The formation of a surface layer during microarc oxidation of aluminum alloys

Mikheev, A Ye; Гирн, А В; Вахтеев, Е. В.; Алексеева, Е. Г.; Раводина, Д В

doi:10.1088/1757-899x/70/1/012002

Cited by 3 publications

(3 citation statements)

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“…(2) This increased the resistivity between the anode-electrolyte, forming an electric field strong enough to liberate and form as gas enveloped the anode surface and initially increased the applied voltage. (3) High voltages greater than the breakdown voltage at the electron avalanche birthplace excited the electrolyte near the anode via ionization and dissociation, transforming gases into ions such as NO 2− , N 2− , and O 2− , which were subsequently localized onto the anode surface by applying considerable kinetic energy (Mikheev et al, 2015 ). (4) The ionized gaseous layer provided sufficient energy to initiate Joule heating, which entailed high temperatures and pressures, forming a plasma discharge within the gas envelope.…”

Section: Resultsmentioning

confidence: 99%

A Novel Synthetic Method for N Doped TiO2 Nanoparticles Through Plasma-Assisted Electrolysis and Photocatalytic Activity in the Visible Region

Kim

Cho

et al. 2018

Front. Chem.

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Nitrogen doped TiO2 (N-TiO2) nanoparticles were synthesized via a novel plasma enhanced electrolysis method using bulk titanium (Ti) as a source material and nitric acid as the nitrogen dopant. This method possesses remarkable merits with regard to the direct-metal synthesis of nanoparticles with its one-step process, eco-friendliness, and its ability to be mass produced. The nanoparticles were synthesized from bulk Ti metal and dipped in 5–15 mmol of a nitric acid electrolyte under the application of AC 500 V, the minimum range of voltage to generate plasma. By controlling the electrolyte concentration, the nanoparticle size distribution could be tuned between 12.1 and 24.7 nm using repulsion forces via variations in pH. The prepared N-TiO2 nanoparticles were calcined at between 100 and 300°C to determine their photocatalytic efficiency within the visible-light region, which depended on their crystal structure and N doping content. Analysis showed that the temperature treatment yielded an anatase TiO2 crystalline structure when the N doping content was varied from 0.4 to 0.54 at.%. In particular, the 0.4 at.% N doped TiO2 catalyst exhibited the highest catalytic performance with quadruple efficiency compared to the P-25 standard TiO2 nanoparticles, which featured a 91% degradation of methyl orange organic dye within 300 min. This solid-liquid reaction based on plasma enhanced electrolysis could open new pathways with regard to high purity mass producible ceramic nanoparticles with advanced properties.

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Section: Resultsmentioning

confidence: 99%

A Novel Synthetic Method for N Doped TiO2 Nanoparticles Through Plasma-Assisted Electrolysis and Photocatalytic Activity in the Visible Region

Kim

Cho

et al. 2018

Front. Chem.

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“…From the results, it clearly implies that the oxidation temperature has a strong consequence on the exterior appearance and oxidation behaviour. It was also suggested by [2,27,28] that the rough outermost surface layer of Al after oxidation exposure indicated a formation of a thin oxide layer and it was believed that this layer was mostly a porous structure. Further prolong exposure to high temperature led to the deposition of oxides mainly on the surface area of Al alloy.…”

Section: Methodsmentioning

confidence: 95%

“…Meanwhile, contradicted observation was shown for the fused metal part. It shows that by extending the oxidation temperature from 400 ( Figure 5 (a)) to 500 °C ( Figure 5 (b)), severe internal oxide attack was discovered within the substrate which specified the internal degradation caused by oxidation [27,31]. Moreover, the outer oxide scale seemed to be thickened.…”

Section: Oxide Characteristicsmentioning

confidence: 98%

Effects of temperature on the surface and subsurface of Al-Mg-Si welded joints

Hussin¹,

Lah²

2017

J. MECH. ENG. SCI.

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Al-Mg-Si (6061) Al alloy represents a widely used light material which is highly dependent on the distribution of its alloying element. Yet, when it involved a welded structure, the performance was absolutely dissimilar due to the influence of alloying element from filler metal addition, especially when it is subjected to high temperature environment. Thus, the study focuses on the surface and subsurface oxide growth patterns, its morphologies, and phases that formed after oxidation exposure. The plates were joined by GMAW using Al-5%Mg (ER5356) filler metal, and then subjected to an oxidation process in air environment at 400 °C, 500 °C and 600 °C for 40 h; their mass gains were then measured. The oxidised parent and fused metal parts were subsequently analysed using the scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and X-ray diffraction technique (XRD). It was observed that with the increasing temperature, the fused metal parts exhibited different oxide morphologies on both surface and subsurface compared to the parent metal parts. Additionally, the less oxidation attack was found after exposure at 400 °C and poor oxidation behaviour showed at 500 and 600 °C. The -Al2O3 phase was detected in both parent and fused metal samples after exposure at 400, 500, and 600 °C. Meanwhile, contradicted observation showed that the MgO phase was detected in fused metal part responsible for the poor oxidation behaviour. Thus, this would lead to a formation of non-protective oxide on the fused metal surfaces. This study suggested that the 6061 welded structure can withstand at 400 °C for long periods in air without serious deterioration but could not withstand exposure to 500 and 600 °C conditions in air.

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