JPS60134025A - Method for producing heat-resistant inorganic fibers - 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 The present invention relates to an inorganic fiber having high heat resistance and a method for producing the same.

Heat resistant, can be used continuously in high temperature atmospheres exceeding approximately 800℃! Ceramic NIL fiber is a typical JLL fiber, and in recent years, it has been used in steel manufacturing and various other metals, taking advantage of its excellent heat resistance, thermal shock resistance, light weight, electrical insulation, chemical stability, and sound absorption properties. Insulating materials, high temperature sealing materials, backings, sound deadening materials, etc. in industry, chemical industry, mechanical industry, etc.
It has become widely used as filter media. However, in recent years, the various types of equipment used in the above ceramic fiber application fields have tended to become more and more sophisticated.
As for the heat-resistant N&fiber materials used for this purpose, there has been a demand for even more heat-resistant materials. For example, the most commonly used aluminosilitate ceramic fiber is amorphous, but gradually crystallizes from around 1000℃, and consists mainly of mullite and free silica (or dopalite). Aluminosilicate ceramic fibers, which are advantageous over other ceramic fibers in many respects, are generally not suitable for use at temperatures above about 1500°C. Based on this, there have already been many attempts to produce fibers with better heat resistance, and typical methods include mixing chromium oxide into the raw material for producing aluminosilicate ceramic fibers, and mixing aluminum/ There are methods of attaching chromium oxide, alumina, phosphorus compounds, etc. to the surface of silicate ceramic fibers. Shigashina: These methods do not fundamentally suppress the formation of mullite, so the effect on heat resistance is not very significant.

Against the background of the above-mentioned current situation, the inventors of the present invention have conducted extensive research into aluminosilicate ceramic fibers with higher heat resistance. The present invention was completed based on the realization that the objective could be achieved by chemical modification to convert the molecule into a .

That is, the present invention provides a heat-resistant inorganic fiber obtained by converting at least the surface layer of an aluminosilicate ceramic fiber into a 5i-AI-0-N four-element compound, and a method for producing this fiber, which uses a delicate aluminum/silicate ceramic fiber. The surface is coated with a thin layer of carbon, and the resulting carbon-coated aluminosilicate ceramic fiber is treated with nitrogen, ammonia,
Provided is a method for heating in a nitrogen-ammonia mixture or a mixed gas of any of these and hydrogen to a temperature at which a 5iAl-0-N 4-element compound is produced from the aluminosilicate material constituting the 4&fiber. It is.

The heat-resistant fiber according to the present invention is a modified aluminosilicate ceramic fiber, as is clear from the -1-Bulletin Act, but the highly modified fiber is no longer considered an aluminosilicate ceramic fiber. It is a delicate ceramic with an unprecedented new composition. The 5i-AI-0-N4 elemental compound constituting the surface layer or the entirety of this fiber has a preferred formula S! It is represented by 5-zAl
ack.

J, Mat, Sci, 1135).

This compound has been considered only as a raw material for producing sintered bodies in the non-textile field, and there are no examples of fibers made from it being derived from aluminosilicate ceramic fibers, and there is no evidence that it has been made using other routes. There were no examples.

Fibrous S i-A I-○-N formed by chemical reaction between aluminosilicate ceramic fiber and nitrogen
The four-element compound is thermally extremely stable, and even if the entire 5i-AI-0-N four-element compound is not converted, the remaining part is still converted to thermally stable mullite. The fibers of the present invention do not suffer from the large shrinkage or strength loss associated with crystallization that occurs with aluminosilicate ceramic fibers, and therefore can withstand more severe conditions than aluminosilicate ceramic fibers.

Next, a method for producing the heat-resistant fiber according to the present invention will be explained.

As the aluminosilicate monolithic ceramic fiber ML used as a starting material, any one manufactured by a well-known conventional method can be used, but among them, 5i-AI-0
-N From the viewpoint of smooth conversion to a four-element compound, Si0235 to 55% by weight, A120365
~45% by weight, with the remainder being 5% by weight or less. Examples of commercially available aluminum/silicate ceramic mats with such compositions include Fineflex 1300 and Fineflex 1.
500 (both manufactured by NICHIAS Co., Ltd.), Su7 Rashir ()-11 manufactured by TcO Co., Ltd., etc. Textile: Diameter is 1
A thickness of ~10μ is preferred, and a value of 3 to 5μ is particularly preferred.

The method of coating the surface of raw fiber with a thin layer of carbon is as follows:
A dispersion of fine particulate carbon (e.g. carbon black, Gura 7 Eye F, etc.) or a carbon precursor (a substance that produces fine carbon powder when heated and carbonized, such as an organic material with a high carbon content such as phenol resin or acrylic resin) There is a method of spraying a solution of a compound) on 1 m of navy blue raw material or by dipping it (4 coats) and drying it, and then heating it in an inert atmosphere to a temperature at which the organic matter can be carbonized if a carbon precursor solution is used. However, it is not limited to these.

It is desirable that the fiber surface be coated as uniformly as possible with carbon particles in an amount of 5 to 30% by weight (particularly preferably 10 to 20% by weight) based on the fiber. Further, it is desirable that the carbon particles maintain a fine particle state with a diameter of i 2 /J or less (preferably (), 5 μ or less) on the fiber surface.

The above treatment of coating the surface of the aluminosilicate ceramic fiber with carbon may be carried out in the final step of producing the aluminosilicate ceramic fiber.

Next, the obtained carbon-coated aluminum/silicate ceramic fibers are placed in a sealable heating furnace, the furnace is sealed, and the inside of the furnace is heated to about 1 x in-' Torr or less (preferably 1 x 10
After creating a vacuum of -6 Torr, nitrogen, ammonia, a nitrogen-ammonia mixed gas, or a mixture of any of these and hydrogen is introduced to reduce the pressure to 0.1-200 Torr.
Kg/cm2, preferably i-100Kg/am2
16 (I (1-2000℃, preferably 1
Heat to 700 to 1800"C. Through this heat treatment, 5i-AI-0-N 4 with a thickness of around 0.1/7 is coated on the surface layer of the fiber for up to about 60 minutes, depending on the heating temperature.
An elemental compound layer is formed and further processing converts the whole into a 5i-AI-0-N quaternary compound (for fibers with a diameter of 3-5/J). During this heat treatment, the carbon that coated the raw material fibers was converted into Sio2 and Al2O,
acts as a reducing agent and promotes the nitriding reaction.

According to the present invention, 5i-AI-0-N
Highly heat-resistant inorganic fibers made of a four-element compound or this and mullite can be easily produced by modifying aluminosilicate ceramic fibers.

The present invention will be explained below with reference to Examples.

Example 1 Phenolic resin varnish・Plyopl+en J-32
5 (Dainippon Ink Co., Ltd. product) diluted twice with methanol, add aluminosilicate ceramic wL fiber Fine Flex 1300 to Chias Co., Ltd. product;
The above diluted solution was attached to the fiber AlE by immersing it (5i0248 weight%, Al□0152% by weight) at room temperature, and the treated fiber was dried under reduced pressure at 50°C-60mm 1-1g, and then at 800°C in a nitrogen atmosphere. By heating for 3 hours to carbonize the 7-enol resin on the surface, an aluminosilicate ceramic fiber coated with 10% carbon based on the weight of the fiber was prepared. Next, put this u & navy blue into a graphite crucible, place it in an electric furnace, and heat the inside of the furnace to 1X.
i After extracting air to 0-6 Torr, nitrogen gas was introduced and the nitrogen gas pressure was increased to 1 Ki? /cm2, then raise the temperature to 1800°C at a layer temperature rate of 30°C/min.
and heated for 120 minutes.

The mineral composition of the obtained fibers was analyzed using X-ray diffraction and an X-ray microanalyzer, and the results showed that the entire fiber was 5i-
It was confirmed that AI-0-N consists of a four-element compound.

Example 2 Aluminosilicate ceramic fibers were modified in the same manner as in Example 1, except that the time for heat treatment of the carbon-coated aluminosilicate ceramic T & navy blue in nitrogen was shortened to 30 minutes.

As a result of analyzing the mineral composition of the obtained fibers using X-ray diffraction and an X-ray microanalyzer, it was found that the surface layer with a thickness of approximately i/J was composed of a 5i-AI-0-N four-element compound;
It was confirmed that the core was made of mullite crystal.

A heating test was conducted at 1500°C for 3 hours on the products and raw material aluminosilicate ceramic ink #& navy blue according to each example (the shrinkage rate due to heating and the tensile strength after heating were measured.The results are shown in Table 1.

Table 1 p,! Msu1 Store (j12 Fi, ≧14fQ4 Shrinkage rate due to heating (%) 0.1 0.5 Is, 0 Tensile strength after heating (Kg/Cm") 1 S O11010 agent Patent attorney Itai Oboro

Claims (6)

[Claims] (1) A heat-resistant inorganic fiber obtained by converting at least the surface layer of aluminum/silicate ceramic N and navy blue into a 5i-AI-0-N four-element compound. (2) 5i-ALO-N 4-element compound has composition formula S
+6-zA 1202N, -2((IIL 2fi1.
The fiber according to claim 1, which is represented by a positive number from 0 to 4.2. (3) The fiber according to claim 1, in which the portion other than the portion consisting of the Si-AI-0-N four-element compound substantially consists of mullite. (4) The surface of the aluminosilicate ceramic fiber is coated with a thin layer of carbon, and the obtained carbon-coated aluminosilicate ceramic wL fiber is mixed with nitrogen, ammonia, a nitrogen-ammonia mixed gas, or a mixture of any of these and hydrogen. A method for producing a heat-resistant inorganic m-fiber, which comprises heating in a gas to a temperature at which a 5i41-0-N4 elemental compound is produced in the aluminosilicate material constituting the fiber. (5) Aluminum 7 silicate ceramic fiber or 5i02
The manufacturing method according to claim 4, wherein the content is 35 to 55% by weight, A1□0565 to 45% by weight, and the balance is 5% or less. (6) Carbon coated aluminum 7 silicate ceramic fiber! I
The manufacturing method according to claim 4 or 5, wherein the heating temperature of # is 16 (1 (1 to 2000°C).