Formation mechanisms of Ni-Al intermetallics during heat treatment of Ni coating on 6061 Al substrate

The formation mechanisms and growth kinetics of Al3 Ni and Al3Ni2 in Ni-Al diffusion couple prepared by electrodeposition of Ni on Al substrate were investigated. The nickel coating with 20 μm thickness was applied on 6061 aluminum alloy by direct current electroplating. The samples were then heat-treated for different durations at 450, 500 and 550 °C under argon atmosphere. The intermetallic phases were identified by means of scanning electron microscopy（SEM）, energy dispersive spectrometry（EDS） and X-ray diffraction（XRD）. The results showed that the formation of intermetallic phases consisted of two important steps. The first step was the lateral growth of intermetallic phase from separate sites, resulting in the formation of a continuous layer. The second step was the growth of the continuous intermetallic layer in the direction perpendicular to the interface. However, excessive increase in thickness of intermetallic phases led to the detachment of reaction products, i.e., Al3 Ni and Al3Ni2, from the substrate. It was also observed that aluminum was the dominant diffusing element during Al3 Ni growth, while nickel diffusion was dominant during Al3Ni2 growth. The growth kinetics of both Al3 Ni and Al3Ni2 phases obeyed a parabolic law.

Calculation of the Heat of Formation:Ternary Alloy System

A semi-empirical calculation of the heat of formation was applied to ternary system: La-Fe-Al,Fe-Ni-V and Cu-Pd-Si.The calculated values were compared with the experimental ones and the coincidence was satisfactory.This method is helpful to predict the stabilities of ternary compounds and solid solubility.

Low-temperature heat capacities and standard molar enthalpy of formation of pyridine-2,6-dicarboxylic acid

This paper reports that the low-temperature heat capacities of pyridine-2,6-dicarboxylic acid were measured by a precision automatic calorimeter over a temperature range from 78 K to 380 K. A polynomial equation of heat capacities as a function of temperature was fitted by the least-squares method. Based on the fitted polynomial, the smoothed heat capacities and thermodynamic functions of the compound relative to the standard reference temperature 298.15 K were calculated and tabulated at intervals of 5 K. The constant-volume energy of combustion of the compound was determined by means of a precision rotating-bomb combustion calorimeter. The standard molar enthalpy of combustion of the compound was derived from the constant-volume energy of combustion. The standard molar enthalpy of formation of the compound was calculated from a combination of the datum of the standard molar enthalpy of combustion of the compound with other auxiliary thermodynamic quantities through a Hess thermochemical cycle.

Accurate ab initio Predictions of Ionization Energies and Heats of Formation for Cyclopropenylidene, Propargylene and Propadienylidene

The ionization energies （IEs） of cyclopropenylidene （c-C3H2）, propargylene （HCCCH） and propadienylidene （H2CCC） have been computed using the CCSD（T）/CBS method, which involves the approxixnation to the complete basis set （CBS） limit at the coupled cluster level with single and double excitations plus quasi-perturbative triple excitation effect （CCSD（T））. The zero-point vibrational energy correction, the core-valence electronic correction, the scalar relativistic effect and the high level correction beyond the CCSD（T） excitations have also been made in these calculations. The CCSD（T）/CBS values for the IN（c-C3H2） and IE（HCCCH） of 9.164, 8.987 eV are in good agreement with the experimental values of （9.15±0.03） and （8.96±0.04） eV. The CCSD（T）/CBS calculations yield the IE values of 10.477 and 10.388 eV for the ionization transitions H2CCC→H2CCC^＋ （^2A1, C2v） and H2CCC→H2CCC＋ （^2A＇, Cs）, respectively. On the basis of the Franek-Condon factor consideration, the IE of （10.43±0.02） eV determined in the previous single-photon ionization experiment most likely corresponds to the ionization threshold for the H2CCC→H2CCC^＋（^2A1, C2v） transition. Although the precision of the experimental IN measurements fpr c-C3H2, HCCCH, and H2CCC is insufficient to pin down the accuracy of the theoretical calculations to better than ±30 meV, the excellent agreement between the experimental and theoretical IE values observed in the present study indicates that the CCSD（T）/CBS calculations together with high-order correlation corrections are capable of yielding reliable IE predictions for simple hydrocarbon carbenes and bi-radicals. We have also reported the heats of formation at 0 K （△H^of0） and 298 K （△H^of298）for c-C3H2/c-C3H2^＋, HCCCH/HCCCH^＋, and H2CCC/H2CCC^＋, The available experimental △H^of0 and △H^of298 values for c-C3H2/c C3H2^＋, HCCCH/HCCCH^＋ are found to be in good accord with the CCSD（T）/CBS predictions after taking into account the experimental uncertainties.

Potential energies of characteristic atoms on basis of experimental heats of formation of AuCu and AuCu_3 compounds(Ⅰ)

The systematic science of alloys(SSA)is a framework of the total energy and total volume able to be separated.The potential energy sequences of characteristic atoms at the central sites of the basic clusters in the fcc-based lattice Au-Cu system are separated out from smaller experimental heats of formation of L10-AuCu and L12-AuCu3 compounds only,by nine potential energy E-functions and through the use of structural unit inversion method.From these potential energy sequences,the potential energies and heats of formation of the disordered Au1-xCux alloys at 0 K are calculated.The potential energies,heats of formation and Tc-temperatures of order-disorder transitions of the L10-AuCu,L12-Au3Cu and L12-AuCu3 compounds,as well as the Au3Cu-,AuCu-and AuCu3-type ordered alloys with maximal ordering degrees are calculated too.The results show that the 5th E-function may be chosen for developing it into the free energy-,enthalpy-,vibrational energy-and vibrational entropy-functions for describing thermodynamic properties of the compounds,ordered and disordered phases and for establishing the phase diagram of the Au-Cu system in the future.

Low-temperature heat capacities and standard molar enthalpy of formation of 4-(2-aminoethyl)-phenol (C_8H_(11)NO)

This paper reports that low-temperature heat capacities of 4-（2-aminoethyl）-phenol （C8H11NO） are measured by a precision automated adiabatic calorimeter over the temperature range from 78 to 400 K. A polynomial equation of heat capacities as a function of the temperature was fitted by the least square method. Based on the fitted polynomial, the smoothed heat capacities and thermodynamic functions of the compound relative to the standard reference temperature 298.15K were calculated and tabulated at the interval of 5K. The energy equivalent, εcalor, of the oxygen-bomb combustion calorimeter has been determined from 0.68g of NIST 39i benzoic acid to be εcalor=（14674.69±17.49）J·K^-1. The constant-volume energy of combustion of the compound at T=298.15 K was measured by a precision oxygen-bomb combustion calorimeter to be ΔcU=-（32374.25±12.93）J·g^-1. The standard molar enthalpy of combustion for the compound was calculated to be ΔcHm = -（4445.47 ± 1.77） kJ·mol^-1 according to the definition of enthalpy of combustion and other thermodynamic principles. Finally, the standard molar enthalpy of formation of the compound was derived to be ΔfHm（C8H11NO, s）=-（274.68 ±2.06） kJ·mol^-1, in accordance with Hess law.

Thermochemistry of Heteroatomic Compounds:Calculation of the heat of Combustion and the heat ofFormation of some Bioorganic Molecules with DifferentHydrophenanthrene Rows

On the basis of the known experimental heats of combustions of the seventeen alkanes in condensed state, the general equation has been deduced, in which i and f are correlation coefficients, N and g are a numbers of valence electrons and lone electron pairs of heteroatoms in molecule. The presented dependence has been used for the calculation of the heats of combustion of thirteen organic molecules with biochemical properties: holestan, cholesterol, methyl-cholesterol, ergosterol, vitamin-D2, estradiol, androstenone, testosterone, androstanedione, morphine, morphinanone, codeine and pentasozine. It is noted that good convergence was obtained within the limits of errors of thermochemical experiments known in the literature and calculations of the heats of combustion for some of them were conducted. With the application of Hess law and the heats of vaporization , which has been calculated with the use of a topological solvation index of the first order , the heats of formation for condensed and gaseous phases were calculated for the listed bioorganic molecules.

Low-temperature heat capacities and standard molar enthalpy of formation of N-methylnorephedrine C11H17NO（s）

This paper reports that low-temperature heat capacities of N-methylnorephedrine C11H17NO（s） have been measured by a precision automated adiabatic calorimeter over the temperature range from T=78K to T=400K. A solid to liquid phase transition of the compound was found in the heat capacity curve in the temperature range of T=342-364 K. The peak temperature, molar enthalpy and entropy of fusion of the substance were determined. The experimental values of the molar heat capacities in the temperature regions of T=78-342 K and T=364-400 K were fitted to two poly- nomial equations of heat capacities with the reduced temperatures by least squares method. The smoothed molar heat capacities and thermodynamic functions of N-methylnorephedrine C11H17NO（s） relative to the standard refer- ence temperature 298.15 K were calculated based on the fitted polynomials and tabulated with an interval of 5 K. The constant-volume energy of combustion of the compound at T=298.15 K was measured by means of an isoperibol precision oxygen-bomb combustion calorimeter. The standard molar enthalpy of combustion of the sample was calculated. The standard molar enthalpy of formation of the compound was determined from the combustion enthalpy and other auxiliary thermodynamic data through a Hess thermochemical cycle.

Thermochemistry of Heteroatomic Compounds: the Heats of Combustion and Formation of Glycoside and Adenosine Phosphates

The heats of combustion of 4th glycoside in the condensed state with the use of the equation ΔcombH=15.7-117.2(N-g) , in which N is a number bond-forming (valence) electrons less the number (g) of lone electron pairs of nitrogen (g = 1) and oxygen (g = 2), have been determined. Such dependence is deduced previously joint for the description of the combustion enthalpies of 17 simple ethers of a cyclic structure and different sugars. The heats of formation ( ΔfHo ) of the mentioned above glycosides were calculated according to the Hess law via two ways: 1) through the use their heats of hydrolysis ( ΔhydrH ), which have been investigated earlier experimentally, 2) with the use the calculated the heats of combustion. The last procedure has been used also for the calculation of the heats of formation of the adenosine tri(ATP)-, di(ADP)- and mono(AMP)phosphates because of such thermochemical parameter is often hard achieved experimentally. The heats of hydrolysis ( ΔfH°hydr ) of ATP into ADP and ADP into AMP were calculated on the basis of their heats of formation in water ( ΔfH°aq ). The free energies of the same process ( ΔhydrG ) were known in literature. Last circumstance give us a possibility to calculate the hydrolysis entropies ( ΔhydrS ) using the Gibbs equation. The entropy values are a large negative, that pointed on the preliminary complex formation between adenosine phosphates and water before the breaking of P-O bonds or P-O-C fragments in its.

A Method for Calculating the Heats of Formation of Medium-Sized and Large-Sized Molecules

A calculation method for heats of formation (HOF, referred to as △Hf) based on the density functional theory (DFT) is presented in this work. Similar to Gaussian-3 theory, the atomic scheme is applied to calculate the heats of formation of the molecules. In this method, we have modified the formula for calculation of Gaussian-3 theory in several ways, including the correction for diffuse functions and the correction for higher polarization functions. These corrections are found to be significant. The average absolute deviation from experiment for the 164 calculated heats of formation is about 1.9 kcal·mol?1, while average absolute deviation from G3MP2 for the 149 (among the 164 molecules, 15 large-sized molecules can not be calculated at the G3MP2 level) calculated heats of formation is only about 1.9 kcal·mol?1. It indicates that the present method can be applied to predict the heats of formation of medium-sized and large-sized molecules, while the heats of formation of these molecules using Gaussian-3 theory are much difficult, even impossible, to calculate. That is, this method provides a choice in the calculation of △Hf for medium-sized and large-sized molecules.

Numerical Modeling of the Vapour Vortex Formation in the Short Heat Pipes

The results of the numerical studies of vortex formation inside short heat pipes (HP’s) with profiled vapour channel in the Laval-liked nozzle form are presented. For the first time, it was found that the vapour vortex of moist compressible vapour flow in the cooled part of vapour channel changes its rotational motion direction. The rotation direction of the toroidal vapour vortex, obtained by solving the Navier Stokes equations is dependent on the heat power value, entering to the HP’s evaporator. With low heat power loads the rotational direction of the circular toroidal vapour ring due to the Coanda effect and sticking moving vapour jets to the channel’s walls occurs from the periphery to the longitudinal axis of the vapour channel. While the heat power load increasing, the direction of the circular toroidal vapour ring rotation changes to the opposite, from the longitudinal axis to the periphery of the vapour channel. The thickness of the formed working fluid condensate film located under the toroidal vapour vortex also related to the evaporator heat power load and the associated toroidal vapour vortex rotation direction. The numerical thickness calculation of the formed working fluid condensate film located under the toroidal vapour vortex was compared with experimental values, obtained by capacitive sensors. The thickness values of the calculated condensate film thickness and experimentally measured values using capacitive sensors are close in magnitude order.

The Role of Topography and Diabatic Heating in the Formation of Dipole Blocking in the Atmosphere

In this paper, the nonlinear stationary waves forced by topography and diabatic heating are investigated. It is pointed out that (1) the nonlinear interaction of different stationary waves forced only by topography might form dipole blocking in the atmosphere, this might explain the dipole blocking appeared in the Pacific and Atlantic regions; (2) the dipole blocking could not be caused by the nonlinear interaction of the different stationary waves forced by the diabatic heating alone; (3) the nonlinear interaction of the diffferent stationary waves forced by both topography and diabatic heating could initiate dipole blocking in the atmosphere. In winter, the dipole blocking mainly occurs in the west regions of the Pacific and the Atlantic, and the heat source over the western part of the two oceans is advantageous to the formation of dipole blocking in the west of two oceans. However, in summer, the dipole blocking could be formed in the east part of the two oceans, and the heat source over the eastern part of two continents is favourable for the formation of dipole blocking in the east regions of two oceans.

Study on NOx Formation in CH4/Air Jet Combustion

With the development of reaction kinetics and transfer science, the modeling of NOx formation plays more and more important roles in the protection of environment and the design of combustion reactors; in this case,turbulence-chemistry model and NOx formation model are the two most important aspects. For thermal NOx mechanism, this article studied the CH4/air system and applied a set of latest NO formation rate constants published at the Leed University which replaced the original model code in FLUENT to increase its precision on prediction of NO concentration. The realizable k-ε model, Reynold Stress model and standard k-ε model were also investigated to predict the turbulent combustion reaction, which indicated that the simulation results of velocities, temperatures and concentrations of combustion productions by the standard k-ε model were in good accordance with the experimental data. With the application of the simulation results to the experimental data to fit some important kinetic parameters in the equation of O atom model and revision of the equation later, this article obtained a new NO formation rate model. It has been proved that the prediction of the developed model coincides well with the measurements.

Formation and Characteristics of Acrylonitrile/Urea Inclusion Compound

The formation process and composition of the acrylonitrile/urea inclusion compounds （AN/UIC） with different aging times and AN/urea molar feed ratios are studied by differential scanning calorimetry （DSC） and X-ray diffraction （XRD）. It is suggested that DSC can determine the guest/host ratio and the heat of decomposition. Meanwhile, the guest/host ratio and heat of decomposition are obtained, which are 1.17 and 5361.53 J/mol, respec- tively. It is suggested AN molecules included in urea canal lattice may be packed flat against each other. It is found that the formation of AN/UIC depends on the aging time. XRD results reveal that once AN molecules enter urea lattice, AN/UIC are formed, which possess the final structure. When AN molecules are sufficient, the length of AN molecular arrays in urea canals increases as aging time prolonging until urea tunnels are saturated by AN.

The geothermal formation mechanism in the Gonghe Basin: Discussion and analysis from the geological background

The Gonghe Basin,a Cenozoic down-warped basin,is located in the northeastern part of the Qinghai-Xizang (Tibetan) Plateau,and spread over important nodes of the transfer of multiple blocks in the central orogenic belt in the NWW direction.It is also called “Qin Kun Fork” and “Gonghe Gap”.The basin has a high heat flow value and obvious thermal anomaly.The geothermal resources are mainly hot dry rock and underground hot water.In recent years,the mechanism of geothermal formation within the basin has been controversial.On the basis of understanding the knowledge of predecessors,this paper proposes the geothermal formation mechanism of the “heat source–heat transfer–heat reservoir and caprock–thermal system”of the Gonghe Basin from the perspective of a geological background through data integrationintegrated research-expert,discussion-graph,compilation-field verification and other processes: (1) Heat source: geophysical exploration and radioisotope calculations show that the heat source of heat in the basin has both the contribution of mantle and the participation of the earth's crust,but mainly the contribution of the deep mantle.(2) Heat transfer: The petrological properties of the basin and the exposed structure position of the surface hot springs show that one transfer mode is the material of the mantle source upwells and invades from the bottom,directly injecting heat;the other is that the deep fault conducts the deep heat of the basin to the middle and lower parts of the earth's crust,then the secondary fracture transfers the heat to the shallow part.(3) Heat reservoir and caprock: First,the convective strip-shaped heat reservoir exposed by the hot springs on the peripheral fault zone of the basin;second,the underlying hot dry rock layered heat reservoir and the upper new generation heat reservoir and caprock in the basin revealed by drilling data.(4) Thermal system: Based on the characteristics of the “heat source-heat transfer-heat reservoir and caprock”,it is preliminarily believed that the Gonghe Basin belongs to the non-magmatic heat source hydrothermal geothermal system (type II21) and the dry heat geothermal system (type II22).Its favorable structural position and special geological evolutionary history have given birth to a unique environment for the formation of the geothermal system.There may be a cumulative effect of heat accumulation in the eastern part of the basin,which is expected to become a favorable exploration area for hot dry rocks.

Numerical Simulation of Bubble Formation at a Single Orifice in Gas-fluidized Beds with Smoothed Particle Hydrodynamics and Finite Volume Coupled Method

A coupled method describing gas–solid two-phase flow has been proposed to numerically study the bubble formation at a single orifice in gas-fluidized beds.Solid particles are traced with smoothed particle hydrodynamics,whereas gas phase is discretized by finite volume method.Drag force,gas pressure gradient,and volume fraction are used to couple the two methods.The effect of injection velocities,particle sizes,and particle densities on bubble growth is analyzed using the coupled method.The simulation results,obtained for two-dimensional geometries,include the shape and diameter size of a bubble as a function of time;such results are compared with experimental data,previous numerical results,and other approximate model predictions reported in the literature.Moreover,the flow profiles of gas and particle phases and the temperature distribution by the heat transfer model around the forming bubble are also discussed.All results show that the coupled method efficiently describes of the bubble formation in fluidized beds.The proposed method is applicable for solving gas–solid two-phase flow in fluidization.

VISUAL OBSERBATION OF HCFC141b GAS HYDRATE FORMATION/DECOMPOSITION PROCESS OUTSIDE OF A TUBE

In order to design a kind of heat exchanger suitable to the indirect-touched gas hydrate cool storage vessel, a visual observation of HCFC141b gas hydrate formation/decomposition process was presented through a self-designed small-scale visualization apparatus of gas hydrate cool storage. Based on the shooted photos and recorded temperatures, the formation/decomposition process of HCFC141b are described, some characteristics are concluded, and some suggestions of designing heat exchanger are indicated according to the specific characteristics of HCFC141b gas hydrate formation/decomposition process.

Formation of integral fins function-surface by extrusion-ploughing process

An extrusion-ploughing process was presented to fabricate the integral fin function-surface. Cutting edge inclination angle and rake angle can be calculated from the tool’s geometry relationship. The description of fins’ geometry characters was standardized. The experiments show that, when the middle cutting edge’s inclination angle η is less than 35°, continuous fin will come out; when η is between 35° and 55°, the fins will be saw-tooth ones, and the fins will be torn when this angle is above 55°; when the extrusion angle θ is between 60° and 150°, the fins will appear, or else, the fins will be torn into chips from the base. Forming angle and clearance angle have little effect on fin’s formation. For continuous fin, its height is close to cutting depth when it is small, but it will become approximately constant as cutting depth grows; for saw-tooth fins, the width, the height, as well as the clearance will increase with the increase of cutting depth, but the increment of clearance is small; neither for continuous fin, nor for saw-tooth ones, cutting velocity has little influence on their structure parameters.