Solid Oxide Fuel Cells are highly efficient energy converting systems transforming chemical energy directly into electrical energy and heat at elevated temperatures. A fuel cell typically consists of three layers which are cathode, electrolyte and anode. This paper focuses on development of the anode layer, where the oxidation of the fuel gas by reaction with oxygen ions takes place. The composite (cermet) anode, developed by thermal spraying, consisted of nickel and YSZ. The aim of the presented study is to investigate the effect of different plasma spraying technologies on the micro structural characteristics and the electrochemical behaviour of the anode layer.
Coatings were fabricated by spraying Ni-coated graphite or nickel oxide with YSZ using Axial III and Triplex II plasma torch under atmospheric conditions as well as a standard F4-torch under atmospheric or soft vacuum conditions. The investigations were directed in order to have an open micro porous structure, higher electrical conductivity and the catalytic activity of anode deposits. Porosity was investigated by QIA and by measuring the gas permeability. SEM and XRD technologies were applied to examine the morphology, micro structure and composition of the layers. Electrical conductivity measurements were carried out to determine ohmic losses within the anode layer. Most promising layers were analysed by measuring the electrochemical behaviour to obtain information about catalytic activity and performance. The as sprayed coatings showed a broad variety with respect to porosity, electrical conductivity and electrochemical behaviour.