scholarly journals Different Setting Conditions Affect Surface Characteristics and Microhardness of Calcium Silicate-Based Sealers

Scanning ◽  
2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
Dong-Kyu Yang ◽  
Sunil Kim ◽  
Jeong-Won Park ◽  
Euiseong Kim ◽  
Su-Jung Shin
Keyword(s):  
Calcium Silicate ◽  
Detrimental Effect ◽  
Surface Characteristics ◽  
Storage Conditions ◽  
Acid Solutions ◽  
X Ray Diffraction ◽  
Surface Microhardness ◽  
X Ray ◽  
Phosphate Buffered Saline ◽  
Scanning Electron

Objective. To investigate the effect of different setting conditions on surface microhardness and setting properties of calcium silicate-based sealers. Methods. Three sealers, EndoSequence Bioceramic (BC; Brasseler USA, Savannah, GA, USA), Endoseal MTA (ES; Maruchi, Wonju, Korea), and Well-Root ST (WR; Vericom, Chuncheon, Korea), were compared. Specimens were exposed to either butyric acid (pH 5.4) or phosphate-buffered saline (PBS [pH 7.4]) for 48 h and stored at 100% humidity for 12 days. The control specimens were stored at 100% humidity for 14 days. Surface microhardness was measured, topographic changes were observed, and phase analysis was performed using X-ray diffraction. Microhardness according to storage conditions was compared using one-way analysis of variance and Tukey’s multiple comparison tests (P<.05). Results. The BC and ES sealers exhibited decreased microhardness when stored in acid or PBS compared with control (P<.05). In the WR group, acid exposure lowered microhardness of the specimens compared with control (P<.05). Scanning electron microscopy revealed different topographies in specimens from all tested sealers exposed to acid or PBS. Conclusion. The surface microhardness of calcium silicate-based sealers was reduced by exposure to either acid or PBS. Acid solutions, however, had a more detrimental effect than PBS.

Photocatalytic activity of TiO2 synthesized by anodization and anodic spark deposition

MRS Advances ◽  
2020 ◽  
Vol 5 (61) ◽  
pp. 3141-3152
Author(s):  
Alma C. Chávez-Mejía ◽  
Génesis Villegas-Suárez ◽  
Paloma I. Zaragoza-Sánchez ◽  
Rafael Magaña-López ◽  
Julio C. Morales-Mejía ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Photocatalytic Activity ◽  
Surface Characteristics ◽  
Amorphous Solids ◽  
X Ray Diffraction ◽  
X Ray ◽  
Catalytic Activities ◽  
Anodic Spark Oxidation ◽  
Porous Surfaces ◽  
Scanning Electron

AbstractSeveral photocatalysts, based on titanium dioxide, were synthesized by spark anodization techniques and anodic spark oxidation. Photocatalytic activity was determined by methylene blue oxidation and the catalytic activities of the catalysts were evaluated after 70 hours of reaction. Scanning Electron Microscopy and X Ray Diffraction analysis were used to characterize the catalysts. The photocatalyst prepared with a solution of sulfuric acid and 100 V presented the best performance in terms of oxidation of the dye (62%). The electric potential during the synthesis (10 V, low potential; 100 V, high potential) affected the surface characteristics: under low potential, catalyst presented smooth and homogeneous surfaces with spots (high TiO2 concentration) of amorphous solids; under low potential, catalyst presented porous surfaces with crystalline solids homogeneously distributed.

scholarly journals Microstructure and properties of boronizing layer of Fe-based powder metallurgy compacts prepared by boronizing and sintering simultaneously

2009 ◽  
Vol 41 (2) ◽  
pp. 199-207 ◽  
Author(s):  
X. Dong ◽  
J. Hu ◽  
Z. Huang ◽  
H. Wang ◽  
R. Gao ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Wear Resistance ◽  
Wear Testing ◽  
Processing Temperature ◽  
X Ray Diffraction ◽  
Surface Microhardness ◽  
X Ray ◽  
Substrate Hardness ◽  
Scanning Electron

In this study, the boronized layers were formed on the surfaces of specimens with a composition of Fe-2 wt. % Cu-0.4 wt. % C by sintering and boronizing simultaneously, using a pack boronizing method. The processes were performed in the temperature range of 1050 - 1150 oC at a holding time of 4 hours in 97 % N2 and 3 % H2 atmosphere. Scanning electron microscopy examinations showed that the boronized layers formed on the surface of boronized and sintered specimens have a denticular morphology. The thicknesses of the boronized layers varied from 63 to 208 ?m depending on the processing temperature. The structures of the boronized layers were Fe2B and FeB confirmed by X-ray diffraction analysis. The microhardness values of boronized layers ranged from 1360 to 2066 HV0.3 much higher than that of substrate hardness which was about 186 HV0.3. Wear testing results showed that the wear resistance of the boronized and sintered specimens was significantly improved, resulting from increased surface microhardness.

scholarly journals Effect of Pulsed Current Frequency and Anodisation Time on Surface Properties of Electropolished and Nonelectropolished Titanium Substrates

2018 ◽  
Vol 2018 ◽  
pp. 1-8
Author(s):  
Victória da Costa Marba ◽  
Natal N. Regone ◽  
Eduardo N. Codaro ◽  
Heloisa A. Acciari
Keyword(s):  
Room Temperature ◽  
Anatase Phase ◽  
Surface Characteristics ◽  
Pulsed Current ◽  
X Ray Diffraction ◽  
Anodic Films ◽  
Current Frequency ◽  
X Ray ◽  
Titanium Substrates ◽  
Scanning Electron

Surface characteristics of anodic films formed on electropolished and nonelectropolished titanium substrates have been evaluated using different sets of anodisation parameters at room temperature. Surfaces were analysed by light microscopy, Raman spectroscopy, scanning electron microscopy, and X-ray diffraction. The formation of TiO2 anatase phase was only detected on nonelectropolished substrates and there seems to be a larger amount of anatase as samples are anodised; consequently, the smallest crystals were obtained at the highest frequency of pulsed current. EIS results showed that there is no difference in the degree of compactness along the layer thickness.

scholarly journals Effect of Metakaolin on Strength and Efflorescence Quantity of Cement-Based Composites

2013 ◽  
Vol 2013 ◽  
pp. 1-11 ◽  
Author(s):  
Tsai-Lung Weng ◽  
Wei-Ting Lin ◽  
An Cheng
Keyword(s):  
Compressive Strength ◽  
Image Analysis ◽  
Portland Cement ◽  
Detrimental Effect ◽  
Cement Mortar ◽  
Hydration Products ◽  
X Ray Diffraction ◽  
Replacement Ratio ◽  
X Ray ◽  
Scanning Electron

This study investigated the basic mechanical and microscopic properties of cement produced with metakaolin and quantified the production of residual white efflorescence. Cement mortar was produced at various replacement ratios of metakaolin (0, 5, 10, 15, 20, and 25% by weight of cement) and exposed to various environments. Compressive strength and efflorescence quantify (using Matrix Laboratory image analysis and the curettage method), scanning electron microscopy, and X-ray diffraction analysis were reported in this study. Specimens with metakaolin as a replacement for Portland cement present higher compressive strength and greater resistance to efflorescence; however, the addition of more than 20% metakaolin has a detrimental effect on strength and efflorescence. This may be explained by the microstructure and hydration products. The quantity of efflorescence determined using MATLAB image analysis is close to the result obtained using the curettage method. The results demonstrate the best effectiveness of replacing Portland cement with metakaolin at a 15% replacement ratio by weight.

scholarly journals Influence of Hydrothermal Temperature on Phosphorus Recovery Efficiency of Porous Calcium Silicate Hydrate

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Wei Guan ◽  
Fangying Ji ◽  
Qingkong Chen ◽  
Peng Yan ◽  
Weiwei Zhou
Keyword(s):  
Calcium Silicate ◽  
Calcium Silicate Hydrate ◽  
Phosphorus Recovery ◽  
Limiting Factor ◽  
Recovery Efficiency ◽  
X Ray Diffraction ◽  
Hydrothermal Temperature ◽  
X Ray ◽  
Recovery Performance ◽  
Scanning Electron

Porous calcium silicate hydrate (PCSH) was synthesized by carbide residue and white carbon black. The influence of hydrothermal temperature on phosphorus recovery efficiency was investigated by Field Emission Scanning Electron Microscopy (FESEM), Brunauer-Emmett-Teller (BET), and X-Ray Diffraction (XRD). Hydrothermal temperature exerted significant influence on phosphorus recovery performance of PCSH. Hydrothermal temperature 170°C for PCSH was more proper to recover phosphorus. PCSH could recover phosphorus with content of 18.51%. The law of Ca2+and OH−release was the key of phosphorus recovery efficiency, and this law depended upon the microstructure of PCSH. When the temperature of synthesis reached to 170°C, the reactions between CaO and amorphous SiO2were more efficient. Solubility of SiO2was a limiting factor.

Preparation of Nano-Sized Wollastonite Using Calcium Silicate Residue of Potassium Feldspar after Extraction of Potassium and Alumina

2014 ◽  
Vol 633 ◽  
pp. 35-38 ◽  
Author(s):  
Jian Chen ◽  
Jing Yang ◽  
Hong Wen Ma
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Particle Size ◽  
Calcium Silicate ◽  
Potassium Feldspar ◽  
X Ray Diffraction ◽  
X Ray ◽  
Calcined Temperature ◽  
Orientation Growth ◽  
Scanning Electron

In this paper, wollastonite nanopowder were successfully synthesized by the surfactants modified-calcined method using calcium silicate residue of potassium feldspar after extraction of potassium and alumina. The effects of modifier and calcined temperature on the phase composition, morphology and microstructure were studied by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results showed that the phase of samples with different modifier processing is wollastonite-2M, while CTAB as modifier can avoid preferred orientation growth. The obtained wollastonite powder is spherical in morphology and well dispersed with the particle size of approximately 150nm.

scholarly journals Synthesis of nanocomposites based on strontium stannate

2021 ◽  
Vol 340 ◽  
pp. 01049
Author(s):  
Anton Loginov ◽  
Alexandr Aparnev
Keyword(s):  
Electron Microscopy ◽  
Thermal Analysis ◽  
Acid Solutions ◽  
X Ray Diffraction ◽  
Decomposition Products ◽  
X Ray ◽  
Hydrochloric Acid Solutions ◽  
Strontium Stannate ◽  
Double Hydroxide ◽  
Scanning Electron

From hydrochloric acid solutions of strontium and tin(IV) by addition of ammonia until pH = 10 was obtained double hydroxide of strontium-tin(IV) SrSn(OH)6. The process of double hydroxide thermolysis and the phase composition of decomposition products were studied by differential thermal analysis, X-ray diffraction and scanning electron microscopy. It is shown that the main dehydration step is completed at a temperatureofnearly350°CandX-rayamorphousproductisformed which converts into the crystalline phase of strontium stannate at a temperature above 650°C.

The Use of Advanced Analytical Techniques for Characterization of the Chemical, Physical, and Crystallographic Nature of a Surface

1973 ◽  
Vol 31 ◽  
pp. 132-133 ◽  
Author(s):  
R. E. Herfert
Keyword(s):  
Surface Characterization ◽  
Analytical Techniques ◽  
X Ray Diffraction ◽  
Depth Of Penetration ◽  
X Ray ◽  
The Past ◽  
Transmission Electron ◽  
Scanning Electron

Studies of the nature of a surface, either metallic or nonmetallic, in the past, have been limited to the instrumentation available for these measurements. In the past, optical microscopy, replica transmission electron microscopy, electron or X-ray diffraction and optical or X-ray spectroscopy have provided the means of surface characterization. Actually, some of these techniques are not purely surface; the depth of penetration may be a few thousands of an inch. Within the last five years, instrumentation has been made available which now makes it practical for use to study the outer few 100A of layers and characterize it completely from a chemical, physical, and crystallographic standpoint. The scanning electron microscope (SEM) provides a means of viewing the surface of a material in situ to magnifications as high as 250,000X.

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.

Sem and X-Ray Analysis of Renal and Biliary Calculi

1976 ◽  
Vol 34 ◽  
pp. 306-307
Author(s):  
R. J. Narconis ◽  
G. L. Johnson
Keyword(s):  
Chemical Constituents ◽  
Natural State ◽  
X Ray Diffraction ◽  
Chemical Methods ◽  
X Ray ◽  
Additional Dimension ◽  
Biliary Calculi ◽  
Calculus Formation ◽  
Scanning Electron

Analysis of the constituents of renal and biliary calculi may be of help in the management of patients with calculous disease. Several methods of analysis are available for identifying these constituents. Most common are chemical methods, optical crystallography, x-ray diffraction, and infrared spectroscopy. The application of a SEM with x-ray analysis capabilities should be considered as an additional alternative.A scanning electron microscope equipped with an x-ray “mapping” attachment offers an additional dimension in its ability to locate elemental constituents geographically, and thus, provide a clue in determination of possible metabolic etiology in calculus formation. The ability of this method to give an undisturbed view of adjacent layers of elements in their natural state is of advantage in determining the sequence of formation of subsequent layers of chemical constituents.

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