Yttria transparent ceramic and preparation method and application thereof

Abstract

The present invention relates to a yttria transparent ceramic and its preparation method and application. The chemical composition of the yttria transparent ceramic is Y2O3+x at. % MO3, wherein M=W or / and Mo, and 0

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of transparent ceramic preparation, and particularly relates to a yttrium oxide transparent ceramic and a preparation method and application thereof. BACKGROUND

[0002] The yttrium oxide transparent ceramic has the advantages of high theoretical transmittance, wide theoretical transmittance interval (0.2-8 μm), low infrared emissivity, easy doping of rare earth luminescent ions, and stable physical and chemical properties, and thus has unique advantages in the aspects of laser ceramic matrix and infrared window of missiles and high-speed aircraft. The development and research of the yttrium oxide transparent ceramic material with high transmittance have important scientific significance and practical application value for promoting the development of laser and infrared technologies. However, due to the characteristics of high melting point, difficult sintering and difficult elimination of residual pores of yttrium oxide, the current transmittance level is still low (the reported transmittance is mostly less than 70% at 400 nm), and there is still a certain gap with the theoretical transmittance. It is necessary to find a suitable sintering aid to prepare the yttrium oxide ceramic with high transmittance to meet the application requirements of the yttrium oxide transparent ceramic.

[0003] At present, the high-priced single-component sintering aids of the yttrium oxide transparent ceramic include La2O3, ZrO2 and TiO2. In 2011, Zhang Bin et al. reported that the best component of the vacuum-sintered La2O3-doped Y2O3 transparent ceramic is (Y 0.90 La 0.10 )2O3, and the maximum transmittance is greater than 80%, but the holding time of vacuum sintering is as long as 40-50 hours. In 2010, Jin, Lingling et al. reported the vacuum-sintered ZrO2-doped Y2O3 transparent ceramic, but the best doping concentration of ZrO2 is relatively high (3-5 at.%). In 2019, Li, Xiaokai et al. reported the vacuum-sintered TiO2-doped yttrium oxide transparent ceramic combined with hot isostatic pressing sintering, but the manufacturing cost of the hot isostatic pressing process is relatively high. SUMMARY

[0004] In view of the above technical problems, the application aims to provide a new sintering aid, a relatively inexpensive vacuum sintering method, and a yttrium oxide transparent ceramic with high optical quality in the case of a very small amount of sintering aid.

[0005] In a first aspect, the application provides a yttrium oxide transparent ceramic, and the chemical composition of the yttrium oxide transparent ceramic is Y2O3+x at.% MO3, wherein M=W or / and Mo, and 0

[0006] When M=W, x is preferably 0.025-0.3, and more preferably 0.075;

[0007] When M = Mo, x is preferably 0.025-0.2, more preferably 0.025.

[0008] Preferably, the transmittance of the transparent ceramic with a chemical composition of Y2O3+x at. % WO3 and a thickness of 1 mm reaches 80-82% at 1100 nm and 76-78% at 400 nm; the transmittance of the transparent ceramic with a chemical composition of Y2O3+x at. % MoO3 and a thickness of 1 mm reaches 69-70% at 1100 nm and 65-67% at 600 nm.

[0009] In a second aspect, the present application provides a preparation method of the yttria transparent ceramic, comprising the following steps:

[0010] The raw material powders Y source, W source and / or Mo source are weighed and mixed according to the chemical composition of the yttria transparent ceramic, and then sequentially subjected to drying, first sieving, heat treatment and second sieving to obtain the tungsten and / or molybdenum doped yttria transparent ceramic powder; the tungsten and / or molybdenum doped yttria transparent ceramic powder is formed into a green body, which is sintered and annealed to obtain the yttria transparent ceramic.

[0011] Preferably, the Y source is at least one of yttrium nitrate, yttrium oxide and yttrium chloride, the W source is at least one of tungsten nitrate, tungsten trioxide and tungsten acetate, and the Mo source is at least one of molybdenum nitrate, molybdenum trioxide and molybdenum acetate.

[0012] Preferably, the first sieving has a mesh size of 80-200 meshes, preferably two times of 120-200 mesh sieving;

[0013] The second sieving has a mesh size of 160-200 meshes, preferably two times of 160-200 mesh sieving; more preferably, the particle size of the mixed powder after the second sieving is controlled to be 50-100 μm.

[0014] Preferably, the heat treatment has a temperature of 800-1000 °C and a holding time of 2-6 hours.

[0015] Preferably, the green body is formed by dry pressing or / and cold isostatic pressing, preferably by dry pressing followed by cold isostatic pressing; wherein the dry pressing has a pressure of 7.5-20 MPa, preferably 10 MPa, and a holding time of 30-60 seconds; the cold isostatic pressing has a pressure of 200-300 MPa and a holding time of 2-5 minutes.

[0016] Preferably, the sintering is performed by pre-sintering followed by vacuum pressureless sintering; wherein the pre-sintering has a temperature of 1000-1300 °C and a time of 3-5 hours; the vacuum pressureless sintering has a temperature of 1780-1860 °C and a vacuum degree of 1 x 10-3 ~ 9 x 10 -3 Pa, the sintering time is 8-12 hours.

[0017] Preferably, the annealing temperature is 1200-1400℃, and the holding time is 3-5 hours; preferably, the holding time is 5 hours at 1400℃.

[0018] In a third aspect, the present application provides a use of the yttria transparent ceramic in an infrared window or a solid laser substrate material.

[0019] Advantages

[0020] The tungsten oxide and / or molybdenum oxide provided by the present application can effectively improve the transmittance of the yttria ceramic as two new sintering aids for the yttria transparent ceramic, and the preparation process of the present application is simple, easy to operate and produce; the transmittance of the yttria transparent ceramic with the chemical composition Y2O3+x at.%WO3 (thickness 1mm) at 1100nm can reach 80-82%, and the transmittance at 400nm can reach 76-78%; the transmittance of the yttria transparent ceramic with the chemical composition Y2O3+x at.%MoO3 (thickness 1mm) at 1100nm can reach 69-70%, and the transmittance at 600nm can reach 65-67%, and a small amount of tungsten and / or molybdenum doping can effectively improve the transmittance level of the yttria ceramic. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 The transmittance curves and ceramic physical pictures of the undoped Y2O3 transparent ceramic material prepared for Comparative Example 1 and the tungsten-doped yttria transparent ceramic material prepared for Examples 1-4 after double-side polishing to 1mm;

[0022] Figure 2 The transmittance curves and ceramic physical pictures of the undoped Y2O3 transparent ceramic material prepared for Comparative Example 1 and the molybdenum-doped yttria transparent ceramic material prepared for Examples 5-7 and Comparative Example 2 after double-side polishing to 1mm. DETAILED DESCRIPTION

[0023] The present application is further illustrated by the following examples, which should not be construed as limiting the present application.

[0024] Firstly, the present application provides a high-transmittance yttria transparent ceramic. The chemical composition of the yttria transparent ceramic is Y2O3+x at.%MO3, wherein M=W or / and Mo, and 0<x<0.5. With the increase of the tungsten or molybdenum addition amount, the light transmittance of the yttria transparent ceramic appears a trend of first increasing and then decreasing.

[0025] In some embodiments, when M = W, according to the binary phase diagram of WO3-Y2O3, a solid solution is formed when the doping amount is less than 1%, thus x can be controlled preferably at 0.025-0.3, more preferably at 0.075.

[0026] In some embodiments, when M = Mo, according to the binary phase diagram of MoO3-Y2O3, a solid solution is formed when the doping amount is less than 0.5%, thus x can be controlled preferably at 0.025-0.2, more preferably at 0.025.

[0027] That is, the transparent ceramic of Y2O3+x at.% WO3 is composed of yttria 1 mol and tungsten oxide 0.00075 mol in the optimal molar ratio; the transparent ceramic of Y2O3+x at.% MoO3 is composed of yttria 1 mol and molybdenum oxide 0.00025 mol in the optimal molar ratio.

[0028] The yttria transparent ceramic provided by the present application has excellent visible light and near-infrared transmittance. In some embodiments, the transmittance of the transparent ceramic with a chemical composition of Y2O3+x at.% WO3 and a thickness of 1 mm can reach 80-82% at 1100 nm and 76-78% at 400 nm; the transmittance of the transparent ceramic with a chemical composition of Y2O3+x at.% MoO3 and a thickness of 1 mm can reach 69-70% at 1100 nm and 65-67% at 600 nm.

[0029] In some embodiments, the yttria transparent ceramic has a density of 99.5%-99.9%.

[0030] Hereinafter, the preparation method of the yttria transparent ceramic provided by the present application is exemplarily described, which can include the following steps.

[0031] (1) Preparation of yttria transparent ceramic powder. The raw material powders Y source, W source and / or Mo source are weighed and mixed according to the chemical composition (molar ratio) of the yttria transparent ceramic, and then sequentially subjected to drying, first sieving, heat treatment, and second sieving to obtain the tungsten or / and molybdenum doped yttria transparent ceramic powder.

[0032] In some embodiments, the Y source can be at least one of yttrium nitrate, yttrium oxide and yttrium chloride; the W source can be at least one of tungsten nitrate, tungsten trioxide and tungsten acetate; and the Mo source can be at least one of molybdenum nitrate, molybdenum trioxide and molybdenum acetate.

[0033] In some embodiments, the mixing method can be ball milling; wherein the rotation speed of the ball milling can be 240-300 rpm, the ball milling time can be 24-30 hours, the milling ball can be zirconium ball, the ball milling medium can be anhydrous ethanol, the mass ratio of the raw material powder, the milling ball and the ball milling medium can be 1-1.5:3-5:0.8-1.5, preferably 1:4:0.8.

[0034] In some embodiments, the drying condition can be drying in an oven at 50-70℃ for 24-36 hours.

[0035] In some embodiments, the first sieving can be 80-200 mesh, which aims to disperse the powder after drying, preferably sieving twice through 120-200 mesh, which aims to obtain fluffy raw material powder.

[0036] The heat treatment can remove the organic impurities in the nylon brush during sieving. In some embodiments, the heat treatment temperature can be 800-1000℃, and the holding time can be 2-6 hours.

[0037] In some embodiments, the second sieving can be 160-200 mesh, preferably sieving twice through a mesh sieve; more preferably, the particle size of the mixed powder after the second sieving is controlled to be 50-100 μm.

[0038] (2) Preparation of yttria transparent ceramic. The tungsten and / or molybdenum doped yttria transparent ceramic powder is formed into a green body, sintered and annealed to obtain the yttria transparent ceramic.

[0039] In some embodiments, the forming method of the green body can be dry pressing or / and cold isostatic pressing, preferably dry pressing followed by cold isostatic pressing. The dry pressing pressure can be 7.5-20 MPa, preferably 10 MPa, and the holding time can be 30-60 seconds; the cold isostatic pressing pressure can be 200-300 MPa, and the holding time can be 2-5 minutes.

[0040] In some embodiments, the sintering method can be pre-sintering followed by vacuum pressureless sintering. The pre-sintering temperature can be 1000-1300℃, and the time can be 3-5 hours, which aims to improve the density and strength of the ceramic, and at the same time, Y source, W source and Mo source decompose and oxidize to form oxides; the vacuum pressureless sintering temperature can be 1780-1860℃, the vacuum degree can be 1x10 -3 ~9x10 -3 Pa, and the sintering time can be 8-12 hours.

[0041] In some embodiments, the annealing temperature can be 1200-1400℃, and the holding time can be 3-5 hours; preferably, the holding time is 5 hours at 1400℃, which aims to remove oxygen vacancies of the ceramic caused by vacuum sintering, and to improve the transmittance of the ceramic.

[0042] The transmittance of the tungsten and / or molybdenum doped yttrium oxide transparent ceramic prepared by the preparation method is good, a high transmittance level can be obtained under a relatively low doping concentration, and the sintered density is high, which can be used in the fields of infrared window or solid laser substrate material.

[0043] The following examples are further listed to illustrate the present application in detail. It should also be understood that the following examples are only used to further illustrate the present application, and cannot be understood as limiting the protection scope of the present application. Some non-essential improvements and adjustments made by those skilled in the art according to the above content of the present application all belong to the protection scope of the present application. The following examples are only one example in the appropriate range, i.e., those skilled in the art can select within the appropriate range according to the description herein, and are not limited to the specific values of the following examples.

[0044] Example 1

[0045] (1) Preparation of yttrium oxide transparent ceramic powder. The raw material powders yttrium nitrate and tungsten oxide were weighed, and the appropriate amount of anhydrous ethanol was added according to the composition ratio (molar ratio) of Y2O3+0.05at.%WO3 (i.e., the addition amount of tungsten oxide is 0.05at.%). The mass ratio of the above raw material powders to anhydrous ethanol was controlled to be 1:0.8. Then, the mixture of the above powders and anhydrous ethanol was placed in a planetary ball mill, and ball milling was carried out at 240 revolutions / minute for 24 hours. The slurry after ball milling was dried in an oven at 55℃ for 24 hours. The dried powder was sieved through a 120 mesh screen twice, and then the sieved powder was heat treated at 800℃ for 2 hours. The heat treated powder was sieved again through a 200 mesh screen twice to obtain tungsten doped yttrium oxide transparent ceramic powder with a particle size of 50-100μm and uniformity.

[0046] (2) Preparation of yttrium oxide transparent ceramic. The tungsten doped yttrium oxide transparent ceramic green body was obtained by using a dry pressing process of 20MPa with 60 seconds of pressure holding combined with a cold isostatic pressing process of 200MPa with 3 minutes of pressure holding. The formed tungsten doped yttrium oxide transparent ceramic green body was pre-sintered in a high temperature furnace at 1300℃ for 3 hours. Then, the pre-sintered sample was sintered in a vacuum furnace with a vacuum degree of 5×10 -3 Pa and a temperature of 1830℃ for 10 hours. The tungsten doped yttrium oxide transparent ceramic sample after vacuum pressureless sintering was placed in air and held at 1400℃ for 5 hours to obtain Y2O3+0.05at.%WO3 transparent ceramic material.

[0047] The transparent ceramic material prepared in Example 1 has a transmittance of 32.2% at 1100 nm and a transmittance of 29.7% at 400 nm.

[0048] Example 2

[0049] The preparation process in Example 2 is similar to that in Example 1, and the main difference is that in step (1), x = 0.075, i.e., the addition amount of tungsten oxide is 0.075 at.%.

[0050] The transparent ceramic material prepared in Example 2 has a transmittance of 81.7% at 1100 nm and a transmittance of 77.1% at 400 nm.

[0051] Example 3

[0052] The preparation process in Example 3 is similar to that in Example 1, and the main difference is that in step (1), x = 0.1, i.e., the addition amount of tungsten oxide is 0.1 at.%.

[0053] The transparent ceramic material prepared in Example 3 has a transmittance of 77.5% at 1100 nm and a transmittance of 22.7% at 400 nm.

[0054] Example 4

[0055] The preparation process in Example 4 is similar to that in Example 1, and the main difference is that in step (1), x = 0.25, i.e., the addition amount of tungsten oxide is 0.25 at.%.

[0056] The transparent ceramic material prepared in Example 4 has a transmittance of 8.5% at 1100 nm and a transmittance of 0.15% at 400 nm.

[0057] Example 5

[0058] The preparation process in Example 5 is similar to that in Example 1, and the main difference is that in step (1), tungsten oxide is replaced by molybdenum oxide, and x = 0.025, i.e., the addition amount of molybdenum oxide is 0.025 at.%.

[0059] The transparent ceramic material prepared in Example 5 has a transmittance of 69.9% at 1100 nm and a transmittance of 66.8% at 600 nm.

[0060] Example 6

[0061] The preparation process in this embodiment 6 refers to embodiment 1, the main difference is that in step (1), tungsten oxide is replaced by molybdenum oxide, x = 0.05, that is, the addition amount of molybdenum oxide is 0.05 at. %.

[0062] It can be known by the spectrometer test that the transmittance of the transparent ceramic material with a thickness of 1 mm prepared in this embodiment 6 is 69.7% at 1100 nm and 60.5% at 600 nm.

[0063] Embodiment 7

[0064] The preparation process in this embodiment 7 refers to embodiment 1, the main difference is that in step (1), tungsten oxide is replaced by molybdenum oxide, x = 0.1, that is, the addition amount of molybdenum oxide is 0.1 at. %.

[0065] It can be known by the spectrometer test that the transmittance of the transparent ceramic material with a thickness of 1 mm prepared in this embodiment 7 is 9.6% at 1100 nm and 6.6% at 600 nm.

[0066] Comparative example 1

[0067] The preparation process in this comparative example 1 refers to embodiment 1, the main difference is that in step (1), x = 0, that is, only yttrium nitrate is used as the raw material powder. Finally, a doped Y2O3 transparent ceramic material is prepared.

[0068] Comparative example 2

[0069] The preparation process in this comparative example 2 refers to embodiment 1, the main difference is that in step (1), tungsten oxide is replaced by molybdenum oxide, x = 0.25, that is, the addition amount of molybdenum oxide is 0.25 at. %.

[0070] It can be known by the spectrometer test that the transmittance of the transparent ceramic material with a thickness of 1 mm prepared in this comparative example 2 is 0.7% at 1100 nm and 0.6% at 600 nm.

[0071] Figure 1 The transmittance curves and ceramic physical maps of the undoped Y2O3 transparent ceramic material prepared in comparative example 1 and the tungsten-doped yttrium oxide transparent ceramic materials prepared in embodiments 1-4 are polished to 1mm. From Figure 1It can be seen that when the tungsten addition level is 0 at.%, the sample's transmittance at 1100 nm is 3.3%. As the tungsten doping concentration increases, the sample's transmittance first increases and then decreases. When the tungsten addition level reaches 0.075 at.%, the ceramic's transmittance reaches its maximum value, reaching 81.7% at 1100 nm and 77.1% at 400 nm. Therefore, compared with Comparative Example 1, the transmittance of the ceramic material at 1100 nm is significantly improved after doping with a small amount of tungsten oxide in Examples 1-4.

[0072] Figure 2 The transmittance curve and ceramic image of the undoped Y2O3 transparent ceramic material prepared in Comparative Example 1 and the molybdenum-doped yttrium oxide transparent ceramic material prepared in Examples 5-7 and Comparative Example 2 after double-sided polishing to 1mm. Figure 2 It can be seen that when the molybdenum addition level is 0 at.%, the sample's transmittance is 3.3% at 1100nm. As the molybdenum doping concentration increases, the sample's transmittance first increases and then decreases. When the molybdenum addition level reaches 0.025 at.%, the ceramic's transmittance reaches its maximum, reaching 69.9% at 1100nm and 66.8% at 600nm. Therefore, compared with Comparative Example 1, the transmittance of the ceramics in Examples 5-7 is significantly improved after doping with a small amount of molybdenum oxide.

[0073] Although the present invention has been described in detail through the above preferred embodiments, it should be understood that the above description is not intended to limit the present invention. After reading the above description, various modifications and substitutions of the present invention will become apparent to those skilled in the art. Therefore, the scope of protection of the present invention should be defined by the appended claims.

Claims

1. A yttrium oxide transparent ceramic, characterized in that: The chemical composition of the yttrium oxide transparent ceramic is Y2O3+x at.%MO3, wherein M=W or / and Mo, and 0<x<0.5; The yttrium oxide transparent ceramic is obtained by sintering and annealing a green body; wherein: the sintering method is pre-sintering first and then vacuum pressureless sintering, the pre-sintering temperature is 1000-1300°C, the pre-sintering time is 3-5 hours, the vacuum pressureless sintering temperature is 1780-1860°C, and the vacuum degree is 1×10 -3 ~9×10 -3 Pa, the sintering time is 8 to 12 hours; the annealing temperature is 1200 to 1400° C., and the holding time is 3 to 5 hours.

2. The yttrium oxide transparent ceramic according to claim 1, wherein When M = W, x is 0.025~0.

3.

3. The yttrium oxide transparent ceramic according to claim 1, wherein When M = W, x is 0.

075.

4. The yttrium oxide transparent ceramic according to claim 1, wherein When M = Mo, x is 0.025~0.

2.

5. The yttrium oxide transparent ceramic according to claim 1, wherein When M =Mo, x is 0.

025.

6. The yttrium oxide transparent ceramic according to claim 1, characterized in that The annealing step is to keep the temperature at 1400° C. for 5 hours.

7. The yttrium oxide transparent ceramic according to claim 1, wherein The transmittance of transparent ceramics with a chemical composition of Y2O3+x at.% WO3 and a thickness of 1 mm reaches 80-82% at 1100nm, and the transmittance at 400nm reaches 76-78%; the transmittance of transparent ceramics with a chemical composition of Y2O3+x at.% MoO3 and a thickness of 1 mm reaches 69-70% at 1100nm, and the transmittance at 600nm reaches 65-67%.

8. A method for preparing the yttrium oxide transparent ceramic according to claim 1, characterized in that: The preparation method comprises the following steps: The raw material powders of Y source, W source and / or Mo source are weighed and mixed according to the chemical composition of yttrium oxide transparent ceramic, and then dried, screened for the first time, heat treated, and screened for the second time in sequence to obtain tungsten and / or molybdenum doped yttrium oxide transparent ceramic powder; The tungsten and / or molybdenum doped yttrium oxide transparent ceramic powder is formed into a green body, and the green body is sintered and annealed to obtain the yttrium oxide transparent ceramic.

9. The preparation method according to claim 8, characterized in that The Y source is at least one of yttrium nitrate, yttrium oxide, and yttrium chloride; the W source is at least one of tungsten nitrate, tungsten trioxide, and tungsten acetate; and the Mo source is at least one of molybdenum nitrate, molybdenum trioxide, and molybdenum acetate.

10. The preparation method according to claim 8, characterized in that The mesh size of the first screening is 80 to 200 meshes; The mesh number of the second screening is 160-200.

11. The preparation method according to claim 8, characterized in that The first screening is performed twice through a 120-200 mesh sieve, and the second screening is performed twice through a 160-200 mesh sieve. The particle size of the mixed powder after the second screening is controlled to be 50-100 μm.

12. The preparation method according to claim 8, characterized in that The heat treatment temperature is 800-1000° C., and the heat preservation time is 2-6 hours.

13. The preparation method according to claim 8, characterized in that The blank is formed by dry pressing and / or cold isostatic pressing; wherein the pressure of the dry pressing is 7.5-20 MPa, and the holding time is 30-60 seconds; the pressure of the cold isostatic pressing is 200-300 MPa, and the holding time is 2-5 minutes.

14. The preparation method according to claim 13, characterized in that The pressure of the dry pressing is 10 MPa.

15. Use of the yttrium oxide transparent ceramic according to claim 1 in an infrared window or a solid laser matrix material.

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