Page 61 - Making things move_ DIY mechanisms for inventors, hobbyists, and artists

42 Making Things Move

These are two common copper alloys:

1. Brass Mix copper and zinc together, and you get brass. It’s stronger and
more durable than copper, and good at resisting corrosion from the
atmosphere and water (including saltwater). It’s not generally used for
structural parts, but is common in furniture and architectural design.

2. Bronze Mix copper and tin together, and you get bronze. The alloy is harder
and stronger than copper, and more corrosion-resistant but softer than brass.
Bronze is also used in bushings because of its relatively low friction. (If you
don’t know what a bushing is, no worries—you’ll learn in Chapter 7.)

Silver
Silver is actually a better conductor than copper, but it is much more expensive, so it is
used only in very high-end electronics. It is also soft and easy to form, making it a
favorite of jewelry makers.

Mixing silver with a bit of copper yields sterling silver, an alloy that is even easier to
work with. Silver is not used structurally because it is too soft and too expensive.

Ceramics

Ceramic compounds fall between metallic and nonmetallic elements (oxides, carbides,
and nitrides). Examples include clay, glass, diamonds, precious stones like amethyst,
and your favorite coffee mug.

Ceramics are hard, but if you’ve ever dropped a coffee mug and seen it shatter, you
know they are also brittle. Unlike metals that stretch and yield before they break,
ceramics just break. They are good insulators of electricity and heat, and resist high
temperatures and corrosion well. For our purposes, you might see them used only as
insulating spacers (standoffs) that keep electrical components safe.

Polymers (Plastics)
Plastics and rubbers are types of polymers. Foams, like neoprene, also fall into this
category. They have low densities, so they are relatively light.