How Each Is Made
Electrolytic copper powder is grown by electrodeposition: copper is deposited from solution under conditions that produce branched, tree-like dendritic particles. Atomised copper powder is made by melting copper and breaking the stream into droplets with a gas jet; the droplets freeze in flight as near-perfect spheres. The two processes produce powders of the same metal with almost opposite handling behaviour.
What the Morphology Changes
The dendritic structure of electrolytic powder (such as CU-ED) interlocks under pressure, giving excellent compressibility and green strength: pressed parts hold their shape before sintering. The cost is flow, dendritic powder is non-flowing and has low apparent density, from 0.65 to 2.7 g/cc across the grade range. Spherical atomised powder (such as CU-AT) is the mirror image: excellent flowability and high apparent density of 4.0 to 4.8 g/cc, but little green strength when pressed.
Property Comparison
| Property | Electrolytic (CU-ED) | Atomised (CU-AT) |
|---|---|---|
| Morphology | Dendritic | Spherical |
| Purity | Cu 99.0% min | Cu 99.9% min |
| Apparent Density | 0.65 to 2.7 g/cc | 4.0 to 4.8 g/cc |
| Flow Rate (Hall) | Non-flowing | 25 sec/50g |
| Green Strength | High | Low |
| Typical Uses | Diamond tools, pressed PM parts, friction materials | Thermal spray, cold spray, additive manufacturing |
Which Should You Specify?
Choose electrolytic dendritic copper when the process presses and sinters: diamond tool segments, powder metallurgy structural parts and friction materials all depend on green strength. Choose atomised spherical copper when the powder has to move: thermal spray, cold spray and additive manufacturing all need free flow and uniform packing. Many manufacturers use both across their product range, and blended formulations sometimes combine them to balance flow against compaction. If in doubt, our technical team will match the grade to your process.
Purity and Oxygen
The routes differ in chemistry as well as shape. Electrolysis is a purification step in its own right, the electrolyte rejects most contaminants, so CU-ED is supplied at Cu 99.0% minimum. Gas atomisation under inert cover protects the melt from oxidation, and CU-AT is supplied at Cu 99.9% minimum. The higher figure reflects a cleaner melt and an inert atomising atmosphere, and it matters most where surface oxide would disturb a melt pool or a sprayed deposit.
Surface Area and Reactivity
Dendritic powder carries far more surface area per kilogram than spherical powder of the same nominal mesh, because the branches multiply the exposed surface. That reactivity is an advantage in sintering, where it drives densification at lower temperatures, and a liability in storage, where it accelerates oxidation once a container is opened. The finer SFP grades are the most reactive of all.