Effect Of Plasma Nitriding Research Articles

Effect of plasma nitriding on microstructure and wear behavior of electrodeposited FeCoNiCr coating

An (FeCoNiCr)N high-entropy alloy coating with a single FCC phase was fabricated on 304 stainless steel by electrodeposition and plasma nitriding. The results indicated that the FeCoNiCr coating exhibited typical granular morphologies and a nearly equiatomic ratio of four elemental compositions. After nitriding, the coating primarily consisted of a high-entropy solid solution phase and a CrN phase, with the microstructure of the (FeCoNiCr)N coating being significantly refined due to the effect of crystallization. The microhardness of the (FeCoNiCr)N coating was 781.30 ± 20.3 HV0.5, considerably higher than that of the FeCoNiCr coating, which was 496.48 ± 21.82 HV0.5. Additionally, the (FeCoNiCr)N coating demonstrated a low friction coefficient and a wear rate of 0.59 and 6.8 × 10−8 mm3/N mm, respectively. The fine microstructure and high resistance to plastic deformation, attributed to solid solution strengthening and dispersion strengthening, were the primary factors contributing to the excellent wear performance of the (FeCoNiCr)N coating.

Improving stress corrosion resistance and wear resistance of austenitic hot-stamping die steels via synergistic effects of shot peening and plasma nitriding

In this work, the effects of plasma nitriding, shot peening and their combination on the high-temperature wear resistance and stress corrosion resistance of an austenitic hot-stamping die steel were investigated. The results showed that the nitrided layer consisted of a single expanded austenite after nitriding at 560 °C for 4 h. Shot-peening pretreatment improved the surface hardness and depth of nitrided layer by 29.4 % and 36.4 % compared with the nitrided-only samples. This could be attributed to an increase in dislocation density, sub-crystal refinement, precipitation of nanoscale carbides and high strain of carbides and slip bands. Nitriding increased the stress corrosion resistance and high-temperature wear resistance of materials. Samples nitrided after shot peening showed the greatest wear and corrosion resistance. Besides, the introduction of residual compressive stresses in the nitrided layer by shot peening also improved wear and corrosion resistance to some extent.

Effect of Plasma Nitriding and Sensitization on the Microstructure and Microhardness of AISI 304 Austenitic Steel

Effect of Plasma Nitriding and Sensitization on the Microstructure and Microhardness of AISI 304 Austenitic Steel

Effect of Plasma Nitriding and Oxidation on the Corrosion Resistance of 304 Stainless Steel in LiBr/H2O and CaCl2-LiBr-LiNO3-H2O Mixtures

The effect of plasma nitriding and oxidation on the corrosion resistance of AISI 304 type stainless steel in LiBr/H2O and CaCl2-LiBr-LiNO3-H2O mixtures at 80 °C has been evaluated by using potentiodynamic polarization curves and electrochemical impedance spectroscopy techniques (EIS). Steel was plasma treated at 500 °C during 8 h under different atmospheres, nominally 20% N2 + 80% H2, 100% N2 and 100% O2. X-ray diffraction analysis (XRD) showed the presence of a CrN layer in nitrided specimens, whereas scanning electronic microscopy analysis revealed that specimen treated in the 20% N2 + 80% H2 atmosphere showed the thickest nitride layer. Specimens nitrided in the 20% N2 + 80% H2 atmosphere had the noblest open circuit potential value in both solutions, whereas potentiodynamic polarization curves indicated the formation of a passive layer. These specimens exhibited the lowest corrosion and passivation current density values. Corrosion process was under charge transfer control in both solutions regardless of the plasma treatment. The type of corrosion suffered by the steel under all treatments was the pitting type of corrosion. Pits density was the lowest for nitrides steels rather than that for untreated or pre-oxidized ones.

Plasma Nitridation Effect on β-Ga2O3 Semiconductors

The electrical and optoelectronic performance of semiconductor devices are mainly affected by the presence of defects or crystal imperfections in the semiconductor. Oxygen vacancies are one of the most common defects and are known to serve as electron trap sites whose energy levels are below the conduction band (CB) edge for metal oxide semiconductors, including β-Ga2O3. In this study, the effects of plasma nitridation (PN) on polycrystalline β-Ga2O3 thin films are discussed. In detail, the electrical and optical properties of polycrystalline β-Ga2O3 thin films are compared at different PN treatment times. The results show that PN treatment on polycrystalline β-Ga2O3 thin films effectively diminish the electron trap sites. This PN treatment technology could improve the device performance of both electronics and optoelectronics.

Effect of Plasma Nitriding on Structure and Properties of Titanium Grade 2 Produced by Direct Metal Laser Sintering

AbstractThis article presents the effect of an Indirect Plasma Nitriding process on the microstructure and properties of Titanium Grade- 2 samples manufactured by Direct Metal Laser Sintering Method (DMLS). It was determined, based on morphological analysis that the physical and chemical phenomena occurring at the surface during nitriding has a decisive effect on surface roughening. Phase and stress analysis shown the nitrided layer produced in a pure nitrogen at 760 °C and containing TiN + TiN0.30 + Ti2N is under compressive stress and its characteristic of a high hardness and Young Modulus as compare to Grade 2 titanium samples produced only by DMLS technique (without nitriding). Static tensile stress carried out at room temperature show that the nitrided samples containing TiN + TiN0.30 + Ti2N have much lower yield (YS0.2) and tensile strength (UTS) compared to the not nitrided samples. Tests carried out in Ringer’s solution, using impedance and potentiodynamic methods at temperatures elevated to 36.6 ± 0.3 °C to simulate human-’s’ body temperature, show that nitriding increased corrosion resistance of the alloy.

Effects of plasma nitriding in the corrosion behavior of an AISI 4140 steel using a seawater medium solution

In this work, a comprehensive analysis was performed to characterize the corrosion response of untreated and nitrided AISI 4140 steel. Samples were plasma nitrided at low temperature (∼400 °C) with two different gas composition. Electrochemical impedance spectroscopy, potentiodynamic polarization in artificial seawater solution at room temperature test were performed. Nitrided samples increases hardness on surface compared to the untreated sample. Nitrided samples composed by a mixture of ε-Fe2-3N and γ′-Fe4N nitrides phases offered significant influence on anodic and cathodic polarization. Nyquist curves indicated a higher corrosion resistance of nitrided samples compared to untreated sample.

Effect of plasma nitriding on tribological properties of nickel‑boron-nanodiamond electroless coatings

This study is an effort to investigate the synergic effect of nano-diamond (ND) addition and plasma nitriding (PN) treatment on tribological and structural properties of nickel‑boron (NiB) coatings. NiB/ND nanocomposites containing different amounts of NDs (0.0, 0.1, 0.5, and 1.0 g/L) were produced in an electroless bath. Then, plasma nitriding was conducted on the samples for 1 h at 400 °C in an N2-H2 environment. To study phase analysis and examine the surface morphology of the samples, X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM) were utilized. The wear behavior and friction were determined under the normal load of 10 N using the pin-on-disk method. The surface roughness, microstructure, and microhardness were also assessed. The results showed that, as the ND concentration increased, the amorphous structure of as-plated (AP) Ni-B transformed to a semi-crystalline one. Moreover, the amorphous structure of the as-deposited NiB/ND coatings changed to a crystalline one after plasma nitriding, which resulted in a higher hardness value. NiB/0.5ND coating showed the highest hardness value (1523 HV0.1) and the highest wear resistance (0.8×10−10 Kg/N.m). The smoothest wear trace with no visible cracks is related to the worn surface of PN NiB/0.5ND sample, suggesting that the NiB/ND nanocomposite can be a promising candidate for surface engineering processes.

Effect of plasma nitriding of austenitic stainless steel produced by direct metal laser sintering

A special additive manufacturing (AM), called as Direct Metal Laser Sintering (DMLS), is a technology that produces 3D workpieces using a wide range of different metals as raw materials. The aim of current research is to investigate the plasma nitriding effect on the DMLS produced samples. The direct current plasma nitriding treatment was achieved at 440 °C for 4 hours with 75%N2 – 25%H2 gas mixture. Before the treatment, the 316L austenitic stainless steels samples were ground with different methods to modify the surface roughness. Scanning electron microscope (SEM), X-ray diffractometer, glow discharge optical electron spectroscopy, Vickers microhardness tester and potentiodynamic corrosion test were used for the characterization of surface properties. The results demonstrated that the surface roughness did not affect the outcome of the plasma nitriding, but the corrosion resistance increases with the decrease of the surface roughness compared to the untreated 3D sample.

Improvement Corrosion Behaviour of Lean Duplex Stainless Steel 2101 alloy in Ringer solution by Plasma Nitriding for Biomedical applications

“Plasma nitriding” is a surface hardening process that involves diffusion of the atoms of nitrogen onto the surface of metal under different plasma nitriding conditions. The new alloys used in the field of Biomedical applications are Lean Duplex Stainless Steel. The alloys of Lean DSS are corrosion resistant, lightweight, and have good mechanical properties such as fatigue strength, but in aggressive environments, they lack “wear resistance”. In a vacuum chamber of air (3 mbar), 400 V, and 30 mA, a lean duplex stainless steel (2101) alloy rod was plasma nitrided. The procedure of plasma nitriding was carried out at various times. The effect of plasma nitriding at different times (5, 10, 15, 20, 25) hrs on the chemical structure of LDX 2101 DSS alloy and the form of phases was investigated using OM, FESEM with EDS, XRD, and antibacterial test, tafel potential polarizaton and cyclic polarization for Orthopedic application. The results show that layers and phases S, Fe3N, and Fe2-3N were formed on the alloy’s surface, which would improve mechanical properties and corrosion resistance in Ringer solution at 37 °C.

Effect of plasma nitriding on high‐cycle fatigue properties and fracture behaviors of GJS700 nodular cast iron under cyclic bending loading

AbstractIn this article, the influence of plasma nitriding on the fatigue behavior and fracture mechanisms of the GJS700 nodular cast iron has been investigated. Factors contributing to this influence, which included the microstructure, the phase detection, the surface roughness, and the hardness of the plasma‐nitrided specimens were discussed. Moreover, rotating‐bending high‐cycle fatigue testing was also done on standard samples, and then the field‐emission scanning electron microscopy was also utilized to find the failure mechanism on fracture surfaces. Obtained results demonstrated that the average surface roughness and the Vickers micro‐hardness increased by plasma nitriding, compared to the base material. However, fatigue lifetimes decreased in plasma‐nitrided samples due to the increase in the surface roughness and the formation of a compound layer. On the fracture surface, micro‐cracks, cleavage planes, and fatigue striations were observed. Debonding of the graphite from the matrix in all specimens was a dominant cause of the failure.

Oxidation behavior of 304 stainless steel with modified layer by plasma nitriding in High temperature and pressurized Water

Effects of plasma nitriding on oxidation behavior of 304 SS exposed in 290 °C high temperature and pressurized water have been investigated. The oxidation behavior of 304 SS with plasma nitriding was changed significantly after the exposure tests. Moreover, the nitriding time also had an obvious effect on the oxidation behavior. The difference in oxidation behavior was mainly due to the changes of pH value on the local area near the nitriding layer caused by the formation and hydrolysis of NH4+. The influencing mechanisms of the nitriding time on oxidation behavior in high temperature and pressurized water are also discussed.

Effect of nitriding pre‐treatment on the tribocorrosion behavior of physical vapor deposition‐coated tool steel

AbstractCr‐Al‐Ti‐B‐N hard coating is deposited onto the AISI D2 cold‐worked tool steel by means of a hybrid physical vapor deposition (PVD) technique. The effect of plasma nitriding pre‐treatment on the tribocorrosion behavior of the hard‐coated tool steel is investigated using a ball‐on‐disc sliding wear tribometer equipped with an electrochemical testing set up. Tribocorrosive characteristics are analyzed by optical and scanning electron microscopy, 3D surface profilometry, and open circuit potential (OCP) measurement. The coefficient of friction and OCP varies depending on the degree of damage to the hard coating, such that the point at which the substrate is first exposed can be identified by these measurements. The plasma nitriding pretreatment increases the surface hardness significantly and, therefore, the adhesion of the PVD hard coating to the substrate material. As a consequence, the material's wear resistance is enhanced and its durability against tribocorrosion is improved.

Effects of plasma nitriding and nitrocarburizing thermochemical treatments and surface texture on surface damage evolution of hot stamping punches

Surface texture of stamping tools affects the performance of the tool, tool life, and surface quality of the stamped product. In this work, punch samples were machined after heat treatment by milling and turning strategies in super finish processes and part of the punches were submitted either to plasma nitriding or nitrocarburizing treatment before the experiments using hot stamping of washers, which were made in two stages. Based on roughness results, for non-treated punches, most of the milled punches presented more intense surface damage than turned punches after hot stamping process, possibly due to the marks left by machining processes, affecting mechanical obstacles to wear evolution and lubricant retention on punch surface. For nitrided punches, surface damage was less intense than it was on non-treated punches. Parallel contours strategy and turning upward strategy presented less intense surface damage after the hot stamping process. For nitrocarburized punches, surface damage was less intense than it was to non-treated punches, mainly for milling strategies. SEM images of nitrided and nitrocarburized punches suggested alveolar corrosion occurrence during hot stamping process for circular upward strategy.

Effect of plasma nitriding at low temperature on the corrosion resistance and conductivity of 2205 duplex stainless steel

ABSTRACT A nitrogen expanded austenite (γN) layer with a thickness of 3 μm was prepared by plasma nitriding of 2205 duplex stainless steel (DSS) at 460°C for 1 h with hollow cathode discharge assistance. The microstructure and phase composition of nitrided specimens were examined. The electrical conductivity of nitrided samples was measured before and after the corrosion test, respectively. The corrosion current density of nitrided 2205 DSS polarized for 4 h was 1.3 μA cm−2 (at 0.6 V) and −1.4 μA cm−2 (at −0.1 V), respectively. The interfacial contact resistance (ICR) of the nitrided 2205 was 14.7 mΩ cm2 which was much lower than that of bare 2205 DSS substrate (93.6 mΩ cm2) after 4 h potentiostatic polarization at cathodic conditions. The corrosion resistance and electrical conductivity were evidently improved compared with 2205 DSS substrate.

Effects of plasma nitriding on low alloy Cr-Mo-V steel

Abstract In this study the effects on resistance to corrosion of a low alloy steel after plasma nitriding has been reported. Nitriding was performed at a low temperature of 450 °C and also at 520 °C for the same duration of 10 h in the plasma of nitrogen and hydrogen (80:20) gas mixture. Sample holder was biased at −250 V and the working pressure was kept at around 500 Pa. After nitriding the steel samples along with the bare steel were exposed to X-ray diffraction (XRD) to understand the phase formation. For the assessment of corrosion resistance properties potentiodynamic polarization tests of the bare and plasma nitrided steels in 3.5% NaCl electrolyte were performed. Nitriding at 520 °C had shown the best corrosion resistance. However, broad passivation region had been shown after nitriding at 450 °C.

Corrosion Behavior Evaluation in Simulated Body Fluid of a Modified Ti–6Al–4V Alloy by DC Glow Plasma Nitriding

DC glow discharge plasma nitriding is the process of surface hardening through the spread of nitrogen atoms to the metal surface under special conditions of the plasma nitriding. Titanium and titanium alloys are the most common alloys used in medical applications. Titanium and its alloys are lightweight, corrosion resistant, and have good fatigue properties but lack wear resistance under aggressive environments. The plasma nitriding process was used for a titanium alloy (Ti–6Al–4V) rod with different parameters at a vacuum chamber of air (2 mbar), 680 volts and 30 mA. The plasma nitriding process was performed at different nitriding times (5, 10, and 15 h), and the effect of plasma nitriding was examined on the chemical compassion of Ti–6Al–4V alloy and the appearance of phases was studied by optical microscopy (OM), scanning electron microscopy and field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), Tafel potential polarization, and cyclic polarization. The results indicate that the formation of layers and phases Ti2N and Ti2N3−x on a surface of the alloy were achieved, which would improve the surface characteristics of chemical corrosion in simulated body fluid.

Effect of plasma nitriding and modulation structure on the adhesion and corrosion resistance of CrN/Cr2O3 coatings

This paper examines the corrosion resistance of high-speed steel (HSS) substrates subjected to plasma-nitriding (PN) before being coated with CrN (in a single layer) or CrN/Cr2O3 (in multiple layers). Low-temperature (∼300 °C) nitriding treatment was applied for various durations (1 h, 3 h, and 5 h) with the aim of maximizing the adhesion strength and corrosion resistance of the HSS substrate. The multilayer coatings were applied in various thickness ratios of CrN vs Cr2O3 using high-power impulse magnetron sputtering (HiPIMS). The purpose of this study was to investigate the influence of plasma nitriding and Cr-based coating layers on the microstructural characteristics as well as the adhesion and corrosion characteristics. Specimens that underwent PN treatment for 5 h presented Lc1 and Lc2 values of 40.2 N and 78.9 N, respectively. The adhesion strength of the CrN/Cr2O3 multilayer coated PN-HSS substrate (PN-5h) (Lc 1 = 93.8 N) greatly exceeded that of the CrN-coated specimens. These results demonstrate that plasma nitriding and the modulation period strongly affect the adhesion strength between Cr-based coatings and the underlying HSS substrate. Corrosion resistance was characterized in terms of corrosion current, as follows: CrN/Cr2O3 multilayer > CrN layer > base-HSS. These findings also demonstrate that the application of a CrN/Cr2O3 multilayer coating can greatly enhance the corrosion resistance of HSS.

Glow discharge plasma nitriding of low alloy steel

Abstract Present study concerns with the effect of plasma nitriding on hardness of low alloy steel. Plasma nitriding had been performed at elevated temperature of 500 °C which improved the hardness to ∼1200 Hv. The case depth was found to be ∼80 µm. With the variation of time the case depth also varied. The plot of the square of the case depth vs. nitriding time and the corresponding line drawn by a linear regression and extrapolation passes almost through the origin. From the plot the nitrogen diffusion co-efficient calculated to be ∼2.23 × 10−13 m2/s. The structural and morphological studies have been made by following the X-ray diffraction (XRD) and scanning electron microscopic (SEM) and EDS analyses. XRD revealed the presence of α-Fe, γ′ and e phases.

Effects of plasma nitriding on tempered steel

Conventional plasma nitriding is highly widespread in the industry, but it has essential problems such as edge effect and hollow cathode effect. These problems induced the development of active screen plasma nitriding (ASPN) where the plasma forms on the active screen instead of the sample, which is completely insulated. However, this arrangement does not work with large furnaces, so the usage of bias voltage is necessary in industrial circumstances. In this experiment, the effects of different biases were examined, specifically the hardness, layer thickness, formed phases and the diffusion of nitrogen. In conclusion, the 20 % bias had the best effects on the sample with the defined nitriding parameters in this research.