Effect of pickling processes on the microstructure and properties of electroless Ni–P coating on Mg–7.5Li–2Zn–1Y alloy

The electroless plating Ni–P is prepared on the surface of Mg–7.5Li–2Zn–1Y alloys with different pickling processes.The microstructure and properties of Ni–P coating are investigated.The results show that the Ni–P coatings deposited using the different pickling processes have a different high phosphorus content amorphous Ni–P solid solution structure,and the Ni–P coatings exhibit higher hardness.There is higher phosphorus content of Ni–P amorphous coating using 125 g/L Cr O3and 110 ml/L HNO3(w68%)than using 180 g/L Cr O3and 1 g/L KF during pre-treatment,and the coating structure is more compact,and the Ni–P coatings exhibit more excellent adhesion with substrate(Fcup to22 N).The corrosion potential of Ni–P coating is improved and exhibits good corrosion resistance.As a result,Mg-7.5Li-2Zn-1Y alloy is remarkably protected by the Ni–P coating.     

Utility-optimization dynamic subcarrier allocation algorithm for SC-FDMA systems

Two utility-optimization dynamic subcarrier allocation （DSA） algorithms are designed for single carrier frequency division multiple access system （SC-FDMA）. The two proposed algorithms aim to support diverse transmission capacity requirements in wireless networks, which consider both the channel state information （CSI） and the capacity requirements of each user by setting appropriate utility functions. Simulation results show that with considerable lower computational complexity, the first utility-optimization algorithm can meet the system capacity requirements of each user effectively. However, the rate-sum capacity performance is poor. Furthermore, the second proposed utility-opti- mization algorithm can contribute a better trade-off between system rate-sum capacity requirement and the capacity requirements of each user by introducing the signal to noise ratio （SNR） informa- tion to the utility function based on the first utility-optimization algorithm, which can improve the us- er requirements processing capability as well as achieve a better sum-rate capacity.     

Conductive and corrosion behaviors of silver-doped carbon-coated stainless steel as PEMFC bipolar plates

Ni–Cr enrichment on stainless steel SS316L resulting from chemical activation enabled the deposition of carbon by spraying a stable suspension of carbon nanoparticles; trace Ag was deposited in situ to prepare a thin continuous Ag-doped carbon film on a porous carbon-coated SS316L substrate. The corrosion resistance of this film in 0.5 mol·L-1 H₂SO₄ solution containing 5 ppm F- at 80℃ was investigated using polarization tests. The results showed that the surface treatment of the SS316L strongly affected the adhesion of the carbon coating to the stainless steel. Compared to the bare SS316L, the Ag-doped carbon-coated SS316L bipolar plate was remarkably more stable in both the anode and cathode environments of proton exchange membrane fuel cell (PEMFC) and the interface contact resistance between the specimen and Toray 060 carbon paper was reduced from 333.0 mΩ·cm2 to 21.6 mΩ·cm2 at a compaction pressure of 1.2 MPa.     

Effects of Fe content on the microstructure and properties of CuNi10FeMn1 alloy tubes fabricated by HCCM horizontal continuous casting

Heating-cooling combined mold (HCCM) horizontal continuous casting technology developed by our research group was used to produce high axial columnar-grained CuNi10FeMn1 alloy tubes with different Fe contents. The effects of Fe content (1.08wt%–2.01wt%) on the microstructure, segregation, and flushing corrosion resistance in simulated flowing seawater as well as the mechanical properties of the alloy tubes were investigated. The results show that when the Fe content is increased from 1.08wt% to 2.01wt%, the segregation degree of Ni and Fe elements increases, and the segregation coefficient of Ni and Fe elements falls from 0.92 to 0.70 and from 0.92 to 0.63, respectively. With increasing Fe content, the corrosion rate of the alloy decreases initially and then increases. When the Fe content is 1.83wt%, the corrosion rate approaches the minimum and dense, less-defect corrosion films, which contain rich Ni and Fe elements, form on the surface of the alloy; these films effectively protect the α-matrix and reduce the corrosion rate. When the Fe content is increased from 1.08wt% to 2.01wt%, the tensile strength of the alloy tube increases from 204 MPa to 236 MPa, while the elongation to failure changes slightly about 46%, indicating the excellent workability of the CuNi10FeMn1 alloy tubes.     

Fracture behavior and microstructure analysis of Al2O3–MgO–CaO castables for steel-ladle purging plugs

Three different castables based on the Al₂O₃–MgO–CaO system were prepared as steel-ladle purging plug refractories: corundum- based low-cement castable (C-LCC), corundum-spinel-based low-cement castable (C-S-LCC), and corundum-spinel no-cement castable (C-S-NCC) (hydratable alumina (ρ-Al₂O₃) bonded). The fracture behavior at room temperature was tested by the method of “wedge-splitting” on samples pre-fired at different temperatures; the specific fracture energy G′_f and notched tensile strength σ_NT were obtained from these tests. In addition, the Young’s modulus E was measured by the method of resonance frequency of damping analysis (RFDA). The thermal stress resistance parameter R′′′′ calculated using the values of G′_f, σ_NT, and E was used to evaluate the thermal shock resistance of the materials. According to the microstructure analysis results, the sintering effect and the bonding type of the matrix material were different among these three castables, which explains their different fracture behaviors.     

Effect of initial orientation on microstructure and mechanical properties of AZ31 Mg alloy sheets via accumulated extrusion bonding

In this study, effects of initial orientation on microstructure evolution and mechanical properties of AZ31 Mg alloy sheets via accumulated extrusion bonding(AEB) was systematically studied. The samples with RD and TD parallel to extrusion direction(ED) were labeled as RED and TED, respectively. RD and TD pieces alternately stacked was named as RTED. The results revealed that under three-dimensional compressive stress, {10-12} tensile twinning dominated the first stage deformation in container. ...     

Protonated-amino-functionalized bamboo hydrochar for efficient removal of hexavalent chromium and methyl orange

Hydrochar has great potential for wastewater treatment and the functional modification can significantly improve the ability of hydrochar to remove pollutants. Herein, a novel protonated amino-modified bamboo hydrochar(PAHC) was synthesized by the reaction of bamboo hydrochar first with acryloyl chloride, then with amine and finally with hydrochloric acid, and employed to adsorb methyl orange(MO) and Cr(Ⅵ). The PAHC was observed by BET, SEM-EDX, FTIR, elemental analysis, and zeta potential to mo...     

Quaternized chitosan/Pluronic F127 thermosensitive hydrogel with high antibacterial properties for wound dressing

In everyday life, traditional dressings such as band-aid and gauze are used for dealing with small wounds.However, these dressings have shortcomings such as pain caused by tearing, inapplicability to joints, single functionality, and adverse reactions. Therefore, there is a great need for an inexpensive, comfortable, and multifunctional wound dressing. In this study, quaternized chitosan(QCS) with a high degree of substitution(107.84%) was successfully prepared and characterized using ultraviole...     

Impacts of different designed microstructures on creep performance of a Ni-based wrought superalloy

The creep behavior of a novel Ni-based wrought superalloy with varying aging states, classified as large underaged(UA), little UA, and little over-aged(OA) states, was investigated at a temperature higher than the intragrain/grain-boundary iso-strength temperature(750°C/250 MPa). In the samples before creep test, there are spherical γ’precipitates homogeneously dispersed within the γ matrix and carbides precipitated at grain boundaries(GBs). After creep tests, precipitate-free zones(PFZs) appear...     

Erratum to: Electrical conductivity of molten LiF–DyF3–Dy2O3–Cu2O system for Dy–Cu intermediate alloy production

Erratum to:International Journal of Minerals, Metallurgy and Materials Volume 26, Number 6, June 2019, Page 701https://doi.org/10.1007/s12613-019-1775-z The acknowledgements of this article unfortunately contained a mistake. The grant number of the National Natural