Agglomeration behavior of nickel particles on yttria stabilized zirconia (YSZ). NiO doped YSZ and TiO2 doped YSZ substrates was examined by scanning electron microscopy (SEM) as two dimensional (2D) analysis and scanning probe microscopy (SPM) as three-dimensional (3D) analysis. For 2D analysis, binarized SEM image was analyzed to examine the agglomeration factor. In 3D analysis, wettability analyzing method was adopted for solid particle on solid substrate, and "apparent" contact angle was evaluated by the following equation; theta = 2 tan(-1) (2 h/d) where d and h are the observed particle diameter and the observed particle height of each agglomerated particle obtained by SPM analysis. Results from both analysis techniques revealed that NiO doped YSZ tend to enhance the nickel agglomeration, whereas TiO2 doped YSZ shows better wettability especially for larger nickel particles. (C) 2012 Elsevier B.V. All rights reserved.