The three structures of copper tubing

Copper alloys with different compositions exhibit distinct crystallization characteristics, varying casting performance, and unique casting process features.

1. Tin bronze: Its crystallization characteristics include a wide crystallization temperature range and a broad solidification zone. Its casting performance is marked by poor fluidity, a tendency to form shrinkage porosity, and resistance to oxidation. A key process feature is the use of directional solidification for parts with thick walls.

2. Aluminum bronze and aluminum brass: Their crystallization characteristics are marked by a narrow temperature range and a sequential solidification pattern. In terms of casting performance, they exhibit good fluidity but tend to form concentrated shrinkage cavities and are highly susceptible to oxidation. As for process features, the gating system for aluminum bronze is bottom-pouring, while that for aluminum brass is open-type.

3. Silicon brass: Its crystallization characteristics are intermediate between those of tin bronze and aluminum bronze; it has the best casting performance; its processing feature is sequential solidification.

What are the corrosion prevention methods for copper pipes?

Specifically: coating the pipe layer with asphalt paint; cement mortar lining plus a special coating; coating the pipe layer with epoxy coal tar asphalt; epoxy ceramic lining; aluminous cement coating and sulfate cement coating; and coating the pipe layer with polyurethane, among others.

The application of copper pipes has surpassed the usage rate of iron.

Iron is ubiquitous in our daily lives and finds extensive applications—from large-scale structures like buildings and halls to smaller items such as stoves and kitchen utensils. However, nowadays, copper pipes are also widely used in real life, even surpassing the use of iron in many areas.

Copper tubes are used far more extensively than pure iron. Each year, 50% of the world’s copper is electrolytically refined into high-purity copper, which is then employed in the electrical industry. The copper tubes referred to here must contain at least 99.95% copper, as impurities such as phosphorus, arsenic, and aluminum can significantly reduce copper’s electrical conductivity. Moreover, impurities like lead, antimony, and bismuth can prevent copper crystals from bonding properly, leading to hot brittleness and adversely affecting copper’s machinability.

These high-purity copper tubes are typically refined by electrolysis: impure copper serves as the anode, while pure copper acts as the cathode, with a copper sulfate solution used as the electrolyte. As current flows through the system, the impure copper at the anode gradually dissolves, while pure copper gradually deposits onto the cathode. The copper thus refined can achieve a purity of up to 99.99%.