TiC Coatings Research Articles

In-situ investigation of the oxidation behavior of powdered TiN, Ti(C,N) and TiC coatings grown by chemical vapor deposition

Since hard coatings used in metal cutting applications are exposed to temperatures up to 1000 °C, their oxidation stability is a crucial parameter for the tool lifetime. Thus, within this work, the detailed oxidation mechanisms of chemical vapor deposited TiN, Ti(C,N) and TiC coatings were studied. Coating powders were subjected to a heat treatment between 420 and 940 °C in ambient atmosphere and their phase composition was monitored in-situ by X-ray diffraction. Rietveld refinement allowed to quantify the phase fractions of TiN, Ti(C,N), TiC, TiO2 rutile and TiO2 anatase at every measurement temperature. Combining this method with differential scanning calorimetry and thermo-gravimetric analysis allowed to precisely track the progress of the involved reactions during oxidation. TiN exhibits the highest oxidation onset temperature of 640 °C. This fact is attributed to the higher Gibbs free energy of the oxidation reaction compared to TiC and the large domain size of the nitride. The latter observation also explains the single-step reaction to rutile without anatase formation. In case of Ti(C,N) and TiC, rutile and anatase form in the course of the oxidation. Ternary Ti(C,N) displays the highest oxidation end temperature and is only entirely consumed at 880 °C. Owing to the lower Gibbs free energy of the oxidation and the lower domain size in comparison to the nitride, TiC exhibits the lowest oxidation onset and end temperature.

Significantly enhanced photocatalytic activity of TiO2/TiC coatings under visible light

Rutile TiO2 forms on TiC coatings (TiO2/TiC coatings) during carbon-embedding heat treatment (cHT) for TiC coatings. The photocatalytic activity of TiO2/TiC coatings has been significantly enhanced, especially under visible light. The influence of cHT temperature for TiC and Ti coatings on surface morphology, formed compounds, and photocatalytic activity has also been investigated. In general, rutile TiO2 forms on TiC coatings, whereas TiCxOy forms on Ti coatings. By raising the cHT temperature for TiC coatings, the surface morphology of TiO2/TiC coatings with a pore-like structure significantly changes from nano-size to micro-size, inevitably resulting in the reduction of the accessible surface area. However, the influence of cHT temperature on the Ti coatings is insignificant, demonstrating a smooth surface morphology. Notably, owing to the increased accessible surface area and formed heterojunction of TiO2/TiC, the photocatalytic activity of TiO2/TiC coatings has been significantly enhanced approximately 6 times especially under visible light, compared with that of TiCxOy/Ti coatings. Furthermore, when the cHT temperature has been raised, the photocatalytic activity of TiO2/TiC coatings initially increases and then decreases, achieving their most satisfaction at 1073 K, which is attributed to the narrowed band gap of TiO2 owing to the shifted O 1s spectra.

TiC coatings on an alloyed steel produced by thermal diffusion

Abstract In this study, an alloyed steel surface was coated by thermal diffusion with titanium carbide powder at different temperatures (900, 1000 and 1100 °C) and times (1, 2 and 3 h) to determine their effect on the coating microstructure. The thermal coating was carried out by tube cementation designed and manufactured by us for the purpose of thermal coating. Coating thickness, element distribution and phase composition were analyzed by optical microscope, scanning electron microscopy, energy dispersive spectrometry, X-ray diffraction (XRD) methods, respectively. Microhardness tests were performed to determine mechanical properties. The influence of different temperatures and production times on the coating thickness and microstructure were determined. The results illustrated that titanium carbide particles adhere almost completely and are diffused to the substrate during production. Thus, coating thickness increased through increasing time and temperatures. Moreover, microhardness increased with increasing temperature more than time did. The highest microhardness value achieved was 1301 HV for 3 hours. Temperatures of 1000 °C were reached due to the diffusion of TiC to the surface of the substrate, thus forming an extremely hard and protective layer.

TiC coatings on an alloyed steel produced by thermal diffusion

Abstract In this study, an alloyed steel surface was coated by thermal diffusion with titanium carbide powder at different temperatures (900, 1000 and 1100 °C) and times (1, 2 and 3 h) to determine their effect on the coating microstructure. The thermal coating was carried out by tube cementation designed and manufactured by us for the purpose of thermal coating. Coating thickness, element distribution and phase composition were analyzed by optical microscope, scanning electron microscopy, energy dispersive spectrometry, X-ray diffraction (XRD) methods, respectively. Microhardness tests were performed to determine mechanical properties. The influence of different temperatures and production times on the coating thickness and microstructure were determined. The results illustrated that titanium carbide particles adhere almost completely and are diffused to the substrate during production. Thus, coating thickness increased through increasing time and temperatures. Moreover, microhardness increased with increasing temperature more than time did. The highest microhardness value achieved was 1301 HV for 3 hours. Temperatures of 1000 °C were reached due to the diffusion of TiC to the surface of the substrate, thus forming an extremely hard and protective layer.

Resistance to intense electron beam bombardment of TiC/Graphite: Numerical modeling and experimental investigation

Resistance to intense electron beam bombardment of TiC/Graphite was investigated numerically and experimentally. The results indicate that the decreasing of initial electron energy and the increasing of TiC coating thickness could both enhance the electron energy deposition inside the surface layer of the TiC/Graphite, and finally cause the increasement of the temperature differences at the interface between TiC coating and graphite substrate. The graphite substrate is well coated with TiC in all the TiC/graphite targets, and the morphology of the TiC coatings could be controlled by adjusting its thickness. Under electron beam with accelerating voltage of 850 keV, current of 11 kA, pulsewidth of 40 ns and pulse number of 30 times, TiC/Graphite target with TiC coating thickness of 1 μm shows more excellent electron beam bombardment resistance, agreeing with the results of the numerical modeling.

Deposition and properties of plasma sprayed NiCrCoMo–TiC composite coatings

In this study, NiCrCoMo–TiC composite coatings were plasma sprayed using NiCrCoMo alloy powders and Ti–C powders. The microstructure, micro-hardness, and wear behaviours were investigated. NiCrCoMo coating consisted of Ni–Cr–Co–Mo phase. NiCrCoMo–TiC coatings consisted of Ni–Cr–Co–Mo, TiC, and TiO2 phases. The average porosity of NiCrCoMo coating was about 5.5 ± 0.6% and it increased to 10.1 ± 0.9% after adding 25 wt% Ti–C powders. All the coatings had a thickness of ≥200 μm with a layered structure. The micro-hardness of NiCrCoMo–TiC coatings increased with the addition of Ti–C powders, and it increased by 39% to 854HV0.2 as the added Ti–C powders was 25 wt%. The friction coefficient of NiCrCoMo coating was 0.43, and that of NiCrCoMo–TiC coatings was 0.60–0.64. The wear volume of NiCrCoMo–15TiC coating was 0.3099 mm3, which was just 28% of that of NiCrCoMo coating. The wear mechanism of NiCrCoMo–TiC coatings was adhesive wear, fatigue wear and abrasive wear.

Comparative Study on Wear Behavior of Plasma-Sprayed TiC Coating Sliding Against Different Counterparts

In this work, TiC coating was fabricated by atmospheric plasma spray (APS) technique and its tribological performances sliding against stainless steel, Si3N4 and WC-Co were evaluated using ball-on-disk tests under 50 N load. The results indicated that the TiC coating exhibited diverse tribological behaviors. The TiC/Si3N4 tribopair showed the lowest friction coefficient with a significant fluctuation. The TiC/steel tribopair exhibited the lowest coating wear rate, while the TiC/WC-Co tribopair had the highest coating wear rate among the three tribopairs. The tribological mechanisms were tentatively explained based on the observation of worn surfaces. This work might provide some clues for the applications of TiC coatings.

Microstructure and tribological properties of in-situ synthesized TiC reinforced reactive plasma sprayed Co-based coatings

In this study, TiC in-situ reinforced Co-based composite coatings (Co–TiC) were fabricated by reactive plasma spraying using Ti-graphite and Co-based alloy powders. The microstructure, mechanical and tribological properties were investigated. The hardness and tribological properties were measured by Vickers indenter and circular sliding tester. Si3N4 was used as friction counterpart, the sliding speed was 400r/min, the normal load was 30 N, and the sliding time was 30min. The results showed that Co–TiC coatings consisted of TiC, α-Co, Fe3Ni3B, Ni31Si12 and TiO2 phases. TiC phase was formed by the reaction between Ti and C directly. With the increase of Ti-graphite powders addition, more TiC was synthesized in-situ. The in-situ formed TiC enhanced the hardness and wear resistance of the coatings, coupling with forming small porosities (<9%). The highest hardness was 1035HV0.2 for Co–15TiC, which is about 20% higher than that of Co coating. The lowest wear volume was 0.0745 mm3 for Co–15TiC coating, which is just 13% of that of Co coating. The main wear mechanism of Co–TiC coatings in the present sliding test was abrasive wear.

Comparative investigation of single-layer and multilayer Nb-doped TiC coatings deposited by pulsed vacuum deposition techniques

Hard-yet-tough coatings are required to protect structural materials, cutting, stamping, and forging tools operating under harsh conditions that combine wear, corrosion, and elevated temperatures. To reveal the high potential of niobium (Nb) as an additive to binary Ti-based coatings, single-layer and multilayer Nb-doped TiC coatings were obtained by pulsed arc evaporation (PAE), electro-spark deposition (ESD) in vacuum, and combination of these methods. Structure, elemental, and phase compositions were studied by means of X-ray diffraction, scanning and transmission electron microscopy, X-ray photoelectron spectroscopy, and Raman spectroscopy. The coatings were characterized in terms of their hardness, elastic modulus, tribological properties, and electrochemical behavior in 3.5% NaCl solution. Tribological tests were carried out under various conditions, such as applied load (5 and 10 N), medium (air and 3.5% NaCl solution), and counterpart material (Al2O3 and 440C steel). Thin PAE coating (1.8 μm thick) consisted of 2–5 × 50–100 nm (Ti,Nb)C crystallites, elongated in direction of the coating growth, embedded in an amorphous matrix (75% sp2 + 25% sp3-hybridized carbon). Thick ESD coating (20 μm) contained TiC grains uniformly distributed in an eutectic Fe(Co)-Fe2(Ti,Nb) matrix with a minor content of Ti-Ni and γ-Fe phases. The single-layer PAE coating demonstrated superior tribological performance both in air and 3.5% NaCl solution, as well as high oxidation resistance during tribocorrosion tests. As a top layer in the PAE/ESD coating, it provided wear protection of less wear-resistant ESD sublayer. It is assumed that the main benefit of the ESD sublayer in the PAE/ESD coating may be that it provides enhanced toughness and high thickness, which prevents a soft substrate from high stress-induced plastic deformation.

Influence of SiC and TiC nanoparticles reinforcement on the microstructure, tribological, and scratch resistance behavior of electroless Ni–P coatings

Two different ceramic carbide nanoparticles (SiC, and TiC) were separately incorporated into the Ni–P matrix via the electroless deposition method. As prepared Ni–P, Ni–P–SiC, and Ni–P–TiC coatings were subjected to heat treatment at 400 °C for 1 h. The surface morphology, microstructural transformation, Vicker’s microhardness, tribological and scratch resistance properties were studied with reference to the different carbide reinforcements as well as heat treatment. Inter-nodular space, craters and kinks are created due to the branching effect of nodules in the surface of the Ni–P–SiC (TiC) composite coatings. After the heat treatment, the matrix phase transformation was not altered due to the incorporation of SiC or TiC into the Ni–P coating; however, a slight increase in residual stress was identified from the XRD analysis. In addition, the content of carbon deposition was found to be higher in the matrix of Ni–P–SiC composite coating than that in the Ni–P–TiC coating. The agglomeration of SiC particles was higher than TiC particles in the coating matrix, which was also supported by the result of Zeta potential measurement. Heat treatment improved wear and coefficient of friction in the Ni–P–SiC and Ni–P–TiC composite coatings. Compared to Ni–P–SiC coating, Ni–P–TiC coating revealed the enhanced tribological and scratch resistance performance after the heat treatment.

Microstructure and thermal conductivity of graphite flake/Cu composites with a TiC or Cu coating on graphite flakes

Graphite flake/Cu composites with Cu or TiC coatings on the graphite surface were fabricated via a powder metallurgy method. The effect of the flake’s surface coating on the microstructure and thermal conductivities of the graphite flake/Cu composites was studied. The results show that a good contact interfacial structure is established when the TiC or Cu coating is introduced. The thermal conductivity of the TiC- and Cu-coated composites with a 60 vol% flake reached 668 W m−1 K−1 and 612 W m−1 K−1, respectively. A modified Diffuse Mismatch Model for anisotropic graphite was established to estimate the interfacial thermal resistance, and the Effective Medium Approach was used to analyze the thermal conductivity behavior of composites. The results show that both coated composites exhibit low interfacial thermal resistance, resulting in high thermal conductivity in the X-Y plane. The thermal conductivity may be further enhanced if a preferable alignment control is used.

A key to tune the grain size gradient of the TiC coating on titanium by interstitial carburization: The timing for pressing

Herein, we fabricated TiC coatings on titanium via the interstitial carburization technique. By hot-pressing the titanium substrate with cast iron at 1100 °C, the interstitial carbon atoms in the cast iron diffused into titanium, forming a TiC coating. The timing of starting pressing affected the spatial distribution of TiC grain size, namely starting pressing at 1100 °C generated coatings with a clear gradient microstructure, while starting pressing at room temperature generated coatings with a relatively homogeneous microstructure. The TiC grain size in the gradient coating increased from 0.3 μm to 1.1 μm with increasing distance from the surface, giving rise to a nanohardness gradient varying from 25 GPa to 32 GPa. The relatively homogeneous microstructure resulted in a constant nanohardness of 32 GPa in the coating. Both coatings exhibited an extremely high micro-hardness of 2100–2300 HV and strong adhesion with the substrate. These findings provide a route for controlling the spatial distribution of the carbide grain size by designing the time evolution of temperature and pressure. These results should be applicable to more substrate materials and may also be valuable for other hot-pressing based technologies.

A study of the effect of deposition conditions on the phase-structural state of ion-plasma WC – TiC coatings

Studies of the influence of thermal and radiation factors on the elemental composition and phase-structural state of WC-TiC ion-plasma condensates of a quasibinary system are presented. As a thermal factor, we used different substrate temperatures during deposition and temperatures of high-temperature annealing of coatings after their deposition. The influence of the radiation factor was changed by applying a negative bias potential of different magnitudes to the substrate during coating deposition. It was found that with a change in the substrate temperature during deposition (in the temperature range 80–950 °C), a change occurs in the elemental composition of the coating. With an increase in the deposition temperature, the relative content of heavy metal atoms W increases and the relative content of Ti and C atoms decreases. At the phase-structural level, this leads to a change from the single-phase state ((W, Ti)C supersaturated solid solution at a deposition temperature of less than 700 °C) to two-phase ((W, Ti)C and α-W 2 C phases at a deposition temperature of more than 700 °C). The use of high-temperature annealing of coatings after their formation showed a relatively low decay activation efficiency. At an annealing temperature of 800 °C, a noticeable change in the phase-structural state is not observed, and at the highest temperature of 1000 °C and holding for 2 hours, the content of the α-W 2 C phase is relatively small and does not exceed 15 vol %. The supply of a bias potential stimulates the formation of a two-phase state from (W, Ti)C and α-W 2 C phases with nanometer crystallite size. With an increase in the bias potential from –50 V to –115 V, the average crystallite size decreases from 4.5 nm to 3.8 nm. The use of structural engineering methods in the work to create two-phase materials based on a quasibinary WC-TiC system is the basis for increasing the strength and crack resistance of coatings of such systems

Biocorrosion and biological properties of sputtered ceramic carbide coatings for biomedical applications

Surface coating with superior corrosion resistance properties is indispensable for biomedical implant industries to reduce the cytotoxicity related problems. In this work, microstructure, biocorrosion and biological properties of magnetron sputtered TiC and ZrC coatings on type 316L stainless steel (SS) substrates are studied for biomedical applications. Biocorrosion properties have been examined in the Artificial Blood Plasma (ABP) solution with 1% and 10% of H2O2 to study the corrosion behavior of carbides coated 316L SS. The formation of strong oxide passive layers on ceramic carbide coated substrates could enhance the corrosion resistance properties than uncoated SS substrates. The whole blood protein adsorption behavior of carbides coated and uncoated SS substrates are studied and the bacterial adhesion behavior is measured with Pseudomonas aeruginosa (P.aeruginosa) pathogen. The results revealed that the coatings possess higher protein adsorption and lower bacterial adhesion than that of bare steel substrates. In addition, Alizarin red based assay is done to confirm the biomineralization (calcium precipitation) of osteoblast like cells onto test samples and the results showed that TiC and ZrC coatings could enhance the biomineralization process.

Comparison of microstructure and tribological properties of plasma-sprayed TiN, TiC and TiB2 coatings

In this work, TiN, TiC and TiB2 coatings were fabricated by atmospheric plasma spray (APS) technique. The phase composition, microstructure, mechanical and tribological properties of the three kinds of coatings were investigated and compared in detail. The results showed that all the coatings were relatively homogenous with lamellar microstructure, while oxidation phenomenon occurred during the deposition processes. The TiN owned the highest oxygen content, while the TiB2 coating presented the highest roughness and porosity. The elastic modulus and hardness values of the TiC coating were about 189.7 ± 26.6 GPa and 7.7 ± 0.7 GPa, respectively, which were higher than those of the TiN and TiB2 coatings. The TiC coating exhibited the best tribological property with the lowest friction coefficients and wear rates under both low and high loads against WC-Co ball. The wear mechanisms of the three kinds of coatings were analyzed as well.

Improvement in Mechanical and Thermal Properties of Graphite Flake/Cu Composites by Introducing TiC Coating on Graphite Flake Surface

In this work, TiC coating was successfully deposited on a graphite flake surface via molten salt technique, for the purpose of promoting the interfacial connection between Cu and graphite flake. Vacuum hot pressing was then employed to prepare TiC-coated graphite flake/Cu composite. The results indicate that introducing TiC coating on graphite flake surface can evidently reduce the pores and gaps at the interface, resulting in a significant improvement on the bending strength. When the TiC-coated graphite flake content is 60 vol%, the bending strength is increased by 58% compared with the uncoated one. The coefficient of thermal expansion dropped from 6.0 ppm·K−1 to 4.4 ppm·K−1, with the corresponding thermal conductivity as high as 571 W·m−1·K−1. The outstanding thermal conductivity, apposite coefficient of thermal expansion, as well as superior processability, make TiC-coated graphite flake/Cu composite a satisfactory electronic packaging material with vast prospect utilized in microelectronic industry.

Hydrogen Permeation of Multi-Layered-Coatings

Using a substrate of AISI 316L austenitic stainless steel, which is used for components in high-pressure hydrogen systems, the hydrogen barrier properties of samples with single-layer coatings of TiC, TiN, and TiAlN as well as a multi-layered coating of TiAlN and TiMoN were evaluated. The ion plating method was used, and coating thicknesses of 2.0–2.6 μm were obtained. Hydrogen permeation tests were carried out under a differential hydrogen pressure of 400 kPa and at a temperature between 573 and 773 K, and the quantities of hydrogen that permeated the samples were measured. This study aimed at elucidating the relationship between the microstructures of the coatings and the hydrogen permeation properties. Coatings of TiC, TiN, TiAlN, and TiAlN/TiMoN facilitated reductions of the hydrogen permeabilities to 1/100 or less of that of the uncoated substrate. The samples coated with TiN and TiC that developed columnar crystals vertical to the substrate exhibited higher hydrogen permeabilities. The experiment confirmed that the coatings composed of fine crystal grains were highly effective as hydrogen barriers, and that this barrier property became even more efficient if multiple layers of the coatings were applied. The crystal grain boundaries of the coating and interfaces of each film in a multi-layered coating may serve as hydrogen trapping sites. We speculate that fine crystal structures with multiple crystal grain boundaries and multi-layered coating interfaces will contribute to the development of hydrogen barriers.

Laser ablation behaviors of vacuum plasma sprayed ZrC‐based coatings

AbstractZrC, ZrC‐30 vol% SiC, and ZrC‐30 vol% TiC coatings were fabricated by vacuum plasma spray and the laser ablation behaviors were evaluated by a CO2 laser beam under two heat fluxes (15.9 and 25.5 MW/m2). The phase compositions and microstructures of the coatings after ablation were investigated and the effect of SiC and TiC additives was analyzed. The results showed that the ZrC–SiC coating displayed better ablation resistance compared with the ZrC and ZrC–TiC coatings under 15.9 MW/m2 heat flux. While the ZrC–TiC coating exhibited the improved ablation resistance under 25.5 MW/m2 heat flux. The continuous and integral ZrO2–SiO2 scale provided protective effect for the ZrC–SiC coating. A liquid ZrO2–TiO2 layer which owned self‐healing ability was formed for the ZrC–TiC coating in both heat fluxes. However, the state of the formed liquid, like amount, viscosity, evaporation, and decomposition, was influenced by the environment and was vital for the ablation resistance. This work might give a clue for designing ultrahigh‐temperature ceramics as potential laser ablation–resistant coating materials.

Investigation on the Wear Properties of Ti/TiC/TiN Composite Coatings Prepared by Powder Cored Wires Through TIG Method at Nitrogen Atmosphere on Titanium Substrate

In this present study, Tungsten Inert Gas (TIG) welding and powder filled cored wires with nitrogen shielding gas were utilized to produce TiC and TiN surface composite coatings on the titanium (Ti) sheet substrate. The TIG procedure was done at same welding parameters for all of prepared samples. Phase analysis and microstructures were done by X-ray Diffraction (XRD), Energy-Dispersive X-ray Spectroscopy (EDS), Optical Microscopy (OM) and Scanning Electron Microscopy (SEM). The obtained results from XRD and EDS demonstrated that the presence of crystalline phases of TiC, TiN and Ti. SEM and OM exhibited formation of the spherical and dendritic TiC particles in a martensitic matrix and also, TiN pinhole areas with rough and collapsed arms. Maximum microhardness value obtained was 571 HV in the case of sample treated with TiC cored wire at 95%argon+5% nitrogen atmosphere. The Pin-on-disk wear tests showed that the coating with maximum hardness had a higher wear resistance due to the presence of fine and hard TiC particles in the high-impact toughness titanium alloy with uniform distribution.

Effects of Doping of Composite Ti–TiC Coatings with Transition and Valve Metals on Their Structure and Mechanical Properties

This study presents the results of an examination of the mechanical properties and structure of wear-resistant composite Ti–TiC-based coatings, which were formed on commercially pure titanium by electric-arc processing in an aqueous electrolyte, with transition and valve metals (Al, Ni, Cr, and Si) introduced into their composition. This study demonstrated that the change in mechanical properties can be attributed to the formation of the martensitic phase at the titanium–TiC interface, which is induced by hardening phenomena associated with electric-arc processing.