Wach P.,Institute of Precision Mechanics |
Michalski J.,Institute of Precision Mechanics |
Burdynski K.,Institute of Precision Mechanics |
Ciski A.,Institute of Precision Mechanics
IOP Conference Series: Materials Science and Engineering | Year: 2017
In the paper, nitrided layers on unalloyed and alloyed steels and their corrosion properties are presented. Nitrided layers in the controlled gas nitriding process on C10 and 42CrMo4 steels were formed. Two types of nitrided layers are presented: with nitride iron layers above and below 15 μm. Nitrided layer with nitride layer above 15 μm has good corrosion resistance, but after nitriding of machine parts were subsequently oxidised and impregnated. In the second type of nitrided layer, the surface layers of iron nitrides had a thickness of 3.0 to 11.0 μm. Nitrided layers with a surface layer of iron nitrides with the γ' (Fe4N) structure were formed on unalloyed steel and investigated. The so-formed layers were subject to basic metallographic, X-ray diffraction and corrosion resistance studies carried out by electrochemical methods and in a neutral salt spray chamber. It was found that the layers consisting only of γ' phase had a good corrosion resistance. Necessary requirements for achieving an enhanced resistance comprise their complete tightness and thickness not lower than 9.0 μm. Thinner layers had good electrochemical properties but did not exhibit corrosion resistance in the salt spray chamber. © Published under licence by IOP Publishing Ltd.
Nasilowska B.,Military University of Technology |
Bogdanowicz Z.,Military University of Technology |
Wojucki M.,Institute of Precision Mechanics
Journal of Constructional Steel Research | Year: 2015
Here we investigated the effect of shot peening on the corrosion resistance of 904 L austenitic stainless steel joints made by CO2 laser beam and GTAW welding. Corrosion tests on the fusion zone in welds made by each of these welding methods were performed on shot peened and non-peened specimens. The samples were placed in a salt chamber and inspected after 24, 48, 72, 120, 240, 480, 720 and 1000 h. Pitting corrosion on non-peened welds made by GTAW welding was visible in the heat-affected zone from the face of the weld and reached a depth of 40 μm. Shot peening of welded joints decreased corrosion by 75%. In the case of shot peened welds made by laser beam welding, pitting corrosion had not occurred after 1000 h of salt mist exposure. © 2015 Published by Elsevier Ltd.
Barranco V.,CSIC - National Center for Metallurgical Research |
Carmona N.,CSIC - National Center for Metallurgical Research |
Galvan J.C.,CSIC - National Center for Metallurgical Research |
Grobelny M.,Institute of Precision Mechanics |
And 2 more authors.
Progress in Organic Coatings | Year: 2010
The behaviour/resistance of four optimised sol-gel coating systems (inorganic, hybrid organic-inorganic, containing zirconium ions and containing cerium ions) against corrosion of AZ91 magnesium alloy were studied. The coatings obtained by the sol-gel process were evaluated as autonomous protective coatings as well as a pre-treatment prior to acrylic top coat. The coating obtained from tetramethoxysilane (TMOS) and diethoxydimethylsilane (DEDMS) as precursors and doped with Ce3+ was especially effective as pre-treatment for a final acrylic coating. For non-defected coating the impedance modulus has not changed during the time of immersion (7 days) in 0.5 M Na2SO4. An inhibition of coating delamination at the defect of the acrylic coating was recorded by means of LEIS. © 2010 Elsevier B.V. All rights reserved.
Spyra M.,Warsaw University of Technology |
Derewnicka D.,Institute of Precision Mechanics |
Leonowicz M.,Warsaw University of Technology
Physica Status Solidi (A) Applications and Materials Science | Year: 2010
The effect of titanium addition on the structure and magnetic properties was studied for the nanocomposite Nd 7Fe 79-xB 14Ti x and Nd 8Fe 78-xB 14Ti x systems. The alloys were rapidly solidified by melt-spinning with the roll speed 20 m/s. The overquenched, amorphous ribbons were subsequently crystallization annealed for 20 min at 953-973 K. It was found that the addition of 2 and 4 at% of Ti leads to a substantial increase of the coercivity and maximum energy product of the nanocomposite magnets while maintaining the remanence unchanged. The highest properties were obtained for the alloys containing 4 at% of Ti. The maximum energy product of 143 kJ/ m 3 was achieved for the Nd 8Fe 74B 14Ti 4 alloy. The TEMstudies showed substantial differences in the morphology of the alloys. The ternary alloys contain grains of various sizes of approximately 300 nm. The alloys containing 4 at% of Ti exhibit more homogeneous structure with the crystal sizes up to 30 and 50 nm for the Nd 8Fe 74B 14Ti 4 and Nd 7Fe 75B 14Ti 4 alloys, respectively. More detailed information on the phase constitution was obtained from the Mössbauer spectroscopy. Comparison of the Ti-free and 4 at% Ti alloys revealed that the amount of the hard magnetic Nd 2Fe 14B phase decreases from 84.53 to 69.88% for the Nd 7Fe 79-xB 14Ti x system and increased from 66.60 to 82.48% for Nd 8Fe 78-xB 14Ti x system. Copyright © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Borowski T.,Warsaw University of Technology |
Jelenkowski J.,Institute of Precision Mechanics |
Psoda M.,Warsaw University of Technology |
Wierzchon T.,Warsaw University of Technology
Surface and Coatings Technology | Year: 2010
High-nickel steels composed of metastable austenite are used in the nuclear power industry, aircraft industry, arms industry, and also in the manufacture of surgical instruments. These steels can be exploited at both low and elevated temperatures. Their important advantage lies in that, during plastic deformation, austenite transforms into martensite (TRIP effect). When subjected to a phase transformation combined with precipitation hardening these steels can achieve very high strength indices (R0.2 ≈ 2200 MPa). The material examined was Ni27Ti2AlMoNb steel. The steel was subjected to cold treatment. This treatment resulted in the formation of athermal martensite (α′a). The treatment conducted in liquid nitrogen gave a phase structure of the duplex type (martensite-austenite). After the transformation, the steel was subjected to glow discharge-assisted low-temperature nitriding (≤ 450 °C). The structure thus produced, composed of the phase transformed steel substrate and a nitrided surface layer, was complex in respect of its phase as well as chemical composition and showed unique physical and mechanical properties. By using the martensitic transformation we can modify the depth to which nitrogen diffuses into the steel substrate during the glow discharge nitriding. This possibility permits improving its resistance to frictional wear and corrosion. © 2009 Elsevier B.V. All rights reserved.
Bogdanski B.,Institute of Precision Mechanics
Solid State Phenomena | Year: 2015
Diffusion chromizing of tool steel has been investigated, using a powder method modified by the use of low pressure during the process for the avoidance of the oxidation of the batch. Innovative chromizing novel processes have been carried out in a hot-wall vacuum oven. The processes have been performed in a chromium chloride atmosphere at a low pressure range from 1 to 800 hPa, with treatment temperatures of 850 to 950°C. Studies of layer thickness, its phase composition, and Cr, Fe, and C depth profiles in the diffusion zone of chromized layer have been conducted. The effect of the process parameters, such as time and temperature, on the growth kinetics of diffusion layers has also been investigated. A comparison was made between the layer thickness produced on the tool steel surface using the novel chromizing method, under low pressure, and a traditional chromizing process, by the pack powder method. Chromizing conducted at low pressure was found to be more effective for maximizing the growth rate of diffusion layers than that for chromizing by the traditional pack cementation method. © (2015) Trans Tech Publications, Switzerland.
Bilovol V.,University of Buenos Aires |
Ferrari S.,University of Buenos Aires |
Derewnicka D.,Institute of Precision Mechanics |
Saccone F.D.,University of Buenos Aires
Materials Chemistry and Physics | Year: 2014
Electronic structure of rapidly quenched ribbons of nominal composition NdyFe(86-y-x)B14Tix (x = 0, 2, 4; y = 7, 8 at.%) was studied by X-ray absorption (Fe and Ti K-edge) and X-ray photoelectron spectroscopy. It was found by XANES that Ti addition promotes modifications of the electronic structure of Fe sub-band. From the analysis of differences in the pre-edges structure areas, coming from variations in the 3d density of states near the Fermi level, the evidences of acceptor nature of Ti and Fe atoms in NdFeB alloys are present. Using photoelectron spectroscopy, we found that neodymium, iron and titanium are in both, metallic and oxidized, states on the surface of the ribbons. A higher Ti0 content (at high vacuum) is characteristic of the annealed samples. The presence of oxidized titanium states was corroborated by XANES. © 2014 Elsevier B.V. All rights reserved.
Szeptycka B.,Institute of Precision Mechanics |
Gajewska-Midzialek A.,Institute of Precision Mechanics |
Babul T.,Institute of Precision Mechanics
Journal of Materials Engineering and Performance | Year: 2016
The research on the graphene application for the electrodeposition of nickel composite coatings was conducted. The study assessed an important role of graphene in an increased corrosion resistance of these coatings. Watts-type nickel plating bath with low concentration of nickel ions, organic addition agents, and graphene as dispersed particles were used for deposition of the composite coatings nickel-graphene. The results of investigations of composite coatings nickel-graphene deposited from the bath containing 0.33, 0.5, and 1 g/dm3 graphene and one surface-active substance were shown. The contents of particles in coatings, the surface morphology, the cross-sectional structures of the coated samples, and their thickness and the internal stresses were studied. Voltammetric method was used for examination of the corrosion resistance of samples of composite coatings in 0.5 M NaCl. The obtained results suggest that the content of incorporated graphene particles increases with an increasing amount of graphene in plating bath. The application of organic compounds was advantageous because it caused compressive stresses in the deposited coatings. All of the nickel-graphene composite layers had better corrosion resistance than the nickel coating. © 2016 The Author(s)
Babul T.,Institute of Precision Mechanics |
Olbrycht A.,Institute of Precision Mechanics
23rd International Federation of Heat Treatment and Surface Engineering Congress 2016, IFHTSE 2016 | Year: 2016
The paper presents the results of work on manufacturing and properties testing of composite materials with nano-carbon dispersion phase. The article describes a method for composite materials production and the results of thermal diffusivity as well as wear resistance measurements of these materials. It was found, that the produced composite materials with nanocarbon dispersion phase are characterized by various advantageous properties such as increased hardness and wear resistance with respect to the matrix material and considerably higher thermal diffusivity. The paper presents also the results of tests using composite materials with nano-carbon dispersion phase implementation for thermal spraying. There are also presented examples of coatings sprayed with detonation method on different substrates and the results of these coatings studies. Copyright © 2016 ASM International® All rights reserved.
Babul T.,Institute of Precision Mechanics
Archives of Metallurgy and Materials | Year: 2014
The article compared the results of theoretical calculations with results of actual temperature measurements of detonation sprayed NiCrBSi powder heated by the impact of the detonation products stream. Theoretical distributions of temperature in the powder particle were calculated by the Finite Element Method FEM, using the COSMOS/M program algorithm. In the absence of the heat transfer equations in the solid state being in movement, which is influenced by dynamic heat wave, the conduction mechanism described by Fourier's law was adopted. Experimental temperature measurements as a function of the acceleration path length were conducted using an own construction two-channel pyrometric system. The obtained data confirmed good agreement between the results obtained using FEM calculations method and results of experimental measurements using the pyrometric devices.