• Transactions of Materials Processing
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• v.29 no.6
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• pp.307-315
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• 2020

The cemented carbide and stainless steel were bonded using a hot-vacuum brazing method to analyze the bonding interface. Since it is suitable for the hot vacuum brazing, nickel metal was used as a binder among the main components of the cemented carbide, and a new cemented carbide material was developed by adjusting the alloy composition. The paste, which is one of the important factors affecting the hot vacuum brazing bonding, was able to improve brazing adhesion by mixing solder as Ni powder and a binder as an organic compound at an appropriate ratio. Division of the stainless steel yielded a dense brazing result. This study elucidated the interfacial characteristics of wear-resistant parts by bonding stainless steel and cemented carbide via hot vacuum brazing.

• Korean Journal of Materials Research
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• v.17 no.3
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• pp.142-146
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• 2007

Vacuum brazing method has been coming to an important process as one of the new fabricating techniques of metals and alloys. In this study, a vacuum brazing of SUS304 stainless steel with BNi-2 filler metal was carried out in $1{\times}10^{4}$ Torr of vacuum atmosphere. The formation of brittle intermetallic compounds in brazed joints between SUS304 stainless steel and BNi-2 filler metal is a major concern, since they considerably degrade the mechanical properties of joints. To obtain enough stable joining strength, it is necessary to understand the unique properties of brazing process with Ni-based filler metals containing boron. So, in this research we investigated the performance of SUS304/BNi-2 brazed system and the brazed joint properties were evaluated at room temperature by using tensile test. Metallurgical and fractographic analysis were used to characterize the microstructure, the mechanisms of brazing, and joint failure modes.

• Korean Journal of Materials Research
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• v.17 no.3
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• pp.179-183
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• 2007

A plate heat exchanger (PHE) normally uses vacuum brazing technology for connecting plates and fins. However, the reliability of high temperature brazing, especially with nickel-based filler metals containing boron the formation of brittle intermetallic compounds (IMCs) in brazed joints is of major concern. since they considerably degrade the mechanical properties. This research was examined the vacuum brazing of commercially SUS304 stainless steel with BNi-2 (Ni-Cr-B-Si) filler metal, and discussed to determine the influence of brazing temperatures on the microstructure and mechanical strength of brazed joints. In the metallographic analysis it is observed that considerable large area of Cr-B intermetallic compound phases at the brazing layer and the brazing tensile strength is related to removal of this brittle phase greatly. The mechanical properties of brazing layer could be stabilized through increasing the brazing temperature over $100^{\circ}C$ more than melting temperature of filler metals, and diffusing enough the brittle intermetallic compound formed in the brazing layer to the base metal.

• Transactions of the Korean Society of Mechanical Engineers
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• v.12 no.5
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• pp.1083-1091
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• 1988

Vacuum brazing is the most modern brazing process and is at present, far from being completely understood. By brazing under high vacuum, in an atmosphere free of oxidizing gases, a superior product with greater strength, ductility and uniformity can be obtained. In this study, the influence of brazing parameters such as base metal characteristics, joint clearance and brazing time were described in relation to the metallurgical phenomena and shear strength of vacuum-brazed joints between carbon steels and 304 stainless steel (SUS 304) brazed by copper filler metal. In copper brazing of SUS 304 to a medium carbon steel(M.C.S) the columnar Fe-Cr-Ni-Cu-C alloy structure was formed and grew from the M.C.S side and at the same time, the surface of M.C.S. was decarbonized. The driving force for the formation and growth of columnar structure was the difference of carbon content between base metals. As the joint clearance is narrower and brazing time is longer, the formation and growth of columnar phase and decarburization of carbon steels were more noticeable. Because of decarburization of carbon steels, the shear strength of brazed joints were reduced as the formation of columnar structure was increased.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.1307-1308
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• 2006

The purpose of this study was to examine the interfacial reaction between diamond grits and Ni-based, Ag-based, brazing filler metal, respectively. The morphology of the interface between diamond grits and Ni-based, filler metal exhibited a very good condition after this heat treatment. Cr-carbide and Ni-rich compounds were detected by XRD analysis in the vicinity of the interface between diamond grits and Ni-based, filler metal after vacuum induction brazing. Chromium carbide is considered to play an important role in the high bonding strength achieved between diamonds grits and the brazing alloy.

• Proceedings of the KWS Conference
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• 2005.11a
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• pp.195-197
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• 2005

An intermediate heat exchanger(IHX) is a key component in a next-generation VHTR with process heat applications such as hydrogen production and also for an indirect gas turbine system. Therefore, high temperature brazing with nickel-based filler metal(MBF-15) was carried out to study the joining characteristic(microstucture, joining strength) of nickel-based superalloy(Haynes 230) by vacuum brazing. The experimental brazing was carried out at the brazing process, an applied pressure of about 0.74Mpa and the three kinds of brazing temperatures were 1100, 1150, and $1190^{\circ}C$ with holding time 5 minute. It's joining phenomena were analyzed by optical microscopy and scanning electron microscopy with EPMA. The results of microstructure in the centre-line region of a joint brazed with MBF-15 show a typical ternary eutectic of v-nickel, nickel boride and chromium boride.

• Proceedings of the KWS Conference
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• 1996.05a
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• pp.51-54
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• 1996

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2006.05a
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• pp.23-27
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• 2006

Brazing Failure has been occurred in the process of thrust chamber assembly. The possible factors have been analyzed by sample tests. The actual causes of 'Overflow' phenomenon have been investigated horn Brazing Material and fabrication of Piece Parts. The rejection rate of process has been improved by appling this results to a real brazing process.

• Proceedings of the KWS Conference
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• 2002.10a
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• pp.555-560
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• 2002

Brazing of Al to Cu using AI-Si-Mg-Bi brazing alloy has been carried out in the vacuum furnace. In the bonded interlayer, there were two kinds of intermetallic compounds. One of these intermetallic compounds was e phase and the other was b phase. The growth of b phase was controlled by diffusion Al into Cu. Deformation behavior of Al-Cu brazing joint was brittle without deformation of the base metal. Shear strength of the joint was only about 20MPa. The shear specimen broken in the intermetallic compound, which was mainly e phase. Shear strength did not depend on the bonding temperature.

• Proceedings of the KWS Conference
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• 2005.06a
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• pp.48-50
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• 2005

Advanced hard materials based on diamond are in common use. In this study our main goal was employed to analyze, the mechanisms for the rich phases and chromium carbide, interface of a diamond grits brazed to a Ni-based brazing filler metal matrix. When Ni-7Cr-3Fe-3B-4Si (wt. %) was utilized as the brazing alloy, an isothermal holding resulted in the various products(Ni-rich/Cr-rich domains, carbide). According to these results, the chemical compounds and chromium carbides products is considered to play an important role in brazing temperature and time. Especially chromium carbide has an influence on brazing junction properties.