Novel fabrication route for porous silicon carbide ceramics through the combination of in situ polymerization and reaction bonding techniques

Abstract

For the first time, an in situ polymerization technique was applied to produce mullite-bonded porous SiC ceramics via a reaction bonding technique. In this study, SiC microsized particles and alumina nanopowders were successfully coated by polyethylene (PE), which was synthesized from the particle surface in a slurry phase reactor with a Ziegler-Natta catalyst system. The thermal studies of the resulting samples were performed with differential scanning calorimetry and thermogravimetric analysis. The morphology analysis obtained by transmission electron microscopy and scanning electron microscopy (SEM) confirmed that PE was successfully grafted onto the particle surface. Furthermore, the obtained porous ceramics were characterized in terms of their morphologies, phase composition, open porosity, pore size distribution, and mechanical strength. SEM observations and mercury porosimtery analysis revealed that the quality of the dispersion of nanosized alumina powder into the microsized SiC particles was strongly enhanced when the particles were coated by polymers with in situ polymerization. This resulted in a higher strength and porosity of the formed ceramic porous materials with respect to the traditional process. In addition, the X-ray diffraction results reveal that the amount of mullite as the binder increased significantly for the samples fabricated by this novel method. The effects of the sintering temperature, forming pressure, and polymer content on the physical and mechanical properties of the final porous ceramic were also evaluated in this study.

Dispersion of SiC powder suspension in mullite sol and influence on properties of sintered ceramics

“…The advantages of inorganic sol as a dispersant are as follows: it can disperse ceramic particles by a combination of electrostatic and steric effect and also provide high bond strength to ceramic bodies due to the formation of its solid gel at low temperature . Recently a new process has developed to fabricate porous SiC ceramics with improved mechanical strength by coating SiC and calcined alumina powders with a polymer (which acts as the pore former) by means of an in situ polymerization technique . Further improvement in mechanical properties with a narrow pore size distribution was obtained by chemical coating of starting SiC powders and sintering additive by alumina sol and polymer via sol‐gel process and in situ polymerization, respectively, followed by reaction bonding technique …”

“…Recently a new process has developed to fabricate porous SiC ceramics with improved mechanical strength by coating SiC and calcined alumina powders with a polymer (which acts as the pore former) by means of an in situ polymerization technique . Further improvement in mechanical properties with a narrow pore size distribution was obtained by chemical coating of starting SiC powders and sintering additive by alumina sol and polymer via sol‐gel process and in situ polymerization, respectively, followed by reaction bonding technique …”

New Approach for Macro Porous RB‐SiC Derived from SiC/Novolac‐type Phenolic Composite

“…Macroporous SiC is fabricated via various approaches including partial sintering, replica, sacrificial fugitives (pore forming agents), direct foaming, and reaction bonding . Among these, reaction‐bonded (RB) technique is most often employed since it allows a relatively low sintering temperature and low cost For examples, macroporous mullite‐bonded SiC has been fabricated via RB sintering (oxidation of SiC and mullitization between oxidation‐derived SiO 2 and additive Al 2 O 3 with using micro‐size graphite particle as pore former) . However, these studies are concerning macroporous RB‐SiC whose pore size is typically below 10 μm; there are few reports on those with pore above 10 μm.…”

Preparation of hybrid composite microspheres containing nanosilicon via microsuspension polymerization

“…Transmission electron microscopy revealed that a carbon layer with a uniform thickness was formed on the surface of the Si nanoparticles with the graphene addition . Recently, several researchers have shown interest in Si hybrid nanocomposites prepared by polymerization because more homogeneously dispersed nanocomposites can be obtained by increasing the interfacial interactions between two components via the formation of hydrogen bonds or covalent bonds . Zhang et al .…”

“…19,20 Recently, several researchers have shown interest in Si hybrid nanocomposites prepared by polymerization because more homogeneously dispersed nanocomposites can be obtained by increasing the interfacial interactions between two components via the formation of hydrogen bonds or covalent bonds. [21][22][23][24] Zhang et al presented an effective approach for the synthesis of a core-shell Si hybrid nanocomposite prepared by emulsion polymerization. 25 They have claimed that the nanocomposite with polyacrylonitrile (PAN) as a shell and Si nanoparticles as the core could be applied successfully to Si-based electrode materials.…”