Derivative Thermal Analysis Research Articles

Sustainable lignocellulosic mediterranean biocomposites: Thermogravimetric analysis, mechanical performance, morphological and comparative study

Utilizing accessible agricultural waste to create sustainable materials is a potentially beneficial attempt toward developing better bio-products and a more sustainable socioeconomic environment. Accordingly, this work aims to investigate the mechanical performance enhancement and/or deteriorations as well as morphological and thermal characteristics of certain Mediterranean lignocellulosic fiber composites considering various reinforcement conditions. Several composites of polypropylene pomegranate peel powder (PG) and short corn leaves (CL) were designed and fabricated with various reinforcement conditions to demonstrate their potential characteristics. Moreover, the experimental results of this work were compared with commonly used fiber/PP composites worldwide to demonstrate their appropriateness for producing bio-based composites suitable for various applications. The investigations included determining the tensile strength, tensile modulus, elongations at break properties under various reinforcement conditions, as well as revealing the thermal properties of the fibers to expose their suitability for such bio-based composites to improve utilizing such available waste of fibers into useful materials for various mechanical components. Thermal gravimetric analysis (TGA) and derivative thermal gravimetric analysis (DTG) were also carried out to examine thermal stability and to distinguish the maximum degradation temperature (Tmax) of the cellulosic fiber compositions. The outcomes revealed that both types of fibers, pomegranate peel powder and short corn leaves, had positive impacts on the tensile strength and modulus of PP regardless of the weight percentage. The 40 wt% of corn leaves displayed the best improvement in the strength (+29 %) and modulus (+17 %). The 40 wt%, CL-PP reached tensile modulus of 1589.5 MPa, whereas the best modulus for the PG-PP was 1399.4 MPa at 30 wt%. When comparing the tensile strength and modulus of PG/PP and CL/PP composites with those reported in the literature, these composites demonstrated superior tensile properties relative to thirteen other types documented. Regarding the thermal analysis, PG and CL fibers could withstand the processing temperature without degradation, which enables them to be feasibly utilized in bio-based composites to enhance the development of green bio-products. When it comes to the morphological analysis, it was observed that there was a good adhesion between PP and CL, which interprets the enhancement tensile properties.

Напрями розвитку методології регулювання хімічного складу і властивостей чавуну в ливарному виробництві на базі ймовірнісного підходу

From the standpoint of systemic and structural-functional approaches, the state and prospects of development of the methodology for regulating and predicting the chemical composition and mechanical properties of grey synthetic cast iron intended for casting production are analysed. Attention is focused on the key intersections of the technological process of manufacturing castings for critical applications. The features, disadvantages, and advantages of the known methods for calculating the charge and adjusting the percentage of chemical elements in the cast iron composition directly during its melting are considered. Ways to take into account the instability of the chemical composition of scrap metal, ferroalloys, and other materials when forming the charge to ensure the quality of pig iron in accordance with the requirements of finished product standards are shown. A promising way to solve this problem in foundry is to use a probabilistic approach and the Monte Carlo method. The article presents formulas for calculating the strength and hardness of cast iron castings with lamellar graphite depending on its carbon equivalent and degree of eutecticity. The peculiarity of the proposed formulas, which gives them enhanced reliability and validity, is that the carbon equivalent and the degree of eutecticity of cast iron in them are determined by the Monte Carlo method using a probabilistic approach with regard to the consideration of the ranges of variation of the content of chemical elements in the cast iron composition regulated in the standard for foundry products. It is noted that the widespread use of thermal derivative express analysis of liquid cast iron in industry is constrained by the lack of a database of reference cooling curves with certain property indicators (chemical composition, microstructure, mechanical and other properties) of cast irons at foundries. Keywords: foundry, cast iron, chemical composition, properties, control, regulation, methodology.

ЭФФЕКТИВНОСТЬ ОГНЕЗАЩИТНЫХ ПРОПИТОЧНЫХ СОСТАВОВ ДЛЯ ДЕРЕВЯННЫХ КОНСТРУКЦИЙ

The article considers the results of evaluating the flame retardant effectiveness of various flame retardants by the method of fire exposure according to GOST 53292–2009 and by methods of thermal analysis (thermogravimetry, differential thermogravimetry, derivative thermal analysis). According to the results of fire of surface application of flame retardants from 350 to 550 kg/m2, group I or II of flame retardant
 efficiency is provided (mass loss from 8,67 to 25 %). It is shown that the group of flame-retardant effectiveness does not actually reflect the nature and degree of realization of the mechanism of flame retardant action of flame retardants, their ability to influence the features of thermal transformations of wood. It has been established that the type of flame retardant, its chemical component composition and the mechanism of flame retardant action to varying degrees affect the main stages of thermal oxidative decomposition of wood. The results obtained can be used to evaluate the effectiveness of fire protection in reducing the intensity of the charring process and predicting the intensity of smoldering (flameless) combustion of wood. tests, it was found that with the consumption

Calorimetric analysis of Mg–Li ultra light magnesium alloy

The Thermal-Derivative Analysis, or Computer-Aided Cooling Curve Analysis, is a commonly used method for determining the solidification parameters of metals and alloys. Knowledge of the enthalpy, kinetics and broad characteristics of the transformations taking place during the cooling of an alloy can be obtained with the proper configuration of analytical equipment and arrangement of test techniques. This work practically analyses the changes occurring in the Mg–4.5Li–1.5Al alloy as a result of the modification of the structure by the addition of TiB and Sr. The results indicate that adding grain refinements significantly affects the microstructure and thermal parameters of Mg–4.5Li–1.5Al alloy. The nucleation temperature and solidus temperature decrease with the addition of chemical reagents. Compressive strength improved due to the refinement of grain size. The results confirmed that thermal-derivative analysis is suitable for analysing changes in cast magnesium alloys.

Effect of eggshell powder on the microstructural and thermal behavior of Al7075/waste eggshell surface composites produced by solid-state friction stir processing developed for potential thermal applications

Lightweight composite materials for potential thermal applications are the contemporary demand for manufacturing and aircraft industries where the possibility to improve and tailor the desired properties is based on the application. Carbonized eggshell powder is a solid lubricant with absorbent capability and has proven as a reinforcement for metallic base composites. In the present work, an attempt is made to investigate the effect of carbonized chicken eggshell powder (3 to 9% by weight) on the microstructural and thermal properties of Al7075 alloy processed by solid-state friction stir processing. An infrared thermography and three K-type thermocouples equipped with the base plate at three equal distances are used to measure the temperature with respect to time. The comparative study of microstructure and grain structure analysis has been done by light microscopy, scanning electron microscopy, and electron backscattered diffraction methods. The findings explored the dynamic recrystallization and grain recovery with a reduced grain size of 6.2 to 10.3 µm at a varying percentage of eggshell powder (3 to 9%) in the stir zone. The thermal conductivity and coefficient of thermal expansion (CTE) were measured for the temperature range of 50 to 400 °C. In addition to it, differential thermal analysis (DTA), thermo-gravimetric analysis (TGA), and derivative thermo-gravimetric analysis (DTG) are conducted for the temperature range of 25 to 900 °C to discuss the endothermic, exothermic nature, and degradation characteristics. The result revealed the decreasing trend of thermal conductivity, and CTE values were found in the range of 97 to 53 W/mK and 26.6 to 24 × 10−6 K−1 (heating cycle), 27.2 to 23.8 × 10−6 K−1(cooling cycle), respectively. Furthermore, the higher and lower thermal conductivity of 108 W/mK and 62 W/mK is observed at higher and lower terminal voltages, 250 V and 100 V, respectively. The DTA, TGA, and DTG curves explored the maximum weight loss, which varies up to 5.25% with exothermic peaks and decomposition steps for each surface composite.

Enhanced Mechanical and Durability Properties of Cement Mortar by Using Alumina Nanocoating on Carbon Nanofibers.

This study evaluated the effect of carbon nanofibers (CNFs) coated by aluminum oxide Al2O3 as a reinforcement on compressive strength, frost resistance, and drying shrinkage of cement mortars. Three weight ratios of 0.125%, 0.25%, and 0.5% of Al2O3/CNFs and bare CNF cement mortars were compared with reference cement mortar samples. The reactive porous and high surface area layer of alumina induced the hydration reaction and promoted the production of well-distributed hydration gel. Derivative thermal analysis–differential thermogravimetric (TGA-DTG) and X-ray powder diffraction (XRD) characterization showed that Al2O3/CNFs reinforcement led to greater hydration gel production than bare CNFs. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) were performed to study the coating and microstructure of the cement mortars evaluated in this paper. The results show that the optimum enhancement of the cement mortar properties was obtained at ratios of 0.125% for Al2O3/CNFs and 0.25% for CNFs. This enhancement was greater with Al2O3/CNFs-reinforced specimens in terms of high compressive strength, less compressive strength degradation after 150 cycles, and less drying shrinkage. The low use of the CNFs in Al2O3/CNFs samples indicates the coating is an economical and promising approach for improving the performance of cement mortars.

Synthesis of biopolymer chitosan-based hydrogels with and without a crosslinker for the removal of industrial dye procion blue HERD: a comparative study

ABSTRACT The current study reports the preparation and application of bio-based polymer composite hydrogel with and without a crosslinker for the removal of industrial dye procion blue HERD (PB). Biopolymer chitosan, acrylic acid as a monomer and potassium persulphate (K2S2O8) as an initiator synthesise composite hydrogel. The crosslinked composite hydrogel is synthesised by the microwave irradiation technique using thiourea (CH4N2S) as a crosslinker. Chitosan-based hydrogel synthesised without crosslinker (CH) and with crosslinker thiourea (CH-T) is analysed using techniques, such as Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), differential thermal analysis (DTG) and derivative thermogravimetric analysis (DTA). The adsorption capacity of CH and CH-T for the removal of PB from an aqueous solution is investigated. The removal efficiency of hydrogel is 90% in a solution of pH 7 for a constant dose of PB (5 mg L−1). The experimental data attained for the adsorption of industrial dye (PB) onto CH and CH-T showed a perfect fit for Freundlich and Langmuir isotherms. The perfect fit of experimental data for PB decolorisation is observed for pseudo-second-order kinetic equation with k values 10.17 × 10−3 mg−1 min−1 and 6.719 × 10−3 mg−1 min−1 with CH and CH-T, respectively.

The Importance of TDA Thermal Analysis in an Automated Metallurgical Process

The article presents the results of research and work related to the implementation of the research and development project POIR.01.01.01-00-0120/17 co-financed by the EU, through the NCBR, entitled: Innovative technology using thermal analysis, TDA, of self-feeding manufacturing of high-quality cast iron to produce new generation, enhanced performance casts. In many foundries, thermal derivative analysis (TDA) is used in addition to chemical analysis to evaluate the physical and chemical properties of an alloy while it is still in the melting furnace or ladle and before it is poured into the mold. This fact makes it possible to improve the metallurgical quality of the alloy by introducing alloying additives, carburizers or modifiers into the furnace as part of the pre-modification or primary or secondary modification in the ladle or when pouring into molds. Foundry machinery (modifier dosing systems and spheroidizing station) is very important in these operations. Only the full synergy of modern equipment with modern technology ensures high quality and repeatability of the casting process. The article mainly discusses the obtained parameters of TDA analysis (with the use of the ITACA system) at different stages of melting and how to improve them by using modern and fully automated dosing systems (Itaca OptiDose, ItacaWire and ItacaStream). Special attention was paid to the minimum temperature of the eutectoid. The change of its value after the modification process, its influence on the quality of the melted metal, a very strong correlation with the number of nuclei and the number of graphite precipitations in the casts were shown.

Crystallization kinetics and microstructural analysis of lanthanum-modified zinc alloys

The development of functional engineering materials based on non-ferrous metals has progressed in recent years, and the incorporation of rare earth metals is a key strategy aimed at modifying the structural components of alloys to enhance their mechanical properties. The work presented herein investigates the effect of lanthanum addition on the microstructure and type of phases formed during crystallization. The effects of alloying elements on the solidification derivative curve and the monotectoid solid-state transformation of ZnAl10Cu1 alloys are also discussed. The overall impact of lanthanum addition was determined based on studies of the microstructure morphology, phase composition, and changes in the derivation curves of the studied alloys. Optical microscopy, scanning electron microscopy, and transmission electron microscopy were employed for structural analysis, and thermal-derivative analysis (TDA) was used to investigate the phenomena occurring during solidification in hypereutectic zinc alloys with various chemical compositions The results of this study indicate that the addition of La modifies the derivation curve during solidification by changing the morphology of the α phase and decreasing the monotectoid transformation temperature (α→α’). The presence of the Zn5La phase in the a′ + η eutectics was also confirmed.

Investigation on the thermal behaviour of AZ31B/waste eggshell surface composites produced by friction stir processing

The increasing demand for low-cost reinforcements emboldens the use of waste byproducts such as chicken eggshells. The chemical composition of the waste eggshell (contains 95% CaCo3) with low density, high hardness, high melting point and its easiest availability makes it a suitable alternative reinforcement to use in the metal matrix composites (MMCs). In this work, the ball-milled and carbonized waste chicken eggshell powder is used to develop the surface composites of magnesium alloy by friction stir processing. Developed material was validated by microscopic images of stir zone, thermomechanical affected zone, heat-affected zone and structural analysis by X-ray diffraction. The material is thermally characterized by thermal conductivity at varying temperatures (50 °C–400 °C) and varying terminal voltage (100 V–250 V), coefficient of thermal expansion along with differential thermal analysis, thermo-gravimetric analysis and derivative thermo-gravimetric analysis. The results revealed the decreasing trend of thermal conductivity and coefficient of thermal expansion, found in the range of 96 to 48 W/mK and 28.92 to 23.5 × 10-6 K-1, respectively at an increasing temperature from 50 °C to 400 °C and at increasing eggshell powder percentage.

Experimental Investigation of Fast Pyrolysis of Isoberlina doka-Derived Sawdust for Bio-Oil Production

Fast pyrolysis is considered an emerging technology for biomass conversion into liquid oil. In this paper, the conversion of waste from Isoberlina doka tree processing into bio-oil using a bench-scale fixed bed reactor with a fluidized behavior within the bed zone has been investigated at temperatures of 400–500 °C and particle size ranges of < 0.5 and 0.5–1 mm. Reactor with the total height of 140 mm consisting of three zones with gas inlet diameter of 10 mm, reaction zone diameter of 70 mm, outlet diameter of 15 mm and a coupled detachable inlet with a diameter 15 mm for biomass loading was used for experimentation. Nitrogen was used as the carrier gas, and the products were biochar, bio-oil and non-condensable gas. Thermogravimetric and derivative thermal analysis (TG/DTA) was carried out in order to understand the thermal behavior of wood particles. Bio-oil produced was analyzed using the gas chromatography mass spectrometry and the Fourier transform infra-red spectrophotometry methodologies. TG/DTA analysis revealed an initial 30.639% mass loss which correlates to hardwood thermal characteristics. Bio-oil yield from bench-scale pyrolysis increased with increasing temperature. A maximum bio-oil yield of 49.84 wt % was observed at the particle size range of 0.5–1 mm, bed temperature of 500 °C and time of 30 min. Volatile generation was at the peak of 54.54% (0.002655 kg/min). However, changes in the chemical composition and functional groups of bio-oil with temperature of production suited it for different usage purposes.

Investigation of the Effect of Diisocyanate on the Thermal Degradation Behavior and Degradation Kinetics of Polyether-Based Polyurethanes

Low molecular weight polyether (PE) or polyester polyols can produce novel elastomeric urethane products when cured with diisocyanate which are then utilized for formation of castable energetic composites in addition to many more applications. In this work four different kinds of diisocyanates, isophorone diisocyanate (IPDI), methylenediphenyl diisocyanate (MDI), 2,2,4-trimethyl hexamethylene diisocyanate (TMDI), and toluene diisocyanate (TDI), were used to react with a PE to form PE-based polyurethanes (PUs); they were denoted PE/IPDI, PE/MDI, PE/TMDI, and PE/TDI, respectively. The effect of the four diisocyanate groups in the PE-based PUs on the thermal degradation behavior, thermal degradation kinetics, reaction model, and thermodynamic parameters of the PE/IPDI, PE/MDI, PE/TMDI, and PE/TDI samples were investigated by thermogravimetric analysis (TGA) and derivative thermal gravimetric analysis (DTGA) methods. On the basis of the degradation peak temperature at a high heating rate, the thermal stability of the PU followed the order PE/TDI > PE/TMDI > PE/MDI > PE/IPDI. The activation energy for the thermal degradation was derived using the Flynn–Wall–Ozawa (FWO) method from the TGA data and the average values of the PE/IPDI, PE/MDI, PE/TMDI, and PE/TDI samples were found to be 136.9, 148.0, 132.3, and 155.7 kJ mol‒1, each at various conversions from 0.05 to 0.95, respectively. In addition, the results of the activation energies obtained from the Kissinger–Akahira–Sunnse (KAS) method were in good agreement and consistent with those obtained the FWO method. The reaction models of the degradation reaction were investigated through the Coats–Redfern method and all PUs samples were probably best described by the Avarami–Erofeyev (A 2) and reaction order (F 1) models. The kinetic and thermodynamic parameters for formation of the activated complex of all PUs, such as the activation energy (Ea ), enthalpy of activation (ΔH #), Gibbs free energy of activation (ΔG #), and entropy of activation (ΔS #), were investigated. The investigated thermal kinetic and thermodynamic parameters indicated that there was significant variation in the properties of the PUs containing the different diisocyanate groups.

Catalytic thermolysis treatment of petroleum refinery wastewater collected from effluent treatment plant

AbstractCatalytic thermolysis of petroleum refinery wastewater was investigated as a pretreatment process. Effects of various parameters like temperature, pH, dose of catalyst and time were investigated for chemical oxygen demand (COD), turbidity, and element reduction. CuSO4, FeSO4, FeCl3, and 1:1 ratio (v:v) mixture of CuSO4 and FeCl3 were used as a catalyst. The maximum reduction of COD and turbidity were 90 and 98% by mixture (1:1) of CuSO4 and FeCl3 at 70 °C, 7 pH, 1.0 kg/m3 dose in 90 min reaction time. The removal of an element like Cr, Mn, Ni, and Pb was analyzed by ICP-OES. The sludge precipitated after catalytic thermolysis was characterized using scanning electron microscopy with energy dispersive X-ray analysis (SEM-EDX), Fourier transform infrared (FTIR) and thermo-gravimetric analysis (TGA)/derivative thermal analysis (DTA) analyses. Sludge from CuSO4 and mixture of CuSO4 and FeCl3 treatment has a compact structure with irregular granule which favors adsorption.

Correction to: 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.

Experimental Response of Nonwoven Waste Cellulose Fabric–Reinforced Epoxy Composites for High Toughness and Coating Applications

Abstract In this article, the authors have fabricated (using the manual hand lay-up method) and characterized in detail the nonwoven waste cellulose fabric (with varying weight percentages of 0, 7, 9, and 11) reinforced epoxy resin composites. The methodology to develop in conjunction with various physical (density, water absorption, and thickness swelling), mechanical (tensile, compression, flexural, hardness, and impact), thermal (differential thermal analysis, thermogravimetric analysis, and derivative thermogravimetric analysis), morphological (scanning electron microscopy and X-ray diffraction), and electrical characterization tests were performed to give complete insight into the mechanics of epoxy fabric laminates. It was predicted from these tests that with an increasing weight percentage of fabric, most of the mechanical properties improved and were complemented through the microstructural morphological tests. Enhanced mechanical strength and thermal stability of the developed composite (relative to the neat epoxy resin) pave its way for high toughness and coating applications in various engineering fields.

Facile synthesis and characterization of nanocellulose from Zea mays husk

AbstractIn present work, agricultural residue Zea mays husk has been converted into cellulose using alkali and bleaching treatment. Further, the cellulose has been converted to nanocellulose through the acid hydrolysis method followed by ultrasonication. The Crystallinity and functional group analysis was studied using X‐ray diffraction (XRD) and Fourier‐transform infrared spectroscopy (FT‐IR), respectively. The surface morphological investigation of prepared Zea mays husk nanocellulose was carried out using scanning electron microscope (SEM) transmission electron microscope (TEM), and atomic force microscopy (AFM). The thermal stability was investigated using thermogravimetric and derivative thermal analysis (TGA/DTA). The obtained results revealed semi‐crystallinity nature, good thermal stability, and fibrous nanocellulose nature with agglomeration.

Effect of Mg addition on the crystallization kinetics of Zn-Al-Cu alloys

In this work, the main aim was to determine the effect of Mg addition on the crystallization kinetics and microstructure of Zn-10Al-1Cu alloy. The effectiveness of magnesium addition was detected on the basis of microstructure morphology investigations and changes occurring in the cooling curves of the investigated alloys. To describe the phenomena that occurred in the material during solidification under various conditions caused by a change in the chemical composition as a result of the appliance of modifiers, it was decided to use methods of thermal derivative analysis, allowing to effectively and accurately describe the crystallization kinetics of the tested materials. The scientific goal of the presented work was examination of the impact of magnesium addition and effect of the crystallization kinetics on the examined alloys. Determining the relationship between the changes in the derivative curve and the related microstructure, the influence of modifiers addition was analysed. The addition of Mg caused a shift of the solidification temperature values of phases and eutectics and monotectoid transformation (????) to lower temperature values, as well as the change of the morphology of the occurring eutectic ??+?.

Magnesium\u2013lithium alloys with TiB and Sr additions

The ultralight hypoeutectic α-phase Mg–4.5Li–1.5Al alloy and hypereutectic β-phase Mg–12Li–1.5Al alloy in as-cast state were fabricated and subjected to modification by 0.2 mass% TiB and 0.2 mass% Sr grain modifiers. The crystallisation sequence of Mg–Li–Al alloys has been investigated in detail by using thermal-derivative analysis and microstructural observations. The presented work includes the effects of grain refiners on grain size and microstructure and thermal events registered during crystallisation of ultralight Mg–Li–Al alloys by recording and analysis of the temperature vs time, i.e. as TN, Tα, Tβ, Tη(LiAl) and TSOL. Microstructure and phase observation has been done by light microscope, X-ray diffraction and energy dispersive X-ray spectroscopy. The changes of characteristic temperature points for phase transformation are studied in detail. Due to the addition of 0.2 mass% TiB and 0.2 mass% Sr, the grain structure of the alloy was refined, and mechanical properties were improved. When a TiB and Sr added simultaneously, the average grain size of the analysed alloys strongly decreases. When the TiB or Sr content was severally added, a low effect of improvements of mechanical properties was observed. With the TiB and Sr content, the liquidus and solidus decrease gradually.

Influence of Ti and REE on Primary Crystallization and Wear Resistance of Chromium Cast Iron

The article presents the results of primary crystallization, wear resistance and SEM studies of chromium cast iron inoculated with ferrotitanium and rare earth elements as a mischmetal inoculating mixture. Thermal-derivative analysis method was used to conduct studies of primary crystallization in two types of testers, namely ATD-C and ATD-Is, reflecting two different cooling speeds. Wear resistance tests were performed with the use of modified pin-on-disk method on Tribotester 3-POD device, where the samples were moving in circular motion in metal-mineral friction system. Silicon carbide was used as a counter sample. The studies allowed to determine the influence of selected inoculants on the microstructure and wear resistance of the studied samples. All characteristic crystallization temperatures of samples casted into ATD-Is testers increased, as well as wear resistance of each inoculated samples compared to the non-inoculated sample. It was proven that TiC and REE compounds are effective inoculants for chromium carbides and that REE compounds can work as underlay for TiC crystallization.

Effect of Re addition on the crystallization, heat treatment and structure of the Cu\u2013Ni\u2013Si-Cr alloy

For determination of the structure and properties of those alloys, the following investigations were carried out: scanning microscopy and EDS X-ray analysis. Investigations concerning the optimal chemical composition and production method of Cu–Ni–Si alloys modified by Cr and Re as well as the improved properties in comparison with traditional alloys contribute to better understanding of mechanisms influencing the improvement of mechanical properties of the newly developed alloys. Thermal analysis of the crystallization process allows for accurate calculation of latent heat of various phases developed during solidification. Based on the assumption that the latent crystallization heat is proportional to the share of various phases in the alloy, the thermo-derivative analysis also allows the calculation of the amount of crystallized phases. Calculation of the properties as mentioned earlier is based on the characteristic points determined in a derivative curve. The adequately selected chemical composition of the alloy, as well as the appropriate cooling rate and heat treatment conditions, leads to improvement of functional properties of manufactured elements. For the analysed alloys, a thermal derivative analysis was used to determine the kinetics of crystallization and the temperature of the beginning and the end of a phase and eutectic crystallization, mainly the liquidus temperature (TL) and solidus temperature (TSOL). The TSOL temperature determined on thermal derivative analysis is the upper limit of supersaturation of the tested alloys. The conductivity and microhardness of the tested alloys were also measured in the function of the chemical composition and the state (i.e., heat treatment).