Thermodynamics Of Metals Research Articles

Numerical investigations of arc plasma characteristic parameters evolution and metal properties in GMAW-based WAAM of Al alloy with an integrated model

Understanding the arc plasma characteristic parameters evolution and the metal thermodynamics is of great significance for guiding the improvement of the forming accuracy and performance of GMAW-based WAAM in engineering. In this study, we have developed a three-dimensional arc plasma-droplet-molten pool integrated model of GMAW-based WAAM of Al alloy, which simultaneously includes the heating of arc plasma, the vaporization of Al metal, the transfer of droplet, the melting and solidification of molten pool, and the relative motion between wire and substrate. Based on this sophisticated model, the effect of Al vapor on the arc plasma characteristics, the dynamic evolution of arc plasma characteristics during the metal transfer process, and the heat transfer and flow behaviors of liquid metal are comprehensively investigated. The simulation results show that the Al vapor is principally generated from the surface of droplet, which leads to the decrease of arc plasma temperature and arc pressure, and the expansion of current path. In a droplet transfer cycle, the average temperature of plasma decreases first and then increases, affected by the distribution of current density. Most of heat for the formation of molten pool comes from the energy transfer of droplet, and the droplet impact effect on the molten pool flow is significantly greater than Marangoni effect. Finally, the simulation results, including droplet transfer process and deposited layer profile, are validated by experimentally measured results, which are in good agreement with each other.

Understanding the biogeochemical mechanisms of metal removal from acid mine drainage with a subsurface limestone bed at the Motokura Mine, Japan

Subsurface limestone beds (SLBs) are used as a passive treatment technique to remove toxic metals from acid mine drainage (AMD). In this study, we investigated the mechanisms and thermodynamics of metal (manganese, copper, zinc, cadmium, and lead) precipitation in the SLB installed at the Motokura Mine. Field surveys in 2017 and 2018 showed that the pH of the SLB influent (initially 5–6) increased to approximately 8 in the drain between 24 and 45 m from the inlet. This increase was caused by limestone dissolution and resulted in the precipitation of hydroxides and/or carbonates of copper, zinc, and lead, as expected from theoretical calculations. Manganese and cadmium were removed within a pH range of approximately 7–8, which was lower than the pH at which they normally precipitate as hydroxides (pH 9–10). X-ray absorption near-edge structure analysis of the sediment indicated that δ-MnO2, which has a high cation-exchange capacity, was the predominant tetravalent manganese compound in the SLB rather than trivalent compound (MnOOH). Biological analysis indicates that microorganism activity of the manganese-oxidizing bacteria in the SLB provided an opportunity for δ-MnO2 formation, after which cadmium was removed by surface complexation with MnO2 (≡ MnOH0 + Cd2+ ⇄ ≡ MnOCd+ + H+). These findings show that biological agents contributed to the precipitation of manganese and cadmium in the SLB, and suggest that their utilization could enhance the removal performance of the SLB.

An introduction to materials engineering and science for chemical and materials engineers

Preface. Acknowledgments. 1 The Structure of Materials. 1.0 Introduction and Objectives. 1.1 Structure of Metals and Alloys. 1.2 Structure of Ceramics and Glasses. 1.3 Structure of Polymers. 1.4 Structure of Composites. 1.5 Structure of Biologics. References. Problems. 2 Thermodynamics of Condensed Phases. 2.0 Introduction and Objectives. 2.1 Thermodynamics of Metals and Alloys. 2.2 Thermodynamics of Ceramics and Glasses. 2.3 Thermodynamics of Polymers. 2.4 Thermodynamics of Composites. 2.5 Thermodynamics of Biologics. References. Problems. 3 Kinetic Processes in Materials. 3.0 Introduction and Objectives. 3.1 Kinetic Processes in Metals and Alloys. 3.2 Kinetic Processes in Ceramics and Glasses. 3.3 Kinetic Processes in Polymers. 3.4 Kinetic Processes in Composites. 3.5 Kinetic Processes in Biologics. References. Problems. 4 Transport Properties of Materials. 4.0 Introduction and Objectives. 4.1 Momentum Transport Properties of Materials. 4.2 Heat Transport Properties of Materials. 4.3 Mass Transport Properties of Materials. References. Problems. 5 Mechanics of Materials. 5.0 Introduction and Objectives. 5.1 Mechanics of Metals and Alloys. 5.2 Mechanics of Ceramics and Glasses. 5.3 Mechanics of Polymers. 5.4 Mechanics of Composites. 5.5 Mechanics of Biologics. References. Problems. 6 Electrical, Magnetic, and Optical Properties of Materials. 6.1 Electrical Properties of Materials. 6.2 Magnetic Properties of Materials. 6.3 Optical Properties of Materials. References. Problems. 7 Processing of Materials. 7.0 Introduction. 7.1 Processing of Metals and Alloys. 7.2 Processing of Ceramics and Glasses. 7.3 Processing of Polymers. 7.4 Processing of Composites. 7.5 Processing of Biologics. References. Problems. 8 Case Studies in Materials Selection. 8.0 Introduction and Objectives. 8.1 Selection of Metals for a Compressed Air Tank. 8.2 Selection of Ceramic Piping for Coal Slurries in a Coal Liquefaction Plant. 8.3 Selection of Polymers for Packaging. 8.4 Selection of a Composite for an Automotive Drive Shaft. 8.5 Selection of Materials as Tooth Coatings. References. Problems. Appendix 1: Energy Values for Single Bonds. Appendix 2: Structure of Some Common Polymers. Appendix 3: Composition of Common Alloys. Appendix 4: Surface and Interfacial Energies. Appendix 5: Thermal Conductivities of Selected Materials. Appendix 6: Diffusivities in Selected Systems. Appendix 7: Mechanical Properties of Selected Materials. Appendix 8: Electrical Conductivity of Selected Materials. Appendix 9: Refractive Index of Selected Materials. Answers to Selected Problems. Index. Sections marked with an asterisk can be omitted in an introductory course.

ChemInform Abstract: Thermodynamics of Metal ‐ Ligand Bond Formation. Part 33. The Effects of Electron‐withdrawing Groups on the Lewis Acidity of Copper(II) Complexes.

AbstractDie thermodynamischen Daten der 1:1‐Adduktbildung von 4‐Methylpyridin mit den Komplexen (I), von Tributylphosphat, DMSO und Trioctylphosphinoxid mit (Ic) und von Pyridin sowie 2‐ und 4‐Methylpyridin mit (II) werden in Benzol bei 30°C bestimmt.

On the accuracy of the liquid theory approximate methods for the description of liquid metal thermodynamics

The accuracy of the various liquid theory methods for calculating the thermodynamic properties of liquid metals is investigated. The calculations have been made for liquid Na, Rb, Mg and Al over wide ranges of temperature T and density n using (i) the variational method and hard-sphere reference system (the HSV method), (ii) the Barker-Henderson (BH) method, (iii) the Weeks-Chandler-Andersen (WCA) method and (iv) the expressions for energy and pressure in terms of the radial distribution function found in the Percus-Yevick approximation (the PYEP method). The results of the calculations are compared with each other and with experiment. The pseudopotential model is used which describes all the atomic properties of the alkali metals to a high precision, those of Mg rather well, and of Al fairly well. It has been shown that the simple HSV approximation suitable for a semi-quantitative description of the liquid metal properties is insufficient for quantitative calculations of differential characteristics, such as melting temperatures, entropies of fusion, entropies of liquid alloy mixing, etc. The PYEP and BH methods allow the authors to calculate some thermodynamic potentials rather precisely but the computational difficulties prevent them from being used for calculating other thermodynamic properties. The WCA method has been found to combine high accuracy with sufficient simplicity of calculations and seems, therefore, to be the most promising one for quantitative calculations of liquid metal thermodynamics. They also discuss the problems of applicability of the methods considered at various T and n (particularly in the vicinity of the critical point), of the dependence of their accuracy on the metal valency and the sensitivity of the results to the type of pseudopotential model used.

Stability and thermodynamics of metal- p-nitrobenzaldehyde thiosemicarbazone systems

Stability and thermodynamics of metal- p-nitrobenzaldehyde thiosemicarbazone systems

Thermodynamics of metal [sbnd]ligand bond formation : XXXII. Lewis acidity of phenyl-zinc and -cadmium compounds

Thermodynamic data have been obtained by calorimetric titration in toluene at 30°C for the formation of adducts of Ph 2Cd and Ph 2Zn with heterocyclic bases. Cd readily becomes 4-coordinate, forming very stable 1/1 adducts with o-phen, bipy or tmed and both 1/1 and2/1 adducts with 4-methylpyridine. Zn prefers to become 3-coordinate, forming very stable adducts (Ph 2Zn) 2B with phen, bipy or tmed; only phen forms a 1/1 adduct and its enthalpy of formation is little greater. With 4-methylpyridine a stable1/1 adduct is formed, but addition of further base is incomplete even with a large excess of base.

Charge neutrality and the statistical thermodynamics of metals and alloys

Charge neutrality and the statistical thermodynamics of metals and alloys

Charge neutrality and the statistical thermodynamics of metals and alloys

It is observed that the long wavelength density fluctuations of the conduction electrons are dependent on those of the ions. This implies certain relations between the partial structure factors, which are relevant to the analysis of scattering data. An expression for the compressibility of a pure metal is derived and is shown to yield the Bohm-Staver formula in the free electron case.

Problems and progress in the thermodynamics of metals and alloys

Problems and progress in the thermodynamics of metals and alloys