Alginate is an elastic hydrocolloid that is irreversible and has many uses in dentistry. Alginates are used to duplicate casts, create study models, and create impressions of edentulous and partially ...edentulous arches. Alginates are commonly used in dentistry because they have many important properties such hydrophilicity, the capacity to capture finer details, elastic recovery, and affordability. Despite being the most widely used impression substance, alginate has significant built-in drawbacks. Alginates include low-density tiny filler particles, which can appear as dust and can lead to respiratory issues when inhaled. Furthermore, because of the separation and imbibitions, they are extremely dimensionally unstable. The failure of alginates to stick to non- perforated trays, their low viscosity, which causes a gag reflex in certain patients, and they are being unable to determine the proper consistency to load. To overcome their flaws, conventional alginates' composition underwent a number of changes. This paper examined a number of recent developments in alginate impression materials and their functionality.
Fast tool servo diamond turning is conventionally a spiral path-based process widely used to efficiently fabricate non-rotationally symmetric surfaces with ultra-fine accuracy. However, the technique ...is naturally restricted by the demanding bandwidth and resolution requirements, which are directly related to the complexity and size of the machining surface. Moreover, non-smooth trajectories required for machining complex lens array with discontinuities, due to overlapping sharp edges, induce vibrations causing the surface quality to deteriorate, and adding additional barriers to using this conventional technique in broader applications. In this paper, a new diamond machining approach is proposed to address its inherent drawbacks. Using the new method, complex lens array consisting of arbitrary lenslet shapes could be fabricated in an extendable way without the typical limitations. Theoretical investigations of the unique cutting kinematics, motion determination, servo synchronization and compensation will be carried out. To predict the machined surface topography, the surface generation mechanism with consideration of both the kinematic tool/workpiece interaction and elastic recovery of materials is presented. The experimental fabrication of hexagonal micro-sphere lens array, micro-freeform lens array, as well as seamlessly stitched sinusoidal surface with quadrupled areas was highly consistent and aligned with the theoretical predictions, thus demonstrating the effectiveness of the new approach and its potential for broader applications.
•An innovative diamond machining approach is proposed to enable the extendable fabrication of complex lens array.•Theoretical investigations of the unique cutting kinematics and surface generation mechanism are conducted.•Servo synchronization and compensation method are proposed and validated.•The presented approach is verified by fabrication of micro-freeform lens array and stitching machining of sinusoidal surface.
Electronic fabrics necessitate both electrical conductivity and, like any textile, elastic recovery. Achieving both requirements on the scale of a single fiber remains an unmet need. Here, two ...approaches for achieving conductive fibers (107 S m−1) reaching 50% elongation while maintaining minimal change in resistance (<0.5%) in embedded metallic electrodes are introduced. The first approach involves inducing a buckling instability in a metal microwire within a cavity of a thermally drawn elastomer fiber. The second approach relies on twisting an elastomer fiber to yield helical metal electrodes embedded in a stretchable yarn. The scalability of both approaches is illustrated in apparatuses for continuous buckling and twisting that yield tens of meters of elastic conducting fibers. Through experimental and analytical methods, it is elucidated how geometric parameters, such as buckling pre‐strain and helical angle, as well as materials choice, control not only the fiber's elasticity but also its Young's modulus. Links between mechanical and electrical properties are exposed. The resulting fibers are used to construct elastic fabrics that contain diodes, by weaving and knitting, thus demonstrating the scalable fabrication of conformable and stretchable antennas that support optical data transmission.
Elasticity is introduced in thermally drawn fibers by modifying the pathway of metallic electrodes to either a buckled or helical configuration. The electrodes maintain minimal change in resistance within the elastic strain regime defined by geometric and material properties. Integration of light‐emitting diodes connected by stretchable electrodes within fibers yields stretchable and conformable fabric optical antennas for high‐bandwidth data transmission.
Additive manufacturing (AM) has a substantial capability to produce superior and divergent properties of titanium alloys for biomedical implants, unlike the existing conventional technologies. This ...work investigated the mechanical properties and microstructure evolution of a β-type Ti-35Nb-2Ta-3Zr alloy prepared by selective laser sintering (SLS) process. The superelastic properties of the resultant specimen were characterized by cyclic loading-unloading tensile testing to evaluate the effect of SLS-process on the β-type Ti alloy specimen. The zigzag and V-shaped formation of {112} β twins, coexisting with stress-induced ω-formation, were observed by the transmission electron microscopy (TEM). The formation of Type I twin martensite along with β-structure is attributed to superelastic recovery and elastic recovery of SLS-produced specimen. High resolution TEM (HRTEM) observation was used to investigate the transition between β and ω phases. Thin layers of ω-formation in weak interfacial stress regions along with the longitudinal twin boundaries were also analyzed. The orientation relationship between ω-structure and parent β-phase involves an overlapping of ω-phase, observed along with longitudinal β-matrix and β-twins. Moreover, dislocation tangles and dislocation pile-ups form along with twin martensite, stress-induced ω-phase, and β-phase.
•β-type Ti-35Nb-2Ta-3Zr alloy specimen was prepared by a selective laser sintering.•The zigzag and V-shaped formation of {112} β twins, coexisting with stress-induced ω-formation were observed.•Thin layers of ω-formation in weak interfacial stress regions along with the longitudinal twin boundaries were analyzed.
Monocrystalline 6H-silicon carbide is a promising material for advanced components and devices; but is also a difficult-to-machine material due to its hardness, brittleness and structural anisotropy. ...With the aid of large-scale molecular dynamics simulations, this paper comprehensively studied the structural anisotropy effect on the nanoscratching of 6H–SiC. Six typical combinations of scratching plane and direction were selected, namely, (0001)<112‾0>, (0001)<11‾00>, (112‾0)<11‾00>, (112‾0) , (11‾00) and (11‾00)<112‾0>. It was found that the scratching-induced deformation morphology, activated dislocations and scratching forces varied significantly under different combinations of scratching conditions due to the strong anisotropy effect of the material. By evaluating the actual depth of cut, elastic recovery, surface roughness and maximum subsurface damage depth, basal plane (0001) along <11‾00> direction was identified as the best combination for conducting nanoscratching on 6H–SiC. Corresponding high-resolution TEM results show that the mechanism revealed by the MD analysis reflects the true deformation of the material.
•Deformation mechanism of 6H-SiC during nanoscratching is revealed by both MD simulation and TEM experiments.•Effects of structural anisotropy on deformation mechanisms of 6H-SiC during nanoscratching are thoroughly investigated.•A schematic model of nanomachining process has been established.•The best combination of crystalline plane and direction for conducting nanomachining of 6H-SiC is identified.
To distinguish the strengthening effect of multilayer graphene (MLG) on the copper matrix from the intrinsic strengthening effect of copper grain boundary (GB), the nanoindentation behavior in the ...Cu/MLG interface boundary (IB) region is investigated and further compared with those in the copper GB region and pure copper grain interior (GI) regions. The indentation displacement recovery ratio, elastic work ratio, and indentation hardness in the Cu/MLG IB regions are significantly enhanced as compared with those in the copper GB region and copper GI regions. The strengthening effect in the Cu/MLG IB regions can be attributed to the elastic recovery behavior during the unloading period induced by the MLG, which is further confirmed in both the experimental and simulated indentation topography evolutions. In addition, gradient strengthening effect is revealed from the gradual increase in the indentation displacement recovery ratio, elastic work ratio, and indentation hardness with gradual decreasing distance from the MLG in the Cu/MLG IB regions. The findings in this paper can be utilized to precisely enhance the mechanical performance of copper matrix composite materials by tailoring the interfacial microstructure and property.
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•Elastic recovery strengthening is found in Cu/multilayer graphene (MLG) interfaces.•Gradient strengthening mechanism is proposed and confirmed in Cu/MLG interfaces.•The findings are useful for enhancing mechanical performance of Cu-MLG composite.
The effect of roll temperature from 60 to 120°C on the crystalline structure and properties of oriented polypropylene (PP) cast films and the stretched microporous membrane was studied. It was found ...that the long period, the thickness of the crystalline and amorphous phase increase with the increasing roll temperature. And the regularity of the lamellar structure also improves with the increasing roll temperature. In comparison, the lamellae lateral dimension is nearly unchanged at 50 nm. The orientation of the lamellar structure slightly decreases from 0.81 to 0.76 with increasing roll temperature. The increase of the long period and the improvement of the regularity of the lamellar structure lead to the increase of the elastic recovery value of PP cast film. The corresponding microporous membrane also shows a smaller thickness of lamellar clusters, larger pores, better air permeability and better thermal shrinkage resistance. The higher roll temperature is beneficial to the perfection of the lamellar structure, obtaining the higher‐performance microporous membrane.
The SAXS calculation results of PP cast films prepared under different roll temperatures.
By using molecular dynamics simulations, the nanoimprinting process was performed to evaluate the mechanical properties and elastic recovery of the CuAgAu metallic glasses. The influences of cooling ...rate, stamp velocity, temperature, and percentage of the Cu-Ag-Au elements were considered in detail. By changing the imprint conditions, the mechanical responses of the nanocrystalline CuAgAu metallic glasses were mentioned and analyzed. Some important mechanical factors such as imprint force, shear strain, shear transformation zones, the fraction of atoms with high shear strain, and elastic recovery ratio were significantly influenced by changing the simulated conditions and deeply discussed.
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