Anti-scale compounds are protective coatings used during the heat treatment of steel to reduce oxidation and decarburization at elevated temperatures. When steel is heated in air, oxygen reacts with the surface to form iron oxide scale. At the same time, carbon near the surface may be depleted, producing a softened “decarburized” layer that can negatively affect hardness, wear resistance, and dimensional accuracy. Anti-scale compounds help limit these effects by forming a temporary barrier between the hot steel and the surrounding atmosphere.
These compounds are commonly applied as a liquid coating before heat treatment. After drying, the coated part is heated in the furnace as normal. During heating, the coating resists oxygen contact with the steel surface and can significantly reduce the amount of scale produced. This is especially useful for tool steels, springs, knife blades, precision components, and other parts where surface finish and hardness are important.
Commercial examples include Condursal Z1100, Turco, and ATP-64. These products vary in temperature capability, application method, and intended alloy systems. Some are designed for high-speed steels and tool steels, while others are intended for general heat treatment operations.
Although anti-scale compounds can greatly reduce oxidation, they are not always a complete substitute for controlled-atmosphere or vacuum heat treatment systems. However, they provide a relatively simple and economical method for improving surface quality in many small-shop and industrial heat treatment applications.