MERCURY INTRUSION POROSIMETRY OF PLASMA-SPRAYED CERAMIC

Limitations and corrections for the application of mercury intrusion p orosimetry (MIP) in measuring plasma-sprayed ceramic (alumina-titania) deposits are studied. The data reduction procedures of the MIP techni que are discussed; the importance of which changes between different m achines and samples. Thus, it is proposed that each published result s hould be accompanied by the specific data reduction procedures and ass umptions used so that data may be compared. Preparation of plasma-spra yed ceramic samples has a significant influence on the MIP result. Sam ple fragmentation into irregular pieces (below about 1.2 mm effective diameter) prior to the MIP measurement resulted in an increase of surf ace effects such that the surface roughness dominated the MIP data and the measured porosity volume increased. Variation in sample thickness between 0.8 and 4.7 mm did not change the measured porosity. Orientat ion (parallel or perpendicular to the substrate) of the flat surface d id not have a measurable effect on the MIP results.