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Fabrication and Compressive Properties of Open-Cell Ni-Mo-Cr (Hastelloy) Foams Manufactured by Electrostatic Powder Spraying

Kang Tae-Hoon, Kim Kyu-Sik, Lee Min-Jeong, Yun Jung-Yeul, Lee Kee-Ahn

Archives of Metallurgy and Materials

2020

Vol. 65, iss. 3

1081--1086

An open-cell Ni-Mo-Cr foam was newly manufactured using electrostatic powder spraying process and its room-temperature compressive properties were investigated in this study. For manufacturing Ni-Mo-Cr foam, Ni-Mo-Cr powders were sprayed on the polyurethane pre-form by electrostatic powder spraying process. And then, Ni-Mo-Cr powder sprayed pre-forms were sintered at 1200°C, 1250°C, and 1300°C, respectively. The relative densities of Ni-Mo-Cr foams were measured at 4 ~ 5%. Room tempera-ture compressive curves of ESP Ni-Mo-Cr foams represented the typical compressive 3-stages (elastic, plateau, densification) of open-cell metallic foam. As a result of observation of deformed specimen, the fracture mode found to be changed from brittle to ductile as sintering temperature increased. Based on these findings, correlations between structural characteristics, microstructure, and compressive deformation behavior were also discussed.

High Temperature Random Stack Creep Property of Ni-Cr-Al based Powder Porous Metal Manufactured with Powder Sintering Process

Kang Tae-Hoon, Kim Kyu-Sik, Park Man-Ho, Lee Kee-Ahn

Archives of Metallurgy and Materials

2019

Vol. 64, iss. 2

513--518

Recently, attempts have been made to use porous metal as catalysts in a reactor for the hydrogen manufacturing process using steam methane reforming (SMR). This study manufactured Ni-Cr-Al based powder porous metal, stacked cubic form porous blocks, and investigated high temperature random stack creep property. To establish an environment similar to the actual situation, a random stack jig with a 1-inch diameter and height of 75 mm was used. The porous metal used for this study had an average pore size of ~1161 μm by rolling direction. The relative density of the powder porous metal was measured as 6.72%. A compression test performed at 1073K identified that the powder porous metal had high temperature (800°C) compressive strength of 0.76 MPa. A 800°C random stack creep test at 0.38 MPa measured a steady-state creep rate of 8.58×10-10 s-1, confirming outstanding high temperature creep properties. Compared to a single cubic powder porous metal with an identical stress ratio, this is a 1,000-times lower (better) steady-state creep rate. Based on the findings above, the reason of difference in creep properties between a single creep test and random stack creep test was discussed.