The influence of a high power diode laser (HPDL) generated glaze on the wetting characteristics and the subsequent HPDL enamelling of ordinary Portland cement

High power diode laser (HPDL) surface glazing of the ordinary Portland cement (OPC) surface of concrete was found to effect significant changes in the wettability characteristics of the OPC. This behaviour was identified as being primarily due to: (i) the polar component of the OPC surface energy increasing after HPDL glazing from 3.46 to 15.56 mJm-2, (ii) the surface roughness of the OPC decreasing from an Ra value of 21.91 to 2.88 m after HPDL glazing and (iii) the relative surface O2 content of the OPC increasing by 4.5at% after HPDL glazing. HPDL glazing was consequently identified as occasioning a decrease in the enamel contact angle from an initial value of 1090 to 310, thus allowing the vitreous enamel to wet the OPC surface

The wear characteristics of a high power diode laser generated glaze on the ordinary Portland cement surface of concrete

The ordinary Portland cement (OPC) surface layer of concrete, which was glazed using a high power diode laser (HPDL), has been tested in order to determine the wear characteristics of the glaze. The work showed that the generation of a surface glaze resulted in the considerable enhancement of the wear characteristics over an untreated OPC surface of concrete. Within both normal and corrosive (detergent, NaOH and HNO3) environmental conditions the wear rate of the HPDL generated glaze was 3.5 mg.cm-2.h-1. In contrast, the untreated OPC surface of concrete exhibited a wear rate of 9.8 - 114.8 mg.cm-2.h-1 when exposed to the various reagents. Life assessment testing revealed that the laser glazed OPC surfaces effected an increase in actual wear life of 1.3 to 17.7 times over the untreated OPC surface of concrete, depending upon the corrosive environment. The reasons for these marked improvements in the wear resistance and wear life of the HPDL generated glaze over the untreated OPC surface of concrete can be attributed to firstly, the vitrification of the OPC surface after HPDL treatment which subsequently created a much more dense and consolidated surface, and secondly, the generation of a surface with improved microstructure and phase which is more resistant in corrosive environments

The influence of shield gases on the surface condition of laser treated concrete

This work aims to elucidate the effects of using O2, Ar and He shield gasses during the treatment of the ordinary Portland cement (OPC) surface of concrete with a high power diode laser (HPDL). The findings showed a marked difference existed in the surface condition of the concrete after HPDL treatment depending on the shield gas used. The use of O2 as the shield gas was seen to result in glazes with far fewer microcracks and porosities than those generated with either Ar or He shield gases. Such differences were found to be due to the smaller O2 gas molecules dissolving molecularly into the open structure of the HPDL generated glaze on the OPC surface of concrete and react with the glass network to increase the fluidity of the melt. This in turn was also seen to affect the cooling rate and therefore the tendency to generate microcracks

Carbon steel wettability characteristics enhancement for improved enamelling using a 1.2 kW high power diode laser

High-power diode laser (HPDL) surface treatment of a common engineering carbon steel(EN8) was found to effect significant changes to the wettability characteristics of the metal. These modifications have been investigated in terms of the changes in the surface roughness of the steel, the presence of any surface melting, the polar component of the steel surface energy and the relative surface oxygen content of the steel. The morphological and wetting characteristics of the mild steel and the enamel were determined using optical microscopy, scanning electron microscopy (SEM), X-ray photoemission spectroscopy (XPS), energy-dispersive X-ray (EDX) analysis and wetting experiments by the sessile drop technique. This work has shown that HPDL radiation can be used to alter the wetting characteristics of carbon steel so as to facilitate improved enamelling

Finite element analysis of temperature distribution using ABAQUS for a laser based tile grout sealing process

Interaction of CO2, Nd:YAG, excimer and high power diode laser (HPDL) radiation with the surface of an Al2O3/SiO2 based ceramic was found to effect significant changes in the wettability characteristics of the material. It was observed that interaction with CO2, Nd:YAG and HPDL radiation reduced the enamel contact angle from 1180 to 310, 340 and 330 respectively. In contrast, interaction with excimer laser radiation resulted an increase in the contact angle to 1210. Such changes were identified as being due to: (i) the melting and partial vitrification of the Al2O3/SiO2 based ceramic surface as a result of interaction with CO2, Nd:YAG HPDL radiation. (ii) the surface roughness of the Al2O3/SiO2 based ceramic increasing after interaction with excimer laser radiation. (iii) the surface oxygen content of the Al2O3/SiO2 based ceramic increasing after interaction with CO2, Nd:YAG and HPDL radiation. The work has shown that the wettability characteristics of the Al2O3/SiO2 based ceramic could be controlled and/or modified with laser surface treatment. In particular, whether the laser radiation had the propensity to cause surface melting. However, a wavelength dependance of the change of the wetting properties could not be deduced from the findings of this work

Surface glazing of concrete using a 2.5 kW high power diode lase

Interaction of CO2, Nd:YAG, excimer and high power diode laser (HPDL) radiation with the surface of an Al2O3/SiO2 based ceramic was found to affect significant changes in the wettability characteristics of the material. It was observed that interaction with CO2, Nd:YAG and HPDL radiation reduced the enamel contact angle from 1180 to 310, 340 and 330 respectively. In contrast, interaction with excimer laser radiation resulted an increase in the contact angle to 1210. Such changes were identified as being due to: (i) the melting and partial vitrification of the Al2O3/SiO2 based ceramic surface as a result of interaction with CO2, Nd:YAG HPDL radiation. (ii) the surface roughness of the Al2O3/SiO2 based ceramic increasing after interaction with excimer laser radiation. (iii) the relative surface oxygen content of the Al2O3/SiO2 based ceramic increasing after interaction with CO2, Nd:YAG and HPDL radiation. The work has shown that the wettability characteristics of the Al2O3/SiO2 based ceramic could be controlled and/or modified with laser surface treatment. Moreover, it was found that changes in the wettability characteristics of the Al2O3/SiO2 based ceramic are related to the effects of laser wavelength, that is whether the wavelength of the laser radiation has the propensity to cause surface melting

The characteristics of a high-power diode laser fired enamel coating on a carbon steel

Significant changes to the wettability characteristics of a common engineering carbon steel(EN8) were effected after high power diode laser (HPDL) surface treatment. These modifications havebeen investigated in terms of the changes in the surface roughness of the steel, the presence of any surface melting, the polar component of the steel surface energy and the relative surface O2 content of the steel. The morphological and wetting characteristics of the mild steel and the enamel were determined using optical microscopy, scanning electron microscopy, X-ray photoemission spectroscopy, energy-dispersive X-ray analysis and wetting experiments by the sessile drop technique. This work has shown that HPDL radiation can be used to alter the wetting characteristics of carbon steel so as to facilitate improved enamelling. Furthermore, standard mechanical, physical and chemical testing of the HPDL-fired enamel glaze revealed the glaze to possess similar properties to those of a conventionally fired enamel glaze in terms of bond strength, rupture /impact strength, wear and corrosion resistance. Such similar performance can be attributed to the two glazes possessing the same mechanical properties and similar amorphous structure, despite their very different firing techniques

A comparative study of the surface glaze characteristics of concrete treated with CO2 and high power diode lasers. Part I: glaze characteristics

This present work describes the differences in the characteristics of glazes generated on the ordinary Portland cement (OPC) surface of concrete by means of CO2 and high power diode laser (HPDL) radiation. The value of such an investigation would be to facilitate the hitherto impossible task of generating a durable and long-lasting surface seal on the concrete, thereby extending the life and applications base of the concrete. The basic process phenomena are investigated and the laser effects in terms of glaze morphology, composition, phase and microstructure are presented. Also, the resultant heat affects are analysed and described. The glaze generated after HPDL interaction was found be fully amorphous in nature, whilst the glaze generated after CO2 laser interaction was seen to be of a semi-amorphous structure, with sizeable areas, randomly located within the glaze, displayed a somewhat regular columnar structure. This is proposed to be due to the differing solidification rates occasioned by each laser after treatment as a result of differences in the beam absorption lengths

The effects of process gas type on the surface condition of high power diode laser treated ordinary Portland cement

This paper examines the effects of using O2, Ar and He process gasses during the treatment of the ordinary Portland cement (OPC) surface of concrete with a high power diode laser (HPDL). The study revealed that, depending on the shield gas used, distinct difference existed in the surface condition of the concrete after HPDL treatment. In particular, the use of O2 as the shield gas was seen to result in glazes with far fewer microcracks and porosities than those generated with either Ar or He shield gases. Such differences were found to be due to the smaller O2 gas molecules dissolving molecularly into the open structure of the HPDL generated glaze on the OPC surface of concrete and react with the glass network to increase the fluidity of the melt. This is turn was also seen to affect the cooling rate and therefore the tendency to generate microcracks

Wettability characteristics of polyethylene (PE) modified with CO2, Nd:YAG, excimer and high power diode lasers

Interaction of CO2, Nd:YAG, excimer and high power diode laser (HPDL) radiation with the surface of the bio-material, polyethylene (PE), was found to effect varying degrees of change to the wettability characteristics of the material depending upon the laser used. It was observed that interaction with CO2, Nd:YAG and HPDL effected very little change to wettability characteristics of the PE. In contrast, interaction of the PE with excimer laser radiation resulted an increase in a marked improvement in the wettability characteristics. After excimer laser treatment the surface O2 content was found to have increased and the material was seen to be more polar in nature, resulting in a significant increase in the wettability characteristics. The work has shown that the wettability characteristics of the PE could be controlled and/or modified with laser surface treatment. However, a wavelength dependence of the change of the wetting properties could not be deduced from the findings of this work