| 1. |
- Wu, Zhongbin, et al.
(author)
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High-Performance Hybrid White Organic Light-Emitting Diodes with Superior Efficiency/Color Rendering Index/Color Stability and Low Efficiency Roll-Off Based on a Blue Thermally Activated Delayed Fluorescent Emitter
- 2016
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In: Advanced Functional Materials. - : Wiley. - 1616-301X .- 1616-3028. ; 26:19, s. 3306-3313
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Journal article (peer-reviewed)abstract
- Thermally activated delayed fluorescence (TADF)-based white organic light-emitting diodes (WOLEDs) are highly attractive because the TADF emitters provide a promising alternative route to harvest triplet excitons. One of the major challenges is to achieve superior efficiency/color rendering index/color stability and low efficiency roll-off simultaneously. In this paper, high-performance hybrid WOLEDs are demonstrated by employing an efficient blue TADF emitter combined with red and green phosphorescent emitters. The resulting WOLED shows the maximum external quantum efficiency, current efficiency, and power efficiency of 23.0%, 51.0 cd A(-1), and 51.7 lm W-1, respectively. Moreover, the device exhibits extremely stable electroluminescence spectra with a high color rendering index of 89 and Commission Internationale de L'Eclairage coordinates of (0.438, 0.438) at the practical brightness of 1000 cd m(-2). The achievement of these excellent performances is systematically investigated by versatile experimental and theoretical evidences, from which it is concluded that the utilization of a blue-green-red cascade energy transfer structure and the precise manipulation of charges and excitons are the key points. It can be anticipated that this work might be a starting point for further research towards high-performance hybrid WOLEDs.
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| 2. |
- He, Qinglong, et al.
(author)
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Additive manufacturing of dense zirconia ceramics by fused deposition modeling via screw extrusion
- 2021
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In: Journal of the European Ceramic Society. - : Elsevier BV. - 0955-2219 .- 1873-619X. ; 41:1, s. 1033-1040
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Journal article (peer-reviewed)abstract
- A fused deposition modeling(FDM)system via screw extrusion suitable for feeding granular feedstocks with high solid loading was developed. Key parameters included aspect ratio of the screw, the compression ratio and pitch etc. In order to get constant extruded mass flow and wire diameter a processing window was determined by optimizing the barrel temperature, the nozzle diameter and the screwing speed. Microstructural characterization coupled with flexural strength measurement revealed that a higher printing temperature was beneficial to the inter layer bonding. The sintered zirconia ceramic samples with 99% of theoretical density of the 3 mol% yttria stabilized tetragonal zirconia polycrystal (3Y-TZP) and flexural strength of 890 +/- 60 MPa was obtained. A set of zirconia ceramic parts with complex geometries and controllable dimensional accuracy was also successfully prepared for demonstrating the potential of the technique.
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| 3. |
- Hu, Xianfeng, et al.
(author)
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Carbothermic reduction of synthetic chromite with/without the addition of iron powder
- 2016
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In: ISIJ International. - : Iron and Steel Institute of Japan. - 0915-1559 .- 1347-5460. ; 56:12, s. 2147-2155
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Journal article (peer-reviewed)abstract
- Carbothermic reduction of chromite is an important industrial process for extracting chromium from the chromite. To have a better understanding of the effect of iron on the carbothermic reduction of chromite, the reduction of synthetic chromite (FeCr2O4) by graphite with/without the addition of iron powder was investigated in this paper by Thermogravimetric Analysis (TGA) in argon atmosphere. The fractional reduced samples were examined by SEM/EDS and XRD analysis, and the reduction process was thermodynamically and kinetically evaluated. The experimental results show that the iron powder addition enhances the reduction of FeCr2O4 and this effect increases when increased amounts of iron powder are added. This phenomenon is attributed to the in situ dissolution of chromium into the iron and mixed carbide (Cr,Fe)7C3, which can decrease the activity of the nascent chromium formed by the reduction of the FeCr2O4. The experimental results indicate that the reduction of FeCr2O4 with up to 80 wt.% iron powder addition is likely to be a single-step process and the kinetic analysis suggests that the reduction reaction is likely to be either (a) chemical reaction at the surface of FeCr2O4 or (b) diffusional dissolution of the product (FeCr2) into the iron/alloy particles or the mixed control of (a) and (b).
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| 4. |
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| 5. |
- Hu, Xianfeng, et al.
(author)
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Direct Alloying Steel with Chromium by Briquettes Made from Chromite Ore, Mill Scale, and Petroleum Coke
- 2017
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In: Steel Research International. - : Wiley-VCH Verlag. - 1611-3683 .- 1869-344X. ; 88:5
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Journal article (peer-reviewed)abstract
- In this work, the effectiveness of using briquettes made from chromite ore, mill scale, and petroleum coke for direct chromium alloying is tested by induction furnace trials carried out in three different scales. The experimental results show that steel scrap can be alloyed with chromium by the chromite ore in the briquettes and the Cr yield from the chromite ore increases with the increase in mill scale addition to the briquettes: the more mill scale is added to the briquettes, the lower the mass ratio of Cr to (Cr + Fe) would be, leading to a higher Cr yield from the chromite ore. Specifically, the maximum Cr yield from the chromite ore is 99.9% when the mass ratio of Cr to (Cr + Fe) in the briquettes is 0.05, and being 93.0% when the ratio is 0.10. However, when the ratio of Cr to (Cr + Fe) in the briquettes reaches 0.20, the maximum Cr yield is only 67.1%. The reduction of chromite ore under the present experimental conditions is promoted by a solid-state reduction mechanism.
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| 6. |
- Hu, Xianfeng
(author)
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Studies on Carbothermic Reduction of Chromite in the Presence of FeOx
- 2016
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Doctoral thesis (other academic/artistic)abstract
- Direct chromium alloying by chromite ore is a promising technology for producing Crcontainingsteels, as the ferrochrome production process and the chromium alloying processare integrated into a single step, which has the potential of saving energy and raw materials.In this work Thermogravimetric Analysis experiments and induction furnace experiments (upto 80-kg scale) have been carried out to investigate the carbothermic reduction process ofchromite in the presence of FeOx (iron, mill scale or magnetite). The aims are to investigatethe effect of FeOx on the carbothermic reduction of chromite and to explore the potential ofdirectly alloying steel with chromium by the designed alloying precursor ‘chromite ore +FeOx + carbonaceous material’.The results from the Thermogravimetric Analysis experiments show that FeOx can enhancethe carbothermic reduction of chromite and the enhancing effect increases when increasedamounts of FeOx are added to the chromite. The enhancing effect is attributed to the presenceof added metallic iron or the metallic iron reduced from mill scale or magnetite, which candecrease the activity of chromium by having chromium dissolve in the iron in situ. The resultsfrom the induction furnace experiments show that the steel can be directly alloyed withchromium by using the designed alloying precursor ‘chromite ore + mill scale + petroleumcoke’ and the chromium yield from chromite ore increases when increased amounts of millscale are added to the alloying precursor.The designed alloying precursor, on one hand, can be potentially used to directly alloy steelwith chromium in the Electric Arc Furnace steelmaking process and, on the other hand, can bepotentially used to produce Cr pre-alloyed iron powder or Cr pre-alloyed Direct Reduced Ironby the solid-state reduction process. The proposed applications have the potential to improvethe raw materials efficiency and energy efficiency.
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| 7. |
- Hu, Xianfeng, et al.
(author)
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Thermal Analysis Study on the Carbothermic Reduction of Chromite Ore with the Addition of Mill Scale
- 2016
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In: Steel Research International. - : Wiley-VCH Verlag. - 1611-3683 .- 1869-344X. ; 87:5, s. 562-570
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Journal article (peer-reviewed)abstract
- This paper presents a fundamental study on the carbothermic reduction of chromite ore with the addition of mill scale, which forms the basis for designing an alloying precursor, "chromite ore + mill scale + carbon," for direct chromium alloying. The reduction of chromite ore by petroleum coke with or without the addition of mill scale is investigated by Thermogravimetric Analysis (TGA) under non-isothermal conditions (from room temperature to 1823 K) in the argon atmosphere; the fractional reduced samples were characterized by SEM/EDS and XRD analyses. The experimental results show that the mill scale in the alloying mixture is reduced to high active iron first and disseminated around the chromite ore particles; the reduction of chromite ore is enhanced with the addition of mill scale especially at temperatures higher than 1623 K, and the enhancing effect increased with increasing mill scale addition. The enhancing effect is attributed to the presence of molten Fe-C alloy in the vicinity of chromite ore, which can decrease the thermodynamic activity of chromium by having chromium in situ dissolve into the melt. In this paper, the effect of mill scale addition on the reduction of chromite ore is investigated on the samples with three different amounts of mill scale addition (78 wt%, 38 wt%, and 0 for the samples #1b, #2b, and #3b, respectively) by thermogravimetric technique. The fractional reduced samples are characterized by SEM/EDS and XRD analyses. The mechanism of mill scale addition on the reduction of chromite ore is discussed and the industrial implications of the experimental results are also presented.
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| 8. |
- Hu, Xianfeng, et al.
(author)
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Thermogravimetric study on carbothermic reduction of chromite ore under non-isothermal conditions
- 2015
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In: Ironmaking & steelmaking. - 0301-9233 .- 1743-2812. ; 42:6, s. 409-416
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Journal article (peer-reviewed)abstract
- In this paper, the reduction of chromite ore by coke was investigated by means of thermogravimetric analysis under non-isothermal conditions (from room temperature to 1823 K). The fractional reduced samples were examined by SEM/EDS and X-ray diffraction analyses. The experimental results showed that the reduction of iron in the chromite ore started before that of chromium in the ore, and the reduction of chromium and iron in the ore overlapped to some degree. Chromium iron carbide (Cr,Fe)7C3, was found to be the intermediate phase during the reduction, and a chromium gradient was found in the spinel phase of the fractional reduced sample at 1673 K. A four-stage reduction process was proposed: one stage involving the reduction of iron in the chromite ore and three stages involving the reduction of chromium in the ore. The activity aspects of component FeCr2O4 and component MgCr2O4 in the chromite ore were considered. The difficulty in the reduction of the chromite ore is attributed to the fact that, as the reduction proceeds, the activity of the component MgCr2O4 in the fractional reduced ore will decrease to a very low level, which makes further reduction very difficult.
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| 9. |
- Huang, Yajun, et al.
(author)
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Flame-retardant polyvinyl alcohol/cellulose nanofibers hybrid carbon aerogel by freeze drying with ultra-low phosphorus
- 2019
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In: Applied Surface Science. - : Elsevier BV. - 0169-4332. ; 497
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Journal article (peer-reviewed)abstract
- Polyvinyl alcohol/cellulose nanofibers hybrid aerogel was prepared under freeze drying method. To improve the aerogels' anti-combustion performance, 0.8 wt% microencapsulated ammonium polyphosphate (MCAPP) was loaded as the flame retardant. Aerogels with extremely low density (~0.06 g/cm3) and excellent mechanical performance (Young's modulus: 1.045 MPa) can be obtained. The resulted aerogel also exhibit considerable thermal insulation ability (thermal conductivity: ~0.04 W/m·K). Experimental results indicate that the value of limiting oxygen index increases from 19.5% to 37.5% when loading 0.8 wt% MCAPP. Accordingly, the aerogels' peak heat release rate decreased significantly from 222.44 to 107.84 kW/m2. The char residue rises when introducing MCAPP and the char's integrity improves a lot after combustion. The fire performance index and fire growth index increases and falls respectively, indicating improved anti-combustion performance. X-ray photoelectron spectroscopy results show C[dbnd]O bonds would be increased for the esterification of phosphoric acid from MCAPP. In addition, the production of carbonate can be prohibited while combustion when loading MCAPP.
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| 10. |
- Jiang, L., et al.
(author)
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Experimental investigation on BOF slag oxidation in air
- 2019
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In: Ironmaking & steelmaking. - : Taylor and Francis Ltd.. - 0301-9233 .- 1743-2812. ; 46:8, s. 747-754
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Journal article (peer-reviewed)abstract
- Basic oxygen furnace (BOF) slag contains a significant amount of iron-containing species, which is considered to be iron resources and therefore need to be recovered. In this work, the oxidation behaviour of BOF slag under air (at selected oxidation temperatures and holding time) was investigated to explore the potential of transforming non-magnetic wustite in the BOF slag into magnetic spinel, which may subsequently be recovered by magnetic separation. The experimental results show that the iron-containing spices in the BOF slag can be oxidised into magnetic spinel phases in the investigated temperature range of 1000–1150°C and thereafter be recovered by magnetic separation. The formation of these phases is closely related to the oxidation temperatures and holding time: a higher oxidation temperature and longer holding time lead to a larger amount of formed magnetic species; however, the amount of formed magnetic species decreases at elevated temperature (>1050°C) and with extended holding time (>40 min).
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| 11. |
- Peng, Shanchi, et al.
(author)
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Global Standard Stratotype-Section and Point (GSSP) for the Base of the Jiangshanian Stage (Cambrian: Furongian) at Duibian, Jiangshan, Zhejiang, Southeast China
- 2012
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In: Episodes. - 0705-3797. ; 35:4, s. 462-477
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Journal article (peer-reviewed)abstract
- The International Commission on Stratigraphy and the IUGS Executive Committee have recently approved a Global Standard Stratotype-section and Point (GSSP) defining the base of the second stage of the Furongian Series, Cambrian System. This stage is named the Jiangshanian Stage, after Jiangshan City, western Zhejiang Province, China, where the GSSP is located. The GSSP is exposed in a natural outcrop near Duibian Village. It is defined at the base of a limestone (wackestone) layer 108.12 m above the base of the Huayansi Formation in the Duibian B section, coinciding with the first appearance of the cosmopolitan agnostoid trilobite Agnostotes orientalis (base of the A. orientalis Zone). The GSSP is at a position of 28 degrees 48.977'N latitude and 118 degrees 36.887 'E longitude. Secondary global markers at or near the base of the stage include the first appearance of the cosmopolitan polymerid trilobite Irvingella angustilimbata, which coincides with the FAD of the primary marker in the stratotype section, and near the end of a large positive carbon isotopic excursion (SPICE excursion). Faunal turnovers close to the base of the Jiangshanian Stage have been recognized as being at the base of the Iverian Stage in Australia, the Gonggrian Stage in Korea, and the Agnostotes orientalis Irvingella perfecta Zone in Siberia, and near the base of the Aksayan Stage in Kazakhstan, the Sunwaptan Stage in Laurentia, and the Parabolina brevispina Zone in Baltica.
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| 12. |
- Wu, Zhongbin, et al.
(author)
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Achieving Extreme Utilization of Excitons by an Efficient Sandwich-Type Emissive Layer Architecture for Reduced Efficiency Roll-Off and Improved Operational Stability in Organic Light-Emitting Diodes
- 2016
-
In: ACS Applied Materials and Interfaces. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; 8:5, s. 3150-3159
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Journal article (peer-reviewed)abstract
- It has been demonstrated that the efficiency roll-off is generally caused by the accumulation of excitons or charge carriers, which is intimately related to the emissive layer (EML) architecture in organic light-emitting diodes (OLEDs). In this article, an efficient sandwich-type EML structure with a mixed-host EML sandwiched between two single-host EMLs was designed to eliminate this accumulation, thus simultaneously achieving high efficiency, low efficiency roll-off and good operational stability in the resulting OLEDs. The devices show excellent electroluminescence performances, realizing a maximum external quantum efficiency (EQE) of 24.6% with a maximum power efficiency of 105.6 lm W-1 and a maximum current efficiency of 93.5 cd A(-1). At the high brightness of 5 000 cd m(-2), they still remain as high as 23.3%, 71.1 lm W-1, and 88.3 cd A(-1), respectively. And, the device'lifetime is up to 2000 h at initial luminance of 1000 cd m(-2), which is significantly higher than that of compared devices with conventional EML structures. The improvement mechanism is systematically studied by the dependence of the exciton distribution in EML and the exciton quenching processes. It can be seen that the utilization of the efficient sandwich-type EML broadens the recombination zone width, thus greatly reducing the exciton quenching and increasing the probability of the exciton recombination. It is believed that the design concept, provides a new avenue for us to achieve high-performance OLEDs.
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| 13. |
- Xie, Hehan, et al.
(author)
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3D gel printing of alumina ceramics followed by efficient multi-step liquid desiccant drying
- 2021
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In: Journal of the European Ceramic Society. - : Elsevier BV. - 0955-2219 .- 1873-619X. ; 41:13, s. 6634-6640
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Journal article (peer-reviewed)abstract
- Dense alumina ceramics were additively manufactured efficiently through a 3D gel printing process. Hydroxyethyl cellulose (HEC) was applied to ensure the printability and rigid of the gel made from boehmite. A multi-step liquid desiccant drying method was implemented to improve the drying efficiency. The results showed that the solid loading and HEC addition were two useful parameters for adjusting the rheology properties of the gel to make it suitable for 3D printing. With polyethylene glycol(PEG) added as liquid desiccants, the printed bodies with section size of 10 mm could be dried within 26 h during which the deformation and crack formation was avoided despite a high linear shrinkage of 45 % was encountered. The successful preparation of dense monolithic alumna ceramics parts with an average grain size of 1 μm, 99 % of the theoretical density and a flexural strength of 380 ± 45 MPa indicated the potential of this process.
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