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1

Influence of the Electrochemical Anodizing Parameters on the Microstructure, Microroughness and Microhardness of Anodized Ti-6Al-7Nb

Veselinov Deyan, Skulev Hristo

Archives of Metallurgy and Materials

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2020

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Vol. 65, iss. 3

1223--1226

EN

This paper presents a study on anodizing titanium alloy Ti-6Al-7Nb in electrolyte of dilute sulfuric acid. The effects of the parameters – voltage, anodizing time, and electrode distance on the anodic film properties have been investigated. The anodic layers are found to become more compact with the increase of the applied voltage in the electrolytic cell. The microstructure, chemical element distribution and mechanical properties, i.e. microroughness and microhardness of the anodic coatings obtained at different operating conditions have been evaluated.

2

Effect of particle size on the oxidation and flotation behavior of galena particles

Lu Yalin, Tong Xiong, Xie Xian, Yang Bo, Hua Zhongbao

Physicochemical Problems of Mineral Processing

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2019

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Vol. 55, iss. 1

208--216

EN

The aim of this study was to determine the effect of particle size on the oxidation and flotation behavior of galena particles. Coarse (-0.074+0.038 mm), intermediate (-0.038+0.025 mm) and fine (-0.025 mm) galena particles were used in this study. Dissolution tests demonstrated that the amount of oxidation products increased with the decrease of particle sizes. The surface oxidization of galena was the greatest at pH 7.3, followed by pH 12 and 9, which were consist with the result of XPS. The micro-flotation results indicated that the effect of pH on the flotation recovery of galena enhanced with the reduction of particle sizes. The decreasing of particle sizes increases both the sorption rate of collector and the dissolution of galena, while the generation of hydrophilic product caused by dissolution is dominant, rendering the mineral hydrophilic. This study shows the differences in the surface oxidation and flotation behavior of different size fractions of galena particles. To promote the flotation recovery of the fine size fraction of galena particles, alleviating their oxidation is the key.

3

Interaction between sphalerite and pyrite and its effect on surface oxidation of sphalerite

Yang B., Xie X., Tong X., Lan Z., Cui Y.

Physicochemical Problems of Mineral Processing

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2018

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Vol. 54, iss. 2

311--320

EN

The interaction between sphalerite and pyrite was investigated by dissolution test, X-ray photoelectron spectroscopy (XPS), zeta potential measurement and density functional theory (DFT) calculation. Dissolution tests indicated that sphalerite dissolution was promoted due to the galvanic interaction between sphalerite and pyrite. The Zn2+ ion concentration increased with increasing pyrite content and dissolved time. XPS analysis results demonstrated that a new oxidation product was formed on the sphalerite surface in the presence of pyrite in a pulp. Zeta potential measurements showed that the isoelectric point of sphalerite increased from 3.3 to 5.4 due to galvanic interaction. DFT calculation results suggested that electron transfer from sphalerite to pyrite occurred when they contacted. The Zn 4s and S 3p states of sphalerite lost electrons. The Fe 4p and 4s of pyrite states obtained electrons, and Fe 3d and S 3s states lost a small number of electrons. The surface oxidation of sphalerite was promoted due to the interaction with pyrite, and the collectorless floatability of sphalerite decreased.

4

The role of aluminium oxidation in the wetting-bonding relationship of Al/oxide couples

Sobczak N., Asthana R., Radziwiłł W., Nowak R., Kudyba A.

Archives of Metallurgy and Materials

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2007

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Vol. 52, iss. 1

55-65

EN

In several Al/ceramic systems wetting is known to be strongly affected by the presence of oxide film on Al, which prevents a true contact, leading to large contact angles measured. However, the role the oxide plays in determining the bond quality and the resulting joint strength is not clear. This paper presents new experimental results on the effect of metal oxidation on the wetting – interface microstructure – interfacial shear strength relationship in Al/oxide systems exhibiting different reactivity with Al (Al2O3, TiO2, ZrO2, and SiO2). The results demonstrate that even a few nanometers thick oxide film covering liquid aluminum significantly affects macro-scale properties of Al/oxide couples such as wetting and shear bond strength.

PL

Znany jest fakt, ze obecność powłoki tlenkowej na aluminium ma istotny wpływ na zjawisko zwilżania niektórych materiałów ceramicznych, ponieważ stanowi ona naturalna barierę w tworzeniu autentycznego kontaktu, przyczyniając się tym samym do wysokich wartości mierzonych kątów zwilżania. Nie jest natomiast wyjaśniona rola powłoki tlenkowej w kształtowaniu połączenia metalowo-ceramicznego, zwłaszcza jej wpływ na wytrzymałość mechaniczną. W niniejszej publikacji na przykładzie badań kilku tlenków metali różniących się reaktywnością w kontakcie z ciekłym aluminium (Al2O3, TiO2, ZrO2, and SiO2) po raz pierwszy zademonstrowano, że w układach typu Al/ceramika utlenianie aluminium jest czynnikiem decydującym o charakterze wzajemnej korelacji pomiędzy zwilżalnością, strukturą granic rozdziału oraz wytrzymałością połaczenia. Stwierdzono, że obecność na aluminium powłoki tlenkowej o grubości nawet kilku nanometrów ma istotny wpływ na zjawiska i właściwości w skali makro, np. zwilżalność tlenków przez ciekłe aluminium oraz wytrzymałość na ścinanie połączenia Al/tlenek.