Improvement in oxidation resistance of Cantor alloy through microstructure tailoring

A method of improving the oxidation resistance of Cantor alloy through microstructure tailoring was revealed.Samples with distinctive microstructures were achieved by different annealing treatments on the cold-rolled Cantor alloy.Oxidation test was then carried out on the various annealed samples at 800°C for 24 h in air.The oxidation behavior was evaluated in terms of oxidation rate,surface and cross-section microstructure characterization.Although stratified oxide layers including outer Mn_(2)O_(3) and inner Cr_(2)O_(3) were observed in all the annealed samples,the thickness of Mn_(2)O_(3) and Cr_(2)O_(3) layers was different.Also,the samples exhibited different oxidation rates.The results indicate that the oxidation resistance of various annealed samples is closely related with grain size as well as twin density.

Facile synthesis of W-Mo bimetallic oxides with high adsorption properties from secondary resources

A simple solvothermal method was used to obtain W-Mo bimetallic oxides from W-Mo alloy scrap,and pure metal powders were also used as the raw materials to simulate scrap.The products had a sea urchin-like structure with abundant oxygen vacancies and the products prepared at low temperatures forms a sosoloid resembling orthorhombic W_(0.4)Mo_(0.6)O_(3).The WMo bimetallic oxide prepared at the reaction temperature of 120℃exhibited excellent selective adsorption performance for methylene blue(MB),which the adsorption rate of MB reached 99%in 12 min and the adsorption rate reached 90%after6 adsorption cycles.When the W-Mo molar ratio is 1:3,the maximum adsorption capacity of sample for MB can reach1148 mg·g^(-1).The adsorption process followed the Langmuir and pseudo-second-order models,which is surface-controlled monolayer adsorption.The experimental results show the feasibility of preparing W-Mo bimetal oxide products from pure materials and scrap.The process is simple and effective,which offered a potential approach for secondary resource recycling and reusing.

‘‘Complexation–precipitation'' metal separation method system and its application in secondary resources

Recovery processes of secondary resources usually encounter problems because of the diverse com- positions of wastes. To enhance the applicability of tradi- tional hydrometallurgical process toward secondary resources, the adjustment of components is necessary. In traditional hydrometallurgical separation, precipitation and complexation are extensively used. However, their com- bination as a specific metal separation method has not yet been studied in detail. This approach is very promising for solving problems caused by changeable components during recycling processes of secondary resources. This paper reviews the effects of precipitation and complexation in metal separation processes, and a metal separation method system of ＂complexation-precipitation＂ developed to adjust the components of secondary resources is introduced.

Regulation of morphology and visible light-driven photocatalysis of WO_(3)nanostructures by changing pH

The controlled preparation of hexagonal tungsten trioxide(h-WO_(3))nanostructures was achieved by adjusting the pH of the precursor solution.The effect of the pH on the morphology,elemental composition,and photocatalytic performance of the samples was characterized via X-ray diffraction(XRD),scanning electron microscopy,energy dispersive X-ray spectroscopy,and Raman spectroscopy.Ultraviolet-visible(UV-Vis)spectra were used to evaluate the absorbance and the photocatalytic performance of methylene blue.Photoluminescence(PL),electrochemical impedance spectroscopy,photocurrent response and Brunauer-Emmett-Teller(BET)were used to study the optical properties,electrical performance,and specific surface area of the WO_(3)-nanostructures,respectively.The results indicate that the WO_(3) nanorods prepared at pH=1.0 exhibit the highest photocatalytic performance(87.4%in 1 h),whereas the WO_(3) nanoblocks prepared at p H=3.0 show the lowest.The photocatalytic performance of the one dimensional(1 D)-nanorods can be attributed to their high specific surface area and charge transfer ability.The h-WO_(3) nanostructures were synthesized via a simple method and without a capping agent.They show an excellent photocatalytic performance,which is promising for their application in environment purification.

Comprehensive recovery of W,V,and Ti from spent selective reduction catalysts

In this study,spent WO_(3)/V_(2)O_(5)-TiO_(2) catalysts used for selective catalytic reduction were treated by a hydrometallurgical process to comprehensively recover valuable metallic elements,such as W,V,and Ti.Al and Si impurities were preferentially removed by selective micro wave-assisted alkali leaching.W and V were leached by enhanced high-pressure leaching with efficiencies estimated at 95% and 81%.The leaching of W and V followed the nuclear shrinkage model controlled by the combination of product layer diffusion and interfacial chemical reaction.A synergistic extraction was applied to separate W and V using an extractant mixture of di-(2-ethylhexyl)phosphoric acid P204 and the primary amine N1923.The extraction efficiencies of V and W reached 86.5% and 6.3%,respectively,with a separation coefficient(V/W) of 95.30.The product was precipitated after extraction to yield ammonium paratung state(APT) and NH_(4)VO_(3).The TiO_(2)catalyst carrier residue meets commercial specifications for reuse.This comprehensive recovery process with the characteristics of high-pressure leaching and synergistic extraction realizes the resourceful utilization of the spent catalysts.