Impact of Ni on the thermophysical and thermodynamic properties of Fe–C–Ni based alloys

Three model alloys based on Fe-C-Ni were studied containing carbon between 0.338 and 0.382 wt. % and nickel between 1.084 and 4.478 wt. %. Phase transition temperatures, heat capacity, enthalpy change, heat of fusion, coefficient of thermal expansion, and density were experimentally and theoretically determined in the high-temperature area from 1000 degrees C to 1595 degrees C. A number of techniques, namely differential thermal analysis (DTA), differential scanning calorimetry (DSC), and dilatometry, were used in this study, and the heat of fusion was determined by two approaches, that is, from the DSC peak area and from the enthalpy change. The experimental data were compared and discussed with the calculation results obtained using SW IDS, JMatPro, and Thermo-Calc operating with the commercially available TCFE8 thermodynamic database. The obtained experimental results show that the liquidus temperature and the coefficient of thermal expansion decrease with increasing nickel content. On the contrary, the density and heat of fusion values derived from the DSC peak increase with increasing nickel content. Furthermore, an ambiguous influence of nickel on the change in solidus temperature, heat capacity, enthalpy change, and heat of fusion obtained from the enthalpy change was observed.Web of Science204332431

The relationship between nil-strength temperature, zero strength temperature and solidus temperature of carbon steels

The nil-strength temperature, zero strength temperature and solidus temperature are significant parameters with respect to the processes of melting, casting and welding steels. With the use of physical tests performed on the universal plastometer Gleeble 3800 and calculations in the IDS software, the nil-strength temperatures, zero strength temperatures and solidus temperatures of nine non-alloy carbon steels have been determined. Apart from that, solidus temperatures were also calculated by the use of four equations expressing a mathematical relation of this temperature to the chemical composition of the investigated steels. The nil-strength and zero strength temperatures and the solidus temperatures decreased with increasing carbon content in the investigated steels. Much higher content of sulfur in free-cutting steel resulted in a decrease of all the temperatures investigated. The zero strength temperatures determined by calculation in the IDS software during solidification were approximately 43-85 degrees C higher than the nil-strength temperatures determined experimentally during heating of the investigated steels. The linear dependence of experimentally measured nil-strength temperature on the calculated zero strength temperature for the investigated steels was determined. Based on regression analyses, there were determined mathematical relations which described with high accuracy a linear dependence of the nil-strength and zero strength temperatures on the solidus temperature of the investigated steels.Web of Science103art. no. 399

Cast Gothic Sacral Sculptures

Import 05/08/2014Táto bakalárska práca sa zaoberá vývojom gotickej skulptúry vo Francúzsku, Nemecku, Česku a na Slovensku. Ďalej popisuje technológiu výroby hlineného a trvalého modelu gotickej sakrálnej plastiky, jej formovanie do bentonitovej zmesi, odlievanie, povrchovú úpravu cizelovaním a leštením.This bachelor thesis deals with the evolution of gothic sculpture in France, Germany, Czech Republic and Slovakia. Further describes the production technology for clay model and permanent model of sacral gothic sculpture, formation in bentonite mixture, casting, surface finish with chiselling and polishing.618 - Katedra metalurgie a slévárenstvívýborn

Study of real steel grades with use of thermal analysis methods

Import 02/11/2016Jednou z najdôležitejších binárnych sústav technickej praxe je sústava Fe-C, ktorá je základom zliatin železa. Výsledky modelovania fázových diagramov, termofyzikálnych a termodynamických vlastností pre reálne akosti ocelí sa mnohokrát len blížia výsledkom experimentov. Preto je nutné naďalej experimentálne študovať systémy na báze Fe-C (ocele), spresňovať fázové diagramy, termofyzikálne a termodynamické dáta a zdokonaľovať databázy softwarov zaoberajúcich sa touto problematikou. Presné materiálové dáta sú taktiež nutné pre mnohé technologické procesy – pre ich optimálne nastavenia (napr. pre tepelné spracovanie a odlievanie). Tepelné správanie systémov na báze Fe-C je možné popísať metódami termickej analýzy, medzi ktoré patrí diferenčná termická analýza (DTA) a diferenčná skenovacia kalorimetria (DSC). Pomocou týchto metód je možné získať teploty a latentné teplá fázových transformácií, tepelné kapacity a ich závislosť na teplote. Značný vplyv na získané dáta môžu mať experimentálne podmienky, ktoré je potrebné eliminovať prostredníctvom kalibračných a metodických meraní. Diplomová práca je zameraná na štúdium teplôt a latentných tepiel fázových transformácií a tepelných kapacít (v závislosti na teplote) dvoch reálnych akostí ocelí. V nízkoteplotnej oblasti boli pozorované teploty počiatku (Tα→γ,S) a ukončenia (Tα→γ,E) fázovej transformácie α→γ a latentné teplá tejto transformácie (ΔHα→γ). Vo vysokoteplotnej oblasti boli pozorované teploty solidu (TS), likvidu (TL), peritektickej transformácie (TP) a latentné teplá topenia (ΔHtav.). Tepelné kapacity boli pozorované v rozmedzí teplôt 150 – 1320°C. Teploty a latentné teplá boli získané pomocou diferenčnej termickej analýzy (DTA) pri rýchlosti ohrevu 10°C/min. a tepelné kapacity pomocou diferenčnej skenovacej kalorimetrie (DSC) s použitím „continuous“ metódy pri rýchlosti ohrevu 5°C/min. V rámci experimentov boli prevedené kalibračné a doplňujúce metodické merania. Výsledné teploty boli aproximované na „rovnovážne podmienky“. Na základe opakovania experimentov bola prevedená základná štatistická analýza. Experimentálne získané dáta boli porovnávané a diskutované s výsledkami výpočtov SW Thermo-Calc a teplota likvidu aj s teoretickými výpočtami podľa vybraných empirických vzťahov.One of the most important binary systems of engineering practise is Fe-C system, which is the base of iron alloys. Results of phase diagrams modelling, thermophysical and thermodynamical properties modelling for real steel grades is still only approaching the results of experiments. Therefore, it is necessary to study Fe-C based systems (steels), precise phase diagrams, thermophysical and thermodynamical data and so enhance the quality of SW databases and calculation relations. Proper material data are necessary for many of technological processes – for their optimal adjustment (e.g. for heat treatment and casting). Thermal behaviour of Fe-C based systems can be characterized by thermal analysis methods, such as by differential thermal analysis (DTA) and differential scanning calorimetry (DSC). Using these methods it is possible to obtain temperatures and latent heats of phase transformations, heat capacity and its temperature dependence. A significant effect on the obtained data can have the experimental conditions that should be eliminated by calibration and methodological measurements. The thesis is focused on the study of temperatures, latent heats of phase transformations and thermal capacity (in dependence on temperature) of two real steel grades. In the low-temperature region were observed temperatures of start (Tα→γ,S) and end (Tα→γ,E) of α→γ transformation and latent heats of this transformation (ΔHα→γ). In the high temperature region were observed temperatures of solidus (TS), liquidus (TL), peritectic transformation (TP) and latent heats of fusion (ΔHtav.). Heat capacities were observed in the temperature range 150 – 1320°C. Temperatures and latent heats were obtained using differential thermal analysis (DTA) by heating rate of 10°C/min and the heat capacity using differential scanning calorimetry (DSC) by heating rate of 5°C/min. and "continuous" method. Calibration and methodological experiments were performed in the frame of this work. Phase transformation temperatures were approximated to “equilibrium conditions”. Repeated experiments were performed and basic statistics was done. Experimental data were compared and discussed with calculation results using SW Thermo-Calc and liquidus temperature also with results obtained by empirical equations.619 - Katedra fyzikální chemie a teorie technologických pochodůvýborn

Study of thermophysical and thermodynamic properties of systems based on Fe-C-O-X(Y),(X, Y = Cr, Ni) in solid and liquid phase

Chróm a nikel patria medzi významné legovacie prvky ocelí. Znalosť jednoduchších systémov ako napr. Fe C Cr, Fe C Ni a Fe C Cr Ni je nevyhnutná pre správny termodynamický a termofyzikálny popis polykomponentných systémov (ocelí) a podobných zliatin využívaných v praxi. V tejto oblasti je stále nedostatok presných experimentálnych výsledkov, ktoré môžu slúžiť ako vstupné dáta pre tvorbu a spresnenie databáz na báze Fe (napr. pre SW JMatPro a Thermo Calc) a taktiež môžu byť využité v simulačných softvéroch (napr. SW Procast). Z týchto dôvodov je štúdium systémov na báze Fe C Cr, Fe C Ni a Fe C Cr Ni stále aktuálnou témou. Tepelné správanie systémov na báze Fe C je možné okrem iného popísať metódami termickej analýzy, medzi ktoré patrí diferenčná termická analýza (DTA), diferenčná skenovacia kalorimetria (DSC), dilatometria a ďalšie. Pomocou týchto metód je možné získať teploty a teplá fázových transformácií, tepelné kapacity, zmenu entalpie, koeficient teplotnej rozťažnosti, hustotu a ich závislosť na teplote. Pre získanie presných dát je nevyhnutné eliminovať experimentálne vplyvy prostredníctvom kalibračných a metodických meraní. V rámci riešenia dizertačnej práce boli získané cenné pôvodné fundamentálne dáta a poznatky o študovaných systémoch. Dizertačná práca je zameraná na štúdium teplôt a tepiel fázových transformácií, tepelných kapacít, zmeny entalpie, koeficientu teplotnej rozťažnosti a hustoty (v závislosti od teploty) zliatin na báze Fe C O Cr, Fe C O Ni a Fe C O Cr Ni. V nízkoteplotnej oblasti boli študované teploty počiatku (Tα→γ,S) a ukončenia (Tα→γ,E) fázovej transformácie α→γ a teplá tejto transformácie. Vo vysokoteplotnej oblasti boli študované teploty solidu (TS), liquidu (TL), počiatku (TP,S) a ukončenia (TP,E) peritektickej transformácie a teplá topenia. Tepelné kapacity a zmena entalpie boli získané v rozmedzí teplôt 30 – 1580 °C. Koeficient teplotnej rozťažnosti a hustota boli študované v rozsahu 200 – 1600 °C. Teploty fázových transformácií boli získané pomocou troch metód a to diferenčnej termickej analýzy (DTA), diferenčnej skenovacej kalorimetrie (DSC) a dilatometrie. Tepelné kapacity, z ktorých bola následne vypočítaná zmena entalpie, boli získané pomocou diferenčnej skenovacej kalorimetrie (DSC) s použitím „continuous“ metódy. Dilatometrické krivky, z ktorých bol vypočítaný koeficient teplotnej rozťažnosti a hustota, boli získané pomocou dilatometrie. V rámci experimentov boli realizované kalibračné a doplňujúce metodické merania. Výsledné teploty boli aproximované na „rovnovážne podmienky“. Na základe opakovania experimentov bola uskutočnená základná štatistická analýza. Experimentálne získané dáta boli porovnávané a diskutované s výsledkami výpočtov SW Thermo Calc, JMatPro a IDS a s hodnotami dostupnými v literatúre. Vybrané študované zliatiny boli podrobené štruktúrnej a fázovej analýze. Na základe získaných výsledkov boli vyvodené zodpovedajúce závery. Ďalej boli tiež pomocou lineárnej regresie z výsledkov týchto meraní doplnených o ďalšie výsledky nadobudnuté v rámci projektu GAČR reg. č. 17 18668S získané nové modely pre výpočet teploty liquidu, tepelnej kapacity a zmeny entalpie zohľadňujúce vplyv chemického zloženia, predovšetkým chrómu a niklu, a teploty na študované termofyzikálne vlastnosti vo forme empirických vzťahov.Chromium and nickel are important alloying elements for steels. Knowledge of simpler systems such as Fe C Cr, Fe C Ni and Fe C Cr Ni are necessary for the accurate thermodynamic and thermophysical description of polycomponent systems (steels) and similar alloys used in practice. There is still a lack of accurate experimental results in this area, which can serve as input data for the creation and refinement of Fe-based databases (for e.g. SW JMatPro and Thermo Calc) and can also be used in simulation software (e.g. SW Procast). For these reasons, the study of systems based on Fe C Cr, Fe C Ni and Fe C Cr Ni is still an actual topic. The thermal behaviour of Fe C based systems can be among other things described by thermal analysis methods, which include differential thermal analysis (DTA), differential scanning calorimetry (DSC), dilatometry and others. Using these methods, it is possible to obtain temperatures and heats of phase transformations, heat capacity, enthalpy change, coefficient of thermal expansion, density and their dependence on temperature. In order to obtain accurate data, it is necessary to eliminate experimental conditions through calibration and methodological measurements. Within the solution of the dissertation, valuable original fundamental data and knowledge about the studied systems were obtained. The dissertation is focused on the study of temperatures and heats of phase transformations, heat capacities, enthalpy change, coefficient of thermal expansion and density (depending on temperature) of alloys based on Fe C O Cr, Fe C O Ni and Fe C O Cr Ni. In the low-temperature area, the start (Tα→γ,S) and end (Tα→γ,E) temperatures of the phase transformation α→γ and the heats of this transformation were studied. Solidus (TS), liquidus (TL), start (TP,S) and end (TP,E) of peritectic transformation temperatures and heats of melting were studied in the high temperature region. Heat capacities and enthalpy change were obtained in the temperature range 30 – 1580 °C. The coefficient of thermal expansion and density were studied in the range of 200 – 1600 °C. Phase transformation temperatures were obtained using three methods: differential thermal analysis (DTA), differential scanning calorimetry (DSC) and dilatometry. The heat capacities from which the enthalpy change was subsequently calculated were obtained by differential scanning calorimetry (DSC) using the "continuous" method. Dilatometric curves, from which the coefficient of thermal expansion and density were calculated, were obtained by dilatometry. Within the experiments, calibration and additional methodological measurements were performed. The resulting temperatures were approximated to the "equilibrium conditions". Based on the repetition of the experiments, a basic statistical analysis was performed. The experimentally obtained data were compared and discussed with the results of SW calculations Thermo Calc, JMatPro and IDS and with the values available in the literature. Selected studied alloys were subjected to structural and phase analysis. Based on the obtained results, corresponding conclusions were drawn. Furthermore, by means of a linear regression from the results of these measurements, they were supplemented by other results obtained within the GAČR project reg. no. 17 18668S obtained new models for calculating liquidus temperature, heat capacity and enthalpy change taking into account the influence of chemical composition, especially chromium and nickel, and temperature on the studied thermophysical properties in the form of empirical relationships.619 - Katedra fyzikální chemie a teorie technologických procesůvyhově

Cordierite/CeO2 ceramic nanocomposites from vermiculite with fixed CeO2 nanoparticles, talc and kaolin

Ceria-based metal oxides are promising redox materials for photocatalytic decomposition of N2O emissions. The objective of this work was to evaluate the structural properties of cordierite ceramics with anchored CeO2 nanoparticles produced by sintering talc, kaolin and vermiculite with CeO2 nanoparticles precursor. In this contribution, we discuss the effect of the presence of CeO2 nanoparticles on the softening and crystallization temperatures of cordierite, and the influence of the sintering procedure on the microstructure properties of the anchored CeO2 nanocrystals. The materials were characterized by X-ray diffraction analysis, differential thermal analysis and morphology of ceria nanoparticles was visualized in a high-resolution transmission electron microscope (HRTEM). The chemical interactions between CeO2 and the clay minerals were investigated using energy dispersive X-ray spectroscopy in the scanning transmission electron microscope (STEM) and complemented by the Raman measurements. X-ray diffraction revealed that the sintered ceramics contain cordierite-indialite, orthoenstatite and protoenstatite. Differential thermal analysis showed that the addition of 3 mass% of CeO2 decreases the softening and the crystallization temperature of cordierite by approximately 50 degrees C. HRSTEM/EDS observed the Fe concentration of CeO2 nanoparticles, probably due to migration of Fe3+ ions from vermiculite in crystallizing cordierite. The hypothesis of Fe dopant in ceria was proven by local chemical analysis, which was performed with the aid of an EDX line scan in the HRSTEM, by the shift of the Raman CeO2 F-2g mode to lower wavenumbers and by the presence of a Raman band from oxygen vacancies.Web of Science179art. no. UNSP 10515

Possibilities of complex experimental study of thermophysical and thermodynamic properties of selected steels

In this paper, selected key thermophysical and thermodynamical properties of steels (three alloys based on Fe-C-Cr) such as solidus (T-S) and liquidus (T-L) temperatures, peritectic transformation temperatures (T-P), heats of fusion (Delta H-F), specific heat capacities(c(P)), surface tension (sigma) , and wettability expressed by the wetting angle (theta) of liquid steel on alumina substrate were experimentally determined in a high-temperature area up to the temperature of 1600 degrees C. The effect of the temperature and the chemical composition of steel on these properties was investigated using 3D heat flux DSC (Differential Scanning Calorimetry) and a sessile drop method. The interaction of the steel samples with the alumina substrate was studied by SEM, EDX and XRD methods. To assess the influence of the major elements (carbon and chromium), the steels with different carbon and chromium content, which varied in the range of 0.077-0.381 wt.% and 0.049-4.990 wt.%, were chosen. It was shown that increasing carbon and chromium content led to a decrease in phase transformation temperatures and thermal capacities, as well as an increase in the heat of fusion, surface tension, and wetting angle. Furthermore, the rising temperature increases the thermal capacities and wetting angles. Whereas the surface tension followed the opposite trend.Web of Science843643363

Experimental and theoretical assessment of liquidus, peritectic transformation, and solidus temperatures of laboratory and commercial steel grades

The paper deals with theoretical and experimental study of phase transformation temperatures of steels in high temperature region (above 1000 degrees C), with focus on the solidus temperature, peritectic transformation temperature and liquidus temperature of multicomponent steels. Experimental data were obtained using Differential Thermal Analysis and direct thermal analysis. The experimental data were assessed by basic statistics. The calculations were performed using InterDendritic Solidification software and Thermo-Calc software. Also, selected empirically based models were used for calculations. The study presents the basic principles of theoretical and experimental methods, characteristics, advantages and disadvantages. Both used thermo-analytical methods are set correctly; the results are reproducible, comparable and close to equilibrium temperatures. Furthermore, comprehensive comparisons between the calculated and measured phase transformation temperatures show that the experimental data is satisfactorily accounted for by the present thermodynamic description.Web of Science4011039

Study of phase transformation temperatures of alloys based on Fe-C-Cr in high-temperature area

Three alloys based on Fe-C-Cr were studied. These alloys contained carbon in a range of 0.308-0.380 mass% and chromium 1.058-4.990 mass%. Temperatures of solidus (onward used as T (S)), liquidus (onward used as T (L)) and peritectic transformation (onward used as T (P)) were studied in the high-temperature region. These temperatures were obtained using two thermal analysis methods: differential thermal analysis (onward used as DTA) and simple thermal analysis (onward used as TA). The Setaram Setsys 18(TM) was used for experiments with employment of the DTA method. All measurements were taken in an inert atmosphere of pure argon at heating rate of 10 A degrees C min(-1), and simple TA method was used for the experiments with the use of the Netzsch STA 449 F3 Jupiter. Measurements were taken in inert atmosphere of pure argon at a heating and cooling rate of 5 A degrees C min(-1). Phase transformation temperatures were obtained by heating and cooling process and were approximated to "equilibrium conditions" (DTA method: zero heating rate and sample mass, standard, TA method: only standard) (A 1/2 aludova et al. in J Therm Anal Calorim 112:465-471, 2013a. The experimental data were compared and discussed with the calculation results using IDS (solidification analysis package) software (onward used as SW) Thermo-Calc and the TCFE8 (Thermo-Calc Fe-based alloys) database. The results of the two alloys were compared with those published for similar steels. The experimentally obtained transition temperatures were close to the calculated values. The solidus, liquidus and peritectic transformation temperatures were lowered with increasing carbon (range 0.308-0.380 mass%) and chromium content (range 1.058-4.990 mass%). The smallest difference between the experimental results and theoretical calculations was observed at the liquidus temperature for all alloys. Nonetheless, the difference measured for the solidus temperatures was much greater.Web of Science1331484

Prediction and measurement of selected phase transformation temperatures of steels

The study deals with precise determination of phase transformation temperatures of steel. A series of experimental measurements were carried out by Differential Thermal Analysis (DTA) and Direct Thermal Analysis (TA) to obtain temperatures very close to the equilibrium temperatures. There are presented results from the high temperatures region, above 1000 degrees C, with focus on the solidus temperatures (T-S), peritectic transition (T-P) and liquidus (T-L) of multicomponent steels. The data obtained were verified by statistical evaluation and compared with computational thermodynamic and empirical calculations. The calculations were performed using 15 empirical equations obtained by literature research (10 for T-L and 5 for T-S), as well as by software InterDendritic Solidification (IDS) and Thermo-Calc (2015b, TCFE8; TC). It was verified that both thermo-analytical methods used are set correctly; the results are reproducible, comparable and close to equilibrium state.Web of Science53339839