Showing 7 results for Plasma Nitriding
H. Aghajani, M. Soltanieh, F. Mahboubi, S. Rastegari and Kh. A. Nekouee,
Volume 6, Issue 1 (3-2009)
Abstract
Abstract: Formation of a hybrid coating by the use of plasma nitriding and hard chromium electroplating on the
surface of H11 hot work tool steel was investigated. Firstly, specimens were plasma nitrided at a temperature of 550
°C for 5 hours in an atmosphere of 25 vol. % H2: 75 vol. % N2. Secondly, electroplating was carried out in a solution
containing 250 g/L chromic acid and 2.5 g/L sulphuric acid for 1 hour at 60 °C temperature and 60 A/dm2 current
density. Thirdly, specimens were plasma nitrided at a temperature of 550 °C for 5 and 10 hours in an atmosphere of
25 vol. % H2: 75 vol. % N2. The obtained coatings have been compared in terms of composition and hardness. The
compositions of the coatings have been studied by X-ray diffraction analysis. The surface morphology and elemental
analysis was examined by using scanning electron microscopy. The improvement in hardness distribution after third
step is discussed in considering the forward and backward diffusion of nitrogen in the chromium interlayer. Also, the
formed phases in the hybrid coating were determined to be CrN+Cr2N+Cr+Fe2-3N+Fe4N.
Arash Yazdani, Mansour Soltanieh, Hossein Aghajani,
Volume 6, Issue 4 (12-2009)
Abstract
Abstract: In this research plasma nitriding of pure aluminium and effect of iron elemental alloy on the formation and growth of aluminium nitride was investigated. Also corrosion properties of formed AlN were investigated. After preparation, the samples were plasma nitrided at 550oC, for 6, 9 and 12 h and a gas mixture of 25%H2-75%N2. The microstructure and phases analysis were investigated using scanning electron microscopy and X-ray diffraction analysis. Moreover corrosion resistance of samples was investigated using polarization techniques. The results showed that only a compound layer was formed on the surface of samples and no diffusion zone was detected. Dominant phase in compound layer was AlN. Scanning electron microscopy results showed that nitride layer has particulate structure. These nitrided particles have grown columnar and perpendicular to the surface. It was also observed that the existence of iron in the samples increases the nitrogen diffusion, thus growth rate of iron containing nitrides are higher than the others. Corrosion tests results showed that formation of an aluminium nitride layer on the surface of aluminium decreases the corrosion resistance of aluminium significantly. This is due to elimination of surface oxide layer and propagation of cracks in the formed nitride layer
S. M. M. Shafiei, M. Divandari, S. M. A. Boutorabi, Naghizadeh,
Volume 12, Issue 2 (6-2015)
Abstract
In this work, TiN/TiCN & PN/TiCN multilayer films were deposited by plasma- assisted chemical vapour
deposition (PACVD). Plasma nitriding (PN) and TiN intermediate layer prior to coating leads to appropriate hardness
gradient and it can greatly improve the mechanical properties of the coating. The composition, crystalline structure
and phase of the films were investigated by X-ray diffraction. Atomic force microscopy and scanning electron
microscopy were employed to observe the morphology and structure of the films. The TiCN layer exhibited a columnar
structure. The adhesion force between the film and the tool steel substrate was 30.8 MPa for TiN/TiCN and 25.4 MPa
for PN/TiCN film determined by pull off tests. The hardness of TiN/TiCN film was 12.75 GPa while it was 5.4 GPa for
PN/TiCN film, respectively. The improvement of the adhesion in TiN/TiCN was attributed to a less gradient hardness
configuration. In addition, the mean friction coefficients of the films were about 0.2 for TiN/TiCN and 0.3 for PN/TiCN
film determined by nanoindentation tests.
M. Soltanieh, M. Kiani, M. Hasheminiasari,
Volume 14, Issue 2 (6-2017)
Abstract
- The mechanism of diffusion layer growth in plasma nitrided coatings applied on a St52 steel using an active screen is investigated. The nitriding was performed at 450,500 and 550 ◦C temperature nitriding times of 5, 10 and 15 h, in a gas mixture containing 20 vol. % H2: 80 vol. % N2 and DC-pulsed plasma nitriding unit.
The surface, cross section and the thickness of diffusion of specimens was studied in terms of optical and scanning electron microscopy. According to the measurements of diffusion layer thickness, values of Q and D0 for nitrogen diffusion in substrate were calculated as 50585 (j/mol) and 4.11×10-10 (m2/s)respectively. The variations of depth of hardness during nitriding period was determined
A. Jafari Tadi, S.r. Hosseini, M. Naderi Semiromi,
Volume 14, Issue 3 (9-2017)
Abstract
Influence of formation of surface nano/ultrafine structure using deep rolling on plasma nitriding and tribological properties of the AISI 316L stainless steel was investigated. Initially, the deep rolling process was carried out on the bar-shaped specimens at 15 cycles with 0.2 mm/s longitudinal rate and 22.4 rpm bar rotation. Then, plasma nitriding treatment was applied on the as-received and deep rolled kinds at 450 °C and H2-25% Vol. N2 gas mixture for 5 h. Surface micro-hardness and un-lubricated pin-on-ring sliding wear tests were carried out on the as-received, deep rolled, plasma nitrided and deep rolled-plasma nitrided kinds. Results revealed that deep rolled-plasma nitrided kind is shown the highest wear resistance than the others, due to the further increased surface hardness achieved via the combined process.
R. Kumar, Y. Chandra Sharma, V. Vidya Sagar, D. Bhardwaj,
Volume 17, Issue 2 (6-2020)
Abstract
In this study an effort has been made for the plasma ion nitriding (PIN) of Inconel 600 and 601 alloys at low temperatures. After plasma ion nitriding, microstructure study, growth kinetics of nitrided layer formation and wear properties were investigated by various characterization techniques such as; scanning electron microscope (SEM), X-ray diffraction (XRD) analysis, micro-hardness measurement and wear test by pin on disk technique. It was found that, surface micro-hardness increases after PIN process. A mix peak of epsilon (ε) phase with fcc (γ) phase was detected for all temperature range (350 0C to 450 0C), while the chromium nitride (CrN) phase was detected at elevated temperature range ~450 0C in inconel 601 alloy. The calculated values of diffusion coefficient and activation energy for diffusion of nitrogen are in accordance with the literature. Volume loss and wear rate of the plasma nitrided samples decreases, but it increases as PIN process temperature increases.
S. Karimzadeh, F. Mahboubi, G. Daviran,
Volume 17, Issue 4 (12-2020)
Abstract
In the present investigation effects of time and temperature on plasma nitriding behavior of DIN 1.2344 (AISI H13) steel are studied. Pulsed plasma nitriding process with a gas mixture of N2 = 25% + H2 = 75% and duty cycle of 70% is applied to cylindrical samples of DIN 1.2344 hot work tool steel. X-ray diffraction, surface roughness, microhardness and ball on disc wear test are performed and behavior of plasma nitrided samples are compared. Scanning electron microscopy and optical microscopy are used in order to observe the microstructure of samples after nitriding. XRD results showed that the compound layer is dual phase. Hardness near the surface dropped by rising the process temperature and it rose in longer process durations. The comparison of µ results showed frictional properties in longer durations with lower temperatures is approximately the same in higher temperatures with shorter durations.
