Effect of Sintering Temperature on Compressive Properties of Porous Aluminum Produced by Spark Plasma Sintering

Abstract

Porous aluminum with a porosity of 78% and pore sizes of 850-1000 mm was produced by the spacer method including spark plasma sintering (SPS) at various sintering temperatures of 773-853 K and the dissolution of space-holding sodium chloride particles. The effect of sintering temperature on the compressive properties of porous Al was investigated. The stress-strain curves for the specimens fabricated at 813 K and higher exhibited a plateau region with a nearly constant flow stress to a large strain of about 40%. However, the specimens fabricated at less than 813 K showed no plateau regions, although there were no significant differences in the characteristics of the pores by macroscopic observation between the porous Al specimen fabricated at 843 K and that fabricated at 773 K. Microscopic observation revealed that there were large voids in the cell wall of the specimens fabricated at 773 K, showing that sintering was insufficient and the connection of Al powder was poor. Furthermore, the fully-dense Al specimen fabricated at 793 K exhibited poor ductility in tension. Therefore, poor ductility in tension of cell walls may be responsible for the lack of plateau regions in the specimens fabricated at less than 813 K.

Influence of Porosity and Pore Size on Electrical Resistivity of Porous Aluminum Produced by Spacer Method

“…The sintering temperature, sintering pressure and sintering time were 843 K, 20 MPa and 10 minutes, respectively. 19,20) The sintered compact was then placed in running water to remove NaCl particles. Mass and dimension measurement confirmed that the desired porosities were successfully achieved, leaving no NaCl residues behind in the waterwashed specimens.…”

“…1) In particular, porous metals with high porosity (to 95%) and small pore size (less than 1 mm) have been fabricated by the spacer (or replication) method. [11][12][13][14][15][16][17][18][19][20] Through this method, the pore size and porosity can be uniformly controlled, and formation of structural defects such as missing cell walls, coupled pores and irregularly elongated pores etc. can be successfully suppressed.…”

“…Porous aluminum has been fabricated via the powder-metallurgical spacer method comprising the sintering of mixed (Al/NaCl) powder and dissolution of the NaCl particles in water. 14,[17][18][19][20] The spacer method having good adjustability of porosity and pore size makes it possible to properly evaluate the effect of the porosity and pore size on the electrical properties of porous metals. In the present study, porous Al specimens with pore size range from 212-300 to 850-1000 mm and porosity from 77 to 90% are produced by the spacer method, and their electrical resistivities are experimentally investigated.…”

Effects of Pore Characteristics Finely-Controlled by Spacer Method on Damping Capacity of Porous Aluminum

“…[3][4][5][6][7][8] The spacer method (or replication method), which has been employed since the 1960s, is one of the methods for fabricating porous Al. [14][15][16][17][18][19] Features of the spacer method are: (1) strict control of the porosity and pore size, and (2) distribution of homogeneous pores and small pores. Hence, porous metals fabricated by the spacer method have been used for investigations of the effects of the porosity and pore size on various properties of porous metals.…”

“…[20][21][22] Also, small pore sizes of approximately 100 mm can be attained by the spacer method. [14][15][16][17][18][19] In the present study, porous Al specimens with porosities ranging from 55.7 to 68.2% and pore sizes ranging from 53-106 to 425-500 mm are fabricated by the spacer method, and the damping capacity is examined in order to understand the effect of the porosity and pore size.…”