Atmospheric pressure non-equilibrium (cold) plasma jet technology received enormous attention in surface processing of materials in the last two decades, and still continues nowadays to attract growing interest. In addition to the advantages of the atmospheric pressure operation such as the potential cost reduction of apparatuses as well as their easier handling and maintenance, due to the distinctive remote operation, plasma jets give the unique possibility of placing the substrate outside the source boundaries. Consequently, the processing of complex three-dimensional objects and the integration into existing production lines are expected to be much easier. However, while appealing, plasma jet technology has the drawback that great efforts are required for process optimization, since many factors can affect, for instance, the physical and chemical proprieties of the so-called “plasma plume” emanating from the devices and propagating in open space towards the substrate to be treated. The aim of this paper is to provide a critical literature review on the utilization of atmospheric pressure non-equilibrium plasma jets in surface processing of materials. Starting from the description and classification of the multitude of devices used in this applicative field so far, the attention will be drawn on some very important aspects to be taken into account in process optimization. The discussion will be focused on basic concepts and peculiarities closely related to the remote operation of the plasma sources, which include the characteristics and dynamics of the plasma plume interacting with the substrate and the surrounding atmosphere. Since the plasma jet approach allows the surface modification of small localized regions of the sample, the strategies implemented to enlarge the treated area will be also addressed. Finally, a brief overview will be given of the available applications and recent developments in the field of etching, thin film deposition and treatment.

Atmospheric pressure non-equilibrium plasma jet technology: general features, specificities and applications in surface processing of materials

Solid lubricants are described as solid materials of intentionally introduced or in situ formed on contact surfaces in relative motion for the purpose of lowering friction and wear and providing protection from damage. Solid lubricants and advanced self-lubricating materials are widely used in modern industries, especially in aerospace, aviation, automotive, metallurgy, materials forming, and machining industries, and have attracted great interest in lubrication applications under very severe circumstances such as elevated temperatures, heavy loads, ultrahigh vacuum, extreme radiation, strong oxidation, and chemical reactivity environments. Many efforts have been made to develop self-lubricating composites by a variety of material preparation techniques, which include powder metallurgy, physical/chemical vapor depositions, thermal spraying, electrodeposition, laser cladding, and additive manufacturing. Although several reviews on the development of high-temperature solid lubricants have been published, most of them only focus on a type of material, a specific process, or application. In this paper, a comprehensive review is provided to present the state-of-the-art progress in solid lubricants, self-lubricating composites/coatings, and their effective functions that can be used over a wide variety of environmental conditions, especially at elevated temperatures. The solid lubricants considered include representative soft metals, layered structure materials (e.g., graphite, hexagonal boron nitride, transition metallic dichalcogenides, MAX phase), chemically stable fluorides, binary or ternary metallic oxides, especially alkaline earth chromates, and sulfates, and synergistic effects from these solid lubricants. This paper also provides new insights into design considerations of environmental adaptive solid lubrication, and the challenges and potential breakthroughs are further highlighted for high-temperature solid lubrication applications.

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High-Temperature Solid Lubricants and Self-Lubricating Composites: A Critical Review

A modified calorimetric probe for the investigation of a commercial atmospheric pressure plasma jet is presented. The design of the probe is adapted to the conditions provided by the plasma jet, in particular the high energy density and gas flow rates. The results of a parametric study are shown to prove the functionality of the newly designed probe and to characterize the plasma jet. Typical values of the energy influx during operation have been determined to 200–350 W/cm $^{\vphantom {R^{a^{.}}}2}$ at a distance of 4–6 mm from the plasma jet. Moreover, the radial profile exhibits a high symmetry.

Investigation of a Commercial Atmospheric Pressure Plasma Jet by a Newly Designed Calorimetric Probe

Investigation on Carbon Nanotubes as Thermal Interface Material Bonded With Liquid Metal Alloy

Various types of alloys and polymers are utilized in orthopedic implants. However, there are still several issues accompanied by the use of prosthetic materials, such as low wear performance and catastrophic failure. Surface enhancement of biomaterials is a promising method that can improve the success rate of prosthetic operations without negatively affecting their bulk properties while improving the biocompatibility of implants and reducing infections. Nonthermal plasma treatment has become a ubiquitous surface modification method in sterilization and healthcare applications. However, the clinical applications of such an approach have been limited due to the lack of detailed studies delineating the wear behavior and biocompatibility of implants after plasma treatment. In this study, we have employed a handheld piezoelectric direct discharge (PDD) plasma generator to modify the surface of two common metallic (Ti6Al4V) and nonmetallic (GUR1020 polymer) biomaterials used typically in joint and disc replace...

Improvement of Tribological and Biocompatibility Properties of Orthopedic Materials Using Piezoelectric Direct Discharge Plasma Surface Modification.

The pre-treatment of copper by an atmospheric pressure plasma jet system with different gas mixtures was studied. Their influence on the protection properties of plasma polymer coatings against corrosive environments were examined via an electrochemical test for the visualization of defects in the plasma polymer coating. The defect density could be significantly reduced by the pre-treatment with nitrogen-hydrogen plasma. Time between pre-treatment and coating process is of important influence on the defect density as our investigation shows. The coating properties were compared with a typical protective paint system used today for electric boards.

Corrosion protection of copper surfaces by an atmospheric pressure plasma jet treatment

In-situ synthesis of graphene-like carbon encapsulated copper particles for reinforcing copper matrix composites

Surface modification on copper particles toward graphene reinforced copper matrix composites for electrical engineering application

Atmospheric Pressure Plasma Jets for Surface Activation Prior to Bonding and Painting

The surface pre-treatment of a high performance thermoplastic CFRP for improved paint adhesion was investigated with a 30 W KrF UV-excimer laser (248 nm). Surface analysis showed no fiber release or visible removal of the thermoplastic matrix but an effective removal of silicon organic release agent residues. The ablation on nanoscale led to a cleaning effect, which improved the paint adhesion. Paint adhesion tests with a solvent-reduced paint system showed good results even after long-term ageing in water or under warm and humid conditions. After UV-laser treatment the adhesion of industrial polysulfide sealants could be achieved even without adhesion promoter. Large scale application concepts based on a compact UV-excimer laser system showed high potential for robotic guided applications with high treatment rates.

https://doi.org/10.2961/jlmn.2023.01.2004

Joerg Ihde

Papers

Corrosion protection of copper surfaces by an atmospheric pressure plasma jet treatment

In-situ synthesis of graphene-like carbon encapsulated copper particles for reinforcing copper matrix composites

Surface modification on copper particles toward graphene reinforced copper matrix composites for electrical engineering application

Atmospheric Pressure Plasma Jets for Surface Activation Prior to Bonding and Painting

UV-Laser Treatment of Thermoplastic CFRP Parts for Paint Applications