Influence of boron nitride (BN) addition in commercially pure titanium (Cp-Ti) was characterized for their microstructural variation, hardness, and oxidation kinetics. Feedstock powders, Cp-Ti with 3 wt% BN (3BN) and 6 wt% BN (6BN), were prepared by roller mill followed by additive manufacturing using laser engineered net shaping (LENS™). Rate of oxidation was measured from thermogravimetric analysis (TGA) at 1000 °C for 50 h. Average instantaneous parabolic constants (kp) for Cp-Ti, 3BN, and 6BN were 41.2 ± 12.0, 28.6 ± 2.8, and 18.2 ± 9.2 mg2/(cm4 h), respectively. Cp-Ti displayed acicular α-Ti microstructure. After TGA, large equiaxed grains along with TiO2 formation at the grain boundaries were observed, which increased the hardness. With BN addition, plate-like TiN and needle-like TiB secondary phases were also observed. Hardness for Cp-Ti, 3BN, and 6BN were 256.9 ± 7.7, 424.0 ± 33.6, and 548.3 ± 49.7 HV0.2, respectively. Overall, a small addition of BN was effective in improving the oxidation resistance of Cp-Ti.

Given the global water challenges, solar-driven steam generation has become a renewed topic recently as an energy-efficient way for clean water production. Here, a hybrid plasmonic structure consisting of a top layer of TiN nanoparticles (NPs) and a bottom layer of mesoporous anodized alumina membrane (AAM) was rationally designed and fabricated. The top TiN NPs with broadband light absorption acted as a plasmonic heating layer, which converted the absorbed light to heat efficiently for interfacial water heating. The AAM acted as the mechanical support layer, guaranteeing the heat isolation and continuous water replenishment. With optimized thickness of the TiN top layer, a solar steam generation efficiency of 87.7% was achieved in this study. This efficiency is comparable or even higher than prior studies. The current work proves the capability of the TiN NPs as an alternative photothermal material.

We investigated the chemical shift of the electron energy-loss near-edge structure (ELNES) for the nitrogen K-edge and titanium L3-edge measured from the interface region between a titanium nitride layer and a titanium layer. Both the titanium nitride and titanium layers were prepared by a sputtering method. Elemental analysis for nitride and titanium in the vicinity of the interface region was performed using a standard technique in electron energy-loss spectroscopy. It was demonstrated that both the ELNES of nitrogen K-edge and titanium L3-edge presented the chemical shift, more or less, depending on the composition of TiNx. The experimental findings were interpreted using a first-principles band structure calculation. The chemical shifts of nitrogen K-edge and titanium L3-edge can be used as fingerprinting for readily distinguishing the composition of TiNx.

Deposition of Ti/N compositionally gradient film onto Ti-6Al-4V alloy substrates was carried out by reactive DC sputtering, not only to improve the blood compatibility of the alloy but also to relax the stress concentrated at the interface between the film and the alloy substrate. The compositional gradient was realized by varying continuously the nitrogen content in Ar-N2 sputter gas during deposition. In Auger electron spectroscopy (AES) analysis, Auger spectra were acquired in the N(E) mode using the beam brightness modulation (BBM) method to overcome the problem of the peak overlap of the principal Auger nitrogen transition peak (N-KLL) with one of titanium peaks (Ti-LMM). The deposited film appeared to be uniform and adhesive. TiN formation at the surface of the film was assumed, because of its yellow gold color and the X-ray diffraction (XRD) pattern for it. Under scanning electron microscopy, it was found that the surface had fine particles dispersed on a smooth accumulated deposit and that this depositing method improved the structural property of the film at the surface. According to AES in-depth profiles, the nitrogen (N) concentration in the film gradually decreased in the depth direction from the surface toward the alloy, confirming that a Ti/N compositionally gradient film had formed on the alloy substrate.

Depth profiling has been performed by using Auger electron spectrometry and X-ray photoelectron spectrometry in combination with Ar-ion sputtering. The data obtained by both surface-analytical methods have been evaluated by means of factor analysis and partly by applying artificial neural network in order to determine the compositional layering of different thin-films such as TiNx on Ti, Cr2O3/CrN sandwich layer, and copper oxide on Cu. Both multivariate statistical methods applied to the same data sets lead to results that agree well within statistical deviations provided that the structure of the artificial neural network is constructed appropriate to the actual problem.