Phase Transformation in Zone of Laser Treatment of Y 2 Ti 2 O 7 -Al 2 O 3 Compositional Ceramics
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Phase Transformation in Zone of Laser Treatment of Y2Ti2O7-Al2O3 Compositional Ceramics Pedro A. Márquez Aguilar1, Marina Vlasova1*, Mykola Kakazey1, Adalberto Castro Hernández1. 1
Center of Investigation in Engineering and Applied Sciences of the Autonomous University of Morelos State (CIICAp-UAEMor), Av. Universidad, 1001, Cuernavaca, Morelos, Mexico.
ABSTRACT
The synthesis of Y2Ti2O7-Al2O3 compositional (multiphase) ceramics from powder mixtures Al2O3-Y2O3-TiO2 was carried out in two stages: 1) under the traditional sintering and then 2) in regime of directed laser heating. It was established that the sintering of mixtures with different content of components and the ratio of TiO 2/Y2O3 = 2.34 in ceramic specimens the main phases are Y2Ti2O7 and α-Al2O3. The content of the main phases in ceramic materials also depends upon the oxide content in the initial mixtures. In ceramics the Y3Al5O12 is formed only at sufficiently high content of titanium and yttrium oxides in initial mixtures. In laser remelting, the phase composition is substantially different from that obtained at the traditional sintering, and depends on the mode of laser heating: irradiation power and the moving speed of the laser beam (i.e., heating temperature). Under certain conditions of laser remelting can be obtained superficial ceramic layer with crystallographic directional crystallization of Y2Ti2O7 and Al2O3 crystallites. The size of crystallites and the coefficient texturing also depend on the mode of laser treatment.
INTRODUCTION Compositional (multiphase) ceramic obtained from mixtures of oxides such as Al2O3, Y2O3 and TiO2 is of interest, since; depending on the content of oxides is formed ceramics with variety of phases that are typical for binary systems Al2O3-Y2O3, Al2O3TiO2 and Y2O3-TiO2 [1, 2]. All compounds to the data of binary compositions have a unique set of properties and are widely used in various fields of technology. For example, the Y3Al5O12 ceramics is used as a polycrystalline transparent ceramics for high-power lasers [3, 4]. The Y2Ti2O7 is one of the most important compounds, which has shown many technological applications, such as ion conductor, photo catalyst for water-splitting, nonlinear optical material, and buffer layer for superconducting films [5, 6]. For binary compositions, for example, Y 3Al5O12-Al2O3, etc., combination of unique physic-chemical and mechanical properties of ceramics is significantly expanded [7, 8]. In [9, 10] it was found that at laser treatment of multiphase ceramics, consisting of Y3Al5O12-Al2O3, the textured surface layer is formed and the phase composition of this layer differs from the basic ceramics. This means that is forming a completely new double-layered ceramic material whose properties and regions of application should be significantly expanded. The aim of the present work is to investigate the phase transformations in the surface layer formed during directed laser treatment of multicomponent oxide ceramics based on Y2Ti2O7 and α-Al2O3 with an TiO2/YState = 2.34. on 29 Dec 20
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