Production of the al based foam by hot pressing method


Thesis Type: Postgraduate

Institution Of The Thesis: Gazi Üniversitesi, Fen Bilimleri Enstitüsü, Turkey

Approval Date: 2012

Student: HALİL KARAKOÇ

Supervisor: RAMAZAN ÇITAK

Abstract:

Aluminum based foam was produced by applying of hot pressing process with powder metallurgy method. Effects of pressure and temperature of pressing were determined in production of aluminum-based metallic foam. In addition, the effects of foaming temperature was investigated. 1% (by weight) TiH2 was added to Alumix 231 powders and these mixed powders were blended in an atritor for 60 min. By using one directional press, these blended powders were pressed after the pre-load (50 MPa) at the different temperatures (350-450-550 0C) and under the different pressures (100-200-300 MPa) for 30 min. In this way, the compact samples for foaming process have been obtained. The compact samples in the high-temperature resistant transparent glass mold was put into the furnace at the different foaming temperatures (670-690-710 oC) for the foaming process for 7 min. The foamed tablet samples in the high-temperature resistant transparent glass mold were observed until reaches the highest rate of expansion and removed from the furnace. The optimum pressing temperature, pressing pressure and the foaming temperature for metallic foams were determined. As results of experimental studies, the densities of foamable P/M samples were increased depend on pressing pressure and pressing temperature. The maximum density (99.54 %) was reached in the pressing process at 550 oC. The lowest linear expansion ratio was obtained with foaming at 670 ºC of pressed samples under 100 MPa, at 350 oC. The highest rates of linear expansion were obtained with foaming at 690-710 oC foaming temperatures of pressed samples under 200 MPa, at 450 oC.