In-situ monitoring of optical emission spectra for microscopic pores in metal additive manufacturing Submitted for Publication

2021 ◽  
pp. 1-21
Author(s):  
Wenbo Sun ◽  
Zhenhao Zhang ◽  
Wenjing Ren ◽  
Jyoti Mazumder ◽  
Jionghua (Judy) Jin
Keyword(s):  
Additive Manufacturing ◽  
Emission Spectra ◽  
Optical Emission ◽  
In Situ Monitoring ◽  
Melt Pool ◽  
Multiple Processes ◽  
Melt Pool Temperature ◽  
Optical Emission Spectra

Abstract Quality assurance techniques are increasingly demanded in additive manufacturing. Going beyond most of the existing research that focuses on the melt pool temperature monitoring, we develop a new method that monitors the in-situ optical emission spectra signals. Optical emission spectra signals have been showing a potential capability of detecting microscopic pores. The concept is to extract features from the optical emission spectra via deep auto-encoders, and then cluster the features into two quality groups to consider both unlabelled and labelled samples in a semi-supervised manner. The method is integrated with multitask learning to make it adaptable for the samples collected from multiple processes. Both a simulation example and a case study are performed to demonstrate the effectiveness of the proposed method.

scholarly journals On the Etching Mechanism of Highly Hydrogenated SiN Films by CF4/D2 Plasma: Comparison with CF4/H2

Coatings ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1535
Author(s):  
Shih-Nan Hsiao ◽  
Thi-Thuy-Nga Nguyen ◽  
Takayoshi Tsutsumi ◽  
Kenji Ishikawa ◽  
Makoto Sekine ◽  
...  
Keyword(s):  
Substrate Temperature ◽  
Etch Rate ◽  
Emission Spectra ◽  
Optical Emission ◽  
In Situ Monitoring ◽  
Photoelectron Spectra ◽  
Hydrogen Atoms ◽  
Hydrogen Dissociation ◽  
Optical Emission Spectra

With the increasing interest in dry etching of silicon nitride, utilization of hydrogen-contained fluorocarbon plasma has become one of the most important processes in manufacturing advanced semiconductor devices. The correlation between hydrogen-contained molecules from the plasmas and hydrogen atoms inside the SiN plays a crucial role in etching behavior. In this work, the influences of plasmas (CF4/D2 and CF4/H2) and substrate temperature (Ts, from −20 to 50 °C) on etch rates (ERs) of the PECVD SiN films were investigated. The etch rate performed by CF4/D2 plasma was higher than one obtained by CF4/H2 plasma at substrate temperature of 20 °C and higher. The optical emission spectra showed that the intensities of the fluorocarbon (FC), F, and Balmer emissions were stronger in the CF4/D2 plasma in comparison with CF4/H2. From X-ray photoelectron spectra, a thinner FC layer with a lower F/C ratio was found in the surface of the sample etched by the CF4/H2 plasma. The plasma density, gas phase concentration and FC thickness were not responsible for the higher etch rate in the CF4/D2 plasma. The abstraction of H inside the SiN films by deuterium and, in turn, hydrogen dissociation from Si or N molecules, supported by the results of in situ monitoring of surface structure using attenuated total reflectance-Fourier transform infrared spectroscopy, resulted in the enhanced ER in the CF4/D2 plasma case. The findings imply that the hydrogen dissociation plays an important role in the etching of PECVD-prepared SiN films when the hydrogen concentration of SiN is higher. For the films etched with the CF4/H2 at −20 °C, the increase in ER was attributed to a thinner FC layer and surface reactions. On the contrary, in the CF4/D2 case the dependence of ER on substrate temperature was the consequence of the factors which include the FC layer thickness (diffusion length) and the atomic mobility of the etchants (thermal activation reaction).

scholarly journals PREPARATION OF DIAMOND FILMS BY DC ARC DISCHARGE AND IN SITU MEASUREMENTS OF THE PLASMA BY OPTICAL EMISSION SPECTRA

1990 ◽  
Vol 39 (12) ◽  
pp. 1965
Author(s):  
ZHANG FANG-QING ◽  
ZHANG YA-FEI ◽  
YANG YING-HU ◽  
LI JING-QI ◽  
CHEN GUANG-HUA ◽  
...  
Keyword(s):  
Arc Discharge ◽  
Diamond Films ◽  
Emission Spectra ◽  
Optical Emission ◽  
In Situ Measurements ◽  
Dc Arc ◽  
Optical Emission Spectra

IN-SITU SPECTRAL ANALYSIS OF VERY HIGH FREQUENCY GLOW DISCHARGE (VHF-GD)

2002 ◽  
Vol 16 (28n29) ◽  
pp. 4475-4478 ◽  
Author(s):  
HUIDONG YANG ◽  
CHUNYA WU ◽  
SHAOZHENG XIONG ◽  
YAOHUA MAI ◽  
HONGBO LI ◽  
...  
Keyword(s):  
Excitation Frequency ◽  
Emission Spectra ◽  
Optical Emission ◽  
Excitation Power ◽  
Dilution Ratio ◽  
Very High Frequency ◽  
Hydrogen Dilution ◽  
Optical Emission Spectra ◽  
Very High

The intensities of SiH*, [Formula: see text] and H* of VHF-GD for depositing μc-Si:H were much higher than those of RF-GD for depositing a-Si:H. The SiH* intensity of VHF-GD became higher than its Si* intensity as the hydrogen dilution ratio decreased. The influences of the hydrogen dilution ratio on the plasma optical emission spectra also depended on the reaction pressure, the excitation power as well as the excitation frequency.

In situ observation of nucleation by optical emission spectra in CVD diamond

2010 ◽  
Vol 19 (1) ◽  
pp. 15-20 ◽  
Author(s):  
G.C. Chen ◽  
B. Li ◽  
H. Li ◽  
X.Q. Han ◽  
L.F. Hei ◽  
...  
Keyword(s):  
Emission Spectra ◽  
Optical Emission ◽  
Cvd Diamond ◽  
In Situ Observation ◽  
Optical Emission Spectra

scholarly journals Optical Emission Spectra of Oxygen Plasma Produced by Radio-Frequency Plasma

2009 ◽  
Vol 18 (2) ◽  
pp. 102-107
Author(s):  
Do-Yeob Kim ◽  
Min-Su Kim ◽  
Tae-Hoon Kim ◽  
Ghun-Sik Kim ◽  
Hyun-Young Choi ◽  
...  
Keyword(s):  
Radio Frequency ◽  
Oxygen Plasma ◽  
Emission Spectra ◽  
Optical Emission ◽  
Radio Frequency Plasma ◽  
Frequency Plasma ◽  
Optical Emission Spectra

scholarly journals REFORMING OF ETHANOL IN PLASMA-CATALYTIC SYSTEM WITH DC AND AC ROTATING GLIDING DISCHARGE

2021 ◽  
pp. 117-121
Author(s):  
O.A. Nedybaliuk ◽  
T.A. Tereshchenko ◽  
I.I. Fedirchyk ◽  
P.V. Tyshchuk ◽  
V.P. Demchina
Keyword(s):  
Synthesis Gas ◽  
Emission Spectra ◽  
Optical Emission ◽  
Reaction Chamber ◽  
Catalytic Reforming ◽  
Instantaneous Power ◽  
Wide Aperture ◽  
Ethanol Reforming ◽  
Gliding Discharge ◽  
Optical Emission Spectra

The article presents the results of the investigation of the reforming of ethanol into synthesis gas using a plasmacatalytic system with either AC or DC wide-aperture rotating gliding discharge. Current and voltage oscillograms of the wide-aperture rotating gliding discharge were measured. The time-dependence of the instantaneous power of the discharge in the air was built. The photographs of the discharge in the airflow and discharge during the ethanol reforming were compared. The optical emission spectra of the plasmas of the torches of AC and DC wide-aperture rotating gliding discharges were studied. The rotational and vibrational temperatures of the plasma torch in the reaction chamber were determined. The results of the gas-chromatography of the synthesis gas produced during the plasm-catalytic reforming of ethanol using either AC or DC rotating gliding discharge are presented.

scholarly journals Correlation between surface texture and internal defects in laser powder-bed fusion additive manufacturing

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Makiko Yonehara ◽  
Chika Kato ◽  
Toshi-Taka Ikeshoji ◽  
Koki Takeshita ◽  
Hideki Kyogoku
Keyword(s):  
Additive Manufacturing ◽  
Surface Texture ◽  
In Situ Monitoring ◽  
Mean Square ◽  
Powder Bed Fusion ◽  
Internal Defects ◽  
Powder Bed ◽  
Texture Parameters ◽  
Areal Surface

AbstractThe availability of an in-situ monitoring and feedback control system during the implementation of metal additive manufacturing technology ensures that high-quality finished parts are manufactured. This study aims to investigate the correlation between the surface texture and internal defects or density of laser-beam powder-bed fusion (LB-PBF) parts. In this study, 120 cubic specimens were fabricated via application of the LB-PBF process to the IN 718 Ni alloy powder. The density and 35 areal surface-texture parameters of manufactured specimens were determined based on the ISO 25,178–2 standard. Using a statistical method, a strong correlation was observed between the areal surface-texture parameters and density or internal defects within specimens. In particular, the areal surface-texture parameters of reduced dale height, core height, root-mean-square height, and root-mean-square gradient demonstrate a strong correlation with specimen density. Therefore, in-situ monitoring of these areal surface-texture parameters can facilitate their use as control variables in the feedback system.

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