High Temperature Solid-Liquid Interactions in Metal-Ceramic Brazing: A Critical Review

2017 ◽  
Vol 884 ◽  
pp. 132-165 ◽  
Author(s):  
Alberto Passerone ◽  
Fabrizio Valenza ◽  
Maria Luigia Muolo
Keyword(s):  
High Temperature ◽  
Liquid Phase ◽  
Structural Information ◽  
Liquid Metals ◽  
Basic Step ◽  
Adhesion Properties ◽  
Early Transition Metal ◽  
Metal Ceramic ◽  
Substrate Dissolution ◽  
Solid Liquid

Solid-liquid interactions in metal-ceramic systems are extremely important in high temperature brazing processes. These interfacial phenomena are reviewed here, from both the thermodynamic and microstructural viewpoints. At high temperature, the wetting characteristics and the adhesion properties of the joints are strongly related to the high atomic mobility of the different phases, giving rise to different phenomena, ranging from the dissolution of the ceramic in the liquid phase, reactions, formation of new phases and reprecipitation at the solid-liquid interface. The role phase diagrams in guiding the choice of the filler alloys composition and to optimize the brazing procedures is emphasized. In particular, it is shown that the computation of new diagrams and the critical use of the existing ones is essential to understand how to suppress the substrate dissolution and to interpret the evolution of the system. Experimental data are presented and discussed concerning the interactions between liquid metals with early-transition-metal diborides (TiB2, ZrB2, HfB2) as a typical example involving the joining of Ultra-High Temperature Ceramics (UHTCs). Overall, these studies represent the basic step linking the chemical and structural information to the design of industrial processes involving a liquid phase at high temperature, such as the production of metal-ceramic joints or composite materials to be used in highly demanding applications.

Studying on High Temperature Thermoplastic of High Carbon Steel

2014 ◽  
Vol 809-810 ◽  
pp. 384-389
Author(s):  
Lang He ◽  
Yu Tang
Keyword(s):  
Electron Microscope ◽  
High Temperature ◽  
Melting Point ◽  
Liquid Phase ◽  
Energy Dispersive Spectrometer ◽  
High Carbon Steel ◽  
Optical Microscope ◽  
High Carbon ◽  
Solid Liquid ◽  
Scanning Electron

High temperature thermoplastic of 50Mn2V casting slab was tested by Gleeble-1500 thermal simulator machine. The morphology, microstructure and composition of fracture surfacewere observed and analyzed by optical microscope (OM), scanning electron microscope (SEM) and energy dispersive spectrometer (EDS).The results show that, there are two brittle temperature zones of 50Mn2V casting slab at the temperature of 600~950°C and 1300~1465°C, respectively, The section shrinkaging rate is less than 60%. The fracture mode changes from mixed one dominated by intergranular to toughness transgranular one with the increase of temperature at the range of 600~1250°C. However, the fracture is along with the solid-liquid phase at the range of 1300°C~ melting point.

scholarly journals The Simulation of the Preparation of the Ingot With Liquid Core

2021 ◽  
Author(s):  
yongqiang wu ◽  
Zhi-ren Sun ◽  
Kaikun Wang
Keyword(s):  
Finite Element ◽  
High Temperature ◽  
Liquid Phase ◽  
Solid Phase ◽  
Liquid Core ◽  
Phase Region ◽  
Simulation Results ◽  
Solid Liquid ◽  
Deform 3D ◽  
Ultra High Temperature

Abstract During the preparation of the ingot with liquid core in the early stage, the finite element models of the solidification and the ultra-high temperature demoulding were established in DEFORM-3D. The thermophysical properties of ASSAB 718 with the variations of C, Mn and Cr were calculated in JMatPro®. The material database was imported into DEFORM-3D. Through the analysis of the finite element simulation results, we obtained the influence of three main elements C, Mn and Cr contents on the size of the solid-phase region, the liquid-phase region and the solid-liquid two-phase region in the ingot. We optimized the composition of the material to get a wide solid-liquid phase range. The high carbon, the medium manganese and the high chromium contents were beneficial to form the liquid core. Based on the method of the solidification time, the algorithm was programmed by the python language. We analyzed the influence of the three elements C, Mn, and Cr on the concentration distribution based on the temperature field data, which were obtained by DEFORM-2D after the solidification and the ultra-high temperature demoulding. According to the simulation results, we found that the region prone to negative segregation.

scholarly journals Predicted Effects of Confinement on the Melting Transition in Krypton-Argon Adlayers

2002 ◽  
Vol 1 (1) ◽  
Author(s):  
Karson Bader ◽  
Michael Roth
Keyword(s):  
Molecular Dynamics ◽  
Phase Transitions ◽  
High Temperature ◽  
Liquid Phase ◽  
Computer Simulations ◽  
Melting Transition ◽  
Graphite Sheet ◽  
Solid Phases ◽  
Solid Liquid ◽  
Graphite Sheets

We report the results of (N,ρ,T) Molecular-Dynamics computer simulations of krypton-argon mixtures physisorbed between two graphite sheets. Three novel aspects of the system’s behavior emerge from this study. To begin with, new high-temperature commensurate solid phases for both argon and krypton as a result of confinement are predicted, as well as a family of confinement-induced solid-liquid phase transitions. In addition, we observe that the melting temperature of the system can be adjusted within a given range by the graphite sheet spacing. Finally, in the case of argon-krypton mixtures, certain temperatures and sheet spacings result in almost complete impurity extraction.

Overview on Wetting and Joining in Transition Metals Diborides

2010 ◽  
Vol 64 ◽  
pp. 98-107 ◽  
Author(s):  
Maria Luigia Muolo ◽  
Fabrizio Valenza ◽  
Natalia Sobczak ◽  
Alberto Passerone
Keyword(s):  
Transition Metals ◽  
Sessile Drop ◽  
Structural Information ◽  
Complex Structures ◽  
Filler Alloy ◽  
Wide Range ◽  
Metal Ceramic ◽  
Drop Tests ◽  
Definition Of ◽  
Solid Liquid

The ultra high temperature performance of ceramic-based complex structures may require the development of liquid-assisted joining techniques; this in turn requires the definition of the wettability of these materials by various metals over a wide range of compositions and temperatures. After a short description of the relevant experimental aspects of wettability studies at high temperatures, a discussion is presented on how these results can be used to derive chemical and structural information on the solid-liquid interactions. Reference is made mainly to metal-ceramic systems; a summary of the results of sessile drop tests under carefully controlled conditions is given in relation to the wettability and the interfacial characteristics of systems based on transition metals (Zr, Hf) diboride ceramics in contact with liquid Ag, Cu, Au and Ni and of some of their alloys with Ti, Zr, Hf and B to promote/control wettability. In particular, the utilization of phase diagrams is discussed, as one of the most powerful tool to design the filler alloy compositions for the optimization of joining (brazing) processes.

INFLUENCE OF FORCED CONVECTION IN LIQUID INSIDE THE TIN ON DURATION OF STERILIZATION IN THE COURSE OF FISH PROCESSING

2017 ◽  
pp. 137-144
Author(s):  
Gennadiy Valentinovich Alexeev ◽  
Elena Igorevna Verboloz
Keyword(s):  
High Temperature ◽  
Liquid Phase ◽  
Forced Convection ◽  
Thermal Process ◽  
Processing Time ◽  
Fish Processing ◽  
Study Results ◽  
Equipment Modernization ◽  
Bottom To Top

The article focuses on the process of intensive mixing of liquid phase in the tin during high-temperature sterilization, i.e. sterilization when temperature of the heat carrier reaches 150-160°C. It has been stated that for intensification of the thermal process during sterilization of tinned fish with liquid filling it is preferable to turn a tin from bottom to top. This operation helps to increase the driving power of the process and to shorten warming time. Besides, high-temperature sterilization carried out according to experimental modes, where the number of tin turnovers is calculated, greatly shortens processing time and improves quality of the product. In this case there is no superheating, all tins are evenly heated. The study results will contribute to equipment modernization and to preserving valuable food qualities.

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