Failure Analysis on Scale Formation of Thermostat Housing and Development of Accelerated Test Methodology

써모스타트 하우징의 침전물 생성에 관한 고장분석 및 가속시험법 개발

  • Cho, In-Hee (Reliability Assessment Center for Chemical Materials Korea Research Institute of Chemical Technology) ;
  • Hyung, Sin-Jong (Reliability Assessment Center for Chemical Materials Korea Research Institute of Chemical Technology) ;
  • Choi, Kil-Yeong (Reliability Assessment Center for Chemical Materials Korea Research Institute of Chemical Technology) ;
  • Weon, Jong-Il (Reliability Assessment Center for Chemical Materials Korea Research Institute of Chemical Technology)
  • 조인희 (한국화학연구원 신뢰성평가센터) ;
  • 형신종 (한국화학연구원 신뢰성평가센터) ;
  • 최길영 (한국화학연구원 신뢰성평가센터) ;
  • 원종일 (한국화학연구원 신뢰성평가센터)
  • Received : 2009.01.09
  • Accepted : 2009.02.23
  • Published : 2009.04.10

Abstract

The failure analysis of scales deposited on automotive thermostat housing has been carried out. Observations using energy dispersive spectroscopy and electron probe micro analyzer indicate that the main components of scales are some of additives of coolant used. For a detailed investigation of organic matters pyrolysis-GC/MS is employed. The result shows that the main organic component is benzoic acid and furthermore, a small amount of acetophenone, benzene and phenyl group is detected. Based on the results of failure analysis performed, the scales on automotive thermostat housing appear due to the deposition of coolant components, followed by crevice corrosion, into gap between housing and rubber horse. New accelerated test methodology, which could mimic the scale formation and the crevice corrosion on thermostat housing, is developed considering the above results. In order to reproduce the real operating conditions, the accelerating factors, i.e. temperature and humidity, are changed and programmed. The reproducibility of the accelerated test proposed is confirmed after analyzing the scales obtained from the accelerated test.

Acknowledgement

Supported by : 지식경제부

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