Processing of Open Cell Nickel-Chromium and P/M Nickel-baseSuperalloy Foams

摘要

Two different methods for processing highly porous open cell metal foam preforms for thernuse in metal-ceramic composite materials were investigated. For fabrication, a method wasrnselected, in which polyurethane foam acts as a template, which is then removed after coatingrnwith a metal slip. Three different metal powders were used, a Ni-20Cr alloy and two nickelbasernsuperalloys (Nimonic 90, Saratherm 2). After processing, the preform was dried andrnheat treated to remove the polymer. After sintering a stable metal foam sample is obtained.rnDifferent atmospheres and heating cycles for debindering and sintering are investigated tornget a complete carbon removal so that carbide formation during sintering is prevented. Ni-rn20Cr samples showed no oxidation and a good sinterability, whereas the nickel-basernsuperalloys exhibit surface oxidation and low sintering activity. Sintering behaviour wasrninvestigated regarding the porosity change, microstructure development and phaserncomposition with density measurement, light and scanning electron microscopy, X-rayrndiffraction, and energy dispersive X-ray analysis, respectively.