Head gaskets typically consist of materials like copper, steel, graphite and polymer coatings, according to Engine Builder. The composition of a head gasket affects its ability to seal the combustion chamber of an engine.
Graphite is often the choice for the outer layer of the gasket because it is soft and flexible enough to form a good seal that requires little or no heat to stick. Graphite also has a high tolerance to high temperatures. Its softness, though, means care should be taken in handling it. Some manufacturers use a polymer coating instead of graphite for better sealing on gaskets that require very smooth surfaces to stick well.
Steel typically forms the body of the head gasket because it is strong, rigid, and able to stand up to high combustion pressures. Some manufacturers reinforce their gaskets by using multiple layers of stainless steel. Steel wire rings in the gasket can also improve sealing around the combustion chamber.
Copper helps reinforce the head gasket. Some manufacturers have also made head gaskets of solid copper for higher horsepower engines. Furthermore, because copper conducts heat well, it can transfer heat away and prevent damage to the engine block.
