Analysis of pore morphology in oxide electroceramics by automatic image analysis

Abstract

Abstract Porosity represents one of the key parameters in the characterization of ceramic materials. Pores remaining after sintering often constitute the origin of direct mechanical or dielectric material failure. Isolated and large-scale pores in the microstructure are particularly problematic; many times these are larger than the average pore diameter. Their detection poses a particular challenge for analytics. The analytical methods used for ceramic materials either detects only part of the porosity or are greatly limited in view of area measurements. Moreover, the analysis of the morphology of detected pores is hardly possible or even impossible for the majority of methods. This research paper offers a detailed account of the qualitative analysis of porosity in oxide ceramics, with the primary focus being on possibilities for pore detection, the measured distribution functions, and the advantages of this method. This paper will show that the use of digital light microscopy together with coaxial illumination is capable of determining pore morphology and distribution in a fraction of time that would be required by conventional methods. The comparison of the measurement results, aided by well established methods for pore characterization, such as the linear intercept method (according to DIN EN ISO 13383), will enable a reliable validation of the results. Final FESEM analysis was used to enable a detailed study of the identified pores and to verify the results.