Facultad Regional Concep. del Uruguay
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Item Wear and corrosion behaviour of AISI 420 stainless steel coated with AlCrN(2024-09-24) Dalibón Bähler, Eugenia Laura; Brühl, Sonia Patricia; Izquierdo Pérez, Javier; Souto Suárez, Ricardo ManuelMartensitic Stainless steels are high strength materials used in many industrial applications where a god resistance to wear and corrosion is required, such as blades, shears and cutting tools, valves in the oil and gas, automotive and aerospace components, surgical instruments, among others. To increase even more wear resistance AISI 420 coated by PVD AlCrN is studied in severe wear conditions, simulated in lab as pin on disk with a high hertzian pressure and abrasive tests in ASTM G65. Corrosion was studied in a chloride solution by polarization and impedance tests. The coating was analyzed also in adhesion and hardness using Rockwell C indentation test and nanoindentation. In all tests the performance was compared with an ion nitrided material, another kind of plasma process, in this case a diffusion process, suitable for large components. The coating reached almost 3 microns width and the nitrided case, 10 microns. The substrate hardness was around 5 GPa, the nitrided case reached 18 GPa and the coating 45 GPa. In the pin on disk test against alumina, 10 N load and 500 m, the coefficient of friction was 0.6 in the coated sample, 0.8 in the nitrided sample and the untreated material, but in the mass loss, the difference was much bigger. One order of magnitude less between each other. In the abrasive test with 130 N load, the nitrided sample failed and only the coating passed the test with almost no damage, and mass loss undetectable. The coatings exhibited different corrosion behaviours. Nitriding led to a higher polarization resistance, smaller passivity current and more positive pitting potential that bare steel, evidencing enhanced passivation [1]. But the AlCrN coating showed more active corrosion potential and two orders of magnitude higher currents in the anodic range due to pinholes that prevent sealing the metal. Abrasive testing did not modify the corrosion characteristics of the coated material.Item Tribological behaviour of TiAlN and AlCrN coatings deposited over martensitic stainless steel(2023-04-26) Dalibón Bähler, Eugenia Laura; Brühl, Sonia Patricia; Maskavizan, Ana JustinaIn this work, the tribological behaviour of PVD TiAlN and AlCrN coatings deposited on AISI martensitic stainless steel is studied. The coatings were deposited by cathodic arc PVD in Oerlikon Balzers Argentina.Item Wear resistance of an Hyperlox Gold® coating over nitrided martensitic AISI 420 stainless steel(2022-09-15) Dalibón Bähler, Eugenia Laura; Schierloh, Gonzalo José; Tuckart, Walter Roberto; Brühl, Sonia PatriciaMartensitic stainless AISI 420 steel was plasma nitrided and then coated with an Hyperlox Gold® coating (Cemecon), using the PVD magnetron sputtering technique in an industrial facility at Coating.Tech, Argentina. The coating is mainly AlTiN, covered with a thin layer of TiN to provide the gold colour. Duplex samples (nitrided + coated) were tested in wear comparing with only coated AISI 420 steel and with only nitrided steel. XRD, Nanoindentation, Raman, optical, electronic and confocal microscopy were used to observe the cross section and analyse the wear scars. Adhesion was studied in a Scratch Test following ASTM C1624 standard. Abrasive wear tests were conducted in a sand rubber wheel test (ASTM G65) and adhesive wear tests, in a rotational pin on disk machine using a 6 mm alumina ball as counterpart, and 500 m wear distance using three different normal loads. Steel samples were heat treated to acquire the martensitic structure and 580 HV hardness previous to the plasma nitriding process which was carried out in an industrial facility at IONAR, Argentina in a DC pulsed 10 h process at 390ºC with 20% N2-H2 atmosphere. The nitrided layer was 10 um thick, and the hardness was measured as 1180 ± 40 HV. The Hyperlox coating was about 3 um thick and the TiN top coating 0.5 um thick. Adhesion was good in all cases, but it was better in the duplex sample where 90 N was the critical load, meanwhile in the only coated sample, it was 60 N. In the abrasive wear test, both coated samples showed indetectable wear volume loss in a severe wear test with 130 N load. However, in the adhesive wear test carried out with a pin on disk results were unexpected. With a low load (5 N), the nitrided samples had a better behaviour than the coated samples. At higher loads, 7 N and 10 N, the behaviour was inverse. Moreover, the duplex coated samples lost less volume at 10 N, more at 7 N and even more at 5 N. The discussion will show the influence of surface oxidation in the nitrided steel at low loads to diminish the friction coefficient and how the structural stability of the coating system and the trapped debris determines the wear behaviour in the coated samples. The stress distribution with depth is also considered.Item Plasma surface engineering to enhance wear and corrosion resistance of stainless steels(2014-11-11) Brühl, Sonia PatriciaA brief description of the research lines of the Surface Engineering Group of UTN will be presented, as well as some important results obtained in the last years concerning plasma nitriding of austenitic stainless steel and different DLC carbon coatings deposited over nitrided martensitic stainless steels.Item Characterization of thick and soft DLC coatings deposited on plasma nitrided stainless steel(2014-09-15) Brühl, Sonia Patricia; Dalibón Bähler, Eugenia Laura; Heim, Daniel; Forsich, ChristianThick and soft DLC coatings were deposited by PACVD with a DC pulsed discharge on nitrided and non nitrided austenitic stainless steel. The films were characterized by EDS and Raman, hardness was assessed with nanoindenter and the microstructure was analyzed by Optical Microscopy, SEM and XRD.Item Corrosion resistance of AISI 316L stainless steel nitrided by three different plasma assisted techniques(2014-07-23) Manova, Darina; Mändl, Stephan; Brühl, Sonia Patricia; Escalada, Lisandro; Simison, SilviaPlasma assisted surface modification methods have been used to nitride stainless steels in order to enhance and therefore the lifetime of industrial components. Nevertheless, the corrosion resistance is not always preserved since it is very sensitive to the process parameters, either in implantation or in thermochemical diffusion techniques. AISI 316L stainless steel was plasma nitrided using three different techniques: low energy ion implantation (LEII), plasma immersion implantation (PI3) and convencional DC pulsed plasma nitriding (DCPN). For each method sveral parameters were tested and some of them were selectedto achieve the so called S phase of about 3 um thickness and no nitrides precipitation. The nitrided layer was characterized with OM and SEM. Hardness wass assessed on the surface with Vickers indenter and 25 g load. XRD was performed to characterize The S phase and to detect other phases if present and electrochemical corrosion tests were carried out in 3.5% NaCI solution. Although the S phase thickness in the three groups of samples was comparable, hardness was not and neither wasthe corrosion resistance. The PI3 samples were he hardest with the best performance in corrosion experiments, resulting in a higher breakdown potencial and lower currents.Item Corrosion resistance of DLC hard coatings deposited over nitrided PH stainless steel(2014-07-23) Cabo, Amado; Trava-Airoldi, Vladimir Jesús; Dalibón Bähler, Eugenia Laura; Brühl, Sonia Patricia; Pereira, Lânia AuxiliadoraIn this work a DLC film was deposited over ion nitrided PH stainless steel Corrax® with a Si interlayer in a CVD Plasma, where the plasma was generated and sustained by an asymmetric pulsed DC discharge. A nitrided sample was compared in all tests with a DLC coated sample and a duplex one (nitrided+coating). Nitriding has been carried out in an industrial facility with a pulsed DC discharge.Item Influence of inclusions on the corrosion attack of plasma nitrided austenitic stainless steel(2013-09-08) Escalada, Lisandro; Brühl, Sonia Patricia; Suárez Vallejo, Sebastián; Guitar, María Agustina; Manova, Darina; Mändl, Stephan; Simison, SilviaAustenitic stainless steels are well known for their good localized corrosion resistance. They are commonly employed in components and instruments in the food and beverage, as well as chemical, oil and medical industries. However their use in some applications is limited due to their poor tribological properties.Item Comparison of wear and corrosion behavior of three different nitriding methods on AISI 316L stainless steel(2013-07-05) Dalibón Bähler, Eugenia Laura; Vaca, Laura Silvia; Brühl, Sonia Patricia; Simison, Silvia; Escalada, Lisandro; Manova, Darina; Mändl, Stephan; Neumann, HorstIn this work, AISI316L stainless steel was nitrided using three different processes: Low Energy Ion Implantation (LEII), Plasma Immersion Ion Implantation (PI3) and DC Pulsed Plasma Nitriding (DCPPN). The process temperature was chosen between 390 and 430 °C in all processes with the aim of preserving their corrosion resistance.Item Wear resistance of nitrided and DLC coated PH stainless steel(2013-05-27) Dalibón Bähler, Eugenia Laura; Brühl, Sonia Patricia; Trava-Airoldi, Vladimir JesúsIn this work PH stainless steel Corrax(R) was ion nitrided and coated with DLC in a CVD process.