scholarly journals New Formation Mechanisms of Pores and Cracks in Micro-arc Oxidation Coatings on 6061 Aluminum Alloy with High Temperature Oxide Prefab Film

2021 ◽  
Vol 27 (1) ◽  
pp. 37-41
Author(s):  
Guo-rui WU ◽  
Dong-dong WANG ◽  
Xin-tong LIU ◽  
Mingjia WANG ◽  
Dong CHEN ◽  
...  
Keyword(s):  
Aluminum Alloy ◽  
High Temperature ◽  
Phase Interface ◽  
Oxide Phase ◽  
Formation Mechanisms ◽  
Coating Materials ◽  
6061 Aluminum Alloy ◽  
High Temperature Oxide ◽  
Micro Arc Oxidation ◽  
Temperature Oxide

Prior to micro-arc oxidation (MAO) treatment, a layer of high temperature oxide (HTO) prefab film was fabricated on the surface of 6061 aluminum alloy specimens. The formation mechanisms of the cracks and pores in the MAO coatings were investigated by means of Mg element as the tracer. The results showed that there were several different formation mechanisms for the pores and cracks formed in the MAO coatings as follows. Some of pores were attributed to the residual micro-discharge channels, and the others were attributed to the residual uncovered concave regions locating among the surrounding convex regions. The difference in oxide phase composition caused by the compositional fluctuations in the coating weakened the bond strength at the phase interface and resulted in forming cracks between every two convex regions. Some of cracks were resulted from the solidification and shrinkage of molten coating materials, and the others were resulted from the poor connection between every two convex regions. The surface morphology and the content of each element of the MAO coating were determined using scanning electron microscopy (SEM) equipped with energy dispersive X-ray spectroscopy (EDS).

NEUTRON POWDER DIFFRACTION AND OXIDE SUPERCONDUCTORS

1993 ◽  
Vol 07 (16n17) ◽  
pp. 3077-3093 ◽  
Author(s):  
A.W. HEWAT
Keyword(s):  
Heavy Metals ◽  
High Temperature ◽  
Powder Diffraction ◽  
Neutron Powder Diffraction ◽  
Oxide Superconductors ◽  
X Rays ◽  
New Materials ◽  
Oxidation Reduction ◽  
High Temperature Oxide ◽  
Temperature Oxide

Neutron powder diffraction has been essential for understanding the structures of the new high temperature oxide superconductors because of the difficulty in locating oxygen with X-rays in the presence of heavy metals, especially when single crystals are usually not available. This understanding lead to the discovery of new materials. In this paper we will show how it also sheds light on the crystal chemistry of oxide superconductors—the effects of oxidation/reduction, phase separation, pressure etc.

Thermochemistry of Hf-Zirconolite, CaHf Ti2O7

1999 ◽  
Vol 556 ◽  
Author(s):  
Robert L. Putnam ◽  
Alexandra Navrotsky ◽  
Brian F. Woodfield ◽  
Jennifer L. Shapiro ◽  
Rebecca Stevens ◽  
...  
Keyword(s):  
Heat Capacity ◽  
High Temperature ◽  
Low Temperature ◽  
Adiabatic Calorimetry ◽  
Formation Enthalpy ◽  
Solution Calorimetry ◽  
Oxide Melt ◽  
High Temperature Oxide ◽  
Temperature Oxide ◽  
Capacity Data

AbstractThe formation enthalpy, - 3752.3 ± 4.7 kJ·mol−1, of Hf-zirconolite, CaHfTi2O7, was obtained using high temperature oxide-melt solution calorimetry. Combined with heat capacity data obtained using low temperature adiabatic calorimetry we report the heat capacity (Cp) and the standard molar formation energetics (ΔH°f. elements, Δ S°T, and ΔG°f. elements)for Hf-zirconolite from T = 298.15 K to T = 1500 K. Comparison of Hf-zirconolite with Zr-zirconolite is made.

High Temperature Oxide (HTO) for non volatile memories applications

1997 ◽  
Vol 36 (1-4) ◽  
pp. 87-90 ◽  
Author(s):  
Ph. Candelier ◽  
B. Guillaumot ◽  
F. Mondon ◽  
G. Reimbold ◽  
H. Achard ◽  
...  
Keyword(s):  
High Temperature ◽  
High Temperature Oxide ◽  
Temperature Oxide
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