Powder Bed Reaction Layer
The powder bed reaction layer is the boundary layer between the molten metal and the unbound powder. Here thermal diffusion and sintering effects occur, which influence surface roughness and edge zone properties.
Physical-Chemical Mechanism of Action
The powder bed reaction layer forms through contact between the molten metal and the unbound powder. Thermal diffusion occurs, where atoms from the melt diffuse into the powder and vice versa. These processes lead to sintering effects that alter the chemical composition and structure of the material.
Metallurgical Relevance & Welding Risks
The powder bed reaction layer affects the surface roughness and the edge zone properties of the part. A layer that is too thin or too thick can cause uneven stresses, cracks, or missing properties. It can also affect hardness and strength, which is critical for mechanical load capacity.
Workshop Practice & Instructions
To ensure an optimal powder bed reaction layer, the following measures should be taken:
• Use powder with the correct chemical composition and size.
• Adjust the melting temperature and time to enable homogeneous diffusion.
• Control the cooling duration and temperature to avoid uneven stresses.
• Use suitable protective agents to protect the powder from corrosion and contamination.