Determination of absorption length of CO2 and high power diode laser radiation for ordinary Portland cement and its influence on the depth of melting

Abstract

The laser beam absorption lengths of CO 2 and a high power diode laser (HPDL) radiation for concrete have been determined. By employing Beer-Lambert's law the absorption lengths for concrete of CO 2 and a HPDL radiation were 470±22 µm and 177±15 µm respectively. Indeed, this was borne out somewhat from a cross-sectional analysis of the melt region produced by both lasers which showed melting occurred to a greater depth when the CO 2 laser was used.

Contrasting the beam interaction characteristics of selected lasers with a partially stabilized zirconia bio-ceramic

“…Moreover, this expression has been shown to be completely applicable to other composite and ceramic materials [23][24][25]. It is important to realise that the validity of (1) rests on the assumption that the plume species resulting from material removal absorb the laser beams in a similar manner to the solid.…”

“…Also, probable changes in the absorption level of the material as removal progresses are not taken in account by (1). Nonetheless, as the work of 6 Andrew et al [27], Schmidt et al [16] and Lawrence et al [23][24][25] demonstrated, this simple form of the expression is quite adequate as a first approximation. Also, according to Bäuerle [26] the expression is applicable to ablation processes which are either photophysical or photochemical in nature.…”

“…In contrast, comparative investigations of the differences in the beam interaction characteristics of the predominant materials processing lasers, the CO 2 , the Nd:YAG and the excimer laser, are few in number [12][13][14][15] [19,20] and polymeric [3,4] materials, noting that changes in the wettability characteristics of the material varied depending upon the laser type. Furthermore, Lawrence et al carried out a comparative study of the characteristic of the glazes generated on the surface of concrete with CO 2 and HPDL's [21,22], as well determining the absorption depths of CO 2 and HPDL beams in ordinary Portland cement [23,24] and an Al 2 O 3 -based refractory [25].…”

Surface treatment of an Al2O3-based refractory with CO2 and high power diode lasers for improved mechanical and chemical resistance characteristics

“…Based on these figures it is reasonable to assume that since the CO 2 laser beam is absorbed to a greater depth, then the melt depth will be more and the resulting meltpool will be larger and will therefore cool at a slower rate than that of the HPDL generated meltpool. Such a observation was made during similar investigations on ordinary Portland cement (OPC) carried out by Lawrence and Li [36,37]. If one considers the theories of constitutional supercooling and morphological stability [38][39][40][41], which are illustrated schematically in Fig.…”

A comparative investigation of the efficacy of CO2 and high-power diode lasers for the forming of EN3 mild steel sheets

“…In comprehensive investigations, Lawrence and Li compared the e V ects of CO 2 , Nd :YAG, excimer and HPDL radiation on the wettability characteristics of an Al 2 O 3 /SiO 2 based ceramic [35], a mild steel [36,37] and selected biomedical polymer (PMMA) [38], noting that changes in the wettability characteristics of the ceramic and the steel varied depending upon the laser type. In addition, Lawrence and Li carried out a comparative study of the characteristic of the glazes generated on the surface of concrete with the CO 2 laser and the HPDL [39,40], as well as determining the absorption depths of CO 2 and HPDL beams in ordinary Portland cement [41,42] and an Al 2 O 3 -based refractory [43].…”