On phenomena in ionized gases
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- Fig. 1.
- 3. Results and discussion
- 5. References
- Air versus Helium atmospheric-pressure plasma for enhanced adhesion of woven textiles
- Calcium phosphate film formation on TiN surface created by atmospheric-pressure plasma
- 2. Experimental 2.1. PA plasma jet
- 4. References
- Investigation on local formation of expanded austenite phase by atmospheric-pressure plasma jet
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3. Results and discussion
First, we performed X-ray diffraction analysis of ITO films fabricated at various N 2 /(Ar + N 2 ). The
diffraction peak intensities of In 2 O 3 (222) and (400) planes decreases with increasing N 2 /(Ar + N 2 ) from 0 to 0.65%, and finally there is no peak detected for N 2 /(Ar + N 2 ) ≥ 1.5%. Figure 1 shows the absolute density of nitrogen and oxygen atoms as a parameter of N
2 /(Ar + N 2 ). The density of nitrogen atoms increases linearly from 1.3×10 10 to 1.6×10 11 cm
-3
with increasing N 2 /(Ar + N
2 ) from 0 to 10%, whereas the density of oxygen atoms is in the range of 3.9×10
9 –1.5×10
10 cm -3 . These results suggest that nitrogen atoms inhibit crystallization and disorder the In 2
3 bixbyte crystal structure, and thus leading to a-ITO films. Electron Hall mobility of a-ITO films increases from 14 to 55 cm 2 /Vs with increasing N 2 /(Ar+N
2 ) from 3 to 5%, while the nitrogen composition ratio of the films is almost constant (10–11 atomic %). Therefore, the improvement in the mobility of a-ITO films for N 2 /(Ar + N 2 )=3–5% is caused not by the nitrogen incorporation, but by the adsorption/desorption behavior of nitrogen atoms on the growing surface.
[1] T. Takasaki, et al., Proc. 68th GEC/9th ICRP/33rd SPP 60, 9, GT1, 150 (2015). [2] S. Takashima, M. Hori, T. Goto, A. Kono, M. Ito, and K. Yoneda, Appl. Phys. Lett. 75, (1999) 3929.
This work was supported by JSPS KAKENHI Grant Number 15H05431.
0 1x10 11 2x10 11 3x10
11 0 2 4 6 8 10 N an d O a to m d en sit
y (c m -3 ) N 2 / Ar + N 2 (%)
N atom O atom derived from targets Amorphous Polycrystalline
atoms in sputtering plasma as a parameter of N 2 /(Ar + N 2 ). Topic number 164
XXXIII ICPIG, July 9-14, 2017, Estoril/Lisbon, Portugal
Time
in presence of 3D textured dielectric layer
I. Topala, G. Borcia P
IPARC, Faculty of Physics, Alexandru Ioan Cuza University, Iasi, Romania
Atmospheric-pressure plasma represents particularly suitable technology for treating textiles. Nonetheless, fiber-based materials raise specific issues related to their surface processing, especially for woven materials, due to their particular 3D nature. In this respect, we are exploring the relation between the 3D structural characteristics of woven samples, the plasma parameters during sample exposure and the time space evolution of the discharge, aiming to establish the role of the heterogeneous nature of the permeable samples, working as supplementary di electric layer, in controlling the discharge, and thus the plasma processing efficiency. It results that such structures shift the behavior of the discharge and the plasma parameters, depending on the 3D characteristics.
Woven materials are heterogeneous structures, from mechanical, electrical and chemical point of view, and may shift the behavior of the discharge and the plasma parameters during processing, depending on their 3D characteristics. Taking this into account, we are exploring the relation between the woven structural characteristics, the plasma electrical parameters during sample exposure and the time
space evolution of the discharge.
The plasma is produced using DBD, in asymmetrical electrode arrangement [1]. The discharge is generated using positive voltage pulses with 5 kV amplitude, 5 kHz frequency, 100 s width. The DBD parameters are established by electrical measurement. Then, a fast imaging technique using an ICCD was employed to complete the information on the plasma parameters and the time
3. Results and discussion The voltage and current waveforms show two temporally distinct discharges, so-called primary and secondary discharge, respectively, associated to the HV rising and falling slope. The current profile for the primary discharge, which ignites due to the externally applied electric field, is different in presence of different samples (Fig. 1), whereas the current profile for the secondary discharge, igniting by the so-called “memory effect”, due to the charge deposited on the dielectric surface during the primary discharge, is similar for all samples.
Fig. 1. Current waveforms in presence various fabrics during the HV rising slope.
The amplitude of the current pulse and the discharge energy vary for different samples, resulting that the aspects related to the permeability of the structure, due to its weaving characteristics, play the major role in the behavior of the discharge. The total
light intensity shows different distribution of the discharge regions, for the primary and the secondary discharge. 4. Acknowledgement CASPIA project, Executive Agency for Higher Education Research Development and Innovation, Romania, PN-II-PT-PCCA-2013, grant 254/2014.
[1] G.B. Rusu, I. Topala, C. Borcia, N. Dumitrascu, G. Borcia, Plasma Chem. Plasma Process. 36 (2016) 341-354.
Topic number: 10 165 XXXIII ICPIG, July 9-14, 2017, Estoril/Lisbon, Portugal
Air versus Helium atmospheric-pressure plasma for enhanced adhesion of woven textiles
G. B. Rusu, I. Topala, C. Borcia, G. Borcia P
IPARC, Faculty of Physics, Alexandru Ioan Cuza University, Iasi, Romania
Atmospheric-pressure plasma treatment is used to improve the dyeing quality of woven structures. A comparison is carried out between inert gas and air atmospheric-pressure plasma, attempting to separate and analyze the physical and chemical plasma effects on the woven, under conditions where oxidation, hence chemical processes, likely superposes on the physical effect. This approach is useful in a context where the separation between combined cleaning chemistry roughness modification and their respective roles on the efficiency of the fabric dyeing procedure is more difficult. The results show that air plasma treatment probably brings a supplementary component to the treatment outcomes, compared to He plasma, although both treatments are conducting to improved adhesion properties of the woven, resulting in better quality of dyed fibers.
Plasma treatment has developed markedly due to its potential environmental and efficient energy use benefits, in developing high-performance fiber- based materials. Taking this into account, we studied the surface modification of synthetic woven
textiles, using atmospheric-pressure plasma,
for controlled adhesion, targeting improved dyeability, since dyeing is compulsory step for most textiles finishing, also aiming to explore the plasma capability to modulate the permeability of fabrics and the relation between the process parameters and the 3D weaving parameters of the fabrics.
The reactor consists of a dielectric barrier discharge (DBD), in asymmetrical electrode arrangement. The treated fabrics are six types of commercial polyester woven, presented as raw materials, with different weaving parameters. Processing is carried out for 30 s. Then, fabric dyeing is performed under industrial conditions, on untreated and plasma-treated samples. Moreover, two different dyeing temperatures are tested. The materials are then analyzed by the usual wettability/wickability measurement, SEM and XPS, also by evaluation of color changes in the CIELAB color space. The influence of the plasma treatment on the mechanisms at the interface between the material and a dye solution is established by a diffusion method. The measurement is carried out with the woven placed between two cells and the absorbance measurement is performed until equilibrium is reached in both cells.
The enhanced adhesion properties of the plasma- treated samples are demonstrated by color analysis, with increased color intensity on plasma-treated samples, compared to untreated ones. Also, the air- plasma has demonstrably more pronounced effect on the color intensity, compared to the He-plasma. The diffusion test is demonstrating the accelerated flow of the dye solution through the textured sample, for air-treated, compared to He-treated samples. The fluid is flowing at higher rate and the saturation of the flow, due to physical obstruction of the woven pores, is visibly limited for air-treated samples. This could suggest that a chemical effect is superposing on the physical cleaning effect of the He-plasma, conducting to better quality of the capillary channels. The plasma effect on loosely weaved structure is more limited, compared to denser structures. Then,
the process
rates were
evaluated, confirming that in case of the He-plasma treatment, the effect would be dominantly the physical one, whereas the strong modification of both rates for air-treated samples would imply that a chemical effect superposes on the physical one.
The results will be further exploited in developing large-scale set-up for air plasma operation, which obviously represents lower cost technological solution.
CASPIA project, Executive Agency for Higher Education Research Development and Innovation, Romania, PN-II-PT-PCCA-2013, grant 254/2014. Topic number: 14 166
XXXIII ICPIG, July 9-14, 2017, Estoril/Lisbon, Portugal Topic number 6 Electric field strength measurement by Stark polarization spectroscopy in diffuse helium-nitrogen barrier discharges S. Nemschokmichal, R. Tschiersch, and J. Meichsner Institute of Physics, University of Greifswald, Felix-Hausdorff-Street 6, 17489 Greifswald, Germany Stark polarization spectroscopy is applied to a diffuse helium-nitrogen barrier discharge to measure the electric field strength. The splitting of the allowed and the forbidden line around 492.2 nm (4 1
1 P ◦ ) as well as the shift of the allowed line are investigated. Both are compared to the electric field strength calculated from the ratio of the singlet lines at 667 nm (3 1 D → 2
1 P ◦ ) and 728 nm (3 1 S → 2
1 P ◦ ). 1. Introduction Discharges in helium with molecular admixtures like nitrogen or oxygen are important for applica- tions at atmospheric pressure because of their ability to produce radicals at low power requirements. For a better understanding of these discharges and to op- timize applications, numerical simulations and their comparison with crucial discharge parameters of the experiment are necessary. One of the most impor- tant discharge parameter is the electric field strength, which can be determined by Stark polarization spec- troscopy [1], and from the intensity ratio of the two singlet lines [2]. The combination of both methods allows a precise absolute calibration by Stark polar- ization spectroscopy, and a good spatial and temporal resolution by the intensity ratio method. 2. Experimental setup The investigated discharge is ignited between to plane electrodes, covered by glass plates at a gap dis- tance of 3 mm. The chamber is filled with a mixture of helium and 500 ppm nitrogen at 1 bar. A square wave voltage with a frequency of 5 kHz and an am- plitude from 0.8 kV to 1.5 kV is applied. Under these conditions, a diffuse glow-like discharge develops. The discharge emission is observed by a system consisting of a monochromator (0.75 m focal length, 1800 mm
−1 grating) and a photomultiplier tube. The photomultiplier signal is amplified and recorded by an oscilloscope, allowing an averaging of up to 50000 signals. For low intensities, as for the Stark splitting line at 492.2 nm, a photon counting procedure is used to improve the signal-to-noise ratio. 3. Results A typcial example of the Stark spectroscopy mea- surement is shown in figure 1 for three distances to the cathodic dielectric. Two characteristics are visi- ble: Firstly, the emission maximum appears later for I di
m A λ nm λ nm λ nm In t a. u. In t a. u. In t a. u. time µs 0 10 20 30 492
492.2 492.4
10 −4 10 −2 10 0 492 492.2
492.4 10 −4 10 −2 10 0 −0.5
0 0.5
1 492
492.2 492.4
10 −4 10 −2 10 0 z = 1.0 mm z = 0.5 mm z = 0.0 mm (a)
(b) (c)
(d) Fig. 1: (a) Discharge current and (b-d) spectrally resolved emission at 492.2 nm for three distances z from the cathodic dielectric. decreasing distance to the cathodic dielectric, which indicates the propagation of the cathode-directed ion- izing front. Secondly, the forbidden line becomes more pronounced. Hence, the electric field strength increases towards the cathode, a cathode fall region forms. The limitations of this method are visible as well. The separation of the forbidden line is weak for low electric fields and a large background emission (probably first positive system of nitrogen) exceeds the forbidden line for later times. Therefore, the shift of the allowed line and the line ratio method are used to calculate the electric field for comparison. References [1] N Cvetanovi´c, M M Martinovi´c, B M Obradovi´c, and M M Kuraica, J. Phys. D: Appl. Phys. 48 (2015) p. 205201. [2] S S Ivkovi´c, G B Sretenovi´c, B M Obradovi´c, N Cvetanovi´c, and M M Kuraica, J. Phys. D: Appl. Phys. 47 (2014) p. 055204. 167
XXXIII ICPIG, July 9-14, 2017, Estoril/Lisbon, Portugal
R. Sannomioya 1 , R. Ichiki 1 , K. Hanada 2 , S. Akamine 1
1
1 P
2
nitriding. Four types of samples were immersed in simulated body fluid and the calcium phosphate formation on the surface was compared. As a result, the growth of calcium phosphate layer formed on the nitrided sample is the fastest among the samples.
These results revealed that biocompatibility of Ti alloy nitrided by atmospheric-pressure plasma was improved.
In recent years, new surface treatment methods have been developed in order to improve biological characteristics of biocompatible metals such as Ti alloy used in the medical field. Several studies have reported that TiN coating and nitriding of Ti alloy improved biocompatibility. For example, Lin et al. proposed that TiN layer can inhibit adhesive property of mutans streptococcus [1]. Moreover, Zhao et al. indicated that TiN layer improves adhesive property of osteoblast cells which synthesize bone [2]. In this study,
compatibility of Ti alloy nitride by pulsed-arc (PA) atmospheric pressure plasma jet. [3]
The sample is Ti-6Al-4V (15×15×4 mm). The experimental system uses PA plasma jet. An external heater surrounds the quartz pipe to control the treatment temperature (1000℃) so that the samples is uniformly heated. The operating gas is N 2 /H
gas mixture at the flow ratio of 99:1. Low- frequency voltage pulses (5 kV, 1.2 A, 21 kHz) are applied to the internal electrode, and the external electrode is grounded. This nitriding method is spraying jet plume onto the sample. 2.2. Immersion test To evaluate the formation ability of calcium phosphate in vitro, samples were immersed in simulated body fluid (Hanks’ solution) at 37℃ for 10 days. In order to prove that nitrided sample have good biocompatibility, calcium phosphate formative ability of four types of samples (control, nitrided, high hydrophilicity, high surface roughness) are compared. In addition, samples are masked to determine formed layer, and thickness of film is measured by laser microscope.
After atmospheric-pressure plasma nitriding, the surface turned to the golden color, corresponding to TiN. Calcium phosphate formed on surface was proved by EDX analysis. Fig. 1 shows comparison of the four types of samples. The growth of calcium phosphate layer of nitrided sample is the fastest among the four samples. In addition, it is revealed that adhesion force of nitrided sample between calcium phosphate layer and substrate is improved.
These results implied that atmospheric-pressure plasma nitriding has a high potential to improve the affinity of Ti alloy for osteoblast cells. This work was supported by JSPS KAKENHI Grant Number 15K17482.
[1] N. Lin et al., Appl. Surf. Sci. 258, (2012) 7047. [2] Y. Zhao et al., ACS Appl. Mater. Interfaces 5, (2013)1510. [3] Y. Yoshimitsu et al., Jpn. J. Appl. Phys. 54, (2015) 030302. Fig. 1 Thickness of formed calcium phosphate. 14
168 XXXIII ICPIG, July 9-14, 2017, Estoril/Lisbon, Portugal
Investigation on local formation of expanded austenite phase by atmospheric-pressure plasma jet
A. Maeda 1 , R. Ichiki 1 , R. Tomizuka 1 ,
H. Nishiguchi 2 , T. Onomoto 3
S. Akamine 1 , S. Kanazawa 1
1 Faculty of Engineering, Oita University, Oita, Japan 2 Research Promotion Institute, Oita University, Oita, Japan 3 Fukuoka Industrial Technology Center, Kitakyushu, Japan
We succeeded in forming expanded austenite phase (S phase) of stainless steel locally by atmospheric-pressure
pulsed-arc plasma jet using N 2 /H 2 . We confirmed the formation of S phase from metallographic structure and XRD patterns. We found that surface hardness increases. This indicates that reduction of passivation film on stainless steel by hydrogen is successful.
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