JPH0121861B2 - - Google Patents

Description

[Detailed description of the invention]

[Technical Field of the Invention] The present invention relates to a material for the inner parts of an electron tube, and more specifically, a material having high strength, low thermal expansion, and excellent workability.
The present invention relates to a tube internal component material suitable as a material for shadow masks, frames, etc. of color picture tubes. [Technical background of the invention and its problems] Immediately in front of the phosphor surface of a color picture tube, a shadow mask having a large number of apertures formed based on predetermined design criteria is disposed. The electron beam emitted from the rear electron gun passes through these apertures and is irradiated onto fluorescent dots at predetermined positions on the fluorescent surface, thereby reproducing a color image there. However, not all of the emitted electron beams pass through the apertures, and a portion directly hits the shadow mask and heats the shadow mask. As a result, the shadow mask thermally expands and the position of the opening deviates from the position of the design standard, which may cause a color shift phenomenon on the fluorescent surface. For this reason, a conventional method has been adopted in which the shadow mask is supported by a bimetal and the curvature of the bimetal during heating is utilized to bring the entire shadow mask closer to the fluorescent surface. Recently, attempts have been made to prevent color shift by forming the shadow mask itself from Invar alloy, which is a nickel-iron alloy having low thermal expansion characteristics. In the former case, the structure becomes complicated. Therefore, although the latter is a more preferable embodiment, there are the following problems in this case. Shadow masks are generally manufactured as follows. In other words, the material used is mild steel, which is inexpensive in terms of mass usage, ease of manufacture, and cost.
It is etched with an iron solution to form holes in a predetermined shape in the form of dots or sag, and then the whole is oxidized with steam, for example, to blacken the surface to improve thermal radiation and prevent diffused reflection. , is the method. At this time, in order to drill the holes smoothly, the mild steel plate needs to be somewhat thin.
Usually it is about 0.15mm. Particularly in recent years, the thickness has become thinner due to the need to drill holes with fine pitches in order to improve resolution. This reduces the overall mechanical strength of the shadow mask. Even so, if the fluorescent surface is a curved surface and the shadow mask is narrowed down to a certain radius of curvature, the structural strength of the shadow mask as a whole will increase, so there will not be much of a problem. If this method is applied to a flat type fluorescent surface, which is commonly used, an inconvenient situation will occur. In other words, since the radius of curvature of the shadow mask increases in accordance with the radius of curvature of the flat type fluorescent surface, the mechanical strength of the mask as a whole inevitably decreases.
Therefore, the shadow mask, that is, the aperture position, is displaced by vibrations generated by a speaker, etc., resulting in a color misregistration phenomenon. This tendency is particularly noticeable with fine-pitch shadow masks. Furthermore, the shadow mask is attached and detached several times during the process of completing the picture tube, and if the mechanical strength of the shadow mask is low, the worker may deform the shadow mask during this repeated attachment and detachment process. be. Furthermore, the mild steel used as a material is usually alpha iron (ferrite) with a small amount of solid solution of carbon, but in most cases carbides are dispersed in the matrix. If carbide exists, the etching rate with the ferric chloride solution will be different, so during the drilling process of mild steel plates, the holes will not be drilled in the shape of the design standard, resulting in so-called "gaza holes". This results in irregularly shaped holes, which are commonly known as pores. As mentioned above, the materials for the shadow mask must have a small coefficient of thermal expansion, high mechanical strength, the ability to form holes in accordance with design standards (high workability), and black However, to date, no suitable material has been developed that satisfies these properties. [Object of the Invention] An object of the present invention is to provide an alloy material with a novel composition that satisfies the above-mentioned requirements and is extremely useful as a material for internal parts of electron tubes, typified by shadow masks. [Summary of the Invention] The alloy material of the present invention first contains 4 chromium (Cr).
The basic characteristic is that ~30% by weight, the balance being iron (Fe). In another embodiment, the carbon content is 1.0% by weight or less, and in still another embodiment, vanadium (V), zirconium (Zr), titanium (Ti), niobium (Nb), molybdenum (Mo), tantalum (Ta), aluminum (Al), nickel (Ni), and tungsten (W).
It is characterized by a content of % by weight. Furthermore, as another embodiment, carbon (C) is 1.0% by weight or less, vanadium (V), zirconium (Zr), titanium (Ti), niobium (Nb), molybdenum (Mo), tantalum (Ta), aluminum ( It is characterized by containing 0.001 to 1.0% by weight of at least one member selected from the group consisting of Al), nickel (Ni), and tungsten (W). The material of the present invention is based on Fe.
Cr is an essential component for increasing the mechanical strength of the material, reducing thermal expansion, and facilitating the blackening process. If the content is too low, sufficient improvement effects in terms of mechanical strength and low thermal expansion will not be obtained, and
If it is too large, the σ phase will precipitate, resulting in poor workability. Therefore, the Cr content is usually set at 4 to 30% by weight. C contained in the material is limited to 1.0% by weight or less. C is a component that contributes to improving the strength of Cr-Fe alloys without impairing their low thermal expansion properties, but even if its content exceeds 1.0% by weight, the effect does not improve and on the contrary, it may produce chromium carbide or retain austenite. Forms phases and deteriorates workability. In the present invention, retained austenite phase and σ
In order to prevent phase precipitation, V, Zr, Ti,
Elements such as Nb, Mo, Ta, Al, Ni, and W are added individually or in appropriate combinations to suppress and stabilize the behavior of C. The effects of these elements are
It is effective from 0.001% by weight or more, but if the content is too large, the low thermal expansion property of the alloy material will be impaired and at the same time it will cause disadvantages such as deterioration of hot workability. Therefore, the content of these elements is between 0.001 and 1.0.
Weight percent is preferred. When two or more of these elements are added, the total amount must be within the above range. Among these elements, V and Zr are particularly preferred components because they exhibit an extremely excellent effect on blackening the material. The material of the present invention is produced by blending the above-mentioned components in predetermined amounts and melting the whole by a method such as vacuum induction melting.
It may be manufactured by casting, forging, and rolling using conventional methods. [Embodiments of the invention] Examples 1 to 32 After casting alloys with the components shown in the table, they were forged, further hot rolled to a thickness of 4 to 10 mm, and then cold rolled to a flat plate of 0.1 mm thickness. . For comparison, alloys outside the composition range of the present invention (Comparative Examples 1 to 3) were made into 4 to 10 mm thick by the same manufacturing method, and then made into flat plates with a thickness of 0.15 mm by cold rolling. Test pieces were cut out from each of these plate materials, and their tensile strength and coefficient of thermal expansion were measured. Additionally, a 0.15mm hole was drilled in each plate using the standard fine pitch specification. In Examples 1 to 32, no "pocket holes" were observed, and the holes were drilled in accordance with the design standards. After being blackened in a steam atmosphere at 400 to 450°C, it was made into a flat type shadow mask with a radius of curvature of 2800. We set these up and observed the state of color shift while applying speaker vibration. The above results are summarized in a table.

【table】

〔Effect of the invention〕

As is clear from the above description, the material of the present invention has low thermal expansion, high mechanical strength, good workability, and can be easily blackened (in a short period of time). It is extremely useful as a material for parts, especially shadow masks, and has great industrial value.

Claims (1)

[Scope of Claims] 1. A material for internal parts of an electron tube, characterized in that it contains 4 to 30% by weight of chromium, and the balance is iron. 2. A material for the inner parts of an electron tube, characterized by containing 4 to 30% by weight of chromium, 1.0% by weight or less of carbon, and the balance being iron. 3 4 to 30% by weight of chromium, 0.001 to 1.0% of at least one element selected from the group of vanadium, zirconium, titanium, niobium, molybdenum, tantalum, aluminum, nickel, and tungsten.
An electron tube inner part material characterized in that the balance by weight is iron. 4 4 to 30% by weight of chromium, 1.0% by weight or less of carbon, and 0.001 to 1.0% by weight of at least one element selected from the group of vanadium, zirconium, titanium, niobium, molybdenum, tantalum, aluminum, nickel, and tungsten. , a material for the inner parts of an electron tube, characterized in that the remainder is iron.