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In this study, severe cracking occurred during an investigation of the direct hot rolling of industrial electrolytic nickel plates. To determine the cause of hot-rolling cracking, the microstructure phase composition was analyzed through the utilization of various techniques, including optical microscopy, scanning electron microscopy, electron backscattering diffraction, transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS) and electron probe micro-analysis. The comparative microstructural analysis took place between specimens heat treated in atmospheric and vacuum environments. The characterization and analysis of the hot-rolled plates considered the crack microstructure and fracture morphology. It was shown that holes appeared along the large angular grain boundaries after annealing at 1100 °C for 8 h. Possible reason: In a high-temperature environment, the decomposition of residual additives in the electrolytic nickel releases oxidizing gases, which oxidizes the grain boundaries. The reaction with carbon diffused into the grain boundaries and produced carbon monoxide gas, which induced holes and severely reduced the grain boundary plasticity. The heat treatment time did not need to be very long for severe grain boundary degradation to occur. After severe cavitation, the electrolytic nickel was severely cracked at grain boundaries cracks due to a shear force, and brittle fractures occurred along grains with very low plasticity. [ABSTRACT FROM AUTHOR]

Direct management and assessment of metal film properties applied to polymer microneedle (MN) biosensors remains difficult due to constraints inherent to their morphology. By simplifying the three-dimensional structure of MNs and adjusting the deposition time, different thicknesses of Au films were deposited on the UV-cured polymer planar and MN substrates. Several properties relevant to the biosensing of the Au films grown on the polymer surfaces were investigated. The results demonstrate the successful deposition of pure and stable Au nanoparticles onto the surface of UV-curable polymer materials. Initially, Au islands formed within the first minute of deposition; however, as the sputtering time extended, these islands transformed into Au nanoparticle films and disappeared. The hydrophilicity of the surface remains unchanged, while the surface resistance of the thin film decreases with increasing thickness, and the adhesion to the substrate decreases as the thickness increases. In short, a sputtering time of 5–6 min results in Au films with a thickness of 100–200 nm, which exhibit exceptional comprehensive biosensing performance. Additionally, MNs made of Au/UV-curable polymers and produced using magnetron sputtering maintain their original shape, enhance their mechanical characteristics, and gain new functionalities. The Au/UV-curable polymer MNs exhibited remarkable electrode performance despite being soaked in a 37 °C PBS solution for 14 days. These discoveries have important implications in terms of decreasing the dependence on valuable metals in MN biosensors, lowering production expenses, and providing guidance for the choice and design of materials for UV-curable polymer MN metallization films. [ABSTRACT FROM AUTHOR]

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The friction behaviors of highly sp3-hybridized carbon films, including ultra-nanocrystalline diamond and diamond-like carbon materials, strongly depend on the atmosphere. However, the roles of the corresponding molecules in the interfacial bonding characteristics remain a subject of debate. By means of density functional theory calculations, this study aims to fill a knowledge gap about the correlation between the evolving contact quality induced by the adsorption of molecules, and the friction behavior of highly sp3-bonded carbons. The results prove that gas–solid adsorption is responsible for the diversity in friction coefficients of ultra-nanocrystalline diamond and diamond-like carbons in different atmospheres. This study emphasizes the role of terminal states in friction coefficients, and demonstrates that electron lubrication is another available strategy for hydrogenated diamond-like carbons to achieve ultra-low friction. This conclusion is validated by the ultra-low friction coefficient (∼0.009) of hydrogenated diamond-like carbons in a dry nitrogen atmosphere. These findings provide atomic scale descriptions of the surface passivation mechanisms for ultra-nanocrystalline diamond and diamond-like carbons, which contribute to our understanding of their macro-scale friction behaviors. [ABSTRACT FROM AUTHOR]

A series of Nb-doped (BiNaK)TiO lead-free piezoelectric ceramics were fabricated by a conventional solid-state reaction method. The X-ray diffraction patterns reveal a pure perovskite structure for all the samples. A giant strain of 0.34% is achieved at 2 mol% Nb-doping concentration, and the corresponding normalized strain $$d_{33}^*$$ reaches 625 pm V, which is one of the best results of the BNT-based ceramics. Complex ac impedance data indicate that only the bulk effect contributes to the resistivity. The compositionally induced disruption of long-range ferroelectric order and relaxor transition contributed to the pinched polarization loops as well as the large electric field-induced strain. The results indicate that appropriate Nb-dopant content can remarkably enhance the strain level of (BiNaK)TiO ceramics, making it a promising candidate for actuator applications. [ABSTRACT FROM AUTHOR]

Highlights: [•] Aluminum ammonium sulfate (NH4Al(SO4)2) power can decomposed out γ-Al2O3 particles in high temperature Al–20%Si alloy melt. [•] In situ γ-Al2O3 particles can refine primary and eutectic Si phases of Al–20%Si alloy. [•] The refinement mechanisms are attributed to heterogeneous nucleation and restrict growth. [ABSTRACT FROM AUTHOR]

Spark plasma sintering (SPS) is an important method of preparation of Ni-Al alloy high performance aircraft material. This paper adopted grey cluster analysis to estimate the Ni-AI alloy aircraft material with different chemical compositions. The cluster properties were judged according to the summary of three grey degrees. The evaluating results can be used for guiding experiment technology and future application in actual production. [ABSTRACT FROM AUTHOR]