In this paper, a quantitative model for determining the viscous behavior of two-phase particles when they hit the substrate is derived and used for the production of silicon-nitride composite layers. Plasma spray deposition is carried out using a Sulzer-Metco unit and powder feed system in which the powder is injected into the jet external to the nozzle. Silicon nitride-YAS layers with low melting points are developed so that the YAS matrix successfully protects the silicon nitride from decay. The model is developed from the observed layer behavior and provides a basis for the further development of ceramic-matrix composite layers. Paper includes a German-language abstract.