Background
The ITO target material is one of ceramic target materials, and in recent years, the special pursuit of people for display screens of computers, televisions and mobile phones is more obvious, so that the market demand of the ITO target material is driven. However, the development of the current ITO technology is not advanced enough, and the development space is huge. The ITO material is an n-type semiconductor material and comprises ITO powder, a target material, conductive slurry and an ITO transparent conductive film. The main applications of the organic electroluminescent display are classified into flat panel display industries, such as liquid crystal displays, thin film transistor displays, electroluminescent displays, field emission displays, electroluminescent flat panel displays, and plasma displays.
After massive search, the prior art is found, the publication number is CN108947520A, and the method for preparing the ITO sintered target material comprises the following steps: carrying out wet ball milling on InO powder and SnO powder together to obtain ITO slurry, wherein the original particle size ratio of the InO powder to the SnO powder is 1: (1.0-2.0), wherein the primary particle size of InO powder is 50nm-200 nm; carrying out spray granulation on the obtained ITO slurry to obtain ITO granulation powder; loading the obtained ITO granulation powder into a cold pressing die, and carrying out one-step cold isostatic pressing after vibration and vacuumizing operation to obtain an ITO green body; and sintering the obtained ITO green body in an oxygen atmosphere to obtain the ITO sintered target. The ITO sintered target material prepared by the preparation method has excellent properties of high density, low resistivity and high strength, and solves the problems of complex process flow, high cost and great environmental pollution of the preparation method of the ITO sintered target material in the prior art.
In conclusion, the domestic demand for the ITO target is greatly increased, and the ITO target produced in China has low density, so that the requirement of the high-end flat panel display industry on the target quality cannot be met. In addition, the existing target preparation method can not produce the target with large size and complex appearance, and meanwhile, the production efficiency is low, and the actual use requirement can not be met.
Disclosure of Invention
The invention aims to provide a preparation method of an ITO (indium tin oxide) sintered target material, which aims to solve the problems in the background technology.
In order to achieve the purpose, the invention provides the following technical scheme: a preparation method of an ITO (indium tin oxide) sintered target material is characterized by comprising the following steps: the preparation method comprises a hot isostatic pressing method and a cold isostatic pressing method, wherein the hot isostatic pressing method and the cold isostatic pressing method both comprise the following process steps: preparing, blanking and sintering;
the configuration process of the hot isostatic pressing method and the cold isostatic pressing method comprises the following steps: partially reducing single-phase ITO solid solution powder under a certain reducing atmosphere and temperature, wherein the reduction degree is between 0.02 and 0.2;
after the hot isostatic pressing method is configured, pressing the reduced powder into a primary blank, and placing the primary blank in a stainless steel sheath;
when the primary blanks are placed in the stainless steel sheaths, the primary blanks are separated by adopting an isolation material, a plurality of primary blank isolation bins are arranged between the stainless steel sheaths for carrying out batch green pressing, and the isolation material is arranged in the sheaths and can separate the primary blanks, so that the number of the primary blanks placed in the sheaths is increased, and batch production can be carried out;
the isolation material is designed by adopting a stainless steel material, and the surface of the isolation material is in smooth circular distribution and is consistent with the appearance of the primary blank;
the heating temperature of the hot isostatic pressing furnace is controlled to be between 800 ℃ and 1050 ℃, the pressure is controlled to be between 50 and 200MPa, and the time is 2 to 6 hours;
after the cold isostatic pressing method is used for manufacturing a primary blank, the primary blank is placed in a sheath in a normal temperature environment, the sheath is made of plastic or rubber, the relative density of the primary blank manufactured by the cold isostatic pressing method is 60% after pressing, and the ITO target with the relative density of more than 90% can be obtained by adopting high temperature of 1600 ℃ and sintering for 6 hours;
after the forming, the blank is placed in a pure oxygen environment with 0.1-0.9MPa, and is sintered at the high temperature of 1500-.
Preferably, in the configuration process, the reducing atmosphere gas comprises a mixed gas of H2, H2 and N2.
Preferably, the opening of the stainless steel sheath is sealed, the stainless steel sheath is vacuumized, and the stainless steel sheath is placed in a hot isostatic pressing furnace for heating;
the target material adopting the hot isostatic pressing method is not easy to reduce, the density of the prepared target material is higher, and the target material with large size and complex appearance can be prepared.
Preferably, liquid is used as a medium in the cold isostatic pressing process, the powder is molded when the liquid is transmitted to the ultrahigh pressure, and the pressure is controlled at 100-630 MPa.
Preferably, the temperature of the reducing atmosphere is controlled between 300 ℃ and 500 ℃.
Compared with the prior art, the invention has the beneficial effects that: according to the invention, the isolation material is arranged in the sheath in the hot isostatic pressing method, so that the primary blanks can be isolated, more primary blanks can be placed in the sheath, the production efficiency is effectively improved, the requirement of mass production is met, meanwhile, the hot isostatic pressing method can be used for processing the target with a complicated external shape, and the target with a large size can be prepared by matching with the use of the cold isostatic pressing method, so that the target with high density and large size can be produced, the production efficiency is improved, and the market requirement can be met.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In the description of the present invention, it should be noted that the terms "upper", "lower", "inner", "outer", "front", "rear", "both ends", "one end", "the other end", and the like indicate orientations or positional relationships only for convenience in describing the present invention and simplifying the description, but do not indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
In the description of the present invention, it is to be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "disposed," "connected," and the like are to be construed broadly, such as "connected," which may be fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.
The invention provides two embodiments: the preparation method of the ITO sintered target comprises the following process steps of: preparing, blanking and sintering;
the configuration process of the hot isostatic pressing method and the cold isostatic pressing method comprises the following steps: the single-phase ITO solid solution powder is partially reduced under a certain reducing atmosphere and temperature, and the degree of reduction is between 0.02 and 0.2.
In the preparation process, the component of reducing atmosphere gas is H2、H2And N2The temperature of the mixed gas is controlled between 300 ℃ and 500 ℃.
The first embodiment is as follows:
completing the configuration of a hot isostatic pressing method, pressing the reduced powder into a primary blank, and placing the primary blank in a stainless steel sheath;
when the primary blanks are arranged in the stainless steel sheath, the primary blanks are separated by adopting an isolation material, and a plurality of primary blank isolation bins are arranged between the stainless steel sheaths for pressing blanks in batches.
Sealing the opening of the stainless steel sheath, vacuumizing the stainless steel sheath, and heating the stainless steel sheath in a hot isostatic pressing furnace;
the heating temperature is controlled between 800-;
the target material adopting the hot isostatic pressing method is not easy to reduce, the density of the prepared target material is higher, and the target material with large size and complex appearance can be prepared;
and the sheathed hot isostatic pressing is a process of placing ceramic powder or a pressed compact in a sheathed material, then carrying out vacuum sealing, and then realizing densification under the conditions of high temperature and high pressure. The requirements for the jacket material are: the ceramic material is high temperature resistant, does not react with the ceramic material at the sintering temperature, is easy to separate from the ceramic after cooling, has excellent weldability and reliable sealing, and has good deformability at high temperature so as to effectively transfer pressure; the viscosity at high temperature is high enough to prevent the sheath from penetrating into the sintered body when the sheath is softened. When the hot isostatic pressing sintering temperature is lower than 1500 ℃, a low-carbon steel sheet is commonly used as a sheath material, and the sheath material can also be sealed by quartz glass.
The glass sheath is more economical than low-carbon steel when a blank with a complex shape is installed. Residual gas in the envelope after packaging can affect final densification, so degassing and packaging are carried out in vacuum, or gas in the powder is extracted by using an exhaust pipe, then the exhaust pipe is flattened, and the opening is sealed by adopting quick welding and melting;
meanwhile, the isolating material is arranged in the sheath and can separate the primary blanks, the isolating material is designed by adopting a stainless steel material, the surface of the isolating material is in smooth circular distribution and is consistent with the appearance of the primary blanks, so that the number of the primary blanks placed in the sheath is increased, batch production can be carried out, the production efficiency is effectively improved, the requirement of large-batch production is met, and meanwhile, the target with a complex external appearance can be processed by a hot isostatic pressing method.
Example two:
after the initial blank is manufactured by the cold isostatic pressing method, the initial blank is placed in a sheath in a normal temperature environment, the material of the sheath is plastic or rubber, wherein liquid is used as a medium, powder is formed when the liquid transmits ultrahigh pressure, and the pressure is controlled at 100-630 MPa;
the cold isostatic pressing machine mainly comprises an elastic mould, a cylinder body, a frame, a hydraulic system and the like, wherein the elastic mould is made of rubber or resin materials. The material particle size and shape have a large impact on the die life. The design of the die is the key of isostatic pressing, because the precision and the compactness uniformity of the blank size are closely related to the die. When the materials are loaded into the die, the edges and corners of the die are not easy to be filled with the materials, and the materials can be loaded by vibration or vacuumized while vibrating, so that the effect is better;
after the forming, the blank is placed in a pure oxygen environment with 0.1-0.9MPa, and is sintered at the high temperature of 1500-;
the density of the sintered target material can reach 95 percent.
In the process of manufacturing the primary blank by the cold isostatic pressing method, the ITO target material with the relative density of more than 90 percent can be obtained by pressing and sintering for 6 hours at the high temperature of 1600 ℃ with the relative density of 60 percent;
compared with mechanical pressing, the cold isostatic pressing method has higher pressing pressure, is suitable for pressing large-size target materials, and the pressed powder products have high density and uniform distribution, do not need to be added with lubricant, and are suitable for batch production.
It will be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, and that the present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.