Ceramic Stack Research Articles

Design and analysis of a piezo-actuated hydraulic micro-displacement amplifier with high bandwidth and large amplification ratio

Micro-displacement amplifiers show great potential for enhancing the performance of piezoelectric ceramic stacks. However, designing a compact micro-displacement amplifier with a high amplification ratio and broad bandwidth remains challenging. This article introduces a hydraulic micro-displacement amplifier driven by a piezoelectric ceramic stack with a large amplification ratio, high bandwidth, and eliminating parasitic displacement. Theoretical and simulation analyses are performed for the hydraulic micro-displacement amplifier, optimizing parameters such as edge thin ring thickness and spring stiffness. A prototype was fabricated and tested in a series of experiments. The experimental results demonstrate that, under steady-state conditions, the hydraulic micro-displacement amplifier achieves an amplification ratio of 26.12 with a standard deviation of 2.28. The maximum output displacement is 172.4 μm at 150 V, and the resonant frequency is 445 Hz under a 20 N load. This study provides a novel approach to designing micro-displacement amplifiers.

Sub-micro-g resolution test of accelerometers based on tilt dynamic modulation in gravity field

Abstract Strategic-grade accelerometers play a pivotal role in various application fields and fundamental research. As the performance of accelerometers are improving rapidly, the requirements for test method have been raised. However, due to the influence of environmental noise, the test facility for accelerometers, especially when the resolution reaches sub-μg level, remains a challenge.
To address this limitation, this study introduces a resolution test facility based on tilt modulation in gravity field, driven by piezoelectric ceramic stacks. The input acceleration ranges from 30ng to 10μg, and the frequency is adjustable from 0.01Hz to 20Hz. Since the input acceleration oscillates at certain frequency, modulation & demodulation technology enables us to extract ultra weak signal out of relatively noisy background. With this facility, we test the resolution of commercial strong motion accelerograph, quartz flexure accelerometers, and homemade accelerometer based on levitated optomechanics, proving the reliability of this method. Our advancement in test method lay solid foundation for strategic-grade accelerometers, not only provides a minimal resolution test solution in the ng~μg range, but also provides a possible scheme of evaluating dynamic response characteristic with an ultra-low acceleration input in a considerable frequency range.

A deep-learning-boosted surrogate model of a metal foam based protonic ceramic electrolysis cell stack for uncertainty quantification

Protonic ceramic electrolysis cells (PCECs) are widely considered as an emerging technology that shows capability for enabling environmentally friendly large-scale production of hydrogen. PCEC stacks’ performance is considerably lower compared to smaller, lab-scale button cells. This performance gap is largely attributed to the highly uneven distribution of reactants throughout the larger cell or stack, which presents a significant challenge to the development of PCEC stack. The issue of non-uniform reactant distribution in PCEC stacks can be effectively addressed by incorporating metal foam structures to replace the conventional rib design of the interconnect components. A 3D multiphysical model is developed to train a deep-learning-boosted surrogate model for PCEC with metal foam, which is subsequently used for parameter screening and sensitivity analysis. A collection of 12 inputs that encompass operating/structural/microstructural/material parameters are chosen, in which the operating parameters are identified as influential parameters. Three distribution uniformity indices maintain strong consistence to variations in the inputs, implying the positive role of metal foam. Faradaic efficiency (FE) is primarily influenced by the operating voltage with a total Sobol index of 0.6. The current density and FE are determined as the most stable performance indicators, exhibiting standard deviations of 0.15 and 0.81 respectively. According to a safety threshold of 10 K cm−1 for temperature gradient, the probability of the stack operating below this threshold is 88.61 %. Valuable insights into the design and performance of PCEC stacks that incorporate metal foam structures are provided. The workflow developed in this work can be further leveraged to explore and optimize PCECs.

Dynamic stability of a nitinol Langevin ultrasonic transducer under power and current tracking conditions

The Langevin transducer is widely used in medical and industrial ultrasonics, typically comprising a piezoelectric ceramic stack preloaded between two end-masses. A principal operational challenge is that, depending on the target application or operational environment, piezoelectric ceramics commonly experience elevated temperatures promoting nonlinear dynamic behaviours, often reducing operational performance. Transducers can be operated via burst excitation to mitigate this, but such methods can have limited efficacy, particularly at elevated temperatures. A novel emergent approach is the incorporation of shape memory Nitinol into the transducer, where its temperature-dependent microstructural phase transformations can compensate for changes in the mechanical properties of the piezoelectric ceramics. However, the ability to maintain dynamic stability under power and current tracking, common methods used to ensure stability of Langevin transducers in practical applications, remains unknown. In this research, a cascaded Nitinol Langevin transducer is used to demonstrate its practical application potential. Dynamic stability is assessed whilst power and current levels are tracked in operation. Stable operating frequency, electrical impedance, and vibration amplitude are shown, using a combination of methods including electrical impedance analysis and laser Doppler vibrometry. This research demonstrates the practical application of Langevin transducers incorporating shape memory materials, including with dynamic stability at elevated temperatures.

CFD simulation and design of ceramic hollow fiber membrane stack for oxygen separation

Hollow fiber ceramic membrane technology demonstrates a great potential for high performance oxygen separation from air. Upscaling of single hollow fiber membrane for membrane stacks and modules is necessary toward practical applications. However, experimental methods are very time-consuming and highly cost. Mathematical modeling is a cost-effective technique and very flexible to evaluate different upscaling strategies. In this research, built upon the experimental results of a proof-of-concept hollow fiber membrane stack, a computational fluid dynamics-based Multiphysics stack model is developed and validated. Comprehensive simulations are conducted to understand the behaviors of stacks under different operating conditions. Different designs strategies are also evaluated toward optimizations of stack performance.

A comprehensive 3D modelling exploration of a protonic ceramic electrolysis cell stack with metal foam

Protonic ceramic electrolysis cells (PCECs) offer significant potential for large-scale green hydrogen production. The performance of conventional PCEC stacks is notably limited due to the uneven gas distribution. In this research, a new stack design using metal foam as the gas distributor is proposed and numerically evaluated using a 3D Multiphysics model to improve the gas distribution uniformity. At 1.3 V and 600 °C, the current density of the newly designed PCEC with metal foam is 173 % higher than that of the conventional PCEC. Moreover, the hydrogen production capability of metal foam based PCEC is 234 % higher than that of conventional PCEC, due to the improved gas distribution uniformity and faradaic efficiency (FE) of the new PCEC. The application of metal foam increases steam distribution uniformity by 91.2 %. In a conventional PCEC, the FE under the rib is notably lower than that under the channel. In contrast, the FE distribution is more uniform in a metal foam based PCEC. The improved performance in terms of current density, FE, and distribution uniformity highlights the potential of metal foam as a beneficial component in PCEC stacks. These findings contribute to the understanding and further development of PCEC technology.

A Timoshenko-Ehrenfest beam model for simulating Langevin transducer dynamics

The Langevin transducer is a widely used power ultrasonic device across both medical and industrial applications, from orthopaedic surgery to drilling and welding. It is a sandwich-type device which typically consists of piezoelectric ceramic rings between two metallic end-masses. The transducer is commonly operated at a particular resonant mode to deliver ultrasonic vibrations to a target structure of interest, and is generally modelled using approaches including the transfer matrix method and electromechanical equivalent circuit methods. Here, we propose a variational framework to study the dynamics of the Langevin transducer based on the Timoshenko-Ehrenfest beam theory and Hamilton's principle. The variational equation derived from this model is then discretized by the standard finite element method with spectral elements. To verify the proposed one-dimensional electromechanical model, the computed resonance frequencies, or natural frequencies, of the one-dimensional model are compared to those of a three-dimensional finite element model with respect to varying geometry parameters characterizing the transducer. The results of the reduced one-dimensional and full three-dimensional models are then compared to those measured through an experimental investigation consisting of laser Doppler vibrometry. This is undertaken for the first ten eigenfrequencies, including longitudinal and bending modes, where normalized amplitudes and vibration mode shapes are reported. The close correlation between modelling and experiment demonstrates that the proposed one-dimensional electromechanical model can deliver results consistent with the full three-dimensional model and from experiment, thus verifying a rapid and reliable method for studying the free vibrations and dynamics of the Langevin transducer which accounts for the axial vibrations of the piezoelectric ceramic stack in all cases.

Generation of effective pulsed waterjets by ultrasonic nozzle used for energy exploration

Pulsed waterjet has higher energy efficiency ratio and less energy consumption than a continuous waterjet. To achieve more effective and powerful pulsed waterjets, a new ultrasonic nozzle with more compact structure and less energy loss was developed. By designing a hollow flow channel in the piezoelectric ceramic stack and the amplifier, the nozzle enables axial water inlet and avoids energy loss at the turnaround point. The resonant frequency of the ultrasonic nozzle was validated as 19227 Hz by modal analysis and impedance test, which is a deviation of 3.87% compared with the expected frequency of 20000 Hz. Besides, the pulse characteristics of modulated waterjet were analyzed experimentally by high-speed photography. The pulsed waterjet presented obvious periodic pulses and good clustering, and water slugs of "mushroom" shape can be clearly observed. The difference between the waterjet velocity and the theoretical value is less than 7.7%. And the pulse frequency of the modulated waterjet reaches about 19485.1 Hz, with a deviation of 1.3% compared with the nozzle resonant frequency of 19227 Hz. The new ultrasonic nozzle can be widely used in energy exploration for effective pulsed waterjet generation and less energy consumption.

Lead-free hybrid piezoelectric ceramic stack for both potent and temperature-stable piezoelectricity

A novel lead-free hybrid piezoelectric ceramic stack provides high-performance and temperature-stable piezoelectric properties with a 4.7% variation up to 300 °C.

Functionalized Nanoporous Ceramic Membranes for Electrodialysis Treatment of Harsh Wastewater

INTRODUCTION Electrodialysis (ED) is a well-developed technology for electrochemical desalination. However, many industries generate harsh wastewater streams that are incompatible with traditional ion exchange membranes and thus limit the use of ED. Membrion® has developed novel ceramic-based ion exchange membranes which offer a number of advantages over traditional polymer membranes: high performance in low pH, chemical resistance to oxidizers, and a rigid structure which minimizes membrane swelling. This presentation will discuss these novel membranes and their performance in electrodialysis stacks. EXPERIMENTAL Novel ceramic ion exchange membranes (IEM) are synthesized with patented silane-based sol-gel techniques. These ceramic membranes have covalently bound charged moieties similar to polymer IEMs; however, they are attached to a tunable nanoporous structure. The pore size, shape, and network structure are engineered through a molecular self-assembly process where thermodynamic driving forces are used to direct where and how pores form. Either cation (e.g., SO3 -) or anion (e.g., NH4 +) groups can be added within the membrane nanopore structure to enhance ion selectivity. The ceramic IEMs are produced on a roll-to-roll manufacturing line with low temperature processing. Membrane performance is assessed by measuring permselectivity (PS), area-specific resistance (ASR), and batch electrodialysis tests. RESULTS Figure 1 shows that both cation exchange membranes (CEM) and anion exchange membranes (AEM) show a decreased ASR compared to traditional polymer membranes, while maintaining comparable PS (i.e., the ability to separate cations and anions). The lower ASR of ceramic membranes is advantageous, as this can improve the overall energy efficiency of electrodialysis desalination. We maintain good performance (i.e., comparable current efficiency and water recovery) when integrated into a 10-cell pair stack. Most significantly, the right plot of Figure 1 shows a stable dilute water recovery of ~90% achieved with ceramic membranes after being stored in solutions ranging from pH 3 to pH 0 for 30 days. We have also demonstrated this technology in the field with copper wastewater generated at a microelectronics manufacturing facility. On site bench and pilot testing showed that our membranes could be used to nearly eliminate the copper sent to single-use IEX resin. DISCUSSION Ceramic-based ion exchange membranes are able to achieve comparable performance to traditional polymer membranes and offer some unique advantages. Long exposure to very low pH has negligible impact on ceramic ED stack performance. Additionally, we have observed stable performance in the presence of strong oxidizing agents such as hydrogen peroxide. This stability is expected, as the silica backbone of these materials is already in a fully oxidized state, as opposed to traditional polystyrene-based membranes. This data suggests ceramic membranes could be an ideal solution for acidic and/or oxidizing wastewater streams found in industries such as semiconductor manufacturing and mining. In addition to offering chemical stability in harsh environments, the patented silica sol-gel process used to cast these membranes is extremely tunable. Through incorporating commercially available functionalized silanes, the pore size and chemical make-up can be easily altered to target specific waste streams. CONCLUSIONS Ceramic ion exchange membranes are shown to have similar performance attributes to traditional polymer IEMs when evaluated for electrodialysis water purification applications. The good stack-level performance combined with stability in harsh environments have the potential to dramatically broaden the use of ED/EDR for industrial wastewater treatment. Figure 1

Traveling wave thermoacoustic refrigeration with variable phase-coordinated boundary conditions.

Thermoacoustic refrigerators exploit the thermodynamic interaction between oscillating gas particles and a porous solid to generate a temperature gradient that provides a cooling effect. In this work, we present a resonator with dual enclosed driver end-caps and show that the temperature gradient across a ceramic thermoacoustic element placed in the cavity could be controlled by modifying the phase difference of the drivers, thus enabling precise control of the refrigeration capability via the temperature difference. Through deltaec simulation results, the response of the temperature gradient to various dynamic boundary conditions that alter the time-phasing and wave dynamics in the resonator are demonstrated. An experimental apparatus is constructed with two moving-coil speakers and a ceramic stack, which is shown to exhibit a temperature gradient along its length, based on the traveling-wave-like nature of the acoustic wave excited by the speakers. By adjusting the relative phase lag between the two speakers, the temperature gradient across the stack is made to increase, decrease, or flip sign. Finally, a desired temperature difference that changes in time is achieved. The results presented in this work represent a key conceptual advancement of thermoacoustic-based temperature control devices that can better serve in extreme environments and precision applications.

Material composition and microstructure of ceramic glass й hearth of blast furnace No. 6 of JSC EVRAZ NTMK after service. Refractory microstructure after service

The results of a comprehensive study of the material microstructure of refractory samples after service in the furnace of a blast furnace with a useful volume of 2200 m3 for 14 years are presented. Structural and genetic analysis established a characteristic sequence of processes of degeneration and wear of the ceramic furnace stack, including 6 stages: the formation of micro-and macro-cracks; condensation of vaporous zinc; zinc oxidation with the formation of fire-resistant ZnO zincite and the deposition of carbon black by the; chemical interaction of zinkite with mullite and corundum to form ZnAl2O4 ganite and 2ZnO·SiO2 willemite; partial oxidation of silicon carbide with the release of silica glass SiO2, eutectic melt of complex composition, and wellimite. Due to intensive accumulation of capillary pores, infiltration of the slag melt in the volume of refractories does not occur. Wear of refractories in the furnace has a complex, mainly thermochemical mechanism and a low speed due to the formation of a garnish containing refractory compounds. Ill. 5. Ref. 14.

Design of a New Type of Electrochemical Ceramic Membrane Oxygen Production System

In order to solve the problem that the existing oxygen production technology cannot simultaneously produce pure oxygen, high-purity oxygen, ultra-pure oxygen, and the modular expansion of oxygen production capacity, a new type of electrochemical ceramic membrane oxygen production system was discussed and developed. Through the design of the ceramic membrane stack, airflow distributor, heater, double spiral exchanger, thermal insulation sleeve, control panel, control box and auxiliary system in the electrochemical ceramic membrane oxygen generator, a modular oxygen production system is formed. The modular design can produce pure oxygen, high-purity oxygen and ultra-pure oxygen to meet various oxygen consumption needs. The electrochemical ceramic membrane oxygen production system is a new type of oxygen production technology. The main components have no moving parts, no noise, and no pollution. It can produce pure oxygen, high-purity oxygen and ultra-pure oxygen on site, with small size, light weight, and module combination which is suitable for convenient expansion and installation of oxygen consumption.

Material Composition and Microstructure of Ceramic Stack and Hearth of JSC EVRAZ NTMK Blast Furnace No. 6 After Service. Refractory Microstructure After Service

Material Composition and Microstructure of Ceramic Stack and Hearth of JSC EVRAZ NTMK Blast Furnace No. 6 After Service. Refractory Microstructure After Service

Fatigue behaviour of piezoelectric ceramic stack under large cyclic dynamic loading

The fatigue behaviour of a piezoelectric ceramic stack co-fired at low temperatures under the influence of a large cyclic dynamic load was studied. The piezoelectric ceramic stack is equivalent to a parallel plate capacitor with a charge source in parallel. The equations for the total current, output current and capacitor charging current of an equivalent device for an applied load were derived using Kirchhoff’s theoretical formula. A new type of fatigue test equipment was developed for continuous long-term M-shaped wave output. The piezoelectric ceramic stack is positioned between two concrete slabs, forming a pavement-subgrade piezoelectric structure. The fatigue behaviour of the piezoelectric ceramic stack was observed for 800,000 cycles of dynamic load. The results show that the dynamic load studied produced fatigue damage in the piezoelectric ceramic stack. As the number of dynamic loads increased, the electric output capacity of the piezoelectric ceramic stack decreased. Evident stage divisions were observed in the fatigue behaviour of the piezoelectric ceramic stack under cyclic dynamic loading. The electric output capacity of the stack decreased as the number of dynamic loads increased in the early and late stages, whereas it exhibited negligible change during the stable period.

Flow and Species Distribution Characteristics in a 15-cells Proton Ceramic Fuel Cell Stack with the Inter-Parallel Flow Field Channel by 3D Modeling

Flow and Species Distribution Characteristics in a 15-cells Proton Ceramic Fuel Cell Stack with the Inter-Parallel Flow Field Channel by 3D Modeling

Preparation of multilayer ceramic tapes by aqueous gel-tape co-casting

The method for the production of multilayer tapes by the aqueous epoxy-based gel-tape co-casting of ceramic suspensions is described. The method enables preparing multilayer tapes with a defect-free interface. The method extends the applicability scope of the epoxy-based gel-tape casting method from high quality single-layer materials towards multilayer materials or materials with gradient doping. A triple-layer material was prepared and the quality of the interface was investigated down to grain level using microscopy techniques. A sharp interface between adjacent layers was obtained with no delamination detected. The areal quality of the interface in co-cast tapes was demonstrated on transparent bi-layer alumina tapes. The relative density of the bi-layer alumina tapes reached 99.99% after pressure-less sintering. The results proved the epoxy gel-tape co-casting method to be applicable for the preparation of high-quality fine powder ceramic stacks.

Design of a Panoramic Scanning Device Based on a Piezoelectric Ceramic Stack Actuator and Friction Transmission

In view of the complex structure and inaccurate positioning capabilities of the existing panoramic scanning system, a panoramic scanning device based on a piezoelectric ceramic stack actuator and friction transmission was designed. In our model, the output displacement of the piezoelectric ceramics is amplified by a bridge-type flexure hinge and applied to a shaft by friction to achieve panoramic scanning imaging. The mathematical model of the device was established, and the working characteristics were analyzed. The analysis demonstrated that the linear displacement increment of the shaft is a superposition. A modality simulation was performed, and the simulation results show that the designed device works normally at a frequency of 511.5 Hz. The test results indicated that the displacement of the actuator can reach 6 μm at an input voltage of 100 V. Moreover, the laser scanning results showed that the designed device can perform panoramic scanning imaging, which meets the requirements for use on the high-speed imaging system.

Study on Single Crystal Holmhertz Underwater Acoustic Transducer

According to the theoretical calculation and finite element simulation, a Holm-Hertz transducer is designed. When the resonant frequency of the outer liquid cavity of the transducer is consistent with the resonant frequency of the piezoelectric ceramic stack, the maximum transmit voltage response(TVR) is obtained. After the electrical material was replaced with a new relaxation ferroelectric single crystal piezoelectric material PIN-PMN-PT, the resonant frequency of the transducer was reduced, and the liquid cavity structure was redesigned. Single crystal, can significantly reduce the resonant frequency of the transducer, while significantly increasing the transmit voltage response.

Quiet power: Exploring the feasibility of a noise-mitigating, thermoacoustic energy harvester

The thermoacoustic effect provides a means to convert acoustic energy to heat and vice versa without the need for moving parts. This enables the realization of mechanically robust, noise mitigating energy harvesters, although there are limitations to the power-to-volume ratio achievable. The mechanical, thermal, and geometric properties of the porous stack that forms a set of acoustic waveguides in thermoacoustic devices are key to its performance. In this feasibility study, first, various 4-in. diameter ceramic and polymeric stack designs are evaluated using a custom-built thermoacoustic test rig. Influence of stack parameters such as material, length, location, porosity, and pore geometry are correlated to simulations using DeltaEC, a software tool based on Rott’s linear approximation. An acousto-thermo-electric transduction scheme is employed to harvest useable electrical power using the best performing stack. Steady-state peak voltage generated was 33.5 mV for a temperature difference of 34 °C between thehot and cold sides of the stack at an acoustic excitation frequency of 117.5 Hz. Further investigations are underway to establish structure-performance relationships by extracting scaling laws for power-to-volume ratio and frequency-thermal gradient dependencies.