Role of microstructure on corrosion initiation of an experimental tool alloy: A Quantitative Nanomechanical Property Mapping study

Álvarez-Asencio, Rubén; Sababi, Majid; Pan, Jinshan; Ejnermark, Sebastian; Ekman, Lars; Rutland, Mark W.

doi:10.1016/j.corsci.2014.08.028

Cited by 7 publications

(3 citation statements)

References 35 publications

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“…Each pixel in such an image represents the output parameters of a contact mechanical fit to the interaction of the tip with surface on approach and separation. From these graphs, obtained within each pixel of the image, mechanical properties such as modulus, deformation, and adhesion can be calculated and imaged, together with sample topography. ,, Prior to measurement, samples were preloaded in 7.5 μM peptide solution as described above. Silicon nitride cantilevers (ScanAsyst-Fluid + , Bruker, Santa Barbara, U.S.A.), with silicon tips of a nominal radius of 2 nm and spring constants ranged between 0.4 and 0.7 N m –1 , were used throughout, calibrated according to a procedure described elsewhere .…”

Section: Experimental Sectionmentioning

confidence: 99%

Factors Affecting Peptide Interactions with Surface-Bound Microgels

et al. 2016

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Effects of electrostatics and peptide size on peptide interactions with surfacebound microgels were investigated with ellipsometry, confocal microscopy, and atomic force microscopy (AFM). Results show that binding of cationic poly-L-lysine (pLys) to anionic, covalently immobilized, poly(ethyl acrylate-co-methacrylic acid) microgels increased with increasing peptide net charge and microgel charge density. Furthermore, peptide release was facilitated by decreasing either microgel or peptide charge density. Analogously, increasing ionic strength facilitated peptide release for short peptides. As a result of peptide binding, the surface-bound microgels displayed pronounced deswelling and increased mechanical rigidity, the latter quantified by quantitative nanomechanical mapping. While short pLys was found to penetrate the entire microgel network and to result in almost complete charge neutralization, larger peptides were partially excluded from the microgel network, forming an outer peptide layer on the microgels. As a result of this difference, microgel flattening was more influenced by the lower Mw peptide than the higher. Peptide-induced deswelling was found to be lower for higher Mw pLys, the latter effect not observed for the corresponding microgels in the dispersed state. While the effects of electrostatics on peptide loading and release were similar to those observed for dispersed microgels, there were thus considerable effects of the underlying surface on peptide-induced microgel deswelling, which need to be considered in the design of surface-bound microgels as carriers of peptide loads, e.g., in drug delivery or in functionalized biomaterials.

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Section: Experimental Sectionmentioning

confidence: 99%

Factors Affecting Peptide Interactions with Surface-Bound Microgels

et al. 2016

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“…[13][14][15][16] The Volta potential is a material intrinsic property and is involved in any chemical or electrochemical reaction and reflects the electrochemical nobility of microstructure constituents, with higher potentials often indicating higher nobilities. [13][14][15][17][18][19][20][21][22][23] However, SKPFM measured Volta potentials cannot be directly used to predict localized corrosion phenomena since information about the electrochemical double layer and kinetic information about electrochemical reactions are missing. Nevertheless, the Volta potential parameter, as introduced by Frankel et al 16 and later its limitations discussed by Rohwerder et al 24 with relevance for corrosion science, 25 can be useful to better understand local corrosion phenomena such as micro-galvanic coupling between microstructure constituents in micrometer scale.…”

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confidence: 99%

Correlative Microstructure Analysis and In Situ Corrosion Study of AISI 420 Martensitic Stainless Steel for Plastic Molding Applications

Anantha

Örnek

Ejnermark³

et al. 2017

J. Electrochem. Soc.

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In this work, the corrosion behavior of tempered AISI 420 martensitic stainless steel (MSS) was studied by in-situ atomic force microscopy (AFM) in 0.1 M NaCl and correlated with the microstructure. Thermocalc simulation, dilatometry, and X-ray diffraction (XRD) were performed to investigate phase transformation which showed the formation of M 3 C, M 7 C 3 , and M 23 C 6 type of carbides and also retained austenite. Optical microscopy, scanning electron microscopy (SEM), and AFM characterization revealed undissolved carbides and tempering carbides in the martensitic matrix. Volta potential mapping measured by scanning Kelvin probe force microscopy (SKPFM) indicated higher electrochemical (practical) nobility of the carbides with respect to the martensitic matrix whereas regions adjacent to carbides showed lower nobilities due to chromium depletion. Open circuit potential and cyclic potentiodynamic polarization measurements showed metastable corrosion activities associated with a weak passive behavior and a risk for localized corrosion along certain carbide boundaries. In-situ AFM measurements revealed selective dissolution of certain carbide interphases and martensitic inter-lath regions indicating higher propensity to localized corrosion.

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“…7, the surface potential fluctuations are obvious, the maximum potential contrast was approximately 400 mV, which is sufficient to distinguish different regions by the surface potential distribution. Greater corrosion occurs in a lower-potential area 19,[22][23][24][25] ; thus, the fluctuating surface potentials indicate areas with different levels of corrosion resistance. From Fig.…”

Section: Resultsmentioning

confidence: 99%

Mechanism of surface uranium hydride formation during corrosion of uranium

Pan

et al. 2019

npj Mater Degrad

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Uranium is widely used in the nuclear industry and it is well known that uranium hydride, UH 3 , forms when uranium is exposed to air. The associated volume change during this transition can cause the surface region to crack, compromising structural integrity. Here, hydriding regions beneath hydride surface craters are studied by secondary ion mass spectroscopy (SIMS) and X-ray photoelectron spectroscopy (XPS). Our results indicate that strain transition regions exist, which are induced by hydrogen with a certain thickness between hydride craters and the uranium bulk. The SIMS and XPS results suggest that hydrogen exists covalently with uranium and oxygen in these transition regions. A micro-scale induction period model based on the transition region and previous hydriding models is developed. Within the so-called micro-scale induction period, hydrogen diffuses and accumulates at particular sites before reaching the critical concentration required to form stoichiometric UH 3 in the transition regions.

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Role of microstructure on corrosion initiation of an experimental tool alloy: A Quantitative Nanomechanical Property Mapping study

Cited by 7 publications

References 35 publications

Factors Affecting Peptide Interactions with Surface-Bound Microgels

Factors Affecting Peptide Interactions with Surface-Bound Microgels

Correlative Microstructure Analysis and In Situ Corrosion Study of AISI 420 Martensitic Stainless Steel for Plastic Molding Applications

Mechanism of surface uranium hydride formation during corrosion of uranium

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