Salt Bath Furnaces

A salt bath furnace is basically a ceramic or metal container filled with molten salt into which work is immersed for either heating or cooling. The furnace contains salt such as nitrates, nitrites, caustic soda, chlorides, carbonates, and cyanide. Mixtures of salt are selected to give a specific temperature range and a desired treatment (or lack of treatment) to the surface of the material being processed. When we want to change the physical properties of something without changing the surface of it, we use neutral salts such as chlorides and nitrates. We can change the surface conditions of a part by placing it in a salt bath furnace having ingredients that react chemically with the surface as in carburizing, cyaniding, nitriding, and aluminizing. Other salts are formulated to remove scale, paint, plastic, or organic contamination.