Tungsten electrode material and thermal electron emission current measurement device

Abstract

Provided is a tungsten electrode material which uses a material to replace thorium oxide so as to improve the electrode service life as compared to the conventional technique. The tungsten electrode material has a tungsten base and oxide particles dispersed in the tungsten base. The oxide particles are prepared as an oxide solid solution containing in a solid solved state: a Zr oxide and / or a Hf oxide and an oxide of at least one rare earth selected from a group consisting of Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu.

Description

technical field

[0001] The invention relates to a tungsten electrode material and a thermal electron emission current measuring device suitable for evaluating the thermal electron emission characteristic of the tungsten electrode material. Background technique

[0002] In the past, in the tungsten electrode (hereinafter also referred to as "tungsten electrode material", or "electrode material", or simply "electrode") that must produce thermionic emission phenomenon, for example, for the cathode of a discharge lamp with a large thermal load, etc. The electrode, implements technology to make it contain thorium oxide to improve thermionic emission characteristics at high temperature.

[0003] However, thorium is a radioactive element, and many techniques have been proposed in order to replace thorium oxide from the viewpoint of its safety management. These techniques realize the selection of a thermionic emission material and the optimization of its composition ratio.

[0004] ...

Examples

Embodiment 1

[0270] [Example 1] The mass ratio of Zr chloride to La chloride (manufactured by Aldrich, purity 99.9% by mass) is specified so that ZrO 2 95 mol% and La 2 o 3 These chlorides were dissolved in water to adjust the concentration to 0.2 mol / L to 5 mol%. While stirring the obtained aqueous solution, 2 mol / L ammonia water was added dropwise to the aqueous solution. Add dropwise until the pH of the aqueous solution is 8 to obtain hydroxide precipitates of Zr and La.

[0271] Next, dry the hydroxide precipitate at 200° C., and roast the dried hydroxide precipitate at 1000° C. in the air to obtain an oxide solid solution powder. By X-ray diffraction, it was confirmed that the powder was ZrO 2 with La 2 o 3 solid solution powder. The particle size of the obtained oxide solid solution is approximately 1-10 μm.

[0272] Next, the above-mentioned ZrO powder is mixed with ordinary tungsten powder having a purity of 99.9% by mass or more and an average particle diameter of about 4 ...

Embodiment 2

[0274] [Example 2] Use ZrO 2 -Sm 2 o 3 20 mol% oxide solid solution, in addition to making tungsten electrode material by the manufacturing process of embodiment 1.

Embodiment 3

[0275] [embodiment 3] make ZrO by the manufacture process of embodiment 1 2 with Er 2 o 3 solid solution oxides. Specifically, ZrO is mixed with ordinary tungsten powder with a purity of 99.9% by mass or more and an average particle size of about 4 μm (measured by the Fsss (Fisher) method). 2 -Er 2 o 3Oxide solid solution (relative to 78 mol% ZrO 2 , 22 mol% Er in solid solution 2 o 3 )powder.

[0276] Secondly, after molding the tungsten powder, it was heated in a hydrogen atmosphere at 1200°C for 1 hour, and then sintered in a hydrogen atmosphere at 2500°C to 3000°C for 1 hour to produce a rod-shaped tungsten electrode material with a cross-section of 25mm×25mm.

technical field

[0001] The invention relates to a tungsten electrode material and a thermal electron emission current measuring device suitable for evaluating the thermal electron emission characteristic of the tungsten electrode material. Background technique

[0002] In the past, in the tungsten electrode (hereinafter also referred to as "tungsten electrode material", or "electrode material", or simply "electrode") that must produce thermionic emission phenomenon, for example, for the cathode of a discharge lamp with a large thermal load, etc. The electrode, implements technology to make it contain thorium oxide to improve thermionic emission characteristics at high temperature.

[0003] However, thorium is a radioactive element, and many techniques have been proposed in order to replace thorium oxide from the viewpoint of its safety management. These techniques realize the selection of a thermionic emission material and the optimization of its composition ratio.

[0004] ...

Examples

Embodiment 1

[0270] [Example 1] The mass ratio of Zr chloride to La chloride (manufactured by Aldrich, purity 99.9% by mass) is specified so that ZrO 2 95 mol% and La 2 o 3 These chlorides were dissolved in water to adjust the concentration to 0.2 mol / L to 5 mol%. While stirring the obtained aqueous solution, 2 mol / L ammonia water was added dropwise to the aqueous solution. Add dropwise until the pH of the aqueous solution is 8 to obtain hydroxide precipitates of Zr and La.

[0271] Next, dry the hydroxide precipitate at 200° C., and roast the dried hydroxide precipitate at 1000° C. in the air to obtain an oxide solid solution powder. By X-ray diffraction, it was confirmed that the powder was ZrO 2 with La 2 o 3 solid solution powder. The particle size of the obtained oxide solid solution is approximately 1-10 μm.

[0272] Next, the above-mentioned ZrO powder is mixed with ordinary tungsten powder having a purity of 99.9% by mass or more and an average particle diameter of about 4 ...

Embodiment 2

[0274] [Example 2] Use ZrO 2 -Sm 2 o 3 20 mol% oxide solid solution, in addition to making tungsten electrode material by the manufacturing process of embodiment 1.

Embodiment 3

[0275] [embodiment 3] make ZrO by the manufacture process of embodiment 1 2 with Er 2 o 3 solid solution oxides. Specifically, ZrO is mixed with ordinary tungsten powder with a purity of 99.9% by mass or more and an average particle size of about 4 μm (measured by the Fsss (Fisher) method). 2 -Er 2 o 3Oxide solid solution (relative to 78 mol% ZrO 2 , 22 mol% Er in solid solution 2 o 3 )powder.

[0276] Secondly, after molding the tungsten powder, it was heated in a hydrogen atmosphere at 1200°C for 1 hour, and then sintered in a hydrogen atmosphere at 2500°C to 3000°C for 1 hour to produce a rod-shaped tungsten electrode material with a cross-section of 25mm×25mm.

Images