Applied Chemistry for Engineering (공업화학)

The Korean Society of Industrial and Engineering Chemistry (한국공업화학회)
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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
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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.

자동차용 써모스타트 하우징 피팅부상의 침전물(스케일)에 대한 고장분석을 실시하였다. 에너지분산형분석기와 전자현미분석기를 이용하여 침전물이 부동액의 주요 첨가제 성분임을 확인하였다. 자세한 유기성분 분석을 위해 열분해 기체크로마토그래피/질량분석을 수행한 결과, 침전물의 주성분이 벤조산이며, 소량의 아세토페논, 벤젠 및 페닐계 화합물 등으로 이루어져 있음을 확인하였다. 더불어 침전물 생성 원인은 알루미늄 하우징과 고무호스 사이에 존재하는 틈새 공간에 부동액 성분의 침전에 따른 틈새부식에 기인한 것으로 판단된다. 이런 결과를 바탕으로 하여 써모스타트 하우징상의 침전물 생성과 틈새부식을 재현할 수 있는 가속시험기법을 개발하였다. 가속인자(온도, 습도)를 변화시키면서 실제 가동조건을 묘사하였다. 가속시험에서 얻은 침전물을 성분 분석을 통해 완벽히 재현되었음을 확인하였다.

Keywords

Acknowledgement

Supported by : 지식경제부

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