Overview
By applying a surface coat of a different material, dramatic changes in the surface properties are possible. Normally the materials used for the coats are too expensive, or have the wrong bulk properties to use for the whole components. There are several ways to coat the surface of a component:
- Painting / varnishing. Commonly used to provide corrosion resistance for woods, but also widely used for metals. Relatively inexpensive and flexible.
- Electroplating is a relatively inexpensive way of providing a surface coat, although it relies on the component being a good conductor and only certain coats are possible.
- Physical vapour deposition (PVD) or sputtering works by "shooting" a fine spray of droplets at the component. It is mainly used for metals and ceramics. Although very expensive, it can provide excellent surface properties for high-performance drill bits etc.
- Chemical vapour deposition (CVD) is similar to PVD, but the surface is formed by a chemical reaction with a special gas rather than using a spray.
