Large-size AZO target material and preparation method thereof

Abstract

The invention belongs to the technical field of target materials, and discloses a preparation method of a large-size AZO target material, which comprises the following steps: carrying out spray granulation on mixed slurry of zinc oxide and aluminum oxide to obtain mixed powder; carrying out mould pressing on the mixed powder to obtain a target blank; performing cold isostatic pressing on the target blank to obtain a green body; the isostatic cool pressing is performed in 4-6 sections, and the pressure of the latter section is 30-60 MPa higher than that of the former section; sintering the green body after degreasing and draining; the sintering process comprises the following steps: embedding a green body into zinc oxide powder, and sintering to obtain the large-size AZO target material. The length of the large-size AZO target material is greater than 500mm, the width is greater than 300mm, and the thickness is greater than 15mm; the relative density is greater than 99.8%, and the resistivity is lower than 7-4 omegacm. In an existing preparation process flow, the large-size AZO target material with the relative density larger than 99.8% and the resistivity lower than 7-4 omegacm can be obtained by changing a cold isostatic pressing mode and a sintering mode, an existing production line can be utilized, the equipment and site cost is not increased, and the industrial value is huge.

Description

Technical Field

[0001] The invention belongs to the technical field of target materials, and in particular relates to a preparation process of a zinc oxide aluminum target material. Background Art

[0002] Zinc oxide aluminum target is also called AZO target. It is mainly made of zinc oxide and doped with a small amount of aluminum oxide. It has excellent conductivity and transparency. It is widely used in the fields of electrodes and optoelectronic devices of thin-film solar cells, and plays an important role in the new energy and electronic information industries. The difficulty of preparing and using targets of different sizes varies.

[0003] CN117776709A discloses a zinc oxide aluminum target material and a preparation method thereof, wherein aluminum oxide powder, a first dispersant, and water are mixed to form a slurry and then ground to obtain a first slurry; the first slurry, zinc oxide powder, and a second dispersant are mixed to form a slurry and then ground to obtain a second slurry; the second slurry is sprayed and granulated to obtain a granular material with a bulk density of 0.8-1 g / cm 3 The powder is molded and cold isostatically pressed to obtain a zinc oxide aluminum target embryo; the zinc oxide aluminum target embryo is sintered to obtain a zinc oxide aluminum target material. The preparation method can obtain a zinc oxide aluminum target material with a relative density greater than 98% and an electrical conductivity greater than 327μs / cm. However, when a large-sized AZO target material is prepared by this preparation method, a target material with a large relative density and a low resistivity cannot be obtained, and the field is also faced with the challenge of further increasing the relative density of large-sized AZO targets and reducing their resistivity. Summary of the invention

[0004] In view of the problems existing in the prior art, the purpose of the present invention is to provide a method for preparing a large-sized AZO target. The large-sized AZO target described in the present invention refers to an AZO target with a length greater than 500 mm, a width greater than 300 mm, and a thickness greater than 15 mm.

[0005] To achieve the above objectives, the present invention provides the following specific technical solutions.

[0006] A method for preparing a large-size AZO target, comprising: The mixed slurry of zinc oxide and aluminum oxide is sprayed and granulated to obtain a mixed powder; The mixed powder is molded to obtain a target blank; The target blank is subjected to cold isostatic pressing to obtain a green blank; the cold isostatic pressing is performed in 4-6 stages, and during the pressurization process, the pressure of the latter stage is 30-60 MPa greater than the pressure of the former stage; After degreasing and draining, the green body is sintered to obtain a large-sized AZO target. The sintering process includes: burying the green body in zinc oxide powder for sintering.

[0007] In a further preferred embodiment, the mass ratio of zinc oxide to aluminum oxide in the mixed slurry of zinc oxide and aluminum oxide is 99-98:1-2.

[0008] In a further preferred embodiment, the mixed slurry of zinc oxide and aluminum oxide is obtained by mixing zinc oxide slurry and aluminum oxide slurry.

[0009] Furthermore, the zinc oxide slurry, the aluminum oxide slurry and the binder are sand-milled to obtain a mixed slurry of zinc oxide and aluminum oxide.

[0010] Furthermore, the binder is at least one of polyvinyl alcohol, carboxymethyl cellulose, polyacrylamide, polyacrylic acid salt, and polyethylene glycol. Further preferably, the amount of the binder is 1-5% of the mass of the mixed slurry of zinc oxide and aluminum oxide.

[0011] Furthermore, the aluminum oxide powder, the first dispersant and water are mixed to form a slurry and ground to obtain an aluminum oxide slurry; the zinc oxide powder, the second dispersant and water are mixed to form a slurry and ground to obtain a zinc oxide slurry.

[0012] Furthermore, the first dispersant and the second dispersant are independently selected from one or more of polyvinyl pyrrolidone, sodium dodecylbenzene sulfonate, and sodium hexadecylbenzene sulfonate.

[0013] Furthermore, the amount of the first dispersant used is 1-5% of the mass of the aluminum oxide slurry; and the amount of the second dispersant used is 10-15% of the mass of the zinc oxide slurry.

[0014] In a further preferred embodiment, the spray granulation is carried out by a spray drying tower, the outlet air temperature of the spray drying tower is 130-200° C., and the atomizer frequency is 40-50 Hz.

[0015] In a further preferred embodiment, the bulk density of the mixed powder is 1.55-1.7 g / cm 3 .

[0016] In a further preferred embodiment, the molding pressure is 25-30 MPa.

[0017] In a further preferred embodiment, the cold isostatic pressing is carried out in 5 stages, the pressure of the first stage is 30-50Mpa, and the holding time is 3-6min; the pressure of the second stage is 60-90Mpa, and the holding time is 2-6min; the pressure of the third stage is 100-130Mpa, and the holding time is 1-3min; the pressure of the fourth stage is 140-160Mpa, and the holding time is 1-3min; the pressure of the fifth stage is 170~200Mpa, and the holding time is 10~15min.

[0018] In a further preferred embodiment, degreasing and drainage are carried out in a degreasing furnace, the heating rate is 1-4°C / min, the degreasing temperature is 400-500°C, and the holding time is 5-10h.

[0019] In a further preferred embodiment, the green body is buried in zinc oxide powder, and the thickness of the zinc oxide powder around the green body is 5-10 mm.

[0020] In a further preferred embodiment, the sintering temperature is 1400-1550° C., and the sintering holding time is 5-10 h.

[0021] Based on the same inventive concept, the present invention provides a large-size AZO target material, wherein the length of the large-size AZO target material is greater than 500 mm, the width is greater than 300 mm, the thickness is greater than 15 mm, the relative density is greater than 99.8%, and the resistivity is less than 7 -4 Ωcm.

[0022] Compared with the prior art, the above one or more technical solutions of the present invention can achieve at least one of the following beneficial effects: The preparation method of the AZO target provided by the present invention is suitable for the preparation of large-size AZO target materials with a length greater than 500 mm, a width greater than 300 mm, and a thickness greater than 15 mm, and has great industrial value.

[0023] In the existing preparation process, by changing the cold isostatic pressing method and the sintering method, a relative density greater than 99.8% and a resistivity less than 7 -4 The large-size AZO target of Ωcm can utilize the existing production line without increasing the equipment and site costs.

[0024] The preparation method provided by the invention is simple and reliable. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a photograph of the target material obtained in Example 1. DETAILED DESCRIPTION

[0026] In order to facilitate the understanding of the present invention, the present invention will be described more comprehensively and meticulously below in conjunction with the accompanying drawings and preferred embodiments of the present invention, but the protection scope of the present invention is not limited to the following specific embodiments.

[0027] Unless otherwise defined, all the professional terms used below have the same meanings as those generally understood by those skilled in the art. The professional terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention.

[0028] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods.

[0029] Example 1 Step 1: Weigh zinc oxide powder and aluminum oxide powder respectively according to the mass ratio of zinc oxide to aluminum oxide of 98:2 for later use.

[0030] Step 2: Add a certain amount of pure water and polyvinyl pyrrolidone dispersant into the dispersion tank, add the alumina powder weighed in step 1 into the dispersion tank for pre-dispersion, the dispersion time is 30 minutes, the dispersion speed is 180 rpm, and the amount of polyvinyl pyrrolidone accounts for 5% of the total mass of the material.

[0031] Step 3: The slurry obtained in step 2 was pumped into a sand mill by a pneumatic diaphragm pump for grinding for 6 hours at a grinding speed of 900 r / min to obtain alumina slurry.

[0032] Step 4: Add a certain amount of pure water and polyvinyl pyrrolidone dispersant into the dispersion tank, add the zinc oxide powder weighed in step 1 into the dispersion tank for pre-dispersion, the dispersion time is 40 minutes, the dispersion speed is 200 rpm, and the amount of polyvinyl pyrrolidone accounts for 15% of the total mass of the material.

[0033] Step 5: The slurry obtained in steps 3 and 4 is pumped into a sand mill using a pneumatic diaphragm pump and ground for 6 hours at a grinding speed of 800 r / min, and 1.8% polyvinyl alcohol of the mass of the slurry obtained in steps 3 and 4 is added to obtain a zinc oxide aluminum mixed slurry.

[0034] Step 6: The mixed slurry obtained in step 5 is fed into a spray drying tower for spray granulation, and then mixed and sieved to obtain a zinc oxide aluminum mixed powder. The air outlet temperature is 65°C, and the atomizer frequency is 70Hz. The bulk density of the zinc oxide aluminum mixed powder is 1.7g / cm 3 .

[0035] Step 7: The mixed powder obtained in step 6 is molded at a pressure of 30 MPa to obtain a large-sized initial target blank, and then cold isostatically pressed to obtain a zinc oxide aluminum target blank. The process parameters of the cold isostatic pressing are: 30 MPa pressure maintenance for 3 minutes, 60 MPa pressure maintenance for 2 minutes, 100 MPa pressure maintenance for 1 minute, 140 MPa pressure maintenance for 3 minutes, and 180 MPa pressure maintenance for 15 minutes in the pressurization and pressure relief stages.

[0036] Step 8: Place the zinc oxide aluminum target embryo into a degreasing furnace for degreasing and drainage. The heating rate of the degreasing furnace is 1°C / min, the degreasing temperature is 500°C, and the insulation time is 5h.

[0037] Step 9: Spread zinc oxide powder at the bottom of the crucible to a height of 6 mm, and put the target embryo obtained in step 8 in. Then sprinkle zinc oxide powder around the target embryo so that the target material is buried in the zinc oxide powder. The thickness of the powder around the target embryo is 6 mm. Sintering is performed. The sintering process is: heating rate of 2°C / min, heating to 1550°C, keeping warm for 15 hours, and then cooling to obtain AZO target material, such as Figure 1 As shown, it can be seen that the obtained AZO target has less white skin on the surface.

[0038] Comparative Example 1 The difference between Comparative Example 1 and Example 1 is that step 7 is different. Specifically: Step 7: The mixed powder obtained in step 6 is molded at a pressure of 30 MPa to obtain a large-sized initial target blank, and then cold isostatically pressed to obtain a zinc oxide aluminum target blank. The process parameters of the cold isostatic pressing are: pressurizing to 180 MPa and maintaining the pressure for 15 minutes, unloading the pressure, and no staged pressure maintenance. The target material sintered and cracked.

[0039] Comparative Example 2 The difference between Comparative Example 2 and Example 1 is that step 7 is different. Specifically: Step 7: The mixed powder obtained in step 6 is molded at a pressure of 30 MPa to obtain a large-sized initial target blank, and then cold isostatically pressed to obtain a zinc oxide aluminum target blank. In the pressure increase and pressure release stages, the pressure is maintained at 90 MPa for 1 minute and at 180 MPa for 15 minutes.

[0040] Comparative Example 3 The difference between Comparative Example 3 and Example 1 is that step 9 is different, specifically, no burial is performed.

[0041] Step 9: Place the target embryo obtained in step 8 in a crucible and sinter it. The sintering process is as follows: heating rate is 2°C / min, heating to 1550°C, keeping the temperature for 15 hours, and then cooling. The target material obtained has a white skin layer of about 4 mm on the upper and lower sides.

[0042] Comparative Example 4 The only difference between Comparative Example 4 and Comparative Example 3 is that the sintering temperature is 1400° C. The target material obtained has a white skin layer of about 3 mm on the upper and lower sides.

[0043] Example 2 Step 1: Weigh zinc oxide powder and aluminum oxide powder respectively according to the mass ratio of zinc oxide to aluminum oxide of 98:2 for later use.

[0044] Step 2: Add a certain amount of pure water and sodium dodecylbenzene sulfonate dispersant into the dispersion tank, add the alumina powder weighed in step 1 into the dispersion tank for pre-dispersion, the dispersion time is 30 minutes, the dispersion speed is 250rpm, and the amount of sodium dodecylbenzene sulfonate accounts for 3% of the total mass of the material.

[0045] Step 3: The slurry obtained in step 2 was pumped into a sand mill by a pneumatic diaphragm pump for grinding for 5 hours at a grinding speed of 1000 r / min to obtain alumina slurry.

[0046] Step 4: Add a certain amount of pure water and sodium hexadecylbenzenesulfonate dispersant into the dispersion tank, add the zinc oxide powder weighed in step 1 into the dispersion tank for pre-dispersion, the dispersion time is 30 minutes, the dispersion speed is 300 rpm, and the amount of sodium hexadecylbenzenesulfonate accounts for 12% of the total mass of the material.

[0047] Step 5: The slurry obtained in steps 3 and 4 is pumped into a sand mill with a pneumatic diaphragm pump and ground for 6 hours at a grinding speed of 800 r / min, and 5% polyacrylamide of the mass of the slurry obtained in steps 3 and 4 is added to obtain a zinc oxide aluminum mixed slurry.

[0048] Step 6: The mixed slurry obtained in step 5 is fed into a spray drying tower for spray granulation, and then mixed and sieved to obtain zinc oxide aluminum mixed powder. The air outlet temperature is 130°C and the atomizer frequency is 40Hz. The bulk density of the zinc oxide aluminum mixed powder is 1.62g / cm 3 .

[0049] Step 7: The mixed powder obtained in step 6 is molded at a pressure of 30 MPa to obtain a large-sized initial target blank, and then cold isostatically pressed to obtain a zinc oxide aluminum target blank. The process parameters of the cold isostatic pressing are: 40 MPa pressure maintenance for 5 minutes, 70 MPa pressure maintenance for 2 minutes, 120 MPa pressure maintenance for 2 minutes, 150 MPa pressure maintenance for 2 minutes, and 200 MPa pressure maintenance for 10 minutes in the pressurization and pressure relief stages.

[0050] Step 8: Place the zinc oxide aluminum target embryo into a degreasing furnace for degreasing and drainage. The heating rate of the degreasing furnace is 3°C / min, the degreasing temperature is 450°C, and the insulation time is 8h.

[0051] Step 9: Spread zinc oxide powder at the bottom of the crucible to a height of 8 mm, and put the target embryo obtained in step 8 in, and then sprinkle zinc oxide powder around the target embryo so that the target material is buried in the zinc oxide powder, and the thickness of the powder around the target embryo is 8 mm. Sintering is performed, and the sintering process is: heating rate of 5℃ / min, heating to 1400℃, keeping warm for 15h, and then cooling to obtain AZO target material.

[0052] Example 3 Step 1: Weigh zinc oxide powder and aluminum oxide powder respectively according to the mass ratio of zinc oxide to aluminum oxide of 99:1 for later use.

[0053] Step 2: Add a certain amount of pure water and sodium dodecylbenzene sulfonate dispersant into the dispersion tank, add the alumina powder weighed in step 1 into the dispersion tank for pre-dispersion, the dispersion time is 30 minutes, the dispersion speed is 300 rpm, and the amount of polyvinyl pyrrolidone accounts for 1% of the total mass of the material.

[0054] Step 3: The slurry obtained in step 2 was pumped into a sand mill by a pneumatic diaphragm pump for grinding for 5 hours at a grinding speed of 1000 r / min to obtain alumina slurry.

[0055] Step 4: Add a certain amount of pure water and sodium hexadecylbenzenesulfonate dispersant into the dispersion tank, add the zinc oxide powder weighed in step 1 into the dispersion tank for pre-dispersion, the dispersion time is 30 minutes, the dispersion speed is 300 rpm, and the amount of sodium hexadecylbenzenesulfonate accounts for 10% of the total mass of the material.

[0056] Step 5: The slurry obtained in steps 3 and 4 is pumped into a sand mill with a pneumatic diaphragm pump and ground for 6 hours at a grinding speed of 800 r / min, and 1% carboxymethyl cellulose of the mass of the slurry obtained in steps 3 and 4 is added to obtain a zinc oxide aluminum mixed slurry.

[0057] Step 6: The mixed slurry obtained in step 5 is fed into a spray drying tower for spray granulation, and then mixed and sieved to obtain zinc oxide aluminum mixed powder. The air outlet temperature is 200°C and the atomizer frequency is 50Hz. The bulk density of the zinc oxide aluminum mixed powder is 1.58g / cm 3 .

[0058] Step 7: The mixed powder obtained in step 6 is molded at a pressure of 30 MPa to obtain a large-sized initial target blank, and then cold isostatically pressed to obtain a zinc oxide aluminum target blank. The process parameters of the cold isostatic pressing are: 50 MPa pressure maintenance for 3 minutes, 90 MPa pressure maintenance for 2 minutes, 120 MPa pressure maintenance for 2 minutes, 150 MPa pressure maintenance for 2 minutes, and 180 MPa pressure maintenance for 10 minutes in the pressurization and pressure relief stages.

[0059] Step 8: Place the zinc oxide aluminum target embryo into a degreasing furnace for degreasing and drainage. The heating rate of the degreasing furnace is 4°C / min, the degreasing temperature is 400°C, and the insulation time is 10h.

[0060] Step 9: Spread zinc oxide powder at the bottom of the crucible to a height of 10 mm, and put the target embryo obtained in step 8 in, and then sprinkle zinc oxide powder around the target embryo so that the target material is buried in the zinc oxide powder, and the thickness of the powder around the target embryo is 10 mm. Sintering is performed, and the sintering process is: heating rate of 2 ° C / min, heating to 1500 ° C, keeping warm for 6 hours, and then cooling to obtain AZO target material.

[0061] The relative density, resistivity, warpage and white skin thickness of AZO target were tested in the following ways.

[0062] (1) Relative density: Archimedes drainage method.

[0063] (2) Resistivity: four-probe method.

[0064] (3) Warpage: measured with a feeler gauge.

[0065] (4) White cortex thickness: measured with a vernier caliper.

[0066] The results are shown in Table 1.

[0067] Table 1 Obviously, the present invention optimizes the cold isostatic pressing and sintering process of the target blank to obtain a large-sized AZO target material with high relative density, low resistivity, less surface white skin and small warping. When the cold isostatic pressing and sintering methods are changed, the target material obtained has defects such as cracking, high resistivity and more white skin.

[0068] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing a large-size AZO target, characterized in that: include: The mixed slurry of zinc oxide and aluminum oxide is sprayed and granulated to obtain a mixed powder; The mixed powder is molded to obtain a target blank; The target blank is subjected to cold isostatic pressing to obtain a green blank; the cold isostatic pressing is performed in 4 to 6 stages, and the pressure of the latter stage is 30 to 60 MPa greater than the pressure of the former stage; After degreasing and draining, the green body is sintered; the sintering process includes: burying the green body in zinc oxide powder for sintering to obtain a large-sized AZO target.

2. The method for preparing a large-size AZO target according to claim 1, characterized in that: The mass ratio of zinc oxide to aluminum oxide in the mixed slurry of zinc oxide and aluminum oxide is 99-98:1-2.

3. The method for preparing a large-size AZO target according to claim 1 or 2, characterized in that: The mixed slurry of zinc oxide and aluminum oxide is obtained by mixing zinc oxide slurry and aluminum oxide slurry; Mixing aluminum oxide powder, a first dispersant, and water to prepare a slurry and grinding to obtain an aluminum oxide slurry; The zinc oxide powder, the second dispersant and water are mixed to prepare a slurry and then ground to obtain a zinc oxide slurry.

4. The method for preparing a large-size AZO target according to claim 3, characterized in that: The first dispersant and the second dispersant are independently selected from one or more of polyvinyl pyrrolidone, sodium dodecylbenzene sulfonate, and sodium hexadecylbenzene sulfonate; the amount of the first dispersant is 1-5% of the mass of the alumina slurry; the amount of the second dispersant is 10-15% of the mass of the zinc oxide slurry.

5. The method for preparing a large-size AZO target according to claim 3, characterized in that: A binder is added when mixing zinc oxide slurry and aluminum oxide slurry; the binder is at least one of polyvinyl alcohol, carboxymethyl cellulose, polyacrylamide, polyacrylic acid salt, and polyethylene glycol; the amount of the binder is 1-5% of the mass of the mixed slurry of zinc oxide and aluminum oxide.

6. The method for preparing a large-size AZO target according to claim 1, characterized in that: The molding pressure is 25-30Mpa.

7. The method for preparing a large-size AZO target according to claim 1, characterized in that: The cold isostatic pressing is carried out in 5 stages, the pressure of the first stage is 30-50 MPa, and the holding time is 3-6 min; the pressure of the second stage is 60-90 MPa, and the holding time is 2-6 min; the pressure of the third stage is 100-130 MPa, and the holding time is 1-3 min; the pressure of the fourth stage is 140-160 MPa, and the holding time is 1-3 min; the pressure of the fifth stage is 170~200 MPa, and the holding time is 10~15 min.

8. The method for preparing a large-size AZO target according to claim 1, characterized in that: The green body is buried in zinc oxide powder, and the thickness of the zinc oxide powder around the green body is 5-10 mm.

9. The method for preparing a large-size AZO target according to claim 1 or 8, characterized in that: The sintering temperature is 1400-1550° C., and the sintering holding time is 5-10 hours.

10. A large-size AZO target, characterized in that: The large-size AZO target has a length greater than 500 mm, a width greater than 300 mm, and a thickness greater than 15 mm; a relative density greater than 99.8%, and a resistivity less than 7 -4 Ωcm.

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