Influence of Engine Coolant Composition on the Electrochemical Degradation Behavior of EPDM Radiator Hoses

Vroomen, G.L.M.; Lievens, Serge; Maes, Jos

doi:10.1520/stp38246s

Cited by 1 publication

(6 citation statements)

References 2 publications

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“…The ECD of the rubber skin was mainly associated with the sulphoxide conversion and scission of sulphur cross-links by the attack of the many hydrogen peroxide anions produced in the coolant water medium containing oxygen. 12, 13, 18, 19 An important phenomenon of the ECD was the penetration of the coolant liquid into the microhole networks in the broken carbon-black phases and/or in the failed rubber matrix, leading to the softening and the swelling of the specimen gauge portion. Thus, the aged skin initiating from the surface absorbed a considerable amount of the coolant liquid, which obviously contrasted with the other core region.…”

Section: Resultsmentioning

confidence: 99%

“…RS n O 3 –) conversion and scission of sulphur cross-links (e.g. R–S–S–R) owing to the attack by the many hydrogen peroxide anions (HO 2 –) that were produced in the coolant water medium containing oxygen because of the formation of a galvanic cell circuit between the positive pole at the carbon-black phase in a rubber matrix and the negative pole at the metal part, 13–15, 18, 19 as illustrated in Figure 1. Following the principle of ECD, we constructed an ECD tester for rubber specimens immersed in a coolant liquid which is kept at a preset temperature, as schematically shown in Figure 2.…”

Section: Methodsmentioning

confidence: 99%

“…Vroomen and co-workers 12, 13 investigated the ECD behaviours of EPDM rubber hoses from an electrical conductivity viewpoint and clarified that the ECD was caused by the formation of a galvanic cell mainly arising in the rubber hose carrying the coolant water around the fitting parts of the engine. The carbon part in the skin of the rubber hose and the metal part of the engine body formed a galvanic couple generating the ECD; the carbon was the anode, and the metal was the opposite cathode.…”

Section: Introductionmentioning

confidence: 99%

“…Using a similar experimental tester, Lucchi 14 demonstrated that the carbon-black loading and type played important roles in the ECD of EPDM rubbers. Vroomen et al 13 and Kwak et al 15 reported that the coolant type had a considerable effect on the degree of ECD of the rubber hoses. Kwak et al 7 further performed ageing tests on EPDM rubber specimens on the basis of the international standards SAE J1684:2000 11 and ISO 188:2011.…”

Section: Introductionmentioning

confidence: 99%

“…Since the radiator hoses convey coolant liquid from and to the automotive engine to maintain the longevity of the automotive engine, an EPDM hose failure may occur owing to electrochemical degradation (ECD) on the inner surface, 7,[9][10][11][12][13] in addition to the thermal oxidation along the outer surface. The failure leads to leakage of the cooling system caused by cracks formed in the inner skin of EPDM hoses.…”

Section: Introductionmentioning

confidence: 99%

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Electrochemical degradation tests on a carbon-black-filled ethylene propylene diene monomer rubber under tensile strain

Han

Choi

2017

Proceedings of the Institution of Mechanical Engineers, Part D:

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Rubber hoses play an important role as a path for carrying the coolant liquid between the radiator and the automotive engine. However, the rubber hoses are apt to deteriorate because of the formation of a galvanic circuit between the rubber hose, the coolant water and the fitting metal part of the engine. Such electrochemical degradation can damage the inner skin of the hose in contact with the coolant liquid heated by the working engine, which often leads to leakage of the coolant water and thereby to hose failure. An ethylene propylene diene monomer rubber has mostly been utilized as the material for the coolant hoses of automotive engines because of the strong resistance to various environmental stresses. This study conducted experimental simulation tests and evaluation of the electrochemical degradation behaviours of the carbon-black-filled ethylene propylene diene monomer rubber used for the coolant hoses. The tests were performed by considering the actual circumstances together with the combined thermal, tensile strain and electrostatic voltage loadings on the rubber hoses. The behaviour of the change in the electrical resistance of a specimen and, thus, the apparent decrease in the current were analysed quantitatively. An Arrhenius life prediction by using the decrease in the current was reasonably expressed for the accelerated life tests. Many microhole networks were thus formed in the skin part of the specimen by the microbreaks in the carbon-black phase and the scission of the sulphur cross-links. The coolant liquid penetrated significantly into the skin, which resulted in a considerable swelling of the skin. The larger the strain application to the rubber, the lower are the strength and the elongation at the breaking point. An exponential index parameter can represent quantitatively the behaviours of the decreases in the mechanical properties used for accurate life prediction.

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Section: Resultsmentioning

confidence: 99%