Composite iridium crucible and preparation method and application thereof

Abstract

The invention relates to the technical field of crucibles, and provides a composite iridium crucible and a preparation method and application thereof. The composite iridium crucible comprises an iridium crucible body, a hafnium carbide isolation layer and a rhenium supporting body. By arranging the rhenium supporting body, the strength of the composite iridium crucible is improved by 3.5-5.4 times compared with that of a pure iridium crucible, the use amount and cost of iridium metal are reduced by 65-94%, and the service life is prolonged by 53% or above; the hafnium carbide isolation layer can effectively prevent diffusion between rhenium and iridium elements and can reduce volatilization of more than 50% of iridium metal; in addition, the thermal matching performance of rhenium, iridium and hafnium carbide is good, and the stability and integrity of the crucible can be kept under severe thermal shock. The production efficiency of the composite iridium crucible is greatly improved by improving the preparation process of the rhenium supporting body and the hafnium carbide isolating layer. When the composite iridium crucible is applied to preparation of a crystal material, the cost of the crucible can be greatly reduced, and meanwhile, the service life of the crucible can be remarkably prolonged.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of crucibles, in particular to a composite iridium crucible and a preparation method and application thereof. BACKGROUND

[0002] The noble metal iridium has high melting point, strong corrosion resistance and high temperature resistance, and is the first choice for manufacturing crucibles. Iridium crucibles perform well under extreme conditions and are commonly used in fields such as metal smelting and high-temperature chemical reactions. Iridium crucibles are mainly used for growing high-melting-point crystals such as sapphire, yttrium aluminum garnet (YAG), lutetium orthosilicate (LSO) and yttrium lutetium orthosilicate (LYSO) by the Czochralski method. Although the melting point of iridium is as high as 2443℃, when the melting point of the crystal exceeds 2000℃ (the melting point of LYSO crystal is 2100℃), the iridium crucible has problems such as serious loss of iridium metal due to volatilization and deformation or even leakage of the crucible after long-term use. Whether the deformation, leakage or volatilization of the crucible will cause the service life of the crucible to decrease and the cost to increase.

[0003] For many years, people have been continuously working on the thinning, strengthening and reducing volatilization of iridium crucibles. At present, the main methods to enhance the strength of the iridium crucible body are iridium alloying, adding a tungsten support body to the outer layer of the crucible, setting reinforcing ribs on the inner surface and adjusting the device, etc. The measures to reduce the volatilization of iridium metal are generally to coat ceramic coatings such as zirconia or yttria on the inner and outer surfaces of the iridium crucible. It is an easy and common method to use alloying to improve the strength of metal materials, and although the addition of alloying elements such as zirconium and yttrium can improve the strength of the iridium crucible, it actually changes the composition and properties of the iridium material to some extent. At high temperatures, alloying elements may diffuse into the molten crystal, which adversely affects the quality of the crystal. In addition, the separation process of alloying elements and iridium metal is very complex, and the recovery of the crucible is difficult. Therefore, for the drawing of high-quality crystals, alloying treatment of the iridium crucible is not desirable.

[0004] A method for manufacturing a tungsten-iridium crucible is provided in the related art, in which a tungsten ingot and an iridium ingot are prepared by a casting method, the ingots are machined into an iridium crucible and a tungsten crucible body by a machining method, and the iridium crucible and the tungsten crucible body are combined together by a hot isostatic pressing technology. Both tungsten and iridium are brittle metals with extremely high hardness, and the machining difficulty is extremely great. Moreover, tungsten and iridium elements mutually diffuse at the interface, and after long-term use at high temperature, the composition of the iridium crucible will change. Therefore, this method is basically not feasible in terms of technical selection and manufacturing cost.

[0005] In the related art, an iridium gold crucible is provided by arranging a reinforcing rib inside the sidewall of the iridium crucible and spraying a ZrO2 protective coating on the outer surface of the crucible. This method has a good effect on enhancing the strength of the iridium crucible, reducing the deformation of the crucible and the volatilization of iridium metal. However, since the iridium reinforcing rib is arranged, the amount of iridium metal is actually increased. In addition, there is a large difference in the thermal expansion coefficient between the ZrO2 ceramic protective coating sprayed on the outer surface of the crucible and the material of the iridium crucible. After multiple heating-cooling cycles, the coating may crack and even peel off from the surface of the iridium crucible.

[0006] In the related art, a protective adjusting device for improving the service life of an iridium crucible is disclosed. The device is composed of a protective component for protecting the iridium crucible and an adjusting component connected to the lower side of the protective component. The protective component supports and enhances the pot wall of the iridium crucible, thereby improving the service life of the crucible. However, the protective component is a mesh structure, and its protective effect on larger iridium crucibles is limited. Moreover, if the protective component is made of metal, the elements may diffuse between the iridium crucible and the metal component, causing mutual adhesion and thus damaging the iridium crucible and the protective component. At the same time, the alloy elements entering the iridium crucible will significantly increase the difficulty and cost of recycling the iridium crucible.

[0007] In summary, in the current technical solutions for enhancing the strength of the iridium crucible and reducing the volatilization of iridium gold, there are common problems such as changing the composition and properties of the iridium material, easy peeling of the coating and short service life, which cannot meet the use requirements. SUMMARY

[0008] Therefore, the present application provides a composite iridium crucible, a preparation method and application thereof. The present application uses refractory rare metal rhenium as an outer support of the iridium crucible to enhance the strength of the crucible. A hafnium carbide ultra-high temperature ceramic isolation layer is prepared between the rhenium support and the iridium crucible to prevent the diffusion of rhenium elements and iridium elements at the interface. The composite iridium crucible provided by the present application does not change the composition and properties of the iridium material, has high strength and long service life.

[0009] In order to achieve the above-mentioned application purposes, the present application provides the following technical solutions: A composite iridium crucible, comprising an iridium crucible body, a hafnium carbide isolation layer arranged on the outer surface of the iridium crucible body, and a rhenium support arranged on the outer surface of the hafnium carbide isolation layer.

[0010] Preferably, the thickness of the iridium crucible body is 0.8-1.5 mm; the thickness of the hafnium carbide isolation layer is 0.2-0.6 mm; and the thickness of the rhenium support is 1-3 mm.

[0011] The present application also provides a preparation method of the composite iridium crucible as described in the above solutions, comprising the following steps: (1) adopting on-site chlorination chemical vapor deposition method, depositing hafnium carbide isolation layer on the outer surface of the iridium crucible body, obtaining hafnium carbide / iridium crucible; (2) the hafnium carbide / iridium crucible is subjected to degassing treatment, and a degassing hafnium carbide / iridium crucible is obtained; (3) adopting on-site chlorination chemical vapor deposition method, depositing rhenium support on the outer surface of the degassing hafnium carbide / iridium crucible, obtaining the composite iridium crucible.

[0012] Preferably, when depositing the hafnium carbide isolation layer or the rhenium support, the bottom of the iridium crucible body or the degassing hafnium carbide / iridium crucible is placed upward, and a molybdenum core matched with the inner profile size of the iridium crucible body is placed inside.

[0013] Preferably, the conditions for depositing the hafnium carbide isolation layer by on-site chlorination chemical vapor deposition method in step (1) include: chlorination temperature of 300-500℃, deposition temperature of 1600-1700℃, chlorine flow rate of 100-300mL / min, methane flow rate of 200-400mL / min, hydrogen flow rate of 1300-1500mL / min, and deposition chamber pressure of 700-900Pa; The device for depositing the hafnium carbide isolation layer by on-site chlorination chemical vapor deposition method includes a chlorination chamber and a deposition chamber, the hafnium sheet is placed in the chlorination chamber, chlorine is introduced into the chlorination chamber, and the hafnium chloride generated by the chlorination reaction of chlorine and the hafnium sheet enters the deposition chamber; methane and hydrogen are introduced into the deposition chamber.

[0014] Preferably, the temperature of the degassing treatment is 1100-1300℃, the holding time is 1-3h, and the vacuum degree is 1×10 -3 ~2×10 -3 Pa.

[0015] Preferably, the conditions for depositing the rhenium support by on-site chlorination chemical vapor deposition method in step (3) include: chlorination temperature of 800-1000℃, deposition temperature of 1400-1600℃, chlorine flow rate of 150-250mL / min, and deposition chamber pressure of 1400-1600Pa; The device for depositing the rhenium support by on-site chlorination chemical vapor deposition method includes a chlorination chamber and a deposition chamber, the rhenium block is placed in the chlorination chamber, chlorine is introduced into the chlorination chamber, and the rhenium chloride generated by the chlorination reaction of chlorine and the rhenium block enters the deposition chamber.

[0016] Preferably, the relative density of the rhenium block is 55-65%.

[0017] Preferably, the preparation method of the rhenium block comprises: pressing rhenium powder and then sintering to obtain a rhenium block; the pressure of the pressing is 40-60 MPa, the sintering temperature is 1500-1600℃, the time is 1-2h, and the vacuum degree is 1x10 -3 ~2x10 -3 Pa.

[0018] The application further provides the application of the composite iridium crucible in the preparation of crystal materials.

[0019] The application provides a composite iridium crucible, which comprises an iridium crucible body, a hafnium carbide isolation layer arranged on the outer surface of the iridium crucible body, and a rhenium support arranged on the outer surface of the hafnium carbide isolation layer. -1 The melting point of rhenium (Re) is as high as 3180℃, and rhenium has excellent comprehensive properties such as high high-temperature strength, good plasticity, good thermal shock resistance and good chemical inertness. The melting point of hafnium carbide (HfC) is 3890℃, which is the highest among known single compounds, and hafnium carbide is an ultra-high-temperature, low-thermal-conductivity material (thermal conductivity is only 5.6 W·m -1 ·K ) with good oxidation resistance, ablation resistance and high-temperature thermal shock resistance. As a protective coating of carbon-based materials or refractory metals, hafnium carbide has good application prospects. So far, there is no report on the application of rhenium and hafnium carbide to the support and isolation layer of the iridium crucible. In the application, the refractory rare metal rhenium is used as the outer support of the iridium crucible to enhance the strength of the crucible; a hafnium carbide ultra-high-temperature ceramic isolation layer is prepared between the rhenium support and the iridium crucible to prevent the diffusion of rhenium elements and iridium elements at the interface, so as to avoid changing the composition and properties of the iridium material; meanwhile, the hafnium carbide isolation layer can effectively prevent the volatilization of iridium metal, greatly reducing the cost of the crucible, and the low-thermal-conductivity hafnium carbide also has a good heat preservation effect on the crystal melt, which can reduce the energy consumption in the crystal preparation process. Moreover, the thermal expansion coefficients of rhenium, iridium and hafnium carbide are very close (6.7x10 -6 / ℃, 6.8x10 -6 / ℃ and 6.7x10 -6 / ℃, respectively), and the three materials have good thermal matching, so that the stability and integrity of the crucible can be maintained under severe thermal shock in the use environment, and problems such as coating peeling do not occur, and the service life is long.

[0020] Further, the thickness of the iridium crucible body in the composite iridium crucible provided by the application is much lower than that of a pure iridium crucible with the same diameter. The Non-ferrous Metal Industry Standard (YS / T 564-2009) stipulates that the thickness of the iridium crucible produced by the welding method is 1.5-2mm when the diameter is 38-150mm. The thickness of the iridium crucible body used in the composite iridium crucible prepared by the application is 0.8-1.2mm, which is 65-94% lower than the amount and cost of iridium metal used in the existing pure iridium crucible produced by the welding method.

[0021] In summary, the composite iridium crucible provided by the present application has the performance characteristics of not changing the composition of iridium material, less iridium evaporation, high strength, good thermal cycle impact resistance, long service life, and less iridium usage, and has a broad application prospect.

[0022] The present application also provides a preparation method of the composite iridium crucible described in the above scheme. The present application adopts on-site chlorination method to deposit the hafnium carbide isolation layer and the rhenium support, which is simple to operate and has high production efficiency. Further, the present application improves the deposition conditions to greatly improve the deposition rate. The deposition rate of rhenium and hafnium carbide prepared by traditional CVD method is not more than 350 µm / h and 30 µm / h respectively. Under the condition of lower deposition efficiency, the production cycle is longer. The present application improves the preparation process, so that the deposition rate of rhenium and hafnium carbide is increased to 500-600 µm / h and 50-80 µm / h respectively, which greatly shortens the deposition time, improves the production efficiency of the composite iridium crucible, and reduces the energy consumption in the production process. In addition, under the process conditions of the present application, the deposition efficiency of rhenium is also improved from the current highest 93% to more than 98%, which plays an important role in the efficient use of rare metal rhenium. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 A longitudinal sectional view of the composite iridium crucible provided by the present application is shown in the figure; Figure 2 A schematic diagram of the principle of preparing the hafnium carbide isolation layer by on-site chlorination chemical vapor deposition method is shown in the figure; Figure 3 A schematic diagram of the principle of preparing the rhenium support by on-site chlorination chemical vapor deposition method is shown in the figure; Figure 4 A physical map of the iridium crucible body with an outer diameter of 56 mm used in Example 2 is shown in the figure; Figure 5 A physical map of the composite iridium crucible prepared in Example 2 is shown in the figure. DETAILED DESCRIPTION

[0024] TERMS EXPLANATION: Iridium crucible: The iridium crucible is a high-temperature container made of pure iridium or iridium alloy, which belongs to precision instruments and equipment, and is mainly used in the fields of rare metal smelting, artificial crystal growth, sapphire synthesis, and semiconductor material preparation. Its working temperature can reach 2100-2200℃, and it has the characteristics of acid and alkali corrosion resistance, strong chemical stability, etc., and can be used continuously for thousands of hours.

[0025] Rhenium: Rhenium is a high-melting-point rare metal element with a hexagonal structure, with a melting point of 3180℃, a density of 21.02 g / cm 3 , and a thermal expansion coefficient of 6.7×10 -6Rhenium has a series of excellent properties, such as high strength, high hardness, good room temperature plasticity, chemical inertness and catalytic performance, and is widely used in catalysts, coating materials and ultra-high temperature structural materials.

[0026] Hafnium carbide: hafnium carbide (HfC) has a melting point of 3890℃, which is the highest among known single compounds, and is an ultra-high temperature, low thermal conductivity material resistant to oxidation, ablation and high temperature thermal shock. It has good application prospects as a protective coating for easily oxidized carbon-based materials or refractory metals.

[0027] Chemical vapor deposition (CVD): is a process of using gaseous substances to perform chemical reactions on the surface of solids to generate solid deposition. The prepared materials can be metals, inorganic materials, and the material forms include thin films, coatings or bulk materials. The materials prepared by CVD have the characteristics of high density and shape preservation near isostatic forming.

[0028] In-situ chlorination chemical vapor deposition method: during the CVD deposition process, chlorine gas (Cl2) is directly introduced, and chlorine gas reacts with raw metal to form precursor gas required for deposition of the material, such as ReCl5, HfCl4, etc. At high temperature, the precursor gas decomposes or undergoes other chemical reactions, and the deposited metal or formed compound is deposited on the substrate.

[0029] The present application provides a composite iridium crucible, comprising an iridium crucible body, a hafnium carbide isolation layer arranged on the outer surface of the iridium crucible body, and a rhenium support arranged on the outer surface of the hafnium carbide isolation layer.

[0030] Figure 1 The longitudinal cross-sectional structure schematic diagram of the composite iridium crucible provided by the present application is shown below, and will be described in detail below. Figure 1

[0031] In the present application, the thickness of the iridium crucible body is preferably 0.8-1.5mm, and can be 0.8mm, 1mm or 1.2mm; the present application does not have special requirements for the outer diameter and height of the iridium crucible body, and the skilled in the art can be used; in the specific embodiments of the present application, the outer diameter of the iridium crucible body can be 38-150mm, and the height can be 28-80mm. The thickness of the iridium crucible body in the present application is much lower than that of the pure iridium crucible with the same diameter in the art, which can greatly reduce the preparation cost and reduce the consumption of rare metal iridium.

[0032] ​In the present application, the thickness of the hafnium carbide isolation layer is preferably 0.2-0.6 mm, and can be 0.1 mm, 0.3 mm, 0.4 mm or 0.5 mm. The main role of the hafnium carbide isolation layer provided between the iridium crucible body and the rhenium support in the present application is a diffusion barrier, i.e. to prevent interdiffusion between rhenium and iridium elements. The strengthening effect of the rhenium layer on the iridium crucible is very obvious, but if rhenium and iridium are in direct contact, long-term use will cause serious diffusion between the two metal elements, which will change the properties of the iridium crucible material and adversely affect the recycling of iridium metal. Diffusion of metal elements in ceramics is very difficult, and the melting point of hafnium carbide is as high as 3890°C, which can effectively prevent the diffusion of metal elements. Test results show that at a temperature of 2000°C, after 100 hours of heat treatment, the rhenium / iridium diffusion layer reaches 200 µm; while a 0.2 mm hafnium carbide layer is prepared between rhenium / iridium, the total thickness of the diffusion layer of rhenium and iridium elements into hafnium carbide is only about 2 µm. According to the test results in the embodiments of the present application, within the use temperature range of 1720-2150°C, after long-term use, the thickness of the diffusion layer does not exceed 300 µm. The second role of the hafnium carbide isolation layer is to reduce the volatilization of iridium metal at high temperatures; bare iridium crucibles have a serious problem of volatilization of iridium metal, causing loss of iridium resources. Wrapping the outer surface of the iridium crucible with a hafnium carbide layer can reduce the volatilization of iridium metal by more than 50%. The third role of hafnium carbide is thermal barrier; the thermal conductivity of iridium metal is as high as 148 W·m -1 ·K -1 , which dissipates heat very quickly, causing excessive energy consumption during the drawing process, while the thermal conductivity of hafnium carbide is only 5.6 W·m -1 ·K -1 Therefore, the hafnium carbide isolation layer can provide a thermal barrier and heat preservation effect for the molten crystal, effectively reducing energy consumption.

[0033] In the present application, the thickness of the rhenium support is 1-3 mm, and can be 1 mm, 1.5 mm or 2 mm. Rhenium (Re) has a melting point as high as 3180°C, and has excellent comprehensive properties such as high high-temperature strength, good plasticity, good thermal shock resistance and good chemical inertness. By providing a rhenium support (i.e. a rhenium metal layer), the strength of the composite iridium crucible can be effectively improved. The results of the embodiments show that in the Re / HfC / Ir layered composite material, as the thickness of the Re layer increases, the strength of the composite material increases significantly, and the high-temperature strength increases more significantly. Compared with pure Ir material, after the Re layer is 1 mm, 2 mm and 3 mm thick, the high-temperature strength of the material is increased by 3.5 times, 4.8 times and 5.4 times, respectively. At the same time, the thermal expansion coefficients of rhenium, iridium and hafnium carbide are very close, and the three materials have good thermal matching, which can maintain the stability and integrity of the crucible under severe thermal shock in the use environment, and will not cause problems such as peeling of the coating, greatly improving the service life of the crucible.

[0034] The application further provides a preparation method of the composite iridium crucible. (1) depositing a hafnium carbide isolation layer on the outer surface of the iridium crucible body by using an on-site chlorination chemical vapor deposition method to obtain a hafnium carbide / iridium crucible; (2) performing degassing treatment on the hafnium carbide / iridium crucible to obtain a degassed hafnium carbide / iridium crucible; (3) depositing a rhenium support on the outer surface of the degassed hafnium carbide / iridium crucible by using the on-site chlorination chemical vapor deposition method to obtain the composite iridium crucible.

[0035] In the application, the hafnium carbide isolation layer is deposited on the outer surface of the iridium crucible body by using the on-site chlorination chemical vapor deposition method. Before the hafnium carbide isolation layer is deposited, the iridium crucible body is preferably sequentially subjected to acid washing, ultrasonic cleaning and drying. The application does not have special requirements for the specific operation conditions of the acid washing, ultrasonic cleaning and drying, and the operation conditions known to those skilled in the art can be used.

[0036] In the application, when the hafnium carbide isolation layer is deposited, the bottom of the iridium crucible body is placed upward, and a molybdenum sensing core matching the inner profile size of the iridium crucible body is placed inside. By adding the molybdenum sensing core, the application can improve the induction heating efficiency of the iridium crucible.

[0037] In the application, the conditions for depositing the hafnium carbide isolation layer by using the on-site chlorination chemical vapor deposition method preferably include: a chlorination temperature of 300-500℃, which can be 300℃, 350℃, 400℃ or 500℃; a deposition temperature of 1600-1700℃, which can be 1600℃, 1650℃ or 1700℃; a chlorine flow rate of 100-300mL / min, which can be 100mL / min, 150mL / min, 200mL / min or 300mL / min; a methane flow rate of 200-400mL / min, which can be 200mL / min, 250mL / min, 300mL / min or 400mL / min; a hydrogen flow rate of 1300-1500mL / min, which can be 1300mL / min, 1350mL / min, 1400mL / min or 1500mL / min; and a deposition chamber pressure of 700-900Pa, which can be 800Pa.

[0038] In the application, the device used for depositing the hafnium carbide isolation layer by using the on-site chlorination chemical vapor deposition method includes a chlorination chamber and a deposition chamber. A hafnium sheet is placed in the chlorination chamber. Chlorine gas is introduced into the chlorination chamber, and the hafnium sheet reacts with the chlorine gas to generate hafnium chloride, which enters the deposition chamber. Methane and hydrogen are introduced into the deposition chamber. The hafnium sheet is preferably subjected to ultrasonic cleaning and drying before use.

[0039] In a specific embodiment of the present application, the hafnium sheet after ultrasonic cleaning and drying is loaded into the chlorination chamber, the iridium crucible body after pickling, ultrasonic cleaning and drying is installed on the rotating platform of the deposition chamber (the bottom is upward), and is positioned in the middle of the induction coil, the molybdenum core is loaded in the inside of the iridium crucible body, after installation, the deposition system is sealed, and is vacuumed to a vacuum degree of 0.5 Pa, then the chlorination chamber and the iridium crucible body are heated to a set chlorination temperature and deposition temperature respectively, then hydrogen, chlorine and methane are introduced, and by adjusting the deposition process parameters and time, hafnium carbide isolation coating with different thicknesses is obtained on the outer surface of the iridium crucible.

[0040] The present application adopts on-site chlorination chemical vapor deposition method to prepare hafnium carbide isolation layer, adopts HfCl4-H2-CH4 reaction system, and a deposition principle diagram is shown in Figure 2 The raw material hafnium sheet in the chlorination chamber is formed into HfCl4 gas through on-site chlorination, HfCl4 is decomposed into Hf atoms under the action of reaction gas H2 at high temperature, Hf atoms and C atoms decomposed from CH4 occur chemical reaction and form HfC coating on the outer surface of the iridium crucible in situ. By controlling process parameters and deposition time, high-quality HfC isolation layer with different thicknesses can be obtained.

[0041] After obtaining the hafnium carbide / iridium crucible, the present application carries out degassing treatment on the hafnium carbide / iridium crucible to obtain a degassed hafnium carbide / iridium crucible. In the present application, the temperature of the degassing treatment is preferably 1100-1300℃, and can be specifically 1200℃, the holding time is preferably 1-3h, and can be specifically 2h, and the vacuum degree is preferably 1×10 -3 ~2×10 -3 Pa. Through the degassing treatment, the present application can avoid the problem that the deposited rhenium layer and the HfC coating interface are not tightly combined or even separated due to the escape of the gas adsorbed in the HfC coating.

[0042] After obtaining the degassed hafnium carbide / iridium crucible, the present application adopts on-site chlorination chemical vapor deposition method to deposit a rhenium support on the outer surface of the degassed hafnium carbide / iridium crucible to obtain the composite iridium crucible. In the present application, the conditions for depositing the rhenium support by on-site chlorination chemical vapor deposition method are preferably as follows: the chlorination temperature is 800-1000℃, and can be specifically 800℃, 850℃, 900℃ or 1000℃, the deposition temperature is 1400-1600℃, and can be specifically 1400℃, 1500℃ or 1600℃, the chlorine flow is 150-250mL / min, and can be specifically 150mL / min, 180mL / min, 220mL / min or 250mL / min, and the deposition chamber pressure is preferably 1400-1600Pa, and can be specifically 1500Pa.

[0043] In the present application, the device for depositing the rhenium support by on-site chlorination chemical vapor deposition method comprises a chlorination chamber and a deposition chamber, the rhenium block is placed in the chlorination chamber, and chlorine gas is introduced into the chlorination chamber, and the chlorination reaction of chlorine gas and the rhenium block generates rhenium chloride which enters the deposition chamber.

[0044] In the present application, the relative density of the rhenium block is preferably 55-65%, and specifically can be 60%. The present application uses semi-dense rhenium blocks to deposit rhenium supports, so that chlorine gas can easily enter the inside of the rhenium block and react with rhenium to generate rhenium chloride, thereby improving the reaction rate; if a rhenium metal with too high density is used, the chlorination reaction rate is slow, which will reduce the production efficiency, and if rhenium powder is used as raw material, the reaction is too fast and is prone to explosion.

[0045] In the present application, the preparation method of the rhenium block preferably comprises: pressing rhenium powder and then sintering to obtain a rhenium block; the pressure of the pressing is preferably 40-60 MPa, and specifically can be 50 MPa; the sintering temperature is preferably 1500-1600℃, the time is preferably 1-2 h, and the vacuum degree is preferably 1x10 -3 ~2x10 -3 Pa; the purity of the rhenium powder is preferably 99.99% In a specific embodiment of the present application, the rhenium block is placed in the chlorination chamber, the degassing treated hafnium carbide / iridium crucible is installed on the rotating platform of the deposition chamber (the bottom of the crucible faces upward), the molybdenum core matching the size of the inner profile of the crucible is loaded in the inside of the crucible, after the installation is completed, the deposition system is sealed and is extracted to a vacuum state with a vacuum degree of 0.5 Pa, then the chlorination chamber and the hafnium carbide / iridium crucible are heated to the set chlorination temperature and deposition temperature respectively, chlorine gas is introduced into the chlorination chamber to start the deposition of rhenium, and different thicknesses of rhenium supports are obtained by adjusting the deposition process parameters and time.

[0046] The deposition principle diagram of the rhenium support prepared by the on-site chlorination chemical vapor deposition method of the present application is shown in Figure 3 The raw material metal rhenium reacts with the introduced chlorine gas in the chlorination chamber to form ReCl5 gas, the ReCl5 gas undergoes thermal decomposition reaction on the surface of the hafnium carbide isolation layer at the deposition temperature to precipitate Re atoms, and gradually accumulates into a high-density rhenium support.

[0047] After the deposition of the rhenium support is completed, the present application preferably adopts a numerical control grinding machine to grind the outer surface of the composite iridium crucible to obtain the final product.

[0048] The present application also provides the application of the composite iridium crucible in the preparation of crystal materials. In the present application, the crystal material is preferably a high-melting-point crystal material, and the melting point of the high-melting-point crystal material is specifically above 1700℃, and preferably 1700-2150℃.

[0049] The technical solutions in the present application will be described clearly and completely below in combination with the embodiments in the present application. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without creative effort belong to the protection scope of the present application.

[0050] The preparation method of the rhenium block used in the following examples is as follows: rhenium powder with a purity of 99.99% is pressed into a circular sheet with a diameter of 10 mm and a thickness of 5 mm on an oil press at a pressing pressure of 50 MPa, and then sintered in a high-temperature tungsten wire furnace. The sintering process is as follows: the vacuum degree is 2×10 -3 Pa, the sintering temperature is 1500℃, and the sintering time is 1 h, so that a rhenium block raw material for deposition with a relative density of about 60% is obtained.

[0051] Example 1 A composite iridium crucible, the size of the inner layer iridium crucible body is Φ×h×d=38×28×0.8mm (Φ, h, d are the outer diameter, height and thickness of the iridium crucible body respectively), the thickness of the rhenium support, hafnium carbide isolation layer and iridium crucible body in the composite iridium crucible is 1.0mm, 0.2mm, 0.8mm respectively.

[0052] The preparation method of the composite iridium crucible is as follows: (1) 150g of hafnium sheet is loaded into a chlorination chamber, and the iridium crucible is installed on the rotating platform in the deposition chamber (the bottom of the crucible faces upwards) after acid washing, ultrasonic cleaning and drying treatment, and a molybdenum sensing core is placed inside the crucible. After installation is completed, the deposition system is sealed and pumped to a vacuum state of 0.5Pa.

[0053] (2) The chlorination chamber and the iridium crucible base are heated to 300℃ and 1600℃ respectively, and then hydrogen gas 1300mL / min, chlorine gas 100mL / min and methane 200mL / min are introduced, and the pressure in the deposition chamber is adjusted to 800Pa. Deposition is stopped after 4h of deposition, and the crucible sample is taken out after cooling.

[0054] (3) The obtained hafnium carbide coating is detected. The coating is uniform and dense in appearance, without cracks, pores and other defects. The coating thickness is 0.21mm, and the deposition rate is 52μm / h.

[0055] (4) The obtained hafnium carbide / iridium crucible is placed in a high vacuum furnace for degassing treatment. The degassing process is as follows: the heating temperature is 1200℃, the holding time is 2h, and the vacuum degree is (1~2)×10 -3 Pa.

[0056] (5) Put 300 g of rhenium block into the chlorination chamber, install the degassed hafnium carbide / iridium crucible on the rotating platform of the deposition chamber (the bottom of the crucible faces upward), and put a molybdenum core into the interior of the crucible. Seal the deposition system and evacuate to a vacuum state of 0.5 Pa.

[0057] (6) Heat the chlorination chamber and the crucible base to 800°C and 1400°C respectively, introduce 150 mL / min of chlorine into the chlorination chamber to start the deposition of rhenium, and adjust the pressure in the deposition chamber to 1500 Pa. Stop the deposition after 2.2 h of deposition.

[0058] (7) Perform relevant detection on the obtained rhenium layer. The rhenium layer is complete and dense, the thickness of the rhenium layer is 1.1 mm, the deposition rate of rhenium is 500 μm / h, and the deposition efficiency is 98%.

[0059] (8) Use a numerical control grinding machine to grind the outer surface of the rhenium layer of the composite iridium crucible to obtain a composite iridium crucible product that meets the design requirements.

[0060] Example 2 A composite iridium crucible, the outer dimensions of the inner iridium crucible body are Φ × h × d = 56 × 45 × 0.8 mm (the actual drawing of the iridium crucible body is shown in Figure 4 FIG. 1), and the thicknesses of the rhenium support body, the hafnium carbide isolation layer, and the iridium crucible body in the composite iridium crucible are 1.0 mm, 0.3 mm, and 0.8 mm, respectively.

[0061] The preparation method of the composite iridium crucible is as follows: (1) Put 200 g of hafnium sheet into the chlorination chamber, install the acid-washed, ultrasonically cleaned, and dried iridium crucible on the rotating platform of the deposition chamber (the bottom of the crucible faces upward), and put a molybdenum core into the interior of the crucible. After installation, seal the deposition system and evacuate to a vacuum state of 0.5 Pa.

[0062] (2) Heat the chlorination chamber and the iridium crucible base to 350°C and 1600°C respectively, then introduce hydrogen 1350 mL / min, chlorine 150 mL / min, and methane 250 mL / min, and adjust the pressure in the deposition chamber to 800 Pa. Stop the deposition after 5 h of deposition, and take out the crucible sample after cooling.

[0063] (3) Perform relevant detection on the obtained hafnium carbide coating. The coating is uniform and dense in appearance, and free of defects such as cracks and pores. The thickness of the coating is 0.31 mm, and the deposition rate is 62 μm / h.

[0064] (4) Put the obtained hafnium carbide / iridium crucible into a high-vacuum furnace for degassing treatment. The degassing process: heating temperature is 1200°C, holding time is 2 h, and vacuum degree is (1-2) × 10 -3 Pa.

[0065] (5) Put 400 g of rhenium block into the chlorination chamber, install the hafnium carbide / iridium crucible treated by degassing into the rotating platform of the deposition chamber (the bottom of the crucible faces upward), and put the molybdenum core into the interior of the crucible. Seal the deposition system and evacuate to a vacuum state with a vacuum degree of 0.5 Pa.

[0066] (6) Heat the chlorination chamber and the crucible base to 850℃ and 1400℃ respectively, introduce 180 mL / min of chlorine into the chlorination chamber to start the deposition of rhenium, and adjust the pressure in the deposition chamber to 1500 Pa. Stop the deposition after 2.1 h of deposition.

[0067] (7) Perform relevant detection on the obtained rhenium layer. The rhenium layer is complete and dense, the thickness of the rhenium layer is 1.1 mm, the deposition rate of rhenium is 524 μm / h, and the deposition efficiency is 98%.

[0068] (8) Use a numerical control grinding machine to grind the outer surface of the rhenium layer of the composite iridium crucible to obtain a composite iridium crucible product meeting the design requirements (the physical map of the obtained composite iridium crucible is shown in Figure 5

[0069] Example 3 A composite iridium crucible, the outer dimensions of the inner iridium crucible body are Φ×h×d=70×50×1, and the thicknesses of the rhenium support body, the hafnium carbide isolation layer and the iridium crucible body in the composite iridium crucible are 1.5 mm, 0.4 mm and 1.0 mm respectively.

[0070] The preparation method of the composite iridium crucible is as follows: (1) Put 300 g of hafnium sheet into the chlorination chamber, install the iridium crucible treated by acid washing, ultrasonic cleaning and drying into the rotating platform of the deposition chamber (the bottom of the crucible faces upward), and put the molybdenum core into the interior of the crucible. After installation, seal the deposition system and evacuate to a vacuum state with a vacuum degree of 0.5 Pa.

[0071] (2) Heat the chlorination chamber and the iridium crucible base to 400℃ and 1650℃ respectively, then introduce hydrogen 1400 mL / min, chlorine 200 mL / min and methane 300 mL / min, and adjust the pressure in the deposition chamber to 800 Pa. Stop the deposition after 6 h of deposition, and take out the crucible sample after cooling.

[0072] (3) Perform relevant detection on the obtained hafnium carbide coating. The coating is uniform and dense in appearance, and free of defects such as cracks and pores. The thickness of the coating is 0.42 mm, and the deposition rate is 70 μm / h.

[0073] (4) Put the obtained hafnium carbide / iridium crucible into a high vacuum furnace for degassing treatment. The degassing process: heating temperature is 1200℃, holding time is 2 h, and vacuum degree is (1~2)×10 -3 Pa.​

[0074] (5) Put 800 g of rhenium block into the chlorination chamber, install the hafnium carbide / iridium crucible treated by degassing into the rotating platform of the deposition chamber (the bottom of the crucible faces upward), and put the molybdenum core into the interior of the crucible. Seal the deposition system and extract it into a vacuum state with a vacuum degree of 0.5 Pa.

[0075] (6) Heat the chlorination chamber and the crucible substrate to 900°C and 1500°C respectively, and start depositing rhenium by introducing 220 mL / min of chlorine into the chlorination chamber, and adjust the pressure in the deposition chamber to 1500 Pa. Stop deposition after 3 h.

[0076] (7) Perform relevant detection on the obtained rhenium layer. The rhenium layer is complete and dense, the thickness of the rhenium layer is 1.7 mm, the deposition rate of rhenium is 567 μm / h, and the deposition efficiency is 98.5%.

[0077] (8) Use a numerical control grinding machine to grind the outer surface of the rhenium layer of the composite iridium crucible to obtain a composite iridium crucible product meeting the design requirements.

[0078] Example 4 A composite iridium crucible, the outer dimensions of the inner iridium crucible body are Φ×h×d=100×80×1.2 mm, and the thicknesses of the rhenium support body, the hafnium carbide isolation layer, and the iridium crucible body in the composite iridium crucible are 2.0 mm, 0.5 mm, and 1.2 mm respectively.

[0079] The preparation method of the composite iridium crucible is as follows: (1) Put 400 g of hafnium sheet into the chlorination chamber, install the iridium crucible treated by acid washing, ultrasonic cleaning, and drying into the rotating platform of the deposition chamber (the bottom of the crucible faces upward), and put the molybdenum core into the interior of the crucible. After installation, seal the deposition system and extract it into a vacuum state with a vacuum degree of 0.5 Pa.

[0080] (2) Heat the chlorination chamber and the iridium crucible substrate to 500°C and 1700°C respectively, then introduce hydrogen 1500 mL / min, chlorine 300 mL / min, and methane 400 mL / min, and adjust the pressure in the deposition chamber to 800 Pa. Stop deposition after 6.5 h, and take out the crucible sample after cooling.

[0081] (3) Perform relevant detection on the obtained hafnium carbide coating. The coating is uniform and dense in appearance, and has no defects such as cracks and pores. The thickness of the coating is 0.52 mm, and the deposition rate is 80 μm / h.

[0082] (4) Put the obtained hafnium carbide / iridium crucible into a high vacuum furnace for degassing treatment. Degassing process: heating temperature is 1200°C, holding time is 2 h, and vacuum degree is 1~2×10 -3 Pa.

[0083] (5) Put 1800 g of rhenium block into the chlorination chamber, install the degassed hafnium carbide / iridium crucible on the rotating platform of the deposition chamber (with the crucible bottom facing upwards), and put a molybdenum core into the crucible. Seal the deposition system and evacuate to a vacuum degree of 0.5 Pa.

[0084] (6) Heat the chlorination chamber and the crucible base to 1000℃ and 1600℃ respectively, and start depositing rhenium by introducing 250 mL / min of chlorine into the chlorination chamber, and adjust the pressure in the deposition chamber to 1500 Pa. Stop the deposition after 3.7 h.

[0085] (7) Perform relevant detection on the obtained rhenium layer. The rhenium layer is complete and dense, the thickness of the rhenium layer is 2.2 mm, the deposition rate of rhenium is 595 μm / h, and the deposition efficiency is 99%.

[0086] (8) Use a numerical control grinding machine to grind the outer surface of the rhenium layer of the composite iridium crucible to obtain a composite iridium crucible product that meets the design requirements.

[0087] Comparative Example 1 An iridium crucible with an outer size of Φ×h×d=38×28×1.5 mm was prepared by melting, processing and welding.

[0088] Comparative Example 2 An iridium crucible with an outer size of Φ×h×d=56×45×1.5 mm was prepared by melting, processing and welding.

[0089] Comparative Example 3 An iridium crucible with an outer size of Φ×h×d=70×50×2.0 mm was prepared by melting, processing and welding.

[0090] Comparative Example 4 An iridium crucible with an outer size of Φ×h×d=100×80×2.0 mm was prepared by melting, processing and welding.

[0091] Performance Test 1. Crucible weight The size, weight of the iridium crucible body used in the composite iridium crucible of Examples 1-4 and the conventional iridium crucible in Comparative Examples 1-4 were compared, and the weight reduction rate of iridium metal was calculated, and the results are shown in Table 1.

[0092] Table 1 Weight of iridium crucible in Examples 1-4 and Comparative Examples 1-4 and weight reduction effect

[0093] According to the data in Table 1, it can be seen that the cost of the composite iridium crucible prepared by the application is greatly reduced. The non-ferrous metal industry standard (YS / T 564-2009) of China stipulates that the thickness of the iridium crucible produced by the welding method is 1.5-2 mm, and the diameter is 38-150 mm. The thickness of the inner layer iridium crucible body used in the composite iridium crucible prepared by the application is 0.8-1.2 mm, compared with the pure iridium crucible produced by the existing welding method, the amount of iridium metal and the cost are reduced by 65-94%.

[0094] 2. Strength test In order to test the strength, Re, Ir and Re / HfC / Ir layered composite materials (using the preparation process of Example 1, only replacing the iridium crucible body therein with an iridium sheet) were prepared. In order to analyze the influence of the rhenium layer on the mechanical properties of the material, the thickness of the Ir layer in the layered composite material was fixed at 1 mm, the thickness of the HfC layer was 0.4 mm, and only the thickness of the Re layer was changed. The room temperature tensile strength and the high temperature tensile strength at 1600℃ of the material were tested, and the experimental data are shown in Table 2.

[0095] Table 2 Room temperature strength and high temperature strength at 1600℃ of Re, Ir and Re / HfC / Ir composite materials

[0096] According to the data in Table 2, it can be found that pure Re and pure Ir have the highest and lowest strength respectively. With the increase of the thickness of the Re layer, the strength of the composite material is obviously improved, especially the high temperature strength increases more significantly: compared with pure Ir material, after the Re layer of 1 mm, 2 mm and 3 mm is compounded, the high temperature strength is increased by 3.5 times, 4.8 times and 5.4 times respectively.

[0097] 3. Use effect The composite iridium crucibles in Examples 1-4 and the iridium crucibles in Comparative Examples 1-4 were applied to the drawing of a plurality of common high-melting-point crystals, and the use of the crucibles, the loss of iridium metal per furnace and the diffusion of metal elements (rhenium) in the hafnium carbide isolation layer were detected, and the specific results are shown in Table 3.

[0098] Table 3 Use of composite iridium crucibles in Examples 1-4 and iridium crucibles in Comparative Examples 1-4

[0099] From Table 3, it can be seen that: The composite iridium crucible prepared in Example 1 was used for the pulling of LaSrAlO4 crystal, and the service time was 11400h, while the service time of the iridium crucible described in Comparative Example 1 was 7440h, the service time of the composite iridium crucible of Example 1 was increased by 53% compared with the service time of the iridium crucible of Comparative Example 1; the single-furnace iridium metal loss of the composite iridium crucible of Example 1 was 0.2g, while the single-furnace loss of the iridium crucible of Comparative Example 1 was 0.5g, the single-furnace iridium loss of the composite iridium crucible of Example 1 was reduced by 60% compared with the iridium crucible of Comparative Example 1; the diffusion layer thickness of metal elements in hafnium carbide of the composite iridium crucible described in Example 1 was 150µm after 11400h of use, which was lower than the hafnium carbide isolation layer thickness of 210µm in the composite iridium crucible.

[0100] The composite iridium crucible prepared in Example 2 was used for the pulling of Nb:YAG crystal, and the service time was 9600h, while the service time of the iridium crucible described in Comparative Example 2 was 5700h, the service time of the composite iridium crucible of Example 2 was increased by 68% compared with the service time of the iridium crucible of Comparative Example 2; the single-furnace iridium metal loss of the composite iridium crucible of Example 2 was 1.2g, while the single-furnace loss of the iridium crucible of Comparative Example 2 was 2.5g, the single-furnace iridium loss of the composite iridium crucible of Example 2 was reduced by 52% compared with the iridium crucible of Comparative Example 2; the diffusion layer thickness of metal elements in hafnium carbide of the composite iridium crucible described in Example 2 was 220µm after 9600h of use, which was lower than the hafnium carbide isolation layer thickness of 310µm in the composite iridium crucible.

[0101] The composite iridium crucible prepared in Example 3 was used for the pulling of LaSrAlO4 and Yb:GdScO3 crystals, respectively, and the service time was 10800h and 4800h, respectively, while the service time of the iridium crucible described in Comparative Example 3 was 6600h and 3000h, respectively, when the same crystals as the composite iridium crucible of Example 3 were pulled, the service time of the composite iridium crucible of Example 3 was increased by 64% and 60%, respectively, compared with the service time of the iridium crucible of Comparative Example 3; the single-furnace iridium metal loss of the composite iridium crucible of Example 3 was 1g and 2g, respectively, when the LaSrAlO4 and Yb:GdScO3 crystals were pulled, while the single-furnace loss of the iridium crucible of Comparative Example 3 was 2g and 5g, respectively, the single-furnace iridium loss of the composite iridium crucible of Example 3 was reduced by 50% and 60%, respectively, compared with the iridium crucible of Comparative Example 3; the diffusion layer thickness of metal elements in hafnium carbide of the composite iridium crucible described in Example 3 was 165µm and 230µm, respectively, after 10800h and 4800h of use, which were both lower than the hafnium carbide isolation layer thickness of 420µm in the composite iridium crucible.

[0102] The composite iridium crucible prepared in Example 4 is used for drawing of LaAlO3, Al2O3 and Nd:YAG crystals respectively, and the service time is 4320h, 5328h and 8250h respectively, while the service time of the iridium crucible described in Comparative Example 4 is 2376h, 3024h and 5100h respectively when drawing the same crystals as the composite iridium crucible of Example 4, and the service time of the composite iridium crucible of Example 4 is increased by 82%, 76% and 62% respectively compared with the service time of the iridium crucible of Comparative Example 4; the single-furnace iridium metal loss of the composite iridium crucible of Example 4 is 5g, 3g and 3.5g respectively when drawing LaAlO3, Al2O3 and Nd:YAG crystals, while the single-furnace loss of the iridium crucible of Comparative Example 4 is 12g, 7g and 8g respectively, and the single-furnace iridium loss of the composite iridium crucible of Example 4 is reduced by 58%, 57% and 56% respectively compared with the iridium crucible of Comparative Example 4; after the composite iridium crucible of Example 4 is used for 4320h, 5328h and 8250h, the diffusion layer thickness of metal elements in hafnium carbide is 260µm, 265µm and 270µm respectively, which is lower than the hafnium carbide isolation layer thickness of 520µm in the composite iridium crucible.

[0103] In summary, the present application has the following advantages: (1) The service time of the composite iridium crucible provided by the present application is significantly longer than that of a pure iridium crucible. When drawing the same crystal and the same growth cycle, the service furnace times and service time of the composite iridium crucible are increased by 53~82% compared with the pure iridium crucible. Moreover, the pure iridium crucible is basically in a severely deformed or leaking state after use and needs to be reprocessed, while the composite iridium crucible is in a non-deformed or slightly deformed state, and in fact the composite iridium crucible has not reached its service limit and can still be used.

[0104] (2) The iridium metal loss of the composite iridium crucible is greatly reduced. When drawing the same crystal, the single-furnace iridium metal loss of the composite iridium crucible is reduced by 50~60% compared with the pure iridium crucible with the same diameter under the condition of the same crystal growth cycle.

[0105] (3) Within the crystal growth temperature range of 1720~2150℃, the diffusion layer thickness of iridium and rhenium elements in hafnium carbide does not exceed 300µm after long-term use, and the hafnium carbide isolation layer can effectively prevent the diffusion of metal elements between the outer rhenium support body and the inner iridium crucible, which is conducive to the normal recovery and reprocessing of iridium metal in the composite crucible.

[0106] In summary, the composite iridium crucible provided by the application has the performance characteristics of high strength, resistance to thermal cycle impact and long service life. At the same time, the thickness of the iridium crucible body in the composite iridium crucible is much lower than that of a pure iridium crucible with the same diameter, the outer layer of hafnium carbide of the crucible can effectively prevent the volatilization of iridium metal, greatly reducing the cost of the crucible, the low thermal conductivity of the hafnium carbide has a good heat preservation effect on the crystal solution, and the energy consumption in the crystal preparation process can be reduced. In addition, the production efficiency of the crucible is significantly improved through the improvement of the preparation process.

[0107] The above only describes the preferred embodiments of the application, and it should be pointed out that for ordinary skilled persons in the art, several improvements and refinements can be made without departing from the principles of the application, and these improvements and refinements should also be considered as the protection scope of the application.

Claims

1. A composite iridium crucible, characterized in that, It includes an iridium crucible body, a hafnium carbide isolation layer disposed on the outer surface of the iridium crucible body, and a rhenium support disposed on the outer surface of the hafnium carbide isolation layer.

2. The composite iridium crucible according to claim 1, characterized in that, The thickness of the iridium crucible body is 0.8~1.5mm; the thickness of the hafnium carbide isolation layer is 0.2~0.6mm; and the thickness of the rhenium support is 1~3mm.

3. The method for preparing the composite iridium crucible according to claim 1 or 2, characterized in that, Includes the following steps: (1) A hafnium carbide isolation layer was deposited on the outer surface of the iridium crucible body by on-site chlorination chemical vapor deposition to obtain a hafnium carbide / iridium crucible; (2) The hafnium carbide / iridium crucible is degassed to obtain a degassed hafnium carbide / iridium crucible; (3) A rhenium support is deposited on the outer surface of the degassed hafnium carbide / iridium crucible by on-site chlorination chemical vapor deposition to obtain the composite iridium crucible.

4. The preparation method according to claim 3, characterized in that, When depositing the hafnium carbide isolation layer or rhenium support, the bottom of the iridium crucible body or the degassed hafnium carbide / iridium crucible is placed upwards, and a sensing molybdenum core that matches the inner surface size of the iridium crucible body is placed inside.

5. The preparation method according to claim 3, characterized in that, The conditions for depositing the hafnium carbide isolation layer by on-site chlorination chemical vapor deposition in step (1) include: chlorination temperature of 300~500℃, deposition temperature of 1600~1700℃, chlorine flow rate of 100~300mL / min, methane flow rate of 200~400mL / min, hydrogen flow rate of 1300~1500mL / min, and deposition chamber pressure of 700~900Pa; The apparatus used for depositing the hafnium carbide isolation layer by on-site chlorination chemical vapor deposition includes a chlorination chamber and a deposition chamber. Hafnium plates are placed in the chlorination chamber. Chlorine gas is introduced into the chlorination chamber, and hafnium chloride generated by the chlorination reaction between the chlorine gas and the hafnium plates enters the deposition chamber. Methane and hydrogen gas are introduced into the deposition chamber.

6. The preparation method according to claim 3, characterized in that, The degassing treatment is performed at a temperature of 1100~1300℃, with a holding time of 1~3 hours and a vacuum degree of 1×10⁻⁶. -3 ~2×10 -3 Pa.

7. The preparation method according to claim 3, characterized in that, The conditions for depositing the rhenium support by on-site chlorination chemical vapor deposition in step (3) include: chlorination temperature of 800~1000℃, deposition temperature of 1400~1600℃, chlorine flow rate of 150~250mL / min, and deposition chamber pressure of 1400~1600Pa; The apparatus used for depositing the rhenium support by on-site chlorination chemical vapor deposition includes a chlorination chamber and a deposition chamber. A rhenium block is placed in the chlorination chamber, and chlorine gas is introduced into the chlorination chamber. The chlorination gas and the rhenium block undergo a chlorination reaction to generate rhenium chloride, which enters the deposition chamber.

8. The preparation method according to claim 7, characterized in that, The relative density of the rhenium block is 55-65%.

9. The preparation method according to claim 7 or 8, characterized in that, The method for preparing the rhenium block includes: pressing rhenium powder and then sintering it to obtain a rhenium block; the pressing pressure is 40~60MPa, the sintering temperature is 1500~1600℃, the sintering time is 1~2h, and the vacuum degree is 1×10⁻⁶. -3 ~2×10 -3 Pa.

10. The application of the composite iridium crucible according to claim 1 or 2, or the composite iridium crucible according to any one of claims 3 to 9, in the preparation of crystalline materials.

Images