Andreas A. Polycarpou

Andreas A. Polycarpou
Texas A&M University | TAMU · Department of Mechanical Engineering

PhD

About

342
Publications
98,440
Reads
How we measure 'reads'
A 'read' is counted each time someone views a publication summary (such as the title, abstract, and list of authors), clicks on a figure, or views or downloads the full-text. Learn more
6,211
Citations
Citations since 2016
113 Research Items
3417 Citations
20162017201820192020202120220100200300400500600
20162017201820192020202120220100200300400500600
20162017201820192020202120220100200300400500600
20162017201820192020202120220100200300400500600
Introduction

Publications

Publications (342)
Article
The introduction of structural energy storage devices into emerging markets, such as electric vehicles, is predominately hindered by weak energy density, safety concerns, and immaturity of the field in materials. Herein, fabrication and testing of a freeze-resistant, multifunctional quasi-solid-state zinc-sulfur battery (ZnS) are reported. To this...
Data
A high-performance aromatic thermosetting copolyester containing multi-walled carbon nanotubes (ATSP-MWNTs) was synthesized, characterized, and tribologically tested against cobalt-chromium-molybdenum (CoCrMo) alloy) as a potential replacement for ultra-high molecular weight polyethylene (UHMWPE) in artificial joints. By investigating the tribologi...
Article
Full-text available
A high-performance aromatic thermosetting copolyester containing multi-walled carbon nanotubes (ATSP-MWNTs) was synthesized, characterized, and tribologically tested against cobalt-chromium-molybdenum (CoCrMo) alloy) as a potential replacement for ultra-high molecular weight polyethylene (UHMWPE) in artificial joints. By investigating the tribologi...
Article
Multilayer coatings of Ni and Cr were deposited onto Inconel 617, and multi-scale physical properties were characterized using high temperature tribological experiments, nanoindentation, and microscratch. The effect of high temperature aging (950 °C under helium environment) on two different Ni/Cr multilayer coatings with individual layer thickness...
Article
Mechanical testing of seals, bearing materials, and mechanisms in cryogenic environments is a rapidly growing field of research, as it promises improvements in equipment performance and reliability for applications such as space exploration, liquid hydrocarbon storage, and superconducting devices. Cooling of test equipment is usually performed with...
Article
Osteoarthritis disorder ranks amongst the most common disabling chronic diseases in young and older adults worldwide. It is linked to degenerative joint diseases and frequently occurs with pain in the knee, hand, hip, and feet. This progression breaks down the cartilage and underlying bones over time and causes motion disability. Artificial bone im...
Article
Abrasive wear of polyether ether ketone (PEEK) and aromatic thermosetting co-polyester (ATSP) based polymer composite coatings were examined with lunar regolith simulant environment by conducting pin-on-disk experiments under dry sliding conditions, contact pressure of 17.5 MPa, and sliding speed of 0.25 m/s. Three different tribo-interfaces, namel...
Article
Full-text available
Aqueous lubricants are gaining attention due to significant advantages such as being environmentally friendly, tunable, and thermally stable. The oil and gas industry can use such additives to utilize in water-based fluids for applications where small sliding velocities and large lateral forces require enhanced lubrication. This investigation aims...
Article
Nickel-based superalloys with superior thermochemical, mechanical, and tribological properties are highly utilized for critical components in several high temperature applications such as gas turbines and nuclear reactors. Inconel 617, in particular, is considered as one of the main candidate superalloys for tribo-components in very-high-temperatur...
Article
Mechanical components in future missions to Venus will encounter high pressure (HP) and high temperature (HT) CO2 harsh conditions. Herein, the surface of Inconel 718 (INC 718), a HT nickel-based alloy was modified by applying advanced coatings by different deposition techniques. Three commercial coatings, namely Nedox PF-F™ (nickel-phosphorous all...
Article
Full-text available
High-performance polymers (HPPs) are increasingly used in different industrial machinery components, particularly for rubbing parts that demand reliable and durable operation at extreme sliding conditions such as elevated temperature environments, where the use of conventional lubricants is not feasible. The current study investigates the role of e...
Article
Structural energy storage devices offer both electrochemical and mechanical performance in a single multifunctional platform, making them promising for weight- and/or volume-restricted applications, such as electric vehicles, aircraft, and satellites. However, the development of state-of-the-art multifunctional energy storage is predominately hinde...
Article
Zinc ion hybrid supercapacitors (ZIHSCs) with promising energy and power densities are a great answer to the ever-growing demand for energy storage devices. The restricted lifespan due to the dendrite formation on metallic Zn is one of the main roadblocks. Herein, we investigate the electrochemical capability of oxygen-enriched porous carbon nanofi...
Article
Inconel 617 superalloy is a main candidate to be used for mechanical and tribo-components in high temperature helium-cooled reactors. Recent findings show that it grows a unique surface oxide, especially under high temperature helium with distinct wear, friction, and contact properties. This study reports the elevated temperature nanoscratch behavi...
Article
Graphene oxide (GO), silk fibroin (SF), and cellulose nanocrystal (CNC) nanocomposite is a novel biomaterial with superior mechanical properties. Elevated temperature nanoindentation experiments using constant load hold method are performed to investigate temperature-dependent mechanical and creep behavior of the GO–SF–CNC nanocomposite. Hardness a...
Article
The current study investigates the thermally grown oxide layers (of the order of 5–10 μm thick) on Inconel 617 at elevated temperature of 950 °C in helium and air atmospheres using nanoindentation and nanoscratch techniques. Nanoindentation is also used to calculate the fracture toughness of the oxides using the crack initiation method. The oxide g...
Article
Full-text available
Perfluoropolyether (PFPE) polymer lubricant performs an important role in protecting both the writing/reading elements in the recording head and the disk of magnetic storage devices from mechanical wear or damage, induced by direct contact. Under high-speed sliding, the nanometer thick lubricant shows complex behavior, such as shear thinning, slipp...
Article
Full-text available
A high temperature mechanical and tribological study was performed to investigate the dependence of friction, wear and mechanical properties of ultra-thin nitrogen-doped diamond-like carbon (NDLC) films on their sp²/sp³ carbon configurations. Two NDLC films with the same thickness of 3 nm, almost the same nitrogen content, and different sp²/sp³ car...
Article
In coiled tubing applications, common constraints e.g., high friction, lateral drag and restricted flow rate increase the demand for friction modifiers. These modifiers also face the inevitable intrusion of abrasive particles in the wellbore that impair the drilling efficiency and accelerate wear of the sliding components. This study shows the trib...
Article
The demand for high performance and customizable oral care products requires addressing technical challenges in dentistry, including tribology. The existing literature on dental tribology is scattered and existing clinical and laboratory testing methods for evaluation of tooth damage and wear are conflicting. Thus, a clear scientific understanding...
Article
Inconel 617 is among the best candidates for utilization in high temperature gas cooled reactor tribo-components. However, the combined effects of sliding contact, along with intermittent idle times and very high temperature material degradation, deteriorates the alloy tribological performance, especially under a helium atmosphere. Laser peening is...
Article
Major interest has recently been raised by zinc-ion hybrid supercapacitors (ZIHSCs) as a promising development in the realm of electrochemical energy storages because of their impressive energy and power densities, ease of manufacturing and handling in air, cost effectiveness, durability, safety, natural abundance, eco-friendliness, and high volume...
Article
In coiled tubing applications, common constraints e.g., high friction, lateral drag and restricted flow rate increase the demand for friction modifiers. These modifiers also face the inevitable intrusion of abrasive particles in the wellbore that impair the drilling efficiency and accelerate wear of the sliding components. This study shows the trib...
Article
Bearing materials in future missions to Venus will encounter high temperatures (~462°C) and extremely dense CO2 atmosphere. Herein, we report on the tribological behavior of PS400 coating (NiMoAl-based alloy) vs. DLC coating at 25, 300, and 500°C under CO2 and air environments. We found that at 25°C DLC provides excellent lubrication and extreme we...
Article
Polymer thin films are deposited onto rigid materials for testing mechanical properties. However, the functionality of nanocomposites typically requires compliant substrates. Hence, it is important to investigate the nanomechanical properties of these films deposited on both substrates. This study compares the nanoindentation and nanoscratch behavi...
Article
Full-text available
The application of nontoxic 2D transition‐metal carbides (MXenes) has recently gained ground in bioelectronics. In group‐4 transition metals, tantalum possesses enhanced biological and physical properties compared to other MXene counterparts. However, the application of tantalum carbide for bioelectrodes has not yet been explored. Here, fluorine‐fr...
Article
Full-text available
In article number 2100015, Sanjiv Dhingra and co‐workers demonstrate fluorine‐free development of a tantalum carbide MXene‐tantalum oxide (TTO) hybrid structure through an innovative and facile protocol. TTO as an efficient biocompatible material for supercapacitor electrodes possesses biocompatibility with different types of human cells, and offer...
Article
Full-text available
Nitrogen doped diamond-like carbon (NDLC) is a candidate protective coating in state-of-the-art heat assisted magnetic recording (HAMR) media. To ensure the robustness of the media particularly at higher temperature applications, mechanical properties of ultra-thin sub 5-nm NDLC coatings are of great interest. Due to instrument limitations and very...
Article
The present study focuses on the chemical and physical synergy between three base oil/additive mixture lubricants which are used in well drilling for oil and gas. Three additives namely, a polymer of cashew-nutshell-liquid, a surface modified melamine cyanurate, and a diol alkane were mixed in a dearomatized commercial base oil and tribotested in t...
Preprint
Full-text available
High-performance polymers (HPPs) with self-lubricating properties are promising materials for bearing and tribological components that demand low friction and low wear in the absence of liquid lubrication. This study reports on the tribological performance of three advanced HPPs, namely ATSP-, PEEK-, and PI-based polymer composites. The experiments...
Article
Adhesives with reversible bonding characteristics are useful in different applications which demand assembly and disassembly of components, over repeated times. To achieve reversible bonding, the bonding strength of the adhesives on the substrate should be sufficiently high to ensure cohesive failure and with minimized adhesive failure after each b...
Article
Despite intense studies for numerous scenarios, the potential of graphene as a lubricant additive for oil & gas drilling applications remains rarely investigated. This study investigates the influence of graphene on the tribological performance of three different aqueous base drilling fluids: distilled water, artificial seawater (KCl brine), and po...
Article
Full-text available
The majority of data generated today is stored in magnetic storage hard disk drives (HDD) of enterprise-level data centers. The HDD industry is striving for higher areal density capacity to meet increasing demand for data storage. Heat-assisted magnetic recording (HAMR) has been proposed as the next-generation technology that will bring revolutiona...
Article
This study investigates the chemical changes of the surface of Alloy 800HT during sliding contact under helium atmosphere in the presence of impurities at 750 °C, which is of interest for the nuclear industry. The alloy samples are exposed to helium (He) atmosphere at high temperature for long duration of 500 h to identify the chemical and topograp...
Article
Developing an efficient all‐solid‐state structural supercapacitor with simultaneous high energy storage and load-bearing capabilities for reducing weight/volume in weight- / weight- restricted applications remains challenging. Relying only on the sole mechanism of the electrical double layer and the existing trade-offs between load bearing and ener...
Article
In response to continuously declining availability of fossil fuels, nuclear power has become an important alternative source of power generation. Growing application of nuclear power has relieved the shortage of electricity. However, it is also accompanied with new drawbacks, such as radioactive waste, and potential catastrophic consequences in cas...
Chapter
Full-text available
High-performance polymer coatings (HPPCs) and their blends are designed for advanced engineering applications where low friction and wear are of great importance for the performance and lifetime of components. In this chapter, thermal and mechanical properties of polymer coatings based on HPPCs are discussed. These polymers are based on polyether e...
Article
Polymers with self-lubricating properties have been employed in various applications as bearing components and tribological surfaces, particularly where the use of liquid lubricant is infeasible, such as space-related applications. This study reports on tribological solutions for extreme temperature ranging from −196 to 300 °C, which simulates extr...
Article
PS400 is a multi-component alloy developed by NASA and intended for high temperature bearing applications. This study reports on four mating surfaces, namely bulk 4130 steel, diamond-like carbon (DLC), polycrystalline diamond, and molybdenum boride cobalt chrome coatings sliding against PS400 coating, and the best performing tribopair at 25 and 500...
Article
Full-text available
Elevated temperature tribological properties of ultra-thin nitrogen-doped carbon overcoat (NCOC) protective film for magnetic disks were investigated. NCOC with three different thicknesses (2.5, 3.5, and 4.5 nm) were examined in terms of both chemical and mechanical properties at temperatures up to 300 oC. The chemical changes were traced by XPS, r...
Article
Since their introduction in the 1960s, oil-based drilling fluids or muds (OBM) have been applied as drilling fluids in oil & gas exploration activities. However, they cause potential issues, such as contaminating immediate areas of freshwater aquifers around the well site, and causing permanent damage to the environment during the disposal of cutti...
Article
The assembly of three dimensional (3D) structures through compressive buckling of 2D precursors can serve as a promising and robust tool to realize different classes of advanced materials in a broad range of applications with complex geometries and a span of length scales from sub-micron to macro scales. In this study, a shape memory polymer (SMP)...
Article
In oil and gas drilling, the borehole temperature can be as high as 200 °C. Using a high pressure and high temperature drilling fluid tribometer, two different lubricant additives (Additives A and B) were introduced to reduce the coefficient of friction (COF) of the drilling fluid. Stribeck curve analysis at 125 °C shows that the sliding speed does...
Article
Inconel 617 is a principal candidate material for helium gas cooled very-high-temperature reactors with outlet temperatures of 700-950 °C. Recent findings showed that this alloy develops unique surface oxide layers especially at high temperature (HT) helium environment with distinctive wear, friction and contact properties. This study investigates...
Article
Microtexturing has been implemented to analyze its efficacy in improving the tribological performance of polymeric materials for potential marine applications. Textured and untextured pins were fabricated using aromatic thermosetting copolyester (ATSP) and tested against a copper alloy. Experiments were conducted under both starved and fully floode...
Article
Surface micro-texturing has been proven an effective way to reduce friction and wear for tribological applications. In current work, we propose a low cost hot sintering method to apply micro-texturing on an advanced bearing polymer material. In step 1 of this method, one face of the mold was micro-textured using a micro-casting method, in step 2 th...
Article
Recent advances in the assembly of three-dimensional (3D) structures driven by compressive buckling have provided an opportunity to exploit the capability in a broad range of engineering applications. These include microelectromechanical systems, energy storage, and wearable electronic devices. The occurrence of defects during fabrication and assem...
Article
The efficacy of microtexturing on the tribological performance of Aromatic Thermosetting CoPolyester (ATSP) and Ultra High Molecular Weight Polyethylene (UHMWPE) were investigated under oil-lubricated starved conditions. Nominal contact pressures of 5.02 and 10.04 MPa were applied over a range of sliding velocities, 0.008–2.278 m/s. Static and kine...
Article
Full-text available
CoCrPt material is used for perpendicular magnetic recording media due to its high magneto-crystalline anisotropy that brings good thermal stability on the media. The addition of SiO2 between the CoCrPt grains offers benefits including lower noise and better thermal stability. It has been reported that the SiO2 content has strong effects on the med...
Article
The present study investigates the effect of surface polishing on the tribological performance of two notably different coatings, namely chromium carbide and aluminized, under three-body abrasive conditions. Surface polishing altered the topographical and mechanical properties of the coatings. Detailed analysis of the most relevant roughness parame...
Article
Graphite filled polytetrafluoroethylene (PTFE) and polyimide (PI) composites were tested against tool steel under nominal contact pressure of 6.32 MPa and sliding speed of 1.91 m/s in clean ISO 46 lubricant, and also contaminated lubricant with 4200 ppm of silica sand. Pin-on-disk test results show higher friction and wear of the tribopair in the c...
Article
Full-text available
Understanding mechanical behaviors influenced by electric potential and tribological contacts is important for verifying the robustness and reliability of applications based on metallic porous nanostructures in electrical stimulations. In this work, nickel-based metallic porous nanostructures were studied to characterize their mechanical properties...
Article
Polyamide (PA) is used in industrial applications such as automotive, gears, bearings, and pipeline spacers. As a bearing material, PA can support high contact pressures under low sliding speeds. To achieve high-performing and durable contacts, it is necessary to have low friction, low vibration, and low wear between PA and steel contacts at differ...
Article
Full-text available
Some tribological applications demand reliable operation over a wide range of temperatures and the absence of liquid lubrication. Under these circumstances, polymer composite coatings have been suggested as an alternative to liquid lubrication. This study investigates the tribological performance of an advanced high-bearing aromatic thermosetting p...
Article
Adding lubricant additives is a predictable method to decrease the frictional resistance in oil and gas drilling applications. In this work, tribological studies were carried out for drilling fluid with/without lubricant additives at different temperatures up to 200 °C and environmental pressure of 3.45 MPa. In pure fluid, additive A exhibited high...
Article
Nickel-based alloy 800HT is considered one of the main candidate alloys for nuclear reactors with gas cooled high-temperature environment and, therefore, it is necessary to have a thorough understanding of the alloy tribological response for obtaining optimum operating and loading conditions. The current study investigated the wear and friction beh...
Article
Full-text available
Three different surface treatments, which are of interest to the oil and gas industry, and are commonly used for tribological applications at elevated temperatures, namely chromium carbide (CrC) coating, Ni–P coating, and boronized nickel alloy were investigated. In addition to different structural compositions, these surface treatments possess dif...
Article
This study investigates the friction and wear behavior of Inconel 617, one of the primary candidate materials for high-temperature gas-cooled nuclear reactors. Using a custom-built, high-temperature tribometer, a helium (He)-cooled reactor environment was simulated up to 950°C. To obtain a comprehensive understanding of the Inconel 617 tribological...
Article
In comparison to conventional vertical hole drilling, extended reach drilling wells with long horizontal section require higher driving torque due to the increased drag on the drill string, drill column, casing and other equipment. This has led to higher friction and wear on the drilling equipment. Friction and wear preventive properties of oil-bas...
Article
Reversible bonding is an attractive option for assembly and disassembly of reconfigurable space structures due to the simplicity of the fastening concept. Interchain transesterifications reaction [ITR—a type of dynamic covalent exchange reactions afforded by aromatic thermosetting copolyesters (ATSP)] between two ATSP coatings can successfully be u...
Article
Biology involves inherently complex three‐dimensional designs. In addition to the geometric complexity, thin and complex biostructures composed of membranes such as insects, wings, and plants leaves can achieve complex functionalities under vibrations, such as maneuverability and resistance to strong winds, respectively. They do so by changing the...
Chapter
In recent years, the applications of polymers for tribological purposes have been increasing. Understanding the tribological performance of polymers is critical for successful applications. The tribology of polymers is complicated. For example, friction is affected by load, sliding velocity and temperature, and wear can arise from abrasion, adhesio...
Chapter
Full-text available
In this chapter, different advanced polymeric coatings and their applications are reviewed. Polymeric coatings have broad properties and functions; herein we discuss the coatings’ deposition methods and three different functional advanced polymeric coatings, namely, tribological coatings, superhydrophobic coatings and self-healing coatings. Advance...
Article
Highly conformal HfBxCy coatings were synthesized using low-temperature chemical vapor deposition (CVD) using a mixture of the precursors hafnium borohydride and dimethylbutene at a substrate temperature of 300 or 600 °C. The film composition was a function of the relative gas injection rates and the substrate temperature, which resulted in variabl...
Article
Extended-reach-drilling (ERD) wells are expensive and challenging; however, in special situations, compared with conventional drilling, ERD wells are more environmentally friendly and cost-effective. Application of drilling fluids with good lubrication for ERD is one of the most important methods to facilitate longer total depth (TD) of the wells....
Article
In this study, we report on the mechanical cleavage of conductive metal-based aluminum diboride (AlB2) flakes. The cleavage resulted in a highly single crystalline 2D material and had an atomically flat and smooth surface as shown by atomic force microscopy (AFM) and secondary ion mass spectrometry. Nanoindentation and AFM imaging of freshly cleave...
Article
We present a highly sensitive force-displacement transducer capable of performing ultra-shallow nanoindentation and adhesion measurements. The transducer utilizes electrostatic actuation and capacitive sensing combined with microelectromechanical fabrication technologies. Air indentation experiments report a root-mean-square (RMS) force resolution...
Article
In article number 1703852, Andreas A. Polycarpou and co-workers fabricate and study the deformation of three-dimensional (3D) multilayered Kirigami microstructures with potential applications in 3D microelectromechanical systems (MEMS) devices. The mechanical response under flat-punch compression is studied using combined experiments and finite ele...
Article
The current study investigates the friction and wear behavior of two primary candidate materials, Inconel 617 and alloy 800HT for high-temperature gas cooled nuclear reactors/very-high-temperature reactors. Using a custom-built high temperature tribometer, helium cooled reactor environment was simulated at room and 800 °C temperatures. Microscopy a...
Article
Mechanically guided 3D microassembly with controlled compressive buckling represents a promising emerging route to 3D mesostructures in a broad range of advanced materials, including single-crystalline silicon (Si), of direct relevance to microelectronic devices. During practical applications, the assembled 3D mesostructures and microdevices usuall...
Article
Extended reach drilling wells enable the reach of large areas of reservoir, and thus higher oil & gas production. However, the friction force encountered between the drilling string and wall set a limitation of the total reach area. In this work, we used an aromatic thermosetting copolyester (ATSP) coating for friction reduction for drilling applic...