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The non-degradable metallic implants, such as bone screws, often act as the source of dysfunction and harmful corrosion products in the aqueous environment inside the human body. Many of these implants are fixed either temporarily or permanently into the human body, and therefore, both need to match tight tolerances with a remarkably finished surface to eradicate burrs or striations. In this regard, the new generation of degradable magnesium (Mg) alloy implants with excellent osseointegration and low elasticity (like that of human bone), minimizing stress shielding, have been identified as potential candidates to challenge surgical procedures reintervention. However, the biological response of an implant toward the cells in vivo can be predominantly regulated by modifying the surface chemistry, morphology, and corrosion characteristics. Powder or abrasive-mixed-micro-electric discharge machining (A-M-µ-EDM) is gaining attention for executing precision machining and achieving a simultaneous surface modification on micro-manufactured surfaces, suitable for clinical applications. Therefore, the present research aimed at improving the surface characteristics of Mg AZ31B alloy via an augmented performance of A-M-µ-EDM by adopting copper and brass-micro-electrodes (C-µ-E and B-µ-E) in association with distinct abrasive particle concentrations (APCs: 0, 1.5, 3, 4.5, and 6 g/l) of bioactive zinc abrasives. To enhance the A-M-µ-EDM capabilities, the experiments were designed with a one-variable-at-a-time (OVAT) strategy, and the trial runs were conducted using different combinations of µ-electrodes and APCs. The superior performance of A-M-µ-EDM was noticed with the fusion of C-µ-E and 3 g/l APC in terms of minimum machining time (MT) and dimensional deviation (DD). The additional outcomes of this work reported favorable improvements in surface morphology, chemistry, topography, wettability, microhardness, and corrosion resistance on the A-M-µ-EDMed sample of interest.

The present study aims to understand the influence of surface mechanical attrition treatment (SMAT) on corrosion, wear, and in vitro cell viability of Ti-6Al-4V alloy. XRD analysis quantified the extent of surface nanocrystallization and the induced strain, which increased from 0.096 ± 0.021 to 0.166 ± 0.039, and so did dislocation density (from 1.55 × 1022 to 4.62 × 1022). TEM analysis advocated for grain refinement and also manifested the occurrence of mechanical twins as well as dislocation walls in the SMATed surface. SMAT processing decreased the corrosion rate in simulated body fluid by ~75%, from 0.167 ± 0.097 mpy to 0.040 ± 0.015 mpy. This was attributed to the nanocrystallization that led to the creation of a stable and insoluble TiO2 passive film at the interface of the surface and electrolyte. Grain refinement of the SMATed surface also derived an improvement in the wear resistance and cell adhesion property.

Current study deals with the effect of carbon nanotube (CNTs) and graphene nanoplatelets (GNPs) reinforcement on the mechanical properties and the adhesion strength of plasma sprayed alumina (Al2O3) single splats, using in-situ picoindentation and nanoscratch test, respectively. The hardness of the Al2O3 splat was measured as 18 ± 5.3 GPa which increased to 34.22 ± 8.44 GPa on 1 wt% CNTs addition and to 42.5 ± 9.06 GPa on 0.5 wt% GNPs addition. Hybrid addition of CNTs and GNPs provided the maximum hardness value of 51.25 ± 8.76 GPa to the Al2O3 splat. Similar trend in the elastic modulus has been reported with a minimum value for Al2O3 splat, i.e. 159 ± 35.40 GPa, and maximum for the Al2O3 splat mixed synergistically with CNTs and GNPs (269 ± 43.12 GPa). Adhesion strength of the Al2O3 splat (0.21 ± 0.11 MPa) also showed a nearly 5-fold increase on hybrid addition of CNTs and GNPs with a maximum value of 1.08 ± 0.38 MPa. This improvement in the properties were due to the extremely high mechanical properties of CNTs and GNPs and better melting of the splats, which not only improved the densification but also provided a better interlocking between the splat and the substrate.

The non-degradable metallic implants, such as bone screws, often act as the source of dysfunction and harmful corrosion products in the aqueous environment inside the human body. Many of these implants are fixed either temporarily or permanently into the human body, and therefore, both need to match tight tolerances with a remarkably finished surface to eradicate burrs or striations. In this regard, the new generation of degradable magnesium (Mg) alloy implants with excellent osseointegration and low elasticity (like that of human bone), minimizing stress shielding, have been identified as potential candidates to challenge surgical procedures reintervention. However, the biological response of an implant toward the cells in vivo can be predominantly regulated by modifying the surface chemistry, morphology, and corrosion characteristics. Powder or abrasive-mixed-micro-electric discharge machining (A-M

Recently, multifunctional coatings offering simultaneous tribological benefits and protection from adverse environments are gaining widespread attention. While, metallic coatings offer excellent durability, their performance is limited to ambient temperature. In this study, it is shown that plasma sprayed Graphene nanoplatelates (GNPs) reinforced CeO2 (CG) coatings offer excellent tribological properties both at room and high temperature. Interestingly, unlike conventional coatings where wear property degrades at high temperature, the wear properties of CG keeps on improving from RT to 873 K. Maximum reduction in wear rate (260%) and COF (26%) was observed at 873 K. It is believed that this coating could pave the path for designing coatings operating at high temperature.

Boron Nitride Nanotube (BNNT) has emerged as a potential reinforcement for ceramic and metal matrices due to its excellent mechanical, chemical, and thermal properties. We have reinforced 5 vol % BNNT into the alumina (Al2O3) matrix using the atmospheric plasma spraying technique in the present study. BNNTs have been successfully retained after experiencing extreme temperatures of the plasma plume. Reinforcement of BNNTs has improved the relative density of pure Al2O3 coating from 90% to 94%, whereas the hardness, elastic modulus, and fracture toughness enhanced by 117%, 35% and 51%, respectively for the BNNTs reinforced coatings. The critical energy release rate increased from 3.90 ± 1.18 J/m2 to 6.50 ± 1.22 J/m2 with BNNT addition. The property enhancement reasons are attributed to improved densification, uniform distribution of BNNTs into the matrix, and toughening mechanisms, such as BNNT truss, nanotube pull-out, and crack bridging. This BNNT strengthened Al2O3 coating could be a successful candidate for highly durable and strong structural material for automobile and aviation sector, high speed cutting tools and in bioimplant sectors.

Splats are the most fundamental and paramount unit of any plasma sprayed coating and splats are having the potential to manipulate the overall property of the same. Current study shows the insulator-conductor transition of alumina (Al2O3) splat by the hybrid addition of carbonaceous nanofillers, namely carbon nanotubes (CNTs) and Graphene nanoplatelets (GNPs) into it. Reinforcement of CNTs and GNPs changed the splat shape from fragmented to nearly disk shaped as well as from porous splat to densified one upon the reinforcement. Further, Current mapping over the splats were carried out using conductive atomic force microscopy (cAFM). Current map for Al2O3 splat showed fully black region, evincing its insulating nature; whereas hybrid addition of CNTs and GNPs into the splat dramatically improved the electrical conductivity of Al2O3 splat, coining its non-conductive map to conductive one. This transition was attributed to electron tunneling mechanism, which is a function of electron hopping distance of these conductive nanofillers. The electron hopping distance of the matrix got minimized when CNTs and GNPs were simultaneously added to Al2O3 splat, due to their higher aspect ratio. This led to the formation of a 3-dimensional conductive channels for the electron transport in the matrix, converting the whole splat as conductive.

Hydroxyapatite (HA) coatings, reinforced with varied concentration (0–2 wt%) of Graphene nanoplatelets (GNPs) have been deposited on titanium alloys (Ti–6Al–4V) substrate using atmospheric plasma spraying. Present work studies the effect of GNP concentration on the electrochemical behaviour of the HA coatings in simulated body fluid (SBF). The HA coating exhibited 15% porosity, whereas reinforcement of 1 wt% GNPs in HA (HA-1G) shows 13% porosity, further addition of 2 wt% GNPs in HA reduced the porosity to 10%. Reduction in porosity was achieved as GNPs easily accessed the inter-lamellae to fill the gaps at inter splat region and minimized the occurrence of post-plasma spray defects such as porosity, voids, microcracks etc. These consequences nextward resulted in the significant enhancement in corrosion resistance of the matrix. HA-1G displayed a significant reduction by 67% in the corrosion rate in SBF solution, while this reduction came to 87% for HA-2G coatings. Randomly oriented wrinkles in the GNPs after corrosion process and their hydrophobic nature effectively hindered the SBF infiltration into the coating and resisted their movement towards the underlying substrate. This in turn improved the overall corrosion resistance of the system.

We report in situ fabrication of oxide-free titanium nitride (TiN) coating by conventional plasma spraying technique. Complete oxide free TiN coating without using low pressure or vacuum environment was achieved by using the N2 shroud with plasma spraying. X-Ray diffraction and Transmission electron microscope confirmed the absence of any traces of oxide in the coating. Coating showed exceptionally higher mechanical properties (H: ∼18 GPa; E: ∼317 GPa). Outstanding reduction of ∼15 times in wear rate and ∼4 times in corrosion rate was observed compared to bare substrate (i.e. Ti-6Al-4V).

Addition of 0.5 wt% of graphene nanoplatelates (GNPs) and 1 wt% carbonnanotube (CNTs) in plasma sprayed Al2O3 coating showed the reduction of 93.25% in wear volume loss and 90.94% in wear rate. This could be attributed to the simultaneous effect of enhanced densification, presence of the transferred layer from the counterpart, strong interface between Al2O3, GNP and CNTs and toughening offered by the GNPs and CNTs. The lowest COF value of 0.27 was recorded on addition of 0.5 wt% of GNP in Al2O3 coating, which could be attributed to the graphitic lubrication on the worn track during the wear.

Lanthanum zirconate (La2Zr2O7), an emerging candidate for TBC system, faces stringent concern owing to poor fracture toughness. We report an exceptionally high fracture toughness (5.3 ± 0.4 MPa m0.5) value for a La2Zr2O7 coating prepared by atmospheric plasma spray technique reinforced by carbon nanotubes (2 wt %); the enhancement in fracture toughness was noted to be more than 300% compared to all previous works. Several factors, viz. increased density, uniform distribution of CNTs in La2Zr2O7 matrix, stabilization of pyrochlore La2Zr2O7 phase and various associated toughening mechanism offered by CNTs (e.g., CNT pull out, CNT bridging and crack arresting etc.) was attributed for this surprising enhancement. In addition, splat sandwiching and nanomechanical interlocking between CNT and La2Zr2O7 was found to be unique toughening mechanism. Apart from it, thermal shock resistance of LZC-SD coating performed at 1300 °C, showed the 145 numbers of cycle before the partial delamination of the coating. While, it was only 87 numbers of cycle for LZ-SD coating. The density, hardness, elastic modulus values also depicted a suitable increase. The introduction of CNTs in the La2Zr2O7 matrix did not alter/affect any of the physical properties (phase purity, compositional integrity etc.) of the pristine La2Zr2O7 system.

Spark plasma sintering (SPS) technique was used to consolidate spray dried (SD) powder of TiC (T-SD), TiC-3.5 wt% WC (TW-SD) and TiC-3.5 wt% WC-2 wt% CNT (TWC-SD) at 1600 °C and 50 MPa pressure. Another, similar composition of ball milled (BM) powder of TiC-3.5 wt% WC-2 wt% CNT (TWC-BM) was consolidated by SPS technique at similar parameters, in which in-situ formation of 2-D graphene nanoribbons (GNR) was observed. High temperature plastic deformation (HTPD) behaviours of these four pellets were characterized by in-situ high temperature nanoindentation technique from RT to 650 °C in controlled atmosphere. Occurrence of HTPD was confirmed by analyzing the mechanical properties, plasticity index and plastic deformation zone radius of all four pellets from RT to 650 °C. The structural stability of 1-D CNTs in TWC-SD and 2-D in-situ formed GNRs in TWC-BM pellets was examined by Raman spectra after the HTPD at 650 °C. HR-TEM micrograph has inferred the collapse of CNT edges in TWC-SD pellet and the peeling of GNR layers in TWC-BM pellet after HTPD. However, the CNTs in TWC-SD pellet was able to lower down the plastic deformation zone radius formed due to HTPD by ~60%, while it was only ~20% by in-situ formed GNR in TWC-BM pellet. This was majorly attributed to the difference in stress dissipation mechanisms between CNTs and GNRs. The 1-D CNTs in TWC-SD was found to have axial stress dissipation, while the in-situ formed GNRs in TWC-BM pellet has dissipated the stresses in axial as well as transverse directions because of its 2-D nature.

Pure zirconia (ZrO2) and ceria (16 mol%) stabilized zirconia (CeSZr) thin films were prepared by electron beam physical vapor deposition with varying deposition rates (1, 4 and 8 A/s) in order to correlate the phase changes to the mechanical property. X-ray diffraction and Raman spectra results indicate the presence of mixed monoclinic and tetragonal phases in ZrO2 film, but tetragonal phase dominated at lower deposition rate. However, irrespective of the deposition rate, cerium addition to ZrO2 resulted in complete stabilization of tetragonal phase. Depending on the presence of dual (ZrO2) or single (CeSZr) phase, either surface cracks or well-connected grain structure was observed in SEM, respectively. Thus, CeSZr film showed a four-fold increase in hardness in comparison to ZrO2, which can be attributed to the complete stabilization of tetragonal phase that hinders the crack propagation along the grain. Plastic deformation of CeSZr film was found to be 1.80 × 10−2 GPa, which is about ∼55% higher as compared to pure ZrO2 film (8.04 × 10−3 GPa). Thus, the development of CeSZr coating may lead to better surface protection of many components.

Graphene nanoplatelets (0.5–1 wt. %) reinforced nickel aluminium (NiAl) coating has been fabricated using shroud plasma spray technique in a quest to achieve an optimized strength-ductility combination. Implementation of an inert shroud atmosphere led to the retention of GNPs in the coatings. XPS results confirmed the presence of 62% sp2 C C bond in NiAl-1GNP coatings. In-situ tensile tests were conducted on the free standing coatings to understand the strengthening and deformation mechanisms offered by the GNP reinforcement. NiAl-GNP coatings showed 60% higher tensile strength and 25% improved ductility on mere addition of 1 wt. % GNP. Shearing and tearing of GNPs is also observed which aids to strengthening.

This article reports the effect of hybrid reinforcement of carbon nanotubes (CNTs) (1 wt%) and graphene nanoplatelets (GNPs) (0.5 wt%) on electrical conductivity of atmospheric plasma sprayed alumina (Al 2 O 3 ) coating. The uniform dispersion of CNTs and GNPs were observed over Al 2 O 3 matrix. Scratch test revealed the improved inter-splat bonding strength with addition of CNTs and GNPs, which could lead to improved electrical conductivity of Al 2 O 3 coating. The electrical conductivity increased from ~5 × 10 –12 to ~0.7 S/m, by the addition of CNTs (1 wt%) and GNPs (0.5 wt%) in Al 2 O 3 coating. A drastic improvement of ~ 12 orders of magnitude in electrical conductivity was observed in Al 2 O 3 − 1 wt% CNT- 0.5 wt% GNP coatings. This improvement in electrical conductivity was majorly attributed to the lower porosity and strong inter-splat bonding. In addition, availability of more numbers of conductive channels as a result of homogeneous distribution of CNTs/GNPs and clean interface with Al 2 O 3 has played the significant role in enhancement of electrical conductivity.

Al2O3, Al2O3-1 wt% Carbon Nanotube (CNT) and Al2O3-1 wt% CNT-0.5 wt% Graphene Nanoplatelets (GNP) were consolidated by spark plasma sintering at a temperature of 1500 °C. Spray drying technique was used for uniformly distributing the CNTs and GNPs. Fracture toughness of Al2O3 pellet drastically increased to 168% on addition of CNTs, while substantial improvement of 250% was seen on the addition of both CNTs and GNPs. Interfacial shear stress for Al2O3-CNT-GNP was found to be 350–1100 MPa. Novel toughening mechanisms such as CNT yarning and CNT embedded graphene was found responsible for the drastic improvement in toughness.

Titanium carbide (TiC) is reinforced with 3.5 wt% of tungsten carbide (WC) and 2 wt% of carbon nanotubes (CNTs) in order to improve its thermal shock resistance and mechanical integrity of oxide layer. Three pellets namely, TiC (T-SD), TiC-3.5 wt% WC (TW-SD) and TiC-3.5 wt% WC-2 wt% CNT (TWC-SD) were thermally shocked at 1700 °C in an open atmosphere for 10 numbers of thermal cycles. Raman spectra confirmed the retention of CNTs after thermal cycling, which could be attributed to the thermal shielding offered by the molten TiC to CNTs. HR-TEM image infers the collapse of some of the CNTs into carbon structure after the thermal shocks. The mass loss % of T-SD, TW-SD and TWC-SD pellets were found to be 41.5%, 33.3% and 15.13%, respectively after the 10 numbers of thermal cycles. The rate of mass change in T-SD sintered pellet was found to be ~1.4 × 10 −3 g/min., which got reduced to ~0.4 × 10 −3 g/min. on addition of 3.5 wt% of WC and 2 wt% of CNT. Furthermore, reinforcement of 3.5 wt% WC and 2 wt% CNTs in TiC matrix showed the dramatic increase of 89% in thermal shock resistance parameter (R st ) compared to T-SD pellet. This significant improvement in thermal shock resistance of TWC-SD pellet is mainly attributed to the following three factors viz. (i) higher fracture toughness (ii) higher density and (iii) homogeneous dispersion of CNTs, which hinders the movement of oxygen atoms along the grain boundaries. Hardness of the thermally shocked TWC-SD pellet was found to be 5.1 GPa, which was 1.3 GPa i.e. ~74% higher compared to thermally shocked T-SD pellet. This increased hardness of thermally shocked TiC matrix has been shown to suppress the crack formation and restrict oxidation.

Carbon nanotube (1 wt. %) and graphene nanoplatelets (0.5 wt. %) reinforced aluminum oxide (Al2O3) coating have been deposited on low carbon steel substrate using atmospheric plasma spray technique. Addition of 1 wt. % CNT and 0.5 wt. % GNP has significantly increased the densification from 88% in Al2O3 coating to 97% of the theoretical density in Al2O3 - 1 wt.% CNT- 0.5 wt.% GNP. Relative hardness and elastic modulus has increased by 52% and 48% respectively on synergistic addition of CNT and GNP. Increase in hardness was attributed to improved densification, while increased elastic modulus was due to higher elastic modulus of CNT and GNP and homogeneous distribution of CNT in Al2O3 matrix. An exceptional improvement of 200% in relative fracture toughness was observed in Al2O3 - 1 wt.% CNT- 0.5 wt.% GNP coating. The improvement in fracture toughness is attributed to three major factors viz. (a) increased densification (b) Strong Al2O3, CNT and GNP interface and (c) various toughening mechanism offered by CNT and GNP such as such as bridging and pull out, crack deflection, GNP Splat gluing, nanomechanical interlock etc.

The structural changes on the addition of strontium in samarium doped ceria/Na2CO3 nanocomposites were investigated with respect to sintering temperature. The nanocomposites prepared by a co-precipitation method in the presence (SrSDS) and absence (SDS) of strontium were sintered at 500, 600 and 700 °C. XRD results indicated an increase in crystallite size and lattice parameter with respect to sintering temperature in the presence of strontium. Raman, SEM and FT-IR studies confirmed the presence of Na2CO3 and CeO2 phases. The observed changes in crystallinity and oxygen vacancy concentrations indicate the beneficial role of strontium upon sintering up to 600 °C. The impedance spectral analysis clearly shows the beneficial effect of adding strontium to the composite. The lowest activation energy (0.61 eV) with the highest conductivity (3.8 × 10−3 S cm−1) for SrSDS sintered at 600 °C arises due to the strong interaction between the Na2CO3 and CeO2 phase. However, sintering the composites at 700 °C indicated a negligible effect of strontium due to the decomposition of Na2CO3, thereby limiting the operational temperature of the nanocomposites for potential fuel cell applications.

Pertaining to real-life applications (by scaling up) of hydroxyapatite (HA)-based materials, herein is a study illustrating the role of carbon nanotube (CNT) reinforcement with ceria (CeO2) and silver (Ag) in HA on titanium alloy (TiAl6V4) substrate, utilizing the plasma-spraying processing technique, is presented. When compared with pure HA coating enhanced hardness (from 2.5 to 5.8 GPa), elastic modulus (from 110 to 171 GPa), and fracture toughness (from 0.7 to 2.2 MPa·m1/2) elicited a reduced wear rate from 55.3 × 10−5 mm3·N−1·m−1 to 2.1 × 10−5 mm3·N−1·m−1 in HA-CNT-CeO2-Ag. Besides, an order of magnitude lower Archard’s wear constant and a 41% decreased shear stress by for HA-CNT-CeO2-Ag coating depicted the effect of higher hardness and modulus of a material to control its wear phenomenon. Antibacterial property of 46% (bactericidal) is ascribed to Ag in addition to CNT-CeO2 in HA. Nonetheless, the composite coating also portrayed exaggerated L929 fibroblast cell growth (4.8 times more than HA), which was visualized as flat and elongated cells with multiple filopodial protrusions. Hence, synthesis of a material with enhanced mechanical integrity resulting in tribological resistance and cytocompatible efficacy was achieved, thereupon making HA-CNT-CeO2-Ag a scalable potent material for real-life load-bearing implantable bio-coating.

Present article communicates the successful fabrication of plasma sprayed graphene nanoplatelets (GNPs) reinforced ceria (CeO2) composite coating. Later, various characterizations confirm the presence of survived GNPs into CeO2 matrix and its transformation to few layered graphene during plasma spraying. The reinforcement of GNPs led a significant enhancement in corrosion resistance and mechanical performance. Addition of 5 wt% GNPs in CeO2 displayed an exceptional reduction in corrosion rate about ∼15 times in 3.5 wt% NaCl solution, while superior improvement of 50% in hardness, 98% in elastic modulus and 185% in fracture toughness during indentation has been observed. The GNPs acted as promising corrosion inhibitor and prevented infiltration of electrolytic salts (NaCl) through the coating. Apart from these, entanglement of few layer GNPs with CeO2 matrix and GNP crack bridging between two crack banks enhanced the mechanical performance of the matrix. As a whole, GNPs reinforcement owed the combined improvement in corrosion resistance as well as mechanical performance, which would make it a better option for advanced technological applications.

Manual processing of recorded EEG data for characteristics like epileptic spikes is very time consuming since the recording of EEG for a longer duration producing enormous amount of data. Therefore, automated systems are required to speed up the processing. In the current work, a classificat ion method has been proposed for detecting the epileptic spikes in the recorded EEG data by using Linear Discriminant Analysis (LDA) and has been named LDASpike. The prerecorded EEG data files were used as input to LDASpike and the output produced was the total number of spikes present in each EEG file. The proposed method results on an average sensitivity 100% and selectivity 95.38%, when the train ing and testing data were same. Ho wever, with four fo ld cross- validation applied in this work, the sensitivity and selectivity were achieved as 98.45% and 96.06%, respectively, on an average. Though a little time init ially is spent to train the system but the result produced by the system is very promising and can be compared with the existing standard methods. This system can also works with the real time recording and processing for a clinical setup.

The brain signal or Electroencephalogram (EEG) has been proved as one of the most important bio-signal that deals with a number of problems and disorders related to the human being. Epilepsy is one of the most commonly known disorders found in humans. The application of EEG in epilepsy related research and treatment is now a very common practice. Variety of smart tools and algorithms exist to assist the experts in taking decision related to the treatment to be provided to an epileptic patient. However, web based applications or tools are still needed that can assist those doctors and experts, who are not having such existing smart tools for EEG analysis with them. In the current work, a web based system named WEBspike has been proposed that breaks the geographical boundary in assisting doctors in taking proper and fast decision regarding the treatment of epileptic patient. The proposed system receives the EEG data from various users through internet and processes it for Epileptic Spike (ES) patterns present in it. It sends back a report to the user regarding the appearance of ES pattern present in the submitted EEG data. The average spike recognition rate obtained by the system with the test files, was 99.09% on an average.

A method for deposition of cadmium sulfide (CdS) buffer layer thin films on fluorine-doped tin oxide (FTO) glass, by chemical bath deposition (CBD), has been modified. For achieving relatively uniform and pin-hole-free CdS films, substrate rotation, concentration of CdS salts, and deposition time were optimized. The deposited films were characterized by UV-Vis-NIR spectroscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD), and atomic force microscopy (AFM). Band gap of ~2.4 eV was measured by UV-Vis-NIR spectroscopy, CdS phase was confirmed by XRD, and film uniformity and roughness (~15–20 nm) were measured by SEM and AFM, respectively.

Solid-oxide fuel cell components were fabricated using an atmospheric plasma spraying method. Lanthanum strontium manganite (LSM), 8 mol% yttria-stabilized zirconia (8YSZ), ceria (CeO2), and YSZ-NiO powders were used as feedstock materials for layered deposition of cathode, electrolyte, and anode, respectively, to make a complete cell. In this work, two types of electrolyte materials were investigated, viz., 8YSZ and the one containing 10 wt.% CeO2. Because a high densification is expected in the solid oxide electrolyte (as opposed to observed porosity of ~27%), current work focuses only on the nanomechanical evaluation of the same. Scanning electron microscopy (SEM) images show the retention of nanocrystallinity in the plasma-sprayed deposits. Elemental analyses via energy-dispersive spectroscopy revealed chemically distinct identities of the cell components ruling out diffusion or reaction at the boundaries. Porosity values vary between 29.0% and 35.4% in anode and 42.9–48.4% in cathode, indicating appreciable achievement for high performance of electrode materials. The addition of 10 wt.% ceria to 8YSZ has shown enhancement in the elastic modulus and hardness of the electrolyte material by 18.4 GPa and 1.6 GPa, respectively. Theoretical estimation of thermal conductivity of the plasma-sprayed materials has been found to be in the order of 2.27–4.45 W/mK.

Biodegradable polylactide-polycaprolactone copolymer (PLC) has been reinforced with 0, 2 and 5wt.% boron nitride nanotubes (BNNTs) for orthopedic scaffold application. Elastic modulus of the PLC-5wt.% BNNT composite, evaluated through nanoindentation technique, shows a 1370% increase. The same amount of BNNT addition to PLC enhances the tensile strength by 109%, without any adverse effect on the ductility up to 240% elongation. Interactions of the osteoblasts and macrophages with bare BNNTs prove them to be non-cytotoxic. PLC-BNNT composites displayed increased osteoblast cell viability as compared to the PLC matrix. The addition of BNNTs also resulted in an increase in the expression levels of the Runx2 gene, the main regulator of osteoblast differentiation. These results indicate that BNNT is a potential reinforcement for composites for orthopedic applications.

Near net shape (NNS) fabrication by plasma spray forming (PSF) is a rapid prototyping technique to fab- ricate engineering components having axi-symmetric geometry out of ceramics and refractory metals which are difficult to manufacture by conventional techniques. This study establishes an experimen- tal and computational protocol to manufacture thin walled ceramic (Al2O3) structures on the graphite mandrel (substrate) via plasma spray forming. The combination of experimental and computational approaches reduces currently used empirical methods for the similar purpose. Thermal profiles gen- erated during plasma spraying of Al2O3 on the graphite mandrel for various mandrel designs and cooling conditions were computed by solving the conjugate problem of computational fluid dynamics and 3D unsteady heat transfer. Entire plasma spraying booth was modeled as per actual dimensions to consider the effect on the thermal profile of the mandrel/coating system. The computed temperature profile was compared with the experimentally measured temperature. The corresponding thermal stresses in the mandrel and spray deposited Al2O3 layer were computed. Computed thermal stresses were compared with the fracture strength of Al2O3 to prevent cracking of the spray formed structure during spraying and its successful removal from the mandrel. An optimum temperature increase rate (TIR) during plasma spray forming is defined for the successful deposition and removal of the freestanding ceramic structure.

Hydroxyapatite (HA) reinforced with sub-micrometer Al2O3 and carbon nanotubes (CNTs) has been synthesized as a coating on the Ti-6Al-4V substrate via plasma spraying. The addition of Al2O3 and CNTs to HA has shown improvement in the hardness and elastic modulus by 65% and 50%, respectively, when compared to HA. Consequently, HA-Al2O3-CNT coatings have been nano-scratched to understand their wear performance. Reinforcement of HA by Al2O3 shows a decrease in the wear volume by more than 13 times, whereas HA-Al2O3-CNT coating demonstrated further wear volume reduction of five times compared to that of HA-Al2O3 coating.

Interface in carbon nanotubes (CNTs) reinforced aluminium–silicon composites are studied via thermodynamic and kinetic analysis. A pseudo-phase diagram has been generated based on the thermodynamic calculations to predict the type of carbide (Al4C3 or SiC) that would form at the matrix–CNT interface as a function of matrix composition and processing temperature. The pseudo-phase diagram is useful in high temperature processes like thermal spray forming. Critical thickness values for carbide nucleation suggest the formation of Al4C3 with Al–11.6 wt.% Si alloy and SiC with Al–23 wt.% Si alloy. Thermodynamic calculations show that the amount of Al4C3 increases with an increase in the CNT content. The computed results perfectly agree with the results obtained by XRD, SEM of fracture surface and highresolution transmission electron microscopy (HRTEM) observations on Al–11.6 wt.% Si and Al–23 wt.% Si alloy reinforced with CNT. © 2009 Elsevier B.V. All rights reserved.

The goal of this work is to develop and investigate the properties of a new type of multifunctional composite which is based on multi-walled carbon nanotubes (MWCNT). The composite was prepared from a MWCNT "bucky pa- per" film which was sandwiched between two adhesive layers. Both two point probe and four point probe methods were used to test its mechanical strain sensing properties. The Young' modulus and shear modulus of MWCNT film composite were acquired by the nanoindentation test and direct shear test. A free vibration test was also performed to investigate its structural damping properties. Our research indicated that this new type of carbon nanotube based composite is potentially capable of functioning as a strain sensor and damping device simultaneously for structural vibration control.

A multiple length scale wear study of plasma-sprayed Al2O3–carbon nanotube (CNT) nanocomposite coating is described. CNT content and dispersion have been shown to enhance the macro-wear resistance (pin-on-disk) by more than 49 times, and nano-wear (scratch) resistance up to 18 times. CNTs have been shown to reduce the wear of Al2O3 matrix by (i) increasing densification, (ii) CNT bridging and (iii) CNT lubrication. A strong dependence of wear volume loss on the microstructural features is described at different length scales, and the disparity of material loss observed in the macro- and nano-wear tests is explained. A wear model has been established to numerically quantify wear loss dependence in terms of bulk material properties and correlating these with wear parameters from nano-scratch testing.

Copper-Zinc-Tin-Sulfide (CZTS), a promising material for absorber layer application in thin film solar cells, has been synthesized in aqueous media by microwave irradiation technique. Compared to conventional synthesis methods, microwave irradiation is highly efficient, reliable, and less time consuming. The synthesized nanopowders were characterized for particle size by dynamic light scattering (DLS), phase by X-ray diffraction (XRD), and band-gap by UV-Vis-NIR spectroscopy. Various atmospheric processing methods are being evaluated for the deposition of absorber layers from CZTS nanopowder based ink.

Highly crystalline CIS nanoink was synthesized using highly efficient microwave route. Thin films of CIS were fabricated using the developed ink by drop casting method. XRD pattern of CIS thin films indicates that a chalcopyrite phase with good crystallinity can be obtained using developed ink and that the composition of precursor ink can be transferred directly to the thin film without change in the stoichiometry. The developed ink alleviates the need of organic binders/dispersant and high temperature selenization using highly toxic H2Se gas (or Na2Se as a Se source) after deposition of thin film absorber layer. UV-VIS-NIR absorption analysis indicates that CIS thin film has a band gap of around 1.18 eV.

Composite coatings consisting of TiC/SiC/Ti 3SiC 2 phases have been synthesized using spark plasma sintering (SPS) of Ti/SiC/C powder mixture on titanium substrate. The processing of composite coatings was achieved at 1300�C and 1400�C with a uniaxial pressure of 90MPa and holding time of 8min. Identification and quantification of the phases have been performed using x-ray diffraction (XRD). X-ray elemental maps obtained using EDS have been used to analyze the evolution of various phases and their distribution in the microstructure. A tentative mechanism for phase evolution based on exothermic reactions between various constituent powders has been proposed. Microhardness of the spark plasma sintered coatings was found to be ~3 times that of the Ti substrate resulting in ~100 times lower wear weight loss in ball-on-disc wear tests. � 2011 Elsevier B.V.

The macro- and nano-scale mechanical and wear properties of carbon nanotube (CNT) reinforced Al-Si composite coatings prepared by plasma spraying have been compared in this paper. The composite coatings show a two phase microstructure; one phase being the Al-Si matrix with well dispersed CNTs and the other being the CNT clusters. Nanoindentation testing on the matrix portion with dispersed CNTs indicated an increase in the elastic modulus by 19% and 39% and an increase in the yield strength by 17.5% and 27% by the addition of 5. wt.% and 10. wt.% CNTs respectively. Macro-scale compression tests indicated no improvement in the elastic modulus but an increases in the compressive yield strength by 27% and 77% respectively, by addition of 5. wt.% and 10. wt.% CNTs. Nanoscratch testing carried out on the Al-Si matrix with dispersed CNTs indicated a decrease in scratch volume by 34% and 71% by addition of 5. wt.% and 10. wt.% CNTs respectively. Macro-scale wear tests indicated a decrease in the wear volume by 68% in case of 5. wt.% CNT coatings but an increase in the wear volume by 15% for the 10. wt.% CNT coating. The differences in mechanical and wear properties at nano and macro scales are explained in terms of the bimodal CNT dispersion (well dispersed and clusters) in Al-Si matrix, CNT cluster size and fraction and carbide formation. � 2011 Elsevier B.V.