Cyclic oxidation behaviour of rare earth oxide coated Fe–20Cr alloys

Abstract

The use of rare earths (REs) to increase high temperature oxidation resistance of chromium dioxide and alumina forming alloys is well known. The REs can be added as elements (or oxides) to the alloys or applied as an oxide coating to the alloy surface. The sol gel technique is very efficient to apply fine oxide particle coatings. The influence of various RE oxide gels such as La2O3, CeO2, Pr2O3, Nd2O3, Sm2O3, Gd2O3, Dy2O3, Y2O3, Er2O3 and Yb2O3 on cyclic oxidation behaviour (RT-900°C) of Fe–20Cr alloy has been studied. The morphology and coverage of the RE oxide gels varied with the type of RE. The cyclic oxidation resistance increases with increase in time at temperature required to reach a specific chromium dioxide layer thickness and this is influenced by RE ion radius and characteristics of the RE oxide coating such as morphology, stability, coverage, resistance to thermal stresses and consequently adhesion.

Challenges in oxidation resistant coatings

“…Many current commercial alloys use yttrium additions to control chromia/alumina growth and other rare earth elements with larger ionic radii are candidate alloying elements to further improve substrate and coating oxidation resistance. 6 Thermal expansion mismatch between a ceramic coating (formed or deposited) and the metallic substrate, which can result in scale spalling, can be reduced by using intermediate coats. Over the years, considerable effort has gone into understanding stress generation and its effect on scale microstructure in thermally formed protective oxide layers or oxide coatings.…”

Amino surface modification of Fe3O4/SiO2 nanoparticles for bioengineering applications

“…[1][2][3][4][5][6][7] Studies of iron based materials have attracted much interest in the last few years from both fundamental and applicative points of view. [8][9][10][11][12][13] Surface modification of magnetic nanoparticles (NPs) is a frequently used method to promote the performance of NPs as nanobiomaterials. In the recent decades, magnetic NPs, especially Fe 3 O 4 and c-Fe 2 O 3 , have attracted increasing interest because of their outstanding properties, including superparamagnetism and low toxicity and, as a result, their potential applications in various fields, especially in biotechnology and biomedicine, such as cell sorting, enzyme immobilisation, biosensing and bioelectrocatalysis, separation and purification.…”

“…The combination of molecular biology and materials science is leading to the development of new devices that benefit from both the exquisite specificity of biomolecules and the extreme control that can be exerted on the properties of the materials, especially of their surface 17 Studies of iron based materials have attracted much interest in the last few years from both fundamental and applicative points of view 813 Surface modification of magnetic nanoparticles (NPs) is a frequently used method to promote the performance of NPs as nanobiomaterials.…”