JPH04337007A - Production of sintered sheet of metallic fiber - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a porous sheet used for filter materials, heat-resistant materials, conductive materials, etc.
The present invention relates to a method for manufacturing a metal fiber sintered sheet made of 00% metal fibers.

0002

BACKGROUND OF THE INVENTION Conventionally known 100% metal fiber sheet materials include wire mesh, webs, woven fabrics, and sintered bodies. Wire nets, webs, and woven fabrics are made by braiding or spinning single or multiple long metal fibers into a mesh or cloth shape, and sintered bodies are made by sprinkling powdered or short fiber metal. , which are fused by applying pressure and heating in a vacuum or inert gas. However, wire meshes, webs, and woven fabrics manufactured by braiding or spinning cannot be used to make thin sheets or those with small pore diameters, and sintered bodies manufactured using conventional manufacturing methods have poor productivity. There were problems such as large thickness unevenness and inability to manufacture long products.

[0003] Therefore, in order to solve the problems of the prior art described above, the present applicant first proposed a means for solving the problems in Japanese Patent Laid-Open No. 61-223105, that is, a metal fiber-rich sheet containing 70% by weight or more of metal fibers. proposed a method for producing a sintered metal fiber sheet in which fibers are sintered at a temperature not exceeding the melting point of the metal fibers in a vacuum or inert gas atmosphere. However, this manufacturing method has a problem in that the surface of the metal fiber lacks glitter, making it unfavorable in terms of appearance.

0004

[Problems to be Solved by the Invention] The present invention has been made in view of the above circumstances, and it is possible to obtain a sintered metal fiber sheet with a dense network structure, uniformity, thinness, and the luster characteristic of metals. A manufacturing method is provided.

[0005]

[Means for Solving the Problems] The present invention provides seven metal fibers.
A metal fiber-rich sheet obtained by forming a slurry of fibers containing 0% by weight or more into a sheet using a wet papermaking method is sintered between the fibers at a temperature not exceeding the melting point of the metal fibers in a hydrogen gas atmosphere. This is a method for manufacturing a sintered metal fiber sheet. The method for manufacturing the sintered metal fiber sheet of the present invention will be described in detail below.

[0006] First, a wet papermaking method is used to prepare a sheet with a high metal fiber content before sintering. That is, a slurry prepared to have a metal fiber content of 70% by weight or more is dehydrated and pressed using a wet paper-making method and then heated and dried to produce a sheet with a high metal fiber content. In this case, if the blending ratio of metal fibers is 70% by weight or less, sintering and fusion between the metal fibers will be inhibited during subsequent sintering. Examples of binder fibers used in wet papermaking include easily soluble PVA fibers with a solubility in water of 40 to 100°C, such as Kuraray Vinylon Fibrid VP (trade name) manufactured by Kuraray Co., Ltd. is preferably used.

Next, the sheet with a high metal fiber content obtained in this manner is heated in a dry hydrogen gas atmosphere at a temperature not exceeding the melting point of the metal fibers in order to prevent oxidation and increase the reduction effect on the surface of the metal fibers. Sinter the space between. The sintering temperature condition at that time is a temperature close to the melting point of the metal fiber, for example, in the case of stainless steel fiber, the sintering temperature is set to about 1200°C.
Sinter at a speed of 20 cm/min. In this case, sintering may be performed in a continuous sintering furnace using only hydrogen gas, or a continuous sintering process using an inert gas atmosphere furnace in combination with an inert gas atmosphere furnace such as nitrogen gas as a pre-process and a hydrogen gas atmosphere furnace as a post-process. It may also be carried out in a sintering furnace. In this case, the effect of preventing oxidation before sintering can be expected by using an inert atmosphere furnace in combination as a pre-process.

In the present invention, during the heating process in the sintering furnace, the nonmetallic fibers that are the binder in the metal fiber-rich sheet are thermally decomposed at about 400°C (in the case of PVA fibers).
As a result, the binding properties between the fibers are lost and the sheet becomes difficult to handle. However, when the temperature rises further, for example to about 800°C in the case of stainless steel fibers, some of the metal fibers begin to sinter and bonding between the fibers occurs, making it difficult to handle. It is possible to obtain a sheet with high physical strength. Further, in order to further stabilize the bonding and entangled state between the metal fibers, it is preferable to perform pressure treatment in a pre-sintering process, a post-sintering process, or during sintering.

[0009] The metal fibers used in the present invention are fibers made of stainless steel, titanium, brass, copper, aluminum, etc., with a fiber length of 2 to 12 mm, preferably 2 to 6 mm. Stainless steel fibers are preferably used in the present invention due to their durability and rust resistance.

0010

[Function] In the present invention, since the metal fibers are sintered in a hydrogen gas atmosphere, the reduction of the surface of the metal fibers is promoted by the reducing action of the hydrogen gas. Therefore, it is possible to obtain a metal fiber sintered sheet that has the luster characteristic of metals.

[0011]

EXAMPLES The present invention will be explained in more detail below with reference to Examples and Comparative Examples. Example 1 A slurry consisting of 90 parts by weight of stainless steel fibers with a fiber length of 4 mm and a fiber diameter of 8 μm and 10 parts by weight of PVA fibers (Fibribond VPB105-1 manufactured by Kuraray Co., Ltd.) having a solubility in water of 70° C. was dehydrated and pressed using a wet papermaking method. The sheet was dried by heating to obtain a metal fiber-rich sheet having a basis weight of 84 g/m2. Next, the sheet was sintered in a hydrogen gas-only continuous sintering furnace without applying pressure at a sintering temperature of 1180°C and a speed of 20 cm/min to give a basis weight of 82 g/m2 and a density of 1.1 g/c.
A sintered metal fiber sheet of the present invention having a diameter of m3 was produced. The volume resistivity value of the obtained sheet was 2.1×10−3
The metal fiber sintered sheet exhibits excellent electrical conductivity in Ωcm, has sufficient physical strength such as tensile strength that does not pose any practical problems, and has the luster characteristic of stainless steel due to its reduction action. It was done.

Example 2 During hydrogen gas sintering in Example 1, 20g/cm2
Everything was the same as in Example 1, except that pressure was applied while sintering was carried out.
A sintered metal fiber sheet of the present invention was produced in the same manner as described above. The volume resistivity value of the obtained sheet was 1.3×10-3Ω・
cm and exhibits excellent conductivity, with a density of 1.3 g/cm3
Furthermore, the metal fiber sintered sheet had sufficient properties such as tensile strength and other physical strengths that would cause no practical problems at all, and had glitter properties.

Example 3 A slurry consisting of 95 parts by weight of stainless steel fibers with a fiber length of 3 mm and a fiber diameter of 2 μm and 5 parts by weight of PVA fibers (Fibribond VPB105-1 manufactured by Kuraray Co., Ltd.) having a solubility in water of 70° C. was prepared using a wet paper-making method. A sheet with a high metal fiber content having a basis weight of 115 g/m 2 was produced by dehydration pressing and heating drying. Next, the sheet was sintered without applying pressure in a continuous sintering furnace using nitrogen gas in the first zone and hydrogen gas in the second zone at a sintering temperature of 1180°C and a speed of 15 cm/min to give a basis weight of 113 g/m2 and a density. A sintered metal fiber sheet of the present invention having a weight of 1.3 g/cm3 was obtained. The obtained sheet has a volume resistivity value of 2.7 x 10-3 Ωcm and exhibits excellent electrical conductivity.It is a metal fiber sintered sheet that also has the luster characteristic of stainless steel due to the hydrogen gas reduction action in appearance. Moreover, the physical strength such as tensile strength had sufficient properties without causing any practical problems.

Comparative Example 1 The metal fiber-rich sheet obtained in Example 1 was sintered in a vacuum sintering furnace at 1200° C. for 2 hours without applying pressure to produce a metal fiber sintered sheet. Although the metal fiber sintered sheet had approximately the same values in basis weight, density, and volume resistivity as the metal fiber sintered sheet of Example 1, it lacked brightness in appearance.

Comparative Example 2 The metal fiber-rich sheet obtained in Example 3 was sintered in a nitrogen gas-only sintering furnace at 1200° C. for 2 hours without applying pressure to produce a metal fiber sintered sheet. Although the metal fiber sintered sheet had approximately the same values in terms of basis weight, density, and volume resistivity as the metal fiber sintered sheet of Example 3, it lacked brightness in appearance.

[0016]

[Effects of the Invention] According to the present invention, it is possible to obtain a sintered metal fiber sheet with glittering properties that could not be obtained with the prior art. In addition, it can perform its functions in sheet materials without impairing the conductivity of the metal itself or the physical properties of the metal fibers themselves, and has sufficient interfiber strength, so it can be used in many industrial applications. .

Claims (2)

[Claims] Claim 1: A metal fiber-rich sheet obtained by forming a fiber slurry containing 70% by weight or more of metal fibers into a sheet by a wet paper-making method is heated under a hydrogen gas atmosphere at a temperature not exceeding the melting point of the metal fibers. A method for producing a sintered metal fiber sheet, characterized by sintering between the fibers. 2. The method for producing a sintered metal fiber sheet according to claim 1, wherein the metal fibers have a fiber length of 2 to 12 mm.