Design and Preparation of Stepwise Functionally Graded Materials Used for Internal Combustion Engine Piston Applications

Abstract

This work includes the design and preparation of a(Low carbon steel / AL 2 O 3) stepwise functionally graded crown part of an internal combustion engine piston. Powder technology technique, has been studied to improve engine thermal efficiency by creating semi adiabatic combustion chambers, where ceramic phase facing the hot combustion gases, while metallic phase assembling with other parts of the piston. Finite element method ABAQUS program had been used to minimize nucleated residual stresses generated under fabrication process and service work conditions by designing the compositional graded of stepwise FGM within specific dimensions, in addition to temperature distribution across FGM thickness. Then the fabricated specimens had SEM imaging, physical and mechanical property inspection. The results also show that linear transition from metal to ceramic structure can provide minimum residual stresses under all conditions, using stepwise FGM can improve engine heat efficiency by doubling the crown surface temperature,(622) ºC, comparing with steel crown, (322) ºC, under the same applied heat flux. Physical inspections show limited relative density, (48.5) %, with high total porosity structure, (53.3) %, can be performed by this fabrication method. Mechanical tests results show that the layers' hardness increase with increasing ceramic content, and decrease with increasing pores percentage. Compression test shows the ability of suggested stepwise FGM to withstand service work stresses of combustion chamber without failure. INTRODUCTION hile only around (30) % of fuel energy which supplied to engines is used to perform useful work, the residual amount is lost through friction and cooling activities. This directs engines researches during the last two decades toward improving thermal efficiency of engines [1]. Improving heat efficiency can lead to; decrease consumed fuel by reducing the incomplete fuel combustion percentage, reduce the pollution gases as reduction of consuming fuel, enhance thermal fatigue resistance as reduction of thermal stresses of underlying metallic surfaces, consequently, increase the estimating work life of the cylinder, finally boosting engine power by improving mechanical and thermal loads limits [2, 3]. Lining the combustion chamber with low thermal conductivity, and high temperature resistance ceramic phase by thermal coating have a discussion by may researcher, however, these procedures can provide only limited heat insulations because the limited thickness that can be applied. In this work, it's suggested to prepare bulk thermal barrier stepwise FGM to use as crown part of piston by powder technology