Near Superhydrophobic Carbon Nanotube Coatings Obtained via Electrophoretic Deposition on Low‐Alloy Steels

Sucker rods are a key element in certain oil-extraction processes as they link the motor group on the surface with the pumps located downhole. During the transport from the production site toward the extraction well, these components are prone to corrosion. A hydrophobic carbon nanotube (CNT) coating, deposited via electrophoretic deposition (EPD), is proposed as a protective layer, shielding the rods from harsh environmental conditions. Three different coating systems are considered and thoroughly characterized (depending on the additive that is used to deposit the CNT), namely, magnesium nitrate hexahydrate (Mg–Nit), triethylamine (TEA), and a duplex coating (DD). The latter presents an approach which combines the advantages of each additive, mechanical stability from Mg–Nit and strong hydrophobicity from TEA (near superhydrophobic). The former coatings are further processed to overcome their individual shortcomings, resulting in an increase in the coating's stability for TEA coating, as well as transforming the hydrophilic Mg–Nit surface into a hydrophobic surface

Influence of the pre-treatments and process temperature on the adhesion of tin films deposited by PBII&D over nitrided austenitic stainless steel

In this work the influence of pre-treatment cleaning processes in the adhesion of TiN films deposited by the plasma based ion implantation and deposition (PBII&D) process over plasma nitrided AISI 316L stainless steel was investigated, varying the gas composition, the duration of the sputtering process and the temperature in the same deposition chamber. The TiN film morphology was scrutinized with scanning electron microscopy on the surface complemented with focus ion beam for the cross section. The film microstructure was characterized with X ray diffraction. The adhesion of the coatings was studied using the Scratch Test with constant load at different values and the Rockwell C indentation method as well. It was found that only with the sputtering carried out in a H2 - Ar gas mixing at 300 ºC temperature used as pre-treatment was successful to prepare the nitrided surface for the subsequent TiN deposition by the PBII&D process.Fil: Vaca, Laura Silvia. Universidad Tecnológica Nacional. Facultad Regional Concepción del Uruguay; ArgentinaFil: Quintana, Juan Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física del Plasma. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física del Plasma; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Física; ArgentinaFil: Guitar, María Agustina. Universitat Saarland; AlemaniaFil: Vega, Daniel. Comisión Nacional de Energía Atómica. Gerencia de Área Investigaciones y Aplicaciones No Nucleares. Gerencia Física (CAC). Departamento de Física de la Materia Condensada; ArgentinaFil: Brühl, Sonia Patricia. Universidad Tecnológica Nacional. Facultad Regional Concepción del Uruguay; ArgentinaFil: Marquez, Adriana Beatriz. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Física; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física del Plasma. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física del Plasma; Argentin

Comparative analysis of DLC and TiSiCN hard coatings against wear and corrosion

La vida en servicio de elementos de máquinas utilizados en la industria del gas y del petróleo puede ser extendida con el uso de recubrimientos que permiten mejorar las propiedades superficiales, como la resistencia al desgaste y a la corrosión. Los recubrimientos DLC son conocidos por su bajo coeficiente de fricción, alta resistencia al desgaste e inercia química. Las películas del tipo TiSiCN son cerámicas duras, por lo que otorgan una buena resistencia al desgaste abrasivo y erosivo. En este trabajo se analizan de forma comparativa estosdos recubrimientos cuando son depositados sobre un acero de media aleación AISI 4140. Se midió espesor y se hizo caracterización por XPS, DRX y espectroscopía Raman. Se realizaron ensayos de desgaste adhesivo tipo Pin-on-Disk y desgaste abrasivo (ASTM G65). Se evaluó la adhesión por Scrach Test. La resistencia a lacorrosión se evaluó mediante cámara de niebla salina y ensayos potenciodinámicos. El DLC presentó un bajo coeficiente de fricción μ ~ 0,2, con una pérdida de volumen dos veces menor que el TiSiCN, mientras que este último presentó una resistencia al desgaste abrasivo 30 veces superior. La adhesión del TiSiCN también fue superior. El DLC mostró una mayor resistencia a la corrosión.Service life of machine parts used in the oil and gas industry can be expanded by using coatings that improve surface properties such as wear and corrosion resistance. DLC coatings are known for their low friction coefficient, high wear resistance and chemical inertness. TiSiCN films are hard ceramics, so they provide good resistance to abrasive and erosive wear. In this work, these two coatings deposited on alloy steel AISI 4140 are comparatively analyzed. Thickness was measured and the coatings were characterized by XPS, DRX and Raman spectroscopy. Pin-on-disk adhesive wear and abrasive wear tests (ASTM G65) were carried out. Adhesion was evaluated by scratch test. Corrosion resistance was evaluated by salt spray test and potentiodynamic tests. DLC coatings presented low friction coefficient μ ~ 0,2, and a volume loss twice as low as TiSiCN, whereas the latter presented 30 times the abrasive wear resistance. The adhesion of TiSiCN was also superior. DLC showed higher corrosion resistance.Fil: Carmona, Aníbal Emilio. Universidad Tecnológica Nacional. Facultad Regional Concepción del Uruguay; ArgentinaFil: Delfín, Francisco Andrés. Universidad Tecnológica Nacional. Facultad Regional Concepción del Uruguay; ArgentinaFil: Maskavizan, Ana Justina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Tecnológica Nacional. Facultad Regional Concepción del Uruguay; ArgentinaFil: Brühl, Sonia Patricia. Universidad Tecnológica Nacional. Facultad Regional Concepción del Uruguay; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Mikroskopische Untersuchung von Lochkorrosion an Plasmanitriertem austenitischem rostfreiem Stahl

UNS 31603 austenitic stainless steel was nitrided using different techniques, and pitting corrosion resistance was analysed in a chloride solution. All nitriding techniques, LEII, PI· and convectional DC nitriding produced a nitrided layer called S phase which is corrosion resistant. Pits morphology and layer structure was investigated using optical and electronic microscopy, SEM-FIB, EDS, and a 3D reconstruction of a pit was assessed using FIB tomography. It was concluded that pits are initiated in MnS inclusions and a channel was generated passing through the nitrided layer, connecting the steel with the electrolyte. Base alloy dissolution was observed beneath the nitrided layer.Fil: Escalada, Lisandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; ArgentinaFil: Brühl, Sonia Patricia. Universidad Tecnológica Nacional. Facultad Regional Concepción del Uruguay; ArgentinaFil: Simison, Silvia Noemi. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; Argentin

Tribological behaviour of nitrided and nitrocarburized carbon steel used to produce engine parts

Purpose – The purpose of this study is to select a proper surface treatment to enhance wear resistance of engine camshafts. The camshaft is a relevant part of a diesel engine which works under torsion, fatigue and wear efforts. They are usually manufactured by casting, forging or machining from forged bar of low alloy steels, and in most cases, the machined surfaces are quenched and tempered by induction heating. After that, in many cases, to withstand the efforts imposed on the active surfaces and improve tribology and fatigue properties, the industry used for decades, thermochemical technologies such as salt bath or gaseous nitriding and nitrocarburizing processes. Design/methodology/approach – This paper studied the effects of plasma nitriding and plasma nitrocarburizing, on the tribological behaviour of the steel SAE 1045HM3 proposed to produce camshafts. After the plasma treatments, the change in surface roughness was measured; the modified layers were studied by X-ray techniques and its thickness by optical microscopy. The diffusion zone was evaluated by Vickers microhardness determinations. Tribology tests were performed by pin-on-disc configuration using WC ball as a counterpart. Findings – Results show that plasma nitrided samples present the best tribological behaviour compared with the nitrocarburized ones; also, the influence of the roughness produced by the thermochemical processes appears to be important. Practical implications – Although both the plasma treatments have been applied for many years, and also reported separately in the scientific literature, there was no information comparing these two treatments for carbon steels, and also, there is not much about tribology in lubricated conditions of nitrided and nitrocarburized carbon steels. In fact, it is not proved that the porosity of the nitrocarburized layer is beneficial for wear resistance in lubricated conditions. In this paper, it was proved that at least in the tested conditions, it is not. Originality/value – Gas or plasma nitrocarburizing is usually recommended for this kind of applications, although the modified layer is porous. This paper attempts to prove that nitriding could be better than nitrocarburizing, even with a thinner white layer.Fil: Brühl, Sonia Patricia. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Tecnológica Nacional. Facultad Regional Concepción del Uruguay; ArgentinaFil: Amado Cabo. IONAR S.A.; ArgentinaFil: Tuckart, Walter Roberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca; Argentina. Universidad Nacional del Sur. Departamento de Ingeniería; ArgentinaFil: Prieto, Germán. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca; Argentina. Universidad Nacional del Sur. Departamento de Ingeniería; Argentin

Sliding friction and wear behaviour of ion nitrided and TiN coated AISI 4140 steel

This work studies the friction and the sliding wear behaviour of surface treated SAE 4140 steel. The performance of ion nitriding and PVD TiN coatings applied by means of industrial processes as single or duplex treatments was evaluated. Although the deposited TiN coatings (0.7 µm thick) resulted thinner than most of the typically employed for sliding situations, the present work shows that they can provide very good protection. The use of ion nitriding as a pretreatment proved to be beneficial when combined with such a thin coating. However, in the pin on disc sliding tests the coated discs developed the highest friction coefficients and boosted the damage in the steel pins.Fil: Mandri, Alejo Daniel. Universidad Nacional de Mar del Plata. Facultad de Ingeniería; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; ArgentinaFil: Colombo, Diego Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; ArgentinaFil: Brühl, Sonia Patricia. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Tecnológica Nacional. Facultad Regional Concepción del Uruguay; ArgentinaFil: Dommarco, Ricardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; Argentin

Comparison of tribological properties of stainless steel with hard and soft DLC coatings

Stainless steels are widely used in chemical, petrochemical and food-processing industries due to their good anticorrosion properties. However, they generally exhibit poor tribological properties which limit their applications in tribocorrosive conditions. Surface modifications, like diamond-like carbon (DLC) coatings, can be an optimal technological solution to overcome this problem. These films have attracted considerable attention because of their outstanding mechanical and tribological properties, but they have a major drawback that is their high internal stresses and low thermal stability. The internal stresses and film hardness depend on the ratio sp2/sp3, therefore, the film can be classified as hard or soft-DLC coatings depending on this ratio. In this work, different stainless steels (EN14301, EN14435 and EN12316) samples were DLC-coated by plasma assisted chemical vapor deposition. Hard and soft a-C:H:Si films (silicon containing amorphous hydrogenated carbon) were obtained. The films were characterized by wear and adhesion tests; the results show an increase of the practical adhesion at higher film thickness and this improvement would be more effective for harder substrates. Pin-on-disc tests showed that soft-DLC films tend to develop a better tribological behavior than hard-DLC films and it is not influenced by the film thickness or the type of stainless steel substrate. The influence on the tribological behavior of test parameters, such as slide velocity and load, varies with the coating type.Fil: Gasco Owens, Ana. Universidad Nacional de Mar del Plata. Facultad de Ingeniería; ArgentinaFil: Brühl, Sonia. Universidad Tecnologica Nacional. Facultad Regional Concepcion del Uruguay; ArgentinaFil: Simison, Silvia Noemi. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Mar del Plata. Instituto de Investigación En Ciencia y Tecnología de Materiales (i); Argentina. Universidad Nacional de Mar del Plata. Facultad de Ingeniería; ArgentinaFil: Forsich, Christian. Upper Austria University of Applied Sciences; AustriaFil: Heim, Daniel. Upper Austria University of Applied Sciences; Austri

Impact of relative humidity and deposition parameters on the tribological behavior of soft DLC coatings

When diamond-like carbon coatings are produced with plasma-assisted CVD, a softer but thicker DLC variant with excellent tribological behavior can be achieved. Due to great adhesion and load-bearing capacity, they can be deposited on low-alloy steels, commonly used in mechanical engineering, to reduce energy consumption and extend the lifespan of machine components. In this work, soft a-C:H coatings were deposited over AISI 4140 steel using a modified commercial PA-CVD system, with acetylene as carbon precursor. Two kind of coatings were deposited: Si free (a-C:H) and Si doped (a-C:H:Si). Adhesion, mechanical properties, and film structure were analyzed. Tribological behavior was evaluated with Pin-on-Disk tests using an alumina ball as counterpart and 12 N normal load. At constant room temperature, three different relative humidity conditions were tested: dry, room and wet. The frictional force was registered and the wear scars in the sample and in the counterpart were measured and evaluated by means of confocal, optical, and scanning electron microscopy with EDS. Si-doped coatings showed up to 60 times more wear than Si-free samples, with the later displaying a friction coefficient as low as 0.05, while for the Si-DLC was μ ~ 0.2. This can be caused by a change in the composition of the graphite-like transfer layer produced by the DLC when doping with Si. Both friction coefficient and wear volume increased along with the humidity level for the Si-free DLC, and the opposite trend was observed for the Si-DLC. This can be explained by the oxidation of the DLC in the case of a-C:H and by the stability of a silicon oxide film that is formed and regenerated in accordance with the environment's humidity in the case of a-C:H:Si.Fil: Delfin, Francisco A.. University Of Applied Sciences Upper Austria. School Of Engineering; Austria. Universidad Tecnológica Nacional; ArgentinaFil: Brühl, Sonia Patricia. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Tecnológica Nacional; ArgentinaFil: Dommarco, Ricardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; ArgentinaFil: Forsich, Christian. University Of Applied Sciences Upper Austria; AustriaFil: Heim, Daniel. University Of Applied Sciences Upper Austria; Austri

Influencia de la nitruración por plasma sobre el comportamiento a la corrosión y la adhesión de recubrimientos dlc sobre acero inoxidable aisi 420

Resumen En este trabajo se estudió el comportamiento a la corrosión y la adhesión de dos recubrimientos DLC ("Diamond Like Carbon"), "Soft" y "Hard", depositados por PACVD ("Plasma Assisted Chemical Vapour Deposition") sobre acero AISI 420, templado y revenido y/o nitrurado por plasma. Se analizaron por espectroscopía Raman y midió dureza en superficie. Se observó la microestructura por OM y SEM. Se realizaron pruebas de adhesión con indentación Rockwell C. Se practicaron ensayos de Niebla Salina e inmersión en HCl. Los DLC "Soft" presentaron una dureza de 500 HV y un espesor de 20 µm, mientras que los "Hard" tuvieron 1400 HV y 2,5 µm. Ambos recubrimientos presentaron bajo coeficiente de fricción y buena adhesión sobre el sustrato nitrurado. También presentaron buena resistencia a la corrosión atmosférica. En HCl el DLC retardó la degradación que se presentó rápidamente en las muestras sin recubrir.In this work the corrosion behavior and adhesion of two DLC ("Diamond Like Carbon") films ("Soft" and "Hard") were studied. Both coatings were deposited by PACVD ("Plasma Assisted Chemical Vapour Deposition") on plasma-nitrided and non-nitrided AISI 420 stainless steel. Raman spectroscopy was conducted and surface hardness was measured. The microstructure by OM and SEM, was observed. Adhesion tests were performed with C. Rockwell indentation test. Salt Spray and immersion were performed in HCl. The "Soft" coating was 20 μm thick, the "Hard" film was about 2.5 μm. The hardness was of 500 HV in the "Soft" DLC and 1400 HV in the "Hard" DLC. Both coatings presented low friction coefficient and good adhesion when they were deposited on nitrided steel. Also presented good resistance to atmospheric corrosion. HCl DLC degradation slowed rapidly introduced uncoated samples