One aspect relates to a process for the preparation of a quartz glass body. The process includes providing a silicon dioxide granulate I prepared from a pyrogenically produced silicon dioxide powder, treating the silicon dioxide granulate I with a reactant at a temperature in a range from 1000 to 1300° C., and making a glass melt out of the silicon dioxide granulate. A quartz glass body is made out of at least a part of the glass melt. Furthermore, one aspect relates to a quartz glass body obtainable by this process. Furthermore, one aspect relates to a light guide, an illuminant, and a formed body, each of which is obtainable by further processing of the quartz glass body. One aspect additionally relates to a process for the preparation of a silicon dioxide granulate II.

A glass tube element having a hollow cylindrical section with a shell having an outer diameter is provided. A first ratio is a difference value to a mean value. The difference value is a difference of a minimal and maximal value of the outer diameter. The mean value is a mean of the minimal and maximal values. A sub-section having a start, an end, and a distance of 1 meter measured along a straight line from the start to the end and intersecting with a center axis of the sub-section at the start and the end. The sub-section having, for every point of the center axis, a shortest distance to the straight line. A second ratio of a specific distance to 1 meter, the specific distance being defined as a largest of all shortest distances. A product of the first and second ratio is smaller than 4×10.sup.−6.

A glass tube element having a hollow cylindrical section with a shell having an outer diameter is provided. A first ratio is a difference value to a mean value. The difference value is a difference of a minimal and maximal value of the outer diameter. The mean value is a mean of the minimal and maximal values. A sub-section having a start, an end, and a distance of 1 meter measured along a straight line from the start to the end and intersecting with a center axis of the sub-section at the start and the end. The sub-section having, for every point of the center axis, a shortest distance to the straight line. A second ratio of a specific distance to 1 meter, the specific distance being defined as a largest of all shortest distances. A product of the first and second ratio is smaller than 4×10.sup.−6.

An apparatus for the continuous production of hollow quartz-glass ingots, comprising a) a crucible or refractory tank for providing a softened quartz-glass mass having a dieorifice in the bottom of the crucible or refractory tank; b) a mandrel vertically drawing off the softened quartz-glass mass through a die toprovide a hollow quartz-glass ingot; and c) a cutting section for on-line cutting of the hollow quartz-glass ingot to a specificlength, characterized in that the apparatus comprises active means for cooling the internalsurface of the hollow quartz-glass ingot prior to the cutting station.

An apparatus for the continuous production of hollow quartz-glass ingots, comprising a) a crucible or refractory tank for providing a softened quartz-glass mass having a dieorifice in the bottom of the crucible or refractory tank; b) a mandrel vertically drawing off the softened quartz-glass mass through a die toprovide a hollow quartz-glass ingot; and c) a cutting section for on-line cutting of the hollow quartz-glass ingot to a specificlength, characterized in that the apparatus comprises active means for cooling the internalsurface of the hollow quartz-glass ingot prior to the cutting station.

The present invention relates to a continuous method for the production of hollow quartz-glass ingots and an apparatus for said method, whereby the hollow quartz-glass ingots are cooled on the internal surface.

The present invention relates to a continuous method for the production of hollow quartz-glass ingots and an apparatus for said method, whereby the hollow quartz-glass ingots are cooled on the internal surface.

A glass tube, such as a glass tube for the production of containers for storage of pharmaceutical compositions, facilitates production of pharmaceutical containers with high quality. The glass tube has a relative cross-sectional area deviation defined as

[00001]$\frac{{\mathrm{QF}}_{\max }-{\mathrm{QF}}_{\min }}{1.5m}.$

[00002]$\frac{{\mathrm{QF}}_{\max }-{\mathrm{QF}}_{\min }}{1.5m}$

is less than k*x+t. QF.sub.max is the highest cross-sectional area and QF.sub.min is the lowest cross-sectional area of at least two cross-sections of the glass tube, the cross-sections being spaced apart from each other along a length of the glass tube, and k is 0.0023 m.sup.−1, t is less than 0.15 mm.sup.2/m and x is

[00003]$\frac{{\mathrm{QF}}_{\max }+{\mathrm{QF}}_{\min }}{2}.$

A glass tube, such as a glass tube for the production of containers for storage of pharmaceutical compositions, facilitates production of pharmaceutical containers with high quality. The glass tube has a relative cross-sectional area deviation defined as

[00001]$\frac{{\mathrm{QF}}_{\max }-{\mathrm{QF}}_{\min }}{1.5m}.$

[00002]$\frac{{\mathrm{QF}}_{\max }-{\mathrm{QF}}_{\min }}{1.5m}$

is less than k*x+t. QF.sub.max is the highest cross-sectional area and QF.sub.min is the lowest cross-sectional area of at least two cross-sections of the glass tube, the cross-sections being spaced apart from each other along a length of the glass tube, and k is 0.0023 m.sup.−1, t is less than 0.15 mm.sup.2/m and x is

[00003]$\frac{{\mathrm{QF}}_{\max }+{\mathrm{QF}}_{\min }}{2}.$

A method includes depositing a glass frit on sidewalls of a plurality of cavities of a shaped article formed from a glass material, a glass ceramic material, or a combination thereof. The glass frit is heated to a firing temperature above a glass transition temperature of the glass frit to sinter the glass frit into a glaze disposed on the sidewalls of the plurality of cavities.