Narrow Results

The effects of BN/Ti molar ratio on the self-propagating high-temperature synthesis (SHS) reaction behaviors and final products in the Ti-BN system were experimentally investigated. With an increase in the BN/Ti ratio, the combustion temperature and wave velocity first increase and then decrease with the maximum values displaying at BN/Ti=0.67. A substoichiometric TiN_1-x was obtained for BN/Ti<0.67, and a stoichiometric one was produced for BN/Ti=0.67. Moreover, the microstructure photographs of the products reveal that with the increase of the BN/Ti ratio, the grains of the ceramic phases tend to be finer.

The deformation microstructures generated by nanoindentation of multilayer coatings consisting of TiSiN layers alternating with ten TiN interlayers, were examined by cross-sectional transmission electron microscopy (XTEM). Two multilayered coatings were studied: a thin TiSiN coating interlayered with thick TiN interlayer and a thick TiSiN coating alternated with thin TiN layers. A monolithic TiSiN coating was also examined for comparison. Surface morphology of the samples was found to be variable. Both surface roughness and coating hardness increase with the thickness of the outermost TiSiN layer. All samples show columnar structures, and for the multilayer coatings, epitaxial growth of these columnar grains through the TiSiN/TiN multilayers was observed. Stair-shaped shear cracks can be seen in the multilayer coating alternated with thick TiN interlayers, whereas radial and edge cracks are observed in the coating multilayered with thin TiN layers and in the monolithic coating. TEM analysis also suggests that columnar grains help to resist the initiation of edge cracks. Compared to other studies on similar coating systems with fewer periods of interlayers, the deformation observed here appears less severe, indicating an improvement in the strength of the coating through increasing the number of interlayers.

An ultrathin metasurface-based absorber consisting of titanium nitride (TiN) nano-disk arrays–dielectric layer-TiN substrate is proposed in this paper. The absorber exhibits near-unity absorption in the whole visible range of 380–780 nm. Our results demonstrate that the proposed metasurface-based absorber is not only independent of light polarization, but also exhibits angle-independent absorption behavior for oblique incidence up to 70${}^{\circ }$. The high absorption performance of the TiN nano-disk arrays-based absorber can attribute to two different loss mechanisms associated with the intrinsic loss and plasmonic resonance.

Molecular dynamics simulation was adopted to investigate the nanoscale titanium nitride formation at the early formation stage in high-strength low-alloy steel. During the cluster formation process, the nitride clusters were formed through the atom aggregation. The atomic interactions of titanium and nitride atoms were revealed and the cluster property was discussed. The nanoscale titanium nitride clusters own a wide composition, and the cluster formation mechanism was concluded.

The effects of parameters on nanoscale titanium nitride during the formation process in ferrite were studied via the molecular dynamics (MD) simulation. The formation of titanium nitride was executed by employing a dislocation-motivated formation model in which the atomic diffusion has a significant contribution. The roles of N/Ti atom ratio, temperature and matrix defect were identified and the according nitride formation property was analyzed.

Titanium nitride (TiN) films were deposited on high-speed steel (HSS) using cathodic arc physical vapor deposition (CAPVD) technique. The effect of substrate bias on the crystallography, microstructure, deposition rate, coating thickness and composition, hardness, and adhesion strength of TiN films was investigated. The crystallography of the films was investigated using X-ray diffraction with glazing incidence angle technique. The coating microstructure and elemental composition analysis were carried out using field emission scanning electron microscopy (FE-SEM) together with energy-dispersive X-ray. Crystallography of the films revealed that the effect of substrate bias shows complex symmetry in crystal structure. The resputtering effect due to the high-energy ion bombardment on the film surface influenced the thickness as well as the color of deposited coatings. By increasing the substrate bias from 0 to - 150 V, the size and amount of macrodroplets decreased, whereas the micro-Vickers hardness decreased from 2530 HV_0.05 to 1500 HV_0.05. Scratch tester used to compare the critical loads for coatings and the adhesion achievable at substrate bias of - 50 V was demonstrated, with relevance to the various modes.

Titanium nitride (TiN) widely used as hard coating material was coated on tool steels, namely on high-speed steel (HSS) and D2 tool steel by physical vapor deposition method. The goal of this study was to examine the effect of ion etching with and without titanium (Ti) and chromium (Cr) on the adhesion strength of TiN coatings deposited on tool steels. From the scratch tester, it was observed that by increasing Ti ion etching showed an increase in adhesion strength of the deposited coatings. The coatings deposited with Cr ion etching showed poor adhesion compared with the coatings deposited with Ti ion etching. Scratch test measurements showed that the coating deposited with titanium ion etching for 16 min is the most stable coating and maintained even at the critical load of 66 N. The curve obtained via penetration depth along the scratch trace is linear in the case of HSS, whereas is slightly flexible in the case of D2 tool steel. The coatings deposited on HSS exhibit better adhesion compared with those on D2 tool steel.

We report the deposition of Ti and TiN films on Si/SiO₂ (100) substrate using e-beam evaporation technique. The influence of substrate temperature on the structural and morphological properties has been studied. The structure and morphology of the deposited films were analyzed by X-ray diffraction (XRD) and field emission scanning electron microscope (FESEM) measurements, respectively. XRD patterns reveal the FCC symmetry for both the Ti and TiN films. The grain size of the films was found to increase with the increase in substrate temperature. FESEM micrographs showed a smooth morphology of the film with columnar grain structure.

Pulse laser deposited thin films of TiN are irradiated by 1 MeV carbon (C⁺) ions beam for various doses ranging 0.4 to 2.8 × 10¹⁴ ions/cm². Atomic force microscopy (AFM) analysis reveals the formation of hillocks like structures after ion irradiation. X-ray diffraction (XRD) investigations show that the film crystallinity increases for lower doses ranging from 0.4 to 1.2 × 10¹⁴ ions/cm² and decreases for higher doses (2 to 2.8 × 10¹⁴ ions/cm²) of ions. No new bands are identified from Raman spectroscopy. However, a noticeable change in microhardness has been observed. The hillock densities as well as hardness are strongly dependent upon ion dose.

In the present work, hardness and elastic modulus of a titanium nitride coatings prepared on Ti6Al4V by powder immersion reaction-assisted coating (PIRAC) are tested and comparatively studied with a physical vapor deposition (PVD) TiN coating. Surface hardness of the PIRAC coatings is about 11GPa, much lower than that of PVD coating of 22GPa. The hardness distribution profile from surface to substrate of the PVD coatings is steeply decreased from $\sim$22GPa to $\sim$4.5GPa of the Ti6Al4V substrate. The PIRAC coatings show a gradually decreasing hardness distribution profile. Elastic modulus of the PVD coating is about 426GPa. The PIRAC coatings show adjustable elastic modulus. Elastic modulus of the PIRAC coatings prepared at 750${}^{\circ }$C for 24h and that at 800${}^{\circ }$C for 8h is about 234 and 293GPa, respectively.

Friction stir processing (FSP), which was the advancement in the friction stir welding technique, is thought to be an economic approach to alloying in the solid state that can be used to make composites. In this study, FSP was carried out to produce AA7075 (B₄$\mathrm{\text{C}}+\mathrm{\text{T}}$iN) composite by varying the composition of the reinforcement particles. Microstructural analysis was carried out and the homogenous distribution of the reinforced particles on the surface of AA7075 alloy was ensured. X-ray diffraction studies were carried out to analyze the phases present after fabricating the hybrid surface composites. Microhardness test was performed on the specimens before and after the fabrication process. Grain refinement in the friction stir processed zones was evidently seen in the optical microstructures. The combined effect of the ceramic powders and grain refinement led to increase in the microhardness in the hybrid surface composites compared with the base AA7075 plate. A 33.87% increase in microhardness was observed in the sample AA7075 reinforced with 75% B₄C and 25% TiN. Wear testing was carried out at various loads (5, 10, 15 and 20 N) and at different sliding velocities (300, 350, 400 and 450 rpm) and the track distance was maintained at 1000 m. It was observed that the highest wear rate is $3.2\times 10^{-7}$ cm³/Nm for the base plate AA7075 and the sample AA7075 reinforced with 50% B₄C and 50% TiN shows the lowest wear rate of $0.56\times 10^{-7}$ cm³/Nm. It is observed that the addition of B₄C and TiN has resulted in a significant improvement in the wear resistance of the AA7075 alloy.

Glucose, carbamide and petroleum coke as carbon sources are separately added to butyl titanate and ethanol system. The initial powder containing titanium source and carbon source is prepared by sol–gel method. IR analysis of the initial powder shows that: glucose-butyl titanate system and carbamide-butyl titanate system form water-soluble compounds. After being dried, they form Ti₂O₃ and C mixed powder. Petroleum coke-butyl titanate system forms TiO₂ powder with nanometer size in carbon. Regarding initial powder as a raw material, titanium nitride powder is prepared by carbon thermal reduction. The XRD analysis shows that the titanium nitride powder is formed after the initial powder prepared in petroleum coke-butyl titanate system is kept at 1350°C for 5 h. The added Fe₂O₃ accelerates the synthesis of titanium nitride; the initial powder prepared in glucose-butyl titanate is kept at 1400°C for 5 h and then synthesizes the titanium nitride powder. Fe₂O₃ does not accelerate the synthesis of titanium nitride. The initial powder prepared in carbamide-butyl titanate system is found to form volatile material in N₂, but no titanium nitride powder is found.

Titanium nitride (TiN) thin films have low electrical resistivity, good chemical and metallurgical stability, and exceptional mechanical properties. As such, we are interested in exploring TiN for use as mold material for micro-and nano replication. Focused ion beam (FIB) technique was successfully used to fabricate sub-micron sized pattern on a TiN/Si(100) wafer. This mask-free fabrication technique takes advantage of the kinetic precision of FIB; the energy of ions used was 40 KeV. The width and depth of each trench in the TiN mold are 390 nm and 280 nm respectively.

The taltanlum nitride films had been synthesized by the reactive magnetron sputtering which deals with the orthogonal design technology of the films including N₂ partial pressure rate, substrate temperature, sputtering pressure and sputtering current. The results showed that the adhesion between the film and substrate was influenced mainly by sputtering pressure and substrate temperature. The hardness of taltanlum nitride films was affected greatly by N₂ partial pressure. The hardness of the taltanlum nitride film was as high as about HK4000. The blood compatibility of the taltanlum nitride films were evaluated by clotting time measurement and platelet adhesion test. The blood compatibility of the TiN, Ta films and low temperature isotropic pyrolytic carbon (LTIC) also were evaluated for comparing. The result showed that the blood compatibility of taltanlum nitride was better than that of the TiN, Ta and LTIC.