A high-density large-size ITO target and its preparation method

Abstract

The invention belongs to the technical field of ITO target preparation and discloses a high-density large-size ITO target and a preparation method thereof. The preparation method of the high-density large-size ITO target comprises the following steps: step 1: placing an ITO blank into a degreasing and sintering integrated furnace, heating the blank to 280-300°C at a heating rate of 100-150°C / h, and keeping the temperature for 10-25h, during which 0.1MPa dry compressed air is continuously introduced at a flow rate of 20-30L / min; step 2: after the insulation of step 1 is completed, heating the blank to 600-620°C at a heating rate of 80-110°C / h, and keeping the temperature for 8-15h, during which dry compressed air is continuously introduced at a flow rate of 20-30L / min; and step 3: after the insulation of step 2 is completed, cooling the blank to 400°C at a cooling rate of 60-100°C / h, introducing dry compressed air to make the pressure in the furnace reach 0.15-2MPa, and then keeping the pressure and temperature for 15-20h. The present invention sets a low-temperature and high-pressure heat preservation and pressure preservation process between the degreasing and sintering processes, thereby ensuring that the moisture and binder in the ITO blank are completely discharged from the interior of the target material, improving the density of the target material while avoiding the cracking of the target material.

Description

Technical Field

[0001] The present invention relates to the technical field of ITO target material preparation, and in particular to a high-density large-size ITO target material and a preparation method thereof. Background Art

[0002] ITO (indium tin oxide) is an important raw material for the preparation of ITO conductive glass. After sputtering, ITO targets can form transparent ITO conductive films on glass. Its performance is a key factor in determining the quality, production efficiency, and yield of conductive glass products. Important indicators of ITO target performance are composition, phase structure, and density. The composition of ITO targets is In2O3+SnO2, and the ratio of indium oxide to tin oxide is usually 90:10 (mass ratio). After the forming process, the ITO target blank is only a semi-finished product. The ITO target is first formed by pre-pressing to produce a high-density target blank. The target blank requires further degreasing and sintering to obtain the ITO target. Existing methods of atmospheric sintering mainly include vacuum hot pressing, atmospheric sintering, cold isostatic pressing, etc. These processes often consume a long degreasing and sintering time in order to obtain high-density targets. The sintering length of ordinary targets is generally 200-500mm or less. The ITO powder molded in the target is generally nano-level, ranging from 10-20kg during molding, with a short sintering time and a high sintering yield.

[0003] For example, D1: Chinese patent application 201210446311.1 discloses a method for preparing an ITO target material by hot pressing, which includes preparing an indium tin hydroxide precipitation solution; centrifugally separating the precipitate and liquid in the precipitation solution; washing the precipitate with water, and centrifugally separating the precipitate and water; drying and calcining the precipitate to obtain an ITO powder; adding polyvinyl alcohol to the ITO powder, and dry-pressing the ITO powder into a molded body using a mold; and placing the molded body in a hot pressing furnace to prepare the ITO target material.

[0004] The above patent application can make ITO powder reach nanoscale by controlling conditions such as the temperature and pH value of the synthetic solution, providing conditions for the preparation of high-density ITO targets by hot pressing, and can effectively prepare higher-density ITO targets.

[0005] However, as the market demand for large-sized ITO targets increases, when targets of 600mm and above in length are formed, the mass of the green billets varies from 25 to 50kg, and improper design of the sintering time and temperature will result in low target density and high energy consumption such as electricity and oxygen. The ITO targets prepared by the technical solution of the above-mentioned patent application can no longer meet the market demand for large-sized ITO targets.

[0006] Based on this, D2: Chinese patent application 201810653327.7 discloses a debinding-sintering integrated production

[0007] The method for preparing an ITO target material comprises the following steps: 1) mixing ITO powder, a dispersant and water, performing ball milling, adding a binder, and performing ultrasonic and vacuum degassing to obtain a slurry; 2) injecting the slurry into a mold, performing molding to obtain a target blank, demoulding, and drying the target blank; 3) placing the target blank on a support plate in a degreasing-sintering integrated furnace, performing programmed heating and programmed cooling to obtain the ITO target material.

[0008] In the process of target blank densification, the above patent application directly heats the target blank from the highest degreasing temperature to a higher temperature sintering, omitting the cooling, transfer and reheating process of the target blank after degreasing. The efficiency of degreasing and sintering is significantly improved, and the cracking of the target blank caused by the transfer between the degreasing furnace and the sintering furnace is eliminated, thereby improving production efficiency and facilitating the mass production of ITO targets.

[0009] Moreover, the above patent application shows in the embodiment that it can be used to produce large-sized targets with a length of 600mm, which has a very high reference value. However, after experimental production, it was found that when producing large-sized targets with a length greater than 700mm and a wall thickness greater than 18mm, the density of the target produced by the technical solution of the above patent will show a significant downward trend, and due to the large wall thickness of the target blank, the volatilization of water and other binders is hindered, resulting in cracking of the target. After analysis, the possible reasons are: due to the large size and thickness of the target, the conventional degreasing time and degreasing rate, the excessively fast heating rate will discharge the water and binder inside the target, resulting in the water vapor environment in the sintering furnace cannot be quickly discharged, thereby causing the target to crack, and the technical solution for adjusting the sintering time and sintering oxygen dosage process, resulting in insufficient insulation time and oxygen dosage for the target to react, thereby reducing the density of the target.

[0010] Therefore, it is necessary to redesign a preparation method that can produce larger-sized, high-density, and high-yield target materials, so as to meet the market demand for larger-sized target materials. Summary of the Invention

[0011] One of the purposes of the present invention is to provide a method for preparing high-density large-size ITO targets to solve the technical problem in the prior art that high-density large-size targets with a length greater than 700 mm cannot be effectively produced by integrating degreasing and sintering and adjusting the oxygen flow rate, insulation temperature and time of degreasing and sintering, so as to meet the market demand for larger-size targets.

[0012] Another object of the present invention is to provide a high-density large-size ITO target material, which has the advantages of both large size and high density and can meet the increasing demand for large-size targets in the market.

[0013] To achieve the above object, the present invention provides a method for preparing a high-density large-size ITO target, comprising the following steps:

[0014] Step 1: Place the ITO blank into a degreasing and sintering integrated furnace and heat it to 280-300℃ at a heating rate of 100-150℃ / h. Keep it warm for 10-25h. During this process, continuously introduce 0.1MPa dry compressed air at a flow rate of 20-30L / min.

[0015] Step 2: After the insulation in step 1 is completed, heat the mixture to 600-620°C at a heating rate of 80-110°C / h and keep it at that temperature for 8-15 hours. During this process, dry compressed air is continuously introduced at a flow rate of 20-30 L / min.

[0016] Step 3: After the insulation in step 2 is completed, cool the furnace to 400°C at a cooling rate of 60-100°C / h, introduce dry compressed air to make the pressure in the furnace reach 0.15-2MPa, and then maintain the pressure and temperature for 15-20h;

[0017] Step 4: After the heat preservation and pressure maintenance in step 3 are completed, the temperature is increased to 1300-1350℃ at a heating rate of 80-120℃ / h and kept at this temperature for 8-15h. During this process, dry compressed air is continuously introduced at a flow rate of 20-30L / min;

[0018] Step 5: After the insulation in step 4 is completed, the temperature is raised to 1600-1700°C at a heating rate of 80-120°C / h and kept at this temperature for 5-20 hours. During this process, dry oxygen is continuously introduced at a flow rate of 5-20 L / min;

[0019] Step 6: After the insulation in step 5 is completed, the temperature is first lowered to 1200°C at a cooling rate of 60-100°C / h, and then lowered to 40°C at a cooling rate of 100-150°C / h to obtain the high-density large-size ITO target.

[0020] Furthermore, the ITO blank is obtained by cold isostatic pressing of ITO powder. The ITO blank is a cylindrical columnar blank with a length of 700-1200 mm, an outer diameter of 153-159 mm, an inner diameter of 135-139 mm, and a wall thickness of 18-20 mm.

[0021] Preferably, the holding time of step 1 is 15-20 hours.

[0022] Preferably, the holding time in step 2 is 10-12 hours.

[0023] Preferably, the heat preservation and pressure holding time of step 3 is 18-20 hours.

[0024] Preferably, the holding time of step 4 is 10-12 hours.

[0025] Preferably, the holding time of step 5 is 8-15 hours, and the flow rate of the dry oxygen is 5-15 L / min.

[0026] The present invention also discloses a high-density large-size ITO target material, which is prepared by the above-mentioned preparation method of the high-density large-size ITO target material. The size of the high-density large-size ITO target material is a cylindrical columnar target material with a length of 700mm-1200mm, an outer diameter of 153-159mm, an inner diameter of 135mm-139mm, and a wall thickness of 18-20mm.

[0027] Beneficial effects

[0028] Compared with the prior art, the present invention has at least the following advantages:

[0029] (1) The present invention sets a low-temperature and high-pressure heat preservation and pressure holding process between the degreasing and sintering processes, thereby ensuring that the moisture and binder in the ITO blank are completely discharged from the interior of the target material, thereby increasing the density of the target material and avoiding the cracking of the target material;

[0030] (2) The present invention discloses a method for preparing a high-density large-size ITO target material, which can produce a high-density large-size target material with a length greater than or equal to 700 mm and a wall thickness greater than or equal to 18 mm;

[0031] (3) The present invention adopts an integrated degreasing and sintering technology, and adds a degreasing finishing process at a low temperature of 400°C and a high pressure of 0.15-2MPa between the transition between degreasing and sintering, which can effectively improve the density of the target material when used for the preparation of large-size ITO targets. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The present invention will be further described below with reference to the accompanying drawings and embodiments;

[0033] Figure 1 This is a photo of the high-density, large-size ITO target produced in Example 3 of the present invention;

[0034] Figure 2 This is a photo of a high-density, large-size ITO target produced in Comparative Example 4 of the present invention. DETAILED DESCRIPTION

[0035] The present invention will be further described below in conjunction with the embodiments, but this does not constitute any limitation to the present invention. Any limited modifications made within the scope of the claims of the present invention are still within the scope of the claims of the present invention.

[0036] In order to explain the technical content of the present invention in detail, further description will be given below in conjunction with the embodiments.

[0037] In the following embodiments and comparative examples, the ITO blank used is a cylindrical columnar blank with a length of 800 mm, an outer diameter of 155 mm, an inner diameter of 135 mm, and a wall thickness of 18 mm. The ITO blank can be prepared by cold isostatic pressing using existing technology in the field. It should be noted that in the field, the ITO blank can also become an ITO target blank.

[0038] Example 1

[0039] A high-density large-size ITO target is prepared by the following steps:

[0040] Step 1: Place the ITO blank into a degreasing and sintering integrated furnace and heat it to 280°C at a heating rate of 100°C / h. Keep it at this temperature for 25 hours. During this process, dry compressed air is continuously introduced at a flow rate of 20L / min.

[0041] Step 2: After the insulation in step 1 is completed, the temperature is raised to 600°C at a heating rate of 80°C / h and kept at this temperature for 15 hours. During this process, dry compressed air is continuously introduced at a flow rate of 20 L / min.

[0042] Step 3: After the insulation in step 2 is completed, the temperature is lowered to 400°C at a cooling rate of 60°C / h, and dry compressed air is introduced to make the pressure in the furnace reach 0.15MPa, and then the pressure is maintained for 20 hours;

[0043] Step 4: After the heat preservation and pressure holding in step 3 are completed, the temperature is raised to 1300°C at a heating rate of 80°C / h and kept at this temperature for 15 hours. During this process, dry compressed air is continuously introduced at a flow rate of 20L / min.

[0044] Step 5: After the insulation in step 4 is completed, the temperature is increased to 1600°C at a heating rate of 80°C / h and kept at this temperature for 20 hours. During this process, dry oxygen is continuously introduced at a flow rate of 5 L / min.

[0045] Step 6: After the insulation in step 5 is completed, first cool the temperature to 1200°C at a cooling rate of 60°C / h, and then cool it to 40°C at a cooling rate of 100°C / h to obtain a high-density large-size ITO target.

[0046] Example 2

[0047] A high-density large-size ITO target is prepared by the following steps:

[0048] Step 1: Place the ITO blank in a degreasing and sintering furnace and heat it to 300°C at a heating rate of 150°C / h, and keep it at that temperature for 10 hours. During this process, dry compressed air is continuously introduced at a flow rate of 30L / min.

[0049] Step 2: After the insulation in step 1 is completed, the temperature is raised to 620°C at a heating rate of 110°C / h and kept at this temperature for 8 hours. During this process, dry compressed air is continuously introduced at a flow rate of 30 L / min;

[0050] Step 3: After the insulation in step 2 is completed, the temperature is lowered to 400°C at a cooling rate of 100°C / h, and dry compressed air is introduced to make the pressure in the furnace reach 0.2MPa, and then the pressure is maintained for 15 hours;

[0051] Step 4: After the heat preservation and pressure holding in step 3 are completed, the temperature is raised to 1350°C at a heating rate of 120°C / h and kept at this temperature for 8 hours. During this process, dry compressed air is continuously introduced at a flow rate of 30L / min;

[0052] Step 5: After the insulation in step 4 is completed, the temperature is increased to 1700°C at a heating rate of 120°C / h and kept at this temperature for 5 hours. During this process, dry oxygen is continuously introduced at a flow rate of 20 L / min;

[0053] Step 6: After the insulation in step 5 is completed, first cool the temperature to 1200°C at a cooling rate of 100°C / h, and then cool it to 40°C at a cooling rate of 150°C / h to obtain a high-density large-size ITO target.

[0054] Example 3

[0055] A high-density large-size ITO target is prepared by the following steps:

[0056] Step 1: Place the ITO blank in a degreasing and sintering furnace and heat it to 300°C at a heating rate of 120°C / h. Keep it at this temperature for 15 hours. During this process, dry compressed air is continuously introduced at a flow rate of 30L / min.

[0057] Step 2: After the insulation in step 1 is completed, the temperature is raised to 620°C at a heating rate of 90°C / h and kept at this temperature for 12 hours. During this process, dry compressed air is continuously introduced at a flow rate of 30 L / min.

[0058] Step 3: After the insulation in step 2 is completed, the temperature is lowered to 400°C at a cooling rate of 80°C / h, and dry compressed air is introduced to make the pressure in the furnace reach 0.18MPa, and then the pressure is maintained for 18 hours;

[0059] Step 4: After the heat preservation and pressure holding in step 3 are completed, the temperature is raised to 1320°C at a heating rate of 100°C / h and kept at this temperature for 10 hours. During this process, dry compressed air is continuously introduced at a flow rate of 30L / min.

[0060] Step 5: After the insulation in step 4 is completed, the temperature is increased to 1650°C at a heating rate of 100°C / h and kept at this temperature for 8 hours. During this process, dry oxygen is continuously introduced at a flow rate of 15 L / min;

[0061] Step 6: After the insulation in step 5 is completed, first cool the temperature to 1200°C at a cooling rate of 60°C / h, and then cool it to 40°C at a cooling rate of 100°C / h to obtain a high-density large-size ITO target.

[0062] Comparative Example 1

[0063] A large-size ITO target is prepared by the following steps:

[0064] Step 1: Place the ITO blank in a degreasing and sintering furnace and heat it to 300°C at a heating rate of 120°C / h. Keep it at this temperature for 15 hours. During this process, dry compressed air is continuously introduced at a flow rate of 30L / min.

[0065] Step 2: After the insulation in step 1 is completed, the temperature is raised to 620°C at a heating rate of 90°C / h and kept at this temperature for 12 hours. During this process, dry compressed air is continuously introduced at a flow rate of 30 L / min.

[0066] Step 3: Heat to 1320°C at a heating rate of 100°C / h and keep at this temperature for 10 hours. During this process, dry compressed air is continuously introduced at a flow rate of 30 L / min.

[0067] Step 4: After the insulation in step 3 is completed, the temperature is increased to 1650°C at a heating rate of 100°C / h and kept at this temperature for 8 hours. During this process, dry oxygen is continuously introduced at a flow rate of 15 L / min;

[0068] Step 5: After the insulation in step 4 is completed, first cool the temperature to 1200°C at a cooling rate of 60°C / h, and then cool it to 40°C at a cooling rate of 100°C / h to obtain a large-size ITO target.

[0069] Comparative Example 2

[0070] A large-size ITO target is prepared by the following steps:

[0071] Step 1: Place the ITO blank into a degreasing and sintering integrated furnace and heat it to 620°C at a heating rate of 90°C / h, and keep it at this temperature for 27 hours. During this process, dry compressed air is continuously introduced at a flow rate of 30L / min.

[0072] Step 2: After the insulation in step 1 is completed, the temperature is lowered to 400°C at a cooling rate of 80°C / h, and dry compressed air is introduced to make the pressure in the furnace reach 0.18MPa, and then the pressure is maintained for 18 hours;

[0073] Step 3: After the heat preservation and pressure holding in step 2 are completed, the temperature is raised to 1320°C at a heating rate of 100°C / h and kept at this temperature for 10 hours. During this process, dry compressed air is continuously introduced at a flow rate of 30L / min.

[0074] Step 4: After the insulation in step 3 is completed, the temperature is increased to 1650°C at a heating rate of 100°C / h and kept at this temperature for 8 hours. During this process, dry oxygen is continuously introduced at a flow rate of 15 L / min;

[0075] Step 5: After the insulation in step 4 is completed, first cool the temperature to 1200°C at a cooling rate of 60°C / h, and then cool it to 40°C at a cooling rate of 100°C / h to obtain a large-size ITO target.

[0076] Comparative Example 3

[0077] A large-size ITO target is prepared by the following steps:

[0078] Step 1: Place the ITO blank in a degreasing and sintering furnace and heat it to 300°C at a heating rate of 120°C / h. Keep it at this temperature for 15 hours. During this process, dry compressed air is continuously introduced at a flow rate of 30L / min.

[0079] Step 2: After the insulation in step 1 is completed, the temperature is raised to 620°C at a heating rate of 90°C / h and kept at this temperature for 12 hours. During this process, dry compressed air is continuously introduced at a flow rate of 30 L / min.

[0080] Step 3: After the insulation in step 2 is completed, the temperature is lowered to 400°C at a cooling rate of 80°C / h, and dry compressed air is introduced to make the pressure in the furnace reach 0.18MPa, and then the pressure is maintained for 18 hours;

[0081] Step 4: After the heat preservation and pressure holding in step 3 are completed, the temperature is increased to 1650°C at a heating rate of 100°C / h and kept at this temperature for 18 hours. During this process, dry oxygen is continuously introduced at a flow rate of 15 L / min.

[0082] Step 5: After the insulation in step 4 is completed, first cool the temperature to 1200°C at a cooling rate of 60°C / h, and then cool it to 40°C at a cooling rate of 100°C / h to obtain a large-size ITO target.

[0083] Comparative Example 4

[0084] A high-density large-size ITO target is prepared by the following steps:

[0085] Step 1: Place the ITO blank in a degreasing and sintering furnace and heat it to 300°C at a heating rate of 120°C / h. Keep it at this temperature for 15 hours. During this process, dry compressed air is continuously introduced at a flow rate of 30L / min.

[0086] Step 2: After the insulation in step 1 is completed, the temperature is raised to 620°C at a heating rate of 90°C / h and kept at this temperature for 12 hours. During this process, dry compressed air is continuously introduced at a flow rate of 30 L / min.

[0087] Step 3: After the insulation in step 2 is completed, maintain the temperature at 620°C and introduce dry compressed air to make the pressure in the furnace reach 0.18 MPa, and then maintain the pressure and insulation for 18 hours;

[0088] Step 4: After the heat preservation and pressure holding in step 3 are completed, the temperature is raised to 1320°C at a heating rate of 100°C / h and kept at this temperature for 10 hours. During this process, dry compressed air is continuously introduced at a flow rate of 30L / min.

[0089] Step 5: After the insulation in step 4 is completed, the temperature is increased to 1650°C at a heating rate of 100°C / h and kept at this temperature for 8 hours. During this process, dry oxygen is continuously introduced at a flow rate of 15 L / min;

[0090] Step 6: After the insulation in step 5 is completed, first cool the temperature to 1200°C at a cooling rate of 60°C / h, and then cool it to 40°C at a cooling rate of 100°C / h to obtain a high-density large-size ITO target.

[0091] Comparative Example 5

[0092] A large-size ITO target is prepared by the following steps:

[0093] Step 1: Place the ITO blank in a degreasing and sintering furnace and heat it to 300°C at a heating rate of 120°C / h. Keep it at this temperature for 15 hours. During this process, dry compressed air is continuously introduced at a flow rate of 30L / min.

[0094] Step 2: After the insulation in step 1 is completed, the temperature is raised to 620°C at a heating rate of 90°C / h and kept at this temperature for 12 hours. During this process, dry compressed air is continuously introduced at a flow rate of 30 L / min.

[0095] Step 3: After the insulation in step 2 is completed, the temperature is lowered to 400°C at a cooling rate of 80°C / h, and dry compressed air is introduced to make the pressure in the furnace reach 0.1MPa, and then the pressure is maintained for 18 hours;

[0096] Step 4: After the heat preservation and pressure holding in step 3 are completed, the temperature is raised to 1320°C at a heating rate of 100°C / h and kept at this temperature for 10 hours. During this process, dry compressed air is continuously introduced at a flow rate of 30L / min.

[0097] Step 5: After the insulation in step 4 is completed, the temperature is increased to 1650°C at a heating rate of 100°C / h and kept at this temperature for 8 hours. During this process, dry oxygen is continuously introduced at a flow rate of 15 L / min;

[0098] Step 6: After the insulation in step 5 is completed, first cool the temperature to 1200°C at a cooling rate of 60°C / h, and then cool it to 40°C at a cooling rate of 100°C / h to obtain a large-size ITO target.

[0099] Comparative Example 6

[0100] A large-size ITO target is prepared by the following steps:

[0101] Step 1: Place the ITO blank in a degreasing and sintering furnace and heat it to 300°C at a heating rate of 120°C / h. Keep it at this temperature for 15 hours. During this process, dry compressed air is continuously introduced at a flow rate of 30L / min.

[0102] Step 2: After the insulation in step 1 is completed, the temperature is raised to 620°C at a heating rate of 90°C / h and kept at this temperature for 12 hours. During this process, dry compressed air is continuously introduced at a flow rate of 30 L / min.

[0103] Step 3: After the insulation in step 2 is completed, maintain the temperature at 620°C and introduce dry compressed air to make the pressure in the furnace reach 0.1 MPa, and then maintain the pressure and insulation for 18 hours;

[0104] Step 4: After the heat preservation and pressure holding in step 3 are completed, the temperature is raised to 1320°C at a heating rate of 100°C / h and kept at this temperature for 10 hours. During this process, dry compressed air is continuously introduced at a flow rate of 30L / min.

[0105] Step 5: After the insulation in step 4 is completed, the temperature is increased to 1650°C at a heating rate of 100°C / h and kept at this temperature for 8 hours. During this process, dry oxygen is continuously introduced at a flow rate of 15 L / min;

[0106] Step 6: After the insulation in step 5 is completed, first cool the temperature to 1200°C at a cooling rate of 60°C / h, and then cool it to 40°C at a cooling rate of 100°C / h to obtain a large-size ITO target.

[0107] Comparative Example 7

[0108] A large-size ITO target is prepared by the following steps:

[0109] Step 1: Place the ITO blank into a degreasing and sintering furnace and heat the temperature from room temperature to 200°C at a rate of 0.5°C / min, while introducing dry air at a flow rate of 300L / min;

[0110] Step 2: Raise the temperature to 400°C at a rate of 0.4°C / min and keep warm for 4 hours while introducing dry air at a flow rate of 300 L / min;

[0111] Step 3: Raise the temperature to 700°C at a rate of 3°C / min and keep it there for 3 hours while introducing dry air at a flow rate of 300 L / min;

[0112] Step 4: Raise the temperature to 1100°C at a rate of 3°C / min and keep warm for 2 hours while introducing oxygen at a flow rate of 800L / min. The oxygen pressure in the furnace is at atmospheric pressure.

[0113] Step 5: Raise the temperature to 1400°C at a rate of 3°C / min and keep warm for 2 hours while introducing oxygen at a flow rate of 800L / min. The oxygen pressure in the furnace is at atmospheric pressure.

[0114] Step 6: Raise the temperature to 1500°C at a rate of 2.5°C / min, while introducing oxygen at a flow rate of 800L / min. The oxygen pressure in the furnace is at atmospheric pressure.

[0115] Step 7: Raise the temperature to 1700°C at a rate of 8°C / min and keep warm for 20 hours while introducing oxygen at a flow rate of 800 L / min. The oxygen pressure in the furnace is at atmospheric pressure.

[0116] Step 8: Reduce the temperature to 1500°C at a rate of 2°C / min and keep it for 3 hours. At the same time, introduce oxygen at a flow rate of 800L / min. The oxygen pressure in the furnace is at atmospheric pressure.

[0117] Step 9: The temperature was lowered to 1300°C at a rate of 3°C / min, while oxygen was introduced at a flow rate of 800 L / min. The oxygen pressure in the furnace was at atmospheric pressure.

[0118] Step 10: Reduce the temperature to 1100°C at a rate of 0.5°C / min and keep warm for 2 hours while introducing oxygen at a flow rate of 300 L / min. The oxygen pressure in the furnace is at atmospheric pressure.

[0119] Step 11: Cool down to room temperature at a rate of 0.5℃ / min to obtain a large-sized ITO target

[0120] Performance Testing

[0121] The density of the ITO targets prepared in Examples 1-3 and Comparative Examples 1-6 was tested using the drainage method (Archimedes principle). The results are shown in Table 1.

[0122] Table 1 Density test results of ITO targets prepared in Examples 1-3 and Comparative Examples 1-6

[0123] <![CDATA[Target density (g / cm 3 )]]> Example 1 7.146 Example 2 7.146 Example 3 7.145 Comparative Example 1 7.129 Comparative Example 2 7.136 Comparative Example 3 7.130 Comparative Example 4 7.146 Comparative Example 5 7.129 Comparative Example 6 7.133 Comparative Example 7 7.137

[0124] It should be noted that in the field of ITO targets, when the targets are used for thin film preparation, the density of the targets is 7.130 g / cm 3 The following film performance is at the same level, target density ≥7.130g / cm 3 And <7.140g / cm 3 The performance of the film prepared by it will be significantly higher than that of the target material with a density of 7.130g / cm 3 The film prepared below has a target density of 7.140 g / cm 3The performance of the film prepared above will be further improved to a higher level. According to the results in Table 1:

[0125] According to the data comparison between Example 3 and Comparative Examples 1, 5 and 6, it can be seen that the heat preservation and pressure keeping means of 400°C low temperature and 0.18MPa high pressure between the degreasing and sintering processes of the present invention can effectively improve the density of large-size targets; among them, Comparative Example 1 does not adopt the heat preservation and pressure keeping means of 400°C low temperature and MPa high pressure between the degreasing and sintering processes, so when preparing large-size targets, the density of the targets is significantly reduced; and Comparative Example 5 adopts the heat preservation and pressure keeping means of 400°C low temperature and 0.1MPa low pressure, which cannot effectively remove the residual moisture and binder inside the target during the process, so the density of the large-size targets is not improved; Comparative Example 6 adopts the heat preservation and pressure keeping means of 600°C high temperature and 0.1MPa low pressure. Although the density of the target is improved, the extent of the improvement cannot meet the requirements of large-size targets for high-performance films.

[0126] According to the data comparison of Example 3 and Comparative Example 7, although the technical means of multi-stage slow heating, heat preservation, degreasing and sintering can effectively improve the density of large-sized targets, the density improvement cannot reach 7.140 g / cm 3 , which cannot meet higher performance requirements; therefore, the present invention adopts a heat preservation and pressure preservation method of 400℃ low temperature and 0.18MPa high pressure between the degreasing process and the sintering process, which can significantly improve the target density of large-sized targets, so that the target density can reach 7.140g / cm 3 And above, to meet the performance requirements of higher-level products.

[0127] According to the data comparison between Example 3 and Comparative Examples 2 and 3, it can be seen that the present invention not only needs to add a 400°C low-temperature 0.15-2MPa high-pressure insulation and pressure-maintaining means between the degreasing and sintering processes, but also needs to perform step-by-step heating and heat preservation in both the degreasing and sintering stages to effectively improve the target density of large-size targets.

[0128] According to the data comparison of Example 3 and Comparative Example 4, the density of the target material can be effectively improved by using a high temperature greater than 400°C combined with a high pressure of 0.15-2MPa. However, due to the long-term high temperature and high pressure, the target material is prone to cracking, resulting in a sharp drop in the yield of the target material. See the attached figure for details. Figure 1 and attached Figure 2 Comparison, with Figure 2The high-density large-size ITO target material is prepared by the preparation method of Comparative Example 4. Since the size of the target material is too large, once the target material cracks, the entire target material will crack directly, and there is no possibility of remedying or removing the cracked section to form a small-size target material, which increases the production cost; therefore, the present invention adopts a high temperature of 400°C combined with a high pressure of 0.15-2MPa to maintain heat and pressure, which ensures the target density of large-size ITO targets with a length greater than or equal to 700mm and a wall thickness greater than or equal to 18mm while controlling the yield and reducing the production cost.

[0129] The embodiments presented herein are merely embodiments selected from a combination of all possible embodiments. The appended claims should not be limited by the embodiments describing the present invention. Some numerical ranges used in the claims include subranges therein, and variations in these ranges should also be covered by the appended claims.

Claims

1. A method for preparing a high-density large-size ITO target, characterized in that: The steps include: Step 1: Place the ITO blank into a degreasing and sintering integrated furnace and heat it to 280-300℃ at a heating rate of 100-150℃ / h. Keep it warm for 10-25h. During this process, dry compressed air is continuously introduced at a flow rate of 20-30L / min. Step 2: After the insulation in step 1 is completed, heat the mixture to 600-620°C at a heating rate of 80-110°C / h and keep it at that temperature for 8-15 hours. During this process, dry compressed air is continuously introduced at a flow rate of 20-30 L / min. Step 3: After the insulation in step 2 is completed, cool the furnace to 400°C at a cooling rate of 60-100°C / h, introduce dry compressed air to make the pressure in the furnace reach 0.15-2MPa, and then maintain the pressure and temperature for 15-20h; Step 4: After the heat preservation and pressure maintenance in step 3 are completed, the temperature is increased to 1300-1350℃ at a heating rate of 80-120℃ / h and kept at this temperature for 8-15h. During this process, dry compressed air is continuously introduced at a flow rate of 20-30L / min; Step 5: After the insulation in step 4 is completed, the temperature is raised to 1600-1700°C at a heating rate of 80-120°C / h and kept at this temperature for 5-20 hours. During this process, dry oxygen is continuously introduced at a flow rate of 5-20 L / min; Step 6: After the insulation in step 5 is completed, the temperature is first lowered to 1200°C at a cooling rate of 60-100°C / h, and then lowered to 40°C at a cooling rate of 100-150°C / h to obtain the high-density large-size ITO target.

2. The method for preparing a high-density large-size ITO target according to claim 1, wherein: The ITO blank is obtained by cold isostatic pressing of ITO powder. The ITO blank is a cylindrical columnar blank with a length of 700-1200 mm, an outer diameter of 153-159 mm, an inner diameter of 135-139 mm, and a wall thickness of 18-20 mm.

3. The method for preparing a high-density large-size ITO target according to claim 1, wherein: The insulation time of step 1 is 15-20 hours.

4. The method for preparing a high-density large-size ITO target according to claim 1, wherein: The insulation time of step 2 is 10-12 hours.

5. The method for preparing a high-density large-size ITO target according to claim 1, wherein: The heat preservation and pressure holding time of step 3 is 18-20 hours.

6. The method for preparing a high-density large-size ITO target according to claim 1, wherein: The insulation time of step 4 is 10-12 hours.

7. The method for preparing a high-density large-size ITO target according to claim 1, wherein: The holding time of step 5 is 8-15 hours, and the flow rate of the dry oxygen is 5-15 L / min.

8. A high-density large-size ITO target, characterized in that: The high-density large-size ITO target is prepared by the preparation method of any one of claims 1 to 7, wherein the high-density large-size ITO target is a cylindrical columnar target with a length of 700mm-1200mm, an outer diameter of 153-159mm, an inner diameter of 135mm-139mm, and a wall thickness of 18-20mm.

Images