Densification modeling of isostatically pressed ceramic balls

• Grant number: 15/09150-0
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: July 01, 2015
• End date: June 30, 2016
• Field of knowledge: Engineering - Mechanical Engineering - Manufacturing Processes
• Principal Investigator: Carlos Alberto Fortulan
• Grantee: Mateus Mota Morais
• Host Institution: Escola de Engenharia de São Carlos (EESC). Universidade de São Paulo (USP). São Carlos , SP, Brazil

Abstract

This project studies the densification of isostatically pressed green ceramic balls and the impacts of the non-homogeneity after sintering. Ceramic balls are components used in precision applications such as bearing elements and hyperspheres of hip implant. The process of isostatic pressing, followed by green machining, is the most used to obtain balls. Though it is recognized to be the process with better performance in the densification homogeneity, the effects of interparticle friction and the mold rigidity in the low-pressure stages may result in non-compliances that may start a failure process by the spread of a crack growing. This project aims to study the balls compression through finite elements modeling confronted with the physical pressed samples. Partially stabilized zirconia powders with 3mol% of Ytria will be additivated and granulated for isostatic conformation of 30mm diameter balls. The pressed balls will be pre-sintered, sliced and will have their density measured by Archimedes' principle. Finite elements modeling with the software ABAQUS and ANSYS will be tested and confronted with the experimental tests. It will also verify the contribution of this study in the mold design for isostatic pressed balls. It is expected that the modeling will predict the non-homogeny compression that, after sintering, might be the cause of stress concentration and product failure in service.