Search results for "CORROSION"

The influence of phosphoric acid on steel and on its corrosion products: a Mössbauer spectroscopic approach

1983

Mossbauer spectroscopy was used to study corroded iron after treatment with phosphoric acid or commercial rust transformers. It was found that treatment produced normal iron phosphates from metallic iron, hematite and FeO, and acid ferric phosphate FeH 3 (POI4I)I2I. 2.5H 2 O from alphaand gamma Fe 2 O 3 and alpha, beta, and gammaFeOOH. When these last are present, phosph oric acid treatment does not produce a protective, inhibiting layer. See also AATA 19-702. -- AATA

Über die Inhibitoren der Korrosion IV(1). Versuche zur Unterdrückung der Auflösung von Aluminium durch organische Substanzen in saurer und alkalische…

1965

Oniumsalze oder potentielle Oniumsalze sind wirksame Inhibitoren der Auflosung von Aluminium in Salzsaure. Ihr Schutz ist im alkalischen Medium geringer. Corrosion Inhibitors IV. Investigations into the suppression of the dissolution of aluminium by organic substances in acid and alkaline solution Onium salts or potential onium salts are effective inhibitors in respect of the dissolution of aluminium in hydrochloric acid. In the alkaline medium, the protective effect is less marked.

Spontaneous periodic and bursting current oscillations in iron corrosion by dichromate: a useful study for simulating biological systems

1995

Abstract Studies on chemical and electrochemical oscillating systems are very useful in understanding more complex biological systems. Spontaneous periodic and bursting current oscillations were found in iron/dichromate systems coupled with graphite or zinc electrodes. In this paper, we study some phenomenological features of the two systems: their typical oscillation profiles and the influence of external resistance. The results are explained by the Franck-Fitzhugh model using the mixed potential theory.

An ESCA and Mössbauer study of the oxide layer formed on steel in water containing chromate and chloride ions

1983

Abstract The formation of oxidic layers on steel in chromate solutions was studied by photo-electron and Mossbauer spectroscopy. To simulate more aggressive realistic systems, some chloride ions were added to the solution. The layers formed under these conditions were found to be thicker by an order of magnitude than those formed in the absence of chloride ions. They probably consist of ferric and chromic oxides of the corundum type (Fe 1−2 Cr x ) 2 O 3 , with the Cr : Fe ratio being depth dependent. The oxide layer is subdivided into small regions behaving superparamagnetically. This heterogeneity of the layer is ascribed to the attack by the chloride ions. The structure of the oxides foun…

Electronic properties and corrosion resistance of passive films on austenitic and duplex stainless steels

2018

Abstract Passive films were grown at constant potential in acidic (pH∼2) and alkaline (pH∼13) solutions on chromium, AISI 304L, AISI 316L and Duplex stainless steels. Passive films on chromium grow following a high field mechanism considering the presence of dissolution phenomena. According to the photoelectrochemical characterization, passive films on Cr have a bandgap of 3.4 eV when formed in acidic solution, and of 2.4 eV when formed in alkaline solution due to the formation of Cr(OH)3. These films result to be poorly stable against anodic dissolution due to a very anodic flat band potential. Conversely, impedance and photoelectrochemical measurements proved that passive films on stainle…

Use of Ultrasound in Reconditioning by Welding of Tools Used in the Process of Regenerating Rubber

2018

Addressing the problem of reconditioning large parts is of particular importance, due to their value and to the fact that the technologies for their reconditioning are very complex. The tools used to refine regenerated rubber which measure 660 mm in diameter and 2130 mm in length suffer from a rather fast dimensional wear. Within this research, the authors looked for a welding reconditioning procedure that would allow a very good adhesion between the deposited material layer and the base material. In this regard, the MAG (Metal Active Gas) welding process was used, but the ultrasonic activation of the welding process was also considered. Thus, the wire used for welding was activated conside…

Magnesium alloys laser (Nd:YAG) cladding and alloying with side injection of aluminium powder

2003

International audience; The development of the high purity magnesium alloys (such as WE43) incites the designers to reconsider them, and the car industry appears, these days, the most interested to use this kind of alloy. However, due to their ignitability and tendency to oxidation, magnesium alloys require surface treatments. A series of experiments was carried out in order to improve the corrosion resistance of two types of magnesium alloys, WE43 and ZE41. In most cases, the substrate surface was treated before laser interaction. Side injection of aluminium powder under a 3 kW cw Nd:YAG laser was employed. The deposited layers present very good bond properties. The resulting microstructur…

MoSi2 laser cladding—elaboration, characterisation and addition of non-stabilized ZrO2 powder particles

2003

International audience; The cladding process using laser beam radiation comprises different operational regimes, depending on the involved lasers (usually CO2 or Nd:YAG) and materials. A series of experiments has been carried out to investigate Nd:YAG laser cladding using MoSi2 powder. Procedures and operating parameters for producing clad layers has been developed and their properties evaluated. The feasibility of the laser cladding technique, using a high power Nd:YAG laser, by projecting MoSi2 powder on steel substrate was demonstrated. The results indicate a low density of cracks, elevated powder catchment efficiency (between 65 and 90%) and hardness values around 1200–1300 HV. Our goal…

Fabrication of Chitosan-Silver Nanoparticles composite coatings by galvanic deposition for orthopaedic implants

Electroplated Ni/Ni-Co multilayer coatings for higher corrosion-erosion resistance

2019

Erosion-corrosion behaviour of hierarchical structured hydrophobic nickel-cobalt coating, obtained by electrodeposition, was assessed. In situ electrochemical measurements were carried out to study the corrosion resistance and stability during erosion tests. The electrochemical behaviour was related to surface hydrophobicity and its hierarchical structure nature as well as its modification. The pure Ni showed the lowest erosion-corrosion resistance. A smoothing of the hierarchical structure and thus a reduction the hydrophobicity was highlighted. On the other hand, Ni-Co coating even if associated to a lower electrochemical stability showed a more stable hierarchical structure also at high …