Nanosecond pulsed laser surface modification of yttria doped zirconia for Solid Oxide Fuel Cell applications: Damage and microstructural changes

An effective strategy to reduce the cathode polarization in a Solid Oxide Fuel Cell (SOFC) is to enlarge the cathode-electrolyte interface, corrugating the electrolyte surface of zirconia doped with 8 mol% of yttria (8YSZ) by pulsed-laser machining. However, laser-material interaction using a nanosecond pulsed laser can involve thermal effects on the surface. The objective of this work was to analyse the microstructural and phase changes, and the collateral damage caused by laser machining on the 8YSZ electrolyte surface of the SOFCs, and compare it with the 3% molar in yttria (3Y-TZP). Several patterns consisting in parallel tracks below 10 μm depth were investigated. The results evidenced a heat affected zone (HAZ) limited to ⁓1-2 μm with microcracking and directional recrystallization, which was larger in 8YSZ than in 3Y-TZP. However, the mechanical response near the HAZ and chemical composition at the machined surface was not significantly changed.