Abstract: The invention relates to a borosilicate glass of high chemical resistance and low viscosity which contains zirconium oxide and lithium oxide. The borosilicate glass has hydrolytic resistance (in accordance with DIN ISO 719), class 1 acid resistance (in accordance with DIN 12116), and class 1 alkali resistance (in accordance with DIN ISO 659), and with a low operating temperature V.sub.A of between 1180.degree. C. to 1230.degree. C. and a coefficient of thermal expansion .alpha..sub.20/300 of 4.9.times.10.sup.-6 K.sup.-1. The borosilicate glass has the composition (in % by weight, based on oxide): SiO.sub.2 73-75; B.sub.2 0.sub.3 7-10; Al.sub.2 0.sub.3 5-7; ZrO.sub.2 1-3; Li.sub.2 0 0.5-1.5; Na.sub.2 0 0-10; K.sub.2 0 0-10; MgO 0-3; CaO 0-3; BaO 0-3; SrO 0-3; ZnO 0-3; ratio of SiO.sub.2 /B.sub.2 0.sub.3 .gtoreq.7.5; .SIGMA. SiO.sub.2 +Al.sub.2 0.sub.3 +ZrO.sub.2 80-83 and .SIGMA. MgO+CaO+BaO+SrO+ZnO.ltoreq.3, and fluorides 0-3.

Abstract: The invention relates to brownish, brown to black colored borosilicate glasses which have stepped grades of transmission in the NIR range or are fully non-transmitting. The borosilicate glass, primarily the borosilicate glass 3.3, is melted with defined additives of titanium carbide and/or metallic silicon. The glasses produced in accordance with the invention are to be used as filters, glass vessels and/or decorative colored glass in construction and for decorating because of their absorption/transmission characteristics. On the other hand, the glasses produced in accordance with the invention can also be used as absorbers in solar technology when the light transmissibility in the NIR/IR range is sufficiently low.

Abstract: Borosilicate glass weak in boric acid having a high chemical stability with an alkali resistance according to DIN 52 322 of LBK-Class 1, a thermal expansion .alpha..sub.20/300 between 4.0 to 5.3.times.10.sup.-6 K.sup.-1, a ratio .alpha.'/.alpha. of thermal expansion coefficients above T.sub.g (.alpha.') to below T.sub.g (.alpha.) of 4 to 8, a glass transformation temperature between 500.degree. C. and 600.degree. C., high radiation transmittance and a UV transmission .tau..sub.250 nm/1 mm of 0 to 70% or .tau..sub.300 nm/1 mm of 0 to 91% of the composition in percent by weight on oxide basis of: SiO.sub.2 >75; B.sub.2 O.sub.3 1 to <9; Al.sub.2 O.sub.3 3 to 6; Li.sub.2 O 0 to 4; Na.sub.2 O 0 to 8; K.sub.2 O 0 to 6; MgO 0 to 3; CaO 0 to 3; BaO 0 to 2; SrO 0 to 2; ZnO 0 to 3; ZrO.sub.2 0 to 3; SnO.sub.2 0 to 3; SnO 0 to 3; TiO.sub.2 0 to 2; CeO.sub.2 0 to 2; Fe.sub.2 O.sub.3 0 to 1; with SiO.sub.2 +B.sub.2 O.sub.3 >83; SiO.sub.2 :B.sub.2 O.sub.3 >8; SiO.sub.2 +Al.sub.2 O.sub.3 +ZrO.sub.2 >83; Li.