Strength and Densification of Ni/AI_2O_3 Membrane Compacted with Uniaxial pressing and CIP for Hydrogen Separation: Influence of Pressing Process

摘要

In our previous studies, 10-40wt％Ni/Al_2O_3 membrane was prepared by uniaxial pressing and sintered at 900 to 1400°C for 2 h. It was found that 10wt％Ni/Al_2O_3 membrane sintered at 1400°C showed the highest physical and mechanical properties. Thus, this work we focused on the effect of different pressing processes on the properties of Ni/Al_2O_3 membrane with longer soaking time. Firstly, 10-40wt％Ni and Al_2O_3 powders were mixed by dried ball-milling. Then, the mixture powder was pressed to form a bar shape by two different processes; uniaxially pressing (No CIP) and uniaxially pressing followed by cold isostatic pressing (CIP) at 250 MPa for 5 min. All Ni/Al_2O_3 specimens from two pressing routes were sintered at 1400°C for 4h under air atmosphere and reduced at 900 °C under H_2 (99.99％). From the results, it was found that the densification process affected to physical and mechanical properties of Ni/Al_2O_3. The CIPed - 10wt％Ni/Al_2O_3 membrane sintered at 1400°C for 4 h showed the highest relative density and flexural strength of 76％ and 106 MPa with the lowest pore size (78 nm) and 17％ porosity. The addition of nickel content gradually decreased physical and mechanical properties of Ni/Al_2O_3.