• Tribology and Lubricants
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• v.25 no.6
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• pp.432-437
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• 2009

The effect of oxidation in SAE 5W30 engine oils on friction and wear characteristics was investigated using reciprocating bench tester and shell 4-ball tester. Commercial engine oils were collected and oxidized using the KS M 2021 method modifying the oxidation time. Kinematic viscosity, total acid number(TAN), FT-IR spectrum and total base number(TBN) also measured to examine the chemical change of oils with oxidation. The results showed that TAN was slightly changed and Kinematic viscosity was suddenly increased during the oxidation stage. however, TBN results keep a constant slope after TBN linearly decreased with oxidation time. Spectroscopy results showed that spectrums were orderly increased at $1710cm^{-1}$ during the oxidation time. Friction test results showed that oxidation of oils formed unstable friction layers causing higher fluctuating friction. however, the wear resistance was independent of oxidized time due to the different friction characteristics by oxidation. We found several factors in relation to lubrication properties with oxidation time. This factors were Viscosity, TBN, change of FT-IR spectrum, friction coefficient using reciprocating bench tester and wear scar.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2000.05a
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• pp.17-17
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• 2000

• Proceedings of the Materials Research Society of Korea Conference
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• 1992.05a
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• pp.114-114
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• 1992

• Proceedings of the Korean Nuclear Society Conference
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• 2002.05a
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• pp.442.1-442
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• 2002

• Journal of Welding and Joining
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• v.29 no.5
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• pp.16-23
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• 2011

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 1999.05a
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• pp.119-120
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• 1999

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 1999.05a
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• pp.11-12
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• 1999

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2009.10a
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• pp.204-204
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• 2009

• Journal of the Korean institute of surface engineering
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• v.45 no.2
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• pp.61-69
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• 2012

Alloys of Fe-(5, 10, 15)Al and Fe-(10, 20, 30, 40)Cr were corroded at 700 and $800^{\circ}C$ for 70 hr in either atmospheric air or 1 atm of Ar+$1%SO_2$ gases. In these atmospheres, Fe-5Al and Fe-10Cr alloys displayed poor corrosion resistance. In atmospheric air, Fe-5Al alloys formed oxide nodules, while Fe-10Cr alloys formed thick scales and internal oxides. In Ar+$1%SO_2$ gases, Fe-5Al and Fe-10Cr alloys formed thick, nonadherent bi-layered scales, which grew primarily by the outward diffusion of Fe ions and inward diffusion of oxygen and sulfur ions. By contrast, in atmospheric air and Ar+$1%SO_2$ gases, Fe-(10, 15)Al and Fe-(20, 30, 40)Cr alloys displayed good corrosion resistance by forming $Al_2O_3$ and $Cr_2O_3$ layers on the surface, respectively.

• Korean Journal of Metals and Materials
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• v.48 no.8
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• pp.724-729
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• 2010

The effect of potassium permanganate ($KMnO_4$) in an electrolyte on the corrosion performance of magnesium alloy coated by micro-arc oxidation (MAO) has been investigated in this study. For this purpose, MAO coating was carried out on the present sample under AC condition in an alkaline silicate electrolyte with and without $KMnO_4$. Irrespective of the addition of $KMnO_4$, it was found from structural observation that the ceramic coating layers consisted of inner and outer layers. In the sample processed in the electrolyte with $KMnO_4$, the outer layer became dense and even contained a number of $Mn_2O_3$ atoms, resulting in high corrosion resistance. Based on the results of a potentiodynamic polarization test, it was confirmed that the coating layer formed in the electrolyte with $KMnO_4$exhibited better corrosion resistance than that without $KMnO_4$. The high corrosion resistance of the MAO-treated magnesium alloy was explained in relation to the equivalent circuit model.