Contents lists available at ScienceDirect Ceramics International journal homepage: www.elsevier.com/locate/ceramint Processing and properties of cordierite-silica bonded porous SiC ceramics Sanchita Baitalik, Nijhuma Kayal ⁎ CSIR-Central Glass and Ceramic Research Institute, 196, Raja S. C. Mullick Road, Kolkata 700032, India ARTICLE INFO Keywords: Sol-gel processes Cordierite Porosity Corrosion Mechanical properties ABSTRACT Cordierite-silica bonded porous SiC ceramics were fabricated by infiltrating a porous powder compact of SiC with cordierite sol followed by sintering at 1300–1400 °C in air. The porosity, average pore diameter and flexural strength of the ceramics varied 30–36 vol%, ~ 4–22 μm and ~ 13–38 MPa respectively with variation of sintering temperature and SiC particle sizes. In the final ceramics SiC particles were bonded by the oxidation- derived SiO 2 and sol-gel derived cordierite. The corrosion behaviour of sintered SiC ceramics was studied in acidic and alkaline medium. The porous SiC ceramics were observed to exhibit better corrosion resistance in acid solution. 1. Introduction Hot gas filtration from industrial processes offers various advantages in terms of improvement of process efficiencies, heat recovery and protection of plant. The use of porous SiC ceramics to control emissions of particulate matter in incineration, industrial wastes, metal smelting, manufacturing of cement, glass, etc., and hot gas filtration process especially for pressurized fluidized bed combustion (PFBC) and inte- grated gasification combined cycle (IGCC) is increasing to protect the environment [1–6]. For hot gas filtration process, the ceramic filters must be able not only to resist the chemical attack at high temperature (600–900 °C) and high pressure (6–10 atm) by variety of gases such as O 2 , HCl, H 2 S, Cl 2 , SO 2 , NO and H 2 O, but also to withstand the mechanical stress or thermal shock in the pulse cleaning process [7]. SiC is especially recommended as useful material for fabrication of hot gas filters because of their unique combination of properties such as high strength, high hardness, high thermal conductivity, low thermal expan- sion coefficient, superb mechanical and chemical stabilities at high temperatures and hostile atmospheres. The literature survey indicates that processing of suitable SiC material for such application is still challenging. Oxide bonding is widely used technique that has been used for synthesis of porous SiC ceramics at low temperatures (1300– 1550 °C) under an ambient atmosphere using commercial-grade raw powders. This technique is simple and inexpensive as it does not require any sophisticated equipment and delicate instrumentation. Clay, silica and mullite are often used as oxide bonds for SiC [8–12]. Cordierite (2MgO·2Al 2 O 3 ·5SiO 2 ) is also considered another important bond as it has a low thermal expansion coefficient, good thermal and chemical stability and can be processed at a low temperature [13]. The oxide bonding technique was found to have several disadvan- tages as oxidation of SiC is limited in the depth of the zone hence limited for large scale production and mechanical failure of the final ceramics occurred due to inhomogeneous mixing of fine sintering aids. To avoid those problems our group prepared mullite bonded porous SiC ceramics following incorporation of sol-gel bond phase precursor by infiltration technique to ensure a homogeneous distribution of the bond phases [14]. The applicability of ceramic filter as hot gas filter depends on the filtration performance, durability, etc. in actual hot gas filtration condition. Most of the previous studies on off-gas cleaning in advanced power generation process were carried out using commercial SiC ceramic candle filters [4–6,15–17]. Recently many authors re- ported the permeability and collection efficiency behaviour of porous ceramics using the laboratory test setup to filter nano aerosol particles [18–20]. Very few studies are reported in literature on evaluation of filtration performance of the ceramic filter using laboratory made test setup to filter coal fly ash particles in actual power generation conditions [21]. The objective of the present work was to prepare rectangular and disc types SiC ceramic filter by incorporation of cordierite as secondary bond phase following infiltration technique. The effect of starting particle size of SiC and sintering temperatures on the formation of oxide bond phases, porosity, microstructure and mechanical properties were examined. In addition, corrosion resistance properties of final porous SiC ceramics were studied in acid and alkaline salt medium at 90 °C with respect to time. http://dx.doi.org/10.1016/j.ceramint.2017.07.196 Received 21 June 2017; Received in revised form 26 July 2017; Accepted 27 July 2017 ⁎ Corresponding author. E-mail address: nijhuma@cgcri.res.in (N. Kayal). Ceramics International xxx (xxxx) xxx–xxx 0272-8842/ © 2017 Elsevier Ltd and Techna Group S.r.l. All rights reserved. Please cite this article as: Baitalik, S., Ceramics International (2017), http://dx.doi.org/10.1016/j.ceramint.2017.07.196