The combination of two laser energy sources for surface modification of high alumina ceramics

2001 ◽  
Author(s):  
D. Triatafyllidis ◽  
L. Li ◽  
F. H. Stott
Keyword(s):  
Surface Modification ◽  
Laser Energy ◽  
High Alumina ◽  
Energy Sources ◽  
Alumina Ceramics

Characterization of High Alumina Refractory Ceramics Treated with Combined Two Laser Surface Processing

2001 ◽  
Vol 697 ◽  
Author(s):  
Johanna R. Bernstein ◽  
Dimitris Triantafyllidis ◽  
Lin Li ◽  
F. Howard Stott
Keyword(s):  
Laser Energy ◽  
Erosive Wear ◽  
Industrial Applications ◽  
Chemical Degradation ◽  
High Alumina ◽  
Energy Sources ◽  
Large Temperature ◽  
Ongoing Work ◽  
Wear Damage ◽  
Alumina Refractory

AbstractAlumina-based refractory materials are extensively used in high-temperature industrial applications, such as for linings in waste and other incinerators. The existence of porosity and material inhomogeneities can promote chemical degradation due to molten slag penetration, while impacting solid or liquid feedstock can cause erosive-wear damage. Previous research has successfully used single laser energy sources to alter the surface properties of similar ceramics, with emphasis on sealing porosity and enhancing degradation resistance. However, this process has resulted in some solidification cracking at the surface due to large temperature gradients developed during processing. In the present, ongoing work, the surface of the refractory ceramic is modified by combining two laser energy sources to control the thermal gradients and cooling rates, with the objective of eliminating crack formation. The surface morphology and microstructures of the laser-treated areas are analyzed. This paper presents some initial results from the programme.

Machining and Wear of High-Alumina Ceramics for Structural Applications

2009 ◽  
Vol 409 ◽  
pp. 137-144 ◽  
Author(s):  
Stojana Veskovic-Bukudur ◽  
Tanja Leban ◽  
Milan Ambrozic ◽  
Tomaž Kosmač
Keyword(s):  
Grain Size ◽  
Wear Rate ◽  
Abrasive Wear ◽  
Direct Relationship ◽  
Bending Strength ◽  
High Alumina ◽  
Alumina Ceramics ◽  
Large Area ◽  
Structural Applications ◽  
Worn Surfaces

The wear resistances of four standard-grade high-alumina ceramics were evaluated and related to their machining ability. Three of the material grades contained 96% of alumina and 4% of either calcium silicate, or magnesium silicate, or manganese titanate in the starting-powder composition. The nominal alumina content in the fourth material was 99.7%. The specimens were fabricated using a low-pressure injection-molding forming technique, followed by thermal de-binding and sintering. After sintering the four materials differ significantly in their grain size, bending strength and Vickers hardness. No direct relationship between the microstructural parameters and the mechanical properties was found, but there was a grain-size dependence of the surface finish after grinding under industrial conditions. The two silicate-containing ceramics exhibited considerably higher wear resistances than the two silicate-free ceramics, but no direct relationship between the abrasive wear rate during grinding and the cutting time was observed. The cutting ability represents a valuable material characteristic for industrial practice, but it should not be directly used for predicting the wear rate during grinding. Quantitative differences in the cutting time and abrasive wear rate were manifested in the different topographies of the worn surfaces. Cutting resulted in relatively large area fractions of plastically deformed surfaces, whereas pullouts dominated the worn surfaces after grinding.

Surface Modification and Ablation of Insulators Using a Tunable, Picosecond Mid-Infrared Laser

1998 ◽  
Vol 526 ◽  
Author(s):  
R. F. Haglund ◽  
D. R. Ermer ◽  
A. H. Lines ◽  
M. R. Papantonakis ◽  
H. K. Park ◽  
...  
Keyword(s):  
Surface Modification ◽  
Near Infrared ◽  
Energy Content ◽  
Laser Energy ◽  
Vibrational Excitation ◽  
Average Power ◽  
Surface Modifications ◽  
Fused Silica ◽  
Laser Source ◽  
Near Ultraviolet

AbstractUltrashort-pulse lasers with fundamental wavelengths ranging from near-infrared to near-ultraviolet are increasingly being used for laser-induced surface modification of non-metallic solids. The relaxation of the initial electronic excitation into vibrational relaxation modes can produce efficient ablation and other desirable surface modifications with little collateral damage because the laser energy is deposited on a time scale much shorter than thermal diffusion times. Little is known, however, about how ultrashort pulses interact with insulators at wavelengths in the vibrational infrared. This paper describes surface modifications achieved by picosecond laser irradiation in the 2-10 lim range. The laser source was a tunable, free-electron laser (FEL) with I-ps micro-pulses spaced 350 ps apart in a macropulse lasting up to 4 μs, with an average power of up to 3 W. This unusual pulse structure makes possible novel tests of the influences vs fluence and intensity, as well as the effects of resonant vibrational excitation. As model materials systems, we studied calcium carbonate, its isoelectronic cousin sodium nitrate, and fused silica. Particularly intriguing are surface modifications achieved by tuning the laser into vibrational resonances and overtones of the target materials, or by tailoring the energy content of the pulse. The mechanisms underlying these effects, and their implications for materials-modification strategies, are discussed.

Premetallizing of high alumina ceramics

1985 ◽  
Vol 11 (4) ◽  
pp. 135
Author(s):  
G. Visomblin ◽  
D. Tchoubar
Keyword(s):  
High Alumina ◽  
Alumina Ceramics

Surface Modification Induced by Femtosecond Laser Pulses in Lithium Niobate

2011 ◽  
Vol 142 ◽  
pp. 134-137
Author(s):  
Hong Yun Chen ◽  
Zhen Zhu Wan ◽  
Yan Ling Han
Keyword(s):  
Surface Modification ◽  
Lithium Niobate ◽  
Femtosecond Laser ◽  
Laser Energy ◽  
Laser Pulses ◽  
Sample Surface ◽  
Femtosecond Laser Pulses ◽  
Two Dimensional ◽  
Damage Depth ◽  
Transparent Materials

The interaction between femtoseocnd laser and transparent materials has been studied intensively in recent years. When the femtosecond laser was focused onto the surface of the transparent materials, if the laser fluence applied to the sample exceeds the material’s fluence threshold, ablation occurs. In this paper, we study the surface ablation of lithium niobate by femtosecond laser. We produced a two-dimensional array of voids in the sample surface by varying the number of shots and laser energy, and analyze of the damage depth with the relation to the pulse energy and the number of the pulse. It has important reference on the microfabrication in such materials by femtosecond laser.

Elastic properties of high-alumina ceramics at low temperatures

1979 ◽  
Vol 36 (3) ◽  
pp. 159-160
Author(s):  
N. S. Kostyukov ◽  
�. V. Pozdeeva ◽  
A. A. Botaki ◽  
V. L. Ul'yanov
Keyword(s):  
Elastic Properties ◽  
Low Temperatures ◽  
High Alumina ◽  
Alumina Ceramics
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