Metal Powders, Satellites and Gas Atomization Techniques

Introduction

The manufacturing of metal powders and advanced manufacturing techniques are closely intertwined in technologies such as powder metallurgy, metal injection molding (MIM), and additive manufacturing (AM). One critical factor affecting the quality of metal powders is the presence of satellites and the methods used for powder production. Gas atomization, an advanced technique where molten metal is transformed into fine powdered particles, is one method that delivers high-quality in-house powders. This blog explores the significance of satellites in metal powders and examines gas atomization techniques in detail.

Satellites and Metal Powders

Satellites are small particles that adhere to the surfaces of larger powder particles. The presence of these foreign particles on the surface of metal powders is referred to as satellites. They significantly impact the properties and performance of metal powders, particularly in additive manufacturing and metal injection molding (MIM) processes. Satellites can form for several reasons:

  1. Cooling : Rapid cooling during powder production can cause smaller particles to attach to larger ones.
  2. Collision: In the atomization process, particles collide and stick together before solidifying.
  3. Electrostatic Forces: Static charges attracts smaller particles to the surfaces of larger particles.

Disadvantages of  Satellites

                 The presence of satellites affects the material formation in an adverse manner thus it is important to know how the product get affected.

  • Flowability: Satellites reduce the flowability of metal powders, making them less efficient for powder bed fusion and other AM processes.
  • Packing Density: They can decrease the packing density, leading to issues related in powder spreading and layering.
  • Surface Finish: The presence of satellites can negatively affect the surface finish of the final product.
  • Mechanical Properties: Inconsistent particle sizes due to satellites can result in uneven sintering and poorer mechanical properties.

Gas Atomization

Gas atomization is one of the most widely used technique for the production of high-quality metal powders. This method involves disintegrating a molten metal stream into fine droplets using a high-velocity gas. The process regulated the production of spherical particles with minimal satellites. Gas atomized particles are widely used for the production of metal parts by utilizing the technologies like additive manufacturing and metal injection molding. Good quality powder results in great mechanical properties including thermal conductivity, density, packaging factors etc..

The Gas Atomization Process

  1. Melting: The metal is melted in a crucible, often using induction or resistance heating.
  2. Atomization: The molten metal is then forced through a nozzle where it is atomized by a high-pressure inert gas stream (commonly nitrogen or argon). The gas breaks the molten stream into fine droplets.
  3. Solidification: As the droplets cool and solidify, they form spherical particles.
  4. Collection: The solidified particles are collected and processed for further use.
Gas-atomization-process

Picture Credit: https://www.researchgate.net/figure/Schematic-diagram-of-gas-atomization-processing_fig1_227032206

Advantages of Gas Atomization

  • Formation of spherical particles that enhance flowability and packing density
  • Controlled size distribution that delivers a consistent result while manufacturing
  • Inert gas under high velocity helps in minimizing the formation of satellites resulting in a cleaner powder
  • The process can be utilized by various metals and alloys thus this  versatile nature can be utilized in different industries
  • Satellite: The new-age addition of anti-satellite blower in atomizers inject a part of the atomization gas back into the atomization zone to create a swirl effect to take away fine particles swiftly from the hot atomization zone. This minimizes the satellite formation.

 How Gas Atomization becomes an economical and environmentally friendly process?

Recent advancements in gas atomization techniques have focused on improving efficiency and powder quality:

  • Closed-Loop Systems: These systems recycle the atomizing gas, reducing costs and environmental impact.
  • Advanced Nozzle Designs: Innovations in nozzle technology enhance atomization efficiency and particle size control.
  • Real-Time Monitoring: Implementing real-time monitoring systems ensures consistent quality and immediate adjustment of process parameters.

  Conclusion

Demand for precision and efficiency in industries such as aerospace, medical, and defense is increasing daily, highlighting the importance of the technologies we use to produce critical components. Two widely used manufacturing techniques are Metal Injection Molding (MIM) and additive manufacturing (including LMM, LPBF, Binder Jetting, etc.). In both technologies, the primary raw material consists of refined, satellite-free powder particles with specific mechanical properties and micron sizes.

Gas atomization is one technique that effectively removes foreign particles. This modern process ensures proper particle distribution while maintaining an environmentally friendly approach. At INDO-MIM, our commitment to environmentally sustainable initiatives always takes precedence. Thus, we have installed multiple gas atomizers to develop the powder particles used as our basic raw material.