Correction of small imperfections on white glazed china surfaces by laser radiation

I. Képíró, K. Osvay, M. Divall

Research output: Contribution to journalArticle

Abstract

A laser-assisted technique has been developed for correction of small diameter (1 mm) and shallow (0.5 mm) imperfections on the surface of gloss fired porcelain. To study the physics and establish the important parameters, artificially made holes in a porcelain sample have been first filled with correction material, then covered with raw glaze and treated by a pulsed, 7 kHz repetition rate CO2 laser at 10.6 μm. The modification of the surface and the surrounding area have been quantified and studied with a large range of parameters of incident laser power (1-10 W), width of the laser pulses (10-125 μs) and duration of laser heating (60-480 s). Although the shine of the treated area, defined as the distribution of micro-droplets on the surface, is very similar to the untreated surfaces, the surroundings of the treated area usually show cracks. The measurement of both the spatial temperature distribution and the temporal cooling rate of the treated surface has revealed that a simple melting process always results in high gradient temperature distribution within the irradiated zone. Its inhomogeneous and fast cooling always generate at least micro-cracks on the surface within a few seconds after the laser was turned off. The duration and intensity of the laser irradiation have been then optimized in order to achieve the fastest possible melting of the surface, but without producing such high temperature gradients. To eliminate the cracks, more elaborated pre-heating and slowed-cooling-rate processes have been tried with prosperous results. These achievements complete our previous study, making possible to repair the most common surface imperfections and holes of gloss fired china samples.

Original languageEnglish
Pages (from-to)7798-7805
Number of pages8
JournalApplied Surface Science
Volume253
Issue number19
DOIs
Publication statusPublished - Jul 31 2007

Fingerprint

Laser radiation
China
laser beams
Defects
defects
porcelain
lasers
Dental Porcelain
Porcelain
cracks
Lasers
Cooling
Cracks
cooling
Melting
Temperature distribution
temperature distribution
melting
glazes
Laser heating

Keywords

  • Micro-cracks
  • Porcelain
  • Spatial temperature distribution

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films
  • Condensed Matter Physics

Cite this

Correction of small imperfections on white glazed china surfaces by laser radiation. / Képíró, I.; Osvay, K.; Divall, M.

In: Applied Surface Science, Vol. 253, No. 19, 31.07.2007, p. 7798-7805.

Research output: Contribution to journalArticle

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