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Preparation method of boron carbide reinforced aluminium matrix composite material

wallpapers Industry 2020-05-08
Boron carbide (B4C) ceramic particles are highly cost-effective reinforced particles. Its hardness and wear resistance is second only to diamond, but the price is much lower than diamond. At present, it has been used in polishing processing to replace the expensive and difficult to prepare. Diamond abrasives ensure the processing quality based on cost control. In recent years, because of the broad neutron capture cross-section of boron carbide particles, strong absorption capacity, full capture energy spectrum, and excellent thermal stability, corrosion resistance, low cost, etc., it has been processed into neutron absorber plates for nuclear energy protection. Because B4C particles do not contain radioisotopes and the energy of secondary rays is low, the material itself will not produce radiation pollution.
  
At present, the main application of B4C particles is the reinforced phase in particle-reinforced metal matrix composites, which significantly improves the wear resistance, corrosion resistance, hardness and strength of the composite materials, making the use environment of the elements more extensive. However, the application of B4C particles is limited by a series of shortcomings such as weak oxidation resistance, high sintering temperature and low fracture toughness.
  
Aluminium and B4C particles have the characteristics of lightweight, high toughness and high strength. Also, B4C particles reinforced aluminium-based composite materials also have the advantages of good elasticity and protection, so they are widely used in armour materials, engine cylinder liner materials, Brake materials, neutron protective device materials, etc.
  
At present, there are mainly the following methods for preparing boron carbide reinforced aluminium matrix composite materials:
  
1. Spray deposition method
  
The spray deposition method uses high-speed airflow to disperse the aluminium metal droplets in the molten state into fine droplets. The metal droplets will conduct heat transfer with the high-speed airflow, and at the same time mix with B4C enhanced particles, the temperature of the droplets gradually decreases At the same time, it is slowly cooled and solidified on the baseliner to form a deposited embryo. A particle reinforced aluminium matrix composite material is prepared.
  
2. Smelting method
  
The B4C / Al alloy is prepared by the smelting method by heating the Al or Al alloy matrix to a molten state, and adding B4C ceramic particles to the Al alloy matrix under mechanical stirring to prepare a composite material. According to the difference in the molten state of the Al alloy matrix during stirring, it is divided into the liquid stirring and semi-solid stirring. Both methods are to add B4C powder and mix well before pouring into the mould. The process has simple equipment, few procedures and convenient operation.
  
3. Powder metallurgy
  
Mixing Al alloy powder with B4C powder, using a powder metallurgy process to prepare composite materials, and sintering below the melting point of Al alloy, the interface reaction between Al and B4C is significantly weakened. The particle size and volume ratio of B4C can be adjusted in a broad range. It can be used The cold isostatic pressing and sintering method can also be completed by direct hot pressing or hot isostatic pressing forming and sintering. The sintered body can be further extruded, forged, rolled, and other processes to improve the performance of the material. The preparation of composite materials by powder metallurgy has high requirements on equipment and preparation technology. It is challenging to prepare large-size and complex-shaped parts, and the cost of this method is relatively high. It is currently only used in aerospace and military needs.
  
4. In-situ composite method
  
In-situ synthesis technology is an emerging method for preparing B4C-reinforced aluminium-based composite materials. Its principle is to put certain substances that can react chemically with aluminium into molten aluminium alloys, and generate several reinforcements in the alloy matrix. Phase, directly strengthening the alloy. Due to the enhanced bonding strength of the reinforced particles made by chemical screening and the alloy, the composite material prepared by this method can obtain an excellent strengthening effect. The preparation process of this method is relatively complicated, and the preparation process cost is difficult to control reasonably. It is only suitable for the preparation of laboratory-prepared aerospace consumables, and it is difficult to mass-produce large-scale production.
  
The above methods for preparing boron carbide/aluminum composite materials have different process and equipment requirements, and the properties of the composite materials are also different. These need to be adjusted in actual production to obtain documents that meet the requirements and are economical. Preparation method of boron carbide reinforced aluminium matrix composite material
  
Trunnano is one of the world's largest boron carbide producers, producing boron carbide powders of various particle sizes. If necessary, please contact Leo Manager, email: brad@ihpa.net.

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Tag: Trunnano   B4C   Boron carbid