摘要:
Methods of preparing ferrite powders for use in microwave elements such as isolators, circulators, phase shifters and transmission line elements. In one method separate precipitations of metal dicarboxylate salts such as oxalates or malonates are mixed with a ferrous dicarboxylate. This is followed by mixing and calcining of the precipitated dicarboxylates to form the ferrite powder. In another method metal acetates in a solution of concentrated acetic acidare mixed with iron powder to form a solution which is mixed with malonic acid. The resulting mixed metal malonates are processed into a powder which is calcined to obtain the ferrite. To form a lithium ferrite, lithium carbonate is added to prepared powders prior to the calcining step.
摘要:
Materials and methods for the fabrication of high density, low temperature fired microwave ferrites for use in microwave power devices, transmission line elements, isolators, circulators, and phase shifters. Very fine (sub-micron) ferrite powders made by sol-gel methods are mixed with solvents and binders then tape-cast. Ferrite tapes in the unfired state are cut into complex shapes and may be provided with via holes. These ferrite sheets are fired discretely, or are laminated, cofired with printed metal pastes, or other active and passive ceramic tapes.
摘要:
A method for precipitating ferrite at room temperature which involves dissolving metal salts in deaerated water, using a base solution to precipitate metal hydroxides, adding an oxidizing agent that has a standard reduction potential greater than 1.229 V versus standard hydrogen electrode. The oxidizing agent further preferably has a standard reduction potential less than 1.8 V versus standard hydrogen electrode. The oxidizing agent is preferably one of hydrogen peroxide, ammonium peroxydisulfate, ozone, nitrous acid, NO, and N.sub.2 O. The base is preferably ammonium hydroxide.
摘要:
An electrically conducting member (2) is insulated with a thin coating (6) of a resinous insulation composition containing a resin interactive with and bonded to an oligomer containing a metal of at least one of Cr, Sn and Zn, where the oligomer is within a silicate type mica or clay structure.
摘要:
Electrical circuit protection devices containing PTC elements comprised of conductive polymers which exhibit PTC behavior and are used to protect a load in an electrical circuit, in which the PTC conductive polymers are based on highly crystalline and highly ordered liquid crystal polymers and particulate conductive fillers dispersed therein, which are cross-linked by radiation. These circuit protection devices operate as automatically resettable current limiters and are particularly useful for protecting motors, solenoids, telephone lines and batteries, and for enhancing circuit interruption capability when used in conjunction with breakers and contactors. The liquid crystal polymers include aromatic polyesters, e.g., poly(p-phenylene terephthalate) and poly(p-hydroxybenzoate); aromatic copolyesters, e.g., poly(p-hydroxybenzoate-co-2,6-hydroxynaphthoate), poly(deca-methyleneterephthaloyl di-p-hydroxybenzoate, and poly(ethylene terephthalate-co-oxybenzoate); aromatic copolyester amides, e.g., poly(2,6-hydroxy-naphoate-phenoxyaminoterephthoate); aromatic polyamides, e.g., poly(p-phenylene terephthalamide), Kevlar, poly(p-benzamide), poly(2-chloro-1,4-phenylene terephthalamide), poly(p,p'-biphenylamide), and poly(2,6-napthalamide); aromaticpolyazomethines, e.g., poly (nitro-2-methyl-1,4-phenylenenitriloethylidine-1,4-phenylenethylidine), poly(nitrilo-2-methyl-1,4-phenylenenitrilomethylidine-1,4-phenylenemethylidine), and poly(nitrolo-2-chloro-1,4-phenylenenitrilomethylidine-1,4-phenylenemethylidine); and, blends thereof. The particulate conductive fillers include carbon black, carbon fibers, graphite, and metal flakes.
摘要:
A catalyzed mica tape used in insulating electrical conducting devices is made from a mica paper bonded to a backing with a bonding resin. The bonding resin is cross-linkable by an addition reaction. The catalyzed mica tape has distributed therein at least a catalyst at a concentration of greater than 0.01 g/m.sup.2 for every 100 g/m.sup.2 of the bonding resin. The catalyst is an organo-transition metal compound, organo-tin compound, or a combination thereof.
摘要翻译:用于绝缘导电装置的催化云母带由用粘合树脂粘合到背衬上的云母纸制成。 粘合树脂通过加成反应可交联。 对于每100g / m2的粘合树脂,催化云母带至少分布有浓度大于0.01g / m 2的催化剂。 催化剂是有机过渡金属化合物,有机锡化合物或其组合。
摘要:
The present invention is directed to conductive polymer composition that have positive temperature coefficients, electrical devices comprised thereof and methods of making the same. The composition comprises a thermoset polymer matrix containing discretely distributed thermoplastic material and dispersed conductive material. Preferably, the thermoset and thermoplastic polymers are substantially immiscible and have comparable volume transition temperatures, such as bisphenol A liquid epoxy resins and oxidized polyethylene.
摘要:
A resin-rich electrically conductive felt material is described. The described conductive felt can be used to suppress corona discharge in high voltage generator coils. The conductive felt is prepared by treatment with electrically conducting polymers, such as polyaniline and polypyrrole, and resistivity values ranging from 4,000 to 100,000 ohms may be obtained. This treated felt can be readily impregnated with thermoset resins, such as epoxies, to provide flexible prepregs suitable for coil bonding applications in turbine generators.
摘要:
Novel conductive liquid compositions which have low resistivity when carrying an applied steady-state current (I.sub.Steady-State) but exhibit sharp increases in resistivity when subject to an applied fault current (I.sub.Fault). When used in circuit protection devices, the novel conductive liquid compositions having low resistivity are contained within an elongated flexible tube sealed by electrodes electrically connected to a load of an electrical circuit. The conductive liquid compositions carry an applied normal current under steady-state conditions. The flexible tube is deformed by radial contraction transverse to the direction of current flow and axial expansion, when an excessive current of fault magnitude is sensed by an actuator electrically connected to the electrodes and mechanically connected to the flexible tube to apply a deformation force on the tube, thereby causing the current path of the conductive liquid compositions to have high resistivity in order to limit the let through current to a safe value (I.sub.Limited). When the excessive current is removed, the deformation is correspondingly removed and the conductive liquid composition automatically reverts back to its original low resistivity state. The invention has specific applications as automatically resettable fuses or current limiters.
摘要:
The invention provides an electrical circuit protection device using a conductive liquid contained in a flexible tube contacted and sealed at each end by an annular metal electrode capped by a flexible membrane. The flexible tube is further sealed inside a solid insulating tube which contains a ferromagnetic liquid. The ferromagnetic liquid surrounds the flexible tube and remains in intimate contact with the outside of the flexible tube and is connected to a load sensing element which generates a magnetic field in the ferromagnetic fluid in response to excessive currents applied in the current path through the conductive liquid between the electrodes. This assembly is contained inside a tubular resistor. Under normal current conditions, a current flows through the conductive liquid which has relatively low resistivity. Upon a fault condition, a self generated magnetic field from the fault current causes the ferromagnetic fluid to rapidly constrict and pinch off current flow in the conductive liquid by constricting the current path in the liquid through deformation of the flexible capsule, i.e., by radial contraction and axial expansion. The current is then preferably commutated to the cylindrical resistor to limit the let through current to a safe value. Once the fault is limited, the magnetic field is dissipated and the flexible membranes force the conductive liquid and ferromagnetic fluid back to its their original position and the conductive liquid accordingly automatically reverts back to low resistivity for normal current conduction.