Characterization of isothermal and cyclic thermal damage of EB‐PVD TBCs with the help of the 3D‐DIC technique

2021 ◽  
Author(s):  
Shun Yang ◽  
Huang Yuan
Keyword(s):  
Thermal Damage ◽  
Dic Technique

Experimental Investigation of Laser Sintering of Conductive Adhesive for Functional Prototypes Produced by Embedding Stereolithography

2014 ◽  
Vol 1038 ◽  
pp. 75-81
Author(s):  
Bernd Niese ◽  
Philipp Amend ◽  
Uwe Urmoneit ◽  
Stephan Roth ◽  
Michael Schmidt
Keyword(s):  
Thermal Damage ◽  
Laser Sintering ◽  
Conductive Adhesive ◽  
Flexible Production ◽  
Sintering Process ◽  
Building Process ◽  
In Situ Generation ◽  
Functional Components

Embedding stereolithography (eSLA) is an additive, hybrid process, which provides a flexible production of 3D components and the ability to integrate electrical and optical conductive structures and functional components within parts. However, the embedding of conductive circuits in stereolithography (SLA) parts assumes usage of process technologies, which enables their direct integration of conductive circuits during the layer-wise building process. In this context, a promising method for in-situ generation of conductive circuits is dispensing of conductive adhesive on the current surface of the SLA part and its subsequent sintering. In this paper, the laser sintering (λ = 355 nm) of conductive adhesive mainly consisting of silver nanoparticles is investigated. The work intends to evaluate the curing behavior of the conductive adhesive, the beam-matter-interactions and the thermal damage of the SLA substrate. The investigations revealed a fast and flexible laser sintering process for the generation of conductive circuits with sufficient electrical conductivity and sufficient current capacity load. In this context, a characterization of the conductive structures is done by measuring their electrical resistance and their potential current capacity load.

Microstructural Characterization of Thermal Damage on Silicon Wafers Sliced Using Wire-Electrical Discharge Machining

2018 ◽  
Vol 140 (9) ◽  
Author(s):  
Kamlesh Joshi ◽  
Upendra Bhandarkar ◽  
Indradev Samajdar ◽  
Suhas S. Joshi
Keyword(s):  
Raman Spectroscopy ◽  
Electrical Discharge ◽  
Thermal Damage ◽  
Electrical Discharge Machining ◽  
Wafer Surface ◽  
Wire Electrical Discharge Machining ◽  
Wire Edm ◽  
Material Loss ◽  
Pulse On Time

Slicing of Si wafers through abrasive processes generates various surface defects on wafers such as cracks and surface contaminations. Also, the processes cause a significant material loss during slicing and subsequent polishing. Recently, efforts are being made to slice very thin wafers, and at the same time understand the thermal and microstructural damage caused due to sparking during wire-electrical discharge machining (wire-EDM). Wire-EDM has shown potential for slicing ultra-thin Si wafers of thickness < 200 μm. This work, therefore, presents an extensive experimental work on characterization of the thermal damage due to sparking during wire-EDM on ultra-thin wafers. The experiments were performed using Response surface methodology (RSM)-based central composite design (CCD). The damage was mainly characterized by scanning electron microscope (SEM), transmission electron microscopy (TEM), and Raman spectroscopy. The average thickness of thermal damage on the wafers was observed to be ∼16 μm. The damage was highly influenced by exposure time of wafer surface with EDM plasma spark. Also, with an increase in diameter of plasma spark, the surface roughness was found to increase. TEM micrographs have confirmed the formation of amorphous Si along with a region of fine grained Si entrapped inside the amorphous matrix. However, there were no signs of other defects like microcracks, twin boundaries, or fracture on the surfaces. Micro-Raman spectroscopy revealed that in order to slice a wafer with minimum residual stresses and very low presence of amorphous phases, it should be sliced at the lowest value of pulse on-time and at the highest value of open voltage (OV).

scholarly journals Characterization of Ablated Bone and Muscle for Long-Pulsed Laser Ablation in Dry and Wet Conditions

Materials ◽  
2019 ◽  
Vol 12 (8) ◽  
pp. 1338 ◽  
Author(s):  
Nguendon Kenhagho ◽  
Shevchik ◽  
Saeidi ◽  
Faivre ◽  
Meylan ◽  
...  
Keyword(s):  
Acoustic Waves ◽  
Thermal Damage ◽  
Pulsed Laser ◽  
Principal Component ◽  
Classification Error ◽  
Ablation Efficiency ◽  
Mahalanobis Distances ◽  
Dry Conditions ◽  
Fast Healing

Smart laser technologies are desired that can accurately cut and characterize tissues, such as bone and muscle, with minimal thermal damage and fast healing. Using a long-pulsed laser with a 0.5–10  ms pulse width at a wavelength of 1.07  µm, we investigated the optimum laser parameters for producing craters with minimal thermal damage under both wet and dry conditions. In different tissues (bone and muscle), we analyzed craters of various morphologies, depths, and volumes. We used a two-way Analysis of Variance (ANOVA) test to investigate whether there are significant differences in the ablation efficiency in wet versus dry conditions at each level of the pulse energy. We found that bone and muscle tissue ablated under wet conditions produced fewer cracks and less thermal damage around the craters than under dry conditions. In contrast to muscle, the ablation efficiency of bone under wet conditions was not higher than under dry conditions. Tissue differentiation was carried out based on measured acoustic waves. A Principal Component Analysis of the measured acoustic waves and Mahalanobis distances were used to differentiate bone and muscle under wet conditions. Bone and muscle ablated in wet conditions demonstrated a classification error of less than 6.66 % and 3.33 %, when measured by a microphone and a fiber Bragg grating, respectively.

The characterization of laser-induced thermal damage mechanism of mid-infrared optical coatings with surface contaminants

2020 ◽  
Vol 95 (3) ◽  
pp. 035507 ◽  
Author(s):  
Zhaokai Lou ◽  
Kai Han ◽  
Chaofan Zhang ◽  
Minsun Chen ◽  
Baozhu Yan ◽  
...  
Keyword(s):  
Thermal Damage ◽  
Damage Mechanism ◽  
Optical Coatings ◽  
Mid Infrared ◽  
Surface Contaminants
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