Brazing Interface Research Articles

Torch brazing 3003 aluminum alloy with Zn—Al filler metal

Using Zn—Al filler metal with Al content of 2%–22% (mass fraction) and improved CsF–AlF3 flux, wetting properties of Zn–Al filler metal on 3003 Al substrate were investigated. The mechanical property as well as the microstructure of the brazed joints was also studied. The results indicate that excellent joints can be produced by means of torch brazing when the Al content is less than 8%. The metallographic structure in the brazing seam is mainly composed of Al based solid solutions and Zn based solid solutions. The high hardness value of brazing seam of the 3003 aluminum alloy is higher than that of the base metal due to the effect of solid solution strengthening. The results also show that three microstructure zones could be found at the brazing interface; i.e., base metal, diffusing zone and interface zone. The distribution of the solid solution in the brazing seam is the main factor of the tensile strength rather than the diffusion zone width near the interface.

G040013 活性金属ろうを用いたNi基耐熱料合金とC/C複合材料のろう付([G04001]機械材料・材料加工部門一般セッション(1))

Carbon/carbon composites plate is brazed to Ni-base super alloy, Inconel 600 using Fe-Cr base brazing filler. The Fe-Cr base brazing filler slurry was pasted on the C/C composites surface. The brazed surface of C/C composites was the cross section of laminates to make the residual thermal stress induced by the mismatch in the coefficient of thermal expansion. The brazing temperature was 1,050°C and the keeping time was 300s. The cooled specimen had crack just below the brazing interface inside of C/C composites. But the observation of microstructure revealed the sound bonding between the brazing filler layer and C/C composites. The Ni-base super alloy seemed to experience the dissolve and solidification process during the brazing. The diffusion of P in the Fe-Cr base alloy took the major role in formation of the microstructure.

Characterization and Performance of Monolayer Brazed Polycrystalline CBN Abrasive Tools

Brazing experiments of polycrystalline CBN abrasive grains and AISI 1045 steel matrix using 95(72Ag-28Cu)-5Ti (wt.%) filler alloy were carried out at the heating temperature of 900 °C for the dwell time of 8 min. The microstructure of the brazing interface among PCBN grain, Ag-Cu-Ti alloy and steel matrix, was characterized with optical microscope, scanning electron microscope and X-ray diffraction equipment. Grinding performance of the brazed polycrystalline CBN abrasive tools was evaluated experimentally by comparison with monocrystalline CBN counterparts. The results show that the reaction layer between polycrystalline CBN abrasive grain and Ag-Cu-Ti filler layer consists of the compounds of Ti-nitride, Ti-borides and Ti3AlN. The resultants have played an important role in terms of strong chemical joining at the grain-filler interface. The brazed abrasive tools with polycrystalline CBN grains have given higher material removal rate and longer service life than that with monocrystalline CBN ones.

Microstructure characteristics of CBN/steel joints brazed with TiB2 modified active filler

The joint of cubic boron nitride (CBN) grits to 0·45%C steel were obtained by using TiB2 modified Ag–Cu–Ti active filler at the brazing temperature of 920°C for the holding time of 5 min. The microstructure characteristics of the brazing interface were detected by means of optical microscope, scanning electron microscope, energy dispersion spectrometer, X-ray diffraction and microhardness measuring equipment as well. It has been found that the microstructure of Ag–Cu–Ti filler layer is significantly refined by TiB2 particles. The almost well proportioned distribution of TiB2 particles in the filler layer is realised. Negative influence of TiB2 particles has not occurred on the chemical reaction of CBN particles and the filler at elevated temperatures. Reliable joining of CBN grits to 0·45%C steel is accomplished dependent on the resultant reaction products at the brazing interface.

Crack analysis near vacuum brazing interface of Cu/Al dissimilar materials using Al–Si brazing alloy

The present paper concentrates on the factors inducing cracking near the Cu/Al vacuum brazing interface using Al–Si brazing alloy. Various analysis and test methods were adopted to analyse the cause of the cracking. Experiment results indicated that two intermetallic compounds layers – δ phase and θ phase – were formed near the interface of Cu and brazing seam region. The microhardness of both the two intermetallic compounds phases reached 720 and 510 HM respectively. The brazing seam region consisted mainly of θ phase and α-Al (Cu) solid solution. Si presence had led to obvious zone liquation in the brazing seam region. Stress concentration appeared on the margin and edge region of the joint. The crack initiated on the θ phase layer, and then extended towards the brazing seam region and δ phase layer. The separation in the θ phase had an obviously brittle fracture surface.

Fusion-brazing Joining for Dissimilar Metals Between 5A02 Aluminium Alloy and Zinc-coated Steel Based on Laser-MIG Hybrid Welding

High efficiency and quality fusion-brazing joining between 5A02 aluminium alloy and zinc-coated steel sheet, based on laser-MIG hybrid welding, is successfully done. The seam appearance and the mechanical properties as well as the microstructures of the joints are analyzed. The results indicate that a high speed fusion-brazing joining can be achieved with this welding method, and the highest welding speed is up to 5 m/min. A brazed joint between the aluminium alloy and the steel is formed, and the steel sheet under the seam is not melted. The top tensile strength of the joint is 153.1 MPa, about 75.7% of that of the aluminium alloy base metal. It is almost as high as that of the aluminium alloy’s fusion joint. In tensile test, the specimen fracture is in the heat-affected zone of aluminium aside. It can be sure that the main fracture form of the joint is ductile fracture, but has the trace of brittle fracture. The analysis on the microstructure of joint shows that a thin intermetallic compound layer is generated on the brazing interface, but its average thickness is only about 1.51 μm. It’s confirmed that the compound layer is composed of Fe3Al, FeAl2, Fe2Al5 and FeAl3, and the zone of these intermetallic compounds abounds in silicon.

Mechanical Property and Corrosion Resistance Evaluations of Ti-6Al-7Nb Alloy Brazed with Bulk Metallic Glasses

Exploitation of metallic glass as new brazing filler for Ti-based biomedical alloy was attempted. Ti-6Al-7Nb was used as a brazed material, and candidates of bulk metallic glass brazing filler were Cu60Hf25Ti15, Mg65Cu25Gd10, Zr55Cu30Al10Ni5 and Pd40Cu30P20Ni10. Convergence infrared-ray brazing was conducted for brazing Ti-6Al-7Nb/metallic glass in Ar atmosphere. After brazing, hardness measurement, X-ray tomography, cross-sectional observation, artificial saliva immersion test and tensile test were performed to evaluate brazability, mechanical property and corrosion resistance of the obtained brazing joints. The results of brazing using these metallic glass fillers show that all the metallic glasses were brazable to Ti-6Al-7Nb except for Mg65Cu25Gd10. Mg65Cu25Gd10, Cu60Hf25Ti15 and their joints collapsed rapidly during immersion test. Zr55Cu30Al10Ni5 joint was the best in terms of degradation resistance; however, tensile strength was inferior to the conventional one. Pd40Cu30Ni10P20 filler and Zr55Cu30Al10Ni5 filler and their joints did not show any collapse or tarnish during the immersion test. Pd40Cu30Ni10P20 joint showed the excellent properties in terms of both corrosion resistance and tensile strength, which were superior to a joint brazed using Ti-15Cu-25Ni conventional filler. X-ray tomograph indicates that fracture tends to occur in the vicinity of the brazing interface after tensile test. The brazed metallic glass fillers were fully crystallized, excludingmore » Pd40Cu30Ni10P20 filler. Pd40Cu30Ni10P20 brazed filler contained mapleleaf like primary dendrite, peritectoid and a few microns interfacial reaction layer in glassy matrix. The results indicated that Pd40Cu30Ni10P20 is promising brazing filler for dental or biomaterial devices.« less

Form and Distribution Characterization of Reaction Products at the Brazing Interface Between Ni-Cr Alloy and Diamond

Form and Distribution Characterization of Reaction Products at the Brazing Interface Between Ni-Cr Alloy and Diamond

Vacuum brazing technology and microstructure near the interface of Al/18-8 stainless steel

The microstructure performance for vacuum brazing interface of Al/18-8 stainless steel was studied by means of SEM, micro-hardness test and X-ray diffraction (XRD). The test results indicate that the adhesion brazing interface is excellent, there is no porosity or crack near the interface. The microstructure of the brazing joint is mainly composed of equiaxial and column crystal. The fracture morphology of the brazing joint consists mainly of a coarse and gray fiber-shape fracture, and the fracture is mainly the mixed fracture of toughness and cleavage. The brazing interface consists of δ (Al, Fe, Si) and α-Al (Si), without obvious brittleness phase of the high hardness.

Microstructure and XRD analysis in the brazing zone of a new WC–TiC–Co hard alloy

The microstructure and phase constituent near the brazing interface of a new WC–TiC–Co hard alloy was investigated by means of a scanning electron microscope, X-ray diffraction and an electron probe microanalysis. Test results indicated that the brazing joint with the interface combined excellently and can be obtained by using a Cu–Zn–Ni brazing filler alloy and by controlling the technology parameters. The microstructure of the brazing filler alloy is α+β eutectic. The brazing interface consists of WC, TiC, CuZn (α phase), and α-Co phase. There are no micro defects (such as microcracks, inclusions, etc.) near the interface.

Oxidation resistance and phase constituents in the brazing interface of WC–TiC–Co hard alloys

The oxidation resistance and phase constituents in the brazing interface of WC–TiC–Co hard alloys have been researched by means of brazing inside a furnace, the scanning electron microscope (SEM) and the X-ray diffraction test, etc. The test results have indicated that a brazing joint in which the interface combines excellently can be obtained by using Cu–Zn–Ni brazing filler alloy, and controlling the heating temperature to 940–960 °C and the holding time 10–15 min employing a suitable post-heat measure. The interface of the hard alloy and the brazing filler alloy is in a good condition. The interface zone consists of WC, TiC, and CuZn (α-phase). There are no micro-cracks, inclusions, etc., near to the brazing interface. The interface zone is formed by the mutual diffusion of elements in the hard alloy and the brazing alloy under the condition of high temperature.

A study on microstructure in the brazing interface of WC–TiC–Co hard alloys

The brazing parameters and microstructure in the interface of WC–TiC–Co hard alloy and the brazing filler were investigated by means of inside-furnace brazing, scanning electron microscopy (SEM) and X-ray diffraction. Test results indicated that the brazing joint with which the interface combines excellently can be obtained by using Cu–Zn–Ni brazing filler alloy and controlling the heating temperature 940–960 °C, the heat preservation time 10–15 min and a suitable cooling. The crystal microstructure of the brazing filler alloy is α+β eutectic. The interface microstructure of the hard alloy and the brazing filler alloy distribute evenly. The interface zone consists of WC, TiC, CuZn (α-phase). There are no microcracks, inclusions, etc. nearby the interface. The interface zone is formed by mutual diffusion of the hard alloy and the brazing filler alloy under high temperature.

Fabrication and Thermal Cycle Testing of a First Wall Mock-Up for ITER Baffle Blanket Module

The objective of this study is to develop joining technology of a plasma facing CFC armor and DSCu heat sink by means of Ag-free brazing and to evaluate its performances under repeated high heat flux. For fabrication of a baffle first wall (FW) composed of dispersion strengthened copper (DSCu) as heat sink and carbon fiber composite (CFC) as amor material, a two-step brazing has been proposed. CFC armor tiles were joined to an oxygen free copper (OFCu) plate in the first step and the OFCu plates joined, in turn, to the DSCu heat sink in the second step. After screening tests, brazing materials of Cu-Mn and Al were selected for the first and the second steps, respectively. A small scale baffle FW mock-up of 400 mm in length, 49 mm in width and 52 mm in thickness was successfully fabricated. By destructive test of a piece with the same materials bonded under the same condition as the mock-up, bondability at each brazing interface was confirmed. Thermal cycle tests were performed with the fabricated mock-up. Test conditions were selected based on thermo-mechanical analyses to simulate the temperature at the brazing interface under ITER operation condition and also higher temperatures with higher heat fluxes for acceleration of thermal cycle tests. The mock-up withstood more than 4600 cycles with heat fluxes of 5–10 MW/m2. From results of the thermal cycle tests, the integrity of CFC/DSCu interface was demonstrated.

Transference of Electric Charge at the Interface between Stabilized Zirconia Ceramics and Brazing Filler Containing Titanium

Electrochemical methods were used along with brazing stabilized zirconia ceramics in order to investigate the reaction behavior between the ceramics and reactive metal titanium added to the silver-copper eutectic brazing filler. A 10 Hz, 5 V rectangular wave signal was applied to a brazing specimen and a comparative specimen, which consists of stabilized zirconia ceramics in order to compare each output signal. The output signals were observed during the brazing process using a digital storage oscilloscope. When the brazing filler foil began to melt, the waveform of the signal from the brazing specimen became sloped. The gradient of the slope was large at the beginning. As the brazing time proceeded, the gradient of the slope gradually decreased. It was suggested that the electric double-layer was formed at the brazing interface by titanium positive ions and oxygen negative ions, and that the capacitance of the layer was gradually decreased with the growing reaction layer. It was considered that titanium positive ions and oxygen negative ions are combined to form an electrical neutral reaction layer. These experimental results were analyzed from the point of view of transient phenomena in electric circuits. Calculation results agreed with the decreasing capacitance of the electric double-layer.

Relationship between wettability and interfacial reaction for Sn10Ag4Ti on Al 2O 3 and SiC substrates

Sn10Ag4Ti filler metal possesses the advantage of low thermal stress for active brazing of ceramics. In order to clarify its brazing mechanism, the wettability and interfacial reactions for such an active filler metal on Al 2O 3 and SiC ceramics substrates were evaluated. It was shown that the contact angle of Sn10Ag4Ti on both ceramics decreased with the increase of temperature and heating time. The wettability of Sn10Ag4Ti on SiC substrate was superior to that on Al 2O 3 substrate. For all cases with better wettability, Ti was also found to aggregate more strongly at the brazing interface. In summarizing these results, it can be concluded that the wetting tendency of Sn10Ag4Ti on Al 3O 3 and SiC ceramics is decided by the interfacial reaction of Ti in the filler metal with the ceramic substrates.

Ａｇ‐Ｃｕ‐Ｔｉ系ろうによるルビーの侵食現象 人工ルビーと金属の接合に関する研究 第２報

The behavior of elements composing ruby and brazing filler metals at the brazing interface was examined by EPMA, and the construction of reaction layer formed at the brazing interface was examined by X-ray diffraction method, in order to investigate the corrosion phenomina of ruby by active metal brazing filler (Ag-Cu-Ti). The corrosion depth of ruby brazed under various conditions were evaluated by measuring surface roughness, in order to examine the relation between the corrosion depth of ruby and brazing condition.The examination of brazing interface by EPMA showed that the reaction layer was constituted by two distinct layers with different titanium content. According to the X-ray diffraction method, the reaction layer formed adjacent to ruby was mainly constituted with TiO. Aluminum made from corroded ruby diffused outside of TiO-layer and formed the secondary reaction layer constituted by Ti3AI, Cu2Ti4O, AICu and CuxTiy. These experimental results showed that ruby was reduced by titanium contained brazing filler metal. According to the corrosion test using Ag-Cu-4 mass%Ti, the isothermal corrosion depth of ruby increased proportional to square root of brazing time in the temperature range of 1123 K to 1223 K. The temperature dependence of the rate constants fits an Arrhenius equation yielding activation energies of 224.2 kJ/mol.

Monitoring of Reactive Metal’s Diffusion and Reaction at Ag–Cu–Ti/ZrO<SUB>2</SUB> Brazed Interface

Under the aim to monitor the segregation and the reaction of reactive metal at the brazing interface with ceramics in situ, the electrochemical method was tried to detect the formation of the reaction layers between reactive metal in brazing filler metal and oxygen in ceramics. The transition of monitoring voltage Vm(t) was composed of two stages. It was suggested that the formation of the first stage was attributed to the segregation of reactive metal to stabilized zirconia, and that the formation of the second stage was attributed to the formation of reaction layers between reactive metal and oxygen of ceramics. The reaction between the segregation layer and oxygen of ceramics depended on the potential and the frequency of power supplier. Titanium oxide layers with various proportion of titanium to oxygen from 1:1-x 1 1:1, 1+y:2 to 1:2 were detected by SEM/EDX analysis.

ルビー／Ａｇ‐Ｃｕ‐Ｔｉ系ろう界面に形成される反応層と接合強度

Synthetic ruby has been brazed to molybdenum rod using Ag-Cu eutectic filler including active metal of 1-8 mass%Ti, in order to investigate on the relation between the brazing condition and the bonding strength.The strength of the joint was evaluated by tensile test and the brazing interface was examined by SEM and EPMA.According to the tensile test, bonding strength of the joint brazed with 1 mass%Ti-Ag.Cu was less than 20 MPa independent on bonding temperature. Anotherside, bonding strength of the joint brazed at 1123 K-1173 K using 2-8 mass% Ti-Ag.Cu, was more than 100 MPa, and above 1223 K, it was reducing with raising of brazing temperature. Especialy the bonding strength of joint brazed at 1223 K using 8 mass%Ti-Ag.Cu showed remarkable reduction.The examination of brazing interface by SEM and EPMA showed that ruby was corroded by brazing filler and reaction layer composed by Ti, Cu, Al and 0 was formed at bonding interface. According to the corrosion test, raising the brazing temperature and increasing the Ti content in the brazing filler hasten the corrosion of ruby.Wiht advancing of ruby corrosin, Al and O made from corroded ruby diffused into the reaction layer and the content of these elements increased in this area. These experimental results showed that bonding strength of joint was reducing with advancing of ruby corrosion at brazing interface.This suggests that advancing of ruby corrosion at bonding interface brings the brittleness of reaction layer and the bonding strength is reducing.Anotherside, the preferential movement of Ti to bonding interface was hasten with advancing of ruby corrosion and it was assumed that the movement of Ti to bonding interface was concern to ruby corrosion.

Active Brazing Alloy Containing Carbon Fibers for Metal–Ceramic Joining

The addition of 8.4 vol% short metal‐coated carbon fibers to an active brazing alloy increased the debonding strength of metal/ceramic joints by 18% to 28%. The carbon fibers helped to strengthen the brazing alloy and to decrease slightly the thermal stress at the brazing interface. The carbon fibers were either uniformly distributed in the brazing layer or concentrated near the ceramic side of the metal/ ceramic brazing interface. The latter resulted in a lower thermal expansion in the part of the brazing filler near the ceramic arid gave superior joints such that the debonding occurred in the part of the brazing filler without carbon fibers. The titanium in the active brazing alloy was segregated at the interfaces between the brazing filler and the ceramic, between the brazing filler and the metal (steel), and between the carbon fibers and the matrix of the brazing filler. The amount of titanium at the interface between the brazing filler and the ceramic was smaller when carbon fibers were present in the brazing filler. Titanium segregation at the fiber–matrix interface was also observed when bare carbon fibers instead of metal‐coated fibers were used. The bare carbon fibers gave joints comparable in quality to the metal‐coated carbon fibers. The carbon fibers also served to lower the cost of the brazing material.

Neutron diffraction study of internal stresses in brazed [formula omitted] divertor structures for NET/ITER

This contribution presents the first results of a study, performed by neutron diffraction, on the internal stresses remaining after brazing at 860°C in graphite/molybdenum samples developed for NET/ITER. Samples of polycrystalline graphite and a carbon-fiber composite are considered. The deformation field is characterized close to the brazing interface, within a linear spatial resolution of approximately 2 mm. The results are discussed with reference to those obtainable by other methods and to theoretical considerations.