阅读说明：本技术 无机盐与高温烧结协同诱导下氧化锆晶须的制备方法 (Preparation method of zirconia whisker under synergistic induction of inorganic salt and high-temperature sintering ) 是由 王玉 白宇 李智 郑全生 王士峰 于 2021-07-30 设计创作，主要内容包括：无机盐与高温烧结协同诱导下氧化锆晶须的制备方法,将氧氯化锆、磷酸盐和氟盐混合均匀,然后在800-1000℃下烧结5-15h,得到固体粉体；将固体粉体进行超声分散,清洗、抽滤,得到具有一定长径比的氧化锆晶须溶液；将具有一定长径比的氧化锆晶须溶液干燥,得到氧化锆晶须。本发明中通过添加氟盐与磷酸盐,且高温烧结协同诱导制得氧化锆晶须,该方法工艺简单、易于合成、生产过程污染较小,适宜批量制备。氧化锆晶须生长过程为固-液-固的能量传输过程,工艺简单、易于合成并且成本低。基于晶须弥散分布于复合涂层未熔颗粒区的特征,利用本发明的氧化锆晶须能够获得高强度、高韧性的热障涂层。(The preparation method of the zirconium oxide whisker under the synergic induction of inorganic salt and high-temperature sintering comprises the steps of uniformly mixing zirconium oxychloride, phosphate and villiaumite, and then sintering at the temperature of 800-1000 ℃ for 5-15h to obtain solid powder; carrying out ultrasonic dispersion, cleaning and suction filtration on the solid powder to obtain a zirconium oxide whisker solution with a certain length-diameter ratio; and drying the zirconium oxide whisker solution with a certain length-diameter ratio to obtain the zirconium oxide whisker. According to the method, the zirconium oxide whisker is prepared by adding villiaumite and phosphate and performing high-temperature sintering synergistic induction, and the method is simple in process, easy to synthesize, less in pollution in the production process and suitable for batch preparation. The growth process of the zirconium oxide whisker is a solid-liquid-solid energy transmission process, and has simple process, easy synthesis and low cost. Based on the characteristic that the crystal whiskers are dispersedly distributed in the unmelted particle area of the composite coating, the zirconium oxide crystal whiskers can be used for obtaining the thermal barrier coating with high strength and high toughness.)

1. The preparation method of the zirconium oxide whisker under the synergetic induction of inorganic salt and high-temperature sintering is characterized in that zirconium oxychloride, phosphate and villiaumite are uniformly mixed and then sintered for 5-15h at the temperature of 800-1000 ℃ to obtain solid powder; carrying out ultrasonic dispersion, cleaning and suction filtration on the solid powder to obtain a zirconium oxide whisker solution with a certain length-diameter ratio; and drying the zirconium oxide whisker solution with a certain length-diameter ratio to obtain the zirconium oxide whisker.

2. The method for preparing zirconium oxide whiskers through synergic induction of inorganic salt and high-temperature sintering as claimed in claim 1, wherein the phosphate is trisodium phosphate.

3. The method for preparing zirconium oxide whiskers through synergic induction of inorganic salt and high-temperature sintering as claimed in claim 1, wherein the fluorine salt is sodium fluoride.

4. The method for preparing zirconium oxide whiskers through synergic induction of inorganic salt and high-temperature sintering as claimed in claim 1, wherein the mass ratio of zirconium oxychloride, phosphate and villiaumite is 5 (5-7) to (1-3).

5. The method for preparing zirconium oxide whiskers through synergic induction of inorganic salt and high-temperature sintering according to claim 1, characterized in that the average aspect ratio of the zirconium oxide whiskers is 10-40.

6. The method for preparing zirconium oxide whiskers through synergic induction of inorganic salt and high-temperature sintering as claimed in claim 1 or 5, characterized in that the diameter of the zirconium oxide whiskers is 50-300 nm.

7. The method for preparing zirconia whiskers under synergic induction of inorganic salt and high-temperature sintering as claimed in claim 1, wherein the temperature is raised from room temperature to 800-1000 ℃ at a temperature-raising rate of 1-5 ℃/min.

8. The method for preparing zirconium oxide whiskers through synergic induction of inorganic salt and high-temperature sintering according to claim 1, characterized in that furnace cooling is carried out after sintering is completed.

Technical Field

The invention relates to a preparation method of zirconia whiskers under the synergistic induction of inorganic salt and high-temperature sintering, belonging to the field of composite materials.

Background

The whisker is a material with toughness and strength and excellent comprehensive performance, is a micron-nanometer short fiber grown in a high-purity single crystal mode, and is generally synthesized by manual control. It is a one-dimensional material and is called a whisker because it is similar in shape to a beard. The whisker interior is hardly defective because of the high degree of order of the atomic arrangement of the whisker upon crystallization. The interior of the whisker is almost close to the structure of perfect crystal, so that the strength of the whisker is close to the theoretical strength of valence bond between atoms of the material, and the whisker is widely used for toughening and strengthening of composite materials. The mechanism of the toughening and strengthening of the crystal whisker comprises three types: firstly, the crack deflects; secondly, the whisker is connected; and thirdly, pulling out the crystal whisker. The function of the crystal whisker consumes the fracture energy, hinders the crack propagation and achieves the toughening effect. The toughening effect of the ceramic whisker is related to the strength of the ceramic whisker, the strength is greatly related to the size, and the strength of the general whisker is reduced along with the increase of the length-diameter ratio. Therefore, the whisker with high length-diameter ratio is selected as the material of the toughening coating, and is more suitable for the severe working environment such as high-temperature heavy load of the coating. Research shows that the zirconia crystal whisker with high length-diameter ratio is added into the thermal barrier coating, can fundamentally solve the problems of overlarge brittleness and the like of the ceramic coating, can greatly improve the fracture toughness of the ceramic coating, and has wide application prospect in national defense advanced industries such as aviation turbine engines, heavy gas turbines and the like.

The preparation method of the ceramic whisker has a plurality of methods, mainly comprising a chemical vapor method, a hydrothermal method, an electrostatic spinning method and a molten salt method. The chemical vapor method is to make gaseous chemical matter inside the reactor agglomerate to grow crystal whisker in the state of low supersaturation degree of gas-solid interface through heating ionization and other modes. The chemical vapor method for preparing the crystal whisker has higher requirements on raw materials and equipment, but has the advantages of stable product quality and higher yield. The hydrothermal method includes a solvent thermochemical synthesis method, a coating method and the like. The method has the advantages that the method can synthesize metal nanowires and various inorganic and organic whiskers which are difficult to synthesize by a gas phase method, and is an important one-dimensional material preparation method. The yield of the crystal whiskers prepared by the hydrothermal method is too low, the utilization rate of powder by spray granulation and spraying processes is limited, and a large amount of powder raw materials are required to be used as experimental supports.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provides a preparation method of zirconia whiskers under the synergetic induction of inorganic salt and high-temperature sintering.

In order to achieve the above purposes, the technical scheme adopted by the invention is as follows:

the preparation method of the zirconium oxide whisker under the synergic induction of inorganic salt and high-temperature sintering comprises the steps of uniformly mixing zirconium oxychloride, phosphate and villiaumite, and then sintering at the temperature of 800-1000 ℃ for 5-15h to obtain solid powder; carrying out ultrasonic dispersion, cleaning and suction filtration on the solid powder to obtain a zirconium oxide whisker solution with a certain length-diameter ratio; and drying the zirconium oxide whisker solution with a certain length-diameter ratio to obtain the zirconium oxide whisker.

In a further development of the invention, the phosphate is trisodium phosphate.

A further improvement of the invention is that the fluoride salt is sodium fluoride.

The invention further improves that the mass ratio of the zirconium oxychloride to the phosphate to the villiaumite is 5 (5-7) to 1-3.

The invention is further improved in that the zirconia whiskers have an average aspect ratio of 10 to 40.

The invention is further improved in that the diameter of the zirconia whisker is 50-300 nm.

The invention is further improved in that the temperature is raised from room temperature to 800-1000 ℃ at a temperature raising rate of 1-5 ℃/min.

The invention is further improved in that the furnace is cooled after sintering.

Compared with the prior art, the invention has the technical effects that:

the method has the advantages of simple process, easy synthesis, less pollution in the production process and suitability for batch preparation. The growth process of the zirconium oxide whisker is solid-liquid-solid energy transmissionThe process is simple, easy to synthesize and low in cost. Based on the characteristic that the crystal whiskers are dispersedly distributed in the unmelted particle area of the composite coating, the zirconium oxide crystal whiskers can be used for obtaining the thermal barrier coating with high strength and high toughness, and compared with a nano-structure YSZ coating, the YSZ/ZrO coating₂The fracture toughness of the whisker toughness-increased ceramic composite coating is improved by about one time, and the ceramic composite coating is expected to be applied to the surfaces of hot end parts of aero-engines and the like.

Furthermore, because the phosphate has a higher melting point and is not directly melted into a liquid phase as a medium for material transmission, sodium phosphate with a melting point higher than 1100 ℃ is selected to promote the zirconium oxide to grow anisotropically, and the growth mechanism of the zirconium oxide is different from that of the traditional molten salt method.

Further, the addition of sodium fluoride lowers the complete conversion temperature of the reaction by-products by 150 ℃, and promotes the preferential growth of monoclinic phase zirconium oxide whiskers along the [100] one-dimensional direction in essence.

Furthermore, on the basis of a molten salt method, the zirconium oxide whisker with high length-diameter ratio can be prepared by virtue of sodium fluoride and high-melting-point salts under the synergistic action of high-temperature sintering, so that the toughening effect which is difficult to embody by the whisker (or nanorod) with small length-diameter ratio is realized.

Drawings

FIG. 1 is a graph of zirconia whiskers prepared at different temperatures according to an embodiment of the present invention, wherein (a) is 800 ℃; (b) at 950 ℃;

FIG. 2 is a graph of zirconia whiskers prepared under different NaF in accordance with an example of the invention, wherein (a) is 2 wt%; (b) is 3 wt%;

FIG. 3 is a TEM photograph of a zirconia whisker prepared in an example of the present invention, wherein (a) is a bright field image; (b) selective electron diffraction;

FIG. 4 is a graph of fracture toughness and Vickers indentation micrographs for coatings of the invention and comparative examples, where (a) is the fracture toughness value for both coatings; (b) is a Vickers indentation micro-topography picture of a YSZ coating, and (c) is YSZ/ZrO₂And a Vickers indentation microscopic morphology image of the coating.

Detailed Description

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

The preparation method of the zirconia crystal whisker under the synergic induction of inorganic salt and high-temperature sintering comprises the following steps:

firstly, zirconium oxychloride, trisodium phosphate and sodium fluoride in a certain proportion are weighed and uniformly mixed to obtain a precursor. The mass ratio of the zirconium oxychloride to the trisodium phosphate to the sodium fluoride is 5 (5-7) to 1-3.

And (3) preserving the heat of the precursor for 5-15h at the temperature of 800-. Wherein the heating rate in the sintering process is 1-5 ℃/min, and furnace cooling is carried out. And carrying out ultrasonic dispersion on the sintered solid powder, and then repeatedly cleaning and filtering the solid powder by using deionized water to obtain a zirconium oxide whisker solution with a certain length-diameter ratio.

Finally, drying the zirconium oxide whisker solution in an oven to obtain the zirconium oxide whisker with the length-diameter ratio of 10-40 and the diameter of 50-300 nm.

Example 1

(1) Uniformly mixing 5g of zirconium oxychloride, 5g of trisodium phosphate and 1g of sodium fluoride to obtain a precursor;

(2) heating the precursor from room temperature to 800 ℃ at the heating rate of 5 ℃/min, preserving heat for 5 hours, carrying out high-temperature sintering, and then cooling along with a furnace to obtain solid powder;

(3) carrying out ultrasonic dispersion on the sintered solid powder, and then cleaning and carrying out suction filtration by using deionized water to obtain a zirconium oxide whisker solution with a certain length-diameter ratio; wherein, the diameter of the zirconium oxide whisker is 50-300nm, and the average length-diameter ratio is 20.

(4) And finally, drying the zirconium oxide whisker solution in an oven to obtain the zirconium oxide whisker.

The experimental data for examples 2-14 are shown in Table 1, as well as for examples 1-14.

TABLE 1 data for examples 1-14 of zirconia whiskers

As shown in fig. 1 (a) and (b), when the sintering temperature of the zirconia whisker is 800 ℃, the NaF content is 1 wt%, the zirconia whisker of example 1 is comparatively short; when the sintering temperature was increased to 950 ℃, zirconia whiskers of example 3 were obtained, in which the whiskers had an average diameter of 200nm and an average aspect ratio of 40.

In fig. 2, (a) and (b) compare the effect of different amounts of NaF on whisker morphology. As can be seen from (a) and (b) in fig. 2, the addition ratio of NaF also affects the formation of whiskers. When the addition proportion of NaF is 2 wt%, the average diameter of the crystal whisker prepared in the example 9 is 300nm, and the length-diameter ratio is 15; when NaF is added in a proportion of 3 wt%, the whiskers prepared in example 12 have an average diameter of 400nm and an aspect ratio of 10.

By further observing the prepared zirconia whiskers of example 1, TEM and SAED results are shown in fig. 3 (a) and (b), indicating that sodium fluoride promotes preferential growth of monoclinic phase zirconia whiskers along the [100] one-dimensional direction.

The zirconia whisker is doped into the YSZ coating to prepare YSZ/ZrO₂The specific microstructure and the vickers indentation microstructure of the coating, the interior of the coating are shown in (a), (b) and (c) of fig. 4. As can be seen from FIGS. 4 (a), (b) and (c), when the zirconia whiskers are located in the unfused nano-regions of the coating, the ceramic coating with the zirconia whiskers added has higher fracture toughness than the coating without whiskers, and finally YSZ/ZrO is caused due to the crack trapping effect of the unfused regions₂The coating has higher obdurability.

Example 15

(1) Uniformly mixing 5g of zirconium oxychloride, 5g of trisodium phosphate and 3g of sodium fluoride to obtain a precursor;

(2) heating the precursor from room temperature to 800 ℃ at the heating rate of 1 ℃/min, preserving heat for 5 hours, carrying out high-temperature sintering, and then cooling along with a furnace to obtain solid powder;

(3) carrying out ultrasonic dispersion on the sintered solid powder, and then cleaning and carrying out suction filtration by using deionized water to obtain a zirconium oxide whisker solution with a certain length-diameter ratio; wherein the diameter of the zirconia whisker is 50-300 nm.

(4) And finally, drying the zirconium oxide whisker solution in an oven to obtain the zirconium oxide whisker.

Example 16

(1) Uniformly mixing 5g of zirconium oxychloride, 6g of trisodium phosphate and 1g of sodium fluoride to obtain a precursor;

(2) heating the precursor from room temperature to 1000 ℃ at the heating rate of 3 ℃/min, preserving heat for 5 hours, carrying out high-temperature sintering, and then cooling along with a furnace to obtain solid powder;

(3) carrying out ultrasonic dispersion on the sintered solid powder, and then cleaning and carrying out suction filtration by using deionized water to obtain a zirconium oxide whisker solution with a certain length-diameter ratio; wherein the diameter of the zirconia whisker is 50-300 nm.

(4) And finally, drying the zirconium oxide whisker solution in an oven to obtain the zirconium oxide whisker.

Example 17

(1) Uniformly mixing 5g of zirconium oxychloride, 7g of trisodium phosphate and 2g of sodium fluoride to obtain a precursor;

(2) heating the precursor from room temperature to 900 ℃ at the heating rate of 5 ℃/min, preserving heat for 10 hours, carrying out high-temperature sintering, and then cooling along with a furnace to obtain solid powder;

(3) carrying out ultrasonic dispersion on the sintered solid powder, and then cleaning and carrying out suction filtration by using deionized water to obtain a zirconium oxide whisker solution with a certain length-diameter ratio; wherein the diameter of the zirconia whisker is 50-300 nm.

(4) And finally, drying the zirconium oxide whisker solution in an oven to obtain the zirconium oxide whisker.

The invention utilizes the synergistic effect of inorganic salt and high-temperature sintering induction to prepare the zirconia crystal whisker with high strength and toughness. The influence rule of the NaF addition proportion and the sintering temperature on the whisker growth is researched, and the optimal mass proportion of the zirconium oxychloride, the trisodium phosphate and the sodium fluoride is 5:7:1, and the optimal sintering temperature is 950 ℃. The addition of the high-melting-point sodium phosphate and the sodium fluoride can promote the anisotropic growth of the zirconium oxide, and the preferential growth of the monoclinic-phase zirconium oxide whisker along the [100] one-dimensional direction is essentially promoted. The method prepares the zirconia crystal whisker with high length-diameter ratio by the synergistic action of inorganic salt and high-temperature sintering, has the advantages of low cost, simple process, easy synthesis and the like, has less pollution in the production process, and is suitable for batch preparation. Meanwhile, the fracture toughness of the YSZ ceramic composite coating doped with the zirconia whiskers is higher than that of a coating without the zirconia whiskers, the coating has higher toughness, and the coating is expected to have wide application prospect in national defense advanced industries such as aviation turbine engines, heavy-duty gas turbines and the like.