JP2001181796A - Fe-Ni-Co ALLOY EXCELLENT IN ETCHING CHARACTERISTIC AND LOW THERMAL EXPANSION CHARACTERISTIC, AND SHADOW MASK EXCELLENT IN ETCHING PIT SHAPE CHARACTERISTIC - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an alloy having excellent etching characteristic and low thermal expansion characteristic and to provide a shadow mask excellent in etching pit shape characteristic. SOLUTION: This Fe-Ni-Co alloy has a composition consisting of, by mass, >2.5-7% Co, Ni in an amount satisfying (Ni+Co)=35.5 to 38%, <0.1%, preferably <=0.05%, of Mn, and the balance essentially Fe, and C is controlled to <0.005% and further S and Cr are controlled to <=0.0015% and <=0.1%, respectively. The shadow mask is composed of these Fe-Ni-Co alloys.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an Fe--Ni--Co alloy for a shadow mask used in a color cathode ray tube, and more particularly to a material excellent in low thermal expansion characteristics. And, it relates to the produced shadow mask.

[0002]

2. Description of the Related Art A shadow mask incorporated in a cathode ray tube for performing color discrimination includes, in addition to a press-molding type shadow mask in which a press molding process is performed to obtain a predetermined shape during a manufacturing process, depending on the type of the cathode ray tube, tension is applied. There is a stretchable shadow mask that is supported by a mask frame frame in a state in which is provided. As for the technical trend of cathode ray tubes used in televisions and personal computers, recently, the trend is toward larger size, flatter and higher definition. Along with this, the characteristics required for the shadow mask material used are:
Current ordinary Fe-Ni based invar alloy (Fe-36%
There is a demand for lower thermal expansion than the thermal expansion characteristics obtained with Ni).

The following two methods have been disclosed as methods for further reducing the thermal expansion of Fe--Ni-based invar alloys having a normal composition. One is that the main component is Fe-36% N
i is to suppress impurities, and the other is Co
To form a Fe—Ni—Co system. Known examples in which low thermal expansion is achieved by these effects are disclosed in JP-A-61-76651, JP-A-7-3401, and JP-A-8-801.
There is 311622. JP-A-8-209306, JP-A-8-33338, and JP-T-8-512363 are examples of those in which the amount of Co is suppressed to the minimum addition amount.

[0004]

The above means is effective as a method for obtaining excellent low thermal expansion characteristics. However, in the case of a material for a shadow mask, it is required that a high-definition electron beam passage hole can be etched and formed in an accurate shape. With the traditional method,
From this viewpoint, the study of the amount of Co and the study of trace elements cannot be said to be sufficient. As a result, for example, in order to obtain low thermal expansion characteristics,
Although a certain cost improvement is sacrificed by the inclusion of o, the etching properties are poor unless the trace elements are adjusted.

Accordingly, an object of the present invention is to provide an alloy which has an excellent low thermal expansion characteristic and also has a sufficient etching property. The purpose is to provide.

[0006]

In order to solve the above-mentioned problems and to put the invention into practical use, the present invention has conducted a detailed investigation on the amount of Co and the component range of trace elements from the viewpoint of low thermal expansion characteristics and etching properties. It has been found that a material having the following components is effective.

That is, in mass%, Co: more than 2.5% and 7% or less, (Ni + Co): 35.5-38%, M
n: Fe-Ni-Co-based alloy containing less than 0.1%, preferably 0.05% or less, and the balance substantially consisting of Fe, wherein C is less than 0.005%, and S is 0% .0
Fe-N with 015% or less and Cr less than 0.1%
It is an i-Co alloy. And these Fe-
A shadow mask made of a Ni-Co alloy, which has excellent low thermal expansion characteristics, reduces distortion of etching holes, and is excellent in smoothness of its inner shape.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The most important feature of the present invention is to achieve an alloy having excellent etching properties and low thermal expansion properties.
As a result of taking into account in detail the effect of each of the Co content and the trace element range on the properties of the Invar alloy as well as the phenomenon occurring in the inner shape of the etching hole formed by etching, the alloy of the present invention It has been found. Hereinafter, the alloy components constituting the present invention and the reasons for the limitation will be described.

Co: It is known as an element for lowering the coefficient of thermal expansion in an Fe-Ni-based invar alloy. In the case of the present invention, in addition to the adjustment of the amount of Mn to be described later, by solving the problem of the etching property due to the low Mn, the excellent low thermal expansion characteristic based on the effect of the Co content of the present invention is achieved. We have found a means that can achieve this and also achieve excellent etching properties.

[0010] In particular, when the alloy of the present invention is applied to a shadow mask, for example, the effect of improving the color shift of a cathode ray tube is 30% less than the thermal expansion coefficient of an ordinary Invar alloy.
%, The significant difference can be obtained. Specifically, excellent low thermal expansion characteristics are achieved with a Co content exceeding 2.5%. In addition, Co has a very high raw material cost and a content exceeding 7% saturates the effect of improving the low thermal expansion characteristic. Therefore, in the present invention, the content of Co exceeds 2.5% to 7%. It was as follows.

Mn: an element that improves hot workability, but has an effect of increasing the thermal expansion coefficient of an Fe—Ni-based invar alloy or an Fe—Ni—Co-based invar alloy. In the present invention, the content is set to less than 0.1% in order to sufficiently achieve the mutual effect of the above. Preferably, it is 0.05% or less.

C: To achieve excellent low thermal expansion characteristics, C:
In the Fe—Ni—Co-based alloy of the present invention in which an appropriate amount of o is added, the adjustment of the C content is effective in compensating for an obstacle to the etching property due to the Co addition. That is, the addition of Co lowers the etching rate, and there is a fear that distortion of the etching hole may occur. Then, when it examined in order to improve this subject, Fe-Ni-C which has Co content of this invention
In an o-based alloy, it was found that the reduction of the C content was effective. Specifically, the C content is 0.005%
Less than.

By limiting the S: Mn content from the conventional 0.25% level to less than 0.1%, a new problem (FIG. 2) arises that the contour of the inner hole of the etching hole is deformed jaggedly. In this case, there is a possibility that a problem may occur in application to a shadow mask requiring high definition (particularly, a shadow mask for a personal computer). When this problem was investigated, it was found that the process differs from the distortion of the etching hole due to the decrease in the etching rate in view of the site where the problem occurred. Then, when various trace elements were investigated, it was found that this problem could be solved by suppressing the amount of S to be low, and a normal etching hole could be formed.

That is, the phenomenon that the inner contour of the etching hole is jagged is caused by the fact that S in the matrix is not fixed by reducing the amount of Mn, and the amount of S existing in the grain boundary increases. It is thought to be the result of increased susceptibility. In order to solve this problem, it is effective to suppress the amount of S. In the case of the present invention, suppressing S to 0.0015% or less is necessary for obtaining a shadow mask having excellent smoothness of the inner shape of the etching hole. preferable.

Cr: Cr is an element that increases the coefficient of thermal expansion of the alloy of the present invention and needs to be 0.5% or less, but is preferably reduced to 0.1% or less.
The effect of increasing the coefficient of thermal expansion can be sufficiently eliminated.

In the present invention, it is important to optimally adjust the (Ni + Co) amount in addition to the Co content in order to achieve excellent low thermal expansion characteristics. Specifically, (Ni +
By adjusting the Co) amount to 35.5 to 38%, it is possible to maintain low thermal expansion characteristics sufficient for application to a shadow mask. Preferably, 30% more than Fe-36% Ni material
As a composition range effective for achieving the above-mentioned low thermal expansion coefficient, the case where Co: 3.3% (Ni + Co) is 35.5 to 35.5%.
When 37.5% and Co: 5%, (Ni + Co) is 3
5.5-38.0%.

In the case of the Fe—Ni—Co alloy of the present invention, for example, Si used as a deoxidizing agent in the melting process is used.
Is also possible, and specifically, may contain 0.1% or less, preferably 0.05% or less of Si.

If the above-described Fe—Ni—Co alloy of the present invention is applied to, for example, a shadow mask,
In addition to its excellent low thermal expansion characteristics, an electron beam passage hole having an accurate hole shape is also formed, so that it is most suitable as a shadow mask material.

[0019]

EXAMPLES (Example 1) An Fe-Ni-Co alloy was melted and cast in a vacuum induction melting furnace to produce an ingot having the components shown in Table 1. Forging this ingot,
A plate material having a thickness of 10 mm was used. For the measurement of the coefficient of thermal expansion, a test piece of 5 mmφ × 20 mmL was prepared from the forged plate material, and then annealed at 800 ° C. for 30 minutes in a N ₂ atmosphere condition. The measurement temperature range of the coefficient of thermal expansion was 30 to 100 ° C. The results are summarized in Table 1.

[0020]

[Table 1]

The results in Table 1 are summarized in FIG. 3 as the effect of the (Ni + Co) amount on the thermal expansion coefficient corresponding to each Co amount. From FIG. 3, even if the alloy satisfies the Mn content of the present invention, the Co content of the present invention is more than 2.5% to 7% and ( Ni + C
o) An alloy whose amount is adjusted to 35.5 to 38% has a smaller coefficient of thermal expansion, and can also achieve low thermal expansion characteristics effective for improving color misregistration when used as a shadow mask. The composition range in which the coefficient of thermal expansion is 30% or more lower than that of the Fe-36% Ni material is as follows: Co: 3.3% (Ni + Co): 35.5 to 37.5%, Co: 5% , (Ni + C
o) is 35.5-38.0%.

(Example 2) An ingot having the components shown in Table 2 was produced by the same manufacturing method as in Example 1 described above, and a plate material having a thickness of 3 mm was formed by forging and hot working.
Then, cold rolling and annealing are repeated to obtain a thickness of 0.12 mm.
And a thin plate test material for etching property evaluation.
The etching property is determined by using a FeCl ₃ solution at a concentration of 47B.
Under conditions of e degree, temperature: 50 ° C., and spray pressure: 2 kg / cm ² , a judgment was made based on an etching rate when an etching hole was formed in the shape of the shadow mask and a contour shape of the hole in the etching hole.

In the determination of the inner shape of the etching hole, if the inner shape of the hole is smooth, it is evaluated as ○. If the shape is slightly jagged but is not hindered in use as a shadow mask, Δ is indicated. Was evaluated as "poor" when there was a possibility that the use as a shadow mask might be hindered. 1 and 2 are observations of the etching hole according to the above determination by an electron microscope of 300 times and 1000 times, and FIG. 1 in which the inner surface shape of the etching hole has a smooth circle is evaluated as ○, and , FIG. 2 corresponds to the evaluation x. The results are shown in Table 2.

[0024]

[Table 2]

According to Table 2, Mn: Fe-N of less than 0.1%
In the i-Co alloy, C is suppressed to less than 0.005%, and S is further suppressed to 0.0015% or less, whereby a decrease in the etching rate can be suppressed, and the inner surface shape of the etching hole is also reduced. It can be seen that it can be improved.

[0026]

According to the present invention, a material having a lower thermal expansion can be obtained than a conventional Fe-Ni-based invar alloy, and the cost and cost can be reduced.
As for the etching property, a material that satisfies the required cost and performance of the shadow mask can be obtained. As a result, it is possible to apply the invention to a shadow mask such as a press molding die or a stretch type, and to improve the image quality of a cathode ray tube.

[Brief description of the drawings]

FIG. 1 is an electron micrograph showing an inner surface shape of an etching hole.

FIG. 2 is an electron micrograph showing an inner surface shape of an etching hole.

FIG. 3 is a diagram showing an example of the effect of the present invention.

Claims (5)

[Claims] 1. A mass% of Co: more than 2.5% and 7% or less, (Ni + Co): 35.5-38%, Mn: 0.1
% Fe-Ni substantially less than Fe
-A Fe-Ni-Co-based alloy which is excellent in etching properties and low thermal expansion characteristics, characterized in that C is suppressed to less than 0.005%. 2. The Fe—Ni—Co alloy according to claim 1, wherein the Fe—Ni—Co alloy is excellent in etching properties and low thermal expansion properties in a content of Mn: 0.05% or less by mass. 3. The Fe—Ni—Co excellent in etching properties and low thermal expansion properties according to claim 1 or 2, wherein S is suppressed to 0.0015% or less by mass%.
System alloy. 4. The Fe—Ni excellent in etching properties and low thermal expansion characteristics according to claim 1, wherein Cr is suppressed to 0.1% or less by mass%.
-Co-based alloy. 5. The F according to claim 1, wherein
A shadow mask having an excellent etching hole shape, comprising an e-Ni-Co alloy.