scholarly journals Laser cleaning of Cu-based artefacts: laser/corrosion products interaction

ACTA IMEKO ◽  
2018 ◽  
Vol 7 (3) ◽  
pp. 104 ◽  
Author(s):  
Elisabetta Di Francia ◽  
Ruth Lahoz ◽  
Delphine Neff ◽  
Emma Angelini ◽  
Sabrina Grassini
Keyword(s):  
Laser Cleaning ◽  
Corrosion Products ◽  
X Ray Diffraction ◽  
Cleaning Procedure ◽  
Before And After ◽  
Archaeological Artefact ◽  
The Difference ◽  
Experimental Findings ◽  
Optimized Conditions ◽  
Reference Samples

<p class="Abstract">This study aims to develop a low invasive and selective laser cleaning procedure for the removal of reactive corrosion products on Cu-based artefacts without damage the substrate. In a preliminary step, laser cleaning was performed on two typologies of artificially corroded copper reference samples. The effect of the variation of laser parameters as pulse duration and output power, was thus evaluated on an oxide layer, simulating a protective patina, and a hydroxychloride layer, simulating a reactive corrosion products layer to be removed. The optimized cleaning procedure was validated on an archaeological artefact, a bronze coin. Morphological, microchemical and microstructural characterizations were performed by means of optical microscopy, confocal microscopy, field emission scanning electron microscopy, X-Ray diffraction and Raman spectroscopy, before and after laser cleaning. The experimental findings show that laser cleaning, in optimized conditions, can reduce the thickness of the hydroxychloride layers slightly affecting the oxide layers. The difference in the interaction with laser radiation of these two layers seems to be mainly related to the difference in grain size and porosity. Notwithstanding these encouraging results, in order to define the real feasibility of the laser cleaning procedure, a further validation on real artefacts is mandatory due to the variation in thickness and composition of the corrosion products formed during long-lasting uncontrolled degradation processes.</p>

In-Situ X-ray Diffraction Study of Lithium Intercalation in Nanostructured Anatase Titanium dioxide

1998 ◽  
Vol 536 ◽  
Author(s):  
R. Van de Krol ◽  
E. A. Meulenkamp ◽  
A. Goossens ◽  
J. Schoonman
Keyword(s):  
Phase Transformation ◽  
Maximum Amount ◽  
Lithium Intercalation ◽  
X Ray Diffraction ◽  
X Ray ◽  
Before And After ◽  
The Difference ◽  
Two Phases ◽  
Reversible Phase

AbstractElectrochemical lithium intercalation in nanostructured anatase TiO2 is investigated with in-situ X-ray diffraction. A complete and reversible phase transformation from tetragonal anatase TiO2 to orthorhombic anatase Li0.5TiO2 is observed. The difference of the XRD spectra before and after insertion can be fitted with the lattice parameters of the two phases as fit parameters. The maximum amount of lithium that can be dissolved in anatase TiO2 before the phase transformation occurs is found to be very small.

scholarly journals Application of µ-Raman spectroscopy to the study of the corrosion products of archaeological coins

ACTA IMEKO ◽  
2021 ◽  
Vol 10 (1) ◽  
pp. 234
Author(s):  
Tilde De Caro ◽  
Emma Angelini ◽  
Leila Es Sebar
Keyword(s):  
Raman Spectroscopy ◽  
Analytical Techniques ◽  
Corrosion Products ◽  
Lead Chloride ◽  
X Ray Diffraction ◽  
X Ray ◽  
Micro Raman Spectroscopy ◽  
Experimental Findings ◽  
Non Destructive ◽  
Excavation Site

<p>In this paper, a study of the corrosion products formed on archaeological bronze artefacts excavated in Tharros (Sardinia, Italy) is presented. The investigation was carried out by means of the combination of different analytical techniques, including optical microscopy, micro-Raman spectroscopy (µ-RS), scanning electron microscopy coupled with energy dispersive X-ray spectroscopy and X-ray diffraction. The artefacts under study are three bronze coins from the Phoenician–Punic period that are deeply corroded due to the chloride-rich soil of the Tharros excavation site. µ-Raman spectroscopy was chosen to investigate the corroded surfaces of the artefacts because it is a non-destructive technique, it has high spatial resolution, and it makes it possible to discriminate between polymorphs and correlate colour and chemical composition. Through µ-RS, it was possible to identify different mineralogical phases and different polymorphs, such as cuprite (Cu<sub>2</sub>O), copper trihydroxychloride [Cu<sub>2</sub>Cl(OH)<sub>3</sub>] polymorphs, hydroxy lead chloride laurionite [PbCl(OH)] and calcium carbonate polymorph aragonite. The experimental findings highlight that micro-Raman spectroscopy can be used to provide further knowledge regarding the environmental factors that may cause the degradation of archaeological bronzes in soil.</p>

scholarly journals A Comprehensive Study for the Laser Cleaning of Corrosion Layers due to Environmental Pollution for Metal Objects of Cultural Value: Preliminary Studies on Artificially Corroded Coupons

2006 ◽  
Vol 2006 ◽  
pp. 1-7 ◽  
Author(s):  
A. Siatou ◽  
D. Charalambous ◽  
V. Argyropoulos ◽  
P. Pouli
Keyword(s):  
Chemical Composition ◽  
Pulse Duration ◽  
Systematic Investigation ◽  
Laser Cleaning ◽  
Cultural Value ◽  
Layer By Layer ◽  
Threshold Values ◽  
X Ray Diffraction ◽  
Before And After ◽  
Comprehensive Study

This paper is focused on the systematic investigation of the layer-by-layer removal of corrosion products on artificially corroded metal coupons aiming to introduce a methodology for the optimum laser cleaning approach of historical metal objects. Thus, it is very important to determine the chemical composition of the studied surfaces before and after irradiation. A series of laser cleaning studies has been performed on test coupons (reference and artificially corroded). Wavelength and pulse duration effects are investigated. Initial studies were focused on the use of infrared (1064 nm) and ultraviolet (355 nm and 248 nm) radiations of nanosecond (ns) pulse duration. Damage and removal threshold values were determined for the substrates and the corrosion layers, respectively. The irradiated surfaces are evaluated microscopically under the optical and the scanning electron microscope, while the mineralogical and chemical composition of the various layers is determined with X-ray diffraction and SEM-EDAX analyses, respectively. The results obtained are providing a comprehensive approach for understanding the main mechanisms that are significant in the different laser cleaning regimes, while the optimum cleaning methodologies for the studied materials are being established.

scholarly journals A Study on the Laser Removal of Epoxy Coatings on SS400 Surface by Beam Scanning Patterns

Coatings ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1510
Author(s):  
Ji-Eon Kim ◽  
Jong-Myoung Lee ◽  
Jeong-Hun Hyun ◽  
Je-Han Jeong ◽  
Jong-Do Kim
Keyword(s):  
Average Power ◽  
Laser Cleaning ◽  
Working Environment ◽  
Beam Scanning ◽  
Before And After ◽  
The Difference ◽  
Cleaning Technology ◽  
Overlap Rate ◽  
Epoxy Paint ◽  
Mechanical Cleaning

Shipyards are very interested in improving their working environment and resolving environmental pollution issues by replacing mechanical cleaning technologies used before and after painting processes with laser cleaning technology. Because epoxy paint is thickly coated, with a thickness of 200 μm or greater, it is difficult to remove using both laser cleaning and mechanical cleaning technologies. Therefore, this study tried to obtain effective cleaning results by controlling the process parameters when removing the thick epoxy coating using a Q-switching fiber laser cleaning system with an average power of 100 W developed by our research team. The pulse duration time of the laser is 150 ns. Additionally, in order to determine whether the cleaning was sufficient, the difference in laser-induced plume/plasma was compared. By controlling the beam scanning patterns, line overlap rate, and pulse overlap rate, it was possible to obtain effective cleaning results without introducing removal deviation. In addition, the NOP increased when the laser beam overlap rate increased. This increased the amount of heat input to the material and reduced the number of scans required to remove the epoxy paint. As a result of the plume/plasma analysis, less plume/plasma was generated as the paint was removed if the epoxy paint remained on the surface. On the other hand, when all of the paint was removed, a higher brightness of plume/plasma generated by evaporation of the bare metal was observed.

scholarly journals A Comparative Study of Hydrogen-Induced Cracking Resistances of API 5L B and X52MS Carbon Steels

2018 ◽  
Vol 2018 ◽  
pp. 1-7 ◽  
Author(s):  
Rodrigo Monzon Figueredo ◽  
Mariana Cristina de Oliveira ◽  
Leandro Jesus de Paula ◽  
Heloisa Andréa Acciari ◽  
Eduardo Norberto Codaro
Keyword(s):  
Hydrogen Permeation ◽  
Carbon Steels ◽  
Corrosion Products ◽  
Metallographic Analysis ◽  
Low Carbon ◽  
X Ray Diffraction ◽  
X Ray ◽  
Standard Testing ◽  
Hydrogen Induced Cracking ◽  
Before And After

Susceptibility to hydrogen-induced cracking of API 5L B and X52MS low-carbon steels in NACE 177-A, 177-B, and 284-B solutions has been investigated by the present work. A metallographic analysis of these steels was performed before and after NACE TM0284 standard testing. Corrosion products were characterized by scanning electron microscopy and X-ray dispersive energy spectrometry, which were subsequently identified by X-ray diffraction. Thus it was found that pH directly affects the solubility of corrosion products and hydrogen permeation. Both steels showed generalized corrosion in solution 177-A, and a discontinuous film was formed on their surfaces in solution 177-B; however, only the API 5L B steel failed the HIC test and exhibited greater crack length ratio in solution 177-A. In solution 284-B whose pH is higher, the steels exhibited thick mackinawite films with no internal cracking.

Wear-Fatigue Behavior of Ni88P11.78Co0.12Fe0.10 and Ni80.55Cr15.25B4.20 Metallic Glasses During Rubbing Against an Eccentric Rotating Ceramic Roller

2012 ◽  
Vol 134 (4) ◽  
Author(s):  
C. Serrar ◽  
P. Guiraldenq
Keyword(s):  
Chemical Composition ◽  
Metallic Glasses ◽  
Photoelectron Spectroscopy ◽  
Fatigue Behavior ◽  
X Ray Diffraction ◽  
Eccentric Rotation ◽  
X Ray ◽  
Before And After ◽  
Fatigue Rupture ◽  
The Difference

The wear-fatigue rupture of Ni88P11.78Co0.12Fe0.10 (NiP) and Ni80.55Cr15.25B4.20 (NiCrB) glasses prepared by planar–flow casting have been studied using a test under simultaneous constant and cyclic loading generated by an eccentric rotation ceramic antagonist. For better apprehending the phenomena related to the structural state changes of samples before and after tests, structural characterization by x-ray diffraction, mechanical characterization by measuring Vickers microhardness (HV 0.1) and chemical composition by X-ray photoelectron spectroscopy (XPS) analysis have been carried out on as-quenched and worn dull side ribbons. Rupture surfaces, in S–N curves, have been measured by scanning electron microscope. Wear-fatigue contact tests consist to impose, simultaneously, a traction strain and cyclic normal stresses which generate traction, compression, rolling, bending and shearing. All results obtained from the two selected glasses (NiP and NiCrB) are systematically compared with those of a nickel pure crystalline foil (Ni). We evaluate mainly the wear mechanism, the mode and the typical rupture surface observed in NiP, NiCrB and Ni specimens. We specify the conditions of obtaining these rupture surfaces which often present in smooth plane, veining and “chevrons” patterns. All results show a great wear and fatigue resistance for the two metallic glasses compared to Ni. The NiCrB wear resistance is superior to that of NiP, while the difference in their fatigue limit is not clearly distinct. The reasons for the differences in wear and fatigue behavior will be discussed in relation to the metallic glass thermal stability, chemical composition, microhardness and surface rupture topography.

Evaluation of Freezing Methods by Low Temperature X-Ray Diffraction

1977 ◽  
Vol 35 ◽  
pp. 330-333
Author(s):  
T. Gulik-Krzywicki ◽  
M.J. Costello
Keyword(s):  
Biological Materials ◽  
Molecular Organization ◽  
X Ray Diffraction ◽  
Glass Capillary ◽  
X Ray ◽  
Rate Dependent ◽  
Before And After ◽  
Freeze Etching ◽  
Diffraction Patterns ◽  
Set Up

Freeze-etching electron microscopy is currently one of the best methods for studying molecular organization of biological materials. Its application, however, is still limited by our imprecise knowledge about the perturbations of the original organization which may occur during quenching and fracturing of the samples and during the replication of fractured surfaces. Although it is well known that the preservation of the molecular organization of biological materials is critically dependent on the rate of freezing of the samples, little information is presently available concerning the nature and the extent of freezing-rate dependent perturbations of the original organizations. In order to obtain this information, we have developed a method based on the comparison of x-ray diffraction patterns of samples before and after freezing, prior to fracturing and replication.Our experimental set-up is shown in Fig. 1. The sample to be quenched is placed on its holder which is then mounted on a small metal holder (O) fixed on a glass capillary (p), whose position is controlled by a micromanipulator.

Antiphase Boundaries in Ordered Ni3FE Crystals

1969 ◽  
Vol 27 ◽  
pp. 62-63
Author(s):  
Y. H. Liu
Keyword(s):  
Domain Size ◽  
Antiphase Domain ◽  
X Ray Diffraction ◽  
X Ray ◽  
Hardening Mechanism ◽  
Superlattice Structure ◽  
Disordered Phase ◽  
Domain Boundaries ◽  
Atomic Scattering ◽  
The Difference

Ordered Ni3Fe crystals possess a LI2 type superlattice similar to the Cu3Au structure. The difference in slip behavior of the superlattice as compared with that of a disordered phase has been well established. Cottrell first postulated that the increase in resistance for slip in the superlattice structure is attributed to the presence of antiphase domain boundaries. Following Cottrell's domain hardening mechanism, numerous workers have proposed other refined models also involving the presence of domain boundaries. Using the anomalous X-ray diffraction technique, Davies and Stoloff have shown that the hardness of the Ni3Fe superlattice varies with the domain size. So far, no direct observation of antiphase domain boundaries in Ni3Fe has been reported. Because the atomic scattering factors of the elements in NijFe are so close, the superlattice reflections are not easily detected. Furthermore, the domain configurations in NioFe are thought to be independent of the crystallographic orientations.

Tem analysis of multiple-energy arsenic implanted and Rta'd silicon

1987 ◽  
Vol 45 ◽  
pp. 246-247
Author(s):  
R.A. Herring
Keyword(s):  
Device Fabrication ◽  
High Concentration ◽  
Tem Analysis ◽  
Defect Clusters ◽  
High Fluences ◽  
Small Defect ◽  
Before And After ◽  
The Matrix ◽  
The Difference ◽  
Factor Type

Rapid thermal annealing (RTA) of ion-implanted Si is important for device fabrication. The defect structures of 2.5, 4.0, and 6.0 MeV As-implanted silicon irradiated to fluences of 2E14, 4E14, and 6E14, respectively, have been analyzed by electron diffraction both before and after RTA at 1100°C for 10 seconds. At such high fluences and energies the implanted As ions change the Si from crystalline to amorphous. Three distinct amorphous regions emerge due to the three implantation energies used (Fig. 1). The amorphous regions are separated from each other by crystalline Si (marked L1, L2, and L3 in Fig. 1) which contains a high concentration of small defect clusters. The small defect clusters were similar to what had been determined earlier as being amorphous zones since their contrast was principally of the structure-factor type that arises due to the difference in extinction distance between the matrix and damage regions.

Changes in Platelet Aggregability after Ovariectomy

1979 ◽  
Vol 42 (04) ◽  
pp. 1332-1339 ◽  
Author(s):  
Hiroh Yamazaki ◽  
Takeshi Motomiya ◽  
Minoru Sonoda ◽  
Noboru Miyagawa
Keyword(s):  
Platelet Count ◽  
Platelet Activation ◽  
Ovarian Hormones ◽  
Control Group ◽  
Platelet Aggregability ◽  
Appearance Rate ◽  
Before And After ◽  
The Difference ◽  
Induced Aggregation ◽  
Observation Period

SummaryChanges in platelets in 48 patients with uterine myoma before and after hysterectomy with and without ovariectomy were examined. Bilateral ovariectomy in 25 cases (ovariec-tomized group) and unilateral or non-ovariectomy in 23 cases (control group) were performed at the hysterectomy. Platelet count and an appearance rate of secondary aggregation decreased at one day after and increased at one week after the operation, similarly in both the ovariectomized and the control group. The appearance rate of secondary aggregation was reflected in an intensity of aggregation at 5 min after the addition of reagent to PRP. At one month after the operation, the appearance rate of secondary aggregation induced by 3 μM ADP showed a statistically significant decrease in comparison with the preoperation value (P <0.05) and the enhancement of 5-min aggregation was still observed in the control group, while ceased in the ovariectomized group. The difference between the two groups was significant (P < 0.05). There was almost no change in the speed and intensity of primary and secondary aggregation during the observation period. No significant differences in collagen-induced aggregation were noted between the two groups. The results suggest that ovarian hormones, mainly estrogen, facilitate platelet activation which is mediated by the so-called secondary aggregation.

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