Resource Library

I have a number of machined aluminium bronze components which are to be packed in wooden boxes and shipped to Australia. How do I avoid corrosion/staining?

The key is to clean thoroughly, remove water, protect and keep dry:

1. After cleaning dry thoroughly using a de watering fluid such as WD40.
2. Remove displaced water with forced warm air.
3. Coat with protective coating such as benzotriazole inhibitor or a block copolymer.
4. Pack into benzotriazole treated paper lined wooden boxes. Moisture absorbent granules may also be used to keep the air inside the boxes dry.
5.Remove the coatings with a phosphoric based solution.
6. Dry thoroughly.

What are the gilding metals and what are they used for?

Copper-zinc alloys (brasses) with up to 20% zinc.

I have been asked by a customer if the leaded brass CZ121Pb3 (CW614N) that I am using to make leaded inserts is RoHS compliant. What does this mean?

The RoHS Directive stands for “the restriction of the use of certain hazardous substances in electrical and electronic equipment”. This directive bans the placing on the EU market of new electrical and electronic equipment containing more than agreed levels of lead, cadmium, mercury, hexavalent chromium, polybrominated biphenyl (PBB) and polybrominated diphenyl ether (PBDE) flame retardants. The allowed limit for lead in copper alloys is 4%; CW614N has a lead range from 2.5 to 3.5% so it is compliant.

When removing old copper pipework, or an old copper cylinder, can they be recycled?

Yes. Copper is infinitely recyclable.

I have been asked for 'Coining Brass'. What is it?

Coining is closed die squeezing (as in making coins) and applies to any of the cold forming brasses: 90/10, 85/15, 80/20, 70/30. Should be OK to use 1/2 hard , but anneal if necessary.

What are the major benefits of copper tubes for air conditioning applications?

Energy efficiency: reducing the diameter of copper tubes in coils provides an economical path to energy efficiency for air conditioning and refrigeration (ACR) products.

Less material: tube-diameter reduction results in more effective heat transfer and consequently smaller, lighter coils. Less tube and fin material could provide equivalent heat transfer or more heat transfer; or the same material could provide much more heat transfer.

Less refrigerant: a dramatic reduction in refrigerant volume is a further benefit of copper tubes.

Durability: coils made of copper tubes and aluminium fins (CTAF) or copper tubes and copper fins (CTCF) are durable and dependable. They set the industry standard for corrosion resistance and long, reliable service life.

Familiarity: tube suppliers, OEMs, mechanical systems engineers and HVAC contractors are all highly familiar with CTAF technology. Up and down the value chain, the materials and processes are well understood.

When working on a site that does not permit flames can you use copper press fittings?

Yes, using flame-free fittings.

I have been asked to produce 22 valves in gunmetal from a drawing which originates from 1958. The company has been taken over and the patterns and casting drawings lost. Due to the small quantity that will have to be made from bar, what should I use?

Suggest that you use continuously cast CC491K (LG2) bar or a wrought free-machining phosphor bronze.

What copper alloy is recommended for condenser tubes cooled by seawater?

90/10 (or 70/30) copper-nickel alloys.

I have been asked to produce bolting for use inside a van used to carry explosives. The material must be non-sparking. What should I use?

Tiny particles can be detached from their parent object by the force of impact of a harder instrument or object in air. Elements like iron, when finely divided and hot, can ignite spontaneously as they oxidise, becoming even hotter. This results in dull red particles rapidly becoming bright white at a much higher temperature. At this temperature the particle is visible as a spark and can cause fire or explosion in a combustible environment. In common with most other copper base alloys, the particles detached from an aluminium bronze object due to impact against a ferrous or other harder objects, do not attain a dangerous temperature and are not visible as a spark. In view of their high strength, aluminium bronzes are the most favoured for applications where this is important. They may therefore be safely selected for non-sparking tools and equipment for handling combustible mixtures such as explosives.

Where can I learn about the metallurgy of copper alloys including the phase diagrams and heat treatment?

Phase diagrams are in Pub 94. Other details are in Pubs 122 and 117. For more info, contact CDA.

What copper/copper alloy may be used for vehicle radiators?

When good heat transfer is essential, as in vehicle radiators, copper and brass are excellent choices due to their high thermal conductivity and ease of brazing, especially in thin sheets.