Laser induced creep and fracture in ceramics

Pompe, W.; Bahr, H.‐A.; Pflugbeil, I.; Kirchhoff, G.; Langmeier, P.; Weiß, H.

doi:10.1016/s0921-5093(97)00061-0

Cited by 19 publications

(6 citation statements)

References 3 publications

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“…Consequently, when the laser heat passes, tensile stress builds up. This creep phenomenon is similar to the results of Pompe et al [12] and Modest [13].…”

Section: Stress Distributionsupporting

confidence: 91%

Formation of the breaking surface of alumina in laser cutting with a controlled fracture technique

Tsai

2003

Proceedings of the Institution of Mechanical Engineers, Part B:

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Laser cutting using the controlled fracture technique is based on the thermal breaking principle. The laser beam is applied to the surface of a ceramic substrate; the substrate is then controllably separated along the moving path of the laser beam. The fractography and cutting surface formation are studied in this work. It is found that the breaking surface can be divided into four regions. The ®rst region is the laser evaporation region produced by the heat concentration. The second region is the columnar grain region produced by resolidi®cation of the melted material. The third region is the intergranular fracture region produced by anisotropic thermal expansion. The fourth region is the transgranular fracture region characterized by unstable fractures. These experiments are conducted on alumina ceramics using a CO 2 laser. The fracture mechanism is analysed using stress analysis and fractographic observation. The tensile stress generated on the surface due to the laser beam separates the material along its path. The e ects of the cutting parameters such as the laser power, cutting speed, laser spot diameter and specimen geometry on the machining quality are obtained from the experimental analysis. It is concluded that the best cutting quality is obtained using a large laser spot size.

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“…Consequently, when the laser heat passes, tensile stress builds up. This creep phenomenon is similar to the results of Pompe et al [12] and Modest [13].…”

Section: Stress Distributionsupporting

confidence: 91%

Formation of the breaking surface of alumina in laser cutting with a controlled fracture technique

Tsai

2003

Proceedings of the Institution of Mechanical Engineers, Part B:

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“…Intensive cyclic surface heating by means of laser irradiation is a suitable test for the analysis of TBC damage evolution [46,[50][51][52]58]. It can be effectively applied for comparing the performance of non-graded and graded TBCs [51] for a wide range of temperatures and numbers of cycles.…”

Section: Laser-induced Tbc Damagementioning

confidence: 99%

Cracks in functionally graded materials

Bahr

Balke

Fett

et al. 2003

Materials Science and Engineering: A

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The weight function method is described to analyze the crack growth behavior in functionally graded materials and in particular materials with a rising crack growth resistance curve. Further, failure of graded thermal barrier coatings (TBCs) under cyclic surface heating by laser irradiation is modeled on the basis of fracture mechanics. The damage of both graded and non-graded TBCs is found to develop in several distinct stages: vertical cracking → delamination → blistering → spalling. This sequence can be understood as an effect of progressive shrinkage due to sintering and high-temperature creep during thermal cycling, which increases the energy-release rate for vertical cracks which subsequently turn into delamination cracks. The results of finite element modeling, taking into account the TBC damage mechanisms, are compatible with experimental data. An increase of interface fracture toughness due to grading and a decrease due to ageing have been measured in a four-point bending test modified by a stiffening layer. Correlation with the damage observed in cyclic heating is discussed. It is explained in which way grading is able to reduce the damage.

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“…They found that the heat-affected zone was observed in the holes and the micro-cracks extending around the holes. According to Pompe et al (1997), the heated region near the surface of an originally stress-free material gets loaded in compression. If the temperature was sufficiently high, the stress relaxes by creep.…”

Section: Introductionmentioning

confidence: 99%

Investigation of underwater laser drilling for brittle substrates

Tsai

2009

Journal of Materials Processing Technology

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Laser induced creep and fracture in ceramics

Cited by 19 publications

References 3 publications

Formation of the breaking surface of alumina in laser cutting with a controlled fracture technique

Formation of the breaking surface of alumina in laser cutting with a controlled fracture technique

Cracks in functionally graded materials

Investigation of underwater laser drilling for brittle substrates

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