Novel Mullite Synthesis Based on Alumina Nanoparticles and a Preceramic Polymer

Abstract

Heating in air of a selected mixture of a silicone resin and alumina nanoparticles in the temperature range 1200°–1500°C yielded dense, crack‐free mullite samples. Al2O3, due to its nanometric size, proved to be very reactive toward silica, deriving from the ceramization of the preceramic polymer, leading to the formation of a large volume fraction of mullite crystals even at low firing temperatures (1250°C). Because of the homogeneity of the distribution of alumina nanoparticles in the starting system, the ceramized samples exhibited a very fine microstructure consisting of crystals with an average dimension in the range of 50–300 nm.

Development of multiphase bioceramics from a filler-containing preceramic polymer

“…Rankinite, as di-and tri-calcium silicates, is a silicate with a higher content of CaO than expected (C x ÁS y , with x > y); however, the degree of overconcentration of calcium oxide is clearly lower (rankinite corresponds to the formula C 3 ÁS 2 ). As previously reported for silicone resins containing g-Al 2 O 3 nano-powders [11,12], the use of nano-sized fillers in preceramic polymers is effective in providing a quasi-molecular mixing. An example of the XRD refinements applied to the analysis of the diffraction data for the sample from the system with Ca-acetate and surfactant (pyrolized at 1200 8C), useful for phase quantification, is given in Fig.…”

“…However, some www.elsevier.com/locate/ceramint papers have very recently highlighted the potentialities of using such oxide fillers in combination with polymethylsiloxanes. In particular, the use of highly reactive nano-sized fillers, such as gAl 2 O 3 nano-particles, allowed to produce a large amount of mullite at low temperature (by reaction in oxidative atmosphere) [11,12] and SiAlON ceramics (in nitrogen atmosphere) [13]. These papers are based on a new concept of ''active filling'', consisting in the reaction of the whole ceramic residue deriving from the pyrolysis (in air or in nitrogen) of the polysiloxanes with the fillers.…”

3D printed porous β-Ca2SiO4scaffolds derived from preceramic resin and their physicochemical and biological properties

“…Thus, a common strategy is that oxide fillers react with the decomposition products of preceramic polymers to produce the desired ceramics. For example, Bernardo et al prepared mullite (3Al 2 O 3 ·2SiO 2 ) and forsterite (2MgO∙SiO 2 ) by using a silicone resin loaded with γ-Al 2 O 3 and MgO nanoparticles, respectively [5–7]. In addition, ternary systems such as akermanite (2CaO·MgO·2SiO 2 ) [8], hardystonite (2CaO·ZnO·2SiO 2 ) [9], gehlenite (2CaO∙Al 2 O 3 ∙SiO 2 ) [10], and cordierite (2MgO∙2Al 2 O 3 ∙5SiO 2 ) [11] were also derived from silicone resin loaded with two active fillers.…”

Wollastonite Foams From an Extruded Preceramic Polymer Mixed with CaCO3 Microparticles Assisted by Supercritical Carbon Dioxide

“…[1][2][3][4][5] Unlike most investigations concerning ''active'' fillers, these oxide particles are not intended to react with the gaseous by-products of the conversion of the silicones into ceramics or with the atmosphere of the furnace in which the conversion is conducted, [6] but rather with the main ceramic residue. Such residue, for thermal treatments in oxidative atmosphere, consists of practically pure silica, and possesses a very remarkable reactivity especially when combined with oxide fillers in the form of nanosized particles.…”

“…Such residue, for thermal treatments in oxidative atmosphere, consists of practically pure silica, and possesses a very remarkable reactivity especially when combined with oxide fillers in the form of nanosized particles. To cite the most important examples, it has been shown, on one hand, that g-Al 2 O 3 nanoparticles combined with a commercial silicone (MK silicone resin from Wacker Gmbh, Germany) [1,2] yielded almost pure mullite, i.e. Al-silicate (3Al 2 O 3 Á2SiO 2 ), with very favorable kinetic features (about 80 vol% mullite after only 100 s at 1350 8C and activation energy for nucleation below 700 kJ mol À1 ); [2] on the other hand, CaCO 3 nanoparticles, combined with the same commercial silicone, led to wollastonite, i.e.…”