Glass compositions and fibers made therefrom

A glass composition consisting of:

• ______________________________________ Silica 50% by weight Sodium Oxide 10% Lithium Oxide 1% Boric Oxide 3% Titania 10% Zirconia 10% Cerium Oxide 15% Sodium Fluoride 1% ______________________________________

A glass composition consisting of:

• ______________________________________ Silica 58% by weight Sodium Oxide 13% Titania 9% Zirconia 12% Boric Oxide 3% Ceric Oxide 5% ______________________________________

A glass composition consisting of:

• ______________________________________ Silica 56% by weight Sodium Oxide 12% Titania 8% Zirconia 13% Boric Oxide 3% Calcium Oxide 6% Ceric Oxide 2% ______________________________________

A glass composition consisting essentially of:

• ______________________________________ Silica 58% by weight Sodium Oxide 14% Titania 10% Zirconia 13% Boric Oxide 4% Barium Oxide 0.1% Mixture of naturally accuring rare earth oxides 0.8% Cl 0.1% ______________________________________

A glass composition consisting essentially of:

• ______________________________________ Silica 58% by weight Sodium Oxide 13% Titania 7% Zirconia 14% Boric Oxide 0.5% Calcium Oxide 4% Barium Oxide 0.6% Mixture of naturally accurring rare earth oxides 2.5% Cl 0.4% ______________________________________

A glass composition, having improved chemical resistance to alkali attack, consisting essentially of:

• ______________________________________ from 50-58 percent by weight Silica " 11-14 " " " R.sub.2 O " 8-10 " " " Titania " 10-14 " " " Zirconia " 0.8-15 " " " Rare Earth Oxide " 0.5-4 " " " Boric Oxide " 0.1-6 " " " R.sup.1 O " 0-1 " " " Fluorine (as fluoride) " 0.1-0.4 " " " Chlorine (as chloride) ______________________________________
• wherein [R20] R.sub.2 O is elected from the group consisting of Na.sub.2 O, K.sub.2 O, mixtures of the two, and mixtures thereof additionally containing up to 1% by weight lithium oxide (based on the total weight of the composition) and R.sup.1 O is selected from the group consisting of MgO, CaO, BaO, SrO and mixtures of two or more thereof.