CN103601207A

CN103601207A - Preparation method of high-purity and high-density YbB6 polycrystalline bulk cathode material

Info

Publication number: CN103601207A
Application number: CN201310557794.7A
Authority: CN
Inventors: 张忻; 梁超龙; 张繁星; 郑亮; 王杨; 刘洪亮; 李松浩; 张久兴
Original assignee: Beijing University of Technology
Current assignee: Beijing University of Technology
Priority date: 2013-11-12
Filing date: 2013-11-12
Publication date: 2014-02-26

Abstract

A method for preparing a high-purity and high-density _YbB6 polycrystalline bulk cathode material belongs to the technical field of rare earth hexaboride polycrystalline cathode materials. At present, YbB ₆ polycrystalline block is usually prepared by hot pressing sintering method, but the hot pressing sintering method has a high sintering temperature (1900-2100°C), high requirements on the mold, and the sintered phase is impure, which limits the YbB ₆ polycrystalline block. body application. The method of the present invention has low sintering temperature, short time and simple process, and the prepared YbB ₆ polycrystalline bulk cathode material has high density, the relative density can reach more than 98%, and the Vickers hardness can reach 2670Kg/mm ² at the highest. Ray diffraction analysis shows a single hexaboride phase.

Description

High purity high dense YbB 6the preparation method of polycrystalline bulk cathode material

Technical field

The invention belongs to rare-earth hexboride compound polycrystalline cathode material technical field, be specifically related to a kind of employing Preparation of Nano-powder by Evaporation-condensation Method be combined with discharge plasma sintering (SPS) technology preparation YbB ₆the method of polycrystalline bulk.

Background technology

Rare-earth boride YbB ₆have that work function is low, fusing point is high, hardness is large, chemical stability is high, emission is large, the feature such as resistance to ion bombardment, anti-toxic are good, can be used for the plurality of devices such as plasma source, electron beam exposure apparatus, electron beam welding machine, have broad application prospects.

At present, conventionally adopt hot pressing sintering method to prepare YbB ₆polycrystalline bulk, and the sintering temperature of hot pressing sintering method high (1900-2100 ℃), high to mould requirement, and sintering is mutually impure, has limited YbB ₆the application of polycrystalline bulk.

Summary of the invention

The object of the invention is to solve the problem of prior art, and a kind of high purity high dense rare-earth boride YbB is provided ₆cathode material and preparation method thereof.Method sintering temperature provided by the present invention is low, the time is short, and technique is simple, and can reduce preparation cost, is conducive to large-scale commercial production and application.

The present invention adopts evaporative condenser to send out to prepare the method that nano-powder is combined with discharge plasma sintering (SPS) technology to prepare rare-earth boride YbB ₆cathode material, concrete steps are as follows:

1) adopt direct current arc evaporation condensing plant, equipment is first evacuated to 2 * 10 ^-2below pa, pass into afterwards argon gas, air pressure is 0.05MPa; The simple substance rare earth metal y b piece of take is anode, and tungsten is negative electrode, reaction current 120～150A, and response voltage is 30～40V, the reaction times is 50～60min, preparation Yb nanometer powder;

By Yb nanometer powder and B powder in oxygen level lower than 8.0 * 10 ^-5in argon gas atmosphere below mg/L, 1: 6 in molar ratio, after being ground, pack in graphite jig;

Or adopt direct current arc evaporation condensing plant, equipment is first evacuated to 2 * 10 ^-2below pa, pass into afterwards argon gas and hydrogen gas mixture, argon gas and hydrogen volume ratio are 1: 1, and total gas pressure is 0.05MPa; The simple substance rare earth metal y b piece of take is anode, and tungsten is negative electrode, reaction current 120～150A, and response voltage is 30～40V, the reaction times is 50～60min, preparation YbH ₂nanometer powder;

By YbH ₂nanometer powder and B powder in oxygen level lower than 8.0 * 10 ^-5in argon gas atmosphere below mg/L, 1: 6 in molar ratio, after being ground, pack in graphite jig;

2) mould is placed in to SPS sintering cavity, apply the axle pressure of 30～60MPa, total gas pressure lower than the vacuum condition of 10Pa under sintering, temperature rise rate with 80～150 ℃/min heats up, sintering temperature is 1350～1450 ℃, insulation 5～10min, cools to room temperature with the furnace, obtains rare-earth boride YbB ₆cathode material.

Compared with prior art, the present invention has following beneficial effect:

The inventive method sintering temperature is low, the time is short, and technique is simple, prepared YbB ₆polycrystalline bulk cathode material density is high, and relative density reaches as high as more than 98%, and Vickers' hardness is at 2500Kg/mm ²above, through X-ray diffraction analysis, be single hexaboride phase.

Accompanying drawing explanation

Fig. 1 uses the YbB of Yb nanometer powder and B powder preparation by present method ₆the X-ray spectrogram of block sample, phase consists of single YbB ₆crystalline phase.

Fig. 2 is by present method YbH ₂the YbB of nanometer powder and B powder preparation ₆the X-ray spectrogram of block sample, phase consists of single YbB ₆crystalline phase.

Below in conjunction with the drawings and specific embodiments, the invention will be further described, but protection scope of the present invention is not limited to following embodiment.

Embodiment

Embodiment 1

1) adopt direct current arc evaporation condensing plant, equipment is first evacuated to 2 * 10 ^-2below pa, pass into afterwards argon gas, air pressure is 0.05MPa.The simple substance rare earth metal y b piece of take is anode, and tungsten is negative electrode, reaction current 120A, and response voltage is 30V, the reaction times is 50min, preparation Yb nanometer powder;

2) by Yb nanometer powder and B powder in oxygen level lower than 8.0 * 10 ^-5in argon gas atmosphere below mg/L, 1: 6 in molar ratio, after being ground, pack in graphite jig;

3) mould is placed in to SPS sintering cavity, applies the axle pressure of 30MPa, sintering under the vacuum condition that is 9Pa at air pressure, temperature rise rate with 100 ℃/min heats up, and sintering temperature is 1350 ℃, insulation 5min, cool to room temperature with the furnace, obtain phase and consist of YbB ₆single-phase polycrystalline bulk cathode material, its relative density is more than 96.1%, Vickers' hardness is 2590Kg/mm ².

Embodiment 2

1) adopt direct current arc evaporation condensing plant, equipment is first evacuated to 2 * 10 ^-2below pa, pass into afterwards argon gas, air pressure is 0.05MPa.The simple substance rare earth metal y b piece of take is anode, and tungsten is negative electrode, reaction current 130A, and response voltage is 35V, the reaction times is 55min, preparation Yb nanometer powder;

3) mould is placed in to SPS sintering cavity, applies the axle pressure of 40MPa, sintering under the vacuum condition that is 5Pa at total gas pressure, temperature rise rate with 110 ℃/min heats up, and sintering temperature is 1400 ℃, insulation 7min, cool to room temperature with the furnace, obtain phase and consist of YbB ₆single-phase polycrystalline bulk cathode material, its relative density is more than 98.0%, Vickers' hardness is 2670Kg/mm ².

Embodiment 3

1) adopt direct current arc evaporation condensing plant, equipment is first evacuated to 2 * 10 ^-2below pa, pass into afterwards argon, hydrogen mixed gas, ratio is 1: 1, and total gas pressure is 0.05MPa.The simple substance rare earth metal y b piece of take is anode, and tungsten is negative electrode, reaction current 150A, and response voltage is 40V, the reaction times is 60min, preparation YbH ₂nanometer powder;

2) by YbH ₂nanometer powder and B powder in oxygen level lower than 8.0 * 10 ^-5in argon gas atmosphere below mg/L, 1: 6 in molar ratio, after being ground, pack in graphite jig;

3) mould is placed in to SPS sintering cavity, applies the axle pressure of 30MPa, sintering under the vacuum condition that is 9Pa at air pressure, temperature rise rate with 100 ℃/min heats up, and sintering temperature is 1350 ℃, insulation 5min, cool to room temperature with the furnace, obtain phase and consist of YbB ₆single-phase polycrystalline bulk cathode material, its relative density is more than 95.9%, Vickers' hardness is 2580Kg/mm ².

Embodiment 4

1) adopt direct current arc evaporation condensing plant, equipment is first evacuated to 2 * 10 ^-2below pa, pass into afterwards argon, hydrogen mixed gas, ratio is 1: 1, and total gas pressure is 0.05MPa.The simple substance rare earth metal y b piece of take is anode, and tungsten is negative electrode, reaction current 150A, and response voltage is 40V, the reaction times is 50min, preparation YbH ₂nanometer powder;

3) mould is placed in to SPS sintering cavity, applies the axle pressure of 40MPa, sintering under the vacuum condition that is 5Pa at total gas pressure, temperature rise rate with 110 ℃/min heats up, and sintering temperature is 1400 ℃, insulation 7min, cool to room temperature with the furnace, obtain phase and consist of YbB ₆single-phase polycrystalline bulk cathode material, its relative density is more than 97.5%, Vickers' hardness is 2636Kg/mm ².

Claims

1. The preparation method of high-purity and high-density _YbB6 polycrystalline bulk cathode material is characterized in that, comprising the following steps:

1) DC arc evaporation and condensation equipment is used. The equipment is first evacuated to below 2×10 ^-2 Pa, and then argon gas is introduced at a pressure of 0.05MPa; the elemental rare earth metal Yb block is used as the anode, and the metal tungsten is used as the cathode, and the reaction current is 120 ～150A, the reaction voltage is 30～40V, the reaction time is 50～60min, to prepare Yb nano powder;

Yb nano powder and B powder are ground and mixed in an argon atmosphere with an oxygen content of less than 8.0×10 ^-5 mg/L at a molar ratio of 1:6, and then put into a graphite mold;

Or use DC arc evaporation and condensation equipment. The equipment is first evacuated to below 2×10 ^-2 Pa, and then the mixed gas of argon and hydrogen is introduced. The volume ratio of argon and hydrogen is 1:1, and the total pressure is 0.05MPa; The rare earth metal Yb block is used as the anode, the metal tungsten is used as the cathode, the reaction current is 120-150A, the reaction voltage is 30-40V, and the reaction time is 50-60min to prepare YbH ₂ nanometer powder;

YbH ₂ nano powder and B powder are ground and mixed in an argon atmosphere with an oxygen content of less than 8.0×10 ^-5 mg/L at a molar ratio of 1:6, and then put into a graphite mold;

2) Place the mold in the SPS sintering cavity, apply an axial pressure of 30-60 MPa, sinter under vacuum conditions with a total air pressure lower than 10 Pa, heat up at a heating rate of 80-150°C/min, and the sintering temperature is 1350- 1450°C, keep warm for 5-10 minutes, and cool down to room temperature with the furnace to obtain the rare earth boride YbB ₆ cathode material.