Metal Interlayer Research Articles

Optimizing weld strength and microstructure in CP-titanium and 304 stainless steel friction welds with chromium interlayer

This study investigates the effect of a Cr-interlayer on the hardness and friction-welded joint strength between CP-titanium and 304 stainless steel. Rotary friction welding, with its adjustable parameters such as upset pressure, is the preferred method for this dissimilar joint. Due to the difference between these two base metals, a metallic interlayer like chromium, is crucial for controlling the formation of intermetallic compounds (IMCs). Welding was conducted at three different upset pressures, both with and without the Cr-interlayer. Tensile and microhardness tests were performed, complemented by phase analysis and microstructural characterization using XRD and SEM. Our findings reveal that employing a chromium layer and higher upset pressures enhances strength while reducing the presence of brittle IMCs in the welds. At the CP-titanium side, dynamic recrystallization occurs due to increased heat generation at the interface and strain occurred by materials flow, facilitating IMC formation, especially evident at 250 MPa upset pressure. Interestingly, relatively higher strength at 150 MPa is attributed to the absence of IMCs. Conversely, higher strength results at 350 MPa due to from the flow of softened material, effectively purging IMCs from the weld zone. Notably, both β-titanium and chromium-based IMCs form in the presence of the chromium interlayer, resulting in decreased joint hardness and increased overall ductility. In conclusion, our study's findings contribute to bridging the gap between theoretical strength and practical application, significantly advancing joint performance.

Transparent (Ni,Au)/ZnO:Al-Based Ohmic Contacts to p-Type GaN as an Insight into the Role of Ni and Au in Standard p-Type GaN Contacts.

In this work, Ni/ZnO:Al and Au/ZnO:Al structures are proposed as efficient ohmic contacts to p-GaN. Through a careful selection of deposition parameters and annealing environment, we not only achieve the formation of high-quality ohmic contacts but also gain insights into the interfacial reactions, enhancing the understanding of conventional Ni/Au contact formation on p-GaN. In particular, the notion that the presence of NiO at the interface is enough for an ohmic contact to form is challenged by showing that in fact it has to be NiO formed at the interface from metallic Ni and additional oxygen. An Au-based ohmic contact is also presented, and its formation mechanism is explained, contrary to popular knowledge that Au does not form an ohmic contact with p-GaN. The obtained contacts are low resistivity, with contact resistances of 4.77 × 10-3 Ω·cm2 and 3.34 × 10-3 Ω·cm2 for Au-based and Ni-based ones, respectively. What is also important is that we show these oxide-based contacts with metallic interlayers give lower series resistances in simplified diode structures than a standard Ni/Au-based contact, making them promising for optoelectronic devices.

Recent Developments in Low Temperature Wafer Level Metal Bonding for Heterogenous Integration

Abstract An overview of various low-temperature (<200°C) wafer bonding processes using metal interlayers is presented. Such processes are very attractive for novel applications in 3D heterogenous packaging as the allow for simultaneous formation of electrical interconnects, as well as hermetic encapsulation of various sensors and microelectromechanical systems-based devices. Metal wafer bonding is a generic category of processes consisting of various sub-categories, each one defined by the different principles governing the process. One can differentiate between eutectic wafer bonding (a eutectic alloy is formed as bonding layer during the process by liquid-solid interdiffusion), intermetallic wafer bonding (an intermetallic alloy is formed as bonding layer during the process by solid-liquid interdiffusion, a process known also as solid liquid intermetallic diffusion transient liquid phase, and metal thermo-compression wafer bonding. Different critical/gating parameters were investigated and their impact for generally reducing processing temperatures for the different metal bonding systems was studied.

Effect of diffusion barriers on steam oxidation properties and interface evolutions of Cr coating for zirconium alloy at 1200 °C

Currently, Cr-based coatings are considered the most promising protective coatings for zirconium alloy claddings under the ATF design concept. However, the primary factor affecting the oxidation resistance of Cr coatings is the interdiffusion of Cr and Zr. In this study, Cr coatings with three refractory metal interlayers of Nb, Mo, and Ta were deposited on zirconium alloy surfaces using closed-field unbalanced magnetron sputtering. The study investigated the effects of different interlayers on the microstructure, oxidation properties, and interface evolution process of Cr coatings under steam conditions at 1200 ℃, and compared them with Cr coatings without intermediate layers. The results indicate that the refractory metal interlayer influences the orientation and growth rate of Cr coating grains. The formation of a Laves phase mixed layer in the interlayer during oxidation effectively hinders the diffusion of O and Cr to the zirconium alloy matrix, enhancing its oxidation resistance. Furthermore, the diffusion rate and vacancy concentration of Mo and Ta elements to the Zr layer exceed that of diffusion to the Cr layer. During the cooling process, a precipitate phase forms in the Zr-4 matrix, while the Nb coating forms an infinite solid solution in the β-Zr.

Novel graphite-based boron-doped diamond coated electrodes with refractory metal interlayer for high-efficient electrochemical oxidation degradation of phenol

Electrode materials are fundamental to electrochemical advanced oxidation processes (EAOPs), while the selection of the substrate material will greatly affect the performance of the electrode material in practical applications. In this work, we firstly reported that the graphite-based boron-doped diamond (BDD) coated electrodes were prepared by pre-depositing a refractory metal (Mo/Nb/Ti/Ta) interlayer on graphite substrate and then depositing the BDD coating. The effects of different interlayers on microstructure, chemical composition, electrochemical properties, and phenol oxidation degradation ability of the electrodes were systematically investigated. Compared with the electrodes with other interlayers (interlayer=Mo, Nb, Ti), the graphite/Ta/BDD coated electrode exhibits a lowest charge transfer resistance (21.29 Ω·cm2), highest carrier concentration (∼1022 cm−3), widest electrochemical window (from −1.34 V to 2.61 V) and fastest electron transfer capability (k0=5.77×10-3), and achieves the high-efficient degradation of phenol organic wastewater. The as-prepared graphite-based BDD coated electrodes with refractory metal interlayer can provide a new strategy for the development of electrode materials in EAOPs.

Josephson effect in a fractal geometry

The Josephson effect is a hallmark signature of the superconducting state, which, however, has been sparsely explored in non-crystalline superconducting materials. Motivated by this, we consider a Josephson junction consisting of two superconductors with a fractal metallic interlayer, which is patterned as a Sierpiński carpet by removing atomic sites in a self-similar and scale-invariant manner. We here show that the fractal geometry has direct observable consequences on the Josephson effect. In particular, we demonstrate that the form of the supercurrent–magnetic field relation as the fractal generation number increases can be directly related to the self-similar fractal geometry of the normal metallic layer. Furthermore, the maxima of the corresponding diffraction pattern directly encode the self-repeating fractal structure in the course of fractal generation, implying that the corresponding magnetic length directly probes the shortest length scale in the given fractal generation. Our results should motivate future experimental efforts to verify these predictions in designer quantum materials and motivate future pursuits regarding fractal-based SQUID devices.

Lithiation: A Pathway to Strengthen Sodiophilic Metal Interlayer of 3D Metallic Skeleton for High-Performance Sodium Metal Anodes.

Constructing a three-dimensional (3D) skeleton with a sodiophilic-modified layer (SML) has been proven to be an effective strategy to alleviate excessive volumetric deformation and continuous dendrite growth for sodium (Na) metal anodes. However, the weak binding force and violent reaction between the SML and the 3D skeleton lead to numerous cracks/defects and even pulverization of the SML during repeated Na plating/stripping. Herein, a lithiation pathway is presented to construct a sodiophilic Li-Sn alloy layer onto a 3D copper mesh to strengthen the SML for stable Na metal anodes. The lithiation 3D skeleton exhibits superior sodiophilicity, higher charge-transfer efficiency, and lower ion-diffusion barrier, contributing to the homogenization of ion-electronic flux and Na deposition. Simultaneously, the dense Li-Sn alloy is more stable than the monometal Sn-layer, which effectively prevents damage to the SML and enhances the stability of the SML. As a result, the asymmetrical cell exhibits great performance with a negligible nucleation overpotential and a high average Coulombic efficiency of 99.4%. Moreover, the full cell assembled with Na3V2(PO4)3 cathode delivers superior capacity retention of 91.3% after 1000 cycles at a current of 3C.

Ambient printing of native oxides for ultrathin transparent flexible circuit boards.

Metal oxide films are essential in most electronic devices, yet they are typically deposited at elevated temperatures by using slow, vacuum-based processes. We printed native oxide films over large areas at ambient conditions by moving a molten metal meniscus across a target substrate. The oxide gently separates from the metal through fluid instabilities that occur in the meniscus, leading to uniform films free of liquid residue. The printed oxide has a metallic interlayer that renders the films highly conductive. The metallic character of the printed films promotes wetting of trace amounts of evaporated gold that would otherwise form disconnected islands on conventional oxide surfaces. The resulting ultrathin (<10 nanometers) conductors can be patterned into flexible circuits that are transparent, mechanically robust, and electrically stable, even at elevated temperatures.

Phase Engineering of Two-Dimensional WS2 Nanostructures for Superior Hybrid Supercapacitors

Two-dimensional (2D) tungsten sulfide (WS2) has recently emerged as a nontrivial material for electrochemical applications; however, the boundaries associated with its 1T (instability) and 2H (low electrical conductivity) phases limit its electrochemical parameters. In this work, this issue is addressed using an exclusive chemical approach to evolve a dual-phase 1T-2H WS2 heterostructure that combines two different 1T (trigonal) and 2H (hexagonal) phases directly on the current collector which demonstrated 2D transformable phase structure, large interlayer distance, and highly exposed edge active sites. A simple inert-atmosphere annealing approach under phosphorus vapors is designed to elicit a fractional phase conversion of WS2 from conventional 2H to the 1T phase, where phosphorus is accommodated in the WS2 interspace and lattice, resulting in interlayer expansion. Theoretical calculations confirmed that the 1T WS2 structure formed after phosphorus doping exhibits semimetallic feature with no band gap, thereby elucidating the high electrical conductivity. The presence of edge-enriched metallic phase and interlayer engineering of 1T-2H WS2 heterostructure validates the exceptional sodium (Na+) ion intercalation when tested in hybrid supercapacitor (HSCs) against Prussian blue analog (PBA) cathodes. As a result, the assembled HSC cell with a 1T-2H WS2 heterostructured anode and a CuFe-PBA cathode shows superior specific energy of 65.5 Wh kg-1 at a specific power of 784 W kg-1, and maintains 75% rate capability and 95.7%cycling stability over 10,000 cycles. This work paves a technique for engineering a simple phase transition of 2D materials and sheds light on the expansion of high-performance next-generation energy storage systems.

Enhanced through-plane thermal conductivity of graphene membranes by the interlayer microstructure manipulation: Multiscale numerical simulations and experimental verifications

Graphene, with ultrahigh in-plane thermal conductivity (IPTC), has been widely applied in the thermal dissipation of integrated circuits. However, the extremely low through-plane thermal conductivity (TPTC) of graphene limits its further application. In this work, a novel strategy was proposed to enhance the TPTC of graphene membranes (GNMs) by improving the interlayer bonding state through interlayer decoration with metal elements. Molecular dynamics simulations demonstrated that decoration with interlayer elements (Al, Ti, and Ni) enhanced the interfacial thermal conductance. This was attributed to interfacial chemical bonding through strong interfacial interactions (intensive electron localization) formed at the interface between metal and GN sheets as implied by the first principles calculations. Furthermore, the composite GNMs decorated with interlayer metal nanoparticles (Al, Ni, and Co) were prepared through co-reduction using thermal decomposition method. The corresponding TPTC was tested using time-domain thermoreflectance (TDTR) method which was much higher for the composite GNMs (175–400 W/m·K) than for pure GNM (∼140 W/m·K), and this was in consistent with the simulation results. Interlayer decoration, which enhanced the TPTC of GNMs, provides a novel and effective strategy for enhancing the overall thermal management performance of graphene-based materials in both vertical and horizontal directions.

Liquid Metal Interlayer for Ultrastable Solid-State Sodium Metal Battery.

Solid-state sodium metal batteries have attracted wide attention due to their high energy density, remarkable safety, and abundant sodium resources. However, the growth of Na dendrites and poor interfacial contact between Na metal anode and Na3Zr2Si2PO12 (NZSP) solid-state electrolytes severely limit their practical application. Herein, a wettable liquid metal (GaIn) interlayer significantly reduces the interfacial resistance and avoids the formation of voids at the Na/NZSP interface. Moreover, the Ga4Na and NaIn alloys at the interface caused by the spontaneous reaction of GaIn with Na metal enhance the bond of NZSP with Na anode, which provides a continuous Na+ diffusion pathway and homogeneous Na+ flux to suppress Na dendrite growth. The symmetric cell can cycle stably for over 6500h at 0.05mA cm-2 and over 3000h at 0.1mA cm-2, with a critical current density of 0.8mA cm-2 at 25°C, and the interfacial resistance is significantly reduced to 21.6 Ω from 1095.1 Ω. The full cell coupled with NaNi1/3Fe1/3Mn1/3O2 also shows outstanding cycling performance, maintaining 85.1% capacity after 100 cycles at 0.5 C. This work demonstrates that the liquid metal interlayer has a large potential for the practical application of solid-state metal batteries.

Tuning the microstructure of biomass-derived hard carbons by controlling the impurity removal process for enhanced Na ion storage performance

Biomass-derived hard carbons are promising anode materials of sodium-ion batteries (SIBs) due to their low cost, renewability and high specific capacity. However, there are inevitably some impurities in biomasses that may not only affect the purity, but microstructure and electrochemical performance of hard carbons. Although the impurities can be removed by appropriate treatments after carbonization, the microstructure of hard carbons can hardly be changed. In this work, taking ficus macrophylla leaves (FMLs) as the model biomass, the effects of impurities and their removing process on the microstructure and Na ion storage performance of hard carbons are investigated. It is found that the presence of Ca and Si-bearing impurities in FMLs results in more graphite-like structure in hard carbons because of their catalytic graphitization effect. The acid and base washing processes after carbonization can mostly get rid of the inorganic impurities is unable to increase the plateau region capacities associating to Na ion insertion in the interlayer of graphitic microcrystals and Na metal filling in micropores. By contrast, by stepwisely removing the Ca and Si-bearing impurities from raw materials before carbonization, hard carbons with high purity, larger interlayer space and more micropores are produced, which exhibit a high reversible specific capacity of 336 mAh g−1 at 20 mA g−1, a high initial Coulombic efficiency of 93 %, excellent rate capability (245 mAh g−1 at 2 A g−1) and robust cycle stability. This study implies that controlling the impurity removal process can simultaneously tune the microstructure of hard carbon anodes derived from biomasses towards high performance Na ion storage.

Differentiating contribution of electron–phonon coupling to the thermal boundary conductance of metal–metal–dielectric systems

Electron–phonon coupling thermal resistance in metals is a key factor affecting the thermal boundary conductance (TBC) of metal–metal–dielectric systems. However, quantitatively differentiating the contribution of electron–phonon coupling to TBC is still a challenge, as various thermal resistances are coupled in a complicated manner at the metal–metal–dielectric interface. Herein, we propose a two-step strategy to study electron–phonon coupling. We first decouple the phonon–phonon thermal conductance (TBCp-p) between metallic interlayer and dielectric from the metal–metal–dielectric interface by experimentally characterizing the TBCp-p of a single metallic interlayer deposited dielectric with the transient thermoreflectance technique; Combining metal–metal–dielectric TBC measurement and a thermal circuit model with measured TBCp-p as input, the contribution of electron–phonon coupling to TBC of the metal–metal–dielectric system is differentiated quantitatively. For the Au–Ni–GaN system, the contribution of electron–phonon coupling thermal resistance in the Ni interlayer (Re−ph,Ni) is substantially higher at lower Ni interlayer thickness, reaching 35% at ∼1 nm Ni. The electron–phonon coupling constant of Ni (gNi) was fitted in the range of 6.4 × 1016–36 × 1016 W/m3K. The above results were also verified in the Au–Ni–SiC system. This study will promote a deeper understanding of the thermal transport in the metal–metal–dielectric system and provide an insightful indication for the manipulation of TBC in this system.

Tuning the Topo-Morphological properties of ITO Films using Al-Ag interlayer for Low-Resistance Optoelectronics Devices

Indium tin oxide (ITO) is recently attracting intense attention for application as transparent conducting electrode in different optoelectronic devices including solar cells, liquid crystal displays and organic light emitting diodes. This is attributed to their high optical transmittance in the visible region and good electrical conductivity. In this work, surface topological-morphological (topo-morphological) and electrical properties of ITO based multilayer films with aluminum-silver (Al-Ag) metal interlayer (ITO/Al-Ag/ITO) are investigated after post annealing treatment at 300-500oC by atomic force microscopic (AFM), field emission scanning electron microscopy (FESEM), four-point probe and hall-effect techniques respectively. The ITO/Al-Ag/ITO films are deposited by direct current and radio frequency magnetron sputtering techniques on p-type Si at room temperature. The results showed a smooth surface topology by as-deposited film with films smoothness improving after post annealing treatment as analyzed by AFM method. Sharp crystallites peaks were obtained by all the films with smaller peaks diffusing and recombining to form larger films with increasing post-annealing temperature. The films root means square roughness increased as the temperature increases with film annealed at 500oC showing a superior and enhanced microstructure. Compared to as-deposited film, careful observation shows that surface morphology smoothness increased with increase in temperature with films annealed at 400oC and 500oC showing highest increasing surface smoothness pattern as determined by FESEM technique. Similarly, higher grain sizes are observed especially by films annealed at 400oC and 500oC due to the heat absorption which causes the particles to expand thereby narrowing the grain boundaries and subsequently improve the surface smoothness. These FESEM findings are consistent with AFM measurements confirming the high surface property and enhanced grain size with increasing post annealing temperature. The films exhibit decreased electrical resistivity and sheet resistance while carrier concentration and Hall mobility increased with increasing post annealing treatment indicating highest corresponding values of...

Protons intercalation induced hydrogen bond network in δ-MnO2 cathode for high-performance aqueous zinc-ion batteries

Birnessite-type MnO2 (δ-MnO2) exhibits great potential as a cathode material for aqueous zinc-ion batteries (AZIBs). However, the structural instability and sluggish reaction kinetics restrict its further application. Herein, a unique protons intercalation strategy was utilized to simultaneously modify the interlayer environment and transition metal layers of δ-MnO2. The intercalated protons directly form strong O H bonds with the adjacent oxygens, while the increased H2O molecules also establish a hydrogen bond network (O H···O) between H2O molecules or bond with adjacent oxygens. Based on the Grotthuss mechanism, these bondings ultimately enhance the stability of layered structures and facilitate the rapid diffusion of protons. Moreover, the introduction of protons induces numerous oxygen vacancies, reduces steric hindrance, and accelerates ion transport kinetics. Consequently, the protons intercalated δ-MnO2 (H-MnO2-x) demonstrates exceptional specific capacity of 401.7 mAh/g at 0.1 A/g and a fast-charging performance over 1000 cycles. Density functional theory analysis confirms the improved electronic conductivity and reduced diffusion energy barrier. Most importantly, electrochemical quartz crystal microbalance tests combining with ex-situ characterizations verify the inhibitory effect of the interlayer proton environment on basic zinc sulfate formation. Protons intercalation behavior provides a promising avenue for the development of MnO2 as well as other cathodes in AZIBs.

Thermal spray coatings for molten salt facing structural parts and enabling opportunities for thermochemical cycle electrolysis

AbstractThermochemical water splitting stands out as the most efficient techniques to produce hydrogen through electrolysis at a high temperature, relying on a series of chemical reactions within a loop. However, achieving a durable thermochemical cycle system poses a significant challenge, particularly in manufacturing suitable coating materials for reaction vessels and pipes capable of enduring highly corrosive conditions created by high‐temperature molten salts. The review summarizes thermally sprayed coatings (deposited on structural materials) that can withstand thermochemical cycle corrosive environments, geared towards nuclear thermochemical copper–chlorine (CuCl) cycles. An assessment was conducted to explore material composition and selection (structure–property relations), single and multi‐layer coating manufacturing, as well as corrosion environment and testing methods. The aim was to identify the critical areas for research and development in utilizing the feedstock materials and thermal spray coating techniques for applications in molten salt thermochemical applications, as well as use lessons learnt from other application areas (e.g., nuclear reaction vessels, boilers, waste incinerators, and aero engine gas‐turbine) where other types of molten salt and temperature are expected. Assessment indicated that very limited sets of coating‐substrate system with metallic interlayer is likely to survive high temperature corrosive environment for extended period of testing. However, within the known means and methods, as well as application of advanced thermal spray manufacturing processes could be a way forward to have sustainable coating‐substrate assembly with extended lifetime. Spraying multi‐layered coating (nano‐structured or micro‐structured powder materials) along with the application of modern suspension or solution based thermal spray techniques are considered to result in dense microstructures with improved resistance to high temperature thermochemical environment.

Adhesion improvement of sputtered Cu films on flexible polymer substrates through the design of metal interlayers

Magnetron sputtering is an alternative approach to prepare flexible copper clad laminates because of low cost and thin copper clad laminate thickness. However, Cu film has poor adhesion when directly deposited on polymer substrates, imposing certain limits to the use of magnetron sputtering technique. This work aims to improve the adhesion between the copper film and the polymer substrate. In this work, we succeeded improved the adhesion between the polymer substrates and copper film by introducing different metal interlayers into the polymer/Cu interfaces. It was found that the the copper films with Ni interlayer have the best adhesion with polymer substrates. This study proposes a promising route to overcome the wear adhesion problem between Cu film and polymers in the preparation of magnetron sputtered flexible copper clad laminates.

Improving interfacial strength at room and elevated temperatures in ultrasonic welding of pure titanium: Interlayer-induced phase transformation and concentrated plastic deformation

Ultrasonic welding (USW) of Titanium (Ti) sheets presents several challenges, notably crack formation due to sliding friction. To overcome this problem, the present study applied USW to pure α-Ti sheets both with and without different interlayer metals (Al, Ni, and Fe). Al interlayer improved the strength at room temperature significantly to cause base metal fracture (1700 N) by inducing concentrated plastic deformation, facilitating bonding with Ti while minimizing damage. However, its strength decreased significantly at 150–300 °C, suggesting the limitation of using Al interlayer at elevated temperatures. Conversely, the Ni and Fe interlayers led to a two-phase strength development. This enhancement was due to β-phase transformation, which reduces the interfacial defects and generates a more pronounced β-stabilization effect. The Ni interlayer, which has a higher β-transus point (765 °C) and lower molybdenum equivalency, required a higher welding energy (1800 J) and longer diffusion time into Ti, resulting in a gradual increase in strength due to a slower β-Ti transformation. On the other hand, the Fe interlayer with a lower β-transus point relative to Ti (595 °C) achieved peak strength at a lower welding energy of 1200 J. Both Fe and Ni interlayers displayed only a slight decrease in strength (1500–1600 N) at 300 °C with base metal fracture, revealing better joint performance at higher temperatures. These insights suggest a strategical interlayer selection based on the operation temperature, where Al interlayers were advantageous for low-energy welding at room temperature application, Fe and Ni interlayers offer sufficient strength at elevated temperatures by facilitating the β-Ti formation.

Bonding of ceramics to silver-coated titanium-A combined theoretical and experimental study.

It would be very beneficial to have a method for joining of ceramics to titanium reliably. Although several techniques have been developed and tested to prevent extensive interfacial chemical reactions in titanium-ceramic systems, the main problem of the inherent brittleness of interfaces was still unsolved. To overcome this problem also in dental applications, we decided to make use of an interlayer material that needs to meet the following requirements: First, it has to be biocompatible, second, it should not melt below the bonding temperatures, and third, it should not react too strongly with titanium, so that its plasticity will be maintained. Considering possible material options only the metals: gold, platinum, palladium, and silver, fulfill the first and second requirements. To find out-without an extensive experimental testing program-which of the four metals fulfills the third requirement best, the combined thermodynamic and reaction kinetic modeling was employed to evaluate how many and how thick reaction layers are formed between the interlayer metals and titanium. With the help of theoretical modeling, it was shown that silver fulfills the last requirement best. However, before starting to test experimentally the effect of the silver layer on the mechanical integrity of dental ceramic/Ag/Ti joints it was decided to make use of mechanical analysis of the three-point bending test, the result of which indicated that the silver layer increases significantly the bond strength of the joints. This result encouraged us to develop a new technique for plating silver on titanium. Subsequently, we executed numerous three-point bending tests, which demonstrated that silver-plated titanium-ceramic joints are much stronger than conventional titanium-ceramic joints. Hence, it can be concluded that the combined thermodynamic, reaction kinetic, and mechanical modeling method can also be a very valuable tool in medical research and development work.

Influence of Hydrothermal Modification on Adsorptive Performance of Clay Minerals for Malachite Green.

Artificially modified adsorbing materials mainly aim to remedy the disadvantages of natural materials as much as possible. Using clay materials such as rectorite, sodium bentonite and metakaolinite (solid waste material) as base materials, hydrothermally modified and unmodified materials were compared. CM-HT and CM (adsorbing materials) were prepared and used to adsorb and purify wastewater containing malachite green (MG) dye, and the two materials were characterized through methods such as BET, FT-IR, SEM and XRD. Results: (1) The optimal conditions for hydrothermal modification of CM-HT were a temperature of 150 °C, a time of 2 h, and a liquid/solid ratio 1:20. (2) Hydrothermal modification greatly increased the adsorptive effect. The measured maximum adsorption capacity of CM-HT for MG reached 290.45 mg/g (56.92% higher than that of CM). The theoretical maximum capacity was 625.15 mg/g (186.15% higher than that of CM). (3) Because Al-OH and Si-O-Al groups were reserved in unmodified clay mineral adsorbing materials with good adsorbing activity, after hydrothermal modification, the crystal structure of the clay became loosened along the direction of the c axis, and the interlayer space increased to partially exchange interlayer metal cations connected to the bottom oxygen, giving CM-HT higher electronegativity and creating more crystal defects and chemically active adsorbing sites for high-performance adsorption. (4) Chemical adsorption was the primary way by which CM-HT adsorbed cationic dye, while physical adsorption caused by developed pore canal was secondary. The adsorption reaction occurred spontaneously.