This study tests a custom-designed knee implant made of an FDA approved biomaterial, Chronoflex AR. The implant is designed to cushion the damaged cartilage at the distal end of the femur to reduce knee pain without the removal of cartilage and bone. A patient’s MRI scan was used to render a 3D computer graphic design of the knee. The manufacturing of the implant is conducted by 3D printing the shape of the distal end of the femur and coating it with the biomaterial. This is a preliminary fabrication method. Ultimately, the implant material will be 3D printed or cast in 3D printed molds. A successful implementation of this sort of custom-designed implant would reduce the invasiveness of knee correcting procedures, enable the patient to retain the shape of his or her femoral and tibial anatomy, and reduce the possibility of revision surgeries. A custom knee implant testing machine was designed and fabricated to measure the force, elastic deformation, plastic deformation, wear and fatigue of the component after performing lab tests simulating a normal walking pattern while adhering to ISO standards.

The paper studies the ventilated façade as a potential alternative to conventional coating technologies for the thermal insulation of building’s external walls. The ventilated façade is modeled by means of a CFD approach that accounts for the full 3D-geometry of the building, the walls thickness and materials’ thermal properties. The effects of the windows on the heat losses and in the performance of the ventilated façade are modeled in order to accurately characterize the thermal behavior of the system. The solar radiative heat transfer during two representative days of the year is considered in the analysis and a multiband thermal radiation is adopted to capture the different nature of radiative heat exchange according to the light wavelengths. The numerical approach enables to estimate the thermo-fluid dynamic behavior of the system and the temperature distribution and the velocity flow field within the air gap between the walls are addressed and their influence on the heat transfer through the building’s external walls is determined. The CFD analysis is employed to compare different configurations of the ventilated façade for improving the thermal insulation of the building; the performance of each scenario is determined in terms of electric energy and fuel consumption for the air conditioning and the heating system. Thus, the potential saving of the energy cost for ambient thermal conditioning is evaluated. The analysis investigates the effects on the energy efficiency of different geometrical features of the system such as the height of the building and the air gap thickness and theoretical correlations are derived in order to estimate the best tradeoff between the energy efficiency of the building and the investment of the ventilated façade configuration.

Similar to direct energy deposition (DED) technology, electrostatic adhesion method can also be employed to deposit powder on targeted areas without direct contact. In this paper, feasibility of utilizing the electrostatic adhesion method (EAM) in material deposition step of metal-power-based additive manufacturing is assessed through theoretical models and experimental verifications. A dielectric layer is proposed to be pre-coated on targeted areas to keep the powders being electrostatically attracted and charged without dropping before laser scanning process. Through this study, it is found that the net force of a single metallic particle on top of the deposited powder layer with a different thickness of the dielectric layer can be determined, leading to the suggestion of suitable coating thickness corresponding with desired particle radius. Results showed that the deposition layer thickness can be predicted with the knowing coated dielectric layer thickness and the powder size distribution. With the proposed electrostatic deposition method, a thinner layer compared to DED technology can be deposited, while maintaining its ability to deposit powder layer over a larger area. Through experiments, the developed electrostatic model is validated with results indicating that the deposition layer thickness can be predicted and controlled with the knowing coated dielectric layer thickness and the powder size distribution.

Thin films of titanium-silicon carbonitride (TiSiCN) with titanium adhesion layers were deposited at approximately 280°C on horizontally and vertically-mounted strips of 301-stainless steel by reactive magnetron sputtering. Considerable differences in the mid-deflections and radii of curvature between the vertical and horizontal samples were observed. Cross-sectional characterizations done on a TEM revealed a columnar growth and uniform microstructure. A finite-element model of the tri-layer sandwich structure using Mesh-Tie constraints was developed to estimate the intrinsic stress levels in the overcoat as probable functions of substrate location and orientation. The computational model in the absence of intrinsic stress was validated by analytical expressions for multilayer films. The initial stress state parameter was varied in Abaqus until consistency in curvature-values was achieved with the physical measurement obtained from an optical setup specially-constructed for this purpose. The difference in the S11/S22 principal stresses provided the intrinsic stress estimate. The calculated values of intrinsic stress were then applied to an FEA test model with fixed constraints to computationally determine the stress reduction for individual samples.

Maintaining material inhomogeneity and sample-to-sample variations is crucial in fracture analysis, particularly for quasibrittle materials. We use statistical volume elements (SVEs) to homogenize elastic and fracture properties of ZrB 2 -SiC, a two-phase composite often used for thermal coating. At the mesoscale, a 2D finite element mesh is generated from the microstructure using the Conforming to Interface Structured Adaptive Mesh Refinement (CISAMR), which is a non-iterative algorithm that tracks material interfaces and yields high-quality conforming meshes with adaptive operations. Analyzing the finite element results of the SVEs under three traction loadings, elastic and angle-dependent fracture strengths of SVEs are derived. The results demonstrate the statistical variation and the size effect behavior for elastic bulk modulus and fracture strengths. The homogenized fields are mapped to macroscopic material property fields that are used for fracture simulation of the reconstructed domain under a uniaxial tensile loading by the asynchronous Spacetime Discontinuous Galerkin (aSDG) method.

A method to fabricate high temperature protective structural coating on top of critical gas turbine components by additive manufacturing (AM) technique using oxide dispersion strengthening (ODS) powder is presented. A novel combined mechanochemical bonding (MCB) plus ball milling (BM) process is utilized to produce ODS powders with nano-crystalline gamma prime phase. AM-assisted ODS coating by direct energy deposition (DED) method on MAR-247 substrate, with laser powers from 100W to 200W were carried out. The ODS coated samples were then subjected to cyclic thermal loadings for over 2000 cycles. Depth-profiling x-ray photoelectric spectroscopy (DP-XPS) was applied for detailed oxide formation analyses through the ODS coating layer at various thermal cycles. Corresponding mechanical properties such as Young’s modulus, yield strength and hardening component of ODS coating samples at various thermal cycles were measured at room temperature using an in-house developed non-destructive spherical micro-indentation testing method. Correlation of the measured mechanical properties with evolution of the ODS microstructures are studied. In particular, stability of gamma prime phase in the ODS coating after thermal cycles is analyzed. Test results revealed a thin steady durable alpha alumina oxide layer on ODS coating surface. After 2,200 thermal cycles, strong bonding at ODS/substrate interface is maintained for ODS coated samples with 200W laser power. Test results also showed stable substrate microstructures due to the protective ODS coating even after 2,200 thermal cycles.

In machining operation, cutting tool performs a central role towards the overall machining performance. A user from metal cutting community always look for better cutting tools that can enhance productivity by reducing tool wear and cost. Modification in the micro-geometry of cutting edge is termed as edge preparation, and it is performed to improve the machining performance by strengthening the cutting edge, reducing internal stresses of coating and lowering the edge chipping etc. Edge preparation has a controlling influence on the formation of deformation zones, cutting temperature, cutting forces and stresses at the cutting interface. Vibration assisted machining (VAM) concept is gaining fame in the metal cutting sector community for machining difficult-to-machine materials. In VAM, cutting tool moves with a small amplitude vibration instead of moving with a constant cutting velocity. This small amplitude vibrational movement provides better machining performance for difficult-to-cut brittle materials. The current numerical study utilized different edge prepared micro-geometries such as sharp edge, round edge and chamfer edge etc. cutting tools, and then these cutting tools were used in the numerical simulations of VAM. The study shows higher magnitude of cutting forces under VAM with tools with modified geometry. The study is beneficial for the metal cutting community and opens new areas of industrial applications.

The impact process of a molten metal droplet impinging on a solid substrate surface is encountered in several technological applications such as ink-jet printing, spray cooling, coating processes, spray deposition of metal alloys, thermal spray coatings, manufacturing processes and fabrication and in industrial applications concerning thermal spray processes. Deposition of a molten material or metal in form of a droplet on a substrate surface by propelling it towards it forms the core of the spraying process. During the impact process, the molten metal droplet spreads radially and simultaneously starts losing heat due to heat transfer to the substrate surface. The associated heat transfer influences impingement behavior. The physics of droplet impingement is not only related to the fluid dynamics, but also to the respective interfacial properties of solid and liquid. For most applications, maximum spreading diameter of the splat is considered to be an important factor for droplet impingement on solid surfaces. In the present study, we have developed a model for droplet impingement based on energy conservation principle to predict the maximum spreading radius and the radius as a function of time. Further, we have used the radius as a function of time in the heat transfer equations and to study the evolution of splat-temperature and predict the spreading factor and the spreading time and mathematically correlate them to the spraying parameters and material properties.

Renewable energy sources demands sustainable energy storage technologies through the incorporation of low-cost and environment-friendly materials. In this regard, cellulose nanocrystals (CN), which are needle-shaped nanostructure derived from cellulose-rich resources, are extracted by sulfuric acid hydrolysis of biomass and used as both template and binder for the construction of electrochemical capacitors electrodes. A composite material is synthetized comprising CN and a conjugated electroactive polymer (CEP) to overcome the electrical insulating properties of cellulose as well as to exploit enhanced electrochemical activity by increased electrode surface-area. A one-step in-situ film synthesis protocol is evaluated by performing simultaneous polymerization and film deposition. The effect of proportion of starting components are evaluated through statistical Response Surface Methodology towards optimizing the electrochemical performance. Depending on the mass proportion of the starting components, a conducting network could be created by surface coating of the CEP on the whiskers during polymerization. Electrochemical measurements suggest an increase in specific surface area by at least a factor of two relative to bare CEP as a consequence of the template role of cellulose. Therefore, adjustment of the proposed one-step synthesis parameters allows tuning the material properties to meet specific application requirements regarding electrochemical performance.

Thermal protection of components such as turbine blades is often done with thermal barrier coatings which are typically ceramic materials. Methods to manufacture ceramic coatings are being developed to create microstructures that optimize thermal protection without degrading mechanical properties of the coating. The coating requires sufficient mechanical properties to remain in place during loads associated with the operation of the component. The work presented in this paper is part of a broader effort that focuses on novel processing techniques. A fabrication method of interest is the inclusion of spherical micron-sized pores to scatter photons at high temperatures along with nano-sized grains to scatter phonons. Pores are sized and distributed so that mechanical strength is maintained. In the current work, yttria-stabilized zirconia (YSZ) is modeled. Three-dimensional microstructures representing YSZ are computationally generated. The defect sizes and orientations are generated to match an experimentally observed distribution. The defects are either randomly or regularly placed in the microstructural models. Stress-displacement analysis is used to determine effective bulk material properties. Comparisons are made to prior two-dimensional work and to experimental measurements available in the literature as appropriate. The influences that defect distributions and three dimensional effects have on the effective bulk material properties are quantified. This work is a preliminary step toward understanding the impacts that micron sized pores, voids and cracks have on thermal and mechanical characteristics. The goal is to facilitate optimizing the microstructure for thermal protection and strength retention.

The current research represents a preliminary investigation of the cold spray metal deposition process which is a form of additive manufacturing and coating repair. It relates the deformations produced from a single particle impact with a substrate surface to the post-impact interfacial fracture behaviors resulting from separate globally applied mode-I and mode-II loadings. The particle and substrate materials were Al 5056 and Al 6061-T6, respectively. A description of the modeling process is presented and its inherent difficulties are discussed. A two-step numerical modeling process was pursued. First, the particle and substrate impact deformations were obtained using the strain rate-dependent Johnson-Cook Flow Stress Material Model for three particle velocities of interest. Second, the modes-I, II and III strain energy release rates ( G I , G II , and G III , respectively) were characterized along the curvilinear impact surfaces using linear-elastic fracture mechanics (LEFM). Crack initiation, crack growth and ultimate fracture loads of the particle-to-substrate interfaces were determined using the Virtual Crack Closure Technique (VCCT). The predicted results were compared for each particle velocity. The influence of mesh discretization, element distortions, interfacial contact surfaces, etc. are elaborated on for consideration in future modeling efforts. This research, in conjunction with future validation tests, is a fundamental step towards the numerical modeling of cold spray fracture behaviors across multiple material length scales; beginning with a single particle/substrate interface, extending to multiple particles and progressing towards the bulk material scale. Results of such models and experiments will identify specific cold spray processing parameters that may be optimized to improve the interface strengths and fracture resistance levels.

The selection of coating or surface treatments is a crucial step in the design of oil and gas equipment to protect against the deterioration caused by wear, corrosion, galling, fatigue, etc. Quench polish quench (QPQ) nitriding is a superior candidate to increase surface hardness for abrasion and galling resistance in carbon or stainless steels. The increased surface hardness improves the wear and corrosion resistance but reduces the surface material ductility. It is generally not recommended for application to V-shaped threads or sharp notches subjected to high stress. During well perforation in cased-hole completion, the detonation of the gun string along with the induced pressure wave in fluids generates a large-magnitude dynamic motion in the gun string. The peak load of a perforating event, from detonation to fluid-structure interaction, happens in the range of microseconds to milliseconds. The coupled wellbore hydrodynamic and structural dynamic shock load may cause an overstress failure in the millisecond scale but is usually overlooked in engineering practice. In this work, we investigated the behavior of QPQ coating under transient dynamic loads, employing both physical test and finite element analysis. We designed a combination of drop test fixture and specimens to simulate a notched specimen subjected to dynamic tensile loads. Two types of specimens were prepared in this study, QPQ-coated specimens and bare metal specimens without coating. The specimens without coating were tested to serve as a baseline for comparison. The methodology in this study provides a generic guideline for design of equipment potentially subjected to transient mechanical shock loads.

Field of composites is rapidly growing in many industries such as aviation, energy and automotive industries. Composites are known to have a high strength to low weight ratio. Significant improvement in the performance of coatings used in the protection of military and civil aircraft has been achieved the last thirty years. Composite coatings are exposed to many environmental conditions, which can significantly affect their properties. In this research, UV light treatment on the surface of composite was introduced to examine its effects on the adhesion properties between the coating and substrate. A cross-cut test was conducted on the composite panels to assess the adhesion of paint to the substrate after the treatments. Coating performance analyses were also carried out using a Fourier transform infrared spectrometer, water contact angle, and optical microscopic images. The first set of panels was treated with UV radiation for 0, 2, 4 and, 8 days, and the surface wettability was also assessed using the contact angle test. Two coats of paints, including a primer and top coat, were used, and the panels were exposed to UV radiation and immersed in water for 500 hrs and 1000 hrs. It was found that untreated panels showed a much higher contact angle of 106°, whereas the contact angle of panels treated with UV radiation was reduced to 47°. The cross-cut tests showed considerable flaking of the coating along the edges and squares of panels that were not treated, and very small flakes along the edges and parts of the grid square on panels that were UV treated, thus confirming the enhancement of coating adhesion between composite and coating surfaces by UV treatments.

Asphalt concrete (AC) consists of asphalt binder and aggregate. Aggregate consists of: coarse aggregate and fines. Asphalt binder creates a coating or film around the aggregate, which is defined as the binder phase of AC. Fines are believed to be trapped inside an asphalt film or mixed with asphalt binder, creating a composite material called mastic. Thus, AC has three phases: mastic, asphalt film binder, and coarse aggregate. All these phases play major roles in performance of AC. Researchers have performed various tests on asphalt binder at micro scale to understand the macro scale behavior of AC. However, test methods developed and performed on binders, to this day, are mostly rheological shear and bending beam tests. No studies have been conducted on the compression stiffness or modulus and hardness of and binder, rather than shear and binders stiffness. In addition, the existing tests used in the asphalt area cannot be performed on binder and mastic while they are an integral part of AC. Nanoindentation tests can be performed on aggregate and asphalt binder while they are integral parts of AC. Because, in nanoindentation test, a nanometer size tip, which is smaller than binder film thickness as well as other phases. In the study, Performance Grade (PG) 64–28 was used for the study, same binder had been used afterwards to characterize asphalt and AC. A loading rate of 0.005 mN/sec, a dwell time of 200 sec and a maximum load 0.055 mN were employed in the study. In the current study 20 indentations were done on the asphalt binder sample and 100 indentations were done on AC sample, due to heterogeneity of the sample. However, to identify a specific phase in AC sample, the current study adopts the depth range technique for as same loading protocol. The depth rage of binder phase was acquired by independent indentation on same asphalt binder sample. As, asphalt is known to be a viscoelastic material that exhibits creep behavior, the creep compliance of asphalt binder was used for validation of the depth range assumption. The validation of phase identification was done by comparing the asphalt binder phase creep response while they are integral part of AC with creep response of independent asphalt binder sample under nanoindenter. The comparison shows depth resolution technique can successfully identify the binder phase of AC.

Industrial activity of aluminum surface coating, namely by electrostatic painting with a polyester powder based resin, generates a significant array of wastes. Among these wastes, paint dust is classified as 08 01 12 on the European List of Wastes. As consequence of the inexistence of adequate treatment routes for its correct management, this waste is currently landfilled, without any energy and / or material recovery. Therefore, the development of proper waste management technologies in line with the environmental policies is imperative in order to improve the industrial competitiveness and to preserve the natural resources. In the present work, RDFs (Refused Derived Fuel) were produced, as pellets, for energetic valorization. These experimental RDF pellets were manufactured by mixing the industrial paint dust with sawdust (1.5 and 3%) and with paperboard (1.5%). They were subsequently tested on a purpose built experimental boiler and the combustion efficiency was assessed in terms of gaseous emissions and chemical composition of the bottom and fly ashes. The paint dust waste was delivered by a local surface treatment company and characterized concerning chemical, physical and eco toxicological properties, proving to be rich in Carbon (50.2%) and Hydrogen (4.73%). The obtained RDFs were characterized for mechanical durability, elemental and chemical analysis, bulk density and lower heating value. Results show that the utmost lower heating value (19670 kJ/kg) was obtained for the maximum incorporation content of paint dust waste tested (3%). Combustion trials were carried out at a fuel flow rate between 2 and 3 kg/h. The results showed that the incorporation of paint dust waste resulted in a decrease of the thermal efficiency which suggests that the air fuel ratio was not properly adjusted to the varying heat value of the fuel blend. For all the tests, the mass flow rate and the quality of the gaseous emissions were evaluated for the most relevant pollutants such as particles, SO 2 , TOC, CO and NOx. All parameters, except for particles in one single case, comply with strict environmental limits applicable. Samples of ashes have also been collected and their chemical composition correlated with the fusibility behavior. The results show that such levels of incorporation could be an effective process for paint dust waste management from both the environmental and energetic points of view.

Methods for reducing surface reflections during PIV measurements are commonly discussed, but the effects of those surface reflections on PIV measurements are generally neglected. In this study, a comparison of light gathering characteristics of an experimental tomographic PIV system is made using a bluff body model that is coated: i) first, with a commercially available flat white aerosol paint and ii) second, with an airbrushed Rhodamine (R6G) fluorescent paint. For each coating, PIV measurements are compared from flow regions that are affected by either direct or indirect reflections. Measurements show that very little incident light is absorbed at white boundaries, producing strong light reflection; this effect, in turn: i) saturates the light signal from far-removed suspended particles and ii) greatly reduces the signal-to-noise ratio for particles situated even close to the receiving optics. By contrast, Rhodamine (R6G) fluorescent paint provides excellent surface reflection mitigation when paired with the 532 nm filters, producing a signal-to-noise ratio sufficient to allow uniform imaging of particles across the entire calibrated volume.

A durable superhydrophobic coating formulation with epoxy binder thermoset was used to coat on surfaces, which provide high quality for corrosion protection, reduced biofouling and improved hydrodynamic behavior. The single and double layers coating of these nanostructured epoxy were fabricated and coated on a novel quartz crystal microbalance (QCM) technique to investigate their hydrophobic properties. Different static and dynamic wettability were obtained and characterized by evaluating the electrical impedance of QCM coated with nanostructured epoxy in air and DI water. It was found that QCM is able to quantitatively characterize the hydrophobicity of these nanostructured polymer surfaces. For double layer coating, the frequency shift in DI water was smaller in comparison to the single layer one. The reduction in mechanical impedance of QCM clearly demonstrates the effect of enhanced hydrophobicity for both single and double layers. The experimental results show that the hydrophobic surface resulted in smaller mechanical impedance loading, while the hydrophilic surface exerted much larger mechanical impedance. The outcome of this research will build a solid foundation for the further improvement of vehicles coated with superhydrophobic surfaces operating in water and increased equipment life.

High temperature corrosion is a grave problem in incinerators, boilers, turbines and IC engines. To prevent hot corrosion, alloying of metals is usually done. But it does not conserve mechanical properties like creep, toughness, ductility etc. Coating is a generic way to enhance the materials life at elevated temperature in the presence of salts. Sol-gel method of coating is easy and cheap as compared to thermal spray coatings. In the present work, Cerium substituted Silicon-Zirconium coating is prepared via Sol-Gel route. It is deposited on Chromium based super alloy SS-304. Sol-gel dip coating method is used for coating the materials. Cyclic oxidation tests are performed at 900°C in the presence of Na 2 SO 4 salt solution on coated and bare samples. The weight gain analysis shows that coated samples have shown better corrosion resistance than bare specimen cyclic oxidation in simulated environment. SEM, EDS and X-ray mapping techniques are also confirmed that organic precursors of Silicon and Zirconium useful in creating uniform coating. However, coating showed cracks after calcinations which may be due to higher rate of drying. But cracks become self-healed when specimen was subjected to simulated environment at 900°C due to grain growth of Zirconium particles. X-ray mapping showed that protective layer of cerium and Zirconium present at surface of SS-304 and coating was successful in providing resistance to substrate metal from penetration of salts.

The GMAW process using two wires is an alternative to a coating process when high productivity is desired. The potential variants emerging from this process are GMAW cold wire and GMAW double wire. One of the greatest difficulties is the setting of its parameters, which duplication compared to conventional GMAW and also act in a dependent manner. A greater understanding of the technology applied to coatings on turbines in various positions is critical to master the process and its variables for enhancing industrial applications. This study involves an experimental evaluation to verify the influence of some variables on the profile of cord and wear resistance. This paper proposes making deposits with weld metal AWS 308LSi stainless steel and alloys of cobalt (Stellite 6 and 21) plates in carbon steel SAE 1020 in the flat positions. The wear characterization in the lining is used to determine the hardness and surface topography. It is concluded that cobalt alloys have superior resistance to erosive damage, with emphasis on Stellite 21 with respect to erosion and Stellite 6 with respect to cavitation. Mixtures of austenitic stainless steel and cobalt alloys have intermediate wear values. Therefore, it is essential to study welding processes with multiple wires, as proposed in this paper, to determine the optimal combination of alloys for resistance to cavitation-erosion phenomena.

The application of lightweight materials for tanks for transportation appears promising. Besides saving weight and therefore transportation costs, new complex geometries that depart from common cylindrical shapes of steel tanks can be manufactured. For transportation of dangerous goods, fire and explosion safety must be maintained to prevent accidents with serious consequences. In this work the fire behavior of lightweight tanks made from glass fiber reinforced plastics (GFRP) with complex geometries is investigated. Pretests on intermediate scale GFRP plates are conducted to identify suitable fire protection systems and surface treatments for composite tanks. The fire resistance is shown to be improved by addition of fire protective coatings and integrated layers. Finally, a complex rectangular GFRP tank with a holding capacity of 1100 liters is fire protected with an intumescent fire coating. The tank is filled up to 80 % with water and burned under an engulfing fully developed fire. It was shown that the intumescent layer could expand before the decomposition of the resin occurred. Furthermore, the adhesion between tank surface and coating was maintained. The structure could withstand a fire for more than 20 min.