Dispersion and Polar Component of Specific Surface Free Energy of NaCl(100), KCl(100), and KBr(100) Single Crystal Surfaces

Contact angle of ethylene glycol and formamide on (100) faces of NaCl, KCl, and KBr single crystal was measured, and the specific surface free energy (SSFE) was calculated. Dispersion component of the SSFE was 90.57, 93.78, and 99.52 mN&#183m-1 for NaCl, KCl, and KBr, respectively. Polar component of the SSFE was 1.05, 0.65, and 0.45 mN&#183m-1 for NaCl, KCl, and KBr. Such a large ratio of dispersion component of SSFE results from the neutrality of the crystal surface of alkali halide. Lattice component of alkali halide is 780, 717 and 689 kJ&#183mol-1 for NaCl, KCl, and KBr. The larger lattice enthalpy decreases dispersion component, and increases polar component of the SSFE. The larger lattice enthalpy is considered to enhance the rumpling of the crystal surface more strongly, and such rumpling is considered to decrease the neutrality of the crystal surface.

Effect of surface free energy of ceramic glaze on oil droplet shape and its behavior in water

A super-hydrophilic functional ceramic was prepared by adjusting the chemical components of ceramic glaze. Effect of surface free energy of ceramic glaze on oil droplet shape and its behavior in water were studied. The results show that water can spread on ceramic surface with high surface free energy, and oil droplet can aggregate rapidly and separate from the ceramic surface in water. For the ceramic with lower surface free energy, the polar shares are dependant on its easy-cleaning property. The higher the polar shares, the better the easy-cleaning property, and the easier the droplet separates from the ceramic surface in water.

A comparative study of the land-atmosphere energy and water exchanges over the Tibetan Plateau and the Yangtze River Region

正确认识不同区域能量和水分循环特征是研究局地地气相互作用及准确预测区域天气,气候变化的关键.为了研究属于干旱/半干旱气候的青藏高原(TP)和湿润/半湿润气候的长江流域(YRR)之间地表能量和水分交换的异同,本文对比分析了两个区域8个不同地表类型(包括高山荒漠,高山草地,(平原)城市和(平原)草地等)观测站点的地表辐射和能量通量数据.结果显示:(1)TP由于高原大气层稀薄且空气洁净,年平均入射短波辐射为251.3W m^(-2),是YRR的1.7倍.加之高原地表反照率高导致反射辐射(59.6 W m^(-2))是YRR的2.87倍.入射及出射的长波辐射为231.5和338.0 W m^(-2),分别为YRR的0.64和0.83.而两个区域的净辐射差异不大;(2)草地站更多的潜热释放使得地表总加热效率高于城市和高山荒漠,TP和YRR的草地站的年平均潜热分别为35.0和38.8 W m^(-2),而植被稀疏且土壤干燥的高山荒漠地区感热最大,年平均感热为42.1 W m^(-2);其次是城市下垫面,其年平均感热为37.7 W m^(-2).研究结果揭示了不同气候背景下典型下垫面地气相互作用特征,为地气相互作用过程深入分析奠定了基础.

EXAMINATION OF THE SURFACE FREE ENERGY AND ACID-BASE PROPERTIES OF CELLULOSE BY THE COLUMN WICKING TECHNIQUE AND THE CRITICAL PACKING HEIGHT/DENSITY

The column wicking technique was applied to estimate the surface free energy of cellulose, the importance of which is to obtain a real effective capillary radius, Reff, initially from the plot of Washburn penetration distance versus time. Since the cellulose sample could not be packed with good reproducibility, therefore, Reff can not be obtained readily from the slope of the plot. A method was developed in this paper by uniting all apparent packing heights with a unique value to deduce a real effective capillary radius. Based on the defined critical packing height related to the critical packing density, the surface free energy and acid-base properties of cellulose Sigma C8002 were estimated.

Model for seawater fouling and effects of temperature,flow velocity and surface free energy on seawater fouling

A kinetic model was proposed to predict the seawater fouling process in the seawater heat exchangers.The new model adopted an expression combining depositional and removal behaviors for seawater fouling based on the Kern–Seaton model.The present model parameters include the integrated kinetic rate of deposition(k d)and the integrated kinetic rate of removal(k r),which have clear physical signi ficance.A seawater-fouling monitoring device was established to validate the model.The experimental data were well fitted to the model,and the parameters were obtained in different conditions.SEM and EDX analyses were performed after the experiments,and the results show that the main components of seawater fouling are magnesium hydroxide and aluminum hydroxide.The effects of surface temperature,flow velocity and surface free energy were assessed by the model and the experimental data.The results indicate that the seawater fouling becomes aggravated as the surface temperature increased in a certain range,and the seawater fouling resistance reduced as the flow velocity of seawater increased.Furthermore,the effect of the surface free energy of metals was analyzed,showing that the lower surface free energy mitigates the seawater fouling accumulation.

Thermodynamic Equilibrium of the Saturated Fluid with a Free Surface Area and the Internal Energy as a Function of the Phase-Specific Volumes and Vapor Pressure

This study is concerned with describing the thermodynamic equilibrium of the saturated fluid with and without a free surface area A. Discussion of the role of A as system variable of the interface phase and an estimate of the ratio of the respective free energies of systems with and without A show that the system variables given by Gibbs suffice to describe the volumetric properties of the fluid. The well-known Gibbsian expressions for the internal energies of the two-phase fluid, namely for the vapor and for the condensate (liquid or solid), only differ with respect to the phase-specific volumes and . The saturation temperature T, vapor presssure p, and chemical potential are intensive parameters, each of which has the same value everywhere within the fluid, and hence are phase-independent quantities. If one succeeds in representing as a function of and , then the internal energies can also be described by expressions that only differ from one another with respect to their dependence on and . Here it is shown that can be uniquely expressed by the volume function . Therefore, the internal energies can be represented explicitly as functions of the vapor pressure and volumes of the saturated vapor and condensate and are absolutely determined. The hitherto existing problem of applied thermodynamics, calculating the internal energy from the measurable quantities T, p, , and , is thus solved. The same method applies to the calculation of the entropy, chemical potential, and heat capacity.

Study of surface cell Madelung constant and surface free energy of nanosized crystal grain

Surface cell Madelung constant is firstly defined for calculating the surface free energy of nanosized crystal grains, which explains the physical performance of small crystals and may be greatly beneficial to the analysis of surface states and the study of the dynamics of crystal nucleation and growth. A new approximative expression of the surface energy and relevant thermodynamic data are used in this calculation. New formula and computing method for calculating the Madelung constant α of any complex crystals are proposed, and the surface free energies and surface electrostatic energies of nanosized crystal grains and the Madelung constant of some complex crystals are theoretically calculated in this paper. The surface free energy of nanosized-crystal-grain TiO2 and the surface electrostatic energy（absolute value） of nanosized-crystal-grain α-Al2O3 are found to be the biggest among all the crystal grains including those of other species.

Predicting octanol/water partition coefficient using solvation free energy and solvent-accessible surface area

The regression model for octanol/water partition coefficients ( K ow ), is founded with only two molecular descriptors available through quantum chemical calculations: solvation free energy (Δ G S ), and solvent accessible surface area (SASA). For the properties of 47 organic compounds from 17 types, the model gives a correction coefficient (adjusted for degrees of freedom) of 0 959 and a standard error of 0 277 log unit. It is a suitable way to predict the partition properties that are related to solute solvent interactions in the water phase.

Study of Surface Cell Madelung Constant and Surface Free Energy of Nanosized Crystal Grain

Surface cell Madelung constant is firstly defined in calculating surface free energy of nanosized crystal grains, which explains the physical performance of small crystals and may be great benefit to make surface analysis and study dynamics of crystal nucleus growth. A new approximative expression of surface energy and relevant thermodynamic data was used in this calculation. A new formula and computing method for calculating the Madelung constant a of any complex crystals is proposed, and surface free energies and surface electrostatic energies of nanosized crystal grains as well as Madelung constant of some complex crystals are theoretically calculated in this paper. The surface free energy of nanosized crystal grain TiO2 and surface electrostatic energy（absolute value） of nanosized crystal grain α-A12O3 are found to be the biggest among other crystal grains.

Specific Surface Free Energy of As-Grown and Polished Faces of Synthetic Quartz

Contact angles of water droplet on as-grown Z, +X, –X, and m faces of synthetic quartz crystals with growth term of 20 and 48 days, and polished Z, +X, –X, Y, and 45&#176 cut faces of synthetic quartz crystal were observed. The average of the contact angles on as-grown Z, +X, and –X faces increased with the growth term, and they were larger than that on polished Z, +X, and –X faces. On the other hand, the average of the contact angles of water on m face decreased with the growth term, and they were smaller than that on polished Y cut face. Growth rate of the faces of synthetic crystals was measured and the order of growth rate was, m < –X < +X < Z. Specific surface free energy (SSFE) was calculated using Neumann’s equation. The SSFE of polished face was in the order of, m < –X < +X < Z, which corresponds to the order of the growth rate. The SSFE was larger for the face with larger growth rate.

Surface free energy of copper-zinc alloy for energy-saving of boiler

Cu-Zn,Cu-Zn-Sn,Cu-Zn-Ni alloys were melted by vacuum smelter.The effect factors to the surface free energy of the alloys such as chemical composition,crystal structure and surface crystal lattice distortion etc.were investigated by OCA30 automatic contact angle test instrument,metallography microscope and XRD instrument etc.Results suggests:adding alloy element to Cu may increase its surface free energy,and the more kinds of alloy elements are added,the more surface free energy increases;the alloy element Sn an increase the surface free energy of Cu-Zn alloy;Cu-Zn alloy with fir-tree crystal structure,great phase discrepancy and obvious composition aliquation has greater surface free energy;Cu-Zn alloy with compounds and serious surface crystal lattice distortion has greater surface free energy.

Effect of ACQ-D Treatment on the Surface Free Energy of Chinese Fir (Cunninghamia lanceolata)

In this study, the contact angles of three different reference liquids （including distilled water, diiodomethane, and formamide） and PF resin on the surfaces of Chinese fir （Cunningharnia lanceolata） samples untreated or treated with different concentrations of ACQ-D （ammoniacal copper quat Type D） solutions were measured. Then, the surface free energy was calculated by two approaches： acid-base approach and geometric mean approach. ACQ-D treatment caused higher contact angles and lower surface free energies at a retention level corresponding to the commodity treated wood products. When wood was treated with much higher concentrations of ACQ-D, the total surface free energy of wood would be higher than the untreated control. Acid-base/polar components related with the hydrogen bonding state in wood were considered to be responsible for the observed changes according to the applied approaches. The hydrophobic properties and also higher contact angles of PF resin drop on wood surfaces after ACQ-D treatment at a reasonable retention level confirms the changes on surface free energy.

Effect of surface free energy of acetylene black powder on air electrode performance

The effects of acetylene black powder surface free energy on air electrode electrochemical performance and lifetime were studied.The acetylene black was immersed in 30%H_(2)O_(2)at room temperature and the changes of functional groups and surface free energy were investigated by X-ray Photoelectron Spectroscopy(XPS)and powder contact angle(CA).The air electrode performance was characterized by the potential polarization curves and the lifetime was measured by constant-current discharge.It shows that,its surface free energy is the lowest when the acetylene black is immersed in H_(2)O_(2)for 240 h.The polarization potential of the air electrode prepared by the pretreated acetylene black is 0.25 V(vs.Hg/HgO),0.21 V lower than the air electrode with untreated acetylene black when the working current density is 100 mA·cm^(-1).And its lifetime is over 800 h at 80 mA·cm^(-1).The pretreatment of acetylene black for proper time by H_(2)O_(2)is favorable for the stability of the tri-phase reaction interface of air electrode and improvement of its performance.

Evaluation of asphalt-aggregate adhesion using surface free energy theory

In order to take a precise and objective evaluation on asphalt-aggregate adhesion, this paper analyzed the function at asphalt- aggregate interface using surface free energy theory. Two asphalts and two aggregates were selected and their surface free energy parameters, FLW, F and F-, were measured by the Wilhelmy plate method and the column wicking technique, respectively. Then, the resistance to moisture damage of asphalt mixture were predicted using calculated asphalt-aggregate adhesive bond energy and asphalt cohesive bond energy. The results show that moisture damage is a thermodynamically favorable phenomenon. Asphalt with a great acid-base polar component and a low Lifshitz-van der Waals apolar component always exhibits perfect cohesion.

Heat transfer of liquid metal alloy on copper plate deposited with film of different surface free energy

Liquid metal alloys(LMAs) are the potential candidates of thermal interface materials(TIMs) for electronics cooling.In the present work, buffer layers of Ag, Ti, Cu, Ni, Mo, and W were deposited on polished Cu plates by DC magnetron sputtering, the contact angles of de-ionized water and diiodomethane on the buffer layers were measured by an easy drop shape analyzer and the surface free energies(SFEs) of the buffer layers were calculated by the Owens–Wendt–Kaelble equation. Samples were prepared by sandwiching the filmed Cu plates and LMAs. The thermal properties of the samples were measured by laser flash analysis method. The SFE of the buffer layer has a strong influence on the interface heat transfer, whereas the measurement temperature has no obvious effect on the thermal properties of the samples. As the SFE of the buffer layer increases, the wettability, thermal diffusivity, and thermal conductivity are enhanced, and the thermal contact resistance is decreased.

Influence of Rare Earth Composite Phosphate on Surface Free Energy of Ceramic Glaze

Rare earth composite phosphate (RECP) was doped into the ceramic glazes. The contact angle and surface free energy were characterized by the OCA-30 automatism contact angle test system. Through studied the influence of RECP on the surface free energy of ceramic glaze and movement modality of oil on the ceramic glaze in the water, the results show that the ceramic surface free energy increase obviously after dope RECP. Analysis and calculation show that the surface free energy increase mainly profited from the surface hydroxyl groups increase.

Study on the Surface Free Energy of Ground CaO by JGC

CaO formed by decomposing CaCO3 at 1450℃ was ground in a vibrational mill, then the long-time ground sample was reheated at different temperatures. Inverse Gas Chromatography (IGC) was used to measure the variation of the sample’s surface free energy under grinding and reheating. It is concluded that the total surface free energy and the London dispersive component of the surface free energy increases with grinding, while the polar component first increases with grinding, and then decreases , and finally disappears. When the long-time ground sample was reheated, its total surface free energy decreases , among which the London component decreases , but the polar component appears again.

Evaluation of gas wettability and its effects on fluid distribution and fluid flow in porous media

The special gas wettability phenomenon of reservoir rocks has been recognized by more and more researchers.It has a significant effect on efficient development of unconventional reservoirs.First,based on the preferentially gas-covered ability and surface free energy changes,definition and evaluation methods have been established.Second,a method for altering rock wettability and its mechanisms have been studied,surface oriented phenomena of functional groups with low surface energy are the fundamental reason for gas wettability alteration of rock.Third,the effect of gas wettability on the surface energy,electrical properties and dilatability are investigated.Last,the effects of gas wettability on capillary pressure,oil/gas/water distribution and flow are investigated with capillary tubes and etchedglass network models.The gas wettability theory of reservoir rocks has been initially established,which provides theoretical support for the efficient production of unconventional reservoirs and has great significance.

Roughness-dependent wetting and surface tension of molten lead on alumina

Surface roughness is an important factor that affects the wetting of molten metal on ceramics.The effect of surface roughness of the alumina substrate on the contact angle,contact diameter,drop height and surface tension of molten lead was investigated in the temperature range of 923-1123 K.The microstructure of the lead/substrate interface was observed by SEM.The surface free energy of alumina substrates was calculated by the geometrical average method.When the surface roughness of the substrate increased from 0.092 to 2.23μm,the surface free energy increased gradually,ranging from 13.356 to 39.998 mJ/m^(2).The contact diameter of lead droplets decreased from 9.111 to 7.19 mm.The lead drop height increased from 3.41 to 3.85 mm.The contact angle increased from 113.05°to 137.15°.Moreover,the surface depression of the alumina substrate was filled with lead,and no obvious change was observed.The results demonstrated that the wetting of lead drop on alumina substrates was consistent with the Wenzel state.

ANISOTROPY OF (1×1)-SURFACE FREE ENERGIES OF CRYSTALS

The surface free energy (SFE) of (1× 1)-surfaces of crystals, without reconstructionand adsorption, is calculated using a bond-broken mode. In the mode, the potentialenergy of the crystals is treated as a sum of the energies of the bonds connectingpair-wise atoms (u-bonds). The SFE is calculated based on the bond energy and thearea density of dangling bonds which depends on the structure of the surface. Theresults provide a general expression for the SFE in terms of the bond energy (E)and the bond length (do) of the crystal and Miller indices hkl. The anisotropy ofthe SFE is therefore completely determined with the expression. As the examples,considering the nearest-neighboring bonding, the SFEs of sc, fcc, bcc and cth (cubictetrahedral) crystals are discussed, respectively. Wulff plots of bcc and fcc crystalsare then obtained. The equilibrium forms (EFs) of these crystals ave consequentlygot from their Wulff plots, respectively. It is found that the EFs of bcc and fcc arerespectively the rhombic dodecahedron and the truncated-octahedron that are their firstBrillouin zones, respectively.