Comparative Analysis Over Tribology Characterization of TiAlN and TiAlSiN PVD Coating On Plasma Nitride Alloy 20

The nickel-iron-chromium (alloy 20) is enriching by hybrid surface treatment through plasma nitride (PN) and physical vapor deposition (PVD) process. The plasma nitriding process takes 12 hours at 500°C. Potentiodynamic testing is used to characterize the corrosion performance of the treated material, followed by morphological analysis of the exposed surface; XRD, EDX, SEM, hardness, and tensile testing are used to investigate appropriate coating properties. Plasma nitride and hybrid PVD nickel-iron-chromium alloys exhibit perlite (γ + α ’) phases and martensite (γ + α) phases, respectively. The martensite microstructure ensures superior tensile strength and hardness. The pin-on-disc tribometer test proposes to analyze friction and hard-faced behavior in the dry sliding position. The inclusion of Si improves the adherent oxide film, resulting in a low wear rate in TiAlSiN alloy 20. Due to the presence of the passive film, TiAlSiN alloy 20 exposes the most passive region to attain better corrosion resistance.

Effects of ultrasonic surface rolling and plasma nitriding on microstructure and properties of 690TT alloy

To enhance surface mechanical properties of 690TT alloy, a surface hardening layer was obtained by ultrasonic surface rolling treatment (USRT) and plasma nitriding (PN). The surface morphology, mechanical properties, wear performances and corrosion performance were investigated by XRD, TEM, using a hardness tester, tensile tester, wear tester and electrochemical workstation in simulated sea water, respectively. The results showed that USRT as the pre-treatment can strengthen the performance of PN treatment samples. The USRT+PN treated sample showed existence of dislocation tangles and twin grains. Corrosion resistance in simulated sea water was enhanced. The surface microhardness increased by 180 % compared with the untreated sample, the cross-sectional hardness gradually decreased till the depth of 1mm. The tensile strength increased by a factor of 90% while the elongation decreased by only 40%. The wear scar was narrower and shallower than the untreated sample and the wear rate was significantly dropped. This paper aims at providing a new method for surface strengthening of 690TT alloy.

The Effect of Plasma Nitridation on Surface Hardness of Titanium Alloy (Ti-6Al-4V) for Artificial Knee Joint Applications

Nitriding has been carried out using plasma nitriding techniques for surface treatment of Titanium as a biomaterial component. The purpose of this study was to determine the effect of plasma nitriding on surface hardness that occurs in titanium. The material used is Titanium Alloy (Ti-6Al-4V) Grade 5 which is processed by plasma nitriding by varying nitrogen (N2) and argon (Ar) gases of (100% N2/0% Ar), (95% N2/5% Ar), (90% N2/10% Ar), (85% N2/15% Ar), (80% N2/20% Ar), and (75% N2/25% Ar), and temperature 400ºC, time 5 hours and a pressure of 1.6 bar. The test results show that the optimum hardness is found in the gas composition with a ratio of 95% N2: 5% Ar. Obtained a hardness of 371 HV/VHN or an increase of 159% of the raw material with hardness value of 143 HV/VHN

Aluminum surface nitriding by an atmospheric-pressure non-thermal plasma technique

The application of aluminum is often limited by low hardness, and plasma nitriding can make it have excellent mechanical property. The purpose of this study is to nitride the aluminum surface by non-thermal transferred arc plasma technology. During the plasma nitriding process, the maximum effective value of output current is about 390 mA and the overall temperature of the samples is much lower than the solidus temperature. It is found that the microstructure and mechanical properties of the aluminum surface are improved by adding hydrogen into the nitrogen plasma. Compared with the surface treated by pure N2 plasma, the particle size of aluminum surface treated by N2/H2 plasma is smaller. The surface hardness of aluminum is nearly doubled after being treated in 6.0 vol%H2 + 94.0 vol%N2 atmosphere.

Verbesserte Tribokorrosionsbeständigkeit des martensitischen Stahls X54CrMoVN17-1 durch die Erzeugung von expanded martensite

Seal-free, media-lubricated rolling bearings have a high-energy efficiency as the absence of the seal minimizes frictional loss and increases the efficiency of the driven machine. In addition, the environment is protected by the absence of hazardous lubricants. However, media-lubrication increases tribocorrosive attack on the bearing surface. Therefore, the tribocorrosion resistance of the bearing surface can be increased by a thermal surface treatment called low-temperature plasma nitriding. The produced “expanded martensite” in martensitic steels features a high hardness with comparatively good corrosion resistance. Tribocorrosion tests in 0.9 % NaCl-solution show that the material loss could be reduced by 70 % due to expanded martensite compared to the initial state of the steel.

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.

Pulsed plasma nitriding of high velocity oxy-fuel sprayed Inconel 625 coatings

A hardening of high velocity oxy-fuel sprayed Inconel 625 coating systems was performed by pulsed plasma nitriding treatment. After deposition of an Inconel 625 coating, samples were pulsed plasma nitrided at 520 °C for 12 h in a gas ratio of 3:1 N2 and H2 under a constant pressure of 2.5 × 102 Pa. Pulsed plasma nitriding improved the microhardness of the high velocity oxy-fuel sprayed Inconel 625 coating from 355 to 401 HV0.05. The high velocity oxy-fuel-sprayed Inconel 625 coating after pulsed plasma nitriding process showed excellent corrosion resistance as well as a reduction of both the friction coefficient and wear rate during the sliding phase in a 3.5 wt.% NaCl solution against sliding action of Al2O3 ball.