Abstract: Silicon carbide shapes of the general type shown and described in U.S. Pat. No. 4,125,756 are densified and nitrided in such a way as to produce shapes with improved durability and reduction in temperature span in response to voltage changes.

Abstract: An electrical resistance heater or igniter characterized by having a core bonded by regrowth of silicon carbide is produced by heating particulate silicon carbide which may be mixed with a minor amount of modifying agent, by means of an uncharged beam of energy, to a temperature above 3000.degree. F. and below 5500.degree. F. and subsequently cooling the resultant coherent shape below 3000.degree. F., both stops being completed within a period of ten minutes. In the preferred method, unconsolidated particulate silicon carbide is exposed to the energy of a laser beam and the particulate silicon carbide has a particle size within the range of magnitude of ten to three hundred microns. Upon its initial formation, the shape or element has a core and a distinctly delineated rind which is attached to the core. The core has a relatively low resistivity as compared with the rind.

Abstract: Silicon carbide shapes of the general type shown and described in U.S. Pat. No. 4,125,756 are densified and nitrided in such a way as to produce shapes with improved durability and reduction in temperature span in response to voltage changes.

Abstract: An electrical exceptance heater or igniter characterized by having a core bonded by regrowth of silicon carbide is produced by heating particulate silicon carbide which may be mixed with a minor amount of modifying agent, by means of an uncharged beam of energy, to a temperature above 3000.degree. F. and below 5500.degree. F. and subsequently cooling the resultant coherent shape below 3000.degree. F., both steps being completed within a period of ten minutes. In the preferred method, unconsolidated particulate silicon carbide is exposed to the energy of a laser beam and the particulate silicon carbide has a particulate size within the range of magnitude of ten to three hundred microns. Upon its initial formation, the shape or element has a core and a distinctly delineated rind which is attached to the core. The core has a relatively low resistivity as compared with the rind.

Abstract: A coherent shape or element of a composition characterized by having a core bonded by regrowth of silicon carbide is produced by heating particulate silicon carbide which may be mixed with a minor amount of modifying agent, by means of an uncharged beam of energy, to a temperature above 3000.degree. F. and below 5500.degree. F. and subsequently cooling the resultant coherent shape below 3000.degree. F., both steps being completed within a period of ten minutes. In the preferred method, unconsolidated particulate silicon carbide is exposed to the energy of a laser beam and the particulate silicon carbide has a particle size within the range of magnitude of ten to three hundred microns. Upon its initial formation, the shape or element has a core and a distinctly delineated rind which is attached to the core. The core has a relatively low resistivity as compared with the rind.

Abstract: A coherent shape of a composition characterized by having a core bonded by regrowth of silicon carbide is produced by heating particulate silicon carbide which may be mixed with a minor amount of modifying agent, by means of an uncharged beam of energy, to a temperature above 3000.degree. F. and below 5500.degree. F. and subsequently cooling the resultant coherent shape below 3000.degree. F., both steps being completed within a period of 10 minutes. In the preferred method, unconsolidated particulate silicon carbide is exposed to the energy of a laser beam and the particulate silicon carbide has a particle size within the range of magnitude of 10 to 300 microns. Upon its initial formation, the shape has a core and a distinctly delineated rind which is attached to the core. The core has a relatively low resistivity as compared with the rind.