Solution precursor plasma spray deposition of porous tin oxide coatings for gas sensors

The Solution Precursor Plasma Spray (SPPS), is applied to fabricate nanocrystalline porous SnO2 coatings as a gas sensing layer. The advantages of using SPPS to fabricate porous coatings are two-fold. The SPPS eliminates powder preparation steps, as solution feedstock is used. Another advantage of SPPS is the production of ultra-fine particles with a strong cohesion between them and good adhesion to substrates.; Two designs of experiments identify influential variables on coating porosity and optimize coating sensitivity. This research identifies retained solution precursor, solid particles, hollow spheres and exploded hollow spheres as main constituents. The microstructure of the coating with the highest sensitivity is a combination of agglomerated particles, with micro-pores inside and a void channel network.; This work demonstrates SPPS is capable of producing porous layers which have comparable sensing performance to sensors fabricated by sintering.