Surface changes in Al2O3–base composite ceramics under action of laser treatment

Abstract Features of the structural-phase reconstruction of the surface remelted layer (track) of ceramic specimens with different contents of Y 2 Ti 2 O 7 , Y 3 Al 5 O 12 , and Al 2 O 3 under the action of directional laser heating have been investigated by the XRD, ATR-FTIR, EDS, and AFM methods. It has been established that, depending of the treatment mode (the irradiation power and traverse speed of the laser beam), the phase composition of the remelted layer changes as compared to that of the volume part of the ceramic specimen, and, as a result of the dissociation of predominantly Y 3 Al 5 O 12 and Y 2 Ti 2 O 7 , cavities and asperities appear. High-temperature laser heating and the presence of a temperature gradient in tracks leads to an intensive ablation process from the surface of the tracks, as a result of which the surface layer of the tracks is depleted of the lower-melting components with a (Y 2 Ti 2 O 7 ) and is enriched in more refractory components (Al 2 O 3 ). A part of the ablation products is deposited in the form of oxides on the surface of tracks. The obtained results make it possible to represent a multilayer model of ceramics subjected to laser treatment: the ceramic volume proper with a specific phase composition → remelted volume layer with a changed phase composition → surface layer with a new changed phase composition, and deposited ablation products. The thickness of the layers depends on the irradiation mode, and clear-cut boundaries between them are absent.