Plasma alumina coating surface

The seemingly simple question of the relation the characteristics of a mechanically prepared metal surface and adhesion to that surface has sporadically occupied attention for many decades without any very general conclusion being reached [69]. In some recent work, Amada et al. [70,71] grit-blasted a steel substrate, varying the angle between the gun and the specimen surface, and measured the adhesion of a plasma-sprayed alumina coating. They examined profiles of the... 

Basak, A.K., Achanta, S., CeUs, J.P., Vardavoulias, M., Matteazzi, P., 2008. Structure and mechanical properties of plasma sprayed nanostructured alumina and FeCuAl—alumina cermet coatings. Surface and Coatings Technology 02 (11), 2368—2373. 

Figure 6.19 (a) STEM image of a cross section of a plasma-sprayed titania (brookite) bond coat-hydroxyapatite topcoat assembly. On the substrate side, embedded alumina (corundum) particles are visible. The sample was produced by focused ion beam (FIB) cutting to conserve the true geometry of the coating interfaces. The black strip at the top surface consists of platinum deposited by decomposing an organic compound to... 

For thin-film metallization, a thin metallic film is first deposited onto the surface of the substrate. The deposition can be accomplished by thermal evaporation, electronic-beam- or plasma-assisted sputtering, or ion-beam coating techniques, all standard microelectronic processes. A silicon wafer is the most commonly used substrate for thin-film sensor fabrication. Other substrate materials such as glass, quartz, and alumina can also be used. The adhesion of the thin metallic film to the substrate can be enhanced by using a selected metallic film. For example, the formation of gold film on silicon can be enhanced by first depositing a thin layer of chromium onto the substrate. This procedure is also a common practice in microelectronic processing. However, as noted above, this thin chromium layer may unintentionally participate in the electrode reaction. 

The dry samples of silica-coated alumina were analyzed by inductively coupled plasma-atomic emission spectroscopy (ICP-AES). Specific surface area was determined by nitrogen adsorption (BET). Particle-size determination was made by low-angle forward scattering of light from a laser beam (Leeds and Northrup s Microtrac particle sizer) and by monitoring sedimentation with a finely collimated beam of low-energy x-rays and a detector (Micromeritics Sedigraph 5100). 

A ceramic bond coat is almost exclusively used to modify a surface for adhesive bonding. The ceramics include, but are not limited to, alumina, zirconia, titania, spinels, carbides and combinations of these materials." The thermally sprayed bond coatings provide a rough surface on the order of 8 p,m R that has a three-dimensional morphology. Arc-plasma is traditionally used for deposition of the ceramics for these applications. 

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