Ballistic-resistant glass-ceramic and method of preparation

Claim 1

A semicrystalline ballistic-resistant glass-ceramic body having a plurality of fine-grained, randomly oriented inorganic crystals substantially uniformly dispersed in a glassy phase said crystals being formed by crystallization in situ from a glass body made from a base glass forming batch having a composition consisting essentially of by weight on an oxide basis: 78.5%-84.5% SiO 2 , 9.5%-15% Li 2 O, 1%-6% Al 2 O 3 and 1.5%-4% K 2 O in a combination totaling 100% of the base glass batch and further including, on a weight basis calculated as a percentage of the total weight of said base glass batch, a combination of the group consisting of TiO 2 , ZrO 2 and SnO 2 wherein the total of said combination of said group is not more than 5% and the weight ratio between them is approximately 3:2:1 respectively; and including MgO between the range of 30% to approximately 50% of the amount of Al 2 O 3 on a weight basis in the composition and wherein the body is characterized by having lithium disilicate, cristobalite and spinel as the primary crystalline phases, a coefficient of thermal expansion which ranges from about 100 to 125×10 -7 /°C. (up to 800° C.) and a density which ranges from about 2.45 to 2.50 gms/cc.

Claim 5

A method of making a semi-crystalline ballistic-resistant glass-ceramic body which comprises forming a molten body of glass consisting essentially of a base glass batch of the following components by weight percent, 78.5 to 84.5% SiO 2 ; 9.5 to 15% Li 2 O; 1 to 6% Al 2 O 3 ; 1.5 to 4% K 2 O, the sum of which totaling at least approximately between 95 to 97.5% of the total composition which also includes the combination of the group consisting of TiO 2 , ZrO 2 and SnO 2 wherein the total of said combination of said group is not more than 5% on a weight basis as a percentage of the total weight of said base glass batch and the weight ratio of said group members relative to each other is 3:2:1, respectively; and including MgO in the range between 30% to approximately 50% of the amount of Al 2 O 3 on a weight basis in the composition; forming said molten body into a solid glass body; then heating said solid body up to a temperature between 480-530 degrees centigrade and holding said temperature for a time period between approximately one to twenty-four hours for annealing purposes before cooling said body to room temperature; then heating said annealed glass body up to approximately 480 to 530 degrees centigrade at a rate between approximately 1 to 5 degrees centigrade per minute, then continue heating said body at a rate between approximately 0.3 to 1.0 degrees centigrade to a temperature between 680 to 725 degrees centigrade and holding said temperature between said 680 to 725 degree centigrade range for a time period between approximately one-half to twenty-four hours; then continuing to heat said body at a rate of temperature increase of 0.5 to 6 degrees centigrade until the temperature of said body reaches approximately 830 to 870 degrees centigrade, then holding said body within the last mentioned temperature range for approximately 5 minutes to 5 hours; then cooling said body at a rate of approximately 0.5 degrees to 3 degrees centrigrade per minute to approximately 380-300 degrees centigrade; then cooling is continued at a cooling rate of approximately 2 to 12 degrees centigrade per minute to room temperature and wherein the body is characterized by having lithium disilicate, cristobalite and spinel as the primary crystalline phases, a coefficient of thermal expansion which ranges from about 100 to 125×10 -7 /°C. (up to 800° C.) and a density which ranges from about 2.45 to 2.50 gms/cc.

Claim 6

A method of making a semi-crystalline ballistic-resistant glass-ceramic body which comprises forming a molten body of glass consisting essentially of a base glass batch of the following components by weight percent, 78.5 to 84.5% SiO 2 ; 9.5 to 15% Li 2 O; 1 to 6% Al 2 O 3 ; 1.5 to 4% K 2 O, the sum of which totaling at least approximately between 95 to 97.5% of the total composition which also includes the combination of the group consisting of TiO 2 , ZrO 2 and SnO 2 wherein the total of said combination of said group is not more than 5% on a weight basis as a percentage of the total weight of said base glass batch and the weight ratio of said group members relative to each other is 3:2:1, respectively; and including MgO in the range between 30% to approximately 50% of the amount of Al 2 O 3 on a weight basis in the composition; forming said molten body into a solid glass body; then heating said solid body up to a temperature between 480-530 degrees centigrade and holding said temperature for a time period between approximately one to twenty-four hours for annealing purposes before cooling said body to room temperature; then heating said annealed glass body up to approximately 480 to 530 degrees centigrade at a rate between approximately 1 to 5 degrees centigrade per minute, then continue heating said body at a rate between approximately 0.3 to 1.0 degrees centigrade to a temperature between 680 to 725 degrees centigrade and holding said temperature between said 680 to 725 degree centigrade range for a time period between approximately one-half to twenty-four hours; then continuing to heat said body at a rate of temperature increase of 0.5 to 6 degrees centigrade until the temperature of said body reaches approximately 830 to 870 degrees centigrade, then holding said body within the last mentioned temperature range for approximately 5 minutes to 5 hours; then cooling said body at a rate of approximately 0.5 degrees to 3 degrees centrigrade per minute to approximately 380-300 degrees centigrade; then cooling is continued at a cooling rate of approximately 2 to 12 degrees centigrade per minute to room temperature and wherein the body is characterized by having lithium disilicate, cristobalite and spinel as the primary crystalline phases, a coefficient of thermal expansion which ranges from about 100 to 125×10 -7 /°C. (up to 800° C.) and a density which ranges from about 2.45 to 2.50 gms/cc.