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Journal of the Korean Ceramic Society 1998;35(2): 163. |
Ceramic 재질을 이용한 자동차용 대형 디젤 엔진 Valve Lifter 연구 I. Brazing Process에 의한 Ceramic-Metal 접합체 개발 |
윤호욱, 한인섭1, 임연수2, 정윤중2 |
KIA-ASIA MOTORS 기술연구소 1한국에너지기술연구소 2명지대학교 공과대학 무기재료공학과 |
Studies of Valve Lifter for Automotive Heavy Duty Diesel Engine by Ceramic Materials I. Developmet of Ceramic-Metal Joint by Brazing Method |
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ABSTRACT |
Continuously contacting with camshaft the face of Valve Lifter made of cast iron brings about abnormal wear such as unfairwear or earlywear because it is heavily loaded in the valve train systems as the engine gets more powered. This abnormal wear becomes a defet namely over-clearance when the valve is lifting so that the fuel gas imperfectly combusted by unsuitable open or close aaction of the engine valve in the combustion chamber. The imperfect combustion in the end results in the major cause of air pollution and combustion chamber. The imperfectly combusted by unsuitable open or close action of the engine valve in the combustion chamber. The imperfect combustion in the end results in the major causes of air pollution and decrease of the engine output. Consequently to prevent this wear this study was to develop the valve lifter which is joined by brazing process with SCM435H and a tip by manufacturing the face as a superhardened which is joined by brazing process with SCM435H and a tip by manufacturing the face as a superhardened ceramics alloy which has high wear resistance. Having the excellent surface hardness with Hv1100-1200 the sintered body developed with superhardened alloy(WC) can endure the severe face loading in the valve train system. We experienced with various brazing alloys and obtained the excellent joining strength to the joint had 150MPa shear strength. Interface analysis and microstructure in a joint were examined through SEM & EDS Optical microscope. Also 2,500 hours high speed(3,000-4,000 rpm) and continuous (1step 12hr) engine dynamo testing was carried out to casting valve liter and ceramics-metal joint valve lifter so that the abnormal wears were compared and evaluated. |
Key words:
Valve train system, Ceramic valve lifer, Ceramic / metal joint by brazing |
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