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Determining the Enthalpy of an Fe-Ni Alloy at Various Temperatures Using the ‘STA’ PT 1600 Equipment

Publié en ligne: 21 Mar 2022
Volume & Edition: AHEAD OF PRINT
Pages: -
Reçu: 07 Jan 2021
Accepté: 12 Jun 2021
Détails du magazine
License
Format
Magazine
eISSN
1854-7400
Première parution
30 Mar 2016
Périodicité
4 fois par an
Langues
Anglais
Abstract

V tem raziskovalnem prispevku smo določili entalpijo zlitine Fe-Ni z uporabo naprave ‘STA’ laboratorija Univerze v Mitrovici ‘Isa Boletini’, Oddeleka za materiale in metalurgijo. Vzorec za analizo je bil odvzet v tovarni ferroniklja, medtem ko je priprava vzorca za analizo na napravi ‘STA PT 1600’ potekala v laboratoriju Univerze v Mitrovici ‘Isa Boletini’.

Analiziran vzorec zlitine Fe-Ni v obliki granule je bil velikosti 2–4 cm. Vseboval je 22,55 % Ni, 76,51 % Fe in majhne količine drugih elementov [1, 2]. Pri analizi zlitine Fe-Ni smo dobili tri vrednosti entalpije glede na pogoje analize z maksimalno temperaturo 800 °C in minimalno temperaturo 600 °C, pri čemer je bila zlitina izpostavljena obema temperaturama posebej po 45 minut.

Iz dobljenih rezultatov smo zbrali negativne vrednosti entalpije v treh preučenih scenarijih in eksotermnem procesu, kjer je ΔH<0 [3]. Entalpija se zmanjšuje, ko sistem sprošča toploto z naraščanjem temperature [4].

Keywords

Ključnebesede

Introduction

Production of Fe-Ni alloy is a difficult process, beginning with the treatment of Fe-Ni ore and involving use of a rotary kiln, an electrical furnace, and finally a converter for the refinement of the metal [1, 5]. The costs of fuel for the rotary kiln and the electricity for melting the calcine are high.

The TGA/DSC equipment measures the heat as well as the change in weight of a material as a function of temperature or time in a controlled environment. The simultaneous measurements of these characteristics not only improve productivity, but also simplify the interpretation of results. The data obtained make it possible to differentiate between endothermic and exothermic processes that do not experience weight loss (melting and crystal-lisation) and those that do experience weight loss (reduction). The simultaneous thermic analyser LINSEIS STA PT 1600 can be used for determining coinciding differences in mass (Tg) and caloric reactions (DSC) of a sample in a 25°C to 1650° temperature range. This simultaneous thermic analyser delivers high accuracy and high resolution. The equipment used for this research is located at the Department of Materials and Metallurgy of the University of Mitrovica ‘Isa Boletini’ (UMIB) and has the following three sensors: TG, TG-DTA, and TG-DSC.

All of the LINSEIS thermo-analytic instruments are controlled from a personal computer (PC). The individual software modules function exclusively using the Microsoft operating system Windows. The software is made up of three modules: temperature control, data acquisition, and data evaluation. The 32-bit program encompasses all fundamental properties for preparing, executing, and evaluating an STA measurement. Thanks to our application experts and specialists, LINSEIS was able to develop a user-friendly, all-inclusive software.

The standard enthalpy of forming a compound is defined as the energy associated with the reaction to form the compound from its constituent elements [3, 4]. The standard enthalpy of formation is a basic thermodynamic property that determines its phase stability, which can be coupled with other thermodynamic data to calculate phase diagrams.

Materials and methods

We carried out the analysis of the Fe-Ni alloy at the Ferronikel plant's laboratory in Drenas and obtained the following composition expressed as the percentage of each element [2] (Table 1):

Composition of Fe-Ni alloy [2]

Ni Fe S C Co P Si Cr Cu
22.55% 76.51% 0.12% 0.01% 0.75% 0.01% 0.01% 0.01% 0.03%

Figure 1

View of a metal casting of refined Fe-Ni.

Figure 2

View of Fe-Ni alloy (granule) [2].

Figure 3

Preparation of the sample (UMIB).

The Fe-Ni alloy sample with the composition found in (Table 1) was prepared at the laboratory of UMIB Department of Materials and Metallurgy. For the preparation of the Fe-Ni alloy sample, we relied on the available parameters of the LINSEIS ‘PT STA 1600’.

The sample has the following parameters:

Length: 4 mm

Width: 4 mm

Weight: 0.5413 g

The sample was weighed on an analytical scale (Figure 4) at the laboratory of the Faculty of Food Technology (UMIB).

Figure 4

Measuring weight of the sample on an analytical scale.

The Fe-Ni alloy sample, after polishing, was placed on the ‘alumina’ plate, and the conditions of the analysis were as follows:

Maximum temperature = 800 °C, for a dura­tion of 45 minutes

Minimum temperature = 600 °C, for a dura­tion of 45 minutes

The initial temperature is the initial extrapolated temperature of the reaction; the final temperature is the final extrapolated temperature of the reaction. In an exothermic reaction, energy is released because the total energy of the products is lower than the total energy of the reactants. As a result, the change in enthalpy, ΔH, for an exothermic reaction will always be negative. The heat variations in chemical reactions are often measured at the laboratory under conditions in which the reaction system is open to the ambient temperatures. In that case, the system is exposed to constant pressure. Chemists routinely evaluate changes in the enthalpy of chemical systems as the reactants are converted into products. The heat absorbed or released by a reaction at constant pressure is the same as the change in enthalpy and is identified by the symbol ΔH.

Figure 5

LINSEIS PT 1600 (UMIB laboratory).

Figure 6

Determination of the enthalpy of the Fe-Ni alloy in LINSEIS ‘PT STA 1600’ at UMIB.

Discussion of results

Using the LINSEIS ‘PT STA 1600’ to analyse the Fe-Ni alloy, we have determined the enthalpy, which decreases as the temperature rises (ΔH<0), leading to the conclusion that these reactions are exothermic [3, 4]. Energy must be inserted into the system to break the chemical bonds, as they frequently do not break away spontaneously. The formation of bonds includes the release of energy; therefore, if more energy is produced in the formation of the bond than is necessary to break the bond, the enthalpy is negative—as we have found in the Fe-Ni alloy [3]. In this example, the change in enthalpy is negative because heat is released from the system, causing the overall enthalpy of the system to decrease [3, 4].

The heat of the reaction is the change of enthalpy for a chemical reaction [3]. The determination of the enthalpy of the Fe-Ni alloy supports our conclusion that the Fe-Ni alloy is an appropriate product for the acquisition of special steels and other stable alloys [3, 4].

Figure 1

View of a metal casting of refined Fe-Ni.
View of a metal casting of refined Fe-Ni.

Figure 2

View of Fe-Ni alloy (granule) [2].
View of Fe-Ni alloy (granule) [2].

Figure 3

Preparation of the sample (UMIB).
Preparation of the sample (UMIB).

Figure 4

Measuring weight of the sample on an analytical scale.
Measuring weight of the sample on an analytical scale.

Figure 5

LINSEIS PT 1600 (UMIB laboratory).
LINSEIS PT 1600 (UMIB laboratory).

Figure 6

Determination of the enthalpy of the Fe-Ni alloy in LINSEIS ‘PT STA 1600’ at UMIB.
Determination of the enthalpy of the Fe-Ni alloy in LINSEIS ‘PT STA 1600’ at UMIB.

Composition of Fe-Ni alloy [2]

Ni Fe S C Co P Si Cr Cu
22.55% 76.51% 0.12% 0.01% 0.75% 0.01% 0.01% 0.01% 0.03%

Bajraktari-Gashi, Z., Zabeli, M., Halilaj, B. (2020): Key metallurgical parameters of Fe-Ni production during 1984–1997 and 2007–2017 at the Ferronickel smelter in Drenas. Materials and Geoenvironment, 67(2), pp. 73–77, DOI: 10.2478/rmzmag-2020-0008. Bajraktari-GashiZ. ZabeliM. HalilajB. 2020 Key metallurgical parameters of Fe-Ni production during 1984–1997 and 2007–2017 at the Ferronickel smelter in Drenas Materials and Geoenvironment 67 2 73 77 10.2478/rmzmag-2020-0008 Ouvrir le DOISearch in Google Scholar

New Ferronickel Complex L.L.C. (1984–1997; 2016–2020). Official Documentation of Melting. New Ferronickel Complex L.L.C. 1984–1997 2016–2020 Official Documentation of Melting Search in Google Scholar

Peter, A., Julio, D.P. (2006): Physical Chemistry. Oxford University Press: Oxford, 1000 pp. PeterA. JulioD.P. 2006 Physical Chemistry Oxford University Press Oxford 1000 Search in Google Scholar

Shamsuddin, M. (2016): Physical Chemistry of Metallurgical Processes, Second Edition. John Wiley & Sons, Inc: New Jersey, 608 pp. ShamsuddinM. 2016 Physical Chemistry of Metallurgical Processes, Second Edition John Wiley & Sons, Inc New Jersey 608 10.1002/9781119078326 Search in Google Scholar

Bajraktari-Gashi, Z., Halilaj, B. (2018): Material balance of the technological process in the new foundry of new Ferronikel in Drenas during 2017. Journal of Technology and Exploitation in Mechanical Engineering, 4(1), pp. 29–35, DOI: 10.35784/jteme.90. Bajraktari-GashiZ. HalilajB. 2018 Material balance of the technological process in the new foundry of new Ferronikel in Drenas during 2017 Journal of Technology and Exploitation in Mechanical Engineering 4 1 29 35 10.35784/jteme.90 Ouvrir le DOISearch in Google Scholar

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