KR950001489B1 - Device and composition for liberating nitrogen gas during the manufacture of a cathode-ray tube - Google Patents

Abstract

None.

Description

Air Heating Delay Nitrogen Doping

1 is a cross-sectional view of a capsule containing a nitrogen release material according to the present invention.

2 is a cross-sectional view of a geta device using a capsule containing a nitrogen release material according to the present invention.

* Explanation of symbols for main parts of the drawings

102: capsule 104: holder

106: cylinder 202: getter device

204: holder 206: getter material

212 capsule

The present invention relates to the release of nitrogen in the production of cathode ray tubes (CRT).

Nitrogen release during CRT manufacturing is well known in the art. For example, US Pat. No. 3,973,816. Sometimes it is desirable to release nitrogen in two stages. For example, US Pat. No. 3,669,567 describes a getter device having a first stage nitrogen release prior to barium getter material evaporation and a second stage nitrogen release later in the barium evaporation.

In the CRT manufacturing process, it is common to go through a sealing process in which a soft glass frit is used to join the front part of the tube to the conical part. U.S. Patent No. 4,052,641 describes the heat treatment sequence in the pleat sealing process as follows.

From 25 ° C to 100 ° C at 3.5 ° C per minute

Hold 100 ℃ for -30 minutes

-From 8 ° C per minute to 100 ° C to 410 ° C

Hold at 410 ° C for -15 minutes

-Cool to 25 ° C at 4 ° C per minute

Although the pleat sealing process varies depending on the CRT particles, it can be seen from the above that a temperature of 400 ° or more, for example, 450 ° C. will be followed for 3-4 hours. It is extremely common for a color selection mask or shadow mask to be placed in a CRT before the pleat sealing process begins. The shadow mask is also used as an attachment location for the getter device. However, wherever the getter device is located, it will be appreciated that if the getter device is present in the pleat sealing process, the getter device will also reach temperatures above 400 ° C. and will be exposed to such temperatures for several hours. Unfortunately, it has been found that when a getter device having a second SOURCE goes through this state, the second nitrogen source would be disadvantageous when the getter device later flashes. The first disadvantage is that nitrogen is released at an undesirable time with respect to the evaporation of barium. Another disadvantage is that nitrogen is released so quickly that nitrogen pressure builds up in the CRT above the desired pressure range to effectively control the distribution and absorption capacity of the barium film. Another disadvantage is that too quickly liberating nitrogen results in small explosions of nitrogen-emitting materials and yields large amounts of fluidized particles. These moving particles enter the electron gun region of the CRT to cause an electrode short, but enter the shadow mask to block the passage of the image producing electron beam to degrade the screen quality. Therefore, it is an object of the present invention to provide a means for controlled release of nitrogen gas after undergoing a pleat sealing process.

It is another object of the present invention to provide a means for controlled release of nitrogen without yielding flow particles after the pleat sealing process.

It is another object of the present invention to provide a composition for controlled release of nitrogen after undergoing a pleat sealing process.

It is another object of the present invention to provide a capsule containing a composition for controlled release of nitrogen after undergoing a pleat sealing process.

These objects and advantages of the present invention will become apparent to those skilled in the art by reference to the following description and drawings.

It was unexpectedly found that a mixture of Fe ₄ N fines, Ni fines, and Al fines was capable of controlled release of nitrogen gas after a pleat sealing process heated in air at about 400 ° C. for about 4 hours.

When mixed with nickel powder and aluminum powder, the Fe ₄ N fines can have any particle size distribution that can withstand the pleat sealing process. However, the Fe ₄ N fine particles preferably have the following particle size distribution.

10-50% by weight 5㎛ or less

60-90% by weight 10㎛ or less

83-98 wt% or less

92-100% by weight 20㎛ or less

97-100% by weight or less

Ni fine particles may have any particle size distribution that can withstand the pleat sealing process, but it is preferable to have the following particle size distribution.

0-9% by weight 5㎛ or less

7-28% by weight 10㎛ or less

21-46% by weight 15㎛ or less

35-56% by weight 20㎛ or less

49-65% by weight or less

58-75% by weight 40㎛ or less

69-86% by weight 60㎛ or less

78-93% by weight 80㎛ or less

At least 92% by weight 100μm or less

Al fine particles may have any particle size distribution that can withstand the pleat sealing process, but it is preferable to have the following particle size distribution.

4.5-9% by weight 40㎛ or less

7-16% by weight 60㎛ or less

15-25% by weight 80㎛ or less

20-45% by weight 100㎛ or less

30-60% by weight 150μm or less

At least 95% by weight 250μm or less

The weight percentages of Fe ₄ N, Ni and Al can vary widely. Fe ₄ N fine particles are preferably present at 40 to 80% by weight. In the composition below 40%, Fe ₄ N is insufficient to make a suitable pressure in the CRT, and above 80%, Ni and Al are insufficient to cause a sufficient exothermic reaction to assist the nitrogen release. Ni should be present at 20-40% by weight. Less than 20% by weight of insufficient Ni for exothermic reaction to assist in the release of N ₂ , and more than 40% by weight of Ni results in too much exothermic and there is a risk of releasing N ₂ too quickly. Al should be present in a weight percent of 5% to 20%, and if the weight percent of Al is less than 5%, Al is insufficient to produce sufficient heat in an exothermic reaction for releasing N ₂ from Fe ₄ N, and the weight of Al If the% is above 20%, an exothermic reaction will occur so violently that N ₂ will be released too quickly. The nitrogen release composition is therefore preferably in the proportion of Fe ₄ N 60%, Ni 320% and Al 10%.

In the broadest polar plane of the present invention the ratio of Ni to Al can vary widely and is generally chosen to generate the maximum amount of heat when Ni is blended with Al. Generally, the maximum amount of heat is generated in the weight ratio of Ni to Al in the range of 1:10 to 10: 1, but the ideal ratio of Ni to Al is about 3: 1.

In the broadest polar aspect of the present invention, the ratio of the combined weight of Fe ₄ N to Ni and Al is generally selected to sufficiently release all of the nitrogen from Fe ₄ N within a very short time of less than 5 seconds and preferably less than 3 seconds. Fe ₄ N Typically present in the composition in a weight ratio of 1: 5 to 5: 1 relative to the combined weight of Ni and Al, preferably in a weight ratio of 1: 2 to 2: 1.

In use, the composition is preferably employed as a second nitrogen source in an N ₂ doped getter, preferably contained in a capsule-like holder. The capsule is made of any suitable material, for example ceramics, for the mixture, and may be made of metal. Nichrome or stainless steel are even better. Any hole in a suitable form may be used, but it is preferred that it is in the form of a closed hollow cylinder on one side.

Such nitrogen release capsules for use in so-called "delayed nitrogen doped getters" will now be described with reference to FIGS.

Reference numeral 102 in FIG. 1 is a nitrogen gas releasing capsule, which is in the form of a cylinder 106 with one end 108 closed. The open end 110 here opens horizontally in the form of a flange 112. The flange 112 has a series of tidal bands 114, 114 ′, 114 ″ for use in subsequent protrusion reception.

Figure 2 illustrates the use of a nitrogen gas releasing capsule as a delayed nitrogen doped gas source or a second gas source in a nitrogen doped getter. The evaporable getter device 202 includes a ring shaped holder 204 that supports the evaporable getter metal air release material 206.

The getter material, which is easy to evaporate, is generally composed of a barium aluminum alloy of BaAl ₄ composition mixed with Ni powder of approximately equal weight. In addition, usually a small amount of Fe ₄ N is mixed as the first nitrogen source. This mixture is any mixture known in the art that can withstand the pleat sealing process (eg US Pat. No. 4,077,899). The getter device 202 that is prone to evaporation in this particular embodiment also includes a reflective shield 208 that serves to support the porcelain disc 210 so that the heated getter device does not break adjacent glass walls of the CRT. In all respects, the same nitrogen gas releasing capsule 212 as the capsule 102 shown in FIG. 1 is protruded into the central portion of the reflective shield 208.

The term "composition of a substance for nitrogen gas release" as used herein and in the claims is used to include both compositions before and after nitrogen gas release.

This predicate includes a material in solid form sold as a getter device and a substance in which most of the nitrogen in the working tube is evaporated from the composition and chemically bonded to the getter membrane on the inner surface of the tube.

In addition, the term [getter metal vapor release material] as used herein and in the claims is used to include both bismuth materials before and after the getter metal vapor release. This predicate includes a material in the form sold as a getter device and a material in which most of the getter metal in the working tube is evaporated from the material into a film on the inner surface of the tube.

The composition of the present invention has the property of not releasing particles even after being heated in air at 100 ° to 450 ° C. for 2 hours.

Example 1

This example was carried out to demonstrate the behavior of prior art material compositions for the release of N ₂ gas contained in hollow cylinders of stainless steel after a pleat sealing process in air. A powder mixture comprising 60% by weight of Fe ₄ N with good particle size as described above was prepared. This mixture also contains 30% of powdered titanium having a particle size distribution as follows and 10% of Al fine particles having a particle size distribution as described above.

2-20 wt% or less

15-40.2% by weight 20㎛ or less

30-70% by weight or less

50-90% by weight or less

80-92% by weight 50㎛ or less

At least 90% by weight less than 60㎛

About 43 mg of this mixture is placed in a hollow cylinder and subjected to heat at 450 ° C. for 2 hours in air.

The cylinders are then placed in a vacuum system and heated to release N ₂ . Violent reactions occurred and particles of the composition were ejected into the system.

Example 2

This example shows that nickel having a particle size distribution as described in US Pat. No. 4,077,899, which promotes the use of nickel to avoid excessive exothermic reactions in compositions for nitrogen gas release, is used instead of titanium. It was carried out under the same conditions as in Example 1. This distribution is as follows.

0 wt% less than 15㎛

0.1-0.2% by weight 20㎛ or less

3-10 wt% or less

22-60% by weight 40㎛ or less

70-96% by weight 50㎛ or less

86-99% by weight 55㎛ or less

97-100% by weight or less

In this case too, a violent reaction occurred, causing particles of the composition to be ejected into the system.

Example 3

This example was carried out to demonstrate the behavior of the material composition for nitrogen gas release of the present invention contained in a capsule after the pleat sealing process. A powder mixture having the same weight composition and particle size range as described above was prepared except that Ni was replaced with Ni having a particle size distribution that followed a good Ni distribution. Getter capsules were exposed to air at the same temperature for the same time as in Example 1. When the capsule to emit the N ₂ N ₂ in the vacuum system was found to be emitted in a controlled flow to any particle without discharge method from the capsule.

While the invention has been described in detail with reference to certain preferred embodiments and applications, it is to be understood that changes and variations are possible within the spirit and scope of the invention as set forth and defined in the following claims.

Claims (9)

(A) Fe ₄ N fine particles (B) 0-9 wt% or less 5㎛ 7-28% by weight 10㎛ or less 21-46% by weight 15㎛ or less 35-56% by weight 20㎛ or less 49-65% by weight or less 58-75% by weight 40㎛ or less 69-86% by weight 60㎛ or less 78-93% by weight 80㎛ or less At least 92% by weight 100μm or less Ni particles having a particle size distribution of and (C) a composition for nitrogen gas discharge, characterized in that composed of fine particles. The method of claim 1, wherein the ratio of Ni to Al is selected as a ratio capable of calculating the maximum amount of heat when Ni and Al are combined, and Ni and Al are almost all nitrogen from Fe ₄ N. A composition, characterized in that it is present in a sufficient amount to generate enough heat to release the heat. The method according to claim 1, wherein the weight ratio of Ni to Al, i.e., (b) is 1:10 to 10: 1; A weight ratio of the weight of Fe ₄ N to the bond of Ni and Al, that is, (a): [(b) + (c)] is 1: 5 to 5: 1. The controlled release of nitrogen gas after heating in air at a temperature of 100 ° C. to 450 ° C. for 2 hours, which is composed of a siliceous mixture of the following components: (A) 10-50% by weight or less 60-90% by weight 10㎛ or less 83-98 wt% or less 82-100% by weight 20㎛ or less 97-100% by weight or less Fe ₄ N fine particles having a particle size distribution of; (B) 0-9 wt% or less 5㎛ 7-28% by weight 10㎛ or less 21-46% by weight 15㎛ or less 35-56% by weight 20㎛ or less 49-65% by weight or less 58-75% by weight 40㎛ or less 69-86% by weight 60㎛ or less 78-93% by weight 80㎛ or less At least 92% by weight 100μm or less Ni fine particles having a particle size distribution of; (C) 4.5-9% by weight or less 7-16% by weight 60㎛ or less 15-25% by weight 80㎛ or less 20-45% by weight 100㎛ or less 30-60% by weight 150μm or less At least 95% by weight 250μm or less Al fine particles with a particle size distribution of (1) one holder; (2) (a) Fe ₄ N fine particles contained in the holder, (B) 0-9 wt% or less 5㎛ 7-28% by weight 10㎛ or less 21-46% by weight 15㎛ or less 35-56% by weight 20㎛ or less 49-65% by weight or less 58-75% by weight 40㎛ or less 69-86% by weight 60㎛ or less 78-93% by weight 80㎛ or less At least 92% by weight 100μm or less A nitrogen gas-releasing capsule composed of a mixture of Ni fine particles having a particle size distribution of and (C) Al fine particles. The method according to claim 5, wherein the weight percent of (a) (b) (A) 40 to 80% (B) 20 to 40% (C) 5 to 20% Nitrogen gas release capsule, characterized in that in the range of. (1) a hollow cylinder with one end closed; (2) compressed in the cylinder, (A) 10-50% by weight or less 60-90% by weight 10㎛ or less 83-98 wt% or less 92-100% by weight 20㎛ or less 97-100% by weight or less Fe ₄ N fine particles with a particle size distribution of, (B) 0-9 wt% or less 5㎛ 7-28% by weight 10㎛ or less 21-46% by weight 15㎛ or less 35-56% by weight 20㎛ or less 49-65% by weight or less 58-75% by weight 40㎛ or less 69-86% by weight 60㎛ or less 78-93% by weight 80㎛ or less At least 92% by weight 100μm or less Ni fine particles having a particle size distribution of (C) 4.5-9% by weight 40㎛ or less 7-16% by weight 60㎛ or less 15-25% by weight 80㎛ or less 20-45% by weight 100㎛ or less 30-60% by weight 150μm or less At least 95% by weight 250μm or less Consisting of a homogeneous mixture of Al fine particles having a particle size distribution of, the weight percent in the mixture is (b) 1: 10 to 10: 1, (a): [(b) + ( )] Is 1: 2 to 2: 1 in a delayed nitrogen doped getter for heating under air at a temperature of 100 ° C. to 450 ° C. for 2 hours and then releasing a second source of nitrogen gas under control. Nitrogen gas release capsule for use in The getter device according to claim 1, wherein the getter device is easy to evaporate in mixing the substance composition of claim 1. The gear device as claimed in claim 5, wherein the capsule of claim 5 is mixed.

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