Papers by Keyword: Surface Treatment

Abstract: This paper reports on investigations of the beneficial effects of electron beam alloying (EBA) and electron beam dispersion alloying (EBDA) on the wear behavior of AZ91D Mg alloy under mild wear conditions with applied normal loads of 1…10 N. The layers generated had a thickness of 1.5 mm with Al contents of 30 wt.%. For dispersion alloyed layers, TiC was added with particle sizes of 20…100 µm. At a sliding distance of 20 m, the wear rates of alloyed layers (150 HB) and dispersion alloyed layers (180 HB) were almost the same and could be reduced by half compared to the untreated AZ91D (60 HB). Due to their large size and the large spaces between them, TiC particles were pressed into the layer matrix, or were torn out and acted as additional abrasives. Therefore, at a sliding distance of 50 m, the wear rate of dispersion alloyed layers increased to the level of the base material.

Abstract: Biodegradable implant material for medical applications has to fulfill specific therapeutic tasks. For our investigations, synthetic polymers, polyurethanes (PUR) and polyetherimide (PEI), were used. Both systems have been used to coat an Al-free Mg alloy. Characterization of materials was performed by IR, spark spectral analysis, microscopy and EIS. Electrochemical investigations of the different treated samples in aqueous NaCl and Hank's Balanced Salt Solution indicate specific response of the polymer/substrate system to corrosion attack.

Abstract: Bioplastics are plastics derived from renewable sources such as corn starch or microbe and biodegradable plastics are plastics that are capable of being decomposed by bacteria or other living organisms. Poly (lactic acid) (PLA) is a typical and biodegradable bioplastic. It has been recognized as a promising alternative material for petroleum-based polymers. In order to increase Young’s modulus, in the present study, silica nanoparticles were added to PLA. The effects of the addition of silica nanoparticles and the surface treatment of nanosilica particles on dynamic properties of nanoparticle added PLA were examined using tensile split Hopkinson pressure bar method and the Izod impact strength tests.

Abstract: The main purpose of this work is the energy saving by reducing friction and minimizing wear to avoid losses by raising the properties of nanomaterials on the surface layer. Therefore, we develop approaches for studying the tribological behavior phenomena concerning materials on surfaces of the layers to define the mechanical and tribological properties of materials to improve the surface layer materials of the treated parts. It was used for the vibratory grinding method of chemical mechanical processing surface using the technology of low-frequency vibration in the treatment of metal parts in the presence of chemical additives, which have a great influence on the improvement of mechanical and geometrical parameters (roughness, fatigue resistance, corrosion resistance, micro and macro hardness, structure) of mechanical parts. This method of vibratory grinding has great advantages such as the treatment of complex mechanical parts, the ability to process parts of different types and shapes at the same time. It is also known to be an environmentally friendly process. Thus this work consisted of a surface treatment by vibratory grinding of samples of different materials.

Abstract: It is known that the diffusion of boron atoms on the surface of metals and alloys can increase the hardness, wear and corrosion resistance of engineering components. Boriding is an alternative method of sample treatment when the manual work required in powder boriding needs to be decreased. In addition, its advantage lies in high volumes of work and in selective treatments. Boron carbide consists of B₄C (approximately 76 wt% boron). Using gases or powders as boronizing process gives rise to boride coatings constituted by an inner layer of Fe₂B (hardness 15GPa) and an outer layer of FeB (hardness 25 GPa) [1,2]. Many industrial processes require the use of highly wear-resistant materials, tools steel, hot work being these basic Cr steels in applications such as extrusion dies for light alloys, matrices for pressing, forging dies and for molding plastic.

Abstract: The growing ecological, social and economic awareness, high rate of depletion of petroleum resources, concepts of sustainability and new environmental regulations have stimulated the search for green materials compatible with the environment. The focus of this research is to study the effect of fibre surface treatment as far as kenaf fibre composite sandwich structure is concern. The kenaf fibre is subjected to alkali treatment. Upon completion, the treated kenaf fibre is used for fabrication of composite sandwich structure by utilizing thermoset resin which is epoxy as the matrix and galvanized steel as the face skin. The sandwich structure undergone SEM for morphological study and three point bending test to identify the bending properties. Treated kenaf fibres shows improvement after the alkali treatment compared to untreated kenaf fibre in the composite sandwich structure.Keywords: Composite sandwich structures; biodegradable; kenaf fibres ; surface treatment; morphology

Abstract: Corrosion is an undesirable action which can occur in metals. To minimize this problem, there are several types of coat to the metal surface being researched in an attempt to retard the oxidation processes. In this work, the deposition of a new ceramic coating based on niobium oxide over aluminum alloy AA 3003 was studied in order to obtaining a corrosion resistant and less polluting film. It was utilized the experimental planning to optimize the deposition of ceramics, and it was performed electrochemical tests, scanning electron microscopy and dispersive energy spectroscopy to evaluate these films. The ceramic coating based on niobium oxide obtained presented itself as an effective corrosion inhibitor for aluminum alloy AA 3003.

Abstract: Large-scale silver nanoparticles with fine dispersion and narrow size distribution were synthesized by reducing silver nitrate with sodium borohydride and sodium citrate and using poly (vinylpyrrolidone) as an adsorption agent in the ethanol solution. The sintering behavior and electrical properties of silver nanoparticles treated with and without glutaric acid were studied. Morphology studies showed that the treated silver nanoparticles obviously agglomerated and began to sinter at 200 °C and the sintering temperature is higher at least 50 degrees than that of the untreated silver nanoparticles The treated silver nanoparticles as fillers of electronically conductive adhesives (ECAs) is more advantageous to the increase of the conductivity. Otherwise, only in the conditions of the appropriate sintering temperature and loading of silver nanoparticles, the high conductivity of the ECAs was obtained. The effect of the treated silver nanoparticles on the electrical properties contributes to the surface activation and sintering behavior.Keywords: Silver nanoparticle, Sintering Behavior, Surface treatment, Electrical property

Abstract: In this paper, silver nanostructures were synthesized via a solvothermal method by reducing silver nitrate with ethylene glycol in the presence of poly (vinylpyrrolidone) and using NaCl, MgCl₂, AlCl₃, FeCl₃, Fe₂(SO₄)₃ , NaOH, NaBr and Na₂S as reaction inhibitor, respectively. Characteristics of the as-prepared silver nanostructures were studied by scanning electron microscopy (SEM), X-ray diffraction (XRD) and UV-visible (UV-vis) absorption spectrum. It is found that the mixture of nanoparticles and nanorods and nanowires can be observed in the AlCl₃ and NaOH systems, the nanorods as main products can be obtained in the MgCl₂ and NaCl and Fe₂(SO₄)₃ systems, the large scale silver nanowires as main products can be obtained in the FeCl₃ and Na₂S systems, especially in the Na₂S system, silver nanowires are very long and curved. The results indicated the reasons of the effect of the reaction inhibitors on the morphologies of silver nanostructures depend on the solubility product constant of silver salt which formed with silver ion and inhibitor anion ion in the initial stage and the properties of metal cationic ion of inhibitor. The smaller solubility product constant of silver salt or the presence of Fe³⁺ or low valence metal ion greatly facilitate the formation of one-dimensional silver nanostructures, especially to nanowires.

Abstract: The article deals with the use of sodium water glass in production of top plate of chordophones and its influence on the physical and acoustic characteristics of wood (density – ρ, modulus of elasticity – E, acoustic constant – A, speed of sound – c) as well as on the frequency spectrum. The selected characteristics of resonance spruce wood (Picea abies), were measured via non-destructive dynamic method on the apparatus called MEARFA. Measurement showed that sodium water glass influences the required characteristics (ρ, A, c) of spruce wood negatively. The frequency analysis was carried out by means of FFT (Fast Fourier Transform).