基于CAFE法优化易切削钢9SMn28锰、硅、硫含量

应用CAFE法,模拟了不同锰、硅、硫含量对易切削钢9SMn28凝固组织的影响,并通过热力学计算分析了原因,优化了钢中的锰、硅、硫含量,得出结论如下:Mn含量在0.9%～1.3%时,随Mn的增加,柱状晶减小;当Mn含量从0.9%到1.2%时,晶粒逐渐细化。Si含量在0.02%～0.10%时,随Si的增加,柱状晶略有减小;当Si含量从0.02%到0.08%时,晶粒逐渐细化。S含量在0.24%～0.36%时,随S的增加,柱状晶减小,晶粒逐渐细化。因此,从凝固组织方面考虑,易切削钢9SMn28的Mn、Si、S含量应分别为1.2%、0.08%、0.36%。同时,对优化了的锰、硅、硫含量进行模拟,有效的改善了9SMn28的凝固组织。

ICP–AES法测定铬镍不锈钢中锰、铬、镍、硅、磷、铜、钼的含量

目的:利用了电感耦合等离子体原子发射光谱法(ICP-AES)多元素同时测定的优点,建立了测定铬镍不锈钢中锰、铬、镍、硅、磷、铜、钼的含量的分析方法。方法:样品使用盐酸和硝酸混合酸溶液溶解,使用标准样品制作标准曲线,确定了恰当的工作条件和分析参数。结果:各元素的测定量在测试范围内与原子发射强度呈良好的线性关系,线性相关系数不小于0.9992,7种元素的检出限在0.0003%~0.0015%之间。本实验方法应用于铬镍不锈钢标准样品的测定,样品测定值与标准值基本相符,测定值的相对标准偏差在0.044%~1.164%之间(n=5)。结论:本实验方法操作简便、获得结果迅速,且精密度与准确度良好,可满足日常铬镍不锈钢中多种元素含量的检测需要。

ICP–AES法测定铬镍不锈钢中锰、铬、镍、硅、磷、铜、钼的含量

建立电感耦合等离子体原子发射光谱（ICP–AES） 法测定铬镍不锈钢中锰、铬、镍、硅、磷、铜、钼7 种元素含量的方法.试样用盐酸与硝酸混合酸溶液溶解,采用溶解国家标准样品的方法制备校准曲线溶液,确定了元素最佳分析谱线.各元素的含量在其测试范围内与原子发射强度呈良好的线性关系,线性相关系数不小于0.999,7 种元素的检出限在0.000 3%～0.003 0% 之间.该方法应用于铬镍不锈钢标准样品的测定,测定值与认定值相符,测定值的相对标准偏差在0.12%～1.15% 之间（n=8）.应用于铬镍不锈钢样品测定时,加标回收率在90%～110% 之间.该方法操作简便、迅速,可满足日常铬镍不锈钢中多元素含量的检测需要.

X荧光光谱法测定钒渣中的钙、铝、硅、镁、锰、钛、钒、磷元素的含量

利用X射线荧光光谱仪测定钒渣中的钙、铝、硅、镁、锰、钛、钒、磷等主要化学成分的含量.采用自制标样绘制校准曲线,利用光谱干扰校正系数和基体效应校正系数消除光谱干扰和基体效应。试验结果表明:该方法简便快速、有良好的精密度和准确度,各元素相对标准偏差小,能够为生产及时提供可靠数据。

Influence of sodium silicate on manganese electrodeposition in sulfate solution

The influences of sodium silicate on manganese electrodeposition in sulfate solution were investigated. Manganese electrodeposition experiments indicate that a certain amount of sodium silicate can improve cathode current efficiency and initial pH 7.0?8.0 is the optimized pH for high cathode current efficiency. The analyses of scanning electron microscopy (SEM) and X-ray diffraction (XRD) indicate the compact morphology and nanocrystalline structure of electrodeposits. X-ray photoelectron spectrometry (XPS) analysis shows that the elements of Mn, Si and O exist in the deposit. The solution chemistry calculations of sulfate electrolyte and sodium silicate solution indicate that species of Mn2+, MnSO4, Mn(SO4)2?2 , Mn2+, MnSiO3, Mn(NH3)2+, SiO32?and HSiO3? are the main active species during the process of manganese electrodeposition. The reaction trend between Mn2+ and Si-containing ions is confirmed by the thermodynamic analysis. In addition, polarization curve tests confirm that sodium silicate can increase the overpotential of hydrogen evolution reaction, and then indirectly improve the cathode current efficiency.

Combined Application of Si and Mn for Correcting Fe Toxicity to Rice（Oryza sativaL．） on a Red Earth

Based on the fact that Fe toxicity which is usually characterized by leaf oranging and low yield canbe obviously subdued by application of Si or Mn due to counteraction between Fe and Si or Mn. A potexperiment was conducted with four treatments of CK, Si, Mn and Si+Mn to further study the effect ofcombined application of Si and Mn on rice growth on red earths. Water-soluble Si, Fe and Mn were measured,and electron probe was used to study Si, Mn, Fe and Ca in root cross sections. Combined application of Si andMn could increase water-soluble Si and Mn but reduce water-soluble Fe, thus being favorable for correctingFe toxicity. Electron probe study showed obvious differences of Si, Fe, Mn and Ca in rice roots betweenCK and the other three treatments. The combined application of Si and Mn could reduce leaf oranging andimprove rice growth. The Si+Mn treatment had a higher plant height, lower number of oranging leaves anda 25.0% higher rice yield than CK and showed a better effect on rice growth than the treatment of sole Si orMn.

Fe-Si-Mn-Oxyhydroxide Encrustations on Basalts at East Pacific Rise near 13°N:An SEM-EDS Study

Fe-Si-Mn-oxyhydroxide encrustations at the East Pacific Rise （EPR） near 13°N were analyzed using the scanning electron microscope （SEM） with an energy dispersive spectrometer （EDS）. These encrustations are mainly composed of amorphous Fe- Si-Mn-oxyhydroxides forming laminated, spherical, porous aggregates with some biodetritus, anhydrite, nontronite, and feldspar particles. Anhydrite particles and nontronite crystals in the Fe-Si-Mn-oxyhydroxide encrustations imply that the Fe-Si-Mn-oxyhy- droxide may have formed under relatively low- to high-temperature hydrothermal conditions. The Fe-Si-Mn-oxyhydroxide encrusta- tions on pillow basalts are 1-2mm thick. The growth rate of ferromanganese crusts in the survey area suggests that these encrusta- tions are an unlikely result of hydrogenic deposition alone having a hydrothermal and （Fe/Mn ratio up to 7.7 and Fe/（Fe＋Mn＋A1） ratio exceeding 0.78） hydrogenic origin （0.22 Fe/Mn ratio close to the mean value of 0.7 for open-ocean seamount crusts）. The varying Fe/Mn ratios indicate that the Fe-Si-Mn-oxyhydroxide encrustations have formed through several stages of seafloor hydrother- malism. It is suggested that, at the initial formation stage, dense Fe-Si-oxyhydroxides with low Mn content deposit from a relatively reducing hydrothermal fluid, and then the loose Fe-Si-Mn-oxyhydroxides deposit on the Fe-Si-oxyhydroxides. As the oxidation degree of hydrothermal fluid increases and Si-oxide is inhibited, Mn-oxide will precipitate with Fe-oxyhydroxides.

Preparation of sodium manganate from low-grade pyrolusite by alkaline predesilication-fluidized roasting technique

Low concentration alkaline leaching was used for predesilication treatment of low-grade pyrolusite. The effects of initial NaOH concentration, liquid-to-solid ratio, leaching temperature, leaching time and stirring speed on silica leaching rate were investigated and the kinetics of alkaline leaching process was studied. The results show that silica leaching rate reached 91.2% under the conditions of initial NaOH concentration of 20%, liquid-to-solid ratio of 4：1, leaching temperature of 180 ℃, leaching time of 4 h and stirring speed of 300 r/min. Shrinking-core model showed that the leaching process was controlled by the chemical surface reaction with activation energy Ea of 53.31 k J/mol. The fluidized roasting conditions for preparation of sodium manganate were optimized by the orthogonal experiments using the desiliconized residue. The conversion rate of sodium manganate was obtained to be 89.7% under the conditions of silica leaching rate of 91.2%, NaOH/MnO2 mass ratio of 3：1, roasting temperature of 500 ℃ and roasting time of 4 h, and it increased with the increase of silicon leaching rate.

Si,Fe and Mn Distributions in Rice (Oryza saliva L.) Rhizosphere of Red Earths and Paddy Soils

An experiment using rhizobox was conducted to study Si, Fe and Mn distributions in rice rhizosphcre of red earths and paddy soils. It was found that Si, Fe and Mn distributions in rhizosphere of the paddy soils were characterized by a depleted zone around root surface, beyond which the concentrations gradually rose. From lmm layer to 2mm layer the concentrations dropped and then rose again. Whereas Si and Fe in red earths showed no depleted zone but even accumulated zone around root surface. Mn showed an approximately even distribution in each layer and no depletion was found in root surface layers. This indicated that during rice (Oryza sativa L.)plantation, depletion and accumulation of Si, Fe and Mn in rhizosphere were important features of matured red earths by water culture. The distribution changes of Si, Fe and Mn in relation to soil-root interaction are also discussed.

Network structure and its effects on the strength of Fe-C-Si-Mn alloy castings

Fe-C-Si-Mn alloy castings used as blades in hydroelectric generators are studied and found to contain network structures after some heat treatments. Castings after annealing and normalizing were analyzed by microscope and transmission electron microscopy (TEM). The network formed during annealing was proved by TEM to be pearlite with very fine slices, while that formed during normalizing was proved by TEM and micro-hardness to be martensite or bainite. A theoretical analysis together with experimental studies has proved that the pearlite network is caused by carbon content increase in the interdendritic regions to which carbon atoms transfered from dendritic arms due to lower manganese content there during annealing, while the martensite or bainite network results from the higher hardenability of interdendritic regions where manganese content is higher. Experiments reveal that higher heating temperature or longer heating time enlarges the network size due to manganese homogenization. The network structure has a strengthening function like reinforcing rib, and the smaller the network size, the greater its strengthening capability.

Ore petrography of low-grade siliceous manganese ores from the Bonai-Keonjhar belt, Orissa, India: The influence of mineral-fabric on their beneficiation

Low grade siliceous manganese ores from the iron ore group of the Bonai-Keonjhar belt, Orissa, India are found mostly in shear zones. The ore characteristics of siliceous manganese ore samples from three differ- ent mines, viz. the Shankar (Barbil OMC lease hold area), the Sone-Patuli (Patmunda, OMM lease hold area), and the Musaghar (Roida, OMDC lease hold area), were studied. These siliceous manganese ores are of three types, respectively: (i) spongy-granular; (ii) massive-mosaic; and (iii) hard-mylonitized. The spongy-gran- ular type contains granular, saccharoidal quartz and the major manganese mineral present is pyrolusite. The second type contains well crystallized quartz and cryptomelane, while the third has cherty, fine grained quartz (mylonite) along with romanechite. All three ores were subjected to physical beneficiation under similar conditions. Both gravity and magnetic separation techniques were employed. The mineral-fabric of the ores has been correlated to the extent of their beneficiation using these physical techniques. Of these three ores only the spongy-granular type responded well to upgrading. The feed with 22% Mn content could be upgraded to 44% with a 28% yield and a 49% recovery. The good response to beneficiation of the spongy- granular sample could be due to the large euhedral crystals of pyrolusite and the friable nature of the sac- charoidal quartz. This study reveals the influence of mineral-fabric on beneficiation of low grade ore, siliceous Mn ore in particular.

SOL-GEL SYNTHESIS AND LUMINESCENCE OF GREEN LIGHT EMITTING PHOSPHORS ZN_2SIO4/MN^(2+)

Mn^2＋ doped Zn2SiO4 phosphors were synthesized by sol-gel method, and the influence of zinc source, Mn^2＋ dopant concentration and annealing temperature were investigated. Results show that zinc nitrate based precursor with strong green emission intensities is better than zinc acetate based precursor. The intensity of green light emission reaches a peak at 254 nm when the Mn^2＋ dopant concentration is about 5%（ molar percentage）. Structural details of the phosphors were examined through X-ray diffractometry, thermogravimetric and differential thermal analysis. The result indicates that they are both rhombohedral structures, which remain amorphous below 700 ℃ and crystallize completely around 1000 ℃. The luminescent properties of Zn2SiO4/Mn^2＋ phosphors were characterized by excitation and emission spectra.

Synthesis and Crystal Structure of the Polyoxometalatebased Complex [Mn(DMSO)_5H_2O]_2SiMo_(12)O_(40)

A polyoxometalate-based complex [Mn(DMSO)5H2O]2SiMo12O40 has been synthe- sized and it crystallizes in triclinic, space group P with a = 11.863(2), b = 12.750(3), c = 13.255(3) , a = 83.62(3), b = 69.46(3), g = 87.14(3), V = 1865.6(6) 3, Dc = 2.445 g/cm3, Z = 1, ?= 2.660 mm-1, Mr = 2746.56, F(000) = 1328, R = 0.0569, wR = 0.1190 and GOF = 1.125. The results of X-ray crystal analysis and IR spectrum show that there exists strong interaction between the heteropolyanions [SiMo12O40]4- and coordination cations [Mn(DMSO)5H2O]2+ in solid state.

Preparation of MnO_2 and calcium silicate hydrate from electrolytic manganese residue and evaluation of adsorption properties

Electrolytic manganese residue(EMR), a high volume byproduct resulting from the electrolytic manganese industry, was used as a cheap and abundant chemical source for preparing MnO2 and EMR-made calcium silicate hydrate(EMR-CSH). The MnO2 is successfully synthesized from the metal cations extracted from EMR, which can effectively recycle the manganese in the EMR. By the combination of XRD, SEM and EDX analysis, the as-prepared MnO2 is found to exhibit a single-phase with the purity of 90.3%. Furthermore, EMR-CSH is synthesized from EMR via hydrothermal method. Based on the detailed analyses using XRD, FT-IR, FE-SEM, EDX and BET surface area measurement, the product synthesized under the optimum conditions(p H 12.0 and 100 °C) is identified to be a calcium silicate hydrate with a specific surface area of 205 m2/g incorporating the slag-derived metals(Al and Mg) in its structure. The as-synthesized material shows good adsorption properties for removal of Mn2+ and phosphate ions diluted in water, making it a promising candidate for efficient bulk wastewater treatment. This conversion process, which enables us to fabricate two different kinds of valuable materials from EMR at low cost and through convenient preparation steps, is surely beneficial from the viewpoint of the chemical and economical use of EMR.

Thermodynamic description of the Mn-Si-Zn system

The experimental phase equilibria of the Mn-Si-Zn system available in the literature were critically evaluated.Thermodynamic assessment of the Mn-Si-Zn system was then performed in the framework of CALPHAD(CALculation of PHAse Diagram) method on the basis of the experimental data in the literature.The optimal thermodynamic parameters of the ternary system were then obtained,yielding a good agreement with most of the experimental data.The complete liquidus projection and reaction scheme was also presented for the Mn-Si-Zn system.It is noteworthy that a stable closed liquid miscibility gap appears in the computed ternary phase diagrams,even though it is metastable in three boundary binaries.The occurrence of such a closed miscibility gap can be predicted by a criterion considering the general thermodynamic rules and the features of the three constituent binary systems.

Research on residual stress inside Fe-Mn-Si shape memory alloy coating by laser cladding processing

The stainless Fe-Mn-Si shape memory alloy(SMA) coating was prepared on the surface of AISI 304 stainless steel. The principal residual stress measured by the mechanical hole-drilling method indicates that the Fe-Mn-Si SMA cladding specimen possesses a lower residual stress compared with the 304 stainless steel cladding specimen. The mean stress values of the former and the latter on 10-mm-thick substrate are 4.751 MPa and 7.399 MPa, respectively. What's more, their deformation values on 2-mm-thick substrate are about 0° and 15°, respectively. Meanwhile, the variation trend and the value of the residual stress simulated by the ANSYS finite element software consist with experimental results. The X-ray diffraction(XRD) pattern shows ε-martensite exists in Fe-Mn-Si SMA coating, which verifies the mechanism of low residual stress. That's the γ→ε martensite phase transformation, which relaxes the residual stress of the specimen and reduces its deformation in the laser cladding processing.

Mineralogical and micromorphological characteristics of Si-Fe-Mn oxyhydroxides from the PACMANUS hydrothermal field, Eastern Manus Basin

The mineralogical and micromorphological characteristics of Si-Fe-Mn oxyhydroxides from the dacite-hosted PACMANUS hydrothermal field were analyzed.The samples are poorly crystallized Si-Fe-Mn oxyhydroxides with minor birnessite, todorokite, nontronite, goethite, and opal-A.There are some microtextures which are rather like fossil microbes such as the filamentous silica and the hollow pipes.Flakes of nontronite crystals are found either forming a honeycomb texture or distrib- uted on the surface of the hollow pipes.Nontronite is the product precipitated from low-temperature hydrothermal fluids, and microbes may play a role in its formation.Si-Fe-Mn oxyhydroxides have two kinds of nuclei: Si-Mn nuclei and Si nuclei, both enveloped by the similar Si-Fe outer layer, existing in the rod-shaped oxyhydroxide and spheroidal oxyhydroxide, respectively.In the Si-Mn nuclei, the concentration of SiO2 is between 39.32 wt% and 86.31 wt%, and MnO concentration is between 4.97 wt% and 27.01 wt%, but Fe2O3 concentration is very low (0.54 wt%-3.43 wt%).In the Si nucleus the concentration of SiO2 is 90.17 wt%, but concentration of MnO and Fe2O3 are low, with 0.06 wt% and 3.47 wt%, respectively.The formation of the Si-Mn nucleus is closely related to microbes, whereas the Si nucleus is of inorganic origin.

Growth of skyrmionic MnSi nanowires on Si： Critical importance of the SiO2 layer

MnSi in the B20 structure is a prototypical helimagnet that forms a skyrmion lattice, a vortex-like spin texture under applied magnetic field. We have systematically explored the synthesis of single crystal MnSi nanowires via controlled oxide-assisted chemical vapor deposition and observed a characteristic signature of skyrmion magnetic ordering in the MnSi nanowires. The thickness of the SiO2 layer on the Si substrate plays the key role in obtaining a high yield of B20 MnSi skyrmion nanowires. A growth mechanism was proposed that is consistent with the existence of an optimum SiO2 thickness. A growth phase diagram was constructed based on the extensive studies of various growth conditions for various MnSi nanostructures. The persistence of both the helicoidal and skyrmion magnetic ordering in the one-dimensional wires was directly revealed by ac and dc magnetic measurements.