. [0003] Recently, MgO one-dimensional nanostructured materials have attracted much attention due to their unique properties and applications in optics, magnetism, superconductivity and ferroelectric phenomena. As a kind of one-dimensional nanostructure, MgO whisker not only has the above characteristics, but also has the advantages of high melting point (2850°C), high strength and high elastic modulu...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C30B29/62C30B29/16C30B25/00
Inventor 刘永长史庆志马宗青
Owner TIANJIN UNIV
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