Solid State Bonding Research Articles

20-μm-ピッチ・金マイクロバンプの低温固相接合

20-μm-ピッチ・金マイクロバンプの低温固相接合

Solid State Bonding of Carbon Material to Copper with Nickel Insert

Carbon material/nickel/copper system was heated under a compressive stress of 13 MPa in a vacuum at 1073 K for different keeping times, and the bending strength of the joint, the microstructure, hardness and carbon concentration near the joining interface were examined. Thermal stress induced in the joint was estimated by a finite element method. In carbon material/copper system solid state bonding is difficult. However, good solid state bonding becomes feasible when nickel is used as an insert metal. Axisymmetric thermoelastic finite element analysis reveals that the maximum tensile thermal stress is induced on the surface of carbon material near the joining interface, and it decreases with increasing nickel thickness. The maximum residual tensile thermal stress in practical joints is less than the maximum tensile thermal stress calculated by finite element method because the thermal stress is released. [doi:10.2320/matertrans.H-MRA2008819]

A Study on High Temperature Oxidation of Titanium Alloys in Solid State Bonding Process

The surface oxidation behavior was investigated over a range of solid state bonding condition of the Ti-6Al-4V ELI alloy. Since the oxides at the bonding interface may prevent the materials from complete bonding, it is important to understand the oxidation behavior at solid state bonding condition. The activation energy of oxidation of Ti-6Al-4V ELI is estimated to be 318 KJ/mol in an environment of solid state bonding process. For Ti-6Al-4V ELI alloy, strucutral integrity of bonding interface without oxides have been obtained at 850°C applying pressure of 3MPa for 1 hour. Solid state diffusion bonding of Ti-15V-3Cr-3Sn-3Al alloy was also obtained under a pressure of 6MPa for 3 hours at 925°C.

Micro Flash Welding of Super Duplex Stainless Steels

Super duplex stainless steels were welded using new flash butt welding technology of temperature controlling system. The super duplex stainless steel (329J4L) and conventional duplex stainless steel (329J3L) were used. The samples were mounted in the dies using a Gleeble thermal simulator and flash but welding was made. The specimens were heated up to 1373K for 10sec, 20sec and 30sec. Flash butt welding has consisting of a two stage processes of a flash action and a contact resistance. First stage was a flash welding process and second stage was a solid state bonding process. The cross sectional microstructure of the weld bond region showed two types of a deposited fine particles region and a solid state bonding region. The grain growth was hardly observed in the weld region and the heat-affected zone. For further increasing joining efficiency of solid state bonding at the second stage, the welding time at 1373K was increased from 5 sec to 180sec. The bonding area increased with increasing welding time at 1373K and successfully welded for conventional duplex stainless steel.

The Influence of the Solid-State Bonding Process on the Mechanical Integrity of Longitudinal Weld Seams

For production of complex hollow 6xxx series aluminium extrusions, porthole dies are the predominant tooling set up. In porthole dies, the billet is divided into multiple metal streams, which are rejoined in the weld chamber to form ‘longitudinal weld seams’. Fundamental understanding of the solid state bonding process, as well as the ability to detect a well bonded (or a defective) weld seam are important for the production of high quality structural hollow extrusions. A study is being conducted to investigate the solid state bonding and weld seam formation processes during extrusion. The method chosen was to use a thermo-mechanical simulator (Gleeble 3500), thereby having the ability to vary process parameters such as strain, strain rate and temperature. The alloy investigated was primary and remelt AA6082. It was determined that the key parameter for bonding is surface stretching (creation of new surface at the interface) and bonding time.

Effect of Graphitization on Solid State Bonding of Carbon to Nickel

Five carbons with different graphitization degrees, which were heat-treated at temperatures of 1273 to 3273 K, were prepared. These carbons were bonded to nickel in a vacuum, using an RF-induction furnace, with joining temperatures of 1073 to 1273 K. On the basis of the results of these experiments, the effects of the graphitization degree on the solid-state bonding of carbon to nickel were examined. Carbon heat-treated at 1273 K remains amorphous, whereas most of the carbons heat-treated at 3273 K change into graphite because the graphitization degree increases with increasing heat treatment temperature. Strong bonding of amorphous carbon to nickel is not accomplished. The bending strength or joinability of carbon (with a graphitization degree lower than 0.28)/nickel joints depends on the joining temperature. Good bonding of carbon with a graphitization degree higher than 0.28 to nickel is achieved regardless of the joining temperature. The graphitization degree and thermal stress affect the joinability and bending strength of the joints.

Effects of Au plating on dynamic resistance during small-scale resistance spot welding of thin Ni sheets

The effects of Au plating on dynamic resistance during small-scale resistance spot welding of thin Ni sheets have been investigated. Compared to the small-scale resistance spot welding of bare Ni, the Au-plated material showed much lower initial static resistance, and the contribution of constriction resistance to overall dynamic resistance reduced to a negligible value very early in the welding sequence because of the low softening temperature and its lack of surface oxide film. For the same reason, the asperity heating and surface breakdown stages during resistance spot welding of bare Ni were not observed during resistance spot welding of Au-plated Ni. Furthermore, the partial surface melting stage was replaced by the solid-state bonding and brazing stages. Step increases in the sheet-to-sheet dynamic resistance curves of Au-plated Ni were shown to be due to the peripheral unzipping of a prior solid-state bond caused by uneven local thermal expansion. The electrode-to-electrode dynamic resistance curve when welding Au-plated material is not useful for monitoring the state of nugget formation.

308 超塑性二相ステンレス鋼と炭素鋼の固相接合について(機械材料・材料加工II)

308 超塑性二相ステンレス鋼と炭素鋼の固相接合について(機械材料・材料加工II)

AWB-06: The Influence of the Solid-State Bonding Process on the Mechanical Integrity of Longitudinal Weld Seams(AWB-I: ADVANCED WELDING AND BONDING, NDE)

AWB-06: The Influence of the Solid-State Bonding Process on the Mechanical Integrity of Longitudinal Weld Seams(AWB-I: ADVANCED WELDING AND BONDING, NDE)

Microstructure Evolution Mechanism in Iron Aluminides/CrMo Steel Composite Prepared by Solid State Bonding

This work addresses a mechanism of columnar microstructure evolution during diffusion bonding in a composite of iron aluminide and CrMo steel focusing on the role of alloying on microstructure. Columnar microstructure develops in the steel side of diffusion couples of iron aluminide and Fe-X (X=Cr, Mo) steel, when the steel composition is in the gamma phase at the bonding temperature. This is consistent with the proposed model for columnar microstructure evolution, which contributes to bonding strength between iron aluminide and steel. Interdiffusion coefficient at the Matano interface decreases with increasing the concentration of alloying elements in steel, and its decrease rate is higher for Mo than for Cr. The columnar grains in the steel side of the couple are longer than expected by chemical composition analysis, and their lengths increase with the interdiffusion coefficient. Microstructure evolution mechanism is discussed in terms of the kinetics of nucleation and subsequent grain growth during diffusion bonding.

Effects of Carbon Fiber Orientation and Graphitization on Solid State Bonding of C/C Composite to Nickel

C/C composites were bonded to nickel in a vacuum, using an RF-induction furnace, with joining temperature, keeping time and joining compressive stress as variables. C/C composites with different carbon fiber orientations and heat treatment temperatures were used. The bending strength of the C/C composite/nickel joints was investigated. The fracture surface of the joints was observed using a scanning electron microscope. X-ray diffraction was performed on the joining surface of C/C composites. Changes in the microstructure and hardness of nickel near the joining interface were investigated. On the basis of the results of these experiments, the influences of carbon fiber orientation and graphitization on the solid-state bonding of C/C composite to nickel were examined. A large difference in thermal expansion coefficients between the longitudinal section of carbon fiber and nickel results in delamination at the interface. In the bending test, when the longitudinal section of carbon fiber is parallel to the joining surface, slip due to crystallographic anisotropy occurs. Therefore, good bonding between the longitudinal section of the carbon fiber and nickel is not achieved. On the other hand, good bonding to nickel along the cross section perpendicular to the carbon fiber axis becomes feasible. Therefore, in plain woven carbon fiber-reinforced carbon composite/nickel joints, the bending strength is low, while in unidirectional carbon fiber-reinforced carbon composite/nickel joints, the bending strength is equivalent to that of C/C composite. The degree of graphitization affects joinability. Strong bonding of C/C composite to nickel is accomplished with the progress of graphitization. The bending strength of the joint is equivalent to that of C/C composite. The bending strength of C/C composite/nickel joints is affected by the joining temperature, keeping time and joining compressive stress, because these factors are related to full contact of joining surfaces and diffusion of carbon atoms from C/C composite into nickel.

球状黒鉛鋳鉄の固相接合 ９ Ｎｉ系ろう材を用いた球状黒鉛鋳鉄接合材の衝撃特性

球状黒鉛鋳鉄の固相接合 ９ Ｎｉ系ろう材を用いた球状黒鉛鋳鉄接合材の衝撃特性

119 超塑性二相ステンレス鋼と炭素鋼の固相接合材の疲労強度

119 超塑性二相ステンレス鋼と炭素鋼の固相接合材の疲労強度

Solid State Bonding of Graphite to Inconel 718

Graphite was bonded to Inconel 718 in a vacuum using an RF-induction furnace. The influence of joining conditions on the bending strength of the graphite/Inconel 718 joint, and changes in the microstructure and hardness of Inconel 718 near the joining interface, were investigated. Thermal stress induced in the joint was estimated using the finite element method. Good-solid-state bonding becomes feasible with annealing at temperatures higher than 1173 K under compressive stress of 35 MPa. The adequate joining temperature and joining compressive stress in graphite/Inconel 718 bonding are higher than those in graphite/nickel bonding. This is because fracture of passive-oxide film on the surface due to plastic deformation of Inconel 718 and the resulting direct contact of graphite with matrix of Inconel 718 are required on solid-state bonding. The bending strength of the joints is nearly equal to or greater than that of graphite. This is because the compressive stress induced on the surface of graphite by the plastic deformation of Inconel 718 after bonding and the resulting elastic deformation of graphite in the radial direction relaxes the tensile thermal stress induced on the surface of graphite during cooling or the compressive stress remains. Heat treatment is required to recover the strength of Inconel 718 since intermetallic compounds precipitated in Inconel 718 dissolve in the matrix during annealing and age hardening disappears.

Effect of Joining Compressive Stress on Solid State Bonding of Graphite to Nickel

Graphite was bonded to nickel in a vacuum using an RF-induction furnace with temperature, keeping time and joining compressive stress as variables. The bending strength of graphite/nickel joints, the changes of microstructure and hardness of nickel near the interface were investigated. Thermal stress induced in the joints was estimated by means of finite element analysis. On the basis of these results, the influences of joining compressive stress on bonding were examined. Joining compressive stress and joining temperature are important factors for close contact and strong bonding between the joining surfaces of graphite and nickel. At a high joining temperature, nickel is plastically deformed even under low joining compressive stress so that full contact and strong bonding are accomplished. At a low joining temperature, strong bonding was not achieved when joining compressive stress is low, because plastic deformation of nickel is restrained. The plastic deformation of nickel plays an important role in enabling good contact and strong bonding. The strength of the joints increased with joining compressive stress. The plastic deformation of nickel near the joining interface increases with the joining compressive stress so that graphite is elastically deformed during annealing. Therefore, compressive stress is retained on the graphite surface near the joining interface. Thermal tensile stress induced on the graphite surface after cooling is relaxed by this compressive stress.

Solid State Bonding of Graphite to Nickel

Graphite was bonded to nickel under joining compressive stress of 3 to 33 MPa in a vacuum at temperatures within the range of 973 to 1273 K using an RF-induction furnace. The influence of joining conditions on the bending strength of the graphite/nickel joint, and changes in the microstructure and hardness of nickel near the joining interface, were investigated. Thermal stress induced in the joint was estimated using the finite element method. On the basis of these results, the influence of thermal stress on the bending strength of the joint was examined Completion of the graphite/nickel joint depends on both joining compressive stress and joining temperature. At high joining temperature, good solid-state bonding under relatively low joining compressive stress becomes feasible. Axisymmetric thermoelastic finite element analysis suggests that the maximum tensile thermal stress is induced at a distance of 0.64 mm from the joining interface on the surface of graphite anal is increased with increasing joining temperature. The position of fracture in a bending test corresponds approximately to that of the maximum tensile thermal stress. Part of the thermal stress in practical joints is relaxed and less than that calculated using the finite element method. The bending strength of the joint increases with decreasing residual tensile stress on the surface of graphite. Relaxation of the maximum tensile thermal stress depends on the amount of carbon which diffuse into nickel. This may be related to changes in plasticity of both nickel and graphite, that is, changes in the amount of carbon that dissolves in nickel to supersaturation and the point defects introduced in graphite.

Investigation of Superplastic Behaviour and Solid State Bonding of Zircaloy-4

Superplastic behaviour and isostatic diffusion bonding (DB) have been investigated for as-received annealed Zircaloy-4 sheet of relatively large grain size. The material was superplastic at strain rates up to 5.0 x 10 -4 s -1 at temperatures in the lower part of the α+β phase field for β-phase volumes of 10-20%. At higher strain rates and lower temperatures the material deformed by power law creep. The DB studies showed that for intermediate and higher temperatures in the α+β phase field, sound bonds could be obtained at relatively low pressures and short times. Bonding in the α-phase field required much higher pressures. Modifications to an earlier model of the DB process involved constraint of collapse by creep of inter-void ligaments at the bond interface. This lead to a dominance of stress directed boundary diffusion and gave improved agreement between prediction and observation for DB of the α- phase.

Solid State Bonding of Graphite to SUS304 Steel

Graphite was bonded to SUS304 steel under a compressive stress of 25 MPa in a vacuum over a temperature range from 873 to 1023 K using a RF-induction furnace. The bending strength of the graphite/SUS304 steel joint, and changes of microstructure and hardness near the joining interface of SUS304 steel, were investigated. Thermal stress induced in the joint was estimated with a finite element method. On the basis of these results the influence of thermal stress on the bending strength of the joint was examined. Good solid state bonding becomes feasible when the joining temperature exceeds 923 K. Axisymmetric thermoelastic finite element analysis suggests that maximum tensile thermal stress is induced at a distance of 0.64 mm from the joining interface on the surface of the graphite and is increased with increasing joining temperature. The position of fracture in a bending test specimen corresponds approximately to that of the maximum tensile thermal stress. A part of the thermal stress is released with the deformation of SUS304 steel and graphite. The bending strength of the joint increases with decreasing residual tensile stress on the surface of graphite. Relaxation of thermal stress depends on the amount of carbon atoms which diffuse into SUS304 steel. This may be related to the changes in plasticity of SUS304 steel and graphite, that is, the changes in the amounts of Cr 23 C 6 precipitated in SUS304 steel and point defect introduced in graphite.

接合複合化に関する最近の話題 １ 超塑性セラミックスを中間材に用いるセラミックスの固相接合

接合複合化に関する最近の話題 １ 超塑性セラミックスを中間材に用いるセラミックスの固相接合

Solid-state bonding of iron-based alloys, steel–brass, and aluminum alloys

Many genuine solid-state-bonding experiments have been performed using a wide range of metals; the latter includes superplastic ultra-high-carbon steel, Fe–Ni–Si alloy, manganese steel, brass, stainless steel, iron-silicon alloy as well as superplastic aluminum alloys 5083 and 7475. The roll-bonding process was employed to study the ability to mechanically bond (one kind of solid-state bond) iron-based alloys at intermediate temperatures. Press bonding was meant to determine the effect of three interconnecting factors—temperature, time, and deformation—on the strength of the diffusion bond. The results and analysis conclude that diffusion bonding is difficult to achieve without successful mechanical bonding preceding it.