The rate of rod fallover in the production of polycrystalline silicon by the Siemens process is sharply reduced by cleaning the Siemens reactor base plate by at least a two-step procedure comprising suctioning the base plate in one step, and subsequently cleaning with liquid or solid cleaning medium in a second step, between each phase of rod removal and new support body installation.

The rate of rod fallover in the production of polycrystalline silicon by the Siemens process is sharply reduced by cleaning the Siemens reactor base plate by at least a two-step procedure comprising suctioning the base plate in one step, and subsequently cleaning with liquid or solid cleaning medium in a second step, between each phase of rod removal and new support body installation.

Siemens CVD reactors are sealed in a manner which facilitates long production campaigns without refurbishing the seals, by the use of at least two seals, and an electrically insulating member having a thermal conductivity of from 1 to 200 W/mK, a sustained use temperature of at least 400° C., and a resistivity of more than 1-10.sup.9 Ωcm.

Siemens CVD reactors are sealed in a manner which facilitates long production campaigns without refurbishing the seals, by the use of at least two seals, and an electrically insulating member having a thermal conductivity of from 1 to 200 W/mK, a sustained use temperature of at least 400° C., and a resistivity of more than 1-10.sup.9 Ωcm.

Particulate composite materials and devices comprising the same are provided.

Particulate composite materials and devices comprising the same are provided.

A device for the installation of rock bolts includes a supporting structure and first and second bolting units mounted to the supporting structure. Each bolting unit is configured for drilling an installation hole and/or for installing a rock bolt into a rock face, wherein the supporting structure is configured for rotatably moving the first and second bolting units about a common axis of rotation. At least one actuator is mounted to the supporting structure and configured for additionally moving at least one of the first and second bolting units.

Efficiency of producing polycrystalline silicon is improved. A silicon filament (11) is constituted by a rod-shaped member made of polycrystalline silicon. The polycrystalline silicon has an interstitial oxygen concentration of not less than 10 ppma and not more than 40 ppma. On a side surface, in a lengthwise direction, of the rod-shaped member, crystal grains each having a crystal grain size of not less than 1 mm are observed.

Efficiency of producing polycrystalline silicon is improved. A silicon filament (11) is constituted by a rod-shaped member made of polycrystalline silicon. The polycrystalline silicon has an interstitial oxygen concentration of not less than 10 ppma and not more than 40 ppma. On a side surface, in a lengthwise direction, of the rod-shaped member, crystal grains each having a crystal grain size of not less than 1 mm are observed.

In a process for producing a silicon single crystal in which carbon is incorporated in order to inhibit crystal defects, provided is a process which easily allows carbon to be mixed and dissolved into a silicon melt. The process for producing a silicon single crystal, which involves allowing a silicon single crystal to grow during its pulling-up from the silicon melt held in a crucible, uses as at least part of a silicon raw material, crushed materials of a polycrystalline silicon rod produced by Siemens process that are obtained by crushing an end of the rod in the vicinity contacting a carbon core wire holding member.