Papers by Keyword: Spreading

Abstract: River-carried solids, especially during floods, lead to dam sedimentation. Dredging extends dam life, but excess unusable sediment storage threatens the environment. The aim of this work is to investigate the influence of the recovery of calcined mud from Chorfa dam on the physico-mechanical and chemical characteristics of mortars fiber bundles. The sludge is used as a partial substitute for cement by volume at rates of 10%, 15%, 20% and 25%. All test specimens had water / binder (W/B) ratio and steel fibers ratio. Testing programme included measuring the fluidity, ultrasonic pulse velocity test, dynamic modulus of elasticity, flexural and compressive strengths. Compared to the control mortar, the fluidity represented by the diameter of M0, M15 and M25 mixtures decreased by approximately 11%, 14% and 22%, respectively. The compressive strength of M15 increased by 17.4% at 28 days, compared with the control specimen. At 7 days, the ultrasonic speed of the M25 mixture decreases by 1.7% compared to that of M15. The dynamic modulus of elasticity of M20 and M25 increases by 13% and 12% as the age ranges from 2 to 28 days. At 28 days, the flexural strength of the M20 blends increased by approximately 64%.

Abstract: The spreading process of drying and coalescing nanodispersion was simulated using the method of analogies. A mathematical description of the energy processes in the proposed physical model was obtained in the form of a system of differential equations of the first order. A transition function that describes the dynamics of the change in the contact angle when the nanodispersion drop spreads was obtained as a result of solving the system of differential equations. The physical meaning of the transition function coefficients was established. Based on the analysis of the ratio of the transition function coefficients, a theoretical justification for the results of experiments on choosing the optimal amount of desiccant introduced into styrene-acrylic nanodispersion was given.

Abstract: We present a result of a study of reactive wetting of surface of low carbon steel by liquid alloys CuSnBiPbGa, CuSnBiPbIn and CuSnBiInCd of equiatomic composition. Dependences of contact angle and spot diameter of wetted surface on temperature and time were studied. Liquid alloy CuSnBiPbGa begins wetting of surface of steel at 900 °C; spreading rate at higher temperatures increased by 8 times. Liquid alloy CuSnBiPbIn begins wetting surface of steel at 780°C, but spreading speed is almost unchanged with the further increase in temperature. Liquid alloy CuSnBiInCd begins wetting of surface of steel at a temperature of 570°C, and spreading is in a flash in nature. We studied microstructure and chemical composition of diffusion layers, formed at the spreading of liquid alloys of equiatomic composition CuSnBiPbGa, CuSnBiPbIn and CuSnBiInCd on steel surface. In all experiments at boundary with substrate a ductile transition layer of a solid solution of iron-based is formed. The thickness of diffusion layer side depends on the alloy composition. The widest diffusion layers formed for alloy CuSnBiInCd, and the most narrow - for alloy CuSnBiPbGa. We detected in segregations of copper and gallium atoms for bimetallic sample "CuSnBiPbGa+steel", of copper and tin atoms for samples "CuSnBiPbIn+steel" and "CuSnBiInCd+steel" in diffusion layers. The results of these studies have significance for the design of soldering technology and application of protective coatings on steel products.

Abstract: In this paper, in-situ wetting and spreading behaviours of the binary Sn-Ti alloys with Ti contents were investigated on poly-crystalline CVD diamond plates. The variation of contact angles at increasing temperatures indicated the wettability of Sn-Ti alloys were strongly influenced by the Ti contents. Addition of small amount of Ti (0.5 wt.%) dramatically reduced the contact angle of Sn-Ti alloys; while a relatively high Ti concentration (above 4 wt.%) induced the formation of large refractory intermetallics phase, which reduced the fluidity and impeded the spreading of Sn-Ti alloys.

Abstract: There is the need to determine the process capability of available and novel carbon fibre (CF) roving with minimal material and reproducible procedures in the field of research and development of continuous fibre reinforced composites and structural components, as well as to identify the power delivery in thermoplastic laminate constructions. The innovative TFW procedure with the appropriate system technology allows the production of piece size variable unidirectional (UD) prepreg in a continuous sequential process of spiral winding. A flexible surface design, resulting in the partial fixation of a single highly spread CF roving on fine nonwoven fabric. By defined accumulating of composite components, the fibre volume content (FVC) is adjustable and correspond to the level of spreading and to the grammage of nonwoven fabric. Minimum single layer thickness promote compound homogeneity and thereby allow the generation of greatest possible degrees of freedom in load-oriented structural design of CF-reinforced thermoplastic lightweight products in the laboratory staff.

Abstract: A two-dimensional nonstationary model of calculation of heat transfer at viscous fluid droplet spreading over the heated substrate is presented. A process of the fixed droplet spreading over a simple geometry substrate has been calculated. A hydrodynamic picture of the process of spreading has been obtained. The influence of the parameters of the model on the nature of spreading has been studied. The temperature profiles at the droplet surface have been obtained. The setting time of the stationary mode has been evaluated.

Abstract: This article presents the phisicochemical propreties of aluminium brings a lot of difficulties during soldering one of tchem is low melting point. The work also presents results of mechanical and metallographic investigations. Structural examination was performed by means of light microscopy and mechanical properties with the aim of shear strength test. On the basis structural investigation joints made with Zn and Zn with Ti addition indicated possibilities of reinforcement of soldered joint of aluminium

Abstract: Based on the extended Huygens-Fresnel principle, taking the partially coherent sinh-Gaussian (ShG) beam as a typical example of partially coherent beams, the analytical expressions for the root mean square width and angular spread of partially coherent ShG beams in atmospheric turbulence along a slant path are derived, and used to study the influence of propagation path on the propagation of partially coherent ShG beams in atmospheric turbulence. It is shown that the spreading of partially coherent ShG beams along a horizontal path is larger than that along a slant path in atmospheric propagation. The influence of atmospheric turbulence along a slant path on the partially coherent ShG beams propagation is smaller than that along a horizontal path. Therefore, the slant path is more beneficial to the beam propagation through atmospheric turbulence in comparison with the horizontal propagation. The validity of our results is interpreted physically. Results in this paper may provide potential applications in free-space optical communications.

Abstract: The present paper used MATLAB digital image processing technology to solve the spreading images occurred by surfactant drop spreading on a liquid film, which to obtain the spreading area very well. Based on analysis of spreading index, it is indicated that the results obtained by present paper is basically agreement with those gained by other researchers, which shows that the method of digital image processing is able to meet the requirements of experiment image analyzing entirely.

Abstract: The spreading of a liquid on a solid surface is very important in a number of practical applications. Many interesting physical phenomena can be observed when a small drop of a fluid spreads on a solid surface. These phenomena are related to spreading dynamics, which can be classified as spontaneous and forced wetting. In this work spreading dynamics of liquid metals and solders alloys were established to determine the mechanism of spreading. The spreading dynamics of bismuth, tin, 99.3wt%Sn-0.7wt%Cu alloy, 99.8 wt%Bi-0.2wt%Cu alloy and 60wt%Sn-40wt%Pb were studied by using sessile droplet method. Tests were carried out at a temperature range from 280oC to 350oC over a copper substrate. Results showed a discontinuous decrease of spreading velocity as a function of time. For example, spreading velocity of liquid tin at 320oC decreased from 234.86 mm/s at 0.0025 s to 4.62 mm/s at 0.0225 s, after that increased up to 9.24 mm/s at 0.025 s, then down back to 6.07 mm/s at 0.03 s, and finally reached to the end of spreading after 0.04 s.