Gte Laboratories Incorporated

Gte Control Devices Incorporated

Thomas R Middleton

Burton W MacAllister, Jr

Da Y Wang

Daniel T Kennedy

Brian M Ditchek

A method of making a positive temperature coefficient of resistance (PTCR) device, and the PTCR device itself, where there is provided a ferroelectric semiconductor having a Curie point and a bulk resistance. A layer of electrically conducting material is provided upon the ferroelectric semiconductor. The layer is heated at a process temperature greater than the Curie point of the ferroelectric semiconductor for a period of time, and cooled to ambient temperature. The process temperature and time period are selected to be sufficent to provide an ambient layer resistance greater than the bulk resistance of the ferroelectric semiconductor. The layer may be heated in an oxidizing atmosphere or in a reducing atmosphere, which also affects the layer resistance. The ferroelectric semiconductor may be in the form of an oxide ceramic or liquid crystals, and may include barium titanate. The layer may be selected from the group consisting of metal, metal alloys, metal oxides, polymers, and composites thereof.

Method of making semiconducting ferroelectric PTCR devices

A method of making a positive temperature coefficient of resistance (PTCR) device,and the PTCR device itself, where there is provided a ferroelectric semiconductor having a Curie point and a bulk resistance. A layer of electrically conducting material is provided upon the ferroelectric semiconductor. The layer is heated at a process temperature greater than the Curie point of the ferroelectric semiconductor for a period of time. End cooled to ambient temperature. The process temperature and time period are selected to be sufficient to provide an ambient layer resistance greater than the bulk resistance of the ferroelectric semiconductor. The layer may be heated in an oxidizing atmosphere or in a reducing atmosphere which also affects the layer resistance. The ferroelectric semiconductor may be in the form of an oxide ceramic or liquid crystals, and may include barium titanate. The layer may be selected from the group consisting of metal, metal alloys, metal oxides, polymers, and composites thereof.

PTCR device

This invention provides a method of welding an electric feedthrough assembly for an electric lamp. The feedthrough assembly comprises at least a plug and an electrode pin, each being formed from an electrically conductive refractory material, such as a molybdenum-titanium-nickel plug and a tungsten electrode pin. In a preferred embodiment of the invention, the electrode pin is inserted into a chuck of a drill press. The plug is placed on a rubber pad with the cavity in the plug aligned under the electrode pin. The electrode pin is rotated and pressed into the cavity with increasing pressure until the plug commences rotating on the rubber pad. Substantial heat is generated within the cavity by friction between the rotating electrode pin and the stationary surface of the plug within the cavity. As the pressure is increased on the electrode pin, intimate contact between the materials is attained. The materials melt at the surfaces where friction occurs; the coefficient of friction in fluid decreases; production of heat ceases; the molten materials cool and fuse together whereupon the plug commences rotating. The rubber pad inhibits rotation of the plug only when the torque on the plug is less than a threshold value, i.e., prior to fusion of the plug and electrode pin.

Method of friction welding a lamp feedthrough assembly

Boron, oxygen, or a mixture thereof, is used as a sintering aid in sintering Mo-Ti alloys. Compounds formed between these sintering aids and the Mo or Ti have thermal expansion coefficients consistent with that of alloys of Mo and Ti. An hermetic member may be made using these constituents. The hermetic member may be used to seal an assembly such as a high pressure sodium lamp.

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Peabody, MA, United States of America

Thomas R Middleton