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Figure 1. Nano-nodular self-assembly of titanium on variously pre-micro-roughened titanium surfaces. (A) Scanning electron microscopic (SEM) x10,000 images before and after electron-beam physical vapor deposition (EB-PVD) of titanium for 16 min 40 sec, with a deposition rate of 5 Å / sec onto various titanium surfaces. Images in gray indicate no or little nano-nodules created, while images highlighted in blue indicate dense, uniform, and consistent nano-nodules. Titanium substrates (disks of 20 mm in diameter) were prepared by the following: machining (Machined), hydrofluoric-acid-etching (HF), sand-blasting, hydrofluoric acid and sulfuric acid dual-etching (HF-H2SO4), sulfuric-acid-etching (H2SO4), and hydrochloric acid and sulfuric acid dual-etching (HCl-H2SO4). Bar = 2 µm and applies to all panels. (B) Atomic force micrographs of the various Ti substrates tested, showing various degrees of micro-roughness before titanium deposition (top images). The images are presented in a fixed vertical scale of 1.5 µm. Nano-structuring was unsuccessful in the first two substrates (A). Histograms show the results of quantitative roughness analysis for the substrates before Ti deposition: root mean-square roughness; peak-to-valley roughness; inter-irregularity space. Data are shown as mean ± standard deviation (n = 5). The blue bars indicate the substrates that resulted in nano-nodular creation, while the gray bars indicate the substrates that created few or no nano-nodules.
