共查询到20条相似文献,搜索用时 15 毫秒
1.
《Journal of the European Ceramic Society》2020,40(4):1496-1504
In this study, Al2O3 workpieces were vacuum brazed by using Ni-45Ti binary alloy. The interfacial microstructure evolution of the joints obtained at different brazing temperatures was investigated using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The bonding strength of the joints was measured by shear testing. The results indicated that Ni2Ti4O and AlNi2Ti were the main reaction products in the joint areas. Moreover, the Ti2Ni intermetallic compound formed in the brazing seam. The typical layer structure of the brazed joints was Al2O3/AlNi2Ti/Ni2Ti4O/Ti2Ni + NiTi/Ni2Ti4O/AlNi2Ti/Al2O3. With the brazing temperature increasing, the thickness of the Ni2Ti4O reaction layer adjacent to the Al2O3 substrate increased significantly, while the AlNi2Ti phase had a tendency to dissolve with the brazing temperature increasing. The mechanism for the microstructure evolution was also discussed. The maximum shear strength of 125.63±4.87 MPa of the joints was obtained when brazed at 1350 °C for 30min. The fracture occurred hardly in the interface between Al2O3 and Ni-45Ti filler alloy. 相似文献
2.
《Ceramics International》2022,48(17):24319-24325
Joining is an indispensable process for expanding the application of ceramics and composites. Recently, glasses have been extensively explored for ceramic/composite joining owing to their unique functional needs. However, the difficulty in detecting amorphous materials and lack of enthalpy data make the interfacial reaction mechanism challenging to investigate. In this study, the interfacial reaction mechanism of joints of SiO2f/SiO2 composite-brazed bismuth glass was thoroughly explored. SiO2 was dissolved from the matrix and used throughout the brazing process. In the initial stage, silica reacts with the brazing glass to form Bi4(SiO4)3. Then, owing to the decomposition of Bi4(SiO4)3, the silicate glass replaced the bismuth glass. Finally, some precipitation of SiO2 occurred at the brazing seam owing to an entropy–enthalpy dominating mode. This study may instigate the design of brazing glasses for joining SiO2f/SiO2 composites. 相似文献
3.
Kaihong Zheng Qi Zhang Juan Wang Yao Lu 《Journal of the European Ceramic Society》2021,41(3):2076-2084
The reliable brazing of the ZTA ceramic joints was successfully obtained using Ni-Ti filler metal. The microstructure and mechanical properties of the joints brazed at different temperatures were investigated. During the process of brazing, both Al2O3 and ZrO2 in the ZTA reacted with the Ni-Ti filler, resulting in the formation of the AlNi2Ti + Ni2Ti4O reaction layer adjacent to the ZTA substrate when brazed at 1350 °C for 30 min. NiTi and Ni3Ti compounds precipitated at the center of brazing seam. When the brazing temperature increased from 1320 °C to 1380 °C, the thickness of AlNi2Ti + Ni2Ti4O layer increased gradually. As the brazing temperature varied from 1400 °C to 1450 °C, TiO was formed adjacent to the ZTA substrate, along with the reduction of Ni2Ti4O. AlNi2Ti distributed at the interface and center of brazing seam. The maximum shear strength of 152 MPa was obtained when brazed at 1420 °C for 30 min. 相似文献
4.
Ying Wang Chenkai Jin Zhenwen Yang Dongpo Wang 《International Journal of Applied Ceramic Technology》2019,16(3):896-906
Al2O3 ceramic and Kovar alloy brazed joints were achieved using three types of Ag-based interlayers: a AgCuTi foil, a AgCuTi/Cu foil/AgCuTi multi-interlayer and a AgCuTi/Cu foam/AgCuTi multi-interlayer. The effects of the addition of Cu interlayers on the interfacial microstructure and mechanical properties of Al2O3/AgCuTi/Kovar brazed joints were investigated. When Kovar alloy and Al2O3 ceramic were brazed with 50 μm Cu foil at 900°C for 10 minutes, the Cu foil was completely dissolved in the liquid filler. A nearly continuous Cu layer remained in the joint when the thickness of the Cu foil reached 100 μm under the same brazing conditions. With the increase in Cu foil thickness, the thickness of Ti–O compounds + Ti3Cu3O reaction layer formed nearby the Al2O3 ceramic first increased and then remained the same. The Al2O3/Kovar joints brazed with 100 μm Cu foil at 900°C for 10 minutes showed a maximum shear strength of 138 MPa. A low brazing temperature was beneficial to maintain the original structure of the Cu foam. Furthermore, when the joints were brazed at 880°C for 10 minutes, the average shear strength of the Al2O3/AgCuTi/Cu foam/AgCuTi/Kovar joints was 140 MPa, which was 30 MPa higher than that of a single AgCuTi interlayer. 相似文献
5.
In order to refine the grain size of TiSi2 silicide and reduce the formation of micro-defects in the joint, and thereby increasing the joint strength of SiC ceramic brazed with Si-24Ti (wt.%), a small amount of SiC particulates were added in the brazing alloy. The microstructure and mechanical strength of SiC joints was investigated by using field emission scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction spectrometer, and shear strength test. The results indicated that SiC particulates enhanced the nucleation and grain refinement of the TiSi2 and Si phase. The adding of appropriate content of SiC (<1 wt.%) could effectively refine the size of TiSi2 phase and increase the fraction of Si-TiSi2 eutectic zone. However, excess addition of 1.5 wt.% SiC caused the coarsening of TiSi2 phase due to the clustering of added fine SiC particulates. With the increasing of SiC particulate content, the shear strength of the joints increased at first and then decreased. The maximum shear strength of 106.3 MPa of SiC joint was obtained for the joint brazed with 1 wt.% SiC addition, which was ~19% higher than that of the joint brazed without SiC particulates. 相似文献
6.
Hailong Wang Jianyong Chen Pengfei Yu Shengping Shen 《Journal of the European Ceramic Society》2018,38(4):1112-1117
Using the stress distribution of the body containing a spherical inclusion, the stress intensity factor at the tip of the annular flaw emanating from the inclusion is formulized. Since the thermal expansion coefficient of matrix and inclusion is not matched, the residual stress is also taken into account. Introducing into the proposed temperature-dependent fracture surface energy or fracture toughness, the temperature-dependent fracture strength for ZrB2-SiC is obtained. The influence of oxidation on the fracture strength is also discussed and the analysis reveals that the oxidation has significant effect on the fracture strength under some circumstances. The calculated results are compared with the experimental data and they have very good consistency. 相似文献
7.
Weibing Guo Zhanlong Yu Zhijie Ding Wenshan Bian Haitao Xue Anhang Li Yiren Hu Chong Fan 《International Journal of Applied Ceramic Technology》2023,20(4):2610-2619
Aluminum nitride (AlN) ceramics and oxygen-free Cu were brazed with multilayer filler consisted of Ag-Cu-Ti +Ni foam. The microstructure and forming principle of AlN/Cu joints were studied and the influence of Ni foam on the joints was focused. The result shows that the composition of AlN/Cu joint was AlN/TiN/Ni3Ti+Cu(s,s)+CuTi+Ni foam+Ag(s,s)/Cu. The joint strength was only 66.7 ± 3.7MPa with pure Ag-Cu-Ti solder and the fracture occurred inside AlN ceramics due to the residual stress. The foam nickel reacted with Ag-Cu-Ti filler metal to form Ni3Ti during brazing process. Ni foam still retained the basic skeleton structure during brazing, and the mechanical capacity of AlN/Cu joint was enhanced significantly. The maximum shear strength of the brazed joint can reach 89.6 ± 4.5 MPa with .1 mm Ni foam, and the fracture position changed to the brazing filler. The result shows that nickel foam can reduce the residual thermal stress, and the mechanical properties of AlN/Cu joints were improved. 相似文献
8.
《Journal of the European Ceramic Society》2017,37(3):931-937
Reliable brazing of carbon fiber reinforced SiC (Cf/SiC) composite to Nb-1Zr alloy was achieved by adopting a novel Ti45Co45Nb10 (at.%) filler alloy. The effects of brazing temperature (1270–1320 °C) and holding time (5–30 min) on the microstructure and mechanical properties of the joints were investigated. The results show that a continuous reaction layer (Ti,Nb)C was formed at the Cf/SiC/braze interface. A TiCo and Nb(s,s) eutectic structure was observed in the brazing seam, in which some CoNb4Si phases were distributed. By increasing the brazing temperature or extending the holding time, the reaction layer became thicker and the amount of the CoNb4Si increased. The optimized average shear strength of 242 MPa was obtained when the joints were brazed at 1280 °C for 10 min. The high temperature shear strength of the joints reached 202 MPa and 135 MPa at 800 °C and 1000 °C, respectively. 相似文献
9.
《Journal of the European Ceramic Society》2014,34(14):3291-3299
Si3N4 based composites with 7 wt.% of graphene nanoplatelets (GNPs) were prepared using different homogenization methods. Si3N4/GNPs powder mixtures were dispersed in isopropanol and homogenized by attritor milling, ball milling or planetary ball milling. The ball milling technique was also used for the homogenization of Si3N4/GNPs mixture in dry state. Fractography analysis was carried out in order to assess the individual homogenization treatment. Depending on the homogenization methods, the size of the processing flaws varied from 20 μm up to 400 μm. The agglomeration of the GNPs and the residual porosity were found as the most frequently observed types of the critical flaws. The planetary ball milling with previous ultrasonication of GNPs in isopropanol was found to be the most promising homogenization technique, resulting in the composites with the highest bending strength (average value is 740 MPa) and the lowest average size of the processing flaws (around 20 μm). 相似文献
10.
《Journal of the European Ceramic Society》2020,40(4):1132-1138
The aim of this study was to evaluate the mechanical properties and coloration of silicon nitride ceramics in the presence of RE2O3 (RE = Nd, Eu or Dy). Dense Si3N4 ceramics were prepared by gas pressure sintering at 1800 °C for 2 h. XRD analysis confirmed the complete transformation of α-Si3N4 to β-Si3N4. The fracture toughness and flexure strengths were 11.93 ± 0.56 MPa·m1/2, 667 ± 40.98 MPa with the addition of Eu2O3 (SE). Base on the SEM image, the pull-out, bridging and deflection of large grains were observed and contributed to the increase in mechanical properties. The chromaticity of sintered bodies was measured using a spectrophotometer. The color difference of the ceramics is due to the formation of different color developing compounds according to the EDS. Results showed that high-toughness and colorful Si3N4 ceramics can be prepared using YAG:Ce3+ as sintering additive and RE2O3 as the colorant. 相似文献
11.
A. Akhavan-Safar S. Rastegar L. F. M. da Silva 《Journal of Adhesion Science and Technology》2018,32(18):2019-2040
This paper deals with the application of fracture mechanics approaches for predicting the residual static strength and the crack kinking angle of adhesively bonded joints containing interfacial edge pre-cracks. The interfacial cracks are created due to different factors such as inappropriate surface preparation which cause a significant reduction of the joint strength. To investigate the residual strength of interfacial cracked adhesive joints and predict the crack kinking angle, three different approaches including the maximum tangential stress (MTS), the minimum strain energy density (SED) and the maximum tangential strain energy density (MTSED) were assessed. To this end, single lap joints (SLJs) containing a brittle adhesive material and with different pre-crack sizes and various substrate thicknesses were manufactured and tested. The results were also verified by applying fracture mechanics approaches on previously published experimental data. According to the results, it was concluded that in mode II dominant cases, the predictions of kinking angle using the MTS method was in good agreement with the experimental observations, while in mode I dominant cases the mentioned approach provided poor predictions. It was also found that the SED criterion could be a precise model for predicting the crack extension angle in mode I dominant conditions. The results also showed that the MTS criterion predicts the residual static strength of interfacial cracked adhesive joints very well. 相似文献
12.
《Ceramics International》2016,42(12):13723-13737
Ag-Cu-Ti/TiX (TiX=TiB2, TiN or TiC) composite filler materials, instead of pure Ag-Cu-Ti alloy, were developed to improve the comprehensive mechanical performance of brazed joints of cubic boron nitride (CBN) grains/bonding layer/steel matrix. This article mainly concerns the effects of TiX addition on the joining interface and compressive strength of brazed CBN grains. The results demonstrate that, due to the variation of chemical activity of Ti atoms induced by TiX addition into the brazing system, the brazing reactions, especially chemical resultants produced at the joining interface between CBN grain and Ag-Cu-Ti alloy, are restrained to some extents. In general, the TiN particles show the greatest suppression effect on the brazing resultants, while the TiC particles have the weakest effect, and TiB2 particles have the medium effect. The optimum reinforcement of the composite filler is finally determined as the TiB2 particles with the content of 8 wt%, with which the average compressive strength of brazed CBN grains reaches 15 N, which is nearly the same high as that of original CBN grains. 相似文献
13.
Yunlong Yang Gang Wang Rujie He Da Shu Caiwang Tan Wei Cao 《Journal of the American Ceramic Society》2021,104(7):2992-3003
ZrB2-SiC ceramics and Nb alloy were brazed at 1160°C for 60 min with CoFeNiCrCuTix high-entropy alloy filler. The influence of Ti content on the interface structure and mechanical properties of ZrB2-SiC/Nb joint was systematically studied. It is found that the rich-Ti Laves phase was formed due to the addition of large atomic size Ti fill into the filler alloy or brazing joint, and its content increases with Ti content. The joint brazed by high-entropy alloys filler without Ti can be divided into a tooth-shaped Cr2B reaction layer and a central area composed of a eutectic mixed structure of FCC phase and rich-Nb lamellar Laves phase. Ti and Nb are mutual solid solution elements. The increase of Ti content in the joint makes the FCC phase and the rich-Nb lamellar Laves phase to transform into a big bulk Ti-rich Laves phase and the quadrilateral (Ti, Nb)B phase. The tooth-shaped Cr2B was disappeared. The residual stress generated in the joint during the brazing process tends to cause defects such as holes and microcracks in the bulk Ti-rich brittle Laves phase. Therefore, with the addition of Ti, the normal temperature performance of the joint decreases from 216 MPa to 52 MPa. However, with the increase of Ti, the high-temperature mechanical properties of the joint first decrease, and then increase. It was mainly due to the formation of rich-Ti Laves phase and quadrilateral (Ti, Nb)B with excellent high-temperature mechanical properties. When brazing with CoFeNiCrCuTi1.5 filler, the high-temperature performance of the joint reached 92% of its room temperature performance. 相似文献
14.
Large articles of polymeric materials which can not be molded require welding to join the components. Weld zones result in a morphology that differs from the adjacent areas. This difference in structure represents a defect in the article that can result in premature failure during service. Experiments with a Pulse 830 (a polycarbonate/acrylonitrile-butadiene-styrene blend) engineering resin showed that weld zones made using hot plate techniques, retained only 30% of the unwelded tensile strength, while 80% was retained if vibration welding was applied. Examination of the weld zone by transmission electron microscopy (TEM) revealed a dramatic difference in the microstructure.The weld zone morphology in Pulse" 830 engineering resin by hot plate welding is highly laminar and oriented while a much more homogeneous structure, similar to that in the bulk, is produced by vibration welding. This morphology difference accounts for the variation of the tensile strength of the joints. 相似文献
15.
Li-Xiang Wu Lin-Lin Zhu Wei-Ming Guo Shi-Kuan Sun Wen-Bin Niu Jia-Xiang Xue Jian-Han Zhai Hai-Bin Ma Rui-Lin Lin Hua-Tay Lin Kevin Plucknett Ye-Hong Liao Tong Liu Qi-Sen Ren 《Journal of the European Ceramic Society》2021,41(1):225-232
The joining of liquid-phase sintered SiC (LPS-SiC) ceramics was conducted using spark plasma sintering (SPS), through solid state diffusion bonding, with Ti-metal foil as a joining interlayer. Samples were joined at 1400 °C, under applied pressures of either 10 or 30 MPa, and with different atmospheres (argon, Ar, vs. vacuum). It was demonstrated that the shear strength of the joints increased with an increase in the applied joining pressure. The joining atmosphere also affected on both the microstructure and shear strength of the SiC joints. The composition and microstructure of the interlayer were examined to understand the mechanism. As a result, a SiC-SiC joining with a good mechanical performance could be achieved under an Ar environment, which in turn could provide a cost-effective approach and greatly widen the applications of SiC ceramic components with complex shape. 相似文献
16.
H.X. Li Z.H. Zhong A.K. Yang Z.Q. Wang Q. Wen C. Chen K.J. Song Y.C. Wu 《Ceramics International》2018,44(15):18016-18024
The interfacial microstructure and mechanical properties of B4C-SiC-TiB2 composite joints diffusion bonded with Ti foil interlayer were investigated. The joints were diffusion bonded in the temperature range of 800–1200?°C with 50?MPa by spark plasma sintering. The results revealed that robust joint could be successfully obtained due to the interface reaction. B4C reacted with Ti to form nanocrystalline TiB2 and TiC at the interface at 800–1000?°C. Both the reactions between SiC and Ti and between TiB2 and Ti were not observed during joining. A full ceramic joint consisted of micron- and submicron-sized TiB2 and TiC, accompanied with the formation of micro-crack, was achieved for the joint bonded at 1200?°C. Joint strength was evaluated and the maximum shear strength (145?±?14.1?MPa) was obtained for the joint bonded at 900?°C. Vickers hardness of interlayer increased with increasing the joining temperature. 相似文献
17.
《Ceramics International》2017,43(10):7454-7460
Multi-walled carbon nanotubes (MWCNTs) were used to optimize the microstructure and improve the fracture properties of hot-pressed carbon fiber-reinforced ZrB2-based ultra-high temperature ceramic composites. Microstructure analysis indicated that the introduction of MWCNTs effectively reduced the carbon fiber degradation and prevented fiber-matrix interfacial reaction during processing. Due to the presence of MWCNTs, the matrix contained fine ZrB2 grains and in-situ formed nano-sized SiC/ZrC grains. The fracture properties were evaluated using the single edge-notched beam (SENB) test. The fracture toughness and work of fracture of the Cf/ZrB2-based composite with MWCNTs were 7.0±0.4 MPa m1/2 and 379±34 J/m2, respectively, representing increases of 59% and 87% compared to those without MWCNTs. The excellent fracture properties are attributed to the moderate interfacial bonding between the fibers and matrix, which favour the toughening mechanisms, such as fiber bridging, fiber pull-out and crack deflection at interfaces. 相似文献
18.
Lin Wang Benxue Liu Yongshuai Xie Dehua Ma Luyi Zhu Xinqiang Wang 《Journal of the American Ceramic Society》2019,102(8):4450-4458
High-strength zirconia (ZrO2) continuous fibers, which are potential candidates as ultra-high temperature thermal insulators and reinforced materials, are typically fabricated by dry spinning an organozirconium precursor. However, the uncontrolled decomposition of organozirconium precursor usually occurs upon heat treatment that breaks the continuous fibers into pieces, resulting in the loss of tensile strength. Herein, in this contribution, we aimed to maintain the integrity of ZrO2 precursor fibers during heat treatment. For this purpose, novel high-pressure vapor (HPV) pretreatment of ZrO2 precursor fiber was introduced. The HPV pretreatment is considered to be efficient for the removal of the organics in precursor, promoting the formation of amorphous structures of Zr(OH)4 and Zr(OH)3HCO3. Combining the studies of microstructures and tensile strengths, it was found that the amorphous structures played roles of cross-linking points, keeping the fibers integrity during the followed heat treatment. After HPV pretreatment, the high-strength ZrO2 continuous fibers would be obtained by direct sintering in air without any atmosphere which substantially lowered the cost. The tensile strengths of sintered ZrO2 continuous fibers pretreated by an optimized HPV procedure could reach up to as high as 1.299 GPa. The HPV pretreatment method provides a high-efficiency, low-cost technique for preparing high-quality ceramic fibers. 相似文献
19.
The tensile and shear strengths of adhesively bonded aluminum (Al) joints were inspected in the presence of amino functionalized multi-wall carbon nanotubes (MWCNTs). Tensile and shear tests were carried out using butt and lap-shear joints. The main goal was to compare the effects of dispersion methods of functionalized-CNT into epoxy on the mechanical performances and failure mechanisms of Al joints. Two different types of dispersion procedures, distributing CNT in the hardener (HH method) and distributing CNT in the resin (RR method), were applied. To identify the failure mechanisms, the morphology of fracture surfaces were analyzed using scanning electron microscopy (SEM). Comparing two dispersion methods against one another ascertained that following the RR method for dispersing CNTs in the adhesive displayed larger shear strength, while applying HH method offered fairly greater tensile strength. Moreover, dispersing CNTs in the resin induced more uniform dispersion of CNTs as compared to distributing nanofillers in the hardener. Following RR method, CNTs good dispersion as well as the presence of effective crack growth dissipating mechanisms, increased the shear strength of CNT reinforced adhesive joint. Incorporating CNTs using HH approach encouraged the plastic void formation of epoxy around the agglomerated CNTs, and as a consequence, promoted the plastic deformation under tension. 相似文献