Si3N4 TiN Research Articles

SURFACE MORPHOLOGY OF SILICON NITRIDE (Si3N4)-TITANIUM NITRIDE (TiN) COMPOSITES USING GRA-RSM STRATEGY ENCOMPASSED WITH EDMed PARAMETERS

This investigation explores the application of electrical discharge machining (EDM) to ceramic composites constructed from Si3N4–TiN (Syalon 501) by testing both square and cylindrical electrodes. Various experimental methods have been employed, including design-of-experiments (DoE), Grey relational analysis (GRA), analysis of variance (ANOVA), confirmation testing, and scanning electron microscopy (SEM), in an effort to optimize machining settings and comprehend their effect on performance. While ANOVA revealed crucial parameter levels influencing overall machining conditions as measured by the grey relational grade (GRG), the sophisticated method of GRA considerably improved the machining characteristics. Significant improvements in the EDM process were shown experimentally, resulting in outstanding results for material removal rate (MRR), surface roughness (SR), and electrode wear rate (EWR). In particular, numerous benefits of the square electrode layout over the more common cylindrical arrangement stood out. All of the aforementioned resulted in an impressively high MRR (measured at 0.0281[Formula: see text]gm/min), a low EWR (at 0.0020[Formula: see text]gm/min), and a significant improvement in SR (at 0.3150[Formula: see text][Formula: see text]m). The GRG value was 0.0163 for the square electrode design, which was excellent, and 0.0025 for the cylindrical electrode, which was significantly better. The optimized parameters were successfully used, especially with the square electrode arrangement, leading to significant improvements in MRR and decreases in EWR. On the other hand, surface quality was negatively affected by larger parameter values, which increased the development of microfractures, particularly when using the square electrode design. In any case, our study provides strong proof that adjusted settings can greatly improve EDM performance, allowing for accurate machining of Si3N4–TiN composites with increased MRR, great surface texture, and reduced electrode wear. In conclusion, our study provides useful information to improve EDM procedures for Si3N4–TiN ceramic composites, as well as practical insights into increasing the efficiency and quality of EDM operations in a variety of industrial sectors.

Preparation of Si3N4–TiN–SiC composite by partial substitution of Ti–Si–Fe alloy for Si under N2 atmosphere

Preparation of Si3N4–TiN–SiC composite by partial substitution of Ti–Si–Fe alloy for Si under N2 atmosphere

Microstructure and mechanical properties of electroless Ni–P–Si3N4–TiN composite coatings

A high performance electroless Ni–P–Si3N4–TiN multi-nanocomposite coating was prepared on the surface of AZ31 Mg alloy. The results showed that the surface morphology of this multi-nanocomposite coating exhibits a uniform nodular structure, and the nodular size decreases clearly while increasing TiN nanoparticle concentrations to 2 g/L in the bath, resulting in the finest size of approximately 3 μm. Furthermore, the incorporation of TiN nanoparticles and Si3N4 nanowires into the Ni–P matrix can significantly enhance the microhardness and reduce the friction coefficient of the multi-nanocomposite coatings. The maximum hardness value of 921.4 HV200 and lowest friction coefficient of 0.54 as well as minimum wear weight loss of 0.7 mg can be also reached at a TiN nanoparticle concentration of 2 g/L.

Electroconductive silicon nitride-titanium nitride ceramic substrates for CVD diamond electrode deposition

The present investigation was carried out to develop dense ceramics of silicon nitride-titanium nitride (Si3N4–TiN) with low electrical resistivity and excellent mechanical properties. The objective was to employ these ceramics as substrates of conductive diamond electrodes produced by chemical vapor deposition (CVD) for electrochemical applications. TiN powder was added to a Si3N4 matrix powder composition at varying volume fractions (21–30%). Disc-shaped samples were fabricated by mixing and pressing the powders, followed by pressureless sintering. The crystalline phase composition and microstructure were analyzed using X-ray diffraction and scanning electron microscopy, while the electrical resistivity was measured with a four-point probe configuration. The composites transitioned from insulating to conductive behavior between 23 and 27%vol TiN. The developed compositions displayed superior hardness, fracture toughness, elastic modulus, and thermal conductivity compared to the Si3N4 matrix. Notably, the composition containing 30%vol TiN displayed noteworthy properties, including a hardness value of 16.1 GPa, fracture toughness of 7.0 MPa m1/2, and electrical resistivity of 8.9 × 10−1 Ω cm. Finally, the proof-of-concept experiment demonstrated the potential of Si3N4–TiN composites as robust and electroconductive substrates for depositing conductive diamond electrodes. This was achieved by successfully depositing conductive diamond films on Si3N4–TiN substrates using the Hot Filament Chemical Vapor Deposition (HFCVD) technique.

Surface morphology and drilled hole accuracy of conductive ceramic composites Si3N4–TiN and MoSi2–SiC on EDMed surfaces

Electro-discharge machining (EDM) was employed to cut conductive ceramic composites consisting of Silicon Nitride-Titanium Nitride (Si3N4–TiN) and intermetallic ceramic composite (MoSi2–SiC), with the geometrical properties of the machined hole and the measurement of performance metrics of essential concern in the EDM process being recorded. Machining characteristics including current, spark on time, spark off time, and dielectric pressure are compared for both conductive ceramic composites. For multiple responses to geometrical errors such circularity, cylindricity and perpendicularity, as well as to performance metrics like metal removal rate (MRR), electrode wear ratio (EWR), machining time and workpiece and electrode surface integrity, spark gap time is preferable. The experimental runs to determine the optimal parameters of Si3N4–TiN and MoSi2–SiC ceramic composite are carried out using Taguchi's L9 OA based on the design of experiments (DOE). SEM with EDAX analysis of the machined surface of both composites allows for in-depth research into the machining process and a comparison of the removal mechanism and surface topography. The surface textures of 9 different holes and electrodes for ceramic composites are analysed by comparing the machined surface of the best hole with the best electrode to the machined surface of the worst hole with the worst electrode. As a consequence, the EDM process seems to be a promising method for manufacturing excellent surfaces in an electrically conductive Si3N4–TiN and MoSi2–SiC composite under the slow process parameters condition of conductive ceramic composites. This was demonstrated by the comparative analysis and establishing that was previously discussed.

Si3N4–TiN conductive ceramic composites: topography on EDMed surfaces and precise drilled holes

In this study, it is challenging to drill a 5 mm hole in a Si3N4–TiN conductive ceramic composite, specifically when attempting to identify an association between EDM machining inputs such as current, pulse on-time, pulse off-time, dielectric pressure and spark gap and performance parameters like as Material Removal Rate, Electrode Wear Rate, Average Surface Roughness, and geometrical tolerances such as Cylindricity, Circularity and perpendicularity. The study examines the surface deformations of a composite comprising EDAX report, machined electrode and molybdenum wire following WEDM machining. Current of 5A, Pulse on-time of 9µs, Pulse off-time of 7µs, spark gap of 0.15 mm, dielectric pressure of 21.0 kg/cm2, material removal rate of 0.004214 g/min, electrode wear rate of 0.000245 g/min and surface roughness of 0.349 µm were found to be optimal. The experimental findings show that good surface finish may be attained on a copper electrode-machined surface, along with improved machining accuracy, closer geometrical tolerances and lesser anomalies.

Comparative Study on EDM Parameter Optimization for Adsorbed Si3N4–TiN using TOPSIS and GRA Coupled with TLBO Algorithm

Electrical discharge machining is a thermo-physical-based material removal technique. 25 combinations of process variables were formulated with the aid of Taguchi technique for EDM of adsorbed Si3N4–TiN. Machining variables like pulse current, pulse-on time, pulse-off time, dielectric pressure, and spark gap voltage varied, and impact of each variables on the performance metrics (MRR, EWR, SR, ROC, θ, CIR, and CYL) was assessed. MCDM strategies like grey relational analysis and TOPSIS are utilized to find out the ideal arrangement of machining parameters to achieve most acute productivity of the multitude of reactions. Likewise, metaheuristic algorithm in particular GRA combined with teaching-learning-based optimization algorithm is utilized for getting global optimized input factors. Important factors like pulse current, pulse-on time, and spark gap voltage characteristically affect the outputs. It is recognized that the pulse-on time and the pulse current are the most significant input factors than others. The ideal machining parameters in view of GRA and TOPSIS techniques for acquiring better output factors are I, 12 amps; PON, 7 μsec; POFF, 4 μsec; DP, 12 kg/cm2; and SV, 36 volts.

Tribological Properties of ZrN–Si3N4–TiN Composites Consolidated by Spark Plasma Sintering

Tribological Properties of ZrN–Si3N4–TiN Composites Consolidated by Spark Plasma Sintering

Experimental investigation on EDM of Si3N4–TiN using grey relational analysis coupled with teaching-learning-based optimization algorithm

Electric discharge machining of silicon nitride–titanium nitride (Si3N4–TiN) ceramic composites was conceded for making square and circular profiles. Five imperative machining parameters namely current, pulse-on time, pulse-off time, dielectric pressure and spark gap voltage have been contemplated to resolve the response characteristics like material removal rate, electrode wear rate, surface roughness and geometrical tolerances. Multi Criteria Decision Making techniques like GRA and Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) are used to discover the optimal set of machining parameter combinations to accomplish maximum efficiency of all the responses. Also, Metaheuristic or nature inspired algorithm namely GRA coupled with TLBO algorithm is engaged for obtaining global optimum parameters. The parameters like the current, pulse-on time and spark gap voltage have the indicative impact on the responses like MRR, EWR and geometrical tolerances. It is acknowledged that the current and pulse-on time are most significant parameters among others. The optimal EDM parameters based on GRA and TOPSIS methods for obtaining better responses are current - 10 amps; pulse-on time - 8 μsec; pulse-off time - 4 μsec; dielectric pressure - 20 kg/cm2 and spark gap voltage - 32 V.

Pulse-Type Influence on the Micro-EDM Milling Machinability of Si3N4-TiN Workpieces.

In this paper, the effect of the micro-electro discharge machining (EDM) milling machinability of Si3N4–TiN workpieces was investigated. The material removal rate (MRR) and tool wear rate (TWR) were analyzed in relation to discharge pulse types in order to evaluate how the different pulse shapes impact on such micro-EDM performance indicators. Voltage and current pulse waveforms were acquired during micro-EDM trials, scheduled according to a Design of Experiment (DOE); then, a pulse discrimination algorithm was used to post-process the data off-line and discriminate the pulse types as short, arc, delayed, or normal. The analysis showed that, for the considered process parameter combinations, MRR was sensitive only to normal pulses, while the other pulse types had no remarkable effect on it. On the contrary, TWR was affected by normal pulses, but the occurrence of arcs and delayed pulses induced unexpected improvements in tool wear. Those results suggest that micro-EDM manufacturing of Si3N4–TiN workpiece is relevantly different from the micro-EDM process performed on metal workpieces such as steel. Additionally, the inspection of the Si3N4–TiN micro-EDM surface, performed by SEM and EDS analyses, showed the presence of re-solidified droplets and micro-cracks, which modified the chemical composition and the consequent surface quality of the machined micro-features.

A Multi Criteria Decision Making (MCDM) based on TOPSIS and RSM for process improvement in electrical discharge machining of silicon nitride–titanium nitride ceramic composites

This experiment is an attempt to choose the optimal machining parameters for electrical discharge machining (EDM) of silicon nitride–titanium nitride (Si3N4–TiN) ceramic composites based on MCDM approach. The electrical discharge machining have been conducted according to L21 orthogonal array with preferred input parameters like current (I), spark gap voltage (SV), pulse-on duration (Ton) and pulse-off duration (Toff). The response parameters measured are material eradication rate (MRR), electrode eradication rate (EWR) and surface roughness (Ra). The MCDM techniques namely Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) and Response Surface Methodology (RSM) are used to find the optimal machining parameters which provide better value of all responses. Also, scanning electron microscopy (SEM) is employed for examining the surface defects like micro-cracks, micro-pores, droplets, surface craters, globules, etc.

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.

Surface integrity, fatigue performance and dry sliding wear behaviour of Si3N4–TiN after wire-electro discharge machining

Silicon nitride–titanium nitride (Si3N4–TiN) ceramic composite was machined by wire-electro discharge machining (WEDM) to characterize the surface integrity and to investigate its effect on fatigue performance. Dry sliding wear behaviour of Si3N4–TiN sliding against EN32 steel was also tested. The polished and machined surfaces were examined for finding the hardness. The wire-EDM cut surface was examined with scanning electron microscope (SEM) for obtaining its microstructure. The wire-EDM of silicon nitride–titanium nitride produced a rough recast surface with different types of defects like micro-cracks, micro-pores, globules, droplets and surface craters. The material deposition to work specimen after machining was scrutinized by EDAX composition analyzer. The polished surface and wire-EDM cut surface were examined for determining the fatigue performance and it was observed that a deficiency of 25–35% in fatigue life in wire-EDM cut surface than that of the polished surface. Also, the wire-EDM cut surface exerts very high tensile residual stress compared to the polished surface. From the results, it is evident that the polished surface exhibits better surface finish and fatigue life, higher wear resistance and micro-hardness than that of the machined surface.

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.

Densification and Phase Transformation in Multi-Layered Graded Si3N4-TiN Components Produced by Field-Assisted Sintering.

The structural and/or functional design of multiphase ceramics, along with their processing, are timely research topics in the area of field-assisted sintering techniques, such as spark plasma sintering, especially for systems containing both electrically insulating and conductive phases. In the present study, spark plasma sintering of Si3N4–TiN composites was investigated by changing the TiN particle size and electrical current waveform. Their combined effects on both the densification behavior and α-to-β phase conversion of the Si3N4 matrix was studied and compared by means of a thermodynamic approach and dilatometric measurements. Through the control of TiN phase characteristics and heating mode, double-layered Si3N4-based components were also prepared using a one-step spark plasma sintering process, which was compared with conventional hot-pressing. It was shown that the size of the conductive TiN phase has a significant influence on the particle rearrangement, with the formation of a liquid phase, and the solution–diffusion–precipitation process, through the field-induced local heating and electrowetting mechanisms. Moreover, the contribution of current pulsing to the densification and α-to-β conversion of the layered Si3N4-based components was mostly dependent upon the particle size distribution and content of the TiN phase, indicating that the electric-field effect is dependent upon current path.

Toughness Enhancement in TiN/CNTs Reinforced Si3N4 Ceramic Nanocomposites

This paper elucidated the effect of carbon nanotubes (CNTs) and TiN nanoparticles on the mechanical properties of silicon nitride(Si3N4) nanocermic matrix, on their own and together respectively. This was investigated by using the samples fabricated by hot-pressing nano-sized Si3N4 powders, carbon nanotubes and TiN nanoparticles. The addition of each nanostructure caused varying degrees of enhancement of mechanical properties, the incorporation of 2wt.% CNTs along with 10wt.% TiN shows the highest improvements in fracture toughness. Fractography of the samples revealed a mixed intergranular/transgranular fracture mode for reinforced nanocomposites. The toughening mechanism for the Si3N4 nanocomposites reinforced with CNTs and TiN nanoparticles was crack deflection, crack bridging and pull-out of CNTs.

Nitride nanopowders by azide SHS technology

Azide SHS technology with NaN3 powder as a nitriding agent was used to fabricate TiN–BN, AlN–BN, and Si3N4–TiN nanopowders using Nа2TiF6, (NH4)2TiF6, KBF4, NH4BF4, Nа3AlF6, AlF3, Na2SiF6, and (NH4)2SiF6 as precursors. Mixtures of the above salts with sodium azide NaN3 readily burned in an SHS reactor to yield agglomerated nanosized or fine target powders. Phase composition of combustion products not always corresponded to expectations and often contained insoluble byproducts. Reported are optimal green compositions and procedures that afford the preparation of target TiN–BN, AlN–BN, and Si3N4–TiN nanopowders free of byproducts.

Role of surface finishing on the in vitro biological properties of a silicon nitride–titanium nitride (Si3N4–TiN) composite

Silicon nitride (Si3N4) has been introduced clinically as an orthopedic biomaterial for interbody fusion devices and in joint replacements. However, the production of complex shapes through conventional mechanical machining is difficult and expensive and limits interesting applications. Thus, several electrically conductive reinforcements to the Si3N4 matrix, like TiN, have been proposed, generating composites suitable to be wrought by electrical discharge machining (EDM). In this study, Si3N4–TiN with high strength, low density, and good electric conductivity wrought by EDM was studied. The role of surface finishing was investigated comparing the interface generated during the EDM process to that resulting from further polishing. The different topographical features were assessed by electron microscopy, energy dispersive X-ray spectrometry, and profilometry. Surface wettability was also determined based on the measurement of the OCA of water and diiodomethane. The biological responses induced in MC3T3 cells, a widely diffused osteoblast model, were correlated with the surface pattern. The unpolished samples could promote better cell viability, with a more relevant effect on the cytoskeleton arrangement as highlighted by numerous cytoplasmic extensions and filopodia-like structures and the high number of focal adhesions, while MC3T3 cells grown on polished Si3N4–TiN specimens displayed a flat morphology. In addition, the unpolished Si3N4–TiN increased osteocalcin production and calcium deposition. Taken together, these data support the biocompatibility and in vitro osteogenic properties of the electroconductive Si3N4–TiN investigated. Further in vivo studies are required to explore the possible use of bone implants directly obtained by EDM.

Optimization of EDM process parameters in machining Si3N4–TiN conductive ceramic composites to improve form and orientation tolerances

Abstract In this research, investigational and experimental work was carried out on the electric discharge machining (EDM) of a Si 3 N 4 –TiN ceramic composite using a copper electrode as the EDM tool. These composites are used in high-temperature environments, such as in metal forming, extrusion dies, turbine blade and non-ferrous molten metal handling components. The Si 3 N 4 –TiN composite is difficult to machine using conventional machining techniques. However, it can be easily machined using a spark EDM process to obtain accurate dimensional and geometric tolerances. The machining parameters, such as the current ( I ), pulse on time ( T on ), pulse off time ( T off ), dielectric pressure (DP) and spark gap voltage (SV), were investigated using a Taguchi L 25 orthogonal array. The output characteristics, such as the material removal rate (MRR), tool wear rate (TWR), wear ratio (WR), surface roughness (Ra), top radial over cut (ROC Top ), bottom radial over cut (ROC Bottom ), taper angle ( θ ), circularity (CIR), cylindricity (CYL), perpendicularity (PER) and run out (RO), were examined during the sparking operation. The significance of the machining parameters was obtained using analysis of variance (ANOVA) based on grey relational analysis (GRA), which showed that the current, pulse on time and spark gap voltage were the most significant parameters. The results were further confirmed using an experiment that illustrated that the spark eroding process could effectively be improved.

Producing Nanodispersed Composite Nitride Powders by Nitriding of Precursors

Highly dispersed and nanodispersed composite powders based on Si 3 N 4 –TiN, Si 3 N 4 –CrN, BN–AlN, and BN–Si 3 N 4 non-metallic nitrides are produced by nitriding of precursors. The main criteria for selecting precursors for the synthesis of these powders are determined. Features of the processare analyzed for powders of TiSi 2 , CrSi 2 , B 4 Si, and AlB 2 precursors in both mechanically activated and non-activated conditions. It is established that the mechanical activation of precursors substantially decreases the temperature of nitride formation and enables synthesizing nanodispersed composite nitride powders with a particle size of 30–70 nm. In comparison with the specimens produced from the powders synthesized by conventional techniques, the specimens produced by hot pressing and spark plasma sintering possess a highly dispersed microstructure with a uniform distribution of phases and advanced physical and mechanical properties.