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Method for preparing ultra-fine crystal grain pure molybdenum block material

A block material, ultra-fine grain technology, applied in the field of high melting point metals and metal-based heat sink materials, can solve the problem of reducing the thermal conductivity of molybdenum, to avoid grain growth, good mechanical properties, shorten sintering time Effect

Inactive Publication Date: 2009-09-09
UNIV OF SCI & TECH BEIJING
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The addition of these additives tends to reduce the thermal conductivity of molybdenum

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0012] Example 1: Preparation of a pure molybdenum bulk material with a molybdenum grain size of 90 nm.

[0013] First granulate the molybdenum powder with a particle size of 90nm, put it into a graphite abrasive tool, and put it under 30MPa and a vacuum degree of 10 -2 Pa, the temperature is 800°C, and the time is 30 minutes, the vacuum hot pressing is pre-fired. The pre-fired green body is machined into a certain size and put into a pyrophyllite mold, and sintered at 8GPa with an input power of 23kW AC, and the sintering time is 1 minute. After the obtained sample is ground and polished, the measured density is 9.85g / cm 3 , the relative density is 96.5%, the micro-Vickers hardness is 765HV, and the bending strength is 996MPa.

Embodiment 2

[0014] Example 2: Preparation of a pure molybdenum bulk material with a molybdenum grain size of 2 μm.

[0015] Put the molybdenum powder with a particle size of 2 μm into the graphite grinding tool, at 30MPa, in a vacuum of 10 -2 Pa, the temperature is 1000°C, and the time is 60 minutes, the vacuum hot pressing pre-fires. The pre-fired green body is machined into a certain size and put into a pyrophyllite mold, and sintered at 8GPa with an input power of 23kW AC, and the sintering time is 1 minute. After the obtained sample is ground and polished, the measured density is 10.06g / cm 3 , the relative density is 98.6%, the micro-Vickers hardness is 540HV, and the bending strength is 571MPa

Embodiment 3

[0016] Example 3: Preparation of a high-strength pure molybdenum bulk material with a grain size of molybdenum of 2 μm.

[0017] Put the molybdenum powder with a particle size of 2 μm into the graphite grinding tool, at 50MPa, in a vacuum of 10 -2 Pa, the temperature is 1000°C, and the time is 60 minutes, the vacuum hot pressing pre-fires. The pre-fired body was put into a pyrophyllite mold, and sintered at 3GPa, with an input power of 23kW AC, and the sintering time was 1 minute. After the obtained sample was ground and polished, the measured density was 9.91g / cm 3 , the relative density is 97.2%, the micro-Vickers hardness is 550HV, and the bending strength is 1035MPa

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Abstract

A method for preparing ultra-fine crystal grain pure molybdenum block material belongs to the technical field of high-melting-point metal and metal-based heat sink material. The invention is characterized in that firstly the molybdenum powder with granularity which is smaller than 10mum and larger than 1mum is selected for executing the vacuum hot pressing pre-burning of green body. Then the pre-burned green body is placed in a pyrauxite mold and is placed into a press for exerting pressure of 1-10GPa on the sample. Then the 10-25 kW alternating current is exerted on two ends of the sample for sintering. The energized current is 1000A-3000A and lasts for 15 seconds to 3 minutes. After energizing and sintering, pressure is continuously maintained for 30 seconds to 3 minutes; then the sintered body is milled and polished. The relative density is 96-99.9% and the grain size is smaller than or equal to the initial powder size of used raw material. The pre-burning is executed under the following conditions: 20-50MPa of pressure, 10<-2>-10<-3>Pa of vacuum degree, 800-1000 DEG C of temperature and 30min-60min of time. The ultra-fine crystal grain pure molybdenum block material prepared by the invention has better mechanical performance and thermal-shock resistance and is suitable for electronic packaging materials, hot sink materials, electrical contact materials and fire-resistant plasma scouring components, such as divertor materials in nuclear fusion devices.

Description

technical field [0001] The invention belongs to the technical field of high-melting-point metals and metal-based heat sink materials, and in particular provides a preparation method of ultrafine-grained pure molybdenum block materials. Background technique [0002] Pure molybdenum has the advantages of high melting point, high strength, high hardness and high wear resistance. In addition, it has a small thermal expansion coefficient, good corrosion resistance and oxidation resistance, and good electrical and thermal conductivity. Therefore, it is used in cutting-edge scientific fields, defense industries and It has been widely used in civil industry. For example, it is used as counterweight and shock-absorbing materials on gyro rotors and aircrafts, as armor-piercing projectiles and submunitions in military industry, as anti-X-ray shielding materials in medical industry, and as high-density alloys on mobile phones in civil industry. Vibrator electrode materials, etc. [00...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B22F3/12
Inventor 周张健马垚都娟
Owner UNIV OF SCI & TECH BEIJING
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