Jateamento para remoção do material refratário: influência sobre a resistência flexural de uma cerâmica feldspática

Abstract

The aim of this study was to evaluate the influence of different blasting protocols for the removal of the refractory material on biaxial flexural strength of a feldspathic ceramic. Forty five disks (1.5 mm thick, 13.5 mm diameter) of feldspathic ceramic Super Porcelain Ex-3 (Noritake, Japan) were sintered on 45 refractory discs (Begoform, Bego). After being regularized and polished on the surface opposite to the one in contact with the refractory material, they were randomized and divided into three groups (n = 15): C, the group that did not receive blasting (control), OA, the group that received alumina blasting and PV, the group that was blasting with glass beads, simulating protocols for the removal of the residues of refractory material used in the refractory die technique. The biaxial flexural strength was determined by a “piston-on-three-ball” test, in accordance with ISO 6872:2008. The obtained data were submitted to the Weibull analysis to calculate the characteristic strength (σ0) and Weibull modulus (m) of the groups. Confidence intervals were calculated by 95% (ENV 843-5:1996) in order to compare the parameters between the groups. There was no statistical difference between the characteristic strengths of PV (103.18 MPa) and C (124.23 MPa). OA group (84.41 MPa) had statistically lower resistance than the group C. However, there was no statistical difference between PV and OA. The results suggest that, between the two treatments tested for the removal of refractory residues, blasting with glass beads is the most indicated.