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The objective of the study was to evaluate the effect of processing parameters such as pressing and sintering time on microstructural characteristics including porosity and microstructure of some iron-based powder metallurgy (PM) materials. The powders used in this study are prealloyed iron-based powders. The particle size of the powders is ranging from 45 to 150 ?m. Following mixing the powders with zinc stearate 1% for 30 minutes, the studied powders were single pressed in a die at a pressure of 600 MPa. Zn-stea...

Based on a previous research, a thermal bimorph actuator was used for a development of a micromirror element. An existing technological process for the manufacturing of IC was used as base for micromirror. An analysis of the available construction materials was made, on the basis of which a choice was made for silicon as the main material for the micromirror, aluminum as the reflective coating and the first element of the bimorph beam, and silicon dioxide as the second element of the bimorph beam. ? polysilicon he...

Total (specular+diffusive) reflection of nanostructured Si layers prepared by metal assisted chemical etching (MACE) of crystalline silicon (c-Si) wafers is investigated. The thickness of nanostructured Si layers is varied from 0.3 to 100 ?m by increasing the MACE time. The time dependence of silicon nanostructured layers thickness on the etching time was found to be logarithmic. Spectra of the total reflection were measured in optical range from 0.2 to 2 ?m. Depending on the thickness of sample, it was observed a...

Anthocyanins are known as safe colouring materials, although they have poor stability which often limits their use. To solve this drawback, mesoporous silica with high surface area was used as an adsorbent for anthocyanins. This study proposes the enhancement of the anthocyanins photo stability by their incorporation into the pores of mesoporous silica containing various metal ions. The anthocyanins were adsorbed on the silica by pouring a highly-concentrated anthocyanins solution to the dried silica. Improved sta...

Polyoxometalates (POMs) are discrete, anionic metal-oxygen clusters of early d bloc metal ions in high oxidation status (e.g. MoVI, WVI) with a very large structural and compositional variety, leading to interest in many different areas (catalysts in homogeneous and heterogeneous catalytic oxidation of organic compounds or biochemical reactions, activity in enzymatic redox processes, as antitumoral, antibacterial and antiviral treatments etc). An important subclass of POMs is the {XMo6O24} structure type, Anderson...

Phosphate removal from wastewater is necessary at sewage treatment plant before discharging into the natural streams due to many reasons especially to preserve phosphate and to avoid eutrophication. Magnetite nanoparticles stabilized on ZSM-5 zeolites were used to adsorb, remove and recover phosphate from said wastewater. Three samples namely, magnetite, magnetite@ZSM5 and ZSM-5 were used for batch adsorption experiments. Results indicated the highest phosphate removal efficiency for magnetite@ZSM-5 material. Magn...

Wear-resistant composite coatings reinforced with Al2O3 nanoparticles (20nm) obtained by electroless technique are analysed in this paper. The structure and surface morphology of coatings with alumina nanoparticles embedded in the Ni-P alloy for different quantities of alumina in the nickel-plating bath (3g/L, 5g/L and 8g/L) are presented. Nanocomposite electroless coatings are characterized by optical microscopy, XRD and SEM. Microstructure of the composites has revealed uniform distribution of Al2O3 nanoparticle...

1050 aluminum alloys are used in the conventional engineering applications where the increased corrosion resistance is required (e.g. automotive industries or construction, containers). Improving the corrosion resistance of 1050 aluminum alloy is an extensively studied topic. Different methods are applied to improve the corrosion resistance of 1050 aluminum alloy as: painting, waxing, zinc-chromate priming, thin layer of pure aluminum, coatings with a liquid protective solution, conversion coatings and also anodic...

In this article, the authors have analysed the influence of ultrasound, used in the quenching from the intercritical range (? + ?), on the volume fraction of martensite in the microstructure of a dual-phase steel with 0.087% C and 0.511% Mn. The ultrasonic oscillations, applied to the medium in which the quenching takes place, under the action of pressure and cavitation phenomenon, destroys and prevents the formation of vapor and gas films, thereby ensuring a more prolonged contact between the workpiece and the co...

In this work, the organic silicon-based composites were obtained from resorcinol, formaldehyde, TEOS, N-(b-aminoethyl)-g-aminopropyl-trimethoxysilane (AEAPTES) as initial materials for carbon-silica composites producing. The solvent was acetone, those molar ratio to resorcinol varied in following: sample S1 ? 1:11; sample S2 ? 1:14 and sample S3 ? 1:19. Gels were prepared by one-stage method. The silica-organic gels were supper-critical dried. It was shown that the heat treatment of silica-organic gels allows gett...

It is well known that the use of aluminium and its alloys in transports, aeronautics or in the car industry as a vehicle downweighting material, also decreases fuel and energy consumption and lowers greenhouse gas emissions. In our study, an innovative thermomechanical processing technology for obtaining flat ultra-strength aluminium products by subsequent cold rolling after equal channel angular pressing (ECAP) was proposed and experimented. ECAP is an advanced severe plastic deformation (SPD) method for controll...

Recent surge in the number of studies on inorganic nanoparticles has raised concerns over possible commercial implication of the same. The developmental stage of regulations and standards controlling the same amplifies this problem. In this perspective, we tried to analyze the current trends on lignocellulose nanomaterials (viz. Nanocellulose and lignin) and its global potential to offer an environmentally benign alternate. We used number of studies indexed in Scopus database to get an idea of trends. An additiona...

The aim of the present work is to develop, substantiate, and study a fundamentally new method of derivation of composite electrolytic films making it possible to control their composition and structure. We assume that, after the termination of the stirring-up of a bath containing the electrolyte-suspension with monodisperse spherical particles of the same density, a uniform sedimentation space is established. The upper boundary of this field will descend with a velocity depending on the dispersity and density of a...

Soil contamination is a component that contributes to the increase of environmental pollution, as soil is the key element that underpins food production for household consumption. The transfer of contaminants from soil to plants is one of the input mechanisms of human exposure to metals through food chain. Mathematical models are documented as effective tools, that could help observe pollutants impact on agricultural products (vegetables and fruits) as well as on environmental systems, to evaluate different scenar...

The aim of the study was to investigate the effect of microcrystalline cellulose fibers on the mechanical properties of flexible starch based foams. During the experiment the foams obtained with potato starch with the addition of glycerol as plasticizer were tested. The starch was blended with glycerol in laboratory mixer with 30 wt.% glycerol addition. The process of making foams have been carried out by microwave heating in laboratory microwave oven. To improve the mechanical properties of starch foams to the mi...

The study solves actual modern problem for obtaining polysilicate solution (as a mineral component of clinkerless binder) based on low-quality siliceous raw materials. A mechanochemical synthesis method of sustainable colloidal silica sol (with a particle size of 5-25 nm) is proposed, as well as a grounded choice of grinding parameters is made. Influence of protolytic properties of liquid phase on dispersion speed, aggregate and sedimentation stability of the silica sol are studied. The obtained dependence of the ...

The paper tries to make a study on the kinematics of the mechanisms involved in robot composition, the theoretical foundations of the dynamics of industrial robotic systems and the structure of a mechatronic micro-position system used in manipulation operations in order to optimize and correct the performances. The robot is a complex automated system that has the role of manipulating the parts and tools, replacing the action of human. An industrial robot is a system that does not operate in isolation, it communica...

The paper presents and analyzes the experimental results obtained by the welding reconditioning of a pressure vessel made of 14CrMoV4, a Romanian trade of steel, which is the equivalent of 13CrMo4-5, in the European norm 10028-2/2009, steel, which functioned for a long period of time in the energetic industry. The welding process used for reconditioning is robotized gas metal arc welding (GMAW). A series of samples were realized using different technological parameters in order to obtain different geometrical conf...

Innovative methods in the investigation of low-grade uranium ores were tested. As the individual ore components in the rock are optically undetectable, we focused on the detection of selected elements (U, Zr, Fe, Nb), their possible associations and distribution. For this purpose, mineral mapping of sample surface was used. The studied samples are uranium-bearing sandstones with remarkable elemental and mineral compositions. Low concentrations of the main ore elements and the small size of mineral phases (in micro...

Engineering novel material structures has continually been pursued to further advance modern technologies. These advancements often rely on novel processing technologies. Although many processing parameters have been thoroughly examined in the field of composition coatings, the formation processes are an exception. In this work, we examine the unique microstructures of composite electrolytic coatings, obtaining from electrolytes-suspension which contains nano-size particles of SiO2 and carbon. Metallographic resea...

Conductive polymer composites due to their unique properties and potential in various applications including chemical and bio sensors are receiving much research attention in recent times. The study investigate the effect of increasing polymer concentration and the influence of mixing time on morphology and electrical conductivity were. A highly conducting nanofiller and reduced graphene oxide (RGO) was incorporated into the matrix of expanded polystyrene; a recycled polymer, and the solution was electrospun under...

The importance of wastewater treatment is growing rapidly with the populationпїЅs need of access to pure water and industrial process water. Different wastewater treatment technologies are available worldwide but the membrane treatment technology has earned popularity in the last decades because of cost/efficiency reasons. Polymeric membranes lead the market in membrane manufacture because they are very competitive in performance and economics. Polysulfone is one of the most used membrane material and has advantag...

Nanostructured black silicon wafers were obtained in a two-stage process of selective chemical etching initiated by metal nanoclusters. The obtained silicon wafer surfaces demonstrate the reflectance of 2-3% in the visible range. Surface-enhanced Raman scattering (SERS) effect was observed on silicon substrates coated with silver or cooper nanoclusters. Test substance of Rhodamine can be detected up to concentration of ~10- 12 ? by using nanostructured silicon substrates covered with silver nanoparticles. Dependen...

The results of microstructure study, X-ray microanalysis, microhardness, porosity of sintered samples from a powder high-speed steel before and after hardening by the wave intensive plastic deformation are presented. It has been established that the basic elements in the composition of sintered samples from tungsten powders are C, O, Mo, Ca, V, Cr, Fe, W. Based on the analysis of the sintered samples microstructure, it was determined that the there is a uniform distribution of solid carbide in the base material vo...

The processes of nanogold deposition and concentration in the environment, which have been occurring with enlargement of metal grain size, may be considered as the natural nanotechnologies. The mechanisms of nanogold concentrations in geological objects are established and described on the example of many deposits in Russia (the Urals, Siberia) and abroad (Canada). They produce different morphological and chemical aggregations of gold nanoparticles. Among them variable growths on the placer metal surface, globular...

Nanoparticles of magnetic fluids are stabilized with various surfactants. Lignosulfonates are water-soluble byproducts of sulfite pulping process. The aim of our work is to estimate possibility of using nitrated lignosulfonates for stabilization of water-based magnetic fluid and determine optimal nitration conditions. Nitrolignosulfonates were synthesized by nitration of sodium lignosulfonates with nitric acid and the products without further purification were used for preparation of magnetic fluid. Magnetic nanop...

Limestone deposits are primary raw material for cement manufacturing plants. However, mining engineers and geologists faces challenges in determining an appropriate, accurate and cost effective estimation method. The aim of this research is to evaluate and compare the applicability of two geostatistical methods, Ordinary Kriging (OrK) and Inverse Distance Weighting (IDW), for estimating quality of the Ta Thiet limestone, a lithological structure deposit at Binh Phuoc province (Vietnam). For this purpose, data coll...

Nanocomposites have been considered as a stimulating route for creating a new type of high performance material that combines the advantages of polymer and the nanoparticles. Polyamide is well known as an engineering thermoplastic material that is widely used in industrial applications for its good mechanical and thermal properties. The paper presents the study of the new nanostructured polymer composites from polyamide/oxidized graphite nanoparticles-PA/GO to manufacture, by injection, bearing seals, contact plat...

A learning algorithm was used as an artificial neural network (ANN) tool to predict the mechanical properties of some iron-based powder metallurgy (P/M) materials. Specimens prepared from atomized iron powder and from pre-alloyed iron base powders powders were analyzed in this paper. The specimens were fabricated by press and sintering of the mixed powders. The samples were compressed in a universal mechanical testing machine to a pressure of 400 and 600 MPa. The sintering temperature was approximately 1.150 пїЅC....

In the present work, polymer-silica hybrid latexes based on methyl methacrylate (MMA), butyl acrylate (BuA), 2-hydroxyethyl methacrylate (HEMA), and different inorganic precursors (tetraethoxysilane (TEOS), isobutyltriethoxysilane (IBTES), diethoxydimethylsilane (DEDMS), vinyltriethoxysilane (VTES)) were synthesized by emulsion polymerization and sol-gel process. The resulting latexes were characterized both as materials placed into plastic vials and as films deposited onto clean glass slides by various techniques...

In this paper, the authors discussed one of the Hume-Rothery conditions for occurring substitutional solid solutions in the context of binary relations. The analyzed condition says that substitutional solid solutions may form if the ionic radius of the solute and solvent ions differ by no more than 15%. Because the problem concerns a mathematical connection between two objects, the authors suggested describing this problem using the set-theoretic notion of binary relation. In this context, the possibility of formi...

Iodine adducts are increasingly being used as the drugs and materials with antimicrobial properties. Using them as biocidal reactive materials in the highly crowded premises, hospitals and maternity homes, can stop the development of epidemics caused by microbes that are resistant to common antibiotics. The iodine adducts formed in the lysine-iodine-potassium iodide system served as the object of the present study. The purpose of the work was to obtain data on structural-phase transformations in the genesis of iod...

The current demand for energy production in dissipated systems and the related need for miniaturization of power machines require the use of appropriate technical solutions. Increasingly, power generation microsystems are used to produce electricity that functions in hermetic circuits (e.g. ORC - Organic Rankine Cycle). Rotors of such type of machinery, in order to generate the expected amount of energy, must rotate at speeds up to 100,000 rpm. Rotational speeds of this order represent significant problems in the ...

Coordination compounds of metals and their halides with biologically active organic ligands can be used to produce materials with various optoelectrical and magnetic properties. Some of them can enhance the tunnel effect. Complexes of metal halides with amino acids and halogens with various structures have been synthesized. Lithium halides, which form complexes with electron-donor molecules are of particular interested for biological applications. The studies on coordination compounds of lithium halides with amino...

This paper reports the synthesis of hybrid zirconium sol-gel coatings by solпїЅgel process at room temperature (25 пїЅC), using tetraethoxysilane (TEOS) as a precursor and different alkyltriethoxysilanes (RTES) with variable organic functionality (methyl, vinyl and octyl) as surface modifying agents. All silica materials was prepared with zirconium(IV) propoxide (as cross-linking agent), by keeping the molar ratio of TEOS:RTES at 1:1, in acidic conditions. The zirconium sol-gel films were obtained by depositing th...

Aerogels production consists of two main stages: preparation of the gel filled with solvent (alcohols, acetone or hexane) by polymerization or sol-gel process and its supercritical drying. The most energy consuming and complicated from a technical point of view is the drying step [1]. Supercritical drying allows keeping the internal structure by preventing collapse of pores. Supercritical conditions require the use of expensive highpressure apparatus and the process rate is limited by diffusion within the pores of...

The development of materials science is in direct connection to the production of composite material with specific properties and to the technologies for their fabrication. The unique properties of the composites fabricated in Ti-Al-B-C systems makes them attractive for aerospace, power engineering, machine and chemical and other practical applications. Besides, Aluminum matrix composites (AMCs) have great potential as structural materials again due to their excellent physical, mechanical and tribological properti...

The magnetorheological (MR) fluids include ferromagnetic and paramagnetic particles suspensions with sizes included between 0.03 and 10 ?m, located in a carrier fluid (usually mineral oil). The complex fluid viscosity strong depends of magnetic field applied. Each particle can be considered a small magnet, which tends to align in the direction of the magnetic field. The magnetorheological fluids have the ability to change their viscosity when they are introduced into a magnetic field, due to the aligned particles ...

The loss of an organ or part of an organism generates, in addition to loss of function, social and psychological disorders. The modern bio-technologies try to diminish their effects on affected humans. The advancement of modern medicine that uses biomaterials to solve issues related to tissues and organs reconstruction has increased the human life expectancy, rapidly. The most important factors that limit the lifetime of implants are certain corrosion and wear products, which can have negative effects on the human...

The wheat is one of the most important crop in the world, the area cultivated exceeding 200mil ha. One provocation for researchers is represented by the question "In the conditions of continued growth of world population, how can to improve the wheat yield in the condition of maintain or decreasing the cultivated area". The answer can be offered by the seed treatment with cold plasma. This paper contains the results of research regarding the using of cold plasma for wheat seed treatment. The research was performed...

New materials based iron powder, with several addition elements obtained by powder metallurgy. The sample were obtained by compacting of 500 M Pa , obtaining a sampless and sintering in dry hydrogen atmosphere at the different temperatures. The sintered samples were metallographic prepared by polishing in order to investigate the porosity and evaluate the microhardness of individual grain and structural constituents. I am studing the effect of addition elements on Rockwell hardness and microhardness. Hardness is t...

The objective of the study was to increase the solubility of amiodarone hydrochloride by complexation with hydroxypropyl-пїЅ-cyclodextrin. After complexation a cyclodextrin/amiodarone inclusion complex was formed. The use of media containing surfactants is a suitable solubilizing method and as a result, a non-ionic surfactant - Tween 80 and an anionic one - sodium lauryl sulfate have been used. The dissolution profile of amiodarone hydrochloride and that of the inclusion complex, regarding the release of the activ...

This paper focuses on the influence of the fiber glass functionalization agent on the properties of the polymer composites. Thermoplastic polymers are novelty materials, with special properties, depending on the type of elastomer, the degree and type of functionalization agent of the reinforcing material etc. Thus new impact and flame resistant advanced materials were developed and characterized. The polymers chosen for this study were polyamide (PA), a thermoplastic polymer that has high temperature resistance an...

Metal Oxide Varistors are today used for manufacturing state of the art overvoltage protection equipment, at any voltage level, being one of the most common power electronic devices existing on the market. They are widely used because they have a very high non-linear dependence between the applied voltage and the resulting current, and a relatively high energy absorption capability in case of normal overvoltage shocks or even in case of permanent overvoltages. Researches could be carried out both for finding a new...

Membrane processes used in wastewater treatment are categorized as the best techniques available at this time because it has advantages in terms of quality and costs. The membranes have different properties depending on the obtaining parameters. Their properties can be influenced throughout the membrane fabrication steps: when the polymer solution is prepared, when the polymer solution is applied in form of a thin film and also even after the thin film membrane is removed from the coagulation bath. Some important ...

Metal Oxide Varistors are today used for manufacturing state of the art overvoltage protection equipment, at any voltage level, being one of the most common power electronic devices existing on the market. They are widely used because they have a very high non-linear dependence between the applied voltage and the resulting current, and a relatively high energy absorption capability in case of normal overvoltage shocks or even in case of permanent overvoltages. Researches could be carried out both for finding a new...

This article presents results of the studies conducted by authors for determining the influence of ultrasounds, used in the intercritical quenching, on the structure of some low carbon and manganese dual-phase steels (0.087% C and 0.511% Mn, respectively 0.101% C and 0.529% Mn). The samples of these steels were heated to temperatures between 760 and 820 ?C (temperatures between the critical points Ac1 and Ac3), for 30 minutes and then quenched in water, water in ultrasonic field with frequency of 40 kHz and water ...

Comparison of microcrystallites morphological structure of microcrystalline cellulose specimens obtained hydrolytically from plant and bacterial cellulose microfibrils is described. Micromorphological characteristics of the structures are visualized using SEM Sigma VP ZEISS scanning electron microscopy. The crystallinity degree of the microcrystalline cellulose specimens is calculated by new method using X-ray diffractometry (XRD-7000S diffractometer). Native bacterial cellulose is obtained on the glucose media us...

The occurrence of nonconformities in prosthetics or medical instruments as a result of the manufacturing process or final machining (finishing) may lead to the decision of not using them in the medical process. The present paper aims to analyze the welding reconditioning possibilities in order to ensure the necessary geometrical characteristics, using the method of finite element analysis (FEA), of the interlocking intramedullary nail prosthetics made of titanium or titanium alloys. After identifying the nonconfor...

Corrosion is the deterioration of a metal as a result of chemical reactions between it and the surrounding environment. Is a natural process, which converts a refined metal to a more chemically-stable form, such as its oxide, hydroxide, or sulfide. It is the gradual destruction of materials (usually metals) by chemical and/or electrochemical reaction with their environment. Biomaterials are used to replace a part of the body functions lost due to illness or to improve functions and to correct anomalies. The import...