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Search Results: 1 - 10 of 297305 matches for " J. Sieniawski "
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The influence of initial plastic deformation on microstructure and hot plasticity of α+β titanium alloys
M. Motyka,J. Sieniawski
Archives of Materials Science and Engineering , 2010,
Abstract: Purpose: Hot deformation behaviour of two-phase titanium alloys is determined depending on microstructure developed in heat treatment and plastic deformation processes. In the paper stereological parameters of microstructure obtained in initial heat treatment and plastic working in the α+β β phase transformation range with various forging reduction (ε ≈ 20 and 50%) were determined. Evaluation of the effect of thermomechanical process parameters on hot plasticity of Ti-6Al-4V and Ti-6Al-2Mo-2Cr titanium alloys was performed.Design/methodology/approach: In the research, light and transmission electron microscopy were employed. Digital image analysis methods were used for determination of stereological parameters of microstructure obtained in particular stages of thermomechanical process of Ti-6Al-4V and Ti-6Al-2Mo-2Cr titanium alloys. Hot deformation of thermo mechanically processed titanium alloys was performed in vacuum at the temperatureof 850 and 925oC at the strain rates ε = 1 10-2, 1 10-1 and 5 10 -1 s-1.Findings: It was found that degree of initial plastic deformation in thermomechanical process considerably affects relative elongation in high temperature tensile test at the lowest strain rate applied (ε = 1 10-2).Research limitations/implications: Developed thermomechanical process enables controlling morphology of microstructural constituents and hot workability of two-phase α+β titanium alloysPractical implications: Obtaining the demanded operational and technological properties of structural two-phase α+β titanium alloys is related to both the appropriate selection of hot working parameters and preceding thermomechanical process conditions.Originality/value: The effect of heat treatment conditions in thermomechanical process on superplasticity of Ti-6Al-4V alloy was researched previously [1, 2]. In this paper two-phase Ti-6Al-2Mo-2Cr titanium alloy was examined too. Additionally, the influence of a degree of initial deformation in thermomechanical process was analyzed. Hot deformation test were conducted at conditions outside the superplastic range too.
Effect of diffusion on platinum coatings deposited on the surface of nickel based superalloy by the electroplating process
M. Yavorska,J. Sieniawski
Archives of Materials Science and Engineering , 2010,
Abstract: Purpose: In this paper the effect of diffusion on platinum coatings deposited on the surface of nickel based superalloy was evaluated.Design/methodology/approach: The platinum coatings with thickness of 3 mm and 7 mm were deposited by electroplating process on Inconel 713 LC Ni-base superalloy. The heat treatment of electroplating coatings at the temperature 1050 °C during 2h under argon atmosphere was performed. The microstructure investigations of the heat treated coatings were conducted by the use of optical microscope (Nikon Epiphot 300) and a scanning electron microscope (Hitachi S-3400N) equipped with an X-radiation detector EDS (VOYAGER of NORAN INSTRUMENTS). The phase composition was identified by X-ray (ARL X’TRAX) diffractometer. The surface roughness parameter - Ra was evaluated by Perthometer S2 MAHR equipment.Findings: The microstructure of platinum electroplating coating with thickness of 3 μm after diffusion treatment consists of two phases: γ-Ni and (Al0.25Pt0.75)Ni3. The increase of platinum thickness from 3 μm to 7 μm does not influence the phase composition of heat treated coatings. Heat treatment of platinum electroplating coatings causes the increase of surface roughness parameter as a result of unequal mass flow of platinum and nickel.Research limitations/implications: The results will be used in the future investigations to explain the mechanism of reaction of platinum as a modifier in aluminide coatings.Practical implications: The platinum electroplating coatings after diffusion treatment and aluminizing process are widely used as coatings for turbine blades of aircraft engines.Originality/value: The paper includes the results of microstructure and surface roughness investigations of platinum electroplating coatings with 3 mm and 7 μm thickness after diffusion treatment.
Modification of the structure of the layers of superficial soda - calcium - silicon glasses nano molecules inorganic compounds
M. Drajewicz,J. Sieniawski
Journal of Achievements in Materials and Manufacturing Engineering , 2012,
Abstract: Purpose: Finding a new surface treatment of glass.Design/methodology/approach: Testing results of the glass operational properties, such as bending strength, scratching resistance, micro-hardness, chemical resistance and optical properties have been presented. Nano-molecules were spread onto the heated glass surface, or onto cold glass surface and then heated up to temperatures close to the glass transformation, when nano-molecules penetrate into the glass surface.Findings: Refining method of soda - calcium - silicon glassy surfaces with inorganic compounds nanomolecules assures profitable operational properties of the glass, such as increased bending strength, scratching resistance, micro-hardness and chemical resistance without deterioration of the optical properties.Research limitations/implications: Structural definition of inorganic compounds nano-powders exposed to thermal processing, including grain-size analysis has been discussed.Practical implications: Optimal technical and technological parameters of the refining process have been selected.Originality/value: The presented method undoubtedly develops new possibilities not only in case of container glass, float glass and glass fibres but also in the field of glass processing.
Oxidation behaviour of platinum modified aluminide coatings deposited by CVD method on nickel-based superalloys under air atmosphere
M. Yavorska,J. Sieniawski
Journal of Achievements in Materials and Manufacturing Engineering , 2011,
Abstract: Purpose: In this paper the oxidation resistance of platinum modified aluminide coating deposited by CVD method on nickel-based superalloy was evaluated.Design/methodology/approach: Platinum coatings 3 and 7 μm thick by the electroplating process were deposited. The heat treatment of electroplating coatings at the temperature 1050°C for 2 h under argon atmosphere was performed. Low activity CVD aluminizing process of platinum heat treated coatings (3 and 7μm thick) at the 1050oC for 8 h using IonBond equipment was performed. Oxidation resistance at 1100oC for 1000 h in air atmosphere using furnace of Czylok company was evaluated. The microstructure investigations of platinum and palladium modified aluminide coatings were conducted by the use of optical microscope (Nikon Epiphot 300) and a scanning electron microscope (Hitachi S-3400N) equipped with an Energy Dispersive Spectroscope EDS (VOYAGER of NORAN INSTRUMENTS). The phase composition was identified by X-ray (ARL X’TRAX) diffractometer. The surface roughness parameter - Ra of modified aluminide coatings was evaluated by Perthometer S2 MAHR equipment.Findings: The microstructure of platinum modificated aluminide coatings (3 and 7 μm thick) consists of (Ni,Pt)Al phase and two zones: outer and internal one. Low activity CVD aluminizing at 1050oC for 8 h causes the increase of surface roughness parameter of modified coatings. The increase of platinum thickness from 3 to 7 μm lets to get a greater surface roughness parameter of aluminide coatings. On the ground of the obtained results, it was found that platinum modification of aluminide coatings provides to increase of oxidation resistance Ni-based substrates. Practical implications: The platinum modified aluminide coatings are widely used as coatings for turbine blades of aircraft engines.Originality/value: It was proved that platinum modification of aluminide coatings has a positive effect on the oxidation resistance of substrate.
Superplasticity in titanium alloys
J. Sieniawski,M. Motyka
Journal of Achievements in Materials and Manufacturing Engineering , 2007,
Abstract: Purpose: The paper reports characteristic of superplasticity phenomenon in titanium alloys and possibility of its applications.Design/methodology/approach: The main objective of the paper is to show features of superplastic forming of titanium alloys and current research trends aiming at widespread application of this technology.Findings: In the paper characteristic of selected superplastic titanium alloys was presented. The effect of microstructural parameters on superplasticity was considered too. Mechanical properties of superplastic deformed titanium alloys, determining criteria of their potential applications, were also addressed.Research limitations/implications: Application of superplastic forming (SPF) in industry is limited due to long time and high temperature of the forming process. In the paper directions of the studies were presented which can lead to increase in effectiveness of the process.Practical implications: SPF enables manufacturing of complex shape details in one-step technological operation. Together with diffusion bonding (DB) it offers particular advantages making possible to manufacture complicated multilayer structures.Originality/value: The paper summarizes achievements of the studies on the superplasticity of Ti alloys, emphasizes the role of microstructural parameters and methods of their modification leading to better results and economics of SPF.
New Quality Assessment Criterion of AlSi5Cu1 Alloy
M. Wierzbińska,J. Sieniawski
Archives of Foundry Engineering , 2007,
Abstract: The paper presents the discussion of the results of mechanical testing for aluminium foundry alloy AlSi5Cu1Mg for high-loaded machine elements. Values of yield strength (Rp0.2), tensile strength (Rm), elongation(A5) and hardness (HB) are usually considered as the primary quality assessment criterion for a manufacturing process. It was concluded, that this criterion, A5 index particularly, is unsatisfactory to estimate the plasticity of the alloy and its crack resistance in the presence of sharp-pointed stress concentrators or microcracks. More adequate parameter is plane strain fracture toughness KIc. However, size of the samples appeared to be twice as large as would be needed to fulfill requirements of test conditions, and the test itself is laborious and time-consuming that it becomes impractical as a acceptance test. Therefore, substitute test for quality assessment – determination of tensile strength in the presence of a sharp notch kmR was applied. The comparative analysis of kmR/Rp0.2 ratio, as a more enhanced fatigue resistance criterion than kmR and plane strain fracture toughness KIc of the alloy was performed. It was assumed that kmR/Rp0.2 parameter has good correlation with the critical stress intensity factor KIc Thus, under manufacturing process conditions, being unable to carry out KIc test, it may be successfully replaced by kmR test.
The technology of Plasma Spray Physical Vapour Deposition
M. Góral,J. Sieniawski
Journal of Achievements in Materials and Manufacturing Engineering , 2012,
Abstract: Purpose: The deposition of thermal barrier coatings is currently the most effective means of protecting the surface of aircraft engine turbine blades from the impact of aggressive environment of combustion gases. The new technologies of TBC depositions are required.Design/methodology/approach: The essential properties of the PS-PVD process have been outlined, as well as recent literature references. In addition, the influence of a set process condition on the properties of the deposited coatings has been described.Findings: The new plasma-spraying PS-PVD method is a promising technology for the deposition of modern thermal barrier coatings on aircraft engine turbine blades.Research limitations/implications: The constant progress of engine operating temperatures and increasing pollution restrictions determine the intensive development of heat-resistant coatings, which is directed to new deposition technologies and coating materials.Practical implications: The article presents a new technology of thermal barrier coating deposition - LPPS Thin Film and Plasma Spray - Physical Vapour Deposition.Originality/value: The completely new technologies was described in article.
Effect of morphology of eutectic silicon crystals on mechanical properties and cleavage fracture toughness of AlSi5Cu1 alloy
M. Wierzbińska,J. Sieniawski
Journal of Achievements in Materials and Manufacturing Engineering , 2005,
Abstract: Purpose: The purpose of this paper is presentation of the results that concerned the influence of morphology of eutectic silicon crystals on mechanical properties, especially on the cleavage fracture toughness of AlSi5Cu1 alloy.Design/methodology/approach: Microscopic studies – optical microscope NIKON 300 and quantitative analysis of geometrical parameters of microstructure – image analysis program APHELION, tensile and fracture toughness tests – testing machine INSTRON 8810.Findings: The sizes of silicon crystals and values of yield strength, tensile strength and plane strain fracture toughness have been determined. Relationships between mechanical properties and silicon crystals size were described using Hall-Petch equation. It was found that a decrease in silicon crystals causes an increasing in strength and in fracture toughness.Practical implications: This paper is part of the previous author’s investigations which results in modification of the casting technology of turboblower compressor impellers.Originality/value: The microscopic observations indicated that alloy cracking begins with nucleation and growth of micro-cracks in the silicon crystals of large size, in orthogonal plane to tension direction. The hard and brittle silicon crystals are very strong barriers for slip in the stressed alloy.
The influence of long-lasting annealing on microstructure of AlCu4Ni2Mg2 alloyThe influence of long-lasting annealing on microstructure of AlCu4Ni2Mg2 alloy
M. Wierzbińska,J. Sieniawski
Journal of Achievements in Materials and Manufacturing Engineering , 2009,
Abstract: Purpose: of this paper was to determine the influence of long-term annealing at elevated temperature on the microstructure and mechanical properties of AlCu4Ni2Mg2 alloy.Design/methodology/approach: The microstructure was observed using optical light (LM), scanning (SEM) and transmission (TEM) microscopy. The mechanical properties were determined on a standard tensile test machine.Findings: It was found that after long time hold at elevated temperature (523 K) the degradation of microstructure of alloy was observed. The microstructural changes consist in increase of size of hardening phases precipitates (Θ’-Al2Cu) and changing its shape. These phenomena cause decrease in the mechanical properties of the alloy.Research limitations/implications: In order to complete obtained results it is recommended to perform further investigations of behaviour of AlCu4Ni2Mg2 alloy in 573 K and 623 K corresponding to the maximum values of temperature at which structural elements of piston engines made of aluminium alloys operate.Practical implications: From a practical point of view it is important to realize, that however the Cu (about 4%) and Ni (about 2%) additions significantly influence increasing of mechanical properties of aluminium alloy, nevertheless don’t protect against the degradation of its microstructure and finally from decreasing of strength during machine elements operation.Originality/value: This work has provided essential data about microstructural changes of aluminium alloy proceeding during elements of piston engines operation.
EXAFS study of iron nanoparticles with oxide shell
A. Onyszko,Cz. Kapusta,J. Sieniawski
Archives of Materials Science and Engineering , 2007,
Abstract: Purpose: The aim of this work is to present the results of the study of the local structure of iron nanoparticlwith oxide shell which uses EXAFS method that apply synchrotronic radiation.Design/methodology/approach: The samples used in the carried out analysis were as follows: pure iropowder, pure iron powder containing nanoparticles and pure iron powder containing nanoparticles subjected 224 hours of grinding.Findings: The local structure of iron nanoparticles with oxide shell were found.Research limitations/implications: It was not enough time to measure O:K edge.Practical implications: The analysis of spectra does not reveal any iron oxides in samples. More accuraresults would be obtained at oxygen K edge.Originality/value: It was proved that iron nanoparticles with oxide shell samples had the local structucharacteristic for metallic iron.
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