Surface alloying of pure iron by molybdenum and tin by a continuous wave CO2 laser

In recent years, the effects of chromium on the transformation characteristics of pure iron and the structures produced thereby have been extensively studied as a function of cooling rate. In this paper, we present TEM observations made on specimens of Fe-10% Cr and Fe-20% Cr alloys produced through laser surface alloying process with an estimated cooling rate of 8.8 x 104°C/sec. These two chromium levels were selected in order to study their phase transformation characteristics which are dissimilar in the two cases as predicted by the constitution diagram. Pure iron (C<0.01%, Si<0.01%, Mn<0.01%, S=0.003%, P=0.008%) was electrodeposited with chromium to the thicknesses of 40 and 70μm and then vacuum degassed at 400°F to remove the hydrogen formed during electroplating. Laser surface alloying of chromium into the iron substrate was then performed employing a continuous wave CO2 laser operated at an incident power of 1200 watts. The laser beam, defocussed to a spot diameter of 0.25mm, scanned the material surface at a rate of 30mm/sec, (70 ipm).

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Thin-Film Processing of Polypropylene and Polystyrene Sheets by a Continuous Wave CO2 Laser with the Cu Cooling Base

Polymers ◽

10.3390/polym13091448 ◽

2021 ◽

Vol 13 (9) ◽

pp. 1448

Author(s):

Nobukazu Kameyama ◽

Hiroki Yoshida ◽

Hitoshi Fukagawa ◽

Kotaro Yamada ◽

Mitsutaka Fukuda

Keyword(s):

Thin Film ◽

Co2 Laser ◽

Continuous Wave ◽

Cw Laser ◽

Heat Effects ◽

Film Processing ◽

Carbon Dioxide Co2 ◽

A Minor ◽

Residual Heat ◽

Thin Film Processing

Carbon dioxide (CO2) laser is widely used in commercial and industrial fields to process various materials including polymers, most of which have high absorptivity in infrared spectrum. Thin-film processing by the continuous wave (CW) laser is difficult since polymers are deformed and damaged by the residual heat. We developed the new method to make polypropylene (PP) and polystyrene (PS) sheets thin. The sheets are pressed to a Cu base by extracting air between the sheets and the base during laser processing. It realizes to cut the sheets to around 50 µm thick with less heat effects on the backside which are inevitable for thermal processing using the CW laser. It is considered that the boundary between the sheets and the base is in thermal equilibrium and the base prevents the sheets from deforming to support the backside. The method is applicable to practical use since it does not need any complex controls and is easy to install to an existing equipment with a minor change of the stage.

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Threshold of permanent cornea thermal damage due to incidental continuous wave CO2 laser irradiation

Thermal Science ◽

10.2298/tsci1002459t ◽

2010 ◽

Vol 14 (2) ◽

pp. 459-467 ◽

Cited By ~ 1

Author(s):

Mayada Tahir

Keyword(s):

Laser Irradiation ◽

Co2 Laser ◽

Thermal Damage ◽

Continuous Wave ◽

Anterior Part ◽

Outer Part ◽

Human Cornea ◽

Thermal Dose ◽

Element Analysis ◽

Reflex Blink

Cornea thermal damage due to incidental continuous wave CO2 laser irradiation is studied numerically based on bio-heat equation. The interaction of laser with tissue leads to a rapid temperature increased in target and the nearby tissue. As the temperature of the eye surface reaches 44?C, a sensation of pain will cause aversion response of the reflex blink and/or shifting away from the source of pain. The aim of the work is to predict numerically the threshold limit of incidental laser power that causes damage to the anterior part of the cornea, which can be healed within 2-5 days as long as damage is not exceeding the outer part of the eye (epithelium). A finite element analysis is used to predict temperature distribution through the cornea where the necroses region can be obtained using thermal dose equation. The thermal dose that required for damaging the cornea is predicted from previously published experimental data on rhesus monkeys and used later as a limit for shrinkage to human cornea. The result of this work is compared by international standard of safety and a good nearby result is obtained which verified the result of this work.

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