2相ステンレス鋼微粉のスリップキャスティング

概要

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Stainless steel powders with the composition of 23% Cr-equivalent and 11% Ni-equivalent were produced by the water atomization using the pressure of 82 MPa and the flow rate of 1.9 m3/ks. Under size powders sieved with 25μm screen had the mean particle size of 5/μm and the tap density of 4 Mg/m3. The slip containing 16 mass% water and 0.3 mass% ammonium alginate as the binder had the good flowability. The apparent viscosity showed the minimum value at the range of PH 9-10 and the value decreased with reducing the oxygen content of powders. With the rise of ammonium alginate contents from 0.2 to 0.5%, the strength of green bodys after drying at 420 K in vacuum increased from 3.2 to 5.1 MPa respectively. Sintering was drastically promoted by the presence of 15-40% δ-ferrite in γ matrix-By sintering at 1400 K and above for 7.2ks, green bodys having the density ratio of 49% were densified to 98% and over. Specimens sintered at 1470 K showed the ultimate tensile strength of 660 MPa and the elongation of 40%.