Preparation of Chrome Carbide Coatings on T/P 24 by PIRAC

2012 ◽  
Vol 452-453 ◽  
pp. 77-80 ◽  
Author(s):  
Shou Jun Wu ◽  
Gutmanas Elazar
Keyword(s):  
Electron Microscopy ◽  
Phase Composition ◽  
Power Plants ◽  
Erosion Resistance ◽  
X Ray Diffraction ◽  
Surface Layers ◽  
X Ray ◽  
Carbide Coatings ◽  
Short Times ◽  
Scanning Electron

In order to improve oxidation/erosion resistance of the T/P 24 steel components used in advanced power plants, chrome carbide coatings were prepared by PIRAC (Powder Immersion Reaction Assisted Coating) on T/P24 at 700-1000°C. Microstructure and phase composition of the obtained surface layers were characterized employing X-ray diffraction and scanning electron microscopy with chemical analysis (SEM/EDS). Results showed that homogenous smooth chrome carbide coatings can be formed on the substrate. Phase composition of the prepared coatings are differs with PIRAC temperatures. Prepared at lower temperatures or short times treatment, Cr23C6, Cr7C3 and Cr3C2 can be detected in the coatings. While, at higher temperatures or longer treatment times, Cr23C6 is subtotal phase of the produced coating. Moreover, the lower the PIRAC temperature is, the more of Cr7C3 and Cr3C2 are. Thermodynamics calculation based on Gibbs free energy is applied to explain phase composition difference of the coatings.

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

2017 ◽  
Vol 12 (1) ◽  
pp. 63-77 ◽  
Author(s):  
Siriporn Sirikingkaew ◽  
Nuta Supakata
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Scanning Electron Microscopy ◽  
Compressive Strength ◽  
Phase Composition ◽  
Fly Ash ◽  
Industrial Waste ◽  
X Ray Diffraction ◽  
X Ray ◽  
Scanning Electron

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.

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

Materials ◽  
2019 ◽  
Vol 12 (24) ◽  
pp. 4171 ◽  
Author(s):  
Paweł Rutkowski ◽  
Jan Huebner ◽  
Adrian Graboś ◽  
Dariusz Kata ◽  
Dariusz Grzybek ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Rare Earth ◽  
Phase Composition ◽  
Powder Mixture ◽  
Hot Pressing ◽  
X Ray Diffraction ◽  
X Ray ◽  
Ultrasonic Methods ◽  
Scanning Electron

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.

Microstructure and Phase Composition of AlN/Al Composite Fabricated by Directed Melt Nitridation

2008 ◽  
Vol 368-372 ◽  
pp. 977-979
Author(s):  
Sheng Li Jin ◽  
Ya Wei Li ◽  
Jing Liu ◽  
Yuan Bing Li ◽  
Lei Zhao ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Phase Composition ◽  
Sandwich Structure ◽  
Ceramic Composite ◽  
Growth Direction ◽  
X Ray Diffraction ◽  
X Ray ◽  
Al Composite ◽  
Scanning Electron

AlN/Al ceramic composite was fabricated by directed melt nitridation of pure Al block covered with 10wt% Mg powder at 1300°C in a high purity flowing N2. Microstructure and phase composition of the composite were investigated by scanning electron microscopy with energy dispersive spectroscopy and X-ray diffraction. Results showed that AlN is the main phase in the composite and its lattice parameters of a and c are 3.1110Å and 4.9806Å, respectively. The phase composition of the composite changes along the growth direction and a gradient sandwich structure forms. The surface of the composite is made up of a dense and thin nodular AlN layer, underneath which an AlN/Al layer appears, followed by an AlN/Al/MgAl2O4 layer. Thermodynamic calculations predicted the formation of possible phases with the addition of Mg. It suggested that the content of Mg at the reaction frontier of nitridation is considerably lower to 0.15wt% where MgAl2O4 was stable, because of escape and reaction exhaustion of Mg. Once Mg is lower than 0.05wt%, only a dense AlN layer can exist, which prevents the further nitridation of Al melt.

Effect of Synthesis Conditions and Actinide Contents on Phase Composition of Actinide Bearing Ceramics

2003 ◽  
Vol 807 ◽  
Author(s):  
A. G. Ptashkin ◽  
S. V. Stefanovsky ◽  
S. V. Yudintsev ◽  
S. A. Perevalov
Keyword(s):  
Electron Microscopy ◽  
Solid Solution ◽  
Phase Composition ◽  
Fluorite Structure ◽  
X Ray Diffraction ◽  
X Ray ◽  
Synthesis Conditions ◽  
Reducing Conditions ◽  
Dispersive System ◽  
Scanning Electron

ABSTRACTPu-bearing zirconolite and pyrochlore based ceramics were prepared by melting under oxidizing and reducing conditions at 1550 °C. 239Pu content in the samples ranged between ∼10 and ∼50 wt.%. Phase composition of the ceramics and Pu partitioning were studied using X-ray diffraction (XRD) and scanning electron microscopy with energy dispersive system (SEM/EDS). Major phases in the samples were found to be the target zirconolite and pyrochlore as well as a cubic fluorite structure oxide. Normally the Pu content in the Pu host phases was 10–12 wt.%. This corresponds to the Pu content recommended for matrices for immobilization of excess weapons plutonium. At higher Pu content (up to 50 wt.%) additional phases, such as a PuO2-based cubic fluorite-structured solid solution, perovskite, and rutile were found.

Biomorphic SiC Prepared from Carbonized Millet by Sol-Gel and Carbothermal Reduction Processing

2010 ◽  
Vol 152-153 ◽  
pp. 1683-1686
Author(s):  
Qing Wang ◽  
Ya Hui Zhang
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Silicon Carbide ◽  
Phase Composition ◽  
Carbothermal Reduction ◽  
Sol Gel ◽  
X Ray Diffraction ◽  
X Ray ◽  
Carbon Template ◽  
Scanning Electron

Biomorphic silicon carbide (bioSiC) was prepared by high temperature pyrolysis and sol-gel and carbothermal reduction processing at 1600 oC. The morphology and microstructure of carbon-silica composites and purified bioSiC samples were characterized by scanning electron microscopy. The phase composition of the resulting sample was analyzed by X-ray diffraction. The results suggest that the bioSiC mainly consists of cubic ß-SiC, and principally replicates the shape and microstructure of the carbon template.

Biomorphic TiO2 Ceramics Prepared from Cotton Stalk

2012 ◽  
Vol 602-604 ◽  
pp. 526-529
Author(s):  
Qing Wang ◽  
Lin Zhang ◽  
Ya Hui Zhang
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Phase Composition ◽  
High Temperature ◽  
Sol Gel ◽  
Cotton Stalk ◽  
X Ray Diffraction ◽  
X Ray ◽  
Carbon Template ◽  
Scanning Electron

Biomorphic TiO2 was prepared by high temperature pyrolysis and a modified sol-gel route. The morphology and microstructure of TiO2 samples were characterized by scanning electron microscopy. The phase composition of the resulting sample was analyzed by X-ray diffraction. The results suggest that the biomorphic TiO2 mainly consists of rutile TiO2, and replicates the shape and part microstructure of the carbon template.

scholarly journals Evolution of Free Volumes in Polycrystalline BaGa2O4 Ceramics Doped with Eu3+ Ions

Crystals ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1515
Author(s):  
Halyna Klym ◽  
Ivan Karbovnyk ◽  
Andriy Luchechko ◽  
Yuriy Kostiv ◽  
Viktorija Pankratova ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Phase Composition ◽  
Grain Boundaries ◽  
Solid Phase ◽  
X Ray Diffraction ◽  
Spectroscopy Technique ◽  
X Ray ◽  
Positron Annihilation Lifetime ◽  
Scanning Electron

BaGa2O4 ceramics doped with Eu3+ ions (1, 3 and 4 mol.%) were obtained by solid-phase sintering. The phase composition and microstructural features of ceramics were investigated using X-ray diffraction and scanning electron microscopy in comparison with energy-dispersive methods. Here, it is shown that undoped and Eu3+-doped BaGa2O4 ceramics are characterized by a developed structure of grains, grain boundaries and pores. Additional phases are mainly localized near grain boundaries creating additional defects. The evolution of defect-related extended free volumes in BaGa2O4 ceramics due to the increase in the content of Eu3+ ions was studied using the positron annihilation lifetime spectroscopy technique. It is established that the increase in the number of Eu3+ ions in the basic BaGa2O4 matrix leads to the agglomeration of free-volume defects with their subsequent fragmentation. The presence of Eu3+ ions results in the expansion of nanosized pores and an increase in their number with their future fragmentation.

Preparation of Biomorphic SiC by Reactive Infiltration of Gaseous Si into Carbonized Millet

2010 ◽  
Vol 152-153 ◽  
pp. 1673-1676
Author(s):  
Qing Wang ◽  
Ya Hui Zhang
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Silicon Carbide ◽  
Phase Composition ◽  
Pyrolysis Process ◽  
X Ray Diffraction ◽  
X Ray ◽  
Reactive Infiltration ◽  
Carbon Template ◽  
Scanning Electron

Biomorphic silicon carbide (bioSiC) was prepared at 1800 oC by reactive infiltration of gaseous silicon into a carbon template derived from millet. The pyrolysis process of millet was measured by thermogravimetric analysis. The morphology and microstructures of carbon template and purified bioSiC samples were characterized by scanning electron microscopy. The phase composition of bioSiC was analyzed by X-ray diffraction. The results suggest that the bioSiC consists of major cubic ß-SiC and a few α-SiC, and principally replicates the shape and microstructure of the carbon template.

Study on the Surface Morphologies of Nickel-Phosphorus Ultra-Black Films

2014 ◽  
Vol 924 ◽  
pp. 166-169 ◽  
Author(s):  
Pan Pan Yue ◽  
Yong Zhong Jin ◽  
Xu Dong Hu ◽  
Hong Yang Yan ◽  
Guo Qing Zeng
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Phase Composition ◽  
Chemical Etching ◽  
Etching Time ◽  
X Ray Diffraction ◽  
X Ray ◽  
Black Films ◽  
Surface Morphologies ◽  
Scanning Electron

Ni-P ultra-black films having conical pores with the diameter of ~ 10-30 μm and the depth of ~ 15-30 μm were prepared by chemical etching of electroless plated Ni-P films using 8 mol/L nitric acid at 40 °C for 60 s. The phase composition and microstructure of the film samples were investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. The results show that the diameter and depth of the etching pores become larger and the flat top regions bounded by etching pores become smaller by the coalescence of adjacent pores with the increase of etching time. The surface morphologies of the etched Ni-P films are characterized by the distribution of conical pores.

Behavior of Some Tungsten Carbide Coatings in Molten Zinc

1996 ◽  
Author(s):  
A.J. Stavros
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Tungsten Carbide ◽  
The Other ◽  
Time To Failure ◽  
X Ray Diffraction ◽  
Molten Zinc ◽  
X Ray ◽  
Carbide Coatings ◽  
Scanning Electron

Abstract Two different W-Co-C powders were used in three deposition devices, the Super D-Gun, Jet Kote, and JP-5000 to produce coatings for laboratory immersion tests in molten zinc and %55Al-Zn. Resistance was evaluated as time to failure. Scanning electron microscopy and X-ray diffraction were used to characterize the structures ssid failure mechanism. All coatings were found to fail when the molten metal breached the coating thickness at weak spots and spread out over the underlying interface to lift the coating away from the underlying 316L substrate. These weak spots were "pits" on one Super D-Gun coating (the most resistant coating) and cracks on all the other coatings. No diffusion of zinc through the tungsten carbide coatings was observed.

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