CN106623944A - Yttrium oxide-tungsten continuous gradient material, preparing method of yttrium oxide-tungsten continuous gradient material and application of yttrium oxide-tungsten continuous gradient material to alloy smelting - Google Patents

Abstract

The invention relates to a yttrium oxide-tungsten continuous gradient material, a preparation method thereof and an application in alloy smelting. The gradient material includes a tungsten layer with a thickness of _l0 , _an yttrium oxide layer with a thickness of l1, and a transition layer with a thickness of _l2 , and _l0 and _l1 are independently ≥0, and _l2 >0; the distance in the transition layer Volume fraction of yttrium oxide at the z position of the tungsten-rich facet and the volume fraction of tungsten Where l=l ₀ +l ₂ , p=0.4, l ₀ ≤z≤l. The method preferably adopts free sedimentation combined with cold pressing and sintering to form the transition layer. The invention also provides the application of the gradient material in metal smelting. After the gradient material of the present invention undergoes 10 to 20 cyclic thermal shocks at 1200 to 1600°C, no interlayer spalling or fracture failure occurs; it can resist instantaneous laser thermal shock of 50 to ^80MW /m2, and the online average electron density There is no obvious damage to the surface of the material under the in-situ irradiation of the plasma of 1-1.5×10 ¹³ /cm ³ . The method has the advantages of simple process, easy operation, low energy consumption, environmental friendliness and broad industrial application prospect.

Description

Yttrium oxide-tungsten continuous gradient material and its preparation method and its application in alloy melting application

technical field

The invention belongs to the field of materials, and in particular relates to a yttrium oxide-tungsten continuous gradient material, a preparation method thereof and an application in alloy smelting.

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. At present, consumable electrode electric arc furnaces are used in combination with forced water-cooled copper crucibles to smelt high-melting point alloys in industry. However, the smelting process will inevitably cause uneven thermal fields, resulting in uneven smelted alloy structures, high energy consumption, and low efficiency. Due to the advantages of high temperature resistance, good thermal shock resistance, easy processing and low price, graphite materials are widely used as crucible materials for melting superalloys. However, due to the high reactivity of the alloy in the molten state, it is easy to react with graphite and CO at high temperature to cause carbon pollution. In order to reduce this kind of pollution, the composite material system that combines the matrix and the lining coating is mostly used, but the research found that there are poor bonding between the matrix and the lining, and the resistance of the lining under high temperature environment or thermal shock conditions. It is difficult to balance thermal shock performance and corrosion resistance. The research on graphite crucibles also mainly focuses on the selection of coating materials and the exploration of spraying process.

Commonly used coating materials include refractory oxides (Al ₂ O ₃ , MgO, CaO, ZrO ₂ , Y ₂ O ₃ , YSZ (7-8% Y ₂ O ₃ )) and nitrides (TiN, ZrN , HfN), there are some carbides. 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. Stability is the best. However, Y ₂ O ₃ has a large coefficient of thermal expansion and low high-temperature mechanical properties, so pure Y ₂ O ₃ cannot meet the requirements for use as a material for melting crucibles for superalloys.

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.

In order to improve the use temperature and the refining purity of superalloys, and take into account the thermal shock resistance and corrosion resistance, the present invention proposes a powder sedimentation method to prepare a Y ₂ O ₃ -W gradient material with a continuous gradient transition structure to meet the above properties. Require. Compared with the gradient material prepared by the powder layer paving method mentioned in related reports, the Y ₂ O ₃ -W continuous gradient material prepared by the sedimentation method can effectively weaken or eliminate the interlayer interface between the gradient layers, thereby reducing the gradient material. The thermal stress mismatch phenomenon generated during preparation and use improves the thermomechanical properties of the entire component.

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

Contents of the invention

In order to overcome one or more of the above-mentioned problems in the prior art, the present invention provides a yttrium oxide-tungsten continuous gradient material in a first aspect, the gradient material includes a tungsten layer with a thickness of _l0 , a tungsten layer with a thickness of _l1 An yttrium oxide layer and a transition layer with a thickness of l ₂ , and l ₀ and l ₁ independently ≥ 0, l ₂ >0; the transition layer has a tungsten-rich surface and a yttrium oxide-rich surface and is located between the tungsten layer and the Between the yttrium oxide layers, the tungsten layer is located on the tungsten-rich side of the transition layer, and the yttrium oxide layer is located on the yttrium-rich side of the transition layer; the distance between the transition layer and the tungsten-rich The volume fraction of yttrium oxide at the z position of the face And the volume fraction of tungsten at the z position from the tungsten-rich surface in the transition layer Wherein, l=l ₀ +l ₂ , p=0.4, l ₀ ≤z≤l.

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:

The method comprises 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) using a third dispersion medium and a third dispersant to prepare a third dispersion for forming the transition layer, and using a first dispersion medium and a first dispersant to prepare a first dispersion for forming the tungsten layer , using a second dispersion medium and a second dispersant to prepare a second dispersion liquid for forming the yttrium oxide layer;

(c) sequentially allowing said first dispersion, said third dispersion and said second dispersion to settle in a mold and removing the liquid to form a settled body;

(d) drying the settled body, thereby making a prefabricated body; and

(e) Cold pressing and sintering the prefabricated green body, so as to obtain the gradient material.

The third aspect of the present invention provides the application of the gradient material according to the first aspect of the present invention or the gradient material prepared by the method according to the second aspect of the present invention in alloy smelting.

While ensuring that the prepared continuous gradient material has good ablation resistance, it also improves the thermal shock resistance and high-temperature mechanical properties of the composite material, avoids the pollution of precious metal and superalloy smelting, and is suitable for manufacturing the core of a multifunctional melting crucible part. The method of the invention also has the advantages of simple preparation process, short cycle, low cost, easy operation and the like.

Description of drawings

Fig. 1 is the illustrative schematic diagram of a settling device used when settling in the method of the present invention, wherein, 1 represents settling tube 1, H1 represents the height of settling tube 1, 2 represents settling tube 2, H2 represents the height of settling tube 2, 3 represents a valve, 4 represents a liquid discharge valve, 5 represents a mold, and the cross-sectional areas of the settling tube 1 and the settling tube 2 and the bottom of the mold are both s.

detailed description

As mentioned above, the present invention provides a continuous gradient material of yttrium oxide-tungsten in the first aspect, the gradient material comprises a tungsten layer with a thickness of _l0 , _a layer of yttrium oxide with a thickness of l1 and a transition layer with a thickness of _l2 layer, and l ₀ and l ₁ independently ≥ 0, l ₂ >0; the transition layer has a tungsten-rich surface and a yttrium oxide-rich surface and is located between the tungsten layer and the yttrium oxide layer, and the tungsten layer Located on the side of the tungsten-rich surface of the transition layer, the yttrium oxide layer is located on the side of the tungsten-rich surface of the transition layer; the volume of the yttrium oxide at the z position from the tungsten-rich surface in the transition layer Fraction And the volume fraction of tungsten at the z position from the tungsten-rich surface in the transition layer Wherein, l=l ₀ +l ₂ , p=0.4, l ₀ ≤z≤l.

The present invention fully considers the requirements of gradient material size, thermal stress matching, thermal shock resistance and alloy corrosion resistance, and also fully considers the properties of yttrium oxide and tungsten materials, according to with (where p=0.4) Calculate the dosage and distribution of yttrium oxide and tungsten, so as to prepare a gradient material with expected performance requirements.

The present invention has no special thickness for the transition layer, the tungsten layer and the yttrium oxide layer, but the thickness of the transition layer must be greater than 0, and the performance of the formed gradient material can meet the needs of the target use. . Regarding the thickness of the tungsten layer and the thickness of the yttrium oxide layer, they can be independently 0, that is to say, the tungsten layer and the yttrium oxide layer can be independently absent (ie neither exists or Neither exists), so that the gradient material only includes the transition layer or only the transition layer is formed. Accordingly, the gradient material may comprise or consist of the following layers: (1) the transition layer, the tungsten layer and the yttrium oxide layer; (2) the transition layer and the tungsten layer; (3) the transition layer and the yttrium oxide layer; (4) the transition layer.

The present invention has no particular limitation on the thickness of the transition layer, as long as the gradient material including the transition layer can have expected performance. For example, the thickness of the transition layer may be 0.1 cm to 2.0 cm and all values or sub-ranges therebetween, such as 0.1 cm, 0.2 cm, 0.3 cm, 0.4 cm, 0.5 cm, 0.6 cm, 0.7 cm, 0.8 cm, 0.9cm, 1.0cm, 1.1cm, 1.2cm, 1.3cm, 1.4cm, 1.5cm, 1.6cm, 1.7cm, 1.8cm, 1.9cm or 2.0cm, the range can be 0.1cm to 0.5cm, 0.1cm to 0.3cm.

The present invention has no particular limitation on the thickness of the tungsten layer, as long as the gradient material including the transition layer can have expected performance. For example, the thickness of the tungsten layer may be 0.01 cm to 4.0 cm and all values or subranges therebetween, such as 0.01 cm, 0.05 cm, 0.1 cm, 0.2 cm, 0.3 cm, 0.4 cm, 0.5 cm, 0.6 cm, 0.7cm, 0.8cm, 0.9cm, 1.0cm, 1.1cm, 1.2cm, 1.3cm, 1.4cm, 1.5cm, 1.6cm, 1.7cm, 1.8cm, 1.9cm, 2.0cm, 3.0cm or 4.0cm, the The range may be 0.1 cm to 0.5 cm, 0.1 cm to 0.3 cm.

The present invention has no particular limitation on the thickness of the yttrium oxide layer, as long as the gradient material including the transition layer can have expected performance. For example, the thickness of the yttrium oxide can be 0.01 cm to 1.0 cm and all values or subranges therebetween, such as 0.01 cm, 0.05 cm, 0.1 cm, 0.2 cm, 0.3 cm, 0.4 cm, 0.5 cm, 0.6 cm, 0.7cm, 0.8cm, 0.9cm or 1.0cm, the range can be 0.1cm to 0.5cm, 0.1cm to 0.3cm.

In some preferred embodiments, the thickness of the transition layer is greater than the thickness of the yttrium oxide layer.

In some embodiments, the tungsten, such as the tungsten in the tungsten layer, or such as the tungsten in the transition layer (excluding the yttrium oxide in the transition layer), can independently have a purity of 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 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.

When calculating the amount of yttrium oxide and tungsten used to form the gradient material, the total mass of _Y2O3 in the transition layer and the yttrium _oxide layer The total mass of W in the transition layer and the tungsten layer where, where p = 0.4, is the density of _Y2O3 , _ρW is the density of _W , s is the cross-sectional area of the gradient material, and the units representing thickness, area and volume should be the same series of units, for example, centimeter, square centimeter and cubic centimeter respectively expressed in centimeters.

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) using a third dispersion medium and a third dispersant to prepare a third dispersion for forming the transition layer, and using a first dispersion medium and a first dispersant to prepare a first dispersion for forming the tungsten layer , using a second dispersion medium and a second dispersant to prepare a second dispersion liquid for forming the yttrium oxide layer;

(c) sequentially allowing said first dispersion, said third dispersion and said second dispersion to settle in a mold and removing the liquid to form a settled body;

(d) drying the settled body, thereby making a prefabricated body; and

(e) Cold pressing and sintering the prefabricated green body, so as to obtain the gradient material.

In some embodiments, the particle size of the tungsten powder used to form the tungsten layer and the particle size of the tungsten powder used to form the transition layer are independently 0.1 μm to 10 μm, such as 0.1, 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 first dispersion medium, the second dispersion medium, and the third dispersion medium may be independently selected from the group consisting of water, ethanol, methanol, and xylene. In addition, the first dispersant, the second dispersant and the third dispersant may be the same or different, preferably partly the same, more preferably completely the same. 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.

In some embodiments, the first dispersant, the second dispersant, and the third dispersant can be independently selected from polyethylene, polyacrylic acid, glycerin, and polycarboxylic acid and polysiloxane copolymers. The group consisting of copolymers formed. In addition, the first dispersant, the second dispersant, and the third dispersant may be the same or different. 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%.

The method of preparing the dispersion liquid is not particularly limited in the present invention, as long as a uniform dispersion liquid can be obtained. However, in some preferred embodiments, during the process of the first dispersion liquid, the second dispersion liquid and/or the third dispersion liquid, it is preferable to disperse by ultrasonic wave for 20 minutes to 40 minutes while stirring (eg 20, 30 or 40 minutes).

In some other optional embodiments, the settling is free settling by gravity, more preferably, the free settling time is 24 hours to 72 hours or any value or subrange therebetween, such as the settling The time can be 24, 48, 60 or 72 hours.

The present invention does not have special restriction to the device that free settling is used, for example can use the settling device that has settling tube to carry out, but absolutely can only use such device, in fact, can realize the required settling of the method of the present invention And all devices that do not cause unacceptable adverse effects can be used. For example, referring to Fig. 1 , the settling device comprises a settling tube 1 positioned above, a settling tube 2 positioned below and communicated with the settling tube 1, and a control flow between the settling tube 1 and the settling tube 2 passes from the settling tube 1 to the settling tube 1. The valve of the pipe 2, the lower end of the settling pipe 2 includes a mold insertion section and a liquid discharge port located on the upper edge of the mold insertion section, and the liquid discharge port is provided with a liquid discharge valve for controlling liquid discharge. During operation, the mold insertion section is vertically placed into the mold, and the settling tube 2 is filled with dispersion medium. Close the valve, and then put the dispersion prepared for sedimentation into the settling tube 1 from above, when the dispersion is stable in the settling tube 1, open the valve, and the particles in the dispersion to be settled pass through the settling tube 2 under the action of gravity Settled freely into the mold. In some other embodiments, it is also possible to prepare the dispersion liquid to be settled in the settling tube 1, and then open the valve for settlement after the dispersion liquid to be dispersed is stable. The settling time of each dispersion can be determined by those skilled in the art, for example, for the third dispersion, that is, the dispersion used to form the transition layer, the settling time can be, for example, 24 hours to 72 hours. After the particles in the dispersion have settled, for example, after the liquid in the settling tube is basically clarified, the drain valve is opened to drain the liquid in the settling tube, thereby completing the settling process, and in-situ drying can be used later.

With the settling method of the present invention, only the dispersion used to form the transition layer can be settled, whereby a gradient material including only the transition layer can be produced. It is also possible to deposit the dispersion liquid for forming the tungsten layer first, and then deposit the dispersion liquid for forming the transition layer, thereby forming a gradient material including the tungsten layer and the transition layer. It is also possible to sequentially deposit the dispersion liquids respectively used to form the tungsten layer, the transition layer and the yttrium oxide layer, thereby preparing a gradient material including the tungsten layer, the transition layer and the yttrium oxide layer. Alternatively, the dispersion liquid for forming the transition layer may be deposited first, and then the dispersion liquid for forming the yttrium oxide layer may be deposited, thereby forming a gradient material including the transition layer and the yttrium oxide layer. The specific form of the gradient material to be formed can be selected according to the target application.

The present invention has no particular limitation on the drying method, but preferably the drying temperature of the drying is 80°C to 120°C or any value or range therebetween, such as 80, 90, 100, 110 or 120°C; the drying time It can be 12 hours to 48 hours or any value or subrange therebetween, for example, it can be 12, 24, 36 or 48 hours. The present invention has no special limitation on the equipment used for drying, for example, the drying can be carried out using a blast oven or an infrared dryer known to those skilled in the art.

The present invention has no special limitation on the sintering method. For example, in some embodiments, the sintering is performed using a method selected from the group consisting of a hot press sintering method, a pressureless sintering method and a hot isostatic pressing sintering method.

In some embodiments where the sintering is carried out by hot pressing sintering method, the sintering temperature may be 1600°C to 2000°C or any value or range therebetween, such as 1600, 1700, 1800, 1900 or 2000°C. During hot press sintering, one-way pressure or two-way pressure can be used to pressurize. The pressure applied is 10MPa to 50MPa or any value or range in between, such as 10, 20, 30, 40 or 50MPa. The time is 1 hour to 5 hours, such as 1, 2, 3, 4 or 5 hours, and the cooling rate is 5°C/minute to 10°C/minute, such as 5, 6, 7, 8, 9 or 10°C/minute, The sintering atmosphere can be argon, nitrogen or vacuum.

In some optional embodiments, the cold pressing can be carried out by first performing cold pressing at 5 MPa to 50 MPa (for example, 5, 10, 20, 30, 40 or 50 MPa), and then performing cold isostatic pressing. The pressure of the cold isostatic pressing can be 100MPa to 200MPa or any value or subrange therebetween, such as 100, 110, 120, 130, 140, 150, 160, 170, 180, 190 or 200MPa; in this case, subsequently The sintering can be performed by a pressureless sintering method, and the sintering temperature of the pressureless sintering is 1600°C to 2000°C or any value or range therebetween, such as 1600, 1700, 1800, 1900 or 2000°C. The sintering holding time is 1 hour to 5 hours, such as 1, 2, 3, 4 or 5 hours, and the sintering atmosphere is nitrogen, argon or vacuum.

In some optional embodiments, the sintering can be directly carried out by hot isostatic pressing sintering, and the sintering temperature of hot isostatic pressing is 1300°C to 1700°C or any value or range therebetween, such as 1300, 1400, 1500, 1600 or 1700°C, the sintering holding time is 1 hour to 5 hours, such as 1, 2, 3, 4 or 5 hours, and the sintering pressure can be 100MPa to 200MPa, such as 100, 150 or 200MPa.

The third aspect of the present invention provides the application of the gradient material according to the first aspect of the present invention or the gradient material prepared by the method according to the second aspect of the present invention in metal smelting.

Example

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

According to the preset l=1.0cm of the continuous gradient material, according to the formula with (Wherein p=0.4), respectively weigh 1 part (parts by weight, the same below) of yttrium oxide powder with an average particle diameter of 1 μm and a purity of 98%, and 8.7 parts of tungsten powder with an average particle diameter of 2 μm and a purity of 98%. Water is selected as a solvent, polyacrylic acid is used as a dispersant, tungsten powder and yttrium oxide powder are respectively prepared into a suspension using water, and the dispersant polyacrylic acid is added so that its molar concentration in the dispersion is 1mol%. The two dispersion liquids were respectively ultrasonically dispersed and stirred for 25 minutes to prepare dispersion liquids. Use the settling device described in Figure 1 for settling. During operation, fill the settling pipe 2 with dispersion medium, close the valve, and put the mold insertion section into the mold. Add the dispersion to be settled into the settling tube 1. After the dispersion is stable, open the valve, and the particles will freely settle into the mold under the action of gravity. After settling for 24 hours, the liquid in the settling tube was basically clear, and the settling was complete. Open the drain valve and drain the liquid in the settling pipe to obtain a settling body. Then the precipitated body was dried at 100° C. for 36 hours to obtain a prefabricated body. The prefabricated green body was cold-pressed at room temperature at a pressure of 5 MPa, and then directly sintered in a vacuum hot-pressed sintering furnace after cold isostatic pressing at 200 MPa to obtain a Y ₂ O ₃ -W continuous gradient material. The technological parameters of 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 96.5%, and the bending strength tested by the three-point bending method at room temperature is 315.5MPa. 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

According to the preset l=2.0cm of the continuous gradient material, as in Example 1, according to the set formula, weigh 1 part of yttrium oxide powder with an average particle diameter of 1.5 μm and a purity of 98.5%, and the average particle diameter is 2 μm , 8.7 parts of tungsten powder with a purity of 98%, select ethanol as the solvent and polyethylene as the dispersant, use water to prepare the tungsten powder and the yttrium oxide powder into a suspension, and add the dispersant polyethylene to make its dispersion in the dispersion The molar concentration is 0.5 mol%. The two dispersion liquids were respectively ultrasonically dispersed and stirred for 30 minutes to prepare dispersion liquids. Use the settling device described in Figure 1 for settling. During operation, fill the settling pipe 2 with dispersion medium, close the valve, and put the mold insertion section into the mold. Add the dispersion to be settled into the settling tube 1. After the dispersion is stable, open the valve, and the particles will freely settle into the mold under the action of gravity. After settling for 36 hours, the liquid in the settling tube was basically clear, and the settling was complete. Open the drain valve and drain the liquid in the settling pipe to obtain a settling body. Then the precipitated body was dried at 100° C. for 36 hours to obtain a prefabricated body. The prefabricated body was cold-pressed at room temperature at a pressure of 5 MPa. Then, direct hot-press sintering in a vacuum hot-press sintering furnace to prepare Y ₂ O ₃ -W continuous gradient material. The technological parameters of sintering are: heat preservation at 1500°C for 1 hour, vacuum degree of 1.3×10 ^-2 Pa, and cooling rate of 10°C/min.

The density of the composite material reaches 97.8%, and the bending strength tested by the three-point bending method at room temperature is 319.4MPa. In an atmosphere furnace filled with inert gas, keep warm at 400°C for 10 to 15 minutes, then immediately put it into an ice-water mixture at 0°C for quenching, repeat the above cycle of thermal shock 10 times, the prepared Y ₂ O ₃ -W gradient material There is no phenomenon of interlayer peeling and fracture failure, and its performance meets the service performance of alloy melting crucible materials.

Example 3

As in Example 1, according to the set formula, l=1.0cm, weigh 1 part of yttrium oxide powder with an average particle diameter of 1.5 μm and a purity of 98.0%, and 8.7 tungsten powders with an average particle diameter of 2 μm and a purity of 98.5%. Parts, select water as solvent, polyethylene as dispersant, as dispersant, respectively use ethanol to prepare tungsten powder and yttrium oxide powder into suspension, and add dispersant polyethylene so that its molar concentration in the dispersion is 1.0 mol%. The two dispersion liquids were respectively ultrasonically dispersed and stirred for 30 minutes to prepare dispersion liquids. Use the settling device described in Figure 1 for settling. During operation, fill the settling pipe 2 with dispersion medium, close the valve, and put the mold insertion section into the mold. Add the dispersion to be settled into the settling tube 1. After the dispersion is stable, open the valve, and the particles will freely settle into the mold under the action of gravity. After settling for 36 hours, the liquid in the settling tube was basically clear, and the settling was complete. Open the drain valve and drain the liquid in the settling pipe to obtain a settling body. Then the precipitated body was dried at 100° C. for 36 hours to obtain a prefabricated body. The prefabricated body was cold-pressed at room temperature at a pressure of 5 MPa. Then it is directly sintered in a hot isostatic pressing sintering furnace to prepare a Y ₂ O ₃ -W continuous gradient material. The technological parameters of sintering are: heat preservation at 1500°C for 1 hour, pressure at 100MPa, vacuum at 1.3×10 ^-2 Pa, and cooling rate at 10°C/min.

The density of the composite material reaches 98.2%, and the bending strength tested by the three-point bending method at room temperature can reach 321.5MPa. In an atmosphere furnace filled with inert gas, keep warm at 400°C for 10 to 15 minutes, then immediately put it into an ice-water mixture at 0°C for quenching, repeat the above cycle of thermal shock 10 times, the prepared Y ₂ O ₃ -W gradient material There is no phenomenon of interlayer peeling and fracture failure, and its performance meets the service performance of alloy melting crucible materials.

Example 4

As in Example 1, according to the set formula, l=1.0cm, weigh 1 part of yttrium oxide powder with an average particle diameter of 0.8 μm and a purity of 99.0%, and tungsten powder with an average particle diameter of 1.5 μm and a purity of 98.5%. 8.7 parts, select ethanol as a solvent, polyacrylic acid as a dispersant, prepare a dispersion in the same manner as in Example 1 and carry out sedimentation, but the molar concentration of the dispersant is 2.0mol%, ultrasonically disperse for 25min, and after free sedimentation for 42h, prepare Get sediment. Then the precipitated body was dried at 100° C. for 36 hours to obtain a prefabricated body. The prefabricated body was cold-pressed at room temperature at a pressure of 5 MPa. After cold isostatic pressing at 200MPa, it is directly sintered in a vacuum hot-pressing sintering furnace. The process parameters are: heat preservation at 1900°C for 1 hour, argon protection, and a cooling rate of 10°C/min.

The density of the composite material reaches 98.0%, and the bending strength of the three-point bending method at room temperature is 318.5MPa. In an atmosphere furnace filled with inert gas, keep warm at 400°C for 10 to 15 minutes, and then put it into an ice-water mixture at 0°C for quenching. After repeating the above cycle of thermal shock for 15 times, the prepared Y ₂ O ₃ -W gradient material There is no phenomenon of interlayer peeling and fracture failure, and its performance meets the service performance of alloy melting crucible materials.

Example 5

As in Example 1, according to the set formula, l=1.0cm, weigh 1 part of yttrium oxide powder with an average particle diameter of 0.8 μm and a purity of 98.5%, and tungsten powder with an average particle diameter of 1.5 μm and a purity of 99.0%. 8.7 parts, select methanol as a solvent, glycerin as a dispersant, prepare a dispersion in the same manner as in Example 1 and settle, but the molar concentration of the dispersant is 1.0mol%, ultrasonically disperse for 35min, and after free sedimentation for 42h, obtained sedimentation body. Then the precipitated body was dried at 100° C. for 36 hours to obtain a prefabricated body. The prefabricated body was cold-pressed at room temperature at 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 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 99.0%, and the bending strength tested by the three-point bending method at room temperature is 324.3MPa. 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

As in Example 1, according to the set formula, l=1.0cm, weigh 1 part of yttrium oxide powder with an average particle diameter of 1 μm and a purity of 99.0%, and 8.7 parts of tungsten powder with an average particle diameter of 2 μm and a purity of 99.0%. , select methanol as a solvent, glycerin as a dispersant, prepare a dispersion in the same manner as in Example 1 and carry out sedimentation, but the molar concentration of the dispersant is 1.5mol%, ultrasonically disperse for 35min, and after free sedimentation for 48h, a sedimentation body is obtained . Then the precipitated body was dried at 100° C. for 36 hours to obtain a prefabricated body. The prefabricated body was cold-pressed at room temperature at a pressure of 5 MPa. Then, sintering is carried out directly in a hot isostatic pressing sintering furnace to prepare Y ₂ O ₃ -W continuous gradient material. The process parameters are: heat preservation at 1600°C for 1 hour, pressure at 100MPa, argon protection, and cooling rate at 10°C/min.

The density of the composite material reaches 99.4%, and the bending strength tested by the three-point bending method at room temperature is 330.7MPa. In an atmosphere furnace filled with inert gas, keep warm at 400°C for 10 to 15 minutes, and then put it into an ice-water mixture at 0°C for quenching. After repeating the above cycle of thermal shock for 15 times, the prepared Y ₂ O ₃ -W gradient material There is no phenomenon of interlayer peeling and fracture failure, and its performance meets the service performance of alloy melting crucible materials.

Example 7

As in Example 1, according to the set formula, l=1.0cm, weigh 1 part of yttrium oxide powder with an average particle diameter of 3 μm and a purity of 99.0%, and 8.7 parts of tungsten powder with an average particle diameter of 1 μm and a purity of 99.0%. , select methanol as solvent, glycerol as dispersant, prepare dispersion in the same manner as in Example 1 and settle, but the molar concentration of dispersant is 2mol%, ultrasonic dispersion 40min, free sedimentation after 54h, made sediment. Then the precipitated body was dried at 100° C. for 36 hours to obtain a prefabricated body. The prefabricated body was cold-pressed at room temperature at a pressure of 5 MPa. After 200MPa cold isostatic pressing, the Y ₂ O ₃ -W continuous gradient material was obtained by direct pressureless sintering in a vacuum hot pressing sintering furnace. The process parameters are: heat preservation at 1850°C for 1 hour, vacuum degree <1.3×10 ^-2 Pa, and cooling rate of 10°C/min.

The density of the composite material reaches 97.2%, and the bending strength tested by the three-point bending method at room temperature is 310.5MPa. In an atmosphere furnace fed with inert gas, keep warm at 400°C for 10 to 15 minutes, then put it into an ice-water mixture at 0°C for quenching, repeat the above cycle of thermal shock for 20 times, the prepared Y ₂ O ₃ -W gradient material There is no phenomenon of interlayer peeling and fracture failure, and its performance meets the service performance of alloy melting crucible materials.

Example 8

As in Example 1, according to the set formula, l=1.0cm, take 1 part of yttrium oxide powder with an average particle diameter of 4 μm and a purity of 99.9%, and 8.7 parts of tungsten powder with an average particle diameter of 2 μm and a purity of 99.0%. , select xylene as the solvent, the copolymer of polycarboxylic acid and polysiloxane as the dispersant, prepare the dispersion in the same manner as in Example 1 and settle, but the molar concentration of the dispersant is 1.0mol%, ultrasonic dispersion After 35 minutes and 60 hours of free sedimentation, a sedimentation body was obtained. Then the precipitated body was dried at 100° C. for 36 hours to obtain a prefabricated body. The prefabricated body was cold-pressed at room temperature at 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 are: heat preservation at 1650°C for 1 hour, pressure at 40MPa, vacuum degree <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 327.6MPa. In an atmosphere furnace fed with inert gas, keep warm at 400°C for 10 to 15 minutes, then put it into an ice-water mixture at 0°C for quenching, repeat the above cycle of thermal shock for 20 times, the prepared Y ₂ O ₃ -W gradient material There is no phenomenon of interlayer peeling and fracture failure, and its performance meets the service performance of alloy melting crucible materials.

Example 9

As in Example 1, according to the set formula, l=1.0cm, take 1 part of yttrium oxide powder with an average particle diameter of 4 μm and a purity of 99.9%, and 8.7 parts of tungsten powder with an average particle diameter of 1 μm and a purity of 99.0%. , select xylene as the solvent, polycarboxylic acid and polysiloxane copolymer as the dispersant, prepare the dispersion in the same manner as in Example 1 and settle, but the molar concentration of the dispersant is 1.5mol%, ultrasonically dispersed for 40min , after 72 hours of free sedimentation, the sedimentation body was obtained. Then the precipitated body was dried at 100° C. for 36 hours to obtain a prefabricated body. The prefabricated body was cold-pressed at room temperature at a pressure of 5 MPa. Then, sintering is carried out directly in a hot isostatic pressing sintering furnace to prepare Y ₂ O ₃ -W continuous gradient material. The process parameters are: heat preservation at 1650°C for 1 hour, pressure at 150MPa, vacuum degree at 1.3×10 ^-2 Pa, and cooling rate at 10°C/min.

The density of the composite material reaches 99.5%, and the bending strength tested by the three-point bending method at room temperature is 335.2MPa. 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

First weigh 5 parts of tungsten powder with an average particle size of 1 μm and a purity of 98.0%, use water as a solvent, and 1.0 mol% polyacrylic acid as a dispersant to prepare a dispersion, and carry out sedimentation in the same manner as described in Example 1 Operation, ultrasonic dispersion for 25 minutes, and free sedimentation for 24 hours, the W sedimentation layer was obtained.

Then, a Y ₂ O ₃ —W composite sedimentation layer with a continuous gradient distribution was formed on the W sedimentation layer in the same manner as in Example 1.

Then weigh 3 parts of yttrium oxide powder with an average particle size of 2 μm and a purity of 98%, use water as a solvent, and 1.0 mol% polyethylene as a dispersant to prepare a dispersion, and settle in the same manner as described in Example 1 Operation, forming a yttrium oxide sedimentation layer on the composite material sedimentation layer, thus making a sedimentation body comprising a W sedimentation layer, a composite material sedimentation layer and an yttrium oxide layer, and then drying the sedimentation body at 120° C. for 48 hours to obtain Prefabricated body. The prefabricated green body was cold-pressed at room temperature with a pressure of 20 MPa. After cold isostatic pressing at 200 MPa, it was directly sintered in a vacuum hot-pressed sintering furnace. hours, the degree of vacuum is 1.3×10 ^-2 Pa, and the cooling rate is 10°C/min, thereby preparing a gradient material including a Y ₂ O ₃ -W continuous transition layer.

The density of the gradient material reaches 98.54%, and the bending strength tested by the three-point bending method at room temperature is 428.5 MPa. 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 .

Claims (10)

1. A continuous gradient material of yttrium oxide-tungsten, characterized in that: The gradient material includes a tungsten layer with a thickness of _l0 , _an yttrium oxide layer with a thickness of l1, and a transition layer with a thickness of _l2 , and _l0 and _l1 are independently ≥0, and _l2 >0; The transition layer has a tungsten-rich surface and a yttrium oxide-rich surface and is located between the tungsten layer and the yttrium oxide layer, the tungsten layer is located on the tungsten-rich surface side of the transition layer, and the yttrium oxide layer is located The side of the yttrium oxide-rich surface of the transition layer; The volume fraction of yttrium oxide at the z position from the tungsten-rich surface in the transition layer And the volume fraction of tungsten at the z position from the tungsten-rich surface in the transition layer Wherein, l=l ₀ +l ₂ , p=0.4, l ₀ ≤z≤l. 2. The gradient material according to claim 1, characterized in that: _{0.01cm≤l0≤4.0cm} ; and/or 0.01cm≤l ₁ ≤1.0cm; and/or 0.1cm≤l ₂ ≤1.0cm. 3. The method according to claim 1 or 2, characterized in that: The purity of the tungsten is independently above 90% by mass, preferably above 98% by mass; and/or The purity of the yttrium oxide is independently 90% by mass or higher, preferably 98% by mass or higher. 4. The gradient material according to any one of claims 1 to 3, wherein the total mass of Y ₂ O ₃ in the transition layer and the yttrium oxide layer The total mass of W in the transition layer and the tungsten layer in, is the density of Y ₂ O ₃ , ρ _W is the density of W, and s is the cross-sectional area of the gradient material. 5. A method for preparing the gradient material according to any one of claims 1 to 4, characterized in that the method comprises 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) using a third dispersion medium and a third dispersant to prepare a third dispersion for forming the transition layer, and using a first dispersion medium and a first dispersant to prepare a first dispersion for forming the tungsten layer , using a second dispersion medium and a second dispersant to prepare a second dispersion liquid for forming the yttrium oxide layer; (c) sequentially allowing said first dispersion, said third dispersion and said second dispersion to settle in a mold and removing the liquid to form a settled body; (d) drying the settled body, thereby making a prefabricated body; and (e) Cold pressing and sintering the prefabricated green body, so as to obtain the gradient material. 6. The method according to claim 5, characterized in that: The particle size of the tungsten powder used to form the tungsten layer and the particle size of the tungsten powder used to form the transition layer are independently 0.1 μm to 10 μm; and/or 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; and/or The first dispersion medium, the second dispersion medium, and the third dispersion medium are the same or different, and are independently selected from the group consisting of water, ethanol, methanol, and xylene; and/or The first dispersant, the second dispersant and the third dispersant are the same or different, and are independently selected from polyethylene, polyacrylic acid, glycerin, and copolymers of polycarboxylic acid and polysiloxane The group, preferably, the use concentration of the dispersant is 0.5mol% to 3mol%. 7. The method according to claim 5 or 6, characterized in that: During the process of the first dispersion liquid, the second dispersion liquid and/or the third dispersion liquid, ultrasonic dispersion is used for 20 minutes to 40 minutes while stirring; and/or The settling is free settling by gravity, more preferably, the free settling time is 24 hours to 72 hours; and/or The drying is carried out at 80° C. to 120° C. for 12 hours to 48 hours. Preferably, the drying is carried out in an air blast oven or an infrared dryer. 8. The method according to any one of claims 5 to 7, wherein the sintering is carried out by a method selected from the group consisting of a hot press sintering method, a pressureless sintering method and a hot isostatic pressing sintering method . 9. The method of claim 8, wherein: The sintering is carried out by a hot press sintering method, and the sintering temperature is 1600°C to 2000°C, pressurized by one-way pressure or two-way pressure, the applied pressure is 10MPa to 50MPa, and the sintering holding time is 1 hour to 1 hour. 5 hours, the cooling rate is 5°C/min to 10°C/min, the sintering atmosphere is argon, nitrogen or vacuum; and/or The cold press forming is carried out by cold pressing at 5MPa to 50MPa first, and then cold isostatic pressing at 50MPa to 200MPa, and the sintering is carried out by a pressureless sintering method, and the sintering temperature of the pressureless sintering is 1600°C to 2000°C, the sintering holding time is 1 hour to 5 hours, and the sintering atmosphere is nitrogen, argon or vacuum; and/or The sintering is directly carried out by HIP sintering, the sintering temperature of HIP sintering is 1300°C to 1700°C, the sintering holding time is 1 hour to 5 hours, and the sintering pressure is 100MPa to 200MPa. 10. The application of the gradient material according to any one of claims 1 to 4 or the gradient material prepared by the method according to any one of claims 5 to 9 in metal smelting.