Tensile strength of plasma-sprayed alumina and/or zirconia coatings on titanium

Failure of the plasma-sprayed coating of lanthanum hexaluminate

“…The phase transitions of ␥ → ␦ and ␦ → ␣ occur at 1000 and 1100 • C, respectively. [28][29][30] and the process of ␥ → ␦ is accompanied by a volume expansion. 28 Even though no strong evidences are supported here, it is suggested that the three exothermic peaks correspond to the recrystallization of LMA, the phase transitions of ␥ → ␦-Al 2 O 3 and ␦ → ␣-Al 2 O 3 , respectively.…”

“…[28][29][30] and the process of ␥ → ␦ is accompanied by a volume expansion. 28 Even though no strong evidences are supported here, it is suggested that the three exothermic peaks correspond to the recrystallization of LMA, the phase transitions of ␥ → ␦-Al 2 O 3 and ␦ → ␣-Al 2 O 3 , respectively. The phase transitions in LMA coating are complicated, high-resolution XRD is necessary to study these processes and this work is still in progress.…”

“…The plasma-sprayed coating of alumina usually contains mainly ␥-Al 2 O 3 and some ␣,␦-Al 2 O 3 , the phase transitions of ␥ → ␦ and ␦ → ␣ occur at 1000 • C and 1100 • C, respectively. [28][29][30] The phase transition of ␥ → ␦ is companied by a volume expansion, 28 and the net shrinkage of the process ␥ → ␣ is about 2%. 29 Both coatings of silica and alumina have re-crystallization or phase transition above 1000 • C. The re-crystallization or phase transition would make serious contractions and cracks for their coatings, and this is the main reason that they can not be used as TBC materials for the applications above 1000 • C. 31 Even though LMA coating has re-crystallization and phase transition above 900 • C, but it still has a long thermal cycling life, indicating that LMA has a high stress tolerance due to the platelet structure.…”

Plasma sprayed α-Al2O3 main phase coating using γ-Al2O3 powders

“…Plasma spraying is a precise thermal spraying method having been developed after flame spraying and possesses such significant advantages as high compactness and bonding strength of coatings, not easy to be oxidised for sprayed materials, convenient to implement spraying high melting point material, etc, consequently having been one of the most widely employed spraying technologies [18][19][20]. Currently α-Al 2 O 3 is mostly adopted as the original powder crude material for preparing alumina coatings by plasma spraying, but the obtained coatings have the main phase of γ-Al 2 O 3 that has relatively loose structure and much lower compactness, hardness, abrasion and corrosion resistance than α-Al 2 O 3 [21][22][23]. In this research, we attempt to produce a ceramic coating containing α-Al 2 O 3 as the main phase by plasma spraying using low-cost γ-Al 2 O 3 as crude materials and investigate the mechanical properties of the coating, so as to provide a reference and guidance for the technology development and engineering application of the newstyle alumina ceramic coating.…”

Adherence of Porcelain Veneered on Titanium with an Intermediate Plasma-Sprayed Zirconia Layer

“…7,8) In addition, the tensile strength of as-sprayed ZrO 2 on Ti seemed unaffected by heat treatment at high temperature. 9) The aim of this study was to study the adherence of porcelain on Ti with the introduction of an intermediate layer of plasma-sprayed zirconia as bond coat on Ti prior to porcelain overcoat and firing. Previous in vivo test has classified ZrO 2 as an bioinert material without the evidence of adverse tissue response.…”