KR940009436B1 - Shadow mask material for crt shadow mask - Google Patents

Abstract

The method lowers yield strength and enhance workability by adding Vanadium to Invar alloy, that is a material of shadow mask. The composition ratio of Invar alloy comprises; Ni: 30-45 wt.%, V: 0.01-0.09 wt.%, remains: Fe and impurity of inevitable small amount elements (C, Si, Mn, P, S).

Description

CRT shadow mask material

1 is a block diagram of a color CRT

2 is manufacturing process diagram

* Explanation of symbols for the main parts of the drawings

1: Panel 2: Funnel

3: neck 4: electron gun

5: deflection device 6: shadow mask

7: frame.

The present invention relates to a shadow mask of a color CRT, and more particularly to a shadow mask material suitable for adding vanadium (V) to a shadow mask material, Invar alloy, to lower yield strength and improve formability.

In general, the color CRT consists of a vacuum vessel as panel 1, funnel 2 and neck 3, as shown in FIG.

On the inner surface of the panel 1, a shadow mask 6 in which stripe or dot-shaped openings emitting red, green, and blue light are arranged is supported and fixed by the frame 7, The frame 7 is fixed to a stud pin fixed to the inner wall of the skirt portion of the panel using a spring as a medium.

The electron beam emitted from the electron gun is deflected by the deflector 5 outside the funnel and irradiated toward the inner surface of the panel, and color-selected while landing through the opening of the shadow mask to land on the screen to reproduce the color image.

As in the above configuration, the effective electron beam passing through the shadow mask in the color cathode ray tube is about 20%, and the remaining electron beam collides with the shadow mask 6 to be converted into thermal energy so that the shadow mask is heated during the operation of the color cathode ray tube.

Generally, the shadow mask material is a cold rolled steel, which is 0.1-0.3 mm thick thin sheet mainly composed of iron, whose coefficient of thermal expansion is 1.2 × 10 ⁻⁵ / ° C.

In contrast, a cold rolled steel having a "L" shape of about 1 mm in thickness is used for the frame 7 for welding and supporting the shadow mask. The heated shadow mask is easily welded to a frame having a large thermal capacity around the periphery. Therefore, a temperature difference occurs between the center and the periphery of the shadow mask, and the center part is mainly thermally expanded to cause the doming phenomenon.

As a result of the domming phenomenon, the shadow mask and the phosphor screen are changed in distance, so that the electron beam is not accurately landed and color purity is lowered.

Therefore, in order to reduce the doming phenomenon, Inba alloy composed of Fe-Ni element whose thermal expansion is about 1/10 of the cold rolled steel and inevitable impurity elements (C, Si, Mn, P, S) is used as the shadow mask. It greatly reduces the coefficient of thermal expansion.

However, the Invar alloy used in the shadow mask has a yield strength of about 25 kg / mm after the final heat treatment, which inevitably implies that the inevitable impurity elements are dissolved into the matrix metal to penetrate or replace the alloy to induce solid solution. It causes the strength to rise.

Among these impurity elements, especially carbon is dissolved in an invasive form, distorting the crystal lattice, causing internal stress, disturbing dislocation movement, suppressing plastic deformation of the alloy, thereby increasing tensile and yield strength, resulting in a shadow mask. Since it is difficult to mold to the desired curvature, it is molded at a temperature of 150-250 ° C. after heat treatment in a hydrogen or nitrogen gas atmosphere.

Therefore, such a conventional invar alloy material has to be accompanied by a complicated post-process and at the same time has a problem that increases the manufacturing cost.

Accordingly, the present invention solves the conventional problems of improving the moldability of the shadow mask by reducing the yield strength to some extent and increasing the elastic modulus according to a series of processes of adding vanadium (V) to the existing invar alloy. There is this.

Hereinafter, the present invention will be described.

The present invention is characterized in that the nickel (NI) 30-45% by weight, vanadium (V) 0.01-0.09% by weight, the inevitable impurity elements (C, Mn, Si, P, S) and the rest is made of iron (Fe) Consists of CRT shadow mask material.

When such a configuration is described in detail according to the action and effect, inevitable impurity elements, especially carbon, are dissolved into the alloy in an invasive form, distorting the crystal lattice, causing internal stress, and preventing dislocation movements, thereby causing plastic deformation. This results in suppression, which increases the tensile and yield strength, but decreases the formability.

Therefore, in the present invention, when vanadium is added to the alloy, vanadium reacts with carbon or nitrogen to form vanadium carbide or vanadium nitride to precipitate on the base metal. These precipitates cause precipitation strengthening, which impedes the movement of dislocations, thereby increasing the strength of the alloy.

At this time, the amount of reinforcement becomes finer as the particles are finer and the distance between the particles becomes shorter. As such, when the amount of vanadium is excessively used for a predetermined amount or more, the solid solution strengthening effect is increased.

Therefore, in the present invention, vanadium is added to precipitate carbon and nitrogen into carbides and nitrides, but the amount thereof is less than 0.09% by weight, thereby reducing the precipitation strengthening effect and coarsening the carbon and nitride particles in the final heat treatment process, thereby enhancing precipitation. By minimizing the effect, the strength of the alloy is reduced by about 10 kg / mm 2 and the modulus of elasticity is increased, resulting in excellent moldability of the alloy.

The present invention will be described through the following examples.

FIG. 2 is a process chart for preparing the material of the present invention, wherein a composition as shown in Table 1 was prepared according to FIG.

That is, vanadium is added to Ni-Fe, which is the composition of Table 1, and dissolved in vacuum to obtain a semi-finished product.

In the heat treatment diagram, homogenization heat treatment (diffusion annealing) is carried out at a temperature of 1,100-1,400 ° C. for about 24 hours to precipitate carbides or nitrides. Next, it was hot rolled to a predetermined thickness, pickled, and cold rolled to a thickness of 0.03 mm. And the final heat treatment at a temperature of 700-1100 ℃ to coarse crystal grains. As a result (Table 1), the yield strength of the present invention was reduced compared to the comparative material while the modulus of elasticity was high.

As can be seen from the above, the present invention can improve the moldability of the shadow mask as a result by reducing the yield strength and increasing the elastic modulus.

TABLE 1 Compositions and Physical Properties

Claims (1)

Brown (Ni) 30-45% by weight, vanadium (V) 0.01-0.09% by weight, the remainder is composed of iron (Fe) and inevitable trace elements (C, Si, Mn, P, S) Common shadow mask material.