Resource Library

I have some brass components which have stained on machining. How can I clean them?

Use an acidic dip such as a mixture of citric and phosphoric acids. This is quite gentle and with care easy to use.

What does the term DEF STAN (DStan) mean?

These are the engineering standards prepared for material for use by the Ministry of Defence.  They have replaced NES (Naval Engineering Standards), which in their turn replaced DGS (Directorate General Ships) standards.

Which copper alloy has a good electrical conductivity and retains strength up to 400°C?

Copper chromium (CC101) – conductivity is 80% IACS – strength good up to 400°C.

I intend to use copper as a cladding material but I do not want to wait for the natural patina to form. What do you suggest that I might use?

Copper sheet is available in pre-patinated form.  As well as green, other attractive colours such as brown, gold and silver are available.  See www.kme.com and www.aurubis.co.uk.

What effect does heavy cold working have on the electrical conductivity of copper?

It reduces by about 3%.

I require an aluminium bronze with a very low iron content (0.5-0.7%). The application is a holder in an induction furnace. It is important that the holder does not become heated in service.

Suggest DEF STAN 02-834, which is a naval grade of aluminium bronze with a low magnetic permeability.  This meets MOD requirements.

Which copper alloy has the best corrosion resistance in seawater?

Various copper alloys have particular strengths under specific sea water conditions but on balance 90-10 copper-nickel has excellent corrosion resistance in many applications and is perhaps the most versatile. There is a detailed description of the properties and applications of this and other popular copper nickel alloys on the www.coppernickel.org website. Of course, aluminium bronze alloys, particularly nickel aluminium bronze, are also recognised for their corrosion resistance in severe seawater conditions and for that reason also have established applications as propellers and pumps and valves.

I wish to produce components by carrying out simple forming operations on brass sheet. Should I use the 70/30 Cartridge Brass (CW505L)?

CW505L is the most ductile brass, but for simple forming the more economical 63/37 Common Brass (CW508L) should be used.

Which copper alloy has the highest ductility?

70/30 brasses CZ106 (CW505L).

I wish to restore a copper canopy on an old building to its original condition. How can I do this?

Stages:

(a) Remove surface oxide with dilute (10%) hydrochloric acid
(b) Neutralise with bicarbonate solution (lye)
(c) Seal by chromate conversion
(d) Lacquer
(e) Wax
(f) Clean with detergent annually.

How does the surface of copper alloys change in seawater?

After exposure to seawater, copper alloys develop a surface oxide film which provides protection from corrosion.