Influences of Calcination Ambiences on Morphologies, Phase Composition and Contents of the Elements of Ceramic Coatings on Ti Alloy by Micro-Arc Oxidation

Compound ceramic coatings with the main crystal phase of Al2TiO5 (as-coated samples) were prepared in situ on the surface of Ti-6Al-4V alloy by means of pulsed bi-polar micro-arc oxidation (MAO) in an NaAlO2 solution. The coated samples were calcined in argon and air at 1000 oC, respectively. The phase composition, surface and section morphology, and element contents of the ceramic coatings were investigated by X-ray diffractometry (XRD), Scanning electron microscopy (SEM) and X-ray fluorescence spectroscopy (XRF). The samples were treated in argon and the as-coated ones were calcined in air at 1000 oC to study the anti-oxidation properties of the samples. The results show that Al2TiO5 had been decomposed in an hour and transformed into α-Al2O3 and rutile TiO2 in air. However, Al2TiO5 had been decomposed in four hours in argon and the final coating surface was completely composed of α-Al2O3. The content of Al2O3 was decreased from outside to inside layers and Ti2O3 was formed in the coating. Furthermore, the morphology of the ceramic coatings after the calcination was different. The coatings calcined in argon were finer; the grains and pores were smaller than those in air.

Influences of Different Calcination Ambiences on Phase Composition, Morphologies of Ceramic Coatings on Ti–6Al–4V Alloy by Micro-Arc Oxidation

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.412.469 ◽

2011 ◽

Vol 412 ◽

pp. 469-472

Author(s):

Guo Dong Hao ◽

Huan Yuan ◽

Jing Zhang

Keyword(s):

Electron Microscopy ◽

Phase Composition ◽

Fluorescence Spectroscopy ◽

Ceramic Coatings ◽

X Ray ◽

Micro Arc Oxidation ◽

Oxidation Properties ◽

Compound ceramic coatings with the main crystal phase of Al2TiO5(as-coated samples) were prepared in situ on the surface of Ti-6Al-4V alloy by means of pulsed bi-polar micro-arc oxidation (MAO) in an NaAlO2solution. The coated samples were calcined in argon and air at 1000°C, respectively. The phase composition, surface and section morphology, and element contents of the ceramic coatings were investigated by X-ray diffractometry (XRD), Scanning electron microscopy (SEM) and X-ray fluorescence spectroscopy (XRF). The samples were treated in argon and the as-coated ones were calcined in air at 1000°C to study the anti-oxidation properties of the samples. The results show that Al2TiO5had been decomposed in an hour and transformed intoα-Al2O3and rutile TiO2in air. However, Al2TiO5had been decomposed in four hours in argon and the final coating surface was completely composed ofα-Al2O3. The content of Al2O3was decreased from outside to inside layers and Ti2O3was formed in the coating. Furthermore, the morphology of the ceramic coatings after the calcination was different. The coatings calcined in argon were finer; the grains and pores were smaller than those in air.

Influences of Different Calcinations Ambience on Phase Composition and Morphologies of Ceramic Coatings on Ti Alloy by Micro-Arc Oxidation

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.97-101.1554 ◽

2010 ◽

Vol 97-101 ◽

pp. 1554-1557

Author(s):

Guo Dong Hao ◽

Nai Wu Zhang ◽

Tao Yun ◽

Jin Wang ◽

Bo Lian ◽

...

Keyword(s):

Phase Composition ◽

High Temperature Oxidation ◽

Ceramic Coatings ◽

Ti Alloy ◽

Temperature Oxidation ◽

Weight Gains ◽

Micro Arc Oxidation ◽

Oxidation Properties ◽

Α Al2o3

Compound ceramic coatings with the main crystalline of Al2TiO5 (as-coated samples) were prepared in situ on the surface Ti-6Al-4V alloy by means of pulsed bi-polar micro-arc oxidation (MAO) in a NaAlO2 solution. The coated samples were calcined in argon and air at 1000 oC, respectively. The phase composition, surface morphology of the ceramic coatings were investigated by XRD, SEM and XRF. The samples were treated in argon and the as-coated ones were calcined in air at 1000 oC to study the anti-oxidation properties of the samples. The results show that Al2TiO5 was decomposed very soon and transformed into α-Al2O3 and rutile TiO2 in air. However, Al2TiO5 was decomposed very slowly in argon and the final coating surface was completely α-Al2O3. Also, the morphology of the ceramic coatings after the calcination was different. The coatings calcined in argon were fined; grains and pores were smaller than those in air. High temperature oxidation occurred very strongly in the TC4 substrate, the weight gains of the as-coated ceramic coatings and the treated ones in argon were nearly changing in the form of parabola, and the weight gains of the coated samples treated in argon were comparatively lower than those of the as-coated samples.

Influences of Argon Ambience on Phase Composition and High Temperature Oxidation Resistance Property of Ceramic Coatings on Ti Alloy by Micro-Arc Oxidation

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.512-515.1078 ◽

2012 ◽

Vol 512-515 ◽

pp. 1078-1081

Author(s):

Guo Dong Hao ◽

Zhi Gang Yang ◽

Xu Xu Zheng ◽

Xu Zhao Zeng ◽

Xu Yan Wu

Keyword(s):

Phase Composition ◽

Ceramic Coatings ◽

Temperature Oxidation ◽

X Ray ◽

High Oxidation ◽

Weight Gains ◽

Micro Arc Oxidation ◽

Oxidation Properties ◽

Α Al2o3

Abstract. Compound ceramic coatings with the main crystal phase of Al2TiO5 (as-coated samples) were prepared in situ on the surface of Ti-6Al-4V alloy by means of pulsed bi-polar micro-arc oxidation (MAO) in an NaAlO2 solution. The coated samples were calcined in argon and air at 1000 oC, respectively. The phase composition, surface and section morphology, and element contents of the ceramic coatings were investigated by X-ray diffractometry(XRD), Scanning electron microscopy (SEM) and X-ray fluorescence spectroscopy (XRF). The samples were treated in argon and the as-coated ones were calcined in air at 1000 oC to study the anti-oxidation properties of the samples. The results show that Al2TiO5 had been decomposed in an hour and transformed into α-Al2O3 and rutile TiO2 in air. However, Al2TiO5 had been decomposed in four hours in argon and the final coating surface was completely composed of α-Al2O3. The content of Al2O3 was decreased from outside to inside layers and Ti2O3 was formed in the coating. Furthermore, the morphology of the ceramic coatings after the calcination was different. The coatings calcined in argon were finer; the grains and pores were smaller than those in air. The high oxidation reaction of the TC4 substrate was the fiercest and the weight gains of the coated samples treated in argon was the lowest. The weight gains of the ceramic coatings were nearly changing in the form of parabola law.

International Journal of Materials Research (formerly Zeitschrift fuer Metallkunde) ◽

Effects of graphene on the microstructure and properties of MAO coatings formed on AA7050

10.1515/ijmr-2020-1110603 ◽

2020 ◽

Vol 111 (6) ◽

pp. 463-468

Author(s):

Bo Xu ◽

Yafeng He ◽

Xiangzhi Wang ◽

Weimin Gan

Keyword(s):

Electron Microscopy ◽

Corrosion Resistance ◽

Aluminum Alloy ◽

Composite Coatings ◽

Ceramic Coatings ◽

X Ray Diffraction ◽

X Ray ◽

Micro Arc Oxidation ◽

Abstract Ceramic coatings were prepared on the surface of 7050 highstrength aluminum alloy using micro-arc oxidation in an aluminate electrolyte with added graphene. To analyze the surface morphology, roughness, phase composition, and corrosion resistance, scanning electron microscopy, X-ray diffraction, X-ray photoelectron, and electrochemical measurements were used, respectively. The addition of 9 g · L-1 of graphene to the electrolyte decreased the micro-pore size of the composite coatings and improved the density. In addition, with the addition of graphene, the roughness was the lowest, and the corrosion resistance was significantly improved.

Phase composition of coatings on the D16 alloy during micro-arc oxdation in alkaline and silicate electrolytes

Theory and practice of metallurgy ◽

10.34185/tpm.1.2020.07 ◽

2020 ◽

Vol 1,2020 (1,2020 (124)) ◽

pp. 51-55

Author(s):

Subbotina V ◽

Belozerov V ◽

Sobol’ O

Keyword(s):

Phase Composition ◽

Liquid Glass ◽

Amorphous State ◽

Practical Significance ◽

Alkaline Electrolyte ◽

X Ray ◽

Micro Arc Oxidation ◽

Coating Formation ◽

Al2o3 Phase ◽

Α Al2o3

Goal. The influence of electrolysis conditions at different electrolyte compositions on the phase formation of coatings obtained by micro-arc oxidation (MDO) on an aluminum alloy D16 was studied. Method. For electrolysis, two types of electrolytes were used: alkaline electrolyte (solution (KOH) in distilled water), silicate electrolyte (with different percentages of Na2SiO3 component). Research results. It was found that the phase composition of the MAO coatings obtained in an alkaline (KOH) electrolyte mainly consists of γ - Al2O3 phases and, to a much lesser extent, the α-Al2O3 phases. An increase in the KOH concentration leads to a shift in the γ – Al2O3 → α – Al2O3 polymorphic reaction toward the formation of the hardest α-Al2O3 phase (corundum). The formation of the preferred orientation of the growth of crystallites of γ – Al2O3 and α – Al2O3 phases during their formation in an alkaline electrolyte was not detected. Scientific novelty. A significant influence on the mechanism and processes of coating formation is made by the addition of liquid glass (Na2SiO3) in the electrolyte. In this case, the growth rate of the coating increases significantly, but the size of the ordering regions decreases from crystalline to X-ray amorphous. The phase composition of the MAO coatings, when they are formed in a silicate electrolyte, varies from a mixture of the γ - Al2O3 phase and mullite (3Al2O3 • 2SiO2) with a low content of liquid glass (10 g/l Na2SiO3) to the formation of only the X-ray amorphous phase with a high content of liquid glass in the electrolyte (50 g/l Na2SiO3). Practical significance. It was concluded that the use of an alkaline or silicate electrolyte with different percentages allows a wide variation of both the phase composition and structural state (α- Al2O3 and γ- Al2O3 phases, mullite (3Al2O3 • 2SiO2) or X-ray amorphous state) and the kinetics of growth the coating itself.

Magnetic Properties of Ferrous Ferric Oxide Confined in Porous Silicon

Materials Science Forum ◽

10.4028/www.scientific.net/msf.663-665.1142 ◽

2010 ◽

Vol 663-665 ◽

pp. 1142-1145

Author(s):

Yuan Ming Huang ◽

Bao Gai Zhai ◽

Qing Lan Ma ◽

Ming Meng

Keyword(s):

Electron Microscopy ◽

Magnetic Properties ◽

Iron Oxide ◽

Porous Silicon ◽

Ferrous Iron ◽

Silicon Film ◽

X Ray ◽

Loop Measurement ◽

During the chemical synthesis nanometer-sized particles of ferrous iron oxide were in situ infiltrated into the mesopores in a porous silicon film. The microstructures of porous silicon and the magnetic properties of the nanometer-sized particles of the ferrous iron oxide were characterized with scanning electron microscopy, X-ray diffractometry, and the hysteresis loop measurement, respectively. Our results have demonstrated that the magnetic properties of the nanometer-sized Fe3O4 particles can be dramatically modified when they are confined into the mesopores of the porous silicon film.

UTILIZATION OF FLY ASH AND CONCRETE RESIDUE IN THE PRODUCTION OF GEOPOLYMER BRICKS

Journal of Green Building ◽

10.3992/1552-6100.12.1.63 ◽

2017 ◽

Vol 12 (1) ◽

pp. 63-77 ◽

Cited By ~ 1

Author(s):

Siriporn Sirikingkaew ◽

Nuta Supakata

Keyword(s):

Electron Microscopy ◽

Mechanical Properties ◽

Compressive Strength ◽

Phase Composition ◽

Fly Ash ◽

Industrial Waste ◽

X Ray Diffraction ◽

X Ray ◽

This study presents the development of geopolymer bricks synthetized from industrial waste, including fly ash mixed with concrete residue containing aluminosilicate compound. The above two ingredients are mixed according to five ratios: 100:0, 95:5, 90:10, 85:15, and 80:20. The mixture's physico-mechanical properties, in terms of water absorption and the compressive strength of the geopolymer bricks, are investigated according to the TIS 168-2546 standard. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) analyses are used to investigate the microstructure and the elemental and phase composition of the brick specimens. The results indicate that the combination of fly ash and concrete residue represents a suitable approach to brick production, as required by the TIS 168–2546 standard.

Standard Hot Pressing as a Possible Solution to Obtain Dense K0.5Na0.5NbO3 Ceramic Doped by Er2O3 and Yb2O3

Materials ◽

10.3390/ma12244171 ◽

2019 ◽

Vol 12 (24) ◽

pp. 4171 ◽

Cited By ~ 1

Author(s):

Paweł Rutkowski ◽

Jan Huebner ◽

Adrian Graboś ◽

Dariusz Kata ◽

Dariusz Grzybek ◽

...

Keyword(s):

Electron Microscopy ◽

Rare Earth ◽

Phase Composition ◽

Powder Mixture ◽

Hot Pressing ◽

X Ray Diffraction ◽

X Ray ◽

Ultrasonic Methods ◽

In this study, the influence of the addition of rare earth oxides on the phase composition and density of KNN piezoelectric ceramics was investigated. The initial powders of Na2CO3 and K2CO3 were dried at 150 °C for 2 h. Then, a powder mixture for synthesis was prepared by adding a stoichiometric amount of Nb2O5 and 5 and 10 wt % overabundance of Na2CO3. All powders were mixed by ball-milling for 24 h and synthesized at 950 °C. The phase composition of the reaction bed was checked by means of X-ray diffraction (XRD). It had an appearance of tetragonal and monoclinic K0.5Na0.5NbO3 (KNN) phases. Then, 1 and 2 wt % of Er2O3 and Yb2O3, were added to the mixture. Green samples of 25 mm diameter and 3 mm thickness were prepared and sintered by hot pressing at 1000 °C for 2 h under 25 MPa pressure. The final samples were investigated via scanning electron microscopy (SEM)-energy-dispersive X-ray spectroscopy (EDS), XRD, Rietveld, and ultrasonic methods. Phase analysis showed tetragonal and orthorhombic KNN phases, and a contamination of (K2CO3·1.5H2O) was present. The obtained KNN polycrystals had a relative density above 95%. Texturing of the material was confirmed as a result of hot pressing.

Morphology and Wear Resistance of Composite Coatings Formed on a TA2 Substrate Using Hot-Dip Aluminising and Micro-Arc Oxidation Technologies

Materials ◽

10.3390/ma12050799 ◽

2019 ◽

Vol 12 (5) ◽

pp. 799 ◽

Cited By ~ 5

Author(s):

Shaopeng Wang ◽

Lian Zhou ◽

Changjiu Li ◽

Zhengxian Li ◽

Hongzhan Li

Keyword(s):

Wear Resistance ◽

Surface Composition ◽

Pure Titanium ◽

Titanium Substrate ◽

Ceramic Coatings ◽

Oxide Ceramic ◽

Pure Aluminium ◽

X Ray ◽

Micro Arc Oxidation

Aluminium layers were coated onto the surface of pure titanium using hot-dip aluminising technology, and then the aluminium layers were in situ oxidised to form oxide ceramic coatings, using the micro-arc oxidation (MAO) technique. The microstructure and composition distribution of the hot-dip aluminium coatings and ceramic layers were studied by using scanning electron microscopy and energy-dispersive X-ray spectroscopy. The phase structure of the MAO layers was studied using X-ray diffraction. The surface composition of the MAO layer was studied by X-ray photoelectron spectroscopy. The wear resistance of the pure titanium substrate and the ceramic layers coated on its surface were evaluated by using the ball-on-disc wear method. Therefore, aluminising coatings, which consist of a diffusion layer and a pure aluminium layer, could be formed on pure titanium substrates using the hot-dip aluminising method. The MAO method enabled the in-situ oxidation of hot-dip pure aluminium layers, which subsequently led to the formation of ceramic layers. Moreover, the wear resistance values of the ceramic layers were significantly higher than that of the pure titanium substrate.

Morphology of Polyethylene/Montmorillonite Nanocomposites Prepared by In Situ Polymerization

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.457-458.244 ◽

2013 ◽

Vol 457-458 ◽

pp. 244-247

Author(s):

Min Li ◽

Li Guang Xiao ◽

Hong Kai Zhao

Keyword(s):

Electron Microscopy ◽

In Situ Polymerization ◽

X Ray Diffraction ◽

X Ray ◽

Transmission Electron ◽

Reflection Peak ◽

Basal Reflection ◽

Polyethylene/montmorillonite (PE/MMT) nanocomposites were prepared by in situ polymerization. The morphology of MMT/MgCl2/TiCl4 catalyst and PE/MMT nanocomposites was investigated by scanning electron microscopy (SEM). It can be seen that MMT/MgCl2/TiCl4 catalyst remained the original MMT sheet structures and many holes were found in MMT and the morphology of PE/MMT nanocomposites is part of the sheet in the form of existence, as most of the petal structure. X-ray diffraction (XRD) and transmission electron microscopy (TEM) were carried out to characterize all the samples. XRD results reveal that the original basal reflection peak of PEI1 and PEI2 disappears completely and that of PEI3 become very weak. MMT/MgCl2/TiCl4 catalyst was finely dispersed in the PE matrix. Instead of being individually dispersed, most layers were found in thin stacks comprising several swollen layers.