scholarly journals Preliminary Laser Cleaning Studies of a Consolidated Prehistoric Basketry Coming from the Pile Building of Fiavè-Carera in the North-East of Italy

2006 ◽  
Vol 2006 ◽  
pp. 1-5 ◽  
Author(s):  
Romina Belli ◽  
Antonio Miotello ◽  
Paolo Mosaner ◽  
Laura Toniutti ◽  
Marta Bazzanella
Keyword(s):  
Energy Density ◽  
Material Removal ◽  
Laser Energy ◽  
Laser Cleaning ◽  
Original Surface ◽  
North East ◽  
The North ◽  
Cleaning Procedures ◽  
Krf Excimer Laser ◽  
Organic Deposits

In the archaeological field, some specific advantages are recognized to laser cleaning, like, for example, the absence of mechanical contacts with the sample. The cleaning procedures generally involve a multilayer structure (dust, dirty, organic deposits, and, in some cases, consolidant substances). In this work, prehistoric wood samples (found and consolidated in 1970s) have been laser irradiated (KrF excimer laser) in order to restore their original surface aspect. A certain amount of burned matter was also present. Samples came from a fragment of a prehistoric basketry found in the lake dwelling site of Fiavè-Carera, Trento, Italy (1500–1400 BC). It was observed that the laser cleaning effects are strictly dependent on the irradiation parameters (power density and number of pulses). Efficient material removal was possible by using appropriate energy density. Moreover, for lower laser energy density, special structures appeared on the surface of the consolidating substance that we attributed to heating-induced stresses on the consolidant surface.

Removal characteristics of shop-primer paint by laser energy density in Q-switching fiber laser cleaning

2020 ◽  
Vol 34 (07n09) ◽  
pp. 2040042
Author(s):  
Ji-Eon Kim ◽  
Myoung-Soo Han ◽  
Jong-Do Kim
Keyword(s):  
Energy Density ◽  
Fiber Laser ◽  
Oxide Layer ◽  
Base Metal ◽  
Steel Surface ◽  
Laser Energy ◽  
Laser Cleaning ◽  
Low Energy ◽  
Laser Energy Density ◽  
Q Switching

In this study, we performed laser cleaning using a Q-switching fiber laser to remove the shop-primer paint and the oxide layer. An analysis of the surface cleaned by laser was carried out at various energy densities. The results showed that the oxide layer on the steel surface was not removed at a relatively low energy density, whereas the base metal was damaged under excessive energy density. We confirmed that it was essential to select an appropriate energy density for efficiently removing only the paint and the oxide layer without damaging the base metal in laser cleaning.

scholarly journals Properties of Jet-Plated Ni Coating on Ti Alloy (Ti6Al4V) with Laser Cleaning Pretreatment

Metals ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 248
Author(s):  
Xiao Wang ◽  
Mingyang Xu ◽  
Zhanwen Wang ◽  
Lida Shen ◽  
Mingbo Qiu ◽  
...  
Keyword(s):  
Wear Resistance ◽  
Titanium Alloy ◽  
Energy Density ◽  
Oxide Layer ◽  
High Efficiency ◽  
Laser Energy ◽  
Laser Cleaning ◽  
Laser Energy Density ◽  
Wear Volume ◽  
Jet Electrodeposition

The surface mechanical properties of the Selective Laser Melting (SLM) formed Ti6Al4V samples were improved by adopting a novel laser cleaning pretreatment process combined with a jet electrodeposition process. This paper aimed to investigate the effects of different laser powers on the morphologies and adhesions of the nickel coatings. The advantages of the laser cleaning process are no grinding, no contact, high efficiency and environmental protection. The morphologies, adhesion, wear resistance, and hardness of the coatings were characterized. The results indicate that when the laser energy density reached 20% (4 J/cm2), the contaminations on the substrate and the oxide layer were removed and the crystalline grain of the coating was 15.3 nm. The shallow pits generated by laser burning increased the adhesion of the coatings. In addition, when the laser energy density increased to 6 J/cm2, a yellow oxide layer was produced on the surface of the cleaned titanium alloy. Moreover, the wear resistance of the titanium alloy after the nickel plating was improved. The wear volume was only 0.046 mm3, and the hardness increased to 1967.6 N/mm2.

Mechanical properties of pulsed laser-deposited hydroxyapatite thin films for applications in biomedical implants

2002 ◽  
Vol 750 ◽  
Author(s):  
Hyunbin Kim ◽  
Yogesh K. Vohra ◽  
William R. Lacefield ◽  
Renato P. Camata
Keyword(s):  
Thin Films ◽  
Mechanical Properties ◽  
Energy Density ◽  
Laser Energy ◽  
Pulsed Laser ◽  
X Ray Diffraction ◽  
X Ray ◽  
Krf Excimer Laser ◽  
Average Size ◽  
Substrate Temperatures

ABSTRACTWe have obtained nanostructured hydroxyapatite thin films on titanium alloy substrates by pulsed laser deposition. Deposition was carried out using a KrF excimer laser (248 nm) with the energy density of 4 – 7 J/cm2 at substrate temperatures in the 550°C - 650°C range. The crystallinity of the coatings was probed by X-ray diffraction. Phase transitions from hydroxyapatite to other calcium phosphate compounds were observed with varying the substrate temperature during the growth process. Scanning electron microscopy revealed thin films made up of partially sintered nanoscale grains. The average size of nanoscale grains increased significantly with film thickness, suggesting a growth mechanism involving the coalescence of nanoscale grains. As the laser energy density increases, the hydroxyapatite crystallites in the coatings are oriented preferentially along the c-axis perpendicular to the substrate. Mechanical properties of the highly c-axis oriented coatings such as hardness and Young's modulus were studied by using nanoindentation technique.

scholarly journals Research on mechanism and process of paint removal with pulsed fiber laser

2018 ◽  
Vol 189 ◽  
pp. 01008
Author(s):  
Xiaodi Zeng ◽  
Wenbin Qin ◽  
Jing Li ◽  
Zhiyong Wang
Keyword(s):  
Energy Density ◽  
Fiber Laser ◽  
Laser Energy ◽  
Steel Substrate ◽  
Paint Layer ◽  
Laser Cleaning ◽  
Laser Energy Density ◽  
Cleaning Efficiency ◽  
Pulsed Fiber Laser ◽  
Paint Removal

Compared with the traditional cleaning technology, laser cleaning, as a new type of industrial technology, has the advantages of high cleaning rate, green pollution-free and low cost. So laser cleaning is widely used in the fields of paint removal. This paper analyzes that the mechanism of paint removal and heat transfer process in the paint layer and substrate, also determines the process parameters of affect the laser paint removal. The removal of paint from steel substrate with fiber laser of frequency adjustable 20 to 500kHz at 1064nm is reported, researching impact that laser energy density,scanning speed and line width on the paint removal effect. The results show that, the 100μm paint layer can be removed completely while keeping the substrate undamaged with the laser energy density of 10.19J/cm2 and speed of 4200mm/s and width of 0.02mm. In order to get better results, the cleaning efficiency can be improved by increasing the power, speed and spot size under the right energy density.

Ras al Khaimah: further archaeological discoveries

Antiquity ◽  
1976 ◽  
Vol 50 (200) ◽  
pp. 216-222
Author(s):  
Beatrice De Cardi
Keyword(s):  
United Arab Emirates ◽  
The State ◽  
Focused Attention ◽  
North East ◽  
The North ◽  
History Of ◽  
The City

Ras a1 Khaimah is the most northerly of the seven states comprising the United Arab Emirates and its Ruler, H. H. Sheikh Saqr bin Mohammad al-Qasimi, is keenly interested in the history of the state and its people. Survey carried out there jointly with Dr D. B. Doe in 1968 had focused attention on the site of JuIfar which lies just north of the present town of Ras a1 Khaimah (de Cardi, 1971, 230-2). Julfar was in existence in Abbasid times and its importance as an entrep6t during the sixteenth and seventeenth centuries-the Portuguese Period-is reflected by the quantity and variety of imported wares to be found among the ruins of the city. Most of the sites discovered during the survey dated from that period but a group of cairns near Ghalilah and some long gabled graves in the Shimal area to the north-east of the date-groves behind Ras a1 Khaimah (map, FIG. I) clearly represented a more distant past.

Lichens in the North-East regions of Cyprus

1999 ◽  
Vol 110 (5-6) ◽  
pp. 455-463 ◽  
Author(s):  
S. Güvenç ◽  
Ş Öztürk
Keyword(s):  
North East ◽  
The North

TBE in Italy

2019 ◽  
Author(s):  
Valentina Tagliapietra ◽  
Flavia Riccardo ◽  
Giovanni Rezza
Keyword(s):  
Case Series ◽  
East Part ◽  
Mountainous Regions ◽  
North East ◽  
The North ◽  
Tick Borne Encephalitis ◽  
Low Incidence

Italy is considered a low incidence country for tick-borne encephalitis (TBE) in Europe. Areas at higher risk for TBE in Italy are geographically clustered in the forested and mountainous regions and provinces in the north east part of the country, as suggested by TBE case series published over the last decade.

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