摘要:
Embodiments of glass ceramic articles and precursor glasses are disclosed. In one or more embodiments, the glass-ceramic articles are transparent and include a nepheline phase and a phosphate phase. The glass-ceramic articles are colorless and exhibit a transmittance of about 70% or greater across the visible spectrum. The glass-ceramic articles may optionally include a lithium aluminosilicate phase. The crystals of the glass-ceramic articles may have a major cross-section of about 100 nm or less.
摘要:
Embodiments of glass ceramic articles and precursor glasses are disclosed. In one or more embodiments, the glass-ceramic articles are transparent and include a nepheline phase and a phosphate phase. The glass-ceramic articles are colorless and exhibit a transmittance of about 70% or greater across the visible spectrum. The glass-ceramic articles may optionally include a lithium aluminosilicate phase. The crystals of the glass-ceramic articles may have a major cross-section of about 100 nm or less.
摘要:
Disclosed herein are opaque glass-ceramics comprising at least one nepheline crystal phase and comprising from about 30 mol % to about 65 mol % SiO2, from about 15 mol % to about 40 mol % Al2O3, from about 10 mol % to about 20 mol % (Na2O+K2O), and from about 1 mol % to about 10 mol % (ZnO+MgO). Also disclosed herein are opaque-glass ceramics comprising at least one nepheline crystal phase and at least one spinel-structure phase doped with at least one colorant chosen from transition metals and rare earth elements. Further disclosed herein are methods for making these opaque glass-ceramics.
摘要:
The colorless transparent colloid-former-containing glass that is convertible into a colorless transparent glass ceramic or a metal colloid-colored glass ceramic via respective heat treatments contains a combination of one or more metal colloid formers and one or more redox partners. The metal colloid formers are compounds containing Au, Ag, As, Bi, Nb, Cu, Fe, Pd, Pt, Sb and/or Sn. The redox partners are compounds containing As, Ce, Fe, Mn, Sb, Sn and/or W, with the proviso that the redox partner must be different from the metal colloid former.
摘要:
Oxychlorination catalyst compositions which include a catalytically effective amount of an oxychlorination catalyst and a diluent having certain chemical composition and/or physical properties are disclosed. Processes using such oxychlorination catalyst compositions are also described. Some oxychlorination catalyst compositions and processes disclosed herein can increase the optimal operating temperature, and thereby increase the production capacity of an existing reactor, such as a fluid-bed reactor, compared to other oxychlorination catalyst compositions.
摘要:
A dental porcelain composition, comprising a glassy matrix and leucite crystallites embedded therein, and having maturing temperatures in the range from about 600.degree. C. to about 885.degree. C. and CTEs in the range from about 11 to about 19, more preferably in the range from about 11.5 to about 18, and most preferably in the range from about 12 to about 17.5.times.10.sup.-6 /.degree.C. (measured from 25.degree. C. to 500.degree. C.). The tetragonal leucite is preferably both fine-grained (i.e, having average diameters of less than about 7 microns) and uniformly-sized. Preferably, the average diameters are less than about 1 to about 3 microns.
摘要:
The invention relates to a glass ceramic in which mica and ZrO.sub.2 are present in crystallized form, containing:K.sub.2 O: 0-9% by weightNa.sub.2 O: 0-9% by weight with the condition that Na.sub.2 O and K.sub.2 O together make up at least about 4% by weight,SiO.sub.2 : 35-60% by weightMgO: 10-25% by weightAl.sub.2 O.sub.3 : 7-30% by weightZrO2: 4-12% by weightF.sup.- : 2-10% by weight which is essentially free of lithium, calcium, strontium and barium, to a process for its production and to its use as a tooth replacement.
摘要:
A leucite-containing phosphosilicate glass-ceramic is described which, in addition to a leucite crystalline phase and at least one further crystalline phase, also contains one or more glass phases.
摘要:
A two-phase porcelain composition for dental restorations comprising a leucite crystallite phase dispersed in a feldspathic glass matrix, a maturing temperature of from about 750.degree. to about 1050.degree. C. and a coefficient of thermal expansion of from about 12.times.10.sup.-6 /.degree.C. to about 17.5.times.10.sup.-6 /.degree.C., said porcelain composition comprising:______________________________________ Component Amount (wt. %) ______________________________________ SiO.sub.2 57-66 Al.sub.2 O.sub.3 7-15 K.sub.2 O 7-15 Na.sub.2 O 7-12 Li.sub.2 O 0.5-3 CaO 0-3 MgO 0-7 F 0-4 CeO.sub.2 0-1 ______________________________________ wherein the leucite crystallites possess diameters not exceeding about 10 microns and represent from about 5 to about 65 weight percent of the two-phase porcelain composition.
摘要:
Alkali-zinc-silicate glass ceramics and glasses are described which have a linear thermal expansion coefficient in the range from 8.0 to 18.7.times.10.sup.-6 K.sup.-1, an excellent chemical resistance and other advantageous optical properties and can be used in particular as dental material.