JPS6019098B2 - Manufacturing method of lanthanum hexaboride hot cathode - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a hot cathode from a six-shelf lantern wafer.

Six-shelf lanthanum has better properties than tungsten as a hot cathode, and its practical application is desired.

The reason is that the work function is smaller than that of tungsten.
This is because it can be used at low temperatures, has high brightness, and can be used for a long time. However, six-shelf lanthanum reacts violently with the supporting metals, which are refractory metals such as tungsten wire and tantalum wire, at high temperatures, and various efforts have been made to put it into practical use. For example, it may be sandwiched between graphite to take advantage of its low reaction with graphite, or a barrier layer may be interposed between Rokugoka lanthanum and the supporting metal. On the other hand, single-crystal six-shelf lanthanum hot cathodes have a longer lifespan and higher brightness than conventional polycrystalline firing body hot cathodes. It is expected that the use of six-shelf lanthanum as a hot cathode will improve its performance as a hot cathode.

However, there are still very few examples of using single-crystal six-shelf lanthanum as a hot cathode, and there are still problems that need to be solved in the manufacturing and supporting methods of hot cathodes using single crystals. There is. An object of the present invention is to provide a method for manufacturing a single-crystal six-shelf lanthanum hot cathode.

The present invention involves coating a barrier layer on the surface of a wafer of single-crystal six-shelf lanthanum, further coating a refractory metal thereon, cutting it into chips, and polishing the tips of the chips to form a conical shape. A supporting wire such as a tungsten wire is attached to this to form a hot cathode.

The manufacturing method of the present invention will be explained in more detail below with reference to the drawings. FIG. 1 is an explanatory diagram showing the steps of a hot cathode manufacturing method according to the present invention.

In the first step, a wafer 1 made of a single crystal of six-shelf lanthanum with a thickness suitable for a hot cathode is used as a starting material, and a wafer 2 is formed by coating this with a barrier layer. In the third step, the wafer 3 is made into a chip 4. In the fourth step, the tip 4 is made into a chip 5 with a processed tip. In the fifth step, a support conductor is welded to make a hot cathode pole. .

FIG. 2 shows a hot cathode obtained by the method of the present invention.

A barrier layer and a fusible metal are coated on a single crystal six-shelf lanthanum wafer 1, and the barrier layer material is Wa group or V
One or a mixture of di-shelf metals of Group A metals is used, and the fusible metal is one of tungsten, tantalum, molybdenum, niobium, rhenium, or a mixture thereof.

Wafer 2 is coated with a barrier layer using a coating method, sputtering, vapor phase chemical plating (CVD), ion plating, etc. as a coating method, and wafer 3 is coated with a fusible metal on top of the barrier layer. shall be. The wafer 3 is cut into chips 4 by ultrasonic machining, electrical discharge machining, or the like. This produces a rectangular parallelepiped chip whose parallel surfaces are coated with a barrier layer and an elutriative metal.
The tip of the tip is mechanically polished to a conical shape with a tip angle A of 50 to 10 mm and a radius of curvature R of 50 to 100 #, and then electrolytically polished to a radius of curvature of 1 mm.
0 to 50 peaks. Finally, a tungsten wire, tantalum wire, or the like is bonded to the coated surface by spot welding or the like to form a hot cathode. According to the invention, one of the chips
Compared to the method of coating each chip one by one, a large number of chips can be made at once, so the cost is lower and the process is technically much simpler.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing the manufacturing process of a hot cathode according to the present invention;
FIG. 2 is a sectional view showing a hot cathode according to the present invention. 1 is a single-crystal six-shelf lanthanum wafer, 2 is 1 coated with a barrier layer, 3 is 2 coated with a meltable metal, 4
is cut into a chip, 5 is a tip processed, 6 is a hot cathode with a support wire attached to the tip, R is the curve radius of the tip, A is the tip angle, 7 is a single crystal six-shelf lanthanum, 8
9 is a barrier layer, 9 is a bonito-fusible metal coating, and 10 is a support conductor. Multi 1 drawing Multi 2 drawing

Claims (1)

[Claims] 1. A barrier layer is coated on both the upper and lower surfaces of a single-crystal lanthanum hexaboride wafer, and a refractory metal is further coated on top of the barrier layer. This is cut to the size of a hot cathode chip, the tip is processed, and a support metal is bonded. A method for producing a lanthanum hexaboride hot cathode, characterized by: