纳米硅化铁的高压研究

采用同步辐射能散X射线衍射技术和金刚石地顶砧高压装置，对硅化铁纳米微粉进行了原位高压X光衍射实验。在27．1－29．5GPa的压力范围内出现了两条的衍射峰，对该实验现象进行了讨论。

铁负载酸活化蒙脱石制备硅/硅化铁纳米复合材料及其储锂性能

纳米硅的储锂容量高,被认为是最有应用前景的新一代锂电负极材料。然而纳米硅的体积膨胀效应和低电导性不利于其实际应用。将天然蒙脱石酸活化和铁负载改性,再经过镁热还原反应,得到了原位复合的硅/硅化铁纳米复合材料。硅化铁具有良好的导电性和机械稳定性,可显著提升硅负极的循环稳定性和倍率性能。在1 A/g的电流密度下循环500圈后,硅/硅化铁纳米复合材料的比容量高达781 m A·h/g,容量保持率为77%。该方法为制备高性能硅基负极材料提供了新思路。

Si衬底上生长的铁硅化合物结构和取向分析

采用分子束外延法分别在650-920℃的Si(110)和920℃的Si(111)衬底表面生长出铁的硅化物纳米结构,并主要分析了920℃高温下纳米结构的形貌、组成相及其与Si衬底的取向关系.扫描隧道显微镜(STM)研究表明,920℃高温下,Si(110)衬底上生长的铁硅化合物完全以纳米线的形式存在,且其尺寸远大于650℃低温下外延生长的纳米线尺寸;Si(111)衬底上生长出三维岛和薄膜两种形貌的铁硅化合物,其中三维岛具有金属特性且直径约300 nm、高约155 nm,薄膜厚度约2 nm.电子背散射衍射研究表明920℃高温下Si(110)衬底上生长的纳米线仅以β-FeSi2的形式存在,且β-FeSi2相与衬底之间存在唯一的取向关系:β-FeSi2(101)//Si(11 1);β-FeSi2[010]//Si[110];Si(111)衬底上生长的三维岛由六方晶系的Fe2Si相组成,Fe2Si属于164空间群,晶胞常数为a=0.405 nm,c=0.509 nm;与衬底之间的取向关系为Fe2Si(001)∥Si(111)和Fe2Si[1 20]//Si[112].

硼化球墨铸铁中硼化物层的断裂韧性

本文研究了硼化球墨铸铁中硼化物的断裂韧性。渗硼是在硼砂、硼酸和硅化铁组成的盐浴中进行的，其热处理工艺是在常压下，加热温度在850—950℃之间，时间为2—8小时。通过X—my衍射、扫描电子显微镜以及光学显微镜等方法验证了球墨铸铁中形成的硼化物(如FeB，Fe2B)。试验结果表明，渗硼时间越长，所形成的硼化物层也越厚，硼化物层截面的光学显微镜观察表明硼化物呈枝晶状。硼化物层显微硬度和断裂韧性可用压痕法来测定。球墨铸铁中形成硼化层的维氏显微硬度在1160-2140HV0.1之间，其断裂韧性在2．19—4．47MPa√m之间，硼化层的硬度和断裂韧性与渗硼时间及温度有关。

Fe_3Si基合金板材的制备技术

在既有的研究工作基础上，给出了更为合适的锻造、轧制等工艺参数和工艺方法．利用普通的锻造和轧制设备，成功制备了良好的约 １．５ ｍｍ厚的 Ｆｅ３Ｓｉ基合金薄板，制备过程中典型的微观组织变化如下：铸态组织的晶粒较大且很不均匀；锻造组织为通过再结晶而形成的晶粒较细且均匀的等轴状组织；轧态组织为纤维组织．

β-FeSi_2热电材料的性能优化及测试方法

本文讨论了β－ＦｅＳｉ２热电材料的微观组织结构特征、合金成分、掺杂和晶粒细化对β－ＦｅＳｉ２热电性能的影响，并给出了根据Ｈａｒｍ ａｎ 方法自制的材料热电性能测量装置的原理与测量方法。

βFeSi_2的高压研究

对 β FeSi2 晶体进行了原位X射线衍射高压研究。利用同步辐射X射线衍射原位研究了 β FeSi2 的高压相演化 ,发现压力在 4 3GPa时出现相变 ,在 2 5 8GPa时相变完成。指标化结果表明 :经高压处理后得到的产物具有四方结构 ,其晶格常数为 :a =b =1 0 0 4 9nm ,c =0 3394nm。

Mn,Co添加Fe_(1-x)M_xSi_2烧结体的β相转移和稳定性研究

In this paper, p type Fe 1- x Mn x Si 2( x =0—0 12) and n type Fe 1-y Co y Si 2( y =0—0 12) were synthesized by means of ceramic technology. The influence of additive amounts of Mn and Co, and heat treatment on the amounts of β phase formed were studied. Experimental results indicate that addition of Mn and Co could inhibit the amounts and velocity of phase formation. High relative density( D r) of p type Fe 1- x Mnx Si 2 and n type Fe 1-y Co y Si 2 causes excellent corrosion resistance and heat resistance which are beneficial for manufacture of thermoelectric components.

离子束外延β-FeSi_2/Si薄膜的电子能谱研究和表征

用电子能谱分析方法对低能离子束外延（IBE）生长的β－FeSi2进行了详细研究，并对其电子能谱进行了表征．实测出XPS价带谱与有关理论计算结果相符，用XPS价带谱来表征β-FeSi2比光电子峰更为清晰、可取．同时，对样品纵向分析表明界面处存在有较厚的过渡层．根据分析结果对低能IBE生长机理进行了探讨．经研究认为：Fe，Si通过空位机制进行的增强互扩散，在高温下生长出与St晶格相匹配的β－FeSi2．

Reaction behavior of ferric oxide in system Fe_2O_3-SiO_2-Al_2O_3 during reductive sintering process

Pure compounds and kaolin were employed to investigate the reaction behavior of ferric oxide in thetrinarysystem Fe2O3?SiO2?Al2O3 during reductive sintering process. The thermodynamic analyses and reductive sintering experimental results show that ferrous oxide generated from the reduction of ferric oxide by carbon can react with silicon dioxide and aluminum oxide to form ferrous silicate and hercynite at 1173 K, respectively. In the trinary system Fe2O3?SiO2?Al2O3, ferrous oxide obtained from ferric oxide reduction preferentially reacts with aluminum oxide to form hercynite, and the reaction of ferrous oxide with silicon dioxide occurs only when there is surplus ferrous oxide after the exhaustion of aluminum oxide. When sintering temperature rises to 1473 K, hercynite further reacts with silicon dioxide to form mullite and ferrous oxide. Results presented in this work may throw a new light upon the separation of alumina and silica present in Al/Fe-bearing materials with low mass ratio of alumina to silica in alumina production.

退火温度对磁控溅射制备的β-FeSi2薄膜的影响

采用磁控溅射的方法，在高真空条件下，沉积金属Fe到Si（100）衬底上，然后通过真空退火炉在不同温度条件下对样品进行热处理，直接形成了β-FeSi2薄膜．采用X射线衍射仪（XRD）对样品进行了晶体结构分析，利用卢瑟福背散射（RBS）对Fe-Si化合物的形成过程中的Fe原子和Si原子的互扩散机理进行了研究，利用扫描电镜（SEM）对样品表面的显微结构进行表征，结果表明，在900℃条件下退火能够得到质量很好的β-FeSi2薄膜，超过这一温度β相将开始向α相转化，到1000℃，β-FeSi2全部转化为α-FeSi2。

FeSi掺杂的MnNiO热敏材料的研究

本文采用ＦｅＳｉ掺杂的办法，在材料常数Ｂ值改变较小的情况下．明显的提高了热敏材料的电阻率，为获得具有较大实用价值的热敏电阻提供了非常有效的方法．通过分析表明：ＦｅＳｉ和ＭｎＮｉＯ发生反应，有利于尖晶石结构的形成．复阻抗分析和Ｘ－ＲＡＹ分析均表明：纯ＭｎＮｉＯ为复相结构（包括ＮｉＯ和Ｍｎ３Ｏ４），而ＦｅＳｉ掺杂的ＭｎＮｉＯ为尖晶石固溶体其中Ｓｉ以ＳｉＯ２的形式存在晶界中．因此，复阻抗分析为材料的相成分分析提供了新的手段．

Microstructures and magnetic properties of [SiO_2/FePt]_5/Ag thin films

[SiO2/FePt]5/Ag thin films were deposited by RF magnetron sputtering on the glass substrates and post annealing at 550 ℃ for 30 min in vacuum. Vibrating sample magnetometer and X-ray diffraction analyser were applied to study the magnetic properties and microstructures of the films. The results show that without Ag underlayer [SiO2/FePt]5 films deposited onto the glass are FCC disordered; with the addition of Ag underlayer [SiO]FePt]5/Ag films are changed into L10 and （111） mixed texture. The variation of the SiO2 nonmagnetic layer thickness in [SiO2/FePt]5/Ag films indicates that SiO2-doping plays an important role in improving the order parameter and the perpendicular magnetic anisotropy, and reducing the grain size and intergrain interactions. By controlling SiO2 thickness the highly perpendicular magnetic anisotropy can be obtained in the [SiO2 （0.6 nm）/FePt （3 nm）]5/Ag （50 nm） films and highly （001）-oriented films can be obtained in the [SiO2 （2 nm）/FePt （3 nm）]5/Ag （50 nm） films.

Thermodynamics of chromite ore oxidative roasting process

To explicate the thermodynamics of the chromite ore lime-free roasting process, the thermodynamics of reactions involved in this process was calculated and the phrases of sinter with different roasting times were studied. The thermodynamics calculation shows that all the standard Gibbs free energy changes of the reactions to form Na2CrO4, Na2O-Fe2O3, Na2O·Al2O3 and Na2O3 SiO2 via chromite ore and Na2CO3 are negative, and the standard Gibbs free energy changes of the reactions between MgO, Fe2O3 and SiO2 released from chromite spinel to form MgO-Fe2O3 and MgO·SiO2 are also negative at the oxidative roasting temperatures （1 173 1 473 K）. The phrase analysis of the sinter in lime-free roasting process shows that Na2O·Fe2O3, Na2O·Al2O3 and Na2O·SiO2 can be formed in the first 20 min, but they decrease in contents and finally disappear with the increase of roasting time. The final phase compositions of the sinter are Na2CrO4, MgO·Fe2O3, MgO·SiO2 and MgO. The results indicate that Na2CrO4 can be formed easily via the reaction ofNa2CO3 with chromite ore. Na2O·Fe2O3, Na2O-Al2O3 and Na2O·SiO2 can be formed as intermediate compounds in the roasting process and they can further react with chromite ore to form Na2CrO4. MgO released from chromite ore may react with iron oxides and silicon oxide to form stable compounds of MgO·Fe2O3 and MgO·SiO2, respectively.

Preparation and sintering of nano Fe coated Si_3N_4 composite powders

Fe/Si3N4 composite powder was synthesized by the heterogeneous precipitation-thermal reduction process,and then pressed into flakes under a pressure of 10 MPa.Flakes were sintered by pressureless and hot-pressing at 1 600℃under 0.1 MPa N2. The chemical composition,phases and microstructure of composite powder and sintered flakes were investigated by energy dispersive spectroscopy(EDS),X-ray diffraction(XRD),scanning electron microscopy(SEM)and transmission electron microscopy (TEM).The results show that the structure of composite powders is Si3N4 coated by nano Fe.The crystal phases of sintered flakes by pressureless are Fe(Si)compound,SiC and Si3N4.The crystal phases of the sintered samples by hot-pressing are Fe,Fe(Si) compound and Si3N4.It is found that crystal phases flakes obtained by pressureless and hot-pressing are very different.

Effect of Aluminium and Silicon on High Temperature Oxidation Resistance of Fe-Cr-Ni Heat Resistant Steel

Fe-Cr-Ni heat resistant steels with different contents of Al and Si were cast in intermediate frequency induction furnace with non-oxidation method. With oxidation weight gain method, the oxidation resistance of test alloys was examined at 1 200 ℃ for 500 h. The effects of Al and Si on oxidation resistance were studied through analyses of X-ray diffraction （XRD） and scanning electron microscope （SEM）. It is shown that the composition of oxide scales is a decisive factor for the oxidation resistance of heat resistant steels. The compounded scale composed of Cr203, α-Al2O3, SiO2 and Fe （Ni）Cr2O4, with flat and compact structure, fine and even grains, exhibits complete oxidation resistance at 1 200 ℃. Its oxidation weight gain rate is only 0.081 g/（m^2.h）. By the criterion of standard Gibbs formation free energy, a model of nucleation and growth of the compounded scale was established. The formation of the compounded scale was the result of the competition of being oxidated and reduction among Al, Si, and the matrix metal elements of Fe, Cr and Ni. The protection of the compounded scale was analyzed from the perspectives of electrical conductivity and strength properties.

微处理器芯片技术的发展及展望

作为计算机核心的微处理器芯片问世至今三十多年以来,式样不断翻新,产品性能突飞猛进,有力的带动了信息产业发展。本文回顾了三十年以来从4004微处理器到当今Pentium4的技术发展历程,从芯片所用材料的变更、封装技术及光布线技术发展的角度进一步探讨,展望了微处理器芯片未来的发展趋势。

A comparison of soft magnetic composites designed from different ferromagnetic powders and phenolic resins

Soft magnetic composites （SMCs） were prepared from three different ferromagnetic powder particles： iron powder ASC 100.29, spherical FeSi particles and vitroperm （Fe73CulNb3Si16B7） flakes. Two types of hybrid organic-inorganic phenolic resins modified with either silica nanoparticles or boron were used to design a thin insulating layer perfect- ly covering the ferromagnetic particles. Fourier transform infrared （FTIR） spectrometry confirmed an incorporation of silica or boron into the polymer matrix, which manifested itself through an improved thermal stability of the hybrid resins verified by thermogravimetric-differential scanning calorimetry （TG-DSC） analysis. The core-shell particles prepared from the ferromagnetic powder particles and the modified hybrid resins were further compacted to the cylindrical and toroidal shapes for the mechanical, electrical and magnetic testing. A uniform distribution of the resin between the ferromagnetic particles was evidenced by scanning electron microscope （SEM） analysis, which was also reflected in a rather high value of the electrical resistivity. A low porosity and extraordinary high values of mechanical hardness and flexural strength were found in SMC consisting of the iron powder and phenolic resin modified with boron. The coercive fields of the prepared samples were comparable with the commercial SMCs.

关注计算机的核心——计算机芯片的发展

微处理器芯片是计算机的核心,问世至今三十多年以来,式样不断翻新,产品性能突飞猛进,有力地带动了信息产业发展。本文回顾了三十年以来从4004微处理器到当今Pentium4的发展历程,从芯片所用材料的变更、封装技术及光布线技术发展的角度进一步探讨和展望了微处理器未来的发展趋势。