Derivative Thermal Analysis Research Articles

Crystallisation kinetics and structure of modified Zn\u2013Al\u2013Cu alloys

The primary purpose of the work was to try to answer the following questions: How will the addition of lanthanum and cerium affect the crystallisation kinetics of the alloys tested? What will be the relationship between changes in the shape of the derivative curve and the microstructure and the same properties of Zn–Al10–Cu1 alloys? To improve properties of the casting zinc alloy, modification of the structure consisting in the change in the morphology of alloy structural constituents has been applied, primarily by reducing interfacial eutectic α′ + η, reduction in the size of fundamental components, as well as the effect of La on the change in the grain morphology of the solid solution with the aluminium matrix from the dendritic one to the “tweed” one. To describe the phenomena that occur in the material during solidification as a result of the application of modifiers, the thermal derivative analysis and structural analysis using scanning and transmission electron microscopy method were carried out.

Influence of Sr addition on microstructure of the hypereutectic Zn\u2013Al\u2013Cu alloy

The purpose of the presented work is to answer the questions: how does the addition of strontium to the Zn–8Al–1Cu alloy crystallisation kinetics influence? What will the significance of the low temperature of heat treatment, characteristic for eutectic Zn–Al alloys, have for the formation of intermetallic phases? To describe the phenomena that occur in the metal during solidification under various conditions caused by the variable cooling rate, and as a result of the application of modifiers that provide the basis for heterogeneous nucleation, it was decided to use thermal-derivative analysis method. The mentioned method allows to accurately describe and interpret the kinetics of crystallisation of the tested materials. The effectiveness of the modification was assessed based on a degree of fragmentation of the structural components and changes in the properties of the material being modified, as well as by analysis of the cooling curves of the tested alloys. The thermal events occurring during solidification process, i.e. liquidus (TL) and solidus (TSol) temperatures and the beginning of phases and eutectic nucleation, were determined with the thermal-derivative analysis and calculation of total heat of crystallisation of the analysed material.

Solidification Characteristics of Mg-Li-Al Alloys

The six Mg-Li and Mg-Li-Al alloys in as-cast state namely Mg-4.5%Li, Mg-9%Li, Mg-12%Li, Mg-4.5%Li-1.5%Al, Mg-9%Li-1.5%Al and Mg-12%Li-1.5%Al were prepared and analysed. These alloys have been subjected to the thermal analysis (thermal derivative-analysis and dilatometry study), and the subsequent thermal assessment, mechanical properties and microstructures were studied. The heating and cooling dilatometric curves characterise by a linear reduction (alloys with 12wt.% of Li) and linear increase (alloys with 4.5wt.% of Li) in coefficient of linear thermal expansion as a function of temperature. No transitions in the solid state occur. Based on results of thermal derivative analysis a crystallisation process of Mg-Li and Mg-Li-Al alloys was proposed. Addition of aluminium in ultra-light Mg-Li alloys shows considerably improved strengthening without a reduction in grain size. Increasing the lithium content causes in an increase of hardness.

Heat Treatment of Al-Si-Cu Alloys

The aim of the presented work is an effort to answer the research questions, i.e. how to determine the optimal supersaturation temperature for multicomponent alloys? What is the relationship between changes in the derivative curve of composites and the relationship between their chemical composition and microstructure? Searching for the right answer to the above questions was the basis for determining the scope and methodology of the presented work. To describe the phenomena that occur in the material during solidification under various conditions caused by the variable cooling rate and variable chemical composition it was decided to use thermal-derivative analysis methods. The mentioned method allows to accurately describe and interpret the kinetics of the crystallization of the tested materials. This method is often used in the search for new directions of modern technologies, attractive from both experimental and cognitive. This methodology allows to determine the relationship between crystallization kinetics and usable casting properties on the example of Al-Si-Cu alloys and other alloying elements.

Effect of cooling rate on microstructural development in alloy ALMG9

The microstructure that is attributable from the distinct casting method dictates new engineering and physical attributes of the material. To understand how to manage the microstructure of the casts, it is necessary to comprehend the differences in microstructure through crystallisation. The effects of cooling rate (0.5, 0.9 and 2.1 °C s−1) on the characteristic parameters of the evaluation of aluminium dendrites in Al–Mg alloy during solidification at different cooling rates were investigated by thermal derivative analysis. Because of the facts that castability is influenced significantly by the dendrite coherency point, which represents the time, temperature, and solid fraction at which interlocking solid network forms through solidification, an increment in the solid fraction at coherency can improve the casting attributes of the material and diminish casting defects. Castability of aluminium is defined with a new approach based on one thermocouple thermal analysis technique of fraction solid at a dendrite coherency point. Changes of sample linear dimensions and the coefficient of linear thermal expansion and diagrams of this coefficient as a temperature function during heating and cooling cycle of investigated materials were registered and presented. The analysis shows that the thermal interpretation is carried out on Universal Metallurgical Simulator and Analyzer device which is a useful instrument for the accumulation and calculation of thermal parameters. The manuscript provides to the better understanding non-equilibrium metallurgical characterisation of aluminium alloys.

Refinement effect of RE in light weight Mg\u2013Li\u2013Al alloys

The effect of 2 mass% rare earth elements (RE) as in mischmetal state on the structure, thermal behaviour and mechanical properties of Mg–xLi–4Al (x = 4, 8 and 12 by mass percentage). The thermo-derivative analysis was implemented using the UMSA platform (Universal Metallurgical Simulator and Analyzer) with cooling rate approx. ≈ 0.6 °C s−1 that correspond to natural cooling. Microstructural evaluations were identified by X-ray diffraction, scanning electron microscopy, light microscope and energy-dispersive X-ray spectroscopy. Obtained results from the thermal derivative analysis allowed determining the solidification pathways for Mg–Li–Al–RE alloy. The addition of grain refinement causes changes in crystallisation process. The addition of RE elements affected an enhancement in mechanical properties, which was associated with the development of intermetallic compounds; the maximum increases in hardness at level 240% was observed for single α-phase alloy and at level 19% for α + β alloy.

Effect of grain refinements on the microstructure and thermal behaviour of Mg\u2013Li\u2013Al alloy

The light as-cast Mg–9Li–1.5Al alloys were manufactured and modified by 0.2 mass% Zr, commercial 0.2 mass% TiBor and 0.2 mass% AlSr master alloys. The thermal derivative analysis using UMSA platform was utilised to characterise a crystallisation process. Samples were heated up to 700 °C and then freely cooled down (~ 0.6 °C s−1) to ambient temperature in order to simulate the natural cooling of casts. Dilatometry study was used to identify changes in solid state. The relative elongation of unmodified and modified alloys was measured in the temperature range from 20 to 400 °C, with a heating rate 1.0 °C s−1. The effects of Zr, TiBor and AlSr content on the microstructure of analysed magnesium alloys were investigated. Evaluation of microstructure was identified by light microscope, scanning electron microscopy, X-ray diffraction and energy-dispersive X-ray spectroscopy. The results showed that the addition of TiBor reduced the grain size of Mg–9Li–1.5Al cast alloy from 930 to 530 µm, while the addition of AlSr master alloy reduced the grain size to 480 µm. Moreover, an addition of TiBor and AlSr simultaneously reduced the grain size to 430 µm. The addition of Zr causes a reduction in grain size to 630 μm. The addition of grain refinement causes changes in crystallisation process and variations in the coefficient of linear thermal expansion (CTE).

Mineralogical characteristics of Cretaceous-Tertiary kaolins of the Douala Sub-Basin, Cameroon

As a step in evaluating the quality of Cretaceous-Tertiary kaolins of the Douala Sub-Basin, their mineralogical characteristics were determined. The X-ray diffractometry technique was used to identify and quantify the mineral phases present in bulk and <2 μm fractions. Scanning electron microscopy was used to determine the micromorphology of <2 μm fractions kaolins. Thermal analyses (derivative thermal gravimetric analysis, thermal gravimetric analysis, and heat flow) were conducted to further characterise the kaolins. The main mineral phases present in the studied Cretaceous-Tertiary kaolins of the Douala Sub-Basin were kaolinite > smectite > illite, with mean values of 33.01 > 11.20 > 4.41 wt %; and 72.23 > 10.69 > 4.69 wt %, in bulk and <2 μm fractions, respectively. The kaolins, micromorphologically, consisted of pseudo-hexagonal and thin platy particles; swirl-textured particles; and books or stacks of kaolinite particles. Three main reactions occurred during heating of the kaolins: a low temperature endothermic reaction, observed between 48 and 109 °C; a second low temperature peak, observed between 223 and 285 °C; and a third endothermic peak was found between 469 and 531 °C. In addition, an exothermic reaction also occurred between 943 and 988 °C in some of the samples. The absence of primary minerals such as feldspars and micas in most of these kaolins is an indication of intensive weathering, probably due to the humid tropical climate of the region. The different morphologies suggested that these kaolins might have been transported. Therefore, a humid tropical climate was responsible for the formation of Cretaceous-Tertiary kaolins of the Douala Sub-Basin through intense weathering of surrounding volcanic and metamorphic rocks.

Investigation of Methylammonium Tin Strontium Bromide Perovskite Systems

The properties of methylammonium-tin-strontium bromide systems (CH3NH3Sn1-xSrxBr3, 0.0 ≤ x ≤ 0.1) were investigated. The X-ray diffraction analysis (XRD) revealed the presence of the untilted cubic Pm-3m perovskite and orthorhombic SnBr2 as major crystalline phases. The morphological analysis confirmed the XRD data by detecting the formation of polyhedral shaped crystallites attributed to MASnBr3 perovskite and elongated crystallites related to SnBr2 phase. Derivative differential thermal analysis (DDTA) and derivative thermogravimetric analysis (DTG) revealed a thermal stability of MASnBr3 phase till T = 250°C and showed the presence of more thermal events related to a multistep decomposition process. The addition of Sr-ions retained the cubic crystalline structure of the perovskite and enhanced its thermal stability at T = 150°C by reducing the weight loss rates. The optical spectra displayed values of absorption edges between 624 nm and 636 nm. The Tauc plots revealed a direct semiconducting behavior with band energy gaps at ∼2.02–2.03 eV. The emission photoluminescence (PL) spectra, measured at room temperature and excitation wavelength λexc = 380 nm as well as the excitation photoluminescence (PL) spectra, measured at room temperature and emission wavelength λem = 520 nm showed a dramatic increase of the intensity by adding the Sr-ions reaching a maximum for x = 0.025.

Thermal Assessment of Modified Ultra-Light Magnesium-Lithium Alloys

AbstractThe paper presents the results of the influence of commercial TiBor and AlSr10 master alloys on the refine the grains size, hardness and crystallisation process based on the thermal-derivation analysis of light cast magnesium-lithium-aluminium alloys. The effects of TiBor and AlSr10 content on the characteristic parameters of the crystallisation process of Mg-Li-Al alloys were investigated by thermal-derivative analysis (TDA). Microstructural evaluations were identified by light microscope, X-ray diffraction, scanning electron microscopy, and energy dispersive X-ray spectroscopy.The results showed that the addition of TiBor master alloy reduced the grain size of Mg-9Li-1.5Al cast alloy from 900 μm to 500 μm, while the addition of AlSr10 master alloy reduced the grain size of investigated cast alloy from 900 μm to 480 μm. Moreover, an addition of TiBor and AlSr10 simultaneously reduced the grain size from 900 μm to 430 μm.Results from the thermal-derivative analysis showed that the addition of grain refinement causes a decrease in nucleation temperature and solidus temperature.

The synthesis and the spectroscopic, thermal, and structural properties of the M2[(fumarate)Ni(CN)4]·2(1,4-Dioxane) clathrate (M = Co, Ni, Cd and Hg)

In this study, the clathrates of fumarate–tetracyanonickel–dioxane, given by the formula M2[(fumarate)Ni(CN)4]·2(1,4-Dioxane) (M = Co, Ni, Cd and Hg), have been obtained for the first time through chemical methods. These clathrates have been characterized by elemental, thermal, FT-IR, and FT-Raman spectroscopies. The parameters of structures of clathrates have been determined by X-ray powder diffraction. The thermal behaviors of these clathrates have been also investigated by thermo-gravimetric analysis (TGA), differential thermal analysis (DTA), and derivative thermal gravimetric analysis (DTG) in the range of 20–900 °C. X-ray powder diffraction data have been recorded at ambient temperature in the 2θ range 5–50°. The FT-IR and FT-Raman spectra of clathrates have been recorded in the region of 4000–400 cm−1 and 4000–100 cm−1, respectively.The results of the spectral and thermal analyses of the newly synthesized clathrates of fumarate–tetracyanonickel–dioxane suggest that these clathrates are new examples of the Hofmann–type dioxane clathrates. In our study, the Hofmann-type dioxane clathrates, which are formed by bounding electrons of oxygen–donor atoms of fumarate ion ligand molecule to transition metal atoms, consist of the corrugated |M–Ni(CN)4|∞ polymeric layers, which are held in parallel through the chain of (–M–fumarate–M–).

Synthesis, characterization, and thermal degradation of Cu (II) surfactants for sustainable green chemistry

The Cu (II) surfactantsof stearic and palmitic acids were synthesized which are greenish blue in colour and chosen for thermogravimetric and derivative thermal analysis. Their structure has been confirmed by elemental analysis, and mass spectroscopy. Thermogravimetric degradation of Cu (II) palmitate soap was studied for energy of activation. This shows that two step thermal degradation in the range of 423 K to 703 K. Various equations like coats-redfern (CR), horowitz-metzger (HM) and broido equations (BE) were applied to evaluate the energy of activation. Thermal degradation of solid components will be a good and significant method for the removal of the pollutant from the environment. The present study will play an important role for pollution controlling and in the field of green chemistry.

Experimental Research on Catalytic Combustion Characteristics of Inferior Coal and Sludge Mixture

Catalytic effects of metal oxides on combustion characteristics of inferior coal, sludge, and their mixture were investigated by thermogravimetric analysis. Combustion and thermal dynamic characteristics including ignition temperatures, apparent activation energy, and frequency factors of inferior coal, sludge, and their mixture were observed. The catalytic effects and mechanism of combustion were discussed. Results showed that thermal gravity analysis (TG) and derivative thermogravimetric analysis (DTG) curves of coal and sludge shifted to lower temperature side, the weight losses increased, and the ignition performance was improved with the addition of metal oxides CaO, Al2O3, and K2O. The combustion dynamics analysis showed that the apparent activation energy of cocombustion of coal blending sludge decreased by 11–20% and the frequency factors increased by 20–30%. The minimum apparent activation energy and the maximum frequency factors were obtained in the presence of K2O, indicating that the catalytic effect of K2O was most significant.

The Analysis of AISI A3 Type Ferritic-Austenitic Cast Steel Crystallization Mechanism

AbstractHigh-alloy corrosion-resistant ferritic-austenitic steels and cast steels are a group of high potential construction materials. This is evidenced by the development of new alloys both low alloys grades such as the ASTM 2101 series or high alloy like super or hyper duplex series 2507 or 2707 [1-5]. The potential of these materials is also presented by the increasing frequency of sintered components made both from duplex steel powders as well as mixtures of austenitic and ferritic steels [6, 7]. This article is a continuation of the problems presented in earlier works [5, 8, 9] and its inspiration were technological observed problems related to the production of duplex cast steel.The analyzed AISI A3 type cast steel is widely used in both wet exhaust gas desulphurisation systems in coal fired power plants as well as in aggressive working environments. Technological problems such as hot cracking presented in works [5, 8], with are effects of the rich chemical composition and phenomena occurring during crystallization, must be known to the technologists.The presented in this work phenomena which occur during the crystallization and cooling of ferritic-austenitic cast steel were investigated using numerical methods with use of the ThermoCalc and FactSage® software, as well with use of experimental thermal-derivative analysis.

Aromatic Polyamines Covalent Triazine Polymer as Sorbent for CO2 Adsorption

A novel aromatic polyamine covalent triazine-based polymer, CPDA was obtained by the polymerization of amino group (1,4-phenylenediamine) and cyanuric chloride. CPDA was characterized with Fourier Transform Infra-red spectroscopy (FTIR) and the thermal behaviour was studied with thermal gravimetric analysis (TGA) and derivative thermal analysis (DTA). A comparison study for CO2 adsorption capacity on covalent organic polymer 1 (COP-1) and CPDA was performed. By introducing the aromatic ring into the nitrogen fertile triazine based system, the thermal stability of the network is enhanced. Polymer structure containing secondary amine functionality was observed in this study. Besides, the suggested chemical pathway is another approach to synthesis of covalent organic materials using economic monomers and absence of expensive catalyst.

SiMo Ductile Iron Crystallization Process

Abstract The article presents crystallization process of silicon molybdenum ductile cast iron (SiMo). The alloy with 5% silicon content and with variable amounts of Mo in a range of 0-1% was chosen for the research. The carbon content in the analysed alloys did not exceed 3,1%. The studies of crystallization process were based on thermal - derivative analysis (TDA). Chemical composition of all examined samples was analysed with the use of LECO spectrometer. Additionally, the carbon and the sulphur content was determined basing on carbon and sulphur LECO analyser. For metallographic examination, the scanning electron microscopy (SEM) with EDS analyser was used. Disclosed phases have been also tested with the use of X-ray diffraction. The results allowed the description of crystallization processes of silicon molybdenum ductile cast iron using thermal - derivative analysis (TDA). Conducted studies did not allow for the clear identification of all complex phases containing molybdenum, occurring at the grain boundaries. Therefore, the further stages of the research could include the use of a transmission electron microscope to specify the description of complex compounds present in the alloy.

Hypoeutectic Al-Si Alloy with Cr, V and Mo to Pressure Die Casting

Abstract This paper presents the results of hypoeutectic 226 grade alloy as well as prepared on its basis Al-Si alloy containing Cr, V and Mo. The additives tested were added as AlCr15, AlV10 and AlMo8 master alloys. Alloys tested were poured into DTA sampler as well as using pressure die casting. An amount of Cr, V and Mo additives in alloy poured into DTA sampler comprised within the range approximately 0.05-0.35%. Alloys to pressure die casting contained 0.05-0.20% Cr, V and Mo. The crystallization process was examined using the derivative thermal analysis (DTA). The microstructure of castings made in the DTA sampler as well as castings made with use of pressure die casting were examined. The basic mechanical properties of castings made using pressure die casting were defined too. It has been shown in the DTA curves of Al-Si alloy containing approximately 0.30 and 0.35% Cr, Mo, and V there is an additional thermal effect probably caused by a peritectic crystallization of intermetallic phases containing the aforementioned additives. These phases have a morphology similar to the walled and a relatively large size. The analogous phases also occur in pressure die casting alloys containing 0.10% or more additions of Cr, V and Mo. The appearance of these phases in pressure die casting Al-Si alloys coincides with a decrease in the value of the tensile strength Rm and the elongation A. It has been shown die castings made of Al-Si alloys containing the aforementioned additives have a higher Rm and A than 226 alloy.

Development of a New ATD-P Tester for Hard Wear Resistant Materials

Abstract The aim of presented studies was to develop a new geometry of the overflow part of standard ATD-C tester for derivative thermal analysis in a way that it would allow to obtain samples for abrasion and mechanical properties tests in the same mould without the need of cutting them from a block of material. The pattern of new ATD-P tester has parts reflecting implemented samples. Computer simulations regarding initial verification of new tester were performed in NovaFlow software. Chromium cast iron melts were made for testing the sampler in real conditions and TDA analysis for casting material were conducted. The sandmix was prepared on silica sand matrix per the ALPHASET technology. This new solution greatly simplifies the preparations of materials difficult to machine.

1H-imidazol-3-ium tricyanomethanide {[HIM]C(CN)3} as a nanostructured molten salt catalyst: application to the synthesis of pyrano[4,3‐b]pyrans

In this work, we have synthesized a novel nanostructured molten salt, 1H-imidazol-3-ium tricyanomethanide {[HIMI]C(CN)3} (1), as an efficient and green protocol-compatible catalyst. This new molten salt has been fully characterized by different analytical techniques, such as FT-IR, 1HNMR, 13CNMR, thermal gravimetric analysis, derivative thermal gravimetric analysis, differential thermal analysis, X-ray diffraction, scanning electron microscopy, and high-resolution transmission electron microscopy. Additionally, the catalytic activity of {[HIMI]C(CN)3} (1, 2 mol%) has been tested in a three-component domino Knoevenagel condensation reaction. A range of structurally diverse aromatic aldehydes (2a–p), malononitrile (3), and 4‐hydroxy‐6‐methyl‐2H‐pyran‐2‐one (4) are tolerated for the synthesis of 2-amino-7-methyl-5-oxo-4-aryl-4,5-dihydropyrano[4,3-b]pyran-3-carbonitrile derivatives (5a–p) under neat conditions at 50 °C. The obtained results have demonstrated that catalyst 1 shows interesting catalytic properties, such as clean reaction profile, cost-effectiveness, and green conditions. Importantly, the aforementioned catalyst is thermally stable with a 171 °C melting point not showing any significant loss in catalytic activity after 7 reaction cycles.

Hypoeutectic Silumin to Pressure Die Casting with Vanadium and Tungsten

AbstractThe basic aim of this study is to investigate the effect of vanadium and tungsten on the crystallization process, microstructure and mechanical properties of silumin grade EN-AC 46000. The research involved a derivative thermal analysis DTA of the crystallization process, the metallographic analysis as well as the mechanical properties. The metallographic analysis was carried out on pressure die castings and made in the DTA probe. Vanadium and tungsten were added simultaneously to silumin in amount of approximately 0.1; 0.2; 0.3 and 0.4%. The DTA studies have shown the similar shape of all crystallization curves. It has been shown the additives of vanadium and tungsten in pressure die cast silumin can significantly increase its tensile strength as an well as elongation.