Laboratory investigation of carbonated BOF slag used as partial replacement of natural aggregate in cement mortars

Direct mineral carbonation produces a material rich in carbonates and with reduced quantities of free oxides. The aim of this work was to show that such materials can be used in the construction domain. Basic Oxygen Furnace (BOF) slag from the steelmaking process has been traditionally seen as unfit for bounded applications due to its propensity to swelling, resulting from hydration of its high free lime content. Here, BOF slag was crushed to suitable particle sizes, carbonated in an aqueous solution of carbonic acid, and utilized to replace 50% of natural sand aggregate in cement mortars. The mechanical and chemical properties of these mortars were compared to mortars containing non-carbonated slags, and a standard cement mortar as a reference. Tests were conducted to determine mortar paste consistency and soundness, and cured mortar compressive strength and leaching tendencies. The results showed a satisfactory performance for all considered aspects (comparable with the reference) of the mortar sample containing 37.5 wt% (1.5 in 4 parts solids) carbonated BOF slag of <0.5 mm particle size.     

铸钢件粘冷铁机制分析及其防止措施

针对结构复杂、壁厚不均铸钢件粘冷铁的问题,简要介绍了冷铁的作用,分析了外冷铁被铸件熔接的原理,研究了铸钢件表面粘冷铁的影响因素.通过采取工艺设计时校核冷铁质量,去除回用冷铁表面氧化层等措施,以改善冷铁的激冷能力,从而有效防止铸钢件粘冷铁,达到降低消耗、节约成本的目的.     

机床立柱类铸件质量改进及方法研究

针对消失模负压铸造生产立柱类产品存在的皮透、塌箱、铁瘤等缺陷，分析其原因并提出有效可行的预防措施。主要从浇注系统设计、振动参数、浇注负压度等方面综合考虑，降低立柱类废品率，获得优良精美的铸件产品。     

Tailoring the performance of graphene-based supercapacitors using topological defects: A theoretical assessment

Graphene-based materials have been proposed as promising electrodes for electric double layer capacitors. Recently, it has been found that one of the limitations of graphene electrodes is the finite quantum capacitance at low applied voltage. In this work, we investigate the impact of having point-like topological defects in graphene on the electronic structure and quantum capacitance. Our results clearly show that the presence of defects, such as Stone Wales, di-vacancies, and di-interstitials, can substantially enhance the quantum capacitance when compared to pristine graphene, which is found to be due to defect-induced quasi-localized states near the Fermi level. In addition, the charging behavior tends to be asymmetric around the neutrality point. We also discuss the possibility of tuning the electronic structure and capacitance through mixtures of these defects. Our findings suggest that graphene-based electrodes with topological defects may demonstrate noteworthy capacitance but should be carefully selected for use as either the positive or negative electrode.     

银川某桥梁泵送商品混凝土塑性裂缝成因与防治

通过对银川某桥梁结构特点、工程环境条件、混凝土构成、施工工艺和裂缝特征分析,探讨了泵送商品混凝土塑性裂缝成因,有针对性的提出了调整混凝土配合比、养护和二次振捣等防治措施。工程实践表明,该措施经济、有效。     

求解约束优化问题的自适应人工蜂群算法

针对约束优化问题，提出一种自适应人工蜂群算法。算法采用反学习初始化方法使初始种群均匀分布于搜索空间。为了平衡搜索过程中可行个体和不可行个体的数量，算法使用自适应选择策略。在跟随蜂阶段，采用最优引导搜索方程来增强算法的开采能力。通过对13个标准测试问题进行实验并与其他算法比较，发现自适应人工蜂群算法具有较强的寻优能力和较好的稳定性。     

Microstructure characterization of W-Ni-Fe heavy alloys with optimized metallographic preparation method

Tungsten heavy alloys (WHA) have been widely adopted in many engineering applications due to their excellent physicochemical properties. Microstructure characterization is a very powerful method ranging from testing materials properties to detecting material failures and defects. However, the microstructure of WHA was not well characterized with the sample prepared by conventional method of etching with strong acids, bases or oxidant after polishing for the coarse surface. To solve the problem, the exact characterization of W-Ni-Fe heavy alloys microstructure was conducted using the sample prepared by optimized polishing method. A series of experiments were conducted to find the suitable polishing conditions including polishing pad, abrasive slurry and slurry pH. The results show that a smooth and clear microstructure sample was obtained by polishing with alkaline colloidal silica and IC polishing pad, which contained few defects compared with that obtained by conventional method of etching after polishing. The microstructure of W-Ni-Fe heavy alloys was analyzed by XRD, EDS tests and EPMA detection. The slipping phenomenon was observed in nanoindentation test using the prepared sample for the first time and the mechanism of satisfactory microstructure sample preparation was illustrated.     

Study on the cold rolling deformation behavior of polycrystalline tungsten

Tungsten is paid special attention due to its superior properties, especially in nuclear field. Meanwhile it is suitable for texture simulation investigation of BCC metals and alloys as it's near elastically isotropic. This study investigates the cold rolling deformation texture of polycrystalline tungsten using RS model, in which the stress and strain consistence is realized simultaneously. The texture evolution and effects of deformation parameters, including external as well as internal reaction stress, strain and activation of different slip, on texture during rolling are discussed by comparing the simulated results and reported experimental results in literatures. The results show that, the cold rolling deformation texture could be simulated statistically based on RS model. The accumulation of each reaction stress is different. The up-limit of reaction stress σ'₁₂ is found to be medium, meaning that σ'₁₂ exerts important effect on texture evolution. Much lower accumulation level of σ'₁₃ as well σ'₂₃ is displayed, each of which within certain range contributes to the increase of different γ-fiber texture components. The effect of σ'₂₂ can't be ignored during rolling, especially in the case of obtaining {111}<110> texture. Regarding the deformation textures of tungsten rolled to true strains of −1.7 and −2.91, {001}<110> texture is strengthened with the increasing strain and becomes dominant, implying the easier activation of {112}<111> slip systems; γ-fiber texture is weakened at higher strain, and the formation of {111}<112> texture shows significant effect of surface shear stress σ₁₃, which is due to the nonnegligible surface friction when rolling at high temperature.     

Highly active and durable FexCuyNi1-x-y/FeOOH/NiOOH/CuO complex oxides for oxygen evolution reaction in alkaline media

Oxygen evolution reaction (OER) catalyzed by Ru/Ir-free electrocatalysts is pivotal for preparing oxygen in efficient way, yet our understanding of the relationship between microphysical properties and OER performance is still insufficient. Here we report on 41 kinds of Fe_xCu_yNi_1-x-y/FeOOH/NiOOH/CuO complexes (FCN-x) to investigate the Cu and Fe induced electronic perturbation and what it brings to OER performance. As result, the activity mapping of FCN-x shows an optimal composition of 1:2:7 (FCN-7) showing a comparable overpotential potential of 170.3 mV, Tafel slop of 75.9 mV dec^?1 and durability of 24 h (～29% activity loss) to that of mainstream Ru/Ir-free catalysts. Such enhancement could be attributed to the role of alloying contribution of Fe/Cu, electronic perturbation and surface modification of surface oxides. Additionally, the incompletely oxidized Fe_xCu_yNi_1-x-y not only provide a platform for electron conduction, but also work as a sacrificial material to forming fresh oxides to maintain the content of surface oxides, which is a key driver of the excellent durability of FCN-7. This synthetic strategy may give an effective way to design and screen Ru/Ir-free OER catalysts.     

Mild oxidative degradation of spent auricularia auricular substrate and molecular composition of carboxylic acids in the resulting soluble portion

Spent auricularia auricular substrate(SAAS) was oxidatively degraded with aqueous hydrogen peroxide(AHPO)/acetic anhydride(AAH) to produce carboxylic acids(CAs) under mild conditions. The results show that up to 53.6% of the organic matter in SAAS was converted to the soluble species(SSs). In total 122 CAs were detected in the SSs by the analysis with a gas chromatograph/mass spectrometer, which can be classified into 29 group components, mainly being aliphatic acids and along with small amount of aromatic acids. Among the aliphatic acids, normal alkanedioic acids are the most abundant. The detected aromatic acids include benzoic acids,phthalic acids, trimellitic acids, pyromellitic acids, and their derivatives. The synergistic oxidation and the released ·OH, CH_3COO·, and HOO· induced by AHPO/AAH play crucial roles in oxidatively degrading SAAS.