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Laser Surface Solutionizing and Crystallization of Al 2 O 3 –Cr 2 O 3
Author(s) -
Kakazey Mykola,
Vlasova Marina,
Márquez Aguilar Pedro Antonio,
Bykov Olexandr,
Stetsenko Volodymyr,
Ragulya Andriy
Publication year - 2009
Publication title -
international journal of applied ceramic technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.4
H-Index - 57
eISSN - 1744-7402
pISSN - 1546-542X
DOI - 10.1111/j.1744-7402.2008.02280.x
Subject(s) - materials science , crystallization , impurity , microstructure , electron paramagnetic resonance , surface layer , analytical chemistry (journal) , dissolution , phase (matter) , paramagnetism , layer (electronics) , crystallography , nuclear magnetic resonance , composite material , chemical engineering , condensed matter physics , physics , organic chemistry , chromatography , chemistry , engineering
Laser surface treatment of different materials influences significantly on the surface morphology, microstructure, and phase components of treated zones. The local temperature conditions, fast melting–fast crystallization , produced during the process is an interesting direction of preparing new ceramic materials in which a controlled inhomogeneous distribution of the impurities, the phases, etc. can be realized. This work is concerned with an experimental investigation of the crystallization, microstructure, and properties induced by a laser beam in α‐Al 2 O 3 + n α‐Cr 2 O 3 pressed powder samples using electron paramagnetic resonance (EPR) spectroscopy and X‐ray diffraction methods. During laser irradiation, melting of the sample surface layers takes place. In such a layer, the Al 2 O 3 melt covers the α‐Cr 2 O 3 particles. Complete dissolution of α‐Cr 2 O 3 in Al 2 O 3 does not occur. During cooling of the sample, crystallization of the α‐Al 2 O 3 layer takes place. The crystallized layer shows preferred orientation, which is different in different samples. In the surface layer, the undissolved α‐Cr 2 O 3 particles also acquire a preferred orientation, the direction of which does not coincide with the direction of the preferred crystallization of α‐Al 2 O 3 . Analysis of changes in the width and the shape of EPR spectra with the increasing concentration of paramagnetic centers under their homogeneous and inhomogeneous spatial distribution in specimens was performed. It is shown that the character of the concentration distribution of chromium impurities in laser‐treated α‐Al 2 O 3 samples is determined by the diffusion laws and is inhomogeneous.