Papers by Keyword: Titanium Nitride

Abstract: Effect of pH value and dispersant of polyethylene imine (PEI) on dispersion of nano TiN in ethanol liquid was investigated by sedimentation volume and viscosity, surface electric characteristic of particles was measured by Zeta potential. Results showed that pH value and PEI concentration had an important effect on dispersion of nano TiN. Excellent dispersibility was obtained through adjusting PEI amount and pH value. It was found that PEI was an efficient dispersant for nano TiN to disperse in ethanol liquid. The dispersibility follows by electrostatic and space steric stability mechanism.

Abstract: The formation of hard surface layer on steel provides a protective coating against wear, thermal loads and corrosion. In the present work a hard composite layer is formed on steel surfaces by preplacement of titanium powder and melted under nitrogen environment. Surface melting was conducted using TIG torch with different energy inputs. The microstructure and the morphology of the melt tracks were investigated using SEM and X-ray diffraction. The in-situ melting of titanium powder in nitrogen atmosphere produced dendritic microstructure of titanium nitride. The melt layer contained dispersed TiN, Ti2N dendrites highly populated at the surface compared to the deeper melt and gave a maximum surface hardness of around 1927 Hv. The wear property of the melt track was investigated using pin-on-disk tribometer at room temperature. The modified surface layer gave a low friction value of 0.12 and wear rate of 0.007895 ×10-4 compared to 1.648 × 10-4 mm3/N/m for the uncoated steel surface.

Abstract: In order to modify surface structure titanium powder was preplaced on steel surface and melted under TIG (tungsten inert gas) torch in a pure nitrogen environment which formed a resolidified layer of around 1 mm thickness. The preplaced titanium powder content was varied between 1.3 and 1.8 mg/mm2 and melting was conducted with energy inputs of 324 J/mm to 540 J/mm. The modified surface layer was analyzed in terms of microstructure, hardness, surface defects such as cracks and pores. The resolidified layer consisted of dispersion of TiN, Ti2N and TiN.88 dendrites in a ferrite matrix containing titanium. The modified layer showed some defects when melting were performed with low energy inputs. A maximum surface hardness of around 2000 Hv was developed in most of the tracks and this hardness corresponds to high concentration of TiN dendrites within the modified layer.

Abstract: Laser as a source of focused energy may be applied for the modification of microstructure and/or composition of the near surface region of a component. The technique may be applied for the development of a ceramic/intermetallics/interstitial compound dispersed metal matrix composite layer on the surface of metallic substrate by melting the substrate with a high power laser and simultaneous addition of alloy powders for the development of metal matrix composite layer by in-situ reactions. In the present contribution, development of metal-dispersed and intermetallic-dispersed matrix composite layer on the surface of metallic matrix has been discussed with a suitable example of its application.

Abstract: Active screen plasma nitriding (ASPN) is an emerging surface engineering technology that offers many advantages over the conventional DC plasma nitriding (DCPN). In this research, plasma nitriding of H11 tool steel, using titanium active screen was investigated. Samples were plasma nitrided at 550oC, for 10 and 20 h with 3 different gas mixtures of H2/N2% = 3, 4, 5. The coating microstructure and phase analysis were investigated using Scanning Electron Microscopy (SEM) and X-ray Diffraction techniques. The dominant phase in the compound layer was TiN. With increasing processing time, the layer thickness was increased. According to SEM results, the sample surface was formed of nano sized and particulate titanium nitride particles. It was shown that with increasing H2% in gas mixtures, better surface quality, golden yellow color, was obtained. Also, the intensity of TiN peaks and layer thickness were increased significantly.

Abstract: Titanium nitride coatings were prepared on common glass slides using TiCl4 and NH3 by atmospheric pressure chemical vapor deposition. The deposition temperature range from 450-650 °C was applied. X-ray diffraction, scanning electron microscope, energy dispersive X-ray Spectrometer, four-point probe sheet resistance instrument and UV-Vis spectrometer were employed to characterize the obtained coatings. The crystallization and electrical conductivity of the coatings was improved with increasing deposition temperature. The reflectance and transmittance spectra showed all the coatings exhibited solar control performance. The coating prepared at 650 °C presented the optimum solar control performance in the present study.

Abstract: The increasing use of nanoparticles makes it necessary to check up possible toxicological risks of this new materials class. In this paper we describe on two nanopowders (tungsten carbide, titanium nitride) which methods and parameters of a chemical-physical characterization are needed in forefront of toxicological experiments. This includes investigation on the powder itself as well as on particles suspended in water and physiological media, respectively. The most important result is that nanoparticles agglomerate in serum-free medium within minutes, whereas in the present of serum an agglomeration is inhibited. Hence, we have physiological suspensions with well-distributed stabilized particles which allow performing toxicological testing under reproducible conditions. Furthermore we could prove that tungsten carbide particles were taken up into cells, but no acute toxicity was found determined by means of in vitro viability tests with different cells.

Abstract: TiN films have been deposited on K211 super alloy substrates by chemical vapor deposition (CVD) using a gaseous mixture of TiCl4, NH3, and Ar as carrier gas between 400 and 700°C. The films were characterized by means of scanning electron microscopy and energy dispersive spectrometer. In this paper, the wear and corrosion resistance of TiN coatings have been investigated by abrasive experiments and corrosion tests. It was shown that coated samples demonstrated significantly higher wear resistance than those uncoated by weight loss measurements in the test procedure. Under the conditions of the corrosion experiments, substrates with TiN coatings showed better corrosion resistance than uncoated samples and stainless steel.

Abstract: Si3N4-Si2N2O-TiN composite ceramics were in-situ fabricated by using following reactions of (1) 3TiO2 + Si3N4 → 3TiN + 3SiO2 + N2 and (2) Si3N4+ SiO2 → 2Si2N2O. The mixed powder of α-Si3N4, Al2O3, Y2O3 and TiO2 was hot-pressed at 24 MPa and 1800°-1900°C for 1-4 h in N2. Sintered composite ceramics were characterized by XRD, SEM, TEM, four-point bending test and Vickers indentation method. XRD results and TEM observation showed that TiN and amorphous SiO2 were formed at 1250°C by the reaction (1), and the Si2N2O phase formed by reaction (2) above 1800°C. Si3N4-Si2N2O-TiN composites consisted of ≥2 m sized Si2N2O grains with TiN and Si3N4 grains. Hardness and fracture strength of the composites were comparable to those of Si2N2O ceramics, with fracture toughness being improved at 5vol% TiN containing composites.

Abstract: Interfacial microstructure of TiN-TiB2 composite, which was synthesized by hot shock compaction combined explosively shock condolidation and self-propagating high-temperature synthesis, was investigated by transmission electron microscopy (TEM). In the TiN-TiB2 composite included 60mol% TiN, an experimentally measured average grain size of the both TiN and TiB2 was approximately 500nm, and it decreased rather than those of the raw powders. By the conventional TEM observations, we clarified that there was a specific orientation relationship between cubic TiN and hexagonal TiB2. The high resolution electron microscopy (HREM) observations revealed that the TiN/TiB2 interphase boudnaries were atomically flat. We also observed grain boundaries of the composite and found that no secondary phases such as amorphous phase and precipitates were observed at the grain boundaries in the composite.