Formation Of Titanium Nitride Layer Research Articles

Laser-Microplasma Reactive Powder Spraying of Titanium Coatings with Nitride Phases

One of the actual problems of modern surface engineering is to improve the wear and corrosion resistance of structural elements made ​​of titanium and titanium alloys, which owing to a number of unique characteristics are becoming more widely used in industries such as aerospace, chemical engineering, medicine and many others. Promising way to improve the tribological characteristics as well as corrosion resistance in aggressive environments of such materials is the formation of titanium nitride layers on the surface. Titanium nitride is characterized by high hardness (up to 20000 MPa), wear resistance, chemical resistance and high refractory properties [1], which allows to significantly expand applicability and product lifetime of these materials.

Characteristics and Wear Performance of Nitrided Ti6Al4V

Samples of a Ti6Al4V alloy were treated by thermochemical gas nitriding at 1120°C for 7 h. Gas nitriding provided formation of titanium nitride layer with a hardness over 1800 HV. The titanium nitride layer exhibited excellent wear resistance along with a lower coefficient of friction against alumina ball under dry sliding conditions when compared to the as-received state.

Microstructure and properties of Ag/N dual ions implanted titanium

Silver (Ag) and nitrogen (N) dual ions were sequentially implanted into titanium to prepare the samples including PIII-Ag–N (Ag ions prior to N implantation), PIII-N–Ag (N prior to Ag ions implantation) and PIII-Ag + N (Ag/N dual ions co-implantation) via plasma immersion ion implantation (PIII) technology. All of the samples were characterized by a scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS). The antibacterial activity, corrosion resistance and hardness of as-implanted samples were investigated. The results show that the Ag/N dual ions implanted titanium exhibit high bactericidal ability to Escherichia coli and Staphylococcus aureus due to the formation of silver nanoparticles in the near surface region. The zeta potentials show more positive evolution in order of pure titanium, PIII-Ag–N, PIII-N–Ag and PIII-Ag + N, which favors to contact with bacteria thus to inhibit their growth and proliferation. Moreover, the formation of titanium nitride layer during Ag/N dual ions implantation can greatly improve the corrosion resistance and hardness of titanium. The present study suggests that the Ag/N dual ions co-implanted process is the most efficient way to obtain the titanium implant with high antibacterial activity, corrosion resistance and hardness.

Formation of titanium nitride layers from a gaseous phase with the participation of a chemical reaction: contribution of the temperature deposition

The processes of formation of titanium nitride layers by chemical vapor deposition techniques are, as a rule, conducted in a TiCl4-H2-N2 atmosphere at pressures ranging from 40 to 80 kPa, the treatment temperature being 1123 to 1273 K. The formation of titanium nitride layers on an iron substrate begins with the reduction of titanium chlorides, this being the result of a chemical reaction of these chlorides with iron contained in the substrate. The titanium thus liberated reacts with nitrogen to form titanium nitride. The above-mentioned reactions can take place until a compact TiN layer has been formed. The further growth of the layer proceeds owing to the reduction of titanium chloride, TiCl4, by means of hydrogen down to TiCl3 or TiCl2. As a result of disproportionation of lower chlorides, titanium appears which reacts with nitrogen to form TiN [1, 2]. It is assumed that in the process of formation of titanium nitride from chloride atmospheres, as long as a compact layer has not yet been formed, the most probable reactions are those of reduction of titanium chloride by iron, as a result of which FeCl2 appears [3]. In the literature no unambiguous statement can be found regarding the chemical reactions responsible for the occurrence of titanium on the growth surface at temperatures below 1273 K. The production of TiN layers by the low-pressure chemical vapor deposition (LPCVD) technique is, as a rule, performed in a steel reactor. In such reactors, chemical transport of iron from the reactor walls towards the surface of the layer under formation is likely to occur. Iron, present on the growth surface, may under such conditions continue to act as a reducer of titanium chlorides, this leading to the appearance of titanium on the compact titanium nitride layer. In order to verify the correctness of this assumption, the process of growth of TiN layers in a TiCl4-H2-N2 atmosphere was investigated in the presence of a source of iron, namely a cylindrical screen made of carbon steel (0.10 wt% C), as well as without any source of iron, i.e. by applying an Al2O3 reactor with no screen. The layers were deposited on Armco iron and Al2O3 substrates in the form of plates of dimensions 30 mm× 110 mm× 2 mm. The process of deposition of TiN layers was carried out on an apparatus used for LPCVD treatment [1]. Parameters of the deposition process are given in Table I. The layers produced in temperatures from 1073 K to 1423 K in the presence of a source of iron on an Armco iron as well as an Al2O3 substrate were golden-colored, characteristic of titanium nitride. The investigation of the phase composition, performed by X-ray diffraction analysis (Philips diffractometer, CuKα radiation), has shown that the layers produced on the Al2O3 as well as those on the Armco iron substrate consist of the TiN phase. In the case of Armco iron specimens for temperature up to 1350 K a loss in weight is observed, whereupon its value increases. In contrast to this, the Al2O3 substrate is the only substrate on which an increase in weight is observed (Fig. 1). A loss in weight of the Armco iron specimens may be indicative of the participation of iron, contained in the substrate, in chemical reactions with the components of the gaseous phase. Fig. 2 shows the surface appearance of the layer deposited on the Armco iron substrates at temperatures of 1073 K and 1233 K it confirms that in the deposition process of TiN on Armco iron chemical reactions occur in which iron contained in the substrate participate, and clear etching of the grain boundaries are seen. Surface analysis of the Al2O3 substrate, performed prior to the deposition of the layer, has demonstrated

Kinetics of the Formation of Titanium Nitride Layers by Rapid Thermal Low Pressure Chemical Vapor Deposition from TiCl4 ‐ NH 3 ‐ H 2

A kinetic study of the titanium nitride growth by low pressure chemical vapor deposition (LPCVD) from gas‐phase was carried out. Experiments were performed in the temperature range of 600–900°C and in the total pressure range of 20 to 73 Pa. Partial pressures ranges were 0.4 to 2.5 Pa for , 5 to 43 Pa for , and 13 to 28 Pa for The following law of deposition was obtained A model was developed to explain the difference between these results and the published results, and to point out the importance of gas injection configuration on the experimental reaction orders and on the apparent activation energies. When (respectively, ) is injected quite near the substrate, this species is strongly adsorbed on the surface, and the available sites for adsorption (respectively, ) are reduced. Then the reaction order with respect to (respectively, is negative, and the rate‐determining step is the adsorption of (respectively, ). When these two species are injected far from the substrate, the rate‐determining step is the reaction between adsorbed and adsorbed NH or .

Formation of titanium nitride layers by the nitridation of titanium in high-pressure ammonium ambient

Nitridation of titanium layer is performed in a high-pressure (5.9 kg/cm2) ammonium (NH3) ambient. Although the nitridation of titanium surface does not occur at 700 °C in an atmospheric pressure, it does occur at 650 °C in an ammonium pressure of 5.9 kg/cm2. Nitridation temperature can be lowered by 100–150 °C with an increase in ammonium pressure from 2.0 to 5.9 kg/cm2. Thickness of titanium nitride layer increased markedly with increasing ammonium pressure. This is due to the enhancement of the chemical reaction of titanium with ammonium gas by the increase of pressure. The thickness increases with an increase of nitridation temperature. The thickness of the titanium silicide layer formed by the silicidation reaction between titanium and the silicon wafer is reduced with the increase in ammonium pressure.

Formation of Titanium Nitride Layers and Composite Layers under Glow Discharge Conditions

By applying a glow discharge in a gaseous mixture composed of TiCI4, H2, and N2 it is possible to produce titanium nitride layers or – if the process is conducted in two stages differing in the atmospheres used – composite layers, e.g. a nitrided layer covered by a titanium nitride layer. Electric activation of the gaseous medium and of the surface under treatment makes it possible to reduce the treatment temperature to ∼600°C.An installation is described for producing titanium nitride layers and composite layers and the results of structural examinations and wear tests performed on these layers are presented.

Formation of titanium nitride layers from a gaseous phase with the participation of a chemical reaction

Formation of titanium nitride layers from a gaseous phase with the participation of a chemical reaction