Temperature Dependences Of Kinematic Viscosity Research Articles

Synthetic oils based on pentaerythritol esters. Kinematic viscosity

One of the main characteristics of lubricants is the viscosity index, which shows the dependence of oil viscosity on temperature. The higher the viscosity index, the better the lubricating properties of the oil. Esters of various polyols, in particular pentaerythritol, are very effective in this direction. This work examines a wide range of high-purity pentaerythritol esters of 14 compounds of varying degrees of branching and studies the temperature dependences of kinematic viscosity in the temperature range from melting temperatures to 150 °C. Based on the obtained data, the values of viscosity indexes were calculated, and the contribution of the carboxylic acid structure to the viscosity properties was also considered.

Kinematic Viscosity and Electrical Resistivity of a Multicomponent Melt due to Liquid–Liquid Structure Transition

We investigated the kinematic viscosity and electrical resistivity of the multicomponent Fe74Cu1Nb1.5Mo1.5B8.5Si13.5 melt during three heating–cooling cycles. The temperature dependence of kinematic viscosity and electrical resistivity have the anomalous zones in the same temperature range and they are associated with the liquid–liquid structure transition (LLST). The anomalies were explained by changes in the activation energy and the cluster size. As the cluster size decreases, the activation energy decreases, but the viscosity and electrical resistance increase. LLST begins with the cluster dissolution, and as a result, the Arrhenius plot becomes nonlinear in the transition temperature range. After three cycles of heating–cooling, the temperature dependences of the kinematic viscosity and electrical resistance did not qualitatively change, and this allows us to conclude that LLST is thermoreversible. With an increase in the number of thermal cycles, the activation energy of viscous flow decreases, as well as the onset temperature and temperature range of LLST.

Viscosity of Cu–Ni Melts

The kinematic viscosity of Cu–Ni melts with nickel contents of 10, 20, 30, 40, 50, 60, 70, 80, and 90 at % is measured. Kinematic viscosity is measured using the damped torsional vibrations of a crucible with a melt in the mode of sample cooling. The measuring results are discussed within the theory of absolute reaction rates. The temperatures at which the viscous flow characteristics (and thus the structural state of the melt) change are determined by analyzing the temperature dependences of kinematic viscosity. The patterns of the liquid–liquid transition in metal alloys of the Cu–Ni system that form a continuous series of solid solutions during crystallization are analyzed.

Влияние условий плавки на выделение кислорода из порошка природнолегированного чугуна

Temperature dependences of kinematic viscosity of naturally alloyed iron in a liquid state have been studied. Temperatures, the heating to which transforms the melt into a homogeneous state have been assigned. The polytherm has a complicated type showing the presence of several stages of structural transformations. It was established that the maximum temperature of the heating melt during the experiment greatly affects the type of the polytherm hysteresis. Based on the quasi-chemical model of micro-inhomogeneous melt structure, physical substantiation of transformations occurring during heating and cooling of liquid metal was offered. The results obtained were used in the production of powders from naturally alloyed iron. Pilot melting during which liquid metal was heated above and below its structural reorganizations was carried out. In addition, the temperature of liquid metal spraying by nitrogen was varied. The influence of the melting regimes of naturally alloyed iron on the oxygen content in the obtained powder was studied. Research by the method of vacuum melting using the equipment “O-N-mat 822” showed that the process of oxygen deposition from powder particles has a complicated type. It was found out that the oxygen content in iron powder depends on the particle size and conditions of melt preparation to spraying. Formation of the homogeneous condition during melting leads to the decrease of oxygen concentration in the powder and to the change of its deposition spectrum. It turns out that in such melts oxygen is in a solid solution or is bound in iron oxides.

Key Experimental Results of the PYROSMANI Project

The presented key results were obtained in the course of experiments carried out within the PYROSMANI (PYROchemical processes Study for Minor ActiNIdes recycling in molten salt chlorides and fluorides) Project supported by Rosatom. The individual and joint solubility of UF4, PuF3 and CeF3 in ternary LiF–NaF–KF and LiF- ThF4-UF4 melts was measured by method of isothermal saturation for the temperature range 550-800°C. The solubility measurement technique based on isothermal saturation was verified in LiF–NaF–KF eutectics for praseodymium trifluoride by the reflectance spectroscopy. The process under investigation was the extraction of lanthanum, neodymium, europium and samarium trifluorides from 73LiF-27BeF2 melt (mole %) into liquid bismuth at 600-610°C. There were defined temperature dependences of kinematic viscosity and melting temperatures for molten 46.5LiF–11.5NaF–42KF; 73LiF-27BeF2; 85LiF-15AlF3 and 43.5LiF–24.3NaF–32.2UF4 salt mixtures from liquidus temperature to 840°C.

Synthesis and properties of dicationic ionic liquids containing a siloxane structural moiety

Five new ionic liquids formed by doubly charged cations containing a siloxane moiety and bis(trifluoromethylsulfonyl) imide anion are synthesized and characterized. Their thermal stability is studied by means of TGA; melting points (glass transition temperatures) and densities are measured. The temperature dependences of kinematic viscosity of the obtained ionic liquids are presented along with their approximations by the Vogel–Tammann–Fulcher equation.

Kinetic Viscosity of Molten High Entropy Alloys Cu–Sn–In–Bi–Pb

By means of torsional oscillation was studied temperature dependence of kinematic viscosity of equiatomic alloys Cu–Sn–In–Bi–Pb in the range of 600–1300 °C during heating and cooling regimes. There was detected discrepancy of temperature dependence for kinematic viscosity, corresponding to regimes of heating and cooling, as well as stepwise variation of characteristics of viscous flow (activation energy of viscous flow and entropy factor in Arrhenius equation) during sample heating.

Viscosity of high-entropy melts in Cu-Sn-Pb-Bi-Ga, G-Sn, Cu-Pb, Cu-Ga, and Cu-Bi equiatomic compositions

Temperature dependences of kinematic viscosity of high-entropy melts (HEM) of the composition, at %, Cu-20Sn-20Pb-20Bi-20Ga, Cu-50Sn, Cu-50Pb, Cu-50Ga, and Cu-50Bi are investigated in a temperature range from 1550 to 1300°C. It is shown that melt overheating above a definite temperature (t hom) leads to the appearance of viscosity hysteresis, which indicates a variation in the structural state of the HEM. The values of t hom for all studied samples are in limits of 925–1185°C. It is found that heating the HEM to definite temperatures (t*) leads to a variation in the activation energy of viscous flow (E) and entropy multiplier (A) in the Arrhenius equation: ν = Aexp[E/(RT)]. Entropy of viscous flow (ΔS #) for studied HEMs is investigated in terms of the Airing theory. It is revealed that the magnitude of ΔS# for a five-component Cu-Sn-Pb-Bi-Ga melt in a cooling mode is smaller than during heating by a factor of 2.6. The rheological characteristics of HEMs allow us to consider these melts promising functional materials: solders, heat carriers, and electric contacts.

VISCOSITY OF HIGH-ENTROPY MELTS IN CU–SN–PB–BI–GA, CU–SN, CU–PB, CU–GA, AND CU–BI EQUIATOMIC COMPOSITIONS

Temperature dependences of kinematic viscosity of high-entropy melts (HEM) of the composition, at %: Cu–20Sn–20Pb–20Bi–20Ga, Cu–50Sn, Cu–50Pb, Cu–50Ga, and Cu–50Bi are investigated in a temperature range from 1550 to 1300 °C. It is shown that melt overheating above a definite temperature (thom) leads to the appearance of viscosity hysteresis, which indicates the variation in the structural state of the HEM. Values of thom for all studied samples are in limits of 925–1185 °C. It is found that heating of the HEM to definite temperatures (t*) leads to the variation in activation energy of viscous flow (Е) and entropy multiplier (A) in the Arrhenius equation: v = Aexp[E/(RT)]. Entropy of viscous flow (ΔS≠) for studied HEM is investigated in terms of the Airing theory. It is revealed that the magnitude of ΔS≠ for a five-component Cu–Sn–Pb–Bi–Ga melt in a cooling mode is smaller than during heating by a factor of 2,6. The found rheological characteristics of HEMs allow us to consider these melts as promising functional materials: solders, heat carriers, electric contacts.

Flow behavior of petrol, bio-ethanol and their blends

The objective of this article deals with the flow behavior of bio-ethanol, conventional petrol and their blends (E15, E85). The temperature dependence density and kinematic viscosity of the liquids have been measured. The densitometer Densito 30PX with the scale for measuring fuels has been used to the measuring temperature dependence of the density of fuels and their blends. The rotary viscometer Anton Paar DV-3P has been used to the measuring temperature dependence of kinematic viscosity of fuels and their blends. For all samples has determined that the temperature has increased the density and kinematic viscosity of fuels and their blends has decreased. The range of temperature measurement has been from −10°C to 40°C. The mathematic models have been compiled (polynomial and exponential) according to the general shapes. The coefficients of determination R2 have achieved high values from 0.98 to 0.99 for temperature dependence of density of fuels and their blends and from 0.86 to 0.96 for temperature dependence of kinematic viscosity of fuels and their blends. The mathematical models could be used to the prediction flow behavior of petrol, bio-ethanol and their blends.

Influence of hot water temperature pumped into force mining holes on output of oil

The subject of the study is the increase of output of crude oil, depending on the temperature of pumped water. The pumping into holes of a coolant is one of the main methods to improve oil extraction. Preparation of the coolant can be carried out with the help of heat station using organic and nuclear power. For the selection and optimization of the parameters of these power plants, it is necessary to know the dependence of consumption of crude oil on the temperature of the pumped coolant. The purpose of the article is to obtain such dependence. The method of achievement of the results is the use of the formula of Walter for the temperature dependence of kinematic viscosity and of the formula of Mendeleev for density of oil. Currently, to maintain the sheeted pressure, cold water is injected into the pumped mining holes. It is known that the oil output is inversely proportional to its viscosity. Increase of the output of crude oil is determined as the ratio of the dynamic viscosity of the oil at 40 o C to the viscosity of oil at a predetermined temperature. To calculate this ratio we derived temperature dependences of kinematic viscosity, density and dynamic viscosity. We obtained the desired dependence of the coefficient of increase of oil output to use it as a coolant of hot water, taking into account 42% of loss of heat into surrounding rocks.

Temperature dependences of kinematic viscosity of bismuth, lead, and their mutual solutions

Measurement results for temperature dependences of kinematic viscosity in Bi-Pb melts are presented. Measurements were carried out in the temperature range between liquidus and 1400 K. The distinctive feature of experiments was their performance at heating after sample melting and further cooling. On the experimental temperature dependences of kinematic viscosity the values of viscosity at fixed temperature and activation energy of viscous flow have been calculated. Special attention was paid to non-coincidence of the curves obtained at heating and cooling. The specified anomaly is explained by the concept of metastable microcoherence of the studied melts.

The kinematic viscosity of liquid copper-aluminum alloys

The method of damped torsional vibrations of crucible with liquid under investigation is used for measuring the temperature dependences of kinematic viscosity ν of Cu100 − xAlx melts (x = 0–100 at.%) in the range of temperatures t between the liquidus and 1100–1450°C. Unlike the majority of such experiments, the measurements are performed both in the process of heating the sample after its melting and in the course of subsequent cooling. The branching of ν(t) curves corresponding to the foregoing modes is revealed below certain temperatures dependent on the composition of sample (viscosity hysteresis). The curves obtained under cooling have a simple exponential shape predicted by activation theories of viscous flow. The obtained temperature dependences are used for constructing isotherms of kinematic viscosity, on which maxima are observed in the vicinity of stoichiometric concentration of CuAl3 and composition of Cu-30 at.% Al. For the same compositions, extrema are observed on the concentration dependence of activation energy of viscous flow.

Kinematic viscosity of liquid Al-Cu alloys

Temperature dependences of kinematic viscosity n of liquid Al100-x-Cux alloys (x = 0.0, 10.0, 17.1, 25.0, 32.2, 40.0 and 50.0 at.%) were measured. A technique based on registration of the period and the decrement of damping of rotating oscillations of a cylindrical crucible with a melt was used. Viscosity was calculated in low viscous liquids approximation. Measurements were carried out in vacuum in crucibles of BeO with a temperature step of 30°C and isothermal expositions of 10 to 15 minutes during both heating up to 1100-1250°C and subsequent cooling. We have discovered branching of heating and cooling curves v(T) (hysteresis of viscosity) below temperatures depending on the copper content: 950°C at 10 and 17.1 at.% Cu, 1050°C at 25 and 40 at.% Cu, 850°C at 32.2 at.% Cu. For samples with 10 and 17.1 at.% Cu the cooling curve ‘returns’ to the heating one near 700°C. An abnormally high spreading of results at repeated decrement measurements was fixed at heating of the alloy containing 50 at.% Cu above 1000°C. During subsequent cooling the effect disappeared. Isotherms of kinematic viscosity have been fitted for several temperatures.

Viscosity of glass forming alloys based on Fe–Si–B system

The temperature dependences of kinematic viscosity of the amorphizing Fe80B14Si6, Fe77B15Si8, Fe78Ni1B12Si9, Fe78.5Ni1Mo0.5B14Si6 and Fe73.6Nb2.4Cu1B7.2Si15.8 melts in the temperature interval ranging from 1200 to 1600°C under heating and cooling conditions have been studied. When heating the anomalies in the shape of sharp viscosity decrease have been revealed in the polytherms. On further cooling its hysteresis has been observed as well.

Molecular dynamic studies of lubricant related systems—variable temperature IR spectroscopic studies

Molecular interactions are the key to understand the structure and properties of liquids, solutions and solids. The relationship between the molecular structure and viscometric behaviour of fluids has been a subject of considerable importance. Quantitative relationships between molecular structures and various bulk properties of lubricant base fluids, i.e. viscosity, viscosity–temperature and viscosity–pressure variations, pour point etc., are not well defined. The understanding of these relationships is much more difficult in lubricating base fluids where only weak van der Waals interactions are predominant. The dynamic properties of molecular interactions such as correlation functions and relaxation times are of great interest to understand the structure–property relationships.In this paper, vibrational/rotational relaxation time (τIR) data along with half-bandwidth data obtained from infrared (IR) spectra have been used to study the several aspects of the molecular dynamics of base oils of varying physical properties. Relaxation time measurements have been carried out on a few model hydrocarbon compounds and a number of mineral base oils at varied temperatures (25–175°C). Activation energies (Ea) for Newtonian viscous flow (macro process) and vibrational/rotational relaxations (micro process) have been obtained from the temperature dependence of kinematic viscosity and the relaxation data, respectively. The activation energies for base oils containing higher isoparaffins (hydrocracking, HC class oils) have shown lower activation energies compared to those having lower amounts of isoparaffins (hydrofinishing, HF class oils). The activation energies for the micro process involving relaxation of the 1360cm−1 band are lower than the 721cm−1 band. IR spectral half-bandwidths are correlated to the reciprocal of the viscosity of base fluids under study. The linear relationships are used to separate the temperature dependent reorientational effects from vibrational effects.

Structural transition in liquid cobalt

The temperature dependence of kinematic viscosity of liquid cobalt in the range 1490–1700°C and the influence of the degree of cobalt overheating on its overcooling were studied by viscometry and differential thermal analysis. It was found that liquid cobalt undergoes a structural transition near 1595°C, which manifests itself as a sharp change in the viscosity and the activation energy for viscous flow at this temperature and is accompanied by a considerable increase in crystallization ability.

Modelling the temperature dependence of kinematic viscosity for refined canola oil

Viscosities of refined, bleached, deodorized (RBD) and refined, bleached, winterized (RBW) canola oils were measured at temperatures from 4 to 100°C. The viscosities of these refined canola oils were exponentially related to the oil temperature. Viscosity of the RBW oil was slightly greater than that of the RBD oil when the temperature was below 15°C. Compared to refined soybean oil, the canola oils were substantially more viscous. The viscosity of canola oil was modelled asv = exp(C0 + C1T + C2T2). The maximum predicted error was less than 1.6% over the tested temperature range.