Applications In Various Industrial Fields Research Articles

Sintering Process Optimization for 3YSZ Ceramic 3D-Printed Objects Manufactured by Stereolithography.

A 3YSZ (3 mol% yttria-stabilized zirconia) ceramic green body with 50 vol% of ceramic content was 3D-printed by supportless stereolithography under optimal drying, debinding, and sintering conditions in order to achieve high strength and density. The viscosity and flowability of the ceramic nanocomposite resins were optimized by adjusting the amounts of non-reactive diluents. The ceramic 3D-printed objects have a high polymer content compared to ceramics samples manufactured by conventional manufacturing processes, and the attraction between layers is weak because of the layer-by-layer additive method. This causes problems such as layer separation and cracking due to internal stress generated when materials such as solvents and polymers are separated from the objects during the drying and debinding processes; therefore, the drying and debinding conditions of 3YSZ ceramic 3D-printed objects were optimized based on thermogravimetry–differential thermal analysis. The sintering conditions at various temperatures and times were analyzed using X-ray diffraction, SEM, and flexural strength analysis, and the body of the 3YSZ ceramic 3D-printed object that sintered at 1450 °C for 150 min had a relative density of 99.95% and flexural strength of 1008.5 MPa. This study widens the possibility of manufacturing ceramic 3D-printed objects with complex shapes, remarkable strength, and unique functionality, enabling their application in various industrial fields.

High strength impact welding of NiTi and stainless steel wires

This work demonstrates the use of a solid-state microwelding process to create very high strength welds between superelastic NiTi and themselves as well as stainless steel (SS) wires. Vaporizing foil actuator welding (VFAW) uses the pressure from a vaporized metal foil to impact weld the wires by driving them into one another. The small scale nature of this explosive-like process allows its use in factories. Advanced techniques were used to examine the structures and properties of the welds that were created. The NiTi/SS welds had the typical wavy interface of ideal impact welds, with no thermally induced defects such as chemical segregation near the interface or brittle intermetallic formation. These latter two are significant issues in traditional fusion based methods. Microhardness tests show that the NiTi/NiTi and NiTi/SS weld interfaces were locally strengthened compared to the softening of other welding processes. Lap shear tests show that NiTi/SS welds made by VFAW present much higher joint efficiency (near 100%) compared to less than 60% for other traditional joining technologies. Tensile cycling of both the NiTi/NiTi and the NiTi/SS welds shows similar stabilization of the pseudoelastic curves as the NiTi base metal. The irrecoverable strains of the NiTi/NiTi welds and NiTi/SS welds after cycling were comparable to that in the NiTi base metal. The unparalleled performance of these high-strength solid-state similar and dissimilar welds of nitinol is a solution to the increasing demands of applications in various industrial fields including the medical, aerospace and electronic sectors.

Investigation of metal mixing in laser keyhole welding of dissimilar metals

Laser keyhole welding of dissimilar metals has broad applications in various industrial fields. However, dissimilar metal mixing in the molten pool often causes the formation of detrimental intermetallic compounds that can undermine the performances of the dissimilar metal joints. In this study, the metal mixing process in laser keyhole welding of dissimilar metals is investigated with a combination of experimental and modeling approaches. The parametric experimental study is conducted to reveal the effects of laser power, welding speed, and heat input on the metal mixing in the fusion zone. Ex-situ energy-dispersive X-ray spectroscopy element mapping is used to characterize the metal mixing status in the fusion zone. To investigate the underlying physics of the welding process, a numerical model is developed to simulate the heat transfer, fluid flow, and metal mixing in the molten pool. It is found that the recoil pressure contributes to an upward flow that pushes copper to migrate from the bottom of the molten pool to the top. Meanwhile, the Marangoni force generates one backward flow and two side vortices that facilitate the metal mixing. An increase of laser power increases both the recoil pressure and the Marangoni stress, which drives more copper to migrate upward and mix with aluminum. An increase of welding speed reduces the molten pool lifetime, which reduces the metal mixing by the fluid flow. The investigation of dissimilar metal redistribution provides insights regarding the formation of intermetallic compounds in the joints, which is valuable for the design and optimization of the welding process in different industries.

Optical Angle Sensor Technology Based on the Optical Frequency Comb Laser

A mode-locked femtosecond laser, which is often referred to as the optical frequency comb, has increasing applications in various industrial fields, including production engineering, in the last two decades. Many efforts have been made so far to apply the mode-locked femtosecond laser to the absolute distance measurement. In recent years, a mode-locked femtosecond laser has increasing application in angle measurement, where the unique characteristics of the mode-locked femtosecond laser such as the stable optical frequencies, equally-spaced modes in frequency domain, and the ultra-short pulse trains with a high peak power are utilized to achieve precision and stable angle measurement. In this review article, some of the optical angle sensor techniques based on the mode-locked femtosecond laser are introduced. First, the angle scale comb, which can be generated by combining the dispersive characteristic of a scale grating and the discretized modes in a mode-locked femtosecond laser, is introduced. Some of the mode-locked femtosecond laser autocollimators, which have been realized by combining the concept of the angle scale comb with the laser autocollimation, are also explained. Angle measurement techniques based on the absolute distance measurements, lateral chromatic aberration, and second harmonic generation (SHG) are also introduced.

Novel hybrid robot and its processes for precision polishing of freeform surfaces

Freeform surfaces have important applications in various industrial fields. However, achieving a high level surface finish on freeform surfaces using polishing is always a challenging task. Hybrid robots are promising alternatives to conventional computer numerical control (CNC) machines and industrial robots for ultra-precision machining. Herein, we present a novel custom-built hybrid robot for freeform polishing. After the laboratory prototype was successfully developed, its automation for a specific freeform surface was a major obstacle preventing its application. This critical issue was addressed by presenting a process to deal with tedious robot programming. Random tool path planning was performed in the task space, and hybrid robot motion planning was conducted in the joint space. By integrating the process flows, a robot programming toolkit was developed to directly output the control program for a specific robot controller. An illustrative example with a freeform surface is provided to verify the functionality of the developed hybrid robot and the proposed control processes, and the corresponding experimental results verify their effectiveness.

Structural topology optimization with positive and negative Poisson’s ratio materials

PurposeNegative Poisson’s ratio (NPR) material has huge potential applications in various industrial fields. However, lower Young’s modulus due to the porous form limits its further applications. Based on the topology optimization technique, this paper aims to optimize the structure consisting two isotropic porous materials with positive Poisson’s ratio (PPR) and NPR and void.Design/methodology/approachUnder prescribed dual-volume fraction constraints, the structural compliance is taken as the objective. Young’s modulus and Poisson’s ratio are, respectively, interpolated and expressed with Lamé’s parameters for easier programming. Accordingly, the sensitivities can be derived through the chain rule. Several two- and three-dimensional illustrative examples are presented to demonstrate the capability and effectiveness of the proposed approach. The influences of Poisson’s ratios, volume fractions and Young’s moduli on the optimized results are investigated.FindingsFor NPR materials having unique load responses, the resulting topologies of PPR and NPR materials have distinct material distributions in comparison of the results from two PPR materials. Furthermore, it is observed that higher structural stiffness can be achieved from the hybrid of PPR and NPR materials than that obtained from the structures made of individual constituent materials.Originality/valueA topology optimization methodology is proposed to design structures composed of PPR and NPR materials.

Chemical reduction of methylene blue in the presence of nanocatalysts: a critical review

Abstract Methylene blue (MB) (3,7-bis (dimethylamino)-phenothiazin-5-ium chloride) is a harmful pollutant and has been long been known for its detrimental effects on human health. Over the recent years, many strategies including reduction, oxidation, biological and photochemical degradation have been reported for converting this harmful dye into commercially useful products. Among the aforementioned strategies, the nanocatalytic reduction of MB into its reduced counterpart, i.e. leucomethylene blue, is considered more preferable because it has been reported to have numerous applications in various industrial fields in the academic literature. The reduction of MB is the kinetically unfavorable reaction. Henceforth, various nanocatalytic systems utilizing different kinds of stabilization mediums have reportedly been used for speeding up this particular reaction. This article attempts to not only describe the fundamental properties of the reduction reaction of MB but also present the classification of the recently reported nanocatalytic assemblies on the basis of the utilized supporting medium. Various techniques used for the characterization of nanocatalytic systems reported for the reduction of MB have been summarized in this review. The thermodynamics, kinetics and mechanistic studies of this nanocatalytic reaction have also been narrated here. This critical review has been written comprehensively to abridge the recent research progress in the assemblage of nanocatalytic systems used for the reduction of MB and to propose some new ideas for further development in this area.

Cellulose nanocrystals from rice and oat husks and their application in aerogels for food packaging

This study describes the valorization of rice and oat husks by obtaining cellulose nanocrystals for the production of aerogels for food packaging applications. Commercial cellulose was used as a control sample. Nanocrystals from cellulose were obtained by enzymatic hydrolysis and mechanical treatment at high pressure. The morphology, particle size, functional groups, crystallinity, and thermal properties of the cellulose nanocrystals were analyzed. The morphology, functional groups, crystallinity, water absorption capability, and zeta potential of aerogels were also analyzed. Cellulose nanocrystals show different structural properties and crystallinity depending on the source of the cellulose. The average diameter of the nanocrystals varied from 16.0 to 28.8 nm. The aerogels prepared with cellulose nanocrystals showed a porous and uniform structure with a water absorption capacity between 264.2% and 402.8% at 25 °C. The aerogel of oat cellulose nanocrystals showed a larger pore size than that of eucalyptus cellulose nanocrystals, and this may have influenced the lowest water absorption capacity of the aerogels of eucalyptus cellulose nanocrystals. These results show that agroindustrial residues have promising applications in various industrial fields and could be used as aerogel absorbers of water in food packaging.

Fabrication and drag reduction of superhydrophobic surface on steel substrates

ABSTRACTSuperhydrophobic surfaces have attracted significant attention because of their potential applications in various industrial fields. In this study, a chemical process for fabricating ZnO nanowires on steel substrates is developed by using a chemical etching and hydrothermal synthesis method. The resultant surface exhibits binary micro/nanostructures. The modified sample exhibits a water contact angle of 164.9° and a sliding angle of 2.3° for a 5-μL water droplet. An experimental setup is created to measure the drag friction on the surface of the sample. Experimental results show that the drag reduction radio for the as-prepared sample is 40–50%.

Application of Flux Method to the Fabrication of Ba5Ta4O15, Sr5Ta4O15, Sr2Ta2O7, and BaTaO2N Polycrystalline Films on Ta Substrates

The fabrication of high-quality crystal layers has been an active research topic in the field of modern materials chemistry with potential applications in various industrial fields. In particular, photocatalytic water splitting, in which hydrogen and oxygen molecules are directly dissociated from water using solar energy and visible-light-driven photocatalysts, is a potentially economical and green process for producing clean and renewable hydrogen energy. In this work, films of three crystalline oxides, Ba5Ta4O15, Sr5Ta4O15, and Sr2Ta2O7, and one crystalline oxynitride, BaTaO2N, were grown using the flux-coating technique in molten chloride salts (flux) at 1000 °C. The film growth was studied under several different conditions. In particular, we investigated the effect of three different atmospheres (air, nitrogen, and ammonia) on the growth behavior and composition of the polycrystalline layers grown from a BaCl2·2H2O flux. We found that the growth atmospheres were important in forming idiomorphic cryst...

Synthesis and characterization of a furan-based self-healing polymer

The extensive researches of self-healing polymer have been carried out for various applications in industrial fields. In this research, bio-based self-healing polymer was prepared using a cross-linking mechanism between polybutylene furanoate (PBF) and bismaleimide (BM) by Diels-Alder reactions, and it was blended with bio-based polyurethane (BPU) to improve the liquidity, elasticity, and mechanical properties. These self-healing polymer and BPU blended elastomer were made with different ratios of PBF, BM, and BPU. PBF-BM polymer has 6:1, 8:1, and 10:1 of PBF: BM ratios. Each polymer and BPU constitutes self-healing elastomer with 1:1, 1:1.5, and 1:2 ratios. Properties and self-healing ability of these elastomers were investigated by thermal, mechanical, and morphological analysis. On average, 6:1 of PBF: BM ratio shows the outstanding self-healing efficiency and 1:2 of PBF-BM polymer: BPU ratio has the highest mechanical properties with maintain its self-healing ability. Overall results indicated that BPU is a good reinforcement of the furan-based self-healing polymer with improving the self-healing ability and eco-friendly performance. Open image in new window

Brazilian Dioscoreaceas starches

Determination of the characteristics of native starches is crucial in order to select their best application in various industrial fields. Thus, two different types of non-traditional native starches from the Dioscoreaceas species (Dioscorea sp. and Dioscorea piperifolia Humb. var. Wild) were studied regarding their thermal, structural and rheological properties. The results were contrasted with traditional commercial starch sources (potato, cassava and corn). From the thermogravimetric results (TG/DTG), D. piperifolia starch obtained the highest thermal stability of the samples, except for potato starch. Furthermore, using differential scanning calorimetry and viscoamylograph profiles (RVA), it was found that the Dioscoreaceas starches presented a higher onset (To) temperature and susceptibility to retrogradation. They also showed lower values in relation to relative crystallinity, which was calculated from their X-ray patterns and tendency to white (L*) colour. The shapes of the Discoreaceas starch granules were determined using electron microscopy; it was found that as the potato starch the Dioscoreaceas starches showed a wide range of particle size.

Frequency control of sol–gel composite films fabricated by stencil printing for nondestructive testing applications

Ultrasonic transducers made of sol–gel composites have been developed for nondestructive testing (NDT) applications in various industrial fields. Stencil printing of sol–gel composite films has been developed for the reduction of fabrication time and cost. However, it was necessary to develop low frequency (<10 MHz) ultrasonic transducers for inspecting industrial structures under severe high-temperature conditions, because high-frequency components suffer attenuation effect caused by high temperature. To realize this, increasing the thickness of Pb(Zr,Ti)O3 (PZT)/PZT films fabricated by stencil printing was attempted in this study. The samples were fabricated by single-layer stencil printing with a thick stencil mask and multilayer pure stencil printing with prespraying and postspraying. The film thicknesses were 150–185 µm, and the center frequencies of ultrasonic responses were 6.0–6.4 MHz. Throughout three thermal cycles of up to 370 K, the ultrasonic performance was stable, and the frequency characteristics were not markedly different from the beginning to the end of the test. Therefore, low-frequency ultrasonic transducers were successfully manufactured using a stencil-printing-based technique.

Evaluation of toxicity and biodegradability of choline chloride based deep eutectic solvents

Deep eutectic solvents (DESs) have been dramatically expanding in popularity as a new generation of environmentally friendly solvents with possible applications in various industrial fields, but their ecological footprint has not yet been thoroughly investigated. In the present study, three choline chloride-based DESs with glucose, glycerol and oxalic acid as hydrogen bond donors were evaluated for in vitro toxicity using fish and human cell line, phytotoxicity using wheat and biodegradability using wastewater microorganisms through closed bottle test. Obtained in vitro toxicity data on cell lines indicate that choline chloride: glucose and choline chloride:glycerol possess low cytotoxicity (EC50>10mM for both cell lines) while choline chloride:oxalic acid possess moderate cytotoxicity (EC50 value 1.64mM and 4.19mM for fish and human cell line, respectively). Results on phytotoxicity imply that tested DESs are non-toxic with seed germination EC50 values higher than 5000mgl−1. All tested DESs were classified as′readily biodegradable′ based on their high levels of mineralization (68–96%). These findings indicate that DESs have a green profile and a good prospect for a wider use in the field of green technologies.

Synthesis and characterization of polysulfone based on poly(ethylene terephthalate) waste

The recycling process of Poly(ethylene terephthalate) (PET) wastes is commercially important since it converts a waste material into a value‐added product and also helps to alleviate environmental pollution. PET waste was depolymerized in the presence of ethylene glycol and manganese acetate as a catalyst. Bis(hydroxyethyl terephthalate), (BHET) and other oligomers are predominately the glycolyzed products (GP). These GP products were reacted with a prepared dichlorodiphenylsulfone (DCDPS) in presence of dried potassium carbonate. Two polysulfones (A &amp;B) with different number average molecular weights, 1787 and 3162 g/mol. were obtained, respectively. The chemical structures of the resulting two polysulfones were elucidated using 1HNMR and characterized by the known conventional analysis techniques (e.g. FTIR, GPC, DSC, TGA…). The prepared polysulfone (B) disclosed higher thermal stability with respect to the initial reactants. The originality of this study was derived from the use of waste materials to yield a product that has acceptable high thermal stability which provide many beneficial applications in various industrial fields. POLYM. ENG. SCI., 55:1671–1678, 2015. © 2014 Society of Plastics Engineers

Synthesis of Amphiphilic Polymers Based on Fatty Acids and Glycerol‐Derived Monomers – A Study of Their Self‐Assembly in Water

Amphiphilic polymers are synthesized from various biobased compounds involving telomerization of glycerin‐derived acrylate monomers with mercaptan‐modified fatty acids. The effects of the chemical structure of the saturated or unsaturated hydrophobic block are investigated. Dynamic and static light scattering measurements, transmission electronic microscopy, and atomic force microscopy observations show that these copolymers are capable of self‐assembling into nanosized spherical particles in aqueous solution, made from compound micelles. The critical micellar concentration of these polymers is in the range of 10–60 mg L−1 determined by fluorescence. These biobased polymers could have applications in various industrial fields, such as cosmetics and agrochemicals. image

Screening and Xylanase Production by Streptomyces sp. Grown on Lignocellulosic Wastes

Xylanases have raised interest because of their potential applications in various industrial fields, including the pulp and paper industries, bioethanol production, and the feed industry. In bioethanol production from lignocellulosic compounds, xylanase can improve the hydrolysis of cellulose into fermentable sugars, since the xylan restricts the cellulases from acting efficiently. In this work, a new thermophilic Streptomyces sp. was selected for its ability to produce xylanase. Carbon source selection is an important factor in the production of hemicellulases. The highest activity was obtained when Streptomyces sp. I3 was grown in the presence of wheat bran. Xylanase activity was partially characterized concerning the effect of pH and temperature on activity and thermostability, and the effects of different metal ions were also tested. The pH and temperature profile showed optimal activity at pH 6.0/70 °C. Zymogram analysis showed multiple xylanases (39, 21, 18, and 17 kDa). Xylanases studied in this work are thermophilic, thermostable, and active in a wide pH range; they have potential to be used in the development of new processes of biotechnological interest.

Poly(ester‐amine) hyperbranched polymer as toughening and co‐curing agent for epoxy/clay nanocomposites

AbstractThe marriage between hardness and flexibility of epoxy resins (improved toughness) is a desired feature, which broads their application in various industrial fields, especially for high impact resistance purposes. Accordingly, this work aims to improve toughness properties of epoxy resin (Epon‐828)/Ancamine (curing agent) system using amino‐terminated hyperbranched poly(ester‐amine) [Poly(PEODA‐NPA)] (HP) as toughening and/or co‐curing agent, in presence of organo‐modified Montmorillonite clay (OMMT) as a reinforcing filler. HP was synthesized via Michael addition reaction of poly(ethylene glycol) diacrylate (PEODA) to N‐methyl‐1,3‐propanediamine (NPA). Chemical structure and molecular weight of HP were elucidated using infrared (FTIR) spectroscopy and gel permeation chromatography (GPC) techniques, respectively. Epoxy/OMMT nanocomposites toughened with HP (at different concentrations) showed remarkable improvement in their toughness without any adverse effect on the other physico‐mechanical properties. The optimum concentration of HP and OMMT was found to be 20 wt % and 1–3 wt% of the epoxy resin, respectively. The extent of exfoliation and dispersion of OMMT platelets within the epoxy cured films was assessed by X‐ray diffraction (XRD) and transmission electron microscopy (TEM) measurements. In addition, thermal gravimetric analyses (TGA‐DTA) of epoxy/OMMT nanocomposites toughened with HP showed a slight increase in their decomposition temperature, particularly at low OMMT loading. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers

Trends in Particle Formation of Bioactive Compounds Using Supercritical Fluids and Nanoemulsions

This review discusses the recent developments in the application of supercritical fluid technologies for the production of composites or encapsulates of bioactive compounds. Various supercritical particle formation technologies are briefly described, including processes in which the supercritical fluid acts as a solute, solvent, and antisolvent. The main features and mechanisms of antisolvent techniques that contribute to the understanding of the fundamentals of the Supercritical Fluid Extraction of Emulsions (SFEE) process are described. The published literature on SFEE, including the results and perspectives of its application in various industrial fields, are discussed. This article is the first comprehensive review specifically focused on the formation of particles using the SFEE technique.

Superhydrophobic surfaces fabricated by surface modification of alumina particles

The fabrication of superhydrophobic surfaces has attracted intense interest because of their widespread potential applications in various industrial fields. Recently, some attempts have been carried out to prepare superhydrophobic surfaces using metal oxide nanoparticles. In the present work, superhydrophobic surfaces were fabricated with low surface energy material on alumina particles with different sizes. It was found that particle size of alumina is an important factor in achieving stable superhydrophobic surface. It was possible to obtain alumina surface with water contact angle (WCA) of 156° and a sliding angle of <2°. Superhydrophobicity of the modified alumina is attributed to the combined effect of the micro-nanostructure and low surface energy of fatty acid on the surface. The surface morphology of the alumina powder and coatings was determined by FESEM. The stability of the coatings was assessed by conducting water immersion test. Effect of heat treatment on WCA of the coating was also studied. The transition of alumina from hydrophilic to superhydrophobic state was explained using Wenzel and Cassie models. The method is shown to have potential application for creating superhydrophobic surface on cotton fabrics.