ADVANCED MATERIALS & PROCESSES | MARCH 2026 15 corrosion resistance, or thermal conductivity of the joint. In many cases, specialized alloys or high-melting-point fillers are chosen to withstand high loads and temperatures in the components’ operating environment. Brazing has established itself as a highly versatile process and is used in many industries, including aerospace, automotive manufacturing, electronics production, as well as in the manu- facture of heat exchangers and piping. It offers advantages such as the ability to join materials that cannot be welded, high accuracy and precision during the joining operation, and minimal deformation of the components due to the relatively low-temperature brazing process compared to welding. Another advantage of brazing is the ability to join components without excessive heat input, which allows for the processing of delicate materials or complex component structures without damaging them or impairing their properties. Additive brazing is a thermal process performed without flux in a vacuum, under protective gas, or even in the atmosphere, using brazing materials in powder, slurry, or tape form, with a liquidus temperature typically above 900°C. The coatings are very dense, wear-resistant, crack-free, and are therefore also highly effective as corrosion protection, even under high-temperature conditions. Unlike with cladding welding, the brazed layers are relatively smooth and often do not require further processing or grinding. In this context, additive brazing is increasingly becoming a key technology for the manufacturing of components with specific, high-loadbearing properties. FROM POWDER TO BRAZED COATINGS The starting point for any coating produced by additive brazing is the powders used. These powders, especially the metallic powders, play a central role in the entire manufacturing process and form the foundation of this advanced technology. They are crucial because they not only influence the physical properties of the coating but also significantly determine the quality and performance of the final product. Therefore, selecting the right powder is of enormous importance. A well-chosen powder contributes significantly to achieving an optimal coating result, as it promotes the desired properties such as adhesion, strength, corrosion resistance, and durability of the coating. On the other hand, poorly chosen powders can impair the coating quality and lead to unwanted effects such as poor material adhesion or inadequate sta- bility. For this reason, selecting the right powder requires careful analysis of material requirements and specific process conditions. When choosing an appropriate powder, a variety of factors play a decisive role. These factors must be carefully considered to ensure the powder is optimally suited for the intended application. Among the most important aspects is powder morphology, which includes various parameters that significantly affect the quality and usability of the powder (Fig. 2). These include: • Shape and Purity: The shape of the powder particles has a significant impact on their behavior during processing. Uniform particle shapes and high purity are important for consistent performance and reliable results. Particles with irregular shapes or impurities could negatively affect the quality of the final product. • Grain Size Distribution: The size of the powder particles and their distribution are crucial for many applications. For example, fine particle size can influence surface reactivity and packing density, while larger particles can lead to lower density. A controlled grain size distribution ensures that the powder performs its intended function under the given conditions. • Tap Density: This refers to the volume the powder occupies after being tapped repeatedly. It is an indicator of the powder’s packability and plays an important role in determining the dosage and volume of the powder in a specific application. Higher tap density indicates better particle compaction, which can affect the handling and transport of the powder. • Flowability: Another essential criteria is the powder’s ability to flow without clogging or aggregation. Good flowability is especially important in automated processes and when dosing the powder, as it enables precise handling and improves efficiency. • Surface Energy: The surface energy of a powder influences its inter- action with other materials, such as in the manufacture of composites or in melt processing. High surface energy can lead to better wetting and adhesion, which is beneficial in many industrial applications. The optimal powder for brazing technology consists of so-called hard materials embedded in a matrix of other materials. The choice of matrix and hard materials plays a decisive role in the per- formance and durability of the deposit. Possible matrix materials that can be used in this context include nickel, iron, cobalt, copper, silver, tungsten carbide, titanium carbide, chromium Fig. 2 — Different powder morphologies.
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