Preparation of Spherical/Quasi-Spherical Tantalum Powder
Release time:
2026-03-03
Tantalum is a high-temperature refractory metal. Its smelting typically employs the following process: first reducing compounds to metallic powder, followed by purification, sintering, and property adjustment to produce tantalum powder meeting diverse application requirements. When tantalum powder is processed into bars, plates, foils, tubes, wires, and other tantalum products, it is commonly referred to as metallurgical-grade tantalum powder. This grade leverages the distinct properties of tantalum metal for diverse applications. Due to its high melting point and low vapor pressure, tantalum is employed in aerospace, defense, and high-temperature vacuum furnace heating components, boats, and insulation materials. Its exceptional corrosion resistance against liquid metals and strong acids (except hydrofluoric acid), coupled with excellent thermal conductivity and chemical stability, also makes it a corrosion-resistant material in chemical and metallurgical industries. Tantalum's strong resistance to electrostatic migration makes it suitable for barrier layers between copper wiring and silicon in integrated circuits. Furthermore, due to the excellent biocompatibility of tantalum and/or niobium, they are commonly used in medical applications such as surgical sutures, custom prosthetics, intervertebral fusion devices, artificial joints, and bone repair materials.
3D-printed medical metal bone implants represent a novel medical technology emerging in recent years. Given tantalum and its alloys' high affinity with the human body and unique capabilities to induce bone growth and inhibit infection, research and applications of these materials in 3D-printed medical implants are increasingly prevalent. As the raw material for 3D printing, tantalum powder must primarily meet the following requirements: spherical or near-spherical morphology, narrow particle size distribution, and low impurity content (especially oxygen).
Literature indicates three primary techniques for producing spherical/quasi-spherical metal powders: plasma powder treatment [1-8], spray granulation [9-10], and hydrogenation-crushing [11-13]. Plasma powder treatment requires substantial equipment investment, high technical expertise, complex processes, and incurs high powder processing costs. Spray granulation technology is limited to metals or alloys with melting points below 2000°C, rendering it unsuitable for metals above this threshold, such as tantalum and niobium. Hydrogenation-based comminution produces tantalum powder with sharp edges and a broad particle size distribution.
This paper primarily investigates the preparation process for spherical/quasi-spherical tantalum powder using hydrogenation-crushing technology and the product properties of the resulting spherical/quasi-spherical tantalum powder.
1. Primary Process Route
1.1 Equipment and Raw/Auxiliary Materials
Equipment used in the preparation of spherical/quasi-spherical tantalum powder includes resistance hydrogenation furnaces, resistance dehydrogenation furnaces, ball mills, jet mills, rotary acid washing tanks, vacuum heat treatment furnaces, resistance deoxygenation furnaces, and vacuum drying ovens.
Required raw and auxiliary materials include high-purity tantalum ingots (purity 99.995%), nitric acid, hydrofluoric acid, pure water, high-purity hydrogen gas, and magnesium chips.
1.2 Process Flow
High-purity tantalum ingots subjected to secondary electron beam high-temperature bombardment serve as raw material. The process involves hydrogenation for hydrogen absorption, followed by grinding and sieving in a ball mill to produce tantalum powder. The powder particles pass through standard sieves of varying mesh sizes. Dehydrogenation treatment is then applied, followed by air jet milling for particle shaping, yielding raw powder with improved morphology. Chemical impurities are removed via acid washing. Vacuum heat treatment and magnesium reduction for oxygen reduction are performed to obtain spherical.
2. Processing Techniques
2.1 Hydrogenation
High-purity tantalum ingots are loaded into a thoroughly cleaned stainless steel crucible, suspended into a resistance hydrogenation furnace, evacuated to below 200 Pa, then charged with hydrogen to (1.0–2.0) × 10⁵ Pa. Heating is initiated while closely monitoring the pressure inside the crucible, which must not exceed 2. 0×10⁵ Pa to prevent rupture of the rubber hose and hydrogen leakage. When the temperature reaches 600–900°C, hold for 1–4 hours. After holding, power off and cool down to complete hydrogenation. During cooling, replenish hydrogen promptly until the tantalum ingot ceases absorbing hydrogen.
2.2 Ball Milling
Place hydrogenated tantalum ingots into a ball mill for comminution to obtain tantalum powder. The ball-milled material is sieved using standard screens of different mesh sizes. The resulting particle size distribution of the hydrogenated material will influence the final product's particle size distribution in subsequent processes. Screening the ball-milled material through different mesh sizes yields undersize powder of varying mesh grades. This ensures a concentrated final product particle size distribution with a low D90 value and excellent spheroidization. If oversize powder (+0.043 mm, +325 mesh) or coarser material is used for subsequent processing, the final product will exhibit larger particles, a higher D90 value, and poorer spheroidization.
2.3 Dehydrogenation
Place ball-milled tantalum powder into crucibles and load them into resistance dehydrogenation furnaces for treatment. Evacuate the chamber and replace the atmosphere with argon gas, pressurizing the reaction chamber to ≥0.04 MPa. Apply power to heat the chamber to 600–900°C and maintain this temperature for 1–4 hours to complete dehydrogenation. After holding, the reaction vessel is lowered into a cooling duct to cool before removal and screening, yielding dehydrogenated tantalum powder. Dehydrogenation minimizes hydrogen content while preventing ultrafine particles from agglomerating onto larger grains, ensuring good dispersion.
2.4 Airflow Shaping
Airflow shaping is performed after dehydrogenation to facilitate obtaining spherical/quasi-spherical powder with good shaping effects. The dehydrogenated tantalum powder is added to an airflow mill for airflow shaping. During air-jet shaping, the operating pressure is maintained at 5.0–7.0 kg, with both primary and secondary processing frequencies set at 20–50 Hz. The shaping duration is controlled between 10–30 hours. By adjusting process parameters during air-jet shaping, the powder morphology is modified. Ultrafine particles are concentrated in the secondary fraction, resulting in a primary fraction with a more concentrated particle size distribution and minimal ultrafine content.
2.5 Acid Washing
The air-jet shaped powder undergoes acid washing to remove chemical impurities introduced during ball milling and air-jet shaping, serving a purification function. The acid solution consists of a mixture of nitric acid and hydrofluoric acid, with a washing duration of 1–3 hours. The tantalum powder after acid washing is termed raw powder.
2.6 Vacuum Heat Treatment
The acid-washed raw powder is loaded into tantalum crucibles and placed in a vacuum heat treatment furnace. This process removes impurities like H and F introduced during acid washing while preventing sintering or grain growth of the metal powder. The vacuum heat treatment process requires the heating chamber vacuum level to reach 1.0 mPa before power-up and temperature rise. The heat treatment temperature is 1000–1250°C, with a duration of 30–90 minutes. The heat-treated product undergoes cooling, passivation, removal from the furnace, and screening.
2.7 Deoxygenation Acid Pickling
Deoxygenate the vacuum-heat-treated powder to reduce oxygen content while preventing sintering or agglomeration of the metal particles. Mix 0.5%–1.5% by weight of magnesium chips with the tantalum powder, load the mixture into a crucible, and place it in a deoxidation furnace. Heat treatment is first conducted under inert gas flow protection (e.g., argon) at 700–800°C for 1 to 4 hours. The mixture is then cooled and passivated to yield magnesium oxide, residual metallic magnesium, and deoxidized tantalum powder. The powder is acid-washed with a mixture of nitric acid and hydrofluoric acid to remove the metallic magnesium and magnesium oxide. The waste acid solution is then filtered out using pure water. The powder is dried under vacuum on separate trays and sieved using a 0. 3 Product Properties and Discussion
3. Product Properties and Discussion
The physicochemical properties of tantalum powder produced via the above process were measured. Example 1 represents powder obtained by ball milling through a 0.043 mm (325 mesh) sieve followed by subsequent processing. Example 2 represents powder obtained by ball milling through a 0.037 mm (400 mesh) sieve followed by subsequent processing.
3.1 Chemical Properties
The chemical impurities of tantalum powder prepared via different sieve sizes using the hydrogenation-crushing process are shown in Table 1. As indicated in Table 1, the use of secondary-impact high-purity tantalum ingots as raw material, combined with subsequent oxygen-reduction pickling treatment, yields tantalum powder with high purity exceeding 99%. 99% or higher, particularly exhibiting low oxygen content that meets the low-oxygen requirements for applications such as 3D printing and spraying. Example 2 tantalum powder is finer than Example 1, resulting in a slightly higher oxygen content ratio compared to Example 1 powder.
3.2 Physical Properties
The physical properties of tantalum powder prepared via the hydrogenation-crushing process using different mesh sizes are shown in Table 2 and Figures 1 and 2. Table 2 indicates that the particle size distributions of tantalum powders from Example 1 and Example 2 are relatively concentrated, exhibiting good flowability. By controlling the mesh size during ball milling and recovering ultrafine tantalum powder in the secondary powder through air-flow shaping, the primary powder exhibits a relatively concentrated particle size distribution. Moreover, during air-flow shaping, the tantalum powder particles undergo repeated collisions and friction under high-pressure airflow impact. smooth and rounded, with a morphology approaching spherical or near-spherical (Figure 2), exhibiting excellent flowability.
4. Conclusion
The hydrogenation process yielded spherical/quasi-spherical tantalum powder composed of independent, uniform particles. This powder exhibits a narrow particle size distribution with a low D90 value, excellent flowability, and low oxygen content, meeting application requirements for 3D printing, spraying, and other processes.
Reference: Nonferrous Metals (Smelting Section) (http://ysylbgrimm.cn) Vol. 12, 2018; Preparation of Spherical/Quasi-Spherical Tantalum Powder; Ren Ping, Zhou Huiqin, Chen Xueqing, Lin Fukun
The preparation of spherical/quasi-spherical tantalum powder is a crucial foundation for advancing the large-scale application of tantalum-based materials in additive manufacturing, high-temperature structural components, and high-end electronic devices. The company has established a complete technological chain—from high-quality powder preparation to performance regulation and additive manufacturing applications—with rare refractory metal spherical powders as its core product, complemented by 3D printing technology and customized forming services. Looking ahead, as performance demands for tantalum materials continue to rise in high-end equipment, aerospace, and nuclear power sectors, tantalum powders with high purity, high sphericity, and high flowability will become critical enablers. The company will deepen its expertise in refractory metal powder materials, continuously optimize spherical tantalum powder production processes, and leverage comprehensive 3D printing service capabilities to deliver more stable, efficient, and engineering-valued integrated material and forming solutions. For further product details, please contact our Sales Manager,Sukie Zhu, at +86 13378626726.
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