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Sub-micro α-Al2O3 polishing liquid is often used as the slurry in chemical mechanical polishing (CMP). At present, water is usually used as dispersion medium to disperse sub-micro α-Al2O3 powders, but the sub-micro α-Al2O3 powders easily subside in aqueous solution. In previous studies, researchers usually used single method to disperse superfine powders, however, the dispersion effect was non-ideal. In order to solve the difficult problem of sub-micro α-Al2O3 powders dispersed in water suspension, firstly, using physical method, the effects of milling time, ultrasonic time on the dispersion property of sub-micro α-Al2O3 powders in water suspension was studied by single factorial test. Then, using chemical method, the effects of dispersant type, dispersant concentration and pH value on the dispersion property of sub-micro α-Al2O3 powders in water suspension was studied by orthogonal test. Absorbance was used to evaluate the dispersion property of sub-micro α-Al2O3 powders. The results show that th...

Non-isothermal reduction kinetics and mechanism of high chromium vanadium–titanium magnetite pellets were studied at 400–1100°C, simulating the lumpy zone of blast furnace conditions. The phase transformation behaviour of valuable elements including Fe, Cr, V and Ti and microstructural changes of reduced pellets were examined by means of X-ray diffraction (XRD) and SEM-EDX. The swelling of reduced pellets was highest at 900°C, while cold crushing strength was highest at 1100°C. Phase transformation behaviour of valuable elements in the lumpy zone is as follows: Fe2O3→Fe3O4→FeO→Fe; Fe2Ti3O9→Fe2TiO4→Fe5TiO8→FeTiO3; V2O3→VO; (Fe0·6Cr0·4)2O3→FeO·Cr2O3→Cr2O3. By analysing the non-isothermal reduction kinetics of high chromium vanadium–titanium magnetite pellets, based on the evaluation of reaction activation energy calculated according to Coats–Redfern method, gaseous internal diffusion through solid product layer and interfacial chemical reaction are most likely to be the main rate controlling steps i...

Polycrystalline ceramic samples of magnesia doped GdSm1–xMgxZr2O7–x/2 have been prepared by conventional solid state reaction method using high purity oxides. The influence of magnesia dopant content on densification, microstructure and electrical properties of GdSm1–xMgxZr2O7–x/2 ceramics are investigated. Magnesia doping promotes the sintering densification behaviour of GdSm1–xMgxZr2O7–x/2 ceramics. GdSm1–xMgxZr2O7–x/2 (x = 0, 0·05, 0·10) ceramics have a single phase of the pyrochlore type structure, while GdSm1–xMgxZr2O7–x/2 (x = 0·15, 0·20) ceramics consist of the pyrochlore type structure and a small amount of magnesia as the second phase. The total conductivity of GdSm1–xMgxZr2O7–x/2 ceramics obeys the Arrhenius relation, and gradually increases with increasing temperature from 723 to 1173 K. GdSm1–xMgxZr2O7–x/2 ceramics are oxide-ion conductors in the oxygen partial pressure range of 1·0×10–4 to 1·0 atm at each test temperature. The maximum value of the total conductivity is 1·29×10–2 S cm–...

A laboratory method combining the high-energy mechanical ball milling and high static pressure has been suggested for modelling synthesis of coesite in the Earth's crust. A window of milling time, a mechanical collision-induced intermediate phase of a-quartz and its condition of easily crystallizing into coesite under the condition of 3.0 GPa, 923 K, < 1.0 min have been discovered. The new method needs much shorter synthesizing time and tower synthesizing critical pressure than those used before. The Raman spectra for the coesite synthesized by the present method have covered all the information of those natural and synthesized coesites reported before. It is demonstrated that this method has a great potential in geo-science research and implied the other possible mechanism of coesite formation in the Earth's crust.

The microstructural evolution of a spheroidised Fe-0.85C wt- steel during heavy cold rolling and post-aging was studied, with the emphasis on cementite. A new morphology of cementite, wavy thin bands nearly parallel to the rolling plane, was found in the specimens subjected to rolling reductions >90. Slip on 001theta planes was observed in the deformed cementite particles. By X-ray diffraction, it was found that the initial spheroidal cementite particles dissolve partially in a solid solution of ferrite by deformation, in a manner similar to that of the lamellar cementite of pearlite. Greater strain age hardening was observed for the spheroidised steel than for a similarly treated pearlitic Fe-0.85C steel. The strain age hardening peak was observed at 573 K for the spheroidite structure, which is 150 K higher than was observed for the pearlite structure. The activation energy for age hardening was estimated to be 122 kJ mol1, which is attributed to carbon atom diffusion from cementite to dislocati...

An attempt has been made to establish a relationship between hardness and tensile properties for various single structured steels: ferrite, pearlite, bainite, and martensite. It is found that the proportionality constant A Y of hardness to yield strength changes from 5.79 to 3.17 and is highest for the ferrite steel and lowest for the tempered martensitic steels. A less pronounced change was found in the proportionality constant A T of hardness to tensile strength (from 3.97 to 2.72). A dependence on microstructure of the proportionality constant at 8% strain A 0.08 was found as well. This difference in A was found to be attributable mostly to the effect of different work hardening behaviours owing to different microstructures. Regression analysis shows that hardness can be expressed as a function of accessible material parameters such as composition, grain size, and transformation temperatures for various single structured steels within a certain degree of accuracy.

We present an introductory description of Q-state Potts model and its application to dynamic hysteresis simulation in multi-domain polar lattice, using Monte-Carlo method. Some fundamental issues associated with dynamic hysteresis in multi-domain polar lattice, such as kinetics of domain switching, domain size effect and Q-dependence as well, are studied before a detailed presentation of the scaling behavior and remanence enhancement effect is given. The experimental data for PZT thin film capacitors as supportive evidence to the simulation is presented.

Transparent Pb0.72La0.28TiO3 thin films have been deposited on (100) LiF substrates by pulsed laser deposition technique employing a KrF laser 248nm wavelength). The single perovskite target employed was prepared by sintering of the alkoxy-derived high-purity PLT powder at 1150°C. Polycrystalline PLT thin films have been grown on (100) LiF substrates under the conditions of laser fluence 2.5J/cm2, oxygen pressure 13Pa and substrate temperature 750°C. The structure, morphology and stoichiometry of the as-grown films and the employed target were characterized by XRD, SEM and EPMA technique, respectively. The optical transmittance spectrum of the as-grown thin film on LiF substrates in the wavelength range of 350 ∼ 2000nm was measured

High quality La0.5Sr0.5CoO3 (LSCO) thin films have been prepared by pulsed laser deposition(PLD). The target was prepared by using citrate processing method. The electrical resistivity versus temperature has been measured. The LSCO thin films were grown epitaxially on LaAlO3(100) substrates, whereas the LSCO films on Si(100) or Si(111) show to be polycrystalline. The resistivity of the films is slightly larger than that of the targets. The PZT films were grown on LSCO/LAO(100) substrates forming heterostructures and their ferroelectric hysterisis has been measured

Translation twins (T twins) of γ-TiAl (L1O-type structure) in an as-cast two-phase TiAl-Ti3Al intermetallic alloy with Cr addition are characterized by high-resolution electron microscopy and supported by image simulation. The T twin and the matrix are connected through a glide reflection plane at the {111} twin interface, and the glide vector is ½ [101] parallel to the interface. The formation mechanism of the T twins and their possible influence on the deformation mechanism of the material are discussed.

The atomic stacking sequence along the 〈001〉 direction in γ-TiAl (L10 type of structure) of an as-cast two phase TiAl/Ti3Al intermetallic alloy with Cr and Si additions has been investigated by field ion microscopy (FIM) and supported atom probe microanalysis. The γ-phase possesses a high degree of ordering. During cooling thermally formed (100) antiphase boundaries (APBs), super dislocations, as well as super partial dislocations were observed and detected by APFIM. From this it is suggested that the addition of Cr lowers the APB energy in TiAl and the origin of the APBs is related to the displacement of 1/2〈011〉 super partial dislocations.

The present report summarizes the results of a search for hemoglobinopathies in 142,171 persons in Xinjiang, the results of structural analyses of abnormal hemoglobins in 134 families, and the incidence and distribution of abnormal hemoglobins and the thalassemias in eight ethnic groups or nationalities.