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CN-122007398-A - Low-potassium doped molybdenum powder and preparation method and application thereof

CN122007398ACN 122007398 ACN122007398 ACN 122007398ACN-122007398-A

Abstract

The invention belongs to the technical field of new material preparation, and discloses low-potassium doped molybdenum powder, and a preparation method and application thereof. According to the method, an atomization doping process is adopted in a molybdenum dioxide stage, potassium nitrate and lanthanum oxide cooperative doping agents are introduced, the total potassium content is controlled to be 80-98mg/kg, and gas phase transmission and grain boundary regulation and control of potassium elements are realized through a two-stage hydrogen reduction and temperature programming strategy. The method reduces energy consumption on the premise of strictly controlling the total potassium content by the compensation type atomization doping process, has the advantages of narrow distribution of the obtained molybdenum powder particles, uniform morphology and good fluidity, is superior to a product obtained by a conventional low-potassium reduction method, effectively improves the density of molybdenum blanks by compounding doped lanthanum oxide, meets the admission standard of a magnetron and a wire cutting field on high-end molybdenum wires by the qualification rate and the yield of molybdenum wire eddy current inspection, has simple process flow, does not need new special equipment, only needs to add an atomization doping unit to the existing reduction production line, has low transformation cost, and is easy to implement in a large scale.

Inventors

  • MA JIAN
  • SU YONG
  • NIU PENG
  • MENG LI
  • ZHU FENG
  • HUANG LIFENG
  • GAO FENG
  • ZHANG ZHIGUO
  • WANG WEI
  • MIAO BIN

Assignees

  • 金堆城钼业光明（山东）股份有限公司

Dates

Publication Date
20260512
Application Date
20260414

Claims (10)

  1. 1. The preparation method of the low-potassium doped molybdenum powder is characterized by comprising the following steps of: placing industrial molybdenum trioxide with the initial potassium content of 50-90mg/kg into a first-stage reduction furnace, and performing primary reduction at 450-600 ℃ in a hydrogen atmosphere to obtain molybdenum dioxide powder; Transferring the obtained molybdenum dioxide powder into a closed rotating fluidized bed doping device, and spraying a potassium nitrate solution to ensure that the total potassium content in a final molybdenum powder product is 80-98mg/kg; placing the molybdenum dioxide powder subjected to atomization doping treatment in a second stage reduction furnace, carrying out secondary addition at 850-950 ℃ under the conditions of hydrogen flow of 2-5L/min and furnace pressure of normal pressure or micro-positive pressure, and carrying out screening and impurity removal treatment on the obtained molybdenum powder to obtain a target product.
  2. 2. The method for preparing the low-potassium doped molybdenum powder according to claim 1, wherein the potassium nitrate solution adopts a potassium nitrate aqueous solution with the concentration of 0.5-2.0g/L, is uniformly sprayed on the surface of molybdenum dioxide powder in an atomized form through a pressure nozzle, and lanthanum oxide micro powder is dissolved in the potassium nitrate solution in advance, and the adding amount of the lanthanum oxide micro powder is 0.05-0.20wt% based on the mass of the molybdenum dioxide.
  3. 3. The method for preparing the low-potassium doped molybdenum powder according to claim 1, wherein a central air inlet pipe and an annular atomizing nozzle array are arranged in the closed rotary fluidized bed doping device, the molybdenum dioxide powder is in a suspension fluidization state under the driving of nitrogen or argon carrier gas, the potassium nitrate-lanthanum oxide mixed solution is conveyed to the atomizing nozzle by a high-pressure pump, and an atomized cloud with the liquid drop diameter of 10-50 μm is formed under the pressure of 0.2-0.5 MPa.
  4. 4. The method for preparing the low-potassium doped molybdenum powder according to claim 1, wherein a temperature programming strategy is adopted in the second stage of reduction, wherein the temperature is raised to 600 ℃ from room temperature at a rate of 5-10 ℃ per minute and kept for 30-60 minutes, so that potassium nitrate is thermally decomposed to generate potassium oxide, and then the temperature is continuously raised to 850-950 ℃ and kept for 2-4 hours, so that the potassium is transferred to the surface of the nascent molybdenum particles in the form of K 2 O (g) or KO 2 (g) through gas phase transmission and is dynamically adsorbed at a grain boundary position.
  5. 5. The method for preparing the low-potassium doped molybdenum powder according to claim 1, wherein the first stage reduction furnace and the second stage reduction furnace are a 1 st tube, a 2 nd tube and a3 rd tube, a3 nd tube of a four-tube parallel horizontal resistance heating furnace, the inner diameter of each tube is 80-120mm, and the length of an effective heating zone is 1500-2000mm.
  6. 6. The method for preparing the low-potassium doped molybdenum powder according to claim 2, wherein the potassium nitrate solution further contains ammonium fluoride with a concentration of 0.01-0.05g/L, and the solution is used for generating HF gas in situ in a 600 ℃ heat preservation stage to etch oxide films on the surfaces of molybdenum particles.
  7. 7. The method for preparing the low-potassium doped molybdenum powder according to claim 1, wherein after the atomization doping is completed, the material is dried for 1-2 hours at 60-80 ℃ to reduce the water content of the powder to below 0.1 wt%.
  8. 8. The molybdenum powder produced by the production method of low-potassium doped molybdenum powder according to claim 1, wherein the molybdenum powder has a fermi of 4.0-6.5 μm, a bulk density of 0.8-1.2g/cm 3 , a tap density of 2.0-2.5g/cm 3 , a sieving rate of 95% or more, a total potassium content of 80-98mg/kg, a lanthanum content of 400-1600mg/kg, and a total impurity element Fe, ni, cu, na of less than 50mg/kg.
  9. 9. The use of the molybdenum powder according to claim 8 for the preparation of molybdenum wire for magnetron cathode support, wherein the molybdenum powder is cold isostatic pressed into a cylindrical billet at a pressing pressure of 150-200MPa, then sintered in a hydrogen atmosphere of 1800-2000 ℃ for 2-3 hours to obtain a sintered molybdenum billet, and then hot rolled, warm rolled and intermediate annealed to draw the molybdenum wire.
  10. 10. The use according to claim 9, wherein the intermediate annealing is carried out in a pure hydrogen atmosphere at 1100-1300 ℃ for 30-60 minutes.

Description

Low-potassium doped molybdenum powder and preparation method and application thereof Technical Field The invention belongs to the technical field of new material preparation, and relates to low-potassium doped molybdenum powder, and a preparation method and application thereof. Background Molybdenum and its alloys have an irreplaceable position in the fields of electronics, vacuum devices and precision machining, especially in high-end applications such as magnetron cathode supports and high-precision wire-cut molybdenum wires, due to their excellent high temperature strength, good thermal and electrical conductivity, and low thermal expansion coefficients. The grain size distribution, apparent density, grain morphology and impurity element content of the molybdenum powder as the precursor raw material directly determine the densification behavior of the subsequent sintered blank and the process yield of the final product. The traditional industrial molybdenum powder is prepared by adopting molybdenum trioxide through a two-stage hydrogen reduction method, namely, firstly reducing the molybdenum trioxide into molybdenum dioxide at 450-600 ℃ and then further reducing the molybdenum dioxide into metallic molybdenum powder at 900-1100 ℃. In the process, trace potassium elements are often intentionally introduced to regulate grain growth and inhibit sintering shrinkage, the typical doping amount is controlled in the range of 100-300mg/kg, and a dynamic adsorption layer is formed on the surface of molybdenum particles by the vapor migration effect of potassium at high temperature, so that the rapid migration of grain boundaries is effectively prevented, and thus, coarse, loose and spherical or spheroidal molybdenum powder with good fluidity is obtained. However, with the continuous rise of the material purity requirements of high-end electronic devices, low-potassium raw materials (K <100 mg/kg) are becoming a new trend in the industry to avoid potential impact of potassium residues on the vacuum performance and long-term stability of the devices. However, when the low-potassium molybdenum trioxide is directly used for conventional two-stage hydrogen reduction, the vapor phase transmission catalysis mechanism cannot be effectively activated due to the lack of enough potassium vapor pressure in the system, so that the surface energy of molybdenum particles in the reduction process is too high, local fusion adhesion and compact hardening are extremely easy to occur, the obtained molybdenum powder is fine in granularity and low in loose ratio, and has serious agglomeration and morphology non-uniformity, and the sieving rate is remarkably reduced. Meanwhile, the structural defects are difficult to completely eliminate in the subsequent powder metallurgy process, namely micro holes and stress concentration areas exist in the molybdenum blank obtained by pressing and sintering, macroscopic defects such as hollow wires, brittle fracture, surface bamboo-like burrs and the like are induced in the rolling and stretching processes, so that the eddy current flaw detection qualification rate and the yield are low, and the flaw detection standard of molybdenum wires for magnetrons which are more than or equal to 95% and the requirement of linear cutting molybdenum wires on continuous processing stability can not be met. If the potassium salt is directly doped in the molybdenum trioxide stage, the molybdenum trioxide is subjected to violent sublimation in a low-temperature stage, so that the dopant is unevenly distributed and even volatilized to be lost, and the ingredient fluctuation and the process uncontrollability are aggravated. Disclosure of Invention In order to achieve the aim of the invention, the invention provides low-potassium doped molybdenum powder, and a preparation method and application thereof. Aiming at the problems of serious molybdenum powder agglomeration, uneven morphology, low apparent density and degradation of subsequent deep processing performance caused by the lack of an effective grain regulation mechanism in the conventional hydrogen reduction process of low-potassium molybdenum trioxide in the prior art, the method is used for realizing the precise regulation and control of the microstructure and macroscopic performance of molybdenum powder on the premise that the total potassium content of raw materials is lower than 100mg/kg by constructing a compensation type atomization doping process, introducing a precisely metered potassium nitrate solution in a molybdenum dioxide intermediate product stage and combining lanthanum oxide as a cooperative doping agent to reconstruct the space-time distribution and action path of potassium elements in the reduction process. The preparation method of the low-potassium doped molybdenum powder comprises the steps of firstly placing industrial molybdenum trioxide in a first stage reduction furnace, primarily reducing the industrial molybdenum trioxide at 450-600