阅读说明：本技术 一种原位合成莫来石晶须陶瓷材料的制备方法 (Preparation method for in-situ synthesis of mullite whisker ceramic material ) 是由 周毅 白伟 张成霞 赵红星 吕振新 张皓博 田玉明 王凯悦 力国民 秦梅 武雅乔 于 2021-01-12 设计创作，主要内容包括：本发明公开了一种原位合成莫来石晶须陶瓷材料的制备方法,主要包括以下步骤：将粉煤灰在高温下煅烧后,采用盐酸处理,经干燥、研磨、过40目筛；将工业芒硝与工业氢氧化铝研磨、烘干、过40目筛；将过筛后的粉煤灰、工业芒硝与工业氢氧化铝装入球磨罐中,充分球磨混合后,高温煅烧,随后随炉自然冷却到室温,得到含莫来石晶须的陶瓷材料。本发明将粉煤灰固废变废为宝、流程简单高效、节能环保,合成出的莫来石晶须具有直径20-40nm；长5-10μm,长径比125-500的显著特征,制备的陶瓷材料抗折强度高,性能好。(The invention discloses a preparation method of an in-situ synthesized mullite whisker ceramic material, which mainly comprises the following steps: calcining the fly ash at high temperature, treating with hydrochloric acid, drying, grinding, and sieving with a 40-mesh sieve; grinding industrial mirabilite and industrial aluminum hydroxide, drying and sieving by a 40-mesh sieve; and (3) loading the sieved fly ash, industrial mirabilite and industrial aluminum hydroxide into a ball milling tank, fully ball milling and mixing, calcining at high temperature, and naturally cooling to room temperature along with a furnace to obtain the ceramic material containing the mullite whiskers. The method changes the solid waste of the fly ash into valuable, has simple and efficient flow, saves energy and protects environment, and the synthesized mullite whisker has the diameter of 20-40 nm; 5-10 μm long, aspect ratio 125-500, and the prepared ceramic material has high breaking strength and good performance.)

1. The preparation method of the in-situ synthesized mullite whisker ceramic material is characterized in that fly ash, industrial aluminum hydroxide and industrial mirabilite are used as raw materials, the fly ash is treated by hydrochloric acid after being calcined at high temperature, and is mixed with the industrial aluminum hydroxide and the industrial mirabilite, and the ceramic material containing the mullite whisker is synthesized in situ by solid state sintering after being fully ball-milled and mixed.

2. The method for preparing the mullite whisker ceramic material in situ synthesis according to claim 1, wherein the mass ratio of the fly ash to the industrial mirabilite to the industrial aluminum hydroxide is 1.7-2.3: 5: 2.7-3.3.

3. The method for preparing the mullite whisker ceramic material for in-situ synthesis according to claim 2, comprising the following steps:

(1) calcining the fly ash at 600 ℃ for 1h, treating the fly ash for 1-2h by hydrochloric acid with the concentration of 15-25 mol/L, then cleaning the fly ash for 3-4 times by using clear water, drying the fly ash for 2-4 h at 90-110 ℃, and sieving the fly ash with a 40-mesh sieve after grinding;

(2) drying industrial mirabilite and industrial aluminum hydroxide at 90-110 ℃ for 2-4 h, grinding and sieving by a 40-mesh sieve;

(3) weighing the sieved fly ash, industrial mirabilite and industrial aluminum hydroxide according to the weight ratio, then loading the weighed materials into a ball milling tank, fully ball milling and mixing the materials for 4 to 6 hours, then transferring the materials into a corundum porcelain boat, calcining the materials for 2 to 3 hours in a box furnace at 900 to 1100 ℃, and then naturally cooling the materials to room temperature along with the furnace to obtain the ceramic material containing the mullite whiskers.

4. The method for preparing the mullite whisker ceramic material for in-situ synthesis according to claim 2, comprising the following steps:

(1) calcining the fly ash at 600 ℃ for 1h, treating the fly ash for 1-2h by hydrochloric acid with the concentration of 15-25 mol/L, then cleaning the fly ash for 3-4 times by using clear water, drying the fly ash for 2-4 h at 90-110 ℃, and sieving the fly ash with a 40-mesh sieve after grinding;

(2) drying industrial mirabilite and industrial aluminum hydroxide at 90-110 ℃ for 2-4 h, grinding and sieving by a 40-mesh sieve;

(3) weighing the sieved fly ash, industrial mirabilite and industrial aluminum hydroxide according to the weight ratio, then loading the weighed materials into a ball milling tank, fully ball-milling and mixing for 4-6 hours, and drying to obtain a premix;

(4) after the premixed and uniform powder is aged, pressing the powder into a strip-shaped blank body with the length multiplied by the width multiplied by the height multiplied by 5 mm multiplied by 50 mm by a tablet press;

(5) and (3) placing the strip-shaped blank on a corundum backing plate, heating to 900-1100 ℃ in a box-type furnace at the speed of 3-4 ℃/min, preserving heat for 2-3 hours, and naturally cooling to room temperature along with the furnace to obtain the ceramic material containing the mullite whisker.

5. The preparation method of the in-situ synthesized mullite whisker ceramic material as claimed in any one of claims 3 or 4, wherein the ball milling pot is a corundum ball milling pot, an agate ball milling pot or a polyurethane ball milling pot.

6. The preparation method of mullite whisker as claimed in claim 5, wherein the ball milling pot is a corundum ball milling pot, the medium ball is a corundum ball, the ball milling medium is distilled water, and the mixture is as follows: corundum balls: the mass ratio of the distilled water is 1: 2: 1.

7. the method for preparing the mullite whisker ceramic material in situ synthesis according to claim 4, wherein the preparation of the strip-shaped blank in the step (4) is as follows:

(a) adding 3-5 wt% of polyvinyl alcohol solution with the weight percentage concentration of 5-10% into the uniformly premixed powder, mixing and grinding for 15-45min by using a grinding rod, and then putting into a closed container for aging for 10-12 h;

(b) the aged powder was compressed into a bar-shaped body having a length × width × height of 5 mm × 5 mm × 50 mm by a tablet press under a pressure of 20 MPa.

8. The method for preparing the mullite whisker-containing ceramic material in situ synthesis according to claim 4, wherein the average breaking strength of the mullite whisker-containing ceramic material obtained in the step (5) is more than 50 MPa.

9. The method for preparing the mullite whisker ceramic material in situ synthesis as claimed in claim 4, wherein the mullite whisker ceramic material obtained in the step (5) mainly comprises mullite whisker phase, the diameter of the whisker is 20-40nm, the length of the whisker is 5-10 μm, and the length-diameter ratio is in the range of 125-500.

Technical Field

The invention belongs to the field of material preparation, and particularly relates to a preparation method for in-situ synthesis of a mullite whisker ceramic material.

Background

Mullite (3 Al)₂O₃·2 SiO₂) Is an aluminosilicate phase internally composed of [ AlO₄]Tetrahedron, [ SiO ]₄]Tetrahedron, and [ AlO ]₆]Octahedron connection. The structure enables the mullite to have excellent thermo-mechanical properties such as low thermal conductivity, low expansion, high strength, high temperature resistance and the like. The whisker is a fine single crystal material characterized by high length-diameter ratio, has the one-dimensional characteristics of nearly perfect defect-free inside and whisker-shaped appearance, and is endowed with strength and toughness close to theoretical values.

The mullite crystal is made into a whisker shape, so that the thermo-mechanical property of the mullite-containing ceramic material is further improved, and the mullite ceramic material is a toughening and reinforcing additive with excellent performance. Mullite whiskers have been widely advocated in the fields of metal-based, ceramic-based, polymer-based and other composite materials and high-temperature refractory materials due to the excellent thermal stability and high strength and toughness of the mullite whiskers, and various composite materials with excellent performance are successfully prepared.

The fly ash is the solid waste with the largest discharge amount in the thermal power plants in the world at present, and the discharge amount is gradually increased along with the social development, so that the sustainable development of ecological environment and the health of human beings and animals are seriously threatened, and the serious harm is brought to the human societyAnd (4) harming. However, thanks to their diagenetic character, i.e. their internal composition consisting mainly of Al₂O₃And SiO₂The composition provides the composition condition for synthesizing the mullite phase.

At present, the idea of synthesizing mullite and mullite whisker by using fly ash as a raw material is adopted. Zhangyujun et al (Shandong university, a preparation method of mullite whisker, CN 1785893A) utilize alumina sol and silica sol to obtain xerogel, then mix with industrial aluminum fluoride, and calcine at 1350 ℃ -1550 ℃ to prepare mullite whisker powder. The sol-gel method has the disadvantages that the raw materials are complex organic matters, the cost is high, and the environment is polluted after the raw materials are discharged; the process is complex, the period is long, and the requirements of simplicity and high efficiency are not met. Another method for synthesizing mullite whiskers is an inorganic calcination method. Penjinhui and the like (a method for synthesizing mullite whisker by normal pressure sintering, CN 101935877A) use industrial alumina and silicon dioxide as raw materials, aluminum fluoride and vanadium pentoxide as additives, and the mullite whisker product is obtained by wet grinding in alcohol and then sintering at 1250-1450 ℃. Although the process is obviously simplified, the method takes high-cost reagents such as aluminum fluoride and vanadium pentoxide as additives, and the sintering temperature is over 1250 ℃.

Disclosure of Invention

In order to solve the problems, the invention provides a preparation method for in-situ synthesis of a mullite whisker ceramic material.

The invention is realized by the following steps: the in-situ synthesis process of mullite whisker ceramic material includes the high temperature calcination of flyash, hydrochloric acid treatment of flyash, mixing with industrial aluminium hydroxide and industrial mirabilite, ball milling and solid sintering to synthesize mullite whisker containing ceramic material in-situ.

Further, the mass ratio of the fly ash, the industrial mirabilite to the industrial aluminum hydroxide is 1.7-2.3: 5: 2.7-3.3.

Further, the preparation method for in-situ synthesis of the mullite whisker ceramic material comprises the following steps:

(1) calcining the fly ash at 600 ℃ for 1h, treating the fly ash for 1-2h by hydrochloric acid with the concentration of 15-25 mol/L, then cleaning the fly ash for 3-4 times by using clear water, drying the fly ash for 2-4 h at 90-110 ℃, and sieving the fly ash with a 40-mesh sieve after grinding;

(2) drying industrial mirabilite and industrial aluminum hydroxide at 90-110 ℃ for 2-4 h, grinding and sieving by a 40-mesh sieve;

(3) weighing the sieved fly ash, industrial mirabilite and industrial aluminum hydroxide according to the weight ratio, then loading the weighed materials into a ball milling tank, fully ball milling and mixing the materials for 4 to 6 hours, then transferring the materials into a corundum porcelain boat, calcining the materials for 2 to 3 hours in a box furnace at 900 to 1100 ℃, and then naturally cooling the materials to room temperature along with the furnace to obtain the ceramic material containing the mullite whiskers.

Furthermore, the ball milling tank is a corundum ball milling tank, an agate ball milling tank or a polyurethane ball milling tank.

Further, the ball-milling jar is corundum ball-milling jar, and the medium ball is corundum ball, and the ball-milling medium is distilled water, mixture: corundum balls: the mass ratio of the distilled water is 1: 2: 1.

the mullite whisker ceramic material is prepared by the steps.

The mullite whisker ceramic material with a blank shape can be prepared, which comprises the following specific steps: a preparation method for in-situ synthesis of a mullite whisker ceramic material comprises the following steps:

(1) calcining the fly ash at 600 ℃ for 1h, treating the fly ash for 1-2h by hydrochloric acid with the concentration of 15-25 mol/L, then cleaning the fly ash for 3-4 times by using clear water, drying the fly ash for 2-4 h at 90-110 ℃, and sieving the fly ash with a 40-mesh sieve after grinding;

(2) drying industrial mirabilite and industrial aluminum hydroxide at 90-110 ℃ for 2-4 h, grinding and sieving by a 40-mesh sieve;

(3) weighing the sieved fly ash, industrial mirabilite and industrial aluminum hydroxide according to the weight ratio, then loading the weighed materials into a ball milling tank, fully ball-milling and mixing for 4-6 hours, and drying to obtain a premix;

(4) after the premixed and uniform powder is aged, pressing the powder into a strip-shaped blank body with the length multiplied by the width multiplied by the height multiplied by 5 mm multiplied by 50 mm by a tablet press;

(5) and (3) placing the strip-shaped blank on a corundum backing plate, heating to 900-1100 ℃ in a box-type furnace at the speed of 3-4 ℃/min, preserving heat for 2-3 hours, and naturally cooling to room temperature along with the furnace to obtain the ceramic material containing the mullite whisker.

The preparation of the strip-shaped blank in the step (4) is as follows:

(a) adding 3-5 wt% of polyvinyl alcohol solution with the weight percentage concentration of 5-10% into the uniformly premixed powder, mixing and grinding for 15-45min by using a grinding rod, and then putting into a closed container for aging for 10-12 h;

(b) the aged powder was compressed into a bar-shaped body having a length × width × height of 5 mm × 5 mm × 50 mm by a tablet press under a pressure of 20 MPa.

The ball milling process in the steps is the same as the ball milling process for preparing the powdery mullite whisker ceramic material.

The average breaking strength value of the obtained strip-shaped blank ceramic material containing mullite whiskers reaches more than 50 MPa. The obtained strip-shaped blank-shaped mullite whisker-containing ceramic material takes a whisker phase as a main component, the diameter of the whisker is 20-40nm, the length is 5-10 mu m, and the length-diameter ratio is in the range of 125-500.

The method has the beneficial effects of changing the solid waste of the fly ash into valuable, being simple and efficient in flow, saving energy and protecting environment. (1) The mullite whisker ceramic material is synthesized in situ by adopting solid waste fly ash discharged by a power plant as a main raw material, low-cost industrial aluminum hydroxide as a supplement aluminum source and low-cost industrial mirabilite as a fluxing agent through simple raw material pretreatment and a solid state sintering method. (2) The synthesized mullite whisker has the diameter of 20-40 nm; 5-10 μm long, aspect ratio 125-500. (3) The breaking strength of the prepared ceramic material is more than 55 Mpa.

Drawings

Figure 1 is the XRD pattern of the product obtained in example 1,

FIG. 2 is an SEM photograph of the product obtained in example 1.

Detailed Description

The present invention is further described in detail below with reference to specific embodiments so that those skilled in the art can practice the invention with reference to the description.

Example 1:

(1) firstly, calcining the fly ash of a power plant at 600 ℃ for 1h, treating the calcined fly ash for 1h by using hydrochloric acid with the concentration of 25 mol/L, then cleaning the fly ash for 4 times by using clean water, drying the fly ash for 4 h at 90 ℃, and sieving the fly ash with a 40-mesh sieve after grinding;

(2) drying industrial mirabilite and industrial aluminum hydroxide at 90 ℃ for 4 h, grinding and sieving by a 40-mesh sieve;

(3) mixing the dried fly ash, industrial aluminum hydroxide and industrial mirabilite according to the weight ratio of 1.7: 3.3: 5, ball-milling for 4 hours after weighing, and drying to obtain a premix; the ball milling tank in the ball milling process is a corundum ball milling tank, the medium ball in the ball milling process is a corundum ball, the ball milling medium is distilled water, and the mixture is as follows: corundum balls: the mass ratio of the distilled water is 1: 2: 1, the mixture refers to a mixture of fly ash, industrial aluminum hydroxide and industrial mirabilite;

(4) after the premixed and uniform powder is aged, pressing the powder into a strip-shaped blank body with the length multiplied by the width multiplied by the height multiplied by 5 mm multiplied by 50 mm by a tablet press;

(5) and (3) placing the strip-shaped blank on a corundum backing plate, heating to 900 ℃ in a box-type furnace at the speed of 4 ℃/min, preserving heat for 3 h, and cooling along with the furnace to obtain the mullite whisker ceramic material.

The method specifically comprises the following steps of:

(a) adding 3 wt% of polyvinyl alcohol solution with the weight percentage concentration of 5% into the uniformly premixed powder, mixing and grinding the powder for 30min by using a grinding rod, and then putting the powder into a closed container to age for 12 h;

(b) pressing the aged powder into a strip-shaped blank body with the length multiplied by the width multiplied by the height multiplied by 5 mm multiplied by 50 mm by a tablet machine under the pressure of 20 MPa;

and (5) obtaining the mullite whisker ceramic material, wherein the average breaking strength value of the mullite whisker ceramic material reaches 57.2 MPa.

The obtained ceramic material containing the mullite whiskers is subjected to X-ray diffraction, the diffraction spectrum of the ceramic material is analyzed, and a figure 1 is obtained, and as can be seen from the figure 1, the ceramic material obtained through the steps mainly contains a mullite phase and contains few impurity phases.

The obtained ceramic material containing mullite whiskers can be shown in figure 2 through a scanning electron microscope, and as can be seen from figure 2, the ceramic material obtained through the steps is mainly composed of whisker phases, the diameter of the ceramic material is 20-40nm, the length of the ceramic material is 5-10 mu m, and the length-diameter ratio of the ceramic material is in the range of 125-500.

Example 2:

(1) firstly, calcining the fly ash of a power plant at 600 ℃ for 1h, treating the calcined fly ash for 1.5h by hydrochloric acid with the concentration of 22 mol/L, then cleaning the fly ash for 4 times by using clean water, drying the fly ash for 3 h at 100 ℃, and sieving the fly ash with a 40-mesh sieve after grinding;

(2) drying industrial mirabilite and industrial aluminum hydroxide at 100 ℃ for 3 h, grinding and sieving by a 40-mesh sieve;

(3) mixing the dried fly ash, industrial aluminum hydroxide and industrial mirabilite according to the weight ratio of 2: 3: 5, ball milling for 5 hours after weighing, and drying to obtain a premix;

(4) adding 4 wt% of polyvinyl alcohol solution with the weight percentage concentration of 7% into the uniformly premixed powder, mixing and grinding for 40min by using a grinding rod, and then putting into a closed container for aging for 10 h;

(5) pressing the aged powder into a strip-shaped blank body with the length multiplied by the width multiplied by the height multiplied by 5 mm multiplied by 50 mm by a tablet machine under the pressure of 20 MPa;

(6) and (3) placing the strip-shaped blank on a corundum backing plate, heating to 1000 ℃ in a box-type furnace at the speed of 3 ℃/min, preserving heat for 2.5 h, and then cooling along with the furnace to obtain the mullite whisker ceramic material.

The ball milling tank in the ball milling process is a corundum ball milling tank, the medium ball in the ball milling process is corundum ball, and the ball milling medium is distilled water.

The average flexural strength value of the mullite whisker ceramic material obtained through the steps reaches 59.5 MPa.

The SEM picture of the mullite whisker ceramic material obtained by the above steps is similar to that of fig. 2.

Example 3:

(1) firstly, calcining the fly ash of a power plant at 600 ℃ for 1h, treating the calcined fly ash with hydrochloric acid with the concentration of 20 mol/L for 2h, then cleaning the fly ash with clean water for 3 times, drying the fly ash at 110 ℃ for 2h, and sieving the fly ash with a 40-mesh sieve after grinding;

(2) drying industrial mirabilite and industrial aluminum hydroxide at 110 ℃ for 2h, grinding and sieving by a 40-mesh sieve;

(3) mixing the dried fly ash, industrial aluminum hydroxide and industrial mirabilite according to the weight ratio of 2.3: 1.7: 5, ball milling for 6 hours after weighing, and drying to obtain a premix;

(4) adding 5 wt% of polyvinyl alcohol solution with the weight percentage concentration of 10% into the uniformly premixed powder, mixing and grinding for 45min by using a grinding rod, and then putting into a closed container for aging for 11 h;

(5) pressing the aged powder into a strip-shaped blank body with the length multiplied by the width multiplied by the height multiplied by 5 mm multiplied by 50 mm by a tablet machine under the pressure of 20 MPa;

(6) and (3) placing the strip-shaped blank on a corundum backing plate, heating to 1100 ℃ in a box-type furnace at the speed of 3 ℃/min, preserving heat for 2h, and then cooling along with the furnace to obtain the mullite whisker ceramic material.

The ball milling tank in the ball milling process is a corundum ball milling tank, the medium ball in the ball milling process is corundum ball, and the ball milling medium is distilled water.

The average flexural strength value of the mullite whisker ceramic material obtained through the steps reaches 52.8 MPa.

The SEM picture of the mullite whisker ceramic material obtained by the above steps is similar to that of fig. 2.

Example 4:

(1) firstly, calcining the fly ash of a power plant at 600 ℃ for 1h, treating the calcined fly ash for 1h by using hydrochloric acid with the concentration of 20 mol/L, then cleaning the fly ash for 4 times by using clean water, drying the fly ash for 4 h at 100 ℃, and sieving the fly ash with a 40-mesh sieve after grinding;

(2) drying industrial mirabilite and industrial aluminum hydroxide at 100 ℃ for 4 h, grinding and sieving by a 40-mesh sieve;

(3) mixing the dried fly ash, industrial aluminum hydroxide and industrial mirabilite according to the weight ratio of 2: 3: 5, then the mixture is fully ball-milled and mixed for 4 hours, then the mixture is moved into a corundum porcelain boat, the temperature is raised to 1000 ℃ at the speed of 4 ℃/min, the mixture is calcined for 3 hours at the temperature of 1000 ℃, and then the mixture is naturally cooled to room temperature along with a furnace, thus obtaining the ceramic material containing mullite whiskers.

And (3) carrying out X-ray diffraction on the obtained mullite whisker-containing ceramic material, analyzing the diffraction pattern of the mullite whisker-containing ceramic material, and obtaining a picture which is similar to that in figure 1, and an SEM picture of the obtained mullite whisker-containing ceramic material is similar to that in figure 2.

The above description is only a preferred embodiment of the present invention, and all equivalent changes or modifications of the structure, characteristics and principles described in the present invention are included in the scope of the present invention.