Hot pressing of nanocrystalline TiO2 (anatase) ceramics with controlled microstructure

Abstract

International audienceThe preparation conditions of nanocrystalline phase-pure TiO2 anatase ceramics by hot pressing are described. Density, surface area, pore size distribution and grain size are determined by various techniques, including gas adsorption, mercury porosimetry, transmission electron microscopy (TEM) and X-ray diffraction (XRD). The evolution of the structural parameters is followed as function of temperature and pressure programme. It is shown that the porosity, grain and pore size of the ceramics can be controlled by a suitable choice of experimental conditions. Ceramics with densities higher than 90% of the theoretical limit with a mean grain size of 30 nm can be obtained at temperatures as low as 490 ◦C under 0.45 GPa for 2 h. The experimental results are discussed in view of the sintering theory

Low temperature proton conduction in bulk nanometric TiO2 prepared by high-pressure field assisted sintering

“…17 On the basis of the results described above, the possibility to investigate proton conduction in polycrystalline dense samples with grains in the low nanometric range appears to be particularly intriguing. Several studies have been devoted to the preparation of polycrystalline bulk anatase samples with grain size in the nanometric range using several different nonconventional sintering approaches, including spark plasma sintering [18][19][20][21] , hot pressing, 22 and two-stage sintering. 23 Spark plasma sintering proved to be particularly successful, although samples prepared at relatively low pressures (7)(8)(9)(10)(11)(12)(13)(14)(15)19 62 MPa, 18 and 40 MPa 21 ) required fairly high sintering temperatures (800-1000°C).…”

Effect of a novel sintering process on mechanical properties of hydroxyapatite ceramics

“…The fact is that the grain growth and densification are both driven by diffusive mechanisms which result to the simultaneous activation of densification and grain growth in the later stage of sintering [11]. Spark plasma sintering (SPS) [14,15] and hot pressing [16] are also, two promising techniques for production of nanostructured ceramics. Guo et al [15], have, for instance, spark plasma sintered synthesized HA nanopowders at a low temperature (825 • C) and short time (3 min), while the final grain size became <130 ± 44 nm.…”

Densification and grain growth of nanocrystalline 3Y-TZP during two-step sintering

“…5 Spark plasma sintering (SPS) and hot pressing are two key techniques to produce nanostructured ceramics. 6,7 These methods yield a rapid sintering rate, high density and ultrafine grain structure. However, limitations such as production cost, shapecomplexity, and product size might exist dependent on the particular material and application.…”