Abstract
This study deals with the different types of wear as well as other parameters present in the tribological system pistonsegment- cylinder in a combustion engine. By means of engineering methods were defined the wear rates in the three components of the system. The biggest wear in the analysis resulted in the cylinder shirt. Specialized methods applied were used to analyze the prevailing metallographic characteristics in its original construction, obtaining a gray melted iron with perlitic matrix. A new material with bainitic matrix has been proposed for increasing wear resistance. To demonstrate the efficiency of this new product, the experimental techniques carried out, were based on a dynamometric testing in a internal combustion engine diesel cycle Scania of 150 kW. It was exposed to a full charge during 500 h with 30 % of potency rising. Compared with the perlitic one, it has been proved that the bainitic matrix allows a better result. Besides, a superior dimensional stability was obtained. The piston segments had a similar wear rate in both materials in reference to the original tribological pair of the project.
Highlights
This study deals with the different types of wear as well as other parameters present in the tribological system pistonsegment-cylinder in a combustion engine
The biggest wear in the analysis resulted in the cylinder shirt
A new material with bainitic matrix has been proposed for increasing wear resistance
Summary
Los motores de combustión interna son sistemas cuyas características de funcionamiento causan desgaste, principalmente cuando se piensa en los componentes de la cámara de combustión, como los segmentos o aros, pistones y cilindros o camisas de cilindros. Los elevados niveles de presión y solicitación son transferidos a la estructura del motor, en particular las paredes resistentes del bloque junto al alojamiento de los cilindros, lo que hace necesario conocer la respuesta del hierro fundido a la solicitación mecánica, posibilitando así optimizar este material a cada aplicación a la cual será sometido. En la realidad estas imposiciones están siendo cumplidas a través de técnicas especiales de acabado superficial de cilindros, exigiendo, además, que este acabado se mantenga durante mayores periodos de funcionamiento, lo que requiere el desarrollo de aleaciones de hierro fundido más resistentes al desgaste, que en el caso de los motores ciclo diesel están encuadradas generalmente en hierro fundido gris. Un cambio de paradigma en términos de matriz de hierro fundido gris es la utilización de la estructura bainítica, que siendo bien tratada térmicamente puede constituir un interesante elemento para las camisas de cilindros de los motores de combustión interna de ciclo diesel. Ludema[13] considera que la fatiga de bajo ciclo (régimen plástico) es la explicación más probable de que ocurra este desgaste
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