粗颗粒乙酸镍的研制

通过改善物料浓度,反应温度,加热温度,降温梯度及搅拌速率来优化生产乙酸镍的工艺条件,研制出颗粒度达到80目以粗的粗颗粒乙酸镍.粗颗粒的乙酸镍由于晶核少,包裹的杂质少,提高了产品的品质；其在生产和使用时,与细颗粒乙酸镍产品相比,有效地减少了粉尘污染.此外粗颗粒的乙酸镍在干燥时也大大节省了甩干和干燥时间,提高了生产效率.     

粒度分布对赤铁矿浮选的影响

以赤铁矿为研究对象,通过浮选试验、扩展的DLVO(EDLVO)理论和凝聚动力学研究了粒度分布(粒径小于18μm的微细粒比例)对赤铁矿浮选的影响.浮选结果表明赤铁矿的浮选回收率与粒度的大小和分布有关,粗粒(粒径大于18μm)赤铁矿的粒度较大时或粒度分布均衡时(微细粒与粗粒含量接近)浮选回收率较高.EDLVO理论计算表明微细粒赤铁矿与粗粒赤铁矿之间存在吸引力,且吸引力的大小与粗粒粒度正相关;凝聚动力学分析表明粒度分布均衡时颗粒间的凝聚速率较大.这是粒度分布对赤铁矿的浮选回收率产生影响的主要原因.     

Grain size distribution of quartz isolated from Chinese loess/paleosol

Grain size distribution of bulk loess-paleosol and quartz chemically extracted from the loess/paleosol shows that mean size of the bulk samples is always finer than that of the quartz. The original aeolian depositions have been modified to various degrees by post-depositional weathering and pedogenic processes. The grain size distribution of the isolated quartz should be close to that of the primary aeolian sediment because the chemical pretreatment excludes secondary produced minerals. Therefore, the grain size of the quartz may be considered to more clearly reflect the variations of winter monsoon intensity.     

Grain size distribution of quartz isolated from Chinese loess1 paleosol

Grain size distribution of bulk loess-paleosol and quartz chemically extracted from the loess/paleosol shows that mean size of the bulk samples is always finer than that of the quartz. The original aeolian depositions have been modified to various degrees by post-depositional weathering and pedogenic processes. The grain size distribution of the isolated quartz should be close to that of the primary aeolian sediment because the chemical pretreatment excludes secondary produced minerals. Therefore, the grain size of the quartz may be considered to more clearly reflect the variations of winter monsoon intensity.     

An integrated view of the chemistry and mineralogy of martian soils

The mineralogical and elemental compositions of the martian soil are indicators of chemical and physical weathering processes. Using data from the Mars Exploration Rovers, we show that bright dust deposits on opposite sides of the planet are part of a global unit and not dominated by the composition of local rocks. Dark soil deposits at both sites have similar basaltic mineralogies, and could reflect either a global component or the general similarity in the compositions of the rocks from which they were derived. Increased levels of bromine are consistent with mobilization of soluble salts by thin films of liquid water, but the presence of olivine in analysed soil samples indicates that the extent of aqueous alteration of soils has been limited. Nickel abundances are enhanced at the immediate surface and indicate that the upper few millimetres of soil could contain up to one per cent meteoritic material.     

可溶性镁合金的制备及其性能

针对传统可溶性压裂球材质存在的缺点,采用铸造法制备性能优异的可溶性镁合金,系统研究了铝含量对可溶性镁合金组织、溶解性能及力学性能的影响.结果表明:可溶性镁合金组织由α-Mg和β-Mg17 Al12相组成,随着铝含量的增多,组织中β-Mg17 Al12相数量增多,呈连续网状分布于α相晶界处,并且α晶粒也变得粗大.可溶性镁合金在氯化钾(KCl)溶液中可自行溶解,且随KCl浓度的升高,溶解速率变大,在质量分数为3％的KCl中溶解性能最佳.随着铝含量的增加,可溶性镁合金的溶解速率变大,室温下溶解速率最高可达7.42 mg·h-1·cm-2.溶解产物粒度分析结果显示,中值粒径D50为38.691μm,溶解产物物相为Mg17 Al12和Mg(OH)2.可溶性镁合金的抗压强度最高可达430 MPa,变形量为3.0％时试样断裂,随着铝含量的增加,可溶性镁合金的塑性降低.     

直流电弧等离子体法制备镍纳米粉

运用直流电弧等离子体法制得镍纳米粉，并利用X射线衍射(XRD)、透射电子显微镜(TEM)和相应选区电子衍射(ED)、BET吸附等测试手段对样品的化学成分、形貌、晶体结构、晶格常数、粒度及其分布、比表面积进行性能表征．结果表明：本法所制得的镍纳米粉的晶格结构与相应的块物质相同，为fcc相结构．平均粒径47nm，粒径20～70nm，比表面积14．23m^2／g，呈规则的球形链状分布，并发现纳米晶体的晶格常数发生膨胀．     

搅拌磨与球磨磨矿对比试验

研究了搅拌磨和球磨磨矿产品的粒度特性及其磨矿过程中的比生产率、能耗情况.结果表明:搅拌磨磨矿产品较为均匀,球磨磨矿产品中微细粒和粗颗粒的质量分数较高;分别采用直线和指数曲线拟合搅拌磨和球磨时不同入磨粒度和比生产率的关系,随着入磨粒度的下降,球磨的比生产率下降较搅拌磨明显;采用Walker等提出的关系式,拟合入磨粒度与能量消耗的关系,搅拌磨的耗能增长速率远小于球磨的增长速率.搅拌磨相对于球磨在细磨和超细磨过程中具有明显的优势.     

不同氧化铝对轻量微孔刚玉骨料结构与性能的影响

以α-Al2O3微粉、工业Al2O3细粉为原料,经过湿磨制料和1 830℃烧结制备了轻量微孔刚玉骨料,研究不同氧化铝原料对轻量微孔刚玉骨料体积密度、气孔率及显微结构的影响。结果表明,在实验工艺条件下,采用工业氧化铝细粉或α-Al2O3微粉作为原料,均可获得体积密度为3.2～3.5g/cm3、显气孔率在5%以下、平均孔径为0.5～1μm的轻量微孔刚玉骨料,其800℃导热系数比普通板状刚玉小25%～42%;相比之下,采用工业Al2O3细粉作为原料时,所制得的骨料晶粒粗大,体积密度较大,闭口气孔在总气孔中所占比率较小,而采用α-Al2O3微粉作为原料时,所制得骨料晶粒细小,体积密度较小,闭口气孔在总气孔中所占比率较大,平均气孔孔径及导热系数亦比采用工业Al2O3细粉作原料时更小。     

典型钢铁企业物能消耗与烟粉尘排放分析

以典型钢铁生产企业为研究对象,基于企业实际生产数据,采用物质流分析法(MFA),构建物质代谢模型.建立了能源、资源利用和污染物排放分析指标,定量描述了钢铁企业的资源能源消耗及烟粉尘排放情况.结果表明:企业层面,高炉-转炉长流程吨钢总资源消耗量为208.6 t,燃料能消耗量占能源消耗总量的93.9%,吨钢烟粉尘排放量为648.08 g,烧结和炼铁工序贡献最大,分别占总排放量的45%和36%.电炉短流程总资源消耗量为1.31 t,电能消耗量占能源消耗总量的96.7%,吨钢烟粉尘排放量67 g.工序层面,烧结、炼焦和炼铁三个主排放工序的排放量分别为222.50 g/t烧结矿、118.20 g/t焦、245.27 g/t铁.据此,提出企业节能减排和产业结构调整的方向性建议,以减少环境压力,实现钢铁企业的可持续发展.     

刨花板生产中不同筛分刨花分开干燥的试验

<正>刨花干燥是刨花板生产的重要工序之一,它不仅影响刨花板的质量,而且影响其成本。 人们对刨花干燥已做过一些研究。Kollmann曾指出:“在同样干燥条件下,干燥过程依赖于木材树种和刨花厚度。”Klamoth所提供的干燥曲线图表明,干燥一开始就能以较大的蒸发水分速率来排除刨花内的水分。Krischer还认为,刨花干燥过程“依刨花中水分蒸发速率可分为二个时期——恒速率期和减速率期。” 刨花干燥开始时,能否以快速率排除水分?刨花的各种筛分物在干燥过程中水分蒸发速率是否有差异?在干燥过程中,干燥介质的温度对各时期刨花内水分的蒸发速率的影响如何? 对上述问题我们进行了试验。实验中所用的刨花原料为芬兰的桦木,刨花为两种:-6+9(筛子目数)和-20+30(表示较小)。为了便于探讨问题,给刨花高含水率,预先把刨花在冷水中浸泡5秒钟,滤水后存放一昼,测出小的刨花含水率为310％左右,大的为190％左右(用称重干燥法测定)。在天平式快速含水率测定仪上干燥(精度为1/1000克),     

Magnetic properties of different grain-sized particles of sediments from the Okinawa Trough and their relationships to sedimentary environment

Multiple magnetic parameters were measured for nine different grain-sized fractions separated from the sediment samples that are representatives of four different sedimentary environments of the Okinawa Trough. Based on the measured results, the contributions of different grain-sized particles to total magnetic susceptibility of bulk sediments, the magnetic mineral assemblage and magnetic domain state as well as their relationships to sedimentary environment were discussed. Our research shows that the magnetic mineral is dominated by magnetite with a small amount of hematite and is primarily in pseudo-single-domain state. That indicates that the different sedimentary environments in the Okinawa Trough have certain correlation in material provenance. The magnetic minerals enrich in different grain-sized particles in response to different sedimentary environments. The contribution of the grain sizes from coarse to fine to coarse and fine to the magnetic susceptibility from the west to the east is in accordance with terrigenous material transportation from continental shelf of the East China Sea to the Okinawa Trough. It also shows difference in magnetic properties as a result of some environmental factors.     

双辊薄带连铸低碳微合金钢的铸态组织

采用双辊薄带连铸技术制备了低碳微合金钢薄带，利用OM，SEM和TEM对铸态凝固组织、室温组织、析出及位错进行观察和分析.结果表明:低碳微合金钢铸带的凝固组织中二次枝晶间距约为12~15μm，相对于传统厚板坯和薄板坯连铸，铸带组织得到了明显细化.铸带的原奥氏体晶粒尺寸比较粗大，约为250~410μm，其组织由魏氏铁素体、珠光体和不规则铁素体组成.铸带组织中存在纳米级TiC析出和短棒状的渗碳体.TiC析出没有被薄带连铸的凝固过程及二次冷却过程明显抑制.铸带组织由于铸轧力及二次冷却速率不均匀导致大量位错的产生.     

Variation of Zr/Rb ratios on the Loess Plateau of Central China during the last 130000 years and its implications for winter monsoon

To find a new index of winter monsoon without effects of chemical weathering and pedogenesis is an important task in loess research. Chemical analysis of five grain size fractions (i.e. >32 μm, 32–20 μm, 20–8 μm, 8–2 μm and <2 μm) show that Zr is enriched in coarser grain size, while Rb is concentrated in finer fractions. An excellent correlation occurs between Zr/Rb ratios and mean grain size in loess units (L₁LL₁ and L₁LL₂) from Huanxian and Xifeng sections, reflecting that Zr/Rb ratios increase when grain size is coarser. Due to immobility of the two elements during the postdepositional process, Zr/Rb ratios can eliminate the effect of weathering and pedogenesis and serve as an excellent proxy on winter monsoon variation. The Zr/Rb ratio curves of the Huanxian, Xifeng and Luochuan sections during the last 130000 years show that the winter monsoon strength was very weak during MIS 3, which corresponded to the intensity during MIS 5.     

雨季广州大气中的硝酸盐粒子

对雨季广州大气中的硝酸盐粒子进行了两年的观察 .粒子被分为两部分 :粗大粒子 (r >1.0 μm )和微小粒子 (r≤ 1.0 μm ) .用离子色谱对粒子总量进行了总体分析 ,用复合薄膜法和X_射线分析法对单个粒子进行了分析 .总体分析结果表明 ,粗大粒子中的NO- 3、Ca2 +和Na+含量比微小粒子中的高 .对单个粒子的分析发现 ,硝酸盐粒子不仅存在于粗大粒子中 ,而且也存在于微小粒子中 ,证明硝酸能凝结在海盐上形成粗大硝酸盐粒子 ,粗大硝酸盐粒子有可能起着最终消除广州大气中硝酸的作用 .     

The building blocks of planets within the 'terrestrial' region of protoplanetary disks

Our Solar System was formed from a cloud of gas and dust. Most of the dust mass is contained in amorphous silicates, yet crystalline silicates are abundant throughout the Solar System, reflecting the thermal and chemical alteration of solids during planet formation. (Even primitive bodies such as comets contain crystalline silicates.) Little is known about the evolution of the dust that forms Earth-like planets. Here we report spatially resolved detections and compositional analyses of these building blocks in the innermost two astronomical units of three proto-planetary disks. We find the dust in these regions to be highly crystallized, more so than any other dust observed in young stars until now. In addition, the outer region of one star has equal amounts of pyroxene and olivine, whereas the inner regions are dominated by olivine. The spectral shape of the inner-disk spectra shows surprising similarity with Solar System comets. Radial-mixing models naturally explain this resemblance as well as the gradient in chemical composition. Our observations imply that silicates crystallize before any terrestrial planets are formed, consistent with the composition of meteorites in the Solar System.     

基于参数化的散料输送机械快速设计系统开发

为了解决散料输送机械的设计及其优化过程中存在的产品设计周期长、方案优化过程慢等问题,开发出一套针对散料输送机械的快速设计系统平台.以某公司斗轮机构的斗子和轮体为例,首先建立了参数化尺寸驱动的设计模型;然后基于参数化的原理利用有限元分析软件建立多目标优化分析模型,实现了产品的快速优化设计,提升了复杂钢结构的设计效率与准确性;最后将参数化设计与参数化分析优化模块进行高度集成,搭建完成快速设计系统平台,用户可通过快速设计系统平台的交互界面输入参数得到所需要的产品.工程实践表明,该快速设计系统对散料输送机械的系列化开发具有较好的应用前景.     

Water-driven structure transformation in nanoparticles at room temperature

The thermodynamic behaviour of small particles differs from that of the bulk material by the free energy term gammaA--the product of the surface (or interfacial) free energy and the surface (or interfacial) area. When the surfaces of polymorphs of the same material possess different interfacial free energies, a change in phase stability can occur with decreasing particle size. Here we describe a nanoparticle system that undergoes structural changes in response to changes in the surface environment rather than particle size. ZnS nanoparticles (average diameter 3 nm) were synthesized in methanol and found to exhibit a reversible structural transformation accompanying methanol desorption, indicating that the particles readily adopt minimum energy structural configurations. The binding of water to the as-formed particles at room temperature leads to a dramatic structural modification, significantly reducing distortions of the surface and interior to generate a structure close to that of sphalerite (tetrahedrally coordinated cubic ZnS). These findings suggest a route for post-synthesis control of nanoparticle structure and the potential use of the nanoparticle structural state as an environmental sensor. Furthermore, the results imply that the structure and reactivity of nanoparticles at planetary surfaces, in interplanetary dust and in the biosphere, will depend on both particle size and the nature of the surrounding molecules.     

轧制方式对镁合金生体腐蚀行为的影响

采用光学显微镜、扫描电镜、浸泡质量损失和拉伸测试等手段研究了轧制方式(常规轧制和一道次高应变速率轧制)对镁合金(纯镁,Mg-4Zn,Mg-4Zn-0.3Ca和ZK60)在Hank’s溶液中腐蚀行为的影响.结果表明:与常规轧制态相比,高应变速率轧制态镁合金在长时间浸泡过程中平均腐蚀速率较低,抗拉强度下降幅度较小,耐腐蚀性能明显提高,可归因于晶粒细化、再结晶程度较高、孪晶较少和残余第二相相对粗大等;轧制态合金中第二相较少且较细小,表现为相对均匀的丝状腐蚀.     

Spatiotemporal variations of Zr/Rb ratio in three last interglacial paleosol profiles across the Chinese Loess Plateau and its implications for climatic interpretation

The ratio of Zirconium to Rubidium （Zr/Rb） is suggested to be a better proxy for the East Asian winter monsoon strength than the widely-used grain size distribution. The rationale for the Zr/Rb proxy relies on the following assumptions： （1） Grain size fractionating characteristics during eolian dust transport should be archived in the Zr/Rb ratio records and this assumption is based on the premise that Zr is preferentially enriched in coarser grain size fraction while Rb tend to be enriched in finer grain size fraction; and （2） post-depositional weathering does not change the Zr/Rb ratio due to the immobility of these two elements. To examine these two assumptions, three last interglacial paleosols （S1） from Dingxi, Tianshui and Lantian, along a NW-SE transect across the Chinese Loess Plateau, were geo- chemically investigated. Our results show that the Rb concentration exhibits an increasing trend along the NW-SE transect both in the paleosol （S1） and the measured portions of the loess units （L1 and L2）, being supportive to the assumption that Rb is enriched in the fine particles. But we also found that Rb loss did occur to some extent in the three profiles, contradicting to the presumption of Rb immobility during pedogenic processes. The Zr concentration exhibits an expected decreasing trend in the measured portions of the loess units and an unexpected increasing trend in the paleosol along the NW-SE transect. Moreover, the ratios of Zirconium to Hafnium （Zr/Hf） show different variation patterns between interglacial and glacial, implying that Zr-bearing minerals and their resident grain size fractions are probably not identical during interglacial and glacial. Thus, the assumption that Zr is enriched in coarse grain size fraction can no longer hold. We conclude that the final Zr/Rb value is not only dependent on grain size sorting processes but also on post-depositional alteration and source prove- nance. Under enhanced chemical weathering, especially when chemical index of alterat