Abstract: A seed retaining member has a recessed portion for breaking and separating formed at an arbitrary location and thereby allows stress concentration to occur at the recessed portion when applying a breaking load, to enable the seed retaining member to break with a smaller load than conventional. So that the seed retaining member can prevent a crack from propagating in an unintended location in the seed retaining member by allowing the crack to propagate along the recessed portion, and also can reduce a workload in a separation work of the seed retaining member and polycrystalline silicon. The seed retaining member for retaining a lower end portion of a seed serving as a seed rod and disposed at a bottom portion of a furnace for producing polycrystalline silicon by a Siemens method. A groove for breaking and separating is formed in an outer peripheral surface of the seed retaining member.

Abstract: An object of the invention is to provide a heat generator having an expanded graphite sheet which is excellent in mechanical strength and flexibility and which is satisfactory in electrical properties as required by a heater, and especially a heat generator which is usable as a heater for the seats of vehicles, and the object of the invention can be achieved by forming an electrical insulating reinforcement on at least one surface of the expanded graphite sheet.

Abstract: An object of the invention is to provide a heat generator having an expanded graphite sheet which is excellent in mechanical strength and flexibility and which is satisfactory in electrical properties as required by a heater, and especially a heat generator which is usable as a heater for the seats of vehicles, and the object of the invention can be achieved by forming an electrical insulating reinforcement on at least one surface of the expanded graphite sheet.