Ceramic humidity sensors based on magnesium aluminate spinel. II. Relation between the parameters of water adsorption kinetics and the service characteristics of ceramic humidity sensors in the MgAl2O4 system

he parameters of water vapor adsorption on the surfaces of powders and compacted powders (compacts) are compared with data on the variation of the electrical resistance of the same compacts in media with various water vapor contents. A study of the kinetic features of water vapor adsorption from the air indicated that powders with small specific surfaces adsorb water vapor and are saturated more rapidly than do powders with large specific surfaces, while their absolute moisture content is lower. The amount of water vapor adsorbed on the surface varies in the same way. The data are consistent with the results from porous structure studies. The rate of water vapor adsorption and the amount adsorbed increase for smaller pores, in which the water vapor condenses more quickly. Data on the specific surface of compacted and sintered materials, their porous structure and their adsorptivity of water vapor provide a basis for making a prior choice of technological parameters of the ceramic treatment so as to enhance the quality of humidity meters.