Hydrothermal preparation and crystal habit of X-zeolite powder

The preparation of X-zeolite powder was investigatedin hydrothermal system, the crystal growth process of X-zeolite in hydrothermal condition was characterized by means of X-ray diffraction, scanning electron microscope and infrared ray. The results show that X-zeolite powder with uniform granularity and intact crystal shape can be obtained in hydrothermal system of acid-treated stellerite-NaOH-NaAl(OH)4-H2O; the crystallite size is in the range of 2 - 3μm. The best reaction time of hydrothermal preparation is 6 h. The formation phases of X-zeolite crystal are as follows: dissolution of feedstocks → formation of [SiO4]4- and [AlO4]5- tetrahedron, many-membered ring,β cage → formation of crystal nucleus and nano-particle → aggregation growth of nano-particle → coalescence growth of crystallite. The crystal habits of X-zeolite are intimately related with crystallization orientation ofβ cage in crystal and with its coupling stability on every crystal face family.     

A Method for Identification and Compensation of Machining Errors of Digital Gear Tooth Surfaces

In order to generate the digital gear tooth surfaces(DGTS)with high efficiency and high precision,a method for identification and compensation of machining errors is demonstrated in this paper.Machining errors are analyzed directly from the real tooth surfaces.The topography data of the part are off-line measured in the post-process.A comparison is made between two models:CAD model of DGTS and virtual model of the physical measured surface.And a matching rule is given to determine these two surfaces in an appropriate fashion.The developed error estimation model creates a point-to-point map of the real surface to the theoretical surface in the normal direction.A“pre-calibration error compensation”strategy is presented.Through processing the results of the first trail cutting,the total compensation error is predicted and an imaginary digital tooth surface is reconstructed. The machining errors in the final manufactured surfaces are minimized by generating this imaginary surface.An example of ma- chining 2-D DGTS verifies the developed method.The research is of important theoretical and practical value to manufacture the DGTS and other digital conjugate surfaces.     

High-performance wall-climbing robot for inspection and maintenance

A wall-climbing robot that can continuously work on many types of wall surfaces has been developed. This robot based on low-vacuum adsorption principle consists of a locomotion mechanism, a sealing device, a fluid machine and a detecting system. The adsorption force is analyzed in details and its influencing factors are given. The robot prototype, which has the features of high adhesion efficiency, light body in weight, small size in structure and good capability in payload, is tested in outdoor and indoor environments. Through the experiments, the influences of the impeller slit and the seal clearance are discussed. In addition, the robot functions such as adsorption performance, locomotion performance and wall adaptability are tested by experiments. The experiments have verified that the robot not only can climb on many types of wall surfaces, but also has outstanding locomotion ability and payload capacity.     

Mechatronic integration and implementation of in situ multipoint temperature measurement for seafloor hydrothermal vent

In order to provide firsthand reference data for model building and analysis of temperature field of seafloor hydrothermal vent, a temperature measurement sys- tem is designed, which can be used to measure the temperature of seafloor hydrothermal vent. The system can implement in situ multipoint temperature measurement and work for 15 days on the seafloor, so low power consumption design principle of the integrated circuit board is adopted. To enable the system to endure the high pressure on the seafloor, mechanical structure of the system is designed in terms of design principle of pressure container. The pressure test ex- periment was performed in the authoritative institution, and the results indicated that the system was safe and could work reliably on the seafloor. In the first Sino-American Joint Dive Cruise, the instruments were carried to the seafloor to work by Alvin. The experiment in the sea was successful, and the results indicated that the system could survive in the high pressure and high temperature environ- ment and record the temperature activities of hydrothermal vents. About 710000 groups of temperature data were acquired, and these are of importance for further scientific researches.     

Characteristics and evolution of ore-forming fluids of the Chongjiang copper deposit in the Gangdise porphyry copper belt, Tibet

Petrography, microthermometry, and scanning electron microscope/energy dispersive spectrometer （SEM/EDS） studies were performed on the fluid inclusions in the ore-beating quartz veins and quartz phenocrysts in the porphyry of the Chongjiang porphyry copper deposit. The analyses of the fluid inclusions indicate that the ore-forming fluids were exsolved from magma. They are near-saturated, supercritical, rich in volatile constituents, and have the capture temperature of 362-389℃ and salinities of 17.7wt%- 18.9wt% NaC1 eq. With the decreasing of temperature and pressure, the supercritical fluids were separated into a low salinity vapor phase and a high salinity liquid phase. During quartz-sericitization, the high salinity fluid boiled and separated into a low salinity vapor phase and a high salinity liquid phase. The high salinity inclusions that formed in the boiling process had daughter mineral melting temperatures higher than the homogenization temperatures of the vapor and liquid phases. The late fluids that are responsible for argillization are of lower temperature and salinity.     

Optimization of thermomechanical processes in Cu-Cr-Zr lead frame alloy using neural networks and genetic algorithms

1 Introduction Copper alloys are the most popular lead frame alloys and are used in plastic packag-ing application due to high thermal and electrical conductivity as well as high strength[1-3]. The thermomechanical treatment technology is one of the most used methods to attain high mechcanical and electrical properties of the copper alloys[4-6]. The thermomechanical processes have been mainly studied empirically with the trial-and-error method so far. There are few reports in the literature de…     

Characteristics and formation of high quality reservoirs in sediment gravity flows of Gangzhong area,Huanghuadepression简

Reservoirs can be developed in the sediment gravity flows.However,high quality reservoirs are found widespread in sediment gravity flows of Gangzhong area,Huanghua depression,Bohai Bay Basin,East China.Characteristics and formation of these reservoirs are key problems to be solved.Through comprehensive analysis of thin section petrography,scanning electron microscopy and X-ray diffraction,two distinct rules were obtained.1） These high quality reservoirs have apparent characteristics：lithology consists mainly of medium-fine grained sands; moderately-well sorted and rounded; intergranular pores dominating 70% of the entire pores,surface per unit pore volume reaches 15%; average porosity is 21% and average permeability is 55×10-3 μm2.2） Types of sedimentary microfacies and dissolution strongly control on the formation of high quality reservoirs.Main channels and sandy braided bars have the best reservoir properties.Because that sediments are mainly medium-fine grained sands in high-energy environments.The favorable primary porosity and permeability may promote calcite cementation and help to produce more secondary pores.Besides,at the depth of 2500-3200 m,basically matching threshold of oil generation,organic acid expelled when organic matter became mature,and H＋ released during clay mineral transformation.These both result in the dissolution of calcite cements and create large volume pores,then physical properties improve correspondingly.Moreover,deep hydrothermal fluid intrusion may also have impacts on the development of secondary pores.     

Effect of cobalt loading on reducibility, dispersion and crystallite size of Co／Al2O3 Fischer-Tropsch catalyst

Co/Al2O3 Fischer-Tropsch synthesis catalysts with different cobalt loadings were prepared using incipient wetness impregnation method. The effects of cobalt loading on the properties of catalysts were studied by means of X-ray diffraction (XRD), temperature programmed reduction (TPR), hydrogen temperature programmed desorption (H2-TPD) and O2 titration. Co-support compound formation can be detected in catalyst system by XRD.For the Co/Al2O3 catalysts with low cobalt loading, CoAl2O3 phase appears visibly. Two different reduction regions can be presented for Co/Al2O3 catalysts, which belong to Co3 O4 crystallites (reduction at 320 ““C) and cobalt oxidealumina interaction species (reduction at above 400℃). Increasing Co loading results in the increase of Co3 O4 crystallite size. The reduced Co/Al2O3 catalysts have two adsorption sites, and cobalt loading greatly influences the adsorption behavior. With the increase of cobalt loading, the amount of low temperature adsorption is increased, the amount of high temperature adsorption is decreased, and the percentage reduction and cobalt crystallite size are increased.     

Matter Composition and Two Stage Evolution of a Liangshan Super High-Sulfur Coal Seam in Kaili, Eastern Guizhou

Super-high sulfur coal resultes in serious coal-derived pollution but might have a particular genesis. Thus,a columnar section of an Early Permian Liangshan Formation coal seam. weight average sulfur content 5.80%,from Kaili,eastern Guizhou,was studied using the methods of coal petrology and geochemistry. The results show that the seam was apparently formed in seawater-effected peat bogs that developed in two distinct stages. During the first stage various layers were formed in a supratidal bog and have a composition characteristic of a bog with a gradually decreasing sea-water effect,decreasing water dynamics,and an increasingly reductive environment. Layers in the upper seam formed during a second stage in an intertidal bog. These layers are very high in total and inorganic sulfur,the ratios of or-ganic/inorganic sulfur and V/I drop,they are high in coal ash yield and have a high ash component index,considerable barkinite,oxidized and detrital macerals,have a porphyroclatic micro-structure and are rich in pyrite,all of which indi-cate the coal-forming environment had higher oxidation potential,strong and roiling water dynamics,and intermittent exposure to a sulfur rich environment.     

Experimental Study of Kinetic Properties of Pyrolysis for Conveyor Belt in Coal Mine

1 IntroductionConveyor belts are widely used in coal minesand other places such as power plants and harbors asimportant means of material transportation. Incoalmines, with the deepening of mining and theincrease of the production capacity, belt conveyorstend to be of high speed and in large scale. Althougha variety of fire prevention measures have beentaken, mine fires due to conveyor belt take placenow and then. The poisonous and hazardous gasesand high temperature fume during mine fire sprea…     

Coalescence of the crystallites under hydrothermal conditions (II)

Cuprite (Cu₂O) particles are synthesized by hydrothermal method. Most crystalline particles have long column morphology. Particles which are regarded as assembling of the crystallites in definite directions are observed. The typical example is the particles formed by assembling six columns in three perpendicular directions. The cone surfaces are visible at the tops of the columns. The results revealed that the coalescence of the crystallites did happen under hydrothermal conditions in which the crystallite connected with other crystallite on certain structure compatible surfaces to form a crystalline particle with a special morphology. This phenomenon is called the second kind of coalescence. The Cu₂O structure unit is determined by its crystal structure. It is concluded that the tetragonal prism and three tetragonal prism-like growth units are the favorable units after stability energy calculation was performed on different kinds of growth units. It is believed that the first kind of coalescence exists commonly. The second kind of coalescence is unlikely to occur for all crystallites under hydrothermal conditions. The occurrence is dependent on the crystal structure.     

The growth units and hydrothermal preparation of lead tungstate (PbWO4) crystallites

The crystal structure of lead tungstate (PbWO4) can be regarded as ordered combination of the tungsten oxide tetrahedrons (WO4) and lead ions (Pb2 ). According to the growth unit model, the growth units of lead tungstate are the aggregations of the tungsten oxide tetrahedrons and lead cations with various geometry configurations. It is suggested that the favorable growth units of lead tungstate crystal are pyramidal, tetragonal prism and quadrangular units corresponding to geometric orientations of the simple forms of the crystal. Under low restricted growth conditions, the growth form of lead tungstate crystallites is the aggregation of the geometric configurations of these favorable growth units. The above conclusions are completely confirmed by the experiment on hydrothermal preparation of lead tungstate crystallites.     

The formation of titania polymorphs under hydrothermal condition

The formation process of crystal polymorphs of titania under hydrothermal condition is studied. According to the experimental results and theoretic analysis, the formation process of crystal polymorphs can be described as a unit process. It includes the formation of growth units, the formation of nuclei through the polymerization of growth unit, and the growth of crystallites. The influence of the environmental phase and growth conditions on the formation of polymorphs is reflected in the changes of the structures of growth units. For example, when changing the pH of the reaction medium, the structure of growth unit with the highest stable energy in the hydrothermal system changes. Then different titania polymorphs can be prepared. The absorption, movement, crystallization or desorption of the growth unit are related to crystalline structure. On the other hand, the formation of crystal inner defects is related to the disturbance of the crystallizing process.     

Formation mechanism of barium titanate nanocrystalis under hydrothermal conditions

Growth units and the crystallization habit of BaTiO3 nanocrystals have been investigated. It has been proposed that the growth units of BaTiO3 were surface hydroxylated Ti(OH)62- octahedra. The relationship between crystal morphology and the variation of the current intensity in the solution has been obtained through the measurement of the OH in the solution and the hydrothermal experiment with superimposed direct electric field. Based on the computation of the stability energy of the growth units, the relationship between the crystallized morphology of crystallites and the most favorable growth units under different conditions has been derived. It has been found that there is structure similarity between anatase (TiO2) and BaTiO3 from the crystal chemistry viewpoint, so they are soluble in each other, which can serve as a reasonable explanation for the abnormal phenomenon of the retention of cubic substable phase at room temperature.     

Crystal Structure of a New Compound :Na_(2.1)Ba_(0.9)Cu_(0.1)Nb_(4.9)O_(14.3)

Single crystal of a new compound Na2.1Ba0.9Cu0.1Nb4.9O14.3 was synthesised for the first time. The crystal structure has been determined by single crystal X-ray diffraction and the final R value is 0. 0559. The compound crystallizes in a tetragonal unit cell [a = 12. 442(3) A and c = 3. 954 A ]with space growp P4/mbm and Z=2. The compound is in tetragonal tungsten-bronze type structure but some oxygen vacancies exist in the structure. The structure of the compound consists of NbO6 octahedra and octahedra (Nb, Cu)O6 to form triangle, quadrilateral and pentagonal tunnels. The quadrilateral tunnels are occupied by Na atoms. More than 1/2 pentagonal tunnels are occupied by Na atoms and less than 1/2 that are occupied by Ba atoms. Cu2 replaces Nb5 to form different-valence isomorpism.     

水热法和溶胶-凝胶法制备Mn_(0.8)Zn_(0.2)Fe_2O_4纳米磁性粒子及其结构表征

通过水热法和Sol-Gel法制备了Mn0.8Zn0.2Fe2O4纳米磁性粒子,利用X射线衍射(XRD)、扫描电镜(TEM)以及ICP元素分析对Mn0.8Zn0.2Fe2O4纳米粒子的晶型和形貌进行了表征,讨论了反应方法和反应条件对纳米粒度和结构的影响。结果表明,水热法和Sol-Gel法制备的纳米粒子均为尖晶石型结构,但前者纯度很高,平均粒径为11 nm,而后者含有氧化物杂相,平均粒径为45 nm,通过对比显示出水热法在此反应中的优越性。     

Template growth mechanism of spherical Ni（OH）2

The microstructures and growth process characteristics precipitation-crystallization method were investigated by SEM, TEM of spherical Ni（OH）2 particles synthesized by the aqueous and XRD, and their growth mechanism was discussed. With the reaction beginning and continuing, amorphous Ni（OH）2 nano-crystallites grow up to spherical micron-particles with radially arranged crystallites. The nucleation, crystallization and re-crystallization led by Ostwald ripening simultaneously take place through the whole growth processes. With the course from reversible aggregation to irreversible agglomeration, the Ni（OH）2 particles tend to grow according to the template growth model： the growth on the crystallite templates stretching in the radius directions is free and quick, while the growth rate for crystallites in other directions is confined due to lower monomers concentration and tends to dissolve So it is only the radially arranged crystallites that predominate in the particle and lead to characteristic microstructures.     

镁锌铁氧体粉末的水热法合成及其矫顽力机理

采用水热法合成名义成分为Mg1-xZnxFe2O4(x=0,0.2,0.4,0.6和0.8)的铁氧体粉末样品,采用X射线衍射仪、扫描电镜和振动样品磁强计等对其结构和矫顽力机理进行研究。结果表明:Zn含量增加有利于(Mg,Zn)Fe2O4铁氧体的成相,晶格常数也随着x的增加而增加;与x=0的样品相比,普通软磁材料矫顽力较大,其他样品的矫顽力呈现典型的软磁铁氧体值,且随着x的增大矫顽力呈逐渐减小的趋势,这与晶粒大小有密切关系;样品中微米级的大颗粒是纳米级小晶粒的聚集体。     

Formation mechanism of barium titanate nanocrystals under hydrothermal conditions

Growth units and the crystallization habit of BaTiO₃ nanocrystals have been investigated. It has been proposed that the growth units of BaTiO₃ were surface hydroxylated Ti(OH)₆²⁻ octahedra. The relationship between crystal morphology and the variation of the current intensity in the solution has been obtained through the measurement of the OH⁻ in the solution and the hydrothermal experiment with superimposed direct electric field. Based on the computation of the stability energy of the growth units, the relationship between the crystallized morphology of crystallites and the most favorable growth units under different conditions has been derived. It has been found that there is structure similarity between anatase (TiO₂) and BaTiO₃ from the crystal chemistry viewpoint, so they are soluble in each other, which can serve as a reasonable explanation for the abnormal phenomenon of the retention of cubic substable phase at room temperature. Project supported by the National Natural Science Foundation of China.