TiN Ceramics Research Articles

Forming a disordered atomic layer to bond TiN or AlN ceramic with Sn[sbnd]9Zn metal under ultrasonication

A disordered atomic layer instead of traditional intermetallic compounds is formed in the bonding interface of ceramic and metal in the metallization of ceramics under ultrasonication. A deep understanding of the bonding mechanism between poor-wetted ceramics and low-temperature metals remains limited with regard to high metallization efficiency and nanoscale bonding structure. In this work, the metallization of AlN and TiN ceramics was realized using Sn9Zn metal with the aid of ultrasonication. The microstructure, energy, and element sources of the ceramic/metal interface were analyzed. Results show that a nanoscale amorphous layer is formed between the ceramics and the metal, and this layer can bond easily with AlN or TiN and Sn9Zn because of the irregular arrangement of its atoms. Some dispersed nanocrystals are also present in the amorphous bonding layer. The thermal effect of ultrasonic cavitation produces a high temperature above 106 K, which provides the energy for the bonding of AlN or TiN with Sn9Zn. O and Zn accumulate in the Sn-9Zn/AlN bonding layer. Zn originates from Sn9Zn. O could be from the O2 dissolved in the liquid solder or the O2 adhering to the ceramic. A small amount of AlN decomposes because of its high ΔG of decomposition. However, TiN decomposes into Ti and N2 under the extreme condition caused by ultrasonic cavitation. The accumulated Ti in the Sn-9Zn/TiN bonding layer originates from TiN. The source of the accumulated O is the same as that of Sn-9Zn/AlN bonding layer.

Microstructure and Mechanical Properties of Magnetron Sputtering TiN-Ni Nanocrystalline Composite Films

In this paper, TiN-Ni nanostructured composite films with different Ni contents are prepared using the magnetron sputtering method. The composition, microstructure, and mechanical properties of composite films are analyzed using an X-ray energy spectrometer (EDS), a scanning electron microscope (SEM), X-ray diffraction technology (XRD), a transmission electron microscope (TEM), and nanoindentation. All the films grow in a columnar crystal structure. There are only TiN diffraction peaks in the XRD spectrum, and no diffraction peaks of Ni and its compounds are observed. The addition of the Ni element disrupts the integrity of TiN lattice growth, resulting in a decrease in the grain size from 60 nm in TiN to 25 nm at 20.6% Ni. The film with a Ni content of 12.4 at.% forms a nanocomposite structure in which the nanocrystalline TiN phase (nc-TiN) is surrounded by the amorphous Ni (a-Ni) phase. The formation of nc-TiN/a-Ni nanocomposite structures relies on the good wettability of Ni on TiN ceramics. The hardness and elastic modulus of the film gradually decrease with the increase in Ni content, but the toughness is improved. The hardness and elastic modulus decrease from 19.9 GPa and 239.5 GPa for TiN film to 15.4 GPa and 223 GPa at 20.6 at.% Ni film, respectively, while the fracture toughness increases from 1.5 MPa·m1/2 to 2.0 MPa·m1/2. The soft and ductile Ni phase enriched at the TiN grain boundaries hinders the propagation of cracks in the TiN phase, resulting in a significant increase in the film’s toughness. The research results of this paper provide support for the design of TiN-Ni films with high strength and toughness and the understanding of the formation mechanism of nanocomposite structures.

A simple procedure for accurately assessing the stoichiometry and structural disorder of TiN ceramics by X-ray diffractometry

Accurately assessing the stoichiometry and structural disorder of TiN ceramics is very important for understanding their properties, but is often not done because it requires complex Rietveld refinements of the corresponding X-ray diffraction (XRD) patterns. As an alternative, a simple procedure is developed here that allows such information to be extracted from the XRD patterns without Rietveld refinements. For this purpose, the stability ranges of super-stoichiometric and sub-stoichiometric TiN are first determined theoretically mathematically from the general principles of Wyckoff position occupation and electrical charge neutrality, and then constrained by theoretical thermodynamic calculations of the Gibbs potential. Subsequently, theoretical simulations of the XRD patterns of a large set of super-stoichiometric and sub-stoichiometric TiN ceramics in their stability ranges are used to reveal the existence of linear relationships between the stoichiometry and the intensity ratio of the hkl peak to the 200 peak (i.e., Ihkl/200 (%) with hkl being 111, 220, 311, 222, 400, and 331), which is then exploited to formulate an analytical model that easily assesses the stoichiometry and structural disorder of TiN ceramics from I111/200 (%). Finally, as an experimental validation and example of application, the stoichiometry of a TiN ceramic fabricated by spark plasma sintering is experimentally evaluated using both the Rietveld method and the proposed model showing marked agreement between their results.

Phase composition, microstructure, electrical and thermal properties of TiN and Yb2O3-Sm2O3 doped AlN ceramics

The phase composition, microstructure, electrical and thermal properties of hot-pressed AlN-2 wt% Yb2O3-4 wt% Sm2O3-x wt% TiN (x = 0, 0.4, 0.8, 1, 2, 3, 4) ceramics were systematically investigated. Yb2O3 and Sm2O3 were used to react with Al2O3 in AlN to form Yb3Al5O12, SmAlO3 and SmAl11O18, which made the samples densely sintered. When sintered at higher than 1700 °C, the electrical resistivity of AlN ceramics with 2 wt% Yb2O3-4 wt% Sm2O3 decreased significantly to 1010 Ω·cm. This decrease in resistivity was probably caused by the continuity of the secondary phase, which encasing the AlN grains and deteriorating the thermal conductivity. When sintered at 1650 °C, the addition of 0.4–4.0 wt% TiN reduces the electrical resistivity from 8.9 × 1012 to 2 × 1010 Ω·cm while maintaining thermal conductivity at around 90 W/m·K with high compactness. Finally, a series of high performance AlN ceramics, with adjustable electrical/thermal properties, could be obtained for modern semiconductor industry.

Microstructure and excellent performance enhancement of MEA base composites with multi-phase induced by ultrasonic assisted laser technology

The ceramics reinforced medium entropy alloy base composites (MEABCs) were manufactured by ultrasonic vibration (UV) assisted laser cladding (LC) process, which were investigated by scanned electron microscope (SEM), electron backscattered diffraction (EBSD) and transmission electron microscope (TEM). The microstructure of MEABCs was mainly composed of body centered cubic (BCC), intermetallics and TiN ceramics, the fine dendrites were produced under the action of the cavitation and the acoustic flow effects of UV, increasing the dislocation density to promote the low angle grain boundary (LAGBs). The micro-hardness and the wear resistance of the composites were enhanced by the second phase and fine grain strengthening. The diffusion of the elements such as Cr/Ni and the generation of LAGBs contributed to the enhancement of the corrosion resistance of the composites.

Si-containing diamond-like carbon coatings to improve the wear resistance of solid ceramic end mills

The study’s purpose is to determine the rational Si content in the DLC-Si external layer of (CrAlSi)N/DLC-Si coatings deposited on α/β-SiAlON + TiN ceramics. The influence of Si content on physical and mechanical properties of coatings such as microhardness, modulus of elasticity, and friction coefficient, and wear resistance of solid ceramic end mills in machining nickel alloy NiCr20TiAl is determined.

Microstructure and luminescence properties of the high pressure high temperature sintered AlN–TiN ceramics

Composite ceramics of titanium nitride grains incorporated in an aluminium nitride matrix have been synthesized by high pressure high temperature treatment of a mechanical mixture of AlN–TiN (3 mol % TiN) powders. The microstructure of the samples analysed by means of electron beam microanalysis and Raman spectroscopy shows that the formation of cubic AlN in the composite begins near titanium nitride grains. The areas of mixed chemical composition, which can be assigned to the formation of the solid solutions Al1−xTixN, have been observed at the phase interfaces. The luminescence properties of AlN–TiN ceramics have been considered focusing on the choice of high pressure and high temperature treatment conditions. Three main components at 2.0 eV, 2.4 eV and 3.1 eV are revealed in the cathodoluminescence spectra analysed quantitatively. The observed emission originates from the radiative transitions with participation of valence band states, oxygen-vacancy centres (VAl–ON), nitrogen vacancies VN, and shallow donors which form a complex system of energy levels in the bandgap of the wurtzite-type AlN.

Spark plasma sinterability and thermal diffusivity of TiN ceramics with graphene additive

The effects of adding graphene nano-platelets (6 wt%) on the microstructure and thermal diffusivity and conductivity of TiN-based ceramics were investigated. Two samples, a monolithic TiN, and a graphene-added TiN ceramics were fabricated using spark plasma sintering technique at 1900 °C for 7 min under 40 MPa. The microstructure of the polished and fractured surfaces of both samples was analyzed by scanning electron microscopy. Adding graphene resulted in a 2% reduction in the relative density, but led to obtaining a fine-grained microstructure. The consumption of graphene nano-additive during the sintering, through the reduction of surface oxide layers of TiN matrix (TiO2), and consequently, the formation of titanium carbonitride (TiN0·8C0.2) were disclosed by X-ray diffraction analysis. The measurement of the thermal diffusivity was done using the laser flash technique. The TiN–6 wt% graphene sample obtained lower thermal conductivity compared to the monolithic TiN, which can be attributed to the smaller grain size of the graphene-added sample.

Sintering Behavior and Fracture Morphology of NiFe2O4/Nano-TiN Ceramics Synthesized under Argon Atmosphere

NiFe2O4/nano-TiN ceramics were synthesized by a two-step cold-pressing sintering process. Sintering behavior, fracture morphology, mechanical performance and high-temperature conductivity were investigated. The results indicated that besides NiO and NiFe2O4, new Ni3TiO5 and metallic phases (iron and nickel) formed in the sintered samples. TiN accelerated the grain growth along with considerable quantity of micro-pores in the sintered samples. Compared to the un-doped samples, the temperature for the onset of sintering of the NiO-Fe2O3-2.0 wt.% TiN system decreased from 1093 to 985 °C. TiN addition changed the sintering mechanism of the NiO-Fe2O3 from grain boundary diffusion to volume diffusion. TiN additions reduce the apparent sintering activation energy and porosities and improve the density, bending strength, and pyroconductivity. Three-dimensional fracture morphology of the composite ceramics synthesized under argon atmosphere, exhibits self-similarity characteristics and the fractal dimension for NiFe2O4-1.0 wt.% TiN ceramics is 2.0813.

The role of graphite addition on spark plasma sintered titanium nitride

Composites of titanium nitride reinforced with graphite were synthesized using spark plasma sintering at 2000°C. The effects of graphite addition on the microstructure, relative density, and mechanical properties of TiN ceramics matrix were examined. The investigation was performed on TiN powder with varying graphite content (1–5wt.%) for 8h using an energy ball milling equipment. Results show that TiN without and with graphite (TiN+1wt.% graphite) sintered at 2000°C recorded sintered relative density of 96.7% and 97% respectively. Additionally, TiN with 3wt.% graphite had a relative density of 98%. However, the shrinkage of TiN+3wt.% graphite was observed to be the lowest compared to other composites at the same sintering conditions. Microstructural analysis indicates that the grain of titanium nitride in the composite was very fine and continuous. Subsequently, a bimodal particle sizes were observed when 5wt.% graphite was dispersed in TiN. The highest Vickers microhardness of 23.5GPa and fracture toughness of 6.5MPam1/2 were achieved with composites reinforced with 3wt.% graphite at milling period of 8h. The combination of TEM/EDS and HRTEM/FFT show a single pattern of diffraction and consistency in interplanar distance obtained from X-ray diffractometry of the milled sample. There is a clear coherence interface between the phases.

Si3N4–TiN Composites Produced by Hot-Pressing Silicon Nitride and Titanium Powders

Si3N4–TiN ceramic composites have been produced by hot-pressing mixtures of silicon nitride and metallic titanium powders at temperatures from 1600 to 1800°C in a nitrogen atmosphere. We have examined the influence of the concentration and morphology of metallic Ti particles in the starting mixture and synthesis conditions on the microstructure, phase composition, and mechanical strength of the Si3N4–TiN ceramic composites. The results demonstrate that the sintering process ensures complete titanium nitridation, leading to the formation of a nonstoichiometric titanium nitride with the composition TiN0.9. The Si3N4–TiN composites prepared from the mixtures containing 5–30 wt % Ti have densities in the range 3.02–3.41 g/cm3, water absorption from 0.01 to 0.14%, open porosity from 0.03 to 0.44%, and bending strength from 250 to 584 MPa. The Si3N4–TiN ceramics prepared using calcium aluminates as sintering aids consist of dense intergrowths of silicon nitride crystallites, which ensures increased strength of the materials. Moreover, the samples containing 25–30 wt % TiN offer high electrical conductivity.

Laser-induced Si3N4–TiN ceramics degradation

This paper presents the process of degradation of the surface layer of Si3N4−TiN ceramics induced by a pulsed Nd:YAG laser. The dissociation of silicon nitride and titanium nitride in the irradiation zone is turned out to yield in a silicon depletion and so the zone becomes enriched with titanium, which, in turn, leads to the formation of TiSi2. This process of the TiSi2 formation can be considered as a ceramics metallization and its concentration depends on the energy delivered by the laser. The expansion of dissociation/evaporation products through the atmosphere is accompanied by the formation of SiO2 and TiO2, which are then deposited on the substrate as an amorphous film of complex composition.

Electronically conductive porous TiN ceramics with enhanced strength by aqueous gel‐casting

AbstractIn this paper, we report on a study of electronically conductive porous TiN ceramics prepared by aqueous gel‐casting. The effects of solid loading, sintering temperature, and sintering aids on the phase composition, microstructure, and volume fraction of porosity of the prepared porous TiN ceramics are studied. The SEM results show that porosity is uniformly distributed in all of the samples studied. With increasing solid loading and sintering temperature, the volume fraction of porosity decreases slowly. Moreover, the relationship between volume fraction of porosity and mechanical and electrical properties has also been investigated. Our results show that adding Y2O3‐TiO2 as combined sintering aids results in a sharp decrease in the volume fraction of porosity, and the volume fraction range changes from 42%‐60% to 28%‐52%. Moreover, adding sintering aids results in an increase in flexural strength and electrical conductivity with a change in maximum value from 34.6 MPa and 2.3 × 104 S∙m−1 to 101.6 MPa and 5.1 × 104 S∙m−1, respectively.

Microstructure and properties of in-situ TiN reinforced laser cladding CoCr2FeNiTix high-entropy alloy composite coatings

To prolong the service life of agitator blades in Phosphoric acid reactors, the in-situ TiN particles reinforced CoCr2FeNiTix (x = 0, 0.5, 1) high-entropy alloy (HEA) coatings have been successfully fabricated by laser cladding on 904L stainless steels. The microstructures and phase compositions were analyzed by metallurgical microscope (OM), scanning electron microscope (SEM), X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM). The microhardness, wear resistance, and corrosion resistance were measured by microhardness tester, wear and friction machine as well as electrochemical workstation, respectively. The experimental results indicate the phase structures of the coatings are composed of FCC plus TiN and a few Laves phases. The microstructure of the coating is columnar crystal while no Ti elements adding. With the addition of Ti elements, the coating consists of irregular dendritic and granular TiN ceramics as well as a few Laves phases. In the terms of wear resistance, the hardness of the coating containing Ti elements increase significantly. As x = 1, hardness of the coating is more than 3 times higher than substrate, and its wear mass is approximately 1/3 of the substrate. According to the electrochemical polarization curve, the corrosion resistance of the HEA coatings is lower than that of the substrate.

Comparative assessment of coated and uncoated ceramic tools on cutting force components and tool wear in hard turning of AISI H11 steel using Taguchi plan and RMS

This study investigated the cutting performance of coated CC6050 and uncoated CC650 mixed ceramics in hard turning of hardened steel. The cutting performance was mainly evaluated by cutting force components and tool wear. The planning of experiments was based on Taguchi’s L36 orthogonal array. The response surface methodology and analysis of variance were used to check the validity of multiple linear regression models and to determine the significant parameter affecting the cutting force components. Tool wear progressions and, hence, tool life, different tool wear forms and wear mechanisms observed for tools coated with TiN and uncoated mixed ceramics are presented along with the images captured by digital and electron microscope. Experimental observations indicate higher tool life with uncoated ceramic tools, which shows encouraging potential of these tools to hard turning of AISI H11 (50 HRC). Finally, tool performance indices are based on units which characterise machined cutting force components and wear when hard turning.

(Ti0.8Cr0.2)B2–CrB–xTiN composites by pressure-assisted SHS

Explored was the feasibility of preparing (Ti0.8Cr0.2)B2–CrB–TiN ceramics by pressure-assisted SHS from reactive powder compacts containing TiN nanopowder as an inert modifier of product structure. The combustion products obtained under optimized conditions exhibited a uniform structure with a porosity of 1–3% and a Vickers hardness of 22.5 GPa.

Enhanced mechanical properties of TiN-graphene composites rapidly sintered by high-frequency induction heating

The current concern about the TiN focuses on its low fracture toughness below the ductile-brittle transition temperature despite of many attractive properties of TiN. To improve its mechanical properties, the approach generally utilized has been the addition of a second phase to form composites and to make nanostructured materials. In this respect, graphene was evaluated as the reinforcing agent of TiN ceramics using novel sintering method (high-frequency induction heated sintering method). Highly dense nanostructured TiN and TiN-graphene composites were obtained within one min at 1400°C. The effect of graphene on the grain size and the mechanical properties (hardness and fracture toughness) of TiN -graphene composites was evaluated.

Transforming automotive waste into TiN and TiC ceramics

A novel approach to obtain titanium-based ceramic by using the automotive waste as raw material has been investigated. The worldwide automotive waste is growing rapidly every year and its impacts are considered to be an important environmental problem. The alternative environmental friendly methodology is required to recycle Automotive Shredder Residue (ASR) waste. We have studied the production of high value Ti-based ceramic materials from this waste by controlled heat treatment of ASR. Our results show successful reduction of existing TiO2 and production of TiC and TiN from ASR. This waste integrated innovative approach of using ASR as supplementary raw material for producing titanium base ceramic not only will reduce the amount of automotive waste in landfills, but also will produce value added ceramic from waste that decrease the production cost of these high-end ceramic components.

Corrosion of AlN–TiN Ceramics in 3% Nacl Solution

The corrosion behavior of nitride ceramics of different compositions, particularly AlN–TiN, 3AlN–TiN, AlN–3TiN, and Ti2AlN, has been studied in seawater (3% NaCl solution). The methods of potentiodynamic polarization curves as well as X-ray diffraction and Auger spectroscopy are employed. The AlN–TiN samples show the highest corrosion resistance. When anodic polarization of the samples increases to +1.20 V (in relation to their stationary potential –0.22 V), their surface becomes the most passive one, and the samples no more pass into the solution. In case of more positive potentials, very thin protective films form on the samples, representing a two-phase coating consisting of AlOOH and Na4TiO4. Other composite ceramics are not characterized by such exceptional stability: longer regions of active dissolution are observed on the anodic polarization curves for these ceramics. For the samples of comparatively corrosion-resistant 3AlN–TiN ceramics, two-phase corrosion products, AlOOH and Al(OH)3, are formed. The AlN–TiN ceramic composite is recommended as the most corrosion-resistant material for seawater applications.

Dependence of physical, mechanical, and structural properties of TiN ceramics on temperature of spark plasma sintering

In this work the dependence of physicomechanical properties of titanium nitride ceramics on the temperature of the spark plasma sintering process is discussed. We study the behavior of the sintering process and find densification variances throughout the whole sintering process. The microstructure of the ceramics is studied and mechanisms of changes in grain structure depending on the sintering temperature are determined. The dependence of hardness of sintered material on sintering temperature is studied, and ceramics with a hardness of 17 GPa are obtained.