罩式退火工艺对Ti-IF钢组织性能的影响

利用光学显微镜、伺服拉伸实验机和X射线衍射仪研究了不同退火温度和保温时间对Ti-IF钢组织、性能及r值的影响规律,分析了工艺优化后的再结晶织构. 结果表明,8 h为实验Ti-IF钢从部分饼形晶粒到绝大部分等轴晶粒演变过程中的一个时间界限,冷轧板在710℃下保温8 h退火后,再结晶晶粒为均匀的等轴晶粒,r值为2.347,抗拉强度312 MPa,延伸率44.7%,{111}面织构密度水平达到13.1. 在此工艺条件下,Ti-IF钢得到优良的深冲性能,该实验结果可为Ti-IF钢罩式退火工艺的优化提供理论依据.     

单取向与无取向硅钢的快速鉴别

利用X-射线衍射仪分别测试了单取向与无取向硅钢在轧面的衍射谱图,通过两种硅钢分别在轧面内不同方向上的衍射峰强度变化,以及在不同晶面衍射峰强度的变化将两者区别开来。结果表明,无取向硅钢在{110}、{200}、{211}晶面均有强的衍射峰出现,而单取向硅钢仅在{110}晶面有强的衍射峰。且在轧面内,单取向硅钢在不同方向的衍射峰强弱分明,而无取向硅钢在各个方向的衍射峰强度变化较小且无规律性。     

ZrO_2溅射膜的柱状生长机制

气相沉积ZrO2 膜常为柱状结构 ,要更好地控制ZrO2 膜性能 ,需要研究ZrO2 膜中柱状结构的形成和演化规律 .在射频溅射条件下沉积了ZrO2 膜 ,发现该膜的柱状晶具有 { 111}面织构 ,其底层可能还有等轴晶 .提出以下柱状晶形成机制 :在光滑 (玻璃 )基片上形成的柱状晶源自于在基片表面形成的具有 { 111}面织构的最初晶核 ;在较为粗糙 (多晶Al2 O3)基片表面上形成的柱状晶源自于〈111〉晶向与沉积物质流方向一致的晶核择优生长及随后对其它取向的小晶核的吞噬而形成的晶核群 .基片表面粗糙时 ,由于柱状晶核经过晶核筛选产生 ,柱状晶底部可能有等轴晶层 ;若温度较低 ,出现等轴晶层可能性更大     

ZrO2溅射膜的柱状生长机制

气相沉积ZrO2膜常为柱状结构,要更好地控制ZrO2膜性能,需要研究ZrO2膜中柱状结构的形成和演化规律.在射频溅射条件下沉积了ZrO2膜,发现该膜的柱状晶具有{111}面织构,其底层可能还有等轴晶.提出以下柱状晶形成机制在光滑(玻璃)基片上形成的柱状晶源自于在基片表面形成的具有{111}面织构的最初晶核;在较为粗糙(多晶Al2O3)基片表面上形成的柱状晶源自于〈111〉晶向与沉积物质流方向一致的晶核择优生长及随后对其它取向的小晶核的吞噬而形成的晶核群.基片表面粗糙时,由于柱状晶核经过晶核筛选产生,柱状晶底部可能有等轴晶层;若温度较低,出现等轴晶层可能性更大.     

烧结锶铁氧体的极图分析

将不同强度取向磁场下湿压成型的生坯在1 190℃烧结2 h,获得锶铁氧体烧结磁体.采用X射线极图分析样品的织构取向特征,根据Stoner-Wohlfarth模型,建立了描述取向度的表示方法.分析表明:在磁场下成型的样品{001}晶面族衍射峰强度显著增强.用(008)晶面极图描述磁体取向度时,随取向磁场强度的增大,晶粒取...     

模板晶粒生长技术制备织构化SrBi2Nb2O9陶瓷

以熔盐法合成各向异性的片状单相SrBi2Nb2O9(SBN)陶瓷粉体作为模板,采用模板晶粒生长(templated grain growth,TGG)技术制得织构化SBN陶瓷.研究结果表明:随着烧结温度的升高和模板数量的增加,其晶粒取向率升高.当模板数量(质量分数)为20%时,在1 300 ℃烧结3 h可获得晶粒取向率为0.86的织构化SBN陶瓷.同时,TGG技术制得的织构化SBN陶瓷的相对体积密度在烧结温度低于1 300 ℃时,随烧结温度的升高而升高;在1 300 ℃时为91.22%;在高于1 300 ℃时开始下降.     

退火温度对硅基铁电薄膜Bi_4Ti_3O_(12)晶相结构的影响

采用溶胶-凝胶(Sol-Gel)法制备铁电Bi4Ti3O12 (BIT)薄膜,研究退火温度对其微观特性的影响,以掌握制备工艺中最佳退火温度。研究表明,随着退火温度的增加,BIT薄膜的c轴取向生长更明显,晶粒尺寸增加,同时表面粗糙度增加;从退火750℃开始,晶粒开始呈棒状生长;当温度高于850℃时,薄膜的c轴生长取向增长趋势不再明显。退火时间对薄膜的相结构和生长取向没有明显影响。     

脉冲准分子激光扫描沉积(PLD)高c轴取向V2O5/Si薄膜及结构分析

采用脉冲准分子激光大面积扫描沉积技术,在Si(111)单晶衬底上沉积了多晶V2O5薄膜,经300℃以上退火处理得到了具有高c-轴取向生长的V2O5膜。300℃以上热退火处理的薄膜表面具有正常的化学计量比（无氧缺位）,晶粒间界明显,晶粒呈针棒状,晶粒尺寸在100－200nm之间。采用X射线衍射（XRD）、Raman光谱（RS）、Fourier红外光谱（FT－IR）及透射电镜扫描附件（STEM）对沉积及不同温度下退火处理的样品进行了结构分析。研究结果表明：V2O5/Si薄膜经400℃热处理后表面部分处于低价态的钒离子已被氧化为V2O5。     

{001}面TiO2光催化降解罗丹明B的研究

以钛酸四丁酯为钛源、HF为形貌控制剂,采用水热法在不同反应温度条件下制备纳米片状{001}面TiO2,并以罗丹明B的光催化降解为模型反应,考察了不同反应温度对{001}面TiO2形貌结构的影响,研究了反应温度、pH及催化剂投加量对光催化活性的影响。结果表明,所有{001}面TiO2均具有良好的锐钛矿相衍射峰,并且在紫外光区域具有明显的光吸收;当反应温度为180℃、溶液pH为2、投加量为1 g/L时,样品对罗丹明B光催化降解活性最高,紫外光照射20 min后罗丹明B降解率可达100%。     

改进有槽法平板玻璃化学组成的初探(续)

(五)热膨胀系数有关玻璃试样膨胀系数比较表表8\产膨胀系数…室温一…,00一…ZDD一…。D0一…400一…软化温度沙、\,1。一,{一一}一}叭样玄_.\\一__1 100℃一2。。℃一300℃}4。。℃一600℃}Tg℃一全匕一…」,竺些卜竺竺一…一旦,卫旦一…i旦,』,…111…些…..竺竺 p一4}83.05一90.83}91·67{103·54{115·63}580转化温度Tg℃530543 (六)玻璃透光度 本项性能测定,其玻璃样品选用威海平板玻璃厂变料前后的产品。方相比,Fe203含量约高0.01%,对透光度略有影响。 玻璃试样透光度对比表高铝含磷配方与原配表9一..........曰....一一一竺-一i翌…     

Crystallographic Facetting in Sintered Barium Titanate

A commercial TiO₂-excess BaTiO₃ powder has been sintered and its microstructure analyzed for crystallographic facetting via both scanning and transmission electron microscopy (SEM and TEM). Facetted grain surfaces are developed initially from {111} at a low temperature of 1215°C, which are then altered to {111} and {100} at 1290°C in the presence of a grain-boundary liquid phase. The grain shape is also modified correspondingly from platelike to polygonal. Facetting of the intragranularly located residual pores in BaTiO₃ along the {141} planes further develops on the (quasi-)equilibrium shape after annealing at 1400°C for 100 h from the initially well-characterized {111}, {110}, and {100} in as-sintered samples sintered at the same temperature for 10 h. The Wulff plots derived from the residual pores in as-sintered and annealed samples are constructed for the 〈011〉 zone. Microstructural analysis also suggests that the shape of grains and intragranular residual pores is modified progressively upon annealing. The initial solid–vapor surface energy has become less anisotropic crystallographically. Abnormal grain growth in relation to the surface energy anisotropy is discussed.     

Influence of surface orientation on the photochemical reactivity of CaTiO3

The orientations and surface structures of ferroelastic CaTiO₃ crystals within a polycrystalline ceramic were measured by electron backscatter diffraction and atomic force microscopy (AFM) respectively. Surfaces annealed at 1250°C in air are made up of a combination of facets with orientations near {100}, {110}, and {111} (indexed with reference to the cubic perovskite cell). The samples were immersed in an aqueous AgNO₃ solution and illuminated to photochemically reduce silver. Based on the amount of silver reduced on different surfaces, it was determined that surfaces with a {111} orientation had the greatest photocathodic reactivity, those with a {110} orientation had the least photocathodic reactivity, and surfaces with the {100} orientation had intermediate reactivity. While the {110} surfaces were essentially inert for photocathodic reduction, they were active for the photoanodic oxidation of Mn²⁺. Ferroelastic domains were observed to enhance and retard the photochemical reduction of silver on spatially alternating domains on 20% of the grains. However, domains had no influence on the reactivity of the other 80% and are therefore secondary to the surface orientation in determining the reactivity.     

Tribological behaviour of <100> and <111> fibre textured CVD diamond films under dry planar sliding contact

<100> and <111> fibre textured diamond films are grown on SSiC sliding rings by hot filament CVD and are tribologically tested in dry planar contact under ambient air.The wear of the self-mated textured diamond coating takes place initially at protruding grains of the as-deposited micro rough diamond surface. After 10 km of dry sliding against <100> textured diamond the respective counterparts with <100> and <111> textures exhibit smoothly polished diamond faces without visible surface failures. After dry sliding against <111> textured diamond as static counterpart {100} diamond faces of isolated grains show Hertzian cone cracks and propagation of cracks preferred along {111} easy cleavage planes whereas {111} diamond faces reveal no crack propagation in substrate direction.The results are visualised in a tribo map in which the linear wear of the dynamic diamond face is plotted against the mean coefficient of friction. The best tribological behaviour in terms of low friction and little diamond wear is achieved for sliding couples with <100> fibre texture on the rotating sliding ring and <111> fibre texture on the static ring as mating diamond faces.     

Arrowhead-like diamond crystals formed by hot-filament chemical vapor deposition

Arrowhead-like diamond crystals have been formed by using a simple method of hot-filament-assisted chemical vapor deposition. These are contact twins with {111} as the twin plane, of which each individual is composed of {100}, {110} and {111} faces. These twins flatten along {110} face and elongate parallel to {111} contact plane. The flattened {110} face consists of many {110} terraces sided by 〈110〉 and 〈112〉 steps. So the twinned crystal looks like an arrowhead. These twins are formed just underneath the uppermost substrate temperature for diamond growth.     

Texture and Fracture Toughness Anisotropy in Silicon Carbide

Quantitative texture analysis, which included calculation of the orientation distribution function, was used to demonstrate textures in hot-pressed and subsequently annealed silicon carbide (SiC). The results indicated that the hot pressing and annealing could produce strong textures in SiC. Grain rotation during hot pressing and preferred grain growth of plate-shaped α-SiC grains during annealing both apparently contributed to texture development in the SiC materials. The {111} pole figure in hot-pressed material (mostly ß-SiC) and the (004) pole figure in annealed material (mostly α-SiC) were consistent with the microstructural observations. The fracture toughness of hot-pressed and annealed material measured parallel to the hot-pressing direction (5.7 MPam^1/2) was higher than that measured perpendicular to the hot-pressing direction (4.4 MPam^1/2), because of the texture and the microstructural anisotropy.     

Development of crystallographic texture in chemical solution deposited lead zirconate titanate seed layers

Direct seeding of {001} textured lead zirconate titanate (PZT) on platinized silicon substrates was achieved by chemical solution deposition. The processing space for {001} PZT texturing was explored, under fixed PZT pyrolysis and crystallization conditions, by varying the lead content in solution, dopant species, and PZT layer thicknesses for deposition on platinized Si substrates with different platinum grain sizes. Strong {001} texture was achieved on fine‐grained (25 nm) platinum deposited at room temperature and dense, large‐grained platinum (80 nm) deposited at elevated temperature. Increases in lead content of solutions (from lead excesses of 10 at.% to 16 at.%) reduced surface pyrochlore coverage, with no substantial influence on orientation or grain size. Seed layer texturing was found to be insensitive to doping (Mn and Nb) on room temperature platinum, although niobium doping increased pyrochlore coverage. Conversely, on platinum deposited at high temperature, manganese doping reduced the perovskite nucleation, producing a rosette microstructure. Undoped seed layers from 30 to 70 nm thick were found to be strongly {001} textured while thicker layers were {111} textured and thinner layers were poorly crystallized.     

Electron microscopy of interfaces in chemical vapour deposition diamond films on silicon

The structure of interfaces in diamond films grown on Si(100) has been investigated by transmission electron microscopy for the early stages of microwave-assisted chemical vapour deposition. Using conditions optimized for achieving so-called highly-oriented diamond films the depositions were performed in two steps, a bias-enhanced nucleation step and a subsequent growth step. Characteristic for the early deposition stages is the self-organized formation of regular arrays of predominantly {111}-facetted Si substrate surface grooves and islands elongated along [1̄10] and [110] directions. Subsequently, an interlayer of nanocrystalline β-silicon carbide islands forms, followed by the formation of epitaxially oriented diamond nanocrystals with high fractions of {111} interfaces. High-resolution electron microscopy of the interface regions depicts arrays of terminating {111} diamond planes at an average ratio of five diamond to four SiC lattice planes which corresponds to a remaining lattice mismatch of 2.3%. The orientation relationships between the lattices may be described by a coincidence site lattice model if the elastic lattice distortions are taken into account. Only small fractions of amorphous inclusions are present near interfaces, essentially consisting of amorphous carbon as could be deduced from analyses of the C K edge fine structure in electron energy loss spectra. The observations are compared with cases for which diamond nucleation directly on silicon has been obtained.     

High resolution mapping of surface reduction in ceria nanoparticles

Surface reduction of ceria nano octahedra with predominant {111} and {100} type surfaces is studied using a combination of aberration-corrected Transmission Electron Microscopy (TEM) and spatially resolved electron energy-loss spectroscopy (EELS) at high energy resolution and atomic spatial resolution. The valency of cerium ions at the surface of the nanoparticles is mapped using the fine structure of the Ce M(4,5) edge as a fingerprint. The valency of the surface cerium ions is found to change from 4+ to 3+ owing to oxygen deficiency (vacancies) close to the surface. The thickness of this Ce(3+) shell is measured using atomic-resolution Scanning Transmission Electron Microscopy (STEM)-EELS mapping over a {111} surface (the predominant facet for this ceria morphology), {111} type surface island steps and {100} terminating planes. For the {111} facets and for {111} surface islands, the reduction shell is found to extend over a single fully reduced surface plane and 1-2 underlying mixed valency planes. For the {100} facets the reduction shell extends over a larger area of 5-6 oxygen vacancy-rich planes. This finding provides a plausible explanation for the higher catalytic activity of the {100} surface facets in ceria.