{"title":"Bimodal trending in corrosion loss of magnesium alloys","authors":"R. Melchers","doi":"10.5006/4548","DOIUrl":null,"url":null,"abstract":"\n Data for mass loss of a variety of magnesium alloys as a function of exposure period show that corrosion loss follows bimodal trending with time for different exposure environments, both laboratory and field support these findings. For data sets sufficient to discriminate bimodal behaviour, the instantaneous rate of corrosion at the commencement of the second mode is (close to) 4 times the instantaneous rate of corrosion at the end of the first mode (i.e. through the transition period). This observation is consistent with the theoretical relative diffusivities of oxygen and hydrogen through the corrosion product layer as it exists during the transition period. These findings support the notion that the bimodal model has corrosion in Mode 1 rate-controlled by the cathodic oxygen reduction reaction and the inward diffusion of oxygen while in Mode 2 corrosion is rate-controlled by the cathodic hydrogen evolution reaction and the outward diffusion of hydrogen. Similar findings have been made previously for various ferrous and other alloys and thus throws new light on the development of corrosion of magnesium alloys. It also provides reasons for measurements of hydrogen evolution and for electrochemical techniques underestimating magnesium corrosion rates. A new procedure for combining these is proposed.","PeriodicalId":10717,"journal":{"name":"Corrosion","volume":null,"pages":null},"PeriodicalIF":1.1000,"publicationDate":"2024-07-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Corrosion","FirstCategoryId":"88","ListUrlMain":"https://doi.org/10.5006/4548","RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q4","JCRName":"MATERIALS SCIENCE, MULTIDISCIPLINARY","Score":null,"Total":0}
引用次数: 0
Abstract
Data for mass loss of a variety of magnesium alloys as a function of exposure period show that corrosion loss follows bimodal trending with time for different exposure environments, both laboratory and field support these findings. For data sets sufficient to discriminate bimodal behaviour, the instantaneous rate of corrosion at the commencement of the second mode is (close to) 4 times the instantaneous rate of corrosion at the end of the first mode (i.e. through the transition period). This observation is consistent with the theoretical relative diffusivities of oxygen and hydrogen through the corrosion product layer as it exists during the transition period. These findings support the notion that the bimodal model has corrosion in Mode 1 rate-controlled by the cathodic oxygen reduction reaction and the inward diffusion of oxygen while in Mode 2 corrosion is rate-controlled by the cathodic hydrogen evolution reaction and the outward diffusion of hydrogen. Similar findings have been made previously for various ferrous and other alloys and thus throws new light on the development of corrosion of magnesium alloys. It also provides reasons for measurements of hydrogen evolution and for electrochemical techniques underestimating magnesium corrosion rates. A new procedure for combining these is proposed.
期刊介绍:
CORROSION is the premier research journal featuring peer-reviewed technical articles from the world’s top researchers and provides a permanent record of progress in the science and technology of corrosion prevention and control. The scope of the journal includes the latest developments in areas of corrosion metallurgy, mechanisms, predictors, cracking (sulfide stress, stress corrosion, hydrogen-induced), passivation, and CO2 corrosion.
70+ years and over 7,100 peer-reviewed articles with advances in corrosion science and engineering have been published in CORROSION. The journal publishes seven article types – original articles, invited critical reviews, technical notes, corrosion communications fast-tracked for rapid publication, special research topic issues, research letters of yearly annual conference student poster sessions, and scientific investigations of field corrosion processes. CORROSION, the Journal of Science and Engineering, serves as an important communication platform for academics, researchers, technical libraries, and universities.
Articles considered for CORROSION should have significant permanent value and should accomplish at least one of the following objectives:
• Contribute awareness of corrosion phenomena,
• Advance understanding of fundamental process, and/or
• Further the knowledge of techniques and practices used to reduce corrosion.