Disclosed is a light-emitting diode package, comprising: a package body having a cavity; a light-emitting diode chip having a plurality of light-emitting cells connected in serial with each other; a fluorescent body for converting the wavelength of light emitted by the light-emitting diode chip; and a pair of lead electrodes. The light-emitting cells are connected together in series between the pair of lead electrodes.

Light emitting diode package

Results. The incidence rate of significant non-cardiac occlusive stenotic lesions in patients with coronary artery disease (CAD), who had to undergo CABG, was 15,84 %. Simultaneous revascularization of coronary and non-coronary arteries was performed in 2,46 % of patients with CAD and PolyVD and multi-stage surgical proced ures were chosen in other cases. Conclusions. The outcomes of CAD surgical treatment were improved in this group of patients due to the implementation of a mul-

Федеральное государственное бюджетное учреждение «Научно-исследовательский институт комплексных проблем сердечно-сосудистых заболеваний» Сибирского отделения Российской академии медицинских наук, Кемерово, Россия

This review highlights the synthesis, processing and properties of non-oxide silicon-based ceramic materials derived from silazanes and polysilazanes. A comprehensive summary of the preparation of precursor compounds containing Si–N–Si units, including commercially available materials, is followed by the discussion of various processing techniques. The fabrication of dense bulk ceramics in the Si/E/C/N systems is reported which involves cross-linking of the polymeric ceramic precursor followed by a polymer-to-ceramic transformation step. The cross-linked precursor can be milled, compacted and pyrolysed to form dense, additive-free, amorphous silicon carbonitride monoliths or polycrystalline composites which withstand oxidation in air at 1600°C. Furthermore, an overview is given on the fabrication of silazane derived powders and coatings involving chemical vapour deposition (CVD) methods utilising volatile precursors. Fibre spinning and fibre properties, as well as other processing techniques like infiltration of preforms, the preparation of porous ceramics and joining are briefly discussed. A state of the art of the mechanical properties of polymer derived amorphous Si/C/N and Si/B/C/N ceramics with respect to hardness as well as high-temperature creep and oxidation resistance is summarised. Finally, some important aspects of industrial applications will be considered. The review is in part based on our own work related to the polysilazane derived ceramics, but will also cover a comprehensive state of the art including the published literature in this field.

Silazane derived ceramics and related materials

A nanocomposite structure comprising a nanostructured filler or carrier intimately mixed with a matrix, and methods of making such a structure. The nanostructured filler has a domain size sufficiently small to alter an electrical, magnetic, optical, electrochemical, chemical, thermal, biomedical, or tribological property of either filler or composite by at least 20%.

Nanostructured fillers and carriers

Porous silicon nitride with macroscopically aligned channels was synthesized using a freeze-drying process. Freezing of a water-based slurry of silicon nitride was done while unidirectionally controlling the growth direction of the ice. Pores were generated subsequently by sublimation of the columnar ice during freeze-drying. By sintering this green body, a porous silicon nitride with high porosity (over 50%) was obtained and its porosity was controllable by the slurry concentration. The porous Si 3 N 4 had a unique microstructure, where macroscopically aligned open pores contained fibrous grains protruding from the internal walls of the Si 3 N 4 matrix. It is hypothesized that vapor/solid phase reactions were important to the formation mechanism of the fibrous grains.

Synthesis of Porous Silicon Nitride with Unidirectionally Aligned Channels Using Freeze-Drying Process

The flexural strength of porous Si{sub 3}N{sub 4} ceramics with a variety of microstructures and porosities were evaluated, and the effect of microstructure on the flexural strength was investigated to obtain machinable Si{sub 3}N{sub 4} ceramics having both high strength and high thermal shock resistance. Porous Si{sub 3}N{sub 4} having three types of microstructure, consisting of (1) only spherical grains, (2) combinations of spherical and columnar grains, and (3) only columnar {beta}-grains connected randomly in three dimensions, were readied as specimens. Their mean pore diameters and porosities were 0.2 to 0.3 {mu}m and 8% to 59%, respectively. The flexural strength of the porous Si{sub 3}N{sub 4} (3) was much larger than that of the porous Si{sub 3}N{sub 4} having the other microstructures, and the maximum flexural strength was 455 MPa at a porosity of 38.3%. The thermal shock resistance ({Delta}T), which was determined by a water quench test, of porous SI{sub 3}N{sub 4} with such microstructure and a porosity of 50% was 980 K. All of the porous Si{sub 3}N{sub 4} (3) was easily machined with cemented carbide drills.

Effect of Porosity and Microstructure on the Strength of Si3N4: Designed Microstructure for High Strength, High Thermal Shock Resistance, and Facile Machining

A silicon nitride sintered body comprising α-silicon nitride including α'-sialon and β'-sialon including β-silicon nitride in which the content of the α-silicon nitride including α'-sialon in the surface part thereof is less than its content in the inner part thereof. The silicon nitride sintered body is excellent in mechanical strength at ordinary temperature, productivity and cost efficiency.

Silicon nitride sintered body

The present invention relates to a method of sintering ceramics and ceramics obtained by said method. According to the present invention, the synthesis and sintering of ceramics can be simultaneously carried out by utilizing the reaction heat generated when at least one metallic element selected from metallic elements of IIb, IVb, Vb and VIb groups of the Periodic Table is combined with at least one nonmetallic element such as B, C N and Si without heat or by preliminarily heating the ceramics at temperatures remarkably lower than the usual sintering temperature ceramics thus-produced are superior in abrasion resistance and corrosion resistance. Furthermore, according to the present invention, particles of the same kind of metal as that used in constructing the ceramics comprising the above described metallic elements and nonmetallic elements are dispersed in a matric comprising said ceramics to obtain metal dispersed reinforced ceramics in which both the matrix and the metallic particles are strongly and chemically bonded to each other. According to the latter procedure, ceramic materials having high temperature characteristics, high corrosion resistance and high abrasion resistance, as well as high toughness and high impact resistance can be obtained.

Method of sintering ceramics and metal-dispersed reinforced ceramics obtained thereby

A composite bearing structure that has a high rotational accuracy and that can withstand high-speed rotation comprises first bearing means, second bearing means, third bearing means and fourth bearing means. The first bearing means supports a radial impact force which is applied to a rotator during rotation, and is formed by an inner ring (1) and an outer ring (2) consisting of silicon nitride ceramics sintered bodies. The second bearing means supports an axial load which is applied to the rotator while maintaining a prescribed clearance with the rotator, and is formed by a magnetic bearing body of two permanent magnets (12) and (13) which are thrust-directionally opposed to each other. The third bearing means maintains the radial rotational accuracy of the rotator, and is formed by a radial dynamic pressure producing groove (5) which is formed in a cylindrical surface of the inner ring (1). The fourth bearing means maintains the thrust-directional rotational accuracy of the rotator, and is formed by an air dome portion (100) which is confined in a semi-closed state by the inner ring (1), the outer ring (2) and a cover (4).

Composite bearing structure

Disclosed is a silicon nitride sintered body produced by subjecting a green compact of a mixed powder composed of 1) a silicon nitride powder having a percentage a crystallization of 93% or more and a mean grain diameter of 0.7 µm or less and 2) 5 to 15% by weight in total of a first sintering aid selected from among rare earth element, yttrium oxide and lanthanide oxides and a second sintering aid consisting of aluminum oxide or nitride and at least one selected from among oxides and nitrides of Mg, Ca and Li, to primary sintering in a nitrogen gas atmosphere under a pressure of 1.1 atm or less at 1500 to 1700 °C; and subjecting the sintered body to secondary sintering in a nitrogen gas atmosphere under a pressure of 10 atm or more at the primary sintering temperature or below, thereby giving a sintered body wherein the relative density of the sintered body is 99% or more and the precipitation ratio of an .alpha.-Si3N4 (including .alpha.'-sialon) crystal phase to a .beta.-Si3N4 (including .beta.'-sialon) crystal phase ranges from 1 : 3 to 1 : 8 in terms of the peak intensity ratio in X-ray diffraction.

Akira Yamakawa

Papers

Effect of Porosity and Microstructure on the Strength of Si3N4: Designed Microstructure for High Strength, High Thermal Shock Resistance, and Facile Machining

Silicon nitride sintered body

Method of sintering ceramics and metal-dispersed reinforced ceramics obtained thereby

Composite bearing structure

Silicon nitride sintered body and process for producing the same