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

Abstract

The application discloses a gradient ion adsorption mixing method of high-tungsten-based multi-element alloy powder and a core-shell structure powder. In view of the problems of mixing segregation (CV>15%), rare earth oxidation (>1200ppm) and interface brittleness, a three-step method is adopted: 1. surface hydroxylation: H2O230vol%+HNO3 etching makes the tungsten powder hydrophilic (contact angle≤10°); 2. pH gradient adsorption: step-by-step pH control (pH 3.0-4.0 preferentially adsorbs rare earths→pH 6.0-8.0 adsorbs light metals); 3. in-situ reduction: gradient heating in a hydrogen-argon mixed atmosphere to generate a core-shell structure. The obtained powder has a coating rate of ≥95% (SEM-EDS), an oxygen content of ≤800ppm (ASTM E1019) and a W / Al distribution CV value of ≤4.2% (GB / T 5060). The powder is suitable for high-end fields such as military or aerospace.

Description

Technical Field

[0001] This invention relates to the field of metal powder processing technology, specifically to a gradient ion adsorption mixing method for high tungsten-based multi-component alloy powder and its composite powder. Background Technology

[0002] High-tungsten-based multi-component alloys are a cutting-edge new material for both military and civilian applications. Currently, the alloy billet uses tungsten as the base material, adding various active metallic elements such as Zr, Ni, and Al. This results in high density and high inertness at room temperature and pressure, but also high energy content and secondary energy release under severe impact or special conditions. The challenges in its preparation lie in: 1. Density difference segregation, W (19.25 g / cm³). 3 ) and Al (2.7g / cm 3 1. Density differences of elements such as Sc and Y can be several times, which easily leads to gravity stratification and uneven component distribution during traditional ball milling. 2. Oxidation failure of rare earth elements: During mechanical ball milling, rare earth elements such as Sc and Y have an oxidation rate of 30-40%, resulting in low element utilization and easy oxidation failure. 3. Interface brittleness: In aluminum-containing products, high-melting-point W powder and low-melting-point Al powder are prone to forming an unalloyed "core-shell" structure during mechanical alloying, resulting in brittle WAl. 12 This reduces the toughness of the sintered product, making subsequent finishing difficult.

[0003] Traditional mixing methods affect the activity and uniformity of material components, making it difficult to continue subsequent processes. Therefore, such materials have extremely high requirements for mixing equipment and processes, and have not yet been able to form industrialized products. Summary of the Invention

[0004] To overcome the shortcomings of the prior art, this invention provides a gradient ion adsorption mixing method for high tungsten-based multi-component alloy powder and its composite powder, addressing the problems of mixed material segregation (CV > 15%), rare earth oxidation (> 1200 ppm) and interfacial brittleness. This method overcomes the three major defects of high density difference mixed material segregation, rare earth element oxidation, and the formation of brittle phases at aluminum-containing interfaces.

[0005] This invention is achieved through the following technical solution:

[0006] A gradient ion adsorption mixing method for high-tungsten-based multi-component alloy powder, characterized by comprising the following steps:

[0007] Step 1: Surface hydroxylation

[0008] Tungsten powder (10-50μm, purity ≥99.9%) is etched with H2O2 and HNO3 solution (pH=1.5-2.5), H2O2 concentration 30vol%, and ultrasonically treated for 10-30min to hydrophilize the tungsten powder and obtain a hydrophilic surface with a contact angle ≤10°.

[0009] Step 2, pH gradient ion adsorption:

[0010] 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).

[0011] Stepwise adsorption control:

[0012] (1) Low pH (3.0-4.0): preferentially adsorbs rare earth elements, i.e., highly electronegative ions (Y). 3+ / Sc 3+ / Ti 4+ / Mo 6+ ), accounting for 40-60 mol% of the total; physical adsorption: the electrostatic adsorption of cations on the surface of hydroxyl tungsten is controlled by adjusting the pH, without the need for additional adsorbents;

[0013] (2) High pH (6.0-8.0): Adsorbs light metals, i.e., low electronegativity ions (Al). 3+ / Fe 3+ / Ge 4+ / Ni 2+ ), accounting for <40 mol% of the total;

[0014] Step 3: In-situ thermal reduction:

[0015] Gradient heating was performed in a hydrogen-argon mixture atmosphere (volume ratio 1:3):

[0016] (1) Keep at 300℃-450℃ for 0.5-1h (reduction of Y / Sc / Ti oxides), followed by hydrogen reduction;

[0017] (2) Keep at 550-600℃ for 0.5-1h (reducing Al / Fe / Ge to metallic state), then reduce with hydrogen to form core-shell powder of "W and other metal elements";

[0018] Step 4: Low-temperature dynamic mixing

[0019] In a liquid nitrogen circulating environment at -50±5℃ and an inert gas protective environment, the core-shell powder and the remaining element powder (such as Mo, Ni) are mixed in three dimensions for 2-4 hours at a speed of ≤150 rpm.

[0020] Further optimization of element combinations:

[0021] The main components (by mass percentage) of the aforementioned multi-element energetic alloy billet are: 50-80% tungsten powder (e.g., 50%, 53%, 58%, 65%, 68%, 72%, 78%, 80%), and 20-50% other elements (e.g., 20%, 22%, 28%, 32%, 35%, 42%, 47%, 50%). These other elements are two or more of the following: scandium (SC), titanium (Ti), yttrium (Y), nickel (Ni), germanium (Ge), aluminum (Al), iron (Fe), and molybdenum (Mo). The target cation contains 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%.

[0022] Further preferred, carbonized reinforced interface:

[0023] When Mo is present, CH4 is introduced during the reduction stage (flow rate 10-50 mL / min) to make MoO4 2- It is transformed into a Mo2C layer, forming a "W and Ti-Y-Mo2C" gradient interface.

[0024] In a further preferred step, when preparing a solution containing ≥2 target cations, the anions are matched with the corresponding anions according to the cations. The etching solution contains residual nitrate ions, and other ions such as chloride ions and sulfate ions are also acceptable. The solution is not fixed, and the anions do not participate in the adsorption.

[0025] Further optimized, the obtained high-tungsten-based multi-component alloy composite powder:

[0026] (1) Core-shell structure: The tungsten core surface is covered with a gradient coating layer with a thickness of 100-500 nm, and the coating rate is ≥95%;

[0027] (2) Elemental distribution: Light elements (Al / Ge) are enriched in the surface layer, while heavy rare earth elements (Y / Sc) are enriched near the tungsten interface;

[0028] (3) Oxygen content: ≤800ppm (Sc / Y element oxidation rate <5%).

[0029] 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 tungsten content of 50-80wt%, containing a combination of ≥3 elements of scandium (SC) / titanium (Ti) / yttrium (Y) / nickel (Ni) / germanium (Ge) / aluminum (Al) / iron (Fe) / molybdenum (Mo), which is suitable for high-end fields such as military or aerospace.

[0030] Based on the performance requirements of existing materials, this invention achieves the following performance breakthroughs through a three-step mixing process design of "surface activation-pH gradient adsorption-in-situ reduction":

[0031] .

[0032] Attached Description

[0033] Figure 1 SEM images of high tungsten-based multi-component alloy powder (W-10Y-5Sc-3Al, wt%) produced using this process.

[0034] Figure 2 SEM image of the carbonized interface-reinforced powder (W-12Mo-5Ti-3Y, wt%) produced using this process. Detailed Implementation

[0035] The gradient ion adsorption mixing method for high-tungsten-based multi-element alloy powder and the core-shell structure powder of the present invention address the problems of mixing segregation (CV > 15%), rare earth oxidation (> 1200 ppm) and interfacial brittleness by employing a three-step method:

[0036] 1. Surface hydroxylation: Etching with H2O2 30 vol% + HNO3 hydrophilizes the tungsten powder (contact angle ≤10°);

[0037] 2. pH gradient adsorption: pH is controlled in steps (rare earth elements are preferentially adsorbed at pH 3.0-4.0 → light metals are adsorbed at pH 6.0-8.0).

[0038] 3. In-situ reduction: Gradient heating in a hydrogen-argon mixed atmosphere generates a core-shell structure.

[0039] The resulting powder has a coating rate ≥95% (SEM-EDS), oxygen content ≤800ppm (ASTM E1019), and W / Al distribution CV value ≤4.2% (GB / T 5060). It is suitable for high-end fields such as military or aerospace.

[0040] Example 1: High tungsten-based multi-component alloy powder (W-10Y-5Sc-3Al, wt%)

[0041] 1. Surface treatment: 45μm tungsten powder is immersed in H2O2 (30%) + HNO3 (pH=2.0) etching solution and ultrasonicated at 40kHz for 20min;

[0042] 2. Equipped with gradient adsorption solution:

[0043] Solution 1 (pH=3.5): Adsorption of Y 3+ (0.25mol / L) → Sc 3+ (0.12 mol / L);

[0044] Solution 2 (pH=7.0): Adsorption of Al 3+ (0.18 mol / L);

[0045] 3. In-situ restoration:

[0046] 450℃ / 1h (Y / Sc reduction) → 600℃ / 0.5h (Al metallization), H2 and Ar are mixed in a 1:3 volume ratio for protection, and the flow rate is 30mL / min;

[0047] 4. Low-temperature mixing:

[0048] Mix with 5μm aluminum powder in a three-dimensional manner under liquid nitrogen circulation at -50℃ for 2-2.5h, with argon protection (concentration 99.99%), and mixing speed 120-150rpm.

[0049] 5. Material performance results: powder coating rate 96.2%, oxygen content 742ppm, W / Al distribution CV value 3.8%, and flowability 24.7 s / 50g.

[0050] 6. Key Innovation: Achieving a coating rate of >96% (traditional ≤80%) through "low pH preferential adsorption of rare earth elements (Y / Sc)", solving the problem of oxidation of highly active elements.

[0051] Example 2: Carbonized interface-reinforced powder (W-12Mo-5Ti-3Y, wt%)

[0052] 1. Surface treatment: 45μm tungsten powder is immersed in H2O2 (30%) + HNO3 (pH=2.0) etching solution and ultrasonicated at 40kHz for 20min;

[0053] 2. Equipped with gradient adsorption solution:

[0054] Solution 1 (pH=4.0): Adsorption of Y 3+ (0.08 mol / L);

[0055] Solution 2 (pH=6.5): Adsorption of TiO2 2+ (0.1 mol / L);

[0056] Solution 3 (pH=7.5): Adsorbed MoO4 2- (0.15mol / L);

[0057] 3. Carbonization and reduction:

[0058] Y and Ti were reduced in a hydrogen-argon mixture atmosphere with a volume ratio of 1:3 at a flow rate of 30 mL / min; CH4 was introduced at 450℃ for 1 h at 20 mL / min at 550℃ for 1 h to form a Mo2C interface layer and generate W and Y-Ti-Mo2C core-shell structure powders.

[0059] 4. Low-temperature three-dimensional mixing:

[0060] Three-dimensional mixing was performed under liquid nitrogen circulation at -50℃ for 2-2.5 hours, with argon protection (concentration 99.99%) and mixing speed of 120-150 rpm.

[0061] 5. Material performance results: powder coating rate 94.8%, oxygen content 698ppm, Mo / Y distribution CV value 4.2%, flowability 26.4 s / 50g.

[0062] 6. Key Innovation: Through "high pH adsorption of MoO4" 2- "+CH4 carbonization" generates a continuous Mo2C interface layer with a thickness of over 150nm, replacing traditional mechanically mixed Mo powder and reducing oxygen content by more than 65%.

[0063] The gradient ion adsorption mixing method for high-tungsten-based multi-element alloy powder of the present invention yields a core-shell structure powder with a coating rate ≥95% (SEM-EDS), oxygen content ≤800ppm (ASTM E1019), and W / Al distribution CV value ≤4.2% (GB / T 5060). It is suitable for high-end fields such as military or aerospace applications.

[0064] Except for the technical features described in the specification, all other 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 in that: The following steps are performed sequentially: Step 1: Hydroxylation of tungsten core surface: Tungsten powder with a particle size of 10-50 μm and a purity of ≥99.9% is immersed in an etching solution, which is 30 vol% H2O2 + HNO3 adjusted to pH 1.5-2.

5. The solution is then ultrasonically treated for 10-30 min to obtain a hydrophilic surface with a contact angle ≤10°. Step 2, pH gradient ion adsorption: Prepare a solution containing ≥2 target cations, wherein the target cations are Sc 3+ Ti 4+ Y 3+ Ni 2+ 、Ge 4+ Al 3+ Fe 3+ Or Mo 6+ The target total cation concentration is 0.1-0.5 mol / L; Stepwise adsorption control: At low pH (3.0-4.0): preferentially adsorbs highly charged ions, including Y2. 3+ ,Sc 3+ Ti 4+ and Mo 6+ ; High pH, ​​6.0-8.0: adsorbs low-electrochemical ions, including Al. 3+ Fe 3+ 、Ge 4+ and Ni 2+ ; Physical adsorption: The electrostatic adsorption of cations on the surface of tungsten hydroxylide is controlled by adjusting the pH, without the need for additional adsorbents; Step 3: In-situ thermal reduction self-assembly: Gradient heating was performed in a hydrogen-argon mixture atmosphere with a volume ratio of 1:3: Reduce Y, Sc, or Ti oxides by holding at 300℃-450℃ for 0.5-1 hour; By holding at 550-600℃ for 0.5-1 hour, Al, Fe, or Ge are reduced to their metallic state. Hydrogen reduction; forming core-shell powder; Step 4: Low-temperature dynamic mixing: The core-shell powder and the remaining element powder were mixed in a liquid nitrogen environment at -50±5℃ for 2-4 hours at a rotation speed ≤150 rpm. The main components of the above-mentioned multi-element alloy powder are as follows by mass percentage: tungsten powder 50-80%, other elements 20-50%, and other elements are two or more of the following elements: scandium (Sc), titanium (Ti), yttrium (Y), nickel (Ni), germanium (Ge), aluminum (Al), iron (Fe) and molybdenum (Mo); the target cation contains at least one rare earth element and at least one light metal element, and the total rare earth element accounts for 5-15 mol.

2. 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 is introduced during the reduction stage at a flow rate of 10-50 mL / min to induce MoO4. 2- It is converted into a Mo2C layer.

3. The gradient ion adsorption mixing method for high-tungsten-based multi-component alloy powder according to claim 1, characterized in that: The second step involves preparing a solution containing ≥2 target cations. The anions are matched with the corresponding anions based on the cations, and the anions do not participate in adsorption.

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