| 摘要 |
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 DEG F. and below 5500 DEG F. and subsequently cooling the resultant coherent shape below 3000 DEG 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. In an igniter formed by the use of a laser, the rind, which appears to be bonded together by quartz rather than by the regrowth of silicon carbide which characterizes the core, is removed, and the core, formed through at least a part of its reach in a serpentine pattern, is densified. The core has a valley or groove formed in it as it is being made, which extends through the surface upon which the laser beam impinges and has characteristically distinct regions along the walls defining the valley or groove. The valley or groove, being formed as the shape or element is formed by the laser, is continuous and follows the configuration of the surface of the shape or element through which the groove or valley opens.
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