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Effects of Mixing Ratio of the Milled Powder on Microstructure and Mechanical Properties of Sintered Valve Seats

소결 밸브시트의 미세조직 및 기계적 성질에 미치는 볼밀 분말 혼합비의 영향

  • 최성태 ;
  • 박종관 ;
  • 최창수 ;
  • 정인상
  • Published : 2003.04.01

Abstract

The recent trend of miniaturization and high performance of vehicle engines has put an urgent necessity for the development of valve seats which can operate under more severe conditions. In order to develope valve seat material that has the most excellent wear resistance at operating temperature of engine through improvement of the progress of work. the effects of mixing ratio of the milled powder on sintered and Cu-infiltrated properties of sintered valve seats have been studied. The resultant radial crushing strength and hardness of sintered specimens were gradually increased with increasement of volume of milled powders. It is because increasement of sintering density by increasing of surface diffusion. The hardness of Cu-infiltrated specimens became lower than that of the commercial powders as the increasement of volume of milled powders. It was due to the decrease of the amount of the martensite. By results of this research, It has been found that martensite is formed around of the Cu-infiltrated site and the decrease of the amount of the martensite is due to decrease of the amount of the Cu-infiltrated site by the decrease of gas channel.

Keywords

Valve seat;Sintering;Mixing ratio;Microstructure;Mechanical property

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