JPS6020866B2 - Anode for X-ray tube - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention features a special alloy composition in an anode for an X-ray tube.

Z It is well known that conventional X-ray tube anodes use pure steel (hereinafter referred to as steel material) for the anode substrate in which the tungsten target plate is embedded, but the adhesion to the tungsten target plate embedded in the steel material is As purity improves, diffusivity deteriorates. Generally, an X-ray tube has a structure as shown in FIG. 1, in which a cathode 1 and an anode 2 are sealed inside a glass bulb 3, which is evacuated to a high vacuum and then sealed off. Note that the cathode 1 has a cathode lead 4,
Alternatively, the anode 2 has an anode terminal 5, and the cathode lead 4 is supplied with cathode heating power to heat the filament 6 installed in the cathode 1 and emit thermionic electrons. Thermionic electrons are collected by a collecting body (not shown). When a high voltage is applied between the cathode 1 and the anode 2, the concentrated electrons fly out toward the anode 2, collide with the tungsten target plate 7 embedded in the center of the anode 2, and generate X-rays. occurs. During this process, when electrons collide with the tungsten target plate 7, a large amount of heat is generated. This heat is conducted to the steel part of the anode 2 in which the tungsten target plate 7 is embedded, and is mainly radiated and cooled at the anode terminal 5 part.

In this way, X-rays are generated, but since the coefficients of thermal expansion of tungsten and copper are significantly different, if the adhesive strength between the steel material of the anode 2 and the steel material of the anode 2 and the tungsten target plate 7 is weak, as shown in FIG. , the tungsten target plate 7 may peel off 8 due to heating, and the part of the tungsten target plate 7 where electrons collide may crack 9 as shown in Fig. The major drawback was that the characteristics could not be maintained and the lifespan would be shortened. The present invention was devised to eliminate such drawbacks, and is intended to provide a stable anode for an X-ray tube by strengthening the adhesive force between steel and tungsten.

Conventionally, the method of embedding the tungsten target plate 7 in a steel material is to fix the tungsten target plate 7 in a crucible 10 as shown in FIG. The steel is heated and cast until it melts. However, as mentioned above, tungsten and steel materials are difficult to alloy due to their nature, and their adhesive strength is also very weak, making them prone to peeling and cracking when heated by electron collisions. The present invention aims to improve this drawback, and specific embodiments will be described in detail.

First, as a preliminary experiment, we added 0.01, 0.2, and 0.51% by weight of nickel or gold to 99.99% steel. As a result, the tensile strength was as shown in Table 1. Obtained. Table 1 shows that when 0.01 to 0.5% of nickel is added to a steel material, the tensile strength gradually increases, and when 1% or more of nickel is added, the tensile strength gradually decreases.

Furthermore, it was found that adding 0.01 to 1% gold to steel increases the tensile strength. Based on this result, as an example, when 0.2% by weight of nickel is mixed as the anode (steel material) 2, that is, a 0.2% nickel steel alloy is used, each is assembled in the crucible 10, and 1. The nickel steel alloy is melted at a high temperature of 100 qo or more, and the tungsten target plate 7 and the nickel reduced alloy are embedded and bonded. In this case, nickel begins to diffuse into the surface of the tungsten target plate 7. Furthermore, nickel and copper are highly diffusible metals, so they are easily diffused. Because such a reaction is repeated, the tungsten target plate 7 is also diffused and embedded in the steel material with a strong adhesive force. Alternatively, the tungsten target plate 7 is filled with a thin nickel plate and melted in the crucible 10, or the tungsten target plate 7 is plated with nickel, or nickel powder is placed and melted at high temperature. Regardless of the casting conditions (temperature, time, etc.), the part in contact with the tungsten target plate of the anode is an alloy containing copper and nickel at a weight ratio of 0401 to 1%, and the tungsten target plate has strong adhesion to the anode base. It will be buried with

As described above, the tungsten target plate is firmly bonded to the anode base through the nickel steel alloy part, but instead of nickel, one or more of chromium, iron, cobalt, rhenium, rhodium, gold, and platinum is used. Even when using copper, an alloy containing 0.01 to 1% of the metal is formed on the part of the anode substrate that is in contact with the tungsten target plate. This creates a strong adhesive force between the tungsten target plate and the anode substrate. , an anode for X-ray tubes with good heat conduction was created.
It has a great effect on increasing the reliability of the wire tube and extending its life.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of the X-ray tube, Figure 2 is a cross-sectional view illustrating the peeled off state of the tungsten target plate of the X-ray tube anode.
FIG. 3 is a front view showing the tungsten target plate in a broken state, and FIG. 4 is a sectional view showing the state assembled in a crucible used for anode casting. 1... Cathode, 2... Anode, 6... Filament, 7... Tungsten target plate, 8... Peeling part, 9... Crack in tungsten target plate, IQ...
...melting pot. Figure 1 Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] 1. In an anode for an X-ray tube in which a tungsten target plate is embedded in an anode base by casting, the anode base contains one or more of nickel, chrome, iron, cobalt, rhenium, rhodium, gold, and platinum at a weight ratio of 0.01. An anode for an X-ray tube, characterized in that it is made of a copper alloy containing ~1%.