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The effect of copper oxide doping (0.05–1 wt%) on the densification, microstructure evolution and mechanical characteristics of alumina toughened zirconia (ATZ: 80 wt% Y-TZP + 20 wt% Al2O3) ceramic composites was investigated. Green samples were pressureless sintered using a short hold time of 12 min at temperatures varying from 1250 °C to 1500 °C. The incorporation of up to 0.2 wt% copper oxide was beneficial in promoting densification at low sintering temperature and improving the mechanical properties of ATZ without affecting the tetragonal phase stability. It was found that 0.2 wt% copper oxide addition was most efficacious, and the samples could attain a relative density of approximately 92% at 1250 °C, approximately 97% dense at 1350 °C and above 99% dense at 1450–1500 °C. This approach was also accompanied by an improvement in the Vickers hardness (12.7 GPa) and fracture toughness (6.94 MPam1/2) when consolidated at 1450 °C/12 min. In comparison, the undoped composite exhibited relative densities of approximately 80% at 1250 °C, 87% at 1350 °C and approximately 97%–98% at 1450 °C-1500 °C. However, the study also found that higher dopant levels (0.5 wt% and 1 wt%) was not beneficial because the tetragonal zirconia phase was disrupted upon cooling from sintering, resulting in the monoclinic phase formation. In addition, low densification and poor mechanical properties were obtained.

In this work, nickel cobaltite (NiCo2O4) nanosheets with a porous structure were fabricated on nickel foam as a working electrode for supercapacitor applications. The nanosheets were fabricated by electrochemical deposition of nickel–cobalt hydroxide on the nickel foam substrate at ambient temperature in a three-electrode cell followed by annealing at 300 °C to transform the coating into a porous NiCo2O4 nanosheet. Field emission scanning electron microscopy and transmission electron microscopy revealed a three-dimensional mesoporous structure, which facilitates ion transport and electronic conduction for fast redox reactions. For one cycle, the NiCo2O4 electrodeposited nickel foam has a high specific capacitance (1734.9 F g−1) at a current density (CD) of 2 A g−1. The electrode capacitance decreased by only approximately 12.7% after 3500 cycles at a CD of 30 A g−1. Moreover, a solid-state asymmetric supercapacitor (ASC) was built utilising the NiCo2O4 nanosheets, carbon nanotubes, and a polyvinyl alcohol-potassium hydroxide gel as the anode, cathode, and solid-state electrolyte, respectively. The ASC displayed great electrochemical properties with a 42.25 W h kg−1 energy density at a power density of 298.79 W kg−1.

Hydroxyapatite/graphene oxide/platinum (HA/GO/Pt) nanocomposite was synthesized and electrodeposited on a pure zirconium substrate. The coated zirconium was annealed at 200, 300, 400, and 600°C in vacuum furnace in presence of argon gas. The structure and morphology of the coated samples were characterized. Biocompatibility and wear and corrosion resistances of specimens were examined. The result of corrosion tests shows that the graphene into HA/Pt composites significantly improves their corrosion resistance. The wear tests results of uncoated and coated samples before and after annealing show that coated samples annealed at 300°C had better wear resistance compared with uncoated and coated samples at other temperatures. Furthermore, the biocompatibility test shows that the coatings improved the cell attachment and proliferation compared to the pure zirconium substrate.

In the current study, hydrostatic tube cyclic expansion extrusion (HTCEE) was proposed as a new severe plastic deformation (SPD) method for producing relatively long and large ultrafine-grained (UFG) tubes. In this process, a moving mandrel placed inside the hollow tube sample and also using high fluid pressure are the cores of this technology. To investigate the applicability of the process, commercially pure copper tube was processed and mechanical properties and microstructure were examined. It was shown that the grain size was reduced to below 150 nm after the only a single pass of HTCEE from the initial value of 65 μm. The results demonstrated that both yield and ultimate strengths were increased to 270 MPa and 345 MPa after one pass of HTCEE from the initial value of 75 MPa and 207 MPa respectively while the elongation was reduced to 41% from 55%. It is realized that the remarkable increase in the strength is obtained with a very low ductility loss. Microhardness was also enhanced to about 133 Hv from the initial value of 59 HV after HTCEE process while exhibiting excellent hardness homogeneity. Reducing the total load, increasing the processable tube length and interestingly achieving simultaneous strength and ductility are important advantages of HTCEE. This method seems to be very interesting and very promising for the future industrial application.

In this study, a combination of reverse microemulsion and hydrothermal techniques were used to synthesize HA. A hydrothermal method was used to synthesize HA/TiO2/CNT nanocomposite powders. Cold and hot isostatic pressing techniques were used to fabricate tablet-shaped samples. To investigate the biocompatibility and tribo-mechanical properties of HA/TiO2 and HA/TiO2/CNTs, four samples were prepared with different percentages of CNTs, namely, HA/TiO2 (S0), HA/TiO2/CNT (S1.0), HA/TiO2/CNT (S2.0), and HA/TiO2/CNT (S3.0). The microstructure and morphology of the HA/TiO2/CNTs were characterized by transmission electron microscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction. Hardness test results show that S3.0 displayed the highest surface hardness (285 HV) compared to other samples. The wear rate of HA/TiO2/CNT with the highest CNT content showed a decrease compared with those of the other samples. The results from nanoindentation tests showed that Young’s modulus of the S3.0 sample was 58.1% greater than that of the S0 sample. Furthermore, the human MDA-MB-231 cell line demonstrated good binding to the surface of the samples in the in-vitro biocompatibility evaluation of the HA/TiO2/CNT composites.

In this study, a combination of reverse microemulsion and hydrothermal techniques were used to synthesize HA. A hydrothermal method was used to synthesize HA/TiO2/CNT nanocomposite powders. Cold and hot isostatic pressing techniques were used to fabricate tablet-shaped samples. To investigate the biocompatibility and tribo-mechanical properties of HA/TiO2 and HA/TiO2/CNTs, four samples were prepared with different percentages of CNTs, namely, HA/TiO2 (S0), HA/TiO2/CNT (S1.0), HA/TiO2/CNT (S2.0), and HA/TiO2/CNT (S3.0). The microstructure and morphology of the HA/TiO2/CNTs were characterized by transmission electron microscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction. Hardness test results show that S3.0 displayed the highest surface hardness (285 HV) compared to other samples. The wear rate of HA/TiO2/CNT with the highest CNT content showed a decrease compared with those of the other samples. The results from nanoindentation tests showed that Young’s modulus of the S3.0 sample was 58.1% greater than that of the S0 sample. Furthermore, the human MDA-MB-231 cell line demonstrated good binding to the surface of the samples in the in-vitro biocompatibility evaluation of the HA/TiO2/CNT composites.

The goal of this study was to examine the tribomechanical properties of hydroxyapatite (HA)/ZnO and HA/ZnO/CNT composite ceramics (carbon nanotubes; with different ratios 0.5 wt%, 1.0 wt%, and 1.5 wt%). The composites were synthesized using the hydrothermal method in an autoclave. The structure and morphology of the composites were analyzed using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), energy-dispersive X-ray analysis (EDX) and transmission electron microscope (TEM). The consolidation process was performed by sintering the compounds at 1150 C under an argon gas atmosphere. The effects of ZnO and CNT on the mechanical properties and wear resistance of the HA-nanoparticle-based ceramic composites were investigated using a Vickers hardness tester, nanoindentation, and reciprocating wear tester equipment. The nanohardness and elastic modulus of the sintered samples increased and the friction coefficient of the sintered samples decreased as the fraction of CNTs increased compared to the pure HA and HA/ZnO compounds. Furthermore, the wear loss of HA/ZnO/CNT composites decreased with the increase in the CNT content compared to the HA and HA/ZnO samples. We acknowledge Hanyang University's financial support through the Young Faculty Forum Fund (number 201600000001555 ). Also, some parts of the research were supported by the Fusion Research Program for Green Technologies through the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT & Future Planning (No. NRF-2015R1A2A2A11027580 ). Scopus

The present study describes the synthesis of HA/rGO/Pd nanocomposite thin film coating on stainless steel 304 using electrodeposition method. In this regard, an attempt is made to investigate the corrosion and biocompatibility behavior of HA/rGO/Pd nanocomposite thin film. Biocompatibility tests were carried out on uncoated, HA-coated, HA/rGO-coated, and HA/rGO/Pd coated SST 304 substrates using the human cell line MDA-MB-231 possessing a green fluorescent protein as a reporter for living cells. The tests revealed that the biocompatibility of the SST 304 surface permitted the most improved cell spreading and proliferation with HA/rGO/Pd nanocomposite coating. Corrosion testing carried out in the synthetic medium confirmed that the corrosion resistance of HA/rGO/Pd coated SST 304 was significantly higher than the uncoated, HA-coated, and HA/rGO-coated SST 304. Furthermore, the HA/rGO/Pd coated SST 304 substrates were annealed at different temperatures including 200, 300, 400, and 600 °C and the corrosion and wear behaviors of annealed samples were investigated. We acknowledge Hanyang University's financial support through the Young Faculty Forum Fund (number 201600000001555 ). Scopus

Layered double hydroxides (LDH) as active electrode materials have become the focus of research in energy storage applications. The manufacturing of excellent electrochemical performance of the LDH electrode is still a challenge. In this paper, the production of CoAl-LDH@Ni(OH)2 is carried out in two steps, including hydrothermal and electrodeposition techniques. The prominent features of this electrode material are shown in the structural and morphological aspects, and the electrochemical properties are investigated by improving the conductivity and cycle stability. The core of this experimental study is to investigate the properties of the materials by depositing different amounts of nickel hydroxide and changing the loading of the active materials. The experimental results show that the specific capacity is 1810.5F·g−1 at 2 A/g current density and the cycle stability remained at 76% at 30 A g−1 for 3000 cycles. Moreover, a solid-state asymmetric supercapacitor with CoAl-LDH@Ni(OH)2 as the positive electrode and multi-walled carbon nanotube coated on the nickel foam as the negative electrode delivers high energy density (16.72 Wh kg−1 at the power density of 350.01 W kg−1). This study indicates the advantages of the design and synthesis of layered double hydroxides, a composite with excellent electrochemical properties that has potential applications in energy storage.

The electrochemical nitrogen reduction reaction (NRR) over single-atom catalysts (SACs) anchored on Mo vacancies of Mo 2CO 2 MXene nanosheets under ambient conditions suffers from poor selectivity, low yield, and low Faradaic efficiency because of their sluggish kinetics and the competing hydrogen evolution reaction. Herein, density functional theory calculations are performed to improve the understanding of the selectivity and yielding of ammonia through NRR over various isolated SACs, that is, from Sc to Au, anchored on the Mo vacancy of the Mo 2CO 2 MXene nanosheet (denoted as MO 2CO 2-M SA). The potential-determining step of the NRR shows that eight candidates (i.e., Y, Zr, Nb, Hf, Ta, W, Re, and Os) confined on the defective Mo 2CO 2 layer could promote the electroreduction from N 2 to NH 3. Among these, Mo 2CO 2-Y SA presented the lowest reported reaction Presents the lowest reported reaction energy barrier (0.08 eV) through the distal pathway and high selectivity to NRR compared with the previously synthesized Mo 2CO 2-Ru SA with a relatively high energy barrier (0.65 eV) and poor selectivity. In addition, the formation energy of Mo 2CO 2-Y SA is more negative than that of the Mo 2CO 2-Ru SA catalyst, suggesting that the experimental preparation of the Mo 2CO 2-Y SA catalyst is highly feasible. This work lays a solid foundation for improving the rational design of MXene-based systems as efficient electrocatalysts for the synthesis of ammonia.

This study examines the influence of thin layer coatings of CrAlTiN and CrN/NbN, deposited via physical vapor, on the biocompatibility, mechanical, tribological, and corrosion properties of stainless steel 304. The microstructure and morphology of the thin CrAlTiN and CrN/NbN layers were characterized by scanning electron microscopy (SEM), EDX, and X-ray diffraction. The pin on disc wear test was performed on bare and metal-nitride coated SST 304 under a 15 N load at 60 rpm and showed that the wear rates of the thin CrAlTiN and CrN/NbN film coatings were lower than the bare substrate wear ratio. The coefficients of friction (COFs) attained were 0.64, 0.5, and 0.55 for the bare substrate, CrN/NbN coating, and CrAlTiN coating, respectively. Nano indentation tests were also performed on CrAlTiN-coated and CrN/NbN-coated SST 304. The nanohardnesses and Young's moduli of the coated substrates were 28 GPa and 390 GPa (CrN/NbN-coated) and 33 GPa and 450 GPa (CrA1TiN-coated), respectively. For comparison, the nanohardness and Young's modulus of the uncoated substrate were 4.8 GPa and 185 GPa, respectively. Corrosion tests were conducted, and the behaviors of the bare and metal nitride-deposited substrates were studied in CaCl2 for seven days. The corrosion Tafel test results showed that the metal-nitride coatings offer proper corrosion resistance and can protect the substrate against penetration of CaCl2 electrolyte. The CrN/NbN-coated substrates showed better corrosion resistance compared to the CrAlTiN-coated ones. In evaluating the biocompatibility of the CrAlTiN and CrN/NbN coatings, the human cell line MDA-MB-231 was found to attach and proliferate well on the surfaces of the two coatings.

Flower-like NiO (F-NiO) and ball-flower-like NiO/Ag (BF-NiO–Ag) were synthesized in the presence of L-glutamine as an electrochemical sensor for lead(II) detection. The structure and morphology of the F-NiO and BF-NiO–Ag were studied by X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM). Energy dispersive X-ray confirmed the presence of Ag on the surface of the BF-NiO–Ag. The results confirmed that Ag+ was reduced to Ag metal in the presence of L-glutamine. The FESEM images confirmed the effect of L-glutamine and Ag on the morphology and the available surface area. Electrochemical impedance spectroscopy results confirmed the effect of the loaded Ag on the conductivity of the BF-NiO–Ag. Differential pulse voltammetry results gave a linear working range for the concentration of lead(II) between 1.5 and 10 nM with a LOD of 0.06 nM (S/N = 3). The sensitivity of this linear segment is 0.3 μA nM−1. The average recoveries, recovery percentage and relative standard deviation obtained from four determinations (n = 4) confirmed the feasibility of the proposed method for the quantitative detection of certain concentration ranges of Pb2+.

Developments in the aquaculture industry have increased the production of shellfish. However, the lack of a proper recycling method for discarded shells is resulting in marine environmental pollution. For the sustainable management of shellfish byproducts, pulverized oyster and scallop shell powder were used as major raw materials in cement-clinker production, replacing 100 wt% of limestone. The characteristics of the synthesized cement clinkers and hydrated cement pastes were analyzed via scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM-EDS), strength tests, thermogravimetric analysis, isothermal calorimetry, and X-ray diffraction (XRD) with Rietveld refinement. The analysis results for the synthesized oyster-shell cement (OSC) and scallop-shell cement (SSC) were compared with those of limestone-based cement and commercial ordinary Portland cement (OPC). Anhydrous cement-clinker phases such as C3S, C2S, C3A, and C4AF were successfully formed in all the synthesized clinkers, similar to the OPC. Additionally, the OSC and SSC yielded the same main hydration products (C–S–H and portlandite) as the OPC, and the morphology of the hydration products in the OSC and SSC was very similar to that in the OPC. The results indicate that oyster and scallop shells are suitable substitutes for limestone as a raw material for cement.

Highly oriented arrays of TiO2–Nb2O5–Al2O3 mixed oxide nanotubes were fabricated via physical vapor deposition (PVD) to sputter a niobium film on Ti–6Al–7Nb (Ti67) and subsequent electrochemical anodization in ethylene glycol/ammonium fluoride/ionized water (5 wt%) electrolyte. Parametric optimization for higher adhesion strength and microhardness was conducted using Taguchi experimental design methodology. The highest adhesion strength and microhardness of the as-deposited Nb film was achieved at 350 W DC power, 20 sccm argon flow rate and a 90 V bias voltage. The microstructural features were found to depend on the anodization time and subsequent thermal treatment. The anodization of Nb/Ti67 for 4 h resulted in a homogeneous ordering of the mixed oxide nanotubes. Upon annealing at a low heating and cooling rate of 1 °C at 440 °C for 30 min in an atmospheric furnace, a highly ordered nanotube array contained a mixture of TiO2, Al2O3 and Nb2O5 phases, wherein the composition of the oxide nanotubes was strongly influenced by the chemistry of the phases present in Ti67. The results of in vitro bioactivity indicated that the crystallized mixed oxide nanotubes could induce a quick apatite formation after immersion in simulated body fluid (SBF). The above findings may contribute to the development of novel nanostructured materials for metallic orthopedic implants.

Ti-6Al-4V is widely used for arthroprostheses, particularly in metal-on-metal (MoM) hip joints. In spite of the suitable wear and corrosion resistance, metallic wear particles and metal ion release occur on a large timescale. In addition, metal ion levels in patients' blood and urine often reportedly increase according to clinical data. Neurological disease, inflammatory response and cell necrosis can potentially develop consequently. The aim of this research is to fabricate a thin, hard film coating on Ti-6Al-4V in order to improve mechanical properties, such as the adhesion strength, surface hardness and surface roughness of Ti-6Al-4V, which should lead to substrate biocompatibility mitigation through reduced debris production, ion release and cytotoxicity. Physical vapor deposition (PVD) magnetron sputtering treatment is applied to obtain an enriched tantalum oxide (Ta-O) thin film coating. In this regard, pure tantalum (Ta) as a biocompatible metal is deposited atop Ti-6Al-4V substrate in the presence of oxygen gas and different parameter conditions, including substrate temperature, argon flow rate, oxygen flow rate and DC power. The results indicate that the surface hardness and surface roughness of the Ta-O coated substrate significantly improve compared to uncoated substrate. The adhesion strength between Ta-O thin film and substrate is examined using a micro scratch tester, and maximum adhesion of 2500 mN is achieved.

Various severe plastic deformation (SPD) processes have been developed to produce metal tubes with ultrafine grain (UFG) structures. However, most techniques are complex and limited to working with components that are short in length to avoid tube failure during SPD processes. To overcome such limitations, this study suggests the use of an equal channel angular pressing (ECAP) process for the production of tubular aluminum alloy 6061. To mitigate plastic instability effects such as tube buckling and fracture during processing, hydraulic oil was used to fill the tube cavity. Finite element analysis (FEA) using Abaqus/Explicit 6.13 was carried out to examine the feasibility of the proposed method and deformation mechanism during ECAP. A series of investigations were performed, including: microstructure analysis, torsion, and micro hardness tests to evaluate the effects of tube-ECAP treatment. Test results indicated that the resultant 60% reduction in grain size led to significant mechanical property improvements including yield shear strength, ultimate shear strength, and microhardness. However, the ductility of the material decreased slightly for the ECAP-treated samples. To resolve this issue, a heat treatment process using the T6 method was performed, leading to a notable ductility enhancement in addition to further improvements in shear strength and microhardness. the Ministry of Higher Education, Malaysia, with high impact research (HIR) grant numbers HIR-MOHE-16001-D000001. Human Resources Program in Energy Technology of the Korea Institute of Energy Technology Evaluation and Planning (KETEP), granted financial resource from the Ministry of Trade, Industry & Energy, Republic of Korea (No. 20154030200900).

An unbalanced physical vapor deposition (PVD) magnetron sputtering technique was used to deposit a titanium/titanium nitride/hydroxyapatite (Ti/TiN/HA) multilayer coating on Ti–6Al–4V. The Taguchi optimization method with an orthogonal array of L9 was utilized to determine the optimal conditions of coating for better surface integrity. The effects of the temperature, DC bias voltage, nitrogen flow rate, and DC power on the adhesion strength, coefficient of friction, surface hardness, and surface roughness were investigated. In achieving the optimized coating parameters, the signal to noise (S/N) response analysis method was implemented. Confirmation tests were carried out to demonstrate the improvement using the best combination of parameters obtained from the optimization process. The surface hardness of the Ti/TiN coated and uncoated specimens was enhanced by 14% and 48%, respectively. The adhesion strength of the coating to the substrate, coefficient of friction, and surface roughness were improved by 5.1%, 43%, and 10.52%, respectively. Finally, hydroxyapatite was successfully deposited atop Ti/TiN coated Ti–6Al–4V using a PVD sputtering technique to improve the biocompatibility of the substrate. The presence of Ti/TiN interfacial thin layers between the HA layer and substrate enhanced the adhesion strength of the HA coating on the substrate by 44.57% compared to the HA-coated substrate without the interfacial layers.

In this study, Titanium alloy (Ti–6Al–4V) substrate was coated with 4 μm tantalum oxide (Ta–O) ceramic layers using physical vapor deposition magnetron sputtering (PVDMS). The coated sample surfaces were heat treated at 300, 400 and 500 °C in a box furnace to enhance the adhesion strength. Field Emission Scanning Electron Microscopy (FESEM) together with energy dispersive X-ray spectroscopy (EDX), X-ray diffraction analysis (XRD) and Vickers microhardness testing was used to distinguish the Ta–O coatings in terms of morphology, surface elements, structure and surface hardness, and to compare untreated and hardened sample conditions. The effect of heat treatment on adhesion was tested with scratch test equipment. The coating thin film adhesion strength improved from 713 to 1907 mN throughout the thermal surface treatment duration. The effect of thermal treatment on surface hardness was examined, and evidently, the surface hardness increased from 446.24 to 535.5 HV on account of the surface treatment at 500 °C.

Joining cylindrical and bar-shaped components manufactured from dissimilar materials is frequently required in various industrial applications. The current study focuses on developing equal channel angular pressing (ECAP) as a severe plastic deformation process for solid state joining of tubular aluminium alloy 6061 components and SAE 1018 steel rods. The influence of using a 0.1 mm thick 60Ag–30Cu–10Sn interlayer in addition to annealing at 220, 320, 420 and 520 °C for 60 min is investigated as well. Finite element analysis (FEA) is performed in order to evaluate the deformation behaviour of the workpieces during the ECAP joining process. XRD and EDX analyses as well as nanoindentation and shear tests are carried out to evaluate the joints' characteristics. The FEA outcomes show remarkable accumulation of equivalent plastic strain with relatively low strain inhomogeneity. Moreover, the experimental results indicate that with increasing annealing temperature, joint strength exhibits improvement as well. It is also revealed that the application of an interlayer at any specific annealing temperature leads to achieving higher shear strength values. According to the results, shear strength of up to 32 MPa is feasible by having an interlayer and with subsequent annealing at 520 °C. Keywords: Dissimilar metal joining, Equal channel angular pressing, Aluminium alloy 6061, Steel SAE 1018, Ag–Cu–Sn Interlayer, Annealing

In this study, the microstructural features and corrosion behavior of self-organized TiO 2 nanotubular arrays on Ti–6Al–7Nb (Ti67) produced from different electrolytes, namely glycerol (G) and ethylene glycol (EG) were investigated. From the XRD data, the TiO 2 characteristic peaks were absent after the anodization, but TiO 2 crystallization occurred during annealing at 600 °C for 2 h, and consequently, led to the formation of highly crystalline TiO 2 (anatase). The corrosion resistance of the anodized samples was higher than the substrate after 30 min of immersion in phosphate buffer saline (PBS) solution. In fact, the surface modification of Ti67 with a nanotubular TiO 2 layer was effective in enhancing the passive layer resistance and reducing the corrosion current density ( I corr ) compared to the substrate. Due to the decrease in I corr , the corrosion rate decreased and reached a minimum of 6.38×10 −2 mm y −1 for the nanotubes (anodized sample in G) annealed at 600 °C for 2 h. These results show that the corrosion behavior of the nanotubular structure was affected by the type of electrolyte and subsequent thermal treatment.

Nanosize Zr-doped carbonated chlorapatite (n-ZCCA) was developed as a novel bioceramic by a ball milling process. Results showed that the microstructural characteristics of the product were affected significantly by the degree of substitution and subsequent annealing at 800 °C for 1 h. In the absence of zirconium, mechanical activation for 3 h resulted in the formation of carbonated hydroxyapatite (CHA). With the addition of various amounts of zirconium, nanosize Zr-doped carbonated chlorhydroxyapatite (n-ZCCHA) and n-ZCCA were formed as a result of progressive mechanochemical reactions. From the HR-TEM images, the preferential substitution of Zr onto the ac or bc chlorapatite crystal facets (rich in calcium ions) led to a c-axis oriented crystal growth of crystalline nanoneedles with an average size of around 40–60 nm in length and 10–20 nm in width. UM High Impact Research Grant UM-MOHE UM.C/625/1/HIR/MOHE/ENG/44 (Regenerative Biomechanics of Human Body) from the Ministry of Higher Education Malaysia and University of Malaya Grant number RP021C-13AET

The present study describes the anodic growth of TiO2 nanotube thin layer on stainless steel 304 in ethylene glycol/water/ammonium fluoride electrolyte. In this regard, pure titanium was coated on stainless steel 304 substrates by a physical vapor deposition magnetron sputtering (PVDMS) technique. The adhesion strength of the coating to the substrate was investigated. TiO2 nanotubes were generated on the top of the Ti coated substrates by means of anodization technique at a 25 V potential and times of 20, 40, and 60 min in an ammonium fluoride electrolyte solution. The anodized Ti-coated samples were heat-treated at 280 °C, 430 °C and 620 °C in a N2 gas furnace to attain diverse phases. The mechanical properties of TiO2 nanotube arrays coated substrate were explored by a nanoindentation apparatus. The results illustrate that the Young׳s modulus and surface hardness of TiO2 nanotube-coated substrates are increased with increasing annealing temperatures (280 °C, 430 °C and 620 °C). The scratch test results show that heat treatment at 430 °C and 620 °C can improve the adhesion strength of Ti/TiO2 coated samples by up to 2860 and 3140 mN, respectively. UMRG Grant, NC2/RC/261/1/1/RP021C-13AET from the University of Malaya, Malaysia

In the present study, a self-organized nanotube TiO2 layer on Ti–6Al–7Nb was fabricated. The influence of acidic electrolytes including glycerol (G) and ethylene glycol (EG) on the anodization, microstructural features and surface wettability was explored. The phase compositions and morphological characteristics were characterized by X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM), respectively. According to the results, due to the intrinsic amorphous feature of ceramic oxide, the characteristic TiO2 peaks were not detected in the XRD profiles. After annealing in normal atmosphere at 600 °C for 2 h, TiO2 crystallized and consequently, nanotubular TiO2 arrays containing anatase and rutile phases formed. From a microstructural point of view, the average length and diameter of the nanotube array ranged from 2.23 to 4.22 μm and 160 to 170 nm, respectively. Besides, the type of acidic electrolyte and subsequent annealing noticeably affected the surface wettability of the products. University of Malaya, grant Nos.: UM TNC2/RC/261/1/1/RP021C-13AET and HIR UM.C/HIR/MOHE/ENG/27

In this study, the mechanical properties, including surface hardness, tensile strength, fatigue, and fretting fatigue behavior of AA 6063 processed by equal channel angular pressing as the most efficient severe shear plastic deformation (SPD) technique, were investigated. Following the SPD process, samples were subjected to heat treatment (HT), hard anodizing (HA), and a combination of HT and HA. Rotating–bending fretting fatigue tests were performed to explore the samples’ response to the fretting condition. From the experimental fatigue and fretting fatigue tests, it was apparent that the SPD treatment had a positive effect on enhancing the fatigue and fretting fatigue lives of the samples at low and high-cyclic loads compared with the HT technique by 78 and 67 pct, and 131 and 154 pct respectively. The results also indicate that the SPD + HT technique significantly increased the fatigue and fretting fatigue lives of the samples at high and low cycles by 15.56 and 8.33 pct, and 14.4 and 5.1 pct respectively, compared with the SPD method. HA of AA6063 increased the fatigue and fretting fatigue lives of SPD + HT-processed samples at low cycle by 15.5 and 18.4 pct respectively; however, at high cycle, HA had reverse effects, whereby the fatigue and fretting fatigue lives of SPD + HT-processed samples decreased by 16.7 and 30 pct, respectively. Ministry of Higher Education, Malaysia, with high impact research (HIR) Grant Numbers HIRMOHE- 16001-D000001; and UM.TNC2/RC/261/1/1/RP021-13AET (UMRG), RP021C-13AET

Binary (Ti/TiN and Cr/CrN) and ternary (TiCr/TiCrN) thin films were deposited on AL7075-T6 by magnetron sputtering. Microhardness, adhesion strength and pin-on-plate wear tests were performed to investigate coating performance. Field emission scanning electron microscope integrated with focused ion beam milling and energy dispersive X-ray spectroscopy was employed for microstructural and chemical characterizations. The tribo-mechanical test results revealed that Cr/CrN promoted up to 5 times greater hardness, Ti/TiN showed the highest scratch resistance and up to 8 times reduced wear, while TiCr/TiCrN favored the least friction and surface roughness. Furthermore, the excellent tribological properties of coatings correlated with their superior adhesion to AL7075-T6.

Carbonated fluorapatite–titania composite nanopowders were successfully synthesized by a facile room-temperature mechanochemical process. Mixtures of calcium carbonate, phosphorous pentoxide and calcium fluoride with different amounts of titania (0, 3, 6, and 9 wt%) were milled using a high-energy planetary ball mill for 10 h. Results showed that a gradual transformation occurred during the mechanical activation. In the absence of titania, nanosized B-type carbonated fluorapatite with crystallite size of 6973 nm was formed. In the presence of 3–9 wt% titania, mechanochemical reaction caused the formation of carbonated fluorapatite–titania composite nanopowders. The crystallite size declined drastically and reached 1271 nm when the titania content was increased to 9 wt%. In contrast, the lattice strain and volume fraction of grain boundary increased notably from 0.004570.0002 to 0.008470.0004 and from 470.21% to 2171.07%, respectively, while the titania content rose from 0 to 9 wt%. From the data obtained, the unit cell volume of carbonated fluorapatite was influenced strongly by the titania content, whereby the sharp increase in unit cell volume from 524.42 to 530.40 A 3 was due to the increase of the titania content from 0 to 9 wt%, respectively. Microscopic observations indicated that the product had a cluster-like structure with an average particle size of about 75 nm. & 2014 Elsevier Ltd and Techna Group S.r.l. All rights reserved.

Due to the increasing demand on ethanol gas sensors for several applications such as automation transportation or environmental monitoring the need for more sensitive and reliable sensors with an on spot response time is required Indirect sensing invasive bulky time initializing and low reliability in strip tests are some drawbacks of ethanol sensing measurements at the present To overcome these leakages there is focused on modelling and simulation of a proposed ethanol sensor based on surface acoustic wave technique using finite element method

Battery-type electrodes of three-dimensional (3D) hierarchical cobalt hydroxide carbonate arrays on Ni foam were fabricated using a hydrothermal method for use in supercapacitors. X-ray diffraction analysis, scanning electron microscopy, and transmission electron microscopy were used to characterize their structures and morphologies. The cobalt hydroxide carbonate synthesized with 10 h reaction time showed the highest specific capacitance (1381 F g1 at a current density of 2 A g1) and excellent cycling stability (92% capacitance retention after 5000 cycles). Moreover, its capacitance increased by 33% at 2 A g1 and by 10% at 20 A g1 after 5000 charge-discharge cycles. This cobalt hydroxide carbonate composite is a promising candidate for electrochemical energy-related applications. This work was performed at the Thin Film Coating Laboratory, Engineering Center, Hanyang University. The work was supported fnancially by Hanyang University, Young Faculty Forum and by a grant (16TBIP-C111710-01) from the Technology Innovation Program funded by the Ministry of Land, Infrastructure and Transport of the Korean Government. Scopus

Chromium nitride (CrN) coating has emerged as a new alternative in machining applications. CrN has good thermal stability, low deposition temperature, and excellent wear and corrosion resistance. However, no precise informa- tion exists yet regarding the ideal coating parameter condi- tions that lead to higher surface integrity. For this reason, an optimization study is desired—a study on the parameters of CrN coating on aerospace Al7075-T6 alloy using physical vapor deposition magnetron sputtering. The present research work investigates the effects of temperature as well as nitro- gen flow rate and DC power on coated samples' surface hardness, adhesion, surface roughness, and microstructure. To carry out the investigation, the Taguchi optimization meth- od with L16 (3 4 ) orthogonal array was applied. However, to obtain optimum parameters for superior surface integrity, signal/noise (S/N) response analysis method was employed. Finally, confirmation tests with the best parameter combina- tions attained in the optimization process were carried out to demonstrate the progress made. Ultimately, surface hardness of coated Al7075-T6 was enhanced by 15.33 %, adhesion by 24.3 %, and surface roughness by 7.22 %.

Aircraft engines, fuselage, automobile parts, and energy saving strategies in general have promoted the interest and research in the field of lightweight materials, typically on alloys based on aluminum. Aluminum alloy itself does not have suitable wear resistance; therefore, it is necessary to enhance surface properties for practical applications, particularly when aluminum is in contact with other parts. Fretting fatigue phenomenon occurs when two surfaces are in contact with each other and one or both parts are subjected to cyclic load. Fretting drastically decreases the fatigue life of materials. Therefore, investigating the fretting fatigue life of materials is an important subject. Applying surface modification methods is anticipated to be a supreme solution to gradually decreasing fretting damage. In this paper, the authors would like to review methods employed so far to diminish the effect of fretting on the fatigue life of Al7075-T6 alloy. The methods include deep rolling, shot peening, laser shock peening, and thin film hard coatings. The surface coatings techniques are comprising physical vapor deposition (PVD), hard anodizing, ion-beam-enhanced deposition (IBED), and nitriding.

Temper rolling is a fundamental process applied in steel industries to improve the tensile properties of sheet steels by eliminating discontinuous yield behaviours. Virtually evaluating the effects of temper rolling mechanics on eliminating discontinuity is still a crucial problem due to a lack of comprehensive constitutive material models that correctly describe this elimination mechanism. In this paper, modified anisotropic constitutive model based on Hill's 48 yield criterion are used for finite element analysis (FEA) of the temper rolling process. This model was applied for four different sheet thicknesses and the FEA results are compared with experimental results obtained directly from the production line. According to the results, the customized model that implements the modified anisotropic yielding criterion efficiently describes the tensile behaviour of low carbon steels following temper rolling, and it more accurately predicts the lower and upper yielding points than the isotropic yielding criterion. This model thus assists to facilitate the simulation, optimization and prediction of mechanical properties following temper rolling.

In recent years, nano-reinforcing technologies for cementitious materials have attracted considerable interest as a viable solution for compensating the poor cracking resistance of these materials. In this study, for the first time, titanium nanotubes (TNTs) were incorporated in cement pastes and their effect on the mechanical properties, microstructure, and early-age hydration kinetics was investigated. Experimental results showed that both compressive (~12%) and flexural strength (~23%) were enhanced with the addition of 0.5 wt.% of TNTs relative to plain cement paste at 28 days of curing. Moreover, it was found that, while TNTs accelerated the hydration kinetics of the pure cement clinker phase (C3S) in the early age of the reaction (within 24 h), there was no significant effect from adding TNTs on the hydration of ordinary Portland cement. TNTs appeared to compress the microstructure by filling the cement paste pore of sizes ranging from 10 to 100 nm. Furthermore, it could be clearly observed that the TNTs bridged the microcracks of cement paste. These results suggested that TNTs could be a great potential candidate since nano-reinforcing agents complement the shortcomings of cementitious materials.

Fretting fatigue is a phenomenon which occurs when two parts are contacted to each other and one of those parts or both are subjected to cyclic load. Fretting decreases fatigue life of materials drastically by half or even more. Therefore, investigation of fretting fatigue life of materials is an important subject. Fretting fatigue tests are usually per- formedusing universal hydraulic testing devices. Inthiswork, a rotating bending apparatus for fretting fatigue test is intro- duced in which the cyclic load is provided by an adjustable eccentric load. The apparatus called RBFF machine which is the abbreviation of rotating bending fretting fatigue. The eccentric load is measured by load cell. The coefficient of friction and fretting load are measured by foil strain gauges using a Wheatstone bridge configuration. The performance of the machine is verified with doing a comparison between fatigue lives of a number of AL7075-T6 alloy samples on a ShimadzurotatingbendingfatiguetestingmachineandRBFF. The results shows very close assent between the operations of the two testing rigs. The main privileges of RBFF are its simplicity with respect to universal devices, cheapness and, coefficient offriction(betweenpadsand specimen) evaluation duringthetest.TheRBFFalsohasthecapabilityofbeingused for any other soft and hard metals. It can be advanced further for high and low temperature.

Aerospace applications and energy saving strate- gies in general raised the interest and study in the field of lightweight materials, especially on aluminum alloys. Alumi- num alloy itself does not have suitable wear resistance. There- fore, improvements of surface properties are required in practical applications, especially surface hardness when alu- minum is in contact with other parts. In this work, first Al7075-T6 was coated using hard anodizing technique in different parameters condition and the surfaces hardness of hard anodizing-coated specimens were measured us- ing microhardness machine. Second, fretting fatigue life of AL7075-T6 was investigated for both uncoated and hard anodized specimens at the highest surface hardness obtained. Third, a fuzzy logic model was established to investigate the effect of hard anodizing parameters, volt- age, temperature, solution concentration, and time on the anodized AL7075-T6. Four fuzzy membership func- tions are allocated to be connected with each input of the model. The results achieved via fuzzy logic model were verified and compared with the experimental re- sult. The result demonstrated settlement between the fuzzy model and experimental results with 95.032 % accuracy. The hardness of hard anodizing-coated speci- mens was increased up to 360 HV, while the hardness of uncoated specimens was 170 HV. The result shows that hard anodizing improved the fretting fatigue life of AL7075-T6 alloy 44 % in low-cycle fatigue.

Aerospace applications and energy-saving strate- gies in general raised the interest and study in the field of lightweight materials, especially on aluminum alloys. Alu- minum alloy itself does not have appropriate wear resis- tance. Therefore, improvement of surface properties is required in practical applications, especially when alumi- num is in contact with other parts. In this work, first titanium nitride (TiN) is coated on aerospace Al7075-T6 in different conditions using PVD magnetron sputtering technique, and the surface hardness of TiN-coated specimens is measured using a micro hardness machine. Second, a fuzzy logic model is offered to predict the surface hardness of TiN coating on AL7075-T6 with respect to changes in input process parameters, direct current (DC) power, DC bias voltage, and nitrogen flow rate. Four membership functions are allocated to be connected with each input of the model. The predicted results achieved via fuzzy logic model are compared to the experimental result. The result demonstrat- ed settlement between the fuzzy model and experimental results with 96.142 % accuracy. The hardness of titanium nitride-coated specimens is increased significantly up to 720 HV, while the hardness of uncoated specimens was 170 HV.

Combinations of three simple techniques were utilized to gradually form zirconia nanoneedles from zirconium nanograins. First, a physical vapor deposition magnetron sputtering technique was used to deposit pure zirconium nanograins on top of a substrate. Second, an anodic oxidation was applied to fabricate zirconia nanotubular arrays. Finally, heat treatment was used at different annealing temperatures in order to change the structure and morphology from nanotubes to nanowires and subsequently to nanoneedles in the presence of argon gas. The size of the pure zirconium nanograins was estimated to be approximately 200–300 nm. ZrO2 nanotubular arrays with diameters of 70–120 nm were obtained. Both tetragonal and monoclinic ZrO2 were observed after annealing at 450 °C and 650 °C. Only a few tetragonal peaks appeared at 850 °C, while monoclinic ZrO2 was obtained at 900 °C and 950 °C. In assessing the biocompatibility of the ZrO2 surface, the human cell line MDA-MB-231 was found to attach and proliferate well on surfaces annealed at 850 °C and 450 °C; however, the amorphous ZrO2 surface, which was not heat treated, did not permit extensive cell growth, presumably due to remaining fluoride.

Metallic materials are extensively used in engineering structures and fatigue failure is one of the most common failure modes of metal structures. Fatigue phenomena occur when a material is subjected to fluctuating stresses and strains, which lead to failure due to damage accumulation. Different methods, including the Palmgren-Miner linear damage rule- (LDR-) based, multiaxial and variable amplitude loading, stochastic-based, energy-based, and continuum damage mechanics methods, forecast fatigue life. This paper reviews fatigue life prediction techniques for metallic materials. An ideal fatigue life prediction model should include the main features of those already established methods, and its implementation in simulation systems could help engineers and scientists in different applications. In conclusion, LDR-based, multiaxial and variable amplitude loading, stochastic-based, continuum damage mechanics, and energy-based methods are easy, realistic, microstructure dependent, well timed, and damage connected, respectively, for the ideal prediction model.

An optimization study on the parameters of titanium nitride coating on aerospace Al7075-T6 alloy, using magnetron sputtering technique is presented. The effects of the temperature, DC bias voltage, rate of nitrogen, and DC power on the surface hardness, adhesion, surface roughness, and microstructure of the coated samples are investigated. Taguchi optimization method is used with the orthogonal array of L16 (44). However, to obtain the most optimum parameters for the best surface hardness, adhesion, and surface roughness, the signal to noise (S/N) response analysis method is implemented. Finally, the confirmation tests were carried out to show the improvement using the best parameters combination obtained from the optimization process. The improvement of 14 % in surface hardness, 4.15 % in adhesion, and 9.43 % in surface roughness are achieved.

Surface plasmon resonance (SPR) is a medical diagnosis technique with high sensitivity and specificity. In this research, a new method based on SPR is proposed for rapid, 10-minute detection of the anti-dengue virus in human serum samples. This novel technique, known as rapid immunoglobulin M (IgM)-based dengue diagnostic test, can be utilized quickly and easily at the point of care. Four dengue virus serotypes were used as ligands on a biochip. According to the results, a serum volume of only 1 μl from a dengue patient (as a minimized volume) is required to indicate SPR angle variation to determine the ratio of each dengue serotype in samples with 83–93% sensitivity and 100% specificity.

DAVOUD MASHHADI JAFARLOU, Researcher, and NOOR AZIZI BIN MARDI, Senior Lecturer, are with the Department of Mechanical Engineering, Faculty of Engineering, University of Malaya, 50603 Kuala Lumpur, Malaysia, and also with the Centre of Advanced Manufacturing & Material Processing (AMMP), 50603 Kuala Lumpur, Malaysia. ERFAN ZALNEZHAD, Assistant Professor, is with the Department of Mechanical Convergence Engineering, Hanyang University, 222 Wangsimni-ro, Seongdong-gu, 133-791 Seoul, Korea. Contact e-mail: erfan@hanyang.ac.kr ABDELMAGID SALEM HAMOUDA, Professor, is with the Mechanical and Industrial Engineering Department, College of Engineering, Qatar University, P.O. Box 2713, Doha, Qatar. GHADER FARAJI, Assistant Professor, is with the School of Mechanical Engineering, College of Engineering, University of Tehran, 11155-4563 Tehran, Iran. MOHSEN ABDELNAEIM HASSAN MOHAMED, Associate Professor, is with the Department of Mechanical Engineering, Faculty of Engineering, University of Malaya and Centre of Advanced Manufacturing & Material Processing (AMMP), and also with the Department of Mechanical Engineering, Faculty of Engineering, Assiut University, Assiut 71516, Egypt. The online version of the original article can be found under doi:10.1007/s11661-015-2806-7. Article published online April 7, 2015