Design of novel composite pistons for diesel engine

The paper presents the requirements to be met by diesel engines and their components, in particular pistons for engines of military vehicles. These requirements are related to the mass of modern military vehicles, which has greatly increased. Materials for the piston should have a good strength properties and low hysteresis of thermal expansion coefficient α across the range of operating temperatures, good resistance to galling, low abrasion, low coefficient of friction and good functional properties. On the clearance of the piston in the cylinder, the coefficient of thermal expansion α and its hysteresis has a decisive influence. The paper includes information on the piston working clearances, the requirements for pistons materials, their chemical composition, standard materials for the forged pistons, for the cast pistons (silumin alloys) and for the composite pistons. The paper presents the changes in coefficient of thermal expansion for the alloy in the raw state and after heat treatment and pistons made of new composite material prior to motor testing and after these tests. The completed new pistons have a lower coefficient of thermal expansion and lower hysteresis α, which allows reducing the running piston and cylinder clearances with the resulting effects.