Nano copper powder has smaller particle sizes and a larger total surface area compared to micron-sized copper powder of the same volume, making it easier to form conductive networks in polymer resins. However, due to its high surface energy and reactivity, it tends to oxidize into cuprous oxide in the air and agglomerate in polymer resins, making it difficult to perform as expected. Do you know the preparation technology for nano copper powder? Let's find out together.
Inductive Heating Method: Metal materials placed in a ceramic crucible are heated under high-frequency or medium-frequency current induction. This heating method features strong induction and stirring effects, resulting in rapid heating and high temperatures. By controlling process parameters, copper powders ranging from 10 nanometers to 1 micrometer can be produced.
Gamma-ray Method: The preparation of various metal particles by gamma-ray irradiation is a new method developed in recent years. Its basic principle is the reduction of metal salts into metal particles under gamma-ray radiation. Gamma rays generate solvated electrons in the solution, eliminating the need for a reducing agent, and can reduce metal ions, lowering their valence, which then nucleate and grow into metal particles. Researchers have obtained nanocopper powder with an average particle size of 50nm using a combined gamma-ray radiation-hydrothermal crystallization method.
Plasma Method: This technique involves melting metal powders into vapor, which then undergoes physical or chemical reactions in the gaseous state. During the cooling process, the particles coalesce and grow to form ultra-fine powders, effectively producing high-purity, uniform, and small-sized metal and metal alloy series nanoparticles. Under appropriate process conditions, nano-copper powder with an average particle size of 70 nanometers, uniform particle size distribution, and good dispersibility can be obtained.
Mechanical-Chemical Method: The mechanical method is a technique that utilizes high-energy ball milling to induce chemical reactions. Its advantages include high yields, simple process, and the ability to produce high melting point metals, immiscible solid solutions, nanometal (intermetallic compounds), and nanometal ceramic composite materials that are difficult to prepare by conventional methods. The drawbacks are that the particle size distribution of the obtained powder is uneven, and impurities are easily introduced during ball milling. If only copper chloride and sodium are used as raw materials for mechanical crushing, and if sodium chloride is added to the reaction mixture beforehand, combustion can be avoided. The resulting copper powder is very fine, with particle sizes ranging from 20 to 50 nanometers.
Electrolytic Method: The electrolytic method can produce many high-purity metal ultra-fine particles that are difficult to prepare or obtain through conventional methods, particularly metal powders with high electronegativity. An improved process can produce ultra-fine copper powder with an average particle size of 80nm-100nm, uniform particle distribution, surface coating, high dispersibility, and antioxidant properties.
In the packaging and transportation of nano copper powder, aluminum foil packaging should be used in 100g, 500g, and 1kg sizes. The packaging must be sealed. Store in a cool and dry place at 0-5°C. Avoid contact with oxidizing agents.