Papers by Keyword: Reactive Wetting

Paper TitlePage

Authors: Chihiro Iwamoto, Shunichiro Tanaka
Abstract: In-situ HRTEM technique was applied to various substrates and the reaction processes between substrates and molten alloy were compared. Substrates used were SiC, Si3N4, Si wafers, an amorphous carbon film, and a carbon nanotube. Ti-containing Ag-Cu eutectic alloy foil was placed on the substrate and the combined specimen mounted on the heating holder of an HRTEM and heated in the microscope to melt the alloy foil. In the case of SiC, Si3N4, carbon materials, the molten alloy spreading on the substrates were observed after melting of the alloy. SiC polar plane nano-steps appeared with the SiC dissociation by the molten alloy. On the surface of the carbon nanotube, thin film precursor spreading was observed. In contrast, Si reaction with the molten alloy produced big holes at the contacted area and molten alloy spreading was not observed.
83
Authors: Xuan Mao Liao, Ding Yi Zhu
Abstract: Mercury-stannum reactive wetting behaviors were studied by the sessile drop technique at room temperature, and wetting surface and interface were also studied respectively by methods of field emission scanning electron microscope (FESEM) and XRD. It showed that mercury droplets wetted completely on the stannum substrate, on whose surface up-and-down cellular structures were generated, and two metallographic microstructures of intermetallic compounds, Hg0.1Sn0.9 and Hg1.25Sn8.75, were produced in wetting interface.
1909
Authors: W. Tillmann, Jan Pfeiffer, L. Wojarski
Abstract: Despite the fact that active brazing is a suitable and well-established method to join ceramics to each other and to metals, issues concerning possible influences on the wetting properties of the used filler alloys are not yet entirely clarified. It is well known that process parameters such as the temperature, the surface roughness of the ceramic, and the atmosphere during wetting influence the wetting angle and the spreading kinetics of the molten filler metal. However, a quantitative description of these influences is still missing.This study closely investigates the isolated effects of the temperature, the surface roughness of the ceramic, as well as the atmosphere on the wetting of Ag-Cu-Ti and Cu-Sn-Ti on silicon carbide. In order to evaluate the effects of the considered factors as well as their interdependencies, a multivariate statistical approach is employed and a linear regression model for both, the contact angle and the spreading area, will be derived. Besides quantitative measurements of the contact angle on solidified sessile drops, microstructural and chemical aspects will be discussed and connected to the results of the wetting experiments as well. By these means, valuable information can be obtained, which lead to a profound understanding concerning changes of the wetting behavior. Furthermore, the study allows a comparison of measurements carried out using varying experimental conditions.
172
Authors: F. Hodaj, J.N. Barbier, Andreas Mortensen, Olivier Dezellus, N. Eustathopoulos
91
Authors: Shun Ichiro Tanaka, Chihiro Iwamoto
Abstract: Nanoscale singularity at the reactive wetting front on SiC (0006) was studied using video recorded in situ to clarify the dynamic atomistic behaviours of the brazing and the molten tip spreading on a high-temperature stage of a high-resolution transmission electron microscope. An atomistic process controls the wetting at the front of the spreading film where the classical macroscopic phenomenon never holds true and the singularities are observed in a precursor film. A 0.5-nm-thick precursor film spreading ahead of the main molten alloy on SiC (0006) at 1073 K and continuous spreading of the molten alloy were clearly observed on the SiC (0006) surface with a less than 1-nm-thick amorphous layer. Molten Ti and TiC nanolayers preceded the Ti5Si3 nanolayer at the tip and they traveled continuously at a velocity of 14 nm/sec on the plane perpendicular to SiC (0006). Since Ti atoms in the molten alloy diffuse sufficiently rapidly on the SiC surface to the tip, the formation of these layers may be the rate-determining step of spreading. Discontinuous spreading of the precursor tip on SiC (0006) with a thick amorphous film was observed in contrast to the continuous spreading on SiC with a thin film. This suggests that the spreading of the Ti molten alloy on SiC is also controlled by the dissolution of the amorphous layer.
269
Authors: Shun Ichiro Tanaka, Chihiro Iwamoto
Abstract: Nanoscale singularity at the reactive wetting front on the 6H-SiC (0006) surface with amorphous oxide layer was studied using video recorded in situ to clarify the dynamic atomistic behaviors of the brazing and the molten tip spreading on a high-temperature stage of a high-resolution transmission electron microscope. A 0.5-nm-thick precursor film spreading ahead of the main molten alloy on SiC (0006) at 1073 K and continuous spreading of the molten alloy were clearly observed on the SiC (0006) surface with a less than 1-nm-thick amorphous layer. Molten Ti and TiC nanolayers preceded the Ti5Si3 nanolayer at the tip and they traveled continuously at a velocity of 14 nm/sec on the plane perpendicular to SiC (0006). Since Ti atoms in the molten alloy diffuse sufficiently rapidly on the SiC surface to the tip, the formation of these layers may be the rate-determining step of spreading. Discontinuous spreading of the precursor tip on SiC (0006) with a thick amorphous film was observed in contrast to the continuous spreading on SiC with a thin film. This suggests that the spreading of the Ti molten alloy on SiC is also controlled by the dissolution of the amorphous layer.
571
Authors: Simeon Agathopoulos, D.U. Tulyaganov, José Maria F. Ferreira
Abstract: A universal model for describing the wetting kinetics at solid/liquid interfaces, where interfacial chemical reaction occurs, is proposed, whereby four distinct stages separated from each other by transition points are anticipated. The stages are described by means of comparing the dimensions of the base of the liquid sessile drop with the evolution of the reaction product forming on the solid/liquid interface, over time.
1801
Showing 1 to 7 of 7 Paper Titles