Al_2O_3 and 3% (mole fraction) yttrium tetragonal zirconia was joined together by a process of directly joining their green body in plastic state and following co-sintering. Joining strength, joint microstructure, str...Al_2O_3 and 3% (mole fraction) yttrium tetragonal zirconia was joined together by a process of directly joining their green body in plastic state and following co-sintering. Joining strength, joint microstructure, stress state of joining interface, and diffusion between joined compositions were studied. Experimental results show that a transition interlayer containing both joined particles is formed in the joint which is dense and pore free, fracture taken place at Al_2O_3 matrix near the joining interface but the joining strength is lower than normal Al_2O_3 matrix because of the complex stress state near the interface. Apart from the effect of plasticity of green bulk on joining before sintering, it is postulated from the HRTEM/EDS studied results that the diffusion of Al 3+ to the ZrO_2 grain during the sintering process contributed to the interface bonding which led a success joining of Al_2O_3 and ZrO_2 composites.展开更多
The C_(f)/Al composites were joined to the TC4 alloy via the laser-induced combustion joining method.The exothermic reaction of the interlayer provided the required energy for the joining process.By combining the theo...The C_(f)/Al composites were joined to the TC4 alloy via the laser-induced combustion joining method.The exothermic reaction of the interlayer provided the required energy for the joining process.By combining the theoretical calculation and experiment,the chemical composition of the Ni−Al−Zr interlayer was designed.The microstructure and mechanical properties of the joint were investigated.The results show that the addition of Zr slightly weakened the combustion reaction of exothermic interlayer but played a key role in the successful joining.Ni−Al−Zr interlayer reacted with substrates,forming a TiAl_(3)layer adjacent to TC4 alloy and NiAl_(3),Ni_(2)Al_(3)layers adjacent to the C_(f)/Al composites.Zr content dominated the microstructure and shear strength of the joint.When the Zr content was 5 wt.%under the joining pressure of 2 MPa,the joint had a maximum shear strength of 19.8 MPa.展开更多
In order to study the characteristics of deformation joining of aluminum-stainless steel composite sheet, an applied example of this composite sheet was given. The conditions of the composite sheet were discussed, the...In order to study the characteristics of deformation joining of aluminum-stainless steel composite sheet, an applied example of this composite sheet was given. The conditions of the composite sheet were discussed, the optical micrographs and scanning electron micrographs were examined by contrast ways of deformation joining and braze joining. Simultaneously the analysis of energy spectrum was also conducted. The results indicate that the deformation joining composite sheet possesses high bonding strength, good corrosion resistance, less inclusions and less microcracks.展开更多
Clinching can be used for effective joining of different metallic materials, e.g., different grades of carbon and alloy steels, aluminum and its alloys and others. This is an alternative joining method to traditional ...Clinching can be used for effective joining of different metallic materials, e.g., different grades of carbon and alloy steels, aluminum and its alloys and others. This is an alternative joining method to traditional methods involving screws, rivets or welding. Clinching is applied in many fields of manufacturing industry. Future applications of clinch joining require advances in quality and among others things, combination with other processes, e.g., hybrid joining by clinching and adhesive bonding. Although the static strength of clinched joints is lower than that of the others joints （e.g., pressure welded joints）, the fatigue strength is comparable. But there is a lack of information about fatigue strength of clinched joints. The static and low cyclic fatigue strengths of mechanically clinched joints were determined experimentally. The load-displacement curves of static strength were compared with low cyclic fatigue strength curves. It was observed the effect of strain hardening for clinched joint of low carbon steels （DC4） under cyclic loading.展开更多
A kind of self-made AgCuTiSn braze alloy powder was used to join graphite and copper. The whole brazing process was performed under vacuum circumstances at different temperatures （ 1 033 - 1 193 K） for several holdi...A kind of self-made AgCuTiSn braze alloy powder was used to join graphite and copper. The whole brazing process was performed under vacuum circumstances at different temperatures （ 1 033 - 1 193 K） for several holding time （300 - 1 800 s ）. According to scanning electron microscope （SEM）, energy dispersive spectrometer （EDS） and electron probe X-ray microanalysis （ EPMA ） results, the reaction products of the interface are TiC, Ti3Sn, Cu（s. s）, Ag（s. s） and Cu-Sn compound. As the brazing parameters increase, the quantity of Ag（ s. s） in the braze alloy and C fibers on graphite/AgCuTiSn interface reduce, while that of Cu （ s. s） in the braze alloy improves. When the brazing temperature /s 1 093 K and holding time is 900 s, the joint can obtain the maximum room temperature shear strength 24 MPa.展开更多
A new testing methodology was developed to quantitively study galvanic corrosion of AZ31B and thermoset carbon-fiber–reinforced polymer spot-joined by a friction self-piercing riveting process.Pre-defined areas of AZ...A new testing methodology was developed to quantitively study galvanic corrosion of AZ31B and thermoset carbon-fiber–reinforced polymer spot-joined by a friction self-piercing riveting process.Pre-defined areas of AZ31B in the joint were exposed in 0.1 M NaCl solution over time.Massive galvanic corrosion of AZ31B was observed as exposure time increased.The measured volume loss was converted into corrosion current that was at least 48 times greater than the corrosion current of AZ31B without galvanic coupling.Ninety percent of the mechanical joint integrity was retained for corroded F-SPR joints to 200 h and then decreased because of the massive volume loss of AZ31B。展开更多
Silicon nitride composite is joined to itself by heating interlayer of Y2 O3 -AL2O3 -SiO2 mixtures above their liquidus temperatures in flowing nitrogen. The joined specimens are tested in four point flexure from room...Silicon nitride composite is joined to itself by heating interlayer of Y2 O3 -AL2O3 -SiO2 mixtures above their liquidus temperatures in flowing nitrogen. The joined specimens are tested in four point flexure from room temperature to 1373 K. The interface microstruclure and fractured surfaces after testing are observed and analyzed by SEM, EPMA and XRD respectively. The results show that F2 O3 -A12 O3 -SiO2 glass reacts with Si3 N4 at interface, forming the Si3 N4/Si2 N2 O( Y-AlrSi-O-N glass/ Y-Al- Si-O glass gradient interface. With the increase of bonding temperature and holding time, the joint strength first increases, reaching a peak, and then decreases . According to interfacial analyses , the bonding strength depends on joint thickness .展开更多
Silicon carbide(SiC) has been widely concerned for its excellent overall mechanical and physical properties, such as low density, good thermal-shock behavior, high temperature oxidation resistance, and radiation resis...Silicon carbide(SiC) has been widely concerned for its excellent overall mechanical and physical properties, such as low density, good thermal-shock behavior, high temperature oxidation resistance, and radiation resistance; as a result, the SiC-based materials have been or are being widely used in most advanced fields involving aerospace, aviation, military, and nuclear power. Joining of SiC-based materials(monolithic SiC and SiCf/SiC composites) can resolve the problems on poor processing performance and difficulty of fabrication of large-sized and complex-shaped components to a certain extent, which are originated from their high inherent brittleness and low impact toughness.Starting from the introduction to SiC-based materials, joining of ceramics, and joint strength characterization, the joining of SiC-based materials is reviewed by classifying the as-received interlayer materials, involving no interlayer, metallic, glass-ceramic, and organic interlayers. In particular, joining processes(involving joining techniques and parameter conditions), joint strength,interfacial microstructures, and/or reaction products are highlighted for understanding interfacial behavior and for supporting development of application-oriented joining techniques.展开更多
The SiC/SiC joints were vacuum brazed at 700℃,740℃,780℃and 800℃for 10 min respectively,using Ag-Cu-In-Ti active filler alloy.The microstructure and joining strength of the joints were characterized by electron pro...The SiC/SiC joints were vacuum brazed at 700℃,740℃,780℃and 800℃for 10 min respectively,using Ag-Cu-In-Ti active filler alloy.The microstructure and joining strength of the joints were characterized by electron probe X-ray microanalyser(EPMA),energy dispersive spectroscopy(EDS),transmission electron microscopy(TEM)and four-point bending strength test.The interface of the joints was composed of three parts:SiC substrate,reaction layer and filler alloy.A representative microstructure of the reaction layer:In-containing layer/TiC layer/Ti5Si3 layer was found from the TEM image.The forming of the In-containing layer could be attributed to the crack or delamination of SiC/TiC interface.The In-containing layer intensified the coefficient of thermal expansion(CTE)mismatch of SiC and the reaction layer,and affected the joining strength.With the increase of the reaction layer’s thickness,the joining strength firstly increased,then declined,and the maximum four-point bending strength reached 234 MPa.展开更多
文摘Al_2O_3 and 3% (mole fraction) yttrium tetragonal zirconia was joined together by a process of directly joining their green body in plastic state and following co-sintering. Joining strength, joint microstructure, stress state of joining interface, and diffusion between joined compositions were studied. Experimental results show that a transition interlayer containing both joined particles is formed in the joint which is dense and pore free, fracture taken place at Al_2O_3 matrix near the joining interface but the joining strength is lower than normal Al_2O_3 matrix because of the complex stress state near the interface. Apart from the effect of plasticity of green bulk on joining before sintering, it is postulated from the HRTEM/EDS studied results that the diffusion of Al 3+ to the ZrO_2 grain during the sintering process contributed to the interface bonding which led a success joining of Al_2O_3 and ZrO_2 composites.
基金the financial supports from the National Natural Science Foundation of China(Nos.51975149,51905055)the Natural Science Foundation of Chongqing,China(No.cstc2020jcyj-msxmX0115)the Fundamental Research Funds for the Central Universities Project,China(No.2020CDJ-LHZZ 086).
文摘The C_(f)/Al composites were joined to the TC4 alloy via the laser-induced combustion joining method.The exothermic reaction of the interlayer provided the required energy for the joining process.By combining the theoretical calculation and experiment,the chemical composition of the Ni−Al−Zr interlayer was designed.The microstructure and mechanical properties of the joint were investigated.The results show that the addition of Zr slightly weakened the combustion reaction of exothermic interlayer but played a key role in the successful joining.Ni−Al−Zr interlayer reacted with substrates,forming a TiAl_(3)layer adjacent to TC4 alloy and NiAl_(3),Ni_(2)Al_(3)layers adjacent to the C_(f)/Al composites.Zr content dominated the microstructure and shear strength of the joint.When the Zr content was 5 wt.%under the joining pressure of 2 MPa,the joint had a maximum shear strength of 19.8 MPa.
文摘In order to study the characteristics of deformation joining of aluminum-stainless steel composite sheet, an applied example of this composite sheet was given. The conditions of the composite sheet were discussed, the optical micrographs and scanning electron micrographs were examined by contrast ways of deformation joining and braze joining. Simultaneously the analysis of energy spectrum was also conducted. The results indicate that the deformation joining composite sheet possesses high bonding strength, good corrosion resistance, less inclusions and less microcracks.
文摘Clinching can be used for effective joining of different metallic materials, e.g., different grades of carbon and alloy steels, aluminum and its alloys and others. This is an alternative joining method to traditional methods involving screws, rivets or welding. Clinching is applied in many fields of manufacturing industry. Future applications of clinch joining require advances in quality and among others things, combination with other processes, e.g., hybrid joining by clinching and adhesive bonding. Although the static strength of clinched joints is lower than that of the others joints （e.g., pressure welded joints）, the fatigue strength is comparable. But there is a lack of information about fatigue strength of clinched joints. The static and low cyclic fatigue strengths of mechanically clinched joints were determined experimentally. The load-displacement curves of static strength were compared with low cyclic fatigue strength curves. It was observed the effect of strain hardening for clinched joint of low carbon steels （DC4） under cyclic loading.
基金This work was supported by the National Natural Science Foundation of China （No. 50705022）.
文摘A kind of self-made AgCuTiSn braze alloy powder was used to join graphite and copper. The whole brazing process was performed under vacuum circumstances at different temperatures （ 1 033 - 1 193 K） for several holding time （300 - 1 800 s ）. According to scanning electron microscope （SEM）, energy dispersive spectrometer （EDS） and electron probe X-ray microanalysis （ EPMA ） results, the reaction products of the interface are TiC, Ti3Sn, Cu（s. s）, Ag（s. s） and Cu-Sn compound. As the brazing parameters increase, the quantity of Ag（ s. s） in the braze alloy and C fibers on graphite/AgCuTiSn interface reduce, while that of Cu （ s. s） in the braze alloy improves. When the brazing temperature /s 1 093 K and holding time is 900 s, the joint can obtain the maximum room temperature shear strength 24 MPa.
基金financially sponsored by the US Department Energy Vehicle Technologies Office, as part of the Joining Core Programmanaged by UT-Battelle LLC for the US Department of Energy under Contract DE-AC05-00OR22725。
文摘A new testing methodology was developed to quantitively study galvanic corrosion of AZ31B and thermoset carbon-fiber–reinforced polymer spot-joined by a friction self-piercing riveting process.Pre-defined areas of AZ31B in the joint were exposed in 0.1 M NaCl solution over time.Massive galvanic corrosion of AZ31B was observed as exposure time increased.The measured volume loss was converted into corrosion current that was at least 48 times greater than the corrosion current of AZ31B without galvanic coupling.Ninety percent of the mechanical joint integrity was retained for corroded F-SPR joints to 200 h and then decreased because of the massive volume loss of AZ31B。
文摘Silicon nitride composite is joined to itself by heating interlayer of Y2 O3 -AL2O3 -SiO2 mixtures above their liquidus temperatures in flowing nitrogen. The joined specimens are tested in four point flexure from room temperature to 1373 K. The interface microstruclure and fractured surfaces after testing are observed and analyzed by SEM, EPMA and XRD respectively. The results show that F2 O3 -A12 O3 -SiO2 glass reacts with Si3 N4 at interface, forming the Si3 N4/Si2 N2 O( Y-AlrSi-O-N glass/ Y-Al- Si-O glass gradient interface. With the increase of bonding temperature and holding time, the joint strength first increases, reaching a peak, and then decreases . According to interfacial analyses , the bonding strength depends on joint thickness .
基金supported by the National Natural Science Foundation of China (No. 51572112)the National Key R&D Program of China (No. 2017YFB0310400)+3 种基金the 333 Talents Project (No. BRA2017387)Six Talent Peaks Project (No. TD-XCL-004)Innovation/Entrepreneurship Program ([2015]26)Qing Lan Project ([2016]15) of Jiangsu Province
文摘Silicon carbide(SiC) has been widely concerned for its excellent overall mechanical and physical properties, such as low density, good thermal-shock behavior, high temperature oxidation resistance, and radiation resistance; as a result, the SiC-based materials have been or are being widely used in most advanced fields involving aerospace, aviation, military, and nuclear power. Joining of SiC-based materials(monolithic SiC and SiCf/SiC composites) can resolve the problems on poor processing performance and difficulty of fabrication of large-sized and complex-shaped components to a certain extent, which are originated from their high inherent brittleness and low impact toughness.Starting from the introduction to SiC-based materials, joining of ceramics, and joint strength characterization, the joining of SiC-based materials is reviewed by classifying the as-received interlayer materials, involving no interlayer, metallic, glass-ceramic, and organic interlayers. In particular, joining processes(involving joining techniques and parameter conditions), joint strength,interfacial microstructures, and/or reaction products are highlighted for understanding interfacial behavior and for supporting development of application-oriented joining techniques.
文摘The SiC/SiC joints were vacuum brazed at 700℃,740℃,780℃and 800℃for 10 min respectively,using Ag-Cu-In-Ti active filler alloy.The microstructure and joining strength of the joints were characterized by electron probe X-ray microanalyser(EPMA),energy dispersive spectroscopy(EDS),transmission electron microscopy(TEM)and four-point bending strength test.The interface of the joints was composed of three parts:SiC substrate,reaction layer and filler alloy.A representative microstructure of the reaction layer:In-containing layer/TiC layer/Ti5Si3 layer was found from the TEM image.The forming of the In-containing layer could be attributed to the crack or delamination of SiC/TiC interface.The In-containing layer intensified the coefficient of thermal expansion(CTE)mismatch of SiC and the reaction layer,and affected the joining strength.With the increase of the reaction layer’s thickness,the joining strength firstly increased,then declined,and the maximum four-point bending strength reached 234 MPa.
