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

The parameters of water vapor adsorption on the surfaces of powders and com pacted powders (compacts) are compared with data on the variation of the el ectrical resistance of the same compacts in media with various wafer vapor contents. A study of the kinetic features of water vapor adsorption from th e air indicated that powders with small specific surfaces adsorb water vapo r and are saturated more rapidly than do powders with large specific surfac es, while their absolute moisture content is lower. The amount of water vap or adsorbed on the surface varies in the same way. The data are consistent with the results from porous structure studies The rare of wafer vapor adso rption and the amount adsorbed increase for smaller pores, in which the wat er vapor condenses more quickly. Data on the specific surface of compacted and sintered materials, their porous structure and their adsorptivity of wa ter vapor provide a basis for making a prior choice of technological parame ters of the ceramic treatment so as to enhance the qualify of humidity mete rs.