阅读说明：本技术 以硅溶胶为原料制备矩形截面的二氧化硅纤维的方法 (Method for preparing silicon dioxide fiber with rectangular cross section by taking silica sol as raw material ) 是由 王天驰 程紫文 戴生伢 于 2021-08-20 设计创作，主要内容包括：本发明公开了一种以硅溶胶为原料制备矩形截面的二氧化硅纤维的方法。所述方法先将硅溶胶滴加到平放的光滑平面上,并铺展均匀,待其光滑平面上硅溶胶自然干燥或者人工干燥后,可自然得到拥有矩形截面的无定形二氧化硅纤维；然后将获得的无定形二氧化硅纤维放入马弗炉中烧结,可得到矩形截面的二氧化硅纤维。本发明方法工艺简单,成本廉价,纤维制备过程中避免了纺丝过程,降低二氧化硅纤维制备难度,且制备出的纤维的横截面为矩形,不同于以往熟知的圆形横截面的纤维。(The invention discloses a method for preparing a silicon dioxide fiber with a rectangular cross section by taking silica sol as a raw material. Firstly, dripping silica sol on a flat smooth plane, uniformly spreading, and naturally drying or artificially drying the silica sol on the smooth plane to obtain amorphous silica fibers with rectangular sections; then, the obtained amorphous silica fiber is put into a muffle furnace to be sintered, and the silica fiber with a rectangular cross section can be obtained. The method has simple process and low cost, avoids the spinning process in the fiber preparation process, reduces the preparation difficulty of the silicon dioxide fiber, and the cross section of the prepared fiber is rectangular and is different from the conventional well-known fiber with a circular cross section.)

1. The method for preparing the silicon dioxide fiber with the rectangular cross section by taking the silica sol as the raw material is characterized by comprising the following steps:

step 1: dropwise adding silica sol onto a horizontally placed smooth plane, and uniformly spreading;

step 2: drying the silica sol to obtain amorphous silica fibers;

and step 3: the obtained amorphous silica fiber was sintered to obtain a silica fiber having a rectangular cross section.

2. The method of claim 1, wherein in step 1, the silica sol has a mass concentration of 10wt% or more.

3. The method of claim 1, wherein in step 1, the smooth surface is a hydrophilic smooth surface.

4. The method of claim 1, wherein the silica sol is dried by natural drying or artificial drying in step 2.

5. The method of claim 4, wherein the drying temperature of the artificial drying is 70 to 150 ℃.

6. The method according to claim 1, wherein in the step 3, the sintering is carried out in a muffle furnace, the sintering temperature is greater than or equal to 800 ℃, the heating rate is 2-15 ℃/min, and the holding time is 1-4 h.

Technical Field

The invention belongs to the field of silica fiber materials, and relates to a method for preparing a silica fiber with a rectangular cross section by taking silica sol as a raw material.

Background

The silicon dioxide fiber belongs to oxide ceramic fiber, has excellent thermal shock resistance, low thermal conductivity and excellent mechanical property, and is a better material for high-temperature heat preservation and high-temperature filtration. At present, the preparation methods of the silicon dioxide fiber mainly comprise a sol-gel method, a high-temperature melting method, a template method and the like. Wherein, the sol-gel method and the high-temperature melting method need spinning technology in the process of preparing the silicon dioxide fiber; the template method also requires fibrous raw materials as templates, which greatly increases the difficulty of preparing the silica fibers.

Silica sols are dispersions of nanoscale silica particles in water or a solvent, which contain a large amount of water and hydroxyl groups, which can be described as SiO₂·nH₂And O. Because the silica sol has the advantages of high temperature resistance, corrosion resistance, oxidation resistance, good chemical stability and the like, the silica sol is often used as a film forming substance in the coating and plays an important role in preparing high temperature resistant and environment-friendly inorganic coatings. However, when silica sol is used alone as a film-forming material, it is fibrous after drying due to the rigidity of the silica-oxygen bond in silica sol, and other modifiers are required to form a film.

Disclosure of Invention

The invention aims to provide a method for preparing a silica fiber with a rectangular cross section by taking silica sol as a raw material. According to the method, silica sol is used as a raw material, spinning is not needed in the process of preparing the silica fiber, and the cross section of the fiber is rectangular.

The technical scheme for realizing the purpose of the invention is as follows:

the method for preparing the silicon dioxide fiber with the rectangular cross section by taking the silica sol as the raw material comprises the following steps:

step 1: dropwise adding silica sol onto a horizontally placed smooth plane, and uniformly spreading;

step 2: after the silica sol is dried, amorphous silica fiber with a rectangular section can be naturally obtained;

and step 3: the obtained amorphous silica fiber was sintered to obtain a silica fiber having a rectangular cross section.

Furthermore, in step 1, the mass concentration of the silica sol is greater than or equal to 10 wt%.

Further, in step 1, the smooth surface is a hydrophilic smooth surface to facilitate spreading of the silica sol.

Further, in the step 2, natural drying or artificial drying is adopted for drying, and the drying temperature during artificial drying is 70-150 ℃.

Further, in the step 3, sintering is carried out in a muffle furnace, wherein the sintering temperature is more than or equal to 800 ℃, the heating rate is 2-15 ℃/min, and the heat preservation time is 1-4 h.

Compared with the prior art, the invention has the following advantages:

the invention uses silica sol as raw material, and utilizes the characteristic that the silica sol is easy to naturally present a fibrous shape after being dried to prepare the silicon dioxide fiber. The process is simple and low in cost, and compared with the traditional fiber preparation method, the cross section of the silicon dioxide fiber prepared by the method is rectangular instead of circular.

Drawings

FIG. 1 is a flow chart of the present invention for producing a silica fiber having a rectangular cross section.

FIG. 2 is a macroscopic representation of the silica fibers produced in example 1.

FIG. 3 is a SEM low and high magnification microstructure of amorphous silica fibers of example 1.

FIG. 4 is a SEM low and high magnification microstructure of silica fibers of example 1.

FIG. 5 is a SEM low and high magnification microstructure of silica fibers of example 3.

FIG. 6 is an X-ray diffraction pattern of silica fibers at different sintering temperatures.

FIG. 7 is a photomicrograph taken during the formation of fibers from the silica sol and magnified under an optical microscope.

Detailed Description

The present invention will be described in further detail with reference to the following examples and the accompanying drawings.

With reference to fig. 1, the method for preparing a silica fiber with a rectangular cross section by using silica sol as a raw material according to the present invention includes the following steps:

step 1: dropwise adding silica sol onto a horizontally placed smooth plane, and uniformly spreading;

step 2: after the silica sol is dried, amorphous silica fiber with a rectangular section can be naturally obtained;

and step 3: sintering the obtained amorphous silica fiber to obtain a silica fiber with a rectangular cross section;

and 4, step 4: sieving to obtain the silica fiber with the rectangular section in different diameter ranges.

Example 1

About 1.5g of silica sol having a concentration of 40 wt% was dropped onto the petri dish and spread uniformly. And then the culture dish is put into a drying oven to be dried for 5min at the temperature of 100 ℃, and then the culture dish is taken out, so that the amorphous silicon dioxide fiber with the rectangular cross section can be naturally obtained. And then placing the amorphous silicon dioxide fibers into a muffle furnace, heating to 800 ℃ at the speed of 3 ℃/min, preserving the temperature for 2h, and taking out the amorphous silicon dioxide fibers to obtain the silicon dioxide fibers of which the crystal forms are cristobalite. The obtained silica fiber is filtered by standard sieves with different mesh numbers, and the silica fiber with rectangular cross sections in different diameter ranges can be sieved.

Example 2

About 1.5g of silica sol having a concentration of 40 wt% was dropped onto the petri dish and spread uniformly. And then the culture dish is put into a drying oven to be dried for 5min at the temperature of 100 ℃, and then is taken out, so that the amorphous silicon dioxide fiber with the rectangular cross section can be naturally obtained.

And then putting the amorphous silicon dioxide fiber into a muffle furnace, heating to 900 ℃ at the speed of 3 ℃/min, preserving the temperature for 2h, and taking out the amorphous silicon dioxide fiber to obtain the silicon dioxide fiber with the main crystal form of cristobalite. The obtained silica fiber is filtered by standard sieves with different mesh numbers, and the silica fiber with rectangular cross sections in different diameter ranges can be sieved.

Example 3

About 1.5g of silica sol having a concentration of 40 wt% was dropped onto the petri dish and spread uniformly. And then the culture dish is put into a drying oven to be dried for 5min at the temperature of 100 ℃, and then the culture dish is taken out, so that the amorphous silicon dioxide fiber with the rectangular cross section can be naturally obtained.

And then placing the amorphous silicon dioxide fiber into a muffle furnace, heating to 1100 ℃ at the speed of 3 ℃/min, preserving the heat for 2h, and taking out the amorphous silicon dioxide fiber to obtain the silicon dioxide fiber with the crystal form of tridymite. The obtained silica fiber is filtered by standard sieves with different mesh numbers, and the silica fiber with rectangular cross sections in different diameter ranges can be sieved.

Example 4

About 1.5g of silica sol having a concentration of 40 wt% was dropped onto the petri dish and spread uniformly. And then the culture dish is put into a drying oven to be dried for 5min at the temperature of 100 ℃, and then the culture dish is taken out, so that the amorphous silicon dioxide fiber with the rectangular cross section can be naturally obtained. And then placing the amorphous silicon dioxide fiber into a muffle furnace, heating to 1500 ℃ at the speed of 3 ℃/min, preserving the heat for 2h, and taking out the amorphous silicon dioxide fiber to obtain the silicon dioxide fiber with the crystal form of tridymite. The obtained silica fiber is filtered by standard sieves with different mesh numbers, and the silica fiber with rectangular cross sections in different diameter ranges can be sieved.

FIG. 2 is a photomicrograph of the silica fibers of example 1 after sintering at 800 ℃ and sieving through an 80 mesh screen; FIG. 3 is an SEM image of amorphous silica fibers of example 1; FIG. 4 is an SEM photograph of silica fibers of example 1 after sintering at 800 ℃; FIG. 5 is an SEM photograph of silica fibers of example 3 after sintering at 1100 ℃. As can be seen from fig. 2, the silica fibers were prepared with the method in a complete morphology. It can be seen from FIGS. 3-5 that the cross-section of the silica fibers appears rectangular, and the thickness of the fibers is not the same, and is affected by the thickness of the spread silica sol. Secondly, as the sintering temperature increases, the pores inside and outside the fiber increase, and pores are left after sintering volatilization probably due to the influence of a large amount of water and hydroxyl contained in the silica sol.

FIG. 6 is an X-ray diffraction pattern of silica fibers obtained through different sintering temperatures. It can be seen from the figure that when the sintering temperature is less than 600 ℃, there is no sharp peak in the XRD pattern, and the crystalline phase of the fiber is mainly amorphous silica. When the sintering temperature reached 800 ℃ it was transformed into cristobalite, and when 900 ℃ some tridymite crystalline phases began to form. And when the sintering temperature exceeds 1100 ℃, the crystal form is completely transformed into tridymite, and the crystal form is not changed.

FIG. 7 is a macroscopic photograph taken during the process of forming a fiber from a silica sol and a photograph taken after the process of enlarging the fiber under an optical fiber mirror. As can be seen from fig. 7a, as the moisture is evaporated, the single fiber is gradually formed by the growth from the outside to the inside without breaking. In addition, it is more clearly observed from an optical microscope that the liquid surface of the silica sol is divided into stripes by cracks gradually growing from the outside to the inside, and the stripes become individual fibers after being dried.