A langmuir probe structure and a method of manufacturing the same

Abstract

The present application relates to a kind of Langmuir probe structure and its preparation method, the Langmuir probe structure includes the tungsten probe being arranged from inside to outside along the radial direction, composite ceramic tube and heat shield;Between the composite ceramic tube and tungsten probe, and between composite ceramic tube and heat shield respectively independently copper-based brazing filler metal layer is arranged;The composite ceramic tube includes ceramic tube and transition layer being arranged in the inner and outer surface of ceramic tube;The Langmuir probe structure provided by the present application is a kind of tungsten probe-copper-based brazing filler metal layer-transition layer-ceramic tube-transition layer-copper-based brazing filler metal layer-heat shield structure, transition layer powder contains more than 75wt% tungsten component, forms tungsten skeleton in preparation process, it is convenient for brazing filler metal to infiltrate into tungsten skeleton and form dense connection, simultaneously with the effect of wetting tungsten material.The Langmuir probe provided by the present application has the advantages of high structural strength, strong high-temperature load resistance.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of ceramic metal sealing, and relates to a ceramic metal sealing structure, in particular to a Langmuir probe structure and a preparation method thereof. BACKGROUND

[0002] The Langmuir probe for a Thomson device is made of pure tungsten, and needs to be insulated by high-purity ceramic with a purity of more than 99wt%. Due to the large difference in material between the two, there is a large welding difficulty. Moreover, the Langmuir probe structure also needs to be able to withstand a high heat load impact of 10MW·m -2 2to avoid the problem of probe structure failure.

[0003] In the prior art, at least the following problems exist when ceramic and metal are connected:

[0004] GB874303A discloses a ceramic part for bonding with metals and alloys, having a metallized mixture forming a diffusion layer and firmly adhering to the ceramic part, the metallized mixture comprising a powder consisting of at least one metal selected from molybdenum, tungsten, rhenium and iron, and at least one oxide selected from oxides of chromium, titanium and niobium; the diffusion layer cannot effectively diffuse and combine with high-purity alumina ceramic with a purity of more than 99wt% because the main element is mainly metal, and is only suitable for ceramic bonding with an alumina content of less than 99wt%, and the sintering temperature needs to reach more than 1500℃.

[0005] Moreover, the formula of the metal layer provided by the prior art will flow, exude and even lose in a high-vacuum and high-temperature environment, resulting in uneven or damaged contact surfaces, and a large decrease in thermal conductivity and bonding strength. SUMMARY

[0006] The application aims to provide a Langmuir probe structure and a preparation method thereof, which can avoid the defects of the transition layer in the prior art, and improve the structural strength and high-heat-load resistance of the Langmuir probe by changing the composition of the transition layer.

[0007] To achieve the application purpose, the following technical solutions are adopted in the application:

[0008] In a first aspect, the application provides a Langmuir probe structure, which comprises, along a radial direction, a tungsten probe, a composite ceramic tube and a heat shield arranged from inside to outside.

[0009] A copper-based filler layer is independently arranged between the composite ceramic tube and the tungsten probe, and between the composite ceramic tube and the heat shield.

[0010] The composite ceramic tube comprises a ceramic tube and a transition layer arranged on the inner and outer surfaces of the ceramic tube.

[0011] The preparation raw material of the transition layer comprises a transition layer powder and a binder.

[0012] The preparation raw material of the transition layer powder comprises tungsten, manganese oxide, silicon dioxide and aluminum oxide.

[0013] In terms of mass percentage, the mass percentage of tungsten in the preparation raw material of the transition layer powder is 75 wt% or more, and the mass ratio of tungsten to manganese oxide is 8:1 to 20:1.

[0014] The Langmuir probe structure provided by the present application is a structure of a tungsten probe-copper-based filler layer-transition layer-ceramic tube-transition layer-copper-based filler layer-heat shield, the powder in the transition layer contains 75 wt% or more of tungsten component, and the mass ratio of tungsten to manganese oxide is 8:1 to 20:1, a tungsten skeleton with micro pores is formed in the preparation process, which facilitates the copper-based filler to infiltrate into the tungsten skeleton to form a dense connection, and also has the effect of wetting the tungsten material. The Langmuir probe provided by the present application has the advantages of high structural strength and strong high-heat load resistance.

[0015] In the present application, the content of tungsten in the transition layer powder is controlled so that the tungsten copper infiltration effect of the transition layer powder can be fully utilized in application. Specifically, in terms of mass percentage, the mass percentage of tungsten in the preparation raw material of the transition layer powder is 75 wt% or more, for example, it can be 75 wt%, 78 wt%, 80 wt%, 82 wt%, 85 wt%, 88 wt% or 90 wt%, but is not limited to the listed values, and other values not listed in the value range are also applicable.

[0016] In the present application, the mass ratio of tungsten to manganese oxide in the preparation raw material of the transition layer powder is 8:1 to 20:1, for example, it can be 8:1, 10:1, 12:1, 15:1, 16:1, 18:1 or 20:1, but is not limited to the listed values, and other values not listed in the value range are also applicable.

[0017] The inner and outer surfaces of the ceramic tube in the present application refer to the surface of the ceramic tube close to the tungsten probe and the surface of the ceramic tube away from the tungsten probe.

[0018] Preferably, the transition layer powder is composed of 75 wt% to 85 wt% of tungsten, 4.5 wt% to 7.5 wt% of manganese oxide, 6.75 wt% to 11.25 wt% of silicon dioxide and 3.75 wt% to 6.25 wt% of aluminum oxide in terms of mass percentage.

[0019] The mass percentage of tungsten in the raw material for preparing the transition layer powder is 75-85wt%, for example, it can be 75wt%, 78wt%, 80wt%, 82wt%, or 85wt%, but is not limited to the listed values, and other values not listed in the value range are also applicable.

[0020] The mass percentage of manganese oxide in the raw material for preparing the transition layer powder is 4.5-7.5wt%, for example, it can be 4.5wt%, 5wt%, 5.5wt%, 6wt%, 6.5wt%, 7wt%, or 7.5wt%, but is not limited to the listed values, and other values not listed in the value range are also applicable.

[0021] The mass percentage of silicon dioxide in the raw material for preparing the transition layer powder is 6.75-11.25wt%, for example, it can be 6.75wt%, 7wt%, 7.5wt%, 8wt%, 8.5wt%, 9wt%, 9.5wt%, 10wt%, 10.5wt%, 11wt%, or 11.25wt%, but is not limited to the listed values, and other values not listed in the value range are also applicable.

[0022] The mass percentage of aluminum oxide in the raw material for preparing the transition layer powder is 3.75-6.25wt%, for example, it can be 3.75wt%, 4wt%, 4.5wt%, 5wt%, 5.5wt%, 6wt%, or 6.25wt%, but is not limited to the listed values, and other values not listed in the value range are also applicable.

[0023] For example, the method for preparing the transition layer powder comprises the following steps: ball-milling tungsten, manganese oxide, silicon dioxide, and aluminum oxide according to the formula to obtain the transition layer powder.

[0024] The grinding balls used in the ball-milling include but are not limited to zirconia balls.

[0025] Preferably, the ball-to-material ratio of the ball-milling is 1:1 to 1.5:1, for example, it can be 1:1, 1.1:1, 1.2:1, 1.3:1, 1.4:1, or 1.5:1, but is not limited to the listed values, and other values not listed in the value range are also applicable.

[0026] The ball-to-material ratio is the mass ratio of the grinding balls to the grinding material.

[0027] Preferably, the ball-milling time is 45h to 48h, for example, it can be 45h, 45.5h, 46h, 46.5h, 47h, 47.5h, or 48h, but is not limited to the listed values, and other values not listed in the value range are also applicable.

[0028] Preferably, the binder comprises an alcohol solvent and cellulose.

[0029] Illustratively, the alcohol solvent comprises, but is not limited to, terpineol.

[0030] The terpineol comprises any one of a-terpineol, β-terpineol or γ-terpineol or a combination of at least two of them, typically but not limited to a combination of a-terpineol and β-terpineol, β-terpineol and γ-terpineol, a-terpineol and γ-terpineol, or a combination of a-terpineol, β-terpineol and γ-terpineol.

[0031] Illustratively, the cellulose comprises ethyl cellulose.

[0032] Preferably, the binder comprises a uniformly mixed alcohol solvent and cellulose.

[0033] The present application does not specifically limit the method of uniformly mixing the alcohol solvent and cellulose, as long as uniform mixing can be achieved. Illustratively, the method of uniform mixing comprises water bath heating and ultrasonic treatment for 20 to 24 hours, under which conditions uniform mixing of the alcohol solvent and cellulose can be ensured.

[0034] Preferably, the binder comprises 5 to 15 wt% cellulose in terms of mass percentage, for example, it can be 5 wt%, 6 wt%, 8 wt%, 10 wt%, 12 wt% or 15 wt%, but is not limited to the listed values, and other unlisted values within the value range are also applicable.

[0035] Preferably, the binder is 33 to 35% of the mass of the transition layer powder, for example, it can be 33%, 33.5%, 34%, 34.5% or 35%, but is not limited to the listed values, and other unlisted values within the value range are also applicable.

[0036] Preferably, the tungsten probe has a diameter of 3 to 3.1 mm, for example, it can be 3 mm, 3.02 mm, 3.05 mm, 3.08 mm or 3.1 mm, but is not limited to the listed values, and other unlisted values within the value range are also applicable.

[0037] The present application does not specifically limit the method of preparing the tungsten probe, as long as a tungsten probe with a diameter of 3 to 3.1 mm can be obtained. Illustratively, the method of preparing the tungsten probe of the present application comprises the following steps: a tungsten rod with a tungsten content of 99.5 wt% or more is prepared into a tungsten rod with a diameter of 3.5 to 4.5 mm by a conventional heat treatment method, and then a tungsten probe with a diameter of 3 to 3.1 mm is prepared by a conventional machining method.

[0038] Preferably, the ceramic tube has an inner diameter of 3.1 mm to 3.2 mm and a wall thickness of 0.4 mm to 0.5 mm.

[0039] The inner diameter of the ceramic tube described in this invention is 3.1 mm to 3.2 mm, for example, it can be 3.1 mm, 3.12 mm, 3.15 mm, 3.18 mm or 3.2 mm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0040] The wall thickness of the ceramic tube described in this invention is 0.4 mm to 0.5 mm, for example, it can be 0.4 mm, 0.42 mm, 0.45 mm, 0.48 mm or 0.5 mm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0041] The ceramic tubes described in this invention include, but are not limited to, alumina ceramic tubes. This invention does not impose excessive limitations on the specific preparation method of the ceramic tubes; as long as a ceramic tube with an inner diameter of 3.1 mm to 3.2 mm and a wall thickness of 0.4 mm to 0.5 mm can be obtained, it is acceptable.

[0042] For example, the method for preparing the ceramic tube of the present invention includes the following steps: mixing alumina powder with a purity of 99 wt% with a binder, preparing a ceramic feedstock using a mixer, and preparing a ceramic tube with an inner diameter of 4.05 mm to 4.15 mm and a wall thickness of 0.6 mm to 0.8 mm by injection molding; then removing part of the binder from the ceramic tube by cold stripping, and then sintering it in a tube furnace to finally prepare a ceramic tube with an inner diameter of 3.1 mm to 3.2 mm and a wall thickness of 0.4 mm to 0.5 mm. The sintering temperature is 1570°C to 1600°C, and the atmosphere is air.

[0043] Preferably, the inner diameter of the heat insulation screen is 4.1mm to 4.2mm, for example, it can be 4.1mm, 4.12mm, 4.15mm, 4.18mm or 4.2mm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0044] The heat insulation screen described in this invention includes, but is not limited to, tungsten heat insulation screens. This invention does not impose excessive limitations on the specific preparation method of the heat insulation screen, as long as a heat insulation screen with an inner diameter of 4.1 mm to 4.2 mm can be obtained. For example, the preparation method of the heat insulation screen described in this invention includes the following steps: preparing a tungsten rod with a tungsten content of 99.5 wt% or higher into a tungsten rod with a diameter of 15 mm to 20 mm using conventional heat treatment methods, and then preparing a tungsten heat insulation screen with an inner diameter of 4.1 mm to 4.2 mm using conventional machining methods.

[0045] Preferably, the composite ceramic tube is prepared by the following method:

[0046] (I) Mix the binder and transition layer powder according to the formula to obtain the transition layer slurry;

[0047] (II) The transition layer slurry is coated on the inner and outer surfaces of the ceramic tube, and then dried and sintered in sequence to obtain the composite ceramic tube.

[0048] Preferably, the mixing method in step (I) includes ball milling.

[0049] The grinding balls used in the ball mill include, but are not limited to, zirconia balls.

[0050] Preferably, the ball-to-material ratio of the ball mill is 1:1 to 1.5:1, for example, it can be 1:1, 1.1:1, 1.2:1, 1.3:1, 1.4:1 or 1.5:1, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0051] The ball-to-material ratio is the mass ratio of grinding balls to grinding material.

[0052] Preferably, the ball milling time is 45h to 48h, for example, it can be 45h, 45.5h, 46h, 46.5h, 47h, 47.5h or 48h, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0053] As a preferred technical solution for the preparation method, the ball milling device used in step (I) is the same as the ball milling device used to prepare the transition layer powder. That is, the binder is added to the ball milling device used to prepare the transition layer powder to achieve mixing of the binder and the transition layer powder.

[0054] If the coating thickness in step (II) is too thin, there will be insufficient welding strength in subsequent applications; if the coating thickness is too thick, there will also be a defect that the welding strength will be reduced when the subsequent copper-based brazing filler cannot completely cover the tungsten skeleton. Therefore, as a preferred technical solution, the coating thickness in step (II) is 0.03 mm to 0.04 mm, for example, it can be 0.03 mm, 0.032 mm, 0.035 mm, 0.036 mm, 0.038 mm or 0.04 mm, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0055] Preferably, the drying temperature in step (II) is 60°C to 80°C, for example, 60°C, 65°C, 70°C, 75°C or 80°C, but not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0056] Preferably, the drying time in step (II) is 10h to 12h, for example, it can be 10h, 10.5h, 11h, 11.5h or 12h, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0057] Preferably, the sintering in step (II) is carried out in a wet hydrogen atmosphere with a water temperature of 30°C to 35°C, for example, 30°C, 31°C, 32°C, 33°C, 34°C or 35°C, but not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0058] Preferably, the sintering in step (II) is continuous sintering.

[0059] Preferably, the continuous sintering is carried out in a continuous sintering furnace.

[0060] For example, along the direction of movement of the sintered sample, the continuous sintering furnace includes four temperature zones, namely the first temperature zone, the second temperature zone, the third temperature zone and the fourth temperature zone. Each temperature zone has eight to nine sintering boats, and one boat is advanced every 12 to 18 minutes.

[0061] The temperature of the first temperature zone is 450°C to 500°C, for example, it can be 450°C, 460°C, 470°C, 480°C or 500°C, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0062] The temperature of the second temperature zone is 850°C to 900°C, for example, it can be 850°C, 860°C, 880°C, 890°C or 900°C, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0063] The temperature of the third temperature zone is 1250°C to 1300°C, for example, it can be 1250°C, 1260°C, 1270°C, 1280°C or 1300°C, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0064] The temperature of the fourth temperature zone is 1450℃ to 1500℃, for example, it can be 1450℃, 1460℃, 1480℃, 1490℃ or 1500℃, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0065] When sintering in a continuous sintering furnace, the boat pushing speed is 12 min / boat to 18 min / boat, for example, it can be 12 min / boat, 14 min / boat, 15 min / boat, 16 min / boat or 18 min / boat, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0066] Secondly, the present invention provides a method for preparing the Langmuir probe structure as described in the first aspect, the method comprising the following steps:

[0067] (1) A copper-based solder layer is wrapped around the outer layer of the tungsten probe and then assembled into the inner cavity of the composite ceramic tube so that the tungsten probe and the composite ceramic tube are tightly fitted through the copper-based solder layer.

[0068] (2) A copper-based brazing layer is wrapped around the outer layer of the composite ceramic tube, and then assembled into the inner cavity of the heat insulation screen so that the heat insulation screen and the composite ceramic tube are tightly fitted through the copper-based brazing layer.

[0069] (3) Sintering is carried out under a reducing atmosphere to obtain the Langmuir probe structure.

[0070] The material of the copper-based solder layer in step (1) includes, but is not limited to, copper foil solder.

[0071] The present invention does not specifically limit the thickness of the copper-based solder layer in step (1), as long as the tungsten probe and the composite ceramic tube can be tightly fitted through the copper-based solder layer.

[0072] The material of the copper-based solder layer in step (2) includes, but is not limited to, copper foil solder.

[0073] The present invention does not specifically limit the thickness of the copper-based solder layer in step (2), as long as the tungsten probe and the composite ceramic tube can be tightly fitted through the copper-based solder layer.

[0074] Preferably, the sintering temperature in step (3) is 1100°C to 1170°C, for example, it can be 1100°C, 1110°C, 1120°C, 1130°C, 1140°C, 1150°C, 1160°C or 1170°C, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0075] Preferably, the sintering time in step (3) is 5 min to 15 min, for example, it can be 5 min, 8 min, 10 min, 12 min or 15 min, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0076] Preferably, the reducing atmosphere in step (3) includes, but is not limited to, a hydrogen atmosphere.

[0077] As a preferred embodiment of the preparation method described in the second aspect of the present invention, the preparation method includes the following steps:

[0078] (1) Copper foil brazing filler is wrapped around the outer layer of the tungsten probe and then assembled into the inner cavity of the composite ceramic tube so that the tungsten probe and the composite ceramic tube are tightly fitted by the copper foil brazing filler.

[0079] (2) Copper foil brazing filler metal is wrapped around the outer layer of the composite ceramic tube and then assembled into the inner cavity of the heat insulation screen so that the heat insulation screen and the composite ceramic tube are tightly fitted by the copper foil brazing filler metal.

[0080] (3) Under reducing atmosphere conditions, the Langmuir probe structure was obtained by sintering at 1100℃ to 1170℃ for 5 min to 15 min to obtain the Langmuir probe structure.

[0081] Compared with the prior art, the present invention has the following beneficial effects:

[0082] The Langmuir probe structure provided by this invention is a tungsten probe-copper-based solder layer-transition layer-ceramic tube-transition layer-copper-based solder layer-heat shield structure. The transition layer powder contains more than 75 wt% tungsten, forming a tungsten skeleton during the preparation process. This facilitates the solder's infiltration into the tungsten skeleton to form a dense connection, while also wetting the tungsten material. The Langmuir probe provided by this invention has the advantages of high structural strength and strong resistance to high heat loads. Attached Figure Description

[0083] Figure 1 A schematic diagram of the Langmuir probe structure provided by the present invention;

[0084] The components are: 1. Tungsten probe; 2. Copper-based solder layer; 3. Transition layer; 4. Alumina ceramic tube; 5. Tungsten heat shield. Detailed Implementation

[0085] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0086] To clearly illustrate the technical solution of the present invention, the tungsten probe in the specific embodiment is prepared by the following method: a tungsten rod with a tungsten content of 99.5 wt% or more is prepared by conventional heat treatment to obtain a tungsten rod, and then a tungsten probe of the target diameter is prepared by conventional machining.

[0087] The ceramic tube is prepared by the following method: 99wt% pure alumina powder and binder are mixed and a ceramic feedstock is prepared using an internal mixer. The ceramic tube is then prepared by injection molding. The binder is then partially removed from the ceramic tube by cold stripping. Finally, the tube is sintered in a tube furnace to obtain an alumina ceramic tube of the target size.

[0088] The heat insulation screen is prepared by the following method: a tungsten rod with a tungsten content of more than 99.5 wt% is prepared by conventional heat treatment method to obtain a tungsten rod, and then the heat insulation screen of the target size is prepared by conventional machining method.

[0089] Example 1

[0090] This embodiment provides a method such as Figure 1 The Langmuir probe structure shown includes a tungsten probe 1, a composite ceramic tube, and a tungsten heat shield 5 arranged radially from the inside out.

[0091] A copper-based solder layer 2 is independently provided between the composite ceramic tube and the tungsten probe 1, and between the composite ceramic tube and the tungsten heat shield 5; the material of the copper-based solder layer 2 is copper foil solder.

[0092] The composite ceramic tube includes an alumina ceramic tube 4 and a transition layer 3 disposed on the inner and outer sides of the alumina ceramic tube 4.

[0093] The tungsten probe 1 has a diameter of 3.05 mm; the alumina ceramic tube 4 has an inner diameter of 3.15 mm and a wall thickness of 0.45 mm; and the tungsten heat shield 5 has an inner diameter of 4.15 mm.

[0094] The raw materials for preparing the transition layer 3 include transition layer powder and binder; the binder accounts for 34% of the mass of the transition layer powder.

[0095] The transition layer powder is prepared from raw materials consisting of 85.4 wt% tungsten, 4.27 wt% manganese oxide, 6.75 wt% silicon dioxide, and 3.58 wt% aluminum oxide. The preparation method includes the following steps: ball milling tungsten, manganese oxide, silicon dioxide, and aluminum oxide according to the formula to obtain the transition layer powder; the ball-to-material ratio is 1.2:1, and the milling time is 46 hours.

[0096] The adhesive is prepared by the following steps: 90% α-terpineol and 10% ethyl cellulose (Maclean, AR) are mixed by mass percentage, heated in a water bath and ultrasonically treated for 24 hours to make the terpineol and ethyl cellulose uniformly mixed.

[0097] The composite ceramic tube was prepared using the following method:

[0098] (I) Ball milling is used to mix the binder and the transition layer powder to obtain the transition layer slurry;

[0099] Ball milling and mixing continued in the ball milling apparatus used to prepare the transition layer powder for 46 hours.

[0100] (II) A transition layer slurry is coated on the inner and outer surfaces of the alumina ceramic tube 4, with a coating thickness of 0.035 mm; the tube is then dried and sintered to obtain a composite ceramic tube; the drying temperature is 70°C and the drying time is 11 h.

[0101] The sintering is continuous and is carried out in a continuous sintering furnace. The sintering uses a wet hydrogen atmosphere and the water temperature is 32°C. Along the movement direction of the sintered sample, the continuous sintering furnace includes four temperature zones: a first temperature zone, a second temperature zone, a third temperature zone, and a fourth temperature zone. Each temperature zone has eight sintering boats, and one boat is advanced every 15 minutes. The temperature of the first temperature zone is 480°C, the temperature of the second temperature zone is 880°C, the temperature of the third temperature zone is 1280°C, and the temperature of the fourth temperature zone is 1480°C.

[0102] The method for preparing the Langmuir probe structure described in this embodiment includes the following steps:

[0103] (1) Copper foil brazing filler is wrapped around the outer layer of the tungsten probe 1 and then assembled into the inner cavity of the composite ceramic tube so that the tungsten probe 1 and the composite ceramic tube are tightly fitted by the copper foil brazing filler.

[0104] (2) Copper foil brazing filler metal is wrapped around the outer layer of the composite ceramic tube and then assembled into the inner cavity of the tungsten heat shield 5 so that the tungsten heat shield 5 and the composite ceramic tube are tightly fitted by the copper foil brazing filler metal.

[0105] (3) Under hydrogen atmosphere, the Langmuir probe structure was obtained by sintering at 1150℃ for 10 min.

[0106] Example 2

[0107] This embodiment provides a Langmuir probe structure, except that the raw materials for preparing the transition layer powder are composed of 80 wt% tungsten, 10 wt% manganese oxide, 6.75 wt% silicon dioxide and 3.25 wt% aluminum oxide, and the rest are the same as in Example 1.

[0108] Example 3

[0109] This embodiment provides a Langmuir probe structure, except that the raw materials for preparing the transition layer powder are composed of 75 wt% tungsten, 7.5 wt% manganese oxide, 11.25 wt% silicon dioxide and 6.25 wt% aluminum oxide, and the rest are the same as in Example 1.

[0110] Example 4

[0111] This embodiment provides a Langmuir probe structure, except that the raw materials for preparing the transition layer powder are composed of 85 wt% tungsten, 4.5 wt% manganese oxide, 6.25 wt% silicon dioxide and 3.75 wt% aluminum oxide, and the rest are the same as in Example 1.

[0112] Example 5

[0113] This embodiment provides a Langmuir probe structure, except that the raw materials for preparing the transition layer powder are composed of 80 wt% tungsten, 6 wt% manganese oxide, 9 wt% silicon dioxide and 5 wt% aluminum oxide, and the rest are the same as in Example 1.

[0114] Example 6

[0115] This embodiment provides a Langmuir probe structure, which includes a tungsten probe 1, a composite ceramic tube, and a tungsten heat shield 5 arranged radially from the inside to the outside.

[0116] A copper-based solder layer 2 is independently provided between the composite ceramic tube and the tungsten probe 1, and between the composite ceramic tube and the tungsten heat shield 5; the material of the copper-based solder layer 2 is copper foil solder.

[0117] The composite ceramic tube includes an alumina ceramic tube 4 and a transition layer 3 disposed on the inner and outer sides of the alumina ceramic tube 4.

[0118] The tungsten probe 1 has a diameter of 3 mm; the alumina ceramic tube 4 has an inner diameter of 3.1 mm and a wall thickness of 0.4 mm; and the tungsten heat shield 5 has an inner diameter of 4.1 mm.

[0119] The raw materials for preparing the transition layer 3 include transition layer powder and binder; the binder accounts for 33% of the mass of the transition layer powder.

[0120] The transition layer powder is prepared from raw materials consisting of 80 wt% tungsten, 6 wt% manganese oxide, 9 wt% silicon dioxide, and 5 wt% aluminum oxide. The preparation method includes the following steps: ball milling tungsten, manganese oxide, silicon dioxide, and aluminum oxide according to the formula to obtain the transition layer powder; the ball-to-material ratio is 1:1, and the milling time is 48 hours.

[0121] The adhesive is prepared by the following steps: 95% α-terpineol and 5% ethyl cellulose (Maclean, AR) are mixed at a mass percentage, heated in a water bath and ultrasonically treated for 24 hours to make the terpineol and ethyl cellulose uniformly mixed.

[0122] The composite ceramic tube was prepared using the following method:

[0123] (I) Ball milling is used to mix the binder and the transition layer powder to obtain the transition layer slurry;

[0124] Ball milling and mixing continued in the ball milling apparatus used to prepare the transition layer powder for 48 hours.

[0125] (II) The transition layer 3 slurry is coated on the inner and outer surfaces of the alumina ceramic tube 4, with a coating thickness of 0.03 mm; after drying and sintering, a composite ceramic tube is obtained; the drying temperature is 60℃ and the time is 12h.

[0126] The sintering is a continuous sintering process carried out in a continuous sintering furnace under a wet hydrogen atmosphere at a water temperature of 30°C. Along the direction of movement of the sintered sample, the continuous sintering furnace includes four temperature zones: a first temperature zone, a second temperature zone, a third temperature zone, and a fourth temperature zone. Each temperature zone contains eight sintering boats, with one boat being advanced every 18 minutes. The temperature of the first temperature zone is 450°C, the temperature of the second temperature zone is 850°C, the temperature of the third temperature zone is 1250°C, and the temperature of the fourth temperature zone is 1450°C.

[0127] The method for preparing the Langmuir probe structure described in this embodiment includes the following steps:

[0128] (1) Copper foil brazing filler is wrapped around the outer layer of the tungsten probe 1 and then assembled into the inner cavity of the composite ceramic tube so that the tungsten probe 1 and the composite ceramic tube are tightly fitted by the copper foil brazing filler.

[0129] (2) Copper foil brazing filler metal is wrapped around the outer layer of the composite ceramic tube and then assembled into the inner cavity of the tungsten heat shield 5 so that the tungsten heat shield 5 and the composite ceramic tube are tightly fitted by the copper foil brazing filler metal.

[0130] (3) Under hydrogen atmosphere, the Langmuir probe structure was obtained by sintering at 1100℃ for 15 min.

[0131] Example 7

[0132] This embodiment provides a Langmuir probe structure, which includes a tungsten probe 1, a composite ceramic tube, and a tungsten heat shield 5 arranged radially from the inside to the outside.

[0133] A copper-based solder layer 2 is independently provided between the composite ceramic tube and the tungsten probe 1, and between the composite ceramic tube and the tungsten heat shield 5; the material of the copper-based solder layer 2 is copper foil solder.

[0134] The composite ceramic tube includes an alumina ceramic tube 4 and a transition layer 3 disposed on the inner and outer sides of the alumina ceramic tube 4.

[0135] The tungsten probe 1 has a diameter of 3.1 mm; the alumina ceramic tube 4 has an inner diameter of 3.2 mm and a wall thickness of 0.5 mm; and the tungsten heat shield 5 has an inner diameter of 4.2 mm.

[0136] The raw materials for preparing the transition layer 3 include transition layer powder and binder; the binder accounts for 35% of the mass of the transition layer powder.

[0137] The transition layer powder is prepared from raw materials consisting of 80 wt% tungsten, 6 wt% manganese oxide, 9 wt% silicon dioxide, and 5 wt% aluminum oxide. The preparation method includes the following steps: ball milling tungsten, manganese oxide, silicon dioxide, and aluminum oxide according to the formula to obtain the transition layer powder; the ball-to-material ratio is 1.5:1, and the milling time is 45 hours.

[0138] The adhesive is prepared by the following steps: 85% α-terpineol and 15% ethyl cellulose (Maclean, AR) are mixed at a mass percentage, heated in a water bath and ultrasonically treated for 24 hours to make the terpineol and ethyl cellulose uniformly mixed.

[0139] The composite ceramic tube was prepared using the following method:

[0140] (I) Ball milling is used to mix the binder and the transition layer powder to obtain the transition layer slurry;

[0141] Ball milling and mixing continued in the ball milling apparatus used to prepare the transition layer powder for 45 hours.

[0142] (II) The transition layer 3 slurry is coated on the inner and outer surfaces of the alumina ceramic tube 4, with a coating thickness of 0.04 mm; after drying and sintering, a composite ceramic tube is obtained; the drying temperature is 80℃ and the time is 10 h.

[0143] The sintering is a continuous sintering process carried out in a continuous sintering furnace under a wet hydrogen atmosphere at a water temperature of 35°C. Along the direction of movement of the sintered sample, the continuous sintering furnace includes four temperature zones: a first temperature zone, a second temperature zone, a third temperature zone, and a fourth temperature zone. Each temperature zone contains eight sintering boats, with one boat being advanced every 12 minutes. The temperature of the first temperature zone is 500°C, the temperature of the second temperature zone is 900°C, the temperature of the third temperature zone is 1300°C, and the temperature of the fourth temperature zone is 1500°C.

[0144] The method for preparing the Langmuir probe structure described in this embodiment includes the following steps:

[0145] (1) Copper foil brazing filler is wrapped around the outer layer of the tungsten probe 1 and then assembled into the inner cavity of the composite ceramic tube so that the tungsten probe 1 and the composite ceramic tube are tightly fitted by the copper foil brazing filler.

[0146] (2) Copper foil brazing filler metal is wrapped around the outer layer of the composite ceramic tube and then assembled into the inner cavity of the tungsten heat shield 5 so that the tungsten heat shield 5 and the composite ceramic tube are tightly fitted by the copper foil brazing filler metal.

[0147] (3) Under hydrogen atmosphere, the Langmuir probe structure was obtained by sintering at 1170℃ for 5 min.

[0148] Comparative Example 1

[0149] This comparative example provides a Langmuir probe structure, which is the same as in Example 5 except that the raw materials for preparing the transition layer powder consist of 70 wt% tungsten, 10.6 wt% manganese oxide, 13.8 wt% silicon dioxide and 5.6 wt% aluminum oxide.

[0150] Comparative Example 2

[0151] This comparative example provides a Langmuir probe structure, which is the same as in Example 5 except that the raw materials for preparing the transition layer powder consist of 90 wt% tungsten, 3 wt% manganese oxide, 4.5 wt% silicon dioxide and 2.5 wt% aluminum oxide.

[0152] Comparative Example 3

[0153] This embodiment provides a Langmuir probe structure, which is identical to that of Embodiment 5 except that the copper foil solder is replaced with nickel solder.

[0154] Since the melting point of nickel is 1455°C, the temperature of step (3) needs to be increased to above 1455°C. At this temperature, the structure of the transition layer will be destroyed and the transition layer will not be able to play its role.

[0155] Performance Characterization

[0156] The electrical properties and high thermal load performance of the Langmuir probe structures obtained in Examples 1-7 and Comparative Examples 1-3 were tested, and the results are shown in Table 1.

[0157] The electrical performance testing method is as follows: the prepared Langmuir probe is ultrasonically cleaned with anhydrous ethanol, dried, and then the voltage is increased to 600V in an insulation withstand voltage tester for 60s, held for 60s, and the resistance value is tested.

[0158] The test method for high thermal load performance of electron beams is as follows: the prepared Langmuir probe structure is welded onto a water-cooled module, and an energy level of 12 MW·m is used. -2 The probe head was bombarded with an electron beam for 3000 times. Its resistance value was then tested, and the appearance was observed for any cracks.

[0159] Table 1

[0160]

[0161]

[0162] In summary, the Langmuir probe structure provided by this invention is a tungsten probe-copper-based solder layer-transition layer-ceramic tube-transition layer-copper-based solder layer-heat shield structure. The transition layer powder contains more than 75 wt% tungsten, forming a tungsten skeleton during the preparation process. This facilitates the solder's infiltration into the tungsten skeleton to form a dense connection, while also wetting the tungsten material. The Langmuir probe provided by this invention has the advantages of high structural strength and strong resistance to high heat loads.

[0163] The above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A Langmuir probe structure, characterized in that, The Langmuir probe structure includes a tungsten probe, a composite ceramic tube, and a heat shield arranged radially from the inside out. A copper-based solder layer is independently provided between the composite ceramic tube and the tungsten probe, and between the composite ceramic tube and the heat insulation screen. The composite ceramic tube includes a ceramic tube and a transition layer disposed on the inner and outer surfaces of the ceramic tube; The raw materials for preparing the transition layer include transition layer powder and binder; The raw materials for preparing the transition layer powder include tungsten, manganese oxide, silicon dioxide, and aluminum oxide; The raw materials for preparing the transition layer powder contain tungsten of 75 wt% or more, and the mass ratio of tungsten to manganese oxide is 8:1 to 20:

1. The transition layer powder, by mass percentage, consists of 75 wt% to 85 wt% tungsten, 4.5 wt% to 7.5 wt% manganese oxide, 6.75 wt% to 11.25 wt% silicon dioxide, and 3.75 wt% to 6.25 wt% aluminum oxide.

2. The Langmuir probe structure according to claim 1, characterized in that, The binder comprises alcohol solvents and cellulose.

3. The Langmuir probe structure according to claim 1, characterized in that, The binder comprises 5 wt% to 15 wt% cellulose by weight percentage.

4. The Langmuir probe structure according to claim 1, characterized in that, The binder comprises 33% to 35% of the mass of the transition layer powder.

5. The Langmuir probe structure according to claim 1, characterized in that, The diameter of the tungsten probe is 3 mm to 3.1 mm.

6. The Langmuir probe structure according to claim 1, characterized in that, The ceramic tube has an inner diameter of 3.1 mm to 3.2 mm and a wall thickness of 0.4 mm to 0.5 mm.

7. The Langmuir probe structure according to claim 1, characterized in that, The inner diameter of the heat insulation screen is 4.1 mm to 4.2 mm.

8. The Langmuir probe structure according to claim 1, characterized in that, The composite ceramic tube was prepared using the following method: (I) Mix the binder and transition layer powder according to the formula to obtain the transition layer slurry; (II) The transition layer slurry is coated on the inner and outer surfaces of the ceramic tube, and then dried and sintered in sequence to obtain the composite ceramic tube.

9. The Langmuir probe structure according to claim 8, characterized in that, The mixing method described in step (I) includes ball milling.

10. The Langmuir probe structure according to claim 8, characterized in that, The coating thickness in step (II) is 0.03 mm to 0.04 mm.

11. The Langmuir probe structure according to claim 8, characterized in that, The drying temperature in step (II) is 60°C to 80°C.

12. The Langmuir probe structure according to claim 8, characterized in that, The drying time in step (II) is 10 to 12 hours.

13. The Langmuir probe structure according to claim 8, characterized in that, The sintering in step (II) is carried out in a wet hydrogen atmosphere with a water temperature of 30°C to 35°C.

14. A method for preparing a Langmuir probe structure as described in any one of claims 1-13, characterized in that, The preparation method includes the following steps: (1) A copper-based solder layer is wrapped around the outer layer of the tungsten probe and then assembled into the inner cavity of the composite ceramic tube so that the tungsten probe and the composite ceramic tube are tightly fitted through the copper-based solder layer. (2) A copper-based brazing layer is wrapped around the outer layer of the composite ceramic tube, and then assembled into the inner cavity of the heat insulation screen so that the heat insulation screen and the composite ceramic tube are tightly fitted through the copper-based brazing layer. (3) Sintering is carried out under a reducing atmosphere to obtain the Langmuir probe structure.

15. The preparation method according to claim 14, characterized in that, The sintering temperature in step (3) is 1100℃ to 1170℃.

16. The preparation method according to claim 14, characterized in that, The sintering time in step (3) is 5 to 15 minutes.

17. The preparation method according to claim 14, characterized in that, The preparation method includes the following steps: (1) Copper foil brazing filler is wrapped around the outer layer of the tungsten probe and then assembled into the inner cavity of the composite ceramic tube so that the tungsten probe and the composite ceramic tube are tightly fitted by the copper foil brazing filler. (2) Copper foil brazing filler metal is wrapped around the outer layer of the composite ceramic tube and then assembled into the inner cavity of the heat insulation screen so that the heat insulation screen and the composite ceramic tube are tightly fitted by the copper foil brazing filler metal. (3) Under reducing atmosphere conditions, the Langmuir probe structure is obtained by sintering at 1100℃ to 1170℃ for 5 min to 15 min.

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