They are the only option to work well for sharpening carbide toothed chain, but that's probably not a good plan for sharpening conventional steel chain.
Diamond saws are known to be more effective on hardened material such as ceramic, rocks, and glass. Unfortunately, when steel is heated to a red-hot or white-hot state (around 1300°C to 1600°C or 2400°F to 2900°F), it emits a significant amount of thermal radiation. In this superheated state, the steel's surface is also exposed to the surrounding atmosphere.
In the presence of oxygen from the air, the carbon atoms in the diamond lattice on the surface of the diamond begin to react.
The high temperature provides the activation energy necessary for this reaction to occur.
- Combustion Reaction: The chemical reaction that takes place is a combustion reaction, which can be represented as follows:
C (diamond) + O2 (g) → CO2 (g) (Carbon from diamond reacts with oxygen to form carbon dioxide)
Basically, any kind of metal is very bad for the diamond wheels, but particularly any steel that makes sparks when heated by friction and goes on to react with oxygen. This chemical reaction between oxygen and steel makes enough heat to start burning up the tiny diamonds, too. I've also been told that the extra heat isn't much good for the metal that is bonding the diamonds to the steel wheel, either. Cobalt is more common as a binding agent for the diamonds, but nickle and bronze are also used. These metals have a melting point barely higher than the very high heat produced by the burning steel created by the of the wheel and mixing with oxygen. This is also a contributing factor to the release of the diamonds from the matrix on the grinding wheel in addition to just burning the diamonds up like tiny motes of coal burning up with the heat of friction.
In general: don't try to cut steel with a diamond wheel. It'll do it, but not for long.
