Process for the preparation of multispectral zinc sulfide crystals

Abstract

A preparation process of a multi-spectrum zinc sulfide crystal comprises the following steps: S1, surface processing treatment of a native CVD zinc sulfide crystal material; S2, ultrasonic cleaning; S3, magnetron sputtering Pd film layer, comprising the following sub-steps: S31, loading the cleaned zinc sulfide crystal material into a sputtering chamber; S32, installing a metal Pd target material; S33, vacuumizing the sputtering chamber; S34, setting working conditions: passing argon gas, argon gas flow being 20-200 sccm, sputtering gas pressure being 0.1-1.0 Pa, sputtering temperature being normal temperature; S35, sputtering Pd film layer, thickness being 100-500 nm, only the bottom installed surface is not plated, and the rest surfaces are plated; S36, after the first plating, making the sputtering chamber reach the external atmospheric pressure, and taking out; S37, loading the taken-out zinc sulfide crystal material into the sputtering chamber, the surface not plated in step S35 being taken as a surface to be plated, and repeating the sub-steps S33, S35 and S36, so as to plate Pd film layer on the whole external surface; S4, hot isostatic pressing treatment; S5, optical cold processing, and removing the Pd film layer of each surface.

Description

Technical Field

[0001] This disclosure relates to the field of crystal materials technology, and more specifically to a preparation process for multispectral zinc sulfide crystals. Background Technology

[0002] Multispectral zinc sulfide crystal is obtained by preparing standard ZnS through chemical vapor deposition (CVD) and then hot isostatic pressing (HIP). It is currently the only infrared optical material besides diamond whose transmission band covers the entire spectrum from visible light to long-wave infrared (8-12 μm) and even the microwave band. Multispectral zinc sulfide is a chemically inert material with high purity, insolubility in water, moderate density, and ease of processing, making it widely used in the fabrication of infrared windows, radomes, and infrared optical components. Like zinc selenide, multispectral zinc sulfide is also a material with uniform and consistent refractive index, exhibiting excellent image transmission performance. Compared to zinc selenide, multispectral zinc sulfide has higher hardness, higher fracture strength, and stronger resistance to harsh environments. Multispectral zinc sulfide materials demonstrate excellent wide-band transmission performance in both military and civilian applications, finding widespread use in high-speed missiles, aerospace, intelligent security, manufacturing, forest fire prevention, and healthcare.

[0003] Currently, the method used to prepare multispectral zinc sulfide involves wrapping CVD-prepared zinc sulfide crystals in metal foil, then placing them in a hot isostatic pressing (HIP) furnace under high temperature and pressure to obtain clear, transparent multispectral zinc sulfide. However, this HIP method results in hazy areas of varying widths around the edges of the multispectral zinc sulfide crystals (when illuminated in a dark room, these hazy areas appear foggy at the edges). During processing, these hazy areas need to be cut away, reducing the utilization rate of the multispectral zinc sulfide crystals. Furthermore, the metal foil wrapping method for zinc sulfide crystals suffers from poor stability and a high rate of defective products (i.e., a low yield). Summary of the Invention

[0004] In view of the problems existing in the background art, one object of this disclosure is to provide a preparation process for multispectral zinc sulfide crystals, wherein the prepared multispectral zinc sulfide crystal material has no haze layer at the edge and no haze layer overall.

[0005] Another objective of this disclosure is to provide a process for preparing multispectral zinc sulfide crystals, which can improve the utilization rate of multispectral zinc sulfide crystals, shorten processing time, increase production efficiency, and reduce costs.

[0006] Another object of this disclosure is to provide a process for preparing multispectral zinc sulfide crystals, which is beneficial for processing irregularly shaped zinc sulfide crystal materials.

[0007] Another objective of this disclosure is to provide a preparation process for multispectral zinc sulfide crystals, which is beneficial to the stability of hot isostatic pressing and improves the yield.

[0008] Therefore, a process for preparing multispectral zinc sulfide crystals includes the following steps: S1, surface processing of the virgin CVD zinc sulfide crystal material to control the surface roughness of the virgin CVD zinc sulfide crystal material to Ra = 0.1-1.5 μm; S2, ultrasonic cleaning; S3, magnetron sputtering deposition of a Pd film layer, including the following sub-steps: S31, loading the cleaned virgin CVD zinc sulfide crystal material from step S2 into the sputtering chamber of the magnetron sputtering coating machine; S32, installing a Pd metal target into the sputtering chamber; S33, evacuating the sputtering chamber to an absolute pressure of 1.0 × 10⁻⁶. -3 S34, Set operating conditions: Introduce argon gas at a flow rate of 20-200 sccm, sputtering pressure of 0.1-1.0 Pa, and sputtering temperature at room temperature. S35, Sputter a Pd film onto the surface of the native CVD zinc sulfide crystal material for the first time. The thickness of the sputtered Pd film is 100-500 nm. At this point, only the bottom mounting surface of the native CVD zinc sulfide crystal material is not coated, while the remaining surfaces are coated. S36, After the first coating is completed, bring the sputtering chamber to atmospheric pressure and remove the native CVD zinc sulfide crystal material with the first sputtered Pd film coating. Avoid contamination of the native CVD zinc sulfide crystal material during removal. S37, The coated surface of the first sputtered Pd film-coated virgin CVD zinc sulfide crystal material is placed into the sputtering chamber of the magnetron sputtering coating machine. The uncoated surface in step S35 is used as the coating surface facing the target material. Sub-steps S33, S35, and S36 are repeated to obtain the virgin CVD zinc sulfide crystal material with a Pd film coating on the entire outer surface. S4, Hot isostatic pressing (HIP) treatment is performed to obtain the crystal material with a Pd film coating on the entire outer surface after HIP treatment. S5, Optical cold processing is performed to remove the Pd film on each side of the crystal material with a Pd film coating on the entire outer surface after HIP treatment to obtain a multispectral zinc sulfide crystal material. The obtained multispectral zinc sulfide crystal material has no haze at the edges and no haze overall.

[0009] The beneficial effects of this disclosure are as follows.

[0010] According to the preparation process of multispectral zinc sulfide crystals disclosed herein, through steps S1 to S5, the prepared multispectral zinc sulfide crystal material has no haze layer at the edge and no haze layer overall.

[0011] In the preparation process of the multispectral zinc sulfide crystal according to the present disclosure, since the prepared multispectral zinc sulfide crystal material has no haze layer at the edge and no haze layer overall, there is no need to cut off the haze layer area at the four edges as mentioned in the background art during the processing of multispectral zinc sulfide crystal. Therefore, the utilization rate of multispectral zinc sulfide crystal can be improved, the processing time can be shortened, the production efficiency can be improved, and the cost can be reduced.

[0012] In the preparation process of multispectral zinc sulfide crystals according to this disclosure, since step S3 uses magnetron sputtering to deposit a Pd film layer on the entire outer surface of the original CVD zinc sulfide crystal material, the Pd film layer deposited on the entire outer surface is integrally attached to the original CVD zinc sulfide crystal material without gaps. This is superior to the state in the prior art where the separate metal foil wrapped around the CVD zinc sulfide crystal is in close contact with it. The contact between the Pd film layer deposited on the entire outer surface (whether it is the periphery or the area outside the periphery) and the original CVD zinc sulfide crystal material is more uniform, which is more conducive to processing irregularly shaped original CVD zinc sulfide crystal materials (e.g., spherical covers). Thus, in the hot isostatic pressing treatment in step S4, the recrystallization promotion effect on the zinc sulfide crystal material is more uniform, which is conducive to improving optical performance, including optical transmittance.

[0013] In the preparation process of multispectral zinc sulfide crystals according to this disclosure, the thickness of the sputtered Pd film in step S3 is 100-500 nm. In the prior art, it is difficult to achieve this thickness in actual production using metal foils for wrapping. This difficulty lies not only in the metal foil material itself but also in the extremely challenging wrapping operation. In other words, compared to the wrapped metal foils in the prior art, the sputtered Pd film in the preparation process of multispectral zinc sulfide crystals according to this disclosure completely wraps the virgin CVD zinc sulfide crystal material with a thinner Pd film, and the wrapping operation is simpler, more convenient, and more effective. Furthermore, this thinner wrapping is more conducive to the effective application of temperature and pressure during hot isostatic pressing (HIP), further shortens the HIP processing time, improves the stability of HIP processing, and increases the yield rate.

[0014] In the preparation process of multispectral zinc sulfide crystals according to the present disclosure, the surface processing in step S1 helps the adhesion of the Pd film and improves the bonding tightness between the Pd film and the native CVD zinc sulfide crystal material. The Pd film in step S3 is prepared by magnetron sputtering, which further enhances the bonding tightness between the Pd film and the native CVD zinc sulfide crystal material. Attached Figure Description

[0015] Figure 1 This is a photograph of the multispectral zinc sulfide crystal material prepared in Example 1.

[0016] Figure 2 This is a transmittance curve of the multispectral zinc sulfide crystal material prepared in Example 1 in the 0.4-0.8 μm band.

[0017] Figure 3 This is a transmittance curve of the multispectral zinc sulfide crystal material prepared in Example 1 in the 8-12μm band.

[0018] Figure 4 This is a photograph of the multispectral zinc sulfide crystal material prepared in Example 2.

[0019] Figure 5 This is a transmittance curve of the multispectral zinc sulfide crystal material prepared in Example 2 in the 0.4-0.8 μm band.

[0020] Figure 6 This is a transmittance curve of the multispectral zinc sulfide crystal material prepared in Example 2 in the 8-12μm band.

[0021] Figure 7 This is a photograph of the multispectral zinc sulfide crystal material prepared in Example 3.

[0022] Figure 8 This is a transmittance curve of the multispectral zinc sulfide crystal material prepared in Example 3 in the 0.4-0.8 μm band.

[0023] Figure 9 This is a transmittance curve of the multispectral zinc sulfide crystal material prepared in Example 3 in the 8-12μm band.

[0024] Figure 10 This is a photograph of the multispectral zinc sulfide crystal material prepared in Example 4.

[0025] Figure 11 This is a transmittance curve of the multispectral zinc sulfide crystal material prepared in Example 4 in the 0.4-0.8 μm band.

[0026] Figure 12 This is a transmittance curve of the multispectral zinc sulfide crystal material prepared in Example 4 in the 8-12μm band. Detailed Implementation

[0027] It will be understood that the disclosed embodiments are merely examples of this disclosure, which can be implemented in various forms. Therefore, the specific details disclosed herein should not be construed as limiting, but are intended only as the basis for the claims and as an illustrative basis to teach those skilled in the art how to implement this disclosure in various ways.

[0028] [Preparation process of multispectral zinc sulfide crystals]

[0029] The preparation process of multispectral zinc sulfide crystals according to this disclosure includes the following steps:

[0030] S1, Surface processing of virgin CVD zinc sulfide crystal material to control the surface roughness of virgin CVD zinc sulfide crystal material within Ra = 0.1-1.5 μm;

[0031] S2, ultrasonic cleaning;

[0032] S3, magnetron sputtering deposition of Pd film, including sub-steps:

[0033] S31, The virgin CVD zinc sulfide crystal material cleaned in step S2 is loaded into the sputtering chamber of the magnetron sputtering coating machine.

[0034] S32, install the Pd metal target into the sputtering chamber;

[0035] S33, evacuate the sputtering chamber to an absolute pressure of 1.0 × 10⁻⁶. -3 Pa;

[0036] S34, set the working conditions: argon gas is introduced, the argon gas flow rate is 20-200 sccm, the sputtering gas pressure is 0.1-1.0 Pa, and the sputtering temperature is room temperature;

[0037] S35, a Pd film is sputtered onto the surface of the native CVD zinc sulfide crystal material for the first time. The thickness of the sputtered Pd film is 100-500nm. At this time, only the bottom mounting surface of the native CVD zinc sulfide crystal material is not coated with a film, while the other surfaces of the native CVD zinc sulfide crystal material are coated with a film.

[0038] S36. After the first coating is completed, the sputtering chamber is brought to the outside atmospheric pressure, and the original CVD zinc sulfide crystal material with the first sputtered Pd film is removed. During the removal process, the original CVD zinc sulfide crystal material is protected from contamination.

[0039] S37, the coated surface of the first sputtered Pd film layer of the original CVD zinc sulfide crystal material is put into the sputtering chamber of the magnetron sputtering coating machine. The surface without film layer in step S35 is used as the coating surface facing the target material. Sub-steps S33, S35 and S36 are repeated to obtain the original CVD zinc sulfide crystal material with Pd film layer on the entire outer surface.

[0040] S4, hot isostatic pressing, to obtain a crystalline material with a Pd film coating on the entire outer surface after hot isostatic pressing.

[0041] S5, optical cold processing, removes the Pd film layer on each side of the crystal material with Pd film layer on the entire outer surface after hot isostatic pressing, to obtain multispectral zinc sulfide crystal material. The obtained multispectral zinc sulfide crystal material has no haze layer at the edges and no haze layer overall.

[0042] In the preparation process of multispectral zinc sulfide crystals according to the present disclosure, through steps S1 to S5, the prepared multispectral zinc sulfide crystal material has no haze layer at the edge and no haze layer overall.

[0043] In the preparation process of the multispectral zinc sulfide crystal according to the present disclosure, since the prepared multispectral zinc sulfide crystal material has no haze layer at the edge and no haze layer overall, there is no need to cut off the haze layer area at the four edges as mentioned in the background art during the processing of multispectral zinc sulfide crystal. Therefore, the utilization rate of multispectral zinc sulfide crystal can be improved, the processing time can be shortened, the production efficiency can be improved, and the cost can be reduced.

[0044] In the preparation process of multispectral zinc sulfide crystals according to this disclosure, since step S3 uses magnetron sputtering to deposit a Pd film layer on the entire outer surface of the original CVD zinc sulfide crystal material, the Pd film layer deposited on the entire outer surface is integrally attached to the original CVD zinc sulfide crystal material without gaps. This is superior to the state in the prior art where the separate metal foil wrapped around the CVD zinc sulfide crystal is in close contact with it. The contact between the Pd film layer deposited on the entire outer surface (whether it is the periphery or the area outside the periphery) and the original CVD zinc sulfide crystal material is more uniform, which is more conducive to processing irregularly shaped original CVD zinc sulfide crystal materials (e.g., spherical covers). Thus, in the hot isostatic pressing treatment in step S4, the recrystallization promotion effect on the zinc sulfide crystal material is more uniform, which is conducive to improving optical performance, including optical transmittance.

[0045] In the preparation process of multispectral zinc sulfide crystals according to this disclosure, the thickness of the sputtered Pd film in step S3 is 100-500 nm. In the prior art, it is difficult to achieve this thickness in actual production using metal foils for wrapping. This difficulty lies not only in the metal foil material itself but also in the extremely challenging wrapping operation. In other words, compared to the wrapped metal foils in the prior art, the sputtered Pd film in the preparation process of multispectral zinc sulfide crystals according to this disclosure completely wraps the virgin CVD zinc sulfide crystal material with a thinner Pd film, and the wrapping operation is simpler, more convenient, and more effective. Furthermore, this thinner wrapping is more conducive to the effective application of temperature and pressure during hot isostatic pressing (HIP), further shortens the HIP processing time, improves the stability of HIP processing, and increases the yield rate.

[0046] In the preparation process of multispectral zinc sulfide crystals according to the present disclosure, the surface processing in step S1 helps the adhesion of the Pd film and improves the bonding tightness between the Pd film and the native CVD zinc sulfide crystal material. The Pd film in step S3 is prepared by magnetron sputtering, which further enhances the bonding tightness between the Pd film and the native CVD zinc sulfide crystal material.

[0047] In one example, in step S1, primary zinc sulfide crystal material is grown using CVD. The CVD process for growing primary zinc sulfide crystal is as follows: ZnS crystal material is grown in a chemical vapor deposition furnace using a Zn-H2S reaction system. The deposition apparatus in the furnace mainly includes a crucible, a deposition chamber, and a discharge box, all made of isostatically pressed graphite. The crucible is responsible for melting and evaporating the raw material solid zinc at a heating temperature of 600°C. ZnS is grown in the deposition chamber. The deposition chamber and the crucible are connected by a partition with internally designed gas nozzles. Hydrogen sulfide gas and the molten and evaporated zinc in the crucible are used for gas deposition. Zinc vapor is injected into the deposition chamber via a nozzle through a carrier argon gas path. It is then transported to the surface of the graphite mold substrate to undergo a chemical reaction to generate ZnS. The deposition chamber is heated to 660℃. Unreacted gaseous reactants, hydrogen byproducts, and zinc sulfide particles that fail to deposit effectively are carried into the unloading box along with the carrier gas. The gaseous substances then enter the tail gas treatment system. After the reaction is completed, the hydrogen sulfide supply is stopped, the crucible heating is stopped, and the temperature is allowed to drop naturally. The deposition chamber temperature is reduced to room temperature at a rate of 0.1-0.5℃ / min. The ZnS crystal material is then obtained from the furnace.

[0048] For example, in step S1, the surface processing is performed by grinding. Grinding is performed by using a grinding machine to grind the surface of the original CVD zinc sulfide crystal material to a surface roughness Ra of 0.1-1.5 μm. The abrasive is 600-mesh diamond powder purchased from Zhengzhou Xinli Wear-resistant Materials Co., Ltd.

[0049] In step S1, the native CVD zinc sulfide crystal material can be, but is not limited to, flat plate material or spherical cover.

[0050] In one example, in step S2, ultrasonic cleaning is performed using an eight-tank ultrasonic cleaner. The virgin CVD zinc sulfide crystal material is placed into the tanks in sequence from one to eight, with the entire process lasting at least 20 minutes. The functions of each tank are as follows: Tank 1: Ultrasonic washing, using undiluted polishing cleaning agent from the Xinmingyang brand at room temperature; Tank 2: Ultrasonic washing, using optical glass cleaning agent from the Feinaier brand, mixed with pure water to prepare a 5%-7% cleaning solution, at a cleaning temperature of 60°C; Tank 3: Ultrasonic washing, using the same cleaning solution as Tank 2, at a cleaning temperature of 50°C; Tank 4: Ultrasonic washing with pure water at room temperature; Tank 5: Ultrasonic washing with pure water at room temperature; Tank 6: Ultrasonic washing with pure water at room temperature; Tank 7: Slow air dehydration; Tank 8: Hot air drying at a drying temperature of 50°C. Furthermore, the entire process lasts 30-40 minutes.

[0051] In one example, in sub-step S32, the purity of the Pd metal target is not less than 4N.

[0052] In one example, in sub-step S33, the sputtering chamber is first roughly evacuated by using a mechanical pump to evacuate it to 5 Pa, and then finely evacuated to an absolute pressure of 1.0 × 10⁻⁶ Pa using a molecular pump. -3 Pa.

[0053] In one example, in sub-step S34, the argon flow rate is controlled by a mass flow controller (MFC).

[0054] In one example, in sub-step S35, the thickness of the sputtered Pd film is monitored using a crystal oscillator method, which utilizes the corresponding crystal oscillators of multiple crystal oscillators of a crystal controller, with a crystal oscillator frequency of not less than 5.99MHz.

[0055] In one example, in sub-step S36, after the coating is completed, the power supply of the magnetron sputtering coating machine is turned off, argon gas is slowly introduced, and the gas inlet rate is controlled by the gas valve of the magnetron sputtering coating machine so that the sputtering chamber of the magnetron sputtering coating machine returns to the outside atmospheric pressure in a time of not less than 20 minutes.

[0056] In one example, the hot isostatic pressing process in step S4 includes the following sub-steps:

[0057] S41, Install the crystal material with Pd film coating on the entire outer surface completed in step S3 into the hot isostatic pressing furnace cavity;

[0058] S42, furnace cleaning and annealing;

[0059] S43, fill the furnace cavity with argon gas at a cold state of 30-60MPa, and then start heating to the target temperature of 900-1050℃ at a heating rate of 0.5-5℃ / min. During the heating process, supplement argon gas to make the hot isostatic pressure furnace cavity reach the target pressure of 100-200MPa.

[0060] S44, maintain target temperature and pressure for 10-120 hours;

[0061] S45, after the heat preservation is completed, cool down to room temperature at a rate of ≤5℃ / min;

[0062] S46, reduce pressure to atmospheric pressure, remove from furnace, and take out the product.

[0063] Furthermore, for example, in sub-step 42, after the furnace is closed, a vacuum is drawn and then argon gas with a purity of not less than 5N is used to fill the furnace. The vacuum-filling and filling process is repeated more than 5 times to clean the furnace.

[0064] Furthermore, for example, in sub-step 43, the purity of argon gas is not less than 5N.

[0065] In one example, in step S5, the optical cold working employs a surface grinding process. For instance, the grinding is performed using a grinding machine, and the abrasive is 600-mesh diamond powder commercially available from Zhengzhou Xinli Wear-Resistant Materials Co., Ltd.

[0066] In one example, the preparation process of the multispectral zinc sulfide crystal according to this disclosure further includes: step S6, preparing a test sample of the multispectral zinc sulfide crystal material and performing optical performance testing. The test results are as follows: the average transmittance in the 0.4-0.8 μm band is 69.95-70.72%, and the average transmittance in the 8-12 μm band is 70.73-75.0%. Further, the test results also show that the volume absorption coefficient is 0.10-0.13 cm⁻¹. -1 The temperature coefficient of refractive index in the 10.6 μm band is (31-36)×10. -6 / ℃, the refractive index uniformity in the 0.6328μm band is (15-18)×10 -6 .

[0067] [test]

[0068] Example 1

[0069] The preparation process of the multispectral zinc sulfide crystals in Example 1 adopts the following steps:

[0070] S1, Surface processing of the native CVD zinc sulfide crystal material to control the surface roughness of the native CVD zinc sulfide crystal material at Ra = 1.2 μm.

[0071] in,

[0072] Primary zinc sulfide crystals were grown using CVD (chemical vapor deposition). The process involved growing ZnS crystals in a chemical vapor deposition furnace using a Zn-H2S reaction system. The deposition apparatus within the furnace mainly consisted of a crucible, a deposition chamber, and a discharge box, all made of isostatically pressed graphite. The crucible was responsible for melting and evaporating the raw material solid zinc at a heating temperature of 600℃, while ZnS grew in the deposition chamber. The deposition chamber and the crucible were connected by a partition with internally designed gas nozzles. Hydrogen sulfide gas and the molten zinc vapor evaporated in the crucible were injected into the deposition chamber via argon gas through their respective gas paths. A chemical reaction occurs on the surface of the graphite mold substrate to generate ZnS; the heating temperature of the deposition chamber is 660℃; unreacted gaseous reactants, reaction byproduct hydrogen, and zinc sulfide particles that failed to be deposited effectively enter the unloading box with the carrier gas, and the gaseous substances then enter the tail gas treatment system; after the reaction is completed, the hydrogen sulfide supply is stopped, the crucible heating is stopped, and it is allowed to cool down naturally; the temperature of the deposition chamber is reduced to room temperature at a cooling rate of 0.3℃ / min; ZnS crystal material is obtained after exiting the furnace, and the blank material (i.e., the obtained ZnS crystal material) is selected and processed into flat plates with a specification of 200mm×200mm×22mm;

[0073] The surface treatment is grinding, which involves using a grinding machine to grind the surface of the original CVD zinc sulfide crystal material to a surface roughness of Ra1.2μm. The abrasive used is 600-mesh diamond powder purchased from Zhengzhou Xinli Wear-resistant Materials Co., Ltd.

[0074] S2, ultrasonic cleaning.

[0075] The ultrasonic cleaning process utilizes an eight-tank ultrasonic cleaner, where virgin CVD zinc sulfide crystal materials are immersed in the tanks in sequence from one to eight, with the entire process lasting 35 minutes. The functions of each tank are as follows: Tank 1: Ultrasonic cleaning, using undiluted grinding and polishing cleaning agent from the Xinmingyang brand at room temperature; Tank 2: Ultrasonic cleaning, using optical glass cleaning agent from the Feinaier brand, prepared as a 6% cleaning solution with pure water at a cleaning temperature of 60℃; Tank 3: ...

[0076] Ultrasonic washing, using the same cleaning solution as tank two, cleaning temperature 50℃; tank four: ultrasonic washing with room temperature pure water; tank five: ultrasonic washing with room temperature pure water; tank six: ultrasonic washing with room temperature pure water; tank seven: slow washing.

[0077] Air dehydration, tank eight: hot air drying, drying temperature 50℃;

[0078] S3, magnetron sputtering deposition of Pd film, using the following sub-steps:

[0079] S31, The virgin CVD zinc sulfide crystal material cleaned in step S2 is loaded into the sputtering chamber of the magnetron sputtering coating machine.

[0080] S32, Install a Pd metal target into the sputtering chamber. The purity of the Pd metal target is 4N.

[0081] S33, Evacuate the sputtering chamber. First, perform a rough evacuation of the sputtering chamber using a mechanical pump to evacuate it to 5 Pa, then use a molecular pump to finely evacuate it to an absolute pressure of 1.0 × 10⁻⁶ Pa. -3 Pa;

[0082] S34, Setting operating conditions: Argon gas is introduced, argon gas flow rate is 50 sccm, sputtering pressure is 0.5 Pa, sputtering temperature is room temperature, and argon gas flow rate is controlled by a mass flow controller (MFC).

[0083] control;

[0084] S35, a Pd film is sputtered onto the surface of the native CVD zinc sulfide crystal material for the first time. The thickness of the sputtered Pd film is 200 nm. At this time, only the bottom mounting surface of the zinc sulfide crystal material is not coated with a film, while the other surfaces of the zinc sulfide crystal material are coated with a film. The thickness of the sputtered Pd film is monitored by using the crystal oscillator method with the corresponding crystal oscillators of multiple crystal oscillators of the crystal controller. The crystal oscillator frequency is not less than 5.99 MHz.

[0085] S36. After the first coating is completed, turn off the power of the magnetron sputtering coating machine, slowly fill it with argon gas, and use the gas valve of the magnetron sputtering coating machine to control the gas inlet rate so that the sputtering chamber of the magnetron sputtering coating machine can be restored to the outside atmospheric pressure in 20 minutes. Take out the crystal material with the first sputtered Pd film, and avoid contamination of the crystal material during the removal process.

[0086] S37, the coated surface of the crystal material with the first sputtered Pd film layer is put into the sputtering chamber of the magnetron sputtering coating machine. The surface without film layer in step S35 is used as the coating surface and faces the target material. Sub-steps S33, S35 and S36 are repeated to coat the coating surface with Pd film layer, so as to obtain crystal material with Pd film layer on the entire outer surface.

[0087] S4, hot isostatic pressing, to obtain a crystalline material with a Pd film coating on the entire outer surface after hot isostatic pressing.

[0088] Hot isostatic pressing (HIP) involves the following sub-steps:

[0089] S41, Install the crystal material with Pd film coating on the entire outer surface completed in step S3 into the hot isostatic pressing furnace cavity;

[0090] S42, Furnace cleaning after merging: After merging the furnace, vacuum it and then fill it with argon gas of 5N purity. Repeat the vacuuming and filling process more than 5 times to clean the furnace.

[0091] S43, fill the furnace cavity with argon gas of 5N purity at 40MPa in a cold state, and then start heating to the target temperature of 960℃ at a heating rate of 1.5℃ / min. During the heating process, argon gas is added to make the hot isostatic pressure furnace cavity reach the target pressure of 150MPa.

[0092] S44, maintain target temperature and pressure for 60 hours;

[0093] S45, after the heat preservation is completed, cool down to room temperature at a rate of 1℃ / min;

[0094] S46, reduce pressure to atmospheric pressure, remove from furnace, and take out the product;

[0095] S5, optical cold working, removes the Pd film layer on each side of the crystal material with Pd film layer on the entire outer surface after hot isostatic pressing, and obtains multispectral zinc sulfide crystal material. The optical cold working adopts surface grinding process, and the grinding is carried out by grinding machine. The abrasive is 600 mesh diamond powder purchased from Zhengzhou Xinli Wear-resistant Materials Co., Ltd.

[0096] Step S6: Prepare a test sample of multispectral zinc sulfide crystal material and perform optical performance testing. The thickness of the test sample is 9.5 mm.

[0097] Example 2

[0098] Except for the following differences, everything else is the same as in Example 1:

[0099] In step S1, the flat plate material has a size of 300mm×300mm×28mm;

[0100] In sub-step S34, the argon flow rate is 80 sccm and the sputtering pressure is 0.8 Pa;

[0101] In sub-step S35, the thickness of the sputtered Pd film is 300 nm;

[0102] In sub-step S43, the target pressure is 160 MPa;

[0103] In substep S44, the duration is 70 hours;

[0104] In step S6, the thickness of the test sample is 5 mm.

[0105] Example 3

[0106] Except for the following differences, everything else is the same as in Example 1:

[0107] In step S1, the spherical cover with the following specifications—convex surface curvature Rcx68, concave surface curvature Rcc60, total height Th56, center thickness CT8, and diameter 134mm—has a surface roughness controlled at Ra = 1.4μm.

[0108] In step S6, the thickness of the test sample is 5 mm.

[0109] Example 4

[0110] Except for the following differences, the rest are the same as in Example 2:

[0111] In step S1, the surface roughness of the spherical cover with convex curvature Rcx106, concave curvature Rcc93.5, total height Th106, center thickness CT12.5, and diameter 212mm is controlled at Ra=1.4μm.

[0112] In step S6, the thickness of the test sample is 1 mm.

[0113] Figure 1 This is a photograph of the multispectral zinc sulfide crystal material prepared in Example 1. Figure 2 This is a transmittance curve of the multispectral zinc sulfide crystal material (i.e., the test sample) prepared in Example 1 in the 0.4-0.8 μm band. Figure 3 This is a transmittance curve of the multispectral zinc sulfide crystal material (i.e., the test sample) prepared in Example 1 in the 8-12 μm band.

[0114] Figure 4 This is a photograph of the multispectral zinc sulfide crystal material prepared in Example 2. Figure 5 This is a transmittance curve of the multispectral zinc sulfide crystal material (i.e., the test sample) prepared in Example 2 in the 0.4-0.8 μm band. Figure 6 This is a transmittance curve of the multispectral zinc sulfide crystal material (i.e., the test sample) prepared in Example 2 in the 8-12μm band.

[0115] Figure 7 This is a photograph of the multispectral zinc sulfide crystal material prepared in Example 3. Figure 8 This is a transmittance curve of the multispectral zinc sulfide crystal material (i.e., the test sample) prepared in Example 3 in the 0.4-0.8 μm band. Figure 9 This is a transmittance curve of the multispectral zinc sulfide crystal material (i.e., the test sample) prepared in Example 3 in the 8-12μm band.

[0116] Figure 10 This is a photograph of the multispectral zinc sulfide crystal material prepared in Example 4. Figure 11 This is a transmittance curve of the multispectral zinc sulfide crystal material (i.e., the test sample) prepared in Example 4 in the 0.4-0.8 μm band. Figure 12 This is a transmittance curve of the multispectral zinc sulfide crystal material (i.e., the test sample) prepared in Example 4 in the 8-12 μm band.

[0117] from Figure 1 , Figure 4 , Figure 7 and Figure 10 It can be seen that, whether it is a flat plate or a spherical cover, the multispectral zinc sulfide crystal material obtained in Examples 1-4 has no haze layer at the edge and no haze layer overall.

[0118] based on Figure 2 and Figure 3 The multispectral zinc sulfide crystal material prepared in Example 2 has an average transmittance of 70.45% in the 0.4-0.8 μm band and an average transmittance of 74.97% in the 8-12 μm band.

[0119] based on Figure 5 and Figure 6The multispectral zinc sulfide crystal material prepared in Example 3 has an average transmittance of 70.55% in the 0.4-0.8 μm band and an average transmittance of 70.73% in the 8-12 μm band.

[0120] based on Figure 8 and Figure 9 The multispectral zinc sulfide crystal material prepared in Example 3 has an average transmittance of 69.95% in the 0.4-0.8 μm band and an average transmittance of 71.1% in the 8-12 μm band.

[0121] based on Figure 11 and Figure 12 The multispectral zinc sulfide crystal material prepared in Example 4 has an average transmittance of 70.72% in the 0.4-0.8 μm band and an average transmittance of 75.0% in the 8-12 μm band.

[0122] In addition, the results of other optical performance tests on the test samples of Examples 1-4 are as follows:

[0123] Example 1: Absorption coefficient 0.11 cm⁻¹ -1 The temperature coefficient of refractive index at 10.6 μm is 36 × 10⁻⁶. -6 / ℃, refractive index uniformity at 0.6328μm is 18×10 -6 ;

[0124] Example 2: Absorption coefficient 0.13 cm⁻¹ -1 The temperature coefficient of refractive index at 10.6 μm is 34 × 10⁻⁶. -6 / ℃, refractive index uniformity at 0.6328μm is 16×10 -6 ;

[0125] Example 3: Absorption coefficient 0.10 cm⁻¹ -1 The temperature coefficient of refractive index at 10.6 μm is 33 × 10⁻⁶. -6 / ℃, refractive index uniformity at 0.6328μm is 15×10 -6 ;

[0126] Example 4: Absorption coefficient 0.12 cm⁻¹ -1 The temperature coefficient of refractive index at 10.6 μm is 31 × 10⁻⁶. -6 / ℃, refractive index uniformity at 0.6328μm is 16×10 -6 .

[0127] Several exemplary embodiments have been described in detail above, but this document is not intended to limit itself to the explicitly disclosed combinations. Therefore, unless otherwise stated, the various features disclosed herein can be combined to form several other combinations, which are not shown for simplicity.

Claims

1. A process for preparing multispectral zinc sulfide crystals, characterized in that, Including the following steps: S1, Surface processing of virgin CVD zinc sulfide crystal material to control the surface roughness of virgin CVD zinc sulfide crystal material within Ra = 0.1-1.5 μm; S2, ultrasonic cleaning; S3, magnetron sputtering deposition of Pd film, including sub-steps: S31, The virgin CVD zinc sulfide crystal material cleaned in step S2 is loaded into the sputtering chamber of the magnetron sputtering coating machine. S32, install the Pd metal target into the sputtering chamber; S33, evacuate the sputtering chamber to an absolute pressure of 1.0 × 10⁻⁶. -3 Pa; S34, set the working conditions: argon gas is introduced, the argon gas flow rate is 20-200 sccm, the sputtering gas pressure is 0.1-1.0 Pa, and the sputtering temperature is room temperature; S35, a Pd film is sputtered onto the surface of the native CVD zinc sulfide crystal material for the first time. The thickness of the sputtered Pd film is 100-500nm. At this time, only the bottom mounting surface of the native CVD zinc sulfide crystal material is not coated with a film, while the other surfaces of the native CVD zinc sulfide crystal material are coated with a film. S36. After the first coating is completed, the sputtering chamber is brought to the outside atmospheric pressure, and the original CVD zinc sulfide crystal material with the first sputtered Pd film is removed. During the removal process, the original CVD zinc sulfide crystal material is protected from contamination. S37, the coated surface of the first sputtered Pd film layer of the original CVD zinc sulfide crystal material is put into the sputtering chamber of the magnetron sputtering coating machine. The surface without film layer in step S35 is used as the coating surface facing the target material. Sub-steps S33, S35 and S36 are repeated to obtain the original CVD zinc sulfide crystal material with Pd film layer on the entire outer surface. S4, hot isostatic pressing, to obtain a crystalline material with a Pd film coating on the entire outer surface after hot isostatic pressing. S5, optical cold processing, removes the Pd film layer on each side of the crystal material with Pd film layer on the entire outer surface after hot isostatic pressing, and obtains multispectral zinc sulfide crystal material. The obtained multispectral zinc sulfide crystal material has no haze layer at the edges and no haze layer overall.

2. The preparation process of multispectral zinc sulfide crystals according to claim 1, characterized in that, In step S1, primary zinc sulfide crystal material is grown using CVD. The CVD process for growing primary zinc sulfide crystals is as follows: ZnS crystal material is grown in a chemical vapor deposition furnace using a Zn-H2S reaction system. The deposition apparatus in the furnace mainly includes a crucible, a deposition chamber, and a discharge box, all made of isostatically pressed graphite. The crucible is responsible for melting and evaporating the raw material solid zinc at a heating temperature of 600℃. ZnS is grown in the deposition chamber. The deposition chamber and the crucible are connected by a partition with internally designed gas nozzles, which handles hydrogen sulfide gas and the zinc vapor molten and evaporated in the crucible. Argon, acting as a carrier gas, is injected into the deposition chamber through its respective gas path via a nozzle. It then travels to the surface of the graphite mold substrate, where a chemical reaction occurs to generate ZnS. The deposition chamber is heated to 660°C. Unreacted gaseous reactants, hydrogen byproducts, and zinc sulfide particles that failed to deposit effectively are carried by the carrier gas into the discharge box, where the gaseous substances are subsequently sent to the exhaust gas treatment system. After the reaction is complete, the flow of hydrogen sulfide is stopped, the crucible heating ceases, and the material cools naturally. The deposition chamber temperature is reduced to room temperature at a rate of 0.1-0.5°C / min. The resulting ZnS crystalline material is then obtained.

3. The preparation process of multispectral zinc sulfide crystals according to claim 1, characterized in that, In step S1, the primary CVD zinc sulfide crystal material is a flat plate or a spherical cover.

4. The preparation process of multispectral zinc sulfide crystals according to claim 1, characterized in that, In step S2, ultrasonic cleaning is performed using an eight-tank ultrasonic cleaner. The virgin CVD zinc sulfide crystal material is placed into the tanks in sequence from one to eight, and the entire process lasts for more than 20 minutes. The functions of each tank are as follows: Tank 1: ultrasonic cleaning, using the same grinding and polishing cleaning agent concentrate from the Xinmingyang brand at room temperature; Tank 2: ultrasonic cleaning, using the optical glass cleaning agent from the Feinaier brand, mixed with pure water to prepare a 5%-7% cleaning solution, with a cleaning temperature of 60°C; Tank 3: ultrasonic cleaning, using the same cleaning solution as Tank 2, with a cleaning temperature of 50°C; Tank 4: ultrasonic cleaning with pure water at room temperature; Tank 5: ultrasonic cleaning with pure water at room temperature; Tank 6: ultrasonic cleaning with pure water at room temperature; Tank 7: slow air dehydration; Tank 8: hot air drying, with a drying temperature of 50°C.

5. The preparation process of multispectral zinc sulfide crystals according to claim 1, characterized in that, In sub-step S32, the purity of the Pd metal target material is not less than 4N.

6. The preparation process of multispectral zinc sulfide crystals according to claim 1, characterized in that, Step S4 includes the following sub-steps: S41, Install the crystal material with Pd film coating on the entire outer surface completed in step S3 into the hot isostatic pressing furnace cavity; S42, furnace cleaning and annealing; S43, fill the furnace cavity with argon gas at a cold state of 30-60MPa, and then start heating to the target temperature of 900-1050℃ at a heating rate of 0.5-5℃ / min. During the heating process, supplement argon gas to make the hot isostatic pressure furnace cavity reach the target pressure of 100-200MPa. S44, maintain target temperature and pressure for 10-120 hours; S45, after the heat preservation is completed, cool down to room temperature at a rate of ≤5℃ / min; S46, reduce pressure to atmospheric pressure, remove from furnace, and take out the product.

7. The preparation process of multispectral zinc sulfide crystals according to claim 6, characterized in that, In sub-step 43, the purity of argon gas is not less than 5N.

8. The preparation process of multispectral zinc sulfide crystals according to claim 1, characterized in that, In step S5, the optical cold processing employs a surface grinding process.

9. The preparation process of multispectral zinc sulfide crystals according to claim 1, characterized in that, The preparation process of the multispectral zinc sulfide crystals also includes: Step S6: Prepare a test sample of the multispectral zinc sulfide crystal material and perform optical performance testing. The test results are as follows: The average transmittance in the 0.4-0.8 μm band is 69.95-70.72%. The average transmittance in the 8-12μm band is 70.73-75.0%.

10. The preparation process of multispectral zinc sulfide crystals according to claim 9, characterized in that, The test results also showed: The volume absorption coefficient is 0.10-0.13 cm. -1 , The temperature coefficient of refractive index in the 10.6 μm band is (31-36)×10. -6 / ℃, The refractive index uniformity in the 0.6328 μm band is (15-18)×10. -6 .

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