Mechanically Alloyed and Spark Plasma Sintered Aluminium/Precious Metal Oxide Composite Materials

Abstract:

Air-atomised pure aluminium powder with additions of 10 at.% of AgO, PtO2 or PdO was mechanically alloyed (MAed) by using a vibrational ball mill, and MAed powders were consolidated into bulk materials by a spark plasma sintering (SPS) process. Mechano-chemical reactions among pure Al, precious metal oxide and stearic acid, added as a process control agent, during the mechanical alloying (MA) process and subsequent heat treatments were investigated by X-ray diffraction. The mechanical properties of MAed powders obtained under various heat treatment conditions and those of the SPS materials were evaluated by hardness tests. Mechano-chemical reactions occurred in Al/precious metal oxide composite powders during 36 ks of the MA process to form AlAg2, Pt and Al3Pd2 for the Al-AgO, Al-PtO2 and Al-PdO systems, respectively. Further solid-state reactions in MAed powders have been observed after heating at 373 K to 873 K for 7.2 ks. The hardness of MAed powders initially increased significantly after heating at 373 K and then generally decreased with increasing heating temperatures. The full density was obtained for the SPS materials under the conditions of an applied pressure of 49 MPa at 873 K for 3.6 ks. All the SPS materials exhibited hardness values of over 200 HV in the as-fabricated state.

• Periodical: Materials Science Forum (Volumes 638-642)
• Pages: 1824-1829
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.638-642.1824
• Online since: January 2010
• Authors: Masahiro Kubota, Pavel Cizek
• Keywords: AgO, Aluminum (Al), Mechanical Alloying (MA), Mechano-Chemical Reaction, PdO, Precious Metal Oxide, PtO₂, Solid-State Reaction, Spark Plasma Sintering (SPS)

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