CeraMat

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.

Sol-gel processed NASICON-type with new compositions in the Na3Zr2-(x/4)Si2-xP1+xO12 system showed an improved sinterability with an increase in the x value. This is attributed to liquid phase sintering. This dense electrolyte system is suitable for the application as gas sensors. The CO2 gas sensors using highly dense x = 0.667 (sample B) and x = 1.333 (sample C) samples show a stable EMF response in dry atmosphere which is very close to the theoretical value.

High-conductivity and high-density samples with new compositions in the NASICON-type electrolyte series, i.e., the Na3Zr2-(x/4)Si2-xP1+xO12 system, with x = 0(A), 0.667(B), and 1.333(C) were synthesized using a mixed inorganic-organic sol-gel process. The sinterability was improved with increasing the x value, but the conductivity decreased. Highly dense samples were obtained by sintering at 1100 °C. The conductivity decreased with decreasing the c lattice parameter of the hexagonal structure.

The sinterability of two different ceramic wastes coming from the hydrometallurgy processing of zinc ores was investigated in view of their low-cost reuse as porous building materials for heat and sound insulation. Their chemical composition, the phase and mass changes during heat treatment were firstly investigated for setting up the thermal cycle for their densification. The materials demonstrated to sinter to high final density without any sintering aid at temperatures close to 1300 °C.

Sol-gel processed NASICON-type with new compositions in the Na3Zr2-(x/4)Si2-xP1+xO12 system showed an improved sinterability with an increase in the x value. This is attributed to liquid phase sintering. This dense electrolyte system is suitable for the application as gas sensors. The CO2 gas sensors using highly dense x = 0.667 (sample B) and x = 1.333 (sample C) samples show a stable EMF response in dry atmosphere which is very close to the theoretical value.

A β-alumina-based gas sensor for automotive exhaust application (hydrocarbon, CO, NO2 detection in 10-1000 ppm concentration range) has been developed by thick film technology (screen-printing) in the frame of a European project. The sensing device consists of a solid electrolyte (β alumina) and of two metallic electrodes having different catalytic properties, the whole system being in contact with the surrounding atmosphere to be analyzed.

As a part of our research on new gas sensors, an original potentiometric gas sensor was developed. The gas sensor consists of a solid electrolyte associated with two different electrodes located in the same gas mixture. Owing to the interesting behavior of this sensor to the action of CO and NOx, it was decided to develop this device within the framework of a European contract and to produce it industrially by screen-printing. The sensor is designed for use in automotive applications. We propose to expose the problems encountered during the development phase as well as the chosen solutions.