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The exceptional biocompatibility of Ti/Ti bonding technology makes it highly significant for the sealing of implantable devices. However, achieving highly reliable Ti/Ti bonding at low temperatures is challenging due to the facile formation of a native oxide film, which hinders the diffusion of interfacial atoms. This paper develops a low-temperature Ti/Ti bonding process based on plasma activation, resulting in a remarkable bonding strength of 17.5 MPa at 300 °C, which can be used for Si–Si homogeneous and Si-glass heterogeneous integration. After optimizing the processes, the surface oxides of Ti can be partially reduced through Ar/H 2 plasma activation to form unsaturated chemical bonds, thereby overcoming the limitation of film thickness in Ti/Ti bonding. The results indicate that plasma activation can realize high strength Ti/Ti bonding in the film thickness range of 10–50 nm. It is worth noting that the Ti/Ti bonding area and strength remain stable after immersion experiments in DI water and normal saline for 7 days, which proves that Ti/Ti bonding has good corrosion resistance. In addition, the microcavity structures were prepared using photolithography and etching techniques. The Ti/Ti bonding technology enables direct bonding of microcavity structures with plate Ti, and an intact bonding interface near the microcavity was obtained. This low-temperature Ti/Ti bonding technology is suitable for the three-dimensional integration of various substrate materials, and its excellent corrosion resistance makes it promising for application in the sealing of BioMEMS. [ABSTRACT FROM AUTHOR]

Lost circulation is a pervasive problem in geothermal wells that can create prohibitive costs during drilling. The main issue with treatment is that the mechanism of plug formation is poorly understood. Here we applied two experimental approaches to characterize the clogging effectiveness of different materials. Fracture flow tests with different geometries were conducted with various individual materials and mixtures at relevant conditions. A high-temperature flow loop system was also developed to inject single- and mixed-material plugs into a gravel pack with a non-uniform geometry to compare with the fracture tests. The fracture tests revealed that single materials tended to form no plug or an unstable plug, while mixtures of materials were uniformly better at sealing fractures. Gravel pack tests at high temperatures show most of the materials are intact but degraded. The fibrous materials can create partial or unstable plugs in the gravel pack, but mixed-material plugs are far more effective at clogging. Both test types suggest that (1) mixed materials are more effective at blocking fluid flow and (2) fibrous materials seal fracture openings better, while granular materials seal inside fractures or pore throats better. Further research is needed to study the long-term stability of different plug configurations. [ABSTRACT FROM AUTHOR]

Driven by the increasing demand for 5G communication, GaN radio frequency (RF) device on Si technology has been flourishing attributable to the large size, low cost, and compatibility with complementary metal–oxide–semiconductor technology. However, a significant challenge is that a high-conductance parasitic channel forms at the interface between the III-N epitaxial layers and the Si substrate, leading to severe RF loss, which has been considerably impairing both the performance and advancement of RF GaN-on-Si technologies. Despite continuing controversies concerning the physical mechanisms engendering the parasitic channel, clarification is critically needed. Standing apart from traditional studies on RF loss in III-N epilayers grown on Si, this article comprehensively investigates the bonding interface of GaN thin film and Si(100) substrate realized via direct surface activated bonding and ion-cutting technologies. It was clearly determined that substantial diffusion of gallium (Ga) atoms into the Si substrate at the bonding interface occurred even at an annealing temperature as low as 350 °C. Subsequent high-temperature post-annealing at 800 °C intensified this diffusion, activating Ga atoms to form a p-type highly conductive parasitic channel. Simultaneously, it triggered Ga atoms aggregation and incited melt-back etching within the Si substrate at the interface. Contrasting with the conventional hetero-epitaxy, this study presents a compelling view based on the bonding technique. It conclusively elucidates the physical mechanisms of the formation of the primary source of RF loss—the p-type highly conductive parasitic channel. [ABSTRACT FROM AUTHOR]

The authors present the design, fabrication and testing of a W‐band monopulse antenna. This antenna consists of three main building blocks: an array with 48 × 48 slots, a tapered corporate‐feed network and a comparator. The comparator has four input ports to generate sum and difference patterns in orthogonal cardinal planes for monopulse operation. A novel octuple excitation is adopted for the corporate network to achieve a side lobe level lower than −20 dB for the sum patterns and simultaneously reduce drastically the manufacturing complexity. Diffusion bonding technology is used for fabrication. Twenty‐four etched copper sheets with a thickness of 0.2 mm are stacked to realise the prototype. The total size of the antenna is 40.76×40.76×1.51λ03 $40.76\times 40.76\times 1.51{\lambda }_{0}^{3}$, with λ0 being the wavelength at the centre frequency (94 GHz). The antenna presents an isolation better than 12 dB among the input ports in the 84–100 GHz band. The realised measured gain is 40.7 dBi at 94 GHz. The measured 3‐dB gain bandwidth is 17.4%. The difference patterns at 94.0 GHz present null depths of −24.0, −18.0, −17.5, and −17.4 dB, in the E‐, H‐, 45°‐, and 135°‐planes, respectively. [ABSTRACT FROM AUTHOR]

The side sealing technology is crucial for ensuring the quality and process stability in twin‐roll casting (TRC). Investigating the temperature and stress distribution in side dams under operational conditions is vital, especially in understanding the causes of side dam fractures. Optimal performance of side dam materials is achieved when the boron nitride (BN) matrix is fine and homogeneous, with zirconium dioxide (ZrO2) and silicon carbide (SiC) particles evenly dispersed throughout. The fracture of the side dam after casting is mainly caused by BN interlamellar tear. The coexistence of BN lamellar tearing and BN layer fracture leads to the fracture of the side dam during the casting process. Through finite element simulation, the effects of variables such as pouring temperature, preheating temperature, and side dam thickness on temperature and stress distribution were analyzed. The findings indicate that a preheating temperature range of 1200–1300 °C minimizes thermal stress in the side dam. Building on these findings, a composite structure for the side dam is developed. Both internal and external composite structures have shown significant effectiveness in reducing thermal stress. These results are pivotal in extending the service life of side dams and enhancing the stability of the TRC process. [ABSTRACT FROM AUTHOR]

The suitability of silanes H2N(C3H6)Si(OC2H5)3‐x(CH3)x (x=0, 1, 2) for the sealing of zeolite pores has been investigated. The sealing efficiency was evaluated by observing the exit kinetics of the fluorescent dye resorufin from the one‐dimensional main channels of zeolite L (ZL). The best results in terms of sealing quality were obtained with x=0, indicating the importance of ensuring maximum probability for siloxane bond formation and cross‐linking during the sealing process. The amino group thereby plays a crucial role in the positioning of the silane prior to covalent bond formation. Samples sealed with 3‐aminopropyltriethoxysilane (APTES) showed excellent stability against leaching in aqueous medium even under moderately alkaline conditions. Further evidence for the ability of APTES to efficiently seal the channels of ZL was obtained by nitrogen sorption measurements. [ABSTRACT FROM AUTHOR]

High-performance germanium (Ge) lateral PIN photodetector (PD) arrays for short wave infrared (SWIR) imaging based on Ge-on-insulator (GOI) platform was proposed and demonstrated. The high-quality GOI platform with top-Ge layer thickness of 1.25 μ m and threading dislocation density of less than 105 cm−2 was prepared by using bonding and smart-cut technology. P -type and N -type regions with centrosymmetric racetrack shapes were introduced to lower the sidewall electric field and suppress the surface leakage current of the PD. Benefiting from the high-quality of the GOI platform and the unique design of lateral active regions, a low dark current of 2 nA under −1 V with outstanding rectification ratio of 2.1 × 106 were obtained at room temperature. Through constructing a vertical resonant cavity by SiO2 passivation layer and the Si/SiO2 substrate, the responsivity at 1550 nm was enhanced to 0.46 A W−1 with a high specific detectivity of 3.09 × 1010cm·Hz1/2 ·W−1 under −1 V. Ultimately, SWIR imaging was demonstrated by a Ge lateral PIN PD line array with 1 × 8 pixels under zero bias at room temperature. The results indicate that the proposed lateral Ge PD structure holds great application potential in the field of SWIR imaging. [ABSTRACT FROM AUTHOR]

The emergence of new semiconductor devices puts forward higher requirements for packaging technology. Sintered silver technology has gradually developed into critical packaging technology in silicon carbide power module packaging due to its good heat dissipation performance and reliability. However, high sintering drive requirements, low sintering densification, and high thermal–mechanical stresses limit the application of sintered silver technology for large-area bonding. In this study, the high-pressure-assisted (≥10 MPa) large-area sintered-silver interconnection process between a substrate and baseplate was discussed. C-scan acoustic microscopy, warpage testing, and microanalysis were used to analyze the effects of drying methods, sintering pressure, and holding time on the sintered joints, and thermal fatigue reliability tests were conducted on large-area sintered silver joints. The results demonstrated that the quality of large-area sintered joints obtained via open-face convective drying is higher than that via close-face convective drying. Combining the performance of sintered joints and productivity, the recommended process condition is determined as follows: open-face convective drying, sintering temperature of 250 °C, sintering pressure of 15 MPa, and holding time of 5 min. Large-area sintered joints have outstanding reliability, with slight delamination of the sintered layer at the corners and no cracking after 1000 cycles of temperature cycling. [ABSTRACT FROM AUTHOR]

It is still a challenging problem to detect small defects for eddy current array probes, which requires the probes to possess excellent sensitivity, as well as high spatial resolution. This paper presents a novel high-resolution magnetic field imaging probe with two rows of tunneling magnetoresistance (TMR) array sensors. The bare die sensors are integrated on a printed circuit board by golden wire bonding technology. The two rows of sensors are placed staggered with each other. The data of the two arrays are merged into a matrix, in which way the image pixel pitch is increased to 0.25 mm. The probe employs a differential scheme to suppress the noise, so as to detect the weak signal of small defects. To highlight the weak defect indications, feature extraction and segmentation algorithms are developed. The experimental results confirm that the proposed method can inspect a small defect with dimensions 1 mm (length) × 0.1 mm (width) × 0.1 mm (depth) on a stainless-steel sample. [ABSTRACT FROM AUTHOR]

The development of 5G mobile communication imposes requirements of high frequency, miniaturization, and integration on surface acoustic wave devices. Compared with traditional piezoelectric bulk single crystal material, surface acoustic wave filters fabricated with silicon-based piezoelectric single crystal film materials exhibit advantages such as high frequency, low insertion loss, high temperature stability and so on, making silicon-based piezoelectric single crystal film material prime foundation material. Smart-Cut™ is the universal method for preparing silicon-based piezoelectric single crystal film materials, and bonding process is one of the most essential procedures. Bonding quality determines the quality of piezoelectric single crystal film and ultimately affects the performance of the devices. In this work, high-quality heterogeneous silicon-based LiTaO3 wafers with the bonding strength up to 1. 84 J/m² and bonding area over 99. 9% were achieved through optimizing low-temperature direct bonding process, which includes plasma activation, megasonic cleaning, pre-bonding, and thermal treatment. [ABSTRACT FROM AUTHOR]

Purpose: Au stud bump bonding technology is an effective means to realize heterogeneous integration of commercial chips in the 2.5D electronic packaging. The purpose of this paper is to study the long-term reliability of the Au stud bump treated by four different high temperature storage times (200°C for 0, 100, 200 and 300 h). Design/methodology/approach: The bonding strength and the fracture behavior are investigated by chip shear test. The experiment is further studied by microstructural characterization approaches such as scanning electron microscope, energy dispersive spectrometer and so on. Findings: It is recognized that there were mainly three typical fracture models during the chip shear test among all the Au stud bump samples treated by high temperature storage. For solder bump before aging, the fracture occurred at the interface between the Cu pad and the Au stud bump. As the aging time increased, the fracture mainly occurred inside the Au stud bump at 200°C for 100 and 200 h. When aging time increased to 300 h, it is found that the fracture transferred to the interface between the Au stud bump and the Al Pad. Originality/value: In addition, the bonding strength also changed with the high temperature storage time increasing. The bonding strength does not change linearly with the high temperature storage time increasing but decreases first and then increases. The investigation shows that the formation of the intermetallic compounds because of the reaction between the Au and Al atoms plays a key role on the bonding strength and fracture behavior variation. [ABSTRACT FROM AUTHOR]

The significance of bonding technology for modern vehicle structural materials is increasingly acknowledged, driven by the adoption of new materials to reduce weight. This is important not only for quality and economic reasons but to address environmental pollution, as well. Traditional joining methods like riveting, screwing, welding, and brazing, are often unsuitable or limited for modern materials. Soldering, an economical and almost waste-free technology, is becoming more widespread. Through optimization, it achieves a strong, durable bond. There is a potential to favourably alter interface properties, including using high energy density surface treatments. Research showed that the laser surface treatment of high-strength steel sheets could improve the mechanical properties of soldered joints. [ABSTRACT FROM AUTHOR]

Temperature and humidity coupling has a more significant effect on the failure properties of bonded joints than a single factor, and there is not enough research on this. In this paper, joints bonded with strong toughness structural adhesives are selected for the experimental analysis of joints aged for 240 h, 480 h, and 720 h at temperatures of 40 °C and 60 °C and a humidity of 95% and 100%. The sequential double Fick's model was used to fit the water absorption of the joints, and the comparison yielded that the water absorption of the adhesive was in accordance with Fick's law. The quasi-static tensile tests revealed that the reduction in mechanical properties of the joints was positively correlated with the moisture content in the environment, while the competing mechanisms of post-temperature curing and hydroplasticization resulted in a slight increase in the failure strength and energy uptake of the aged joints, which is in agreement with the experimental results of the Fourier infrared spectroscopy. A combination of macroscopic failure sections and scanning electron microscope (SEM) images yielded that the failure mode of the joints changed from cohesive failure to interfacial failure with increasing ageing time. In addition, reliability analyses for the fatigue testing of joints are expected to provide guidance for the life design of bonding technology in the vehicle service temperature range. [ABSTRACT FROM AUTHOR]

Finger seal is a new flexible dynamic sealing technology, and its heat transfer characteristics and seepage characteristics are one of the main research hotspots. In this paper, based on the fractal theory, a fractal model of the total thermal conductance of the finger seal considering the heat transfer effect of the contact gap of the rough surface is established, a fractal model of the effective gas permeability of the adjacent finger seals annulus considering the gas slip effect and the temperature change is established, and a finite element calculation method of the two-way thermo-mechanical coupling for the finger seal is proposed. The results show that the solid-phase thermal conductance decreases with the increase of the scale coefficient. When the axial pressure difference is greater than 0.4 MPa, the rotor speed is greater than 11,000 r/min, the radial displacement excitation is [0.03 mm, 0.09 mm], and the temperature is less than 600 K, the gas-phase thermal conductance between the finger seal and the rotor shows an increasing trend. The gas-phase thermal conductance of the finger seal and the rotor is always the main position under different working conditions. Under different fractal dimensions, the solid-phase thermal conductance gradually occupies the dominant position. Temperature has a certain effect on the effective gas permeability, and fractal dimension, scale coefficient, and axial pressure difference have less effect on the effective gas permeability. At an axial pressure difference of 0.08 MPa, the numerical calculation results of the two-way thermo-mechanical coupling calculation method for finger seal are closer to the experimental results, with a maximum error rate of 1.96%. The above results further improve the theoretical research system of the heat transfer characteristics of the finger seal. [ABSTRACT FROM AUTHOR]

[Display omitted] In this research, new injectable and in situ photocurable elastomeric nanohybrids have been fabricated from polyalphaolefin (PAO) resins and halloysite nanofiller. In this regard, the co-oligomerization of long α-olefin monomers (C6, C8 and C10) with alkenol counterparts was carried out via a simple cationic route to provide OH-functionalized PAOs. The newly formed PAO type copolymer resins as well as halloysite nanoclay were then equipped with photocurable C C bonds containing an acrylate moiety. After the characterization of the final chemical substances and also of the intermediate structures, experimentally and computationally by means of Density Functional Theory (DFT) calculations, the neat treated PAO and PAO/halloysite nanohybrids were subjected to a curing process by visible light irradiation (λ ∼ 475 nm, blue light). The crosslinking efficiency of the neat resins and the formed nanohybrid was evaluated using shrinkage strain–time curves and equilibrium swelling method. The suggested nanohybrid is not only biocompatible (96 % in the MTT assay), and hydrophilic (with a water contact angle of 61°), but also exhibits an easy, fast and robust curing process with great potential for coating and sealing technologies for medical devices. [ABSTRACT FROM AUTHOR]

We demonstrate the temperature distribution, optical and laser performances of a YAP/Tm:YAP/YAP composite crystal fabricated by thermal bonding technology. The thermal distribution simulations show that the bonded crystal possesses a higher thermal dissipation efficiency than that of the unbonded one. The wavefront distortion of the bonded YAP/Tm:YAP crystal is close to the unbonded Tm:YAP, indicating a high bonding quality. The optical transmission spectra and absorption loss suggest that the bonding region is a uniform transition and almost without scattering interface. Moreover, compared with the un-bonded Tm:YAP crystal, a maximum average output power of 41.2 W and slope efficiency of 49.5% are achieved on the bonded crystal, which are increased by 28.4% and 21.0%, respectively. Therefore, the 1.94 μm laser performance can be effectively improved by combining pure YAP crystals on the Tm:YAP crystal as end-caps. [ABSTRACT FROM AUTHOR]

Diffusion bonding technology is widely used in the connection of precision components, yet accurately and reliably detecting contact-type defects on the bond interface still remains a significant problem. Nonlinear ultrasonic methods have been proven to be sensitive to contact-type defects; however, the use of continuous wave or tone burst wave excitation limits its wider application. In this paper, dual-probe nonlinear ultrasonic testing with pulse wave excitation is proposed to detect contact-type defects in diffusion-bonded joints. A titanium alloy diffusion-bonded specimen with artificial defects was fabricated, and the corresponding detection device was designed based on the existing ultrasonic C-scan testing system. A C-scan imaging program based on nonlinear parameters was developed by extracting the fundamental and second harmonic waves of the reflection echo on the bond interface. The results demonstrated that the proposed detection scheme can obtain the nonlinear parameters of diffusion-bonded interfaces, and the nonlinear ultrasonic C-scan image of the bond interface is also obtained. The nonlinear parameter in the contact-type defects areas calculated from the bond interface echo is about 10 times (20 dB) higher than that in macro defects areas, whose gap is about 10 μm. The results indicate that the nonlinear ultrasonic methods seem to be more sensitive to contact-type defects and have a great potential to complement the insufficient detection capability of linear ultrasound for diffusion-bonded joints. [ABSTRACT FROM AUTHOR]

This article discusses the importance of sealing technology in preventing pump failure and the catastrophic consequences that can result from seal problems. Traditionally, pumps were sealed with gland packing, but this method requires regular maintenance and large amounts of water to prevent overheating. Mechanical seals, on the other hand, offer greater efficiency and lower leakage, resulting in savings on downtime and maintenance. The article also mentions the use of seal support systems and flush plans to prevent damage and leakage. Additionally, it explores the development of magnetic drive pumps as a solution to eliminate the risk of leaks, although these pumps have limitations such as limited solids handling and sensitivity to extreme operating conditions. [Extracted from the article]

People wear clothes for warmth, survival and necessity in modern life, but in the modern era, eco-friendliness, shortened production times, design and intelligence also matter. To determine the relationship between data series and verify the proximity of each data series, a gray relational analysis, or GRA, is applied to textiles, where seamless bonding technology enhances the bond between components. In this study, a polyurethane prepolymer, 2-hydroxyethyl acrylate (2-HEA) as an end-capping agent and n-octyl acrylate (ODA) as a photoinitiator were used to synthesize a dual-curing polyurethane hot-melt adhesive. Taguchi quality engineering and a gray relational analysis were used to discuss the influence of different mole ratios of NCO:OH and the effect of the molar ratio of the addition of octyl decyl acrylate on the mechanical strength. The Fourier transform infrared spectroscopy (FTIR) results showed the termination of the prepolymer's polymerization reaction and the C=O peak intensity at 1730 cm−1, indicating efficient bonding to the main chain. Advanced Polymer Chromatography (APC) was used to investigate the high-molecular-weight (20,000–30,000) polyurethane polymer bonded with octyl decyl acrylate to achieve a photothermosetting effect. The thermogravimetric analysis (TGA) results showed that the thermal decomposition temperature of the polyurethane hot-melt adhesive also increased, and they showed the highest pyrolysis temperature (349.89 °C) for the polyhydric alcohols. Furthermore, high peel strength (1.68 kg/cm) and shear strength (34.94 kg/cm2) values were detected with the dual-cure photothermosetting polyurethane hot-melt adhesive. The signal-to-noise ratio was also used to generate the gray relational degree. It was observed that the best parameter ratio of NCO:OH was 4:1 with five moles of monomer. The Taguchi quality engineering method was used to find the parameters of single-quality optimization, and then the gray relation calculation was used to obtain the parameter combination of multi-quality optimization for thermosetting the polyurethane hot-melt adhesive. The study aims to meet the requirements of seamless bonding in textile factories and optimize experimental parameter design by setting target values that can effectively increase production speed and reduce processing time and costs as well. [ABSTRACT FROM AUTHOR]

Compressive stress in glass‐to‐metal seals is crucial to ensure sealing quality and service reliability. Photoluminescence spectroscopy (PS), which relies on the piezospectroscopic effect of Cr‐doped α‐Al2O3, shows promise for stress detection owing to its rapid detection, non‐destruction, and high resolution. The premise of the PS technique is to fill a glass matrix with alumina particles and detect signals from the alumina. In this study, the interaction between alumina particles and the glass matrix was analyzed to calibrate the measured stresses and investigate the stress state in the glass. Test results for glass‐to‐metal seals are believed to consist of simultaneous internal residual stress and external applied stress. The internal residual stress is formed due to the coefficient of thermal expansion mismatch between glass and alumina and is assumed to transfer by radial compression. In the experiment, it was detected by the PS technique and verified by X‐ray diffraction using an unstressed sample without metal housing. The external applied stress is formed due to metal housing compaction and possibly transferred by the shear effect. The stress distribution within the pre‐stressed sample containing metal housing was also measured by the PS technique. Then, calibrations were conducted on the measured stresses based on the deduced stress transfer relationships. Finally, finite element models were established to simulate the internal residual stress and external applied stress respectively to prove the validity of the calibration method, and mutually anastomotic results were obtained within the target margin of error. [ABSTRACT FROM AUTHOR]

Numerous scientific satellites require micronewton thrusters for compensating environmental disturbances. The mass flow control proportional valve plays a crucial role in precisely regulating the thrust. To meet the high resolution and wide range requirements of the thrusters, this paper introduces a novel proportional valve with two sets of independently controllable piezoelectric stack. One set of the piezo-stack is used to compensate the stroke loss of the valve core, mainly caused by the deformation of the valve seat. The valve sealing mechanism is carefully analyzed to reduce the stroke loss. Another set of the stack works as the primary actuator, enabling the high mass flow control resolution. Two sets of independently controlled piezoelectric stacks not only expand the range and improve the range ratio but also provide redundancy and enhance reliability. This means that the actuator can still operate at lower ranges even if one piezo-stack is damaged. The piezo-actuators are assembled using U-shaped connectors, creating a compact and space-efficient overall design. Experimental tests have been conducted to verify the performance of the valve, which demonstrated a mass flow range of 0–675 μg/s with a resolution better than 0.1 μg/s and a flow noise below 0.1 μg/s/Hz1/2 at 0.1 mHz–1 Hz. [ABSTRACT FROM AUTHOR]

Due to increasing legal requirements to reduce emissions from vehicle fleets, vehicle manufacturers are focusing on the electrification of the powertrain. In entirely electrically driven vehicles, the energy is stored in traction batteries integrated below the passenger cell between the axles and thus located in the vehicle's wet area. Therefore, high requirements apply to the protection of the sensitive cells against mechanical stress as well as against moisture penetration. In addition, one of the main requirements for the connections of the battery housing is to ensure gas tightness over the entire service life. Adhesive bonding technology as a planar joining process offers the potential to produce functionally tight connections. However, there is a lack of reliable test methods for validating the long-term tightness of structural adhesive joints under mechanical and corrosive loads. For this reason, the paper deals with developing a test concept with laboratory-scale test specimens for leak testing under mechanical loading. Various leakage test methods investigate the leakage rate of structurally bonded joints. An analysis of the leakage rate under superimposed cyclic mechanical shear tensile loading follows this. The test method is validated on a specially developed sample battery housing on a laboratory scale. [ABSTRACT FROM AUTHOR]

Fireproof sealing technology is widely used in industrial, commercial, and other public buildings, so the performance of fireproof sealing materials in high temperatures or fire environments must be taken into account as an important factor. Fireproof sealant is considered to be a highly effective adhesive for sealing and fireproofing purposes. To explore its thermal decomposition mechanism and estimate its pyrolysis behaviors, a series of thermogravimetric experiments from 10 K/min to 60 K/min coupled with Fourier transform infrared spectroscopy analysis technology were performed. The results indicated that the thermal decomposition of the fireproof sealant could be divided into three reactions: the degradation of ammonium polyphosphate, melamine, and acrylic acid. In addition, the pyrolysis behavior of the fireproof sealant was compared under two kinds of atmosphere (nitrogen and air). Furthermore, the initial kinetic parameters in the nitrogen atmosphere were calculated based on model-free methods including the Friedman, KAS, and Starink methods. The average activation energy of three reactions obtained by the three methods was 108.32 kJ/mol, 200.46 kJ/mol, and 177.10 kJ/mol, respectively, while these obtained parameters were hard to regenerate, the thermogravimetric curves were accurately based on the established pyrolysis reaction scheme, with the existence of clear deviations. Therefore, a global heuristic optimization algorithm, Shuffled Complex Evolution (SCE), was selected to optimize 14 parameters (including activation energies and the pre-exponential factors) and the optimized pyrolysis results agreed well with the experimental data, even at the extra heating rate, with the correlation coefficient for the mass loss and mass loss rate being reaching up to 0.9943 and 0.9019, respectively. The study indicated that the SCE algorithm showed an appropriate potential to estimate the pyrolysis behavior of an unknown thermogravimetric experiment group. [ABSTRACT FROM AUTHOR]

This work deals with the development and investigation of self-reinforced polylactic acid (SRPLA) composites manufactured from two different nonwoven preforms with two different bicomponent filament architectures. The SRPLA nonwovens prepared via spun bonding technology have two different bicomponent filament architectures, that is, core-sheath, and islands in the sea. For the core-sheath filaments, spunbound nonwovens are compared with the dry-laid SRPLA nonwovens. The SRPLA nonwoven preforms are compression molded at three different mold temperatures to fabricate composite plates. The optimum mold temperature is identified based on the flexural properties and residual void volume fraction of composites. The flexural modulus and strength are about 38% and 50% higher than those of the pure PolyLactic Acid (PLA) matrix, respectively. The influence of bicomponent filament architecture on the mechanical performance of composites is negligible, whereas the nonwoven architecture leads to significant differences both in the residual void volume fraction and in the mechanical properties of composites. Finally, the mechanical properties of the SRPLA composites are compared with those of the conventional composites to prove their applicability to semi-structural parts. [ABSTRACT FROM AUTHOR]

This article presents the main methods of implementing degassing control systems, which allow for a radical reduction in the likelihood of accidents and achieving the most effective production results. The article discusses measures to prevent explosive gas concentrations during degassing operations, proposes optimal diameters and distances between degassing wells. Additionally, parameters influencing the volume of pumped methane are identified. A technology for sealing underground wells to maintain methane gas concentration is proposed. A modern mobile degassing unit is presented for methane extraction followed by utilization for electricity generation. [ABSTRACT FROM AUTHOR]

Purpose: Wafer bonding is a key process for 3 D advanced packaging of integrated circuits. It requires very high accuracy for the wafer alignment. To solve the problems of large movement stroke, position calibration error and low production efficiency in optical alignment, this paper aims to propose a new wafer magnetic alignment technology (MAT) which is based on tunnel magneto resistance effect. MAT can realize micro distance alignment and reduces the design and manufacturing difficulty of wafer bonding equipment. Design/methodology/approach: The current methods and existing problems of wafer optical alignment are introduced, and the mechanism and realization process of wafer magnetic alignment are proposed. Micro magnetic column (MMC) marks are designed on the wafer by the semiconductor manufacturing process. The mathematical model of the space magnetic field of the MMC is established, and the magnetic field distribution of the MMC alignment is numerically simulated and visualized. The relationship between the alignment accuracy and the MMC diameter, MMC remanence, MMC thickness and sensor measurement height was studied. Findings: The simulation analysis shows that the overlapping double MMCs can align the wafer with accuracy within 1 µm and can control the bonding distance within the micrometer range to improve the alignment efficiency. Originality/value: Magnetic alignment technology provides a new idea for wafer bonding alignment, which is expected to improve the accuracy and efficiency of wafer bonding. [ABSTRACT FROM AUTHOR]

In this article, a resolution of 15 × 30 blue flip-chip micro-LED array with a pixel size of 20 × 35 μm2 was fabricated. The micro-LED array was hybridized with the silicon backplane via flip-chip bonding technology and liftoff process. The Au/In/Au multilayers could provide lower electrical resistivity and reduce cracks and voids at the film interface, leading to a micro-LED display that had uniform brightness and high reliability. The blue micro-LED display exhibits excellent optical and electrical characteristics, including a low turn-on voltage of 2.8 V and a brightness reach of 1.78 × 107 cd/m2 (nits) at 5 V. Additionally, there appears in the emission spectrum at a voltage of 3 V a blue shift of a peak wavelength from 455.51 to 453.96 nm. Further, the average shear strength of the micro-LED bonded by Au/In/Au multilayers increased to 2.24 g. The presented method has tremendous potential in high resolution micro-LED displays for augmented and virtual reality devices. [ABSTRACT FROM AUTHOR]

In order to ensure the reliability of drilling tractor in the downhole operation, three high‐temperature and high‐pressure sealing mechanisms are designed in this paper to balance the pressure difference between the inside and outside of the drilling tractor, namely the triangular, the U‐shaped and the right‐angle combined sealing structure. In this paper, three models of combined sealing structures are established, the contact stress of different contact surfaces of the three combined sealing structures is analysed by simulation method, and their sealing performance is studied and compared. By comprehensively comparing the effects of pre‐compression ratio, working medium pressure and reciprocating motion on the sealing effect of the three combined sealing structures, the optimal combined sealing structure of the drilling tractor is selected as the U‐shaped combined sealing structure. The research results of this paper can provide reference and theoretical basis for the design and selection of the combined sealing structure. [ABSTRACT FROM AUTHOR]

In this study, to solve the problem of reduced efficiency of NO degradation due to the agglomeration effect of TiO2 nanoparticles, nano- TiO2 was converted to a 3D-ordered microporous [three-dimensional ordered macroporous (3DOM)] structure and combined with fog seal technology, which is expected to improve the degradation performance of nano- TiO2 on NO gas in automobile exhaust. We optimized the preparation process parameters of 3D-ordered macroporous (3DOM) TiO2 and developed and designed an experimental device for exhaust-gas catalytic degradation. We further tested and analyzed the effects of emulsified asphalt type, photocatalyst type, doping amount, and 3DOM TiO2 pore size on the photocatalytic performance of 3DOM TiO2 fog seal material. The effects of 3DOM TiO2 fog seal material on road antiskid performance were evaluated herein. The results show that the optimal coating volume of the PS microsphere solution is 0.14−0.16 mL/cm2. The optimal filling time of the precursor solution is 20 min for the preparation of 3DOM TiO2 materials by the sandwich method. The degradation efficiency of 3DOM TiO2 fog seal material for the optimal pore size was 17.0%, 15.0%, and 25.1% higher than that of nano- TiO2 , respectively. The 3D-ordered pore structure reduces the agglomeration effect of nano- TiO2 Thus, the degradation efficiency is improved. With the increase of 3DOM TiO2 doping, the degradation efficiency of fog seal materials gradually increased. However, the increment of degradation efficiency decreased. The appropriate increase of 3DOM TiO2 pore size is beneficial to the catalytic effect of light. If the pore size is significantly large, the emulsified asphalt will block the pore space and reduce the contact area between 3DOM TiO2 and exhaust gas. The optimal pore size is 300 nm. The type of emulsified asphalt on 3DOM TiO2 fog seal material degradation effect is not significant. The antislip performance of the pavement coated with 3DOM TiO2 fog seal materials can meet the requirements of specifications. The photocatalyst doping amount, type, and different 3DOM TiO2 pore sizes do not significantly affect the antislip performance of the fog seal. The novel 3DOM TiO2 photocatalytic pavement material proposed in this study is of positive significance for the reduction of automobile exhaust pollution. [ABSTRACT FROM AUTHOR]

Fluorosilicone rubber, essential in automotive and aerospace owing to its excellent chemical resistance, plays a pivotal role in sealing technology, addressing the industry's evolving demands. This study explores the preparation and properties of fibrillated cellulose-reinforced fluorosilicone rubber composites to enhance their stiffness and oil resistance. Fibrillated cellulose sourced as a wet cake and subjected to processing and modification is incorporated into a fluorosilicone rubber matrix. The resulting composites are analysed by tensile and compression tests, along with compressive stress-relaxation testing in air and in an oil-immersed environment. The findings demonstrate significant improvements in the mechanical properties, including an increased Young's modulus and elongation at break, whereas the tensile strength remained uncompromised throughout the testing procedures. Morphological analysis of the fracture surfaces revealed a remarkable interfacial affinity between the fibrillated cellulose and rubber matrix, which was attributed in part to the modified fatty acids and inorganic nanoparticles. The presence of fibrillated cellulose enhanced the stress-relaxation characteristics under oil-immersion conditions. These results contribute to the domain of advanced elastomer materials, with potential for applications requiring enhanced mechanical properties and superior oil resistance. [ABSTRACT FROM AUTHOR]

Despite numerous research studies inspecting the safety benefits of centreline and shoulder rumble strips (RS) on pavements, there has been limited exploration into the impact on pavement durability due to the installation of RS. The RS milling process creates micro-cracks in the pavement structure that could propagate to macro cracks over time with freeze and thaw, moisture damage, and traffic loading, thereby decreasing the lifespan of the pavements. The primary objective of this study was to develop testing procedures for RS samples as well as analysis methods to determine the impact of potential controlling factors such as permeability and resulting moisture damage; freeze–thaw; the presence of microcracks; surface layer sealants (chip seal); RS size, depth, type, and RS location in relation to the longitudinal construction joint. The flexural beam fatigue test suggests that sinusoidal rumble strips had 38% increased fatigue cracking resistance. Moreover, the sinusoidal rumble strip resulted in 41% improved cracking and structural performance in the Hamburg Wheel Tracking Test (HWTT) tests. Also, the rutting performance of sinusoidal rumble strips was similar to the control section without rumble strips. In addition, 0% moisture infiltration was observed in sinusoidal rumble strip specimens. [ABSTRACT FROM AUTHOR]

Sand fog seal is a preventive maintenance material to repair the early distresses in asphalt pavements. The objective of this study is to develop an optimal design guideline for sand fog seal to balance the demand for rapid traffic opening with the need to keep good road performance. Based on the response surface methodology (RSM) and I-optimal methodology, the effects of the components' ratios (including water, filler, and sand) and their interactions on the curing process and surface function of sand fog seal were investigated. The test results showed that water can regulate the fluidity and dispersibility of the fresh sand fog seal mortar, but will prolong the curing process. The modified sodium bentonite, as the filler, can shorten the full curing time of sand fog seal due to its good moisture absorption and permeability. Moreover, the interaction of water and filler significantly affected the bonding strength, and the recommended water-filler ratio was 1.5. The sand content should be controlled to less than 25% to ensure good adhesion and abrasion resistance. Finally, a formulation design guideline for sand fog seal based on desirability optimization methodology (DOM) was proposed, with recommended formulation of 21.8% water, 30% filler, and 25% sand. [ABSTRACT FROM AUTHOR]

To meet the requirements of alumina ceramics in delicate electronics, there is an urgent need for a low-temperature bonding technology that can realize a good combination of alumina and metal. In this work, alumina ceramics and nickel metals were successfully connected at a low temperature (25–150 °C) by Al-Ni self-propagating nanofoil as a heat source. The interface microstructure and element distributions of the solder joints from cross-section and fracture surface were investigated. In addition, the solder joint formation process was simulated by finite element analysis and molecular dynamics. These results showed that their shear strengths could be continuously improved with the growing temperature, which were 17.4 MPa (room temperature, 25 °C), 19.5 MPa (50 °C), 22.9 MPa (100 °C) and 25.69 MPa (150 °C). The Al 2 O 3 /Al-Ni nanofoil/Ni solder joints were prone to crack at the corner and boundary at Al 2 O 3 /solder interfaces due to the stress concentration. Moreover, the increase in ambient temperature not only raises the melting time and transient temperature during the self-propagating reaction, but also improves the interdiffusion of Ni and Sn atoms at the Ni/Sn interfaces. [ABSTRACT FROM AUTHOR]

A kind of full-function two-sided optical bench interferometer (OBI) is designed to meet the practical requirements of the Taiji Program for space gravitational wave detection. The main optical paths are arranged on the A-side for transmission and interference, and other optical paths and electronic devices are placed on the B-side. According to the design scheme, we successfully constructed two OBIs by using hydrogen–oxygen catalytic stress-free bonding technology. When the OBI is installed and adjusted, the position and Angle error of the interference beam are controlled within 30 μm and 50 μrad through the self-designed precision mechanical clamping mechanism and beam position measuring device. The built OBI was placed on the vibration isolation platform in the vacuum tank for the stability test. The test results show that the noise of the OBI is less than 10 p m / √ H z in the frequency band of 0.1 Hz to 1 Hz, which meets the noise budget requirements of the Taiji Pathfinder in the middle- and high-frequency band. [ABSTRACT FROM AUTHOR]

Wafer-level direct bonding technology is a key process for the production of backside illuminated (BSI) CMOS image sensor (CIS). Usually, constant-depth mode scanning acoustic microscope (C-SAM) 300mm wafer images are acquired and defect size distribution is provided to monitor defects that degrade bonding yield. This acquisition technique is used as it is nondestructive and is able to capture the full wafer. Current solutions are not providing information detailed enough to identify the root cause of this degradation. A consequence is that most measurements and classification is currently done manually which take time and have reproducibility issues. In this paper, we propose a rule-based method for the classification of the defects and automatic segmentation of the defects to extract precise measurements depending on the type of defect. The classes of defects are precisely defined based on their origin in the process. All these information will allow to reduce the time to analyze the images and improve the precision and consistency of the analysis. These results will allow to identify more precisely the defects thus the causes of yield degradation during bonding process. [ABSTRACT FROM AUTHOR]

The paper presents an analytical model for the design of a composite membrane circular capacitive micromachined ultrasonic transducers (cMUT) cell. The analytical model harnesses composite membrane layer cMUT cell based on the mass-spring-damper system. The effects of damping due to the surrounding medium and acoustic impedance of self-radiation as well as identical neighbouring cells cluster are also modelled for dynamic analysis of unit cMUT cell. The validation of analytically obtained results is performed through FEM simulations using MEMSCAD tool CoventorWare®. The analytically obtained results show good agreement with the FEM simulation results. The designed structure is based on the wafer bonding technology, which is well established at the authors' laboratory. It is a low temperature anodic bonding process without through silicon via/through glass via (TSV/TGV) technique requirement (Aditi et al. in IEEE 24th Electronics Packaging Technology Conference (EPTC), 2022). Composite membrane circular cMUT cell is designed and validated for air-coupled application; moreover, the model developed is also applicable to other fluids as well. [ABSTRACT FROM AUTHOR]

Despite numerous research studies inspecting the safety benefits of centreline and shoulder rumble strips (RS) on pavements, there has been limited exploration into the impact on pavement durability due to the installation of RS. The RS milling process creates micro-cracks in the pavement structure that could propagate to macro cracks over time with freeze and thaw, moisture damage, and traffic loading, thereby decreasing the lifespan of the pavements. The primary objective of this study was to develop testing procedures for RS samples as well as analysis methods to determine the impact of potential controlling factors such as permeability and resulting moisture damage; freeze–thaw; the presence of microcracks; surface layer sealants (chip seal); RS size, depth, type, and RS location in relation to the longitudinal construction joint. The flexural beam fatigue test suggests that sinusoidal rumble strips had 38% increased fatigue cracking resistance. Moreover, the sinusoidal rumble strip resulted in 41% improved cracking and structural performance in the Hamburg Wheel Tracking Test (HWTT) tests. Also, the rutting performance of sinusoidal rumble strips was similar to the control section without rumble strips. In addition, 0% moisture infiltration was observed in sinusoidal rumble strip specimens. [ABSTRACT FROM AUTHOR]

Sand fog seal is a preventive maintenance material to repair the early distresses in asphalt pavements. The objective of this study is to develop an optimal design guideline for sand fog seal to balance the demand for rapid traffic opening with the need to keep good road performance. Based on the response surface methodology (RSM) and I-optimal methodology, the effects of the components' ratios (including water, filler, and sand) and their interactions on the curing process and surface function of sand fog seal were investigated. The test results showed that water can regulate the fluidity and dispersibility of the fresh sand fog seal mortar, but will prolong the curing process. The modified sodium bentonite, as the filler, can shorten the full curing time of sand fog seal due to its good moisture absorption and permeability. Moreover, the interaction of water and filler significantly affected the bonding strength, and the recommended water-filler ratio was 1.5. The sand content should be controlled to less than 25% to ensure good adhesion and abrasion resistance. Finally, a formulation design guideline for sand fog seal based on desirability optimization methodology (DOM) was proposed, with recommended formulation of 21.8% water, 30% filler, and 25% sand. [ABSTRACT FROM AUTHOR]

A brush seal is a type of contact sealing technology that generates a great amount of heat during operations. The heat can affect the seal's performance and lifespan. To study the brush seals' temperature distribution, a new model considering the anisotropic heat transfer effect is established in this paper. The friction heat effect at the bristles' tip is studied. The temperature field and leakage rates are obtained by using combined finite element analysis (FEA)-computational fluid dynamics (CFD) analysis and the anisotropic heat transfer theory. The influence of operating and structural parameters on the temperature field and the sealing properties of the brush seal are investigated. It is shown that the value of the rotation rate and the interference can cause the temperature of the brush seal to increase. The pressure difference enhances the convective heat transfer from the brush seals. While the temperature at the bristles' tip increases, the radial average temperature of the bristles decreases significantly. In the case of a small pressure difference, the fence's height can increase the windward area, leading to stiff bristles and resulting in a temperature increase at the bristles' tip; however, the effective flow area increases, resulting in an acceleration of the radial temperature's decrease. To summarize, the porous medium model of anisotropic heat transfer provides a new method for studying brush seals, and it can reflect the temperature distribution and leakage performance of brush seals. [ABSTRACT FROM AUTHOR]

Hybrid bonding enables the commercialization of ultra‐fine pitch high‐density 3D packages. Cu/SiO2 hybrid bonding is the standard packing interface recently introduced in the industry. Herein, the Cu/polymer hybrid bonding interface beyond Cu/SiO2 is proposed in order to have high compatibility for additional processes in the future. Ideally, polymers can provide excellent bonding strength and low permittivity, enabling high‐speed signal transmission with high reliability. To realize it, optimum polymer and additives selection and polymer bonding processing development are needed to get the desired packaging interface. Therefore, detailed materials and processing challenges are discussed to realize the successful Cu/polymer hybrid bonding. Then, the authors' preliminary results are suggested to supplement the feasibility of the emerging bonding technology. [ABSTRACT FROM AUTHOR]

The work considers principles for the design of photocurable repair-purpose materials, the main advantage of which is the possibility of rapid formation of high-strength, adhesive, jointless coatings and coverings for sealing, insulation, protection, and repair of surfaces of various natures, such as metal, concrete, and plastic. The application of such materials is validated in the practice of pipeline repair (including oil pipelines and mud lines). [ABSTRACT FROM AUTHOR]

Due to the particularity of mine spaces and the limitations of underground ventilation, the gas in disaster areas changes greatly after a fire occurs. Rapid sealing technology is beneficial for preventing the development of fires and gas explosions by controlling oxygen. Using the Fuzzy Analytic Hierarchy Process (FAHP), in this research, we analyzed the three most effective rapid sealing processes, conducted experimental research on the three sealing processes, and developed a further optimized design. At the same time, according to different stages of blasting damage, the change characteristics and migration laws of explosive hazardous gases in a disaster area were analyzed using fluent numerical simulation. Additionally, the ability of the three optimal processes to create an airtight area was measured in this research. The applicable scenarios and scope of the three technologies were found, which provides a wider range of application scenarios and more diverse options for rapid airtightness during catastrophic periods, mine fire prevention, and explosion protection. [ABSTRACT FROM AUTHOR]

Additive manufacturing (AM) methods are finding more and more applications in the manufacturing of machine parts. One consequence of this method is that generated surface qualities are typically lower than in other processes. This becomes especially relevant when the surface quality is critical for the mechanical function: This is the case in dynamic sealing technologies, for example, in seals between a moving rod and a hydraulic cylinder. Between the seal lip and the polished rod, a thin lubrication film is established with the goal of minimal leakage. How well this goal is reached depends on the surface quality of the seal. For spare part production of seals, we investigate AM methods, which have a surface defined by layers from fused filament fabrication (FFF). We apply a coupled model for fluid–structure interaction of the elastic seal and the film flow. This model provides information on flow field and pressure distribution. Results change when the 'ideal' seal lip is replaced by the seal lip geometry from FFF. The continuous loss of solid body contact is replaced by a stepwise loss of contact for the FFF surface. [ABSTRACT FROM AUTHOR]

With the increasing scale of the automotive industry, the mixed application of multiple materials and bonding technology have become indispensable means to achieve lightweighting. In this paper, accelerated aging experiment and tensile test were developed to study the effect of loading rate (1 mm/min–100 mm/min) on the failure of BFRP-Aluminum alloy single lap joint after hygrothermal aging (0 days–28 days). The aging mechanism of the adhesive and BFRP in the hygrothermal environment was also analyzed by Fourier transform infrared and differential scanning calorimetry. The test results showed that the joint failure strength varied with the hygrothermal aging time and loading rate, with the former showing a negative correlation and the latter a positive correlation. Combined with the joint failure surface, it was found that the joint strength decrease was mainly caused by the hydrolysis reaction of the adhesive and the interfacial failure of the joint. A regression model was developed to characterize the failure strength of the joints under different loading rates in the hygrothermal environment, and it was concluded that the aging time was more significant than the loading rate on the strength of the joints. [ABSTRACT FROM AUTHOR]

Laser surfacing repair technology for sealing welds is widely used in metal repair. Due to welding technology and usage scenarios, process defects on the metal surface are inevitable. Therefore, ultrasonic surface wave technology is used to analyze the surface defects of metal materials. Principal Component Analysis (PCA) is used to extract the main defect signals on the metal surface, and synthetic aperture focusing technology is used to reduce imaging errors. Considering the lack of PCA in imaging defects, wavelet domain hidden Markov models (WHMM) are combined to optimize the signal, thereby improving the inspection effect of metal defects. In the test results of the relationship between the propagation distance of 316 L steel and the defect echo signal, the echo signal gradually fitted as the propagation distance increased. When the propagation distance was greater than 10 mm, the image acquisition defect signal had significant noise points. Various techniques were used to process the original echo signals of metal surface defects. The improved PCA-WHMM algorithm had significant advantages with the SNR value of the defect image increased by 13.65 % compared to PCA-WHMM. At the same time, the surface repair effects of laser surfacing 316 L metal before and after optimization were compared. The hardness, toughness, and corrosion resistance of the optimized metal were significantly improved. The proposed technological innovation combines traditional laser surfacing repair with deep learning fault diagnosis, which not only greatly improves the efficiency of fault diagnosis, but also proves that this research can effectively avoid common focus issues of laser surfacing repair technology, providing important technical reference for the application of ultrasonic technology in metal defect detection. [ABSTRACT FROM AUTHOR]

Advanced packaging technology has become more and more important in the semiconductor industry because of the benefits of higher I/O density compared to conventional soldering technology. In advanced packaging technology, copper–copper (Cu-Cu) bonding has become the preferred choice due to its excellent electrical and thermal properties. However, one of the major challenges of Cu-Cu bonding is the high thermal budget of the bonding process caused by Cu oxidation, which can result in wafer warpage and other back-end-of-line process issues in some cases. Thus, for specific applications, reducing the thermal budget and preventing Cu oxidation are important considerations in low-temperature hybrid bonding processes. This paper first reviews the advancements in low-temperature Cu-based bonding technologies for advanced packaging. Various low-temperature Cu-Cu bonding techniques such as surface pretreatment, surface activation, structure modification, and orientation control have been proposed and investigated. To overcome coplanarity issues of Cu pillars and insufficient gaps for filling, low-temperature Cu-Cu bonding used, but it is still challenging in fine-pitch applications. Therefore, low-temperature Cu/SiO2, Cu/SiCN, and Cu/polymer hybrid bonding have been developed for advanced packaging applications. Furthermore, we present a novel hybrid bonding scheme for metal/polymer interfaces that achieves good flatness and an excellent bonding interface without the need for the chemical mechanical polishing (CMP) process. [ABSTRACT FROM AUTHOR]

One of the improving application areas of geopolymers is their using as an alternative assembly of different materials. This study presents the results of an experimental study on making aluminum panels by using geopolymer as an alternative adhesive to replace typical organic polymers. We prepared a metakaolinbased geopolymer having a composition of Na2O•Al2O3•4SiO2•11H2O. Aluminum alloys (Al 3003), 7 and 15 mm in high and (Al 5005) were used as core and plate materials of the panels, respectively and their surface was cleaned for adhesion bonding according to ASTM D 2651-01. Shear test samples were cut and then geopolymer resin was applied to the cleaned surface of aluminum core and plate by hand. Following hydrothermal sealing, the samples were then cured at 50 °C in an open-air furnace for 36 h under clamp fixed. Aluminum-geopolymer interface and geopolymer bond were examined by SEM-EDS in terms of chemical composition. Ambient temperature mechanical test results revealed that the aluminumgeopolymer bonds have mean shear strength of (1.406 ±1.01 MPa) and (0.133 ±0.07 MPa) for 7 and 15 mm samples, respectively. [ABSTRACT FROM AUTHOR]

The research and development of dielectric microwave absorbing materials with broad electromagnetic (EM) response is a significant project in EM wave absorption field. To achieve high-performance absorption and strong interfacial bonding at the same time, thermal-assisted in-situ bonding technology was applied to fabricating the dielectric composite absorbing materials. Thanks to the combination of vacuum filtration and in-situ hydrothermal reaction, the as-prepared binary composite aerogel shows both strong interface contacting and good mechanical stability. In addition, the carbon nanofibers/silica composite aerogel (CSA) exhibits ultra-broad effective bandwidth covering from S to Ku band, originated from the uniform dispersed silica aerogel in conductive carbon fiber network. In details, for CSA1 sample, the maximum reflection loss (RL) values and effective absorption bandwidth reach −46.2 dB (1.8 mm) and 5.2 GHz (1.5 mm). Meanwhile, the optimum RCS reduction values reaches 16.2 dB m2 when the detection theta was set as 0°. For CSA2 sample, the effective absorption bandwidth reaches 8.64 GHz at 1.5 mm, and tends to possess lower frequency EM response covering the S-band. This work exhibits a kind of broad-bandwidth aerogel absorbers at low thickness, which shows huge potential in large-scale production of microwave absorbing devices. [Display omitted] [ABSTRACT FROM AUTHOR]