scholarly journals Crosslinking Behavior of UV-Cured Polyorganosilazane as Polymer-Derived Ceramic Precursor in Ambient and Nitrogen Atmosphere

Polymers ◽  
2021 ◽  
Vol 13 (15) ◽  
pp. 2424
Author(s):  
Afnan Qazzazie-Hauser ◽  
Kirsten Honnef ◽  
Thomas Hanemann
Keyword(s):  
Chemical Composition ◽  
Chemical Conversion ◽  
Ceramic Coatings ◽  
Nitrogen Atmosphere ◽  
Silicon Carbonitride ◽  
Ambient Atmosphere ◽  
Ceramic Yield ◽  
Uv Led ◽  
Dehydrogenation Reactions ◽  
Vinyl Group

Polymer-derived ceramics (PDCs) based on silicon precursor represent an outstanding material for ceramic coatings thanks to their extraordinary versatile processibility. A promising example of a silicone precursor, polyorganosilazane (Durazane 1800), was studied concerning its crosslinking behavior by mixing it with three different photoinitiators, and curing it by two different UV-LED sources under both nitrogen and ambient atmosphere. The chemical conversion during polymerization and pyrolysis was monitored by FTIR spectroscopy. Pyrolysis was performed in a nitrogen atmosphere at 950 °C. The results demonstrate that polyorganosilazane can be cured by the energy-efficient UV-LED source at room temperature in nitrogen and ambient atmosphere. In nitrogen atmosphere, already common reactions for polysilazanes, including polyaddition of the vinyl group, dehydrogenation reactions, hydrosilylation, and transamination reaction, are responsible for crosslinking. Meanwhile, in ambient atmosphere, hydrolysis and polycondensation reactions occur next to the aforementioned reactions. In addition, the type of photoinitiator has an influence on the conversion of the reactive bonds and the chemical composition of the resulting ceramic. Furthermore, thermogravimetric analysis (TGA) was conducted in order to measure the ceramic yield of the cured samples as well as to study their decomposition. The ceramic yield was observed in the range of 72 to 78% depending on the composition and the curing atmosphere. The curing atmosphere significantly impacts the chemical composition of the resulting ceramics. Depending on the chosen atmosphere, either silicon carbonitride (SiCN) or a partially oxidized SiCN(O) can be produced.

scholarly journals Effect of oxidizing and reducing atmospheres on Ba(Ti0.90 Zr0.10)o3:2V ceramics as characterized by piezoresponse force microscopy

2011 ◽  
Vol 5 (3) ◽  
pp. 139-147 ◽  
Author(s):  
Francisco Moura ◽  
Alexandre Simões ◽  
Carla Riccardi ◽  
Maria Zaghete ◽  
Jose Varela ◽  
...  
Keyword(s):  
Data Storage ◽  
Photoelectron Spectroscopy ◽  
Ferroelectric Properties ◽  
Piezoresponse Force Microscopy ◽  
Nitrogen Atmosphere ◽  
Ambient Atmosphere ◽  
Practical Applications ◽  
Force Microscopy ◽  
Storage Media ◽  
Piezoelectric Force Microscopy

The effect of annealing atmospheres (Atamb, N2 and O2) on the electrical properties of Ba(Ti0.90Zr0.10 )O3:2V (BZT10:2V) ceramics obtained by the mixed oxide method was investigated. X-ray photoelectron spectroscopy (XPS) analysis indicates that oxygen vacancies present near Zr and Ti ions reduce ferroelectric properties, especially in samples treated in an ambient atmosphere (Atamb ). BZT10:2V ceramics sintered in a nitrogen atmosphere showed better dielectric behaviour at room temperature with a dielectric permittivity measured at a frequency of 10 kHz equal to 16800 with dielectric loss of 0.023. Piezoelectric force microscopy (PFM) images reveal improvement in the piezoelectric coefficient by sintering the sample under nitrogen atmosphere. Thus, BZT10:2V ceramics sintered under a nitrogen atmosphere can be useful for practical applications which include nonvolatile digital memories, spintronics and data-storage media.

scholarly journals Effect of Thermal and Oxidative Aging on Asphalt Binders Rheology and Chemical Composition

Materials ◽  
2020 ◽  
Vol 13 (19) ◽  
pp. 4438
Author(s):  
Ingrid Gabrielle do Nascimento Camargo ◽  
Bernhard Hofko ◽  
Johannes Mirwald ◽  
Hinrich Grothe
Keyword(s):  
Thin Film ◽  
Asphalt Binder ◽  
Chemical Characterization ◽  
Nitrogen Atmosphere ◽  
Asphalt Binders ◽  
Effect Of Temperature ◽  
Ambient Atmosphere ◽  
Test Procedures ◽  
Oxidative Aging ◽  
Aging Test

Aging of asphalt binders is one of the main causes of its hardening, which negatively affects the cracking and fatigue resistance of asphalt binders. Understanding asphalt aging is crucial to improve the durability of asphalt pavements. In this regard, this study aims at understanding and differentiating the effect of temperature and oxygen uptake on the aging mechanisms of unmodified asphalt binders. For that, four laboratory aging procedures were employed. The two standardized procedures, rolling thin-film oven test (RTFOT) and pressure aging vessel (PAV), were considered to simulate the short-term and long-term aging of the asphalt binders, respectively. In addition, two thin-film aging test procedures, the nitrogen atmosphere oven aging test (NAAT) and ambient atmosphere oven aging test (OAAT) were employed to assess the effect of thermal and oxidative aging on unmodified asphalt binder properties. The NAAT procedure is based on the principle that the inert gas minimizes the oxidative aging. The rheological and chemical characterization showed that the high temperatures considered during the NAAT procedure did not change the properties of the unmodified asphalt binders. Therefore, it can be hypothesized that no significant thermal and oxidative aging was observed during NAAT aging procedure for the considered binders and that oxidative aging is the main cause for the hardening.

scholarly journals Sub-1.4eV bandgap inorganic perovskite solar cells with long-term stability

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Mingyu Hu ◽  
Min Chen ◽  
Peijun Guo ◽  
Hua Zhou ◽  
Junjing Deng ◽  
...  
Keyword(s):  
Solar Cells ◽  
Perovskite Solar Cells ◽  
Nitrogen Atmosphere ◽  
Ambient Atmosphere ◽  
Low Bandgap ◽  
Long Term Stability ◽  
Device Stability ◽  
Controlled Exposure ◽  
Halide Perovskites

AbstractState-of-the-art halide perovskite solar cells have bandgaps larger than 1.45 eV, which restricts their potential for realizing the Shockley-Queisser limit. Previous search for low-bandgap (1.2 to 1.4 eV) halide perovskites has resulted in several candidates, but all are hybrid organic-inorganic compositions, raising potential concern regarding device stability. Here we show the promise of an inorganic low-bandgap (1.38 eV) CsPb0.6Sn0.4I3 perovskite stabilized via interface functionalization. Device efficiency up to 13.37% is demonstrated. The device shows high operational stability under one-sun-intensity illumination, with T80 and T70 lifetimes of 653 h and 1045 h, respectively (T80 and T70 represent efficiency decays to 80% and 70% of the initial value, respectively), and long-term shelf stability under nitrogen atmosphere. Controlled exposure of the device to ambient atmosphere during a long-term (1000 h) test does not degrade the efficiency. These findings point to a promising direction for achieving low-bandgap perovskite solar cells with high stability.

scholarly journals Microstructural characterization and film-forming mechanism of a phosphate chemical conversion ceramic coating prepared on the surface of 2A12 aluminum alloy

RSC Advances ◽  
2019 ◽  
Vol 9 (33) ◽  
pp. 18767-18775
Author(s):  
Shuai Huang ◽  
Jian Wang ◽  
Xiaowei Wei ◽  
Yuli Zhou ◽  
Lijun Wang ◽  
...  
Keyword(s):  
Aluminum Alloy ◽  
Ceramic Coating ◽  
Microstructural Characterization ◽  
Chemical Conversion ◽  
Ceramic Coatings ◽  
Conversion Process ◽  
Forming Mechanism ◽  
Alloy Substrate ◽  
Film Forming

Phosphate chemical conversion (PCC) ceramic coatings on the surface of 2A12 aluminum alloy substrate have been fabricated by a simple and inexpensive chemical conversion process in CrO3–NaF–H3PO4 solution.

Crystalline Defects in Silicon Wafer Caused by Prolonged High-Temperature Annealing in Nitrogen Atmosphere

2013 ◽  
Vol 699 ◽  
pp. 445-449
Author(s):  
Haruo Nakazawa ◽  
Masaaki Ogino ◽  
Hideaki Teranishi ◽  
Yoshikazu Takahashi ◽  
Hitoshi Habuka
Keyword(s):  
High Temperature ◽  
Silicon Wafer ◽  
Secondary Ion Mass Spectrometry ◽  
Nitrogen Atmosphere ◽  
Ambient Atmosphere ◽  
High Concentration ◽  
Cross Sectional ◽  
X Ray ◽  
Transmission Electron ◽  
Elemental Analyses

A floating zone (FZ) silicon wafer produced from a Czochralski (CZ) single-crystal ingot was subjected to prolonged annealing at a high temperature. Precipitates were formed in a N2(70%)+O2(30%) ambient atmosphere. The precipitate regions manifested themselves as dark concentric rings in the X-ray topographs. According to the results of cross-sectional transmission electron microscopy observations and energy-dispersive X-ray spectroscopy elemental analyses, nitrogen was distributed throughout the precipitate regions, while oxygen was rich in the periphery of the regions. A high concentration of nitrogen was also directly detected by secondary ion mass spectrometry in the mid-depth of the wafer in the precipitate regions. Electron diffraction analysis of the precipitates showed that their phase was α-Si3N4.

Surface Chemical Analysis of Nanoparticles for Commercial Products and Devices

2013 ◽  
Vol 1533 ◽  
Author(s):  
Marie-Isabelle Baraton
Keyword(s):  
Chemical Composition ◽  
Surface Chemistry ◽  
Surface Analysis ◽  
Surface Composition ◽  
High Vacuum ◽  
Surface Reactivity ◽  
Ultra High Vacuum ◽  
Ambient Atmosphere ◽  
Surface Chemical ◽  
Surface Chemical Composition

ABSTRACTAmongst the list of the measurands specific to nanoparticles, size and shape definitely matter but surface chemistry is also often cited. While it is now largely recognized that surface composition, structure and reactivity are perhaps the dominant parameters controlling properties of nanoparticles, surface chemistry is one of the key characteristics of nanoparticles which is seldom or inappropriately evaluated, as it has been identified by international organizations (such as ISO, BIPM or CEN). The usual techniques for surface analysis of materials often require ultra-high vacuum (UHV) conditions and are hardly applicable to nanoparticles. Moreover, because the surface chemical composition and reactivity are dependent on the environmental conditions, the results obtained under UHV cannot be extrapolated to nanoparticles in ambient atmosphere or dispersed in liquids.After an analysis of the stakes and challenges in the surface characterization of nanoparticles and a very brief overview of the usual techniques for surface studies, this paper presents the performance of Fourier transform infrared (FTIR) spectroscopy to investigate surface chemical composition, surface reactivity and surface functionalization of nanoparticles. As illustrating examples, the results of the FTIR surface analysis of different kinds of ceramic nanoparticles are discussed with regard to several fields of applications.

scholarly journals Optimization of cellulose acrylate and grafted 4-vinylpyridine and 1-vinylimidazole synthesis

2010 ◽  
Vol 64 (6) ◽  
pp. 529-535 ◽  
Author(s):  
Vaso Bojanic
Keyword(s):  
Noble Metals ◽  
Radical Copolymerization ◽  
Nitrogen Atmosphere ◽  
Molar Ratio ◽  
Vinyl Monomers ◽  
Acryloyl Chloride ◽  
Optimal Conditions ◽  
Grafting Reaction ◽  
Elementary Analysis ◽  
Vinyl Group

Optimization of cellulose acrylate synthesis by reaction with sodium cellulosate and acryloyl chloride was carried out. Optimal conditions for conducting the synthesis reaction of cellulose acrylate were as follows: the molar ratio of cellulose/potassium-t-butoxide/acryloyl chloride was 1:3:10 and the optimal reaction time was 10 h. On the basis of elemental analysis with optimal conditions for conducting the reaction of cellulose acrylate, the percentage of substitution of glucose units in cellulose Y = 80.7%, and the degree of substitution of cellulose acrylate DS = 2.4 was determined. The grafting reaction of acrylate vinyl monomers onto cellulose in acetonitrile with initiator azoisobutyronitrile (AIBN) in a nitrogen atmosphere was performed, by mixing for 5 h at acetonitrile boiling temperature. Radical copolymerization of synthesized cellulose acrylate and 4-vinylpyridine, 1-vinylimidazole, 1-vinyl-2-pyrrolidinone and 9-vinylcarbazole, cellulose-poly-4-vinylpyridine (Cell-PVP), cellulose-poly-1- vinylimidazole (Cell-PVIm) and cellulose-poly-1-vinyl-2-pyrrolidinone (Cell-P1V2P) and cellulose-poly-9-vinylcarbazole (Cell-P9VK) were synthesized. Acrylate cellulose and cellulose grafted copolymers were confirmed by IR spectroscopy, based on elementary analysis and the characteristics of grafted copolymers of cellulose were determined. The mass share of grafted copolymers, X, the relationship of derivative parts/cellulose vinyl group, Z, and the degree of grafting copolymers of cellulose (mass%) were determined. In reaction of methyl iodide and cellulose-poly-4-vinylpyridine (Cell-PVP) the cellulose-1-methyl-poly-4-vinylpyridine iodide (Cell-1-Me-PVPJ) was synthesized. Cellulose acrylate and grafted copolymers were obtained with better thermal, electrochemical and ion-emulation properties for bonding of noble metals Au, Pt, Pd from water solutions. The synthesis optimization of cellulose acrylate was applied as a model for the synthesis of grafted lignin copolymers and grafted tannin polymers with vinyl monomers.

Structure and Optical Properties of Magnetron-Sputtered SiOx Layers with Silicon Nanoparticles

2010 ◽  
Vol 303-304 ◽  
pp. 7-19
Author(s):  
L. Khomenkova ◽  
N. Korsunska ◽  
T. Stara ◽  
Y. Goldstein ◽  
J. Jedrzejewski ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Silicon Content ◽  
Silicon Nanoparticles ◽  
Depth Distribution ◽  
Blue Shift ◽  
Nitrogen Atmosphere ◽  
Emission Characteristics ◽  
Particle Sizes ◽  
Nanocrystal Formation ◽  
Si Content

The properties of SiOx layer prepared by magnetron sputtering is studied by photoluminescence Auger and SIMS methods. The depth distribution of emission characteristics and chemical composition is obtained. It is shown that as-sputtered SiOx layers are non-emitted and characterized by homogeneous enough chemical composition. High-temperature annealing in nitrogen atmosphere stimulates not only the Si nanocrystal formation but also the redistribution of silicon and the appearance of Si depleted region near layer-substrate interface. The last process is found to be dependent on excess Si content. It is found that decrease of silicon content in the depth of annealed layers is followed by the decrease of particle sizes that is proved by the blue shift of photoluminescence maximum. The possible reasons of the appearance of Si depleted region are discussed.

Comparison of Plasma-Sprayed Coatings Produced in Argon or Nitrogen Atmosphere

1997 ◽  
Author(s):  
M. Leylavergne ◽  
A. Vardelle ◽  
B. Dussoubs ◽  
N. Goubot
Keyword(s):  
Plasma Spraying ◽  
Nitrogen Atmosphere ◽  
Cryogenic Cooling ◽  
Ambient Atmosphere ◽  
Air Plasma ◽  
Spray Process ◽  
Plasma Sprayed Coatings ◽  
Plasma Sprayed ◽  
Thick Coatings ◽  
Sprayed Coatings

Abstract When spraying is conducted in the ambient atmosphere, the entrainment of air cools down the plasma jet and affects its expansion. It may also cause the oxidation or the chemical decomposition of the sprayed materials. Inert Plasma Spraying (IPS), generally conducted in argon atmospheres, prevents these phenomena. However, the main drawbacks of IPS in comparison with air plasma spraying are the capital and apparating costs. To reduce the latter by 25 to 30%, nitrogen atmospheres may be used as a substitute for the conventional argon atmosphere. This paper presents a study in which titanium carbide and niobium powders were sprayed in argon and nitrogen atmospheres. Cryogenic cooling of the substrate was used during the spray process. This helps to maintain a low temperature in the chamber, produces thick coatings and allows the use of substrate materials that are sensitive to heat. The adhesion, roughness and microstructure of the coatings produced in both atmospheres are compared as well as their nitrogen content.

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