Plasma Nitriding Research Articles

Analysis of Physicochemical Properties of W1.8507 Steel Parts with Sharp Edges, Thermochemically Treated by Plasma Nitriding with and without Polarized Screens

The plasma nitriding edge effect phenomenon is characteristic of parts with sharp edges. The intersection for the discharge of negative light of the two adjacent faces causes the apparition of this effect. In some cases, this effect causes disturbance to the general process. In this work, a sample with different angles of 30°, 60°, and 90° was analyzed. The sample was subjected to ion nitriding with and without the cathode grid to highlight the reduction of the edge effect on the non-uniformity appearing on the edges and corners of the parts. The effect of the active screen was also analyzed by hardness measurements in the area of the nitride edges and by SEM and EDX analyses in the mentioned areas. Additionally, the influence of active screens was studied by nanoindentation and scratch tests and by measuring the contact angle of coolants and liquid lubricants on the nitride surfaces with both methods.

Investigation on the effects of pretreatment on the surface characteristics of duplex plasma-treated AISI P20 tool steel

Plasma nitriding (PN) coupled with physical vapor deposition (PVD) has emerged as one of the promising surface treatments to achieve an elevation in the tribological, oxidation resistance, and load-bearing ability of the engineering materials in recent years. However, the consequential impact of heat treatment processes implemented upon the base substrate on enhancing the wear resistance of such materials cannot be disregarded. In the present study, AISI P20 steel samples in as received and heat-treated conditions were selected for the investigation to establish the influence of pretreatment prior to the duplex treatment through microstructural, phase and compositional characterizations carried out by the means of XRD, SEM and EDS analysis followed by surface roughness and microhardness tests. Heat-treated samples were observed to bear higher hardness than the as-received ones, while surface roughness evaluations indicated a reversed behavior. Further, tribological investigations were conducted for an accurate estimation of wear resistance and coefficient of friction of the duplex-coated samples. All the results of the investigations indicated a significant influence of the white compound layer in governing the tribological and mechanical properties of the duplex-coated samples for as received as well as heat-treated samples.

Effect of Pre-treatment and Duration of Pulse Plasma Nitriding on Duplex Plasma Treatment by Physical Vapor Deposition of TiN on AISI D2 Steel

Effect of Pre-treatment and Duration of Pulse Plasma Nitriding on Duplex Plasma Treatment by Physical Vapor Deposition of TiN on AISI D2 Steel

Effects of Plasma Nitriding Process on AISI 304 Stainless Steel

AISI 304 stainless steel is a type of austenitic stainless steel that contains a high percentage of chromium and nickel. It is one of the most widely used grades of stainless steel and is commonly used in a variety of applications, including kitchen equipment, food processing equipment, and chemical processing equipment. AISI 304 stainless steel is a versatile and widely used material due to its excellent corrosion resistance, durability, and non-magnetic properties. Low-temperature processes like ion implantation, plasma nitriding can prevent the corrosion resistance of stainless steels by diffusion of plasma into the surface of the material, forming precipitation of Chromium nitride. For this research work, plasma nitriding is carried out on AISI 304 at low-temperatures 550°C for the time duration of 8 hrs, 16 hrs and 32 hrs. The formation of nitrogen-enriched layers with high nitrogen content promoted to increase in surface hardness. Wear test were carried out with pin on disc machine and the samples were undergone with hardness tests. The microstructures of plasma treated samples were compared with untreated microstructures. It was noted that phase change occurred from austenite to expanded austenite forming a hard layer from the surface level improving the wear resistance of the material.

Study of Surface Modification of Niobium Caused by Nitriding and Cathodic Cage Deposition

In this work, plasma nitriding (PN) and cathode cage plasma deposition (CCPN) treatments were carried out with temperatures of 400 and 450 °C to evaluate the modifications caused on the surface of pure niobium samples. XRD, SEM, Vickers microhardness, and sphere-disk analyses were used to characterize the coatings’ composition, morphology, hardness, and wear resistance. The results showed that the treated samples increased hardness and wear resistance, with the sample submitted to CCPN at 450 °C presenting the best tribological behavior.

Effects of Plasma Nitriding Temperature on the Properties of 1.3207 Type High Speed Steel

Active screen plasma nitriding on HS 10-4-3-10 high-speed steel specimens was performed at three different low nitriding temperatures while trying to keep the other nitriding parameters uniform. In addition, two extra samples were made to increase the treatment time. Optical microscopic investigation and microhardness testing were performed on the segments of the samples, and their qualitative composition was determined by energy-dispersive X-ray spectrometry. Based on the measurements, it is stated that the hardness of the surface can be increased 50% with active screen plasma nitriding.

Fractographic analysis of the AA 7075-T6 alloy subjected to fatigue in the RRA treatment condition and plasma nitride

RESUMO Este trabalho avaliou o comportamento de fratura da liga de alumínio AA7075-T6 submetida a carregamento de fadiga. Ambos os corpos de prova entalhados e não entalhados foram submetidos a um tratamento térmico de retrogression and re-aging (RRA) e nitretação a plasma antes dos ensaios mecânicos. A nitretação a plasma, que tem sido um método escolhido para aumentar a dureza superficial e as resistências à fadiga, desgaste e corrosão de diversas ligas, foi realizada com tela ativa com fonte DC de 20 Hz e ciclo de trabalho de 40 Hz. O tratamento RRA, que é utilizado para aumentar a resistência e a dureza da liga de alumínio AA7075 e obter melhorias nos comportamentos de fadiga e corrosão, foi realizado a 200 °C por 20 minutos com resfriamento a água (resolubilização), seguido de 24 horas a 120 °C (reenvelhecimento). Os ensaios de fadiga axial de corpos de prova entalhados e não entalhados foram realizados com R = 0,1, frequência de 14 Hz, e em nível de tensão de 150 MPa para corpos de prova entalhados e 500 MPa para corpos de prova não entalhados. A fratura por fadiga foi então realizada via estereomicroscopia e microscopia eletrônica de varredura. Para os corpos de prova não entalhados, as condições AA7075-T6 e AA7075-RRA apresentaram características de fratura semelhantes, com boa definição dos três estágios de falha por fadiga; a condição nitretada AA7075 não apresentou evidência de fratura por fadiga típica. Os corpos de prova entalhados apresentaram fractografias semelhantes à condição de concentração de tensão severa, com marcas superficiais convexas à região de nucleação.

Structure of the surface layer of high-chrome steel nitridated in the elion regime in the plasma of a suspended arc discharge with a heated cathode

The purpose of this work is to reveal the patterns of formation of the structure of the surface layer of high-chromium steel subjected to nitriding in a low-pressure gas discharge plasma using a plasma generator with a hot cathode "PINK". Heating of the samples to the nitriding temperature was carried out by the ionic component of the plasma, as well as by the electron and ionic components of the plasma (elion mode). The object of the study was heat-resistant corrosion-resistant steel of the austenitic class grade 20X23H18 (foreign analogue of AISI310S). The relevance of research is due to the relatively low level of hardness and wear resistance of steels of this class. Nitriding of steel was carried out on the TRIO installation, retrofitted with a switching unit for implementing the aelion (electronic and ionic) processing mode. It has been established that the thickness of the hardened layer is (55-60) pm and weakly depends on the method of nitriding, temperature (in the range of 793-873 K), and duration (3-5 hours) of the process. A nitriding regime has been revealed that makes it possible to form a surface layer with a microhardness of 13.7 GPa (ionic heating mode) and 10.8 GPa (elion heating mode). It has been established that the high strength and tribological properties of nitrided steel are due to the formation of a nanocrystalline structure in the surface layer, the main phases of which are iron nitrides Fe4N and chromium nitrides CrN. It is shown that heating the samples to the nitriding temperature in the aelion mode, which uses the electron and ion components of the plasma, leads to a significantly lower level of material roughness compared to the samples heated during nitriding by the ion component of the plasma.

Contribution of thermal dissociation during steel nitriding in electron beam plasma

We report the results of measurements of mass-to-charge ion composition of the beam plasma generated by a forevacuum plasma-cathode electron source in a nitrogen atmosphere during electron beam interaction with the surface of a steel sample. It has been found that as the sample surface temperature increases from 540 ℃ to 930 ℃, the fraction of atomic nitrogen ions in the spectrum increases by 4-10%. This increase in atomic nitrogen occurs at the backdrop of decreasing number of molecular nitrogen monoxide ions and is associated with thermal dissociation of its molecules.

Influence in Fatigue Properties Due a Plasma Nitriding and Laser Carburizing in a Bainitic Steel

Influence in Fatigue Properties Due a Plasma Nitriding and Laser Carburizing in a Bainitic Steel

To determine the effect of plasma nitriding treatment 56 on screw loosening and surface topography of different 78 implant-abutment screw systems with and without thermocycling: An in vitro study.

The aim of this study was to evaluate and compare the effect of plasma nitride-treated abutment screws of two different implant systems on screw loosening and surface topography with and without thermocycling. This was an in-vitro experimental study. Fifty-two abutment screws (Group A: 26 Genesis and Group B: 26 Bredent) underwent plasma nitride treatment and were subdivided into two groups, one without thermocycling and one with thermocycling. Dynamic load was applied and detorque values were evaluated for determining the screw loosening using "independent t-test" with the help of IBM SPSS Statistics 20 and scanning electron microscopy was done to check for surface topography. Inter- and intragroup comparisons were done using independent t-test (SPSS: Statistical Package for the Social Sciences software version 20). Plasma nitriding treatment genesis implant system abutment screw showed more screw loosening (P < 0.05) and surface roughness as compared to bredent with and without thermocycling. From the present study, it was shown that plasma nitride-treated abutment screws decreased the occurrence of screw loosening favoring the bredent implant-abutment system more than the genesis implant-abutment system.

Plasma nitriding of 410S ferritic/martensitic stainless steel: microstructure, wear and corrosion properties

Plasma nitriding of 410S ferritic/martensitic stainless steel: microstructure, wear and corrosion properties

Дослідження залежності мікротвердості модифікованих поверхонь титанових сплавів від глибини насичення азотом при вакуумному іонному плазмовому азотуванні в термоциклічному режимі

A study of titanium alloys with a strengthened nitrided layer by the method of vacuum ion plasma nitriding in thermocyclic mode was carried out to determine the regularity of the effect of diffusion saturation parameters on microhardness. At the same time, the effect of anomalous mass transfer of nitrogen in the surface of the part being processed was used, by creating a field of thermal stresses in the surface layer due to the cyclic inclusion and exclusion of the glow discharge and cyclic temperature changes. Microhardness studies of strengthened surface layers were carried out on metallographic slides using a PMT-3M microhardness meter, the thickness of the nitride layer was controlled using microstructural analysis using a MIM-10 microscope, and the phase composition of the surface layer was monitored using a DRON-3M device. Vacuum ionic nitriding in the thermocyclic regime of titanium alloys allows changing the physical and mechanical characteristics within wide limits (diffusion layer depth up to 500 μm, microhardness up to 9600 MPa, phase composition of nitrided surfaces, etc.), obtaining surface layers with different phase composition (α , γ' and ε - phases) with and without the nitride zone, depending on the temperature, pressure, composition of the saturating medium, and the size of the temperature cycles. Nitriding in a glow discharge achieves a high hardness of the surface of titanium alloys – up to 10,000 MPa, but at the same time the plasticity of the nitrided layers is sharply reduced and the tensile strength of the material is reduced by 30%. Conclusions. 1. The amount of microhardness depends on the phase composition of the surface. Three phases TiN, Ti2N and Ti(N) are formed on the surface of the VT1-0 alloy after nitriding. The hardness of the surface layer of nitrided titanium depends on the ratio of these phases and is higher, the greater the amount of the TiN phase. The TiN phase has the highest hardness, the Ti2N phase has the lowest hardness. The hardness of the internal nitriding zone (Ti(N)) varies depending on the concentration of nitrogen in it. 2. By changing the parameters of the vacuum ion nitriding process in the pulse mode (temperature, pressure, composition of the saturating medium and nitriding time), it is possible to change the physical and mechanical characteristics (diffusion layer depth up to 300 μm, microhardness up to 9600 MPa, different hardness gradient along the depth , phase composition of nitrided surfaces, etc.), obtain surface layers with different phase composition (α, γ' and ε - phases) with and without a nitride zone, depending on temperature, pressure, composition of the saturating medium, and size temperature cycles, which allows to optimize the properties of the surface layer in specific operating conditions. 3. Increasing the nitriding time of titanium alloys contributes to increasing the thickness of the nitrided layer to 300 microns. Addition of inert helium and argon gases to the saturating medium helps to increase the plasticity and thickness of the nitrided layer.

Effects of Plasma Nitriding Temperature on the Properties of 1.3207 Type High Speed Steel

Kutatásunk során 1.3207 (HS10-4-3-10) gyorsacél próbatesten végeztünk aktív ernyős plazmanitridálást három különböző, kicsinek számító nitridálási hőmérsékleten, miközben a nitridálás további paramétereit egységesen tartottuk. Azt követően további két kezelést végeztünk eltérő nitridálási idő mellett. Az elkészült próbatestek keresztmetszetén mikroszerkezeti vizsgálatokat végeztünk, a felületi összetételüket energiadiszperzív röntgenspektrometriával határoztuk meg. Továbbá a keresztmetszeten és a felületeken vizsgáltuk a keménységet. Vizsgálataink eredményeként elmondható, hogy az aktív ernyős plazmanitridálás technológiájával jelentősen, akár 50%-kal is növelhető a kutatás során használt minta felületi keménysége.

Зміцнення інструменту для холодної роликової прокатки корозійностійких труб

The work is devoted to a topical technical problem - to increase the wear resistance of pipe tools for cold roller rolling of corrosion-resistant pipes, due to its significant cost and difficult working conditions. It is proposed to improve the technology of heat treatment of rolled tools for the production of corrosion-resistant pipes (mandrels, rollers, support strips) from steels 4Х5МФ1С and 60С2ХФА. Instead of the usual technology - tempering with tempering, tempering with tempering and subsequent ionic nitriding in plasma of two-stage vacuum-arc discharge in a modified installation "Bulat-6" in the laboratory of plasma technology. The microstructure of special samples of these steels on a scanning electron microscope (SEM) at different magnifications was studied. Their microhardness was determined using a microhardness tester PMT-3. A comparison of the microhardness of the samples after traditional treatment and the proposed. The wear resistance of the actual tool (mandrels made of 60С2ХФA steel) for cold roller rolling of particularly thin-walled corrosion-resistant pipes was studied directly during industrial tests in the factory. Studies of the microstructure on the REM of the nitrided layer after ion-plasma nitriding revealed a finely dispersed very strong ε-phase. Due to its presence in the surface layer, the surface hardness of nitrided parts increases due to the formation of stable in the process of heating carbides, nitrides, carbonitrides. Steel acquires high hardness on the surface, high wear resistance, high endurance, corrosion resistance. Tests of mandrels in the factory, which were additionally subjected to ionic nitriding, showed an increase in their stability by 25-30%. Also reduced the cost of processing the manufacture of pipes and improved the quality of the inner surface of the pipes (absence of films, cuts and other defects of corrosion-resistant pipes). Replacement of steel 60С2ХФA with secondary hardening steel 4Х5MФ1С for the manufacture of rollers and support bars in addition to improving the quality of the inner surface of the pipes increased the stability of the tool by 2.7-3 times. Keywords: rollers, support laths, mandrels, cold rolling, heat treatment, ionic nitriding.

Plasma Nitriding of Inner Surface of Slender Tubes using Small Diameter Helicon Plasma

A steady-state, high-flux N2/Ar helicon wave plasma (HWP) with a small diameter (10 mm) was used to nitride the interior of a slender austenitic stainless steel (ASS) 316L tube at a temperature of 450 °C. N2 and Ar were fed to a 500 mm long slender tube with 10 mm inner diameter and were ionized inside the tube using a helicon wave in the magnetic field of 2000 G. The microstructure and depth of the nitrided layers, in addition to the morphology and hardness of the nitrided surfaces, were intensively characterized by employing scanning electron microscopy (SEM), optical microscopy (OM), X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), as well as microhardness tests. The results confirmed that the nitrided layer consisted primarily of the expanded austenite phase γN, and neither CrN nor iron nitride precipitates. An increasing trend in microhardness was observed in inductively coupled plasma (ICP) and HWP modes; however, the increase in HWP nitriding (up to HV 1820 with a thickness of 14 μm) was approximately 1.5 times greater than that achieved through ICP plasma nitriding. This was owing to the higher N+ ion density in the HWP mode. Considering the successful control of N2 plasma discharge in a slender tube with a small diameter, this study opens up a new avenue for achieving high-yield nitride layers inside slender tubes.

Modification of Diffusion Layers by Laser Shock Peening

The article deals with a possibilities of an enhancement of functional properties of highly stressed components by specific combination of surface technology. Two surface technologies such as plasma nitriding and laser shock peening were selected for the experiment. Those technologies were applied upon steel 42CrMo4 frequently utilized in manufacturing of strained components. Properties obtained by applied surface technologies were tested by following experimental methods. The chemical composition was verified by optical emission spectrometer Tasman Q4 Bruker. The surface morphology was inspected by scanning electron microscope TESCAN MIRA 4. The microstructure of heat treated as well as of nitrided specimens was observed by opto-digital microscope Olympus DSX500i. The microhardness profiles were measured by microhardness tester LM247 AT LECO. The friction coefficient was tested on tribometer Bruker UMT 3 TriboLab. For an assessment of the surface wear resistance the profilometer Talysurf CLI 1000 and Contour GT were utilized. The experimental results show that although the proposed surface technology combination manifests itself to be disadvantageous, both technology LSP, as well as plasma nitriding, applied separately, can lead to a significant wear reduction.

Direct and pulse electroplating effects on the diffusion barrier property of plasma-nitrided Cr coatings on HT9 steel

The introduction of a Cr and chromium nitride multi-coating barrier between the nuclear metallic fuel and the cladding is a potential candidate to mitigate fuel cladding chemical interaction (FCCI). Cr coatings were electroplated on HT9 disks using direct and pulse currents followed by plasma nitriding for synthesizing additional nitride coating. The pulse current induced Cr coatings revealed severe microstructural changes from crack-free to the abundance of cracks during the plasma nitriding due to phase transformation during the plasma nitriding. The phase transformation of hexagonal CrH to cubic Cr occurred at a temperature as low as 110 °C resulting in the liberation of hydrogen pores agglomerated at Cr grain boundaries and internal stress. Finally, the diffusion barrier property of the pulse current induced Cr coatings was significantly reduced, while the plasma-nitrided Cr coating produced by a direct current exhibited a crack-closure effect, and an additional nitride layer successfully hindered the elemental diffusion of Ce and Nd at 650 °C for 25 h. This current study points to the critical effect of current waveforms on the final barrier property of Cr-chromium nitride coatings for nuclear cladding applications.

A novel crack healing in sprayed FeCrBSi coatings by plasma nitriding

In this study, the plasma nitriding technique was applied to heal the cracks of the FeCrBSi coating. Plasma nitriding was carried at 520 °C for 4, 8 and 16 h in an atmosphere of 75 vol% nitrogen and 25 vol% hydrogen. The crack-healing behavior of FeCrBSi coating was observed on the nitrided surface, and the healing effect becomes more noticeable as the nitriding duration increases. After 8 h of nitriding, the thickness of the nitrided layer reaches ∼12 μm and the surface hardness is the highest (c. 12 GPa). According to microstructural evolution, the healing mechanism of FeCrBSi coating by nitriding was investigated.

Performance evaluation of plasma nitrided 316L stainless steel during long term high temperature sodium exposure

Enhancement of wear resistance of components used in fast reactors is necessary for long service life of the components. Plasma nitriding is a promising surface modification technology to impart high hardness and improved wear resistance of various steel components. This study discusses the characterization of chrome nitrided SS316L casing ring used in secondary sodium pump of fast breeder reactor and its stability under long term sodium exposure. Microstructural and hardness analysis showed that stress relieved component could be chrome nitrided successfully to a thickness of about 100 μm. Assessment of in-sodium performance of the chrome nitrided casing ring subjected to long term exposure up to 5000h at 550°C, showed retention of chrome nitrided layer with a case depth almost similar to that before sodium exposure. A slight decrease in the hardness was observed due to prolonged high temperature sodium exposure. Tribological studies indicate very low coefficient of friction indicating the retention of good wear resistance of the coating even after long term sodium exposure.