A green fabrication strategy for porous Yb 3 Al 5 O 12 ceramics with high strength and tunable gas permeability
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Huimin Xiang Science and Technology of Advanced Functional Composite Laboratory, Aerospace Research Institute of Materials & Processing Technology, Beijing 100076, China
Guigen Wang Shenzhen Key Laboratory for Advanced Materials, Department of Materials Science and Engineering, Harbin Institute of Technology Shenzhen Graduate School, Shenzhen 518055, China
Yanchun Zhoua),b) Science and Technology of Advanced Functional Composite Laboratory, Aerospace Research Institute of Materials & Processing Technology, Beijing 100076, China (Received 24 May 2016; accepted 18 August 2016)
Novel porous Yb3Al5O12 ceramics are successfully fabricated via a green and simple foam-gelcasting approach. Using a nontoxic water-soluble copolymer of isobutylene and maleic anhydride (Isobam), together with a surfactant EMAL TD (Surf-E), 50 vol% solid loading Yb3Al5O12 aqueous ceramic slurries are prepared. Thanks to the small contents of organic additives (0.4 wt% Isobam and 1 vol% Surf-E) added, low linear shrinkage (;13.9%), and mass loss (;2.21 wt%) are obtained after pressureless sintering of gelcasted green body at 1600 °C for 4 h under an air atmosphere. Furthermore, porous Yb3Al5O12 ceramics with controlled porosity and spherical-like cells possess excellent structural and shape stability. The flexural strength and compressive strength of the as-prepared porous Yb3Al5O12 ceramics with a relative density of 20% remain as high as 6.3 and 19.7 MPa, respectively, and the gas permeability can be tuned between 4.3 1013 and 7.8 1011 m2 with exponentially increasing porosity from 58% to 84%. I. INTRODUCTION
Porous ceramics exhibit a unique combination of fascinating properties, including low bulk density, high porosity, and permeability, as well as good thermal stability, which increasingly enable them to have wide applications in the field of light-weight structures, filters, catalyst carriers, adsorption, and thermal insulation, and so on.1–5 In most of these applications, high mechanical properties accompanied with at least one other functional property such as high porosity, high permeability, or low thermal conductivity are much desirable. Contrary to the polymeric and metallic porous architectures, pores have been traditionally avoided in ceramic components because of their native inherent brittleness.6 To achieve the goals of superior performances Contributing Editor: Paolo Colombo a) Address all correspondence to this author. e-mail: [email protected], [email protected] b) This author was an editor of this journal during the review and decision stage. For the JMR policy on review and publication of manuscripts authored by editors, please refer to http://www.mrs. org/jmr-editor-manuscripts/. DOI: 10.1557/jmr.2016.319
and high reliability of porous ceramics, various methods such as replica,7,8 partial sintering,9,10 direct foaming,11–14 and sacrificial templating,15–17 have been developed. However, these methods have several limitations since they are often size-confining or time-consuming, too costly, and not eco-friendly.18 An
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