“…The compositions I and II sintered at 1350-1400 °C were formed by spherical grains of ZrO2 with the average size of 200-400 nm and dark Al2O3 -enriched particles of the same sizes (Figure 7). The distinction between dark Al2O3 enriched zones and bright ZrO2 zones linked with the differences between the absorptional and reflectional energies of secondary electrons and it was demonstrated previously [40,41]. The increase of the sintering temperature over 1450 °C lead to the appearance of the large grains of ZrO2 up to 0.7-0.8 μm for the composition I and 0.8-1.5 μm for composition II.…”
Section: The Microstructure Investigationssupporting
Nanocrystalline 3 mol% yttria-tetragonal zirconia polycrystal (3Y-TZP) ceramic powder containing 5 wt.% Al2O3 with 64 m2/g specific area was synthesized through precipitation method. Different amounts of Co (0–3 mol%) were introduced into synthesized powders, and ceramic materials were obtained by heat treatment in the air for 2 h at 1350–1550 °C. The influence of Co addition on the sintering temperature, phase composition, microstructure, mechanical and biomedical properties of the obtained composite materials, and on the resolution of the digital light processing (DLP) printed and sintered ceramic samples was investigated. The addition of a low amount of Co (0.33 mol%) allows us to decrease the sintering temperature, to improve the mechanical properties of ceramics, to preserve the nanoscale size of grains at 1350–1400 °C. The further increase of Co concentration resulted in the formation of both substitutional and interstitial sites in solid solution and appearance of CoAl2O4 confirmed by UV-visible spectroscopy, which stimulates grain growth. Due to the prevention of enlarging grains and to the formation of the dense microstructure in ceramic based on the tetragonal ZrO2 and Al2O3 with 0.33 mol% Co the bending strength of 720 ± 33 MPa was obtained after sintering at 1400 °C. The obtained materials demonstrated the absence of cytotoxicity and good cytocompatibility. The formation of blue CoAl2O4 allows us to improve the resolution of DLP based stereolithographic printed green bodies and sintered samples of the ceramics based on ZrO2-Al2O3. The developed materials and technology could be the basis for 3D manufacturing of bioceramic implants for medicine.
“…The compositions I and II sintered at 1350-1400 °C were formed by spherical grains of ZrO2 with the average size of 200-400 nm and dark Al2O3 -enriched particles of the same sizes (Figure 7). The distinction between dark Al2O3 enriched zones and bright ZrO2 zones linked with the differences between the absorptional and reflectional energies of secondary electrons and it was demonstrated previously [40,41]. The increase of the sintering temperature over 1450 °C lead to the appearance of the large grains of ZrO2 up to 0.7-0.8 μm for the composition I and 0.8-1.5 μm for composition II.…”
Section: The Microstructure Investigationssupporting
Nanocrystalline 3 mol% yttria-tetragonal zirconia polycrystal (3Y-TZP) ceramic powder containing 5 wt.% Al2O3 with 64 m2/g specific area was synthesized through precipitation method. Different amounts of Co (0–3 mol%) were introduced into synthesized powders, and ceramic materials were obtained by heat treatment in the air for 2 h at 1350–1550 °C. The influence of Co addition on the sintering temperature, phase composition, microstructure, mechanical and biomedical properties of the obtained composite materials, and on the resolution of the digital light processing (DLP) printed and sintered ceramic samples was investigated. The addition of a low amount of Co (0.33 mol%) allows us to decrease the sintering temperature, to improve the mechanical properties of ceramics, to preserve the nanoscale size of grains at 1350–1400 °C. The further increase of Co concentration resulted in the formation of both substitutional and interstitial sites in solid solution and appearance of CoAl2O4 confirmed by UV-visible spectroscopy, which stimulates grain growth. Due to the prevention of enlarging grains and to the formation of the dense microstructure in ceramic based on the tetragonal ZrO2 and Al2O3 with 0.33 mol% Co the bending strength of 720 ± 33 MPa was obtained after sintering at 1400 °C. The obtained materials demonstrated the absence of cytotoxicity and good cytocompatibility. The formation of blue CoAl2O4 allows us to improve the resolution of DLP based stereolithographic printed green bodies and sintered samples of the ceramics based on ZrO2-Al2O3. The developed materials and technology could be the basis for 3D manufacturing of bioceramic implants for medicine.
“…6, the SEM micrograph for MgAl 11 CeO 19 phases showed the elongated grains. MgAl 11 CeO 19 phase influences the grain size composition of the microstructures 19 . 5 Microstructures and phase area analysis corresponding to the various additions of MgO nanoparticle on ZTA5CeO 2 , a 0 wt-% b 0.5 wt-% and c 1.5 wt-% with FE-SEM micrograph of a thermal etched surface, together with characteristic EDX analyses 6 The Vickers hardness and fracture toughness of ZTA5CeO 2 as a function of MgO nanoparticle additions…”
Section: Resultsmentioning
confidence: 99%
“…5 c ), the spotted point of elongated grain corresponds to the ternary compound of MgAl 11 CeO 19 for the 1.5 wt-% sample. According to Podzorova et al 19 , with modification of 1 mol-% MgO into ZrO 2 –CeO 2 –Al 2 O 3 composite, MgAl 11 CeO 19 compound is mainly attributed to Mg and Ce redistributed into the elongated grains. These findings are also supported by the XRD quantitative results (Table 3), which clearly detected MgAl 11 CeO 19 phases.…”
The poor hardness of zirconia-toughened alumina (ZTA) with 5 wt-% CeO2 (ZTA5CeO2) ceramic has limited its applications as a cutting insert. Therefore, in this work, the possibility of MgO nanoparticles (20 nm) as reinforcement to ZTA5CeO2 ceramics was investigated. Mgo nanoparticles with different weight percentages (0-2 wt-%) were added to ZTA5CeO2 ceramics. ZTA5CeO2 with 0.5 wt-%MgO showed the highest fracture toughness of 9.14 MPa.√m. The addition of 0.5 wt-%MgO nanoparticles showed the excellent role of MgAl11CeO19 grains as a crack deflector, which consequently produced a reasonable hardness value of 1591 HV and lowered the wear areas to 0.0528 mm2.
“…Using the nanopowder as an initial material results in reducing the dimension parameters of the structure and enhances its homogeneity. Modifying the composition of the nanopowder by small amount (∼1 mol %) of metal ions promotes the outrunning the pore collapse process over the crystal growth during the sintering and thus ensure the decreasing of the grain size (Podzorova et al, ).…”
Section: Introductionmentioning
confidence: 99%
“…Atomic force microscopy (AFM) technique that enables nanoscale mapping (De Oliveira et al, ; Löberg et al, ; Sharma et al, ) have been used to investigate the 3D topographic features in different studies of the ([Ce‐TZP]‐[Al 2 O 3 ]) dental alloys (Podzorova et al, ). Now there is a question about the characterization of the 3D surface morphology of ([Ce‐TZP]‐[Al 2 O 3 ]) dental alloys processed with/without Ca +2 modifier.…”
The objective of this study was to characterize the three-dimensional (3D) surface micromorphology of the ceramics produced from nanoparticles of alumina and tetragonal zirconia (t-ZrO2) with addition of Ca(+2) for sintering improvement. The 3D surface roughness of samples was studied by atomic force microscopy (AFM), fractal analysis of the 3D AFM-images, and statistical analysis of surface roughness parameters. Cube counting method, based on the linear interpolation type, applied for AFM data was used for fractal analysis. The morphology of non-modified ceramic sample was characterized by the rather big (1-2 μm) grains of α-Al2O3 phase with a habit close to hexagonal drowned in solid solution of t-ZrO2 with smooth surface. The pattern surfaces of modified composite content a little amount of elongated prismatic grains with composition close to the phase of СаСеAl3О7 as well as hexahedral α-Al2O3-grains. Fractal dimension, D, as well as height values distribution have been determined for the surfaces of the samples with and without modifying. It can be concluded that the smoothest surface is of the modified samples with Ca(+2) modifier but the most regular one is of the non-modified samples. A connection was observed between the surface morphology and the physical properties as assessed in previous works.
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