Preparation method and application of high-density tantalum pentoxide material

Abstract

The invention discloses a preparation method and application of a high-density tantalum pentoxide material, and relates to the field of functional materials.The preparation method comprises the following steps that tantalum pentoxide powder and silicon nitride powder are mixed with nanometer yttrium oxide to obtain bottom layer mixed powder and surface layer mixed powder; the preparation method comprises the following steps: weighing tantalum pentoxide powder and silicon nitride powder according to a gradient ratio, and adding nano yttrium oxide into each layer to obtain transition layer mixed powder; the bottom layer mixed powder, the transition layer mixed powder of each layer and the surface layer mixed powder are sequentially filled into a mold, and the high-density tantalum pentoxide material is obtained after sintering and treatment. The gradient composite structure of Ta2O5 and Si3N4 is adopted, continuous transition of the refractive index is achieved by adjusting sintering air pressure, densification and interface fusion are synchronously completed through single-time sintering by using a multi-chamber vacuum sintering furnace and combining a pre-pressed blank lamination technology, interlayer defects of traditional multiple coating are avoided, and the hardness of a film layer is improved by introducing a nano Y2O3 sintering aid.

Description

Technical Field

[0001] The present invention relates to the technical field of functional materials, and in particular to a preparation method and application of a high-density tantalum pentoxide material. Background Art

[0002] Tantalum pentoxide (Ta2O5) is a metal oxide with a high melting point (about 1800°C), high chemical stability and excellent dielectric properties. Its high refractive index (n=2.2 in the visible and infrared bands) and good film-forming ability made it widely used in the fields of electronics and optics in the early days. In the electronics field, Ta2O5 is mainly used to manufacture the dielectric layer of tantalum electrolytic capacitors. With its ability to form extremely thin and dense oxide films, it achieves high capacitance density and low leakage current, meeting the needs of miniaturization and high performance of electronic equipment; in the optical field, early Ta2O5 was mostly used to prepare single-layer optical films, using its high refractive index to achieve a certain degree of optical anti-reflection or spectroscopic function. However, with the development of technology, the requirements for material performance are constantly increasing, and the single Ta2O5 material has gradually shown limitations in terms of optical and mechanical properties.

[0003] In order to break through the performance bottleneck of a single material, the composite of tantalum pentoxide and silicon nitride (Si3N4) has become a technical development direction. Si3N4 has the characteristics of low refractive index (n=1.9), high hardness and good chemical stability, which form a distinct performance complement with Ta2O5. In the field of optics, traditional single-layer optical films are difficult to meet the needs of wide band and high anti-reflection, and Ta2O5 and Si3N4 are composited to construct a gradient structure, which can achieve continuous change of refractive index within a certain range, thereby effectively reducing the reflectivity of specific bands (such as infrared bands) and improving the light transmittance of optical devices; in terms of mechanical properties, the composite of the two can combine the chemical stability of Ta2O5 and the high hardness advantage of Si3N4 to enhance the overall wear resistance and corrosion resistance of the material. However, in the composite process, how to achieve uniform composite of the two materials, avoid interlayer defects, and accurately control the gradient structure has become a technical difficulty. Traditional preparation processes are difficult to effectively solve these problems. Summary of the Invention

[0004] In order to solve the above technical problems, the present invention provides a preparation method and application of a high-density tantalum pentoxide material.

[0005] The purpose of the present invention can be achieved through the following technical solutions:

[0006] A method for preparing a high-density tantalum pentoxide material comprises the following steps:

[0007] S1. Dividing the total tantalum pentoxide powder and the total silicon nitride powder into a first portion and a second portion respectively; mixing the first portion of tantalum pentoxide powder and the first portion of silicon nitride powder with nano yttrium oxide respectively to obtain a bottom layer mixed powder and a surface layer mixed powder;

[0008] S2. Weigh the second portion of tantalum pentoxide powder and the second portion of silicon nitride powder in a gradient ratio. From the bottom layer to the surface layer, the mass percentage of tantalum pentoxide decreases by 15-25% layer by layer, and the mass percentage of silicon nitride increases layer by layer accordingly. Design 3-6 layers. Add nano-yttrium oxide to each weighed layer of powder, and dry mix for 1-3 hours to obtain a transition layer mixed powder for each layer.

[0009] S3. Fill the mold in the order of bottom layer mixed powder, transition layer mixed powder of each layer (laid in gradient order from tantalum-rich side to silicon-rich side), and surface layer mixed powder. Pre-press each layer with 10-30 MPa for 4-6 minutes. After all powders are laid, the whole is cold-pressed at a pressure of 100-150 MPa for 5-15 minutes. The pressure is maintained. A sintered body is obtained by a segmented pressure-controlled vacuum sintering process in the sintering cavity of a pretreated multi-chamber vacuum sintering furnace. The surface of the sintered body is polished with diamond paste to obtain a high-density tantalum pentoxide material.

[0010] It should be noted that in step S3, the thickness of each layer of the bottom mixed powder, each layer of the transition layer mixed powder and the surface mixed powder when laid is 0.1-0.3 mm.

[0011] Furthermore, the mixing process in step S1 is to add the first portion of tantalum pentoxide and the first portion of silicon nitride powder and nano yttrium oxide into a ball mill respectively, at a rotation speed of 200-400 rpm, mix for 20-30 hours to form a slurry, and dry and sieve the slurry.

[0012] Furthermore, in step S1, the average particle size of the tantalum pentoxide powder is 400-600 nm, and the purity is ≥99.9%; the average particle size of the silicon nitride powder is 1-2 μm, and the purity is ≥99.5%.

[0013] Furthermore, the average particle size of the nano-yttrium oxide in step S1 and step S2 is 50-150 nm, and the purity is ≥99.9%; the amount of nano-yttrium oxide added to the bottom mixed powder is 0.4-0.6% of the mass of the first portion of tantalum pentoxide powder; and the amount of nano-yttrium oxide added to the surface mixed powder is 0.4-0.6% of the mass of the first portion of silicon nitride powder.

[0014] Furthermore, in step S1, the mass ratio of the total tantalum pentoxide powder to the total silicon nitride powder is 1-2:1-2.

[0015] Furthermore, in step S1, the mass ratio of the first portion of tantalum pentoxide powder to the second portion of tantalum pentoxide powder is 1-2:1-3; the mass ratio of the first portion of silicon nitride powder to the second portion of silicon nitride powder is 1-2:1-3.

[0016] Furthermore, in step S2, the amount of nano-yttrium oxide added to the mixed powder of each transition layer is 0.4-0.6% of the total mass of tantalum pentoxide powder and silicon nitride powder in the mixed powder of each transition layer.

[0017] Furthermore, the pretreatment of the multi-chamber vacuum sintering furnace in step S3 is to evacuate the multi-chamber vacuum furnace to a background vacuum degree of ≤10 -4 Pa, and ensure that the furnace environment is clean.

[0018] Furthermore, the segmented pressure-controlled vacuum sintering process in step S3 is:

[0019] Stage 1: Heating to 300-500℃, pressure gradient increased to 10 -3 Pa, keep warm for 1-3h;

[0020] Stage 2: Heating to 1000-1200℃, pressure gradient increased to 10 -2 Pa, keep warm for 1-2h;

[0021] Stage 3: Heating to 1400-1600℃, pressure gradient increased to 10 -1 Pa, keep warm for 2-4h;

[0022] Stage 4: Cooling to room temperature with the furnace, the pressure gradient changes to normal pressure.

[0023] A method for preparing a high-density tantalum pentoxide material is provided, and the material prepared is used in preparing an anti-sand-erosion coating for an airborne infrared lens.

[0024] Beneficial effects of the present invention:

[0025] (1) Using a gradient composite structure of Ta2O5 (high refractive index layer) and Si3N4 (low refractive index layer), by adjusting the sintering pressure (10 -3 Pa to 10 -1 The gradient change of Pa achieves a continuous transition of the refractive index from 2.2 to 1.9, and the reflectivity is <0.3% in the 3-5μm band.

[0026] (2) By using a multi-chamber vacuum sintering furnace and combining it with pre-pressed green body lamination technology, densification and interface fusion can be completed simultaneously in a single sintering process, thus avoiding the interlayer defects of traditional multiple coating processes. The introduction of nano-Y2O3 sintering aids can increase the hardness of the film layer, making it suitable for anti-sand corrosion coating of airborne infrared lenses.

[0027] (3) The traditional multiple coating process requires repeated furnace loading and multiple sintering, and the production cycle is long, usually more than 48 hours. The present invention utilizes a multi-chamber vacuum sintering furnace combined with pre-pressed green body lamination technology, and a single sintering can simultaneously complete densification and interface fusion. The production cycle is shortened to about 24 hours, which reduces production costs, improves production efficiency, and is suitable for large-scale industrial production. DETAILED DESCRIPTION

[0028] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0029] Example 1

[0030] Table 1: Material Proportions in Example 1 (Main Material Amount is the sum of the mass of Ta2O5 and Si3N4 in each layer (bottom layer, transition layers 1, 2, 3, 4, 5, 6 and surface layer))

[0031] Stratum <![CDATA[Mass ratio of Ta2O5]]> <![CDATA[Mass ratio of Si3N4]]> <![CDATA[Addition amount of Y2O3 (accounting for the amount of main material)]]> bottom layer 100％ 0％ 0.4％ Transition layer 1 85％ 15％ 0.4％ Transition layer 2 70％ 30％ 0.4％ Transition layer 3 55％ 45％ 0.4％ Transition layer 4 40％ 60％ 0.4％ Transition layer 5 25％ 75％ 0.4％ Transition layer 6 10％ 90％ 0.4％ surface layer 0％ 100％ 0.4％

[0032] A method for preparing a high-density tantalum pentoxide material comprises the following steps:

[0033] S1. Divide the total tantalum pentoxide powder and the total silicon nitride powder into the first and second parts respectively according to the mass percentage; add the first part of tantalum pentoxide powder and nano-yttrium oxide into a ball mill with a ball-to-material ratio of 10:1, use anhydrous ethanol (the amount is twice the volume of the first part of tantalum pentoxide powder) as a medium, rotate at 200 rpm, mix for 20 hours to form a slurry, and dry and sieve the slurry to obtain a bottom mixed powder; add the first part of silicon nitride powder and nano-yttrium oxide into a ball mill with a ball-to-material ratio of 10:1, use anhydrous ethanol (the amount is twice the volume of the first part of silicon nitride powder) as a medium, rotate at 200 rpm, mix for 20 hours to form a slurry, and dry and sieve the slurry to obtain a surface mixed powder;

[0034] The average particle size of tantalum pentoxide powder is 400 nm, and the purity is ≥99.9%; the average particle size of silicon nitride powder is 1 μm, and the purity is ≥99.5%; the average particle size of nano-yttrium oxide is 50 nm, and the purity is ≥99.9%; the mass ratio of total tantalum pentoxide powder to total silicon nitride powder is 1:1; the mass ratio of the first portion of tantalum pentoxide powder to the second portion of tantalum pentoxide powder is 1:2.85, and the mass ratio of the first portion of silicon nitride powder to the second portion of silicon nitride powder is 1:2.85.

[0035] S2. Weigh the second portion of tantalum pentoxide powder and the second portion of silicon nitride powder in a gradient ratio. From the bottom layer to the surface layer, the mass percentage of tantalum pentoxide decreases by 15% layer by layer, and the mass percentage of silicon nitride increases layer by layer accordingly. Design 6 layers. Add nano-yttrium oxide to each weighed layer of powder, and dry mix for 1 hour to obtain transition layer mixed powders for each layer.

[0036] S3. Fill the mold in the order of bottom layer mixed powder, transition layer mixed powder of each layer (laid in gradient order from tantalum-rich side to silicon-rich side), and surface layer mixed powder. Pre-press each layer with 10 MPa for 4 minutes. After all powders are laid, the whole is cold-pressed under a pressure of 100 MPa and the pressure is maintained for 5 minutes. The thickness of each layer (bottom layer, transition layers 1, 2, 3, 4, 5, 6 and surface layer) is 0.1 mm. In the sintering chamber of a pretreated multi-chamber vacuum sintering furnace, a sintered body is obtained through a segmented pressure-controlled vacuum sintering process. The surface of the sintered body is polished with diamond paste to obtain a high-density tantalum pentoxide material.

[0037] The segmented pressure-controlled vacuum sintering process is as follows:

[0038] Stage 1: Heating to 300°C, pressure gradient increased to 10 -3 Pa, keep warm for 1 h;

[0039] Stage 2: Heating to 1000℃, pressure gradient increased to 10 -2 Pa, keep warm for 1h;

[0040] Stage 3: Heating to 1400℃, pressure gradient increased to 10 -1 Pa, keep warm for 2h;

[0041] Stage 4: Cooling to room temperature with the furnace, the pressure gradient changes to normal pressure.

[0042] Example 2

[0043] Table 2: Material ratio of Example 2 (the amount of main material is the sum of the mass of Ta2O5 and Si3N4 in each layer (bottom layer, transition layers 1, 2, 3 and surface layer))

[0044] Stratum <![CDATA[Mass ratio of Ta2O5]]> <![CDATA[Mass ratio of Si3N4]]> <![CDATA[Addition amount of Y2O3 (accounting for the amount of main materials)]]> bottom layer 100％ 0％ 0.6％ Transition layer 1 75％ 25％ 0.6％ Transition layer 2 50％ 50％ 0.6％ Transition layer 3 25％ 75％ 0.6％ surface layer 0％ 100％ 0.6％

[0045] A method for preparing a high-density tantalum pentoxide material comprises the following steps:

[0046] S1. Divide the total tantalum pentoxide powder and the total silicon nitride powder into the first and second parts respectively according to the mass percentage; add the first part of tantalum pentoxide powder and nano-yttrium oxide into a ball mill with a ball-to-material ratio of 10:1, use anhydrous ethanol (the amount is twice the volume of the first part of tantalum pentoxide powder) as a medium, rotate at 400 rpm, mix for 30 hours to form a slurry, and dry and sieve the slurry to obtain a bottom mixed powder; add the first part of silicon nitride powder and nano-yttrium oxide into a ball mill with a ball-to-material ratio of 10:1, use anhydrous ethanol (the amount is twice the volume of the first part of silicon nitride powder) as a medium, rotate at 400 rpm, mix for 30 hours to form a slurry, and dry and sieve the slurry to obtain a surface mixed powder;

[0047] The average particle size of tantalum pentoxide powder is 400 nm, and the purity is ≥99.9%; the average particle size of silicon nitride powder is 1 μm, and the purity is ≥99.5%; the average particle size of nano yttrium oxide is 50 nm, and the purity is ≥99.9%; the mass ratio of total tantalum pentoxide powder to total silicon nitride powder is 1:1; the mass ratio of the first portion of tantalum pentoxide powder to the second portion of tantalum pentoxide powder is 1:1.5, and the mass ratio of the first portion of silicon nitride powder to the second portion of silicon nitride powder is 1:1.5.

[0048] S2. Weigh the second portion of tantalum pentoxide powder and the second portion of silicon nitride powder in a gradient ratio. From the bottom layer to the surface layer, the mass percentage of tantalum pentoxide decreases by 25% layer by layer, and the mass percentage of silicon nitride increases layer by layer accordingly. Design three layers, add nano-yttrium oxide to each weighed layer of powder, and dry mix for 3 hours to obtain transition layer mixed powders of each layer;

[0049] S3. Fill the mold in the order of bottom layer mixed powder, transition layer mixed powder of each layer (laid in gradient order from tantalum-rich side to silicon-rich side), and surface layer mixed powder. Pre-press each layer at 30 MPa for 6 minutes. After all powders are laid, the whole is cold-pressed at a pressure of 150 MPa and the pressure is maintained for 15 minutes. The thickness of each layer (bottom layer, transition layers 1, 2, 3 and surface layer) is 0.3 mm. In the sintering cavity of a pretreated multi-chamber vacuum sintering furnace, a sintered body is obtained through a segmented pressure-controlled vacuum sintering process. The surface of the sintered body is polished with diamond paste to obtain a high-density tantalum pentoxide material.

[0050] The segmented pressure-controlled vacuum sintering process is as follows:

[0051] Stage 1: Heating to 500°C, pressure gradient increased to 10 -3 Pa, keep warm for 3h;

[0052] Stage 2: Heating to 1200℃, pressure gradient increased to 10 -2 Pa, keep warm for 2h;

[0053] Stage 3: Heating to 1600℃, pressure gradient increased to 10 -1 Pa, keep warm for 4 h;

[0054] Stage 4: Cooling to room temperature with the furnace, the pressure gradient changes to normal pressure.

[0055] Example 3

[0056] Table 3: Material ratio of Example 3 (the amount of main material is the sum of the mass of Ta2O5 and Si3N4 in each layer (bottom layer, transition layers 1, 2, 3, 4 and surface layer))

[0057]

[0058]

[0059] A method for preparing a high-density tantalum pentoxide material comprises the following steps:

[0060] S1. Divide the total tantalum pentoxide powder and the total silicon nitride powder into the first and second parts respectively according to the mass percentage; add the first part of tantalum pentoxide powder and nano-yttrium oxide into a ball mill with a ball-to-material ratio of 10:1, use anhydrous ethanol (the amount is twice the volume of the first part of tantalum pentoxide powder) as a medium, rotate at 300 rpm, mix for 25 hours to form a slurry, and dry and sieve the slurry to obtain a bottom mixed powder; add the first part of silicon nitride powder and nano-yttrium oxide into a ball mill with a ball-to-material ratio of 10:1, use anhydrous ethanol (the amount is twice the volume of the first part of silicon nitride powder) as a medium, rotate at 300 rpm, mix for 25 hours to form a slurry, and dry and sieve the slurry to obtain a surface mixed powder;

[0061] The average particle size of tantalum pentoxide powder is 400 nm, and the purity is ≥99.9%; the average particle size of silicon nitride powder is 1 μm, and the purity is ≥99.5%; the average particle size of nano-yttrium oxide is 50 nm, and the purity is ≥99.9%; the mass ratio of total tantalum pentoxide powder to total silicon nitride powder is 1:1; the mass ratio of the first portion of tantalum pentoxide powder to the second portion of tantalum pentoxide powder is 1:2, and the mass ratio of the first portion of silicon nitride powder to the second portion of silicon nitride powder is 1:2.

[0062] S2. Weigh the second portion of tantalum pentoxide powder and the second portion of silicon nitride powder in a gradient ratio. From the bottom layer to the surface layer, the mass percentage of tantalum pentoxide decreases by 20% layer by layer, and the mass percentage of silicon nitride increases layer by layer accordingly. Design 4 layers. Add nano-yttrium oxide to each weighed layer of powder, and dry mix for 2 hours to obtain transition layer mixed powders of each layer.

[0063] S3. Fill the mold in the order of bottom layer mixed powder, transition layer mixed powder of each layer (laid in gradient order from tantalum-rich side to silicon-rich side), and surface layer mixed powder. Pre-press each layer with 20 MPa, and the pre-pressing time is 5 minutes. After all the powders are laid, the whole is cold-pressed at a pressure of 125 MPa, and the pressure is maintained for 10 minutes. The thickness of each layer (bottom layer, transition layers 1, 2, 3, 4 and surface layer) is 0.2 mm; in the sintering cavity of a pretreated multi-chamber vacuum sintering furnace, a sintered body is obtained through a segmented pressure-controlled vacuum sintering process; the surface of the sintered body is polished with diamond grinding paste to obtain a high-density tantalum pentoxide material.

[0064] The segmented pressure-controlled vacuum sintering process is as follows:

[0065] Stage 1: Heating to 400℃, pressure gradient increased to 10 -3 Pa, keep warm for 2h;

[0066] Stage 2: Heating to 1100°C, pressure gradient increased to 10 -2 Pa, keep warm for 1.5h;

[0067] Stage 3: Heating to 1500℃, pressure gradient increased to 10 -1 Pa, keep warm for 3h;

[0068] Stage 4: Cooling to room temperature with the furnace, the pressure gradient changes to normal pressure.

[0069] Comparative Example 1

[0070] Table 4: Material ratio of comparative example 1 (the amount of main material is the sum of the mass of Ta2O5 and Si3N4 in each layer (bottom layer, transition layer and surface layer)

[0071] Stratum <![CDATA[Mass ratio of Ta2O5]]> <![CDATA[Mass ratio of Si3N4]]> <![CDATA[Addition amount of Y2O3 (in proportion to the main material)]]> bottom layer 100％ 0％ 0.5％ transition layer 50％ 50％ 0.5％ surface layer 0％ 100％ 0.5％

[0072] A method for preparing a high-density tantalum pentoxide material comprises the following steps:

[0073] S1. Divide the total tantalum pentoxide powder and the total silicon nitride powder into the first and second parts respectively according to the mass percentage; add the first part of tantalum pentoxide powder and nano-yttrium oxide into a ball mill with a ball-to-material ratio of 10:1, use anhydrous ethanol (the amount is twice the volume of the first part of tantalum pentoxide powder) as a medium, rotate at 300 rpm, mix for 25 hours to form a slurry, and dry and sieve the slurry to obtain a bottom mixed powder; add the first part of silicon nitride powder and nano-yttrium oxide into a ball mill with a ball-to-material ratio of 10:1, use anhydrous ethanol (the amount is twice the volume of the first part of silicon nitride powder) as a medium, rotate at 300 rpm, mix for 25 hours to form a slurry, and dry and sieve the slurry to obtain a surface mixed powder;

[0074] The average particle size of tantalum pentoxide powder is 400 nm, and the purity is ≥99.9%; the average particle size of silicon nitride powder is 1 μm, and the purity is ≥99.5%; the average particle size of nano-yttrium oxide is 50 nm, and the purity is ≥99.9%; the mass ratio of total tantalum pentoxide powder to total silicon nitride powder is 1:1; the mass ratio of the first portion of tantalum pentoxide powder to the second portion of tantalum pentoxide powder is 2:1, and the mass ratio of the first portion of silicon nitride powder to the second portion of silicon nitride powder is 2:1.

[0075] S2. Mix the second portion of tantalum pentoxide powder and the second portion of silicon nitride powder, add nano-yttrium oxide, and dry mix for 2 hours to obtain a transition layer mixed powder;

[0076] S3. Fill the mold in the order of bottom layer mixed powder, transition layer mixed powder and surface layer mixed powder, pre-press each layer at 20 MPa for 5 minutes, and after all powders are laid, cold press the whole under a pressure of 125 MPa for 10 minutes. The thickness of each layer (bottom layer, transition layer and surface layer) is 0.2 mm; in the sintering cavity of a pretreated multi-chamber vacuum sintering furnace, a sintered body is obtained through a segmented pressure-controlled vacuum sintering process; the surface of the sintered body is polished with diamond paste to obtain a high-density tantalum pentoxide material.

[0077] The segmented pressure-controlled vacuum sintering process is as follows:

[0078] Stage 1: Heating to 400℃, keeping warm for 2h, maintaining the pressure in the furnace at 10 -3 Pa;

[0079] Stage 2: Heating to 1100°C, pressure gradient increased to 10 -2 Pa, keep warm for 1.5h;

[0080] Stage 3: Heating to 1500℃, pressure gradient increased to 10 -1 Pa, keep warm for 3h;

[0081] Stage 4: After keeping at the highest temperature for 2 hours, cool to room temperature with the furnace, maintaining the pressure gradient change throughout the process.

[0082] Comparative Example 2

[0083] Table 5: Material ratio of comparative example 2 (the amount of main material is the sum of the mass of Ta2O5 and Si3N4 in each layer (bottom layer, transition layers 1, 2, 3, 4 and surface layer))

[0084] Stratum <![CDATA[Mass ratio of Ta2O5]]> <![CDATA[Mass ratio of Si3N4]]> <![CDATA[Y2O3 content (by the amount of the main material)]]> bottom layer 100％ 0％ 0.5％ Transition layer 1 80％ 20％ 0.5％ Transition layer 2 60％ 40％ 0.5％ Transition layer 3 40％ 60％ 0.5％ Transition layer 4 20％ 80％ 0.5％ surface layer 0％ 100％ 0.5％

[0085] A method for preparing a high-density tantalum pentoxide material comprises the following steps:

[0086] S1. Divide the total tantalum pentoxide powder and the total silicon nitride powder into the first and second parts respectively according to the mass percentage; add the first part of tantalum pentoxide powder and nano-yttrium oxide into a ball mill with a ball-to-material ratio of 10:1, use anhydrous ethanol (the amount is twice the volume of the first part of tantalum pentoxide powder) as a medium, rotate at 300 rpm, mix for 25 hours to form a slurry, and dry and sieve the slurry to obtain a bottom mixed powder; add the first part of silicon nitride powder and nano-yttrium oxide into a ball mill with a ball-to-material ratio of 10:1, use anhydrous ethanol (the amount is twice the volume of the first part of silicon nitride powder) as a medium, rotate at 300 rpm, mix for 25 hours to form a slurry, and dry and sieve the slurry to obtain a surface mixed powder;

[0087] The average particle size of tantalum pentoxide powder is 400 nm, and the purity is ≥99.9%; the average particle size of silicon nitride powder is 1 μm, and the purity is ≥99.5%; the average particle size of nano-yttrium oxide is 50 nm, and the purity is ≥99.9%; the mass ratio of total tantalum pentoxide powder to total silicon nitride powder is 1:1; the mass ratio of the first portion of tantalum pentoxide powder to the second portion of tantalum pentoxide powder is 1:2, and the mass ratio of the first portion of silicon nitride powder to the second portion of silicon nitride powder is 1:2.

[0088] S2. Weigh the second portion of tantalum pentoxide powder and the second portion of silicon nitride powder in a gradient ratio. From the bottom layer to the surface layer, the mass percentage of tantalum pentoxide decreases by 20% layer by layer, and the mass percentage of silicon nitride increases layer by layer accordingly. Design 4 layers. Add nano-yttrium oxide to each weighed layer of powder, and dry mix for 2 hours to obtain transition layer mixed powders of each layer.

[0089] S3. Fill the mold in the order of the bottom layer mixed powder, the transition layer mixed powder of each layer (laid in gradient order from the tantalum-rich side to the silicon-rich side), and the surface layer mixed powder. Pre-press each layer at 20 MPa for 5 minutes. After all the powders are laid, the whole is cold-pressed at a pressure of 125 MPa and the pressure is maintained for 10 minutes. The thickness of each layer (bottom layer, transition layers 1, 2, 3, 4 and surface layer) is 0.2 mm. Move the mold into a muffle furnace for sintering and densification at a temperature of 1450°C for 6 hours to obtain a sintered body. Polish the surface of the sintered body with diamond grinding paste to obtain a high-density tantalum pentoxide material.

[0090] Comparative Example 3

[0091] Table 6: Material ratio of comparative example 3

[0092] Stratum <![CDATA[Mass ratio of Ta2O5]]> <![CDATA[Mass ratio of Si3N4]]> bottom layer 100％ 0％ Transition layer 1 80％ 20％ Transition layer 2 60％ 40％ Transition layer 3 40％ 60％ Transition layer 4 20％ 80％ surface layer 0％ 100％

[0093] A method for preparing a high-density tantalum pentoxide material comprises the following steps:

[0094] S1. Divide the total tantalum pentoxide powder and the total silicon nitride powder into a first portion and a second portion respectively according to mass percentage; the first portion of tantalum pentoxide powder is the bottom layer powder; the first portion of silicon nitride powder is the surface layer powder;

[0095] The average particle size of the tantalum pentoxide powder is 400 nm, and the purity is ≥99.9%; the average particle size of the silicon nitride powder is 1 μm, and the purity is ≥99.5%; the mass ratio of the total tantalum pentoxide powder to the total silicon nitride powder is 1:1; the mass ratio of the first portion of tantalum pentoxide powder to the second portion of tantalum pentoxide powder is 1:2, and the mass ratio of the first portion of silicon nitride powder to the second portion of silicon nitride powder is 1:2.

[0096] S2. Weigh the second portion of tantalum pentoxide powder and the second portion of silicon nitride powder in a gradient ratio. From the bottom layer to the surface layer, the mass percentage of tantalum pentoxide decreases by 20% layer by layer, and the mass percentage of silicon nitride increases layer by layer accordingly. Design 4 layers and dry mix for 2 hours to obtain transition layer mixed powders for each layer.

[0097] S3. Fill the mold in the order of bottom layer mixed powder, transition layer mixed powder of each layer (laid in gradient order from tantalum-rich side to silicon-rich side), and surface layer mixed powder. Pre-press each layer with 20 MPa, and the pre-pressing time is 5 minutes. After all the powders are laid, the whole is cold-pressed at a pressure of 125 MPa, and the pressure is maintained for 10 minutes. The thickness of each layer (bottom layer, transition layers 1, 2, 3, 4 and surface layer) is 0.2 mm; in the sintering cavity of a pretreated multi-chamber vacuum sintering furnace, a sintered body is obtained through a segmented pressure-controlled vacuum sintering process; the surface of the sintered body is polished with diamond grinding paste to obtain a high-density tantalum pentoxide material.

[0098] The segmented pressure-controlled vacuum sintering process is as follows:

[0099] Stage 1: Heating to 400℃, pressure gradient increased to 10 -3 Pa, keep warm for 2h;

[0100] Stage 2: Heating to 1100°C, pressure gradient increased to 10 -2 Pa, keep warm for 1.5h;

[0101] Stage 3: Heating to 1500℃, pressure gradient increased to 10 -1 Pa, keep warm for 3h;

[0102] Stage 4: Cooling to room temperature with the furnace, the pressure gradient changes to normal pressure.

[0103] The following is a further test of the effects of a high-density tantalum pentoxide material prepared by the present invention. The hardness test method is nanoindentation; the reflectivity test method is Fourier infrared spectrometer; and the sand erosion resistance test method is high-speed sand impact test.

[0104] The test results are as follows. The results are recorded in Table 7;

[0105] Table 7: Test results

[0106]

[0107] According to the data in Table 7, it can be seen from the comparison between the embodiments of the present invention and the comparative examples that a single transition layer leads to an increase in reflectivity. The reason is that the sudden change in the refractive index triggers Fresnel reflection, the constant low pressure causes the decomposition of Si3N4 (resulting in Si loss), and the lack of Y2O3 leads to an increase in grain boundary porosity, a decrease in hardness, and a weakening of sand erosion resistance.

[0108] The above content is merely an example and explanation of the concept of the present invention. Those skilled in the art may make various modifications or additions to the described specific embodiments or replace them in a similar manner. As long as they do not deviate from the concept of the invention or exceed the scope defined by the claims, they should all fall within the scope of protection of the present invention.

Claims

1. A method for preparing a high-density tantalum pentoxide material, characterized in that: The following steps are involved: S1. Dividing the total tantalum pentoxide powder and the total silicon nitride powder into a first portion and a second portion respectively; mixing the first portion of tantalum pentoxide powder and the first portion of silicon nitride powder with nano yttrium oxide respectively to obtain a bottom layer mixed powder and a surface layer mixed powder; S2. Weigh the second portion of tantalum pentoxide powder and the second portion of silicon nitride powder in a gradient ratio. From the bottom layer to the surface layer, the mass percentage of tantalum pentoxide decreases by 15-25% layer by layer, and the mass percentage of silicon nitride increases layer by layer accordingly. Design 3-6 layers. Add nano-yttrium oxide to each weighed layer of powder, and dry mix for 1-3 hours to obtain a transition layer mixed powder for each layer. S3. Fill the mold in the order of bottom layer mixed powder, transition layer mixed powder of each layer (laid in gradient order from tantalum-rich side to silicon-rich side), and surface layer mixed powder. Pre-press each layer with 10-30 MPa for 4-6 minutes. After all powders are laid, the whole is cold-pressed at a pressure of 100-150 MPa for 5-15 minutes. The pressure is maintained. A sintered body is obtained by a segmented pressure-controlled vacuum sintering process in the sintering cavity of a pretreated multi-chamber vacuum sintering furnace. The surface of the sintered body is polished with diamond paste to obtain a high-density tantalum pentoxide material.

2. The method for preparing a high-density tantalum pentoxide material according to claim 1, characterized in that: The mixing process in step S1 is to add the first portion of tantalum pentoxide and the first portion of silicon nitride powder and nano yttrium oxide into a ball mill respectively, at a rotation speed of 200-400 rpm, mix for 20-30 hours to form a slurry, and dry and sieve the slurry.

3. The method for preparing a high-density tantalum pentoxide material according to claim 1, characterized in that: In step S1, the average particle size of the tantalum pentoxide powder is 400-600 nm, and the purity is ≥99.9%; the average particle size of the silicon nitride powder is 1-2 μm, and the purity is ≥99.5%.

4. The method for preparing a high-density tantalum pentoxide material according to claim 1, characterized in that: The average particle size of the nano-yttrium oxide in step S1 and step S2 is 50-150 nm, and the purity is ≥99.9%; the amount of nano-yttrium oxide added to the bottom mixed powder is 0.4-0.6% of the mass of the first portion of tantalum pentoxide powder; and the amount of nano-yttrium oxide added to the surface mixed powder is 0.4-0.6% of the mass of the first portion of silicon nitride powder.

5. The method for preparing a high-density tantalum pentoxide material according to claim 1, characterized in that: In step S1, the mass ratio of the total tantalum pentoxide powder to the total silicon nitride powder is 1-2:1-2.

6. The method for preparing a high-density tantalum pentoxide material according to claim 1, characterized in that: In step S1, the mass ratio of the first portion of tantalum pentoxide powder to the second portion of tantalum pentoxide powder is 1-2:1-3; the mass ratio of the first portion of silicon nitride powder to the second portion of silicon nitride powder is 1-2:1-3.

7. The method for preparing a high-density tantalum pentoxide material according to claim 1, characterized in that: In the step S2, the amount of nano-yttrium oxide added to the mixed powder of each transition layer is 0.4-0.6% of the total mass of tantalum pentoxide powder and silicon nitride powder in the mixed powder of each transition layer.

8. The method for preparing a high-density tantalum pentoxide material according to claim 1, characterized in that: The pretreatment of the multi-chamber vacuum sintering furnace in step S3 is to evacuate the multi-chamber vacuum furnace to a background vacuum degree of ≤10 -4 Pa, and ensure that the furnace environment is clean.

9. The method for preparing a high-density tantalum pentoxide material according to claim 1, characterized in that: The segmented pressure-controlled vacuum sintering process in step S3 is as follows: Stage 1: Heating to 300-500℃, pressure gradient increased to 10 -3 Pa, keep warm for 1-3h; Stage 2: Heating to 1000-1200℃, pressure gradient increased to 10 -2 Pa, keep warm for 1-2h; Stage 3: Heating to 1400-1600℃, pressure gradient increased to 10 -1 Pa, keep warm for 2-4h; Stage 4: Cooling to room temperature with the furnace, the pressure gradient changes to normal pressure.

10. Use of a material prepared by the method for preparing a high-density tantalum pentoxide material according to any one of claims 1 to 9 in preparing an anti-sand-erosion coating for an airborne infrared lens.

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