Definition - What does Exothermic Reaction mean?
Certain materials undergo chemical reactions when thermally sprayed and produce extra heat. This reaction is known as an exothermic reaction. This can improve adhesion and toughen coatings. Spray polyurethane foam (SPF) and certain coatings are the product of exothermic reactions.
Exothermic reactions are opposite of endothermic reactions.
Corrosionpedia explains Exothermic Reaction
An exothermic reaction is a chemical or physical reaction that releases heat. It gives out energy to its surroundings. The energy needed for the reaction to occur is less than the total energy released.
For example, curing of epoxy resins is an exothermic reaction, and in some cases produces sufficient heat to cause thermal degradation if not controlled. Insufficient heat during curing results in a network with incomplete polymerization, and thus reduced mechanical, chemical and heat resistance.
Exothermic reaction or production of heat can damage material life. For example, in SPF this heat can result in poorly formed foams that dramatically reduce coverage rates and diminish product performance, causing shrinkage. In extreme cases, where closed-cell foam is applied at thicknesses several times the manufacturer’s limits, it can generate enough heat to self-ignite.
Therefore, exothermic reactions are useful in coating adhesion, but uncontrolled exothermic reaction can lead to damage of the materials.