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    Wyświetlanie 1-13 z 13
    Tytuł:
    Thermal Decomposition Kinetics of Hexanitrohexaazaisowurtzitane/Ammonium Perchlorate
    Autorzy:
    Zhu, Y.-L.
    Wang, K.-K.
    Shan, M.-X.
    Zheng, X.-D.
    Jiao, Q.-J.
    Wang, J.-S.
    Powiązania:
    https://bibliotekanauki.pl/articles/358067.pdf
    Data publikacji:
    2016
    Wydawca:
    Sieć Badawcza Łukasiewicz - Instytut Przemysłu Organicznego
    Tematy:
    hexanitrohexaazaisowurtzitane
    ammonium perchlorate
    thermal analysis
    thermal decomposition kinetics
    Opis:
    The thermal decomposition kinetics of hexanitrohexaazaisowurtzitane/ ammonium perchlorate (HNIW/AP) have been investigated by thermogravimetrydifferential scanning calorimetry-mass spectrometry (TG-DSC-MS) simultaneous analysis. TG showed that there were three weight loss processes for the thermal decomposition of the HNIW/AP mixture. The first was ascribed mainly to the thermal decomposition of HNIW, while the second and third were assigned to that of AP. The presence of AP has little effect on the thermal decomposition process of the HNIW component. The apparent activation energy of the thermal decomposition of the HNIW component, calculated by the Kissinger method, was little changed compared to that of neat HNIW. The addition of HNIW to AP caused the onset and end temperatures of the thermal decomposition to be decreased and the decomposition process to be shortened. The high-temperature and lowtemperature decomposition processes of AP became blurred in the presence of HNIW, and this was supported by the MS results.
    Źródło:
    Central European Journal of Energetic Materials; 2016, 13, 1; 149-159
    1733-7178
    Pojawia się w:
    Central European Journal of Energetic Materials
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Synthesis and Characterization of Metal Derivatives of 1,1,2,2-Tetranitraminoethane (TNAE)
    Autorzy:
    Zhu, C.
    Meng, Z.
    Xu, Z.
    Liu, W.
    Liu, Y.
    Shi, X.
    Xie, T.
    Powiązania:
    https://bibliotekanauki.pl/articles/358571.pdf
    Data publikacji:
    2018
    Wydawca:
    Sieć Badawcza Łukasiewicz - Instytut Przemysłu Organicznego
    Tematy:
    Ionic compound
    1,1,2,2-tetranitraminoethane
    thermal property
    safety performance
    thermal decomposition kinetics
    Opis:
    The introduction of anions and cations into energetic materials can significantly improve their physicochemical and energetic properties. The K, Zn, Ba, Cu and Pb salts of 1,1,2,2-tetranitraminoethane (TNAE) were synthesized using TNAE as the starting material, and were characterized by IR spectroscopy, NMR spectroscopy and elemental analysis. All of the energetic salts exhibited relatively high thermal stabilities (decomposition temperatures ranging from 195.1 °C to 279.3 °C) and high densities (ranging from 2.1 g·cm–3 to 3.7 g·cm–3). It was demonstrated that the introduction of metal ions conveys better thermal stability than covalent TNAE itself. More importantly, the Zn, Ba and Cu salts exhibited good thermal stability, high density, low sensitivity, and therefore have the potential to be a new class of insensitive, highly energetic explosives for practical applications.
    Źródło:
    Central European Journal of Energetic Materials; 2018, 15, 3; 435-444
    1733-7178
    Pojawia się w:
    Central European Journal of Energetic Materials
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Effect of Nanomaterials on Thermal Stability of 1,3,6,8-Tetranitro Carbazole
    Autorzy:
    Pourmortazavi, S. M.
    Rahimi-Nasrabadi, M.
    Rai, H.
    Jabbarzadeh, Y.
    Javidan, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/358744.pdf
    Data publikacji:
    2017
    Wydawca:
    Sieć Badawcza Łukasiewicz - Instytut Przemysłu Organicznego
    Tematy:
    thermal stability
    nanomaterial effect
    decomposition kinetics
    1,3,6,8-tetranitro carbazole
    energetic material
    Opis:
    1,3,6,8-tetranitro carbazole (TNC) as a secondary explosive is used in composite explosive formulations in order to reduce the sensitivity and increase the stability of the explosive composites. In this work, the thermal stabilities of pure TNC and its nanocomposites prepared via three different nanoparticles were studied by thermal analysis, i.e. differential scanning calorimetery (DSC) and thermogravimetry (TG) techniques. Thermal analysis data revealed that the thermal behavior of pure TNC is significantly different from the nanocomposites studied. Pure TNC decomposed completely during a single step in the temperature range 385-425 °C. However, the addition of nanoparticles to the TNC powder leads to higher thermal stability in comparison with the pure TNC. The decomposition kinetics of TNC and its nanocomposites were studied by non-isothermal DSC at several heating rates. Thermokinetic and thermodynamic parameters corresponding to the thermal decomposition of pure TNC and nanocomposites were computed and compared. The results showed that the addition of nanoparticles to the TNC powder has a considerable effect on the thermal stability of the explosive.
    Źródło:
    Central European Journal of Energetic Materials; 2017, 14, 1; 201-216
    1733-7178
    Pojawia się w:
    Central European Journal of Energetic Materials
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Studies of the Ammonia Decomposition over a Mixture Of α - Fe(N) And γ - Fe4n
    Autorzy:
    Kiełbasa, K.
    Arabczyk, W.
    Powiązania:
    https://bibliotekanauki.pl/articles/779244.pdf
    Data publikacji:
    2013
    Wydawca:
    Zachodniopomorski Uniwersytet Technologiczny w Szczecinie. Wydawnictwo Uczelniane ZUT w Szczecinie
    Tematy:
    catalytic ammonia decomposition
    kinetics
    iron catalyst
    Opis:
    An industrial pre-reduced iron catalyst for ammonia synthesis was nitrided in a differential reactor equipped with the systems that made it possible to conduct both the thermogravimetric measurements and hydrogen concentration analyser in the reacting gas mixture. The nitriding process, particularly the catalytic ammonia decomposition reaction, was investigated under an atmosphere of ammonia-hydrogen mixtures, under the atmospheric pressure, at 475oC. The nitriding potentials were changed gradually in the range from 19.10-3 to 73.10-3 Pa-0.5 in the reactor for an intermediate area where two phases exist simultanously: Fe(N) and γ’-Fe4. In the area wherein P > 73.10-3 Pa-0.5, approximately stoichiometric composition of γ’ - Fe4N phase exists and saturating of that phase by nitrogen started. The rate of the catalytic ammonia decomposition was calculated on the basis of grain volume distribution as a function of conversion degree for that catalyst. It was found that over γ’ - Fe4N phase in the stationary states the rate of catalytic ammonia decomposition depends linearly on the logarithm of the nitriding potential. The rate was decreasing along with increase in the nitriding potential. For the intermediate area, the rate of ammonia decomposition is a sum of the rates of reactions which occur on the surfaces of both Fe(N) and γ’ - Fe4N.
    Źródło:
    Polish Journal of Chemical Technology; 2013, 15, 1; 97-101
    1509-8117
    1899-4741
    Pojawia się w:
    Polish Journal of Chemical Technology
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Investigation of the cook-off processes of HMX-based mixed explosives
    Autorzy:
    Chen, L.
    Ma, X.
    Lu, F.
    Wu, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/358000.pdf
    Data publikacji:
    2014
    Wydawca:
    Sieć Badawcza Łukasiewicz - Instytut Przemysłu Organicznego
    Tematy:
    explosives
    chemical kinetics
    thermal decomposition
    cook-off
    numerical simulation
    Opis:
    In order to investigate the characteristics of the thermal reaction for two kinds of mixed explosives, PBXC-10 (HMX/TATB/Binder, 38/57/5) and JO-8 (HMX/Binder, 95/5), multi-point measured temperature cook-off tests were carried out at different heating rates. The thermal transfer and finite chemical reactions that include the β→δ transition of HMX, and the endothermic and exothermic cook-off processes were analyzed. A 3D model of the explosive cook-off test was developed to simulate the thermal and chemical behaviour in a thermal ignition. The decomposition mechanisms for HMX and TATB are described by the multistep, chemical kinetic model. The thermal properties, decomposition pathways, and chemical kinetic reaction rate constants for each component are used to develop the reaction courses at various weight percentages. The thermal decomposition reaction of a multi-component, mixed explosive can be predicted as long as the chemical kinetics model of each single-base explosive and binder are known. The phase transition of HMX has an influence on the temperature of the explosive, especially for an explosive with a high HMX content. For mixed explosives containing HMX and TATB, most of the heat release is produced by the decomposition of HMX before ignition, but TATB can delay the ignition time and decrease the reaction violence in the cook-off process.
    Źródło:
    Central European Journal of Energetic Materials; 2014, 11, 2; 199-218
    1733-7178
    Pojawia się w:
    Central European Journal of Energetic Materials
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Thermal Decomposition and Kinetics Studies of AN, KDN and Their Mixtures with and without Catalysts
    Autorzy:
    Kumar, P.
    Joshi, P. C.
    Kumar, R.
    Powiązania:
    https://bibliotekanauki.pl/articles/358729.pdf
    Data publikacji:
    2017
    Wydawca:
    Sieć Badawcza Łukasiewicz - Instytut Przemysłu Organicznego
    Tematy:
    green oxidizers
    phase stabilization
    thermal decomposition
    thermo-kinetics
    catalysts
    Opis:
    Potassium dinitramide (KDN) was incorporated in ammonium nitrate (AN) crystals in AN/KDN ratio of 90/10, 75/25 and 50/50 by a co-crystallization method. These mixtures were subjected to thermal decompositional studies (DSC-TG) using a Simultaneous Thermal Analyzer (STA). The catalysts used for the present studies were: i) cupric(II) oxide (CuO) and, ii) copper-cobalt based metal oxide (Cu-Co*). For all catalytic samples, 2% by weight percent of catalyst was added to the total weight of the samples. Thermal decomposition studies were carried out for all the oxidizer samples prepared. Thermal decompositional studies were carried out at three different heating rates, i.e. 3 K/min, 5 K/min and 10 K/min, and the kinetic parameters were computed using the model free Flynn-Wall-Ozawa equation. It has been observed that 50% KDN addition resulted in complete suppression of endothermicity indicating total supression of the phase changes of AN in this temperature range. Further, it was noticed that CuO acts as a better phase stabilizer for AN as compared to Cu-Co*. However, Cu-Co* considerably increased the net exothermic decompositional heat release (J/g) of AN.
    Źródło:
    Central European Journal of Energetic Materials; 2017, 14, 1; 184-200
    1733-7178
    Pojawia się w:
    Central European Journal of Energetic Materials
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Mechanism and Kinetics Studies on Non-Isothermal Decomposition of Ludwigite in Inert Atmosphere
    Autorzy:
    Fu, X.
    Chu, M.
    Gao, L.
    Liu, Z.
    Powiązania:
    https://bibliotekanauki.pl/articles/352128.pdf
    Data publikacji:
    2018
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    ludwigite
    non-isothermal decomposition
    kinetics
    activation energy
    model function
    Opis:
    Ludwigite is the main available boron-bearing resource in China. In order to enrich the theory system and optimize its utilization processes, this paper study the mechanism and kinetics on non-isothermal decomposition of ludwigite in inert atmosphere by means of thermal analysis. Results show that, the decomposition of serpentine and szajbelyite is the main cause of mass loss in the process. At the end of decomposition, hortonolite and ludwigite are the two main phases in the sample. The average E value of structural water decomposition is 277.97 kJ/mol based on FWO method (277.17 kJ/mol based on KAS method). The results is proved to be accurate and reliable. The mechanism model function of structural water decomposition is confirmed by Satava method and Popescu method. The form of the most probable model function is G(α) = (1 – α)–1– 1 (integral form) and f (α) = (1 – α)2 (differential form), and its mechanism is chemical reaction. This is verified by the criterion based on activation energy of model-free kinetics analysis.
    Źródło:
    Archives of Metallurgy and Materials; 2018, 63, 3; 1217-1224
    1733-3490
    Pojawia się w:
    Archives of Metallurgy and Materials
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    The kinetics of 1,1-dichloroethene (CCl2=CH2) and trichloroethene (HClC=CCl2) decomposition in dry and humid air under the influence of electron beam
    Autorzy:
    Nichipor, H.
    Dashouk, E.
    Yacko, S.
    Chmielewski, A.
    Zimek, Z.
    Sun, Y.
    Vitale, S.
    Powiązania:
    https://bibliotekanauki.pl/articles/148600.pdf
    Data publikacji:
    2003
    Wydawca:
    Instytut Chemii i Techniki Jądrowej
    Tematy:
    1,1-dichloroethene
    trichloroethene
    electron beam decomposition
    theoretical model
    kinetics calculation
    Opis:
    New experimental data related to the removal of C2H2Cl2 and C2HCl3 in dry and humid (300 ppm of H2O) air at atmospheric pressure and a temperature of 25°C under the influence of electron beam in the dose range 1 < D < 100 kGy are published. Taking into account these experimental data, theoretical models of the decomposition of both compounds and computer simulations were performed by the present authors to find the kinetics of such processes. The influence of active atoms Cl, O and OH radicals on the VOC degradation process has been established. The theoretical model of C2H2Cl2 degradation under the influence of electron beam in dry and humid air describes the C2H2Cl2 decay and formation of the main products like Cl2, COCl2, CO, CO2, HCl, HCOCl and C2H2Cl2O. The results of calculation of the kinetics of C2H2Cl2 decomposition were compared with data obtained experimentally for the C2H2Cl2 concentration range 321-2213 ppm. It was established that the relation between the rate constants of intermediate product decomposition: C2H2Cl3O Ţ C2H2Cl2O + Cl; (k1) C2H2Cl3O Ţ COCl2 + CH2C2; (k2) should be k1/k2 = 40. The theoretical model of C2HCl3 degradation under the influence of electron beam in dry and humid air describes the C2HCl3 decay and formation of the main products like Cl2, COCl2, CO, CO2, HCl, HCOCl and C2HCl3O. A detailed comparison of experimental and theoretical data for the C2HCl3 concentration 108-3206 ppm shows that the relation between the rate constants of intermediate product decomposition: C2HCl4O Ţ C2HCl3O + Cl; (k3) C2HCl4O Ţ COCl2 + CHCl2; (k4) should be k3/k4 =10. It was also found that O2+ ions have been formed in a gas mixture as a result of charge transfer process from N2+ ions, partly in excited form, which may lead to charge transfer to C2HCl3 and degradation of those particles. According to performed calculation, it can be stated that in humid air (300 ppm of H2O) VOC degradation is occurring mainly due to a chain reaction stimulated by Cl atoms, but also OH radicals are playing an important role. In the described gas mixture, the OH radicals are formed in the following reactions: O2+) + H2O + M Ţ (O2+)H2O + M O2+ (H2O) + H2O Ţ O2 + (H3O+)OH (H3O+)OH + H2O Ţ H3O+ + OH + H2O VOC degradation process under the influence of electron beam is more effective in humid air than in dry air for the same initial VOC concentration level. This conclusion is also supported by experimental data. --------------------------------------------------------------------------------
    Źródło:
    Nukleonika; 2003, 48, 1; 45-50
    0029-5922
    1508-5791
    Pojawia się w:
    Nukleonika
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Investigations on Chemical, Thermal Decomposition Behavior, Kinetics, Reaction Mechanism and Thermodynamic Properties of Aged TATB
    Autorzy:
    Singh, A.
    Kaur, G.
    Sarkar, C.
    Mukherjee, N.
    Powiązania:
    https://bibliotekanauki.pl/articles/357970.pdf
    Data publikacji:
    2018
    Wydawca:
    Sieć Badawcza Łukasiewicz - Instytut Przemysłu Organicznego
    Tematy:
    1,3,5-triamino-2,4,6-trinitrobenzene
    thermal decomposition
    kinetics
    thermodynamics
    Opis:
    1,3,5-triamino-2,4,6-trinitrobenzene (TATB) is a kind of insensitive high explosive that can be used as an energetic material in nuclear weapon and space applications. In this work, we have studied the effect of aging on the properties of TATB from a 20 year old lot that had been in direct contact with casing and natural environment conditions. The kinetics was studied using the temperature at the maximum reaction rate (peak) and isoconversional methods from TGA and DTA data obtained at five heating rates under a nitrogen atmosphere. The properties investigated for thermal stability indicate that there is no change in the properties during prolonged exposure in natural environment conditions. The activation energy calculated by the Kissinger method was 179.9 kJ·mol−1 by DTG and the 176.9 kJ·mol−1 by DTA. The experimental results of kinetic analysis obtained by isoconversional methods are in good agreement and very close to each other. In the analysis of reaction mechanisms, the reaction models could be probably best described by a surface contraction mechanism using the Coats-Redfern and Criado methods. The thermodynamic parameters such as Gibbs free energy, enthalpy and entropy of activation were also investigated. The self-accelerating decomposition temperature (TSADT) and critical temperature for thermal explosion (Tb) were also calculated.
    Źródło:
    Central European Journal of Energetic Materials; 2018, 15, 2; 258-282
    1733-7178
    Pojawia się w:
    Central European Journal of Energetic Materials
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Non-isothermal Decomposition Kinetics of 1-Amino-1,2,3-triazolium Nitrate
    Autorzy:
    Du, X.-J.
    Zou, M.-S.
    Li, X.-D.
    Yang, R.-J.
    Powiązania:
    https://bibliotekanauki.pl/articles/358020.pdf
    Data publikacji:
    2014
    Wydawca:
    Sieć Badawcza Łukasiewicz - Instytut Przemysłu Organicznego
    Tematy:
    1-amino-1,2,3-triazolium nitrate
    thermal decomposition
    TG
    non-isothermal kinetics
    compensating effect
    Opis:
    The thermal decomposition kinetics of 1-amino-1,2,3-triazolium nitrate (ATZ-NO3) was investigated by non-isothermal TG-DTG at various heating rates (2, 5, 10, 15, and 20 °C∙min-1). The results showed that the thermal decomposition of ATZ-NO3 consists of two mass-loss stages. The first mass-loss stage corresponds to the loss of nitrate anion and the substituent group, while the second stage corresponds to the splitting of the triazole ring. The kinetic triplets of the two stages were described by a three-step method. Firstly, the Kissinger and Ozawa methods were used to calculate the apparent activation energies (E) and pre-exponential factors (A) of the two decomposition stages. Secondly, two calculation methods (the Šatava-Šesták and Achar methods) were used to obtain several probable decomposition mechanism functions. Thirdly, three assessment methods (the Šatava, double-extrapolation, and the Popescu methods) were used to confirm the most probable decomposition mechanism functions. The reaction models for both stages are random-into-nuclear and random-growth mechanisms, with n = 3/2 for the first stage and n = 1/3, m = 3 for the second stage. The kinetic equations for the two decomposition stages of ATZ-NO3 may be expressed as [wzór]. Mathematical expressions for the kinetic compensation effect were derived.
    Źródło:
    Central European Journal of Energetic Materials; 2014, 11, 1; 99-114
    1733-7178
    Pojawia się w:
    Central European Journal of Energetic Materials
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    The kinetics of the thermal decomposition of the willow wood (Salix viminalis L.) exposed to the torrefaction process
    Badania kinetyki procesu termicznego rozkładu drewna wierzby konopianki (Salix viminalis L.) poddanego obróbce hydrotermicznej
    Autorzy:
    Walkowiak, M.
    Bartkowiak, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/52561.pdf
    Data publikacji:
    2012
    Wydawca:
    Sieć Badawcza Łukasiewicz - Instytut Technologii Drewna
    Tematy:
    process kinetics
    thermal process
    thermal decomposition
    willow wood
    willow
    Salix viminalis
    torrefaction process
    thermal analysis
    pyrolysis
    Opis:
    The aim of the study was to analyze the kinetic parameters (activation energy Ea, pre-exponential coefficient A, rate constant k) of thermolysis in torrefied and raw willow wood (Salix viminalis L.), as well as to determine the effect of thermal modification conditions on the kinetics of this process. Samples of raw and torrefied willow wood in a steam atmosphere were analysed. The samples were subjected to thermogravimetric analysis under isothermal conditions. Analyses were conducted in an atmosphere of helium at 270–330°C. TG and DTG curves were recorded. The thermal characteristics of the samples were based on thermogravimetric analysis under dynamic conditions at a temperature of up to 600°C. On the basis of the data obtained from the TGA analyses, the kinetic parameters were calculated and statistical and mathematical analyses of the results were performed.
    Celem pracy było obliczenie parametrów kinetycznych (energii aktywacji Ea, współczynnika przedwykładniczego A, stałej szybkości k) procesu termolizy prażonego i surowego drewna wierzby konopianki (Salix viminalis L.) oraz określenie wpływu warunków modyfikacji termicznej na kinetykę tego procesu. Stosowano próbki wikliny surowej oraz prażonej w następujących warunkach: temperatura procesu 200°C, czas prażenia: 6 godzin (W-200-6-H2O), 12 godzin (W-200-12-H2O) oraz 24 godziny (W-200-24-H2O). Proces był prowadzony w atmosferze pary wodnej, działającej przez 6 godzin w początkowym okresie modyfikacji. Surowce poddano analizie termograwimetrycznej w warunkach izotermicznych. Analizy były prowadzone w atmosferze helu w temperaturach 270°C, 285°C, 300°C, 330°C. Rejestrowano krzywe TG i DTG. Charakterystykę termiczną wikliny oparto na analizie termograwimetrycznej w warunkach dynamicznych, w temperaturze do 600°C. Na podstawie danych otrzymanych z wykonanych analiz obliczono parametry kinetyczne (Ea, A, k) i przeprowadzono analizę statystyczno- matematyczną wyników. Wartość energii aktywacji procesu termolizy wikliny zawierała się w przedziale 138,1– –227,3 kJ/mol. Największą wartość Ea (227,3 kJ/mol) uzyskano w przypadku wikliny prażonej w temperaturze 200°C, w czasie 24 godzin (W-200-24-H2O). Surowiec ten również okazał się najbardziej odporny termicznie. W celu ustalenia funkcji g(α), która najlepiej opisuje proces termicznego rozkładu surowego i prażonego drewna wierzby konopianki wybrano trzy modele kinetyczne: F1, D3, R3. Modelem, który najlepiej opisywał dane doświadczalne był model D3, odnoszący się do procesu dyfuzji trójwymiarowej.
    Źródło:
    Drewno. Prace Naukowe. Doniesienia. Komunikaty; 2012, 55, 187
    1644-3985
    Pojawia się w:
    Drewno. Prace Naukowe. Doniesienia. Komunikaty
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Development and validation of a quantitative dilatometric analysis model of austenite decomposition into ferrite and pearlite
    Opracowanie i walidacja modelu ilościowej analizy dylatometrycznej rozpadu austenitu w ferryt i perlit
    Autorzy:
    Opara, J.
    Wrożyna, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/182071.pdf
    Data publikacji:
    2015
    Wydawca:
    Sieć Badawcza Łukasiewicz - Instytut Metalurgii Żelaza im. Stanisława Staszica
    Tematy:
    hypoeutectoid steel
    dilatometry
    austenite decomposition
    ferrite
    pearlite
    lattice parameter
    kinetics
    stal podeutektoidalna
    dylatometria
    rozpad austenitu
    ferryt
    perlit
    parametry sieci
    kinetyka
    Opis:
    The quantitative dilatometric analysis model for the austenite decomposition into ferrite and pearlite during continuous cooling treatment is presented. It is based on measurements of a relative length change of a sample during the progress of phase transformations and calculations of the difference in atomic volume of present phases. The proposed model incorporates crucial effects accompanying the austenite decomposition, i.e. the carbon enrichment of the remaining austenite during ferrite formation, which causes an increase in the definite atomic volume of austenite, while formation of pearlite has a clearly different impact with the volume fractions of cementite and ferrite regulated by constant carbon composition inherited from austenite (enriched in carbon). The analysis results are compared with quantitative microstructure analysis and an excellent convergence has been found. Depicted results state a convincing confirmation that the model is correctly developed by the authors. Additionally, kinetics of phase transformations as function of normalized time were analyzed and a process of carbon enrichment of austenite was demonstrated.
    W niniejszej pracy zaprezentowano model ilościowej analizy dylatometrycznej dla rozpadu austenitu w ferryt i perlit podczas ciągłego chłodzenia. Rozwiązanie bazuje na pomiarach względnej zmiany długości próbki w trakcie postępu przemian fazowych oraz obliczeniach różnic objętości atomowych występujących faz. Zaproponowany model uwzględnia kluczowe zjawiska towarzyszące rozpadowi austenitu, tzn. wzbogacanie się austenitu w węgiel podczas powstawania ferrytu, które powoduje wzrost określonej objętości atomowej austenitu, podczas gdy formowanie się perlitu ma wyraźnie odmienny wpływ poprzez udziały objętościowe ferrytu i cementu, które wynikają z ustalonej zawartości węgla dziedziczonej z austenitu (wzbogaconego w węgiel). Rezultaty ilościowej analizy dylatogramów zestawiono z ilościową analizą mikrostruktur i uzyskano doskonałą zbieżność wyników. Przedstawione wyniki stanowią wyraźne potwierdzenie, iż model jest poprawnie opracowany przez autorów. Ponadto, przeprowadzono analizę kinetyk przemian fazowych w funkcji znormalizowanego czasu oraz przedstawiono proces wzbogacania austenitu w węgiel.
    Źródło:
    Prace Instytutu Metalurgii Żelaza; 2015, T. 67, nr 4, 4; 24-32
    0137-9941
    Pojawia się w:
    Prace Instytutu Metalurgii Żelaza
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    The Applicability of Chromatographic Methods in the Investigation of Ageing Processes in Double Base Rocket Propellants
    Autorzy:
    Matečić-Muśanić, S.
    Sućeska, M.
    Čuljak, R.
    Powiązania:
    https://bibliotekanauki.pl/articles/358695.pdf
    Data publikacji:
    2013
    Wydawca:
    Sieć Badawcza Łukasiewicz - Instytut Przemysłu Organicznego
    Tematy:
    activation energy
    artifcial ageing
    DB rocket propellants
    decomposition
    Ethyl Centralite (EC)
    Gel Permeation Chromatography (GPC)
    High Performance Liquid Chromatography (HPLC)
    kinetics of degradation
    mean molecular mass of NC
    Opis:
    The ageing of double base (DB) rocket propellants is the result of chemical decomposition reactions and physical processes, causing degradation of a number of relevant propellant properties (such as reduction in stabilizer and nitroglycerine (NG) content, reduction of the mean molecular mass of nitrocellulose (NC) etc.), which is refected in a decrease in the reliable service life time of DB propellants. This is the reason why the study of processes of ageing and their consequences (effects) is so important. In this paper we have studied the kinetics of DB rocket propellant decomposition during their artifcial ageing, i.e. at elevated temperatures. The kinetic parameters were obtained by measurements of the stabilizer/Ethyl Centralite (EC) content and the mean molecular mass reduction of NC, during artifcial ageing at temperatures of 80, 85 and 90 °C. Consumption of the EC was observed using High Performance Liquid Chromatography (HPLC), whilst the reduction in the mean molecular mass of NC was monitored using Gel Permeation Chromatography (GPC). It has been shown that artifcial ageing of DB propellant causes signifcant EC consumption and a reduction in the mean molecular mass of NC, from the very beginning of ageing. EC is entirely consumed after 120 days at 80 °C, and is followed by the intensive reactions of NC decomposition. Signifcant changes in the mean molecular mass of NC starts after 60 days of ageing at 90 °C (or ~250 days at 80 °C). The results obtained from the kinetic data have shown that the activation energy of DB propellant decomposition, determined on the basis of changes in the mean molecular mass of NC is 145.09 kJ•mol-1 , whilst the activation energy of decomposition obtained on the basis of EC consumption is 142.98 kJ•mol-1 , which is consistent with available literature values [1, 2].
    Źródło:
    Central European Journal of Energetic Materials; 2013, 10, 2; 245-262
    1733-7178
    Pojawia się w:
    Central European Journal of Energetic Materials
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-13 z 13

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