First、 Physical Law
Physical methods can usually prepare copper powder with high purity and good sphericity.
1.Atomization method
Aerosolization method: using high-pressure inert gas, the resulting powder has low oxygen content and good sphericity, but the cost is relatively high. Commonly used in high-performance powder metallurgy and 3D printing of metal powders.
Water atomization method: using high-pressure water flow, fast cooling speed, irregular powder particles obtained (mostly in the form of flakes or tears), large specific surface area, and relatively high oxygen content. Low cost, commonly used for manufacturing diamond tools, friction materials, etc.
Principle: Molten copper liquid is sprayed out through a nozzle, crushed into small droplets using high-pressure gas (air, nitrogen, argon) or high-pressure water, and then condensed into spherical or nearly spherical powder under the action of surface tension.

Characteristics: High production efficiency, easy industrial large-scale production, and is one of the main methods for producing metal powders.

2.Vacuum evaporation condensation method
Principle: In a high vacuum environment, metal copper is heated and evaporated, and gaseous copper atoms are condensed into ultrafine powder on a low-temperature condensation wall.
Characteristics: It can prepare nanoscale, high-purity ultrafine copper powder, but the equipment is complex, the yield is low, and the cost is high. It is mainly used in laboratory research and high-precision fields.

Second, Chemical method
Chemical methods can prepare copper powder with finer particle size and diverse shapes, especially nano copper powder.

1.Liquid phase reduction method (the most commonly used chemical method)
Principle: Using soluble copper salts (such as copper sulfate and copper chloride) as raw materials and hydrazine hydrate, formaldehyde, sodium borohydride, ascorbic acid (vitamin C) or glucose as reducing agents, Cu ² ⁺ is reduced to Cu ⁰ atoms in the liquid phase and aggregated into powder.
Reaction example (using copper sulfate and hydrazine hydrate as examples):
2CuSO₄ + N₂H₄·H₂O + 4NaOH → 2Cu↓ + N₂↑ + 2Na₂SO₄ + 5H₂O
Characteristics: The operation is relatively simple, and the particle size and morphology of copper powder can be controlled by adjusting parameters such as reactant concentration, temperature, pH value, and additives (dispersants, protectants). It is the most commonly used method for laboratory and industrial production of ultrafine copper powder.

2.electrolysis method
Principle: Use copper plate as the anode and titanium or stainless steel plate as the cathode, and apply electricity in an electrolyte containing copper ions. The copper at the anode loses electrons and dissolves into Cu ² ⁺. Cu ² ⁺ obtains electrons at the cathode and is reduced to metallic copper, which is deposited in powder form on the cathode.
Characteristics: The obtained copper powder has high purity (up to 99.95% or more), dendritic structure, large specific surface area, and good compressibility. But the energy consumption is high and the cost is also high. It is an important method for producing copper powder for electrical materials.

3. Thermal decomposition method
Principle: Copper compounds (such as copper formate, basic copper carbonate, and carbonyl compounds of copper) undergo thermal decomposition at a specific temperature, producing copper powder and gas products. Characteristics: The powder has high purity, but the raw material cost is high and may produce harmful gases, making it less commonly used.

3、 Mechanical Law
ball milling
Principle: Metal copper blocks or copper shavings are placed together with grinding balls in a ball milling jar. Through the high-speed rotation or vibration of the ball mill, the grinding balls strongly impact, crush, and friction the copper material, causing it to repeatedly break and cold weld, ultimately refining it into powder
Features: Simple equipment, high output, low cost. But the powder shape is irregular, the particle size distribution is wide, it is easy to introduce impurities, and the energy consumption is high. Mainly used for producing flake copper powder (such as copper gold powder for coatings) or alloying copper with other elements.

The above are several mainstream methods for synthesizing copper powder, and there are other methods that can also be used to produce copper powder.

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