Korrosion av kopparlegeringar i RME: Parameterstudie och legeringstester
Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
Biodiesels are a hot topic and this includes the diesel replacement rapeseed methyl ester (RME). However, there is some concern because some metals may accelerate the degradation of RME. RME also causes corrosion of some metals. Copper, which accelerates degradation the most, can be found in engine system. Therefore, the aim of this Master’s thesis was to evaluate the corrosion of copper and different copper alloys in RME. In the experimental part, evaluation was made by analyzing water content, concentration of formic acid, acetic acid and propionic acid, metal concentrations in the fuel, oxidative stability (time until degradation with Rancimat method), macroscope of metallic surface and surface analysis by FTIR. The studied alloys included copper, brass, and aluminum alloyed with 3.2 weight % copper. A stable period for copper corrosion was observed through the copper levels in the fuel. The stable period was confirmed to be related to the properties of the material. Most likely, a protective layer consisting of corrosion products was formed on the copper surface. Formic acid and free water addition increased corrosion and prevented a stable period. Salt formation was observed when decreasing copper and acid levels and was confirmed by FTIR analysis on exposed copper. Brass accelerated the aging of B100 fuel, but to a less extent than pure copper and indicated a stable period. Aluminum did not accelerate the aging of B100 fuel in this experiment. The evaluation method proposed for copper involved measuring copper concentration as an indicator for when the corrosion has passed by the stable period. In these bench scale experiment which used 250 ml B100 and 40 cm2 area copper, the threshold was 5 mg Cu/kg B100. This method may potentially also be used for copper alloys. The knowledge that there is a stable period can be used in field tests (engines) to understand the behaviour of corrosion of copper and to design a stable window. Important to remember is that copper corrosion behaviour can be drastically different in field tests (engines) compared to the lab scale experiments performed in this Master's thesis. This because of different temperature, flow patterns, additional factors, etc. The stable period of brass needs to be confirmed with longer aging times with B100 fuel. The additions of formic acid and free water to both brass and aluminum will need to be studied to see if they exhibit the same behaviour as copper. Other metals should be studied to see if the also exhibit a stable corrosion period similar to copper.
Place, publisher, year, edition, pages
2015. , 69 p.
Teknik, korrosion, koppar, metall, mekanism, bettende, resistans, aluminium, mässing, syra, vatten, myrsyra, B100, B 100, RME, biobränsle, diesel, bil, motor, omättad, fleromättad, instabil, nedbrytning, oxiderar, accelererar, testmetod, åldring
IdentifiersURN: urn:nbn:se:ltu:diva-50453Local ID: 7b739905-cc3e-4744-9758-99a9a7133ad4OAI: oai:DiVA.org:ltu-50453DiVA: diva2:1023812
Subject / course
Student thesis, at least 30 credits
Sustainable Process Engineering, master's level
Validerat; 20150807 (global_studentproject_submitter)2016-10-042016-10-04Bibliographically approved