US 5,087,299 A · Vibration-proof tungsten wire

Abstract

A vibration-proof tungsten wire which forms, in cases where the diameter of the wire is D mm and when an electric current corresponding to 90% of the fusion current value is passed therethrough for 5 minutes, a wire having a crystal grain boundary at which bubbles of 0.3 .mu.m or less in diameter are dispersed in bubble rows with lengths of (0.39/D).sup.2 .times.3 .mu.m or more arrayed in the wire axis direction of said crystal grain boundary, and bubbles of 0.2 .mu.m or less in diameter are randomly dispersed; and a crystal grain in which bubbles of 0.3 .mu.m or less in diameter are dispersed in rows with lengths of (0.39/D).sup.2 .times.30 .mu.m or more arrayed in the wire axis direction within said crystal grain, and bubbles of 0.2 .mu.m or less are randomly dispersed; a process for preparing the same; and a tungsten filament obtained from the above-defined wire. The doped tungsten wire of this invention possesses excellent vibration-proof property on lighting as well as high reliability.

Claims11

Dependent claims

A vibration-proof tungsten wire having a structure comprising

a crystal grain boundary at which bubbles of 0.3 .mu.m or less in diameter are dispersed in bubble rows with lengths of (0.39/D).sup.2 .times.3 .mu.m or more arrayed in the wire axis direction of said crystal grain boundary, and bubbles of 0.2 .mu.m or less in diameter are randomly dispersed;
and
a crystal grain in which bubbles of 0.3 .mu.m or less in diameter are dispersed in rows with lengths of (0.39/D).sup.2 .times.30 .mu.m or more arrayed in the wire axis direction within said crystal grain, and bubbles of 0.2 .mu.m or less in diameter are randomly dispersed,
wherein D denotes the diameter of the wire in mm and an electric current corresponding to 90% of the fusion current value has been passed through the wire for 5 minutes.

1 more element

A process for preparing a vibration-proof tungsten wire having a structure comprising a crystal grain boundary at which bubbles of 0.3 .mu.m or less in diameter are dispersed in bubble rows with lengths of (0.39/D).sup.2 .times.3 .mu.m or more arrayed in the wire axis direction of said crystal grain boundary, and bubbles of 0.2 .mu.m or less in diameter are randomly dispersed;

and a crystal grain in which bubbles of 0.3 .mu.m or less in diameter are dispersed in rows with lengths of (0.39/D).sup.2 .times.30 .mu.m or more arrayed in the wire axis direction within said crystal grain, and bubbles of 0.2 .mu.m or less in diameter are randomly dispersed, wherein D denotes the diameter of the wire in mm, the process comprising the steps of subjecting ammonium para-tungstate to reduction at a temperature of 300.degree. to 600.degree. C. to form tungsten oxide;
admixing as dopants a potassium compound, and at least one compound selected from the group consisting of a silicon compound and an aluminum compound to the resultant tungsten oxide to form a mixture;
subjecting the resultant mixture to reduction in a stream of hydrogen at a temperature of 600.degree. to 900.degree. C. to form a metallic tungsten powder;
subjecting the resultant metallic tungsten powder to acid washing to remove superfluous dopants therefrom;
press-molding the resultant metallic tungsten powder followed by pre-sintering in a hydrogen furnace and subsequent sintering by current passage to give a tungsten sintered bar;
subjecting the resultant tungsten sintered bar to swaging and drawing to obtain a tungsten wire;
and then passing an electric current corresponding to 90% of the fusion current value through the resultant wire for 5 minutes.

4 more elements

Dependencies are inferred from the claim text.

Vibration-proof tungsten wire

Life of this patent

Vibration-proof tungsten wire

Life of this patent

Abstract

Claims11