Growing Integration Layer [GIL] Strategy: Direct Fabrication of Compositionally, Structurally and Functionally Graded Ceramic Coatings and/or Films from Mother Materials in Solution
We have proposed a novel concept and technology of the formation “Growing Integration Layer” [GIL] between ceramics and metallic materials to improve the adhesion performance. Those GIL(s) can be prepared via integration of ceramic film formation from a component of the metallic materials by chemical and /or electrochemical reactions in a solution at low temperature of RT-200℃. They have particular features: 1) Widely diffused interface(s), 2) Continuously graded layers grown from the bulk(substrate), 3) Low temperature process,etc. They are quite different from Layer-by-Layer[LBL] strategy, where every layer is deposited from the Top. BaTiO3 or SrTiO3/TiOx GIL films on Ti plates formed by hydrothermal-electrochemical method showed good adhesion. CaTiO3/Al2O3/Ti2Al GIL films on TiAl exhibited excellent adhesion and anti-oxidation performances: they could be sustained for 10 times cyclic oxidation test at 900 C in air for 5 hrs. The GIL strategy is effective for many metallic alloys and bulk metallic glassed because they generally contain active component(s). On a Ti-base Bulk Metallic Glass, we could succeed to prepare bioactive titanate nano-mesh layer by hydrothermal-electrochemical techniques at 90-120℃. Similarly, bioactive oxide layers could be prepared on different Bulk Metallic Glasses. Carbon film formation on SiC can be regarded as one of GIL methods.
The GIL methods are typical “Soft Process” and ”Green Process” using aqueous solutions, and applicable for various functional and structural ceramics layers.