Biomedical Alloys and Physical Surface Modifications: A Mini-Review

Biomedical alloys are essential parts of modern biomedical applications. However, they cannot satisfy the increasing requirements for large-scale production owing to the degradation of metals. Physical surface modification could be an effective way to enhance their biofunctionality. The main goal of this review is to emphasize the importance of the physical surface modification of biomedical alloys. In this review, we compare the properties of several common biomedical alloys, including stainless steel, Co–Cr, and Ti alloys. Then, we introduce the principle and applications of some popular physical surface modifications, such as thermal spraying, glow discharge plasma, ion implantation, ultrasonic nanocrystal surface modification, and physical vapor deposition. The importance of physical surface modifications in improving the biofunctionality of biomedical alloys is revealed. Future studies could focus on the development of novel coating materials and the integration of various approaches.

Deposition of fluoropolymer coating on stainless steel surface from plasma of glow discharge

The present work investigates the application of the plasma of glow discharge to deposit the fluoropolymer coatings. Two series of experiments were carried out in which the influence of pressure and current strength on surface coatings morphology during its surface treatment with glow discharge plasma was investigated. The surface morphology is investigated by a scanning electron microscope (SEM), and the water contact angle (WCA) is measured. The fact that the choice of pressure significantly affects the morphology and properties of the deposited coating is established.

Plasma-enhanced thermal growth of copper oxide nanostructures on anode of glow discharge setup

Plasma-enhanced growth of copper oxide nanostructures is widely explored in science and manufacturing, since it provides the flexibility, productivity, and cost-effectiveness necessary to meet the growing demands of customers. However, in the field of growth of metal oxide nanostructures, thermal methods still prevail in plasma methods in spite of long production time up to ten hours. Radiofrequency and microwave plasma sources were applied to grow CuO nanostructures, which are of high interest in various branches of industry, and allowed obtaining a large variety of the nanostructures, and nanowires in particular. At that, high price of the equipment limits the implementation of the results and urges to find cheaper plasma-enhanced method of growth. For this purpose, a common glow discharge plasma setup was engaged to grow the nanostructures in an oxygen atmosphere on surfaces of samples installed on the anode of the electric circuit designed to sustain the glow discharge. An additional heater was mounted under the anode. The proposed combination allowed conducting the growth process under conditions of the delivery of the necessary heat flux and removal the excessive ion flux that can destroy the growing nanostructures because of sputtering. In the first set of experiments, the additional heater was not used, and the observed nanostructures were presented by grains (2D) of about 370 nm in diameter and 80 nm in thickness. This structure is supposedly formed because of action of the internal stresses in the oxide layer. After turning on the heater, the nanowires (1D) were the only nanostructures observed in the experiment, and since no nanowires were found in a case of heating the anode without plasma ignition, one can consider the plasma as a factor determining the nanowire growth.

Towards High Efficiency CO2 Utilization by Glow Discharge Plasma

Plasma technology reaches rapidly increasing efficiency in catalytic applications. One such application is the splitting reaction of CO2 to oxygen and carbon monoxide. This reaction could be a cornerstone of power-to-X processes that utilize electricity to produce value-added compounds such as chemicals and fuels. However, it poses problems in practice due to its highly endothermal nature and challenging selectivity. In this communication a glow discharge plasma reactor is presented that achieves high energy efficiency in the CO2 splitting reaction. To achieve this, a magnetic field is used to increase the discharge volume. Combined with laminar gas flow, this leads to even energy distribution in the working gas. Thus, the reactor achieves very high energy efficiency of up to 45% while also reaching high CO2 conversion efficiency. These results are briefly explained and then compared to other plasma technologies. Lastly, cutting edge energy efficiencies of competing technologies such as CO2 electrolysis are discussed in comparison.

Carbon nanostructure growth: new application of magnetron discharge

Purpose: The application of a common magnetron discharge to the growth of carbon nanostructures is studied. The simplicity of the proposed technique can be beneficial for the development of new plasma reactors for large-scale production of carbon nanostructures. Design/methodology/approach: Graphite cathode was treated by carbon-containing powder accelerated by use of nozzle, and then aged in hydrogen. Superposition of glow and arc discharges was obtained, when putting the cathode under the negative biasing with respect to the walls of a vacuum chamber. The pulsed discharge was preserved through the whole time of treatment. This process was explained in terms of interaction of glow discharge plasma with a surface of the cathode made of non-melting material. Findings: The plasma treatment resulted in generation of the diverse nanostructures confirmed by SEM and TEM images. Spruce-like nanostructures and nanofibers are observed near the cathode edge where the plasma was less dense; a grass-like structure was grown in the area of “race-track”; net-like nanostructures are found among the nanofibers. These findings allow concluding about the possible implementation of the proposed method in industry. Research limitations/implications: The main limitation is conditioned by an explosive nature of nanostructure generation in arcs; thus, more elaborate design of the setup should be developed in order to collect the nanospecies in the following study. Practical implications: High-productivity plasma process of nanosynthesis was confirmed in this research. It can be used for possible manufacturing of field emitters, gas sensors, and supercapacitors. Originality/value: Synthesis of carbon nanostructures is conducted by use of a simple and well-known technique of magnetron sputtering deposition where a preliminary surface treatment is added to expand the production yield and diversity of the obtained nanostructures.