Papers by Keyword: Atmospheric Pressure Plasma Jet

Abstract: The surface condition of carbon fibre reinforced plastic (CFRP) substrates is decisive to obtain high bond strength and lifetime of adhesively bonded parts. Those surfaces were adjusted in terms of their microscopic topography by means of peel plies and release foils. The subsequent surface treatment via atmospheric pressure plasma jet or vacuum blasting allowed the modification of the microscopic roughness as well as the surface chemistry. Those configuration were assessed using surface analytic methods as well as quasi-static and cyclic fracture tests on single lap shear specimens. The microscopic surface roughness, if at all, only showed a small influence on the bond strength. Despite release agent residues, fracture was found within the fiber-matrix interface, which caused difficulties in evaluating the effect of surface pretreatments on the adhesion strength. Fatigue tests revealed a lifetime reduction of uneven microscopic rough surfaces, which was assigned to stress concentrations at the tip of asperities. The crack propagation was accelerated in case of release agent residues. If surfaces were free of contaminations, no differences between microscopically smooth and slightly structured surfaces were found. Overall, fatigue testing on single lap shear specimens showed an increased sensitivity with regard to the assessment of surface morphology.

Abstract: The aim of this study was to evaluate the effect of argon plasma jet, generated at atmospheric pressure, on Aspergillus sp. The molds were isolated from commercial white bread and inoculated on potato dextrose agar (PDA) containing 10% tartaric acid. The atmospheric pressure plasma jet (APPJ) was generated at a high frequency (43 kHz) power of 10, 20, or 30W and applied to the inoculated molds on PDA for 5, 10, or 20 minutes. The PDA plates were incubated for 3 and 6 days and the fungal inactivation was investigated directly under light microscope and indirectly by comparing the fungal dry weights. The results indicated that higher power supply and longer plasma exposure time led to more reduction in the fungal dry weight. The APPJ appears to be effective in destroying Aspergillus sp., yet the optimal plasma treatment condition remains to be optimized.

Abstract: The Atmospheric Pressure Plasma Jet (APPJ) is an innovative technology in advanced optics manufacturing; it is a non-contact precision machining method based on the chemical reaction between a reactive neutral radical generated by the plasma and substrate surface atoms for atom-scale material removal. The APPJ involves a complicated process; therefore, the controllability of the technical process was investigated to describe the accuracy of machining efficiency that is the uniformity and repeatability for machining systems, the linearity relation between the removal rates and dwell time. Moreover, the experimental result of the fused quartz removal function variation trend with different processing parameters was discussed. The results of experimentation indicate that the APPJ method has good repeatability within a short dwell time, the removal depth increases with the dwell time and a linearity relation seems appropriate, and the radio frequency (RF) power and the flux of assistant gas oxygen have a great influence on removal efficiency. However, the removal rate remains stable under small perturbation of flux of plasma gas He and reactive gas SF₆. And the surface roughness is improved from Ra 9.3nm to Ra 3.7nm.

Abstract: The influence of He/O2 atmospheric pressure plasma jet (APPJ) treatment on subsequent wet desizing of polyarylate from PET fabrics was studied in present paper. Scanning electron microscopy (SEM) analysis showed an increased surface roughness after the plasma treatment. And SEM results also showed that the fiber surfaces were as clean as unsized fibers surfaces after 35s treatment followed by NaHCO3 desizing. X-ray photoelectron spectroscopy (XPS) analysis indicated that oxygen-based functional groups increased for the plasma treated polyacrylate sized fabrics. The percent desizing ratio (PDR) results showed that more than 99% PDR was achieved after 65s plasma treatment followed by a 5min NaHCO3 desizing.

Abstract: The influence of He/O2 atmospheric pressure plasma jet (APPJ) treatment on subsequent wet desizing of polyarylate on PET fabrics was studied in present paper. Atomic force microscopy (AFM) and Scanning electron microscopy (SEM) showed an increased surface roughness after the plasma treatment. SEM also showed that the fiber surfaces were as clean as unsized fibers after 35 s treatment followed by NaHCO3 desizing. X-ray photoelectron spectroscopy (XPS) analysis indicated that oxygen-based functional groups increased for the plasma treated polyacrylate sized fabrics. Compared to conventional wet desizing, plasma treatment could significantly reduce desizing time.

Abstract: The objective of this study was to investigate the uniformity and penetration of surface modification into textile materials including fiber, yarn and fabric treated by atmospheric pressure plasma jet (APPJ). Exposure to helium/oxygen plasma at atmospheric pressure made improvement in the wettability, dyeability, adhesion of single fiber, yarn and woven fabric. The results showed that such a plasma jet was possible and effective in penetration of surface modification into textile structure. It can treat the whole surfaces of a single fiber, yarn filament in the treated parallel filament tow uniformly. For porous fabrics, rapid and efficient treatment on both sides of the treated samples was found to be ensured. And the degree and depth of penetration depended on the penetration of active species in plasma jet, which was affected by plasma parameters and materials structure. The former included treatment time, power, gas temperature, jet-to-substrate distance. The latter included number of twisting and fabric pore size. These findings would have important effects on industrialization of textiles treated by atmospheric pressure plasma jet.

Abstract: A convenient method for direct and large-area growth of one-dimensional (1-D) CuO and ZnO nanostructures on a conductive brass substrate has been developed. The ZnO and CuO nanostructures have been simultaneously induced and growth on a brass (70Cu-30Zn alloy) substrate by using an atmospheric-pressure plasma jet (APPJ) with pure oxygen as the reaction gas in an ambient environment. Various one-dimensional (1-D) nanostructures such as nano-particles, nanowires, nanobelts, nanocombs, and nanosheets have been in situ grown on the brass substrates under different plasma treatment times. The plasma power of 150W and scanning speed of sample stage 1 mm/sec with different treating times were used in plasma surface treatment processing. The nano-scaled ZnO and CuO formation and its structure were characterized by means of grazing-incidence X-ray diffraction, Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS). The results showed that the nano-scaled CuO and ZnO growth process was as follows: nano-particles, nano-crystal clusters then nano-crystal columns with increasing plasma treatment times. The growth of nano-scaled oxide formed in sequence that CuO was first grew on the brass substrate then ZnO. The morphologies of nano-scaled ZnO resembled bulbs and long-legged tetrapods. However, the morphologies of nano-scaled CuO were likely bulbs and flake nanostructures. This approach could prepare CuO and ZnO nanostructures on a brass substrate without size limitations. The possible growth mechanisms and structure of nano-scaled CuO and ZnO are discussed in this paper. The simplicity of the preparation procedure and the potential technological of the product were be interested in this study.

Abstract: A novel atmospheric pressure plasma jet with a cylindrical symmetry i.e. a tubular dielectric barrier and two tubular electrodes was developed at Microstructure Research Center – fmt, Wuppertal, Germany. The jet was investigated by means of ultra fast (down to tens of nanoseconds exposition time) ICCD photography and regular CCD photography. Some spectacular results were achieved and their partial explanation was presented. The jet acts as a “plasma gun” throwing small “plasma bullets” out of its orifice. The most important findings are: (i) the bullet velocity is approximately 3 orders of magnitude larger than the gas flow velocity, and (ii) the jet dynamics is mainly electrical field controlled. A simple model - formation of a jet in air - based on a Helium metastables core can explain qualitatively reasonably well most of our experimental observations. Some variations of the original cylindrical jet geometry were presented and discussed: microjet and fmt Plasma-Pen, single tube multijet, tube-in-tube single and multijet systems (so-called “Wuppertal-Approach”).