Servizio Comunitario di Informazione in materia di Ricerca e Sviluppo - CORDIS

A processing route for graded Al2O3-ZrO2 discs by means of electrophoretic deposition (EPD)

K.U.Leuven developed a procedure for the colloidal processing of free standing Al2O3-ZrO2 cylindrical discs with a gradient composition by means of electrophoretic deposition (EPD). The capability to produce thick Al2O3-ZrO2 FGM discs was explored. The EPD processing parameters and subsequent sintering schedules were optimised. In order to deposit thick Al2O3-ZrO2 plates, it was necessary to develop a suitable organic suspension with adequate stability. A mathematical model was established for the EPD process, allowing to calculate the composition gradient in plate-shaped FGM materials from the starting composition of the suspensions, the EPD operating parameters and the powder specific EPD characteristics. The model was essential to calculate the experimental parameters to engineer the symmetric gradient profiles in the green deposits. Defect-free Al2O3/ZrO2 FGM discs with a diameter up to 55 mm and a thickness of more than 5 mm were successfully produced.A procedure was described for the manufacturing of Al2O3/ZrO2 composite plates with an outer layer of pure Al2O3, a central homogeneous Al2O3/ZrO2 composite layer and intermediate continuously graded layers by means of EPD from a suspension of acetone and butylamine and subsequent sintering in air. The experimentally obtained gradients were found to be in excellent agreement with the composition profile, calculated according to a developed EPD-model, based on the EPD parameters and the EPD characteristics of the powders. By careful engineering of the thickness of the homogeneous regions and the slope of the profiles in the graded layers in the FGM disc, it is possible to generate and modify the compressive stress in the outer pure alumina layer of the Al2O3/ZrO2 FGM discs.

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K.U.Leuven - Department of Metallurgy and Materials Engineering
Kasteelpark Arenberg 44
3001 Leuven
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