Experimental Investigations of Laser Micromachining of Nickel Using Thin Film Micro Thermocouples

2008 ◽  
Vol 130 (2) ◽  
Author(s):  
Hongseok Choi ◽  
Xiaochun Li
Keyword(s):  
Thin Film ◽  
Surface Temperature ◽  
Laser Energy ◽  
Laser Micromachining ◽  
Laser Spot ◽  
Experimental Investigations ◽  
Operation Temperature ◽  
Fundamental Understanding ◽  
Thin Film Thermocouples ◽  
Complex Phenomena

Laser-material interactions during laser micromachining are extremely complicated. In order to improve the fundamental understanding of the laser micromachining process, it is essential to investigate the complex phenomena and mechanisms of the physical processes within and close to the region of the interaction. Moreover, C-type micro thin film thermocouples with a junction size of 2×2μm2 were fabricated to increase the maximum operation temperature and spatial resolution of sensors. Surface temperature distribution around the laser spot was obtained in the range from 45μmto85μm away from the center of laser spot. The result showed that there was a steep gradient of temperature in the radial direction and a superheated area around the laser spot. Topographical characterizations of laser micromachining with various laser energy fluences were undertaken to correlate the resulting geometry changes with surface temperature measurements. Possible changes of surface chemical composition induced by the laser micromachining process, in particular, oxide formation, were also investigated around the laser spot.

Experimental Investigations of Laser Micromachining of Metal Using Micro Thin Film Thermocouples

2007 ◽  
Author(s):  
Hongseok Choi ◽  
Xiaochun Li
Keyword(s):  
Thin Film ◽  
Surface Temperature ◽  
Laser Energy ◽  
Laser Micromachining ◽  
Temperature Measurements ◽  
Laser Spot ◽  
Experimental Investigations ◽  
Operation Temperature ◽  
Thin Film Thermocouples ◽  
Complex Phenomena

Laser-material interactions involved in laser micromachining are extremely complicated. In order to improve the fundamental understanding of the laser micromachining process, it is essential to investigate the complex phenomena and mechanisms of the physical processes within and close to the region of the interaction. Topographical characterizations of laser micromachining with various laser energy fluences were undertaken to correlate the resulting geometry changes with surface temperature measurements. Single pulses of laser beam with a nominal diameter of 47 μm were used. Possible changes of surface chemical composition induced by the laser micromachining process, in particular oxide formation, were also investigated around the laser spot. Moreover, C-type micro thin film thermocouples (TFTCs) with a junction size of 2 μm × 2 μm were fabricated to increase the maximum operation temperature and spatial resolution of temperature measurements. Surface temperature distribution around the laser spot was obtained in the range from 45 μm to 85 μm away from the center of laser spot. The result showed that there was a steep gradient of temperature in the radial direction and a superheated area around laser spot. It was also observed that the temperature profile matched the oxidation profile due to thermal effects.

Transient Surface Temperature Measurement With Micro Sensors for Nanosecond Pulsed Laser Micromachining of Nickel

2006 ◽  
Author(s):  
Hongseok Choi ◽  
Xiaochun Li
Keyword(s):  
Laser Energy ◽  
Numerical Models ◽  
Pulsed Laser ◽  
Laser Micromachining ◽  
Measured Data ◽  
Time Resolved ◽  
Nanosecond Pulsed Laser ◽  
Thin Film Thermocouples ◽  
Transient Thermal ◽  
Thermal Phenomena

In order to investigate and understand the complicated transient thermal phenomena in laser micro processing, it is essential to accurately measure time-resolved temperatures of the workpiece. Micro thin film thermocouples with a micrometer spatial and nanosecond temporal resolution were fabricated on electroplated nickel workpieces to measure transient surface temperatures in nanosecond pulsed laser micromachining by ablation. Transient temperatures were successfully measured, and the effect of laser energy fluences on the peak temperatures was experimentally investigated. This study demonstrates that the micro TFTCs can be useful in measuring the transient temperatures on the workpiece during laser micromachining, and the measured data can be utilized to validate and improve existing analytical and numerical models.

Thin Film Thermocouples for Surface Temperature Measurement of Turbine Blade

2013 ◽  
Vol 873 ◽  
pp. 420-425 ◽  
Author(s):  
Yin Zhi Chen ◽  
Hong Chuan Jiang ◽  
Shu Wen Jiang ◽  
Xing Zhao Liu ◽  
Wan Li Zhang
Keyword(s):  
Thin Film ◽  
Seebeck Coefficient ◽  
Surface Temperature ◽  
Tin Oxide ◽  
Indium Tin Oxide ◽  
Life Time ◽  
Surface Temperature Measurement ◽  
Nickel Based Superalloy ◽  
Type K ◽  
Thin Film Thermocouples

There are three types thin film thermocouples (TFTCs) fabricated on the nickel-based superalloy substrates, including type-K (Ni-10%Cr/Ni-3%Si), type-S (Pt-10%Rh/Pt) and indium tin oxide (ITO) versus platinum (Pt) TFTCs. All of the samples were calibrated and cycled in tube furnace. The Seebeck coefficient of type-K, type-S and ITO/Pt TFTCs is 36.53 μV/°C, 8.89 μV/°C and 81.67 μV/°C, respectively. The life time of type-K and type-S TFTCs is 3 calibrating cycles (about 25 h) and 2 calibrating cycles (about 20 h), respectively. The ITO/Pt TFTCs shows longer life time that is longer than 5 cycles (about 50 h).

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