Příprava a vlastnosti nanokrystalického teragonálního oxidu zirkoničitého

Processing and properties of nanocrystalline tetragonal zirconia

článek v časopise - ostatní, Jost

en

Zirconia nanopowders (stabilized by 1.5 and 3 mol% Y2O3) with particle size below 10 nm were compacted by cold isostatic pressing. Pressureless sintering and hot isostatic pressing were applied to obtain dense nanocrystalline ceramics. The influence of the pore size in powder compacts on sintering behaviour was investigated. Green bodies pressed at 1000 MPa had a maximum pore size of 5 nm. These bodies were densified to a relative density of over 99.6% with an average grain size about 85 nm by pressureless sintering at 1100 degC. Indentation techniques were used to evaluate the hardness and fracture toughness of zirconia nanoceramics. The decrease in the yttria content from 3 to 1.5 mol% resulted in the toughness increasing from 5.3 to 11.1 MPa m^0.5. The differences in fracture toughness of zirconia ceramics prepared with different yttria contents and by different sintering methods were discussed and their possible causes were proposed.

ZrO2 nanoprášeky (stabilizované 1,5 a 3% Y2O3) s částicemi pod 10 nm byly zhutněny pomocí isostatického lisování za studena. Pro získání hutné nanokrystalické keramiky bylo použito beztlaké slinování a isostatické lisování za tepla. Byl zkoumán vliv velikosti pórů v práškových výliscích na slinovací chování. Polotovary lisované při 1000 MPa měly maximální velikost pórů 5 nm. Tato tělesa byla zhutněna do relativní hustoty 99,6% s průměrnou velikostí zrn 85 nm beztlakém slinování při 1000 degC. Pro hodnocení tvrdosti a lomové houževnatosti ZrO2 nanokeramiky byly použity indentační metody. Snížení obsahu Y2O3 z 3 na 1,5 mol% vedlo ke zvýšení houževnatosti z 5,3 na 11,1 MPa m^0,5. Byly diskutovány rozdíly v lomové houževnatosti ZrO2 keramiky připravené s různým obsahem Z2O3 a různými slinovacími metodami. Byla navrženy možné příčiny těchto rozdílů.

Zirconia nanopowders (stabilized by 1.5 and 3 mol% Y2O3) with particle size below 10 nm were compacted by cold isostatic pressing. Pressureless sintering and hot isostatic pressing were applied to obtain dense nanocrystalline ceramics. The influence of the pore size in powder compacts on sintering behaviour was investigated. Green bodies pressed at 1000 MPa had a maximum pore size of 5 nm. These bodies were densified to a relative density of over 99.6% with an average grain size about 85 nm by pressureless sintering at 1100 degC. Indentation techniques were used to evaluate the hardness and fracture toughness of zirconia nanoceramics. The decrease in the yttria content from 3 to 1.5 mol% resulted in the toughness increasing from 5.3 to 11.1 MPa m^0.5. The differences in fracture toughness of zirconia ceramics prepared with different yttria contents and by different sintering methods were discussed and their possible causes were proposed.

zirconia, nanopowder, pore size, sintering, indentation, fracture toughness

2007

01.01.2007

Trans Tech Publications

Curich, Švýcarsko

1013-9826

Key Engineering Materials

336-338

4

2300–2303

4