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Crevice Corrosion Accelerated Test for Cylinder Head/Gasket/Monoblock Assemblies from Lightweight Engines Considering Overheating Effects

Tecnologico de Monterrey, EIC, Puebla-Leonardo Farfan-Cabrera
Instituto Politecnico Nacional Esime Zac-Gerardo Rodríguez-Bravo, Roberto Vega-Moron
  • Technical Paper
  • 2020-01-1067
To be published on 2020-04-14 by SAE International in United States
Severe crevice corrosion occurring at the joint of cylinder head/gasket/mono-block from lightweight engines causes accelerated dissolution of lightweight material, in particular, in the cylinder head. It facilitates the linking of cooling vessels with the combustion chambers or oil vessels in both the cylinder head and monoblock. It is conductive to combustion of coolant or oil, and contamination of oil with coolant or vice versa, which is considered as catastrophic engine failure. Since crevice corrosion is dependent of assembly characteristics, coolant and engine operation conditions, full-scale tests are the most frequent alternative for this type of evaluations. Nonetheless, they are very long and expensive, and sometimes, unreliable. Alternatively, the standard procedure ASTM-G78 is widely used to evaluate accelerated crevice corrosion of different metallic materials under certain specified immersion conditions using a corrosive media. However, this method does not cover the characteristics and conditions existing at the cylinder head/gasket/mono-block joint. This paper presents an accelerated test consisting on three-electrode cyclic potentiodynamic anodic polarization and polarization resistance standard tests using special assembly samples to replicate the actual cylinder…
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Tribological Performance of an Engine Mineral Oil Blended with a Vegetable Oil under Approached Long-Term Use Conditions

Tecnologico de Monterrey, EIC, Puebla-Leonardo Israel Farfan-Cabrera
Instituto Politecnico Nacional Esime Zac-Ezequiel Gallardo, Mario Gómez-Guarneros, Andys Hernandez Peña
Published 2019-01-15 by SAE International in United States
It has widely reported that tribological performance of engine mineral oils (EMOs) can be improved by blending them with vegetable oils (VOs) in certain concentrations. Nonetheless, bio-oils are more susceptible to oxidation than EMOs by thermal ageing, which could be a drawback when they are used in engines comprising high variations of temperature. In this paper, a comparative analysis of tribological performance of an EMO and a blend made of 80%vol. of EMO and 20%vol. of a VO in fresh and aged conditions is given. The VO selected for the blend was Jatropha oil since various advantages reported in literature. EMO and B20 were thermally aged in laboratory approaching actual oxidation and additives depletion caused in EMO used in a car for 7500 km. The effects of ageing on the oils were evaluated by means of oxidation (PAI value), Zinc dialkyldithiophosphates (ZDDPs) depletion and viscosity. The tribological performance of the oils was determined by measuring the friction coefficients and wear rates generated in samples from engine cylinder liners in a pin-on-disk tester under boundary lubrication…
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