An XPS study of compositional changes induced by argon ion bombardment of the LaPO4 surface

Ivanova, Olga; Naumkin, A.V.; Vasilyev, L. A.

doi:10.1016/0042-207x(95)00180-8

Cited by 31 publications

(11 citation statements)

References 21 publications

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“…In our case, from the shape and intensity of satellites observed for La3d 5/2 and La3d 3/2 , it can be concluded that the principal component is La 2 O 3 or La(OH) 3 or a mixture of both. 36,37 Lanthanum oxide La 2 O 3 is very hygroscopic and is rapidly turned into hydroxide La(OH) 3 when exposed to air. 38,39 Therefore, the lanthanum analyzed on the surface of the sample and observed at a binding energy of 835.5 eV is attributed to lanthanum hydroxide.…”

Section: 33mentioning

confidence: 99%

“…A peak of La3d 5/2 at a binding energy of 835.1 eV can be attributed to both a La(OH) 3 36 and La 2 O 3. 37 In order to overcome a problem of peak attribution and determination of the chemical environment of lanthanum, the shape of the peaks and the intensity of satellites can be used. If LaF 3 was present, the intensity of the satellites should be very small.…”

Section: 33mentioning

confidence: 99%

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Role of Post-Treatment in Improved Corrosion Behavior of Trivalent Chromium Protection (TCP) Coating Deposited on Aluminum Alloy 2024-T3

Ely

Światowska

Seyeux

et al. 2017

J. Electrochem. Soc.

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The effects of post-treatment applied on Trivalent Chromium Protection (TCP) coatings deposited on aluminum alloy 2024-T3 was studied by electrochemical and surface analytical techniques: X-ray Photoelectron Spectroscopy (XPS) and Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS). The aim of the post-treatment was to improve the corrosion resistance of the TCP coating. To understand the influence of the post-treatment, using a bath containing H 2 O 2 and a lanthanum salt as an inhibitor, our approach was to study the effect of these two components separately. It was found that the improved corrosion protection provided by the post-treated TCP was related to a synergetic effect of the two components. XPS and ToF-SIMS analyses showed that (i) the thickness of the TCP coating is not modified by the post-treatment, (ii) lanthanum is present on the surface and in the bulk of the TCP and (iii) is found in very small amount only on the extreme surface. The total concentration of Cr(VI) (oxide/hydroxide) was estimated to be below 0.1 wt% in the post-treated TCP layer. It was concluded that lanthanum plays a significant role in improving the coating density and homogeneity and has a beneficial effect on the TCP coating cracking as observed by Scanning Electron Aluminum alloys are used for aerospace applications for their low weight and good mechanical properties.1-3 To improve the corrosion properties of aluminum alloys and to provide good paint adhesion, the first layer of coating applied on the aluminum alloy surface used to be a chromate conversion coating (CCC).4-6 However, hexavalent chromium used in the CCC coatings is highly toxic, 4,7 its use is very much restricted in Europe 8 and the United States 9 and will be forbidden by 2024 by the European Community with respect to the Registration, Evaluation, Authorization and Restriction of Chemicals (REACh).8 Therefore, new conversion coatings have been developed, and one of the most promising solutions is the Trivalent Chromium Protection coating called also as the Trivalent Chrome Process (TCP).10-14 TCP conversion coatings are formed by immersion in a solution containing Zr 4+ , Cr 3+ and F − ions, at a pH between 3.8 and 4.0. As it has already been widely discussed, the coating formation mechanism occurs by multiple chemical steps. 10,11,13,[15][16][17] The initial step involves dissolution of the aluminum oxide layer by fluorides. The removal of the oxide layer exposes the metal surface where cathodic reactions take place. Oxygen reduction reaction, and possibly hydrogen discharge, which counterbalance aluminum oxidation, consume protons and causes a pH increase at the interface between the metallic substrate and the solution, as measured by Li et al. 15 The high pH favors the precipitation of ions present in the solution, forming a hydrated layer of zirconium and chromium oxide. The thickness of the TCP layer is usually of the order of 100 nm, depending on the nature of the aluminum alloy, the concentration of the solution and the immersion time.11,12,18 ...

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Section: 33mentioning

confidence: 99%

Section: 33mentioning

confidence: 99%

Role of Post-Treatment in Improved Corrosion Behavior of Trivalent Chromium Protection (TCP) Coating Deposited on Aluminum Alloy 2024-T3

Ely

Światowska

Seyeux

et al. 2017

J. Electrochem. Soc.

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“…The La signal was clearly observed after 5 and 30 minutes of PACS post-treatment (Figure 6(e)).The spectra present characteristic spin orbit doublet of La 3d 5/2 and La 3d 3/2 , however here for simplicity only La 3d 5/2 is present. Different peaks can be distinguished here: the low binding energy peak at around 830 eV corresponding to the Auger KLL of fluorine[53], and the higher binding energy peaks at around 835 eV corresponding to La(OH) 3[25,62,63], the peak at around 839 eV to LaF 3 and finally the shake-up satellite peak at 843 eV. After 30 minutes of PACS posttreatment time, the small increase of relative intensity of lanthanum fluorides to lanthanumA C C E P T E D M A N U S C R I P Thydroxides/oxides can be observed.…”

mentioning

confidence: 99%

Influence of post-treatment time of trivalent chromium protection coating on aluminium alloy 2024-T3 on improved corrosion resistance

Stoica

Światowska

Romaine

et al. 2019

Surface and Coatings Technology

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Low corrosion protection performances of Trivalent Chromium Process (TCP) coatings with reference to Chromium Conversion Coatings (CCC) deposited on aluminium alloys can be overcome by application of post-treatment processes. This work shows the effect of post-treatment bath (containing hydrogen peroxide and lanthanum salt) on the chemical composition, structure and the corrosion performances of TCP coating deposited on AA 2024-T3 aluminium alloy. Different times of post-treatment bath were applied on the TCP coating and the samples were analyzed by Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS), X-ray Photoelectron Spectroscopy (XPS) and Glow Discharge-Optical Emission Spectrometry (GD-OES). The ToF-SIMS and GD-OES depth profiles show that the post-treatment time has no influence on the thickness of the TCP coating and on its bi-layered structure. It is composed of an outer layer, rich in zirconium and chromium oxides and an inner layer rich in aluminium oxides and oxy-fluorides. 3D ToF-SIMS images reveal an enrichment of Cr and Zr-like species over the surface of intermetallic particles with reference to alloy matrix, whereas a homogenous distribution of La is observed. The analysis of in-depth distribution shows that La is present principally in the outer part of the TCP coating. The La concentration increases with increasing post-treatment time. The effect of post-treatment time on protection was evaluated by Electrochemical Impedance Spectroscopy (EIS) and Linear Sweep Voltammetry (LSV) in a 0.001 M NaCl + 0.1 M Na 2 SO 4 electrolyte. The increased posttreatment time enhances the cathodic inhibition against oxygen reduction. The post-treatment provides improved coating homogeneity and sealing properties.

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“…Specific heat (C p ) was gained by Neumann-Kopp law [30]. Pores and cracks usually produced an obvious impact on heat propagation; the thermal conductivity (k) of specimen without pores and cracks was [27]:…”

Section: Property Measurementmentioning

confidence: 99%

Influence of HfO2 alloying effect on microstructure and thermal conductivity of HoTaO4 ceramics

Lin

Feng

2019

J Adv Ceram

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HfO2 alloying effect has been applied to optimize thermal insulation performance of HoTaO4 ceramics. X-ray diffraction, Raman spectroscopy, and X-ray photoelectron spectroscopy are employed to decide the crystal structure. Scanning electronic microscopy is utilized to detect the influence of HfO2 alloying effect on microstructure. Current paper indicates that the same numbers of Ta5+ and Ho3+ ions of HoTaO4 are substituted by Hf4+ cations, and it is defined as alloying effect. No crystal structural transition is introduced by HfO2 alloying effect, and circular pores are produced in HoTaO4. HfO2 alloying effect is efficient in decreasing thermal conductivity of HoTaO4 and it is contributed to the differences of ionic radius and atomic weight between Hf4+ ions and host cations (Ta5+ and Ho3+). The least experimental thermal conductivity is 0.8 W·K−1·m−1 at 900 °C, which is detected in 6 and 9 mol%-HfO2 HoTaO4 ceramics. The results imply that HfO2–HoTaO4 ceramics are promising thermal barrier coatings (TBCs) due to their extraordinary thermal insulation performance.

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An XPS study of compositional changes induced by argon ion bombardment of the LaPO4 surface

Cited by 31 publications

References 21 publications

Role of Post-Treatment in Improved Corrosion Behavior of Trivalent Chromium Protection (TCP) Coating Deposited on Aluminum Alloy 2024-T3

Role of Post-Treatment in Improved Corrosion Behavior of Trivalent Chromium Protection (TCP) Coating Deposited on Aluminum Alloy 2024-T3

Influence of post-treatment time of trivalent chromium protection coating on aluminium alloy 2024-T3 on improved corrosion resistance

Influence of HfO2 alloying effect on microstructure and thermal conductivity of HoTaO4 ceramics

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