Corrosion characteristics of NdFeB sintered magnets containing various alloying elements

Bala, H.; Pawłowska, G.; Szymura, S.; Sergeev, V. V.; Rabinovich, Yu. M.

doi:10.1016/0304-8853(90)90757-h

Cited by 68 publications

(30 citation statements)

References 14 publications

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“…On other hand, the increased electrode potential reduces the electrochemical potential difference between the rare earth-rich phase and the matrix phase, leading to the lower anodic current density. Bala [18] offered similar explanation on the improved corrosion resistance for Cr-doped Nd-Fe-B alloy.…”

Section: Resultsmentioning

confidence: 67%

Magnetostriction and corrosion resistance of Tb0.3Dy0.7(Fe1−Si )1.95 alloys

Jiang

Zhou

et al. 2008

Journal of Alloys and Compounds

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Section: Resultsmentioning

confidence: 67%

Magnetostriction and corrosion resistance of Tb0.3Dy0.7(Fe1−Si )1.95 alloys

Jiang

Zhou

et al. 2008

Journal of Alloys and Compounds

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“…[24][25][26] It was also reported that Zr and Ni additions help improving corrosion resistance owing to the disappearance of free Nd metal, associated with the eutectic composition. Bala et al 17 reported that a 1 at.-%Cr addition is the most advantageous both in acid and atmospheric corrosion processes. However, the addition of Cr accelerates the dissolution of the magnet at strongly cathodic polarisation potentials.…”

Section: Influence Of Alloying Elementsmentioning

confidence: 99%

Corrosion characteristics of Nd–Fe–B permanent magnets in different environments

Gurrappa¹,

Pandian²

2006

Corrosion Engineering, Science and Technology

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The corrosion behaviour of Nd-Fe-B, a permanent magnetic alloy, has been studied in two different solutions chosen to simulate the effects of marine and industrial environments. The results showed that the corrosion rate of the alloy was about nine times higher in the simulated industrial (sulphate) environment when compared to the marine (chloride) environment. The studies also revealed that the alloy could not form a protective layer on its surface in either of the environments studied, but was resistant to pitting corrosion. Scanning electron microscopy results indicated that the magnetic alloy undergoes preferential grain boundary corrosion in both environments although the corrosion rate varies considerably. A sequence of steps that result in the loss of magnetic properties under corrosive conditions has been proposed. Furthermore, the effect of alloying elements on the corrosion behaviour and magnetic properties of the alloy was also discussed. The importance of surface engineering techniques for improving the corrosion resistance of Nd-Fe-B permanent magnets was highlighted and a suitable surface coating system was proposed.

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“…E Nd3+/Nd = -2.43 V) [4,12]. As many authors indicate [4,[12][13][14][15][16], in most acidified environments the Nd-Fe-B type material dissolves activationally, which is particularly undesired. However, in acidified phosphate solution, as well as in neutral and alkaline solutions the magnets effectively passivate.…”

Section: Introductionmentioning

confidence: 99%

The Effect of Powder Particle Biencapsulation with Ni-P Layer on Local Corrosion of Bonded Nd-(Fe,Co)-B Magnetic Material

Klimecka-Tatar¹,

Pawłowska²,

Sozańska³

2015

Archives of Metallurgy and Materials

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Effect of the Nd-(Fe,Co)-B powder particle biencapsulation with Ni-P layer on bonded magnetic materials corrosion behaviour has been investigated. Bonded magnets were prepared from single-phase, nanocrystalline magnetic Nd 11 Fe 77 Co 5 B 6 powder. Powder particles before consolidation were preliminary etched and then coated with bilayer (powder biencapsulation). The powder surface was coated as a first with autocatalytic applied Ni-P layer during 5, 15 and 30 minutes in Ni(II) containing bath and the second layer was thermosetting epoxy-resin. Impact of the used biencapsulation process was rated on the basis of polarization curves recorded in phosphate environment with addition of chloric ions. It has been established that the used biencapsulation method satisfactorily isolate individual particles of the powder and consequently, significantly inhibits corrosion processes of the final material, especially in passivating environment containing Cl − . Keywords: Nd-Fe-B bonded magnets, biencapsulation, local corrosion, Ni-P layer W pracy zaprezentowano wyniki badań nad wpływem bienkapsulacji cząstek proszku powłokami Ni-P/żywica epoksydowan na odporność korozyjną magnesów wiązanych. Materiały magnetyczne zostały przygotowane z jednofazowego, nanokrystalicznego proszku Nd 11 Fe 77 Co 5 B 6 . Cząstki proszku przed konsolidacją były wstępnie trawione, a następnie pokryte podwójną warstwą (bienkapsulacja proszku). Powierzchnia proszku w pierwszej kolejności została poddana 5 i 30 minutowemu autokatalitycznemu nanoszeniu warstw Ni-P. Drugą warstwę stanowił materiał spoiwa, czyli żywica epoksydowa. Dokonano oceny wpływu zastosowanej metody bienkapsulacji na odporność na korozję lokalną na podstawie krzywych polaryzacji zarejestrowanych w środowisku fosforanowym (0,5M, pH = 3) z dodatkiem jonów chlorowy. Stwierdzono, że zastosowane metody bienkapsulacji zadowalająco izolują pojedyncze cząstki proszku, a co za tym idzie, hamują proces korozji materiału końcowego, zwłaszcza w środowisku pasywującym zawierającym Cl − .

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Corrosion characteristics of NdFeB sintered magnets containing various alloying elements

Cited by 68 publications

References 14 publications

Magnetostriction and corrosion resistance of Tb0.3Dy0.7(Fe1−Si )1.95 alloys

Magnetostriction and corrosion resistance of Tb0.3Dy0.7(Fe1−Si )1.95 alloys

Corrosion characteristics of Nd–Fe–B permanent magnets in different environments

The Effect of Powder Particle Biencapsulation with Ni-P Layer on Local Corrosion of Bonded Nd-(Fe,Co)-B Magnetic Material

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