Harsh Environment Applications Research Articles

Quantum dots may improve space laser communications by tolerating harsh radiation conditions

Bolstering semiconductor laser diodes’ radiation hardness can facilitate their application in harsh environments like space or nuclear power plants.

Experimental Investigation of Producer Gas Effects on Coated Pipelines in Biomass Downdraft Gasifier System

Abstract This research examines the performance of epoxy, ceramic, and graphene coatings on stainless steel 316 in a producer gas environment, focusing on corrosion and erosion resistance. This research aimed to identify the most effective coating for applications in harsh gasification environments. In this research, various analyses, including microstructural examination, hardness and weight measurements, FESEM analysis, and EDAX analysis, were conducted to evaluate the performance of the coatings. The producer gas was passed on to all the coated samples for a period of 100 hours. The significant findings include the superior corrosion and erosion resistance of ceramic-coated stainless steel, as evidenced by low weight fluctuations, maintained hardness levels, and elemental stability. Graphene coatings exhibit high hardness but increased porosity, raising concerns about durability, while epoxy coatings are vulnerable to gas-induced structural alterations. The inclusion rating analysis underscored the ceramic coatings' ability to preserve consistent material properties. Overall, ceramic coatings have emerged as the preferred option for gasification environments due to their structural resilience, inclusion integrity, and elemental stability. Considering the inclusion integrity, mechanical strength, weight stability, and elemental stability, ceramic-coated stainless steel 316 samples exhibit better resistance toward producer gas influence. This research contributes valuable insights for material selection in applications exposed to harsh gasification environments, emphasizing the importance of coating selection for long-term durability and performance.

Near-zero thermal expansion ZrW2O8/SiO2f wave-transparent composites: Interfacial anti-debonding structures based on polymeric films

The thermal stability of fiber-optic gyroscopes (FOGs) limits their application in harsh environments. This work utilized the unique water-retention properties of hyaluronic acid and the low-temperature cold sintering process combined to fabricate near-zero thermal expansion ZrW2O8/SiO2f composites with thermal resistance. Based on this novel process, the interface debonding of the composites is effectively suppressed and the mechanical and thermal properties of the composites are significantly improved (flexural strength increased by 69.47 %). Moreover, the interface anti-debonding structure reduces the interfacial polarization and reflection loss of the composites, and enhances the wave-transparent properties in the 2–18 GHz frequency range, with a minimum reflection loss of −0.21 dB. Furthermore, the interface anti-debonding structure of the composite provides creep resistance with enhanced sintering densities (increased by 13.61 %). Simultaneously, the composites achieve a controllable coefficient of thermal expansion (CTE) by regulating the liquid phase content and reach near-zero CTE (−0.246 × 10−6 °C−1 [30–300 °C]). Finally, finite element analysis and thermal shock experiments show that the anti-debonding interfacial structure has excellent thermal resistance, and the densest ZrW2O8/SiO2f composites exhibit the best thermal resistance due to minimal thermal strain during thermal shock, which is expected to meet the requirements of FOGs applications.

Experimental characterization of bond between concrete and HDG steel tubes for mixed steel-concrete structures

Bond between concrete and reinforcement material is crucial for the structural behaviour and design of reinforced concrete or mixed steel-concrete structures. When considering applications in harsh environments, such as severe marine exposure or submerged conditions, hot-dip galvanized (HDG) steel seems to be a promising solution, as part of new mixed steel-concrete structural systems. Although it is essential to guarantee an effective composite response, the interaction and bond behaviour between materials is not yet sufficiently well understood. This experimental investigation aimed to study the bond behaviour between concrete and HDG steel tubes, including the influence of adopting concrete pin connectors by creating holes in the tube profile, and also the influence of the galvanic surface state. The impact of bond length on the bond behaviour of the galvanized steel tube embedded in different concrete mixtures was analysed. Pushout tests were conducted to obtain the load end versus slip responses, as well as the failure modes. The results showed that the embedment lengths and the concrete compositions had no relevant effect on the overall shape of the pushout experimental responses, with the exception of the specimens that include the concrete pin connector. However, both variables clearly influenced the bond stress, dissipated energy during pushout until failure, and residual pushout force. The addition of the concrete pin significantly improved the adherence mechanism, while the contamination of the galvanic surface showed to significantly reduce the bond strength.

Ultra-flexible inorganic coating realized by scale-like nanosheets

Rapid development of foldable devices poses a challenging requirement on functional inorganic coatings with high flexibility. However, the inherent brittleness often renders inorganic coatings incompatible with flexibility. How to make flexible inorganic coatings remains challenging. Here, inspired by the scale structure of animal skins, we realize ultra-flexible scale-like coatings on polyimide (PI) film with layered double hydroxide (LDH) nanosheets. The adhesion is enhanced without peeling due to the bonding of polyimide with amino group attached to nanosheets. LDH nanosheets parallel to the substrate form scale-like structure that absorbs and releases stress to prevent coatings from cracking. And the coatings exhibit ultra-flexibility by surviving from 20,000 cycles of bending fatigue test. We apply the LDH-coated PI for atomic oxygen protection, which has important applications in aerospace industry. The coatings are designed as this special scale-like structure to release stress while possessing protection ability. Due to the barrier and adsorption of this flexible LDH coating, the erosion yield of the PI under an exposure of ~5 × 1021 atoms/cm2 is decreased by about 4 orders of magnitude to 0.015 % (~5 × 10−28 cm3/atom), which can satisfy the requirement for applications in harsh space environment of low earth orbit. Our work provides a general solution for simultaneously realizing high mechanical strength and flexibility in the coating technology, which may find applications in other areas, such as flexible electronics.

A Si-Nb co-alloyed AlCrN coating with good mechanical properties, excellent thermal stability and resistance to high temperature oxidation

The thermal properties of AlCrN coatings influence their application in harsh mechanical environments. This paper introduces a Si-Nb co-alloying strategy to prepare AlCrN-based coatings with good mechanical properties, excellent thermal stability and resistance to high temperature oxidation for developing high-performance tool coatings. The results indicate that, benefiting from the synergistic effect of replacing a portion of Si with an appropriate amount of Nb, Al0.59Cr0.31Si0.06Nb0.04N coating exhibits a fine columnar crystal structure different from the featureless dense structure of Al0.60Cr0.32Si0.08N coating. The different microstructure results in the difference of mechanical properties. Therefore, Al0.59Cr0.31Si0.06Nb0.04N has a higher hardness (32.3 ± 0.8 GPa) than Al0.60Cr0.32Si0.08N (28.8 ± 0.8 GPa). Meanwhile, the Al0.59Cr0.31Si0.06Nb0.04N coating get a better thermal stability and a comparable resistance to high temperature oxidation as Al0.6Cr0.32Si0.08N coating. The temperatures of thermal decomposition and oxidation resistance for Al0.59Cr0.31Si0.06Nb0.04N coating are increased by about 125 °C and 175 °C, respectively, compared with Al0.66Cr0.34N coating. In addition, the Si-Nb co-alloyed coatings maintain a better hardness after annealing.

Preparation of superhydrophobic coatings on kraft paper for the protection of important documents

Kraft paper (KP) has the advantages of being biodegradable, recyclable, and environmentally friendly. It has a wide range of applications in paper packaging, food packaging, and other fields. However, the non-waterproof characteristic of KP limits its application in harsh environments or special paper packaging, etc. To solve the problem of poor water resistance of KP, a simple and efficient method is proposed to prepare superhydrophobic coatings on kraft paper (SKP) by spraying method using hydrophobic Nano-calcium carbonate (Nano-CaCO3) particles and rosin (RA) as raw materials. Here, the micro-nano structures are mainly constructed by hydrophobic Nano-CaCO3 particles, and RA is utilized as a binder to improve the adhesion between the nanoparticles and the paper. The results indicated that the water contact angle (WCA) of SKP reached 154.5° and the water sliding angle (WSA) was 3.2°. And after 34 h of immersion in water, the WCA of SKP surface can remain above 150°. It can also withstand 30 times of sandpaper abrasion and 30 times of tape peeling. Overall, SKP shows excellent stability, water resistance, stain resistance and self-cleaning. It is expected to protect important documents in harsh environments.

Device and material investigations of GaN enhancement-mode transistors for Venus and harsh environments

This Letter reports the device and material investigations of enhancement-mode p-GaN-gate AlGaN/GaN high electron mobility transistors (HEMTs) for Venus exploration and other harsh environment applications. The GaN transistor in this work was subjected to prolonged exposure (11 days) in a simulated Venus environment (460 °C, 94 bar, complete chemical environment including CO2/N2/SO2). The mechanisms affecting the transistor performance and structural integrity in harsh environment were analyzed using a variety of experimental, simulation, and modeling techniques, including in situ electrical measurement (e.g., burn-in) and advanced microscopy (e.g., structural deformation). Through transistor, Transmission Line Method (TLM), and Hall-effect measurements vs temperature, it is revealed that the mobility decrease is the primary cause of reduction of on-state performance of this GaN transistor at high temperature. Material analysis of the device under test (DUT) confirmed the absence of foreign elements from the Venus atmosphere. No inter-diffusion of the elements (including the gate metal) was observed. The insights of this work are broadly applicable to the future design, fabrication, and deployment of robust III-N devices for harsh environment operation.

Rational Design of Amorphous Carbon-Coated Laminar-Structured Wood for Integrating Repeatable Early Fire Detection and High-Temperature Affordable Flexible Pressure Sensing in One System.

High-temperature affordable flexible polymer-based pressure sensors integrated with repeatable early fire warning service are strongly desired for harsh environmental applications, yet their creation remains challenging. This work proposed an approach for preparing such advanced integrated sensors based on silver nanoparticles and an ammonium polyphosphate (APP)-modified laminar-structured bulk wood sponge (APP/Ag@WS). Such integrated sensors demonstrated excellent fire warning performance, including a short response time (minimum of 0.44 s), a long-lasting alarm time (>750 s), and reliable repeatability. Moreover, it achieved high-temperature affordable flexible pressure sensing that exhibited an almost unimpaired working range of 0-7.5 kPa and a higher sensitivity (in the low-pressure range, maximum to 226.03 kPa-1) after fire. The high stability was attributed to reliable structural elasticity, and the wood-derived amorphous carbon is capable of repeatable fire warnings. Finally, a Ag@APP/WS-based wireless fire alarm system that realized reliable house fire accident detection was demonstrated, showing great promise for smart firefighting application.

Fully‐Recyclable Green and Fire‐Resistant Triboelectric Elastomer via Geometrical Synergistic Fillers and Its Applications for Smart Firefighting Boots

AbstractWearable sensors for high temperatures (WSHT) applications pose a significant challenge in the electronics field due to the inherent inability of most electronics to function in harsh environments. Triboelectric nanogenerators (TENG) present a substantial potential for applications in such challenging conditions. Herein, a fully‐recyclable flame‐retardant triboelectric elastomer is developed, which exhibits superior charge stability under high temperature conditions and proposes the specially designed synergistic fillers that play a dual role by trapping more charges into the interface and stabilizing the char layers via layer‐ball‐layer structure. An efficient flame‐retardant system is presented, which exhibits a 31% lower fire growth index than the individual components. The maximum surface charge density of this triboelectric elastomer can reach 361 µC m−2, while this surface charge density can be preserved to 70.9% after 16 s of combustion (≈520 °C) and to 37.9% by continuously working at 130 °C. At last, utilizing this flame‐retardant triboelectric elastomer, smart firemen's boots featuring gait analysis for identification and second level early warning systems have been developed. This work paves the way for the development of triboelectric materials and intelligent wearable devices suitable for applications in harsh environments.

Fabrication of hierarchical superhydrophobic structures by silane enriched with nanomaterials for enhancing permeability and freeze-thaw resistance

In this paper, the method of dehydration condensation reaction was used to establish a superhydrophobic cement mortar surface with the contact angle of 159.3° and the slide angle of 6.1° by using organosilane and inorganic nanomaterials. The nanoparticles built roughness and the silane provided low surface energy, which in combination achieved self-cleaning, waterproof and durability improvement. The superhydrophobic coating with good penetration depth is able to show superhydrophobicity after simply brushing and curing at room temperature for 24 hours and maintain hydrophobicity after surface abrasion. A variety of liquid droplets can roll freely from the surface of superhydrophobic cement mortar and carry contaminants rolling down to show self-cleaning performance. In terms of durability, the coating appears good adhesion to the surface of cement mortar, which retained its hydrophobic property after tape-peeling tests and outdoor simulation tests. In addition, compared with ordinary cement mortar, the superhydrophobic cement mortar demonstrates excellent waterproof ability and freeze-thaw resistance through low water absorption and slow quality reduction after multiple freeze-thaw cycles. These key characteristics provide advantages for concrete protection applications in harsh environments.

Source–drain switching characteristics when coupled with a gate-controlled DBD in a microplasma switch

Microplasma switches have attracted considerable attention in harsh environment applications, such as satellites, space exploration, nuclear reactors, and oil drilling, because of their inherent characteristics. A microplasma switch is generally constructed from a source, drain, and gate electrodes, and current conduction is generated between the drain and source (DS), and modulated by the gate. In this work, to improve the gate lifespan and device stability, a microplasma switch with a gate dielectric barrier structure is fabricated due to the even and stable discharge of a dielectric barrier discharge (DBD), and a parameterized nanosecond pulse voltage signal is applied to the gate. Under the effect of the DS voltage, a pulsed DS current is triggered by the gate pulse since a large number of charged particles are generated by the gate DBD, which shows that the DS switching behavior is triggered by the gate pulse. The microplasma switch operates stably (with an average delay jitter of less than 50 ps) at the repetition frequencies (up to 80 kHz). Moreover, the influence of experimental conditions on the switching performance is systematically investigated. The conduction current and delay, which are related to the discharge intensity and speed, are influenced by the electric-field strength of the channel (determined from the pulse amplitude and DS voltage) and its variation rate (determined from the rising and falling edge time of the pulse). In addition, the device performance is influenced by varying the breakdown voltage of the DS (determined from the gas pressure multiplied by DS spacing), which can result in variation of the working coefficient. It is also influenced by varying the wall voltage (decided by pulse width and frequency), which can result in the decrease in the total voltage of the channel.

Exploring the impact of multivalent substitution on high-temperature electrical conductivity in doped lanthanum chromite perovskites: An experimental and ab-initio study

Doped LaCrO3 perovskites hold promise as robust materials for electrical interconnects and sensor applications in harsh environments. In this work, we investigated the high-temperature behavior of La1–xSrxCrO3, La1–xCaxCrO3 and La0.8Sr0.2Cr1-x MnxO3 (0.1 ≤ x ≤ 0.4) through a combination of computational modeling and physical characterization up to 1500 °C. Crystalline structural properties were determined and compared with ab-initio calculations, which demonstrated excellent agreement with experimental findings. High-temperature electrical conductivity measurements were performed under different atmospheres. Calcium and strontium/manganese co-doped lanthanum chromites exhibited typical semiconductor exponential trends and conductivity showed proportional correlation with substitutions levels up to 30%. The DFT modelling was completed up to 1500 °C, including low and high temperature chromite phases and oxygen vacancies insertion. Calculations were correlated with experimental electrical properties. This work expands the understanding of doped lanthanum chromites and paves the way for the development of materials suitable for demanding high-temperature applications.

Shape memory polyimide/carbon nanotube composite aerogels with physical and chemical crosslinking architectures for thermal insulating applications

The development of lightweight smart materials with exceptional shape memory and thermal insulation properties is highly important in the aerospace industry. The reported shape memory polymer aerogels (SMPAs) are restricted to harsh environments because of their poor high-temperature resistance and large volume shrinkage at elevated temperatures. Herein, shape memory polyimide (PI) composite aerogels with superior thermal insulation were fabricated by combining molecularly designed PI chains with amino-functionalized carbon nanotubes (NH2-CNTs) through freezing gelation and subsequent thermal imidization. Because shape memory behavior was thermally triggered, the thermal conductivity associated with the shape memory mechanisms of the aerogels was comprehensively explored. The presence of CNTs promoted heat transfer in the aerogel skeleton, facilitating the shape recovery response. Benefiting from chemical-crosslinked and physical-crosslinked structures, the fabricated PI composite aerogels demonstrated desirable thermo-mechanical properties, exceptional shape memory and superior thermal insulation performance. This study may provide guidelines for designing shape memory PI composite aerogels for harsh environment applications in aerospace engineering.

A toroidal SAW gyroscope with focused IDTs for sensitivity enhancement

A surface acoustic wave (SAW) gyroscope measures the rate of rotational angular velocity by exploiting a phenomenon known as the SAW gyroscope effect. Such a gyroscope is a great candidate for application in harsh environments because of the simplification of the suspension vibration mechanism necessary for traditional microelectromechanical system (MEMS) gyroscopes. Here, for the first time, we propose a novel toroidal standing-wave-mode SAW gyroscope using focused interdigitated transducers (FIDTs). Unlike traditional SAW gyroscopes that use linear IDTs to generate surface acoustic waves, which cause beam deflection and result in energy dissipation, this study uses FIDTs to concentrate the SAW energy based on structural features, resulting in better focusing performance and increased SAW amplitude. The experimental results reveal that the sensitivity of the structure is 1.51 µV/(°/s), and the bias instability is 0.77°/s, which are improved by an order of magnitude compared to those of a traditional SAW gyroscope. Thus, the FIDT component can enhance the performance of the SAW gyroscope, demonstrating its superiority for angular velocity measurements. This work provides new insights into improving the sensitivity and performance of SAW gyroscopes.

Characterization of V-containing black plasma electrolytic oxide coatings on aluminium alloy: Impact of base electrolytes

Black oxide coatings on 6061 Al alloy were produced by plasma electrolytic oxidation (PEO) process in silicate- and phosphate-rich base electrolytes with addition of ammonium metavanadate (NH4VO3), respectively. The characteristics of PEO processes and resulting coatings were investigated. The thermal control properties of the coatings were measured. The corrosion protection performances of the coatings in an acidic environment were evaluated. Results show that the base electrolytes have significant influence on the PEO discharge behavior, coating characteristics and properties. There are more intensive discharges in silicate-rich electrolyte with addition of NH4VO3 (denoted as “Si–V″) than that in phosphate-rich electrolyte with addition of NH4VO3 (denoted as “P–V”), leading to higher thickness and more defects for the Si–V coating. Both Si–V and P–V coatings are characterized by black color in appearance due to the formation of V-containing compounds. However, the P–V coating has higher contents of V-containing compounds and therefore lower lightness and higher solar absorptance (αs) than the Si–V coating. In addition, the P–V coating exhibits better corrosion protection performance and color durability compared with the Si–V coating in acidic NaCl solution (pH = 3.1⁓3.3) due to the formation of AlPO4 in the coating. It is demonstrated that phosphate-rich base electrolyte with addition of NH4VO3 is a good candidate for getting stable black therm control coatings on Al alloy for practical applications in harsh environment.

The Effect of Epoxy Resin on the Infiltration of Porous Metal Parts Formed through Laser Powder Bed Fusion

Laser powder bed fusion (L-PBF) additive manufacturing technology can print multi-material parts with multiple functions/properties, and has great potential for working in harsh application environments. However, the metal blank formed by sintering metal powder material with binder added through L-PBF has an obvious porous structure and insufficient mechanical properties, and few studies have been conducted studying this. In this paper, epoxy resin was used to impregnate the blank of porous metal parts formed by L-PBF with iron-based powder material at a certain temperature, and a cross-linked curing reaction was carried out with three kinds of phenolic resin in different proportions under the action of a curing agent, so as to fill the pores and achieve the desired mechanical properties. The characteristic peaks of each group of epoxy resin were characterized using Fourier transform infrared spectroscopy (FT-IR) and H-nuclear magnetic resonance (1H-NMR) spectrums. The microstructure, decomposition temperature, and residue of four epoxy resin dispersion systems were analyzed with a scanning electron microscope (SEM), a thermal gravimetric analyzer (TGA), and derivative thermogravimetry (DTG). The results show that the density of the porous metal parts was obviously improved, the heat resistance temperature of the parts could reach 350 °C, and the tensile strength of the sample after EP2-1 impregnation was increased by 4–6 times after curing at 160 °C for 6 h. Therefore, the use of an epoxy resin dispersion system can increase the porosity of L-PBF porous metal parts, but can also significantly improve their mechanical properties, which can help them to meet the requirements of applications as model materials, biological materials, and functional materials to provide a feasible solution.

Formation and significance of topologically close-packed Laves phases in refractory high-entropy alloys

Refractory high-entropy alloys (RHEAs) inherently have a high potential to form topologically close-packed (TCP) Laves phases. Phase engineering to control the amount and type of TCP-Laves phases plays an important role in physical and mechanical properties of RHEAs. The present investigation addressed key parameters to TCP-Laves phase formation in RHEAs by considering thermodynamic calculations and empirical relations. Two novel TiVCrZrCo and TiVCrZrFe RHEAs were designed and fabricated as alloy models with high melting points (>2000 K) and relatively low density (∼6.5 g.cm−3) with multiphase microstructure including BCC matrix together with C14 and C15 Laves phases. Existence of atoms such as V, Co, Cr and Fe together with Zr, Ti, Nb and Hf refractory elements promote TCP-Laves phase formation. Very negative values for mixing enthalpy of atom pairs (ΔHmix) and remarkable differences between atomic sizes of the constitutive elements (δ) are key factors in the Laves phase formation in multicomponent alloys. The parameters including ΔHmix and δ must be in the defined range of −20 ≤ ΔHmix ≤ −3 kJ.mol−1 and 4 <δ < 10 to appear Laves phase in the microstructures of HEAs. TCP-Laves phase formation led to increase and decrease in hardness and fracture toughness, respectively. The understanding of key factors in RHEAs design can lead to phase engineering and the fabrication alloys with a desirable amount of TCP-Laves phase, which are suited for hydrogen storage applications or for applications in harsh operating environments exposed to high temperatures, irradiations, wear and erosion.

Numerical investigation of solder joint shape for micro-spring package during vacuum vapor phase soldering

The novel micro-coil spring package has become a new choice for reliable applications in extreme temperature change, high-strength impact, long-term vibration and other harsh environments due to the advantages arising from its special packaging design. The study of solder joint shape is an important step in the characterization of the package reliability. By Ansys Fluent software, the finite volume method was applied to investigate the flow behavior of molten solder during vacuum vapor phase soldering and the volume of fluid model was used to track the solder melt front. The simulation results reveal the effect of two critical process parameters (solder volume and pad diameter) on solder joint shape in micro-spring array package. The fillet height of the solder joint increases with decreasing pad diameter and decreases with decreasing solder volume. The optimal solder volume is 0.07 mm3 coupled a pad diameter of 0.80 mm, producing suitable fillet height and nice concave fillet shape, which is in agreement with the real sample of micro-spring soldering joint. The good consistency between experiment and simulation proves that the finite element method can effectively predict the shape of the melted solder. This work paves the way for the optimization of the solder joint shape in the electronic assembly.

High-efficiency electromagnetic wave absorption of lightweight Nb2O5/CNTs/polyimide with excellent thermal insulation and compression resistance integration

With the widespread application of electronic devices, multifunctional electromagnetic wave (EMW) absorbing materials suitable for complex high-temperature and high-pressure environments, have attracted tremendous research attention. Herein, multifunctional polyimide (PI) composites doped with fluffy Nb2O5/CNTs microspheres (NBCP) were prepared by combining the ultrasonic spraying process and freeze-drying technique. Introduction of fillers results in the formation of diverse conduction paths and heterogeneous interfaces, which enhance the dielectric loss. Furthermore, the multi-porous structure of the PI matrix induces multiple reflection scattering events and improves the impedance matching. Such a multi-loss mechanism endows NBCP with an excellent EMW absorption performance. At 15 vol% filling, the minimum reflection loss is −41.66 dB, the effective absorption bandwidth is 2.63 GHz, and the radar cross-section is reduced by 85%. Furthermore, NBCP exhibits outstanding mechanical properties and a thermal insulation of over 100 °C in thermal environment at 150 °C. The proposed multifunctional NBCP is thus an efficient EMW absorber that offers significant potential for applications in harsh environments.