title: A general process for in situ formation of functional surface layers on ceramics.
abstract: Ceramics are often prepared with surface layers of different composition from the bulk, in order to impart a specific functionality to the surface or to act as a protective layer for the bulk material. Here we describe a general process by which functional surface layers with a nanometre-scale compositional gradient can be readily formed during the production of bulk ceramic components. The basis of our approach is to incorporate selected low-molecular-mass additives into either the precursor polymer from which the ceramic forms, or the binder polymer used to prepare bulk components from ceramic powders. Thermal treatment of the resulting bodies leads to controlled phase separation ('bleed out') of the additives, analogous to the normally undesirable outward loss of low-molecular-mass components from some plastics; subsequent calcination stabilizes the compositionally changed surface region, generating a functional surface layer. This approach is applicable to a wide range of materials and morphologies, and should find use in catalysts, composites and environmental barrier coatings.
authors.affiliation: Ube Research Laboratory, Corporate Research & Development, Ube Industries Ltd., Ube City, Japan. 24613u@ube-ind.co.jp
authors.forename: Toshihiro
authors.initials: T
authors.lastname: Ishikawa
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Yamaoka
authors.forename: Yoshikatsu
authors.initials: Y
authors.lastname: Harada
authors.forename: Teruaki
authors.initials: T
authors.lastname: Fujii
authors.forename: Toshio
authors.initials: T
authors.lastname: Nagasawa