Wettability characteristics of a modified mild steel with CO 2 , Nd:YAG, excimer and high power diode lasers

Optics and Lasers in Engineering

2004

Self Cite

Certain differences between the interaction characteristics of a CO 2 laser, a Nd:YAG laser and a high power diode laser (HPDL) with an alpha-alumina bioceramic have been investigated. For each laser the fluence threshold values at which significant material removal occurs were found graphically.Through the implementation of a derivative of Beer-Lambert's law, the laser beam absorption lengths were calculated along with the thermal loading values. An examination of the laser induced meltpool propagation in the alpha-alumina revealed good agreement with the Stefan solution to the heat diffusion equation for the lasers. Absorptivity measurements revealed that there was no correlation between the actual absorptivity of the alpha-alumina and the absorption length for each of the three lasers on account of the absorptivity measurements being similar for each laser. However, differences in the depth of melting experienced by the alpha-alumina meant that it is reasonable to assume that absorption length is the principal influence on the melt depth.

Section: Introductionmentioning

confidence: 99%

An analysis of the beam interaction characteristics of selected lasers with an alpha-alumina bioceramic

Optics and Lasers in Engineering

2004

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“…Yet the reasons for these changes with regard to changes in the material's surface morphology, surface composition and surface energy are not reported. However, in a number of more comprehensive investigations by Lawrence et al, which compared the effects of CO 2 , Nd:YAG, excimer and HPDL radiation on the wettability characteristics of a mild steel [20,21] and a SiO 2 /Al 2 O 3 -based ceramic material [22], it was found that changes in the wettability characteristics of the steel varied depending upon the laser type. Furthermore Lawrence et al have conducted numerous studies to investigate the feasibility and characteristics of laser enamelling ceramic materials [23][24][25][26] and steels [27,28].…”

Section: Introductionmentioning

confidence: 99%

The enamelling of concrete for improved performance characteristics by means of high power diode laser interaction

Journal of Materials Processing Technology

2003

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The contemporary 120 W high power diode laser (HPDL) has been successfully used for the first time to fire an enamel glaze onto the ordinary Portland cement (OPC) surface of concrete. The enamel glazes were generated with laser power densities as low as 1 kW/cm 2 and at speeds of up to 780 mm/min, yielding a possible maximum coverage rate of 0.34 m 2 /h. The enamel glazes were typically 750 µm in thickness and displayed no discernible microcracks or porosities. Owing to the wettability characteristics of the OPC, it proved necessary to laser treat the OPC surface prior to firing the enamel. Mechanical testing of the HPDL fired enamel glazes revealed that the average rupture strength was 2.8 J, whilst the rupture strength of the untreated OPC surface was some 4.3 J. The average bond strength of the glaze was recorded as 2.4 MPa as opposed to 6.3 MPa for the untreated OPC. The HPDL fired enamel glazes exhibited exceptional wear and corrosion resistance, wearing by only 3.3 mg/cm 2 after 8 h and showing no discernible morphological or microstructural changes when exposed to acid, alkali and detergent. In contrast, the untreated OPC surface was attacked almost immediately by the reagents used and was worn by 78 mg/cm 2 after 8 h. In addition, the HPDL fired enamel glaze afforded the concrete bulk complete resistance to water absorption. The findings of life assessment testing revealed that the HPDL fired enamel glaze effected an increase in the wear life of the concrete by 4.5 to 52.7 times over an untreated OPC surface, depending on the corrosive environment.

“…In more comprehensive investigations, Lawrence et al compared the effects of CO 2 , Nd:YAG, excimer and HPDL radiation on the wettability characteristics of ceramics [3,4] and a mild steel [5,6], noting that in all instances, changes in the wettability characteristics of the material varied depending upon the laser type.…”

Section: Introductionmentioning

confidence: 99%

Determination of the absorption length of CO2, Nd:YAG and high power diode laser radiation for a selected grouting material

Applied Surface Science

Minami

et al. 2002

The laser beam absorption lengths of CO 2 , Nd:YAG and a high power diode laser (HPDL) radiation for a newly developed SiO 2 /Al 2 O 3 -based tile grout have been determined through the application of Beer-Lambert's law. The findings revealed marked differences in the absorption lengths despite the material having similar beam absorption coefficients for the lasers. The absorption lengths for the SiO 2 /Al 2 O 3 -based tile grout for CO 2 , Nd:YAG and HPDL radiation were calculated as being 232±11 µm, 193±4 µm and 183±8 µm respectively. Moreover, this method of laser beam absorption length determination, which has hitherto been used predominantly with lasers operated in the pulsed mode, is shown to be valid for use with lasers operated in the continuous wave (CW) mode, depending upon the material being treated.