Temperature dependences of the optical properties of aluminum nanoparticles

Kalenskii, A. V.; Zvekov, A. A.

doi:10.1134/s1063785017060098

Cited by 2 publications

(3 citation statements)

References 12 publications

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“…Due to the strong interband transitions in both the solid and liquid state, X-point determination proves to be challenging, as the shifted peaks lead to three intersection points of the two curves instead of the expected single one. Although even in the thoroughly conducted literature study no explicitly stated values for the X-point of aluminum could be found, we were able to calculate estimates based on temperature-dependent absorptivity measurements [37,75]. According to these estimates, the X-point features a comparably strong temperature dependence and should be positioned at λ X, Al ≈ 950 nm.…”

Section: Comparison With the Process Stability Criterion Of Iron And ...mentioning

confidence: 93%

“…While temperature-dependent values for thermo-physical properties are available from commercial databases for pure metals, as well as alloys, there are no such ready-to-use data available in the literature or databases for the wavelength and temperature-dependent absorptivity A(λ, T). Thus, we conducted extensive literature research for the optical properties over a temperature range from room temperature to elevated temperatures at the molten state for copper [16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33], aluminum [27][28][29][30][34][35][36][37][38][39][40][41][42][43][44][45][46] and iron [26][27][28][29][30][46][47][48][49][50][51][52]…”

Section: Evaluation Of the Optical And Thermo-physical Propertiesmentioning

confidence: 99%

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Why Color Matters—Proposing a Quantitative Stability Criterion for Laser Beam Processing of Metals Based on Their Fundamental Optical Properties

Kohl

Kaufmann

Schmidt

2022

Metals

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With its excellent automation capability and localized energy input enabling precise, reproducible welds, laser beam welding represents a preferred industrial joining technology. Electro-mobility drastically increases the need for defect-free and automatable copper joining technologies. However, copper welds that are produced with state-of-the-art infrared lasers often suffer from spattering and porosity. Recent publications show distinct improvements using novel beam sources at visible wavelengths, attributing them to increased absorptivity. Nevertheless, this cannot fully explain the steadier process behavior. This wavelength-dependent process stability has not yet been investigated sufficiently. Therefore, we have developed a predictive material-dependent criterion indicating process stability based on the example of copper heat-conduction spot welding. For this purpose, we combined energy balances with thermo-physical material properties, taking into account the wavelength and temperature dependence of the optical properties. This paper presents the key mechanism that we identified as decisive for process stability. The criterion revealed that X-points (unique, material-specific wavelengths) represent critical stability indicators. Our calculations agree very well with experimental results on copper, steel and aluminum using two different wavelengths and demonstrate the decisive, material-dependent wavelength impact on process stability. This knowledge will help guide manufacturers and users to choose and develop beam sources that are tailored to the material being processed.

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Section: Comparison With the Process Stability Criterion Of Iron And ...mentioning

confidence: 93%

Section: Evaluation Of the Optical And Thermo-physical Propertiesmentioning

confidence: 99%

Why Color Matters—Proposing a Quantitative Stability Criterion for Laser Beam Processing of Metals Based on Their Fundamental Optical Properties

Kohl

Kaufmann

Schmidt

2022

Metals

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“…At wavelengths above this X-point, the emissivity increases with the temperature while it decreases below. For iron and platinum, the X-point was later found around 2 µm [10] and for aluminum at 0.95 µm [11]. In addition, the X-point was observed in several experiments regarding the temperature dependence of the absorptivity without relating to this phenomenon [8,12,13].…”

Section: Introductionmentioning

confidence: 99%

Energy Coupling of Laser Radiation on AISI 304 Stainless Steel: Effect of High Temperatures and Surface Oxidation

2019

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The industrial application of laser materials processing methods is still far ahead of research into the physical phenomena occurring during these processes. In particular, the effect of high temperatures on the energy coupling of laser irradiation of metals is poorly understood. However, most processes in laser materials treatment involve temperatures above the melting point or even cause evaporation. This study therefore evaluates the effect of high temperatures on the energy coupling efficiency of stainless steel experimentally for three typical laser wavelengths (515 nm, 1.07 µm, 10.6 µm). As a result, it is shown that the effect of temperature on the energy coupling efficiency depends on the wavelength. In this context the relevance of the X-point phenomenon known from the emissivity theory could be demonstrated for laser material processing. Further, the effect of a process-induced surface oxidation is analyzed. At temperatures above 650 °C the energy coupling efficiency dramatically increases to around 65% at melting point and stays at this high level even in the liquid phase.

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Temperature dependences of the optical properties of aluminum nanoparticles

Cited by 2 publications

References 12 publications

Why Color Matters—Proposing a Quantitative Stability Criterion for Laser Beam Processing of Metals Based on Their Fundamental Optical Properties

Why Color Matters—Proposing a Quantitative Stability Criterion for Laser Beam Processing of Metals Based on Their Fundamental Optical Properties

Energy Coupling of Laser Radiation on AISI 304 Stainless Steel: Effect of High Temperatures and Surface Oxidation

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