Thermal radiative properties of magnesium oxide at high temperatures

Highlights The oxidation behaviours of Mg alloys from low to high temperatures are reviewed. Characteristics of MgO during oxidation is discussed. Mechanisms of Mg oxidation is presented. Effect of various alloying elements is analysed. AbstractThis paper reviews (i) the oxidation of Mg alloys at elevated temperatures in air; (ii) the influence of alloying elements on the oxidation of Mg alloys; and (iii) the progress in the development of oxidation-resistant Mg alloys. Low oxidation rates have been shown by Mg alloys containing the alloying elements, Ca, Be and rare earth elements. However, these alloying elements may also decrease mechanical properties, such as ductility.

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“…MgO has a high melting point of 2942 ± 50 C [28] and calcined or fused magnesia is widely used as a (high-temperature) insulator [26].…”

Section: Magnesium Oxidementioning

confidence: 99%

Oxidation of magnesium alloys at elevated temperatures in air: A review

et al. 2016

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“…Such growth will result in eventual breakdown of scale adhesion, as was observed on Yimplanted alumina forming alloys. 90,91 In the case of chromium, the Y-implants with a dose of 2610 16 ions cm 22 , after 20 h exposure, showed signs that the effect was diminishing. 92 It should be emphasised that for Mg alloys exposed to temperatures of semisolid and liquid states RE coatings will not be effective and bulk alloying remains the only option.…”

Section: Methods Of Re Addition To Metallic Alloysmentioning

confidence: 99%

“…In a majority of systems, the observed effects derived entirely from the chemical role of the implanted element. 81,82 Of all doses of implants reported in the literature, there appears to be a threshold dose for improved oxidation resistance, usually between 1610 15 and 1610 17 ions cm 22 . Maximum inhibition is typically obtained with doses between 2610 16 and 1610 17 ions cm 22 .…”

Section: Methods Of Re Addition To Metallic Alloysmentioning

confidence: 99%

“…81,82 Of all doses of implants reported in the literature, there appears to be a threshold dose for improved oxidation resistance, usually between 1610 15 and 1610 17 ions cm 22 . Maximum inhibition is typically obtained with doses between 2610 16 and 1610 17 ions cm 22 . 83 Coatings of RE oxides can be applied by several techniques.…”

Section: Methods Of Re Addition To Metallic Alloysmentioning

confidence: 99%

“…in monocrystalline films formed at room or slightly elevated temperatures. In MgO lattice, Mg 2z diffuses extrinsically by a single vacancy mechanism, while O 22 diffuses intrinsically by a di-vacancy mode. The selfdiffusion in magnesium oxide can be determined both experimentally and through computer modelling, e.g.…”

Section: Characteristics Of Magnesium Oxidementioning

confidence: 99%

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The reactive element effect on high-temperature oxidation of magnesium

Czerwiński

2015

International Materials Reviews

102

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It was discovered over 75 years ago that minor additions of elements with high affinity to oxygen exert a profound effect on oxidation resistance of many metals and alloys. In this report, progress in understanding the 'reactive element effect' (REE) and opportunities created for controlling the high-temperature oxidation of magnesium alloys were reviewed. Magnesium, the lightest structural metal, exhibits high affinity to oxygen and, as opposed to heat-resistant materials, does not form a dense, slow-growing and protective oxide layer. However, additions of small amounts of reactive elements (REs) to magnesium alloys produce a number of positive effects in improving their oxidation resistance. What is of crucial importance for magnesium is that RE benefits are also extended to its ignition, flammability, evaporation and liquid-state reactivity. The mechanism by which these elements influence oxidation and other related behaviour remains, so far, unclear. Although no specific theory explaining the REE on magnesium has been developed, growth kinetics, surface morphology and internal microstructure of magnesia films and scales, doped with REs show characteristics typical for high-temperature materials that form protective oxides.

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