Analysis of the properties of a Cu-Al2-O3 sintered system based on ultra fine and nanocomposite powders

Abstract

In this paper synthesis of a composite based on Cu-Al2O3 by a thermo-chemical method is shown along with a comparative analysis of the properties of the obtained nanocomposite sintered samples, which are characterized by a good combination of electric-mechanical properties, suitable for work at elevated temperatures. Ultra fine and nanocrystal powder Cu-Al2O3 is obtained by a chemical method, starting from water solutions of nitrates up to achieving the requested composition with 3 and 5% of Al2O3. Synthesis of composite powders has been developed through several stages: drying by spraying, oxidation of the obtained powder of precursor and then reduction by hydrogen until the final composition of nanocomposite powder is achieved. After characterization of the obtained powders, which comprised examination by the Scanning Electronic Microscopy (SEM) method and X-ray-structure analysis (RDA), the powders were compacted with compacting pressure of 500 MPa. Sintering of the obtained samples was performed in the hydrogen atmosphere in isothermal conditions at temperatures of 800 and 900oC for 30, 60, 90 and 120 minutes. Characterization of the obtained Cu-Al2O3 of the nanocomposite sintered system comprised examination of microstructure by the Scanning Electronic Microscopy (SEM), as well as examining of electric mechanical properties. The obtained results show a homogenous distribution of dispersoides in the structure, as well as good mechanical and electric properties. .

U radu je prikazana sinteza kompozita na bazi Cu-Al2O3 termohemijskim putem uz uporednu analizu svojstava dobijenih nanokompozitnih sinterovanih uzoraka, koje karakteriše dobra kombinacija električna-mehanička svojstva, pogodnih za rad na povišenim temperaturama. Ultra fini i nanokristalni prah Cu-Al2O3 dobijen je hemijskim putem polazeći od vodenih rastvora nitrata do postizanja zahtevanog sastava sa 3 i 5% Al2O3. Sinteza kompozitnih prahova se odvijala kroz nekoliko faza: sušenje raspršivanjem, oksidacija dobijenog praha prekursora i zatim redukcija vodonikom do postizanje konačnog sastava nanokompozitnog praha.Nakon karakterizacije dobijenih prahova, koja je obuhvatila ispitivanja metodom skanirajuće elektronske mikroskopije (SEM) i rendgenostrukturne analize (RDA), vršeno je presovanje prahova pritiskom presovanja od 500 MPa. Sinterovanje dobijenih uzoraka vršeno je u atmosferi vodonika u izotermskim uslovima na temperaturama 800 i 900o C u toku 30, 60, 90 i 120 minuta. Karakterizacija dobijenog Cu-Al2O3 nanokompozitnog sinterovanog sistema je obuhvatila ispitivanja mikrostrukture skanirajućom elektronskom mikroskopijom, kao i ispitivanja električnih i mehaničkih svojstava. Dobijeni rezultati pokazuju homogenu raspodelu disperzoida u strukturi, kao i dobre mehaničke i električne osobine. .