A magnesium-gadolinium binary alloy fuel powder and a method and system for making the same

Abstract

The application provides a magnesium-gadolinium binary alloy fuel powder and a preparation method and system thereof. The mass content of gadolinium in the magnesium-gadolinium binary alloy fuel powder is 6-30%, the density is 2.11-3.59 g / cm 3 , and the mass heat value is 20.01-24.06 kJ / g. The preparation method comprises the following steps: under the condition of argon positive pressure, melting the metal containing magnesium and gadolinium in a manganese steel crucible smelting furnace, conveying the obtained magnesium-gadolinium binary alloy liquid to a tightly coupled gas atomization tank for atomization through a stainless steel conveying pipe, and obtaining the magnesium-gadolinium binary alloy fuel powder after screening. The system comprises a smelting furnace, a tightly coupled gas atomization tank, a liquid conveying pipeline, a mechanical screening machine, an air flow sorting machine and a high-pressure argon tank. The application solves the phase segregation caused by the high density difference between magnesium and gadolinium in the magnesium-gadolinium alloy atomization powder preparation, and the safety problem caused by the volatility of magnesium, and the prepared magnesium-gadolinium alloy powder has a uniform metallographic structure and no serious segregation.

Description

Technical Field

[0001] This invention relates to the field of alloy technology, and more specifically, to a magnesium-gadolinium binary alloy fuel powder and its preparation method and system. Background Technology

[0002] Magnesium powder is a type of powder with a low ignition temperature (~600℃) and a high calorific value (26.10 kJ / g, 45.40 kJ / cm³). 3 Magnesium is a single-element metallic fuel widely used in magnesium / fluoride ignition agents and infrared radiation agents that use fluorides as oxidants. However, magnesium has a high activation energy (~280 kJ / mol), resulting in a low burning rate. Furthermore, the combustion product, magnesium fluoride, has a low melting point (~1260℃) and a high boiling point (~2260℃). Within the combustion temperature range of magnesium / fluoride agents (1500℃~1700℃), liquid magnesium fluoride adheres to the magnesium particles to be burned, severely affecting the combustion efficiency of magnesium / fluoride agents. The rare earth metal gadolinium has a much lower activation energy (~113 kJ / mol) than magnesium, resulting in a much faster combustion rate. In addition, gadolinium's combustion product, gadolinium fluoride, is solid (melting point ~2330℃), which helps to eliminate the adhesion of liquid magnesium fluoride. Introducing gadolinium into magnesium to create magnesium-gadolinium alloy fuels results in refined alloy grains due to the presence of the metastable Mg5Gd phase, increasing the surface area for reaction. This leads to micro-explosions in the magnesium-gadolinium alloy powder during combustion with fluorides, further eliminating the combustion-inhibiting effect of liquid magnesium fluoride and significantly improving the combustion efficiency of magnesium-gadolinium / fluoride agents. Therefore, magnesium-gadolinium alloy fuels are of significant value in improving the combustion performance of magnesium / fluoride agents.

[0003] In existing technologies, magnesium-gadolinium alloys are only used as structural materials, and there is no evidence of preparing magnesium-gadolinium alloy fuel powder. Furthermore, the preparation of magnesium-gadolinium alloy structural materials suffers from phase segregation, which is caused by uneven alloy mixing, resulting in deterioration of the alloy's mechanical properties. This is due to the large density difference between magnesium and gadolinium. The atomization of magnesium-gadolinium alloys to produce fuel powder also faces the problem of phase segregation caused by the high density difference between magnesium and gadolinium. At the same time, the volatility of magnesium also poses safety issues. Summary of the Invention

[0004] In order to solve the technical problems existing in the prior art, the present invention provides a magnesium-gadolinium binary alloy fuel powder and its preparation method and system.

[0005] This invention utilizes a tightly coupled gas atomization method to prepare spherical magnesium-gadolinium alloy powder. The magnesium-gadolinium alloy is smelted in a manganese steel crucible, and a high-speed argon gas flow is used to pulverize the liquid alloy into small droplets, which then rapidly solidify into powder, resulting in a shorter cooling time. The core principle is controlling the interaction of the gas with the molten metal flow, maximizing the conversion of the gas flow's kinetic energy into the powder's surface energy. Because the smelting furnace and atomizing tank are vertically positioned in the tightly coupled gas atomization method, the feed pipe is shorter, reducing impurities caused by pipeline corrosion. The valve in the middle of the feed pipe allows for free control of the liquid flow rate. This method is particularly suitable for atomizing highly corrosive alloys. The tightly coupled atomizer is a coaxial, internally and externally isolated sleeve structure, characterized by independent control of the material and gas paths. Therefore, the preparation process requires careful control of the gas flow direction, gas velocity, and gas flow rate. Meanwhile, to improve atomization efficiency, the tightly coupled gas atomization equipment improves the nozzle structure to minimize the distance from the airflow outlet to the liquid flow, creating turbulence between the liquid and airflow in the atomization chamber and increasing the efficiency of gas kinetic energy transfer to the molten metal. This patent uses stainless steel pipelines to transport the liquid material, ensuring the sphericity, density, and cooling rate of the powder while preventing segregation. Mechanical sieving and airflow separators are used for particle size classification. To ensure the safety of the powder production process, a full-process "oxygen-free closed-loop / argon positive pressure" process control is employed. The prepared magnesium-gadolinium alloy powder has a median particle size of 5μm to 80μm, a sphericity of not less than 95%, a smooth surface, no satellite powder, a purity of over 99.5%, a powder density of not less than 99% of the theoretical density, a loose packing density of not less than 50% of the theoretical density, and a uniform metallographic structure without severe segregation.

[0006] One of the objectives of this invention is to provide a magnesium-gadolinium binary alloy fuel powder.

[0007] The gadolinium content in the magnesium-gadolinium binary alloy fuel powder is 6-30% by mass; preferably 10-20%.

[0008] The density of the magnesium-gadolinium binary alloy fuel powder is 2.11–3.59 g / cm³. 3 The preferred value is 2.36–2.95 g / cm³. 3 ;

[0009] The mass calorific value is 20.01–24.06 kJ / g, preferably 21.92–22.86 kJ / g;

[0010] The melting point is 590℃~1313℃, preferably 640℃~660℃;

[0011] The ignition temperature is 474℃~750℃, preferably 680℃~720℃;

[0012] The activation energy is 113 kJ / mol to 283 kJ / mol, preferably 120 kJ / mol to 150 kJ / mol.

[0013] A second objective of this invention is to provide a method for preparing magnesium-gadolinium binary alloy fuel powder, comprising:

[0014] (1) Under positive pressure of argon, the metal containing magnesium and gadolinium is melted in a manganese steel crucible melting furnace to obtain magnesium-gadolinium binary alloy liquid;

[0015] (2) Under positive pressure of argon gas, magnesium gadolinium binary alloy liquid is transported to a tightly coupled gas atomizing tank through a stainless steel conveying pipe. After being atomized by tightly coupled gas and sieved, the magnesium gadolinium binary alloy fuel powder is obtained.

[0016] In a preferred embodiment of the present invention,

[0017] Step (1),

[0018] In the magnesium-gadolinium binary base solution, the gadolinium content is 6% to 30% by mass; preferably 10% to 20%.

[0019] In a preferred embodiment of the present invention,

[0020] Step (1),

[0021] The oxygen volume content in the manganese steel crucible melting furnace is kept to no more than 0.01% by vacuuming and purging with argon.

[0022] During the melting process, the positive pressure of argon gas is 103 kPa to 105 kPa;

[0023] The melting superheat is 130℃~220℃; melting superheat refers to the temperature difference above the melting point of the alloy, which is to ensure that the alloy melts completely.

[0024] The melting temperature is 700℃~950℃; preferably 780℃~850℃.

[0025] The melting time is 1 to 2 hours.

[0026] In a preferred embodiment of the present invention,

[0027] Step (2),

[0028] The oxygen volume content in the atomizing can is kept to no more than 0.01% by vacuuming and purging with argon.

[0029] The positive pressure of argon gas in the tightly coupled gas atomizing canister and pipeline is 102 kPa to 105 kPa;

[0030] The pressure difference between the tightly coupled gas atomizing canister and the manganese steel crucible melting furnace is 1 kPa to 4 kPa;

[0031] The mass flow rate of the liquid feed is controlled within the range of 14 g / s to 17 g / s.

[0032] The high-pressure gas atomizing alloy used for tightly coupled gas atomization has a high-pressure gas flow rate of 26 m / s. 3 / h~34m 3 / h.

[0033] In a preferred embodiment of the present invention,

[0034] Step (2),

[0035] The tightly coupled atomizing canister has an annular slit atomizing nozzle, the diameter of which is 3mm to 8mm, preferably 3mm to 5mm.

[0036] The annular slit atomizing nozzle has a nozzle at its end, and the eccentricity angle of the nozzle is 3° to 7°, preferably 5° to 7°.

[0037] The atomization pressure is 3.0MPa-5.0MPa.

[0038] In a preferred embodiment of the present invention,

[0039] Step (2),

[0040] Under positive pressure of argon gas, powder of different particle sizes is obtained by mechanical screening and airflow separation.

[0041] A third objective of this invention is to provide a system for preparing magnesium-gadolinium binary alloy fuel powder.

[0042] The system includes a smelting furnace, a tightly coupled gas atomizing tank, a liquid conveying pipeline, a mechanical screening machine, a gas flow separator, and a high-pressure argon tank;

[0043] The smelting furnace is a manganese steel crucible smelting furnace;

[0044] The tightly coupled gas atomizing can is equipped with a tightly coupled gas atomizing device.

[0045] The liquid delivery pipeline is made of stainless steel.

[0046] The smelting furnace is connected to the top of the atomizing tank via a stainless steel pipe. The bottom of the atomizing tank is connected to the top of the mechanical screening machine, and the bottom of the mechanical screening machine is connected to the airflow separator.

[0047] The high-pressure argon cylinder provides argon gas to the system;

[0048] The smelting furnace, the tightly coupled gas atomizing tank, the mechanical screening machine, the airflow separator, and the material conveying pipeline are all equipped with vacuum pumping devices and argon filling devices.

[0049] In a preferred embodiment of the present invention,

[0050] The tightly coupled gas atomizing device has an annular slit-type gas atomizing nozzle, the diameter of which is 3mm to 8mm, preferably 3mm to 5mm.

[0051] The annular slit-type atomizing nozzle has a nozzle at its end, and the eccentricity angle of the nozzle is 3° to 7°, preferably 5° to 7°.

[0052] The fourth objective of this invention is to provide a magnesium-gadolinium binary alloy fuel powder prepared by the above-mentioned preparation method or system.

[0053] The present invention can specifically adopt the following technical solutions:

[0054] 1. A metastable magnesium-gadolinium binary alloy fuel

[0055] (1) The melting point and phase composition of magnesium-gadolinium alloys with different gadolinium contents were calculated using alloy thermodynamics. Magnesium-gadolinium alloy compounds with higher reactivity than magnesium were sought. Within the mass ratio of the second element (Gd) (6%–30%), Mg5Gd alloy compounds were present in all magnesium-gadolinium alloy phases. Since the melting temperature of the Mg5Gd phase (437℃) is much lower than the melting point of magnesium (650℃), the melting point of the magnesium-gadolinium alloys is lower than that of magnesium (see Table 1). Based on the principle that liquid metals are more reactive than solid metals, this magnesium-gadolinium alloy fuel exhibits metastable characteristics. The preferred gadolinium mass content is 10%–20%, with 15% showing the best effect.

[0056] (2) Using the fuel combustion thermodynamics calculation method, the theoretical density and theoretical calorific value of different elemental compositions in the range of MgGd6~MgGd30 (wt.%) were calculated, and the ignition temperature and activation energy range were calculated by equation (1) to equation (4) (see Table 1).

[0057]

[0058]

[0059] In equations (1) to (2), ρ f Q f η i These are the theoretical density and theoretical calorific value of the alloy fuel, respectively. ρ f Q i These represent the mass fraction, density, and calorific value of each element.

[0060] Ignoring trace functional elements that contribute to grain refinement and surface densification, as well as impurities (below 0.5% by mass), the ignition temperature T of the alloy fuel is determined based on the characteristics of the molten alloy system. ign,f With activation energy E a,f They are respectively:

[0061] T ign,f ∈[T ign,min T ign,max (3)

[0062] E a,f ∈[E a,min E a,max (4)

[0063] In equations (3) and (4), T ign,min T ign,max E a,min E a,max These represent the lowest and highest ignition temperatures and the lowest and highest activation energies for each element.

[0064] Table 1. Performance parameters of magnesium-gadolinium alloy fuels with different gadolinium contents

[0065]

[0066] Among the five gadolinium alloy fuels with different gadolinium contents designed and calculated, the Mg5Gd phase content in the alloy phase of MgGd6 is too low, which is not conducive to the micro-explosion phenomenon in the fuel reaction process; while the calorific value of MgGd20 is too low, and the calorific values ​​of MgGd10, MgGd15 and MgGd20 are higher.

[0067] 2. A method and system for producing tightly coupled gas-atomized spherical magnesium gadolinium alloy powder.

[0068] To fully utilize the performance of magnesium-gadolinium alloy fuel, spherical magnesium-gadolinium alloy powder is prepared by rapidly solidifying molten alloy streams into small droplets using a high-speed argon gas flow. This method employs a tightly coupled gas atomization powder preparation system, integrating a corrosion-resistant manganese steel crucible alloy melting furnace, corrosion-resistant stainless steel conveying pipelines, a tightly coupled atomizer, and equipment such as a mechanical sieve and airflow separator. Combined with a complete "oxygen-free closed-loop / argon positive pressure" safety process, this ensures high purity, high sphericity, and high density of the powder while effectively guaranteeing production safety. The prepared spherical magnesium-gadolinium alloy powder has a median particle size of 5μm–80μm. The alloy powder has a sphericity greater than 95%, a uniform microstructure, and the main phases are Mg solid solution and Mg5Gd.

[0069] 3. The system for preparing magnesium-gadolinium binary alloy fuel powder is as follows: Figure 1As shown. 1 is a corrosion-resistant manganese steel crucible and target alloy melting furnace, a precision temperature-controlled resistance heating melting furnace specifically designed to prevent the introduction of impurities during the melting process. The maximum heating temperature is 900℃, with a temperature control accuracy of ±5℃. 2 is a liquid material conveying pipeline, made of corrosion-resistant stainless steel, to prevent the introduction of impurities during the high-temperature liquid material conveying process. 3 is a tightly coupled gas atomizing canister; the melting furnace and the atomizing canister are vertically positioned, and the conveying pipe is relatively short, which helps reduce impurities caused by pipeline corrosion. The middle of the material pipe... The valve can freely control the flow rate of the liquid material, and is used for atomization and powdering of magnesium-gadolinium binary alloy liquid material; 4 is a mechanical sieve, which can sieve particles of 25μm to 80μm into particles with multiple median diameters such as 25μm, 45μm, and 80μm; 5 is an airflow separator, which is used to obtain powder with a particle size of 5μm to 25μm, and can separate particles smaller than 25μm into specifications such as 15μm, 10μm, and 5μm; 6 is a high-pressure argon tank, which provides argon gas to various equipment and pipelines in the system.

[0070] 4. The principle of tightly coupled gas atomization powder production is as follows: Figure 2 As shown, the tightly coupled gas atomizing device consists of a nozzle structure and a cylinder. The nozzle is an annular slit type, with a compact structure and an eccentricity angle of 3° to 7°. The molten metal flows out in the guide tube, reducing the flight distance. When the liquid flow is ejected from the nozzle, the resulting droplets depend on the liquid flow rate and atomization pressure. The liquid flow rate is controlled at 14 g / s to 17 g / s; the atomization chamber pressure is 3.0 to 5.0 MPa; at this time, the breakup mechanism is determined by the interaction (friction) between the ambient medium and the surface of the liquid column.

[0071] 5. Three magnesium gadolinium alloy fuels: MgGd10, MgGd15, and MgGd20

[0072] This fuel is primarily composed of magnesium, with a gadolinium content of 10%–20% and a theoretical density of 2.36 g / cm³. 3 ~2.97g / cm 3 Its calorific value is 22.04 kJ / g to 23.05 kJ / cm³. 3 The metastable Mg5Gd phase content is 21%–53%, the alloy melting point is 607℃–633℃, and the activation energy is between 113kJ / mol and 283kJ / mol. Characteristic parameters are shown in Table 2.

[0073] Table 2. Fuel design performance parameters of magnesium-gadolinium alloys with different gadolinium contents.

[0074]

[0075] 6. Magnesium-gadolinium alloy fuel close-coupled gas atomization pulverization method and system

[0076] This method integrates a tightly coupled atomizing tank, a corrosion-resistant manganese steel crucible alloy melting furnace, a corrosion-resistant stainless steel conveying pipe, an argon-environment mechanical screening machine and an airflow separator, as well as a full-process "oxygen-free closed-loop / argon positive pressure" safety assurance system. The resulting magnesium-gadolinium binary alloy powder has low impurity content, a powder density of not less than 99% of the theoretical density, a loose packing density of not less than 50% of the theoretical density, a sphericity of not less than 95%, a smooth surface, no satellite powder, no severe segregation in the metallographic structure, and a particle size of 5μm to 80μm that can be graded.

[0077] (1) Smelting magnesium-gadolinium binary target alloy in corrosion-resistant manganese steel crucible

[0078] The first step in the atomization powdering process of magnesium gadolinium alloy is to smelt the target alloy using MgGd30 base alloy and magnesium ingots as raw materials.

[0079] Magnesium-gadolinium alloys with a gadolinium content of less than 30% in the target alloy: The feed ratio and total yield are calculated according to formulas (5) and (6).

[0080]

[0081] M=M(Mg)+M(MgGd30) (6)

[0082] In equations (5) and (6), x represents the gadolinium content of the target alloy, and M(MgGd30), M(Mg), and M represent the MgGd30 base alloy, the amount of magnesium metal added, and the total yield of the target alloy, respectively.

[0083] Similarly, to avoid the liquid alloy corroding the crucible and introducing impurities, and to effectively suppress magnesium volatilization, a corrosion-resistant manganese steel crucible and precise temperature control technology using an argon positive pressure environment are employed. The magnesium-gadolinium binary alloy and magnesium are placed in a... Figure 1 In the sealed melting furnace 1 shown, the furnace is first evacuated to 0.1 kPa and then filled with argon gas to 1 atm; the second evacuation is performed to 10 kPa and then filled with argon gas to 1 atm. The oxygen content is monitored using an oxygen content detector until it is no more than 0.01% (sensor value). During the alloy melting process, the positive pressure of argon gas in the furnace is controlled within the range of 103 kPa to 105 kPa. Argon gas stirring is used to achieve uniform composition, and the maximum batch size is 50 kg / batch.

[0084] (2) Corrosion-resistant stainless steel pipeline for transporting magnesium gadolinium alloy liquid

[0085] To prevent the alloy molten material from corroding the pipeline and introducing impurities, corrosion-resistant stainless steel conveying pipes and argon positive pressure molten material conveying technology are used, such as... Figure 1As shown. The feed pipe is first evacuated to 0.1 kPa, then filled with argon to 1 atm; the second evacuation is performed to 10 kPa, followed by filling with argon to 1 atm. The positive pressure of argon relative to the atomizing tank in the feed pipe is controlled within the range of 102 kPa to 105 kPa. The oxygen content in the atomizing tank is controlled to be no greater than 0.01% using an oxygen content detector. During the feed liquid delivery process, the atomizing gas pressure is adjusted using a pressure regulating valve to maintain the atomizing gas pressure at approximately 3.0 to 5.0 MPa. The atomization status and the operation of each instrument are continuously monitored during the atomization process for timely adjustments.

[0086] (3) Closely coupled gas atomization powder production

[0087] Feed flow rate control: Mass flow rate of feed liquid The temperature T of the smelting furnace and conveying pipeline, the difference between the furnace pressure P2 and the tank pressure P3, the length L and cross-sectional area S1 of the material conveying pipe in the atomizing tank are controlled by parameters such as the temperature T of the smelting furnace and conveying pipeline, the difference between the furnace pressure P2 and the tank pressure P3, and the material conveying pipe length L and cross-sectional area S1 in the atomizing tank, as shown in equation (7).

[0088]

[0089] In equation (7), F(β, T) is the resistance function of material conveying, and β is the resistance coefficient between the material and the pipe.

[0090] Gas flow rate control: High-pressure gas is delivered through an argon cylinder. The gas flow rate is controlled by parameters such as the difference between furnace pressure P2 and cylinder pressure P3, gas cylinder pipe flow rate v1, gas delivery pipe length L2 of the annular nozzle and radius r of the annular nozzle, nozzle inclination angle α and argon density, as shown in equation (8).

[0091]

[0092] Tightly Coupled Gas Atomization Pressure and Flow Rate Control: Working Principle of Tightly Coupled Gas Atomizers (e.g.) Figure 2 The diameter of the annular slit-type gas atomizing nozzle is designed to be 3–5 mm, and the pressure difference between the tank and the furnace is 1–4 kPa. Therefore, the mass flow rate of the liquid feed is controlled within the range of 14–17 g / s. The atomization pressure is 3.0–5.0 MPa, and the supersonic argon gas flow rate is 26 m / s. 3 / h~34m 3 / h, nozzle eccentricity angle 3°~7°.

[0093] The relationship between atomization pressure and average powder particle size is as follows:

[0094]

[0095] In the formula, P is the atomization pressure; n and C are constants related to the equipment and melt properties.

[0096] The solidification time and spheroidization time of the liquid droplets are respectively:

[0097]

[0098] In the formula t sol For solidification time, t sph sphericization time, h c c is the heat transfer coefficient. p T is the specific heat of liquid metal. l T g T m These represent the superheat temperature of the liquid, the gas temperature, and the melting point of the liquid metal, respectively. ΔH is the enthalpy change.

[0099]

[0100] In the formula t sph Spheroidization time, V is the droplet volume; R and r are the radii of the droplet before and after spheroidization, respectively.

[0101] 7. Method Implementation Process

[0102] The implementation process of magnesium-gadolinium binary alloy atomization powder production is as follows: Figure 3 As shown.

[0103] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0104] This invention utilizes a high-speed argon gas flow to pulverize liquid alloy flow into small droplets, which then rapidly solidify into powder. This results in a shorter cooling time. In the tightly coupled gas atomization method, the melting furnace and atomizing tank are placed vertically, and the feed pipe is shorter, which helps reduce impurities caused by pipeline corrosion. The valve in the middle of the feed pipe can control the flow rate of the liquid over a wide range.

[0105] By improving the nozzle structure to minimize the distance between the airflow outlet and the liquid flow, turbulence is created between the liquid material and the airflow in the atomization chamber, increasing the efficiency of the transfer of gas kinetic energy to the molten metal flow.

[0106] The prepared magnesium-gadolinium alloy powder has a median particle size of 5μm to 80μm, a sphericity of not less than 95%, a smooth surface, no satellite powder, a purity of more than 99.5%, a powder density of not less than 99% of the theoretical density, a loose packing density of not less than 50% of the theoretical density, a uniform metallographic structure, and no serious segregation.

[0107] This invention solves the phase segregation caused by the high density difference between magnesium and gadolinium in magnesium-gadolinium alloy atomization powder production, as well as the safety issues caused by the volatility of magnesium. Attached Figure Description

[0108] Figure 1 A schematic diagram of the system equipment for preparing magnesium-gadolinium binary alloy fuel powder;

[0109] Among them, 1 is a smelting furnace, 2 is a conveying pipe, 3 is a tightly coupled gas atomizing canister, 4 is a mechanical screening machine, 5 is an airflow separator, and 6 is a high-pressure argon cylinder;

[0110] Figure 2 A schematic diagram of a tightly coupled gas atomizer structure in a magnesium-gadolinium binary alloy fuel powder system.

[0111] 3-1 Metal melt channel, 3-2 Gas channel, 3-3 Annular slit nozzle radius r, 3-4 Nozzle tilt angle α, 3-5 Gas outlet, 3-6 Melt outlet, 3-7 Metal melt;

[0112] Figure 3 A flowchart illustrating the process of atomizing magnesium-gadolinium binary alloy fuel powder.

[0113] Figure 4 The image shows the surface morphology of the MgGd10 powder in Example 1 using SEM.

[0114] Figure 5 This is a partial SEM image of the surface morphology of the MgGd10 powder in Example 1.

[0115] Figure 6 Metallographic photograph of MgGd10 powder in Example 1;

[0116] Figure 7 The graph shows the oxidation reaction rate of MgGd10 powder in Example 1.

[0117] Where the left vertical axis represents mass change and the right vertical axis represents heat flow;

[0118] Figure 8 The image shows the surface morphology of the MgGd15 powder in Example 2 using SEM.

[0119] Figure 9 This is a partial magnified SEM image of the surface morphology of MgGd15 powder in Example 2;

[0120] Figure 10 Metallographic photograph of MgGd15 powder in Example 2;

[0121] Figure 11 The graph shows the oxidation reaction rate of MgGd15 powder in Example 2.

[0122] Where the left vertical axis represents mass change and the right vertical axis represents heat flow;

[0123] Figure 12 The image shows the surface morphology of the MgGd20 powder in Example 3 using SEM.

[0124] Figure 13This is a partial magnified SEM image of the surface morphology of MgGd20 powder in Example 3;

[0125] Figure 14 Metallographic photograph of MgGd20 powder in Example 3;

[0126] Figure 15 This is a graph showing the oxidation reaction rate of MgGd20 powder in Example 3;

[0127] The left vertical axis represents mass change, and the right vertical axis represents heat flow. Detailed Implementation

[0128] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. It should be noted that the following embodiments are only used to further illustrate the present invention and should not be construed as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the content of the present invention are still within the scope of protection of the present invention.

[0129] All raw materials used in the examples are commercially available.

[0130] Example 1

[0131] Preparation of MgGd10 alloy powder:

[0132] According to formulas (5) and (6), 16.67 kg of magnesium gadolinium base alloy (MgGd30) and 33.33 kg of magnesium ingots were fed. 50 kg of raw materials were placed in melting furnace 1. The first vacuum was evacuated to 0.1 kPa and argon was purged to 1 atm for stirring; the second vacuum was evacuated to 10 kPa and argon was purged to 103 kPa for stirring. The oxygen content in the furnace was measured to be 0.009%. The superheat of the molten material was set to 150 ± 20 °C, heated to 780 °C, held for 10 min, and the total melting time was 1 h, resulting in a magnesium gadolinium binary alloy liquid.

[0133] The furnace was first evacuated to 0.1 kPa and then filled with argon gas to 1 atm; the second evacuation was performed to 10 kPa and then filled with argon gas to 102 kPa. The oxygen content inside the furnace was measured to be 0.01%. Argon gas was slowly injected into the atomizing canister to maintain the pressure difference between the furnace and the canister at 2 ± 0.1 kPa.

[0134] Maintain the liquid mass flow rate at approximately 14.5 g / s. Select a 3 mm diameter annular slit-type atomizing nozzle, control the nozzle eccentricity angle at 5°, turn on the atomizing gas, and adjust the atomizing pressure to approximately 3.0 MPa using the pressure regulating valve. During atomization, continuously monitor the atomization status and the operation of each instrument for timely adjustments. Ensure the high-pressure gas flow rate is 28 m / s. 3 / h or so.

[0135] Atomization is completed in approximately 40 minutes. After cooling for 2 hours, remove the collection bucket and pour the powder into a screening machine under an argon atmosphere. Take out the powder with a mesh size of 200 mesh (80μm) or larger, 200–325 mesh (45μm), and 325–500 mesh (25μm). Put the remaining material below 500 mesh into an air classifier for further subdivision.

[0136] Implementation results:

[0137] (1) Surface morphology. Taking a powder with a median diameter of 25 μm as an example, Figure 4 and Figure 5 The surface morphology photographs of MgGd10 alloy powder show that its sphericity is greater than 95%, the two-dimensional projection roundness value of the spherical powder is greater than 0.95, and the surface is clean and smooth.

[0138] (2) Elemental composition. The composition of MgGd10 alloy powder was analyzed by a Plasma 2000 inductively coupled plasma atomic emission spectrometer from NACKS NACKS. The test results are shown in Table 3.

[0139] Table 3 Composition of MgGd10 alloy powder

[0140] Alloy Name magnesium(%) gadolinium(%) Impurities such as Fe, Si, and Mn (%) MgGd10 89.98 9.9 ＜0.15

[0141] (3) Metallographic structure. The metallographic images were taken using a Shanghai Changfang CMM-20; the metallographic images of the MgGd10 powder are shown below. Figure 6 This indicates that MgGd10 has a dendritic structure and uniform grain distribution.

[0142] (4) Figure 7 The DSC / TG thermal oxidation curves of the powder in air atmosphere show that the melting temperature of the magnesium-gadolinium alloy ball is 645℃; the ignition temperature is 682.77℃; and the value is calculated to be 142.23 kJ / mol using the Kissinger method.

[0143] The calorific value released by the combustion of the powder in an oxygen environment of 3 MPa was tested using an oxygen bomb calorimeter; the density was tested using a JW-M100A series fully automatic true density tester, and the density of the alloy powder was measured to be 2.95 g / cm³. 3 The oxidation behavior of the powder in air at a heating rate of 10℃ / min was characterized using TG-DSC. The exothermic reaction and weight gain graph of the powder oxidation reaction showed that the oxidation reaction was rapid. The measured calorific value of the powder was 22.86 kJ / g, which, compared with the theoretical calorific value of 23.05 kJ / g in Table 1, represented an energy release rate of 99.16%.

[0144] Example 2

[0145] Preparation of MgGd15 alloy powder:

[0146] Take 25 kg of magnesium-gadolinium binary alloy raw material (MgGd30) and 25 kg of magnesium ingots. Place 50 kg of raw material into melting furnace 1. First, evacuate to 0.1 kPa and purge with argon to 1 atm while stirring; second, evacuate to 10 kPa and purge with argon to 103 kPa while stirring. The oxygen content in the furnace is measured to be 0.009%. The superheat setting for the molten material is 180 ± 20℃, and the temperature is raised to 810℃. Hold at this temperature for 10 minutes; the total melting time is 1.5 hours.

[0147] The furnace was first evacuated to 0.1 kPa and then filled with argon gas to 1 atm; the second evacuation was performed to 10 kPa and then filled with argon gas to 102 kPa. The oxygen content inside the furnace was measured to be 0.01%. Argon gas was slowly injected into the atomizing canister to maintain the pressure difference between the furnace and the canister at 3 ± 0.1 kPa.

[0148] The mass flow rate of the liquid feed should be controlled at approximately 15.5 g / s. A 4 mm diameter annular slit-type atomizing nozzle should be selected, with a nozzle eccentricity angle of 6°. The atomizing gas should be turned on, and the atomizing pressure adjusted to approximately 3.5 MPa using the pressure regulating valve. During atomization, the atomization status and the operation of each instrument should be continuously monitored for timely adjustments. The high-pressure gas flow rate should be maintained at 30 m / s. 3 / h or so.

[0149] Atomization is completed in approximately 50 minutes. After cooling for 2 hours, remove the collection bucket and pour the powder into a screening machine under an argon atmosphere. Take out the powder with a mesh size of 200 mesh (80μm) or larger, 200–325 mesh (45μm), and 325–500 mesh (25μm). Put the remaining material below 500 mesh into an air classifier for further subdivision.

[0150] Implementation results:

[0151] (1) Surface morphology. Taking a powder with a median diameter of 25 μm as an example, Figure 8 See the surface morphology photograph of MgGd15 alloy powder. Figure 1 This indicates that the sphericity of the magnesium gadolinium alloy powder is greater than 95%, the two-dimensional projection roundness value of the spherical powder is greater than 0.95, and the surface is clean and smooth.

[0152] (2) Elemental composition. The ICP analysis results of the MgGd15 alloy powder are shown in Table 4.

[0153] Table 4 Composition of MgGd15 Alloy Powder

[0154] Alloy Name magnesium(%) gadolinium(%) Impurities such as Fe, Si, and Mn (%) MgGd15 84.96 14.9 ＜0.15

[0155] (3) Metallographic structure. Metallographic analysis photographs of the MgGd15 alloy powder are shown below. Figure 5 This indicates that MgGd15 has a dendritic structure with uniform grain distribution.

[0156] (4) Figure 11 The DSC / TG thermal oxidation curve of the powder in air atmosphere shows that the melting temperature of the magnesium gadolinium alloy ball is 650℃ and the hot spot ignition temperature is 700.14℃; the value is calculated to be 120.91 kJ / mol using the Kissinger method.

[0157] The calorific value released by the combustion of the powder in an oxygen environment of 3 MPa was tested using an oxygen bomb calorimeter. The density was tested using a JW-M100A series fully automatic true density tester, and the density of the alloy powder was measured to be 2.68 g / cm³. 3 The oxidation behavior of the powder in air at a heating rate of 10℃ / min was characterized using TG-DSC. The exothermic reaction and weight gain graph of the powder oxidation reaction showed that the oxidation reaction was rapid. The measured calorific value of the powder was 22.01 kJ / g, which, compared with the theoretical calorific value of 22.44 kJ / g in Table 1, represented an energy release rate of 98.07%.

[0158] Example 3

[0159] Preparation of MgGd20 alloy powder:

[0160] 33.33 kg of magnesium-gadolinium binary alloy raw material (MgGd30) and 16.67 kg of magnesium ingot raw material were placed in melting furnace 1. The furnace was first evacuated to 0.1 kPa and then filled with argon gas to 1 atm for stirring. The furnace was then evacuated to 10 kPa and filled with argon gas to 105 kPa for stirring. The oxygen content in the furnace was measured to be 0.009%. The superheat of the molten material was set to 200 ± 20℃, and the temperature was increased to 850℃. The temperature was held for 10 minutes, and the total melting time was 2 hours.

[0161] The furnace was first evacuated to 0.1 kPa and then filled with argon to 1 atm; the second evacuation was performed to 10 kPa and then filled with argon to 105 kPa. The oxygen content inside the furnace was measured to be 0.01%. Argon was slowly injected into the atomizing canister to maintain the pressure difference between the furnace and the pressure vessel at 3.5 ± 0.1 kPa.

[0162] Maintain the liquid mass flow rate at approximately 16.5 g / s. Select a 5 mm diameter annular slit-type atomizing nozzle, control the nozzle eccentricity angle at 7°, turn on the atomizing gas, and adjust the atomizing pressure to approximately 4.0 MPa using the pressure regulating valve. During atomization, continuously monitor the atomization status and the operation of each instrument for timely adjustments. Ensure the high-pressure gas flow rate is 34 m / s. 3 / h or so.

[0163] Atomization is completed in approximately 40 minutes. After cooling for 2 hours, remove the collection bucket and pour the powder into a screening machine under an argon atmosphere. Take out the powder with a mesh size of 200 mesh (80μm) or larger, 200–325 mesh (45μm), and 325–500 mesh (25μm). Put the remaining material below 500 mesh into an air classifier for further subdivision.

[0164] Implementation results:

[0165] (1) Surface morphology. Taking a powder with a median diameter of 25 μm as an example, Figure 12 See the surface morphology photograph of the MgGd20 alloy powder. Figure 1 This indicates that the sphericity of the magnesium gadolinium alloy powder is greater than 95%, the two-dimensional projection roundness value of the spherical powder is greater than 0.95, and the surface is clean and smooth.

[0166] (2) Elemental composition. The ICP analysis results of the MgGd20 alloy powder are shown in Table 5.

[0167] Table 5 Composition of MgGd20 Alloy Powder

[0168] Alloy Name magnesium(%) gadolinium(%) Impurities such as Fe, Si, and Mn (%) MgGd20 79.98 19.9 ＜0.15

[0169] (3) Metallographic structure. Metallographic analysis photographs of the MgGd20 alloy powder are shown below. Figure 14 This indicates that MgGd20 has a dendritic structure with uniform grain distribution.

[0170] (4) Figure 15 The DSC / TG thermal oxidation curve of the powder in air atmosphere shows that the melting temperature of the magnesium gadolinium alloy ball is 655℃ and the hot spot ignition temperature is 700.95℃; the value is calculated to be 136.77 kJ / mol using the Kissinger method.

[0171] The calorific value released by the combustion of the powder in an oxygen environment of 3 MPa was tested using an oxygen bomb calorimeter. The density was tested using a JW-M100A series fully automatic true density tester, and the density of the alloy powder was measured to be 2.36 g / cm³. 3 The oxidation behavior of the powder in air at a heating rate of 10℃ / min was characterized using TG-DSC. The exothermic reaction and weight gain graph of the powder oxidation reaction showed that the oxidation reaction was rapid. The measured calorific value of the powder was 21.92 kJ / g, which is 99.45% higher than the theoretical calorific value of 22.04 kJ / g.

Claims

1. A magnesium-gadolinium binary alloy fuel powder, characterized in that: The gadolinium content in the magnesium-gadolinium binary alloy fuel powder is 6-30% by mass. The density of the magnesium-gadolinium binary alloy fuel powder is 2.11~3.59 g / cm³. 3 ; The calorific value is 20.01~24.06 kJ / g; Melting point is 590℃~1313℃; The ignition temperature is 474℃~750℃; The activation energy is 113 kJ / mol ~ 283 kJ / mol; The preparation method of the magnesium-gadolinium binary alloy fuel powder includes: (1) Under positive pressure of argon, the metal containing magnesium and gadolinium is melted in a manganese steel crucible melting furnace to obtain magnesium-gadolinium binary alloy liquid; (2) Under positive pressure of argon, magnesium gadolinium binary alloy liquid is transported to a tightly coupled gas atomizing tank through a stainless steel conveying pipe. After being atomized by tightly coupled gas and sieved, the magnesium gadolinium binary alloy fuel powder is obtained. The tightly coupled atomizing tank has an annular slit atomizing nozzle with a diameter of 3mm to 8mm; the annular slit atomizing nozzle has a nozzle at its end with an eccentricity angle of 3° to 7°; the liquid mass flow rate is controlled within the range of 14g / s to 17g / s; the high-pressure gas velocity of the tightly coupled atomizing tank is 26m. 3 / h~34m 3 / h; atomization pressure is 3.0MPa - 5.0MPa.

2. The magnesium-gadolinium binary alloy fuel powder as described in claim 1, characterized in that: The gadolinium content in the magnesium-gadolinium binary alloy fuel powder is 10-20% by mass; and / or, The density of the magnesium-gadolinium binary alloy fuel powder is 2.36~2.95 g / cm³. 3 ; and / or, The calorific value is 21.92~22.86 kJ / g; and / or, Melting point is 640℃~660℃; and / or, The hot spot temperature is 680℃~720℃; and / or, The activation energy is 120 kJ / mol to 150 kJ / mol.

3. A method for preparing magnesium-gadolinium binary alloy fuel powder as described in claim 1 or 2, characterized in that... The method includes: (1) Under positive pressure of argon, a metal containing magnesium and gadolinium is melted in a manganese steel crucible melting furnace to obtain a magnesium-gadolinium binary alloy liquid; the mass content of gadolinium in the magnesium-gadolinium binary alloy liquid is 6%~30%; (2) Under positive argon pressure, magnesium-gadolinium binary alloy liquid is transported to a tightly coupled gas atomizing tank through a stainless steel conveying pipe. After tight coupling gas atomization and sieving, the magnesium-gadolinium binary alloy fuel powder is obtained. The tightly coupled gas atomizing tank has an annular slit gas atomizing nozzle with a diameter of 3mm to 8mm. The annular slit gas atomizing nozzle has a nozzle at its end with an eccentric angle of 3° to 7°. The liquid mass flow rate is controlled within the range of 14g / s to 17g / s. The high-pressure gas flow rate of the tightly coupled gas atomizing tank is 26m. 3 / h~34m 3 / h; atomization pressure is 3.0MPa - 5.0MPa.

4. The method for preparing magnesium-gadolinium binary alloy fuel powder as described in claim 3, characterized in that: Step (1), The oxygen volume content in the manganese steel crucible melting furnace is kept to no more than 0.01% by evacuation and argon filling; and / or, During the melting process, the positive pressure of argon gas is 103 kPa to 105 kPa; and / or, The melting superheat is 130℃~220℃; and / or, The melting temperature is 700℃~950℃; and / or, The melting time is 1 to 2 hours.

5. The method for preparing magnesium-gadolinium binary alloy fuel powder as described in claim 4, characterized in that: Step (1), The melting temperature is 780℃~850℃.

6. The method for preparing magnesium-gadolinium binary alloy fuel powder as described in claim 3, characterized in that: Step (2), The oxygen volume content in the tightly coupled gas atomizer is kept no greater than 0.01% by evacuation and argon purging; and / or, The argon positive pressure of the tightly coupled gas atomizer and pipeline is 102 kPa to 105 kPa; and / or, The pressure difference between the tightly coupled gas atomizing canister and the manganese steel crucible smelting furnace is 1 kPa to 4 kPa.

7. The method for preparing magnesium-gadolinium binary alloy fuel powder as described in claim 3, characterized in that: The diameter of the circumferential slit atomizing nozzle is 3mm~5mm; and / or, The eccentricity angle of the nozzle is 5°~7°.

8. The method for preparing magnesium-gadolinium binary alloy fuel powder as described in claim 3, characterized in that: Step (2), Under positive pressure of argon gas, powder of different particle sizes is obtained by mechanical screening and airflow separation.

9. A system for preparing magnesium-gadolinium binary alloy fuel powder as described in claim 1 or 2, characterized in that: The system includes a smelting furnace, a tightly coupled gas atomizing tank, a liquid conveying pipeline, a mechanical screening machine, a gas flow separator, and a high-pressure argon tank; The smelting furnace is a manganese steel crucible smelting furnace; The tightly coupled gas atomizing can is equipped with a tightly coupled gas atomizing device. The liquid delivery pipeline is made of stainless steel. The smelting furnace is connected to the top of the atomizing tank via a stainless steel pipe. The bottom of the atomizing tank is connected to the top of the mechanical screening machine, and the bottom of the mechanical screening machine is connected to the airflow separator. The high-pressure argon cylinder provides argon gas to the system; The smelting furnace, the tightly coupled gas atomizing tank, the mechanical screening machine, the air classifier, and the material conveying pipeline are all equipped with vacuuming devices and argon filling devices. The tightly coupled gas atomizing device has an annular slit-type gas atomizing nozzle, the diameter of which is 3mm~8mm; The annular slit atomizing nozzle has a nozzle at its end, and the eccentricity angle of the nozzle is 3°~7°. The mass flow rate of the liquid feed is controlled within the range of 14 g / s to 17 g / s; the high-pressure gas flow rate for close-coupled gas atomization is 26 m / s. 3 / h~34m 3 / h; atomization pressure is 3.0MPa - 5.0MPa.

10. The system of magnesium-gadolinium binary alloy fuel powder as described in claim 9, characterized in that: The diameter of the circumferential slit atomizing nozzle is 3mm~5mm; and / or, The eccentricity angle of the nozzle is 5°~7°.

11. A magnesium-gadolinium binary alloy fuel powder prepared by the method described in any one of claims 4 to 8 or the system described in any one of claims 9 to 10.

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