Low Thermal Conductivity Ceramics for Thermal Barrier Coatings

2007 ◽  
Vol 336-338 ◽  
pp. 1764-1766 ◽  
Author(s):  
Ye Xia Qin ◽  
Jing Dong Wang ◽  
Wei Pan ◽  
Chun Lei Wan ◽  
Zhi Xue Qu
Keyword(s):  
Electron Microscopy ◽  
Thermal Conductivity ◽  
Scanning Electron Microscopy ◽  
Rare Earth ◽  
Thermal Barrier Coatings ◽  
Thermal Barrier ◽  
X Ray Diffraction ◽  
Barrier Coatings ◽  
X Ray ◽  
Scanning Electron

This paper summarizes the basic properties of a series of rare-earth zirconate ceramics (Gd2Zr2O7, Sm2Zr2O7, Dy2Zr2O7, Er2Zr2O7 and Yb2Zr2O7). The phases and microstructures were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Thermal properties of these materials were determined. The results indicated that Sm2Zr2O7 rare-earth zirconate ceramics have the lower thermal conductivity and the highest thermal expansion coefficient than other rare-earth zirconate ceramics. The dielectric constant decreases with the increase of atomic number.

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.

Study on Microstructure of NiCrMoY Alloy Coatings

2014 ◽  
Vol 577 ◽  
pp. 62-65
Author(s):  
Chun Lian Hu ◽  
Shang Lin Hou
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Rare Earth ◽  
High Frequency ◽  
Flame Spray ◽  
X Ray Diffraction ◽  
X Ray ◽  
New Phase ◽  
Scanning Electron ◽  
High Frequency Induction

The microstructure of rare earth NiCrMoY alloy manufactured by atomization and oxygen-acetylene flame spray and high frequency induction remelting technique is investigated by a combination of scanning electron microscopy (SEM), energy spectrum, X-ray diffraction meter (XRD). The results indicate that Microstructure of NiCrMoY alloy coatings are finer and bulk-and needle-like hard Metallograph are precipitated, a new phase MoB is produced.

Synchrotron X-Ray Diffraction to Quantify In-Situ Strain on Rare-Earth Doped Yttria-Stabilized Zirconia Thermal Barrier Coatings

2021 ◽  
Author(s):  
Quentin Fouliard ◽  
Johnathan Hernandez ◽  
Hossein Ebrahimi ◽  
Khanh Vo ◽  
Ranajay Ghosh ◽  
...  
Keyword(s):  
Rare Earth ◽  
Gas Turbine ◽  
Thermal Barrier Coatings ◽  
Gas Turbine Engine ◽  
Temperature Sensing ◽  
Thermal Barrier ◽  
X Ray Diffraction ◽  
Barrier Coatings ◽  
Turbine Engine ◽  
X Ray

Abstract The recent advancement in multifunctional thermal barrier coatings (TBCs) for temperature sensing or defect monitoring has gained interest over the past decade as they have shown great potential for optimized engine operation with higher efficiency, reduced fuel consumption and maintenance costs. Specifically, sensor coatings containing luminescent ions enable materials monitoring using integrated spectral characteristics. While facilitating sensing capabilities, luminescent rare-earth dopants ideally present minimal intrusiveness for the thermal barrier coating. However, the effects of rare-earth dopant addition on thermomechanical and thermochemical properties remain unclear. Our study intends to fill this knowledge gap by characterizing coatings’ internal thermomechnical properties under realistic gas turbine engine operating temperatures. In this work, TBC configurations including industry standard coatings and sensor coatings were compared to quantify dopant intrusiveness. The TBC configurations have been characterized using high-energy synchrotron X-ray diffraction while being heated up to gas turbine engine temperatures. The TBC samples have been subjected to a single cycle thermal load with multiple ramps and holds during XRD data collection. Depth-resolved XRD was used to obtain the 2D diffraction patterns corresponding to each depth location for the determination of strain distributions along the TBCs. Internal strains and stresses acting through the coatings were quantified mostly highlighting that there is negligible variation between the standard and novel sensor coatings. Thus, the thermal response at high temperature remains unaffected with addition of luminescent dopants. This evaluation of novel coating configurations provides valuable insight for future safe implementation of these temperature sensing coatings without performance reductions.

Novel Catalytic Systems Based on Platinum Catalysts

2020 ◽  
Vol 299 ◽  
pp. 1033-1037
Author(s):  
G. M. Kurunina ◽  
O.M. Ivankina ◽  
G. M. Butov
Keyword(s):  
Electron Microscopy ◽  
Thermal Analysis ◽  
Scanning Electron Microscopy ◽  
Rare Earth ◽  
Diffraction Analysis ◽  
Platinum Catalysts ◽  
X Ray Diffraction ◽  
Catalytic Systems ◽  
X Ray ◽  
Scanning Electron

The paper presents a method for the production of 1% platinum catalysts containing oxides of rare-earth elements (REE); it also dwells upon the results of analyzing such catalysts by scanning electron microscopy (SEM), x-ray diffraction analysis (XDA), and thermal analysis (DTA-TGA).

Synthesis and Characterization of Mixed Rare Earths Hydroxide Catalyst

2018 ◽  
Vol 936 ◽  
pp. 53-57
Author(s):  
Bheechanat Duangdee ◽  
Dussadee Rattanaphra ◽  
Anusith Thanapimmetha ◽  
Maythee Saisriyoot ◽  
Penjit Srinophakun
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Rare Earth ◽  
Rare Earths ◽  
Synthesis And Characterization ◽  
X Ray Diffraction ◽  
X Ray ◽  
Co Precipitation ◽  
Scanning Electron

This work presents the synthesis and characterization of mixed rare earths hydroxide heterogeneous catalyst. The catalysts were prepared by co-precipitation of mixed rare earths with NaOH at different pH (6, 7 and 12). The prepared catalysts were characterized by X-ray fluorescence (XRF), X-ray diffraction (XRD) and scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM–EDS). The XRF results showed that the catalyst composed of cerium (Ce), neodymium (Nd), lanthanum (La), praseodymium (Pr) and samarium (Sm) being predominant at pH up to 7. Particularly, cerium (Ce) was favorable precipitation at pH 7. This results were confirm by SEM-EDS. The Ce (OH)3 phase was clearly observed for the mixed rare earth catalyst precipitated at pH 7. The XRF, SEM-EDS and XRD results were consistency.

Mechanical Alloying Synthesis of K2Bi8Se13– type Solid Solutions

2007 ◽  
Vol 1044 ◽  
Author(s):  
Nikolaos Toumpas ◽  
Theodora Kyratsi ◽  
Euripides Hatzikraniotis ◽  
Andreas Tsiappos ◽  
Eleni Pavlidou ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Thermal Conductivity ◽  
Scanning Electron Microscopy ◽  
Electrical Properties ◽  
Mechanical Alloying ◽  
Solid Solutions ◽  
Structural Features ◽  
X Ray Diffraction ◽  
X Ray ◽  
Scanning Electron

AbstractSolid solutions of β-K2Bi8-xSbxSe13are an interesting series of materials for thermoelectric investigations due to their very low thermal conductivity and highly anisotropic electrical properties. In this work, we aimed to synthesize solid solutions of β-K2Bi8-xSbxSe13type materials using powder techniques. The synthesis was based on mechanical alloying as well as sintering procedures. The products were studied in terms of structural features, composition and purity with powder x-ray diffraction, scanning electron microscopy and energy dispersive spectroscopy. Preliminary results on thermoelectric properties as well as IR reflectivity measurements are presented.

Identification of calcium oxalate crystals in dried or fixed tobacco leaf

1984 ◽  
Vol 42 ◽  
pp. 288-289
Author(s):  
Vicki L. Baliga ◽  
Mary Ellen Counts
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Calcium Oxalate ◽  
Growth And Development ◽  
Polarized Light ◽  
Calcium Oxalate Crystals ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Scanning Electron

Calcium is an important element in the growth and development of plants and one form of calcium is calcium oxalate. Calcium oxalate has been found in leaf seed, stem material plant tissue culture, fungi and lichen using one or more of the following methods—polarized light microscopy (PLM), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and x-ray diffraction.Two methods are presented here for qualitatively estimating calcium oxalate in dried or fixed tobacco (Nicotiana) leaf from different stalk positions using PLM. SEM, coupled with energy dispersive x-ray spectrometry (EDS), and powder x-ray diffraction were used to verify that the crystals observed in the dried leaf with PLM were calcium oxalate.

Environmental scanning electron microscopy of fresh human gallstones reveals new morphologies of precipitated calcium salts

1992 ◽  
Vol 50 (2) ◽  
pp. 1322-1323
Author(s):  
Howard S. Kaufman ◽  
Keith D. Lillemoe ◽  
John T. Mastovich ◽  
Henry A. Pitt
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Environmental Scanning Electron Microscopy ◽  
Environmental Scanning ◽  
X Ray Diffraction ◽  
Calcium Salts ◽  
Cholesterol Gallstones ◽  
X Ray ◽  
Ca Carbonate ◽  
Scanning Electron

Gallstones contain precipitated cholesterol, calcium salts, and proteins. Calcium (Ca) bilirubinate, palmitate, phosphate, and carbonate occurring in gallstones have variable morphologies but characteristic windowless energy dispersive x-ray (EDX) spectra. Previous studies of gallstone microstructure and composition using scanning electron microscopy (SEM) with EDX have been limited to dehydrated samples. In this state, Ca bilirubinates appear as either glassy masses, which predominate in black pigment stones, or as clusters, which are found mostly in cholesterol gallstones. The three polymorphs of Ca carbonate, calcite, vaterite, and aragonite, have been identified in gallstones by x-ray diffraction, however; the morphologies of these crystals vary in the literature. The purpose of this experiment was to study fresh gallstones by environmental SEM (ESEM) to determine if dehydration affects gallstone Ca salt morphology.Gallstones and bile were obtained fresh at cholecystectomy from 6 patients. To prevent dehydration, stones were stored in bile at 37°C. All samples were studied within 4 days of procurement.

PENINGKATAN LAJU DISOLUSI ACYCLOVIR DENGAN METODE SISTEM DISPERSI PADAT MENGGUNAKAN POLOXAMER 188

2016 ◽  
Vol 5 (1) ◽  
pp. 6
Author(s):  
Budi Setiawan ◽  
Erizal Zaini ◽  
Salman Umar
Keyword(s):  
Electron Microscopy ◽  
Thermal Analysis ◽  
Scanning Electron Microscopy ◽  
Fourier Transform ◽  
Differential Thermal Analysis ◽  
Fourier Transform Infrared ◽  
X Ray Diffraction ◽  
Poloxamer 188 ◽  
X Ray ◽  
Scanning Electron

Sebuah penelitian tentang sistem dispersi padat dari asiklovir dengan poloxamer 188 telah dilakukan formulasi dengan pencampuran secara fisika dengan rasio 1 : 1, 1 : 3, 1 : 5 dan dispersi padat 1 : 1, 1 : 3, 1 : 5 dan penggilingan 1:1 sebagai pembanding. Dispersi padat dibuat menggunakan metode pencairan (fusi), yang digabung dengan poloxamer 188 pada hotplate kemudian asiklovir dimasukkan ke dalam hasil poloxamer 188 lalu di kocok hingga membentuk masa homogen. Semua formula yang terbentuk termasuk asiklovir poloxamer 188 murni dianalisis karakterisasinya dengan Differential Thermal Analysis (DTA), X-ray Diffraction, Scanning Electron Microscopy (SEM), dan Fourier Transform Infrared (FTIR), kemudian pengambilan dilakukan  (penentuan kadar) mengunakan spektrofotometer UV pada panjang gelombang 257,08 nm dan uji laju disolusi dengan aquadest bebas CO2 menggunakan metode dayung. Hasil pengambilan  (penentuan kadar) menunjukkan bahwa semua formula memenuhi persyaratan farmakope Amerika edisi 30 dan farmakope Indonesia edisi 4 yaitu 95-110%. Sedangkan hasil uji laju disolusi untuk campuran fisik 1: 1, dan dispersi padat 1: 1, dan penggilingan 1: 1 menunjukkan peningkatan yang nyata dibandingkan asiklovir murni. Hal ini juga dapat dilihat dari hasil perhitungan statistik  menggunakan analisis varian satu arah  SPSS 17.

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