Difference between copper and copper alloy – brass and bronze

What is a copper alloy? Many people are confused with copper, brass, and bronze. What is the difference between copper, brass, and bronze?

The simplest point is that copper is a pure metal. As a comparison, brass is a copper alloy with zinc and bronze is a copper alloy with tin.

1. Copper – Pure metal VS copper alloy

Copper is pure metal.  Brass and bronze are copper alloys.

Pure copper, also known as red copper, is a simple substance of copper (pure copper), named because of its purplish-red color.  Pure copper contains a certain amount of oxygen, so it is also called copper with oxygen.

The melting point of pure copper is 1083.4°C. Its boiling point is 2567°C, and its density is 8.92g/cm3.

Over the past thousands of years, copper has been one of the most important metals. Its greatest advantages over other metals are its good strength, formability, and corrosion resistance in many environments. Besides that, it is also an excellent electrical and thermal conductor,

2. Brass – Copper alloy with Zinc

Brass is an alloy of copper and zinc. Its color varies according to the content of the alloying elements, ranging from red to yellow.  It also has different properties depending on the amount of zinc or other elements.

Brass has strong wear resistance. It is an important copper alloy. It is popular in the manufacture of valves, water pipes, air conditioning, and radiator connection pipes. The melting point of brass H62, and H68 is 934°C and that of brass H80 is 967°C.

3. Bronze – copper alloy with Tin, Aluminum or Silicon

Bronze, another type of copper alloy, is a combination of copper with tin, aluminum, or silicon. There are different types of bronze/copper alloy depending on the alloying elements added.

3.1 Tin bronze- copper alloy with Tin

Applications: springs, washers, coins, crafts, pump parts, pressure-resistant castings, bearings, etc.

The application depends on the percentage of tin used in the alloy. The maximum content of tin in alloys suitable for cold working is about 7% and these copper alloys have good malleability.

The maximum tin content is about 20%. Starting from 5% tin, the structure of the alloy changes and some additional heat treatment is required, which leads to its porous structure, which is why they are not suitable for other forming methods than casting.

The main application of duplex tin bronze is in the bearing industry, where this structure has a good balance, where the alpha phase ensures resistance to striking, while the hard and brittle compound takes the load and provides some wear resistance.

Sometimes manufacturers also add zinc and lead into tin bronze as alloying elements. Zinc improves the quality of the castings and also cut down its cost. This copper alloy is famous for gunmetal because large guns used to be made from this material.

Small amounts of lead help improve the cutting mechanical properties of bronze. Lead bronze used as a bearing material has a relatively high lead content (up to 25%).

3.2 Aluminum bronze- copper alloy with aluminum

Applications: Gear, shaft sleeve, worm gear, and other high-strength wear-resistance parts and high corrosion-resistance elastic components.

Aluminum bronze has similar properties to tin bronze, is mostly single-phase, and is suitable for cold forming. This kind of copper alloy is very suitable for coins, where the aluminum content is usually between 6 and 12%.

4. Cupronickel – copper alloy with nickel

Cupronickel is a copper alloy with nickel. It has silvery white color with a metallic luster. Copper and nickel can dissolve each other in any proportion to form a continuous solid solution, i.e. the constants are alpha-monophase alloys regardless of the ratio of each other.

When the content of alloying element nickel is more than 16%, the color of the alloy becomes silvery white. The higher the nickel content is, the whiter the alloy color is. The nickel content in Cupronickel is typically 25%. The melting point of white copper is about 935°C.

5. copper transformer

The windings of the transformer are all copper. The national standard stipulates that the purity of copper for electrical purposes must be above 99.5%. The copper wire and copper profile used in the transformer coil all belong to the electrical copper. 

How do you braze the windings of the transformer? Please click here to get more information on it.