COPPER/NICKEL (NICKEL BRONZE, CN SERIES, EN CC330-334G)
Copper/nickel casting alloys contain about 30% nickel with additions of either chromium (grade CN1) or niobium (grade CN2). The wrought versions of this material contain between 5% and 32% nickel to the copper parent and various trace elements (NES 779 & NES 780 alloys). Casts formed in copper/nickels are highly resistant to corrosion and are typically specified for service in adverse conditions – most commonly as naval architecture. The interest to artists lies in the material’s distinctive colour, close to that of silver coinage (though a green tint is often discernable, especially after a period of exposure and weathering).
Nickel bronzes are structurally stronger, but more problematic to cast and chase and finish (patinate), than most of the common cast copper alloys. Wrought material is available from specialist non-ferrous metal stockists – round bar (BS 2874) and sheet or plate (BS 2870), are the most common forms available. Cast and wrought nickel bronze alloy (90/10 grade CN 102/NES 779 is best overall for general purpose use), is usually welded by a TIG process, though filler wire for MIG process is also available (nickel rich copper filler material for welding carries a C17 or C19 designation). In keeping with other unusual or exotic alloys, founders are likely to charge premium rates for works ordered in this material.
OTHER COPPER ALLOYS
A number of other copper based alloys are available including copper/chromium (BS 4577/EN CC040&140A), copper/manganese/aluminium (EN CC212E) and copper/beryllium (CB101 wrought alloy). Most of these are typically used for highly specialised industrial applications and are of little interest to the artist or designer except perhaps on a conceptual level. The use of copper/beryllium materials should be avoided, this material can release a highly toxic particulate if abrasively worked.
Franta Belski 'Dolphins'.
Cast nickel bronze (1988).
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