Corrosion Behaviour of Steel Nitrided and Nitrocarburized in Gas, Respectively

2015 ◽  
Vol 365 ◽  
pp. 278-284
Author(s):  
Hisao Fujikawa ◽  
H. Iwamura ◽  
M. Uramoto
Keyword(s):  
Corrosion Test ◽  
Corrosion Behaviour ◽  
Plasma Nitriding ◽  
Salt Spray ◽  
Salt Bath ◽  
Carbon Steels ◽  
Test Method ◽  
Oxidation Treatment ◽  
Gas Nitriding ◽  
Nitride Layers

Nitriding treatment is well known as one of the corrosion protection methods for steels as well as a way to prevent wear and fatigue. Initially, salt bath nitrocarburizing was popular, but recently, gas nitriding, gas nitrocarburizing, plasma nitriding and so on have come to be used more often because of their superior nitriding ability. In the case of nitriding, only nitrogen (N) diffuses into the steel, but in the case of nitrocarburizing, both nitrogen and carbon (C) diffuse into the steel. General speaking, nitriding includes all the treatments mentioned above. The corrosion behavior of nitride carbon steels has been understood mainly by salt bath or gas nitrocarburizing treatments1)-4).However, recently, nitriding is mainly applied to parts for things such as automobiles which need protection from wear and fatigue, and is seldom used for parts which need corrosion resistance. The present paper is to remind researchers again that nitrided steels show good corrosion resistance.Therefore, the comparison of various thicknesses of nitride layers as well as the comparison between nitride layers on steel has been carried out in this examination, using the salt spray corrosion test method. The effect of oxidation treatment after nitriding was also investigated.

Preparation and Corrosion Behaviour of Micro-Arc Oxidation Coating on Ti6Al4V Alloy

2012 ◽  
Vol 621 ◽  
pp. 117-120
Author(s):  
Xiu Zhou Lin ◽  
Min Gong ◽  
Zhao Hua Wang ◽  
Peng Zhang
Keyword(s):  
Corrosion Resistance ◽  
Corrosion Potential ◽  
Corrosion Behaviour ◽  
Salt Spray ◽  
Corrosion Current ◽  
Ti6al4v Alloy ◽  
Oxidation Time ◽  
Oxidation Treatment ◽  
X Ray ◽  
Micro Arc Oxidation

Micro-arc oxidation (MAO) coatings were prepared on Ti6Al4V alloys surface by using self-made micro-arc oxidation equipment. Its characterizations were systematically detected by Vickers hardness tester, scanning electron microscope (SEM), X-ray diffractometer (XRD) and X-ray fluorescence spectrometer (XFS). Corrosion behaviour of MAO coating and Ti6Al4V alloy in Hank's simulated body fluid were studied comparatively using electrochemical workstations and salt spray test chamber. The experimental results indicated that the MAO coating, with rough surface, high hardness and typical porous ceramic structure, is mainly consist of anatase and rutile TiO2 phase. Micro-arc oxidation treatment can significantly improve corrosion resistance of Ti6Al4 alloy, and the corrosion resistance of the coating is observably affected by the coating technology. During the micro-arc oxidation treatment, the thickness of the coating increases with the increase of oxidation time, which induce that the corrosion potential and polarization resistance of the coating increase, and the corrosion current reduce. Simultaneously, the thicker the coating, the higher the pitting resistance is. On the other hand, under the same oxidation time, as the current density increases during micro-arc oxidation treatment, the corrosion potential of the coating positive shifts, and the corrosion current reduces.

scholarly journals (Ti,Al)O2 Whiskers Grown during Glow Discharge Nitriding of Ti-6Al-7Nb Alloy

Materials ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2658
Author(s):  
Krzysztof Szymkiewicz ◽  
Jerzy Morgiel ◽  
Łukasz Maj ◽  
Małgorzata Pomorska
Keyword(s):  
Surface Hardening ◽  
Surface Defects ◽  
Plasma Nitriding ◽  
Surface Roughening ◽  
Effective Surface ◽  
Plan View ◽  
Gas Nitriding ◽  
Transmission Electron ◽  
Temperature Window ◽  
20 Nm

Plasma nitriding of titanium alloys is capable of effective surface hardening at temperatures significantly lower than gas nitriding, but at a cost of much stronger surface roughening. Especially interesting are treatments performed at the lower end of the temperature window used in such cases, as they are least damaging to highly polished parts. Therefore identifying the most characteristic defects is of high importance. The present work was aimed at identifying the nature of pin-point bumps formed at the glow discharged plasma nitrided Ti-6Al-7Nb alloy using plan-view scanning and cross-section transmission electron microscopy methods. It helped to establish that these main surface defects developed at the treated surface are (Ti,Al)O2 nano-whiskers of diameter from 20 nm to 40 nm, and length up to several hundreds of nanometers. The performed investigation confirmed that the surface imperfection introduced by plasma nitriding at the specified range should be of minor consequences to the mechanical properties of the treated material.

ANTICORROSION PERFORMANCE OF SELF-HEALING POLYMERIC COATINGS ON LOW CARBON STEEL SUBSTRATES

2017 ◽  
Vol 79 (7-4) ◽  
Author(s):  
Muhammad Ashraff Ahmad Seri ◽  
Esah Hamzah ◽  
Abdelsalam Ahdash ◽  
Mohd Fauzi Mamat
Keyword(s):  
Steel Substrate ◽  
Salt Spray ◽  
Immersion Test ◽  
Salt Spray Test ◽  
Test Method ◽  
The Self ◽  
Self Healing ◽  
Pure Epoxy ◽  
Steel Substrates ◽  
Epoxy Paint

Recently, self-healing coating is classified as one of the smart coatings which has the ability to heal or repair damage of the coating to prevent further corrosion. The aim of this study is to synthesize the self-healing coatings from polymeric material and evaluate the performance and their corrosion behavior when coated on steel substrates. The corrosion tests were performed using immersion test and salt spray test method at room temperature. The immersion test shows that self-healing coating gives lower corrosion rate compared to pure epoxy paint, with a value of 0.02 and 0.05 mm/year respectively. Also, salt spray test shows similar trend as the immersion test, which is 0.11 and 0.19 mm/year for self-healing coating and pure epoxy paint respectively. While uncoated samples without any protection corroded at 0.89 mm/year. It was also found that the damage on self-healing coating was covered with zeolite from the microcapsules indicating that the self-healing agent was successfully synthesized and could function well. In other words, self-healing coating shows better corrosion resistance compared to the pure epoxy coating on steel substrate.

The Study of Electroless Ni-P and Ni-P-PTFE Coating on Steel Tire Mold

2012 ◽  
Vol 501 ◽  
pp. 316-320
Author(s):  
Jian Zhang Guo ◽  
Bin Xu
Keyword(s):  
Wear Resistance ◽  
Corrosion Resistance ◽  
Pore Structure ◽  
Energy Dispersive Spectrometer ◽  
Salt Spray ◽  
Amorphous Structure ◽  
Carbon Steels ◽  
Electrochemical System ◽  
Electroless Ni ◽  
Scanning Electron

In order to improve the surface property of the steel tire mold, carbon steels were processed by electroless Ni-P and Ni-P-PTFE under contrast experiment. The coatings were characterized by Scanning Electron Microscopy (SEM) and Energy Dispersive Spectrometer (EDS). The wear resistance and corrosion resistance of the coatings were explored by tribometer, salt spray cabinet and advanced electrochemical system. The experimental results showed that the Ni-P coating was amorphous structure, and the Ni-P-PTFE coating was micro-pore structure; The wear resistance of Ni-P-PTFE coating was superior to Ni-P coating; In view of the micro-pore structure, the corrosion resistance of Ni-P-PTFE coating was worse than Ni-P coating, but they were all superior to carbon steels, and the service life of the steel tire mold were improved.

Electrochemical and Salt Spray Corrosion Behavior of Copper Alloy Contact Wires in Chloride Solution

2014 ◽  
Vol 789 ◽  
pp. 622-626
Author(s):  
Peng Chao Zhang ◽  
Jian Zhang ◽  
Jin Chuan Jie ◽  
Yuan Gao ◽  
Yong Dong ◽  
...  
Keyword(s):  
Corrosion Behavior ◽  
Corrosion Test ◽  
Chloride Solution ◽  
Copper Alloys ◽  
Salt Spray ◽  
Electrochemical Corrosion ◽  
Corrosion Current ◽  
Corrosion Mechanism ◽  
Salt Spray Corrosion ◽  
Surface Morphologies

The effect of different alloying elements on corrosion behavior of copper alloys was investigated using electrochemical corrosion and salt spray corrosion test in NaCl solution. Cu-Ag has the most stable corrosion current in the potentiostatic scanning test, exhibiting a better corrosion resistant performance. It can be analyzed from corrosion surface morphologies that Cu-Ag presents exfoliation corrosion mechanism while Cu-Sn shows crevice corrosion mechanism. Cu-Mg has a complex corrosion process caused by multiple corrosion mechanism. In the salt spray corrosion test, the corrosion degree of Cu-Ag is lighter than those of Cu-Sn and Cu-Mg after 24h test. Therefore, the Cu-Ag alloy exhibits the best corrosion resistance in chloride solution.

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