Sintering characteristics and crystallization for sol–gel-derived powders for low-dielectric and low-temperature sintering ceramics

Samples in the MgO–Al₂O₃–SiO₂ system were prepared by the sol–gel technique. The coalescence, sintering characteristics, and crystallization were investigated by X-ray diffraction, thermal analysis, and scanning electron microscopy. The dielectric properties and density were measured with an impedance analyzer. Results demonstrated that the obtained cordierite powders synthesized with the sol–gel method distribute uniformly and its effective size is 474 nm. The glass powder could be sintered at 950 °C, and the polymorphic modification cordierite detected in the sintered sample was only stable hexagonal -phase. The sintering densification process was performed mainly in the temperature range from 800 °C to 930 °C, and follows the viscous floating principle. The dielectric constant of the sintered body is 4.2 and its dielectric loss is lower than 0.001 at high frequency (1.5 GHz).     

Electromagnetic Confinement and Shaping for Plate-Form Part

1. IntroductionAs an alternating current is switched on an induction coil, an electromagnetic pressure Pm actingon melt in the coil is produced due to the reaction between this current and induced currellt in themelt. The principle of electromagnetic confinementand shaping technique is using the balan-ce betweenthis pressure and static pressure Ps by melt weightto shape the melt, and by means of adjusting thedistributions of electromagnetic pressure and staticpressure to change the shape of me…     

Oxide single crystals for research and production—an adventure for producer and user or functional technique?

Oxide single crystals have been used during the last 100 years in very different industries. In the first 50 years the jewellery and watch industries were the main users of oxide single crystals like ruby, sapphire and spinel. At that time Europe was the main producer of oxide crystals. Production plants were in France, Switzerland and Germany. In the Second World War the aviation industry started to use these materials for instrumentation systems. This production was mainly in the USA, Russia and Germany. Today, the use of all kinds of oxide single crystals is well established within many industries. However, only a small range of crystals is used in very high quantities. These are crystals such as quartz, aluminium oxide, titanium dioxide, strontium titanate, lithium niobate and tantalate, BBO and garnets. The other crystal materials are widely developed at R&D centres and universities but not really in industrial production. Among the problems are the unstable market places and the rapid change in material specifications from OEM customers.     

Highly spin-polarized materials and devices for spintronics?

The performance of spintronics depends on the spin polarization of the current. In this study half-metallic Co-based full-Heusler alloys and a spin filtering device (SFD) using a ferromagnetic barrier have been investigated as highly spin-polarized current sources. The multilayers were prepared by magnetron sputtering in an ultrahigh vacuum and microfabricated using photolithography and Ar ion etching. We investigated two systems of Co-based full-Heusler alloys, Co₂Cr_{1 − x}Fe_xAl (CCFA(x)) and Co₂FeSi_{1 − x}Al_x (CFSA(x)) and revealed the structure and magnetic and transport properties. We demonstrated giant tunnel magnetoresistance (TMR) of up to 220% at room temperature and 390% at 5 K for the magnetic tunnel junctions (MTJs) using Co₂FeSi_0.5Al_0.5 (CFSA(0.5)) Heusler alloy electrodes. The 390% TMR corresponds to 0.81 spin polarization for CFSA(0.5) at 5 K. We also investigated the crystalline structure and local structure around Co atoms by x-ray diffraction (XRD) and nuclear magnetic resonance (NMR) analyses, respectively, for CFSA films sputtered on a Cr-buffered MgO (001) substrate followed by post-annealing at various temperatures in an ultrahigh vacuum. The disordered structures in CFSA films were clarified by NMR measurements and the relationship between TMR and the disordered structure was discussed. We clarified that the TMR of the MTJs with CFSA(0.5) electrodes depends on the structure, and is significantly higher for L2₁ than B2 in the crystalline structure. The second part of this paper is devoted to a SFD using a ferromagnetic barrier. The Co ferrite is investigated as a ferromagnetic barrier because of its high Curie temperature and high resistivity. We demonstrate the strong spin filtering effect through an ultrathin insulating ferrimagnetic Co-ferrite barrier at a low temperature. The barrier was prepared by the surface plasma oxidization of a CoFe₂ film deposited on a MgO (001) single crystal substrate, wherein the spinel structure of CoFe₂O₄ (CFO) and an epitaxial relationship of MgO(001)[100]/CoFe₂ (001)]110]/CFO(001)[100] were induced. A SFD consisting of CoFe₂ /CFO/Ta on a MgO (001) substrate exhibits the inverse TMR of - 124% at 10 K when the configuration of the magnetizations of CFO and CoFe₂ changes from parallel to antiparallel. The inverse TMR suggests the negative spin polarization of CFO, which is consistent with the band structure of CFO obtained by first principle calculation. The - 124% TMR corresponds to the spin filtering efficiency of 77% by the CFO barrier.     

Research profiling for ‘standardization and innovation’

This paper addresses the profiling of research papers on ‘standardization and innovation’—exploring major topics and arguments in this field. Drawing on 528 papers retrieved from the database, Web of Science, we employed trend, factor, and clustering analyses to demonstrate that the standardization and innovation research has continuously grown from publication of 13 papers in 1995 to 68 papers in 2008; the majority of these papers have been published in the six subject group domains of management, economics, environment, chemistry, computer science, and telecommunications. Technology innovation management specialty journals are the most central sources favorable for these themes. We also present an exploratory taxonomy that offers nine topical clusters to demonstrate the contextual structures of standardization and innovation. The implications of our results for ongoing consistent policy and future research into standardization and innovation are discussed.     

A method for identifying customer orientations and requirements for product–service systems design

For manufacturers, developing product–service systems (PSSs) is getting more important because of the trends of servitisation and creating social value. A PSS is a social system where multiple actors mutually provide products and services. A PSS design, therefore, must take into account various actors as customers. However, existing methods provide an insufficient solution as to how various customers should be handled in an analysis to identify and accommodate various customer preferences and requirements. To tackle this issue, this article proposes a new method of identifying customers’ orientations and requirements for PSS design. The proposed method employs a combination of topic analysis, persona and scenario approaches. The effectiveness of the method is demonstrated with its application to an urban development case. Through the demonstration, its practical benefits are concluded as follows: consistent and logical results of requirement analysis and insights into a new market for manufacturers.     

Rietveld refinements for calcium and yttrium containing α-sialons

The crystal structures of calcium and yttrium containing-sialons, M _x (Si, Al)₁₂(N, O)₁₆, were refined by the Rietveld analysis of their X-ray powder diffraction patterns. Rather lowR factors obtained in the refinements provide conclusive evidence for a structural model proposed by the Newcastle group. In these-sialons, the modifying cations occupy large closed interstices of the (Si, AD-(N, O) network similar structurally to that in-Si₃N₄; each cation is coordinated to seven (N, O) atoms with an average M-(N, O) length of 0.26nm. The (Si, Al)-(N, O) bonds range in distance from 0.17 to 0.18nm (average 0.176 nm). The Rietveld method has been shown to give highly accurate occupation factors for the interstitial cations.     

Towards ferrofluidics for μ-TAS and lab on-a-chip applications

In this paper, we show that ferrofluids can be pumped very effectively in closed-channel geometries both in the macro-?and micro-scales using spatially travelling, sinusoidally time-varying magnetic fields. The results from numerical modelling demonstrate that the optimum pumping frequency is the reciprocal of the Brownian relaxation time constant of the magnetic nanoparticles inside the ferrofluid. Since the Brownian time constant depends in part on the overall hydrodynamic volume of the magnetic nanoparticles, this work has been carried with a view to developing functionalized ferrofluids that can be used as sensitive pathogen detectors in the context of ferrohydrodynamic pumping via travelling magnetic fields. A micro-ferrofluidic device has been designed and fabricated in order to demonstrate the potential development of this technology for pathogen detection. A cost-effective fabrication process combining insulated metal substrate etching and soft lithography is used to realize the prototype micro-ferrofluidic device. Results show good agreement between simulation and experiment. We finally propose a ferrofluid-based pathogen detection scheme that is expected to be insensitive to temperature and viscosity differences between the ferrofluid and the sample to be tested.     

Electroluminescent Polymers and Carbon Nanotubes for Flat Panel Displays

polymeric light-emitting diodes(LEDs) with sufficient brightness. efficiencies, low driving voltages, and various interesting features have been reported. The relatively short device lifetime, however, still remains as a major problem to be solved before any commercial applications will be realized. In this regard,carbon nanotubes have recently been proposed as more robust electron field emitters for flat panel displays. We have synthesised large arrays of vertically aligned carbon nanotubes, from which micropatterns of the aligned nanotubes suitable for flat panel displays were fabricated on various substrates. In this paper, we summarise our work on the synthesis and microfabrication of electroluminescent polymers and carbon nanotubes for flat panel displays with reference to other complementary work as appropriate.     

An Idea for Development of Intelligent Materials and Devices

本文基于铁电体的自发极化P     

Henkel Technologies and Products for China AerospaceEI北大核心

Epoxy structural adhesives and composites have been in use for many years for the construction of aerospace vehicles. Henkel provides many epoxy products. Many other resin systems have been evaluated and several, such as imide, phenolic and cyanate ester, have also achieved significant use. Henkel’s newly developed “Epsilon” chemistry demonstrates unique features that benefit application in aerospace structure that use adhesives and composites.     

Thermochromic Silks for Temperature Management and Dynamic Textile Displays

Silks have various advantages compared with synthetic polymer fibers,such as sustainability,mechanical properties,luster,as well as air and humidity permeability.However,the functionalization of silks has not yet been fully developed.Functionalization techniques that retain or even improve the sustainability of silk production are required.To this end,a low-cost,effective,and scalable strategy to produce TCSs by integrating yarn-spinning and continuous dip coating technique is developed herein.TCSs with extremely long length(>10 km),high mechanical performance(strength of 443.1 MPa,toughness of 56.0 MJ m?3,comparable with natural cocoon silk),and good interfacial bonding were developed.TCSs can be automatically woven into arbitrary fabrics,which feature super-hydrophobicity as well as rapid and programmable thermochromic responses with good cyclic performance:the response speed reached to one second and remained stable after hundreds of tests.Finally,applications of TCS fabrics in temperature management and dynamic textile displays are demonstrated,confirming their application potential in smart textiles,wearable devices,flexible displays,and human–machine interfaces.Moreover,combination of the fabrication and the demonstrated applications is expected to bridge the gap between lab research and industry and accelerate the commercialization of TCSs.     

Gröbner bases and combinatorics for binary codes

In this paper we introduce a binomial ideal derived from a binary linear code. We present some applications of a Gröbner basis of this ideal with respect to a total degree ordering. In the first application we give a decoding method for the code. In the second one, by associating the code with the set of cycles in a graph, we can solve the problem of finding all codewords of minimal length (minimal cycles in a graph), and show how to find a minimal cycle basis. Finally we discuss some results on the computation of the Gröbner basis.     

Microstructure and mechanical properties of Sn–Cu alloys for detonating and explosive cords

To develop alloys as the substitute of Pb-based alloys for cladding materials in detonating and explosive cords, the materials requirement was analysed and Sn–Cu based alloys were selected as potential candidates. Four alloys including Sn–0.3?wt-%Cu, Sn–0.5?wt-%Cu, Sn–0.7?wt-%Cu, and Sn–1.0?wt-%Cu were prepared by casting and rolling. Microstructures of as-cast Sn–Cu alloys comprised Sn solutions with Cu6Sn5 intermetallic in the matrix. The as-rolled hypoeutectic Sn–Cu alloys (0.3–0.5?wt-%Cu) offered the yield strength from 26.1 to 31.9?MPa, UTS from 30.1 to 34?MPa and elongation from 86.4 to 87.5%, which were found to be appropriate for detonating and explosive cords. Particularly, the Sn–Cu alloys exhibited strain softening behaviour under tensile stress, which will benefit cladding manufacture and subsequent processing after assembly with high-energy explosive materials.     

The International Technology Roadmap for Semiconductors—Perspectives and challenges for the next 15 years

The paper will give an overview on the structure and the contents of the International Technology Roadmap for Semiconductors (ITRS), with special emphasis on the ‘ITRS 2001’ edition. The scope of the ITRS covers the next 15 years. The outlook in semiconductor manufacturing expects the continuous application of silicon technology where CMOS based devices will carry the development of the industry at least for one more decade. New device architectures and concepts based on silicon wafer material are being developed to support the development of the IC industry for another one or two decades. The paper will highlight the key issues of future requirements on semiconductor structures and processes for manufacturing technologies on silicon. These will cover material aspects for front end processing, interconnect, lithography, and new devices.     

Contrast and Comparison Between the Old and New Bar Code for Commodity Management Measures

With the development of socialism market economy, the former Bar Code For Commodity Management Measures (being called Old Measures for short hereafter) issued by the National Bureau of Quality and Technical Supervision can not adapt to the requirement of managing for bar code for com-     

A constitutive model for fiber-reinforced polymer plies accounting for plasticity and brittle damage including softening – Implementation for implicit FEM

A constitutive ply model is developed to allow for the simulation of laminated structures made of fiber-reinforced polymers. The model accounts for stiffness degradation accompanied by strain hardening (i.e. distributed brittle damage), unrecoverable strain accumulation (i.e. multi-surface plasticity), and stiffness degradation accompanied by strain softening (i.e. localized brittle damage). Owing to the characteristics of such ply materials the model handles these effects and their evolutions in an anisotropic manner.     

Residual life prediction and retirement for cause criteria for sstg upper casings—I. Mechanical and fracture mechanics material properties development

Mechanical and fracture mechanics material properties of 2-1/4Cr-1Mo cast steel were developed at temperatures up to 1000°F (538°C) in support of a fracture mechanics analysis to evaluate the residual life and establish retirement for cause criteria relative to upper inlet Ships Service Turbine Generator (SSTG) casings that contained numerous cracks in the inlet steam passageways and steam chest. Mechanical tests included tensile, Charpy V-notch impact, monotonie and cyclic stress-strain plus static creep rupture tests. Fracture mechanics tests included fracture toughness, load and displacement-controlled fatigue crack growth rate (FCGR) tests and displacement-controlled creep-FCGR interaction tests. Details of the actual fracture mechanics analysis are contained in Part II of this paper.