Patent GB-1007868-A (GB)
Title: Improvements in and relating to luminescent glass bodies
IPC: C03C21/00
Filed: 1963-02-28
Abstract: A glass body is heat treated to give a surface layer only of luminescent crystals.  The treatment may be by (1) steam autoclaving in a steam atmosphere of over 25 p.s.i., a steam partial pressure at a temperature between 500 DEG  and 50 DEG  F. below the fibre softening point of the glass, (2) immersion in a molten salt bath containing the lithium ion, (3) heating the one surface while keeping the other portions of the body at a lower temperature at which crystals do not form, (4) direct flame treatment, the flame and surfaces being relatively moved to give uniform surface heating and treatment being continued till the required depth of the surface layer has become crystalline, (5) heating for relatively lengthy periods at temperatures below the softening point of the glass or (6) immersion in a furnace, preheated to the crystallization temperature, until the required depth has become crystalline or by repeated immersion and cooling to give the depth required.  The thickness of the layer may be less than 10 microns or up to 0.3 inches, usually 100-500 microns.  The following are suitable glasses with ranges of constituents in percentages by weight.  Zinc silicate glasses: SiO2 38.1 to 68.5; ZnO 21.4 to 49.9; MnO 0.1 to 1.9; Na2O to 11.7; NaF 0 to 5; Al2O3 0 to 4.8; B2O3 0 to 6.7; SnO2 0 to 4.5; Li2 0 to 5; BeO 0 to 6.5; SrO 0 to 7.1; CaO 0 to 8; PbO 0 to 8.5; TiO2 0 to 3.  Calcium silicate glasses: SiO2 48.2 to 71.5; CaO 19.6 to 45.3; MnO 0.3 to 2.9; PbO 0 to 8; Na2O 0 to 10.2; ZnO 0 to 2.2; Li2O 0 to 14.6; B2O3 0 to 5; MgO 0 to 7; Al2O3 0 to 5.  Lead barium silicate glasses: SiO2 33.6 to 43; PbO 23.2 to 43.3; BaO 19.8 to 39.6; MnO 0 to 0.25; Li2O 0 to 1.6; Al2O3 0 to 4.9; Sb2O3 0 to 12.9; Au 0 to 0.027.  Calcium tungstate glasses: SiO2 43.7 to 57.3; CaO 24.3 to 35; WO3 10.6 to 15.5; Al2O3 2 to 4.3; PbO 1.1 to 5.6; MgO 0 to 2.7; Na2O 0 to 8; MnO 0 to 1.06; Li2O 0 to 5.7.  Cadmium borate glasses: SiO2 0 to 9.9; CdO 59.8 to 68; B2O3 28.1 to 39.9; MnO 0.25; Al2O3 0 to 5. Zinc borate glasses: ZnO 49.5 to 64.2; B2O3 27.4 to 42.7; MnO 0.3 to 1.6; SiO2 0 to 7.9; Al2O3 0 to 13; PbO <FORM:1007868/C4-C5/1> 2.6.  Calcium phosphate glasses: P2O5 5.7 to 73; CaO to 43.9; CaF2 0 to 3; SiO2 0 to 58.5; Al2O3 0 to 23; Na2O 0 to 7 with one or more activators selected from MnO, SnO2, Sb2O3 and Dy2O3 0.3 to 3.2.  Zinc vanadate glasses: as example ZnO 70.7; V2O5 23.6; B2O3 5.7. Zinc aluminate glasses: as examples, ZnO 48.2; Al2O3 16.6; B2O3 34.7; MnO 0.7 or th same with SrO 15.1 replacing part of ZnO. Calcium magnesium silicate glasses: as Examples (1) and (2) MgO 14, 18; CaO 24, 25; SiO2 54.2, 53.7; Al2O3 4.9, 0; TiO2 3, 3. Mixtures are also referred to, particularly for giving white luminescence by mixtures having suitable colour luminescence.  A large range of colour luminescence can be obtained from the above glasses by irradiation with electro magnetic and particle radiations such as ultraviolet rays, X-rays, cathode rays, alpha rays, beta rays, gamma rays or with protons, neutrons and deuterons.  The glass bodies have particular use for cathode ray tube face plates and can also be used for measurement and detection of, for example, alpha and gamma ray radiations. In a fluorescent lighting tube, a 1 1/2 inch O.D. tubing of wall thickness 0.02 inch is drawn and a molten eutectic mixture of CaCl2, LiCl to give a tube with thin translucent crystals which, when energized, is a yellow colour.  A viewing plate of a cathode-ray tube was surface crystallized under steam pressure, the crystals on the viewing side being removed by grinding and polishing.ALSO:A glass body is heat treated to give a surface layer only of luminescent crystals.  The treatment may be by (1) steam autoclaving in a steam atmosphere of over 25 p.s.i.a. steam partial pressure at a temperature between 500 DEG  F. and 50 DEG  F. below the fibre softening point of the glass, (2) immersion in a molten salt bath containing the lithium ion, (3) heating the one surface while keeping the other portions of the body at a lower temperature at which crystals do not form, (4) direct flame treatment, the flame and surface being relatively moved to give uniform surface heating and treatment being continued till the required depth of the surface layer has become crystalline, (5) heating for relatively lengthy periods at temperatures below the softening point of the glass or (6) immersion in a furnace, preheated to the crystallization temperature, until the required depth has become crystalline or by repeated immersion and cooling to give the depth required.  The thickness of the layer may be less than 10 microns or up to 0.3 inches, usually 100-500 microns.  The following are suitable glasses with ranges of constituents in percentages by weight.  Zinc silicate glasses: SiO2 38.1 to 68.5; ZnO 21.4 to 49.9; MnO 0.1 to 1.9; Na2O 0 to 11.7; NaF 0 to 5; Al2O3 0 to 4.8; B2O3 0 to 6.7; SnO2 0 to 4.5; Li2O 0 to 5; BeO 0 to 6.5; SrO 0 to 7.1; CaO 0 to 8; PbO 0 to 8.5; TiO2 0 to 3.  Calcium silicate glasses:  SiO2 48.2 to 71.5; CaO 19.6 to 45.3; MnO 0.3 to 2.9; PbO 0 to 8; Na2O 0 to 10.2; ZnO 0 to 2.2; Li2O 0 to 14.6; B2O3 0 to 5; MgO 0 to 7; Al2O3 0 to 5.  Lead barium silicate glasses: SiO2 33.6 to 43; PbO 23.2 to 43.3; BaO 19.8 to 39.6; MnO 0 to 0.25; Li2O 0 to 1.6; Al2O3 0 to 4.9; Sb2O3 0 to 12.9; Au 0 to 0.027.  Calcium tungstate glasses:  SiO2 43.7 to 57.3; CaO 24.3 to 35; WO3 10.6 to 15.5; Al2O3 2 to 4.3; PbO 1.1 to 5.6; MgO 0 to 2.7; Na2O 0 to 8; MnO 0 to 1.06; Li2O 0 to 5.7. Cadmium borate glasses:  SiO2 0 to 9.9; CdO 59.8 to 68; B2O3 28.1 to 39.9; MnO 0.25; Al2O3 0 to 5. Zinc borate glasses:  ZnO 49.5 to 64.2; B2O3 27.4 to 42.7; MnO 0.3 to 1.6; SiO2 0 to 7.9; Al2O3 0 to 13; PbO 0 to 2; Na2O 0 to 1.7; F 0 to 7.1; SnO2 0 to 2.6. Calcium phosphate glasses:  P2O5 5.7 to 73; CaO 0 to 43.9; CaF2 0 to 3; SiO2 0 to 58.5; Al2O3 0 to 23; Na2O 0 to 7 with one or more activators selected from MnO, SnO2, Sb2O3 and Dy2O3 0.3 to 3.2.  Zinc vanadate glasses: as example ZnO 70.7; V2O5 23.6; B2O3 5.7.  Zinc aluminate glasses:  as examples, ZnO 48.2; Al2O3 16.6; B2O3 34.7; MnO 0.7, or the sam with SrO 15.1 replacing part of ZnO.  Calcium magnesium silicate glasses: as examples (1) and (2), MgO 14, 18; CaO 24, 25; SiO2 54-2, 53.7; Al2O3 4.9, 0; TiO2 3, 3.  Mixtures are also referred to, particularly for giving white luminescence by mixtures having suitable colour luminescence.  A large range of colour luminescence can be obtained from the above glasses by irradiation with electromagnetic and particle radiations such as ultra-violet rays, X-rays, cathode rays, alpha rays, beta rays, gamma rays or with protons, neutrons and deuterons.  The glass bodies have particular use for cathode-ray tube face plates and can also be used for measurement and detection of, for example, alpha and gamma ray radiations.