Improvement of mechanical properties of Y-TZP by thermal annealing with monoclinic zirconia nanoparticle coating

摘要

Objective. To assess whether a thermal annealing with a monoclinic zirconia (mZrO(2)) nanoparticle coating can improve the reliability of sandblasted yttria-stabilized tetragonal zirconia polycrystals (Y-TZP) and maintain its mechanical strength.Methods. Commercially available Y-TZP (Lava Frame, 3M Dental Products) disks were sintered and surface-treated as follows: AS (as sintered, with no treatment); SB (sandblasting); SBTA (sandblasting followed by thermal annealing at 1000 degrees C); and SB-mZr-TA (sandblasting followed by thermal annealing at 1000 degrees C with the mZrO(2) nanoparticle coating). The mZrO(2) nanoparticles of 21 nm in size were prepared by a hydrothermal method, and coated onto Y-TZP sintered disks as a 5 g/L ethanol dispersion. Biaxial flexural strength (S) was measured using the piston-on-three-ball test, and reliability was evaluated by the Weibull modulus (m).Results. Biaxial flexural tests showed a significant increase in the strength of Group SB (S-SB = 1445 +/- 191 MPa) compared with Group AS (S-AS = 1071 +/- 112 MPa). The thermal annealing improved the reliabilities of the sandblasted Y-TZP (m(SB-TA) = 20.14 and m(SB-mZr-TA) = 21.33), as compared with Group SB (m(SB) = 7.77). However, the conventional thermal annealing without the mZrO(2) coating caused a significant decrease in the strength of sandblasted Y-TZP (SSB-TA = 1273 +/- 65 MPa). Importantly, the mZrO(2) coating prevented the decrease in the strength caused by conventional thermal annealing (SSB-mZr-TA = 1379 +/- 65 MPa).Significance. The thermal annealing with the mZrO(2) nanoparticle coating can improve the reliability of sandblasted Y-TZP and maintain its mechanical strength, which would otherwise be decreased by the conventional annealing process. (C) 2019 The Academy of Dental Materials. Published by Elsevier Inc. All rights reserved.