Interfacial Reaction Products Research Articles

Recent Research on the Optimization of Interfacial Structure and Interfacial Interaction Mechanisms of Metal Matrix Composites: A Review

Interfaces in metal matrix composites (MMCs) are crucial in determining the mechanical properties and functionality of MMCs. This article reviews recent scientific advances and issues related to MMC interfaces from four different perspectives: interfacial structural design, interfacial defect control, thermodynamics and kinetics of interfacial reactions, and interfacial microstructure properties‐based numerical simulation. The influence of interfacial microstructural features on interfacial strength–toughness trade‐offs and their functionality is given special attention. The interfacial problem is still one of the main challenges to be solved in the composite system, which is mainly reflected in the following aspects: interfacial microstructure–deformation mechanisms in complex systems, precise control of interfacial defects and interfacial reaction products, and the efficient and cost‐effective application of numerical simulation techniques. The integrated computation and intelligent design (artificial intelligence) of composites through multiscale computational simulation with the guidance of “interface design‐property prediction” will be the key area of MMC interface research in the future.

Electro-Chemo-Mechanical Evolution at the Garnet Solid Electrolyte-Cathode Interface.

Solid-state batteries promise higher energy density and improved safety compared with lithium-ion batteries. However, electro-chemomechanical instabilities at the solid electrolyte interface with the cathode and the anode hinder their large scale implementation. Here, we focus on resolving electro-chemo-mechanical instability mechanisms and their onset conditions between a state-of-the-art cathode, LiNi0.6Mn0.2Co0.2O2 (NMC622), and the garnet Li7La3Zr2O12 (LLZO) solid electrolyte. We used thin-film NMC622 on LLZO pellets to place the interfacial region within the detection depth of the X-ray characterization techniques. The experimental probes of the near-interface region included in operando X-ray absorption spectroscopy and ex situ focused ion beam scanning electron microscopy. Electrochemical degradation was not observable during cycling at room temperature with 4.3 V versus Li/Li+ charge voltage cutoff, or with stepwise potentiostatic hold up to 4.1 V versus Li/Li+. In contrast, secondary phases including reduced transition metal species (Ni2+, Co2+) were found after cycling up to 4.3 V versus Li/Li+ at 80 °C and during potentiostatic hold at 4.3 V versus Li/Li+ (Ni2+). Intergranular cracks between NMC622 grains and delamination at the NMC622|LLZO interface occurred readily after the first charge. These interface reaction products and mechanical failure lowered the capacity and cell efficiency due to partial loss of the NMC622 phase, partial loss of contact at the interface, and a higher polarization resistance. Electrochemical instability between delithiated NMC622 and LLZO could be mitigated by using a low charge voltage cutoff or cycling at lower temperature. Ways to engineer the mechanical properties to avoid crack deflection and delamination at the interface are also discussed for enhancing mechanical stability.

Microstructures and properties of Cu/50 vol% MoS2 composites prepared with Cu-coated MoS2 powders and sintered at different temperatures

Constitution and distribution of phases and interphase reactions are crucial for properties of composites. So far, the problem of MoS2 agglomeration remains unsolved in Cu/MoS2 composites, and interfacial structures and reaction products between MoS2 and Cu have not been fully considered. Herein, Cu-coated MoS2 powders prepared via electroless plating were sintered at different temperatures into Cu/MoS2 composites. Cu does not react with MoS2 in the composites sintered at 600 ℃ and 650 ℃, leading to their desirable tribological properties under dry sliding. Reactions between Cu and MoS2 occur in the composites sintered at 700 ℃ and 800 ℃, and the resultant products include Cu2S, Cu1.8Mo6S8 and Cu1.83Mo3S4 phases, resulting in a better wear resistance under oil lubrication and mechanical properties.

Study on the wettability of Sn/Cu system under ultrasonic vibration

In this study, the wetting behavior of Sn solder on Cu substrate under ultrasonic vibration using the sessile drop method was investigated. The distribution of the vibration field on the substrate surface was analyzed via COMSOL Multiphysics finite element analysis, while the spreading behavior and interfacial reaction products of intermetallic compounds (IMCs) induced by varying ultrasonic amplitudes were explored. ultrasonic vibration demonstrates a significant influence on both wettability and interfacial reaction products. The wetting mechanism under ultrasonic vibration is primarily attributed to physical driving forces generated by ultrasound-induced interfacial viscous boundary layers, along with chemical driving forces facilitated by ultrasonic-accelerated interfacial atomic diffusion and reactions.

Study on wetting mechanism of Sn3Sc alloy on silica and sapphire surfaces

To further investigate the wetting mechanism of filler alloys containing active elements on oxide ceramics surfaces, we prepared a new filler alloy (Sn-3at.%Sc filler alloy) containing trace rare earth elements by vacuum melting furnace. Under high vacuum, its wetting behavior on silica and sapphire substrates was studied using a modified sessile drop method. The final contact angles of liquid Sn-3at.%Sc filler alloy on silica and sapphire surfaces are 6.0° and 9.8°, respectively, showing good wetting properties, and exhibiting similar wetting behavior at the same temperature. The same interfacial product Sc2O3 was detected at the interface of Sn-3at.%Sc/silica and Sn-3at.%Sc/sapphire systems. However, thermodynamic and spreading analysis suggests that Sc2O3 is precipitated in different ways at the interface of the two systems. The former is generated by an interfacial reaction, while the latter precipitates during the cooling process. The wettability of the Sn-3at.%Sc/silica system may depend on the interaction between the interface reaction products and residual scandium adsorption at the solid/liquid interface, while the wettability of Sn-3at.%Sc/sapphire system may depend on the adsorption of Sc-O clusters at the interface. These findings provide a theoretical basis and design ideas for further development of tin-based filler alloys and design of new type filler alloys.

Interfacial reaction mechanism between Y-containing DD5 alloy and Al2O3 ceramic during directional solidification process

This study systematically investigated the influence of varying yttrium(Y) additions on the interfacial reaction mechanism between the DD5 superalloy melt and Al2O3-based ceramic molds during directional solidification. The analysis revealed the formation of a complex multilayer reaction layer at the alloy-ceramic interface. The interfacial products changed from CaO·6Al2O3 to a mixture of various yttrium oxides after Y was added. As the reaction time increased, the sequence of interfacial reaction products observed on the surface of Y-containing alloys progressed as follows: Y2O3, Y4Al2O9, YAlO3, and ultimately Y3Al5O12. Increasing the Y additions promoted the formation of a reaction layer with a higher atomic percentage of Y. The interfacial reaction process between the DD5 superalloy and Al2O3-based ceramic molds involved ceramic decomposition and diffusion, Y element diffusion and displacement reactions, Al2O3 dissolution and further diffusion of the Al element. This process resulted in the formation of different yttrium-aluminum oxides and related to the bidirectional erosion of the Y2O3. These interfacial reactions significantly contributed to the consumption of Y element within the alloy.

Quantifying Chemical Reactions and Interfacial Properties at Buried Polymer/Polymer Interfaces.

Maleic anhydride (MAH)-modified polymers are used as tie layers for binding dissimilar polymers in multilayer polymer films. The MAH chemistry which promotes adhesion is well characterized in the bulk; however, only recently has the interfacial chemistry been studied. Sum frequency generation vibrational spectroscopy (SFG) is an interfacial spectroscopy technique which provides detailed information on interfacial chemical reactions, species, and molecular orientations and has been essential for characterizing the MAH chemistry in both nylon and ethyl vinyl alcohol copolymer (EVOH) model systems and coextruded multilayer films. Here, we further characterize the interfacial chemistry between MAH-modified polyethylene tie layers and both EVOH and nylon by investigating the model systems over a range of MAH concentrations. We can detect the interfacial chemical reaction products between MAH and the barrier layer at MAH concentrations of ≥0.022 wt % for nylon and ≥0.077 wt % for EVOH. Additionally, from the concentration-dependent reaction reactant/product SFG peak positions and the product imide or ester/acid C═O group tilt angles extracted from the polarization-dependent SFG spectra, we quantitatively observe concentration-dependent changes to both the interfacial chemistry and interfacial structure. The interfacial chemistry and molecular orientation as a function of MAH concentration are well correlated with the adhesion strength, providing important quantitative information for the future design of MAH-modified tie layers for a variety of important applications.

Interaction mechanism between DD5 superalloy with different Y content and ceramic molds with Y2O3 layer

DD5 alloys with different Y content were produced by directional solidification (DS) using ceramic molds with the Y2O3 layer. The interaction mechanisms between the corresponding alloys and the Y2O3 layer were discussed. It was found that the Y2O3 layer effectively hindered the direct contact reaction between the active melt and the Al2O3 ceramics, which was conducive to improving the purity of the melt and reducing the loss of Y. Slight dissolution and decomposition of the Y2O3 layer under high temperature melt erosion resulted in the release of Y and O elements into the alloy. The involvement of Y in the melt changed the interfacial reaction mechanism between the Y2O3 layer and the alloy. The interfacial reaction products of melting the DD5 alloy without Y were Al2Y4O9 and Y2O3, while the interfacial reaction product of melting the DD5 alloy with Y was mainly Y2O3.

Joining of silicon nitride ceramic to oxygen‐free copper using Ag–Cu–TiH2 filler

AbstractComplex liquid–solid reactions occur during brazing. A deep understanding of brazing liquid evolution is therefore of important concern for the bonding between filler and substrates. The joining of gas‐pressure‐sintered silicon nitride (Si3N4) ceramic to oxygen‐free copper (OFC) foil was prepared using Ag–Cu–TiH2 filler at 875°C for 0.5 h. The effect of the Ag:Cu ratio on the interfacial microstructure and peeling strength of the joints was analyzed. The reaction of brazing liquid with Si3N4 ceramic includes reactions with both the β‐Si3N4 and the grain boundary phases (Y–Si–Mg–O–N). The resulting interfacial reaction products include TiN, Ti5Si3, and potential Cu3Ti3O. Based on the phase composition and three‐dimensional morphology of the interfacial reaction products in the Si3N4 ceramic/OFC foil joints, a model for the evolution of the brazing liquid as the reaction proceeds was proposed. Peeling test results indicated that the peeling strength of the joints rises unilaterally with the increase of the Ag:Cu ratio in the filler until reaching the peak value of 24.3 N/mm at the maximum Ag:Cu ratio of 90:10. The mechanisms of the joint peeling fracture were discussed in detail.

Interfacial Si–O coordination for inhibiting the graphite phase enables superior SiC/Nb heterostructure joining by AuNi

The reaction between SiC and Ni-based brazing alloy is extremely intense, where the brittle Ni–Si compound and accompanied dissociate graphite phase as the interfacial reaction product in the joint damage the mechanical properties. In this study, the design of "graphite-controlled" heterogeneous integration component structure on SiC surface is developed to weaken the intense reaction of Ni and SiC. The high-quality surface Si–O coordination was successfully achieved by plasma-enhanced chemical vapor deposition (PECVD) method at relatively low temperature on SiC, which increases the Si bond strength due to that the higher binding energy of Si–O (451 kJ/mol) than that of Si–C (347 kJ/mol). SiO2 films enhance the mechanical properties of the joint through macro-weak side interface interlocking and micro-stress mismatch regulation. The shear strength of SiC/Nb heterostructure joints by AuNi alloy was increased by 44 %, which paves an inspiring way for boosting heterogeneous integration of SiC ceramic components.

Achieving high thermal conductivity in CNTs@GF/Al laminates via a rapid and simple strategy

The present work developed a rapid and simple fabrication strategy to achieve the high thermal conductivity (TC) in graphite film (GF)/Al laminates. CNTs@GF prepared by spray flash technique was selected as reinforcement in Al matrix, then consolidated with Al foils by vaccum hot-pressing sintering. Scanning electron microscopy, transmission electron microscopy, X-ray diffraction and Raman spectroscopy were used to evaluate the GF and interface structure. The results revealed that no interfacial reaction products were generated in the highly dense composites. Specially, due to the heat conduction channel and interlocking effects of CNTs on GF/Al interface, the laminated composite containing 56.5 vol% CNTs@GF showed an in-plane TC of 897 W (m k)−1 without bending strength sacrifice. The present work paves an efficient new way to design and fabricate GF/Al laminates for potential thermal management application.

Origins of Fermi Level Pinning for Ni and Ag Metal Contacts on Tungsten Dichalcogenides.

Tungsten transition metal dichalcogenides (W-TMDs) are intriguing due to their properties and potential for application in next-generation electronic devices. However, strong Fermi level (EF) pinning manifests at the metal/W-TMD interfaces, which could tremendously restrain the carrier injection into the channel. In this work, we illustrate the origins of EF pinning for Ni and Ag contacts on W-TMDs by considering interface chemistry, band alignment, impurities, and imperfections of W-TMDs, contact metal adsorption mechanism, and the resultant electronic structure. We conclude that the origins of EF pinning at a covalent contact metal/W-TMD interface, such as Ni/W-TMDs, can be attributed to defects, impurities, and interface reaction products. In contrast, for a van der Waals contact metal/TMD system such as Ag/W-TMDs, the primary factor responsible for EF pinning is the electronic modification of the TMDs resulting from the defects and impurities with the minor impact of metal-induced gap states. The potential strategies for carefully engineering the metal deposition approach are also discussed. This work unveils the origins of EF pinning at metal/TMD interfaces experimentally and theoretically and provides guidance on further enhancing and improving the device performance.

Sustainable application of coal fly ash: One-step hydrothermal cleaner production of silicon-potassium mineral fertilizer synergistic alumina extraction

Coal fly ash (CFA) is the main solid waste discharged from coal-fired power plants, a new method for preparing silicon-potassium mineral fertilizer using KOH hydrothermal treatment CFA was proposed to improve its comprehensive utilization rate and reduce its threat to ecological environment security. In this paper, the characteristics of CFA raw material and transformation residue were studied, the agricultural applicability of the process was verified by pakchoi planting experiments, and the effects of the silicon-potassium mineral fertilizer on soil physical-chemical characteristics were investigated. The results show that increasing the leaching temperature and time can improve the extraction rate of alumina from CFA, and the reaction rate is controlled by the mixing of interfacial chemical reaction and solid product layer diffusion. The CFA raw material was hydrothermally leached at 280 g/L K2O 200 °C for 1 h, in which the Al2O3 extraction rate was 27.46%. The main component of the transformation residue was potassium aluminum silicate hydrate, which is the main component of the silicon-potassium mineral fertilizer, and the effective K2O and SiO2 content is 25.07% and 34.56%. The application of CFA residue can effectively improve the fertility and productivity of the soil, providing nutrients for the growth of pakchoi and improving the soil quality. This research provides theoretical guidance for the preparation of silicon-potassium mineral fertilizer using CFA and has the potential for practical production, which is important for the resourceful use of CFA and its application in agriculture.

Interfacial reaction and interfacial strengthening mechanism of graphene nanosheets reinforced powder metallurgy nickel-based superalloy composite

Graphene nanosheet (GNS) reinforced nickel based superalloy (FGH96) composites with various interfacial reaction degrees were fabricated by powder metallurgy of Hot Isostatic Pressing (HIP) at sintering temperature range of 1120–1190 °C. The interfacial reaction products [Ti, Nb]C particles were formed in FGH96 metal matrix composite by the in-situ reaction between homogeneously-dispersed GNS and FGH96 matrix. In addition, the interfacial reaction products determined by Transmission Electron Microscopy, the interfacial structure was also determined and named clean interface, transition zone and in-situ generation of metal carbides interface. The interfacial [Ti, Nb]C particles on partially reacted with GNS, led to significant improvement of interfacial strength and consequent reinforced the mechanical transfer efficiency in FGH96 metal matrix consequently, compared to those FGH96 without GNS. The role of interfacial [Ti, Nb]C particles played in determining the interfacial bonding strength and interfacial bonding mode of GNS was discussed. This work emphasizes the importance of the interface state of GNS on the interface structure in metal matrix composites, and may provide new insights into the interfacial phenomena and load transfer mechanism in GNS reinforced metal matrix composites.

Wetting behavior and mechanical properties of Sn-10Sb solder/Ni-plated Cu system with different surface structures

The Sn-10Sb alloy is a high-temperature lead-free solder for soldering with Cu substrates. It often causes brittle solder joints and poor reliability due to the generation of an over-thick interfacial layer. Adding Ni plating to Cu substrates can suppress the generation of an excessively thick interfacial layer. This paper investigated the wettability and bonding strength of two different surface structures of Ni-plated Cu substrates with Sn-10Sb solder. Sn-10Sb solder exhibited a contact angle of 69° on the rough Ni-plated Cu substrate and 80° on the smooth one. TEM and XPS analyses demonstrated that the interfacial reaction product between the Ni-plated Cu substrate and the solder was (Cu, Ni)6Sn5. The finer grains on the smooth Ni-plated surface inhibit the diffusion of Cu atoms into the solder and the slower the interfacial reaction rate, which is more conducive to the generation of stable (Cu, Ni)6Sn5 phase. Therefore, the bonding strength ratio between the Ni-plated Cu substrate with a smooth surface and the solder is better.

Formation of ductile close-packed hexagonal solid solution on improving shear strength of Au–Ge/Cu soldering joint

The morphology, chemical composition, mechanical properties of the interface reaction products and their effects on the shear strength of the Au–Ge/Cu soldering joint were systematically investigated. The results showed that a close-packed hexagonal (HCP) structure solid solution phase was formed at the interface after soldering at 400 °C for 5–60 min. The composition of the HCP phase varied among 78–46 at.% Cu, 9–42 at.% Au and ~12 at.% Ge. The Young’s modulus and hardness of HCP phase were 105–112 GPa and 4.3–4.7 GPa, respectively. The shear strength of the 5 min soldering joint was 57 MPa; however, it increased to 68 MPa when the soldering time was prolonged to 60 min. The increasing shear strength can be ascribed to the formation of HCP ductile phase and its effect on depleting the brittle (Ge) phase. It suggested that a HCP structured solid solution formed at the interface could enhance the shear strength of the solder joint.

Reaction Kinetics Investigation of Ni Ohmic Contacts on N-Type 4H-SiC

Investigation of the reaction kinetics between Ni film and 4H-SiC substrate at temperatures which are usually used for ohmic contacts formation provides valuable insights into the studies on fundamental properties of ohmic contacts to 4H-SiC, which are limiting the switching speed, energy efficiency and high-temperature thermal stability of SiC MOSFETs. High Resolution Scanning Electron Microscope (HRSEM) and Raman spectroscopy were used to elaborately characterize the interfacial reaction products under various annealing conditions and to assess the thicknesses of reaction diffusion layers. The square of reaction layer thicknesses versus time followed parabolic law and the apparent active energy of interfacial reaction was derived as 1.5 eV (145 kJ/mol). For Raman spectra, the intensity ratio of two Raman peaks for each nickel silicide detected varied monotonically with temperature in the same trend, indicating that crystal quality of nickel silicide film was improved with annealing temperature rising at micron scale. The red-shift of Ni2Si peak locations at about 140 cm-1 with temperature was suggestive of the polycrystalline Ni2Si film with weaker stress/strain status. Moreover, the in-plane size of graphite cluster aggregating at top surface increased with annealing temperature rising until about 1000°C, which is detrimental to the ohmic contacts from the perspective of device applications.

Influence of B4C Particle Size on the Microstructure and Mechanical Properties of B4C/Al Composites Fabricated by Pressureless Infiltration

To investigate the effect of B4C particle size on the microstructure and mechanical properties of B4C/Al composites, and to provide theoretical guidance for the subsequent thermal processing of composites, B4C/Al composites with varying B4C particle sizes (0.2 µm, 0.5 µm, 1 µm, 10 µm) were fabricated using pressureless infiltration. The microstructure of the composites was characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM), while the mechanical properties were analyzed by hardness test, three-point bending and high temperature compression. The results indicated that Al3BC and AlB2 were the primary interfacial reaction products in B4C/Al composites, and interface reaction could be alleviated with increasing particle size. B4C/Al composites with larger B4C particle sizes exhibited a relatively uniform and discrete distribution of B4C, while those with smaller B4C particle sizes showed agglomeration of B4C. The Vickers hardness and peak flow stress of B4C/Al composites gradually decreased with the increase of B4C particle size, while the bending strength, flexural modulus, and fracture toughness tended to increase. In addition, when B4C particle size was 10 µm, the composites displayed optimal comprehensive performance with the lowest peak flow stress (150 MPa) and the highest fracture toughness (12.75 MPa·m1/2).

Microstructure and tribological properties of Mg matrix composite reinforced with modified graphene

Graphene has recently gained significant interest as a promising lubricant and additive for metal matrix composites. In this work, the microstructure and tribological properties of Mg-based composites were systematically investigated by introducing nano-ZnO modified graphene. It was found that graphene can be uniformly distributed in Mg matrix. In addition, MgO, the interfacial reaction product with nanoscale structure, can enhance the interfacial bonding strength of the composite. Compared to pure Mg matrix, the composite shown significant improvements in hardness and wear resistance. Finally, the mechanism of the wear resistance of the composite was discussed. This work provides technical support and theoretical guidance for the preparation and design of metal matrix composite with high wear resistance.

Corrosion behavior of CMAS coupling NaVO3 salt for plasma-sprayed Al2O3/YSZ thermal barrier coatings

Cost-effective of 20 wt.% Al2O3-7YSZ TBCs were designed and achieved desirable corrosion resistance against CMAS and CMAS + NaVO3 salt (abbreviated as CN). NaVO3 additions decreased the melting point, viscosity and improved the wettability of CMAS deposits, thereby promoting globular zirconia formation and interior infiltration in the TBCs. Furthermore, compared to conventional 7YSZ TBCs, the Al2O3 addition effectively mitigated CMAS- and CN-induced corrosion by limiting the initial melt spreading and subsequent infiltration. This was because Al2O3 dissolution into the CMAS/CN melt modified its thermophysical properties, inducing crystallization and dense layering of the anorthite interfacial reaction product.