Ceramic Coatings on Graphite via Polymer Vapor Pyrolysis Deposition Process

Silicon carbide coatings on graphite were prepared through polymer vapor pyrolysis deposition process (PVPD) under N2 atmosphere. During this process, some low molecular weight substances that polycarbosilane (PCS) pyrolyzed can be deposited on graphite, and they can convert into SiC in high temperature. The results of XRD showed that amorphous SiC coatings were formed on graphite when the pyrolysis temperature was 1000°C, andβ-SiC phase formed in the coatings when the temperature up to 1250°C. Effects of the coatings on the microstructure and properties were investigated. It was shown that the uniform dense SiC coatings could be obtained by carefully controlling the pyrolysis temperature and ramping rate when the number molecular weight of PCS was in the range of 1,000~1,500.

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Biochar-driven reduction of As(V) and Cr(VI): Effects of pyrolysis temperature and low-molecular-weight organic acids

Ecotoxicology and Environmental Safety ◽

10.1016/j.ecoenv.2020.110873 ◽

2020 ◽

Vol 201 ◽

pp. 110873 ◽

Cited By ~ 6

Author(s):

Junhao Qin ◽

Qiwen Li ◽

Yanqing Liu ◽

Anyi Niu ◽

Chuxia Lin

Keyword(s):

Molecular Weight ◽

Organic Acids ◽

Pyrolysis Temperature ◽

Low Molecular Weight

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Low-temperature chemical vapour curing using iodine for fabrication of continuous silicon carbide fibres from low-molecular-weight polycarbosilane

Journal of Materials Chemistry A ◽

10.1039/c3ta13727a ◽

2014 ◽

Vol 2 (8) ◽

pp. 2781 ◽

Cited By ~ 19

Author(s):

Junsung Hong ◽

Kwang-Yeon Cho ◽

Dong-Geun Shin ◽

Jeong-Il Kim ◽

Sung-Tag Oh ◽

...

Keyword(s):

Molecular Weight ◽

Silicon Carbide ◽

Low Temperature ◽

Chemical Vapour ◽

Low Molecular Weight

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Irradiation performance of pyrolytic silicon carbide coatings on fissile fuel particles

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100112130 ◽

1984 ◽

Vol 42 ◽

pp. 418-419

Author(s):

R. J. Lauf

Keyword(s):

Silicon Carbide ◽

Fission Product ◽

Fission Products ◽

Carbide Coatings ◽

Fuel Particles ◽

Irradiation Performance ◽

Sic Coatings ◽

Irradiation Behavior ◽

Kinetics Of

Fuel particles for the High Temperature Gas-Cooled Reactor (HTGR) contain a layer of pyrolytic silicon carbide to act as a miniature pressure vessel and primary fission product barrier. Optimization of the SiC coating with respect to fuel performance involves four areas of study: (a) characterization of as-deposited SiC coatings; (b) thermodynamics and kinetics of chemical reactions between SiC and fission products; (c) irradiation behavior of SiC in the absence of fission products; and (d) the combined effects of irradiation and fission product interactions. This paper reports the behavior of SiC deposited on fissile fuel particles and irradiated to fast neutron fluences typical of HTGR fuel at end-of-life.

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Encapsulation of Low-Molecular-Weight Drugs into Polymer Multilayer Capsules Templated on Vaterite CaCO3 Crystals

Micromachines ◽

10.3390/mi11080717 ◽

2020 ◽

Vol 11 (8) ◽

pp. 717 ◽

Cited By ~ 1

Author(s):

Jack Campbell ◽

Georgia Kastania ◽

Dmitry Volodkin

Keyword(s):

Drug Delivery ◽

Molecular Weight ◽

Drug Loading ◽

Drug Carriers ◽

Deposition Process ◽

Vital Role ◽

Low Molecular Weight ◽

Layer By Layer ◽

Polymer Deposition ◽

Smart Drug

Polyelectrolyte multilayer capsules (PEMCs) templated onto biocompatible and easily degradable vaterite CaCO3 crystals via the layer-by-layer (LbL) polymer deposition process have served as multifunctional and tailor-made vehicles for advanced drug delivery. Since the last two decades, the PEMCs were utilized for effective encapsulation and controlled release of bioactive macromolecules (proteins, nucleic acids, etc.). However, their capacity to host low-molecular-weight (LMW) drugs (<1–2 kDa) has been demonstrated rather recently due to a limited retention ability of multilayers to small molecules. The safe and controlled delivery of LMW drugs plays a vital role for the treatment of cancers and other diseases, and, due to their tunable and inherent properties, PEMCs have shown to be good candidates for smart drug delivery. Herein, we summarize recent progress on the encapsulation of LMW drugs into PEMCs templated onto vaterite CaCO3 crystals. The drug loading and release mechanisms, advantages and limitations of the PEMCs as LMW drug carriers, as well as bio-applications of drug-laden capsules are discussed based upon the recent literature findings.

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Bulk and molecular composition variations of gold-tube pyrolysates from severely biodegraded Athabasca bitumen

Petroleum Science ◽

10.1007/s12182-020-00484-4 ◽

2020 ◽

Vol 17 (6) ◽

pp. 1527-1539

Author(s):

Zhong-Xuan Li ◽

Hai-Ping Huang

Keyword(s):

Molecular Weight ◽

Aromatic Hydrocarbons ◽

Environmental Samples ◽

Pyrolysis Temperature ◽

Polar Compounds ◽

Low Molecular Weight ◽

Hydrocarbon Generation ◽

Oil Sand ◽

Pyrogenic Source ◽

Hydrocarbon Gas

AbstractGold-tube pyrolysis experiments were performed on two Athabasca oil sand bitumens at 300 °C to 525 °C with 2 °C/h rate and 25 °C step under 50 MPa. Pyrolysis temperature of 425 °C is critical for weight loss of bulk bitumen and hydrocarbon generation and destruction. Polar compounds are the main source of saturated and aromatic hydrocarbon, gas and coke fractions. Molecular compositions in pyrolyzates vary systematically with increasing pyrolysis temperatures. High molecular weight n-alkanes (C26+) are gradually destructed during pyrolysis due to thermal cracking. Moderate molecular weight n-alkanes (C21–C25) show the highest thermal stability in designed pyrolysis temperatures. The loss of low molecular weight n-alkanes (C20−) might be caused by volatilization during pyrolysis, which may alter commonly used molecular parameters such as ∑n-C20−/∑n-C21+, Pr/n-C17 and Ph/n-C18. Aromatic hydrocarbons were generated from 300 to 425 °C, then condensation and dealkylation have been initiated at 425 °C as evidenced by decreased summed alkylnaphthalenes to alkylphenanthrenes ratios and increased unsubstituted aromatics to substituted homologs ratios in higher temperatures. The occurrence of anthracene and benz[a]anthracene in pyrolysates indicates pyrogenic origin, while fluoranthene shows unexpected behaviors during pyrolysis. Ratios derived from them are not always reliable for pyrogenic source input diagnosis in environmental samples.

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Investigation of Low Molecular Weight Carbosilanes as Potential Single-Source Precursors to Silicon Carbide

MRS Proceedings ◽

10.1557/proc-495-139 ◽

1997 ◽

Vol 495 ◽

Cited By ~ 1

Author(s):

M. A. Lienhard ◽

L. V. Interrante ◽

D. J. Larkin

Keyword(s):

Molecular Weight ◽

Growth Rate ◽

Silicon Carbide ◽

Low Molecular Weight ◽

Single Source ◽

Single Source Precursors ◽

By Products ◽

Sic Films

ABSTRACTSeveral volatile, low molecular weight, linear and cyclic carbosilanes containing a 1:1 Si:C ratio were studied as single-source CVD precursors to SiC. A comparison of methylsilane, 1,3-disilacyclobutane, 1,3-disila-n-butane, and 1,3,5-trisilacyclohexane in terms of both their pyrolysis chemistry (decomposition onset temperatures and gaseous by-products) and resulting film characterization (growth rate, stoichiometry, crystallinity and morphology) is presented. Polycrystalline β-SiC films were deposited by LPCVD on Si (100) substrates at temperatures ranging from 800°C to 1100°C by using each of these single-source precursors.

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Irradiation behavior of pyrolytic silicon carbide

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100074288 ◽

1983 ◽

Vol 41 ◽

pp. 72-73

Author(s):

R. J. Lauf

Keyword(s):

Silicon Carbide ◽

Fission Products ◽

Thermodynamics And Kinetics ◽

Neutron Fluences ◽

Fuel Particles ◽

Sic Coatings ◽

Irradiation Behavior ◽

Kinetics Of ◽

Htgr Fuel

Fuel particles for the High-Temperature Gas-Cooled Reactor (HTGR) contain a layer of pyrolytic silicon carbide to act as a miniature pressure vessel and primary fission product barrier. Optimization of the SiC with respect to fuel performance involves four areas of study: (a) characterization of as-deposited SiC coatings; (b) thermodynamics and kinetics of chemical reactions between SiC and fission products; (c) irradiation behavior of SiC in the absence of fission products; and (d) combined effects of irradiation and fission products. This paper reports the behavior of SiC deposited on inert microspheres and irradiated to fast neutron fluences typical of HTGR fuel at end-of-life.

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A high-performance oil-free backing pump for electron microscopes

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100107691 ◽

1978 ◽

Vol 36 (1) ◽

pp. 110-111

Author(s):

G.K.W. Balkau ◽

E. Bez ◽

J.L. Farrant

Keyword(s):

Molecular Weight ◽

Electron Microscope ◽

Hot Spots ◽

High Performance ◽

Carbonaceous Material ◽

Contamination Rate ◽

Low Molecular Weight ◽

Principal Source ◽

Rotary Pumps ◽

Electron Microscopes

The earliest account of the contamination of electron microscope specimens by the deposition of carbonaceous material during electron irradiation was published in 1947 by Watson who was then working in Canada. It was soon established that this carbonaceous material is formed from organic vapours, and it is now recognized that the principal source is the oil-sealed rotary pumps which provide the backing vacuum. It has been shown that the organic vapours consist of low molecular weight fragments of oil molecules which have been degraded at hot spots produced by friction between the vanes and the surfaces on which they slide. As satisfactory oil-free pumps are unavailable, it is standard electron microscope practice to reduce the partial pressure of organic vapours in the microscope in the vicinity of the specimen by using liquid-nitrogen cooled anti-contamination devices. Traps of this type are sufficient to reduce the contamination rate to about 0.1 Å per min, which is tolerable for many investigations.

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