Oxides in plasma-sprayed chromium steel

Voleník, K.; Lettner, Josef; Hanousek, F.; Dubský, J.; Kolman, B.

doi:10.1007/s11666-997-0067-8

Cited by 20 publications

(5 citation statements)

References 16 publications

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“…To prepare samples for the measurements, the oxidation products were separated from the metallic matrix by dissolving the metal in a solution of iodine in methyl alcohol. The technique has been described elsewhere [2]. To remove the metallic phase thoroughly, the product of the separation procedure was milled and the dissolution run was repeated.…”

Section: Analysis Of Oxidation Productsmentioning

confidence: 99%

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Oxidation of nickel during plasma spraying and some properties of nickel oxide

et al. 2004

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The techniques of plasma spraying are suitable for deposition of metals, ceramics or composites. Atmospheric plasma spraying of metals is accompanied by their oxidation. The oxidation of nickel during its spraying gives rise to NiO. During the flight of molten nickel particles in the plasma plume, the first stage of the oxidation reaction takes place. To determine the amount of NiO grown during this stage, oxidation can be stopped abruptly by trapping and quenching the particles in liquid nitrogen. If, on the other hand, the flying molten particles are allowed to hit a solid substrate, a plasma deposit or coating is built up. The period starting at the moment of the particle impact and solidification corresponds to the second oxidation stage. This is finished by cooling down the system substratecoating.Plasma spraying of nickel was conducted using a water-stabilized plasma gun. To study the structure and optical properties of the oxidation products, it is necessary to remove the metallic phase from the samples. This was done by a technique of metal dissolution described previously.After the first oxidation stage, if the particles are trapped in liquid nitrogen, NiO is obtained by rapid solidification of oxide melt grown on the surface of the flying particles as a result of a gas -molten Ni reaction. The colour of solid NiO formed in this way is green, which corresponds to a region of high reflectance between 1.9 and 2.7 eV. The green colour is typical of stoichiometric NiO and is due to octahedral Ni 2+ ions.The second oxidation stage is characterized by a gas -solid Ni reaction. It results in black NiO, whose colour follows from strong absorption of light in the whole visible range. The oxygen content in this oxide exceeds slightly the stoichiometric value. The light absorption is due to free charge carriers, i.e. holes, whose presence is a consequence of the deviation of NiO from stoichiometry.

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Section: Analysis Of Oxidation Productsmentioning

confidence: 99%

“…The metallic phase prevails in both sample types. However, pure oxide samples can be investigated after metallic phase dissolution [2]. Fragments of hollow spheres of oxide films similar to the case shown in [3] result from this treatment after the first oxidation stage.…”

Section: Introductionmentioning

confidence: 99%

Oxidation of nickel during plasma spraying and some properties of nickel oxide

et al. 2004

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“…This technique enables one to abruptly stop the in-flight oxidation reaction at a required distance from the plasma gun nozzle and to prevent the metallic particles from further oxidation. To study the properties of the resulting oxide crust, the metallic phase can be dissolved by a chemical method described elsewhere [20]. Specimens of oxide crusts or their fragments are obtained by this technique.…”

Section: Resultsmentioning

confidence: 99%

Cooling rates of plasma-sprayed metallic particles in liquid and gaseous nitrogen

Kotalík

Voleník

2001

J. Phys. D: Appl. Phys.

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Plasma spraying of metallic particles in the ambient atmosphere is accompanied by their oxidation. The oxides formed on the particle surfaces are often unstable at room temperature. Fast cooling of the particles may conserve these oxides, leaving thus the particles heterogeneous and consisting of at least two materials - the oxide layer on the surface and the metal in the centre. The times required to cool the particles below the melting points of the two materials are estimated for slow and fast cooling in gas and liquid nitrogen, respectively. The estimates are carried out numerically by solving a one-dimensional heat transfer equation for solidifying spherical iron and \mbox{Fe-Cr} alloy particles having either a thin (1 µm) or a thick (10 µm) oxide layer on their surface. It has been found that for the typical particle size of 120 µm in diameter, the cooling rates, under the assumed conditions, are 105-106 K s-1 and it takes 10-1 ms to completely solidify the initially liquid particles. The temperature histories of the particles without any oxide layer and with a thin oxide layer are almost identical.

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“…Volenik's research demonstrates that a spectral peak at 1100 cm -1 , accompanied by a smaller peak at 1198 cm -1 , can be attributed to the vibrational motion of Si-O bonds in SiO2 [26].…”

Section: Microscopic and Ftir Analysismentioning

confidence: 99%

Effects of seawater and acidic environment on mechanical properties of iron powder-loaded glass-epoxy composite laminates: Experimental and analytical investigation

Gheid,

Chemami,

Gaagaia

et al. 2024

Res. Eng. Struct. Mat.

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This study assesses the impact of seawater and acidity on a glass epoxy composite filled with pure iron powder. Plates with varying iron content (15%, 20%, and 25%) were created using contact molding, with 30% glass fiber content. After dividing the plates into samples, a three-point bending examination was conducted following ISO14125 standards. The samples were immersed in saltwater (Group A), an acidic solution (Group B), or kept dry for comparison (Group C). Each subgroup had 15 specimens (5 for each iron %), immersed for over 60 days before undergoing bending tests. Results showed a significant decline in flexural strength, with a maximum reduction of 29.7% in Group A and 37.9% in Group B, while Young's modulus decreased up to 34.8% in Group A and 45.6% in Group B. The two-way ANOVA approach confirmed these findings, and microscopic examinations and FTIR analysis after immersion elucidated physical alterations and chemical reactions. Despite certain advantages, such as specific applications, the composite's limitations in corrosion resistance, durability, and production cost may restrict its relevance in various industrial and real-world applications. Consideration of these factors is essential before choosing this material for a specific project.

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Oxides in plasma-sprayed chromium steel

Cited by 20 publications

References 16 publications

Oxidation of nickel during plasma spraying and some properties of nickel oxide

Oxidation of nickel during plasma spraying and some properties of nickel oxide

Cooling rates of plasma-sprayed metallic particles in liquid and gaseous nitrogen

Effects of seawater and acidic environment on mechanical properties of iron powder-loaded glass-epoxy composite laminates: Experimental and analytical investigation

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