Abstract: A ceramifiable sizing composition includes, in % by weight:a) 5.5 to 20% of at least one water-soluble metal salt chosen from chromium, zirconium, titanium and aluminum salts;b) 0.2 to 15% of at least one binding agent;c) 0.15 to 3% of at least one silane giving the continuous inorganic yarn good properties of resistance to abrasion and of tensile strength of dry yarn;d) 0.6 to 17% of at least one lubricating agent; ande) a balance of water.

Abstract: Apparatus for removing a fused silica glass object from a rotating pot has a gripping member which grips the upper rim of the fused silica glass object and a rotational synchronization member connected to the gripping member which is lowered vertically into frictional contact with the rotating pot. The rotation of the pot drives the rotation of the synchronization member which drives the rotation of the gripping member. The object can be withdrawn vertically from the pot without the angular velocities of the object and pot diverging.

Abstract: This invention relates to a method of making an object of silica glass, such as a crucible, according to which a pot capable of rotating about its axis is filled with a refractory pulverulent material. The pot is rotated and a cylindrical cavity is formed in the material, the axis of which coincides with that of the pot. The bottom and the wall of the cavity are then formed to a certain thickness with a silica-rich material. This silica-rich material is melted, the object thus produced is cooled and then extracted vertically by an extraction mechanism comprising a gripping member which is rotating, at least initially, at the same speed as the pot.

Abstract: A process is described for making a doped-silica ingot useful in the manufacture of optical fibers. At least a silicon compound and a titanium compound are decomposed in the flame of the induction plasma burner in the presence of a determined supply of hydrogen and are reacted with the oxygen contained in the burner feed gas and/or in the vector gas to form SiO.sub.2 and H.sub.2 O against a heat-stable support. As a result silica and titanium oxide are deposited on the support in the form of a homogeneous vitreous mass exhibiting a selected concentration of hydroxyl groups between 10 and 50 parts per million. Fluorine-doped silica is deposited radially in the same way on the resulting ingot. The resulting semifinished product is a cylinder consisting of a titanium-doped silica core, whose TiO.sub.2 concentration by weight is about 0.1 to 8%, covered by a sheath of fluorine-doped silica, whose fluorine concentration is about 0.1 to 3%.