Planar Microstructure Research Articles

Continuous and Stable Printing Method of Planar Microstructure Based on Meniscus-Confined Electrodeposition.

The meniscus-confined electrodeposition (MCED) technique offers advantages such as low cost and wide applicability, making it a promising method in the field of micro/nanofabrication. However, unstable meniscal morphology and poor deposition quality during planar deposition in MCED necessitate the development of improved methods. Therefore, a planar adaptive micro-tuning deposition method (PAMTDM), which utilizes the positioning technology of scanning electrochemical cell microscopy (SECCM) and employs a singular value decomposition (SVD) planar fitting method to determine the flatness of the deposition plane, is proposed. An adaptive micro-tuning motion mode was proposed by analyzing the variation patterns of the meniscus. Moreover, a combination of multi-physics finite element simulations and orthogonal experimental methods was introduced to determine the optimal motion parameters. The experimental results demonstrate that the PAMTDM effectively addresses the issues encountered during planar growth. Compared to the point-by-point deposition method, the PAMTDM achieves a threefold increase in deposition speed for continuous deposition of 105-μm-long line segments in two-dimensional planes, with a deposition current error of less than 0.2 nA. In conclusion, the proposed method provides significant insights into the broad future applications of MCED.

Predictive microstructure distribution and printability maps in laser powder bed fusion for a Ni–Cu alloy

The solidification microstructure of a melt pool under additive manufacturing conditions is highly heterogeneous due to the heterogeneity in the thermal spatio-temporal fields. This work combines a finite element (FE)-based thermal model with a phase field model (PFM) to predict microstructure distribution among the process parameter span in LPBF, which is strongly controlled by local thermal histories. The segregation distribution across the parameter space can be classified into four different microstructure distribution types: (i) fully planar, (ii) bottom dendritic, (iii) top dendritic, and (iv) fully dendritic. Also, the relationship between the thermal histories (the temperature gradient (G) and the growth rate (R)) variation induced by P and V→ and the microstructure distribution is clearly analyzed in the paper. For a Ni-20 at.%Cu alloy, the predicted microstructural distribution is verified experimentally. The parameter space is further divided into homogeneous and heterogeneous regions using the predicted area fraction of cellular–dendritic segregation across the melt pools. The process map is then used to build AM parts with homogeneous microstructures, where only planar microstructure is found experimentally. This methodology will aid in the exploitation of the alloy and processing space to identify alloy-process combinations that yield microstructurally-homogeneous, defect-free parts, provided an unconditionally printable regime can be identified.

Low-Density Unsaturated Polyester Resin with the Presence of Dual-Initiator.

Dual-initiation is a new orientation of many studies in the curing of unsaturated polyester resin and the manufacture of low-density unsaturated polyester resin (LDUPR) composite materials. In our research, two kinds of low-temperature (40-70 °C) initiators (cyclohexanone peroxide (CYHP) and methyl ethyl ketone peroxide (MEKP)), one kind of medium-temperature (70-130 °C) initiator (tert-butyl peroxy-2-ethylhexanoate (TBPO)), and three kinds of high-temperature (≥130 °C) initiators (tert-butyl benzoate peroxide (TBPB), tert-amyl carbonate peroxide-2-ethylhexanoate (TAEC), and tert-butyl carbonate peroxide-2-ethylhexanoate (TBEC)) were applied to constitute different dual-initiators. Those dual-initiators were a low-temperature dual-initiator (CYHP/MEKP), medium-low-temperature dual-initiators (CYHP/TBPO and MEKP/TBPO), and high-temperature dual-initiators (TAEC/TBPB, TAEC/TBEC, and TBEC/TBPB). In the low-temperature and medium-low-temperature ranges, the LDUPR sample displayed the highest specific compression strength (Ps) of 42.08 ± 0.26 MPa·g-1·cm3 in the presence of the MEKP/TBPO dual-initiator. In the high-temperature range, the LDUPR sample exhibited the highest specific compression strength (Ps) of 43.32 ± 0.45 MPa·g-1·cm3 for the existence of the TAEC/TBPB dual-initiator. It is pointed out that the dual-initiator released more active free radicals, accelerating the initial curing time and the peak time of UPR. More active free radicals caused both high-activity (short-chain) molecules and low-activity (long-chain or intertwined) molecules in resin to cross-link, prolonging UPR's curing process by approximately two minutes and resulting in an improvement of UPR's cross-linking. In the presence of a dual-initiator, the integrated and planar microstructure of LDUPR samples performed uniformly distributed dimples, dispersed external forces, and enhanced samples' specific compressive strength.

3D-printing-assisted flexible pressure sensor with a concentric circle pattern and high sensitivity for health monitoring

In this study, a flexible pressure sensor is fabricated using polydimethylsiloxane (PDMS) with a concentric circle pattern (CCP) obtained through a fused deposition modeling (FDM)-type three-dimensional (3D) printer and poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) as the active layer. Through layer-by-layer additive manufacturing, the CCP surface is generated from a thin cone model with a rough surface by the FDM-type 3D printer. A novel compression method is employed to convert the cone shape into a planar microstructure above the glass transition temperature of a polylactic acid (PLA) filament. To endow the CCP surface with conductivity, PDMS is used to replicate the compressed PLA, and PEDOT:PSS is coated by drop-casting. The size of the CCP is controlled by changing the printing layer height (PLH), which is one of the 3D printing parameters. The sensitivity increases as the PLH increases, and the pressure sensor with a 0.16 mm PLH exhibits outstanding sensitivity (160 kPa−1), corresponding to a linear pressure range of 0–0.577 kPa with a good linearity of R2 = 0.978, compared to other PLHs. This pressure sensor exhibits stable and repeatable operation under various pressures and durability under 6.56 kPa for 4000 cycles. Finally, monitoring of various health signals such as those for the wrist pulse, swallowing, and pronunciation of words is demonstrated as an application. These results support the simple fabrication of a highly sensitive, flexible pressure sensor for human health monitoring.

Effect of polyanionic cellulose modification on properties and microstructure of calcium bentonite

Soil-bentonite slurry trench cutoff walls have been extensively used as engineered barriers for contaminant containment. In some regions without appropriate sodium bentonite (NaB), local calcium bentonite (CaB) that is cheap and abundantly available may be considered as an alternative material. However, CaB has a poor swelling capacity and it is important to improve the properties to meet the requirements of the cutoff walls. As a highly effective filtrate reducer and viscosifier, polyanionic cellulose (PAC) has been used to modify NaB and Na activated CaB to enhance their chemical compatibilities, but its application to natural CaB has been seldom studied. Therefore, this study aimed to identify the optimal reaction condition for PAC-CaB preparation using a more systematic slurrying-drying-grinding method and preliminarily evaluate the application potential of PAC-CaB in slurry trench cutoff walls from the perspective of the workability of bentonite slurry. The effect of PAC modification on the physicochemical properties of CaB and workability of CaB slurry were explored by a series of laboratory experiments. The modification mechanisms of PAC were comprehensively revealed by means of scanning electron microscopy, Fourier transform infrared spectroscopy and X-ray diffraction. The results show that as the PAC dosage (by mass) increased from 2 to 8%, the swell index of CaB increased almost linearly and exceeded that of NaB. Both 4% and 8%PAC-CaBs had a lower hydraulic conductivity and a better chemical compatibility (using 10 mM CaCl2) than NaB. Moreover, PAC modification could significantly enhance the workability of CaB slurry, approaching or even exceeding that of NaB slurry, and reduce the bentonite content. A planar or spatial network microstructure was observed in PAC-CaB due to the interactions between PAC and CaB involving bridging and bonding. Overall, PAC is a promising modifier for CaB and PAC-CaB has the potential to replace the NaB in stabilizing the trench wall during construction.

Features of the radiative properties of quantum-size particles of narrow-gap semiconductors

For colloidal quantum-size particles (QP) of narrow-gap semiconductors, in contrast to quantum dots of wide-gap CdSe, in QP-PbS there take place an anomalous temperature dependence of the photoluminescence intensity. Also, in the planar microstructure containing QP-InSb, long-wavelength radiation (more than 3 μm) and photoconductivity (over 20 μm) was observed. Under certain conditions, the radiation intensity and photoconductivity demonstrate a resonance maximum. The effects were explained in the model of a one-dimensional quantum oscillator, which energy substantially depends on the effective mass of its quasi-free electron. This leads to competition between the manifestations of long-wave radiation and photoluminescence, and hence, to the anomalous temperature dependence of photoluminescence. It is assumed that QP-InSb in a planar microstructure can be sources and receivers of terahertz radiation, which properties depend on the crystal structure of quantum-sized particles determined by the parameters of their synthesis. Keywords: quantum-dimensional particle, quantum dot, narrow-gap semiconductor, effective mass, Brillouin zone, dimensional quantization, quantum oscillator, photoluminescence, long-wavelength radiation.

Capillary transfer: Numerical study of how topology affects the fluid flow rate into a planar microstructure with pseudopotential multiphase Lattice-Boltzmann method

We investigate how topology impacts capillary action with the hope of aiding future thermal engineering decisions. Heat pipes and their two-dimensional variant, vapor chambers are essential components in electronics cooling. With thin-film evaporation as the driving force for such high-heat-flux movers, studies have been done to optimize the thermal performance of different designs. However, the fundamental problem of liquid transportation needs to be addressed exclusively: evaporation can only work as long as the new liquid is continuously being replaced. The device achieves this by the capillary process (or wicking) through the thermal ground (or wicks): a configuration of microstructures attached to the device's walls. Some planar topologies of the structure allow for consistent but slower mass feeding; others offer higher bandwidth but with local flow hindrance, creating a pulsating tendency; certain conditions would even block the capillary flow. Surveying the capillary performance of different two-dimensional designs of the thermal ground, we encounter a topological factor that correlates with this mass transfer rate. We incorporate in the factor the wick's width, its height, and the gap between one microstructure to another. An energy model is studied to explain the underlying influence of the structure topology, while Lattice-Boltzmann method is used to evaluate the capillary dynamics inside the thermal ground. With ultra-thin applications in mind, the paper looks at the length scales of micrometers with a wick height of 50 μm. Overall, we find that tightly packed structures pull the most liquid in the same amount of time; however, we find that two core constraints need to be met: sufficient clearance between structures and freedom of mobility.

Design and Fabrication of a Functionally Gradient SOFC Electrode with Controllable Porous Microstructure

A controllable and gradient porous ceramic structure is desirable for many applications including solid oxide fuel cells (SOFC), ceramic filters or gaseous component separation. There are numerous ways to fabricate porous ceramic structures, including the use of pore formers, particle size control or freeze casting. The process we used was string-coating. Strings with various materials’ coating and coatings on various strings could be a controllable element for assembling a planar or tubular ceramic microstructure. In this research, ceramic microtubes were made using removable templates covered by layers of ceramic materials using sol-gel technology. A low-cost device was designed and built for coating multiple layers of slurry onto templates efficiently. Tested templates included silk (single and triple strands), cotton thread, and angel hair pasta coated with 1, 5, 10, 15, 20, or 25 layers of slurry and then fired with a 5-stage heating cycle up to 1,100°C/1,450°C over a period of 20 hours. Samples were analyzed using a scanning electron microscope (SEM). Average diameters were calculated by measuring 30 diameters from different locations of each tube. The 20× and 25× coatings on the single silk strand, sintered at 1,450°C, resulted in the strongest and most density-uniform microtubes by decreasing the porosity. The single silk strand with 20× coating under 1,450°C firing formed a 25µm diameter hole and an average outer diameter (OD) of 39.90 µm with a standard deviation of 0.97 µm, while the 20× coating under 1,100°C resulted in an average 67.46 µm OD with a standard deviation of 1.14 µm. The 25× coating resulted in a 49.89 µm OD with standard deviation of 0.99 µm when fired up to 1,450°C. The success of this process set a foundation for assembling the individually controllable single microtubes to form ceramic planar or tubular shapes that their microstructure is controllable in terms of composition, pores size, porosity and connectivity.

Особенности излучательных свойств квантово-размерных частиц узкозонных полупроводников

For colloidal quantum-size particles (QP) of narrow-gap semiconductors, in contrast to quantum dots of wide-gap CdSe, in QP-PbS there take place an anomalous temperature dependence of the photoluminescence intensity. Also, in the planar microstructure containing QP-InSb, long-wavelength radiation (more than 3 µm) and photoconductivity (over 20 µm) was observed. Under certain conditions, the radiation intensity and photoconductivity demonstrate a resonance maximum. The effects were explained in the model of a one-dimensional quantum oscillator, which energy substantially depends on the effective mass of its quasi-free electron. This leads to competition between the manifestations of long-wave radiation and photoluminescence, and hence, to the anomalous temperature dependence of photoluminescence. It is assumed that QP-InSb in a planar microstructure can be sources and receivers of terahertz radiation, which properties depend on the crystal structure of quantum-sized particles determined by the parameters of their synthesis.

Effect of Trajectory Curvature on the Microstructure and Properties of Surfacing Wall Formed with the Process of Wire Arc Additive Manufacturing

Curvature effects are typically present in the process of additive manufacturing (AM), particularly for wire arc additive manufacturing. In this paper, stainless-steel wire was adopted to deposit thin-walled samples with different curvatures. Optical microscopy, SEM, EDS and micro-hardness was used to analyse the microstructure, composition and properties of the samples. The result shows that the bottom region of the thin-walled sample had a mainly planar and cellular crystal microstructure. For the middle region, the microstructure revealed mainly dendrites, and the top layer has equiaxed dendrite morphology. The microhardness value of the bottom was greater than that of the middle, and the microhardness value of the middle was greater than that of the top. Moreover, the grain size of the inner part (direct to curvature radius) was larger than that of the outer part, and the micro-hardness value exhibited an increasing tendency from the inner to the outer side. With enlarging curvature, the degree of grain size differences and micro-hardness variants decreased. Finally, an investigation with a low carbon steel wire showed that it had a similar curvature effect for its AM specimen.

Study on the Design of bridge microstructure for Energy Conversion Components

Microstructure energy conversion components, as the key components of MEMS initiating explosive device, has a significant impact on the output performance and energy utilization of the initiating explosive device, especially the design of its bridge microstructure. In order to perfect the design theory of microstructure energy conversion components of MEMS (Micro Electro-Mechanical Systems) initiating explosive device, 8 different bridge microstructure are designed for energy conversion components in this paper, and using simulation research and infrared test to carry out the research on the planar microstructure effect and the better bridge type choice of a series of bridge type. Obtained two optimization bridge structure of microstructure energy conversion components and the influence law between different microstructure and output performance of energy conversion components, and the average ignition voltage of V-50 bridge microstructure energy conversion components up to 100μF/3.5V, and the energy utilization rate is 46.6%°

Aerosol Jet Printing of Platinum Microheaters for the Application in Gas Sensors

This paper presents the results of characterization of microheaters fabricated on the surface of ceramic substrates by aerosol jet printing with commercially available platinum ink containing colloidal particles with the average size of about 100 nm. The microheater under study represents planar microstructure with variable cross-sectional area comprising narrow segment capable of being heated up to few hundred degrees when current is passed through. The narrow segment is fabricated in the form of single line with the width and height of 50 μm and 6.7 μm, respectively. To remove the organic substance from the deposited material (dry residue of the ink), the printed microheaters were fired at 150°C for 20 min. The dependence of the operating temperature on the power consumed by the microheater was obtained from the measurements of direct current resistance as a function of consumed power with the use of previously determined temperature coefficient of the material (3.910−3 K−1).

Ultracompact all-optical full-adder and half-adder based on nonlinear plasmonic nanocavities

Abstract Ultracompact chip-integrated all-optical half- and full-adders are realized based on signal-light induced plasmonic-nanocavity-modes shift in a planar plasmonic microstructure covered with a nonlinear nanocomposite layer, which can be directly integrated into plasmonic circuits. Tremendous nonlinear enhancement is obtained for the nanocomposite cover layer, attributed to resonant excitation, slow light effect, as well as field enhancement effect provided by the plasmonic nanocavity. The feature size of the device is <15 μm, which is reduced by three orders of magnitude compared with previous reports. The operating threshold power is determined to be 300 μW (corresponding to a threshold intensity of 7.8 MW/cm2), which is reduced by two orders of magnitude compared with previous reports. The intensity contrast ratio between two output logic states, “1” and “0,” is larger than 27 dB, which is among the highest values reported to date. Our work is the first to experimentally realize on-chip half- and full-adders based on nonlinear plasmonic nanocavities having an ultrasmall feature size, ultralow threshold power, and high intensity contrast ratio simultaneously. This work not only provides a platform for the study of nonlinear optics, but also paves a way to realize ultrahigh-speed signal computing chips.

Interfacial microstructure evolution and shear behavior of Au–12Ge/Ni solder joints during isothermal aging

During isothermal aging, the interfacial microstructure evolution of Au–12Ge/Ni joints as well as its influence on the shear strength and the fracture behavior have been investigated. Results showed that there was a duplex layer of NiGe and Ni5Ge3 intermetallic compounds (IMCs) in the joints after soldering. The most obvious changes in morphology were the transformation from scallop type to planar type microstructure. EPMA data indicated that the growth of the total IMC layer was mainly attributed to the growth of Ni5Ge3 phase. Furthermore, it was found that the grain boundary diffusion was the dominant growth-controlling mechanism of overall IMC layer and the activation energy was 82.23 kJ/mol. In addition, the shear strength decreased continuously with extended aging time. The fracture of as-produced joint was at solder/IMCs interface, showing both ductile and brittle morphology. After the subsequent aging process, a thicker IMC layer was formed at the interface, leading to the movement of the fracture to IMCs region, a transformation of fracture to brittle morphology and a deterioration in shear strength.

Crystal plasticity simulations using nearest neighbor orientation correlation function

A probabilistic scheme is presented for simulating evolution of polycrystalline microstructures during deformation. Microstructure images are described using a compact descriptor called the nearest-neighbor conditional orientation correlation function, defined as the probability density of occurrence of a crystal orientation at one pixel distance from a known orientation. The neighborhood information obtained from this function is used to correct a Taylor-based formulation of crystal plasticity. A finite differencing scheme is developed to capture equilibrium of each orientation in an average sense. The predictions of textures and stresses using our approach are compared against crystal plasticity finite element model of a planar polycrystalline microstructure. We find that the new descriptor is able to capture texture components that are otherwise missed by the Taylor model and provides consistent improvements in the prediction of reorientation and stresses. The simulation speed is significantly faster than crystal plasticity finite element method and is more comparable to that of Taylor models.

Effect of microstructures on the room temperature fracture toughness of NiAl–32Cr–6Mo hypereutectic alloy directionally solidified at different withdrawal rates

The effect of microstructures on the room temperature fracture toughness of NiAl–32Cr–6Mo (at%) hypereutectic alloy was investigated. The solidification microstructure changed from planar eutectic to cellular eutectic and dendritic eutectic with increasing withdrawal rate. The fracture toughness of alloy with planar eutectic microstructure solidified at 10μms−1 was 23.74MPam1/2, and then it dropped to 15.35MPam1/2 when the alloy solidified at rate of 15μms−1. But higher fracture toughness of 22.92MPam1/2 was obtained when the alloy solidified at 25μms−1 and had a perfect cellular microstructure. In this case, the production efficiency can be markedly improved. The fracture surfaces of the NiAl–32Cr–6Mo hypereutectic alloy showed quasi-cleavage fracture mode, some cleavage steps and tearing ridges were observed. The alloys with cellular and dendritic eutectic microstructures exhibited transcellular fracture morphologies; the conically shaped ridges or valleys were observed in each eutectic cell. Owing to the perfect cellular microstructure, the bonding strength of the cell boundary was high; the eutectic cells could largely deform consistently and offer higher resistance of the crack propagation.

Accelerated processing route for KNN based piezoceramics

It is known that the properties of potassium–sodium–niobate (KNN, K0·46Na0·54NbO3) are sensitive to processing and that the most successful way of stabilising and improving material performance is proper doping of KNN. However, this leads to more complex material systems, whose synthesis is very time consuming to assess by conventional processing techniques. On the other hand, known high throughput routes impose a serious interference with conventional processing, resulting in significant differences of the findings, or inaccessibility of certain parameters. In this paper, an accelerated processing route is introduced and compared with conventional mixed oxide processing regarding the density, large signal piezoelectric charge constant, permittivity, loss tangent planar coupling factor, specific resistivity and microstructure. By means of three differently doped KNN based compositions, it is shown that the accelerated processing route yields reproducible results, which are equal or even superior to conventional techniques, while the processing time and the batch costs are significantly reduced.

Integrated all-optical logic discriminators based on plasmonic bandgap engineering

Optical computing uses photons as information carriers, opening up the possibility for ultrahigh-speed and ultrawide-band information processing. Integrated all-optical logic devices are indispensible core components of optical computing systems. However, up to now, little experimental progress has been made in nanoscale all-optical logic discriminators, which have the function of discriminating and encoding incident light signals according to wavelength. Here, we report a strategy to realize a nanoscale all-optical logic discriminator based on plasmonic bandgap engineering in a planar plasmonic microstructure. Light signals falling within different operating wavelength ranges are differentiated and endowed with different logic state encodings. Compared with values previously reported, the operating bandwidth is enlarged by one order of magnitude. Also the SPP light source is integrated with the logic device while retaining its ultracompact size. This opens up a way to construct on-chip all-optical information processors and artificial intelligence systems.

Synthesis of Au-Decorated Tripod-Shaped Te Hybrids for Applications in the Ultrasensitive Detection of Arsenic

Novel Au-decorated Te hybrids with a tripod-shaped planar microstructure were prepared through a two-step hydrothermal process: the synthesis of Te single crystals and the subsequent self-sacrificial reaction of Te template with HAuCl4. Based on the influences of reaction temperature and solvent compositions on the as-obtained microstructures, a plausible mechanism was proposed to account for the formation of the tripod-shaped Te and Au/Te crystals. The as-prepared Au/Te hybrids have the sensitivity of 6.35 μA/ppb in the electrochemical detection of As(III), which represents the highest sensitivity reported in literature. The Au/Te sensor also has a low detection limit of 0.0026 ppb and could work in complex mixtures containing As(III), Cu(II) and other heavy metal ions, exhibiting excellent selectivity on As(III) and Cu(II) ions. The enhanced electrocatalytic property may be attributed to the synergetic interactions between the noble metal and semiconductor and the presence of a large number of active sites on the hybrids surface.

Correlating planar microstructures in shocked zircon from the Vredefort Dome at multiple scales: Crystallographic modeling, external and internal imaging, and EBSD structural analysis

Microstructural and geochronological analysis of shocked zircon has greatly advanced understanding the formation and evolution of impact structures. However, fundamental aspects of shock-produced planar microstructures in zircon remain poorly known, such as their deformation mechanisms, crystallographic orientations, and how planar microstructures visible at the grain scale by scanning electron microscopy correlate to microstructures visible at sub-micrometer scales by transmission electron microscopy and electron backscatter diffraction (EBSD). To unify observations of planar microstructures in zircon made at different scales into a consistent framework, we integrate the results of: (1) three-dimensional crystallographic modeling of planar microstructure orientations, with (2) 360° external prism backscattered electron imaging at the grain scale, and (3) polished section cathodoluminescence and EBSD analysis at the sub-micrometer scale for a suite of detrital shocked zircons eroded from the Vredefort Dome in South Africa. Our combined approach resulted in the documentation of seven planar microstructure orientations that can be correlated from grain to sub-micrometer scales of observation: (010), (100), (112), (11̄2), (1̄12), (1̄1̄2), and (011). All orientations of planar microstructures exhibit minor variations in style, however all are considered to be fractures; no amorphous ZrSiO4 lamellae were identified. We therefore favor the usage of “planar fracture” (PF) over “planar deformation feature” (PDF) for describing the observed planar microstructures in zircon based broadly on the nomenclature developed for shocked quartz. Some {112} PFs visible at the grain scale contain impact microtwins detectable by EBSD, and are the first report of polysynthetic twinning in zircon. The microtwins consist of parallel sets of thin lamellae of zircon oriented 65° about <110> and occur in multiple crosscutting {112} orientations within single grains. Curviplanar fractures and injected melt are additional impact-related microstructures associated with PF formation. Crosscutting relations of shock microstructures reveal the following chronology: (1) Early development of c-axis parallel PFs in (010) and (100) orientations; (2) the development of up to four {112} PFs, including some with microtwins; (3) the development of curviplanar fractures and the injection of impact derived melt; (4) the development of (011) PFs associated with compressional deformation; and (5) grain-scale non-discrete crystal plastic deformation. Experimental constraints for the onset of PFs, together with the absence of reidite, suggest formation conditions from 20 to 40 GPa for all of the planar microstructures described here.