Characterization method of formability properties of zinc alloy coating on a metal substrate

The present invention relates to a method for the characterisation of formability properties of a zinc alloy coating on a metal substrate and a metal substrate comprising a zinc alloy coating. The method for the characterisation of formability properties of a zinc alloy coating on a metal substrate, the zinc alloy coating containing one or more alloying elements selected from the group consisting of Mg, Al, Ni each with a content of at least 0.3 weight % and at most 10 weight %, optionally one or more additional elements selected from the group consisting of Si, Sb, Pb, Ti, Ca, Mn, Sn, La, Ce, Cr, or Bi, wherein the content by weight of each additional element in the metallic coating is less than 0.3 weight %, inevitable impurities, the remainder being zinc, the zinc alloy coating having a microstructure comprising a primary zinc phase and binary eutectic and/or ternary eutectic phases, wherein Electron Backscatter Diffraction (EBSD) is used to determine a crystallographic orientation-dependent strain hardening exponent (n) of the zinc alloy coating microstructure

Interfacial modification by lithiophilic oxide facilitating uniform and thin solid electrolyte interphase towards stable lithium metal anodes

In this work, metal foam current collectors (CCs, i.e. nickel [Ni] and copper [Cu]) were treated by thermal oxidation to create a lithiophilic oxide surface that exhibited enhanced electrochemical performances of lithium anodes such as the cyclic stability of Coulombic efficiency at different current densities for various capacities compared to pristine CCs. The oxidized CCs facilitated much increased diffusivities of ions for lithium growth than pristine CCs. It was found that an inhomogeneous solid electrolyte interphase (SEI) formed on pristine CCs while a uniform SEI formed on oxidized CCs. Uniform lithium (Li) deposition can be achieved on oxidized CCs owing to the lithiophilic oxide surface containing metal nanoparticles and the ionic compound lithium oxide (Li2O) matrix that led to a uniform SEI film and many nucleation sites. In addition, the porous and non-porous composite anodes exhibited different electrochemical performances. The porous composite anodes showed initial lower voltage hysteresis but shorter lifetime with carbonate-based electrolyte than non-porous composite anodes. The porous composite anodes showed better rate performances in full-cell measurements while the non-porous composite anodes displayed better stability. The interfacial modification of porous hosts by lithiated oxides and the effects of porous structure on battery performances can be also useful for designing other electrodes (e.g. sodium [Na], potassium [K], zinc [Zn])

An analytical method to predict and compensate for residual stress-induced deformation in overhanging regions of internal channels fabricated using powder bed fusion

Powder bed fusion (PBF) is ideally suited to build complex and near-net-shaped metallic structures such as conformal cooling channel networks in injection molds. However, warpage occurring due to the residual stresses inherent to this process can lead to shape deviation in the internal channels and needs to be minimized. In this research, a novel analytical model based on the Euler-Bernoulli beam bending theory was developed to estimate the residual stress-induced deformation of internal channels printed horizontally using PBF. The model was used to predict the shape deviation for three different shapes of channel cross sections (circular, elliptical, and diamond-shaped), and showed very good agreement with the experimentally determined shapes of nine different internal channels (three cases per cross-sectional shape). Further, the model predictions were used to compensate for the shape deviation in the design stage, resulting in a reduction in root mean square (RMS) deviation of the circular channel by a factor of 2. The proposed approach is thus expected to be a useful tool to generate design-for-AM guidelines for the additive manufacturing of overhangs and internal channels

Effects of carbon content and argon flow rate on the triboperformance of self-lubricating WS2/a-C sputtered coating

Layered transition metal dichalcogenides (TMD) such as WS2 are materials well-known for their solid lubrication properties [1]. However, the lubricating property degrades through oxidation or moisture and it is also limited by its low hardness and low load-bearing capacity. In contrast amorphous diamond-like carbon (DLC) films are reported to have many features that contribute to excellent tribological characteristics, such as high hardness, anti-wear property with both low friction coefficient and low wear rate[2]. The present research aims at depositing WS2/a-C nanocomposite coatings by magnetron co-sputtering method. The effects of carbon content and argon flow rate on the microstructure and mechanical performance were investigated. The WS2/a-C nanocomposite tribocoating was scrutinized by electron microscopy and mechanical testing. Transmission electron microscopy reveals feathery WS2 platelets, randomly distributed in the amorphous carbon matrix. The nanocomposite coating turns out to be more amorphous-like with increasing carbon content. Nanoindentations tests show that the hardness and elastic modulus of the coating increase with increasing carbon addition while decreasing with a higher argon flow from 10 sccm to 25 sccm. Ball-on-disk tribotests (100Cr6 steel ball as a counterpart) show that the coefficient of friction can be as low as 0.017 in a dry environment (5% relative humidity). It reaches 0.15 in a high humidity surrounding and remains stable within 20000 sliding cycles

Design and fabrication of conformal cooling channels in molds:Review and progress updates

Conformal cooling (CC) channels are a series of cooling channels that are equidistant from the mold cavity surfaces. CC systems show great promise to substitute conventional straight-drilled cooling systems as the former can provide more uniform and efficient cooling effects and thus improve the production quality and efficiency significantly. Although the design and manufacturing of CC systems are getting increasing attention, a comprehensive and systematic classification, comparison, and evaluation are still missing. The design, manufacturing, and applications of CC channels are reviewed and evaluated systematically and comprehensively in this review paper. To achieve a uniform and rapid cooling, some key design parameters of CC channels related to shape, size, and location of the channel have to be calculated and chosen carefully taking into account the cooling performance, mechanical strength, and coolant pressure drop. CC layouts are classified into eight types. The basic type, more complex types, and hybrid straight-drilled-CC molds are suitable for simply-shaped parts, complex-shaped parts, and locally complex parts, respectively. By using CC channels, the cycle time can be reduced up to 70%, and the shape deviations can be improved significantly. Epoxy casting and L-PBF show the best applicability to Al-epoxy molds and metal molds, respectively, because of the high forming flexibility and fidelity. Meanwhile, LPD has an exclusive advantage to fabricate multi-materials molds although it cannot print overhang regions directly. Hybrid L-PBF/CNC milling pointed out the future direction for the fabrication of high dimensional-accuracy CC molds, although there is still a long way to reduce the cost and raise efficiency. CC molds are expected to substitute straight-drilled cooling molds in the future, as it can significantly improve part quality, raise production rate and reduce production cost. In addition to this, the use of CC channels can be expanded to some advanced products that require high-performance self-cooling, such as gas turbine engines, photoinjectors and gears, improving working conditions and extending lifetime