Atmospheric Plasma
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2021 ◽  
Author(s):  
Jiabin Xu ◽  
Xiaoshuang Rao ◽  
Xiaoyu Xu ◽  
Kechong Wang ◽  
Bao Guo ◽  
...  

Abstract RB-SiC ceramic is one of the most important and useful material as optical precision elements in many scientific research fields. In this paper, a novel cold atmospheric plasma (CAP), which is based on the precision grinding process in surface technology to modify at room temperature (RT) for grinding with a combination of plasma oxidation surface modification is proposed. To identify the performance of the proposed cold atmospheric plasma (CAP) method on the surface modification of RB-SiC ceramic, precision grinding test was conducted. To reveal the fundamental issue in the grinding of RB-SiC ceramic, numerical calculation and model analysis were conducted to investigate the effect of the composite process on grinding forces and the mechanism of subsurface material removal in the presence of plasma oxidation. As a result of the method included the kept constant during the precision grinding of the composite process self-adaption-grinding process to avoid the deviation caused by second grinding particle entry. As a summary, we provides a significant cold atmospheric plasma-precision grinding compound process toward the establishment of the basic theory by analyzing the mechanism of the simulated design and computation. The process and technical difficulties of RB-SiC ceramic and mechanism of subsurface material removal during precision grinding were be solved.


Materials ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 7322
Author(s):  
Corneliu Munteanu ◽  
Viorel Paleu ◽  
Bogdan Istrate ◽  
Anişoara Dascălu ◽  
Cornelia Cîrlan Paleu ◽  
...  

Cardan joints are used in transmissions between misaligned shafts, as in all-wheel-drive (AWD) cars and railway applications. Their functioning is accompanied by heavy cyclical loads, with the cardan cross spindles subjected to intensive abrasive wear and pitting. In this paper, a solution to the mentioned issue is proposed, thin anti-wear coatings of Metco 32 and Metco 72 metallic powders deposited by atmospheric plasma spray (APS) on cylindrical samples cut from spindles of two cardan crosses made of 40Cr10 and RUL2 steel. The morphological analysis of the coated surfaces was realized by scanning electron microscopy (SEM), and the elemental composition of the tested samples was elaborated by energy-dispersive X-ray spectroscopy (EDS). To investigate the wear resistance of the coated samples in dry and grease-lubricated conditions, tests at constant load and constant speed were carried out using an AMSLER tribometer. The results of greased tests proved that the expulsion of the lubricant from the tribological contact occurred no matter the combination of coated or uncoated samples. During grease-lubricated tests of ten minutes, the least coefficient of friction was measured for uncoated specimens with better surface finishing; but in dry friction tests, the lowest values of the mean friction coefficients were obtained for the Metco 72 coatings. The porous coatings may act as lubricant reservoirs in long-lasting tests, providing a solution to the expulsion phenomenon of the lubricant to the boundary outside the area of the larger-diameter roller.


Coatings ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1477
Author(s):  
Zining Yang ◽  
Weize Wang ◽  
Shujuan Deng ◽  
Huanjie Fang ◽  
Ting Yang ◽  
...  

Gadolinium zirconate with excellent high-temperature phase stability and sintering resistance has become a very promising candidate material for a new generation of thermal barrier coatings (TBCs). However, the low fracture toughness of gadolinium zirconate greatly limits its application. In this study, gadolinium zirconate (GZ) and two kinds of toughened gadolinium zirconate (GZ/YSZ prepared by mixed powder of Gd2Zr2O7 and YSZ and GSZC prepared by (Gd0.925Sc0.075)2(Zr0.7Ce0.3)2O7 powder) double-layered TBCs were prepared by atmospheric plasma spraying (APS). The fracture toughness of the GZ/YSZ coating and GSZC coating were 9 times and 3.5 times that of GZ coating, respectively. The results of thermal shock test showed that the three TBCs exhibit different failure mechanisms. During the thermal shock test, cracking occurred at the interfaces between the YSZ layer and the BC or GZ/YSZ layer, while GSZC TBC failed due to premature cracking inside the GSZC layer. The particle erosion rate of the GZ, GZ/YSZ, and GZSC coatings were 1.81, 0.48, and 1.01 mg/g, respectively, indicating that the erosion resistance of coatings is related to their fracture toughness. Furthermore, the superior erosion resistance of the GZ/YSZ and GSZC coatings can be attributed to the conversion of crack propagation path during the erosion test.


Author(s):  
Maximilian Grimm ◽  
Susan Conze ◽  
Lutz-Michael Berger ◽  
Rico Drehmann ◽  
Thomas Lampke

AbstractCoatings prepared from chromia-rich (Al,Cr)2O3 solid solution (ss) feedstock powders are intended to improve the properties of Cr2O3 coatings, but are rarely studied so far. In this work, the processability of a commercial (Al,Cr)2O3 solid solution (ss) powder containing 78 wt.% Cr2O3 by atmospheric plasma spraying (APS), the corresponding coating microstructures and properties were investigated. Possible further improvements were expected by blending with 2, 23 and 54 wt.% TiOx powder. For comparison, plain Cr2O3 and TiOx coatings were studied as well. The microstructures were analyzed using SEM, EDS and XRD measurements. Hardness (HV0.3) was measured, as well as the dry unidirectional sliding wear resistance and the abrasion wear resistance (ASTM G65). Moreover, the corrosion and electrical insulating properties were measured. The (Al,Cr)2O3 ss showed only a small change of the composition, and the formation of γ-Al2O3, as found for alumina-rich (Al,Cr)2O3 ss powders, was avoided. Compared to the plain chromia coating, some improvements of the processability and coating properties for the ss (Al,Cr)2O3 coating were found. The most balanced coating performance was achieved by blending the ss (Al,Cr)2O3 with 2 wt.% TiOx, as this coating showed both a high sliding and abrasion wear resistance, in combination with a high corrosion resistance.


2021 ◽  
Vol 11 (23) ◽  
pp. 11181
Author(s):  
Sigrid Karrer ◽  
Mark Berneburg ◽  
Florian Zeman ◽  
Michael Koller ◽  
Karolina Müller

The increase in antibiotic resistance requires effective non-antibiotic therapies for acne. Cold atmospheric plasma (CAP) inactivates bacteria and improves wound healing, but its effect on acne has not been investigated. The objective of this controlled split-face study was to assess safety and efficacy of CAP in moderate acne. One side of the face received 8–10 treatments with cold helium plasma within 4–6 weeks; follow-up was two and four weeks thereafter. Acne lesions were counted, followed by global acne severity ratings. Of the 34 patients included, 29 completed the study. No serious adverse events occurred. The two facial sides did not significantly differ in the number of inflammatory and non-inflammatory lesions. An interaction effect of number and type of treatment was found for inflammatory lesions. Lesion reduction after 10 treatments was significantly higher on the treated than on the untreated side. Percentage of patients reporting improved aesthetics was higher for the treated than for the untreated side after treatment completion (79% vs. 45%) and at the two- (72% vs. 45%) and four-week follow-up (79% vs. 52%). In conclusion, CAP was safe with excellent tolerability, showed moderate reduction in acne lesions and led to higher patient-based ratings of aesthetics than non-treatment.


2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Zahra Yazdani ◽  
Pooyan Mehrabanjoubani ◽  
Alireza Rafiei ◽  
Pourya Biparva ◽  
Mostafa Kardan

Curcumin (CUR) has interesting properties to cure cancer. Cold atmospheric plasma (CAP) is also an emerging biomedical technique that has great potential for cancer treatment. Therefore, the combined effect of CAP and CUR on inducing cytotoxicity and apoptosis of melanoma cancer cells might be promising. Here, we investigated the combined effects of CAP and CUR on cytotoxicity and apoptosis in B16-F10 melanoma cancer cells compared to L929 normal cells using MTT method, acridine orange/ethidium bromide fluorescence microscopic assay, and Annexin V/PI flow cytometry. In addition, the activation of apoptosis pathways was evaluated using BCL2, BAX, and Caspase-3 (CASP3) gene expression and ratio of BAX to BCL2 (BAX/BCL2). Finally, in silico study was performed to suggest the molecular mechanism of this combination therapy on melanoma cancer. Results showed that although combination therapy with CUR and CAP has cytotoxic and apoptotic effects on cancer cells, it did not improve apoptosis rate in melanoma B16-F10 cancer cells compared to monotherapy with CAP or CUR. In addition, evaluation of gene expression in cancer cell line confirmed that CUR and CAP concomitant treatment did not enhance the expression of apoptotic genes. In silico analysis of docked model suggested that CUR blocks aquaporin- (AQP-) 1 channel and prevents penetration of CAP-induced ROS into the cells. In conclusion, combination therapy with CAP and CUR does not improve the anticancer effect of each alone.


Biomedicines ◽  
2021 ◽  
Vol 9 (11) ◽  
pp. 1700
Author(s):  
Sungryeal Kim ◽  
Chul-Ho Kim

Much progress has been made since plasma was discovered in the early 1900s. The first form of plasma was thermal type, which was limited for medical use due to potential thermal damage on living cells. In the late 1900s, with the development of a nonthermal atmospheric plasma called cold plasma, profound clinical research began and ‘plasma medicine’ became a new area in the academic field. Plasma began to be used mainly for environmental problems, such as water purification and wastewater treatment, and subsequent research on plasma and liquid interaction led to the birth of ‘plasma-activated liquid’ (PAL). PAL is currently used in the fields of environment, food, agriculture, nanoparticle synthesis, analytical chemistry, and sterilization. In the medical field, PAL usage can be expanded for accessing places where direct application of plasma is difficult. In this review, recent studies with PAL will be introduced to inform researchers of the application plan and possibility of PAL in the medical field.


2021 ◽  
Vol 122 ◽  
pp. 111759
Author(s):  
Se-Hoon Choi ◽  
Jin-Ah Kim ◽  
Sang-Yeon Lee ◽  
Kuck-Jin Hwang ◽  
Se-Yeong Park ◽  
...  

2022 ◽  
Vol 141 ◽  
pp. 107411
Author(s):  
Q. Dong ◽  
J. Tan ◽  
R. Huang ◽  
H.L. Wang ◽  
P. Song ◽  
...  

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