Gradient ion adsorption mixing method for high-tungsten-based multi-component alloy powder

Abstract

The invention discloses a gradient ion adsorption mixing method of high-tungsten-based multi-component alloy powder and core-shell structure powder. Aiming at the problems of mixed material segregation (CV is greater than 15%), rare earth oxidation (greater than 1200 ppm) and interface brittleness, the method comprises the following three steps: 1, surface hydroxylation: carrying out H2O2 30vol% and HNO3 etching to hydrophilize tungsten powder (the contact angle is less than or equal to 10 degrees); 2, pH gradient adsorption: regulating the pH step by step (preferably adsorbing rare earth when the pH is 3.0-4.0, and adsorbing light metal when the pH is 6.0-8.0); 3, in-situ reduction: carrying out gradient heating in a hydrogen and argon mixed atmosphere to generate a core-shell structure; the coating rate of the obtained powder is larger than or equal to 95% (SEM-EDS), the oxygen content is smaller than or equal to 800 ppm (ASTM E1019), and the W / Al distribution CV value is smaller than or equal to 4.2% (GB / T 5060). The method is suitable for military or aerospace and other high-end fields.

Description

Technical Field

[0001] The present invention relates to the technical field of metal powder processing, and in particular to a gradient ion adsorption mixing method for high-tungsten-based multi-component alloy powder and a composite powder thereof. Background Art

[0002] High-tungsten-based multi-component alloy is a cutting-edge new material for both military and civilian use. Currently, the alloy billet uses tungsten as the base material, with the addition of various active metal elements such as Zr, Ni, and Al. This gives the material high density and high inertness at room temperature and pressure, but triggers high energy content and secondary energy release when subjected to violent impact or special conditions. The difficulties in preparing this material are: 1. Density differential segregation, W (19.25g / cm 3 ) and Al (2.7g / cm 3 ) or other elements with density differences of up to several times, traditional ball milling mixing is prone to gravity stratification and uneven distribution of components; 2. Oxidation failure of rare earth elements: During the mechanical ball milling process, the oxidation rate of rare earth elements such as Sc / Y reaches 30-40%, resulting in low element utilization and easy oxidation failure of the elements; 3. Interface brittleness: In aluminum-containing products, high-melting-point W powder and low-melting-point Al powder are prone to produce unalloyed "core-shell" structure during mechanical alloying, generating brittle WAl 12 This will reduce the toughness of the sintered product and make subsequent finishing difficult.

[0003] Traditional mixing methods affect the activity and uniformity of material components, making subsequent processes difficult to continue. Therefore, this type of material has extremely high requirements for mixing equipment and processes, and has not yet been able to form an industrialized product. Summary of the Invention

[0004] In order to make up for the shortcomings of the existing technology, the present invention provides a gradient ion adsorption mixing method for high-tungsten-based multi-component alloy powder and its composite powder to address the problems of mixing segregation (CV>15%), rare earth oxidation (>1200ppm) and interface brittleness, overcoming the three major defects of high-density poor mixing segregation, rare earth element oxidation and the formation of aluminum-containing interface brittle phase.

[0005] The present invention is achieved through the following technical solutions: A gradient ion adsorption mixing method for high tungsten-based multi-component alloy powder, characterized by comprising the following steps: Step 1: Surface hydroxylation Tungsten powder (10-50 μm, purity ≥99.9%) was etched with H2O2 and HNO3 solution (pH = 1.5-2.5), with H2O2 concentration of 30 vol% and ultrasonic treatment for 10-30 min to hydrophilize the tungsten powder and obtain a hydrophilic surface with a contact angle of ≤10°; Step 2: pH gradient ion adsorption: Prepare a solution containing ≥2 target cations (Sc 3+ / Ti 4+ / Y 3+ / Ni 2+ / Ge 4+ / Al 3+ / Fe 3+ / Mo 6+ , total concentration 0.1-0.5 mol / L); Step-by-step adsorption control: (1) Low pH (3.0-4.0): Preferential adsorption of rare earth ions, i.e., highly electronegative ions (Y 3+ / Sc 3+ / Ti 4+ / Mo 6+ ), accounting for 40-60 mol% of the total; physical adsorption: by adjusting the pH to control the electrostatic adsorption of cations on the surface of hydroxylated tungsten, no additional adsorbent is required; (2) High pH (6.0-8.0): Adsorption of light metals, i.e. low electronegative ions (Al 3+ / Fe 3+ / Ge 4+ / Ni 2+ ), accounting for <40mol% of the total; Step 3: In-situ thermal reduction: Gradual temperature increase in a hydrogen-argon (volume ratio 1:3) mixed atmosphere: (1) Keep at 300℃-450℃ for 0.5-1h (reduction of Y / Sc / Ti oxides), hydrogen reduction; (2) Keep at 550-600℃ for 0.5-1h (reduce Al / Fe / Ge to metallic state), and then reduce with hydrogen to form a core-shell powder of "W and other metal elements"; Step 4: Low temperature dynamic mixing The core-shell powder and the remaining element powder (such as Mo, Ni) are three-dimensionally mixed in an inert gas protection environment at -50±5℃ with a liquid nitrogen circulation and a rotation speed of ≤150rpm for 2-4h.

[0006] Further preferably, the element combination is optimized: The multi-component energetic alloy billet comprises primarily (by mass): 50-80% tungsten powder (e.g., 50%, 53%, 58%, 65%, 68%, 72%, 78%, and 80%), and 20-50% other elements (e.g., 20%, 22%, 28%, 32%, 35%, 42%, 47%, and 50%). The other elements may be two or more of scandium (Sc), titanium (Ti), yttrium (Y), nickel (Ni), germanium (Ge), aluminum (Al), iron (Fe), and molybdenum (Mo). The target cations comprise at least one rare earth element (Sc / Y) and at least one light metal element (Al), with the total rare earth element (Sc / Y) comprising 5-15 mol%.

[0007] Further preferably, the carbonization strengthened interface: When Mo is present, CH4 (flow rate 10-50 mL / min) is introduced during the reduction phase to make MoO4 2- Transformed into Mo2C layer, forming a "W and Ti-Y-Mo2C" gradient interface.

[0008] Further preferably, in the second step, when preparing a solution containing ≥2 target cations, the anions are matched with the corresponding anions according to the cations, and the etching solution has residual nitrate ions. Other ions such as chloride ions and sulfate ions can also be non-fixed, and the anions do not participate in the adsorption.

[0009] Further preferably, the obtained high tungsten-based multi-component alloy composite powder is: (1) Core-shell structure: The surface of the tungsten core is covered with a gradient coating layer with a thickness of 100-500 nm, and the coating rate is ≥95%; (2) Element distribution: light elements (Al / Ge) are enriched in the surface layer, and heavy rare earth elements (Y / Sc) are enriched near the tungsten interface; (3) Oxygen content: ≤800ppm (Sc / Y element oxidation rate <5%).

[0010] The beneficial effects of the present invention are: the mixing method of the present invention and the composite powder produced therefrom are a multi-component alloy powder mixing method with a tungsten content of 50-80wt%, comprising a combination of ≥3 elements of scandium (SC) / titanium (Ti) / yttrium (Y) / nickel (Ni) / germanium (Ge) / aluminum (Al) / iron (Fe) / molybdenum (Mo), and are suitable for high-end fields such as military or aerospace.

[0011] Based on the performance requirements of existing materials, the present invention achieves the following performance breakthroughs through the three-step mixing process structure design of "surface activation-pH gradient adsorption-in situ reduction": .

[0012] Description of the drawings Figure 1This is the SEM electron microscope image of the high tungsten-based multi-component alloy powder (W-10Y-5Sc-3Al, wt%) produced using this process.

[0013] Figure 2 This is the SEM electron microscope image of the carbonized interface strengthened powder (W-12Mo-5Ti-3Y, wt%) produced by this process. DETAILED DESCRIPTION

[0014] The gradient ion adsorption mixing method for high-tungsten-based multi-element alloy powder and the core-shell structure powder of the present invention adopt a three-step method to address the problems of mixing segregation (CV>15%), rare earth oxidation (>1200ppm) and interface brittleness: 1. Surface hydroxylation: H2O2 30vol% + HNO3 etching makes the tungsten powder hydrophilic (contact angle ≤ 10°); 2. pH gradient adsorption: pH is adjusted step by step (pH 3.0-4.0 preferentially adsorbs rare earths → pH 6.0-8.0 preferentially adsorbs light metals); 3. In-situ reduction: Gradual heating in a hydrogen and argon mixed atmosphere to generate a core-shell structure.

[0015] The resulting powder has a coverage ratio of ≥95% (SEM-EDS), an oxygen content of ≤800ppm (ASTM E1019), and a W / Al distribution CV value of ≤4.2% (GB / T 5060). It is suitable for high-end applications such as military and aerospace.

[0016] Example 1: High Tungsten-Based Multi-Component Alloy Powder (W-10Y-5Sc-3Al, wt%) 1. Surface treatment: 45μm tungsten powder was immersed in H2O2 (30%) + HNO3 (pH = 2.0) etching solution, and ultrasonic treatment was performed at 40kHz for 20min. 2. Prepare gradient adsorption solution: Solution 1 (pH=3.5): adsorption of Y 3+ (0.25mol / L) → Sc 3+ (0.12mol / L); Solution 2 (pH=7.0): Adsorption of Al 3+ (0.18mol / L); 3. In situ reduction: 450℃ / 1h (Y / Sc reduction) → 600℃ / 0.5h (Al metallization), H2:Ar mixed protection (volume ratio: 1:3), flow rate: 30mL / min; 4. Low temperature mixing: The mixture was three-dimensionally mixed with 5μm aluminum powder at -50℃ in liquid nitrogen circulation for 2-2.5h, with argon protection (concentration 99.99%), and the mixing speed was 120-150rpm.

[0017] 5. Material performance results: powder coverage 96.2%, oxygen content 742ppm, W / Al distribution CV value 3.8%, flowability 24.7 s / 50g.

[0018] 6. Key innovation: Through "low pH preferential adsorption of rare earth (Y / Sc)", a coverage rate of >96% (traditional ≤80%) is achieved, solving the problem of oxidation of highly active elements.

[0019] Example 2: Carbonized interface strengthening powder (W-12Mo-5Ti-3Y, wt%) 1. Surface treatment: 45μm tungsten powder was immersed in H2O2 (30%) + HNO3 (pH = 2.0) etching solution, and ultrasonic treatment was performed at 40kHz for 20min. 2. Prepare gradient adsorption solution: Solution 1 (pH = 4.0): adsorption of Y 3+ (0.08mol / L); Solution 2 (pH = 6.5): adsorption of TiO 2+ (0.1mol / L); Solution 3 (pH=7.5): adsorption of MoO4 2- (0.15mol / L); 3.Carbonization reduction: Reduction of Y and Ti was carried out in a hydrogen-argon mixed atmosphere with a volume ratio of 1:3 at a flow rate of 30 mL / min; CH4 (20 mL / min) was passed through the mixture at 450°C / 1h → 550°C for 1h to form a Mo2C interface layer and generate W and Y-Ti-Mo2C core-shell structure powders; 4. Low temperature three-dimensional mixing: The three-dimensional mixing was carried out for 2-2.5 h under liquid nitrogen circulation at -50 °C, with argon protection (concentration 99.99%) and a mixing speed of 120-150 rpm.

[0020] 5. Material performance results: powder coverage 94.8%, oxygen content 698ppm, Mo / Y distribution CV value 4.2%, flowability 26.4 s / 50g.

[0021] 6. Key innovation: Adsorption of MoO4 at high pH 2- +CH4 carbonization” generates a continuous Mo2C interface layer with a thickness exceeding 150nm, replacing traditional mechanically mixed Mo powder and reducing the oxygen content by more than 65%.

[0022] The present invention's gradient ion adsorption mixing method for high-tungsten-based multi-component alloy powders produces a core-shell structured powder with a coverage ratio ≥95% (SEM-EDS), an oxygen content ≤800 ppm (ASTM E1019), and a W / Al distribution CV value ≤4.2% (GB / T 5060). This method is suitable for high-end applications such as military and aerospace applications.

[0023] Except for the technical features described in the specification, the remaining technical features are known to those skilled in the art.

Claims

1. A gradient ion adsorption mixing method for high tungsten-based multi-component alloy powder, characterized by: The following steps are performed in sequence: The first step is hydroxylation of the tungsten core surface: Immerse 10-50μm tungsten powder with a purity of ≥99.9% in an etching solution composed of 30vol% H2O2 + HNO3, pH=1.5-2.5, and ultrasonically treat for 10-30min to obtain a hydrophilic surface with a contact angle of ≤10°; Step 2: pH gradient ion adsorption: Prepare a solution containing ≥2 target cations, using Sc as the cation 3+ / Ti 4+ / Y 3+ / Ni 2+ / Ge 4+ / Al 3+ / Fe 3+ / Mo 6+ Several of them, with a total concentration of 0.1-0.5 mol / L; Step-by-step adsorption control: Low pH (3.0-4.0): preferentially adsorbs highly charged ions (Y 3+ / Sc 3+ / Ti 4+ / Mo 6+ ); High pH (6.0-8.0): Adsorption of low-charge ions (Al 3+ / Fe 3+ / Ge 4+ / Ni 2+ ); Physical adsorption: The electrostatic adsorption of cations on the surface of hydroxylated tungsten is controlled by adjusting the pH, without the need for additional adsorbents; Step 3: In-situ thermal reduction self-assembly: Gradual temperature increase in a hydrogen-argon mixed atmosphere with a volume ratio of 1:3: Keep at 300-450℃ for 0.5-1 hour to reduce Y / Sc / Ti oxides; Keep at 550-600℃ for 0.5-1 hour to reduce Al / Fe / Ge to metallic state. Hydrogen reduction; forming "W and other metal elements" core-shell powder; Step 4: Low temperature dynamic mixing The core-shell powder and the remaining element powder were three-dimensionally mixed in a liquid nitrogen environment at -50±5°C for 2-4 hours at a rotation speed of ≤150rpm.

2. The gradient ion adsorption mixing method for high tungsten-based multi-component alloy powder according to claim 1, characterized in that: The mass percentages of the main components of the above-mentioned multi-component energetic alloy billet are: 50-80% tungsten powder, 20-50% other elements, and the other elements are two or more of scandium (SC) / titanium (Ti) / yttrium (Y) / nickel (Ni) / germanium (Ge) / aluminum (Al) / iron (Fe) / molybdenum (Mo) elements; the target cations contain at least one rare earth element and at least one light metal element, and the total amount of rare earth elements accounts for 5-15 mol%.

3. The gradient ion adsorption mixing method for high tungsten-based multi-component alloy powder according to claim 1, characterized in that: When Mo is present, CH4 (flow rate 10-50 mL / min) is introduced during the reduction phase to make MoO4 2- Converted into Mo2C layer.

4. The gradient ion adsorption mixing method for high tungsten-based multi-component alloy powder according to claim 1, characterized in that: In the second step, when preparing a solution containing ≥2 target cations, the anions are matched with the corresponding anions according to the cations. The etching solution has residual nitrate ions, chloride ions, and sulfate ions. They are non-fixed and the anions do not participate in adsorption.

5. A high-tungsten-based multi-component alloy composite powder prepared by the method of any one of claims 1 to 3, characterized in that: (1) Core-shell structure: The surface of the tungsten core is covered with a gradient coating layer with a thickness of 100-500 nm, and the coating rate is ≥95%; (2) Element distribution: light elements (Al / Ge) are enriched in the surface layer, and heavy rare earth elements (Y / Sc) are enriched near the tungsten interface; (3) Oxygen content: ≤800ppm (Sc / Y element oxidation rate <5%).

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