Cr/Fe ratio by XPS spectra of magnetoelectropolished AISI 316L SS fitted by Gaussian-Lorentzian shape lines

U radu su predstavljene analize XPS spektara željeza Fe2p3/2 i kroma Cr2p3/2 podešavanjem pomoću simetričnih i asimetričnih oblika linija. Izračuni su provedeni na AISI 316L SS biomaterijalu nakon postupka magnetoelektropoliranja MEP. Najbolji rezultati su postignuti za podešavanje pomoću oblika linija GL(30) i LA(1,3; 4; 5) plus GL(40). Ustanovljeno je da se nakon postupka magnetoelektropoliranja MEP omjer kroma i željeza povećao od 16,4 do 22,4 puta u odnosu na onaj u rasutom materijalu.In the paper, the analyses of Fe2p3/2 and chromium Cr2p3/2 XPS spectra with fitting by symmetrical and asymmetrical line shapes, are presented. The calculations are performed on AISI 316L SS biomaterial after magnetoelectropolishing MEP operation. The best results were obtained for fitting by GL(30) and by LA(1,3; 4; 5) plus GL(40) line shapes. It was found, the chromium-to-iron ratio after magnetoelectropolishing MEP was increasing in the range from 16,4 to 22,4 times versus that one of bulk material

Analytical dependence of substance solubility measure on temperature

ABSTRACT The work covers an adequate analytical dependence of solubility measure of the chemical substances on the water/aqueous solution temperature. The solubility was defined and new, more readable solubility measure was introduced; the coefficient of solubility has been proposed instead. Then the source differential equation was introduced as the basis for the derivation of a final analytical form of dependence of the solubility coefficient on temperature. That characteristics has been developed by determining the dependence of the solubility coefficient variability intensity on temperature. An example of the use of presented theory has been delivered by referring it to the phenomenon of dissolution of AgNO 3 silver nitrate in the aqueous environment. In the summary, quite a developed use of the source differential equation has been underlined with some more examples revealed

Comparative SEM and EDX analysis of surface coatings created on niobium and titanium alloys after plasma electrolytic oxidation (PEO)

U radu su opisani rezultati SEM i EDS analize površinskih slojeva nastalih na legurama niobija i titanija (TNZ, NiTi, Ti6Al4V) nakon plazma elektrolitičke oksidacije (PEO), poznate i kao mikro lučna oksidacija (Micro Arc Oxidation - MAO). Za eksperiment PEO postupka upotrebljen je nekonvencionalni elektrolit, temeljen na koncentriranoj ortofosfornoj kiselini. Nakon PEO dobiveni su i proučavani bakrom obogaćeni površinski slojevi na biomaterijalu. Prikazane su i statistički obrađene opće značajke površine u odnosu na kovinske biomaterijale nakon PEO postupka, uz značajne razlike u rezultatima.In the paper, the SEM and EDS study results of the surface coatings formed on the niobium and titanium alloys (TNZ, NiTi, Ti6Al4V) after the Plasma Electrolytic Oxidation (PEO), also known as Micro Arc Oxidation (MAO), are described. For the experiment of the PEO treatment, a non-conventional electrolyte, based on the concentrated orthophosphoric acid, was used. Copper-enriched surface coatings on the biomaterials after the PEO were obtained and studied. General surface characteristics, regarding the metallic biomaterials after the PEO treatment, with the significant differences of the results, have been displayed and statistically developed

ANSYS analysis of stress and strain after cones plastic deformation

The paper deals with study of stress and strain after cones plastic deformation by ANSYS software. There are shown the new results of FEM analysis, what is the base for the further experimental studies.Web of Science22250850

Development of porous coatings enriched with magnesium and zinc obtained by DC plasma electrolytic oxidation

Coatings with developed surface stereometry, being based on a porous system, may be obtained by plasma electrolytic oxidation, PEO (micro arc oxidation, MAO). In this paper, we present novel porous coatings, which may be used, e.g., in micromachine's biocompatible sensors' housing, obtained in electrolytes containing magnesium nitrate hexahydrate Mg(NO3)(2)center dot 6H(2)O and/or zinc nitrate hexahydrate Zn(NO3)(2)center dot 6H(2)O in concentrated phosphoric acid H3PO4 (85% w/w). Complementary techniques are used for coatings' surface characterization, such as scanning electron microscopy (SEM), for surface imaging as well as for chemical semi-quantitative analysis via energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), glow discharge optical emission spectroscopy (GDOES), and X-ray powder diffraction (XRD). The results have shown that increasing contents of salts (here, 250 g/L Mg(NO3)(2)center dot 6H(2)O and 250 g/L Zn(NO3)(2)center dot 6H(2)O) in electrolyte result in increasing of Mg/P and Zn/P ratios, as well as coating thickness. It was also found that by increasing the PEO voltage, the Zn/P and Mg/P ratios increase as well. In addition, the analysis of XPS spectra revealed the existence in 10 nm top of coating magnesium (Mg2+), zinc (Zn2+), titanium (Ti4+), and phosphorus compounds (PO43-, or HPO42-, or H2PO4-, or P2O74-).Web of Science97art. no. 33

SEM, EDS and XPS analysis of nanostructured coating formed on NiTi biomaterial alloy by Plasma Electrolytic Oxidation (PEO)

Plasma elektrolitička oksidacija (PEO) NiTi legure proučavana je u elektrolitu koji se uobičajeno sastojao od koncentrirane ortofosforične kiseline s dodatkom nitrata bakra II. Taj se PEO postupak primijenio za dobivanje nanostrukturirane prevlake na Nitinol površini. Metode analize površinskog sloja kao što su skeniranje elektronskim mikroskopom (SEM) s energetski disperzivnom rendgenskom spektroskopijom (EDS) i rendgenskom fotoelektronskom spektroskopijom (XPS), omogućile su određivanje strukture i sastava najočekivanijih prevlaka i otkrivanje uvjeta za njihovo dobivanje. Ustanovilo se da se porozna PEO prevlaka dobivena u elektrolitu koji je sadržavao bakreni nitrat u količini većoj od 1,6 mol/L sastoji uglavnom od fosfata bakra-titanija-nikla. Uz to, u usporedbi s matricom, karcinogeni nikal u prevlaci srećom se javlja u vrlo malim količinama, tj. ispod 1 at%.Plasma Electrolytic Oxidation (PEO) of NiTi alloy was studied in the electrolyte consisting generally of concentrated orthophosphoric acid with an addition of copper II nitrate. The PEO process was used to obtain a nanostructured coating on the Nitinol surface. The surface layer analyses methods, such as scanning electron microscopy (SEM) with the energy-dispersive X-ray spectroscopy (EDS), and X-ray photoelectron spectroscopy (XPS), allowed determining the structure and composition of the most expected coatings and revealing the conditions for obtaining them. It was found that the porous PEO coating obtained in the electrolyte containing copper nitrate in an amount higher than 1,6 mol/L consists mainly of copper-titanium-nickel phosphates. Moreover, in comparison with matrix, the emergence of carcinogenic nickel appearing in the coating fortunately appears in very small quantities, i.e. below 1 at%

XPS measurements of AISI 316LVM SS biomaterial tubes after magnetoelectropolishing

XPS (X-ray Photoelectron Spectroscopy) mjerenja obavljena su na uzorcima cijevi od biomaterijala AISI 316LVM nehrđajućeg čelika koji služi za stentove, nakon uobičajenog elektropoliranja (EP) i magnetoelektropoliranja (MEP). Nakon izvršenih operacija elektropoliranja, uzorci su se, zapakirani u foliji, držali otprilike četiri godine. Rezultati XPS analize pokazuju značajnu razliku u vrijednostima mjerenja i računanja, ovisno o metodi površinske obrade: EP i/ili MEP. Izračunat je sastav površinskog sloja čelika i PREN (ekvivalentni broj otpornosti na točkastu eroziju). Najveći su iznosi tih vrijednosti dobiveni na uzorcima poslije MEP-a kada su i vrijednosti spojeva kroma (Cr 2p) i molibdena (Mo 3d) porasle više od tri puta u odnosu na te vrijednosti nakon postupka EP. Izračunati PRENMEP (Fe, Cr, Mo, Mn, Ni, P, S, O) = 16,37, s PRENMEP (Fe, Cr, Mo, Mn, Ni, P, S) = 36,89, u odnosu na PRENEP (Fe, Cr, Mo, Mn, Ni, P, S, O) = 3,12, s PRENEP (Fe, Cr, Mo, Mn, Ni, P, S) = 8,53. Postignuti rezultati ukazuju na korisno i neobično djelovanje magnetskog polja tijekom MEP-a.XPS (X-ray Photoelectron Spectroscopy) measurements were performed on AISI 316LVM stainless steel tubes of biomaterial samples, serving for stents, after a standard electropolishing (EP), and magnetoelectropolishing (MEP). After electropolishing operations, the samples were kept in a closed foil pack for about four years. The results of XPS analysis indicate a significant difference in the measurement and calculation values, dependent on surface treatment method: EP and/or MEP. The steel surface film composition and PREN (pitting resistance equivalent number) were calculated. The highest numbers of these values were obtained on samples after MEP where both chromium compounds (Cr 2p) and molybdenum (Mo 3d) increased over three times against these values after EP treatment. The calculated PRENMEP (Fe, Cr, Mo, Mn, Ni, P, S, O) = 16,37, with PRENMEP (Fe, Cr, Mo, Mn, Ni, P, S) = 36,89, versus PRENEP (Fe, Cr, Mo, Mn, Ni, P, S, O) = 3,12, with PRENEP (Fe, Cr, Mo, Mn, Ni, P, S) = 8,53. The results obtained point to an advantageous and unusual effect of the magnetic field action during MEP

XPS analysis of nanolayer formed on AISI 304L SS after High-Voltage Electropolishing (HVEP)

U radu se predlaže novi postupak nazvan elektropoliranje pod visokim naponom - High-Voltage Electropolishing (HVEP) kako bi se dobila specifična svojstva površine obrađivanog metalnog materijala. Za HVEP obradu kao biomaterijal korišten je AISI 304L nehrđajući čelik. Druga karakteristika ovoga rada je primjena koncentrirane otopine fosforne kiseline kao elektrolita u bakrovom nitratu. Osnovna svrha HVEP-a u toj vrsti elektrolita bila je uključivanje bakarnih iona u pasivni površinski sloj. Takav se modificirani nanosloj analizirao primjenom X-ray Photoelectron Spectroscopy (XPS) kako bi se otkrio sastav dobivenog sloja. Učinjena je usporedba numeričkih rezultata, ovisno o primijenjenom naponu. Uz to, određeni su omjeri Cr/Fe i Cu/P kako bi se pokazale prednosti tog elektrokemijskog HVEP postupka.In the paper, a novel process named the High-Voltage Electropolishing (HVEP) is proposed to gain the specific surface properties on the treated metallic material. The AISI 304L stainless steel as the biomaterial was used for the HVEP treatment. Another feature of this work is using a concentrated phosphoric acid solution within the copper nitrate as electrolyte. The main purpose of the HVEP processing in that kind of electrolyte was to incorporate the copper ions into the passive surface film. Such a modified surface nanolayer was studied by means of the X-ray Photoelectron Spectroscopy (XPS) to reveal the composition of the obtained film. The comparison of the numerical results, dependent on the voltage applied, was performed. Moreover, the Cr/Fe and Cu/P ratios were determined to show the advantages of this electrochemical HVEP treatment

SEM/EDX, XPS, corrosion and surface roughness characterization of AISI 316L SS after electrochemical treatment in concentrated HNO3

U radu se opisuje površina nehrđajućeg čelika AISI 316L poslije elektrokemijske obrade u koncentriranoj HNO3. Obilježena je prametrima hrapavosti, ponašanjem kod zaštite od korozije i kemijskim sastavom površinskog sloja. Uobičajeno korišteni 2D i 3D parametri hrapavosti koji opisuju površinu nakon elektrokemijske obrade su sljedeći: Ra = 0,737 μm i Sa = 1,13 μm kao i Rq = 0,895 μm i Sq = 1,37 μm. Kod proučavanja korozije pasivna gustoća struje bila je 2,3×10−2 μA/cm2, potencijal točkaste korozije Epit = 1140 mV vs. SCE i mogućnost ponovnog pasiviziranja bio je 79 mV vs. SCE. U površinskom su sloju otkriveni spojevi željeza, kroma, molibdena, kobalta, mangana, kao i kalcija (zagađenost). Rezultati visoke rezolucije XPC spektra pokazali su da se većina pronađenih željeznih spojeva može opisati kao Fe2O3/FeOOH, a spojevi kroma kao Cr2O3/CrOOH. Molibden otkriven u površinskom sloju bio je uglavnom sa strukturom valencija šest (65 at%) i pet (17 at%).In the paper there is described the AISI 316L stainless steel surface obtained after electrochemical treatment in concentrated HNO3. It was characterized by roughness parameters, corrosion protection behaviour and chemical composition of the surface layer. Generally used 2D and 3D roughness parameters describing the surface after the electrochemical treatment are the following: Ra = 0.737 μm and Sa = 1,13 μm as well as Rq = 0,895 μm and Sq = 1,37 μm. In case of corrosion studies the passive current density was equal to 2,3×10 ̶ 2 μA/cm2, pitting potential was equal to Epit = 1140 mV vs. SCE and re-passivation potential was 79 mV vs. SCE. In the surface layer there were detected compounds of iron, chromium, molybdenum, cobalt, manganese, as well as calcium (contamination). The high resolution XPS spectra/results data have shown that most of detected iron compounds can be described as Fe2O3/FeOOH and chromium compounds as Cr2O3/CrOOH. The molybdenum detected in the surface layer was mainly in valency states six (65 at%) and five (17 at%)