Akzo N.v.

Akzona Incorporated

Hans-Dieter Achtsnit

Diederich Schilo

Arno Wegerhoff

Gerhard Klug

Fibrous silicon dioxide material that is resistant to high temperatures, particularly in the form of mats or plates, is produced by dry-spinning water glass into water glass fibers, the water glass fibers being then transformed into silica fibers by treatment with aqueous acid or salt solutions that contain hydrogen ions. The silica fibers are thereupon treated with an agent that accelerates the formation of cristobalite from amorphous silica. Such agents include, in particular, alkali hydrogen phosphates, sodium acetate and solium chloride. The fibers are dried and dehydrated at temperatures above 600.degree. C., particularly between 950.degree. C. and 1050.degree. C., before or after treatment with the accelerating agent. There dehydration occurs after such treatment, the fibers are subsequently subjected to thermal aftertreatment. When subjected to 1500.degree. C. temperatures, the material thus obtained generally shrinks by less than 3%; it has very little tendency to become brittle and is particularly well suited for the fabrication of high temperature insulation material.

High temperature-resistant fibrous silicon dioxide material

Production of drawn dilaments by cooling freshly spun filaments at a temperature below the setting point and taking them off at 3500 m/min while passing them over heated surfaces, such heated surfaces being 20 to 300 mm long heated to from 450.degree. to 650.degree. C. and arranged at a distance of from 1500 to 6500 mm from the spinneret.

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Elsenfeld-Eichelsbach, Germany

Hans-Dieter Achtsnit