Preliminary research no vel composite materials with small hysteresis and high functional parameters for combustion engines pistons

Pistons of internal-combustion engines are the most loaded elements of internal-combustion engines, belong to these specialistic elements, which have essential influence on the ecological properties of engines, their durability and reliability. The object of paper is pistons manufactured from the standard material and from new research alloy. The investigations were performed with dilatometer permitting on the registration of changes of the dimensions of sample in the function of temperature and time. The measurements are possible in straight system and in differential system. Exemplary results of investigations are presented in the paper. During the piston heating, period preutectic phases succumb the partial dissolution in solid solution a, but in the cooling process they secrete again. As a consequence the piston partial deformation occurs, which by result is gradual growth of difference between its expansibility during the warming and contraction in the process of cooling (so-called hysteresis occurs). The characteristics of the new piston silumin alloys give possibility of dearances minimalization and the obtainments of a correct engine performance in the full range of engine rotational velocities and loads. The effect are the decrease of the oil expenditure, the decrease of the emission of hydrocarbons in exhaust gases, the decrease of blowbys to crankcase, the decrease of the expenditure of piston rings grooves wear and the piston skirt wear, the decrease of the piston deformation and the increase of engine durability and reliability