Important: Safety Warning
This page describes trade processes that use dangerously toxic materials such as cyanide solutions, mercury amalgams, or strong acids. These processes require training, equipment, and precautions far beyond what the text describes.
This information has been left in for historical purposes but should not be acted upon.
Expanding Alloy
Lead 9, antimony 2, bismuth 1. This alloy is useful to fill holes in castings, as it does not contract and become loose like lead or cast iron. What are termed expanding alloys invariably contain bismuth and antimony in some proportion. This special quality has rendered these metals valuable for type-metal composition, etc. See BISMUTH; ANTIMONY; TYPE-METAL. Expansion is the enlargement or increase of bulk in substances, chiefly by means of heat. This is one of the most general effects of heat and is common to all bodies whether solid, fluid, or in the aeriform state. Expansion by heat varies greatly. The following table gives the linear expansions of several useful metals from 0 deg. to 100 deg. C., the length at 0 deg. being taken as unity:
Metal. Expansion 0 deg. to 100 deg. Platinum, cast..... .000907 Gold, Cast..... .001451 Silver, cast..... .001936 Copper..... .001708 Iron..... .001228 Cast steel..... .001110 Bismuth..... .001374 Tin..... .002269 Lead..... .002948 Zinc..... .002905 Cadmium..... .003102 Aluminum..... .002336 Brass (copper 72, zinc 28)..... .001879 Bronze (copper 86, tin 10, zinc 4)..... .001802 See CONTRACTION; SHRINKAGE.