Abstract: The present disclosure relates to an alkali-aluminosilicate glass which contains between 47.5 and 55 wt.% SiO2, between 21 and 27.5% Al2O3; and between 12 and 16 wt.% Na2O. The molar ratio of Al2O3 and Na2O amounts to between 1:0.9 and 1:1.2. This glass is characterized by high hardness and high surface strengths after its chemical toughening, whereby the resulting extremely high scratch resistance favors its use as a display glass. A further preferred feature of this glass is its much lower viscosity for this group of glasses.

Abstract: The present disclosure relates to an alkali-aluminosilicate glass which contains between 47.5 and 55 wt.% SiO2, between 21 and 27.5% Al2O3; and between 12 and 16 wt.% Na2O. The molar ratio of Al2O3 and Na2O amounts to between 1:0.9 and 1:1.2. This glass is characterized by high hardness and high surface strengths after its chemical toughening, whereby the resulting extremely high scratch resistance favors its use as a display glass. A further preferred feature of this glass is its much lower viscosity for this group of glasses.

Abstract: Micaceous-cordierite-glass ceramic particularly suitable for stomatological, head surgery and neck surgery applicatiosn has a fracture toughness K.sub.IC of up to 2.0 MPa m.sup.1/2, a hardness HV.sub.0.07 of 300-1000, a compressive strength of up to 450 N/mm.sup.2, a linear thermal expansion coefficient of 75-125.times.10.sup.-7 K.sup.-1, good chemical stability and excellent machinability as well as a high resistance to wear and comprises a composition in weight percentages of______________________________________ SiO.sub.2 43-50 Al.sub.2 O.sub.3 26-30 MgO 11-15 R.sub.2 O 7-10.5 F.sup.- 3.3-4.8 Cl.sup.- 0.01-0.6 CaO 0.1-3 P.sub.2 O.sub.5 0.1-5 ______________________________________wherein R.sub.2 O is the sum of 3 to 5.5 wt. % Na.sub.2 O and 4 to 6 wt. % K.sub.2 O, a first crystal phase of mica, and a second crystal phase of 5 to 30 volume % cordierite, wherein relatively large mica crystals of 10 to 200 .mu.m are embedded in the glass and cordierite crystals of 0.5 to 5 .mu.m are arranged in the glass.

Abstract: The invention relates to inorganic-organic compound substances useful for biomedical purposes. The object of the invention is to develop inorganic-organic compound materials which overcome the disadvantages of the state of art, wherein inorganic-organic compound substances for biomedical purposes possess to a large extent specifically adjustable characteristics. Inorganic initial substances form a new solid chemical compound with organic initial substances. The inorganic initial component consists of a biocompatible silicate glass and/or a silicate glass ceramic of the system SiO.sub.2 -Al.sub.2 O.sub.3 -MgO-Na.sub.2 O/K.sub.2 O-F.sup.-, and/or a bioactive phosphate silicate glass and/or a phosphate silicate glass ceramic of the system SiO.sub.2 -Al.sub.2 O.sub.3 -MgO-Na.sub.2 O/K.sub.2 O-CaO-P.sub.2 O.sub.5 F.sup.- and/or of the system SiO.sub.2 -MgO-K.sub.2 O-F.sup.- -CaO-P.sub.2 O.sub.5, and/or a bioactive phosphate glass and/or a phosphate glass ceramic of the system P.sub.2 O.sub.5 -Al.sub.2 O.sub.