Papers by Keyword: Titanium Nitride

Abstract: The effects of nitrogen pre-implantation of AISI C1045 steel substrates on the properties of deposited TiN coatings were investigated. Nitrogen ion implantations were performed at 40 keV, to the fluences from 5x1016 – 5x1017 ions/cm2. On so prepared substrates we deposited 1.3 μm thick TiN layers by reactive sputtering. Structural characterizations of the samples were performed by grazing incidence X-ray diffraction analysis (GXRD), standard X-ray diffraction analysis (XRD), and scanning electron microscopy (SEM). Microhardness was measured by Vicker’s method. The obtained results indicate the formation of iron-nitrides in the near surface region of the substrates, more pronounced for higher implanted fluences. The structure of the deposited TiN coatings shows a strong dependence on the pre-implantation of the substrates, which is attributed to the changed local structure at the surface. Ion implantation and deposition of hard TiN coatings induce an increase of the microhardness of this low performance steel of more than eight times.

Abstract: Surface modification is a promising technique to improve wear properties of titanium and titanium alloys by modifying either the surface composition or microstructure. Laser remelting and laser nitriding of commercial purity titanium were carried out under pure argon and pure nitrogen ambient, respectively. Characterization of the laser treated surface was done by optical microscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD), microhardness tester. During laser irradiation heating, Ti exhibits a height activity and combines with N in the atmosphere of pure nitrogen forming TiN and TiN0.3, whereas Ti only transform into martensitic Ti in pure argon. The Vickers microhardnesses are greatly improved by laser remelting and laser nitriding.

Abstract: Ti/TiN multilayer films were synthesized on 17-4PH stainless steel using unbalanced magnetron sputtering. The modulation periods is ranged from 100nm to 350 nm. The microstructure of the multilayer films was analyzed by X-ray diffraction. The cross-section views of the multilayer films were studied by scanning electron microscope (SEM). The microhardness and wear resistance of the films were measured by a HXD-1000 microhardness tester and ball-on-disk wear tester. The corrosion resistance of the multilayer films was evaluated by potentiodynamic polarization scans in a 3% NaCl solution. The results showed that there was TiNx intergradation layer in the films. The microhardness and the wear resistance of the multilayer films increased with the layer number. The Ti/TiN multilayer can improve the corrosive resistance of the 17-4PH stainless steel.

Abstract: In this work, some surface properties of AISI M2 steel were improved by a thermoreactive deposition process. Gas nitriding was realized on AISI M2 steel at 550°C for 2 h in an ammoniac atmosphere and then, titanizing treatment performed on pre-nitrided steel in the powder mixture consisting of ferro-titanium, ammonium chloride and alumina at 1000°C for 1-4 h. Structural characterization of titanium nitride layer formed on the surface of AISI M2 steel was carried out by using optical microscopy, scanning electron microscopy, electron microprobe and Xray diffraction (XRD) analysis. The hardness measurements of titanium nitride layer were conducted under 10 g loads by using Vickers microhardness indenter. Structural analysis studies showed that titanium nitride layers formed on the AISI M2 steel samples were smooth, compact and homogeneous. XRD analysis show that the coating layer formed on the steel samples includes TiN, Fe6Mo7N2, C0.7N0.3Ti, C0.3N0.7Ti and V2N phases. The hardness of titanium nitride layers formed on the steel samples is between 2040±186 and 2418±291 HV0.01. The thickness of titanium nitride layer formed on the steel samples ranged from 3.86±0.43 9m to 6.13±0.47 9m, depending on treatment time.

Abstract: Xerogel was prepared by the sol-gel method using butyl titanate, alcohol, carbamide and glucose as raw materials. The precursor powders were obtained after xerogel was solvothermally treated at 220oC for 2 h. The IR analysis suggests that the precursor with 10% excess glucose gave an absorption peak at 1084.37cm-1, which was assigned to Ti-OH bond, while no such a peak can be observed for that with 30% excess glucose. The prepared precursor powders were then sintered at 1400oC in nitrogen atmosphere. XRD and SEM results indicated that the sintering time and the contents of glucose had great effects on synthesizing titanium nitride powders. The titanium nitride powders with a high purity and a mean grain size of about 35 nm could be prepared by heating the precursor with 10% excess glucose at 1400oC for 6.5 h.

Abstract: Generally, solution nitriding (nitrogen permeation) is not applied to ferritic stainless steel, which has low nitrogen solubility in the ferrite phase. This study has investigated phase changes, nitride precipitations and hardness variations of Fe-11Cr-0.1Ti (409L) ferritic stainless steel following nitrogen permeation and tempering heat treatments. The strong affinity between nitrogen and Ti enabled the permeation of nitrogen to 409L ferritic stainless steel. The nitrogen-permeated surface changed to a martensitic phase with a hardness range of between 520 and 585Hv, depending on the nitrogen permeation temperature and time, while the surface nitrogen content was about 0.04%~0.05%. When tempering the NPSA (solution annealing after nitrogen permeation) treated specimen at 450 °C, a maximum hardness of 550Hv was obtained, probably due to the precipitation of very fine rod and square type titanium nitrides, while the minimum hardness of 365Hv was obtained at a tempering temperature of 650°C, owing to the precipitation of coarse TiN.

Abstract: A laser beam profilometry technique was used to investigate residual stress accumulation during TiN deposition and stress relaxation during post-deposition heat treatment. The test coatings were reactively sputtered on silicon and steel substrates using a UMS technique. TiN coatings, deposited at different bias and pressure levels, were evaluated for residual stress and microhardness. It was found that both the residual stress and the hardness were strongly affected by the coating deposition conditions. In addition, stress-temperature correlations were obtained by subjecting the coatings to temperature cycles up to 450°C. Stress-temperature plots revealed that the level of residual stress relaxation depended on deposition conditions and only coatings deposited at low ion bombardment could be fully annealed. The role of intrinsic and thermal stresses in the total residual stress in the coating/substrate system was also discussed.

Abstract: Si3N4-based composite powders have been synthesized by vapor phase and liquid phase processes. Nano-sized Si3N4-TiN composite particles were formed by the vapor phase method, in which TiN nanocrystallites were included in amorphous Si3N4 particles. The composite powder was also formed by the liquid phase method, where Si and Ti complex imide powders were prepared in an organic solvent and decomposed by heating. Si3N4-TiN nanocomposites were fabricated by hot pressing of the composite powders. The Si3N4-TiN composites were also fabricated by in-situ process from amorphous Si3N4 and Y2O3-TiO2-AlN additive. In all processes, rod-like Si3N4 grain growth was stimulated by TiN inclusion.

Abstract: The addition of titanium nitride (TiN) particles to a Si3N4 matrix reduces the intrinsic electric resistivity of this ceramic allowing it to be machined by EDM in cutting tools manufacturing. Gains can be expected given the cost reduction by the increase of productivity when shaping these hard to machine ceramic materials. Si3N4 ceramic matrix composites (CMC’s) with 0- 30vol.% of TiN sub-micrometric particles were produced by uniaxial hot pressing (HP) and pressureless sintering (PS). For the PS samples, EDM tests showed that machining of the composites is possible when they contain at least 23vol.% TiN particles what corresponds to a resistivity of 7.5
cm. For HP samples at least 30vol.% of TiN is required to get an electroconductive material for EDM machining. This difference is due to the lower temperatures used in the HP process that delay the formation of a conductive network between the TiN particles.