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Influence of pore formers on electrical properties of Perovskite-type ceramics

Lendze T., Mielewczyk-Gryń A., Gdula-Kasica K., Kusz B., Gazda M.

Advances in Materials Science

2011

Vol. 11, nr 1(27)

55-63

Porous CaTi0.9Fe0.1O3-delta (CTF) perovskites were synthesized by the standard solid state method at different sintering temperatures with carbon black (CB), corn starch (CS) and potato starch (PS) as pore-forming agents. The ceramic samples of porosity between 9% and 42% with 5 - 40 mikrom pore sizes, were obtained by a 6 h sintering at either 1130o C or 1200o C of precursor powder prepared at 1470o C. X-ray diffraction analysis proved the existence of orthorhombic single-phase perovskites crystalline structure. Electrical conductivity at 800�‹ C was between 1.42 �~10.2 S cm.1 and 1.86�~10.3 Scm.1 . The conductivity markedly depended on the sample porosity. It should be noted that 30% of porosity, resulted in reduction of conductivity by less than one order of magnitude. Activation energy of conductivity varied between 0.41 and 0.56 eV. Cornstarch has been chosen as the most suitable pore-forming agent for obtaining the cathode of good properties. The best amount of the cornstarch has been proposed as between 5 and 10%.

Low velocity impact damage in glass / polyester composite sandwich panels

Lendze T., Wojtyra R., Guillaumat L., Biateau C., Imielińska K.

Advances in Materials Science

2006

Vol. 6, nr 1

26-34

Impact resistance of glass/polyester facesheets/PVC foam core sandwich structures was primarily assessed in terms of skin-/core bonding efficiency using two types of adhesives and bonding with uncured resin. Also, the air-coupled ultrasonic C-scan technique was estimated as a means of characterizing impact damage size in sandwich structures. The following observations were made. The impact damage size estimated by visual inspection was much more extensive in all samples, which is due to the C-scan images showing only the overlapping delaminations area directly under the impact site, whereas the visual inspection of the laminate surface and macroscopic observations of the sample section show the extent of the largest, single delamination. The least extensive damage size was found in the two-phase high-density adhesive samples showing also the highest tendency for core cracking. In contrast, the “pinkglue” adhesive, which is low-density due to the presence of the microspheres provides greater local flexibility which prevented core craking.