Set-up of a screen-printing procedure for the production of a beta-alumina based gas sensor

A gas sensor based on a β-alumina thick film was recently developed on a laboratory scale. This sensor can be successfully used for selective detection of CO and NO x, resulting from an appropriate choice of the working temperature of the sensing element. This paper deals with the approach of the industrial transfer of the sensor prototype, mainly concerning the scale-up of the screen-printing procedure from a hand-operated apparatus to an industrial production machine. Many parameters were already investigated during the laboratory development, namely the ink composition in terms of organic/inorganic component ratio, the type and amount of the liquid dispersant and rheological agent, the composition and softening temperature of the binder, the β-alumina/binder weight ratio. During the industrial transfer, some other parameters must be considered, such as the particle size distribution of the ceramic components of the ink, the influence of the mesh number of the screen fabric on the surface texture of the β-alumina film, the viscosity performances of the ink as a function of the applied shear rate and ageing. A common commercial metallic paste was also used as reference for optimizing the characteristics of the β-alumina based ink.