scholarly journals Dependence of the fire retardant and fire extinguishing efficiency of compositions based on phosphates of bivalent and trivalent ammonium metals on their physicochemical properties

2020 ◽  
Vol 4 (4) ◽  
pp. 367-377
Author(s):  
Валентина Владимировна Богданова ◽  
Ольга Игоревна Кобец ◽  
Александр Васильевич Врублевский
Keyword(s):  
Condensed Phase ◽  
Fire Retardant ◽  
Burning Surface ◽  
Chemical Compositions ◽  
Main Task ◽  
Scanning Calorimetry ◽  
Synthesis Conditions ◽  
Forest Fuels ◽  
Fire Extinguishing ◽  
Trivalent Metals

Purpose. The object of research were fire-retardant and fire-extinguishing agents based on ammonium phosphates of bivalent and trivalent metals used for the treatment of forest combustible materials (FCM), including wood and peat. The subject of the research was to determine the fire-retardant and fire-extinguishing effectiveness of these agents, depending on their physical and chemical properties determined by the conditions of synthesis. The aim was to establish common traits or difference in the mechanism of inhibition of combustion of FCM by metallophosphate systems of various chemical compositions, as well as to reveal the role of the processes occurring in the condensed phase under the influence of their thermal decomposition products. The main task was to study the physicochemical, thermal properties of fire-retardant and fire-extinguishing agents, as well as fire-protected samples of peat and other FCM in the temperature range on the burning surface of natural materials (200–500 °C). Methods. X-ray phase analysis, differential scanning calorimetry, chemical analysis. Findings. The factors determining the fire-retardant and fire-extinguishing efficiency of synthetic agents based on phosphates of bivalent and trivalent ammonium metals with controlled properties depending on the synthesis conditions with respect to FCM, wood and peat have been determined. A process has been established that has a dominant effect on stopping their combustion – inhibition of radical reactions in the gas phase by volatile nitrogen-containing products. At the same time, it was shown that when developing new fire-retardant and fire-extinguishing agents, it is necessary to take into account their properties such as the ability to form thermal insulating structures in the condensed phase. Application field of research. The results obtained in this work can be used to create new fire-retardant and fire-extinguishing synthetic compositions based on ammonium phosphates of bivalent and trivalent metals for the treatment of forest fuels.

Research and Preparation of Silver Free Amorphous Active Brazing Alloy

2015 ◽  
Vol 817 ◽  
pp. 96-103
Author(s):  
Wei Ping Fang ◽  
Yao Yong Yi ◽  
Feng Mei Liu ◽  
Zheng Lin Liu ◽  
Zhen Hua Deng
Keyword(s):  
Bending Strength ◽  
Mechanical Test ◽  
Amorphous Material ◽  
Chemical Compositions ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Xrd Pattern ◽  
Spreading Area ◽  
Wetting Ability ◽  
Wetting Contact Angle

A silver free amorphous Cu-35Ti-12Ni active brazing alloy was successfully prepared in this work. The crystallinity, microstructure, and chemical composition were characterized with X-ray diffraction (XRD), scanning electron microscope (SEM), and energy-dispersive spectrometry (EDS), respectively. A typical characteristic peak of amorphous material was observed in the XRD pattern. The microstructures and chemical compositions of the silver free amorphous alloy were uniform. Differential scanning calorimetry (DSC) result shows that the amorphous silver free brazing alloy has higher melting temperature than commercial silver brazing alloy (Ag-26.5Cu-1.5Ti). Wetting contact angle and spreading area on Si3N4 ceramic substrate were used to evaluate the wetting ability of brazing alloy. The wetting angle was smaller than 5o, and the spreading area was 141.6 mm2 at 1100°C. The bending strength of silver free brazing alloy/Si3N4 was also carried out. The mechanical test shows that the amorphous Cu-35Ti-12Ni/Si3N4 has higher joint strength (304.7MPa) than the crystal Cu-35Ti-12Ni/Si3N4 (294.7MPa) at room temperature.

scholarly journals Valorization of Industrial Lignin as Biobased Carbon Source in Fire Retardant System for Polyamide 11 Blends

Polymers ◽  
2019 ◽  
Vol 11 (1) ◽  
pp. 180 ◽  
Author(s):  
Neeraj Mandlekar ◽  
Aurélie Cayla ◽  
François Rault ◽  
Stéphane Giraud ◽  
Fabien Salaün ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Condensed Phase ◽  
Flame Retardants ◽  
Fire Behavior ◽  
Fire Retardant ◽  
Ternary Blends ◽  
Cone Calorimetry ◽  
Polyamide 11 ◽  
Twin Screw ◽  
Flame Retarded

In this study, two different types of industrial lignin (i.e., lignosulphonate lignin (LL) and kraft lignin (DL)) were exploited as charring agents with phosphorus-based flame retardants for polyamide 11 (PA11). The effect of lignins on the thermal stability and fire behavior of PA11 combined with phosphinate additives (namely, aluminum phosphinate (AlP) and zinc phosphinate (ZnP)) has been studied by thermogravimetric analysis (TGA), UL 94 vertical flame spread, and cone calorimetry tests. Various blends of flame retarded PA11 were prepared by melt process using a twin-screw extruder. Thermogravimetric analyses showed that the LL containing ternary blends are able to provide higher thermal stability, as well as a developed char residue. The decomposition of the phosphinates led to the formation of phosphate compounds in the condensed phase, which promotes the formation of a stable char. Flammability tests showed that LL/ZnP ternary blends were able to achieve self-extinction and V-1 classification; the other formulations showed a strong melt dripping and higher burning. In addition to this, cone calorimetry results showed that the most enhanced behavior was found when 10 wt % of LL and AlP were combined, which strongly reduced PHRR (−74%) and THR (−22%), due to the interaction between LL and AlP, which not only promotes char formation but also confers the stability to char in the condensed phase.

scholarly journals Структура и свойства пленок SiO-=SUB=-x-=/SUB=-, полученных химическим травлением лент аморфного сплава

2018 ◽  
Vol 60 (4) ◽  
pp. 701
Author(s):  
В.А. Федоров ◽  
А.Д. Березнер ◽  
А.И. Бескровный ◽  
Т.Н. Фурсова ◽  
А.В. Павликов ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Chemical Etching ◽  
Amorphous Ribbon ◽  
Amorphous Structure ◽  
Chemical Compositions ◽  
Scanning Calorimetry ◽  
Transparent Films ◽  
Before And After ◽  
Iron Based ◽  
Raman And Ir Spectroscopy

AbstractThe structure and the physical properties of amorphous SiO_ x films prepared by chemical etching of an iron-based amorphous ribbon alloy have been studied. The neutron diffraction and also the atomicforce and electron microscopy show that the prepared visually transparent films have amorphous structure, exhibit dielectric properties, and their morphology is similar to that of opals. The samples have been studied by differential scanning calorimetry, Raman and IR spectroscopy before and after their heat treatment. It is found that annealing of the films in air at a temperature of 1273 K leads to a change in their chemical compositions: an amorphous SiO_2 compound with inclusions of SiO_2 nanocrystals (crystobalite) forms.

scholarly journals Liquid-Crystal and Fire-Retardant Properties of New Hexasubstituted Cyclotriphosphazene Compounds with Two Schiff Base Linking Units

Molecules ◽  
2020 ◽  
Vol 25 (9) ◽  
pp. 2122 ◽  
Author(s):  
Zuhair Jamain ◽  
Melati Khairuddean ◽  
Tay Guan-Seng
Keyword(s):  
Schiff Base ◽  
Liquid Crystal ◽  
Polyester Resin ◽  
Fire Retardant ◽  
Terminal Group ◽  
Scanning Calorimetry ◽  
Limiting Oxygen Index ◽  
Crystal Properties ◽  
Fire Retardant Properties ◽  
Good Agreement

A series of new hexasubstituted cyclotriphosphazene compounds (4a–j) consisting of two Schiff base linking units and different terminal substituents was successfully synthesized and characterized. The structures of these compounds were confirmed using Fourier Transform Infra-Red (FTIR), Nuclear Magnetic Resonance (NMR), and CHN elemental analysis. Polarized optical microscopy (POM) was used to determine their liquid-crystal behavior, which was then further confirmed using differential scanning calorimetry (DSC). Compounds 4a–i with heptyl, nonyl, decyl, dodecyl, tetradecyl, hydroxy, 4-carboxyphenyl, chloro, and nitro terminal ends, respectively, showed the liquid-crystal properties, whereas compound 4j with the amino group was found to be non-mesogenic. The attachment of an electron-donating group in 4j eventually give a non-mesogenic product. The study of the fire-retardant properties of these compounds was done using the limiting oxygen index (LOI). In this study, polyester resin (PE) was used as a matrix for moulding, and the LOI value of pure PE was 22.53%. The LOI value increased to 24.71% when PE was incorporated with 1 wt.% of hexachlorocyclotriphosphazene (HCCP), thus indicating that HCCP has a good fire-retardant properties. The result showed that all the compounds have good agreement in their LOI values. Compound 4i with a nitro terminal group gave the highest LOI value of 28.37%.

scholarly journals Fabrication and Characterization of the Newly Developed Superalloys Based on Inconel 740

Materials ◽  
2020 ◽  
Vol 13 (10) ◽  
pp. 2362 ◽  
Author(s):  
Małgorzata Grudzień-Rakoczy ◽  
Łukasz Rakoczy ◽  
Rafał Cygan ◽  
František Kromka ◽  
Zenon Pirowski ◽  
...  
Keyword(s):  
Solidus Temperature ◽  
Chemical Compositions ◽  
Scanning Calorimetry ◽  
Dendritic Microstructure ◽  
X Ray ◽  
Thermal Expansion Coefficients ◽  
Expansion Coefficients ◽  
Fabrication And Characterization ◽  
The Difference

The chemical composition of standard Inconel 740 superalloy was modified by changes in the Al/Ti ratio (0.7, 1.5, 3.4) and addition of Ta (2.0, 3.0, 4.0%). Remelted Inconel 740 (A0) and nine variants with various chemical compositions were fabricated by lost-wax casting. The microstructure, microsegregation, phase transformation temperatures, thermal expansion coefficients and hardness of the superalloys were investigated by scanning electron microscopy, energy dispersive X-ray spectroscopy, differential scanning calorimetry, dilatometry and Vickers measurements. Typical dendritic microstructure was revealed with microsegregation of the alloying elements. Segregation coefficient ki for Ti, Nb and Ta did not exceed unity, and so precipitates enriched mainly in these elements were found in interdendritic spaces. The Nb-rich blocky precipitates, MC carbides, MN nitrides, oxides, and fine γ’ was in all modified castings. Presence of other microstructural features, such as Ti-rich needles, eutectic γ-γ’ islands, small Al-rich and Cr-rich precipitates depended on the casting composition. The lowest solidus and liquidus temperatures were observed in superalloys with a high Al/Ti ratio. Consequently, in A7–A9 variants, the solidification range did not exceed 100 °C. In the A0 variant the difference between liquidus and solidus temperature was 138 °C. Hardness of all modified superalloys was at least 50% higher than for the remelted Inconel 740 (209 HV10).

Intermetallic Alloys Ni3Si and Ni3(Si,Ti): Microstructures and Properties

2008 ◽  
Vol 368-372 ◽  
pp. 1143-1145 ◽  
Author(s):  
Ding Fan ◽  
Yao Ning Sun ◽  
Min Zheng ◽  
Jian Bin Zhang ◽  
Yu Feng Zheng
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Differential Scanning Calorimetry ◽  
Continuous Wave ◽  
Chemical Compositions ◽  
Intermetallic Alloys ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Scanning Electron

Laser cladding experiment was carried out with a 5 kW continuous wave CO2 laser by preplacing Ni75Si25 and Ni78Si13Ti9 powders onto Ni-based superalloy substrate. The microstructure of the specimens was monitored by using optical and scanning electron microscopy. The chemical compositions of the alloys and their phases were obtained using X-ray diffraction and energy dispersive x-ray spectroscopy. The phase transformation temperatures were determined by non-isothermal differential scanning calorimetry tests. The microhardness of the laser cladded sample was measured.

Structure and properties of poly(lactic acid)/poly(lactic acid)-α-cyclodextrin inclusion compound composites

2017 ◽  
Vol 37 (9) ◽  
pp. 897-909
Author(s):  
Li Zhang ◽  
Weijun Zhen ◽  
Yufang Zhou
Keyword(s):  
Lactic Acid ◽  
Average Molecular Weight ◽  
Gel Permeation Chromatography ◽  
Mechanical Analysis ◽  
Poly Lactic Acid ◽  
Polymerization Temperature ◽  
Scanning Calorimetry ◽  
Synthesis Conditions ◽  
Cyclodextrin Inclusion ◽  
Comprehensive Performance

Abstract Poly(lactic acid) (PLA) was synthesized using a green catalyst, nano-zinc oxide (ZnO). The optimum synthesis conditions of PLA were as follows: a stoichiometric amount of 0.5 wt% of nano-ZnO, polymerization time of 14 h, and polymerization temperature of 170°C. Gel permeation chromatography results showed that the weight-average molecular weight (Mw) of PLA was 13,072 g/mol with a polydispersity index (PDI) of 1.7. Furthermore, PLA-α-cyclodextrin inclusion compounds (PLA-CD-ICs) were prepared by ultrasonic co-precipitation techniques. X-ray diffraction analysis and Fourier transform infrared spectroscopy demonstrated the change in lattice of α-CD from a cage configuration to a tunnel structure and the existence of some physical interactions between α-CD and PLA in the PLA-CD-ICs. To enhance the crystallization properties of PLA, PLA/PLA-CD-IC composites were blended with different contents of PLA-CD-ICs as nucleating agents. The crystallization behavior and comprehensive performance were investigated by differential scanning calorimetry, polarized optical microscopy, tensile testing, dynamic mechanical analysis, and scanning electron microscopy. Compared to PLA, the crystallinities of PLA/PLA-CD-IC composites were increased by 24.0%, 26.3%, 27.3%, and 31.8%. The results of all the analyses proved that PLA-CD-ICs were useful as green organic nucleators and improved the comprehensive performance of PLA materials.

scholarly journals New experimental diagnostics in combustion of forest fuels: Microscale appreciation for a Macroscale approach

2018 ◽  
Author(s):  
Dominique Cancellieri ◽  
Valérie Leroy-Cancellieri ◽  
Xavier Silvani ◽  
Frédéric Morandini
Keyword(s):  
Thermal Degradation ◽  
Large Scale ◽  
Field Scale ◽  
Scanning Calorimetry ◽  
Natural Fire ◽  
Fire Propagation ◽  
New Device ◽  
Forest Fuels ◽  
Kinetics Of ◽  
Experimental Diagnostics

Abstract. In modelling the wildfire behaviour, a good knowledge of the mechanisms and the kinetic parameters controlling the thermal decomposition of forest fuel is of great importance. Lab-scale experimental diagnostics as Thermogravimetric Analysis (TGA), Differential Scanning Calorimetry (DSC), Cone Calorimeter (CC) or Fire Propagation Apparatus (FPA) led to valuable results for modelling the thermal degradation of vegetal fuels and allowed several upgrades of pyrolysis models. But, these works remain beyond large-scale conditions of a wildland or forest fire. In an effort to elaborate the kinetic models under realistic natural fire conditions, a mass-loss device specifically designed for the field scale has been developed. The paper presents primary results gained using this new device, during large-scale experiments of controlled fires. The experimental data collected at the field scale lead to a new insight about thermal degradation processes of natural fuel, when compared to the kinetic laws established in TGA. These new results, provide a global description of the kinetics of degradation of Mediterranean forest fuels.

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