[en] A unique approach to crack-free joining of heterogeneous ceramics is demonstrated by the use of sialon polytypoids as Functionally Graded Materials (FGM) as defined by the phase diagram in the system, Si3N4-Al2O3. Polytypoids in the Al2O3-Si3N4 system offer a path to compatibility for heterogeneous ceramics. This paper describes successful hot press sintering of multilayered FGM's with 20 layers of thickness 500 mm each. Transmission Electron Microscopy was used to identify the polytypoids at the interfaces of different areas of the joint. It has been found that the 15R polytypoid was formed in the Al2O3-contained layers and the 12H polytypoid was formed in the Si3N4-contained layers

No abstract available

[en] Creep behavior is reported for an in-situ toughened SiC, between 1100 and 1500 C,in four-point bending

[en] Heat treatments at 1300 degrees C, 1400 degrees C, 1500 degrees C, and 1600 degrees C in Ar were found to produce nanoscale precipitates in hot-pressed silicon carbide containing aluminum, boron, and carbon sintering additives (ABC-SiC). The precipitates were studied by transmission electron microscopy (TEM) and nano-probe energy-dispersive X-ray spectroscopy (nEDS). The precipitates were plate-like in shape, with a thickness, length and separation of only a few nanometers, and their size coarsened with increasing annealing temperature, accompanied by reduced number density. The distribution of the precipitates was uniform inside the SiC grains, but depleted zones were observed in the vicinity of the SiC grain boundaries. A coherent orientation relationship between the precipitates and the SiC matrix was found. Combined high-resolution electron microscopy, computer simulation, and nEDS identified an Al4C3-based structure and composition for the nano-precipitates. Most Al ions in SiC lattice exsolved as precipitates during the annealing at 1400 to 1500 degrees C. Formation mechanism and possible influences of the nanoscale precipitates on mechanical properties are discussed

[en] Modeling of non-equilibrium solidification in multi-component alloys is of singular importance in microstructure control, which however owing to the complex systems with complex additional constraints is still an open problem. In this work, the thermodynamic extremal principle was applied to solve the complex additional constraints self-consistently in thermodynamics. Consequently, short-range solute redistribution and long-range solute diffusion that share the same mobility are integrated naturally into the solute diffusion equations, thus avoiding the introduction of additional kinetic coefficients (e.g. interface permeability) to describe solute redistribution. Application to the non-equilibrium solidification of Al-Si-Cu alloys shows that anomalous solute trapping and anomalous solute profiles within the diffuse interface could occur, thus highlighting the important effect of the interaction among the component elements on the interface kinetics. The current phase-field model might be preferred for simulations not only because of its simplest form of evolution equations but also its feasibility to increase the simulation efficiency by the “thin interface limit” analysis.

[en] The age hardening behavior and microstructural characteristics of a 53Ni-20Co-15Cr-5Mo-4.9Al-1.3Ti alloy has been investigated by micro-Vickers hardness test and transmission electron microscopy. The shape of γ' precipitates was spherical at the early stage of aging and was cuboidal at the later stage. The aged hardness of the alloy closely related to the size and the quantity of γ' precipitates. The γ' precipitation cannot be suppressed by water quenching after solution treatment. It is necessary to cool the specimen at rates of higher than 10⁴ K/s for restraining the precipitation of γ' phase. The growth kinetics of γ' precipitates in the alloy followed the prediction of Lifshitz-Slyozov-Wagner (LSW) theory for growth under volume diffusion control at all aging temperatures examined. The activation energy for the growth was estimated to be 266 kJ/mol which was close to those of diffusion of solute atoms such as Al, Ti and so on in Ni and Ni-base alloys. The actual particle size distribution of γ' precipitates was somewhat different from distributions predicted by the LSW and Brailsford-Wynblatt encounter modified (BWEM) theories. (author)

[en] In this manuscript, porous Co₃O₄ nanorods are prepared through a two-step approach which is composed of hydrothermal process and heating treatment as high performance anode for lithium-ion battery. Benefiting from the porous structure and 1-dimensional features, the product becomes robust and exhibits high reversible capability, good cycling performance, and excellent rate performance. - Graphical abstract: 1D porous Co₃O₄ nanostructure as anode for lithium-ion battery with excellent electrochemical performance. - Highlights: • A two-step route has been applied to prepare 1D porous Co₃O₄ nanostructure. • Its porous feature facilitates the fast transport of electron and lithium ion. • Its porous structure endows it with capacities higher than its theoretical capacity. • 1D nanostructure can tolerate volume changes during lithation/delithiation cycles. • It exhibits high capacity, good cyclability and excellent rate performance

[en] We report successful application of space-charge forces of a low-energy electron beam for improvement of particle lifetime determined by beam-beam interaction in high-energy collider. In our experiments, an electron lens, a novel instrument developed for the beam-beam compensation, was set on a 980-GeV proton bunch in the Tevatron proton-antiproton collider. The proton bunch losses due to its interaction with antiproton beam were reduced by a factor of 2 when the electron lens was operating. We describe the principle of electron lens operation and present experimental results

[en] Objective: To analyze the misdiagnosis of breast diseases on mammography. Methods: In total 69 cases of breast disorder confirmed by pathological examinations, but misdiagnosed on mammography were retrospectively studied. Results: Among 69 cases, 24 benign disorders were misdiagnosed as malignant lesions, and 45 malignant lesions were misdiagnosed as benign ones. Lesions were lacking contrast in dense breasts and tiny abnormalities of lesions revealed on mammogram resulted in misdiagnosis. Conclusion: Standardized mammography and careful investigation of mammogram can reduce the misdiagnosis

[en] Highlights: • Phenol degradation over WO_3 under visible light occurs in presence of H_2O_2. • Reaction rate is greatly increased upon the addition of trace CuWO_4. • Photocatalytic reduction of H_2O_2 to OH radicals is also enhanced. • Electrochemical reduction of H_2O_2 suggests an electron transfer from CuWO_4 to WO_3. - Abstract: Development of a visible light photocatalyst is challenging. Herein, we report a significant activity enhancement of WO_3 upon addition of CuWO_4. Reaction was carried out under visible light for phenol degradation in aqueous suspension in the presence of H_2O_2. A maximum reaction rate was observed at 1.0 wt% CuWO_4, which was 2.1 and 4.3 times those measured with WO_3 and CuWO_4, respectively. Similar results were also obtained from the photocatalytic formation of OH radicals, and from the electrochemical reduction of O_2. A possible mechanism responsible for the improved activity of WO_3 is proposed, involving the electron transfer from CuWO_4 to WO_3, followed by the reduction of H_2O_2 over WO_3.