In the present study, kinetics and thermal behavior of the Inconel 738 alloy were studied by the low-temperature thermoreactive aluminizing process, which was carried out at 625 degrees C, 650 degrees C, 675 degrees C, and 700 degrees C for 2, 4, and 6 h. The coating layer formed on the surface of the Inconel 738 alloy substrate was characterized by X-ray diffraction (XRD) analysis, scanning electron microscopy (SEM), and EDS-attached SEM. XRD analysis revealed that the dominant compounds formed during the thermoreactive aluminizing process are Al3Ni2, AlNi, and AlCr2. SEM examinations showed that the aluminized layer formed on the surface of the Inconel 738 alloy has a compact nature with different contrast due to the presence of various elements. Depending on the process temperature and duration, the aluminide layer thickness and hardness values were found to be in the range of 6-68 mu m and 390-1200 HV, respectively. A kinetic model employing the mass balance equation was considered in the multiphased aluminized layer formed on the Inconel 738 alloy. In this model, the diffusivity of aluminum (Al) in the Ni matrix was accounted for under a transient diffusion regime, and the distribution of Al concentration within the aluminized layer was linear. It enabled us to assess the activation energy for Al diffusion in the aluminized layer on the Inconel 738 alloy. In addition, the sample coated at 650 degrees C for 4 h was exposed to oxidation at 700 degrees C, 800 degrees C, and 1000 degrees C. It was found that the activation energy of oxidation was 296 kJ mol -1 for the coated sample, whereas it was 113 kJ mol -1 for the bare alloy.

The present study reports on silicide coating on Ti6Al4 V alloy by pack siliconizing technique. This siliconizing surface process was carried out in medium consisting of mixture of silicon, alumina, and ammonium chloride at 1000, 1100, and 1200 degrees C for 2, 4, 6, and 10 h in an argon atmosphere. The presences of outer TiSi2 and the inner TiSi and Ti5Si3 silicide compounds were verified by X-ray anlaysis technique and scanning electron microscope (SEM) equipped with an energy dispersive spectroscope. Depending on process time and temperature, the layer thickness of silicides formed on the surface of substrate materials changes between 9 and 47 mu m leading to a diffusion controlled process. The hardness of silicides compounds measured by means of Vickers indenter ranged from 940 to 1647 HV. For silicon diffusion in the silicide compounds an activation energy of 216.27 kJ mol-1 was determined using the integral method. TG-DTA results revealed that silicide coating is stable up to 850 degrees C.

In the present study, a hip joint cup/liner material has been developed using ultra high molecular weight polyethylene (UHMWPE) matrix material which is reinforced by hydroxyapatite (HAp) particles with the 0.5, 1, 2, and 4 wt.% using mechanical activation followed by hot pressing. The main goal of the present study is to increase the life cycle of UHMWPE joint material, increasing wear resistance with HAp. The homogeneous distribution of HAp particles was confirmed by scanning electron microscopy (SEM) and the presence of characteristic peaks of UHMWPE and HAp was detected by x-ray diffraction (XRD) analysis. It was concluded that the hardness value of the UHMWPE-4 wt.% HAp composite increased by 118%, the wear rate decreased by 81%, and the coefficient of friction decreased by 65% compared to pure UHMWPE. The presence of an apatite structure was detected in the in vitro experiments performed after the UHMWPE-4 wt.% composite was kept in simulated body fluid (SBF) solution at 37 degrees C for 8 days. Differential scanning calorimetry (DSC) analysis revealed an increase of 7.91% in the melting temperature and 159% in the crystallinity value of pure UHMWPE with HAp reinforcement. All results revealed that UHMWPE-HAp composites demonstrate suitability for application as cup and/or liner components in hip joint prosthetic systems.

The study focused on the synthesis of hydrogels using polyvinyl alcohol (PVA) and polyethylene glycol (PEG) as primary components and containing various proportions of carbon nanotubes (CNTs). The findings revealed that the hydrogels containing CNTs exhibited an increase in hydrophobic properties, with the average contact angle increasing from 14.77

Elektromanyetik radyasyon koruyucu malzeme geliştirmek amacıyla UHMWPE (Ultra High Molecular Weight Polyethylene) yüzeyleri akımsız kaplama yöntemiyle Nikel ile kaplanmış ve üzerine Ag nanopartikül sentezi yapılmıştır. Nikel kaplama ve nanogümüş katkısının tespiti ve kompozit matris içerisinde dağılımını gözlemlemek amacıyla SEM-EDS analizleri gerçekleştirilmiştir. UHMWPE içerisindeki hakim fazlar Ni ve NanoAg, XRD analizi ile tespit edilmiştir. Elde edilen tozlar 180 °C’de 15 dk süresince sıcak preslemeye tabi tutularak Ni kaplı ve nanogümüş katkılı UHMWPE kompozitleri elde edilmiştir. Ni kaplı ve NanoAg katkılı UHMWPE partiküllerine, ekranlama değerlerinin belirlenmesi için EMI-SE (Elektromagnetic Interference Shielding Effectiveness) ölçümü yapılmıştır. Elde edilen ekranlama değerleri Ni kaplama için 56 dB, NanoAg katkısı için 34 dB olarak belirlenmiştir. Hem X hem de Ku-bandı için sonuçlar karşılaştırıldıklarında Ni kaplı UHMWPE partikülleri üzerine NanoAg sentezinin ekranlama değerlerini nasıl etkilediği gözlemlenmiştir.

Problems such as hydrophilic properties of hydrogels, limited encapsulation of hydrophilic drugs, and unintended release amounts damage normal tissues and lead to overdose or repeated doses. This study investigates the development and characterization of drug carrier hydrogel formulations that can protect normal tissues. In this study, polyvinyl alcohol (PVA) hydrogel was synthesized by adding melamine (M) and tannic acid (TA) at different weight ratios to limit the hydrophilic properties of the hydrogel. In the analysis of the synthesized hydrogel, the efficiency of drug encapsulation increased from 60 to 90

In the present study, the surface of Ti6Al4V alloy was coated with UHMWPE-HAp composite film by dip coating for hip joint material. Ti6Al4V alloy surfaces were firstly roughened by anodic oxidation to provide adhesion of the polymer coating on it. Scanning Electron Microscope (SEM) and Field Emission Scanning Electron Microscope (FE-SEM) results showed that the UHMWPE-HAp composite film was coated homogenously on the substrate and HAp particles were well bonded to the matrix. Functional groups and bond types of the composite coatings were detected by Fourier-transform Infrared Spectroscopy (FTIR). The melting temperature T m and the enthalpy of fusion (Delta H-f) of the UHMWPE and UHMWPE-HAp composite coatings were measured by differential scanning calorimetry (DSC). The crystallinities were calculated as 24.5% for pure UHMWPE and increased to 54.2% by addition of 1 wt%HAp particles into the UHMWPE matrix. Dry sliding wear properties of coatings against alumina ball were tested by a ball-on-disc tribometer in linear mode. Wear results revealed that UHMWPE-HAp composite coating on anodic oxidized Ti6Al4V alloy has an ultra-low friction coefficient of 0.06 compared to the friction coefficient of anodic oxidized Ti6AlV4 alloy at of 0.8 and with a favorable wear resistance 84% higher than oxide coated ones. This newly developed composite coating material shows potential use for artificial hip joint replacements.

In this work, we offer an easy approach to develop a novel injectable, pH sensitive and in situ smart drug delivery system for use in cancer treatments. The developed hydrogels containing nitrogen doped carbon quantum dots (NCQD), doxorubicin (Dox) and hydroxyapatite (HA) were obtained by in situ self-crosslinking. Characterization of the synthesized nanomaterials, interactions between NCQD/Dox/HA hydrogel structure were carried out by TEM, FESEM, EDS, FTIR, XPS, XRD, Zeta potential, DLS, UV-Vis, SEM, gelation time, injectability and DIST measurements. In addition, antibacterial evaluation which was performed against Staphylococcus aureus realized that HA compound significantly increased the antibacterial activity of the hybrid hydrogel. The anticancer drug release to the tumor cell microenvironment with a pH of 5.5 was found to be higher compared to the release in the normal physiological range of pH 6.5 and 7.4. MTT and live/dead assays were also performed using L929 fibroblastic cell lines to investigate the cytotoxic behavior of NCQDs, and NCQDs/Dox/HA hydrogels. Furthermore, the NCQDs/Dox/HA hydrogel could transport Dox within a MCF-7 cancerous cell at specifically acidic pH. Additionally, imaging of cell line was observed using NCQDs and their use in imaging applications and multicolor features in the living cell system were evaluated. The overall study showed that in situ formed NCQDs/ Dox/HA hydrogel represented a novel and multifunctional smart injectable controlled-release drug delivery system with great potential, which may be considered as an attractive minimal invasive smart material for future intelligent delivery of chemotherapeutic drug and disease therapy applications.

Nickel-plated ultrahigh molecular weight polyethylene (UHMWPE) samples were prepared by an electroless coating method followed by hot pressing. The concentration of Ni in the composites was varied between 3.98 and 10.88 in volume percentage. XRD results revealed that Ni coating was successfully realized on the surface of UHWMPE particles confirmed by SEM–EDS. Ni thickness on the UHMWPE particles has thickness of 2 μm and there was also self-precipitated Ni plates as well as additive Ni particles according to SEM. Hardness values of Ni-coated UHMWPE–Ni composites increased 30% with increasing Ni content. The EMI-SE of the composite increased from 49 up to 70 dB by increasing Ni content for both X and Ku-band with respect to Ni concentration. Our samples, performed very high shielding within X band and also Ku band compared to most of other reports in the open literature, can be suitable for high-performance requirements especially in aerospace applications.

The present study reports on iron (Fe) silicides produced on 31CrMoV9 steel by using the pack-cementation method. Pack siliconizing was carried out using metallic silicon (Si), ammonium chloride (NH4Cl) and alumina (Al2O3) at 1000–1100–1200°C and with varying deposition times of 3–5–7 h in an open atmospheric furnace. The morphology and structure of silicide layers were analyzed by optical microscopy and scanning electron microscopy–energy-dispersive X-ray spectroscopy. It was observed that there was good bonding between the matrix and silicide layers, which were smooth, homogenous and dense and had no remarkable porosity. Dominant phases of Fe3Si, as well as some FeSi, were detected by X-ray diffraction analysis. The layer thickness was measured from the surface to the matrix and changed from 40 to 800 μm, which increased with increasing process time and temperature. The observed silicide layer growth obtained at 1200°C was much higher than those at 1000 and 1100°C. The hardness profile showed that there was no diffusion zone. The matrix hardness is 225 HVN, while the hardness of the coating layer rose to 1021 HVN with the process time and temperature. The activation energy for the growth of the siliconizing layer was determined as 292 (kJ/mol)/K according to the kinetic study. It can be claimed that the optimum siliconizing layer was obtained up to 1100°C for 5 h due to the formation of a layer with smoother morphology, less porosities and oxygen impurities and adequate thickness.

ZnWO4(sanmartinite) powders were produced by mechanochemical synthesis using ZnO and WO(3)at 700 rpm for 25, 50 and 100 min, respectively. SEM indicated the ratio of sub-micron-sized ZnWO(4)particles was raised, and particle size distribution was homogenized by increasing process time. XRD results revealed the formation of sanmartinite after 100 min milling with 700 rpm. Raman Spectroscopy confirmed the XRD results except detection of WO(3)and ZnO traces. The surface area of the samples was ranged between 3.65 and 4.05 m(2)/g. Optical band-gap energies of the samples increased from 2.68 to 2.86 eV with further process time. Under the visible light, the highest photocatalytic efficiency for degradation of malachite green dyes was observed in sample ball milled at 700 rpm for 25 min. Samples ball milled at 700 rpm for 100 min have lower photocatalytic activity compared to samples ball milled at 700 rpm 25 and 50 min. The efficiency of photocatalytic activities changed from 45 to 83% after 120-min photocatalysis process. It is possible to claim that ZnWO(4)powders are promising photocatalyst.

In this study, HAp reinforcement into UHMWPE matrix having 1.0 % wt. mass and its effects on microstructural and mechanical properties of the UHMWPE composites were investigated. UHMWPE composites reinforced with 0.5, 1 and 2.0 wt. % nano HAp powders, respectively were successfully produced by solution and gelation method. SEM studies showed that HAp nano particles were homogenously distributed into UHMWPE matrix and good cross-linked with the matrix. SEM-map EDS analysis confirmed SEM. FTIR results revealed that HAp incorporation into matrix was conducted and crystallization of UHMWPE increased by increment in amount of HAp results in deepening crystallization peaks at nearby 500 and 1500 cm-1. DSC results, which is useful technique to determine the variation of melting point and crystallization ratio of UHMWPE composites, indicated that there was no remarkable change in melting points of composites, while crystallinity of the samples generally showed slight increase by increasing amount of nano HAp particles. The tensile test instrument was utilized to determine elastic modulus of the samples and their elastic modulus were raised from 1050 to 1900 MPa with higher HAp reinforcement. It can be concluded that UHMWPE-2 % wt. HAp composites have promising results by being paired with crystallinity and elastic modulus.

ABSTRACT In this study, Ultra‐high‐molecular‐weight polyethylene (UHMWPE) in 0.5 wt % concentration—0.5, 1, and 2 wt % nanosized and micron‐sized TiO 2 composites were produced via gelation/crystallization method in decalin + antioxidant solution at 150 °C for 45 min by using magnetic stirrer. The gel composites were cooled in an aluminum tray embedded in iced water under ambient conditions and dried in an oven at 130 °C for 90 min to remove any residual trace of decalin and to strengthen the UHWMPE matrix. Scanning electron microscopy–EDS images indicate that TiO 2 particles were integrated well with the polymer matrix. differential scanning calorimetry studies revealed that the crystallinity of pure UHMWPE was calculated as 56% and an increase of 13.32% for micron sized and 19.25% for nano sized TiO 2 . Crystalline and amorphous phases of UHMWPE–TiO 2 composites confirmed by Raman are in good agreement with the literature. The elastic modulus of test materials ranged from 610 to 791 MPa for micron sized and raised from 675 to 1085 for nano sized reinforcing agents. Ultimate tensile stress increased about 35% for micron sized and 60% for nano sized weight 1% TiO 2 reinforced composites. Biomineralization tests (performed in stimulated body fluid, at 37 °C and 6.5 pH during 1 month) have shown that produced composites are compatible as acetabular liner replacement for hipjoints due to no accumulation (Ca, P, Na, etc.) on UHMWPE–TiO 2 composites. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136 , 47402.

In this study, it was aimed to investigate the effect of subzero heat treatment duration as well as tempering on some microstructural and mechanical properties of commercial Calmax cold work tool steels. Firstly, five steel samples were austenitized at 960C following by quenching at 170°C and one of them was remained as just quenched for reference. After quenching, one of other four samples was tempered at 525°C for 30 min, while two of four samples were exposed to subzero heat treatment in liquid nitrogen medium having -197°C for 15 and 60 min, respectively and last sample was subjected to subzero heat treatment for 60 min. and then tempered at 525°C for 30 min. The hardness of quenched, quenched and tempered, quenched and subzero heat treated and quenched, subzero heat treated and tempered test materials were determined as 755, 527, 807, 829, 616 HV(0.1), respectively. The microstructure of test samples investigated by Scanning electron microscopy was mainly consisting of martensite and small amount of alloy carbides after heat treatments. On the other hand, martensitic zones in the microstructure increased by increasing deep cryogenic (sub-zero) duration and seconder alloy carbides became more visible by applying of tempering. XRD analysis revealed that remained austenite was considerably eliminated by only sub-zero heat treatment, but effectiveness of the process increased with additive tempering by observing of the ferritic and austenitic peaks. The presence of carbides (Cr23C6, Cr7C3) was also verified by XRD and SEM-dot EDS analysis. The retained amount of austenite in the microstructures of samples determined by quantitative analysis of austenitic and ferritic iron peaks was calculated as 9.8% for quenced sample, 2.5 % for quenced and tempered, 1.9% for only sub-zero heat treated for 15 min., 1.4% for only sub-zero heat treated for 60 min. and 0.6% for quenced and sub-zero heat treated for 60 min. following by tempering at 525 °C, in volume, respectively. The results of the study indicated that both sub-zero heat treatment and tempering decreases the amount of retained austenite. Sub-zero heat treatment increases the hardness of test materials, while tempering decreases the hardness of samples. Additionaly, it was found that applying of subzero heat treatment for only 15 min. is enough for eliminating the amount of remained austenite to desirable level.

In this study a novel composite containing fMWCNT and Ag, Zn or Co doped hydroxyapatite (HA) and undoped HA successfully synthesized using biomimetic process and coated on the chemically silane functionalized Ti via facile surface functionalization and deposition approach through the covalent immobilization. In this approach, the properties of Ti pretreated with NaOH and APTES were examined before the composite coating. Functional groups with oxygen were created on the MWCNT surface by acidic treatment. The synthesized powders were characterized using SEM, XRD, EDS, TGA, FTIR, Raman. Surface energies were decreased from 46.03 mN/m (Ti) to 43,79 mN/m (Ti-/fMWCNT/Ag, Zn or Co doped HA). The contact angles of APTES, fMWCNT and undoped or doped HA containing Ti surfaces increased from 40.03 ± 1.2 to 49.05 ± 1.6°. The bond strengths between the coatings and Ti substrates were measured using an adhesive strength test which indicates that the crosslinking process increased the adhesion strength (from 14.6 ± 0.9 to 19.8 ± 1.2 MPa). The results indicated that the Ag+, Zn2+ or Co2+ added in prepared SBF medium have been located in the HA lattice structure at rate of 1.06, 1.86 and 1.78 at.%, respectively. The biocompatibility of the synthesized composites was evaluated using MTT assays in vitro and no negative effect was observed on cell viability. This work shows that the fMWCNT/Ag, Zn or Co doped HA coating promise for the potential implementation in biomaterial coating fields.

Nano-sized hydroxyapatite (HA) particles were synthesized by sol-gel through water and ethanol based mediums of phosphoric acid (H 3 PO 4 ) and calcium hydroxide (Ca(OH) 2 ) at pH = 11 for different calcination time (1 h, 2 h, 4 h). The effects of calcination time and solution on the crystallinity, morphology and impurity phases of the HA nanoparticles were examined via Fourier Transform Infrared (FTIR), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDS) and X-ray Diffraction (XRD). It was found that crystallite size and the fraction crystallinity of the synthesized samples increased with calcination time. According to solution medium, only CaO as impurity was appeared in the water-based solvent, CaO and Ca(OH) 2 impurities were appeared in the ethanol-based solvent. The lowest crystallinity was 0.92 and the highest crystallinity was 1.73 respectively, depending on the process parameters. The Ca/P atomic ratio closest to the bone was found as 1.5178. As a result, the employed water-based sol-gel processes for 1 h calcination time was determined as the optimum for the formation of nano-sized HA powders using calcium hydroxide and phosphoric acid.

The measured capacitance and conductance–voltage (C&G/ω–V) data between 1 and 200 kHz of Al/(BSA-doped-PANI)/p-InP structure were examined to uncover real and imaginary components of complex permittivity (ε* = ε′ − jε″), loss tangent (tanδ), complex electric modulus (M* = M′ + jM″), and electrical conductivity (σ). It was uncovered that dielectric constant (ε′), dielectric loss (ε″), tanδ, real and imaginary components (M′ and M″) show a big dispersive behavior at low frequencies due to the oriental and the interfacial polarizations, as well as the surface states (Nss) and the BSA doped-PANI interlayer. Such behavior in ε′, ε″, and tanδ, behavior with frequency was also explained by Maxwell–Wagner relaxation. The values of σ are almost constant at lower-intermediate frequencies, but they start increase at high frequencies which are corresponding to the dc and ac conductivity, respectively. The values of M′ and M″ are lower in the low frequency zone and they become increase with increasing frequency at accumulation region due to the short-range charge carriers mobility. Ultimately, dielectric parameters and electric modulus alteration with frequency is the consequence of surface states and relaxation phenomena.

In this study, we describe new collagen/functionalized multiwalled carbon nanotube/chitosan/hydroxyapatite (Col/f-MWCNT/CS/HA) composite scaffolds which were fabricated by freezing (-40 °C at 0.9 °C/min) and lyophilization (48 h, 0 °C and 200 mtorr). The compressive stresses (from 523 to 1112 kPa), swelling (from 513.9 ± 27 to 481.05 ± 25%), porosity (from 98 ± 0.15 to 95.7 ± 0.1%), contact angle (from 87.8 to 76.7°) properties examined before and after biomineralization for comparison 3D porous Col, CS, Col/f-MWCNT and Col/f-MWCNT/CS scaffolds. Biomineralization was performed by biomimetic method in concentrated SBF (10 × SBF, at 37 °C and 6.5 pH). XRD, SEM, EDS, FTIR, TGA, Optical microscopy and BET results showed that compared to Col, CS and Col/f-MWCNT scaffolds, Col/f-MWCNT/CS scaffolds had higher in vitro bioactivity, large surface area (11.746 m2/g) and a good pore volume (0.026 cc/g), interconnected porous microstructure (with 20-350 μm pore size) and incorporates the advantageous properties of both Col, f-MWCNT, CS and HA. Finally, the methyl thiazolyl tetrazolium (MTT) assay was performed to evaluate scaffolds cytotoxicity which showed that Col/f-MWCNT/CS scaffolds have the best biocompatibility.

In this study, Polyaniline emeraldine base (PANI-EB) and benzene sulphonic acid (BSA) doped polyaniline (PANI-BSA), HCl doped Polyaniline (PANI-HCl), and BSA and HCl doped Polyaniline (PANI-HCl-BSA) polymers were synthesized. Synthesizing was accomplished by chemical oxidative polymerization of aniline in acidic environment at room temperature (20 degrees C). Aniline to ammonium peroxydisulfate (APS) ratio is 1:1.25, and aniline to acid ratio is 1:1 for PANI-HCl and 1:0.5:0.5 for PANI-HCl-BSA. PANI-EB was obtained by de-doping PANI-HCl with NH3. In order to determine the type and degree of doping, electrical conductivity, band gap values, physical and structural properties were investigated. Structural properties of the doped and undoped PANI samples were determined using Fourier transform infrared spectroscopy (FT-IR), Ultraviolet visible spectroscopy (UV-vis) and (SEM), and electrical was is determined using four-point probe method. PANI-BSA, PANI-HCl-BSA and PANI-HCl doped polymers conductivity were measured as 1.39, 0.77 and 0.54 S.cm(-1) respectively. Band gap values calculated by Kubelka-Munk equation are 2.35, 2.38, 2.40 eV respectively. The conductivity of the insulating PANI-EB polymer was measured as 2.9.10(-4) S.cm(-1) and its energy band gap was found as 3.06 eV. PANI-BSA, showed higher solubility in dimethylsulphoxide (DMSO) compared to PANI-HCl which is more commonly known. With its high conductivity, high resolution and low band gap, PANI-BSA has proven to be a suitable interface for electronic devices. (C) 2018 Karabuk University. Publishing services by Elsevier B.V.