Composite glass articles for channel plate fabrication

Claim 1

A composite glass article suitable for the manufacture of a glass body comprising an array of channels which consists of: (a) an interconnected glass matrix composed of a non-leachable lead silicate matrix glass having an average linear coefficient of thermal expansion over the temperature range 0°-300° C. of not less than about 70 × 10 -7 /° C., a softening point not exceeding about 650° C., and a dissolution rate in 1N HNO 3 not exceeding about 5 × 10 -5 milligrams per square centimeter of exposed surface area per minute at 25° C., and (b) an array of leachable core glass elements encased in said glass matrix, each of said core glass elements being composed of a glass consisting essentially, in weight percent on the oxide basis, of about 38-64% BaO, 0-17% CaO, 0-3% MgO, 49-67% total of BaO + CaO + MgO, 8-45% B 2 O 3 , 6-34% SiO 2 , 32-51% total of B 2 O 3 + SiO 2 , at least 88% total of BaO + CaO + MgO + B 2 O 3 + SiO 2 , 0-12% Al 2 O 3 , 0-10% TiO 2 , 0-7% ZrO 2 , 0-3.5% Na 2 O and 0-4% ZnO, said glass having an average linear coefficient of thermal expansion over the temperature range 0-300° C. not exceeding about 105 × 10 -7 /° C., a softening point of at least about 645° C., a dissolution rate in 1N HNO 3 of at least about 0.4 milligrams per square centimeter of exposed surface area per minute at 25° C., and being essentially free of La 2 O 3 and ThO 2 .