KR910006396B1 - Manufacturing method of stabilized zirconia staple fiber - Google Patents

Abstract

Acetylacetone with equivalent ratio of 0.3-1.5 is added to zirconium alkoxide. One compound which is selected among calcium chloride of equivalent ratio 0.05-0.25, Yttrium chloride of 0.01-0.08 or Yttrium nitric acid of 0.01-0.08 is added and mixed into above mentioned mixed compound. 12N conc. hydrgen chloric acid of 0.1-0.6 mole per mole of alkoxide is added, mixed with mixture for 10-30minutes. The whole mixture is heated at 30-90 deg.C with the heat elevation ratio below 30 deg.C per minute, spun with the speed of 500-8000 rpm and heat-treated at 700-1500 deg.C to make stabilized zirconia staple fiber.

Description

Manufacturing method of stabilized zirconia short fiber

1 is a reference diagram of a spinning device for producing fibers by spinning a mixed solution according to the present invention.

Figure 2 is a tissue photograph of zirconia fibers produced according to the present invention.

The present invention relates to a method for producing stabilizing zirconia short fibers used as a fire insulation. Zirconia has a high melting point of about 2680 and a low thermal conductivity eh, so it can be used as a fire-resistant insulation material, but the phase transition from tetragonal to monoclinic near 1170 ℃ In this case, use has been limited due to the volume expansion of 3-5%. Therefore, when Y ₂ O ₃ , CaO, MgO, etc. are added to zirconia to stabilize the structure by cubic discharge, the volume change due to phase transition can be removed, and thus it can be used as an excellent refractory material in oxidation and reduction atmospheres. In general, fibrous insulation has light weight and low thermal conductivity, and has many advantages such as high thermal efficiency. Therefore, efforts have been made to fiberize zirconia, but due to the high melting point of zirconia itself, it is more chemical than fiber manufacturing by melting method. Efforts have been made to make fibers by the method.

Currently commercially available zirconia fibers use zirconium nitrate, zirconium acerate and zirconium chloride. Soak organic fibers in this solution, dry them, heat them at a temperature of 700-1500 ℃ to remove organic matters. Prepared polycrystalline fibers. This method has a large pupil and fiber destruction problem due to the diverging passage of the combustion gas generated during the combustion of the organic fiber, the fiber produced by this method can be used only in a limited range. In addition, another method is to add a binder to the solution to increase the viscosity of the solution, and then put it in a spinning device and spin or inject it through a nozzle having a small hole. There is a big advantage to densify.

Since the present invention reacts sensitively to trace amounts of water and forms a precipitate immediately, it is particularly difficult to produce a fiber of less than 10 mm in diameter, so zirconia alkoxide (Zirconium Alkoxide), which has not been used as a raw material for zirconia fiber, has been As a main raw material is to produce a stable zirconia short fibers by having a viscosity that is suitable for making the fiber without generating a precipitate, as described in detail as follows. In other words, the present invention adds 0.3-1.5 acetylacetone in the equivalence ratio to the zirconium alkoxide, and mixes one species in the group consisting of 0.05-0.25 calcium chloride, 0.01-0.08 yttrium chloride and 0.01-0.08 yttrium nitrate. Select and add to the mixed solution, heat the final mixed solution to 30-90 ° C. and spin the heated mixed solution at a rate of 500-8000 r · pm; And it relates to a method for producing stabilized zirconia fibers for heat-treating the fiber produced by spinning at 700-1500 ℃.

The acetylacetone is a component added to control the instability and rapid reactivity of zirconium alkoxide (zirconium n-propoxide, n-butoxide), it is preferable to limit to 0.3-1.5 equivalent ratio The reason is that if the amount of acetylacetone is small or large, a precipitate can be formed in the solution to obtain a clear and uniform solution.

In the case of calcium chloride, it is preferable to limit the amount of yttrium chloride and yttrium nitrate to the equivalent ratio of 0.05-0.25, respectively. As a result of volume expansion due to phase change, stabilization zirconia cannot be formed, and when it is added in excess, it is not suitable for making a fiber using alkoxide because of the large amount of water required to dissolve the substance in alcohol or attached to the crystal water. to be.

Calcium chloride, yttrium chloride and yttrium nitrate are dissolved in ethyl alcohol and then mixed with the zirconium alkoxide, which is preferably mixed for about 10-30 minutes, and when the amount of alcohol is small, calcium chloride is uniformly dispersed in the alkoxide. It is preferable to use an alcohol of about 0.5-1.0 times the volume of the zirconium alcohol side, because it is difficult to make, and a large amount of alcohol is a waste of time and alcohol in the evaporation process.

The calcium chloride, yttrium chloride and yttrium nitrate do not require water when it contains crystal water, but when it does not contain crystal water, it is added and dissolved in ethyl alcohol with a predetermined amount of water corresponding to the crystal water. It is preferable to homogeneously disperse calcium chloride or the like by adding 0.1-0.6 mole per 1 mole of alkoxide to 12 N hydrochloric acid in the added solution of calcium chloride, yttrium nitrate or yttrium chloride and mixing for about 10-30 minutes.

In addition, the heating step is performed to solve this problem when the mixed solution containing calcium, yttrium nitrate and yttrium chloride is aged at room temperature, so that the mixed calcium chloride absorbs moisture in the atmosphere and does not form a homogeneous mixture. As the water absorption is less than 30 ℃, homogeneous mixing is not made, and above 90 ℃ 30-90 ℃ is preferable because there is a risk of explosion of alcohol.

When the viscosity of the mixed solution heated as described above reaches about 0.3-4N sec / m 2, the fiber is put into a rotating body having a spinneret having a diameter of 1-0.1 mm in FIG. 1 to rotate the rotating body to produce fibers. If the rotation speed is 500r.pm or less, the mixed solution cannot come out through the nozzle or very thick fibers are made. If the rotation speed is 8000r.pm or more, the fibers are stuck together before the fibers are hardened so that the desired diameter 500-8000r.pm is preferred because it is thicker.

In addition, the fiber prepared as described above still contains a lot of volatile organic substances, it is preferable to heat treatment at 700-1500 ℃ to remove it and to produce a polycrystalline zirconia fiber, because the reason is below 700 ℃ Even if organic matter is removed, crystal growth does not occur to a desired size, and it is uneconomical at 1500 ° C or higher. On the other hand, the heat treatment time is shorter at higher temperatures and longer at lower temperatures, so it is preferable to select a suitable temperature, and the heating rate is preferably 30 ° C. or less. If the heating rate is faster than the above speed, the fiber may be broken during the heat treatment.

Hereinafter, the present invention will be described in detail through examples.

Example 1

Acetyl acetone was added and mixed in 1.0 equivalent ratio of zirconia alkoxide, and then 0.2 equivalent ratio of calcium chloride was dissolved in alcohol. The mixture was added to the mixed solution, mixed and heated to 80 DEG C. when the solution reached 1 N sec / m 2, 4000r. After spinning at a rate of pm, and then quenched immediately by heating to 1500 ℃ to perform an X-ray diffraction analysis experiment. In addition, the zirconium alkoxide was stabilized with 1.0 equivalent ratio of acetylacetone so that ZrO ₂ was 92% by weight, and then 8% by weight of Y ₂ O ₃ Y (NO) ₃ was dissolved in alcohol and added and mixed to the stabilized solution. X-ray diffraction analysis was carried out by heating to a temperature of 80 ℃ to rotate at a speed of 3,500 using the centrifugal spinnery of FIG. .

According to the X-ray diffraction analysis of the two kinds of fibers, it was found that the fibers produced by the present invention had zirconia having a stable cubic crystal structure.

On the other hand, a tissue photograph of the former fiber is shown in FIG. 2A and a tissue photograph of the latter fiber is shown in FIG. 2B.

Claims (3)

0.3-1.5 acetylacetone is added and mixed to the zirconium alkoxide in an equivalent ratio; Selecting one kind from the group consisting of 0.05-0.25 calcium chloride, 0.01-0.08 sodium chloride and 0.01-0.08 yttrium nitrate in an equivalent ratio to add and mix the mixed solution and heat the mixed solution to 30-90 ° C; Spinning the heated mixed solution at a rate of 500-8000 r.p.m; And a method for producing stabilizing zirconia short fibers, which is prepared by heat-treating the fibers prepared by spinning at 700-1500 ° C. The method for preparing stabilizing zirconia short fibers according to claim 1, wherein the hydrochloric acid having a concentration of 12N is added to the mixed solution for 10-30 minutes by adding 0.1-0.6 mole per mole of alkoxide before heating. The method for producing stabilized zirconia short fibers according to claim 1 or 2, wherein the heating is performed at a heating rate of 30 ° C / min or less to a heat treatment temperature.

Images