Ag Interlayer Research Articles

Investigation of Microstructure and Interfacial Reactions of Diffusion Bonding of Ni-Ti6Al4V Materials Joined by Using Ag Interlayer.

Due to its super plasticity, low weight, and high mechanical resistance properties, generally, Ti6Al4V is used for aeronautical applications. However, it has low resistance to plastic shearing. In addition, it has poor wear resistance. For these reasons, a lot of techniques have been developed to improve its wear resistance. Investigations of microstructure and interfacial reactions of diffusion bonding of Ni and Ti6Al4V materials have been performed experimentally. Ni samples were prepared with 50 ± 5 µm Ni powders in cylindrical shape. For diffusion bonding, Ag foil was used for improving the interlayer and connection quality. Nickel and its alloys can be joined by using some different processes, and the use of an interlayer can further facilitate the joining process and improve the joint quality. The experiments were carried out under the protected atmosphere. Argon gas was used for protection. The experiments were performed under 5 MPa pressure for 60 min duration at 850 °C, 900 °C, and 950 °C thermal conditions. Investigations of metallurgical structure occurring in the interface areas were examined by optic analysis of EDS, SEM, and X-ray. The strength of the joints was tested by lap-shear tests. From observations, the best quality of the coalescence at interfaces was indicated at elevated temperatures.

Understanding interfacial compounds induced by Ag diffusion on improving interface electrical contact resistivity between the Cu electrode and Bi2Te3 thin film

It has been reported that introducing Ag interlayer at the Cu/Bi2Te3 interface can achieve ultra-low electrical contact resistivity. However, there is no consensus on the influence of Ag diffusion induced by Ag interlayer on electrical contact. Thus, the impact of Ag diffusion on electrical contact conductivity for Cu/Ag/Bi2Te3 multilayers was investigated. The generation of interfacial compounds induced by Ag diffusion was analyzed and the contact resistivity was measured in Cu/Ag/Bi2Te3 multilayers with different Ag interlayer thickness before and after annealing. It was found that Ag diffusion induced interfacial compounds Cu4Ag3Te4 at the Cu/Ag interface before annealing, which could decrease contact resistivity to 3.728×10−12 Ω∙m2. After annealing, the relative amount of Cu4Ag3Te4 at the Cu/Ag interface slightly decreased, and the Ag2Te was found to appear at the Ag/Bi2Te3 interface, which could further decrease contact resistivity to 3.187×10−12 Ω∙m2. With Ag interlayer thickness increasing from 50 nm to 300 nm, the contact resistivity decreased from 3.726×10−10 Ω∙m2 to 3.728×10−12 Ω∙m2 before annealing because the relative amount of Cu4Ag3Te4 increased about 5 times, after annealing the contact resistivity further decreased by 10.27∼41.7 % because the relative amount of Ag2Te increased about 1.1 times. In addition, we had optimized the ultra-low contact resistivity test method by redesigning the structure of test samples and modifying the formula of contact resistivity to eliminate two errors. One is caused by Cu electrode short-circuit resistance due to the test current being short-circuited by the middle electrode between two test electrodes. The other is caused by the increased electrical resistance of Bi2Te3 thin film due to Te atom volatilization after annealing. The results showed that the errors of the test results were reduced by at least 21.50 %. Our work provides guidance for further optimizing electrical contact of thin-film thermoelectric devices.

Micro-Ag particle interlayer with high dislocation density for sintered-joining of Al2O3 and AlN in air

A novel sintered-joining of Al2O3 and AlN is achieved for the first time using micro-Ag particle interlayers in air. In comparison with reactive air brazing, this method addresses the issue of reduced strength caused by air holes in brazed joints. Also, this sintered-joining method can be performed at a lower temperature (920 °C), improving the joint strength by relieving the residual stresses. The sintering effect of micro-Ag particles and their high density of dislocations promote the recovery and recrystallization of the Ag interlayer, as well as the interdiffusion of Ag and ceramic. Ag–O clusters formed at the interface can be embedded into oxygen vacancies on the ceramic surface, playing a key role in interfacial joining. By optimizing joining temperature, assembly pressure and holding time, a maximum joint shear strength of 85.2 MPa is achieved at 920 °C for 30 min with an assembly pressure of 1 MPa. This study successfully prepares Al2O3/AlN joints with excellent mechanical properties, providing a reliable foundation for the fabrication of power integrated circuits with efficient operation.

Interface investigations of 2A14Al/Nb explosively welded composites with 1060Al and Ag interlayers: Morphologies, grains, and mechanical properties

Explosive welding (EW) with an interlayer is considered a suitable technology for producing Al/Nb layered composite, but the fundamental process behaviors of this method remain insufficient discussion. Here, contrast EW experiments respectively using 1060Al and Ag sheets as the interlayers were carried out to prepare 2A14Al/Nb composites, and the complex interfacial phenomena and the underlying mechanisms were thoroughly examined by advanced characterizations and theoretical analyses. The microstructure results indicated that the interlayer materials had significant influence on the bonding morphologies, but the defects of the two composites shared the same geometry and distribution characteristics. Combining the microstructures and thermodynamic history, the formation mechanisms of the different defects were revealed. The 2A14Al/Ag/Nb and 2A14Al/1060Al/Nb composites had the advantages of no intermetallic compounds and few defects, respectively, but the latter showed a higher bond strength, suggesting that the geometric defects had more negative effects on mechanical properties than intermetallic compounds. The multi-view EBSD data provided insights into the intricate grain evolutions induced by the EW process, including equiaxed 2A14Al grains and columnar 1060Al grains at the 2A14Al/1060Al interface, and nanoscale Al3Nb grains at the 1060Al/Nb interface. Finally, the correlations between the grain structures and mechanical properties were established by nanoindentation tests.

Joined AZ31B Magnesium Alloys with Ag Interlayer by Ultrasonic-Induced Transient Liquid Phase Bonding in Air

Joined AZ31B Magnesium Alloys with Ag Interlayer by Ultrasonic-Induced Transient Liquid Phase Bonding in Air

Ag interlayer's influence on microstructure and mechanical properties of laser-welded Ta/304L joints

Tantalum and 304L possess unique properties for aerospace applications. Ta offers high temperature and acid/alkali resistance, while 304L is cost-effective with excellent corrosion resistance. Joining Ta and 304L optimises design, lowers costs and meets specific requirements. This study examined laser lap welding of 0.6 mm Ta and 304L with/without silver interlayer. Joint structure and properties were analysed to reveal the influence of detrimental phases, with first principles calculations for TaFe2 and TaCr2. Without Ag interlayer, the joint had 1857.19 N tensile shear force and 530 HV average weld zone hardness. Adding Ag reduced TaFe2 formation, improving tensile shear strength to 2100.30 N with 460 HV average hardness. First principles calculation confirmed TaCr2's superior phase stability over TaFe2.

Effect of Ag interlayer on the microstructural properties and nanocreep behavior of Ti6Al4V/AA7075 dissimilar laser weldments

Creep failure poses a potential risk in dissimilar welded joints between aluminum and titanium alloys, potentially compromising the joint's integrity. This study utilizes laser beam welding (LBW) to achieve dissimilar joining of AA7075 and Ti6Al4V by incorporating an Ag interlayer. The role of Ag interlayer for dissimilar joining of AA7075 and Ti6Al4V alloys and its impact on the microstructure and nanocreep behavior of joints is examined. The findings showed that the use of Ag decreased the interaction of Ti/Al considerably with each other which led to a reduction in the formation of brittle intermetallic compounds. The nanohardness and atomic force microscopy (AFM) results indicated that the Ti6Al4V HAZ exhibited the highest hardness and least plastic deformation, owing to the formation of α′ martensite. The nanoindentation creep analysis revealed the highest stress exponent value in Ti6Al4V HAZ, pointing to a dislocation climb creep mechanism. Additionally, the results also suggested that the observed creep mechanism might be attributed to both diffusional creep and dislocation climb for other zones.

Charge generation layer with Yb assistant interlayer for tandem organic light-emitting diodes

Tandem organic light-emitting diode (OLED) devices require an efficient charge generation layer (CGL) between two stacked OLED units. In this study, a CGL with an Yb assistant interlayer was fabricated and investigated. The optical transmittance and charge generation performances of the CGLs were analyzed with respect to the Yb thickness. The best result was obtained at a Yb thickness of 3 nm, at which both the electrical and optical properties exhibited optimal performances. The optical transmittance was greater than 90 %; this was superior to the performances using Ag and Al interlayers. The insertion of a 3-nm Yb layer reduced the threshold voltage from 18 to 6 V. Capacitance measurements revealed that the insertion of the Yb layer enhanced charge generation in the CGLs, reducing the threshold voltage and enhancing charge transport. The tandem OLED device fabricated using Bphen:Liq/Yb/MoO3/TAPC as a CGL exhibited a 1.92 × enhancement in the current efficiency, which is nearly twice the ideal value, compared to a single-unit device. Thus, Yb is a promising candidate for use as an assistant interlayer in CGLs for high-performance tandem OLED devices.

Interlayer Engineering and Prelithiation: Empowering Si Anodes for Low-Pressure-Operating All-Solid-State Batteries.

Silicon (Si) anodes, free from the dendritic growth concerns found in lithium (Li) metal anodes, offer a promising alternative for high-energy all-solid-state batteries (ASSBs). However, most advancements in Si anodes have been achieved under impractical high operating pressures, which can mask detrimental electrochemo-mechanical issues. Herein, we effectively address the challenges related to the low-pressure operation of Si anodes in ASSBs by introducing an silver (Ag) interlayer between the solid electrolyte layer (Li6PS5Cl) and anode and prelithiating the anodes. The Si composite electrodes, consisting of Si/polyvinylidene fluoride/carbon nanotubes, are optimized for suitable mechanical properties and electrical connectivity. Although the impact of the Ag interlayer is insignificant at an exceedingly high operating pressure of 70MPa, it substantially enhances the interfacial contacts under a practical low operating pressure of 15MPa. Thus, Ag-coated Si anodes outperform bare Si anodes (discharge capacity: 2430vs 1560mAhg-1). The robust interfacial contact is attributed to the deformable, adhesive properties and protective role of the in situ lithiated Ag interlayer, as evidenced by comprehensive ex situ analyses. Operando electrochemical pressiometry is used effectively to probe the strong interface for Ag-coated Si anodes. Furthermore, prelithiation through the thermal evaporation deposition of Li metal significantly improves the cycling performance.

Exploring the role of Ag foam interlayer in alleviating the brittleness of G018 glass sealant for joining YSZ to Mn–Co spinel coated Crofer 22 H

Glass/Glass-ceramic sealing is always accompanied by issues of high porosity and brittle joints. To migrate these problems, an Ag foam was innovatively induced as an interlayer in the process of glass sealing the yttria-stabilized zirconia (YSZ) ceramic to Mn–Co spinel-coated Crofer 22 H stainless steel. Interlayer-added joints showed a significant reduction in porosity, and the shear strength was improved to 52.3 MPa, with an enhancement of 37.8 %. The influence of interlayer on the microstructure of the joint has been investigated and the formation process of the joint is illustrated. The Ag interlayer expels gases from the sealant material through expansion at high temperatures and promotes finer nucleation grains of crystallites integrating with the interlayer, reducing the porosity and alleviating the brittleness as well.

Optical and electrical properties of thin films of MnS/metal/MnS for photocatalysis and gas sensing applications

Thin films of manganese sulfide (MnS) with interlayers of silver and copper were prepared using the thermal evaporation technique for applications in photocatalysis and gas sensing. The structure, morphology, optical, and electrical properties of the deposited films were described by X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM), UV/VIS/NIR spectrophotometer, and two-probe technique. Various parameters such as crystallite size, micro-deformation, dislocation density, optical energy gap, refractive index, extinction coefficient, Urbach energy, dielectric constants, dispersion parameters, activation energy, mobility and, Seebeck coefficient were determined. According to the experimental results, XRD analysis revealed that the MnS powder has a crystalline structure with a cubic phase. While the pure MnS thin films exhibited an amorphous structure, the addition of metals (Ag and Cu) as interlayers resulted in a distinct crystallinity. The pure MnS films had a direct optical energy gap of 3.17 eV, which changed to an indirect transition with energy gaps of 2.43 eV and 2.50 eV when Ag and Cu interlayers were added, respectively. The refractive index values and dispersion of the films depended on the type of interlayer, with all films exhibiting normal dispersion. The temperature dependence of the sheet resistance indicates a semiconducting behavior of the samples, and the addition of the interlayer metal reduced the sheet resistance. Overall, the results suggest that thin films of MnS and MnS/metal/MnS hold promise for organic photocatalysis and gas sensor applications, respectively.

Designing sandwich-structured Ag–SnO2 contact materials: Overcoming the trade-off between erosion resistance and mechanical properties

Designing a second-phase enhancement system for SnO2 microstructures always plays a major role in improving the electrical contact performance of Ag–SnO2 contacts. This study fabricated sandwich-structure Ag–SnO2 contacts to overcome the trade-off between the erosion resistance and mechanical properties of Ag–SnO2 contacts via electrospinning with spark-plasma sintering; subsequently, the influence of SnO2 interlayers on the arc-erosion behaviour and mechanical characteristics of the contacts was investigated. The sandwich structure facilitated a reduction in the hill-and-valley morphology of the contact surface during repetitive erosion; fibrous SnO2 restricted the fluid evaporation of Ag, while SnO2 interlayers dispersed molten bridges, thereby improving the erosion resistance of the system. In parallel, 3D models of the sandwich-structured Ag–SnO2 contacts were reconstructed to investigate the evolution of their mechanical characteristics. Experimental and simulation indicated that the dispersion of stress concentration and reduction in surface deformation induced by the interface effect were the mechanical enhancement mechanisms, while the improvement of impact and wear resistances was attributed to the intensified support provided by the SnO2 interlayers on the matrix surface. Moreover, the synergistic interactions between Ag and SnO2 interlayers mitigated crack initiation and fracture propagation, thereby improving the fracture resistance of the contact matrix. These insights led to a feasible strategy for designing the microstructures of Ag-based contact materials.

Microstructure and Performance Study of Al/Cu Laser Welding with Ag Interlayer

Microstructure and Performance Study of Al/Cu Laser Welding with Ag Interlayer

Controlling the thermal aging and Kirkendall void diffusion speed of sputtered silver interlayers in GaN power semiconductor packaging interfaces for in-wheel motor system integrations

We investigate the role of an Ag interlayer to suppress Kirkendall void formation in Ti/Ni surface finishes on the die-attached joints during harsh thermal aging tests at 250 °C. GaN dies were attached to the Ti/Ag/Ni sputtered direct bonded aluminum (DBA) and Ti/Ni sputtered DBA substrate using a high-temperature soldering, respectively. Without the Ag interlayer, void size increased to 0.69 µm after 1000 h of aging, but with the Ag interlayer, it reduced to 0.0794 µm. The Ag interlayer retards the development of cracks and void coalescing by controlling the diffusion rate between Ni/Sn at the bonding interface during thermal aging.

Plasmonic Ag Interlayer Induced Direct Energy Transfer Studied at Single-Particle Level

Plasmonic Ag Interlayer Induced Direct Energy Transfer Studied at Single-Particle Level

Highly stable quantum dot light-emitting diodes with improved interface contacting via violet irradiation

The relatively low stability of quantum dot light-emitting diodes (QLEDs) caused by unbalanced carrier injection has not been completely solved. Among various influencing factors, interface contacting is one of the important factors affecting the carrier injection equilibrium. Herein, we proposed a method to improve the carrier injection equilibrium for QLEDs. We investigated and explored the effects of violet irradiation on the efficiency and operating stability of MoO3-based inverted QLEDs. Specifically, violet irradiation on the interface of MoO3/Mg:Ag is carefully analysed. Further research shows that the interfacial reaction between Mg:Ag anode and MoO3 hole injection layer accounts for such improvement. During violet irradiation, the Mg:Ag quickly reacts with the oxygen from MoO3, leading to the formation of Mo-O-Mg:Ag interlayer. The hole injection is effectively enhanced, resulting from the reduction of the electrons extraction barrier at MoO3/Mg:Ag interface and the improvement of the interface contacting. By optimizing the violet irradiation dosage and violet wavelength, the maximum current efficiency (CE) is increased from 20.2 cd/A to 31.1 cd/A. Moreover, devices exhibit a highly stable operation lifetime of 44161 h (T95@1000 nits), which is much longer than non-violet irradiation QLEDs and meet the stringent industrial requirements for display applications.

Elucidating the effect of Ag interlayer formation on the intrinsic mechanical properties of free-standing ITO/Ag/ITO thin films

The impact of Ag interlayer formation governing the intrinsic mechanical behavior of ITO/Ag/ITO thin films is proposed, which can fundamentally contribute to the robust design of advanced flexible electronics.

Effects of silver interlayer thickness on the microstructure and properties of electron beam welded joints of TC4 titanium and 4J29 Kovar alloys

Abstract Electron beam welding of TC4 titanium alloy and 4J29 Kovar alloy was performed by using different thicknesses of silver interlayers. The microstructure and the composition of welded joints were characterized by scanning electron microscopy, X-ray diffraction, and energy-dipersive spectrometry. The mechanical properties of welded joints were evaluated by tensile strength tests. The results indicated that Ag thickness has great effects on the weld appearance, microstructure, and mechanical properties of electron beam-welded joints. In case of 0.3 and 0.4 mm thickness of Ag interlayers, a considerable part of 4J29 and TC4 melts and a large amount of Fe, Ti, and Ni elements diffuse into the molten pool forming intermetallic compounds (IMCs) such as TiFe2, NiTi, and FeTi. In case of 0.6 mm thickness of Ag interlayer, the welded joint exhibits brazing characteristics with little IMCs near the fusion line of 4J29 Kovar alloy side. When the thickness of the Ag interlayer increases to 0.8 mm, the diffusion of Ti and Fe elements is completely inhibited by Ag. As the thickness of the Ag interlayer increases from 0.3 to 0.8 mm, the tensile strength of the welded sample shows a phenomenon that first rises and then falls, and the largest tensile strength is 243 MPa.

Thermally stable and transparent F-doped SnO2 (FTO) /Ag/FTO films for transparent thin film heaters used in automobiles

We investigated the characteristics of F-doped SnO2 (FTO)/Ag/FTO films prepared using thermal evaporation at room temperature for the application of the as-formed films in transparent thin film heaters (TFHs) of automobiles. To optimize the electrical and optical properties of the FTO/Ag/FTO multi-layer, the figure of merit (FoM) values of the FTO/Ag/FTO multi-layers were compared as a function of the thickness of the Ag and FTO layers. The sheet resistance and optical transmittance of the FTO/Ag/FTO multi-layer were primarily affected by the Ag inter-layer and bottom/top FTO thicknesses, respectively. At optimized Ag (10 nm) and FTO (40 nm) thicknesses, we fabricated a FTO/Ag/FTO electrode with a sheet resistance of 8.00 Ohm/square, an optical transmittance of 83.04 % at a visible wavelength (400–800 nm) and a FoM value of 19.49 Ohm-1. The TFHs comprising the optimal FTO/Ag/FTO electrode exhibited a saturated temperature of 117 °C at a low operating direct current of 6 V, owing to the low sheet resistance. In addition, the FTO/Ag/FTO-based TFHs exhibited thermally stable performances owing to the stability of the bottom and top FTO electrodes. The performance of the FTO/Ag/FTO-based TFHs demonstrated that the thermally evaporated FTO/Ag/FTO multi-layer is a promising, stable, and transparent electrode material for application in the front window TFHs used in automobiles.

Effect of Ag interlayer on friction torque, mechanical properties and microstructure of large diameter aluminum/steel joints by continuous drive friction welding

The large diameter aluminum/steel continuous driven friction welding component is prone to overload of the main motor due to high friction torque in the welding process. Therefore, multistage friction is used in industrial production to avoid overloading the main motors. However, multistage friction usually increases the heat input in the welding process and leads to the formation of thick and heterogeneous FeAl intermetallic compounds at the welding interface, which degrades the mechanical properties of the joints. Adding an Ag interlayer to the aluminum/steel interface can reduce the friction torque in the welding process, inhibit the interdiffusion of FeAl elements and reduce the thickness of FeAl intermetallic compounds. In this study, Q235 low-carbon steel rods (Diameter of weld end = 120 mm) with/without Ag interlayer and 1060 pure aluminum rods (Diameter of weld end = 90 mm) were welded by continuous drive friction welding. Voltage and Current of Major Motor (VCMM) in the welding process were processed and analyzed. The effects of the Ag interlayer on friction torque, mechanical properties of the post-weld joint and microstructure at the welding interface were analyzed. The research shows that the Ag interlayer can effectively reduce the initial peak torque and joint temperature in the welding process. The mechanical properties and intermetallic compound thickness of the post-weld joint still exhibit heterogeneity along the radial direction. The strength and toughness are significantly improved in the region of 0.5– 0.8R from the center, which is because the Ag2Al and Ag3Al phases with better toughness are formed in this region due to the change of the flow form of the interfacial viscoplastic metal by the Ag interlayer.