Partial-cluster model of viscosity of copper-aluminum melt

2021 ◽  
pp. 59-65
Author(s):  
V. P. Malyshev ◽  
A. M. Malysheva
Keyword(s):  
Cluster Model ◽  
State Diagram ◽  
Liquidus Line ◽  
Viscosity Model ◽  
Analytical Determination ◽  
Heat Of Mixing ◽  
Al Alloy ◽  
Calculated Dependence ◽  
Wide Range ◽  
Copper Aluminum

The adequacy of the developed partial-cluster viscosity model with respect to melts of metal alloys was verified using the well-studied copper-aluminum system, for which the state diagram and viscosity isotherms are known in a wide range of compositions. Based on the literature on the thermodynamics of mixing copper and aluminum melts, it was found that this shift is accompanied by heat generation due to the formation of intermetallic compounds in the melt. The destruction of these compounds requires appropriate heat consumption, therefore, it should be taken into account in the partial-cluster viscosity model as an additional thermal barrier to randomization. On this basis, a refined and more generalized form of the partial-cluster model with the expression of the randomization energy of the melt in the form of the algebraic sum of the randomization heat along the liquidus line and the heat of destruction of any intermetallic formations is proposed ΔHch = RTliq – ΔHmix. Application of the generalized partial-cluster model to copper-aluminum melts ensured the repetition of the extreme form of empirical isotherms, even with the appearance of excess viscosity in the calculated dependence. A more detailed analysis of the heat of mixing according to its covalent and metal components showed that the second of them is already randomized and only the covalent component should be taken into account, which should be randomized and should be included in the total randomization barrier in the form ΔHch = RTliq – ΔcovH. Taking this component into account allowed us to obtain a more adequate calculated dependence of the viscosity of the Cu – Al alloy at a temperature of 1100 оC with a correlation coefficient of 0.986, which can be considered as a priority result in the description of viscosity isotherms according to state diagrams. This result is due to the analytical determination of the fraction of clusters in the melt based on the distribution of clusters proposed by the authors according to the number of particles included in the framework of the concept of randomized particles developed by the authors, which is directly related to the Boltzmann’s distribution.

scholarly journals Determination of microstructural changes by severely plastically deformed copper-aluminum alloy: Optical study

2014 ◽  
Vol 50 (1) ◽  
pp. 61-68 ◽  
Author(s):  
N. Romcevic ◽  
M. Gilic ◽  
I. Anzel ◽  
R. Rudolf ◽  
M. Mitric ◽  
...  
Keyword(s):  
Plastic Deformation ◽  
Severe Plastic Deformation ◽  
Structural Characteristics ◽  
Al Alloy ◽  
Local Structures ◽  
Angular Pressing ◽  
Aluminum Solid Solution ◽  
Oxide Particles ◽  
Copper Aluminum ◽  
Nanosized Oxide

Our work deals with the problem of producing a complex metal-ceramic composite using the processes of internal oxidation (IO) and severe plastic deformation. For this purpose, Cu-Al alloy with 0.4wt.% of Al was used. IO of sample serves in the first step of the processing as a means for attaining a fine dispersion of nanosized oxide particles in the metal matrix. Production technology continues with repeated application of severe plastic deformation (SPD) of the resulting metalmatrix composite to produce the bulk nanoscaled structural material. SPD was carried out with equal channel angular pressing (ECAP), which allowed that the material could be subjected to an intense plastic strain through simple shear. Microstructural characteristics of one phase and multiphase material was studied on internally oxidized Cu with 0.4wt.% of Al sample composed of one phase copper-aluminum solid solution in the core and fine dispersed oxide particles in the same matrix in the mantle region. In this manner AFM, X-ray diffraction and Raman spectroscopy were used. Local structures in plastically deformed samples reflect presence of Cu, CuO, Cu2O, Cu4O3 or Al2O3 structural characteristics, depending on type of sample.

scholarly journals The UK Smoke Constituents Testing Study. Summary of Results and Comparison with Other Studies

2004 ◽  
Vol 21 (2) ◽  
pp. 117-138 ◽  
Author(s):  
E Gregg ◽  
C Hill ◽  
M Hollywood ◽  
M Kearney ◽  
D McLaughlin ◽  
...  
Keyword(s):  
Yield Variability ◽  
Analytical Determination ◽  
Minor Role ◽  
Department Of Health ◽  
Routine Measurement ◽  
Wide Range ◽  
The Uk ◽  
A Minor ◽  
Analytical Variation

AbstractAt the request of the UK Department of Health, samples of 25 commercial UK cigarette brands were provided to LGC Ltd a for smoke analysis. The brands reflected a high market share (58% in July 2001) and included a wide range of blend and product styles manufactured and imported into the UK.= 0.76), suggesting a minor role of other design features on constituents yield variability. This was confirmed by the application of multiple regression analysis to the data. A subset of five brands, retested at another laboratory, gave between-laboratory differences in mean constituent yields of as much as 2.5-fold. Consideration of these results, other likely sources of analytical variation in this study and a review of other studies, clearly indicates that any tolerance values to be associated with individual smoke constituent measurements will be greater than those for NFDPM, and in some cases, much greater. Consistent with the reported results from other large studies it is concluded that, under ISO smoking conditions, smoke constituent yields are largely predictable, if NFDPM and CO yields are known, for a standard cigarette. Given these observations and the likely limitations of analytical determination, the need for routine measurement of smoke constituent yields, other than NFDPM, nicotine or CO, on standard cigarettes, is questionable.

scholarly journals Phytochemical Investigation and Antioxidative Capacity of Triterpenes Present in Plant Species Belonging to Lamiaceae Family

2020 ◽  
Keyword(s):  
Ursolic Acid ◽  
Betulinic Acid ◽  
Analytical Determination ◽  
Antioxidative Capacity ◽  
Dpph Method ◽  
Wide Range ◽  
Ic50 Values ◽  
Hexane Extracts ◽  
Dpph Scavenging ◽  
Rosmarinus Officinalis L

Triterpenes are persistently associated with observed bioactivities of extracts obtained from plant material that contains these very important natural products. Many species belonging to Lamiaceae family have been used for the presence of essential oil and very little is known about the presence of the triterpene substances in this family. Qualitative and quantitative analyses of this very important substances, in the aerial parts of eight species, all belonging to Lamiaceae family, were investigated in this study. Different extracts containing triterpene substances were tested by DPPH method to evaluate their antioxidative capacity. TLC and HPLC methods, used for the analytical determination of triterpenes, showed the presence of betulin, betulinic acid, ursolic acid and oleanolic acid. Betulin (3.2 mg/g) and betulinic acid (37.1 mg/g) were the most abundant triterpene components in the hexane extracts of Rosmarinus officinalis L. Ursolic acid (0.14 mg/g) was the most abundant triterpene compound in the hexane extract of Thymus pulegioides L. All tested samples demonstrated DPPH scavenging activity in a concentration dependant manner, with a wide range of IC50 values from 0.4 mg/mL to 3.3 mg/mL.

Determination of the liquid evaporation rate when categorizing rooms and outdoor installations

2020 ◽  
pp. 120-129
Author(s):  
Геннадий Тимофеевич Земский ◽  
Владимир Александрович Зуйков ◽  
Александр Валерьевич Ильичев ◽  
Наталья Валентиновна Кондратюк ◽  
Александр Владимирович Зуйков
Keyword(s):  
Evaporation Rate ◽  
Saturated Vapor ◽  
State Diagram ◽  
Critical Parameters ◽  
Normative Documents ◽  
Ambient Temperatures ◽  
Wide Range ◽  
Evaporation Intensity ◽  
Liquid Evaporation

Возможность взрыва паровоздушной смеси при аварийном проливе жидкости из технологического аппарата во многом зависит от интенсивности испарения жидкости. Для определения интенсивности испарения существуют уравнения, в которые входят величины, характеризующие свойства жидкости, условия ее нахождения в аппарате перед аварией и условия, в которые попадает выливающаяся жидкость. Критически рассмотрены известные уравнения для определения интенсивности испарения, начиная от уравнения Ленгмюра - Кнудсена и заканчивая уравнениями, вошедшими в нормативные документы по обеспечению пожарной безопасности. Рассмотрены варианты аварийного пролива пожароопасных жидкостей в зависимости от сочетания следующих температур: температуры кипения жидкости, температуры вспышки жидкости, температуры жидкости до пролива и температуры окружающей среды. The possibility of an explosion of a steam-air mixture in the event of an emergency spillage of liquid from the process apparatus largely depends on the liquid evaporation intensity. The evaporation intensity is influenced by the following factors: the properties of the liquid (such as critical parameters, liquid temperature, saturated vapor pressure, flash point) as well as the temperature and pressure of the surrounding atmosphere. To determine the intensity of evaporation there are equations that include values that characterize the properties of the liquid, the conditions of its presence in the device before the accident, and the conditions for the spilling liquid after the accident. There is critically considered the wide range of known equations for determining the evaporation intensity beginning with the Langmuir-Knudsen equation and ending with the equations included in the normative documents on fire safety. The Langmuir-Knudsen equation is valid when liquid evaporation occurs in vacuum. When liquid vaporizes in real conditions it is necessary to take into account the non-isothermic nature of the process and the diffusion of vapors into the atmosphere, as well as the possible entrainment of vapors by convective air flows. After the appropriate corrections as a result of special tests there was obtained the equation for determining the evaporation rate. Variants of emergency spillage of fire-hazardous liquids are considered depending on a combination of the following temperatures: the boiling temperature of the liquid, the flash temperature of the liquid, the temperature of the liquid before the spill and the ambient temperature. Equations for calculating the evaporation intensity are defined for every variant. There is carried out correlation of the variants with liquid evaporation during emergency spill with the classification of liquids according to the state diagram in relation to the range of ambient temperatures according to Marshall.

Combined Surface Treatment of Electron Beam Alloying and PVD Hard Coating for Al Alloys

2014 ◽  
Vol 794-796 ◽  
pp. 187-192 ◽  
Author(s):  
Anja Buchwalder ◽  
Rolf Zenker ◽  
Erik Zaulig ◽  
Jürgen Liebich ◽  
Dietmar Leuteritz
Keyword(s):  
Electron Beam ◽  
Physical Vapor Deposition ◽  
Combined Treatment ◽  
Surface Hardness ◽  
Base Material ◽  
Hard Coatings ◽  
Beam Deflection ◽  
Al Alloy ◽  
Wear Protection ◽  
Wide Range

Due to their typically high hardness, excellent resistance against wear, and their low coefficient of friction, Physical Vapor Deposition (PVD) hard coatings are used on steels for a wide range of tools and components. Currently, however, the potential for wear protection of Al alloy components cannot be exploited. The thin PVD layers tend to collapse and disintegrate due to plastic deformation of the soft base material. Present research is focused on electron beam (EB) surface alloying, using Co-based additives to increase the surface hardness of the Al base material, producing an improved supporting effect for PVD coatings. The influence of different beam deflection techniques and EB parameters on the microstructure and hardness of alloyed layers was investigated. The properties of the duplex composite layers produced are strongly dependent on the thermal stability of the EB alloyed layers (type and amount of intermetallic compounds, coarsening effects) which are affected by the temperature-time cycle of the PVD process. This will be discussed by means of SEM and EDX investigations in correlation with XRD analysis. Measurements using scratch test with increasing load result in critical load values for the combined treatment that are 3 to 5 times higher when compared to only PVD-coated base material.

Lazy Wave Catenary Risers: Scaling Factors and Analytical Approximation of the Static Stress Range in the Touchdown Zone

2013 ◽  
Author(s):  
Lucile M. Quéau ◽  
Mehrdad Kimiaei ◽  
Mark F. Randolph
Keyword(s):  
Oil And Gas ◽  
Structural Response ◽  
High Sensitivity ◽  
Cost Effective ◽  
Analytical Approximation ◽  
Static Stress ◽  
Analytical Determination ◽  
Stress Range ◽  
Dynamic Amplification Factor ◽  
Wide Range

Offshore exploration and production of oil and gas continue to increase and move into ever deeper water. Steel catenary risers (SCRs) are one of the most cost effective type of risers in deep water. However, high sensitivity to vessel motions and hydrodynamic loading in the touchdown zone may limit the feasibility of SCR applications. In recent years, there has been a growing interest in the use of Lazy-wave catenary riser (LWR) due to their better fatigue performance in the touchdown zone through the damping effect of the buoyancy section. The design of LWR involves numerous parameters that lead to a wide range of configurations. Each of these configurations needs to be evaluated against several criteria with respect to geometry, strength and fatigue for instance. This paper presents how tools recently proposed to improve the design of standard SCRs can be extended to benefit LWR applications. The dimensionless groups governing the structural response of LWRs are established in the aim of easing sensitivity analysis to key input parameters for LWR design, assisting experiments and reducing the number of numerical simulations. Moreover, the DAF (dynamic amplification factor) approach for dynamic response which has previously been explored for SCRs could also be used to simplify design of LWRs. As DAF relies on the analytical determination of static response, this framework shows that analytical boundary layer solutions in conjunction with the use of a Winkler type soil model can efficiently and accurately predict the static stress range of LWRs observed in the TDZ.

Continuous Grain Refinement Using Severe Torsion Straining Process

2006 ◽  
Vol 503-504 ◽  
pp. 385-390 ◽  
Author(s):  
Katsuaki Nakamura ◽  
Koji Neishi ◽  
Kenji Kaneko ◽  
Michihiko Nakagaki ◽  
Z. Horita
Keyword(s):  
Grain Size ◽  
Grain Refinement ◽  
Uniform Elongation ◽  
Continuous Process ◽  
Longitudinal Axis ◽  
Mg Alloy ◽  
Critical Ratio ◽  
Al Alloy ◽  
Heated Zone ◽  
Wide Range

This study presents a new rapid continuous process for grain refinement in metallic materials through severe plastic deformation (SPD). The new process, designated in this study the severe torsion straining process (STSP), is applicable to a wide range of alloys based on aluminum, magnesium and copper including carbon steel. This process consists of producing a local heated zone in a rod and cooling both sides of the heated zone by spray water while rotating one end with the other. Thus, torsion strain is introduced in the local heated zone. The STSP can be continuous because the straining is achieved while the rod is shifted along the longitudinal axis of the rod. Furthermore, the process requires no die, suggesting a potential for commercialization of grain refinement through SPD. In this study, STSP was applied to an Al-Mg alloy and a Mg-Al-Zn alloy. It is shown that STSP is effective for both alloys so that the grain size is reduced to ~1.5 μm for the Al alloy and ~0.9 μm for the Mg alloy. Tensile testing showed that the strength is increased with a minimal decrease in uniform elongation. There is a critical ratio between rotation speed and moving speed, which defines the feasibility of STSP operation without breaking the rod. The grain size tends to be lowered as the ratio is close to the critical value.

scholarly journals Temperature-Dependent Viscosity Model for Silicone Oil and Its Application in Viscous Dampers

Processes ◽  
2021 ◽  
Vol 9 (2) ◽  
pp. 331
Author(s):  
Márk Venczel ◽  
Gabriella Bognár ◽  
Árpád Veress
Keyword(s):  
Shear Rate ◽  
Torsional Vibration ◽  
Transient Flow ◽  
Silicone Oil ◽  
Viscosity Model ◽  
Working Fluid ◽  
Oil Viscosity ◽  
Temperature Dependent ◽  
Wide Range ◽  
Dependent Viscosity

Silicone fluids belong to the group of pseudoplastic non-Newtonian fluids with complex rheological characteristics. They are considered in basic and applied researches and in a wide range of industrial applications due to their favorable physical and thermal properties. One of their specific field of applications in the automotive industry is the working fluid of viscous torsional vibration dampers. For numerical studies in the design and development phase of this damping product, it is essential to have thorough rheological knowledge and mathematical description about the silicone oil viscosity. In the present work, adopted rheological measurement results conducted on polydimethylsiloxane manufactured by Wacker Chemie with initial viscosity of 1000 Pas (AK 1 000 000 STAB silicone oil) are processed. As a result of the parameter identification by nonlinear regression, the temperature-dependent parameter curves of the Carreau–Yasuda non-Newtonian viscosity model are generated. By implementing these parameter sets into a Computational Fluid Dynamics (CFD) software, a temperature- and shear-rate-dependent viscosity model of silicone fluid was tested, using transient flow and thermal simulations on elementary tube geometries in the size range of a real viscous torsional vibration damper’s flow channels and filling chambers. The numerical results of the finite volume method provide information about the developed flow processes, with especial care for the resulted flow pattern, shear rate, viscosity and timing.

scholarly journals Phase Equilibrium of Biologically Active Systems 4,6-dinitro-5,7-dichlorobenzofuroxane and 5-nitro-4,6-dichlorobenzofuroxane

2020 ◽  
Vol 9 (4) ◽  
pp. 26-31
Author(s):  
L. M. Yusupova ◽  
A. N. Khuziakhmetova ◽  
E. G. Gorelova ◽  
V. K. Mingazova ◽  
I. V. Galkina
Keyword(s):  
Solid Solution ◽  
Synergistic Effect ◽  
Phase Equilibria ◽  
State Diagram ◽  
Thermodynamic Characteristics ◽  
Biologically Active ◽  
Study Phase ◽  
Physicochemical Interaction ◽  
Mold Fungus ◽  
Wide Range

Introduction. One of the intensive ways to increase the therapeutic efficacy and safety of a drug is a combination of several already known substances or chemical compounds, leading to the appearance of a synergistic effect. This method of creating a medicinal product is one of the most important trends in recent times, since the synergistic effect allows one to achieve greater pharmacological activity, expand the range of medical applications and reduce the toxic effect of the drug on the organism. These pharmaceutical active substances include a binary mixture "Dimixan"(mixture 4,6-dinitro-5,7-dichlorobenzofuroxan (4,6-DNDHBFO) and 5-nitro-4,6-dichlorobenzofuroxan (5-NDHBFO). They demonstrate potentiated synergism to the ultra-resistant mold fungus of the species Aspergillius niger. However, the synergy mechanism of the mixture of 5-NDHBFO and 4,6-DNDHBFO is not fully studied. The results of determining the thermodynamic characteristics and phase equilibria in these systems will make it possible to determine the nature of the interaction between 5-NDCBPO and 4,6-DNDCBPO, which will undoubtedly contribute to the optimal organization of the production of a promising drug.Aim. Establishing the nature of the interaction between 5-NDHBFO and 4,6-DNDHBFO in the system.Materials and methods. Using differential scanning calorimetry (DSC), phase equilibria in the 5-NDHBFO and 4,6-DNDHBFO systems were studied in a wide range of component concentrations. From the state diagram, the thermodynamic characteristics of the eutectic were determined: the enthalpy and entropy of melting of mixtures of 5-NDHBFO – 4,6-DNDHBFO at different ratios of components.Results and discussion. Based on the results of the study, phase reactions with the physicochemical interaction of 5-NDHBFO and 4,6-DNDHBFO in two-component systems with the formation of eutectic alloys of the "solid solution" type are identified. The specific values of the enthalpies of melting of alloys of eutectic compositions were determined, from which the entropies of melting were calculated. The results of a study of the density of eutectic compositions of 5-NDHBFO – 4,6-DNDHBFO indicate the formation of an interstitial solid solution.Conclusion. The nature of the interaction between 5-NDHBFO and 4,6-DNDHBFO in the system, leading to the appearance of a synergy effect, has been established. The results obtained are important for predicting the eutectic compositions of 5-NDHBFO and 4,6-DNDHBFO as active pharmaceutical ingredient with increased biological activity.

Correlation of Strength with Hardness and Electrical Conductivity for Aluminium Alloy 7010

2006 ◽  
Vol 519-521 ◽  
pp. 853-858 ◽  
Author(s):  
Manuel A. Salazar-Guapuriche ◽  
Y.Y. Zhao ◽  
Adam Pitman ◽  
Andrew Greene
Keyword(s):  
Mechanical Properties ◽  
Electrical Conductivity ◽  
Tensile Strength ◽  
Aluminium Alloy ◽  
Precipitation Hardening ◽  
Age Hardening ◽  
Al Alloy ◽  
Wide Range ◽  
Proof Strength ◽  
The Relationship

The tensile strength, proof strength, hardness and electrical conductivity of Al alloy 7010 under different temper and ageing conditions were investigated with the aim to correlate strength with hardness and electrical conductivity so that the strength of the alloy can be determined nondestructively. Following the solutionising treatment, continuous age hardening was performed on a series of test coupons, taken from a large plate, to produce a wide range of precipitation hardening conditions, which gave rise to progressive variations of strength, hardness and conductivity. The relationship between strength and hardness was found to be reasonably linear, whereas the relationship between hardness and strength with electrical conductivity was non-linear. The ageing conditions and therefore the mechanical properties of the components can be predicted more accurately by the simultaneous combination of hardness and conductivity values.

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