Chemically Derived Yttria-Stabilized Zirconia for Plasma-Spraying

1990 ◽  
Vol 180 ◽  
Author(s):  
Fawzy G. Sherif ◽  
H. Herman
Keyword(s):  
Grain Size ◽  
Tetragonal Zirconia ◽  
Yttria Stabilized Zirconia ◽  
Metal Alkoxides ◽  
Stabilized Zirconia ◽  
Spray Coatings ◽  
Plasma Spray Coatings ◽  
Hydrolysis Conditions ◽  
Controlled Hydrolysis ◽  
Zirconia Powders

ABSTRACTYttria-stabilized zirconia powders were prepared by three chemical routes utilizing emulsion hydrolysis techniques. Metal alkoxides, acetates and mixtures of alkoxides and acetates were used as starting materials. Under controlled hydrolysis conditions, particles with different morphology and size were obtained. Spherical or granular particles in the range of 20–60u in diameter were formed. The grain size varied from 0.1–0.2u. The powders were applied successfully as plasma spray coatings. The chemical uniformity was demonstrated by the presence of 100% non-transformable tetragonal zirconia in the powder and in the coating.

Analytical TEM study of a yttria stabilized zirconia/glass composite

1988 ◽  
Vol 46 ◽  
pp. 572-573
Author(s):  
Yung-Jen Lin ◽  
Peter Angelini ◽  
Martha L. Mecartney
Keyword(s):  
Grain Size ◽  
Grain Boundary ◽  
Grain Growth ◽  
Room Temperature ◽  
Tetragonal Zirconia ◽  
Yttria Stabilized Zirconia ◽  
Boundary Phase ◽  
Stabilized Zirconia ◽  
High Toughness ◽  
M Phase

Yttria stabilized zirconia is a versatile ceramic material. It can be used for structural components or as a solid electrolyte. Its properties (such as high toughness) are strongly affected by the microstructure. In partially stabilized zirconia, the high toughness is mainly due to the toughening effect of a tetragonal (t) to monoclinic (m) phase transformation in the vicinity of a crack. Retention of tetragonal zirconia at room temperature is important for fabricating transformation toughened materials. To completely retain tetragonal zirconia at room temperature the grain size of the material must be less than a critical size. In yttria stabilized zirconia this critical grain size depends on the yttria concentration. Grain growth of yttria stabilized zirconia is also influenced by the amount of yttria in the grains. These previous studies, however, have focused on the behavior of materials with minimal glassy grain boundary phases. In contrast, in commercial polycrystalline zirconia often a significant amount of glassy grain boundary phase is present. This current research seeks to elucidate the effects of these grain boundary phases on the grain growth in yttria stabilized zirconia ceramics.

Reaction synthesis of mullite-zirconia from mixtures of alumina, silica, and 3 mol% yttria-zirconia powders

1999 ◽  
Vol 14 (3) ◽  
pp. 916-924 ◽  
Author(s):  
Yung-Jen Lin
Keyword(s):  
Boundary Diffusion ◽  
Tetragonal Zirconia ◽  
Nucleation And Growth ◽  
Yttria Stabilized Zirconia ◽  
Aluminosilicate Glass ◽  
Reaction Sintering ◽  
Stabilized Zirconia ◽  
Powder Mixtures ◽  
Zircon Formation ◽  
Zirconia Powders

Mullite-zirconia composites were synthesized by reaction-sintering powder mixtures of α-alumina, amorphous silica, and 3 mol% yttria-stabilized zirconia. It is found that the addition of 3 mol% yttria-zirconia improves sintering and lowers the mullitization temperature. It also suppresses the cristobalite formation and enhances zircon formation between 1300 and 1400 °C. Results further suggest that these effects are consequences of modification of the silicate glass by yttria. Samples containing ≥20 vol% of 3 mol% yttria-zirconia could be sintered at 1500 °C for 2 h to obtain dense composites consisting of mullite and tetragonal zirconia. The microstructural investigations of the sintered samples support the viewpoint that mullite formation is via nucleation and growth from aluminosilicate glass. They also reveal that zirconia can hinder the grain growth of mullite and that the coalescence of zirconia grains is accomplished by grain boundary diffusion.

Preparation of nanosized yttria-stabilized zirconia powders and their characterization

1991 ◽  
Vol 26 (14) ◽  
pp. 3787-3791 ◽  
Author(s):  
T. L. Wen ◽  
V. Hebert ◽  
S. Vilminot ◽  
J. C. Bernier
Keyword(s):  
Yttria Stabilized Zirconia ◽  
Stabilized Zirconia ◽  
Zirconia Powders

Elaboration of Sol-Gel Derived Hydroxyapatite / Yttria Stabilized Zirconia Composite Coatings Obtained for Biomedical Application

2011 ◽  
Vol 312-315 ◽  
pp. 894-899
Author(s):  
Sahar Salehi ◽  
Mohammad Hosseien Fathi
Keyword(s):  
Grain Size ◽  
Crystallite Size ◽  
Grain Growth ◽  
Biomedical Application ◽  
Composite Coatings ◽  
Sol Gel ◽  
Yttria Stabilized Zirconia ◽  
Stabilized Zirconia ◽  
Nanostructured Composite

In this study, nanostructured composite coatings of hydroxyapatite (HA)/ 30wt% yttria stabilized zirconia (YSZ) coatings containing 0, 3, 5, and 8 mol% Y2O3 (namely; HA-0YSZ, HA-3YSZ, HA-5YSZ, and HA-8YSZ) were successfully synthesized using the sol-gel method. The crystallite size of the coating was about ~44-58 nm for tetragonal and cubic zirconia grain size and 75-87 nm for hydroxyapatite grain size. Crack-free and homogeneous HA-YSZ composite coatings were obtained with no observable defects. The uniform distribution of zirconia particles in a composite would be highly beneficial for obtaining homogeneous coatings of HA-YSZ film and would hinder grain growth of HA phase during calcinations. In vitro evaluation in 0.9% NaCl showed that Ca2+ dissolution rate of composite coatings was lower than pure HA coatings.

ESR Investigation of Yttria Stabilized Zirconia Powders with Nanosize Particles

2004 ◽  
Vol 298 (1) ◽  
pp. 289-296 ◽  
Author(s):  
A. M. Slipenyuk ◽  
M. D. Glinchuk ◽  
I. P. Bykov ◽  
A. V. Ragulya ◽  
V. P. Klimenko ◽  
...  
Keyword(s):  
Yttria Stabilized Zirconia ◽  
Stabilized Zirconia ◽  
Nanosize Particles ◽  
Zirconia Powders
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