What is the primary purpose of nitrogen atmosphere in SLS printing?

The primary purpose of using a nitrogen atmosphere in SLS (Selective Laser Sintering) printing is to prevent oxidation of the powder material at the elevated temperatures required for sintering. Many materials used in SLS, especially metals and certain polymers, are highly reactive with oxygen at high temperatures. Oxidation can lead to several problems, including degradation of the material's mechanical properties, changes in its chemical composition, and the formation of unwanted surface oxides that can interfere with the sintering process. By creating an inert atmosphere of nitrogen, the amount of oxygen available to react with the powder is drastically reduced, minimizing oxidation and preserving the material's integrity. The nitrogen atmosphere also helps to remove volatile contaminants from the powder bed, further improving the quality of the sintered parts. Without a nitrogen atmosphere, many materials would be unsuitable for SLS printing due to excessive oxidation.