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1

The influence of plasma nitriding process conditions on the microstructure of coatings obtained on the substrate of selected tool steels

Mokrzycka Magdalena, Przybyło Adrianna, Góral Marek, Kościelniak Barbara, Drajewicz Marcin, Kubaszek Tadeusz, Gancarczyk Kamil, Gradzik Andrzej, Dychtoń Kamil, Poręba Marek, Jopek Jakub, Pytel Maciej

Advances in Mechanical and Materials Engineering

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2024

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Vol. 41, nr 1

5-16

EN

This study presents the results of research into the influence of the time of the plasma nitriding process on the microstructure of the coatings obtained. Cold-work tool steels (60WCrV8, 90MnCrV8, 145Cr6), hot-work tool steel (X37CrMoV5-1) and high-speed tool steel (HS6-5-2) were selected as substrate material. The processes were carried out under industrial conditions using an Ionit device from Oerlikon Metaplas with variable process times of 2, 4 and 6 hours. According to literature data, a nitriding mixture consisting of 5% nitrogen and 95% hydrogen was chosen, which allowed the expected diffusion layer to be obtained without a white layer (composed of iron nitrides). Analysis of elemental mapping indicates that the presence and content of nitride-forming elements influences the formation of alloy additive nitrides in the microstructure of the diffusion layer. It was also found that an increase in the duration of plasma nitriding, results in an increase in the depth of the nitrided layers formed on the substrate of high-alloy steels: X37CrMoV5-1 and HS6-5-2. Nitrides of alloying additives, present in the diffusion layer, are formed in the high-alloyed the hot-work steel X37CrMoV5-1, indicating that these steels are the most suitable for plasma nitriding of the entire tool steels analysed.

PL

W pracy przedstawiono wyniki badań wpływu czasu procesu azotowania plazmowego na mikrostrukturę otrzymanych powłok. Jako materiał podłoża wybrano stale narzędziowe do pracy na zimno (60WCrV8, 90MnCrV8, 145Cr6), stale narzędziowe do pracy na gorąco (X37CrMoV5-1) oraz szybkotnące (HS6-5-2). Procesy prowadzono w warunkach przemysłowych z wykorzystaniem urządzenia Ionit firmy Oerlikon Metaplas ze zmiennymi czasami procesu 2, 4 i 6 godzin. Zgodnie z danymi literaturowymi wybrano mieszaninę azotującą składającą się z 5% azotu i 95% wodoru, co pozwoliło na uzyskanie oczekiwanej warstwy dyfuzyjnej bez warstwy białej (złożonej z azotków żelaza). Analiza mapowania pierwiastkowego wskazuje, że obecność i zawartość pierwiastków azototwórczych w pływa na powstawanie azotków dodatku stopowego w mikrostrukturze warstwy dyfuzyjnej. Stwierdzono również, że wydłużenie czasu azotowania plazmowego powoduje zwiększenie głębokości warstw azotowanych powstających na podłożu ze stali wysokostopowych: X37CrMoV5-1 i HS6-5-2. Azotki dodatków stopowych, obecne w warstwie dyfuzyjnej, powstają w wysoko-stopowej stali do pracy na gorąco X37CrMoV5-1, co wskazuje, że stale te są najbardziej odpowiednie do azotowania plazmowego spośród wszystkich analizowanych stali narzędziowych.

2

The Role of Complementary Potential in Plasma Nitriding Processes of Technical Titanium

Pilarska M., Frączek T., Maźniak K.

Archives of Metallurgy and Materials

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2018

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Vol. 63, iss. 4

1637--1642

EN

This article deals with the testing of surface layers produced on technical titanium Ti99.2 under glow discharge conditions. In order to determine the effect of process temperature on the produced surface layers, nitriding processes were carried out at 700°C and 800°C and for 3 and 5 hours. The research results on evaluating the properties of the obtained surface layers and the characterization of their morphology were presented. The impact of the adopted nitriding process variant on the quality of the obtained layers was evaluated. It was demonstrated that the use of the supplementary potential during the ion nitriding process reduces the unwanted edge effect, which results in a significant increase in the homogeneity of the nitrided layers and improves the functional properties of the technical titanium Ti99.2.

3

Influence of plasma glow discharge on nitriding process of technical titanium

Pilarska M., Frączek T.

Journal of Achievements in Materials and Manufacturing Engineering

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2017

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Vol. 85, nr 1

21--25

EN

Purpose: This article compares selected properties of surface layers produced by plasma nitriding. Additionally, the temperature at the onset of the production of surface layers with uniform characteristics over the entire sample surface was determined. Design/methodology/approach: The selected properties of the surface layers were compared using the following test methods: microhardness measurement by the Knoop method, GDEOS profile analysis, XRD analysis, topography analysis. Findings: It was found that nitriding in plasma glow discharge at 700°C results in obtaining homogeneous surface layers over the entire surface of the sample Research limitations/implications: The ion nitride processes did not allow a complete reduction in the oxygen content. Practical implications: The adopted plasma nitriding parameters will allow homogeneous properties of the surface layers over the entire surface of the sample to be obtained. Originality/value: The effect of plasma glow discharge on the properties of surface layers was determined.

4

Structure and adhesion of nickel–phosphorus coatings plated on the nitrided 1.2343 (WCL) steel

Zych A., Kulikowski K., Kucharska B., Wierzchoń T.

Inżynieria Materiałowa

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2017

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Vol. 38, nr 6

254--258

EN

Modern industry expects comprehensive solutions in terms of ensuring adequate exploitation properties of materials, such as high hardness, wear resistance, fatigue strength and corrosion resistance in aggressive environments. These requirements can be met via surface treatments, especially vigorously developed in recent years hybrid technologies, which merge various methods in the aspect of composite layers production. Those layers are characterized by complementing or entirely new properties in comparison to layers or coatings manufactured in separate processes. In this study the plasma nitriding process and electroless nickel plating are combined. In the production of composite layers consisting of surface layer and coating, in this particular case it is essential to ensure good adhesion of the Ni(P) coating to nitrided substrate. This paper presents microstructure (light microscopy), microhardness (crosssection and surface), surface roughness and scratch test results after different variants and steps of treatment of heat treated 1.2343 (WCL) steel. The study was conducted on the nitrided layers varying in structure and surface topography due to grinding prior to electroless nickel plating. The results show that heat treatment subsequent to electroless nickel plating leads to increase in composite layers’ hardness and adhesion of Ni(P) coating to nitrided layer. Moreover, Ni(P) coating might act as a solid lubricant in some cases.

PL

Celem badań było określenie wpływu struktury, twardości oraz rozwinięcia powierzchni warstwy azotowanej na stali 1.2343, a także procesu obróbki cieplnej powłoki Ni(P) na przyczepność powłoki niklowo-fosforowej do azotowanego podłoża. W pracy zawarto wyniki badań chropowatości powierzchni, mikrostruktury warstw kompozytowych, ich twardości oraz przyczepności.

5

Direct current and pulsed direct current plasma nitriding of ferrous materials a critical review

Łępicka M., Grądzka-Dahlka M.

Acta Mechanica et Automatica

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2016

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Vol. 10, no. 2

150--158

EN

Nowadays, the improvement of ferrous materials performance is a problem of high interest. One of well-known wear- and corrosion properties improving technique is plasma nitriding, in which elemental nitrogen is introduced to the surface of a metal part for subsequent diffusion into the material. As a result, a compound, “white” layer and a diffusion zone are formed at the detail’s surface. Most of the authors positively describe the effects of surface ion nitiding. On the other hand, there are also reports on adverse effects of direct current and pulsed direct current plasma nitriding on ferrous materials performance. Therefore, an attempt to provide comprehensive summary on direct current and pulsed direct current ion nitriding and its influence on ferrous materials’ mechanical and corrosion properties has been made. According to the results, some of the technique drawbacks are hard to avoid in mass production.

6

Selected plasma nitriding methods usable for the thermo-chemical treatment of aircraft parts

Grzesiak G., Zahorski T., Stypniak M., Walkowicz J., Jurczyszyn R.

Journal of KONES

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2014

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Vol. 21, No. 4

145--152

EN

The aim of the work was to review selected methods of plasma nitriding, which according to the authors might he used in the thermo-chemical treatment of aircraft parts. The introduction explains the nitriding process and presents the requirements on the thermo-chemical treatment of aircraft parts. Three methods of plasma nitriding have been described: Direct Current Plasma Nitriding (DCPN), Active Screen Plasma Nitriding (ASPN) and Low Pressure Nitriding in AEGD (Arc Enhanced Glow Discharge) plasma. While describing DCPN plasma nitriding method, authors drew attention to known problems, which occur in this process such as edge effect or hollow cathode effect. The Keller's model, the Marchand's model and the Walkowicz's model of nitriding process, which can be found in the literature, were also presented in this work. Another purpose of this work was to present hypotheses about the transportation of nitrogen during Active Screen Plasma Nitriding process and to show that in this nitriding method, defects typical for Direct Current Plasma Nitriding do not occur. While describing Low Pressure Nitriding in AEGD plasma, authors also presented the model of nitriding mechanism in this process, which shows four nitrogen diffusion paths (physisorption, chemisorption, adsorption ofNj, ion implantation). Examples of layers obtained by applying described nitriding methods were presented. The measurement ofnitrided layers confirmed that it is possible to obtain a layer without E film on the surface.

7

Effect of plasma nitriding process conditions on corrosion resistance of 440B martensitic stainless steel

Łępicka M., Dahlke M.

Acta Mechanica et Automatica

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2014

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Vol. 8, no. 3

156--159

EN

Martensitic stainless steels are used in a large number of various industrial applications, e.g. molds for plastic injections and glass moldings, automotive components, cutting tools, surgical and dental instruments. The improvement of their tribological and corrosion properties is a problem of high interest especially in medical applications, where patient safety becomes a priority. The paper covers findings from plasma nitrided AISI 440B (PN-EN or DIN X90CrMoV18) stainless steel corrosion resistance studies. Conventionally heat treated and plasma nitrided in N2:H2 reaction gas mixture (50:50, 65:35 and 80:20, respectively) in two different temperature ranges (380 or 450°C) specimens groups were examined. Microscopic observations and electrochemical corrosion tests were performed using a variety of analytical techniques. As obtained findings show, plasma nitriding of AISI 440B stainless steel, regardless of the process temperature, results in reduction of corrosion current density. Nevertheless, applying thermo-chemical process which requires exceeding temperature of about 400°C is not recommended due to increased risk of steel sensitization to intergranular and stress corrosion. According to the results, material ion nitrided in 450°C underwent leaching corrosion processes, which led to significant disproportion in chemical composition of the corroded and corrosion-free areas. The authors suggest further research into corrosion process of plasma nitrided materials and its degradation products.

8

Wpływ plazmochemicznej modyﬁkacji powierzchni stopów Al-Zn-Mg na ich budowę i wybrane właściwości użytkowe

Kyzioł K., Kaczmarek Ł., Kluska S., Środa M., Jonas S.

Inżynieria Materiałowa

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2013

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Vol. 34, nr 5

497--500

PL

Praca przedstawia wyniki badań budowy i wybranych parametrów użytkowych stopów Al-Zn-Mg przed i po modyﬁkacji ich powierzchni metodą RF CVD (Radio Frequency Chemical Vapour Deposition). W prowadzonych eksperymentach zmieniano rodzaj i skład otrzymywanej powłoki, którą stanowiły struktury SiNH lub SiNH dotowane węglem. Za każdym razem stopy poddawano procesowi trawienia jonowego (Ari) i azotowania powierzchni w warunkach plazmochemicznych. Do badań wykorzystano techniki typowe dla inżynierii materiałowej, mikroskopię elektronową skaningową (SEM) Z analizą składu chemicznego (EDS), dyfraktometrię rentgenowską (XRD) oraz badania twardości, modułu Younga (metodą nanoindentacji) i parametrów zużycia tribologicznego (współczynnika tarcia) wraz z obrazami niszczenia powłok. Na podstawie otrzymanych wyników można stwierdzić, że otrzymanie powłoki przeciwzużyciowej (SiCNH) zawierającej w swojej strukturze węgiel wpływa korzystniej zarówno na badane parametry mechaniczne (twardość ok. 9 GPa, moduł Younga ok. 85 GPa), jak i tribologiczne w porównaniu z modyfikacją, w której powłokę zewnętrzną stanowiła powłoka SiNH. Można to tłumaczyć obecnością w strukturze wiązań CN, CC i fazy SiC, których odpowiednio wytrzymałość i budowa w znacznym stopniu mogą wpływać na synergizm układu powłoka-podłoże.

EN

The work presents the results of the selected physicochemical parameters of Al-Zn-Mg alloys before and after surface modiﬁcation using RF CVD (Ra- dio Frequency Chemical Vapour Deposition) method. In research, type and composition ofthe studied layer, i.e. SiNH coatings or SiNH coatings doped carbon atoms, were changed. Every time, the alloys were treated by plasma etching and nitriding. Typical techniques for materials engineering such as scanning electron microscopy (SEM) with EDS analysis, X-ray diffraction, nanoindentation method (hardness and Young's modulus) and tribological parameters (incl. friction coefﬁcient) with proliferation of coatings images were applied in the performer study. It can be concluded that the obtained anti-wear coatings, containing carbon in its structure, positively inﬁuence on mechanical (hardness approx. 9 GPa, Young's modulus approx. 85 GPa) and tribological parameters, in comparison with the modified external surfaces with SiNH coatings. It can be explained by CN, CC bonds in coating structure as well as SIC phase, both existence may inﬁuence on synergism of coating-aluminum alloy system.

9

Krótkookresowe i niskotemperaturowe azotowanie jarzeniowe stali austenitycznej X5CrNi18-10 z zastosowaniem ekranu aktywnego

Ogórek M., Frączek T., Skuza Z., Maźniak K.

Inżynieria Materiałowa

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2013

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Vol. 34, nr 5

513--516

PL

Badaniom poddano stal austenityczną gatunku X5CrNi18-10 według PN-EN 10088-121998 (304 Wg AISI) po azotowaniu jarzeniowym w temperaturze 375°C przez 3 h dla dwóch różnych wariantów rozmieszczenia próbek w komorze jarzeniowej: bezpośrednio na katodzie oraz na katodzie z zastosowaniem ekranu aktywnego. Proces azotowania jonowego przeprowadzono zgodnie z opracowanym modelem matematycznego planowania doświadczeń według kwadratu łacińskiego. Zakres zastosowanego czasu i temperatury azotowania przyjęto na podstawie przeprowadzonych badań wstępnych dotyczących krótkookresowego i niskotemperaturowego azotowania jarzeniowego stali austenitycznych. Każdy z przyjętych parametrów azotowania spowodował zwiększenie twardości powierzchniowej azotowanych stali. Najważniejszym wyznacznikiem podczas wyboru parametrów azotowania było uzyskanie warstw azotowanych o satysfakcjonujących właściwościach tribologicznych przy zachowaniu dobrej odporności korozyjnej azotowanej stali austenitycznej (brak zachodzenia procesów wydzieleniowych azotków chromu prowadzących do dechromizacji osnowy austenitycznej).W celu oceny efektywności wariantów procesu azotowania przeprowadzono badania głębokości dyfuzji metodą GDOES, badania twardości powierzchniowej, badania odporności na zużycie ścierne oraz analizę mikrostruktury otrzymanych warstw wierzchnich. Stwierdzono, że zastosowanie ekranów wspomagających powoduje wzrost głębokości dyfuzji azotu w głąb azotowanej stali austenitycznej X5CrNi18-10, Zwiększenie grubości otrzymanych warstw wierzchnich, a co za tym idzie wpływają na poprawę odporności na zużycie ścierne. Szczególnie jest widoczna poprawa odporności na zużycie ścierne próbek azotowanych z ekranem aktywnym w porównaniu z próbkami azotowanymi katodowo.

EN

The research was conducted on austenitic steel X5CrNi1 8-10 PN-EN 10088- 121998 (AISI 304) after plasma glow nitriding at 375°C and time 3 h, for the two different variants of samples distribution in the chamber tube. Ion nitriding process was carried out in accordance with a mathematical model of experimental design, according to the latin square. Range of time and temperature used during nitriding process were adopted on the basis of preliminary studies on the short-term and low-temperature plasma nitriding of austenitic steels. Each of the parameters of nitriding process caused the increase of the surface hardness of nitrided steel. The most important determinant when choosing nitriding parameters was to obtain nitrided layers with satisfactory tribological properties while maintaining good corrosion resistance of nitrided austenitic stainless steel (no chromium nitride precipitation processes leading to dechromization of austenitic matrix). In order to assess the effectiveness of the studied nitriding variants diffusion depth analysis using GDOES, surface hardness measurement, wear resistance test and structural analysis ofthe surface layers were conducted. It was found that the use of screens increases the depth of nitrogen diffusion into the nitrided austenitic steel X5CrNil 8-10, thereby increasing the thickness ofthe surface layers. In particular, an improvement of wear resistance of nitrided samples with the active screen compared to cathodic nitrided ones was seen.

10

Analiza fazowa i stan naprężeń własnych w warstwach azotowanych na stopie tytanu Ti6Al4V wytwarzanych w niskotemperaturowej plazmie

Skrzypek S. J., Tarnowski M., Goły M., Borowski T., Wierzchoń T.

Inżynieria Materiałowa

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2013

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Vol. 34, nr 6

872--875

PL

Obróbki powierzchniowe biomateriałów tytanowych znajdują coraz szersze zastosowanie w kształtowaniu ich właściwości użytkowych jako implantów kostnych i kardiologicznych, takich jak: odporność na zużycie przez tarcie, atrombogenność, aktywność biologiczna, zwilżalność czy wytrzymałość zmęczeniowa. Na właściwości tych warstw w istotnym stopniu, obok topografii powierzchni, składu chemicznego i morfologii składników mikrostrukturalnych, wpływa skład fazowy i stan naprężeń własnych, które można kształtować warunkami technologicznymi zastosowanych procesów plazmowych obróbek powierzchniowych. W artykule przedstawiono badania składu fazowego i stanu naprężeń własnych określonych metodami sin2ψ i GID-sin2ψ warstw azotowanych, wytworzonych w temperaturze ok. 650°C na stopie Ti6Al4V metodami azotowania w niskotemperaturowej plazmie zarówno na potencjale katody, jak i z zastosowaniem aktywnego ekranu, w zależności od sposobu przygotowania powierzchni (szlifowanie, polerowanie) i wykorzystania zjawiska rozpylania katodowego. Przedstawiono również topografię oraz stan chropowatości powierzchni azotku tytanu – zewnętrznej strefy warstwy azotowanej typu TiN + Ti2N + α-Ti(N).

EN

Surface treatments of titanium biomaterials are increasingly used in forming the properties of titanium bone and cardiac implants such as: wear resistance, athrombogenic properties, biological activity, wetability or fatigue strength. Properties of these layers like surface topography, chemical and phase composition and morphology can affect their residual stresses state and can be modified with several different process parameters. This paper presents the phase composition and residual stress state analysis, using sin2ψ and GID-sin2ψ methods, of nitrided layers produced on Ti6Al4V titanium alloy at 650°C in cathode and plasma potential (active screen plasma nitriding) according to mechanical state of the surface before the nitriding process (polishing, grinding) using the cathode sputtering phenomena. The topography and surface roughness parameters of produced titanium nitride TiN outer zone of TiN + Ti2N + α-Ti(N) diffusive layers are presented.

11

Effect of heat treatment and plasma nitriding on corrosion resistance of 440B martensitic stainless steel

Łępicka M., Grądzka-Dahlke M.

Acta Mechanica et Automatica

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2013

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Vol. 7, no. 3

155--159

EN

Reliability and durability assurance poses a serious challenge for surgical instruments manufacturers. Hard working conditions, such as intermittent contact with body fluids and hard bone tissues, as well as necessity to undergo frequent sterilisation processes, induce constant research into solutions capable of ensuring high wear resistance while maintaining satisfactory imperviousness to corrosion. Plasma nitriding is marked as the modern corrosion resistance improving method suitable for surgical instruments steels. The paper pre-sents findings from the heat treated and plasma nitrided AISI 440B (PN EN or DIN X90CrMoV18) steel corrosion resistance studies. Three conventionally heat treated (quenched with tempering in 250, 390 or 605°C) and three additionally plasma nitrided in N2:H2 reaction gas mixture (50:50, 35:65 and 20:80 ratio, respectively) specimens groups were examined. Furthermore, the authors evaluated the effect of machining - polishing and sandblasting - on investigated steel corrosion resistance. Microscopic observations and electrochemical corrosion tests were performed using a variety of analytical techniques. Results showed that, in comparison to conventional heat treatment, plasma nitriding of 440B stainless steel does not significantly affect its corrosive characteristics as far as the uniform nitride layer over the entire detail surface is obtained. The layer heterogeneity results in intensification of corrosion processes, making the material even more susceptible to corrosion than after conventional heat treatment, and contributing to severe, visible even with the unaided eye damages development.

12

Optimized plasma nitriding processes for efficient wear reduction of forging dies

Paschke H., Weber M., Braeuer G., Yilkiran T., Behrens B. A., Brand H.

Archives of Civil and Mechanical Engineering

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2012

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Vol. 12, no. 4

407--412

EN

Plasma nitriding treatments are approved to reduce wear occurring in the field of hot forging applications. But there are demands for a further optimization of the processes in order to achieve adapted properties for differently loaded forging tools. This work presents the influence of main process parameters on the wear behavior of dies. The focused steel material of this work is DIN-X38CrMoV5-1 (1.2343), a standard hot forming tool steel. The influence of nitriding parameters like temperature, nitrogen flow and time on the nitriding depth, hardness and crack sensitivity has been investigated. Comparative application tests show the influence of different surface treatments on the wear behavior and lifetime of forging tools in an industrial environment.

13

Wpływ wodoru na warstwy azotowane na stali 34CrAlNi7-10

Ćwiek J.

Ochrona przed Korozją

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2011

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nr 4-5

225-229

PL

W artykule przedstawiono wyniki badań wpływu warstwy azotowanej jarzeniowo na stali 34CrAlNi7-10 na jej podatność na niszczenie wodorowe. Badania przeprowadzono rozciągając próbki z małą prędkością w powietrzu i środowisku kwaśnym podczas polaryzacji katodowej. Badano przenikanie oraz absorpcję wodoru przez warstwę azotowaną - wykonano elektrochemiczne pomiary przenikania wodoru przez membranę oraz pomiary ekstrakcji próżniowej. Przełomy próbek po próbach rozciągania obserwowano przy użyciu skaningowego mikroskopu elektronowego w celu określenia wpływu wodoru na zmianę charakteru pękania. Warstwy azotowane stanowią barierę dla wnikania wodoru do stali, przez co zmniejsza się jej podatność na niszczenie wodorowe. Wodór jest głównie akumulowany w strefie azotków. Nawodorowanie warstwy azotowanej nie powoduje zwiększenia jej kruchości w próbie odkształcania z małą prędkością.

EN

Studies on the influence of nitrided layer on 34CrAlNi7-10 on the susceptibility of steel to hydrogen degradation has been presented in the paper. Investigations were carried out using the slow strain tensile rate test (SSRT) in air and in an acidic environment under cathodic polarization. Permeation and absorption of hydrogen in nitrided layer were evaluated - an electrochemical hydrogen permeation test through a membrane, and hydrogen vacuum extraction test were performed. The fractured surface of the specimens with modified layers were examined using a scanning electron microscope (SEM) in order to determine the influence of hydrogen on change in the fracture mode. Plasma nitrided layers, being effective barriers to hydrogen entry into steel, decrease the susceptibility of steel to hydrogen degradation. Hydrogen is mainly accumulated in a compound nitrides zone. There is no evidences for increase in the brittleness of nitrided layers with absorbed hydrogen.

14

Processing and Surface Properties of Based on Iron Sintered Alloys after Plasma Nitriding Treatment

Karwan-Baczewska J., Dymkowski T., Sobiecki J. R., Formański T.

Archives of Metallurgy and Materials

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2010

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Vol. 55, iss. 2

383-389

EN

Sintered parts based on iron and alloyed powders have been widely used in automotive industry. In order to enhance surface properties of those PM (Powder Metallurgy) alloys like hardness and abrasive wear, nitriding and carbonitriding treatment are applied. One of the main problem of PM chemical heat treatment alloys is their porosity degree. In the experiments Fe-Ni-Cu-Mo and Fe-Mo sintered structural parts modified by boron were made. Boron activates the sintering process which results in their considerable consolidation in the sintering at 1200 °C for 60 min. in the atmosphere of hydrogen. The experiments are related to the production of sintered structural elements based on iron powder – NC 100,24 as well as Astaloy Mo (Fe-Mo) and Distaloy SA (Fe-Ni-Cu-Mo) modified by 0.2 wt%, 0,4 wt% and 0,6 wt% B. P/M parts were obtained by mixing powders said above, followed by compacting at 600 MPa pressure and sintered at 1200 °C during 60 minutes time in hydrogen atmosphere. Selected sintered parts were plasma nitrided at 560 °C during 4 hours time. The effect of plasma nitriding on the microstructure and surface properties of samples has been analyzed.

PL

Elementy spiekane produkowane z proszków żelaza i z proszków stopowanych znajdują szerokie zastosowanie w przemyśle motoryzacyjnym. Ażeby podwyższyć właściwości powierzchniowe stopów wytworzonych technologią metalurgii proszków, między innymi twardość i odporność na ścieranie stosuje się azotowanie lub węgloazotowanie. Podstawowym problemem obróbki cieplno-chemicznej spieków jest występowanie pewnego stopnia porowatości. W przeprowadzonych eksperymentach wytworzono spieki z proszków stopowanych (Fe-Ni-Cu-Mo) i (Fe-Mo) z dodatkiem boru, który aktywuje proces spiekania prowadzony w temperaturze 1200 °C, w czasie 60 min., w atmosferze wodoru i w efekcie doprowadza do znacznego zagęszczenia próbek. Wykonane eksperymenty dotyczyły otrzymywania spieków na bazie proszku żelaza – NC 100,24, proszku stopowanego Astaloy Mo (Fe-Mo) i proszku stopowanego Distaloy SA (Fe-Ni-Cu-Mo) z dodatkiem 0,2%wag., 0,4%wag. i 0,6%wag. Próbki uzyskano w wyniku mieszania w/w proszków z dodatkiem boru, następnie prasowania pod cisnieniem p=600 MPa i spiekania w temperaturze 1200 °C, w czasie 60 min., w atmosferze wodoru. Wybrane części spiekane poddano procesom azotowania plazmowego w temperaturze 560 °C, w czasie 4 godzin. W toku eksperymentów przeanalizowano wpływ azotowania plazmowego na mikrostrukturę i właściwosci powierzchniowe badanych spieków.

15

Behaviour of nitrided layers subjected to influence of hydrogen

Ćwiek J., Baczyńska M.

Archives of Materials Science and Engineering

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2010

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Vol. 43, nr 1

30-41

EN

Purpose: of this paper is evaluation of behaviour of plasma nitrided layers subjected to influence of internal and external hydrogen. Properties of nitrided layers like: hydrogen permeation and trapping, fracture mode, and plasticity were examined. Design/methodology/approach: Structural low-alloy steel was nitrided at glow discharge in the gas mixture of various N2, H2, and Ar content. Samples with nitrided layers were subjected to cathodic hydrogen charging in acid solution simulating the aged engine oil hydrogenating environment. The effect of the nitrided layers on the hydrogen transport and on the irreversible trapping was evaluated by the measurements of the hydrogen permeation rate and by the vacuum extraction, respectively. Surfaces with modified layers were examined with the use of a scanning electron microscope (SEM) before and after hydrogen permeation tests. Slow strain rate test (SSRT) on samples with and without nitrided layers was carried out in hydrogen generating environment. After SSRT fracture mode and plasticity of nitrided layers were examined with SEM. Findings: In the presence of the not defected compact nitride layer, no hydrogen permeation through the steel has been stated under the experimental conditions. Influence of hydrogen content in working atmosphere, i.e. internal hydrogen, was found. Absorbed hydrogen, i.e. external hydrogen, was accumulated within this layer. Research limitations/implications: There is no possibility to perform direct observations of exact mechanism of hydrogen-assisted cracking so far. Further research should be taken to reveal the exact mechanism of increased plasticity of nitrided layer with absorbed hydrogen. Practical implications: Plasma nitrided layers are effective barriers to hydrogen entry into structural steel utilised in aggressive environments, which is especially important in the case of possible hydrogen charging of exploited steel. Originality/value: Using the atmosphere of the higher nitrogen to hydrogen ratio at plasma assisted nitriding provides the formation of thin compact nitride zone, highly protective against corrosion and hydrogen degradation. Evidences of a likely increased plasticity of nitrided layers with absorbed hydrogen was observed.

16

Topography of X39Cr13 steel surface after heat and surface treatment

Gwoździk M., Nitkiewicz Z.

Optica Applicata

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2009

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Vol. 39, nr 4

853-857

EN

The paper presents results of surface condition examinations of martensitic X39Cr13 steel subject to heat and surface treatment (plasma nitriding). The heat treatment consisted of compressed nitrogen quenching from 1050 °C (1323 K) and two-hours tempering at 300 °C (573 K) and 620 °C (893 K) for specimens subject to nitriding. The plasma nitriding was carried out in an ion-nitriding installation with cooled anode, at temperature of 460 °C (733 K), at pressure of 150 Pa and during t = 20 h (72 ks); 25%N2+75%H2 was used as the reactive atmosphere. Specimens surface was examined using a profilographometer designed for surface 2D and 3D examinations using a contact method. Surface topography measurements were carried out on specimens taken from 1 mm thick sheet. 1.5 mm×1.5 mm surface was the measurement area. The sampling interval in X and Y axis was 1 žm, while the measuring speed was 0.5 mm/s. The studies carried out allowed evaluating the conditions of examined steel surface through the comparison of stereometric parameters of the surface.

17

Investigation of surface properties of high temperature nitrided titanium alloys

Koyuncu E., Kahraman F., Karadeniz Ö.

Journal of Achievements in Materials and Manufacturing Engineering

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2009

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Vol. 37, nr 2

434-441

EN

Purpose: The purpose of paper is to investigate surface properties of high temperature nitrided titanium alloys. Design/methodology/approach: In this study, surface modification of Ti6Al4V titanium alloy was made at various temperatures by plasma nitriding process. Plasma nitriding treatment was performed in 80% N2-20% H2 gas mixture, for treatment times of 2-15 h at the temperatures of 700-1000°C. Surface properties of plasma nitrided Ti6Al4V alloy were examined by metallographic inspection, X-Ray diffraction and Vickers hardness. Findings: Two layers were determined by optic inspection on the samples that were called the compound and diffusion layers. Compound layer contain TiN and Ti2N nitrides, XRD results support in this formations. Maximum hardness was obtained at 10h treatment time and 1000°C treatment temperature. Micro hardness tests showed that hardness properties of the nitrided samples depend on treatment time and temperature. Practical implications: Titanium and its alloys have very attractive properties for many industries. But using of titanium and its alloys is of very low in mechanical engineering applications because of poor tribological properties. Originality/value: The nitriding of titanium alloy surfaces using plasma processes has already reached the industrial application stage in the biomedical field.

18

Comparison of the PVD coatings

Polok-Rubiniec M., Dobrzański L., Adamiak M.

Archives of Materials Science and Engineering

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2009

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Vol. 38, nr 2

118-125

EN

Purpose: of the paper was comparison of the structure, adhesion and wear resistance of the monolayers CrN and TiN PVD coatings deposited onto plasma nitrited X37CrMoV5-1 type hot work tool steel. Design/methodology/approach: Diffraction and thin film structue were tested with the use of the transmision electron microscopy. The surfaces’ thopography and the structure of the PVD coatings were observed on the scanning electron microscopy.The evaluation of the adhesion of coatings to the substrate was made using the scratch test. The wear and friction tests were performed on a pin-on-disc device at the room temperature and at the temperature of 500°C. Findings: The best wear resistance in both conditions (20°C, 500°C temperature) demonstrate the TiN coating. These test results correspond with the very good adhesion of the coating to the substrate material and its high hardness. The critical load Lc5 (coating total delamination) lies within the range 86-92 N, depending on the coating type. It was revealed that the coating damage mechanism in the scrtch test commences in all cases with the widespread coating at the edge of the scratch being made and next develops depending on the coating type and location of the originated defects. Practical implications: The good properties of the plasma nitriding and the PVD coatings make them suitable in various engineering and industrial applications. Originality/value: The duplex surfaces treatment of the hot work tool steel for tools made for work at the elevated temperature improves their abrasion wear resistance significantly, compared to coatings developed with the PVD process.

19

Plasma Nitriding as a Prevention Method Against Hydrogen Degradation of Steel

Ćwiek J.

Advances in Materials Science

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2009

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Vol. 9, nr 1(19)

4-13

EN

Aim of this paper is evaluation of susceptibility of plasma nitrided structural steel to hydrogen absorption and degradation. Structural steel, nitrided at glow discharge in the gas mixture of various N2, H2, Ar content was subjected to cathodic hydrogen charging in acid solution simulating the aged engine oil. The effect of the nitrided layers on the hydrogen transport and on the irreversible trapping was evaluated by the measurements of the hydrogen permeation rate and by the vacuum extraction, respectively. Surfaces with modified layers were examined with the use of a scanning electron microscope (SEM) before and after hydrogen permeation tests. In the presence of the not defected compact nitride layer, no hydrogen permeation through the steel has been stated under the experimental conditions. Absorbed hydrogen was accumulated within this layer. Using the atmosphere of the higher nitrogen to hydrogen ratio at plasma assisted nitriding provides the formation of thin compact nitride zone, highly protective against corrosion and hydrogen degradation.

20

Efektywne wykorzystanie energii elektrycznej w piecach jarzeniowych

Niedbała R.

Przegląd Elektrotechniczny

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2008

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R. 84, nr 5

71-74

PL

Zadawalające rezultaty uzyskiwane w technologiach z udziałem wyładowania jarzeniowego spychały na dalszy plan całościowe rozwiązania urządzeń i planowanie procesów energetycznych. W referacie przedstawiono cechy wyładowania jarzeniowego anormalnego w aspekcie procesów azotowania detali o różnorodnej geometrii. Podano dostrzeżone związki pomiędzy charakterystykami energetycznymi wyładowania jarzeniowego a stratami cieplnymi. Na podstawie zebranych doświadczeń określono wzajemne współdziałanie układów zasilających z odpowiednimi konstrukcjami pieców, które mogą przyczynić się do oszczędnego gospodarowanie energią elektryczną podczas długotrwałych procesów technologicznych.

EN

Satisfying results obtained in technologies using the glow discharge processes, played down the globar constructional solutions of installations and planning of processes from the point of view of rational use of energy. In the paper the features of abnormal glow discharge, applied to nitriding parts of various shapes, are presented. The observed relations between energy characteristics of glow discharge and heat losses were given. On the ground of experiments was determined the cooperation of supply units with different constructions of furnaces, that could make possible the saving of electric energy used at longlasting technological processes.