In operando stability tests of La(FeMnSi)13Hy regenerators
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School of Chemical Engineering |
Master's thesis
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Authors
Date
2024-08-28
Department
Major/Subject
Functional Materials for Global Challenges
Mcode
Degree programme
Master's Programme in Advanced Materials for Innovation and Sustainability
Language
en
Pages
58
Series
Abstract
Magnetocaloric cooling represents a chance for the cooling sector to transform into a more sustainable future. Higher theoretical efficiency, no use of a (toxic, flammable, ozone-depleting, global-warming) refrigerant, and less noise are the main reasons this technology is widely considered the most promising cooling technology for a sustainable future, being able to beat the efficiency of vapor-compression systems using available materials, and being almost market ready. Considering performance, price, and criticality, regenerators (the solid magnetocaloric components) based on hydrogenated and Mn-substituted La(Fe,Si)13 alloys are the best commercially available option. However, the brittle intermetallic alloys experience magnetostriction during in-device use, leading to fracture. Also, the alloy is subject to oxidation and passivates poorly, especially in contact with water, the targeted heat exchange medium. La(Fe,Mn,Si)13Hy-based regenerators are, therefore, prone to corrosion which can ultimately lead to device failures. While aspects of corrosion protection have already been explored, experiments in application-oriented scenarios still need to be completed. This work outlines an economical, scalable, and efficient two-fold corrosion protection strategy. A uniform electroless applied Cu coating working with a tailored inhibitor mixture shows no signs of corrosion after six weeks of in operando testing, provided that a suitable geometry for the regenerator is used. With magnetocaloric cooling devices on the brink of commercialization, this work represents one more brick in paving the way to a sustainable cooling industry.Description
Supervisor
Karttunen, AnttiThesis advisor
Münch, FalkZwick, Jens-Peter
Keywords
LaFeSi, functional materials, coatings, electroless plating, copper, corrosion, magnetic cooling