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CN-121992373-A - Silver-coated copper powder based on fluidized bed chemical vapor deposition and preparation method thereof

CN121992373ACN 121992373 ACN121992373 ACN 121992373ACN-121992373-A

Abstract

The invention relates to the technical field of metal composite material preparation, and particularly discloses silver-coated copper powder based on fluidized bed chemical vapor deposition and a preparation method thereof, wherein the silver-coated copper powder comprises the steps of in-situ reduction of copper powder, namely in-situ reduction and activation of copper powder in a fluidized bed reactor to reduce the oxygen content of the copper powder to below 500ppm, so as to obtain a clean surface; and (3) silver layer vapor deposition coating, namely introducing a gaseous silver precursor into a fluidized bed reactor, and controlling the deposition rate to realize uniform and compact coating of silver on the copper powder surface in a fluidized state. The method is a full gas phase process, and the generation of waste water is radically stopped. The silver-coated copper powder prepared by the method has the characteristics of continuous and compact silver layer, clean interface and excellent oxidation resistance, is particularly suitable for preparing high-performance and low-cost photovoltaic conductive paste, and effectively promotes the cost reduction and efficiency improvement of the photovoltaic industry.

Inventors

  • HAN JING
  • YIN ZHICHANG
  • WEI LI
  • XIA FAN
  • Yang Deman
  • BAI HAOLONG

Assignees

  • 苏州纽姆特纳米科技有限公司

Dates

Publication Date
20260508
Application Date
20260204

Claims (8)

  1. 1. The preparation method of the silver-coated copper powder based on fluidized bed chemical vapor deposition is characterized by comprising the following steps of: S1, copper powder in-situ reduction, namely introducing pretreated copper powder with the average particle diameter D50 of 0.5-5 mu m into a fluidized bed reactor, replacing air in the fluidized bed reactor with carrier gas, heating the fluidized bed reactor to 300-500 ℃ in the carrier gas atmosphere, introducing a mixture of reducing gas and carrier gas for reduction reaction, reducing the oxygen content in the copper powder to below 500ppm, and ending the reduction reaction; s2, silver layer vapor deposition coating, namely after S1 is finished, continuously maintaining the copper powder in a fluidized state in a carrier gas atmosphere, adjusting the temperature of a fluidized bed reactor to 90-190 ℃, introducing a gaseous silver precursor into the fluidized bed reactor to enable the gaseous silver precursor to contact and react with copper powder in the fluidized state, stopping supplying the gaseous silver precursor, heating the fluidized bed reactor to 250-350 ℃, maintaining the fluidized state for 30-60 min in the carrier gas atmosphere, depositing a silver layer on the surface of the copper powder, and finally forming silver-coated copper powder.
  2. 2. The preparation method of the silver-coated copper powder based on the fluidized bed chemical vapor deposition of claim 1, wherein the gaseous silver precursor is any one of gasified silver trimethylphosphonoacetate, (1, 5-cyclooctadiene) (hexafluoroacetylacetone) silver and beta-diketone silver complex, the gaseous silver precursor and carrier gas are mixed and then conveyed together, in the conveying process, the conveying environment temperature of the gaseous silver precursor is the same as the gasification temperature, the volume flow ratio of the carrier gas to the gaseous silver precursor is 1:20-1:2, and the carrier gas is any one of nitrogen, argon and helium.
  3. 3. The method for preparing silver-coated copper powder based on fluidized bed chemical vapor deposition according to claim 2, wherein the volume ratio of the reducing gas in the mixed gas of the reducing gas and the carrier gas is not less than 10%, and the reducing gas is any one of hydrogen, carbon monoxide, hydrogen sulfide, methane and sulfur monoxide.
  4. 4. The method for preparing silver-coated copper powder based on fluidized bed chemical vapor deposition according to claim 1, wherein in S1, the gas velocity of the mixed gas of the reducing gas and the carrier gas is 0.2-3 Umf, and in S2, the deposition rate of the gaseous silver precursor is 2.0-10 nm/min.
  5. 5. The method for preparing silver-coated copper powder based on fluidized bed chemical vapor deposition according to claim 1, wherein after S2 is finished, the formed silver-coated copper powder is in a fluidized state in a carrier gas atmosphere, the constant temperature time is not less than 30 minutes, and the gas velocity is 0.2-0.5 Ut.
  6. 6. The preparation method of the silver-coated copper powder based on the fluidized bed chemical vapor deposition according to claim 1, wherein the copper powder in S1 is pretreated by washing with an organic acid and vacuum drying, the pretreatment steps comprise 1) taking spherical or nearly spherical copper powder with an average particle size D50 of 0.5-5 mu m, the purity is more than or equal to 99.9%, 2) washing the copper powder in the step 1) with a rare organic acid solution with the concentration of 1% -5%, then washing with deionized water, and finally vacuum drying, wherein the rare organic acid solution is any one of acetic acid, formic acid, oxalic acid and citric acid.
  7. 7. The silver-coated copper powder prepared by the preparation method based on fluidized bed chemical vapor deposition of any one of claims 1 to 6 is characterized by comprising a copper core and a silver layer coated on the copper core, wherein the thickness of the silver layer is 50-500 nm, the chemical state of copper element exists in the form of elemental copper at the interface of the silver layer and the copper core, and the surface resistivity attenuation rate of the silver-coated copper powder is less than 10% after 1000 hours of accelerated aging test in an environment with 85 ℃ and 85% relative humidity.
  8. 8. The silver-coated copper powder according to claim 7, wherein the tap density of the silver-coated copper powder is not less than 40% of its theoretical density and the specific surface area is increased by not more than 15% as compared to the specific surface area of an uncoated copper core.

Description

Silver-coated copper powder based on fluidized bed chemical vapor deposition and preparation method thereof Technical Field The invention belongs to the technical field of metal composite material preparation, and particularly relates to silver-coated copper powder based on fluidized bed chemical vapor deposition and a preparation method thereof. Background The rapid development of the photovoltaic industry has placed extreme demands on the cost control of conductive pastes. Silver powder is a key functional phase of conductive paste due to irreplaceable conductivity and stability, but the high cost of silver powder accounts for more than 50% of the non-silicon cost of a battery piece, and is one of main bottlenecks for limiting the price of photovoltaic. Under the background, the silver-coated copper powder with the low cost of copper and the excellent surface characteristics of silver is regarded as a solution for realizing the most potential of replacing silver with copper and promoting industry cost reduction and synergy. However, there are great challenges in the large-scale preparation of high-quality silver-coated copper powder. Copper powder is chemically active and is extremely easy to oxidize to form a non-conductive oxide layer, so that the copper powder cannot be directly applied. Currently, the industry mainly relies on liquid phase chemical methods for mass production, including chemical displacement methods and chemical reduction methods. These methods, while relatively mature, suffer from the following inherent drawbacks: 1. The environmental pollution is serious, a large amount of wastewater containing heavy metal ions such as silver, copper and the like and organic complexes is generated in the production process, the treatment cost is high, the environmental protection pressure is huge, and the development trend of green manufacturing is contradicted. 2. The coating quality is difficult to control, the liquid phase reaction speed is high, the nucleation and growth process is difficult to accurately regulate and control, uneven and non-compact coating of the silver layer is easy to cause, even the problems of independent nucleation of silver particles or partial exposure of copper cores and the like occur, and the conductivity, oxidation resistance and long-term reliability of the product are seriously affected. 3. The process flow is complex, a plurality of dispersing agents and protective agents are often added for preventing abnormal deposition of silver, the subsequent steps are complex, and noble metal silver in the waste liquid is recovered by a complex process, so that the overall cost and the process complexity are increased. In order to avoid the pollution problem of the liquid phase method, gas phase technologies such as spray pyrolysis method and the like are explored in the industry. However, such techniques generally have problems of low productivity, extremely high requirements on precursor atomization and decomposition process control, and the like, and it is difficult to ensure uniformity of coating of all particles, and large-scale industrial application cannot be realized yet. Disclosure of Invention The invention aims to overcome the defects of the prior art and provide silver-coated copper powder based on fluidized bed chemical vapor deposition and a preparation method thereof, wherein the method aims to eliminate wastewater pollution generated by the traditional liquid phase chemical method from the source, and solves the technical problems of uneven and non-compact coating of a silver layer through the accurate control of vapor phase in-situ reduction activation and deposition dynamics, thereby realizing the clean, efficient and controllable preparation of high-quality silver-coated copper powder. The invention further aims to provide the high-performance silver-coated copper powder prepared by the method, and the product has the characteristics of continuous and compact silver layer, strong interfacial clean binding force, excellent oxidation resistance and the like. In order to achieve the above purpose, the present invention adopts the following technical scheme: a preparation method of silver-coated copper powder based on fluidized bed chemical vapor deposition comprises the following steps: S1, copper powder in-situ reduction, namely introducing pretreated copper powder with the average particle diameter D50 of 0.5-5 mu m into a fluidized bed reactor, replacing air in the fluidized bed reactor with carrier gas, heating the fluidized bed reactor to 300-500 ℃ in the carrier gas atmosphere, introducing a mixture of reducing gas and carrier gas for reduction reaction, reducing the oxygen content in the copper powder to below 500ppm, and ending the reduction reaction; s2, silver layer vapor deposition coating, namely after S1 is finished, continuously maintaining the copper powder in a fluidized state in a carrier gas atmosphere, adjusting the temperature of a fluidiz