TIN & TIN ALLOY (PEWTER BS:5140 1974 , BS EN 611-1/2 1996, BABBITT)
Tin is generally best known as a plating metal for coating CARBON STEELS (as in tin can manufacturing). Within art casting processes, tin is an especially important alloying element found in many copper based alloys, including true BRONZES and GUNMETALS. Tin is also used as a bearing metal (BABBITT), alloyed in this instance with 7% antimony and 3% COPPER.
Tin in it’s own right, as either a cast or wrought material, is little used in sculpture making; though one particular alloy of tin – PEWTER is occasionally used for casting artworks. Traditionally, pewter is used for casting (decorative) tableware and similar household items. The composition of pewter varies, though most grades consist of about 90% tin base, with the remaining 10% made up from additions of lead, copper, antimony and bismuth. Like LEAD, pewter is a LOW MELTING POINT alloy, which is easily melted and exceptionally free running, suitable also for casting into silicone rubber moulds as an alternative to REFRACTORY MOULDS. Babbit can also be readily melted in an iron ladle under moderate heating. Similar to pewter and babbit, the alloys collectively referred to as WHITE METALS are usually composed of lead and tin in varying proportions with additions of bismuth and cadmium to improve the fluidity of the molten material.
NICKEL (MONEL®, INCONEL®, INCOLOY®)
Nickel, a white-grey metal in appearance, features principally in art founding as an addition to the copper/nickel or NICKEL BRONZE series of alloys. Nickel is also found in AUSTENATIC STAINLESS STEELS, and used extensively as an electroplating deposit for finishing architectural and other decorative works. An excellent level of corrosion resistance is offered by nickel and nickel alloys; however, the visual appearance of the metal is generally of greater interest to the artist or designer. For fabricated works requiring bright nickel finishes, wrought nickels (BS3072) are available, in addition to nickel clad steels which offer considerable cost savings over full nickel stock (if the finish offered by a stainless steel is unsuitable).
The more important alloys of nickel are known under the following registered trade names, MONEL (nickel/copper), INCOLOY (nickel/chromium/iron) and INCONEL (nickel/chromium/iron with molybdenum and niobium). Other nickel alloys include NIMONIC, BRIGHTRAY and NILO. Incoloy (BS3076) is especially suited to wrought metalworking techniques, this alloy handles in a similar fashion to the more common austenitic stainless steel alloys. Nickel and most of it’s alloys are weldable by all the standard arc processes, and in particular TIG welding.
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