Method for preparing needle-shaped yttrium pyrosilicate and needle-shaped yttrium pyrosilicate obtained therefrom

Abstract

The present invention relates to a method for preparing needle-shaped yttrium pyrosilicate, which comprises providing silicon source powder, yttrium source powder and binder aqueous solution respectively; ball milling and mixing silicon source powder and yttrium source powder, drying the mixed silicon source and yttrium source to obtain mixed powder, adding the binder aqueous solution to the mixed powder and grinding it evenly, and then dry pressing to obtain a blank; and placing the blank at 1400°C to 1800°C for oxidation to obtain needle-shaped yttrium pyrosilicate, wherein yttrium pyrosilicate grows directional in silica glass into a needle-shaped morphology. According to the method for preparing needle-shaped yttrium pyrosilicate of the present invention, the silicon source and the yttrium source have no fixed morphology, and SiO2 and Y2O3, Y2SiO5 or Y2Si2O7 generated after high-temperature oxidation, the final stable phase is yttrium pyrosilicate, and yttrium pyrosilicate grows directional into a needle shape. According to the method for preparing needle-shaped yttrium pyrosilicate of the present invention, the steps are simple, the blank can be fully oxidized, and the growth of needle-shaped yttrium pyrosilicate is promoted.

Description

Technical Field

[0001] The invention relates to yttrium disilicate, and more particularly to a method for preparing needle-shaped yttrium disilicate and the needle-shaped yttrium disilicate obtained thereby. Background Art

[0002] The physicochemical properties of materials are affected not only by their composition and particle size, but also by their morphology. When electrons are confined in a one-dimensional (1D) quantum wire, they have only one degree of freedom along the direction of the quantum wire, which changes the scattering effect of the electron motion, resulting in physicochemical properties of one-dimensional materials that are different from those in other dimensions. Yttrium silicate has excellent properties such as mechanical properties, thermal properties, and high-temperature stability. It is one of the most promising rare earth silicates and is widely used in environmental barrier coatings and fine ceramics. Yttrium silicate with a one-dimensional (1D) structure not only has its unique mechanical, thermal, and corrosion properties, but also has excellent one-dimensional structural material properties. Its design and synthesis are receiving increasing attention.

[0003] There are many methods for preparing yttrium disilicate powder, and the morphology of the prepared yttrium disilicate powder is difficult to control. The yttrium disilicate prepared by the prior art is in the form of particles, and there is a lack of reports on needle-shaped yttrium disilicate. Summary of the invention

[0004] In order to solve the problem that the morphology of yttrium disilicate powder is difficult to control in the prior art, the present invention provides a method for preparing needle-shaped yttrium disilicate and the needle-shaped yttrium disilicate obtained thereby.

[0005] According to one aspect of the present invention, a method for preparing needle-shaped yttrium diosilicate is provided, which comprises the following steps: S1, respectively providing a silicon source powder, a yttrium source powder and a binder aqueous solution; S2, ball-milling the mixed silicon source powder and the yttrium source powder, drying the mixed silicon source and yttrium source to obtain a mixed powder, adding the binder aqueous solution to the mixed powder, grinding it evenly, and then dry-pressing it to obtain a green body; and S3, oxidizing the green body at 1400°C~1800°C to obtain needle-shaped yttrium diosilicate, wherein the yttrium diosilicate undergoes directional growth in the silica glass into a needle-shaped morphology.

[0006] In a preferred embodiment, the silicon source is nano-sized SiC powder or micro-sized SiC powder.

[0007] In a preferred embodiment, the yttrium source includes at least one of yttrium disilicate powder, yttrium silicate powder, yttrium oxide powder, yttrium silicide powder, or yttrium silicate mineral powder.

[0008] In a preferred embodiment, the binder includes at least one of polyvinyl alcohol, polytetrafluoroethylene, carboxymethyl cellulose, polyolefin, and polyurethane.

[0009] In a preferred embodiment, in step S2, the silicon source and the yttrium source are mixed by ball milling in anhydrous ethanol.

[0010] In a preferred embodiment, in step S2, the drying temperature is 20°C to 70°C, and the drying time is 6h to 12h.

[0011] In a preferred embodiment, in step S2, the content of the binder accounts for 1% to 15% of the mass of the mixed powder.

[0012] In a preferred embodiment, in step S2, the molding pressure is 0.5 MPa to 20 MPa.

[0013] In a preferred embodiment, in step S3, SiC powder is oxidized to generate SiO2, and Y2O3 and SiO2 generate yttrium disilicate.

[0014] According to another aspect of the present invention, there is provided needle-shaped yttrium disilicate obtained according to the above preparation method.

[0015] According to the preparation method of needle-shaped yttrium pyrosilicate of the present invention, the silicon source and the yttrium source do not have a fixed morphology, and SiO2 and Y2O3, Y2SiO5 or Y2Si2O7 generated after high-temperature oxidation, the final stable phase is yttrium pyrosilicate, and yttrium pyrosilicate undergoes directional growth into a needle shape. According to the preparation method of needle-shaped yttrium pyrosilicate of the present invention, the steps are simple, the blank can be fully oxidized, and the growth of needle-shaped yttrium pyrosilicate is promoted. In short, according to the preparation method of needle-shaped yttrium pyrosilicate of the present invention, after the irregular yttrium source powder is mixed with SiC powder, the granular yttrium pyrosilicate will grow back into needle-shaped yttrium pyrosilicate after high-temperature oxidation. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a morphology diagram of the SiC-Y2Si2O7 body according to Example 1 of the present invention.

[0017] Figure 2 This is a SEM morphology image of the needle-shaped yttrium pyrosilicate morphology obtained after the SiC-Y2Si2O7 body according to Example 1 of the present invention is oxidized at 1400°C.

[0018] Figure 3 This is an EDS elemental analysis diagram of the needle-shaped yttrium pyrosilicate morphology obtained after the SiC-Y2Si2O7 blank according to Example 1 of the present invention is oxidized at 1400°C.

[0019] Figure 4 This is a morphology diagram of the SiC-Y2O3 body according to Example 2 of the present invention.

[0020] Figure 5This is a SEM morphology image of the needle-shaped yttrium pyrosilicate morphology obtained after the SiC-Y2O3 body of Example 2 of the present invention was oxidized at 1400°C.

[0021] Figure 6 This is a SEM morphology image of the yttrium disilicate obtained after the SiC-Y2Si2O7 body of Comparative Example 1 of the present invention was oxidized at 1200°C. DETAILED DESCRIPTION

[0022] The preferred embodiments of the present invention are given below in conjunction with the accompanying drawings and described in detail.

[0023] The preparation method of needle-shaped yttrium pyrosilicate according to the present invention first comprises respectively providing silicon source powder, yttrium source powder and binder aqueous solution. In a preferred embodiment, the silicon source is carbon (Si) powder or silicon carbide (SiC) powder. In a preferred embodiment, the silicon source is nano-scale SiC powder or micron-scale SiC powder. In a preferred embodiment, the particle size of SiC powder is about 1 μm. In a preferred embodiment, the yttrium source comprises yttrium pyrosilicate (Y2Si2O7) powder, yttrium silicate (Y2SiO5) powder, yttrium oxide (Y2O3) powder, yttrium silicide (YSi2) powder, or yttrium silicate mineral (Y2SiO5) powder. 4.67 In a preferred embodiment, the binder comprises at least one of polyvinyl alcohol (PVA), polytetrafluoroethylene (PTFE), carboxymethyl cellulose (CMC), polyolefins (PE, PP, etc.), and polyurethane (polyurethane). In a preferred embodiment, the binder is an aqueous solution with a concentration of 1wt% to 20wt%. In a preferred embodiment, the binder is an aqueous solution with a concentration of 5wt%.

[0024] The preparation method of needle-shaped yttrium pyrosilicate according to the present invention then includes ball milling to mix silicon source powder and yttrium source powder. In a preferred embodiment, the grinding balls used for ball milling are SiC grinding balls. It should be understood that the component of SiC after oxidation is SiO2, and the selection of this material can prevent contamination. In a preferred embodiment, the mass ratio of silicon source to yttrium source is 10:1. In a preferred embodiment, the silicon source and yttrium source are ball milled and mixed in an organic solvent. In a preferred embodiment, the organic solvent is anhydrous ethanol. In a preferred embodiment, the ball milling time is 2h~72h. In a preferred embodiment, the ball milling time is 24h.

[0025] The preparation method of needle-shaped yttrium pyrosilicate according to the present invention then includes drying the mixed silicon source and yttrium source to obtain a mixed powder. In a preferred embodiment, the drying temperature is 20°C to 70°C. In a preferred embodiment, the drying temperature is 60°C. In a preferred embodiment, the drying time is 6h to 12h. In a preferred embodiment, the drying time is 10h.

[0026] The preparation method of needle-shaped yttrium pyrosilicate according to the present invention then includes adding a binder aqueous solution to the mixed powder, grinding it evenly, and then dry pressing it to obtain a green body. In a preferred embodiment, the content of the binder accounts for 1% to 15% of the mass of the mixed powder. In a preferred embodiment, the content of the binder accounts for 5% of the mass of the mixed powder. In a preferred embodiment, after grinding evenly, the mixed powder is passed through a 60-mesh screen. In a preferred embodiment, the molding pressure is 0.5MPa to 20MPa. In a preferred embodiment, the green body is a SiC-Y2Si2O7 green body or a SiC-Y2O3 green body.

[0027] The preparation method of needle-shaped yttrium pyrosilicate according to the present invention finally comprises placing the blank at 1400°C to 1800°C for oxidation and recrystallization to obtain needle-shaped yttrium pyrosilicate. In a preferred embodiment, the oxidation temperature is 1400°C. In a preferred embodiment, the oxidation time is 50h. In a preferred embodiment, SiC powder is oxidized to generate SiO2, and Y2O3 and SiO2 generate yttrium pyrosilicate.

[0028] Example 1

[0029] Silicon carbide powder (SiC, about 1 μm) and yttrium disilicate powder (Y2Si2O7) were ball-milled in anhydrous ethanol. The mass ratio of silicon carbide powder to yttrium disilicate powder was 10:1. The ball-milling time was 24 h. After drying at 60 ° C for 10 h, 5% of the total powder mass of PVA binder was added to the mixed powder. The concentration of the aqueous solution was 5wt%. After being fully ground, the green body was obtained by dry pressing. The molding pressure was 20 MPa. The surface morphology of the SiC-Y2Si2O7 green body after molding is as follows: Figure 1 As shown, the white particles are yttrium pyrosilicate and the gray particles are silicon carbide. The blank is then oxidized at 1400°C for 50 hours to obtain needle-shaped yttrium pyrosilicate. The SEM morphology is shown in Figure 2 As shown, its EDS component characterization diagram is as follows Figure 3 As shown, a large number of needle-like crystals appeared on the surface of the oxide layer, and the EDS energy spectrum analysis results showed that the needle-like crystals were yttrium disilicate.

[0030] Example 2

[0031] Silicon carbide powder (SiC, about 1 μm) and yttrium oxide powder (Y2O3) were ball-milled in anhydrous ethanol. The mass ratio of silicon carbide powder to yttrium oxide powder was 10:1. The ball-milling time was 24 h. After drying at 60 ° C for 10 h, 5% of the total powder mass of PVA binder was added to the mixed powder. The concentration of the aqueous solution was 5wt%. After being fully ground, the green body was obtained by dry pressing. The molding pressure was 20 MPa. The surface morphology of the SiC-Y2O3 green body after molding is as follows: Figure 4As shown, the white particles are yttrium oxide and the gray particles are silicon carbide. The blank is then oxidized at 1400°C for 50 hours to obtain needle-shaped yttrium pyrosilicate. The SEM morphology is shown in Figure 5 As shown, needle-shaped yttrium pyrosilicate crystals exist on the surface of the oxide layer.

[0032] Comparative Example 1

[0033] Silicon carbide powder (SiC, about 1 μm) and yttrium disilicate powder (Y2Si2O7) were ball-milled in anhydrous ethanol. The mass ratio of silicon carbide powder to yttrium disilicate powder was 10:1. The ball-milling time was 24 h. After drying at 60 ° C for 10 h, 5% of the total powder mass of PVA binder was added to the mixed powder. The concentration of the aqueous solution was 5wt%. After being fully ground, the green body was obtained by dry pressing. The molding pressure was 20 MPa. The surface morphology of the SiC-Y2Si2O7 green body after molding is as follows: Figure 1 As shown in the figure, the white particles are yttrium disilicate and the gray particles are silicon carbide. After the green body is oxidized at 1200°C for 50h, it is still granular yttrium disilicate. Its SEM morphology is shown in Figure 6 shown.

[0034] The above is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention. The above embodiment of the present invention can also be modified in various ways. That is, all simple, equivalent changes and modifications made according to the claims and the description of the present invention fall within the scope of protection of the claims of the present invention. The contents not described in detail in the present invention are all conventional technical contents.

Claims

1. A method for preparing needle-shaped yttrium pyrosilicate, characterized in that: The preparation method comprises the following steps: S1, respectively providing a silicon source powder, a yttrium source powder and a binder aqueous solution, wherein the silicon source is a nano-scale SiC powder or a micro-scale SiC powder, and the yttrium source includes at least one of yttrium pyrosilicate powder, yttrium silicate powder, yttrium oxide powder, yttrium silicide powder, or yttrium silicate mineral powder; S2, ball milling the mixed silicon source powder and yttrium source powder, drying the mixed silicon source and yttrium source to obtain a mixed powder, adding a binder aqueous solution to the mixed powder, grinding it evenly, and then dry pressing it to obtain a green body; and S3, placing the blank at 1400°C-1800°C for oxidation to obtain needle-shaped yttrium pyrosilicate, wherein the yttrium pyrosilicate grows directionally in the silica glass into a needle-shaped morphology.

2. The preparation method according to claim 1, characterized in that: The binder includes at least one of polyvinyl alcohol, polytetrafluoroethylene, carboxymethyl cellulose, polyolefin and polyurethane.

3. The preparation method according to claim 1, characterized in that: In step S2, a silicon source and a yttrium source are mixed by ball milling in anhydrous ethanol.

4. The preparation method according to claim 1, characterized in that: In step S2, the drying temperature is 20°C to 70°C, and the drying time is 6h to 12h.

5. The preparation method according to claim 1, characterized in that: In step S2, the content of the binder accounts for 1% to 15% of the mass of the mixed powder.

6. The preparation method according to claim 1, characterized in that: In step S2, the molding pressure is 0.5 MPa to 20 MPa.

7. The preparation method according to claim 1, characterized in that: In step S3, SiC powder is oxidized to generate SiO2, and Y2O3 and SiO2 generate yttrium disilicate.

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