Reinforced insulated heater getter device

A porous non-evaporable getter device comprising;

• A. a spirally wound molybdenum heating wire defining a cylindrical surface having two ends, the cylindrical surface being disposed about a central axis and;
• B. two support lead wires of substantially equal length, integrally formed with said heating wire and of the same diameter, extending from the same end of the cylindrical surface and parallel to said central axis, situated diametrically opposite to each other and;
• C. each support lead encircled by a hollow electrically insulating Al.sub.2 O.sub.3 ceramic cylinder, having an outer surface and an inner surface whose inner diameter is from 5% to 20% greater than that of the support lead wire, one end of each ceramic cylinder in proximity with the position of integral formation of the support lead wire with the heating wire and;
• D. an electrophoretically deposited insulating coating of Al.sub.2 O.sub.3 comprising;
• (a) a first zone covering the spirally wound molybdenum heating wire to a thickness of between 0.05 and 0.2 mm and;
• (b) a second zone, integrally formed with said first zone, covering the outer surface of each ceramic cylinder to a distance of from 30% to 60% of its length and;
• (c) a third zone, integrally formed with said first zone, extending between the diameter of the lead wire and the inner diameter of each ceramic cylinder to a distance of from 90% to 98% of its length and;
• E. a non-evaporable getter material comprising;
• (a) a particulate non-evaporable getter material chosen from the group consisting of titanium, zirconium and their hydrides;
• (b) a particulate antisintering material chosen from the group consisting of:
• (i) graphite,
• (ii) an alloy of zirconium with aluminium in which the weight percent of aluminium is from 5-30%;
• (iii) an alloy of zirconium with M.sub.1 and M.sub.2 where M.sub.1 is chosen from the group consisting of vanadium or niobium and M.sub.2 is chosen from the group consisting of iron and nickel;
• (iv) an alloy of Zr-V-Fe whose composition in weight percent, when plotted on a ternary composition diagram in weight percent Zr, weight percent V and weight percent Fe, lies within a polygon having as its corners the points defined by:
• --75% Zr--20% V--5% Fe
• --45% Zr--20% V--35% Fe
• --45% Zr--50% V--5% Fe;
• the non-evaporable getter material completely enclosing the first and second zones of electrophoretically deposited insulating coating of Al.sub.2 O.sub.3 and covering the outer surface of each ceramic cylinder to a distance of from 20% to 60% between the distance covered by the second electrophoretically deposited zone and the third electrophoretically deposted zone.

A method for the manufacture of a non-evaporable getter device comprising the steps of;

• I. placing a heater sub-assembly in a bath of coating suspension adapted for the electrophoretic deposition of an insulating coating, said heater sub-assembly comprising
• A. a heating wire and;
• B. two support lead wires, integrally formed with said heating wire and;
• C. each support lead encircled by a hollow insulating cylinder, having an outer surface and an inner surface whose inner diameter is greater than that of the support lead wire, one end of each ceramic cylinder in proximity with the position of integral formation of the support lead wire with the heating wire,
• to a depth such that the coating suspension,
• a. covers the heating wire, and
• b. covers part of the outer surface of each ceramic cylinder, and
• c. enters the volume contained between the diameter of the support lead wire and the inner diameter of each ceramic cylinder, then
• II. electrophoretically depositing an insulating coating to produce:
• (a) a first zone covering the heating wire and;
• (b) a second zone, integrally formed with said first zone, covering part of the outer surface of each insulating cylinder and;
• (c) a third zone, integrally formed with said first zone, extending between the diameter of the lead wire and the inner diameter of each insulating cylinder
• thus producing a reinforced heater assembly, then,
• III. sintering the reinforced heater assembly to produce a sintered reinforced heater assembly then,
• IV. coating the sintered reinforced heater with a non-evaporable getter material,
• the non-evaporable getter material enclosing the first and second zones of electrophoretically deposited insulating coating and covering part of the outer surface of each insulating cylinder.

A method for the manufacture of a porous non-evaporable getter device comprising the steps of;

• I. placing a heater sub-assembly in a bath of coating suspension adapted for the electrophoretic coating of Al.sub.2 O.sub.3, said heater sub-assembly comprising;
• A. a spirally wound molybdenum heating wire defining a cylindrical surface having two ends, the cylindrical surface being disposed about a central axis and;
• B. two support lead wires of substantially equal length, integrally formed with said heating wire and of the same diameter, extending from the same end of the cylindrical surface and parallel to said central axis, situated diametrically opposited to each other and;
• C. each support lead encircled by a hollow electrically insulating Al.sub.2 O.sub.3 ceramic cylinder, having an outer surface and an inner surface whose inner diameter is from 5% to 20% greater than that of the support lead wire, one end of each ceramic cylinder in proximity with the position of integral formation of the support lead wire with the heating wire,
• to a depth such that the coating suspension,
• a. covers the heating wire, and
• b. covers each ceramic cylinder to a distance of from 30% to 60% of its length, and
• c. enters the volume contained between the diameter of the support lead wire and the inner diameter of each ceramic cylinder to a distance of from 90% to 98% of its length, then
• II. electrophoretically depositing an insulating coating of Al.sub.2 O.sub.3 to produce:
• (a) a first zone covering the spirally wound molybdenum heating wire to a thickness of between 0.05 and 0.2 mm and;
• (b) a second zone, integrally formed with said first zone, covering the outer surface of each ceramic cylinder to a distance of from 30% to 60% of its length and;
• (c) a third zone, integrally formed with said first zone, extending between the diameter of the lead wire and the inner diameter of each ceramic cylinder to a distance of from 90% to 98% of its length,
• thus producing a reinforced heater assembly, then,
• III. sintering the reinforced heater assembly in a hydrogen furnace at a temperature of from 1600.degree. to 1700.degree. C. for a time of from 3 to 10 minutes to produce a sintered reinforced heater assembly then,
• IV. coating the sintered reinforced heater with a non-evaporable getter material comprising;
• (a) a particulate non-evaporable getter material chosen from the group consisting of titanium, zirconium and their hydrides;
• (b) a particulate antisintering material chosen from the group consisting of:
• (i) graphite,
• (ii) an alloy of zirconium with aluminium in which the weight percent of aluminium is from 5-30%;
• (iii) an alloy of zirconium with M.sub.1 and M.sub.2 where M.sub.1 is chosen from the group consisting of vanadium or niobium and M.sub.2 is chosen from the group consisting of iron and nickel;
• (iv) an alloy of Zr-V-Fe whose composition in weight percent, when plotted on a ternary composition diagram in weight percent Zr, weight percent V and weight percent Fe, lies within a polygon having as its corners the points defined by:
• --75% Zr--20% V--5% Fe
• --45% Zr--20% V--35% Fe
• --45% Zr--50% V--5% Fe
• the non-evaporable getter material completely enclosing the first and second zones of electrophoretically deposited insulating coating of Al.sub.2 O.sub.3 and covering the outer surface of each ceramic cylinder to a distance of from 20% to 60% between the distance covered by a second electrophoretically deposited zone and the third electrophoretically deposited zone.