Papers by Keyword: Melting Temperature

Abstract: This paper reports melting temperature depression (MPD) for nano particle using different melting models reported in the literature such as: Liquid drop model, Surface phonon instability model, Gibbs Thomson equation, and Semi-empirical model etc. Reduced particle size is associated with a significant decrease of melting temperature. For bigger nanoparticles of all forms taken into consideration, the behaviour of melting temperature is identical, while for small nanoparticles, it differs dramatically. The effect of the shapes on melting point during the depression of nano particles has also been calculated for different shapes like film, icosahedron, wire, spherical, hexahedron, octahedron and tetrahedron. It has been discovered that the shape of the particle affects the lead, silver, gold, and aluminum nanoparticles' melting temperatures. Melting temperature depression is found to be lowest for tetrahedron-shaped nanoparticles and largest for thin films.

Abstract: This research aims to identify the optimal condition of the zinc Zamak3 alloys' melting process using 2k full factorial design and its optimizer in Minitab 18 software. The evaluation results of the ANOVA test with a first-order model revealed that the change in both independent variables simultaneously resulted in a statistically significant alteration of the percentage of slag. The independent parameters also had an effect individually on the response. Additionally, the slag percentage reduction was increased significantly due to an elevation of the temperature. However, the change of flux type resulted in an overall alteration of the slag percentage more than the change of melting temperature. The response optimizer demonstrated that the optimal condition was the melting temperature of 500°C coupled with the ZinCrex EP7119 flux achieving the lowest slag percentage of 1.672%, with the 95% confidence interval ranging from 0.643% to 2.701%.

Abstract: We investigated the relationship of the vacancy formation energy with kinematic viscosity and self-diffusion coefficient in liquid metals at the melting temperature. Formulas are obtained that relate experimental values of the vacancy formation energy, kinematic viscosity, and self-diffusion coefficient to the atomic size and mass, the melting and Debye temperatures. The viscosity and self-diffusion parameters are introduced. The ratio of these parameters to vacancy formation energy is equal to dimensionless constants. It is shown that the formulas for viscosity and self-diffusion differ only in dimensionless constants; the values of these constants are calculated. Linear regression analysis was carried out and formulas with the highest adjusted coefficient of determination were identified. The calculated values of the self-diffusion coefficient for a large number of liquid metals are presented.

Abstract: The potential of using paraffin deposits as natural insulation of the internal surface of oil pipelines in the permafrost zone has been considered. Paraffin deposits have been collected from the surface of oil field equipment in the Irelyakhskoye gas and oil field (Sakha Republic (Yakutia). The method of differential scanning calorimetry has been applied for study of phase transformation of commercial paraffins in the composite solvents based on gas condensate (GC) that is currently used for removal of paraffin deposits in this field, and in the composite solvents based on n-undecane (n-C11), as a model of the gasoline fraction of condensate. Binary and ternary composites based on gas condensate and n-undecane represent compositions with cyclohexane and p-xylene. The degree of crystallinity (DC) of paraffins has been determined to depend on the degree of aliphaticity of used composite solvents – as the degree of aliphaticity of solvents increases, DC of paraffins decreases. It has been identified that paraffins in ternary solvents based on GC and on n-C11 have low DC and high melting points. The results of research allow us to recommend paraffin deposits in ternary solvents obtained from GC as a promising raw material for thermal insulation of pipelines through targeted paraffinization, thus reducing a heat loss to the surroundings from oil and avoiding soil thawing and destruction in the permafrost area.

Abstract: Since the implementation of RoHS in avoidance to useof lead in electronic packaging, the development of lead-free solder has become priority. However, some of the potential candidates for lead-free solder have weaknesses such as slightly higher of melting point, excessive of intermetallic growth (IMC) and uncertainty service reliability that need to overcome. One of the common methods used to improve the characteristic and properties of the lead-free solder is by the addition of another alloying element. One of the promising alloying elements is bismuth (Bi). A few researchers have found out that Bi has a capability to improve the microstructure, reduce the melting temperature and controlled the IMC growth, yet, its advantageous is believed have not been thoroughly explored. Influence of (Bi) in lead-free solder alloys give interest to be studied and understand from different perspective due to its capability to improve the wettability and solder spread, and also reduce the melting temperatures of the solder. In this paper, a review on influence of Bi inSn-based lead-free solder and its advantageous were discussed.

Abstract: This article presents an investigation on phase equilibria of barium hexaferrite and neighboring phases near its melting point and on the characteristics of the compounds in the vicinity of BaFe₁₂O₁₉ phase. Fe₃O₄, BaFe₂²⁺Fe₁₆³⁺O₂₇ (W type), BaFe²⁺Fe₁₄³⁺O₂₃ (X type), BaFe₁₂O₁₉ (M type), Ba₂Fe₂2+Fe₁₂3+O₂₂ (Y type), Ba₃Fe₂²⁺Fe₂₄³⁺O₄₁ (Z type) and BaFe₂O₄ (S type) were detected in the molten and solidified stoichiometric BaFe₁₂O₁₉. Literature data are summarized and compared with results of the present work.

Abstract: Empirical Electron Theory in Solids and Molecules (EET) was used to analyze the valence electron structure of ZrTiHfVNb, ZrTiHfVTa and ZrTiHfNbMo high-entropy alloys. The parameters characterizing the valence electron structure of high-entropy alloys were calculated, which were used to discuss the hardness and melting temperature of high-entropy alloys. The results show that the hardness of high-entropy alloys is positively correlated to the shared electron pair number in valence electron structure. The theoretical melting temperatures of high-entropy alloys were predicted by the parameters characterizing the valence electron structure.

Abstract: In this paper the systematized literature data about the PbO-Fe₂O₃ system and new experimental results are presented. Based on the analysis of EDX, DTA and PXRD data on a series of compositions from 5 to 85 mol % PbO, the phase diagram of the PbO-Fe₂O₃ system was updated. Using the obtained data and the data of other authors thermodynamic functions were optimized and the thermodynamic modeling of the phase equilibria in the system was performed, results of which are presented in the form of the PbO-Fe₂O₃ phase diagram.

Abstract: This paper presents the results of synthesis of BaO-Fe₂O₃ system compounds. The powder X-ray diffraction patterns are presented. The patterns of Ba₃Fe₂O₆, Ba₂Fe₂O₅ and BaFe₂O₄ coincide with literature data. The experimental cell parameters were calculated. The study results of nature and the melting temperatures of Ba₃Fe₂O₆, Ba₇Fe₄O₁₃, Ba₂Fe₂O₅, BaFe₂O₄ are described. The compounds have congruent melting character. The melting temperatures of listed compounds are 1325, 1320, 1365, 1405 °C (1598, 1593, 1638, 1678 K), respectively.

Abstract: The aim of work consist in the investigation of the influence of alloying elements in ZnAl5 alloy on thermal and mechanical properties. The ZnAl5Cu (1-3), ZnAl5Mg (1-3), ZnAl5Ag (1-5) and ZnAl5In1(Ga1) solder alloys were used experiments. Solders were assessed by DSC analysis and by measuring tensile strength and Vickers hardness. It was found out that by adding of alloying elements, the melting temperature is decreasing. The opposite was observed in the case of ZnAl5Mg (1-3) alloys. By adding of In or Ga to ZnAl5, tensile strength and Vickers hardness are decreasing. Addition of Ag (1-5) resulted in increasing of tensile strength and Vickers hardness. In case of ZnAl5Cu (1-3) and ZnAl5Mg (1-3) solder, decreasing of tensile strength and increasing of Vickers hardness was observed.