About the Mechanism of the Formation of Aluminum Oxides in Iron Carbonate Melts

This work evaluates the dry sliding behavior of anodic aluminum oxides (AAO) formed during one traditional hard anodizing treatment (HA) and two golden hard anodizing treatments (named G and GP, respectively) on a EN AW-6060 aluminum alloy. Three different thicknesses of AAO layers were selected: 25, 50, and 100 μm. Prior to wear tests, microstructure and mechanical properties were determined by scanning electron microscopy (VPSEM/EDS), X-ray diffractometry, diffuse reflectance infrared Fourier transform (DRIFT-FTIR) spectroscopy, roughness, microhardness, and scratch tests. Wear tests were carried out by a pin-on-disc tribometer using a steel disc as the counterpart material. The friction coefficient was provided by the equipment. Anodized pins were weighed before and after tests to assess the wear rate. Worn surfaces were analyzed by VPSEM/EDS and DRITF-FTIR. Based on the results, the GP-treated surfaces with a thickness of 50 μm exhibit the lowest friction coefficients and wear rates. In any case, a tribofilm is observed on the wear tracks. During sliding, its detachment leads to delamination of the underlying anodic aluminum oxides and to abrasion of the aluminum substrate. Finally, the best tribological performance of G- and GP-treated surfaces may be related to the existence of a thin Ag-rich film at the coating/aluminum substrate interfaces.

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The Dynamics of Tungsten in Soil: An Overview

Environments ◽

10.3390/environments8070066 ◽

2021 ◽

Vol 8 (7) ◽

pp. 66

Author(s):

Gianniantonio Petruzzelli ◽

Francesca Pedron

Keyword(s):

Everyday Life ◽

Soil Ph ◽

Food Chain ◽

Green Energy ◽

Basic Information ◽

Environmental Legislation ◽

Soil Environment ◽

Aluminum Oxides ◽

Adsorption And Desorption ◽

Iron And Aluminum Oxides

The increasing use of tungsten in the production of green energy in the aerospace and military industries, and in many other hi-tech applications, may increase the content of this element in soil. This overview examines some aspects of the behavior of tungsten in soil, such as the importance of characteristics of soils in relation to bioavailability processes, the chemical approaches to evaluate tungsten mobility in the soil environment and the importance of adsorption and desorption processes. Tungsten behavior depends on soil properties of which the most important is soil pH, which determines the solubility and polymerization of tungstate ions and the characteristics of the adsorbing soil surfaces. During the adsorption and desorption of tungsten, iron, and aluminum oxides, and hydroxides play a key role as they are the most important adsorbing surfaces for tungsten. The behavior of tungsten compounds in the soil determines the transfer of this element in plants and therefore in the food chain. Despite the growing importance of tungsten in everyday life, environmental regulations concerning soil do not take this element into consideration. The purpose of this review is also to provide some basic information that could be useful when considering tungsten in environmental legislation.

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Thermodynamic Studies of Iron Carbonate Solubility in Aqueous Monoethylene Glycol Mixtures and CO2 Atmosphere

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.830.134 ◽

2016 ◽

Vol 830 ◽

pp. 134-138 ◽

Cited By ~ 1

Author(s):

Camila Senna Figueiredo ◽

Jailton Ferreira do Nascimento ◽

Rony Oliveira de Sant'ana ◽

Deborah Cordeiro de Andrade ◽

Zaniel Souto Dantas Procópio ◽

...

Keyword(s):

Carbon Dioxide ◽

Natural Gas ◽

High Capacity ◽

Gas Production ◽

Aqueous Mixtures ◽

Iron Carbonate ◽

Low Viscosity ◽

Carbon Dioxide Atmosphere ◽

Equilibrium Data ◽

Monoethylene Glycol

Monoethylene glycol (MEG) is being widely applied as thermodynamic inhibitor to avoid formation of natural gas hydrates. High hydrophilicity, low toxicity, low viscosity, low solubility in liquid hydrocarbons and high capacity of dissolving salts are advantageous for the use of MEG in the natural gas production. In addition, MEG recovery can be easily achieved considering its low volatility in relation to water, which makes the process economical and environmentally feasible. The reuse of MEG is being theme of research and phase equilibrium data for the involved species are required. In this work, a experimental procedure to synthetize iron carbonate and, afterwards, determine its solubility in aqueous mixtures of MEG in the presence of carbon dioxide atmosphere have been developed. Furthermore, a series of solubility data has been measured. This work presents a worthy contribution to the description of iron carbonate aqueous solubilities in the presence of MEG and carbon dioxide, regarding the instability of the salt to respect of oxidation. Subsequently, the knowledge of the behavior of the iron carbonate solubilities is useful for the industrial unities of production of natural gas and recovery of MEG.

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