METAL PROPERTIES, CHAR, USES, AND CODES - OD1643 - LESSON 1/TASK 2
silicon and sometimes iron and magnesium.
Wrought aluminum alloys
may contain chromium, silicon, magnesium, or manganese.
Aluminum,
which resembles magnesium, can be distinguished by the application of
a drop of silver nitrate solution on each surface.
The silver
nitrate will not react with aluminum, but leaves a black deposit of
silver on magnesium. A copper sulfate solution is used as discussed
in paragraph 3b(8), page 27, to distinguish steel from aluminum or
lead.
(2) Aluminum Bronze.
The aluminum bronze metals are yellow in
color but, when polished, they are darker than brass.
(3) Polished Brasses and Bronzes. The colors of polished brasses
and bronzes will vary from an almost copper-color red to yellow,
depending on the composition of the metal. These metals will oxidize
to various shades of green, brown, and yellow.
(4) Copper.
Copper is a lustrous, reddish-brown metal.
When
polished it gives a red appearance and it will oxidize to various
shades of green.
(5) Lead.
Lead is white in color when freshly cut and becomes
dull gray when exposed to the air. A copper sulfate solution is used
to distinguish steel from lead, as discussed in paragraph 3b(8), page
27.
(6) Magnesium.
Magnesium is silver-white when polished, but
oxidizes rapidly to a grayish film.
It weighs about one-third less
than aluminum, which it otherwise resembles. To distinguish aluminum
from magnesium, a silver nitrate solution is used, as discussed in
paragraph 3c(1), beginning on page 27.
(7) Monel. Monel metal is an alloy of nickel, copper, iron, and
manganese. It is light gray in color and dulls to a darker gray on
aging.
(8) White Metal.
White metal castings are usually made with
alloys of aluminum, lead, magnesium, and tin. With the exceptions of
those made with lead or tin, they are lightweight and notably white
in color.
The surface is much smoother than that of castings
produced by the use of sand.
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