Exhaust valve and valve seat with same weld deposit materials were used in a marine diesel engine. After a long period of operation,the exhaust valve and seat ring wore slightly,no obvious adhesive wear was found. By observing the morphology of the worn surface and analyzing the composition of the micro-area,the wear mechanism of the exhaust valve and valve seat matching scheme was explored. Research shows that:Combustion exhaust gas forms a deposition film on the sealing conical surface of the exhaust valve,which reduces the tendency of friction pairs to experience adhesive wear by isolating the sealing surface and solid lubrication;Under the alternating stress of seating and combustion pressure,the wear mechanism of the weld deposit layer on the conical surface of the exhaust valve is mainly fatigue peeling, while the wear mechanism of the weld deposit layer on the conical surface of the exhaust valve seat is slow abrasion caused by polishing.
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