In operando stability tests of La(FeMnSi)13Hy regenerators

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master_Weiß_Nico_Philipp_2024.pdf (8.1 MB)

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School of Chemical Engineering | Master's thesis
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Date

2024-08-28

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Functional Materials for Global Challenges

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Master's Programme in Advanced Materials for Innovation and Sustainability

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en

Pages

58

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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.

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Supervisor

Karttunen, Antti

Thesis advisor

Münch, Falk
Zwick, Jens-Peter

Keywords

LaFeSi, functional materials, coatings, electroless plating, copper, corrosion, magnetic cooling

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https://urn.fi/URN:NBN:fi:aalto-202411217265

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[dipl] Kemian tekniikan korkeakoulu / CHEM