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1.
The initial rapid wetting of a solid surface by a liquid phase is an important step in many industrial processes. Liquid-phase sintering of powder metallurgical steels is one such industrial process, where metallic powders of micrometer size are used. Investigating the dynamic wetting of a high-temperature metallic drop of micrometer size experimentally is very challenging. Here, a phase-field-based numerical model is first implemented and verified by accurately capturing the initial dynamic wetting of millimeter-sized metal drops and then the model is extended to predict the dynamic wetting of a micrometer-sized metal drop. We found, in accordance with recent observations, that contact line friction is required for accurate simulation of dynamic wetting. Our results predict the wetting time for a micrometer-sized metal drop and also indicate that the dynamic wetting patterns at the micro- and millimeter length scales are qualitatively similar. We also found that the wetting process is much faster for a micrometer-sized metal drop compared to a millimeter-sized metal drop.  相似文献   

2.
ImportanceofLiquidMetal-SolidWettinginModernMaterialsScienceandTechnologyLiJianguo(李建国)(InstitutfurNichtmetallischeWerkstoffe...  相似文献   

3.
Appropriate substrate surface wetting by a molten filler ensures a sound bead profile during brazing. A theory to estimate the wetting length considering gradual cooling of liquid filler and loss in its ability to spread is currently unavailable. We present here a methodology to estimate wetting length based on the minimisation of energy for spreading of a liquid filler considering its gradual cooling and tested the computed results in gas metal arc brazing of galvanised sheets for a wide range of conditions. The computed wetting lengths are used further to estimate bead height and toe angle of joint profile.  相似文献   

4.
Micro metal droplet is the basic building block of three-dimensional metal parts fabricated by micro droplet deposition manufacturing (MDDM) technique. In this paper, the effect of wetting behavior between liquid metal and spray nozzle on the generation of micro aluminum droplets produced by pneumatic drop-on-demand (DOD) technique was investigated by simulation and experiment. A finite element model of liquid–gas flow was established based on the improved level set method (LSM). Then the generation of micro liquid aluminum droplets under different wetting conditions was simulated. A series of spraying experiments were also performed on micro droplet deposition experiment platform. The results show that the generation and flight of micro aluminum droplets are influenced by wetting condition between liquid metal and the nozzle surface significantly. Additionally, the effect of wetting behavior on the droplet size was analyzed to achieve the smallest building block. It was found that the droplet radius decreased with the increase of contact angle exponentially, which agreed with the numerical calculation and experiment results. On this basis, a wettability criterion was proposed for selecting nozzle materials. These works would be helpful for the processing optimization and equipment improvement of MDDM technique.  相似文献   

5.
T. P. Swiler 《Acta Materialia》2000,48(20):4775-4782
We examined the atomistic mechanisms involved in metal-on-metal wetting using an embedded atom method (EAM) silver–copper system as a model of a generic metallic system. In simulations of liquid silver wetting a static copper substrate, the formation of an adsorbed layer of silver on the substrate preceded true wetting. In contrast, no adsorbed layer formed in simulations of liquid copper wetting a static silver substrate. We examined structural correlations in these systems and found that the silver-on-copper system had a more favorable liquid–substrate interaction than the copper-on-silver system. We show that the substrate plus adsorbate represents the equilibrium substrate surface during “moist” spreading treated by the Young equation and we compare the thermodynamics of wetting in these two systems.  相似文献   

6.
作为渗透检测中的润湿现象有三种方式:即粘湿、浸湿和铺展。若渗透液在固体受检试件表面上的接触角θ≤180°,则可发生粘湿;若接触角θ≤90°,则可发生浸湿;若接触角θ≈0°,则可发生铺展。凡能铺展者,必要浸湿,更能沾湿。渗透检测要求铺展。接触角臼的大小是由在气、液、固三种界面张力的大小所决定的。从接触角口数值大小可看出液体对固体润湿的程度。这些讨论有助于对渗透检测中实际问题的认识。  相似文献   

7.
铝液对石墨润湿过程的研究   总被引:2,自引:0,他引:2  
铝-石墨复合材料制造中的突出问题是铝液与石墨的润湿能力很差,为此大多在工艺上采取措施,如石墨表面喷涂Ti-B,Ni或Cu涂层,或采用流变铸造等。然而这些措施使得工艺复杂、成本提高,因而推广应用受到限制。为改善铝液与石墨的润湿能力,有必要深入研究铝液对石墨的润湿过程。国内外这方面报道甚少,而且所报道的结果差别较大。我们通过长时间的保温试验,仔细地研究了不同温度下铝液对石墨的润湿过程,发现了一些新的现象。  相似文献   

8.
检测了工业用Al2O3过滤器和SiC过滤器与液态铝的润湿性并在工厂使用以上2种陶瓷过滤器过滤铝液。实验结果表明:Si C过滤器比Al2O3过滤器更易于润湿液态铝。提高液态铝与过滤器的润湿性有助于铝液透过过滤器,提高夹杂物的去除率,同时,易于去除与铝不浸润的杂质。  相似文献   

9.
The wetting behaviour of titanium carbide by molten nickel was investigated at different oxygen partialpressures by using the sessile drop method.Special attention was paid to the kinetics of wetting.Wettingprocess in the Ni/TiC system is controlled by the dissolution of TiC in the liquid phase.Discussions weremade on the basis of the new experimental results achieved in the present investigation and those given inthe literature for the Ni/TiC system and for some similar metal/carbon systems to elucidate how theinterfacial dissolution reaction influences the wetting process.The reactive wetting process is a complex mat-ter and is very sensitive to the experimental conditions.Implantation of the wetting study in the compositeprocessings was also suggested and the optimum processing is proposed.  相似文献   

10.
The wetting phenomena of molten alloy/ceramic substrate depend on the bonding characteristics of liquid alloys and ceramics as well as on the magnitude of interactive forces at the interface. According to this, the first step of this investigation is to determine the surface properties of Ag–Cu, Ag–Ti and Cu–Ti liquid alloys. The energetics of mixing in liquid alloys has been analysed through the study of surface properties (surface tension and surface composition) and microscopic functions (concentration fluctuations in the long-wavelength limit and chemical short-range order parameter) in the frame of statistical mechanical theory in conjunction with the quasi-lattice theory (QLT). The results obtained for these binary systems have been extended to the ternary Ag–Cu–Ti system. Combining the Young and the Dupré equations, the computed results of surface tension together with contact angle data have been used to calculate the work of adhesion and, in the case of non-reactive wetting, the interfacial tension between the solid substrate and the liquid alloys over the whole concentration range. The evaluation of the interfacial tension values is determined from calculated and measured data using solid surface tension data from literature. These results provide more information on the characteristics of metal–ceramic systems, and are therefore useful in guiding experiments, or in predicting the surface properties of metallic systems with similar characteristics as well as their wetting behaviour in contact with ceramic materials.  相似文献   

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