Improving the luminescence properties and powder morphologies of red-emitting Sr0.8Ca0.19AlSiN3:0.01Eu2+ phosphors for high CRIs white LEDs by adding fluxes

Red-emitting Sr_0.8Ca_0.19AlSiN₃:0.01Eu²⁺ phosphor with halide fluxes for use in the production of white light-emitting diodes (white LEDs) with high-colour rendering indices (CRIs) was prepared through the high-temperature solid-state method. Fluoride (NaF, SrF₂, BaF₂, CaF₂, AlF₃·3H₂O and CeF₃), chloride (NH₄Cl, BaCl₂, MgCl₂, NaCl and LiCl) and composite fluxes (NaF + SrF₂, SrF₂+NH₄Cl and NaF + NH₄Cl) were applied in the phosphors. NaF, SrF₂, NH₄Cl and NaF + SrF₂ fluxes had prominent effects on the characteristics of Sr_0.8Ca_0.19AlSiN₃:0.01Eu²⁺ phosphors. Sr_0.8Ca_0.19AlSiN₃:0.01Eu²⁺ phosphors with various powder morphologies can be obtained through the addition of fluxes, which are conducive for phosphor formation. The powder morphologies of phosphors incorporated with NaF + SrF₂ were preferable to those of powders incorporated with other fluxes. This result indicated that the incorporation of NaF + SrF₂ into Sr_0.8Ca_0.19AlSiN₃:0.01Eu²⁺ yielded phosphors with high luminescent intensity and quantum efficiency, excellent thermal stability, narrow full widths at half-maximum (FWHM, 75.2 nm), uniform rod-like morphologies with large particle sizes (D₅₀ = 16.99 μm) and good particle dispersion. White LEDs with high CRIs were obtained by combining prepared phosphors (NaF + SrF₂ additive) with the commercial green-emitting phosphors Y₃(Al,Ga)₅O₁₂:Ce³⁺ and (Sr,Ba)₂SiO₄:Eu²⁺. White LEDs with Y₃(Al,Ga)₅O₁₂:Ce³⁺ and (Sr,Ba)₂SiO₄:Eu²⁺ phosphors had correlated colour temperatures (CCTs) of 3064 and 3023 K, respectively, and CRIs of 81.8 and 92.4, respectively. Therefore, NaF + SrF₂ can be used as a favourable flux for the production of Sr_0.8Ca_0.19AlSiN₃:0.01Eu²⁺.     

现代炼铁工艺及低碳发展方向分析

分析了现代高炉炼铁和非高炉炼铁(直接还原、熔融还原)工艺特点和发展现状,从多个方面比较现有生产条件下各工艺的优缺点。从能源结构、生产规模及工艺成熟度阐述高炉炼铁在当前仍是国内主流工艺,并结合当前国内外低碳发展趋势和政策要求,提出高炉工艺降低碳耗的措施,明确了以“短流程”替代“长流程”和以新能源替代碳素冶金的发展方向,以最终实现“零碳炼铁”。结合现有的国际上的能源结构调整方向,指出了氢冶金的发展方向。     

Alloy design via additive manufacturing: Advantages,challenges, applications and perspectives

Additive manufacturing (AM) has rapidly changed both large- and small-scale production environments across many industries. By re-envisioning parts from the ground up, not limited to the challenges presented by traditional manufacturing techniques, researchers and engineers have developed new design strategies to solve large-scale materials and design problems worldwide. This is particularly true in the world of alloy design, where new metallic materials have historically been developed through tedious processes and procedures based primarily on casting methodologies. With the onset of directed energy deposition (DED) and powder bed fusion (PBF)-based AM, new alloys can be innovated and evaluated rapidly at a lower cost and considerably shorter lead time than has ever been achieved. This article details the advantages, challenges, applications, and perspectives of alloy design using primarily laser-based AM. It is envisioned that researchers in industry and academia can utilize this work to design new alloys leveraging metallic AM processes for various current and future applications.     

氢的大规模制备及在钢铁行业的应用和展望

中国钢铁产量占世界总产量的一半以上,随着全球“碳达峰”“碳中和”的推进,钢铁行业面临着巨大的低碳发展挑战。氢能被认为是一种低碳能源,“以氢代碳”是实现源头降碳和流程低碳转型的重要途径之一。重点介绍氢气基本性质、制备来源与碳排放的关系,探讨煤制氢、天然气制氢、甲醇制氢和电解水制氢4种主流大规模制氢路线的技术特性、发展现状、制备成本和发展方向,结合钢铁行业的用氢特点,对氢在氢冶金和燃料替代方面的应用前景进行分析展望,提出中国钢铁行业通过实施氢能利用逐步实现低碳转型的发展路径。     

Phase equilibria and dielectric properties of Bi3+(5/2)xMg2−xNb3–(3/2)xO14−x cubic pyrochlores

Subsolidus pyrochlores with the proposed formula, Bi_3+(5/2)xMg_2−xNb_3−(3/2)xO_14−x (0.14≤x≤0.22) were successfully synthesised at the firing temperature of 1025 °C using conventional solid-state reaction. The excess Bi³⁺ charge was offset by removal of relative proportion of Mg²⁺ and Nb⁵⁺ together with creation of oxygen non-stoichiometry in order to preserve electroneutrality of the system. These samples were crystallised in cubic structure with space group of Fd3m, No. 227 and their refined lattice parameters were in the range of 10.5706 (3)–10.5797 (7) Å. The surface morphologies of the samples as confirmed by scanning electron microscopy analysis were of irregular shaped grains while their crystallite sizes of ~30–85 nm were calculated using the Scherrer equation and the Williamson–Hall method. No thermal event was discernable indicating these pyrochlores were thermally stable within a studied temperature range of ~30–1000 °C. The recorded dielectric constants of Bi_3+(5/2)xMg_2−xNb_3−(3/2)xO_14−x (0.14≤x≤0.22) subsolidus pyrochlores were generally above ~160 and their dielectric losses were in the order of 10⁻⁴–10⁻³ at the frequency of 1 MHz and temperature of ~30 °C. Meanwhile, these ceramic samples also exhibited negative temperature coefficient of relative permittivity between −528 and −742 ppm/°C in the temperature range of ~30–300 °C.     

Powder coating of veneered particle board surfaces by hot pressing

The powder coating of veneered particle boards by the sequence electrostatic powder application – powder curing via hot pressing is studied in order to create high gloss surfaces. To obtain an appealing aspect, veneer sheets were glued by heat and pressure on top of particle boards and the resulting surfaces were used as carrier substrates for powder coat finishing. Prior to the powder coating, the veneered particle board surfaces were pre-treated by sanding to obtain good uniformity and the boards were stored in a climate chamber at controlled temperature and humidity conditions to adjust an appropriate electrical surface resistance. Characterization of surface texture was done by 3D microscopy. The surface electrical resistance was measured for the six veneers before and after their application on the particle board surface. A transparent powder top-coat was applied electrostatically onto the veneered particle board surface. Curing of the powder was done using a heated press at 130 °C for 8 min and a smooth, glossy coating was obtained on the veneered surfaces. By applying different amounts of powder the coating thickness could be varied and the optimum amount of powder was determined for each veneer type.     

含钌废催化剂回收钌的技术综述

从废钌催化剂中回收钌对于钌资源缺乏的我国具有特殊意义。基于文献和国内相关专利的分析,对氧化蒸馏法、熔融还原沉淀法、离子交换法、吸附法、捕集法、萃取法以及其他回收钌的方法进行了综述分析。不同方法各有其优缺点,其中成熟和应用最广的是氧化蒸馏法,选择性吸附法和萃取法具有选择性高、回收率高、污染小,是有发展前景的技术。     

银氧化锡合金废料电解综合回收工艺研究

采用直流电解法和化学法回收银氧化锡(AgSnO2)合金废料中的银和锡。优化得到的电解银工艺参数为:槽电压1.5~3.0 V,电解周期为24 h,电解液中Ag⁺浓度为150~260 g/L,HNO3浓度为15~20 g/L,同极距120~140 mm,极板排布为六阴极五阳极间隔交替排列。一个周期银氧化锡废料电解银直收率接近95%,主体纯银粉在阴极析出。富含氧化锡的阳极泥和残极用硝酸浸出少量残余银,不溶渣还原熔炼回收锡,硝酸浸出的含银溶液中加入氢氧化钠调节pH值到10,沉淀得氧化银,500℃焙烧得到单质银。废料中的银和锡均得到有效回收。全流程银的回收率不低于99%。     

Removal of pharmaceutical and personal care products (PPCPs) pollutants from water by novel TiO2–Coconut Shell Powder (TCNSP) composite

Photocatlytic removal of three pharmaceutical and personal care products pollutants using novel TiO₂–Coconut Shell Powder (TCNSP) composite was investigated. The photocatalytic degradation rate of PPCPs generally increased with increasing light intensity and dissolved oxygen concentration. The degradation rate decreased with increasing initial concentration of PPCPs. The PPCPs concentration decreased substantially under irradiation of UVC when used in conjunction with the TCNSP composite. A number of composite/radiation types and intensities were tested. The concentration rate decrease trend was as: UVC/TCNSP > UVA/TCNSP > UVC > UVA. Under the UVC/TCNP combination, 99% removal was achieved compared to 30% for TiO₂.