Preceramic polymers, i.e., polymers that are converted into ceramics upon heat treatment, have been successfully used for almost 40 years to give advanced ceramics, especially belonging to the ternary SiCO and SiCN systems or to the quaternary SiBCN system. One of their main advantages is the possibility of combining the shaping and synthesis of ceramics: components can be shaped at the precursor stage by conventional plastic-forming techniques, such as spinning, blowing, injection molding, warm pressing and resin transfer molding, and then converted into ceramics by treatments typically above 800 °C. The extension of the approach to a wider range of ceramic compositions and applications, both structural and thermo-structural (refractory components, thermal barrier coatings) or functional (bioactive ceramics, luminescent materials), mainly relies on modifications of the polymers at the nano-scale, i.e., on the introduction of nano-sized fillers and/or chemical additives, leading to nano-structured ceramic components upon thermal conversion. Fillers and additives may react with the main ceramic residue of the polymer, leading to ceramics of significant engineering interest (such as silicates and SiAlONs), or cause the formation of secondary phases, significantly affecting the functionalities of the polymer-derived matrix.

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The use of preceramic polymers in the synthesis of Sialon ceramics has been scarcely discussed in the literature. In this article we report the production of virtually phase-pure β′-Sialon ceramics from a mixture of commercially available polysilazanes and γ-Al2O3 nanopowder, pyrolized in N2 atmosphere in the 1300°C–1600°C range. This approach combines the advantage of embedding nano-sized fillers in preceramic polymers, in terms of their reactivity towards the Si–N based ceramic pyrolysis residue, with the complex interactions with residual carbon, also present as a secondary phase in the same ceramic residue. Starting from a polymer (PSZ20) yielding a SiCN amorphous ceramic after pyrolysis, the Sialon phase purity is greatly affected by the residual C content: for an optimized polymer/filler ratio (PSZ20/Al2O3 = 2), β′-Sialon can be produced possesing only small quantities of quasi-amorphous SiC as a secondary phase. Additional improvements based on the partial replacement of PSZ20 with a polymer (PHPS) not containing C in the backbone, lead to the production of pure nanocrystalline β′-Sialon powders (average grain size of 100–200 nm)

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Wollastonite (CaSiO3) bioceramics have recently received great attention as hard tissue repairing material. In this paper we discuss a novel processing for open cell foams based on the mixing of a silicone resin with CaCO3 micron‐sized fillers, by means of conventional polymer extrusion assisted by supercritical carbon dioxide. The novel mixing was so effective that the wollastonite yield was comparable to that achieved employing much more reactive nanosized fillers, and led to silicone/CaCO3 extruded parts, embedding CO2. These parts can be easily converted into highly porous foams (porosity of about 80%) by a secondary low temperature treatment, before final ceramization at 900 °C. Depending on the conditions of secondary treatment, it was possible to obtain foams with similar density but different pore architecture, and consequently different strength, ranging from 0.45 to 6 MPa.

Many silicates and alumino-silicates feature remarkable mechanical properties at high temperatures, low thermal expansion and high thermal shock resistance, optimum dielectric properties, etc. The poor interdiffusion, due to their characteristic partially covalent bonding however, greatly complicates the obtainment of dense and/or phase pure articles, by conventional sintering. The present paper concerns the realization of high-purity cordierite (2MgO∙2Al2O3∙5SiO2) components by direct thermal treatment in air of preceramic polymers embedding suitable nano-sized oxide particles. More precisely, a selection of silicone resins allowed the obtainment of both dense and highly porous bodies

Vertically aligned carbon nanotube (CNT) forests are a particularly interesting class of nanomaterials, because they combine multifunctional properties, such as high energy absorption, compressive strength, recoverability, and super-hydrophobicity with light weight. These characteristics make them suitable for application as coating, protective layers, and antifouling substrates for metallic pipelines and blades. Direct growth of CNT forests on metals offers the possibility of transferring the tunable CNT functionalities directly onto the desired substrates. Here, we focus on characterizing the structure and mechanical properties, as well as wettability and adhesion, of CNT forests grown on different types of stainless steel. We investigate the correlations between composition and morphology of the steel substrates with the micro-structure of the CNTs and reveal how the latter ultimately controls the mechanical and wetting properties of the CNT forest. Additionally, we study the influence of substrate morphology on the adhesion of CNTs to their substrate. We highlight that the same structure-property relationships govern the mechanical performance of CNT forests grown on steels and on Si.