Laser Processing of Thermally Sprayed Coatings

Surface and Coatings Technology

2003

Within both normal and corrosive (NaOH and HNO 3 ) environmental conditions, the wear rate and wear life characteristics of an Al 2 O 3 -based refractory were greatly enhanced by means of CO 2 and high power diode laser (HPDL) surface treatment. Such improvements are attributed to the fact that after laser treatment, the microstructure of the Al 2 O 3 -based refractory was altered from a porous, randomly ordered structure, to a much more dense and consolidated structure that contained fewer cracks and porosities. What is more, resulting from the different rates of solidification brought about by differences in the wavelengths of the two lasers, dissimilar microstructures were subsequently generated. Indeed, despite the fact that the glaze thickness was less, the wear life of the HPDL treated surface exceeded that of the CO 2 laser treated surface in all the test environments owing to its finer, more densely packed and less cracked microstructure.

Section: Introductionmentioning

confidence: 99%

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

Surface and Coatings Technology

2003

“…In contrast, several successful studies have shown the feasibility of using lasers to improve the surface characteristics of various ceramic and composite materials. The remelting of ZrO 2 -based protective ceramic layers using a CO 2 laser [13] was shown to result in a marked decrease in the level of structural defects. Further, the CO 2 laser remelting of a number of oxide ceramic coatings has been found to effect significant improvements in corrosion resistance 4 [14], whilst the CO 2 laser remelting of Al 2 O 3 and Al 2 O 3 -TiO 2 coatings yielded an increase in hardness and wear resistance [15].…”

Section: Introductionmentioning

confidence: 99%

Augmentation of the mechanical and chemical resistance characteristics of an Al2O3-based refractory by means of high power diode laser surface treatment

Journal of Materials Processing Technology

2003

Augmentation of the wear rate and wear life characteristics of an Al 2 O 3 -based refractory within both normal and corrosive (NaOH and HNO 3 ) environmental conditions was effected by means of high power diode laser (HPDL) surface treatment. Life assessment testing revealed that the HPDL generated glaze increased the wear life of the Al 2 O 3 -based refractory by 1.27 to 13.44 times depending upon the environmental conditions. Such improvements are attributed to the fact that after laser treatment, the microstructure of the Al 2 O 3 -based refractory was altered from a porous, randomly ordered structure, to a much more dense and consolidated structure that contained fewer cracks and porosities. In a world economy that is increasingly placing more importance on material conservation, a technique of this kind for delaying the unavoidable erosion (wear) and corrosion that materials such as the Al 2 O 3 -based refractory must face may provide an economically attractive option for contemporary engineers.

“…The remelting of ZrO 2 -based protective ceramic layers using a CO 2 laser [5] was shown to result in a marked decrease the level of structural defects. Further, the CO 2 laser remelting of a number of oxide ceramic coatings has been found to effect significant improvements in corrosion resistance [6], whilst the CO 2 laser remelting of Al 2 O 3 and Al 2 O 3 -TiO 2 coatings yielded an increase in hardness and wear resistance [7].…”

Section: Introductionmentioning

confidence: 99%

A portable high-power diode laser-based single-stage ceramic tile grout sealing system

Optics & Laser Technology

Schmidt

et al. 2002

By means of a 60 W high power diode laser (HPDL) and a specially developed grout material the void between adjoining ceramic tiles has been successfully sealed. A single-stage process has been developed which uses a crushed ceramic tile mix to act as a tough, inexpensive bulk substrate and a glazed enamel surface to provide an impervious surface glaze. The single-stage ceramic tile grout sealing process yielded seals produced in normal atmospheric conditions that displayed no discernible cracks and porosities. The single-stage grout is simple to formulate and easy to apply.Tiles were successfully sealed with power densities as low as 200 kW/mm 2 and at rates of up to 600 mm/min. Bonding of the enamel to the crushed ceramic tile mix was identified as being primarily due to van der Waals forces and, on a very small scale, some of the crushed ceramic tile mix material dissolving into the glaze. In terms of mechanical, physical and chemical characteristics, the singlestage ceramic tile grout was found to be far superior to the conventional epoxy tile grout and, in many instances, matched and occasionally surpassed that of the ceramic tiles themselves. What is more, the development of a hand-held HPDL beam delivery unit and the related procedures necessary to lead to the commercialisation of the single-stage ceramic tile grout sealing process are presented. Further, an appraisal of the potential hazards associated with the use of the HPDL in an industrial environment and the solutions implemented to ensure that the system complies with the relevant safety standards are given.