Significance of hot pressing parameters and reinforcement size on sinterability and mechanical properties of ZrB2–25vol% SiC UHTCs

• Published in: Ceramics international 2015-09, Vol.41 (8), p.9628-9636
• Main Authors: Jaberi Zamharir, Mehran, Shahedi Asl, Mehdi, Ghassemi Kakroudi, Mahdi, Pourmohammadie Vafa, Nasser, Jaberi Zamharir, Mahsa
• Format: Article
• Language: English
• Subjects: A. Grain growth; A. Hot pressing; C. Mechanical properties; Taguchi method; ZrB2–SiC composites
• ISSN: 0272-8842; 1873-3956
• DOI: 10.1016/j.ceramint.2015.04.027

The influences of hot pressing parameters and SiC particle size on the bulk density, the average ZrB2 grain size and Vickers hardness of ZrB2–25vol% SiC ultrahigh temperature ceramic composites were investigated. In this paper, the Taguchi methodology (An L9 orthogonal array) was used to specify the contributions of four parameters: the hot pressing temperature, holding time, applied pressure and SiC particle size. The experimental procedure included nine tests for four parameters with three levels which were employed to optimize the process parameters. The statistical analyses recognized the hot pressing pressure and temperature as the most consequential parameters affecting the density and hardness of ZrB2–SiC composites. The SiC particle size and holding time were specified as the most effective parameters on the average ZrB2 grain size. The bulk density, average ZrB2 grain size, Vickers hardness and fracture toughness of the sample, hot pressed at optimal conditions (1850°C, 90min, 16MPa and 200nm), reached about 5.36g/cm3, 10.03µm, ~17.1GPa and 5.9MPam1/2, respectively. The confirmation test, carried out under optimum conditions, showed that the experimental results were relatively equal to the predicted values from the Taguchi prediction model. Finally, the mechanisms of enhanced fracture toughness of the hot pressed ZrB2–SiC ceramic composites were discussed.