Proceedings of SerbiaTrib '13

Serbian TribologySocietySERBIATRIB ‘1313 th International Conference onTribologyKragujevac, Serbia, 15 – 17 May 2013Faculty of Engineeringin KragujevacANALYSIS OF THE SURFACE LAYER FORMATION OF SINGLECYLINDER ENGINE COMBUSTION CHAMBER WITHPHOSPHOROUS-FREE AND CONVENTIONAL ENGINELUBRICANTSL.YÜKSEK 1* , H.KALELİ 2 , D.ÖZKAN 3 , H. HACIKADİROĞLU 31 Researcher Dr., Yıldız Technical University, Faculty of Mechanical Engineering, Automotive Division34349 Beşiktaş-İstanbul/TURKEY, lyuksek@yildiz.edu.tr2 Professor Dr., Yıldız Technical University, Faculty of Mechanical Engineering, Automotive Division34349 Beşiktaş-İstanbul/TURKEY, kaleli@yildiz.edu.tr3 PhD. Student, Yıldız Technical University, Faculty of Mechanical Engineering, Energy Division34349 Beşiktaş-İstanbul/TURKEY, dogus_ozkan@hotmail.com*Corresponding author.Abstract: Phosphorus-free engine lubricants are gaining importance for preventing catalyst poisoningwhich is the major deactivation mechanism that causes three-way catalyst malfunction. The main purpose ofthis paper is to evaluate the mechanism of surface layer formation in combustion chamber of spark ignitionengines with phosphorous-free and phosphorous containing mineral engine lubricants. An experimentalendurance test was conducted for 100 hours at equal load conditions for each lubricant. Endurance testswere run with a laboratory engine test bench. Subsequently, engines dismantled and cylinder liners were cutaccurately to obtain specimens for microscopic examination. Optical microscopy, scanning electronmicroscopy and energy dispersive X-ray spectroscopy methods were used for evaluation.Elemental measurements on the surface which were obtained by X-ray spectroscopy were examinedstatistically. Results of the experiments showed that phosphorous containing lubricant deposited morecarbon and oxygen although less manganese and silica than the phosphorous containing rival. After the X-ray spectroscopy of the combustion chamber surface at top dead centre, iron element composition of thephosphorus-free lubricant was notably higher than phosphorus containing oil.Keywords: Phosphorous-free Oil, Combustion chamber, X-ray spectroscopy, Additive layer formation,Cylinder liner1. INTRODUCTIONMechanical losses are responsible for theapproximately 10-15% fuel energy loss. Half of themechanical losses are generated by the frictionbetween piston rings and cylinder liner. Therefore,the performance of the piston ring and cylinderliner tribological pair is the indicator of theperformance and the lifespan of an internalcombustion engine [1]. Particularly, wear aroundtop dead centre is the main limiter of effectiveengine life. Piston rings are intended to maintainthe dynamic sealing between crankcase and thecombustion chamber which minimize the powerlosses caused by the blow-by mass transfer throughthe crankcase during expansion stroke [2]. Successof this sealing mainly depends on the wear rate ofring and liner pack which are primarily the functionof the formed tribofilm on ring and liner surfaces.Engine lubricants are formulated to generate andsustain the protection against wear whilelubrication, cooling and cleaning of the surfaces arealso expected from lubricant. Modern enginelubricant can satisfy these demands with chemicalcompounds like anti-wear additives, anti-oxidantadditives, dispersants, detergents etc. [3]. Additivesalso enhance the chemical composition of baselubricant [4].98 13 th International Conference on Tribology – Serbiatrib’13