JPS60167926A - Production of heat-resistant inorganic fiber - Google Patents

Abstract

PURPOSE:To obtain the titled fibers having improved mechanical properties, by firing fibers prepared from a specific silicon compound, aluminum compound and material containing carbon atoms as main raw materials in a nitrogen atmosphere to convert the silicon and aluminum compounds into a compound containing Si-Al-O-N elements. CONSTITUTION:(A) A silica-forming silicon compound, e.g. colloidal silica, (B) an alumina-forming compound, e.g. alumina sol, and (C) a material, containing carbon atoms, and same or different from the component (A) or (B) as main saw materials are dissolved or dispersed in water, and a water-soluble organic polymer, e.g. polyvinyl alcohol, is added thereto to impart fiber-forming properties to the solution or dispersion. The resultant spinning dope is then deaerated and spun to give precursor fibers, which are then fired in a nitrogen atmosphere to convert the silicon and aluminum compounds in the fibers into a compound containing Si-Al-O-N elements and give the aimed fibers.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an inorganic fiber having a high degree of heat resistance.

Ceramic fiber is a typical heat-resistant fiber that can be used continuously in high-temperature environments exceeding approximately 800℃.
In recent years, its excellent heat resistance, thermal shock resistance, light weight, electrical insulation, chemical stability, sound absorption properties, etc. have made it popular as a heat insulating material and high temperature material in steel manufacturing and other metal industries, chemical industry, machinery industry, etc. Sealing materials, reinforcing materials, bunking, sound deadening materials,
It has become widely used as filter media. However, in the case of aluminosilicate ceramic fiber, which is the most typical ceramic fiber, its heat resistance limit temperature is approximately 1.
Although it is said to be 500'C, deterioration actually occurs even at temperatures much lower than that. In other words, when this fiber is heated to about 980°C or higher, it forms mullite crystals (3A+
203.2SiOz) causing volumetric contraction,
It becomes brittle. Another disadvantage is that only short fibers with a maximum length of about 100 to 200 m+o can be obtained, and the content of granules is large. In addition, polycrystalline alumina fibers produced by molding precursor fibers from a viscous solution containing an aluminum compound as a main component and firing the fibers have a melting point of 20
The main component is alumina at 50°C, and it is essentially highly heat resistant, but at temperatures above about 1200°C, it undergoes furangum (α-A +
20), which tends to reduce strength and become brittle, so the practical heat resistance limit of this fiber is also not very high.

On the other hand, in recent years, the various types of equipment in which these heat-resistant fibers are used have tended to become more and more sophisticated, and as a result, the heat-resistant fiber materials used there are also required to have even better heat resistance. became.

The present invention was completed as a result of intensive research by the present inventors in search of ceramic fibers having higher heat resistance against the background of the above-mentioned current situation, and includes silica-forming silicon compounds, An aqueous solution containing an alumina-forming aluminum compound and a carbon atom-containing substance that is the same as or different from the silicon compound or aluminum compound in a dissolved state or a colloidal state and has fiber-forming ability is made into fibers, and the obtained fibers are heated in a nitrogen atmosphere. By firing, the silicon compounds and aluminum compounds in the fibers are converted into 5i-AI-(
) A method for producing a heat-resistant inorganic fiber is provided, which is characterized by converting N into a four-element compound.

The fiber obtained by the production method of the present invention has substantially 5iAI
-0-N A novel fiber made of a four-element compound. The preferred composition is this 5i-AI-
The 0-N four-element compound is known as a raw material for producing sintered bodies in the non-textile field (K.

H, Jack, JoMat-3ci,, 11 * 1
135). However, no examples have yet been found where fibers made from this compound have been produced.

The fiber made of the 5iAI-0-N four-element compound obtained by the production method of the present invention is not only extremely thermally stable but also has excellent mechanical properties.
It can withstand use under extremely harsh conditions without causing significant shrinkage or strength loss due to crystallization, which occurs with aluminum/silicate ceramic fibers.

Next, the method for producing the above-mentioned heat-resistant fiber according to the present invention will be explained in order of steps.

As fiber manufacturing raw materials such as silicon compounds, aluminum compounds, and carbon atom-containing substances, those that are well soluble in water or dispersed in colloidal form are used. As the silicon compound, there may be used a compound that produces silica by dehydration or thermal decomposition when heated to about 1000° C. or higher, such as Frogl silicate, hydrolyzate of ethyl silicate, organosilicon polymer, and the like.

As the aluminum compound, a compound that produces alumina by dehydration or thermal decomposition when heated to about 1000° C. or higher, such as alumina sol, aluminum acetate, aluminum lactate, aluminum chloride, aluminum oxychloride, aluminum sulfate, aluminum alflate, etc. is used. . The quantitative ratio of the silicon compound to the aluminum compound is preferably such that the molar ratio of Sio2 and A1□O1 is 1:3 to 10:1.

The carbon atom-containing substance is carbonized in the firing process in a nitrogen atmosphere described later, and then the following 5iAl-() is used as a reducing agent.
Participates in the reaction of producing N4 element compounds.

2ZAI203 + 4(6Z)SiO2+ 3(8Z
)C+ 2(8-Z)N2=4S 16-zA l□O
, N, -□+3(8-Z)Co2 (however, Z is 1.0 to 4
．． 2 positive number) The amount of carbon required for this reaction is, for example, when Z = 4,
The amount is about 11% by weight based on the weight of the fiber. If the silicon compound or (and) aluminum compound used as a raw material is a compound containing carbon atoms and can serve as a sufficient carbon source, there is no need to supply carbon for the above reaction. In order to have an amount of carbon present,
It is desirable to separately add a carbon atom-containing substance. As the carbon atom-containing substance used for this purpose, water-soluble organic polymers that are added to give the raw material solution fiber-forming properties described later are also useful, but higher alcohols, carbon black, etc. can also be used. .

A spinning solution is prepared by dissolving or dispersing the above main raw materials in water, and adding a water-soluble organic polymer such as polyvinyl alcohol, polyethylene oxide, zaryacrylamide, etc. to impart fiber-forming ability. The concentration of the spinning solution suitable for fiberization is 20 to 60% by weight, and the viscosity is 10 to 100%.
0 poise, and if necessary for this purpose, concentration is carried out accordingly.

The spinning solution prepared as described above is degassed and then spun.
Produce precursor fibers. As a spinning method, any method such as centrifugation, extrusion, or blowing can be adopted, but the most advantageous method is to extrude the spinning solution from a spinning nozzle placed downward, and immediately send it downward at high speed. In this method, the material is pulled by an air current to be thinned, and at the same time, hot air is blown from the side to dry it and solidify it into a filament.

The obtained precursor fiber is gradually heated in a nitrogen atmosphere,
First, organic substances are carbonized and silicon compounds and aluminum compounds are converted into silica and V-alumina.

After that, continue heating to reach a maximum temperature of 1500 to 1800.
By raising the temperature to .degree. C. and keeping it at this temperature for several minutes to several hours, the conversion to the 5i-AI-0-N four-element compound by the reaction described above occurs. In this case, carbon monoxide or methane may be mixed into the atmospheric gas to act as a reducing agent. The formation of the 5i-AI-0-N four-element compound can be confirmed by mineral analysis using X-ray diffraction. .

As described above, according to the manufacturing method of the present invention, using common raw materials, it is possible to easily and highly The result is to manufacture high-performance heat-resistant WL units with high productivity.

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

Example 1 Flougl Silica 20% liquid (Nissan Chemical, S/-Te NxO) and aluminum hydroxychloride, A1□ (OH
) and SC120% aqueous solution at a ratio of 1:3, 3% by weight of polyvinyl alcohol was added and dissolved, and the mixture was concentrated under reduced pressure at 40° C. to prepare a spinning solution with a viscosity of 60 bores. This spinning solution was extruded from a spinning nozzle and immediately pulled by a high-speed air stream to be thinned, and at the same time, hot air was blown from the side to dry it and solidify it into a filament.

The obtained precursor fibers were then transferred to a firing furnace and heated at a temperature increase rate of 200°C/hr while flowing nitrogen gas to a temperature of 17°C.
The temperature was raised to 00°C, held at this temperature for 10 minutes, and then slowly cooled.

The resulting fibers essentially consisted of a 5iAl-0-N four-element compound, had an average diameter of 8μ, and a tensile strength of 120 Kg.
/mm2.The tensile strength after heating at 1500℃ for 3 hours is 10
0g/IaI was 112.

Example 2 Ethyl silica) 100 parts by weight, ethanol 300i
i part, 17.8 parts by weight of water, and 4 parts by weight of 2N hydrochloric acid were mixed and stirred for 5 hours, and a 10% aqueous solution of aluminum formate was mixed with 1 part
After adding 0.01% of polyethylene oxide to the mixed solution, the mixture was concentrated under reduced pressure at 40'C to prepare a spinning solution having a viscosity of 400 poise. This spinning solution is extruded from a spinning nozzle to form fibers at a circumferential speed of 100 m/min.
It was wound up with a rotor.

The obtained precursor fibers were then transferred to a firing furnace and heated at a temperature increase rate of 200' (:/hr) while flowing nitrogen gas.
The temperature was raised to 800''C and slowly cooled while maintaining this temperature for 5 minutes.

The obtained WL fibers are substantially made of 5i-AI-0-N 4-element compound +), have an average diameter of 11μ, and a tensile strength of -'Ha1.
70 Kg/ml112.The tensile strength after heating at 1500°C for 3 hours was 160 Kg/mm2.

Agent: Patent Attorney San Itai

Claims (2)

[Claims] (1) Fiberizing an aqueous solution containing a silica-forming silicon compound, an alumina-forming aluminum compound, and a carbon atom-containing substance that is the same or different from the silicon compound or aluminum compound in a dissolved or colloidal state and has fiber-forming ability, A method for producing heat-resistant inorganic materials #& miscellaneous, which comprises firing the obtained fibers in a nitrogen atmosphere to convert silicon compounds and aluminum compounds in the fibers into 5i-AI-0-N four-element compounds. (2) Si41-0-N four-element compound has the composition formula Si
, -zA hO-N,, -, (however, 2 is 1.0 to 4.2
The manufacturing method according to claim 1, which is expressed by a positive number).