Interfacial reactions in SiCf/C/Ti17 composites dominated by texture of carbon coatings

Two kinds of turbostratic carbon coatings with different texture were deposited on SiC fibers using single filament chemical vapor deposition by changing substrate temperature: 920 and 1000 °C, labeled as C920 and C1000, respectively, followed by coating Ti17 matrix, and then SiCf/C920/Ti17 and SiCf/C1000/Ti17 composites were fabricated by hot isostatic pressing (HIP). C1000 possesses much stronger texture than C920, evidenced by combined tests of X-ray photoelectron spectrum, Raman spectroscopy and transmission electron microscope (TEM). Interfacial reactions of SiCf/C920/Ti17 and SiCf/C1000/Ti17 composites are found to depend strongly on texture of turbostratic carbon coatings after HIP, revealing that C1000 with stronger texture can hinder the outward diffusion of C and inward diffusion of matrix elements more efficiently than C920, which is elucidated by the results of scanning electron microscope, TEM and energy-dispersive spectroscopy. Interdiffusion between C coating and Ti17 matrix results in formation of C gradient distribution in interfacial reaction layer for both composites, in which interfacial zone of fiber and matrix can be described as turbostratic C||amorphous C||fine-grained TiC||transition TiC||coarse-grained TiC, however, each sub-layer thickness is determined by the texture of C coating. Based on these results, the model of interfacial reactions dominated by texture of C coatings was proposed.

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