CN106424739A - Yttrium oxide-tungsten gradient material, preparation method thereof and application of tungsten-yttrium oxide gradient material in manufacturing of crucible for smelting strong-corrosivity alloy - Google Patents

Abstract

The invention relates to an yttrium oxide-tungsten gradient material, a preparation method thereof and an application in manufacturing a crucible for smelting highly corrosive alloys. The gradient material includes an yttrium oxide layer and a plurality of transition layers, and the volume fractions of yttrium oxide and tungsten in the mth transition layer are according to C _Wm = 1‑C _Ym and Calculation, where C _Ym and C _Wm are respectively the volume fraction of yttrium oxide and tungsten in the m transition layer; m is a natural number from 1 to (n-1); l is the total thickness of the multiple transition layers; n is The total number of layers of the yttrium oxide layer and each transition layer is n≥3; H _i is the thickness of the i-th layer, and H _m is the thickness of the m-th transition layer. The method includes weighing required tungsten powder and yttrium oxide powder; using each powder to pave corresponding layers in a mould, and performing molding and sintering. The invention also provides the application of the gradient material in manufacturing crucibles for smelting highly corrosive alloys. The gradient material has good resistance to alloy melt erosion, thermal shock resistance and wear resistance, and can be widely used in smelting highly corrosive alloys. The method has the advantages of simple process, low energy consumption, and environmental friendliness. .

Description

Yttrium oxide-tungsten gradient material and its preparation method and in the manufacture of strong corrosive alloy melting Application in refining crucible

technical field

The invention belongs to the field of materials, in particular, the invention relates to a yttrium oxide-tungsten gradient material and its preparation method and its application in the manufacture of a crucible for smelting highly corrosive alloys

technical background

With the development of science, some metals and alloy materials with special properties are widely used in the automobile industry, aerospace, electrical and electronics, chemical industry, petroleum, national defense and military industry, etc. Including magnesium alloy, aluminum alloy, nickel alloy, copper alloy, uranium alloy, etc. For these alloy materials, high purity is required during use to ensure performance. Therefore, the smelting of alloys has important national value. Melting methods often use water-cooled copper crucibles or graphite crucibles to melt alloys under the protection of inert gases, but water-cooled copper crucibles will take away a lot of heat, resulting in waste of energy, and the thermal field is uneven, and the alloy structure is difficult to control. The use of a graphite crucible will increase the carbon content of the alloy and form a large-scale brittle layer, thereby reducing the purity and performance of the alloy. Therefore, it is necessary to find a new method of melting alloys to change the status quo.

For example, molten Ti alloy has extremely high chemical activity and reacts with almost all refractory materials, such as MgO, Al ₂ O ₃ , SiO ₂ , ZrO ₂ , etc., will react violently with liquid titanium, so they are not suitable As a refractory material for melting titanium alloys. Condon JB et al. studied the coating of nearly 50 kinds of ceramic materials (including metal oxides, nitrides, carbides, borides, silicides), and designed a superalloy melting reactivity experiment. Most of the metal oxides are in the alloy reaction. maintained good chemical stability. Among them, the Y ₂ O ₃ coating has the best alloy corrosion resistance and the best thermal stability. Zhang Xian, Cheng Laifei and others performed thermodynamic calculations on the chemical reactions between Y ₂ O ₃ , CaO, BeO, Ce ₂ O ₃ , MgO, ZrO ₂ and other coating or lining materials and metals at high temperatures. _The results show that in the temperature range _of 1200K～1900K, Y ₂ O ₃ , CaO, BeO and Ce ₂ O ₃ will not chemically react with the superalloy, and have good thermochemical stability. The stability is the best, followed by CaO, BeO and Ce ₂ O ₃ , and MgO can react when it is close to 1600K. However, Y2O3 has a large thermal expansion coefficient and low high _- temperature mechanical properties, so pure _Y2O3 cannot meet the application requirements as a high-temperature alloy melting crucible material.

Pure W has high thermal conductivity, low thermal expansion coefficient, excellent corrosion resistance, thermal shock resistance and neutron radiation resistance. However, as a melting crucible material, due to the interdiffusion between metals, it will inevitably have a certain impact on the melting and concentration of the alloy.

Toshiba Corporation of Japan has developed a WY ₂ O ₃ composite material. This material has high strength and high corrosion resistance and is used to melt rare earth metals. Compared with ordinary graphite crucibles, the service life of composite crucibles is 10 times longer. times; within 1000°C, the flexural strength reaches 800MPa, more than 5 times that of pure W, and the content of rare earth metal impurities after smelting drops to one-tenth. However, the WY ₂ O ₃ composite material developed by Toshiba Corporation in Japan produces high thermal stress during the preparation and service of the transfer material, which leads to insufficient thermal shock resistance and erosion resistance.

Chinese patent application CN200910046508.4 discloses a crucible for melting titanium. The crucible is coated with a composite coating on the inner surface of the graphite crucible. The composite coating has a three-layer structure of an inner layer, a transitional gradient coating and an outer layer. The inner layer is a thin SiC layer, the transition layer is composed of one of high temperature stable compound yttrium oxide, calcium zirconate or cerium sulfide and one of refractory metal tungsten, molybdenum or tantalum, the outer layer is high temperature stable compound yttrium oxide, One of calcium zirconate or cerium sulfide, the transition gradient coating is composed of powder of one of high-temperature stable compound yttrium oxide, calcium zirconate or cerium sulfide and one of refractory metal tungsten, molybdenum or tantalum The powder is mixed in different mass ratios and prepared by thermal spraying method (laser cladding, plasma spraying, etc.), from the inside to the outside, based on the mass ratio of high-temperature stable compounds and refractory metals, the first sub-layer is 1: 3. The second sublayer is 1:1, and the third sublayer is 3:1. However, this crucible is based on graphite and needs to be coated with a thin layer of SiC on the inner layer, so it cannot be used for melting metals or alloys sensitive to C. In addition, the proportion of high-temperature stable oxide and refractory metal in the sub-three layers of the transition layer in the crucible is only a simple increase and decrease, and the optimal matching of the thermal stress of the target material is not achieved by optimizing the gradient distribution function of the target material. Therefore, there are still obvious interlayer interfaces between the inner layer, the transition gradient coating and the outer layer, and between the sub-tertiary layers, resulting in thermal stress mismatch phenomenon generated during preparation and use, and reducing the stability of the entire material component. Thermomechanical properties especially reduce the thermal shock resistance of the component.

It is speculated that _Y2O3 and W used in the present invention have good compatibility at high temperature, and during the sintering process _of metal W, _{Y2O3 acts} as a dispersed phase and has a pinning effect, which hinders the high temperature of tungsten The recovery and recrystallization process increases the recrystallization temperature, inhibits the growth of tungsten grains, improves the high-temperature strength and creep resistance of tungsten, improves the low-temperature ductility of tungsten, and reduces the ductile-brittle transition temperature of tungsten. In order to further improve the service temperature and the refining purity of superalloys, and take into account the thermal shock resistance and corrosion resistance, the present invention proposes the use of a Y ₂ O ₃ -W gradient material with a layered gradient transition structure to meet the above performance requirements . Y ₂ O ₃ -W gradient materials can give full play to the high temperature thermochemical stability of Y ₂ O ₃ ceramics and the advantages of high strength and high thermal conductivity of W metal; and Y ₂ O ₃ -W gradient materials with layered gradient transition structure It can effectively relieve and transfer the thermal stress generated in the process of material preparation and service, thereby prolonging the service life of the material.

The material prepared by the invention can be widely used in the field of smelting highly corrosive alloys, has good thermal shock resistance and corrosion resistance, has a simple preparation process, low energy consumption, and is environmentally friendly, and has broad industrial application prospects.

Contents of the invention

The present invention provides a yttrium oxide-tungsten gradient material in a first aspect, the gradient material includes a yttrium oxide layer and a plurality of transition layers, and the yttrium oxide layer is located in the transition layer with the largest yttrium oxide content. One side of the layer, counting from the side of the layer with the largest tungsten content in the multiple transition layers, the multiple transition layers include the 1st, 2nd, ..., n-1 layers, the yttrium oxide layer Be the nth layer; the volume fraction of the yttrium oxide of the mth transition layer and the volume fraction of tungsten in the multiple transition layers are calculated according to the following formula:

C _Wm ＝1-C _Ym (2)

in:

C _Ym is the volume fraction of the yttrium oxide in the mth transition layer; C _Wm is the volume fraction of the tungsten in the m transition layer; m is the natural number of 1 to (n-1); 1 is described a plurality of transition layers The total thickness; n is the total number of layers of the yttrium oxide layer and each transition layer and n≥3; H _i is the thickness of the i-th layer, and H _m is the thickness of the m-th transition layer.

In a second aspect, the present invention provides a method for preparing the gradient material described in the first aspect of the present invention, said method comprising the steps of:

(a) According to the size and the number of layers of the gradient material, take the required tungsten powder and yttrium oxide powder;

(b) Use yttrium oxide powder and composite powder composed of yttrium oxide powder and tungsten powder, and tungsten powder to lay up the yttrium oxide layer, the transition layer and the tungsten layer respectively in the mold to form a composite material layup green body, and lay the layers Simultaneously or after forming and sintering, the gradient material is thus produced.

The third aspect of the present invention also provides the application of the gradient material described in the first aspect or the gradient material prepared by the method described in the second aspect in the manufacture of a crucible for smelting highly corrosive alloys.

After the gradient material of the present invention undergoes 10 to 20 cyclic thermal shocks at 1200 to 1600 ° C, the material does not have interlayer peeling and fracture failure; and the material can resist instantaneous laser heat with a power of 50 to 80 MW/ ^m2 . Impact, the surface of the material has no obvious damage under the in-situ irradiation of plasma with an online average electron density of 1-1.5×10 ¹³ /cm ³ , and its performance meets the service performance of alloy melting crucible materials. The invention ensures that the prepared gradient material has good ablation resistance, improves the thermal shock resistance and high-temperature mechanical properties of the composite material, avoids the pollution of the highly corrosive alloy during the smelting process, and can be widely used in the smelting of the highly corrosive alloy It is especially suitable for manufacturing multifunctional melting crucibles, especially the core parts of crucibles for smelting highly corrosive alloys. The invention has the advantages of simple process, low energy consumption, environmental friendliness and broad industrial application prospect.

Description of drawings

1 is a schematic diagram of an embodiment of the gradient material of the present invention, the uppermost layer (the layer in contact with, for example, a highly corrosive alloy metal or alloy to be smelted) is an yttrium oxide layer (i.e. the nth layer, in this embodiment n=9, i.e. the 9th layer), the transition layer comprises n-1 layer i.e. 8 layers, and the calculation from bottom to top is successively the 1st layer, the 2nd layer, ..., the n-1th layer (i.e. the 8th layer) , the lowermost side is the tungsten-rich side of the transition layer, and the opposite side of the tungsten-rich side in the transition layer is the yttrium oxide-rich side.

detailed description

As mentioned above, the present invention provides a yttrium oxide-tungsten gradient material in the first aspect, the gradient material includes a yttrium oxide layer and a plurality of transition layers, and the yttrium oxide layer is located in the plurality of transition layers The side of the layer with the largest yttrium oxide content is counted from the side of the layer with the largest tungsten content in the multiple transition layers, and the multiple transition layers include the 1st, 2nd, ..., n-1 layers, The yttrium oxide layer is the nth layer; the volume fraction of yttrium oxide and the volume fraction of tungsten in the mth transition layer in the plurality of transition layers are calculated according to the following formula:

C _Wm ＝1-C _Ym (2)

in:

C _Ym is the volume fraction of the yttrium oxide in the mth transition layer; C _Wm is the volume fraction of the tungsten in the m transition layer; m is the natural number of 1 to (n-1); 1 is described a plurality of transition layers Total thickness; n is the total number of layers of the yttrium oxide layer and each transition layer and n≥3; H _i is the thickness of the i-th layer, H _m is the thickness of the m-th transition layer, x _m is as shown in formula (3) , that is, the distance between the middle position of the mth transition layer in the thickness direction and the outer surface (the surface away from the yttrium oxide layer) of the layer with the largest tungsten content among the plurality of transition layers.

The present invention is based on the requirements of the size of the crucible material, thermal stress matching, thermal shock resistance and alloy corrosion resistance, and also fully considers the properties of yttrium oxide and tungsten materials, and calculates each transition according to the above formulas (1) to (3). The amount and distribution of yttrium oxide and tungsten in the layer are used to prepare a gradient material that meets the expected performance requirements.

In some preferred embodiments, the total number of layers of the gradient material is 3≤n≤15, for example, n is 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13 , 14 or 15, and for example, 5≤n≤11 or 5≤n≤10.

The present invention has no particular limitation on the thickness of each layer in the transition layer, as long as the gradient material can have expected performance. But preferably, the thickness of each layer in the transition layer can be independently 0.5mm to 3mm and all values or sub-ranges in between, such as 0.5mm, 1.0mm, 1.1mm, 1.2mm, 1.3mm, 1.4 mm, 1.5cm, 1.6mm, 1.7mm, 1.8mm, 1.9mm, 2.0mm, 2.1mm, 2.2mm, 2.3mm, 2.4mm, 2.5mm, 2.6mm, 2.7mm, 2.8mm, 2.9mm or 3.0mm.

The present invention has no particular limitation on the thickness of the yttrium oxide layer, as long as the gradient material can have expected performance. Preferably, however, the thickness of the yttrium oxide layer may independently be 0.5 mm to 3 mm and all values or subranges therebetween, such as 0.5 mm, 1.0 mm, 1.1 mm, 1.2 mm, 1.3 mm, 1.4 mm, 1.5 cm, 1.6mm, 1.7mm, 1.8mm, 1.9mm, 2.0mm, 2.1mm, 2.2mm, 2.3mm, 2.4mm, 2.5mm, 2.6mm, 2.7mm, 2.8mm, 2.9mm or 3.0mm. .

In some optional implementation manners, the gradient material may further include a tungsten layer on the tungsten-rich side. The present invention has no particular limitation on the thickness of the tungsten layer, and the thickness of the tungsten layer can be 0.01mm to 3.0mm and all values or sub-ranges therebetween, such as 0mm, 0.01mm, 0.05mm, 0.1mm, 0.2 mm, 0.3mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, 1.0mm, 1.1mm, 1.2mm, 1.3mm, 1.4mm, 1.5mm, 1.6mm, 1.7mm, 1.8mm, 1.9mm, 2.0mm, 2.1mm, 2.2mm, 2.3mm, 2.4mm, 2.5mm, 2.6mm, 2.7mm, 2.8mm, 2.9mm or 3.0mm.

In some embodiments, the tungsten, such as tungsten in the tungsten layer (if present), or such as tungsten in the transition layer (not counting the yttrium oxide in the transition layer), which The purity may independently be 90% by mass or higher, such as 90, 91, 92, 93, 94, 95, 96, 97, 98, 99 or 99.9% by mass, preferably 98% by mass or higher.

In some other embodiments, the purity of the yttrium oxide, for example, the yttrium oxide in the yttrium oxide layer or the yttrium oxide in the transition layer (the tungsten in the transition layer is not counted) can independently be 90 mass % or more, for example, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99 or 99.9 mass % or more, preferably 98 mass % or more.

In a second aspect, the present invention provides a method for preparing the gradient material described in the first aspect of the present invention, the method comprising the following steps:

(a) According to the size and the number of layers of the gradient material, take the required tungsten powder and yttrium oxide powder;

(b) Use yttrium oxide powder and composite powder composed of yttrium oxide powder and tungsten powder in a mold (such as a graphite mold), and tungsten powder is used to lay up an yttrium oxide layer, a transition layer and a tungsten layer respectively to form a composite material laminated body , and molding and sintering are carried out at the same time as or after lamination, thereby preparing the gradient material.

In some embodiments, the particle size of the tungsten powder used to form the tungsten layer (if any) and the particle size of the tungsten powder used to form the transition layer are independently 0.1 μm to 10 μm, for example 0.1 μm , 0.2, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10 μm.

In other embodiments, the particle size of the yttrium oxide powder used to form the yttrium oxide layer and the particle size of the yttrium oxide powder used to form the transition layer are independently 0.1 μm to 8 μm, for example, 0.1, 0.2 , 0.5, 1, 2, 3, 4, 5, 6, 7 or 8 μm.

In some embodiments, the composite powder can be prepared by ball milling wet mixing, wherein the dispersion medium and the dispersant are used as the mixing medium, and the mixing time is 6 hours to 24 hours (such as 6, 12, 18 or 24 hours), Then, for example, the mixed medium is removed by evaporating the mixed medium such as ethanol in an open drying oven or a vacuum distillation system to obtain a mixed powder, and then the mixed powder is passed through a 120-mesh sieve to obtain a uniformly mixed composite powder.

The present invention has no special limitation on the dispersion medium and dispersant used in ball milling wet mixing, but in some preferred embodiments, the dispersion medium can be selected from the group consisting of water, ethanol, methanol and xylene. In the present invention, there is no special limitation on the amount of the dispersion medium, as long as it can disperse the yttrium oxide powder and tungsten powder to be dispersed. In other embodiments, the dispersant may be selected from the group consisting of polyethylene, polyacrylic acid, glycerin, and copolymers formed by copolymerization of polycarboxylic acid and polysiloxane. In the present invention, there is no special limitation on the amount of the dispersion medium, as long as it can disperse the yttrium oxide powder and/or tungsten powder to be dispersed. However, in some preferred embodiments, the concentration of the dispersant in the dispersion liquid may be 0.5 mol% to 3 mol%, such as 0.5, 1, 2, or 3 mol%.

In some optional embodiments, the composite powder can be prepared by ball milling dry mixing, wherein ceramic balls or cemented carbide balls are used as the mixing medium, and the mixing time is 12 hours to 48 hours (for example, 12, 18, 24 , 30, 36, 42 or 48 hours), and then passed through a 120 mesh sieve to obtain a uniformly mixed composite powder.

Optionally, the composite powder can be granulated after preparation to achieve better shaping.

In some embodiments where layup, shaping and sintering are achieved simultaneously, the composite layup body can be laid up with respective powders for the respective layers by means of a plasma spraying equipment equipped with a powder feeder . The working pressure of the spray gun of the plasma spraying equipment can be 0.1～0.5MPa (such as 0.1, 0.2, 0.3, 0.4 or 0.5MPa), and the moving speed of the spray gun can be 20～50mm/s (such as 20mm/s, 30mm/s s, 40mm/s or 50mm/s), the powder feeding rate of the powder feeder can be 5-20g/min (such as 5, 10, 15 or 20g/min), and the spraying temperature can be 1600-2000℃ or in between Any numerical value or range, for example, 1600, 1700, 1800, 1900 or 2000° C., thereby realizing forming and sintering while laying layers.

In an embodiment in which layer laying, molding and sintering are performed sequentially, the layer laying can be done by hand laying, tape casting and the like. For example, in the case of tape laying, it can be laid by casting at room temperature, then dried at 80 to 150°C (80, 90, 100, 110, 120, 130, 140, or 150°C), and Debinding is carried out at 120-350° C. (120, 150, 200, 250, 300 or 350° C.), so as to lay the composite material ply body. Then, the green body is formed and sintered in sequence. The molding can be realized by cold pressing at room temperature and/or cold isostatic pressing. The pressure of the room temperature cold pressing can be 5 to 50 MPa, for example, 5, 10, 20, 25, 30, 35, 40, 45 or 50 MPa. The pressure of the cold isostatic pressing may be 50-200 MPa (for example, 50, 100, 150 or 200 MPa). Sintering can be performed by hot-press sintering or pressureless sintering. The sintering temperature of hot-press sintering can be 1600-2000°C or any value or range in between, such as 1600, 1700, 1800, 1900 or 2000°C. One-way pressure or two-way pressure can be used during hot-press sintering Pressurization, the applied pressure is 10MPa to 50MPa or any value or range therebetween, such as 10, 20, 30, 40 or 50MPa, and the sintering holding time is 1 hour to 5 hours, such as 1, 2, 3, For 4 or 5 hours, the cooling rate is 5°C/min to 10°C/min, such as 5, 6, 7, 8, 9 or 10°C/min, and the sintering atmosphere can be argon, nitrogen or vacuum. The sintering temperature of the pressureless sintering can be any value or range between 1600°C and 2000°C, for example, 1600, 1700, 1800, 1900 or 2000°C. The holding time of pressureless sintering is 1 hour to 5 hours, such as 1, 2, 3, 4 or 5 hours, and the cooling rate is 5°C/min to 10°C/min, such as 5, 6, 7, 8, 9 or 10°C/min, the sintering atmosphere can be argon, nitrogen or vacuum.

In the third aspect, the present invention also provides the gradient material described in the first aspect or the gradient material prepared by the method described in the second aspect used in the manufacture of crucibles, such as crucibles for melting high-temperature metals or alloys, especially highly corrosive alloys Use the crucible application.

The present invention will be further described below by way of illustration, but these examples are only for the purpose of illustration, and should not be construed as limiting the protection scope of the present invention.

Example 1

The number of layers of the composite material is preset to be n=5, and the uppermost layer of the material is Y ₂ O ₃ layers with a thickness of 2 mm. The transition layer is 4 layers, and the thickness of each layer is 3mm. The average particle size is 1 μ m, the yttrium oxide powder of purity 98% and the average particle size are 0.2 μ m, the tungsten powder of purity 98% calculates the volume ratio of each transition layer according to the formula (1) to (3) above, transition layer is formed by The components of each layer from top to bottom are:

_91.0vol .% _Y2O3-9.0vol .%W, _72.0vol .% _Y2O3-28.0vol .%W,

_50.0vol .% _Y2O3-50.0vol .%W, _23.3vol .% _Y2O3-76.7vol .%W,

According to the pre-designed gradient structure, each powder is put into the graphite mold layer by layer, cold-pressed at room temperature, and the pressure is 5MPa; after 200MPa cold isostatic pressing, it is directly sintered in a vacuum hot-pressing sintering furnace to obtain Y ₂ O ₃ -W gradient material. The process parameters of vacuum pressureless sintering are: heat preservation at 1800°C for 1 hour, vacuum degree of 1.3×10 ^-2 Pa, and cooling rate of 5°C/min.

The density of the composite material reaches 97.0%, and the bending strength tested by the three-point bending method at room temperature is 451.0MPa. It can resist instantaneous laser thermal shock with a power of about 50MW/m ² , and there is no obvious damage to the surface of the material under the in-situ irradiation of plasma with an online average electron density of 1-1.5×10 ¹³ /cm ³ .

Example 2

The number of layers of the composite material is preset to be n=5, and the uppermost layer of the material is Y ₂ O ₃ layers with a thickness of 2 mm. The transition layer is 4 layers, and the thickness of each layer is 3mm. Calculate the volume ratio of the transition layer according to the formulas (1) to (3) above with the yttrium oxide powder with an average particle size of 1 μm and a purity of 98% and the tungsten powder with an average particle size of 0.2 μm and a purity of 98%. The components of the transition layer from top to bottom are:

_91.0vol .% _Y2O3-9.0vol .%W, _72.0vol .% _Y2O3-28.0vol .%W,

_50.0vol .% _Y2O3-50.0vol .%W, _23.3vol .% _Y2O3-76.7vol .%W,

Put the powder into the graphite mold layer by layer according to the pre-designed gradient structure, and cold press at room temperature with a pressure of 5 MPa. Then, direct hot-press sintering in a vacuum hot-press sintering furnace to prepare the Y ₂ O ₃ -W gradient material. The process parameters of the vacuum hot pressing sintering are: heat preservation at 1500°C for 1 hour, pressure at 30MPa, vacuum degree at 1.3×10 ^-2 Pa, and cooling rate at 10°C/min.

The density of the composite material reaches 98.0%, and the bending strength tested by the three-point bending method at room temperature is 465.5MPa. In a cyclic thermal shock furnace, after 10 cycles of thermal shock between 1200°C and 1600°C, the prepared Y ₂ O ₃ -W gradient material has no interlayer peeling and fracture failure, and its performance meets the requirements of the alloy Service performance of melting crucible materials.

Example 3

The number of layers of the composite material is preset to be n=5, and the uppermost layer of the material is Y ₂ O ₃ layers with a thickness of 2 mm. The transition layer is 4 layers, and the thickness of each layer is 3mm. Calculate the volume ratio of the transition layer according to the formulas (1) to (3) above with the yttrium oxide powder with an average particle size of 2 μm and a purity of 99% and the tungsten powder with an average particle size of 0.5 μm and a purity of 98%. The components of the transition layer from top to bottom are:

_91.0vol .% _Y2O3-9.0vol .%W, _72.0vol .% _Y2O3-28.0vol .%W,

_50.0vol .% _Y2O3-50.0vol .%W, _23.3vol .% _Y2O3-76.7vol .%W,

According to the volume content of the pre-designed transition layer, it is put into the powder feeder of thermal spraying one by one, and the powder is sprayed layer by layer by the plasma spraying process to prepare the Y ₂ O ₃ -W gradient material. The process parameters are: arc heating at 1600°C, the working pressure of the spray gun is 0.5-1.0MPa, the moving speed of the spray gun is 30mm/s, and the powder feeding volume of the powder feeder is 15g/min.

The density of the composite material reaches 95.7%, and the bending strength tested by the three-point bending method at room temperature can reach 443.0MPa. In a cyclic thermal shock furnace, after 10 cycles of thermal shock between 1200°C and 1600°C, the prepared Y ₂ O ₃ -W gradient material has no interlayer peeling and fracture failure, and its performance meets the requirements of the alloy Service performance of melting crucible materials.

Example 4

The number of layers of the composite material is preset to be n=9, and the uppermost layer of the material is Y ₂ O ₃ layers with a thickness of 2 mm. The transition layer is 8 layers, and the thickness of each layer is 1.5mm. Calculate the volume ratio of the transition layer according to the formulas (1) to (3) above with the yttrium oxide powder with an average particle size of 2 μm and a purity of 99% and the tungsten powder with an average particle size of 0.5 μm and a purity of 98%. The components of the transition layer from top to bottom are:

_95.6vol .% _Y2O3-4.4vol .%W, _86.5vol .% _Y2O3-13.5vol .%W,

_77.0vol .% _Y2O3-23.0vol .%W, _66.9vol .% _Y2O3-33.1vol .%W,

_56.1vol .% _Y2O3-43.9vol .%W, _44.3vol .% _Y2O3-55.7vol .%W,

_31.0vol .% _Y2O3-69.0vol .%W, _14.4vol .% _Y2O3-85.6vol .%W,

According to the pre-designed gradient structure, the powder is put into the graphite mold layer by layer, cold-pressed at room temperature, and the pressure is 5MPa; after 200MPa cold isostatic pressing, it is directly sintered without pressure in a vacuum hot-pressing sintering furnace to obtain Y ₂ O ₃ -W gradient material. The process parameters of vacuum pressureless sintering are: heat preservation at 1900°C for 1 hour, argon protection, and cooling rate of 10°C/min.

The density of the composite material reaches 98.6%, and the bending strength tested by the three-point bending method at room temperature is 487.0MPa. In a cyclic thermal shock furnace, after 15 cycles of thermal shock between 1200°C and 1600°C, the prepared Y ₂ O ₃ -W gradient material has no interlayer peeling and fracture failure, and its performance meets the alloy Service performance of melting crucible materials.

Example 5

The number of layers of the composite material is preset to be n=9, and the uppermost layer of the material is Y ₂ O ₃ layers with a thickness of 2 mm. The transition layer is 8 layers, and the thickness of each layer is 1.5mm. The yttrium oxide powder with an average particle size of 4 μm and a purity of 99% and the tungsten powder with an average particle size of 1 μm and a purity of 99% are used to calculate the volume ratio of the transition layer according to the above-mentioned formulas (1) to (3). The components of each layer from top to bottom are:

_95.6vol .% _Y2O3-4.4vol .%W, _86.5vol .% _Y2O3-13.5vol .%W,

_77.0vol .% _Y2O3-23.0vol .%W, _66.9vol .% _Y2O3-33.1vol .%W,

_56.1vol .% _Y2O3-43.9vol .%W, _44.3vol .% _Y2O3-55.7vol .%W,

_31.0vol .% _Y2O3-69.0vol .%W, _14.4vol .% _Y2O3-85.6vol .%W,

Put the powder into the graphite mold layer by layer according to the pre-designed gradient structure, and cold press at room temperature with a pressure of 5 MPa. Then, direct hot-press sintering in a vacuum hot-press sintering furnace to prepare the Y ₂ O ₃ -W gradient material. The process parameters of the vacuum hot pressing sintering are: heat preservation at 1600°C for 1 hour, pressure at 35MPa, argon protection, and cooling rate at 10°C/min.

The density of the composite material reaches 98.8%, and the bending strength tested by the three-point bending method at room temperature is 502.5MPa. It can resist instantaneous laser thermal shock with a power of about 60MW/m ² , and there is no obvious damage to the surface of the material under in-situ irradiation of plasma with an online average electron density of 1-1.5×10 ¹³ /cm ³ .

Example 6

The number of layers of the composite material is preset to be n=9, and the uppermost layer of the material is Y ₂ O ₃ layers with a thickness of 2 mm. The transition layer is 8 layers, and the thickness of each layer is 1.5mm. The yttrium oxide powder with an average particle size of 4 μm and a purity of 99% and the tungsten powder with an average particle size of 1 μm and a purity of 99% are used to calculate the volume ratio of the transition layer according to the above-mentioned formulas (1) to (3). The components of each layer from top to bottom are:

_95.6vol .% _Y2O3-4.4vol .%W, _86.5vol .% _Y2O3-13.5vol .%W,

_77.0vol .% _Y2O3-23.0vol .%W, _66.9vol .% _Y2O3-33.1vol .%W,

_56.1vol .% _Y2O3-43.9vol .%W, _44.3vol .% _Y2O3-55.7vol .%W,

_31.0vol .% _Y2O3-69.0vol .%W, _14.4vol .% _Y2O3-85.6vol .%W,

According to the volume content of the pre-designed transition layer, it is put into the powder feeder of thermal spraying one by one, and the powder is sprayed layer by layer by the plasma spraying process to prepare the Y ₂ O ₃ -W gradient material. The process parameters are: arc heating at 1700°C, the working pressure of the spray gun is 0.5-1.0MPa, the moving speed of the spray gun is 40mm/s, and the powder feeding volume of the powder feeder is 10g/min.

The density of the composite material reaches 97.0%, and the bending strength tested by the three-point bending method at room temperature is 472.5MPa. In a cyclic thermal shock furnace, after 15 cycles of thermal shock between 1200°C and 1600°C, the prepared Y ₂ O ₃ -W gradient material has no interlayer peeling and fracture failure, and its performance meets the alloy Service performance of melting crucible materials.

Example 7

The number of layers of the composite material is preset to be n=11, and the uppermost layer of the material is a Y ₂ O ₃ layer with a thickness of 2 mm. The transition layer is 10 layers, and the thickness of each layer is 1.2mm. Calculate the volume ratio of the transition layer according to the formulas (1) to (3) above with the yttrium oxide powder with an average particle size of 5 μm and a purity of 99.9% and the tungsten powder with an average particle size of 0.8 μm and a purity of 99%. The components of the transition layer from top to bottom are:

_96.5vol .% _Y2O3-3.5vol .%W, _89.2vol .% _Y2O3-10.8vol .%W,

_81.8vol .% _Y2O3-18.2vol .%W, _74.0vol .% _Y2O3-26.0vol .%W,

_65.8vol .% _Y2O3-34.2vol .%W, _57.2vol .% _Y2O3-42.8vol .%W,

_48.0vol .% _Y2O3-52.0vol .%W, _38.0vol .% _Y2O3-62.0vol .%W,

_26.5vol .% _Y2O3-73.5vol .%W, _12.3vol .% _Y2O3-87.7vol .%W,

Put the powder into the graphite mold layer by layer according to the pre-designed gradient structure, and cold press at room temperature with a pressure of 5 MPa. Then, directly carry out pressureless sintering in a vacuum hot-pressing sintering furnace to prepare Y ₂ O ₃ -W gradient material. The process parameters of the vacuum pressureless sintering are: heat preservation at 1850°C for 1 hour, vacuum degree of 1.2×10 ^-2 Pa, and cooling rate of 10°C/min.

The density of the composite material reaches 98.5%, and the bending strength tested by the three-point bending method at room temperature is 493.5MPa. In a cyclic thermal shock furnace, after 20 cycles of thermal shock between 1200°C and 1600°C, the prepared Y ₂ O ₃ -W gradient material has no interlayer peeling and fracture failure, and its performance meets the alloy Service performance of melting crucible materials.

Example 8

The number of layers of the composite material is preset to be n=11, and the uppermost layer of the material is a Y ₂ O ₃ layer with a thickness of 2 mm. The transition layer is 10 layers, and the thickness of each layer is 0.8mm. Calculate the volume ratio of the transition layer according to the formulas (1) to (3) above with the yttrium oxide powder with an average particle size of 5 μm and a purity of 99.9% and the tungsten powder with an average particle size of 0.8 μm and a purity of 99%. The components of the transition layer from top to bottom are:

_96.5vol .% _Y2O3-3.5vol .%W, _89.2vol .% _Y2O3-10.8vol .%W,

_81.8vol .% _Y2O3-18.2vol .%W, _74.0vol .% _Y2O3-26.0vol .%W,

_65.8vol .% _Y2O3-34.2vol .%W, _57.2vol .% _Y2O3-42.8vol .%W,

_48.0vol .% _Y2O3-52.0vol .%W, _38.0vol .% _Y2O3-62.0vol .%W,

_26.5vol .% _Y2O3-73.5vol .%W, _12.3vol .% _Y2O3-87.7vol .%W,

Put the powder into the graphite mold layer by layer according to the pre-designed gradient structure, and cold press at room temperature with a pressure of 5 MPa. Then, direct hot-press sintering in a vacuum hot-press sintering furnace to prepare the Y ₂ O ₃ -W gradient material. The process parameters of the vacuum hot pressing sintering are: heat preservation at 1600°C for 1 hour, pressure at 40MPa, vacuum degree at 1.2×10 ^-2 Pa, and cooling rate at 10°C/min.

The density of the composite material reaches 99.0%, and the bending strength tested by the three-point bending method at room temperature is 508.0MPa. In a cyclic thermal shock furnace, after 20 cycles of thermal shock between 1200°C and 1600°C, the prepared Y ₂ O ₃ -W gradient material has no interlayer peeling and fracture failure, and its performance meets the alloy Service performance of melting crucible materials.

Example 9

The number of layers of the composite material is preset to be n=11, and the uppermost layer of the material is a Y ₂ O ₃ layer with a thickness of 2 mm. The transition layer is 10 layers, and the thickness of each layer is 0.8mm. The yttrium oxide powder with an average particle size of 4 μm and a purity of 99.9% and the tungsten powder with an average particle size of 1 μm and a purity of 99% are used to calculate the volume ratio of the transition layer according to the above formulas (1) to (3). The components of each layer from top to bottom are:

_96.5vol .% _Y2O3-3.5vol .%W, _89.2vol .% _Y2O3-10.8vol .%W,

_81.8vol .% _Y2O3-18.2vol .%W, _74.0vol .% _Y2O3-26.0vol .%W,

_65.8vol .% _Y2O3-34.2vol .%W, _57.2vol .% _Y2O3-42.8vol .%W,

_48.0vol .% _Y2O3-52.0vol .%W, _38.0vol .% _Y2O3-62.0vol .%W,

_26.5vol .% _Y2O3-73.5vol .%W, _12.3vol .% _Y2O3-87.7vol .%W,

According to the pre-designed volume content of the transition layer, a tape casting process is used to prepare a composite material green body with a composition gradient change at room temperature. After drying at 115°C and debinding at 185°C, a composite body with gradient composition was prepared. Cold pressing at room temperature, the pressure is 200MPa. Then, directly carry out pressureless sintering in a vacuum hot-pressing sintering furnace to prepare Y ₂ O ₃ -W gradient material. The process parameters of the vacuum pressureless sintering are: heat preservation at 1600°C for 1 hour, pressure at 40MPa, vacuum degree at 1.2×10 ^-2 Pa, and cooling rate at 10°C/min.

The density of the composite material reaches 98.0%, and the bending strength tested by the three-point bending method at room temperature is 492.2MPa. It can resist instantaneous laser thermal shock with a power of about 70MW/m ² , and there is no obvious damage to the surface of the material under in-situ irradiation of plasma with an online average electron density of 1-1.5×10 ¹³ /cm ³ .

Example 10

The number of layers of the composite material is preset to be n=5, and the uppermost layer of the material is Y ₂ O ₃ layers with a thickness of 2 mm. The transition layer is 3 layers, and the thickness of each layer is 2mm. According to the order of calculation from the Y ₂ O ₃ layer, the volume ratio of yttrium oxide and tungsten in the first layer, the second layer and the third layer of the transition layer The order is 3:1, 1:1 and 1:3. The bottom layer is a tungsten layer with a thickness of 2 mm. The yttrium oxide powder with an average particle size of 1 μm and a purity of 98% and the tungsten powder with an average particle size of 0.2 μm and a purity of 98% are mixed according to the above volume ratio, and the components of each layer from top to bottom of the transition layer are as follows:

75.0vol.% Y ₂ O ₃ -25.0vol.% W,

50.0vol.% Y ₂ O ₃ -50.0vol.% W,

_25.0vol .% _Y2O3-75.0vol .%W,

Put the powder into the graphite mold layer by layer according to the pre-designed gradient structure, and cold press at room temperature with a pressure of 5 MPa. Then, direct hot-press sintering in a vacuum hot-press sintering furnace to prepare the Y ₂ O ₃ -W gradient material. The process parameters of the vacuum hot pressing sintering are: heat preservation at 1500°C for 1 hour, pressure at 30MPa, vacuum degree at 1.3×10 ^-2 Pa, and cooling rate at 10°C/min.

The density of the composite material reaches 90.4%, and the bending strength tested by the three-point bending method at room temperature is 230.1MPa. In a cyclic thermal shock furnace, after 8 cycles of thermal shock between 1200°C and 1600°C, the prepared Y ₂ O ₃ -W gradient material has interlayer peeling and fracture failure, and its performance cannot meet the requirements of alloys. Service performance of melting crucible materials.

Claims (10)

1. a kind of yittrium oxide-tungsten functionally gradient material (FGM), it is characterised in that：

The functionally gradient material (FGM) includes yttrium oxide layer and multiple transition zones, and the yttrium oxide layer is located at the oxygen in the plurality of transition zone Change the side of the layer of yttrium content maximum, the side of the layer of the W content maximum from the plurality of transition zone starts meter, described many Individual transition zone includes the 1st, 2 ..., n-1 layer, the yttrium oxide layer be；M transition zone in the plurality of transition zone The volume fraction of the volume fraction of yittrium oxide and tungsten is calculated according to equation below：

$C_{Ym}={\left(\frac{x_m}{l}\right)}^{0.7}---\left(1\right)$

C_Wm=1-C_Ym(2)

$x_m=\underset{i=1}{\overset{m}{\mathrm{\Σ}}}{H}_i-\frac{1}{2}{H}_m---\left(3\right)$

Wherein：

C_YmVolume fraction for the yittrium oxide in m transition zone；C_WmVolume fraction for the tungsten in m transition zone；M is 1 to (n- 1) natural number；L is the gross thickness of the plurality of transition zone；N is total number of plies and n >=3 of yttrium oxide layer and each transition zone；H_iFor I-th layer of thickness, H_mThickness for m transition zone.

2. functionally gradient material (FGM) according to claim 1, it is characterised in that：

The thickness of each layer in n layer of the functionally gradient material (FGM) is each independently 0.5mm to 3mm.

3. method according to claim 1 and 2, it is characterised in that：

The purity of the tungsten independently is more than 90 mass %, more than preferably 98 mass %；And/or

The purity of the yittrium oxide independently is more than 90 mass %, more than preferably 98 mass %.

4. functionally gradient material (FGM) according to any one of claim 1 to 3, it is characterised in that the functionally gradient material (FGM) is in the richness Tungsten side also includes tungsten layer, and the thickness of the tungsten layer is independently 0 to 3mm.

5. a kind of method for preparing functionally gradient material (FGM) any one of Claims 1-4, it is characterised in that methods described includes Following steps：

A () is according to size and the number of plies of the functionally gradient material (FGM), the tungsten powder needed for weighing and yttrium oxide powder；

B composite powder that () is constituted using yttrium oxide powder and by yttrium oxide powder and tungsten powder in a mold, tungsten powder are distinguished Laying yttrium oxide layer, transition zone and tungsten layer, form composite plys base substrate, and carry out while laying or afterwards molding And sintering, the functionally gradient material (FGM) is thus obtained.

6. method according to claim 5, it is characterised in that：

For forming the particle diameter of the tungsten powder of the tungsten layer and independently being for forming the particle diameter of the tungsten powder of the transition zone 0.1 μm to 10 μm；And/or

For forming the particle diameter of the yttrium oxide powder of the yttrium oxide layer and for forming the yttrium oxide powder of the transition zone Particle diameter independently is 0.1 μm to 8 μm.

7. the method according to claim 5 or 6, it is characterised in that the composite powder is obtained one of in the following way：

(1) wet ball-milling mode, using disperse medium and dispersant as blending agent, incorporation time is 6 hours to 24 hours, so Blending agent is removed afterwards so as to mixed-powder is obtained, then mixed-powder is crossed 120 mesh sieves, the composite powder being uniformly mixed End；

(2) the dry-mixed mode of ball milling, using Ceramic Balls or sintered carbide ball as blending agent, incorporation time is little to 48 for 12 hours When, then cross 120 mesh sieves, the composite powder being uniformly mixed.

8. method according to claim 7, it is characterised in that：

The disperse medium is selected from the group of water, ethanol, methanol and dimethylbenzene composition；And/or

The dispersant is selected from the copolymer composition of polyethylene, polyacrylic acid, glycerol and polycarboxylic acids and polysiloxanes Group, it is preferred that the concentration of the dispersant is 0.5mol% to 3mol%.

9. the method according to any one of claim 5 to 8, it is characterised in that：

Laying is carried out by manual laying method or the tape casting, the composite plys base substrate is obtained, then to described compound Material laying base substrate carries out room temperature cold moudling and/or isostatic cool pressing, then carries out hot pressed sintering or pressureless sintering；Or, lead to Cross plasma spraying equipment spraying to realize laying, molding and sintering；

Preferably：In the tape casting, composite plys blank is prepared at room temperature, then dry at 80 DEG C to 150 DEG C Dry, then dumping is carried out at 120 DEG C to 350 DEG C, so as to prepare composite plys base substrate；Or, in the cold moudling, The pressure for using is 5MP to 50MPa；Or, in the isostatic cool pressing, the pressure for using is 50MPa to 200MPa；Or, In the hot pressed sintering, it is unidirectional or Bidirectional-pressure that sintering temperature is 1600 to 2000 DEG C, pressuring method, and it is 10 to apply pressure To 50MPa, the sintered heat insulating time is that 1 to 5 hour, cooling degree rate is 5 to 10 DEG C/min, and sintering atmosphere is argon, nitrogen or true Empty；Or, in the pressureless sintering, it is 1 to 5 hour 1600 to 2000 DEG C, sintered heat insulating time that sintering temperature is, cooling degree Rate is 5 to 10 DEG C/min, and sintering atmosphere is nitrogen, argon or vacuum；Or, the work of the spray gun of the plasma spraying equipment Make pressure for 0.1～0.5MPa, the rate travel of spray gun is 20～50mm/s, the powder sending quantity of powder feeder is 5～20g/ minute, spray The temperature of painting is 1600～2000 DEG C.

10. functionally gradient material (FGM) according to any one of claim 1 to 4 or the side any one of claim 5 to 9 Application of the functionally gradient material (FGM) obtained in method in manufacture severe corrosive alloy melting crucible.