METHOD OF PRODUCING AIRTIGHT CERAMIC-METAL SEAL USING COMPENSATING ELEMENT Russian patent published in 2012 - IPC C04B37/02 B23K31/02 

FIELD: chemistry.

SUBSTANCE: invention relates to ceramic materials and compounds thereof with metallic articles when making separate units of electrovacuum equipment, used in radio and electronic engineering. The airtight compressed mismatched ceramic-metal seal 'ceramic BK94-1 steel 12X18H10T' is obtained via single-step brazing in a vacuum medium with 'silver-copper' PSr72 system solder by adding an intermediate compensating element made from a titanium alloy. Solder PSr72 is first annealed in a vacuum and clarified in HNO₃ solution. The intermediate compensating element made from titanium alloy is prepared by defatting and removing the oxide film with vacuum annealing at temperature 860°C. The titanium alloy compensates for the effect of internal destructive compression stress arising in the mismatched joint 'vacuum-tight alumina ceramic BK94-1 - stainless steel 12X18H10T', creates a low-melting eutectic mixture with 'silver-copper' PSr72 system solder at joint temperature in a vacuum.

EFFECT: method enables to eliminate labour input for preliminary metal coating the ceramic surface and obtain joints with high mechanical strength and air-tightness of not more than 1×10^-3 mm Hg×l/s while monitoring leakage with a helium leak detector.