Informacja

Drogi użytkowniku, aplikacja do prawidłowego działania wymaga obsługi JavaScript. Proszę włącz obsługę JavaScript w Twojej przeglądarce.

English (EN)·Polski (PL)·Yкраїнський (UK)
Przejdź do strony domowej biblioteki Centralna Biblioteka Wojskowa Link otwiera się w nowym oknie Logo biblioteki Prolib Integro - strona głównaCentralna Biblioteka Wojskowa

Wyszukujesz frazę "composite microstructure" wg kryterium: Temat

  Lista filtrów
Wyrównaj
Wyświetlanie 1-15 z 44
Tytuł:
Corrosion Resistance of Titanium Based Composites Reinforced with in situ TiB Precipitation Phase
Autorzy:
Miklaszewski, A.
Powiązania:
https://bibliotekanauki.pl/articles/353786.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
corrosion resistance
titanium based composites
composite microstructure
in situ TiB reinforcement phase
Opis:
The paper presents the results of corrosion resistance tests carried out on titanium based composites reinforced with different TiB precipitation phase amount, dependent from boron addition in starting powder blends. Precursor powder preparation and processing parameters of conventional powder metallurgical approach influence density and obtained porosity of bulk compacts. The potentiodynamic tests performed in 0.1 M NaCl solution by the technique of linear voltammetry shows visible difference between compared composite structures. Studies have confirmed that the reinforcement phase amount and its morphology influence obtained microstructure and have important effect on the composite corrosion resistance.
Źródło:
Archives of Metallurgy and Materials; 2016, 61, 4; 1767-1770
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Combined Effect of CrB2 Micropowder and VN Nanopowder on the Strength and Wear Re-sistance of Fe‒Cu–Ni–Sn Matrix Diamond Composites
Autorzy:
Ratov, Boranbay
Mechnik, Volodymyr
Rucki, Miroslaw
Gevorkyan, Edwin
Kilikevicius, Arturas
Kolodnitskyi, Vasyl
Siemiatkowski, Zbigniew
Umirova, Gulzada
Chałko, Leszek
Józwik, Jerzy
Zhanggirkhanova, Arailym
Chishkala, Vladimir
Korostyshevskyi, Dmytro
Powiązania:
https://bibliotekanauki.pl/articles/2201897.pdf
Data publikacji:
2023
Wydawca:
Stowarzyszenie Inżynierów i Techników Mechaników Polskich
Tematy:
diamond composite
electroconsolidation
composite microstructure
adhesion
CrB2
VN nanopowder
micropowder
VN
wear resistance
cutting tools
mining tools
Opis:
The paper presents research results on the enhancement of diamond composites designed for tools application for mining industry, hard rocks cutting, able to withstand harsh conditions under heavy dynamical loads. In the present study, both CrB2 micropowder and VN nanopowder additives were used in proportions up to 5 wt.% and 6 wt.%, respectively, together with the basic matrix composition of 51 wt.% Fe, 32 wt.% Cu, 9 wt.% Ni, and 8 wt.% Sn. Addition of both components, CrB2 and VN, appeared to be ad-vantageous in proportion of 2 wt.% and 4 wt.%, respectively. This composition exhibited the highest relative density of 0.9968, better than that without additives. Similarly, the highest values of compressive strength Rcm and flexural strength Rbm were reached for the composite with the same percentage of CrB2 and VN. Compared to the composite with no addition of CrB2 and VN, Rcm improved by almost 70%, while Rbm by 81%. Additionally, the abovementioned additives enhanced the ability of the matrix to prevent the diamond reinforcement from being torn out of the composite, which is very important under harsh working conditions of the cutting tools. The presence of CrB2 micropowder and VN nanopowder promoted densification of the matrix and adhesion between the diamond grits and the Fe‒Cu–Ni–Sn matrix.
Źródło:
Advances in Science and Technology. Research Journal; 2023, 17, 1; 23--34
2299-8624
Pojawia się w:
Advances in Science and Technology. Research Journal
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Microstructure and Fatigue Life of the A359 Alloy Reinforced with Al2O3 after Multiple Remelting
Autorzy:
Pietrzak, K.
Klasik, A.
Maj, M.
Sobczak, J.
Wojciechowski, A.
Powiązania:
https://bibliotekanauki.pl/articles/380378.pdf
Data publikacji:
2018
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
A359 alloy
composite microstructure
mechanical properties
multiple remelting
stop A359
mikrostruktura kompozytu
właściwości mechaniczne
przetapianie wielokrotne
Opis:
The multiple direct remelting of composites based on the A359 alloy reinforced with 20% of Al2O3 particles was performed. The results of both gravity casting and squeeze casting were examined in terms of the obtained microstructure and mechanical characteristics. In microstructure examinations, the combinatorial method based on phase quanta theory was used. In mechanical tests, the modified low cycle fatigue method (MLCF) was applied. The effects obtained after both gravity casting and squeeze casting were compared. It was noted that both characteristics were gradually deteriorating up to the tenth remelting. The main cause was the occurrence of shrinkage porosity after the gravity casting. Much better results were obtained applying the squeeze casting process. The results of microstructure examinations and fatigue tests enabled drawing the conclusion that the A359 alloy reinforced with Al2O3 particles can confer a much better fatigue life behavior to the resulting composite than the A359 alloy without the reinforcement. At the same time, comparing these results with the results of the previous own research carried out on the composites based also on the A359 alloy but reinforced in the whole volume with SiC particles, it has been concluded that both types of the composites can be subjected to multiple remelting without any significant deterioration of the structural and mechanical characteristics. The concepts and advantages of using the combinatorial and MLCF methods in materials research were also presented.
Źródło:
Archives of Foundry Engineering; 2018, 18, 2; 39-44
1897-3310
2299-2944
Pojawia się w:
Archives of Foundry Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Fatigue Life and Microstructure after Multiple Remelting of A359 Matrix Composites Reinforced with SiC Particles
Autorzy:
Klasik, A.
Maj, M.
Pietrzak, K.
Wojciechowski, A.
Sobczak, J.
Powiązania:
https://bibliotekanauki.pl/articles/352210.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
alloy
composite
microstructure
properties
recycling
Opis:
The article presents the results of fatigue life tests and microstructure examinations of A359 alloy matrix composites (F3S.10S and F3S.30S) containing 10 and 30wt% of SiC particles, subjected to multiple remelting by conventional gravity casting. Mechanical characteristics were determined in a modified low cycle fatigue (MLCF) test, enabling rapid estimation of fatigue life and other mechanical parameters in practice of any material. Qualitative and quantitative metallographic examinations were also carried out. The quantitative evaluation of microstructure was performed by computer image analysis. A set of geometrical parameters of the reinforcing particles, pores and eutectic precipitates present in the metal matrix was determined. The relationships between the mechanical parameters, structural characteristics and the number of remelting operations were presented. It was found that up to the fourth remelting, the mechanical characteristics, including fatigue life, are slightly deteriorated but decrease gradually in the subsequent operations of remelting. The observed effect is mainly due to the shrinkage porosity occurring as a result of gravity casting. To eliminate this defect, the use of squeeze casting process was recommended. It has also been shown that multiple remelting can be an easy and economically well-founded alternative to other more expensive recycling methods.
Źródło:
Archives of Metallurgy and Materials; 2016, 61, 4; 2123-2128
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Microstructure characterization by means of X-ray micro-CT and nanoindentation measurements
Autorzy:
Rajczakowska, M.
Stefaniuk, D.
Łydżba, D.
Powiązania:
https://bibliotekanauki.pl/articles/178547.pdf
Data publikacji:
2015
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
micro-CT
nanoindentation
microstructure
composite
Opis:
The aim of this paper is to present an example of the material microstructure characterization with the use of X-ray micro-CT and nanoindentation measurements. Firstly, the current scope of application of the aforementioned techniques is provided within different fields of science. Then, background of each of the methods is presented. The methodology of X-ray micro-CT is described with the emphasis on the Beer’s law formulation. In addition, the basics of the nanoindentation technique are outlined and major formulas for the hardness and Young’s modulus calculation are given. Finally, example results for a concrete sample are presented. The microstructure of the selected material is firstly characterized in terms of geometry using the results from the microtomograhy measurements, e.g., porosity and attenuation profiles, pore and aggregate size distribution, shape factor of pores, etc. Next, the results of the nanoindentation tests are provided, namely the hardness and Young’s modulus versus the height of the sample. The influence of the number of tests and statistical analysis on the final results is underlined.
Źródło:
Studia Geotechnica et Mechanica; 2015, 37, 1; 75-84
0137-6365
2083-831X
Pojawia się w:
Studia Geotechnica et Mechanica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of SiC and GR Reinforcement Particles on the Structure and Functional Properties of Composite Casting E43 MMC Reinforced with SiC Particles
Autorzy:
Boczkal, S.
Dolata, A. J.
Nowak, M.
Powiązania:
https://bibliotekanauki.pl/articles/351537.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
aluminium hybrid composite
microstructure
wear tests
Opis:
The aim of the study was to describe the structure of composites based on the AlSi7Mg2Sr0.03 alloy matrix reinforced with SiC particles added in an amount of 10% and with a mixture of SiC and GR particles added in a total amount of 20%. Studies of the composite structure, were carried out by scanning electron microscopy (SEM). Based on the results of chemical analysis in microregions, an increased content of elements such as Mg, O and Si and of the precipitates was observed at the interface. In many places in the examined sample, GR particles formed partly disintegrated conglomerates with well developed boundaries. The effect of the content of particles of the reinforcing phase on the functional properties of the composite was investigated during studies of abrasion. The lowest mass loss of 5,33mg was obtained for the AlSi7Mg2Sr0.03 alloy reinforced with 10% SiC particles.
Źródło:
Archives of Metallurgy and Materials; 2016, 61, 1; 399-404
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of Annealing Treatment on Deep Drawing Behavior of Q235 Carbon Steel /410/304 Stainless Steels Three-Layer Composite Plate
Autorzy:
Lv, Zehua
Zhang, Zhixiong
Han, Jianchao
Wang, Tao
Powiązania:
https://bibliotekanauki.pl/articles/2106574.pdf
Data publikacji:
2022
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
composite plate
deep drawing
annealing
microstructure
Opis:
Effect of annealing treatment on deep drawing behavior of hot-rolled Q235 carbon steel/410/304 stainless steel three-layer composite plate was investigated. Deep drawability of the unannealed composite plates exhibits a sharp difference for various contact surfaces with the die. The limit drawing ratio (LDR) of the composite plate with the carbon steel contacting the die is 1.75, while it is 1.83 with the stainless steel contacting the die due to the different mechanical responses to the tensile stress at the corner of the die. After annealing at 900°C for 2 h, however, the deep drawabilities of the composite plates both for various contact surfaces with the die are significantly improved and becomes almost identical, which are attributed to the stress relief, the enhanced ductility and the improved interface bonding strength of the hot-rolled component plates during annealing.
Źródło:
Archives of Metallurgy and Materials; 2022, 67, 2; 421--433
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of Boron and Tungsten Carbides on the Properties of TiC-Reinforced Tool Steel Matrix Composite Produced by Powder Metallurgy
Autorzy:
Slokar Benić, Ljerka
Šubić, Jadranko
Erman, Žiga
Powiązania:
https://bibliotekanauki.pl/articles/355244.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
metal matrix composite
steel/TiC composite
powder metallurgy
properties
microstructure
Opis:
The influence of boron carbide and tungsten carbide on the apparent porosity, density, coercive force, hardness and micro-structure of metal matrix composite of the Ferro-TiC type, is presented in this paper. The samples of investigated steel/titanium carbide composite were produced by powder metallurgy process, i.e. by powders mixing and compacting followed by sintering in the vacuum furnace. According to the results, steel/titanium carbide composite materials with addition up to 11.9 vol.% of boron carbide are interesting to detailed investigation as well as materials having more than 17.2 vol.% of tungsten carbide because these compositions show significant changes in hardness and coercive force values.
Źródło:
Archives of Metallurgy and Materials; 2020, 65, 2; 539-547
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of Ceramic Particles on the Microstructure and Mechanical Properties of SAC305 Lead-Free Soldering Material
Autorzy:
Kumar, Manoj Pal
Gergely, G.
Koncz-Horvath, D.
Gacsi, Z.
Powiązania:
https://bibliotekanauki.pl/articles/356293.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
composite solder
SiC particles
microstructure
wettability
microhardness
Opis:
In this study, silicon carbide (SiC) reinforced lead-free solder (SAC305) was prepared by the powder metallurgy method. In this method SAC305 powder and SiC powder were milled, compressed and sintered to prepare composite solder. The composite solders were characterized by optical and scanning electron microscopy for the microstructural investigation and mechanical test. Addition of 1.5 wt.% and 2 wt.% ceramic reinforcement to the composite increased compressive strengths and microhardness up to 38% and 68% compared to those of the monolithic sample. In addition, the ceramic particles caused an up to 55% decrease in the wetting angle between the substrate and the composite solder and porosity was always increased with increase of SiC particles.
Źródło:
Archives of Metallurgy and Materials; 2019, 64, 2; 603-606
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Fabrication and Different Characterization of Graphene Nano Platelets Reinforced Epoxy Nano Composites
Autorzy:
Namdev, Anurag
Purohit, R.
Telang, A.
Kumar, A.
Powiązania:
https://bibliotekanauki.pl/articles/28099532.pdf
Data publikacji:
2023
Wydawca:
Polska Akademia Nauk. Czasopisma i Monografie PAN
Tematy:
nano polymer composite
microstructure
GNP
epoxy
mechanical properties
Opis:
In this research, Graphene nanoplatelets (GNP) reinforced epoxy nano composites were fabricated via magnetic stirrer and ultra sonification assisted hand layup method. The impact of different weight percentage of GNP (0, 0.25, 0.50, and 1.0%) on different characteristics of nano composites was evaluated. The microstructure analysis of developed nano composite was determined by Field emission scanning electron microscopy. It was examined that epoxy nano composites containing 0.5 wt.% GNP have the highest tensile, flexural, and impact strength compared to neat epoxy. The reduction in tensile and flexural strength is achieved at 1% of GNP. Adding more nanofiller to a certain limit causes non-uniform dispersion and agglomeration of nanoparticles, which results in a reduction in properties. The 1% GNP reinforced nano composite has the highest value of shore hardness.
Źródło:
Archives of Metallurgy and Materials; 2023, 68, 2; 823--832
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Impact of Cutting Forces and Chip Microstructure in High Speed Machining of Carbon Fiber - Epoxy Composite Tube
Autorzy:
Allwin Roy, Y.
Gobivel, K.
Vijay Sekar, K. S.
Suresh Kumar, S.
Powiązania:
https://bibliotekanauki.pl/articles/352953.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
composite materials
orthogonal machining
cutting forces
chip microstructure
Opis:
Carbon fiber reinforced polymeric (CFRP) composite materials are widely used in aerospace, automobile and biomedical industries due to their high strength to weight ratio, corrosion resistance and durability. High speed machining (HSM) of CFRP material is needed to study the impact of cutting parameters on cutting forces and chip microstructure which offer vital inputs to the machinability and deformation characteristics of the material. In this work, the orthogonal machining of CFRP was conducted by varying the cutting parameters such as cutting speed and feed rate at high cutting speed/feed rate ranges up to 346 m/min/ 0.446 mm/rev. The impact of the cutting parameters on cutting forces (principal cutting, feed and thrust forces) and chip microstructure were analyzed. A significant impact on thrust forces and chip segmentation pattern was seen at higher feed rates and low cutting speeds.
Źródło:
Archives of Metallurgy and Materials; 2017, 62, 3; 1771-1777
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Numerical calculations of RVE dimensions for two-phase material
Autorzy:
Miedzińska, D.
Niezgoda, T.
Powiązania:
https://bibliotekanauki.pl/articles/242298.pdf
Data publikacji:
2011
Wydawca:
Instytut Techniczny Wojsk Lotniczych
Tematy:
microstructure
two-phase material
metal-ceramic composite
RVE
Opis:
A representative volume element (RVE) is a statistical representation of typical material properties. It should contain enough information on the microstructure thereby be sufficiently smaller than the macroscopic structural dimensions. The paper deals with the numerical calculations of the dimensions of the RVE for a two-phase material microstructure. Two and three dimensional models are taken into consideration. The structure of the samples are developed on the base of randomization of elements belonging to one of the phases. The phases volume share is 50/50%. The following series of the models are analyzed: from 10 x 10 to 100 x 100 elements for 2D samples and from 10 x 10 x 10 to 100 x 100 x 100 elements for 3D samples. The element characteristic dimension is 10 jm. The elastic behavior of the base materials (magnesium and alumina) is taken into account. The quasi-static compression tests of the developed structures are carried out with the use of LS-DYNA computer code. The results are presented as the equivalent Young modulus values and compared to the calculations based on the rule of mixtures. The stabilization of the achieved results allows to assess the dimensions of the RVE for two-phase material with random distribution.
Źródło:
Journal of KONES; 2011, 18, 2; 303-310
1231-4005
2354-0133
Pojawia się w:
Journal of KONES
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Fabrication of Cu-Based SiC Composites by Spark Plasma Sintering of Cu-Nitrate Coated SiC Powders
Autorzy:
Jeong, Y.-K.
Kim, Y. S.
Oh, S.-T.
Powiązania:
https://bibliotekanauki.pl/articles/354995.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
Cu-SiC composite
Cu-nitrate
spark plasma sintering
microstructure
Opis:
An optimum route to fabricate the Cu-based SiC composites with homogeneous microstructure was investigated. Three methods for developing the densified composites with sound interface between Cu and SiC were compared on the basis of the resulting microstructures. Starting with three powder mixtures of elemental Cu and SiC, elemental Cu and PCS coated SiC or PCS and Cunitrate coated SiC was used to obtain Cu-based SiC composites. SEM analysis revealed that the composite fabricated by spark plasma sintering using elemental SiC and Cu powder mixture showed inhomogeneous microstructure. Conversely, dense microstructure with sound interface was observed in the sintered composites using powder mixture of pre-coated PCS and Cu-nitrate onto SiC. The relationship between powder processing and microstructure was discussed based on the role of coating layer for the wettability.
Źródło:
Archives of Metallurgy and Materials; 2017, 62, 2B; 1407-1410
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Microstructure and Properties of Multifibre Composites
Autorzy:
Głuchowski, W.
Rdzawski, Z.
Domagała-Dubiel, J.
Sobota, J.
Powiązania:
https://bibliotekanauki.pl/articles/356505.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
fibrous composite
copper matrix
microstructure
mechanical properties
electrical properties
Opis:
In the study microstructure and properties of composite multifibre copper-base wires are presented. A decision was made to produce wires with “soft” fibres (Al) and “hard” fibres (Fe). In the study the phenomenon occurring on the border of Al-Cu was also analysed. The produced Cu-Al and Cu-Fe composites presented ordered microstructure with the fibres uniformly distributed in the copper matrix. The composites underwent plastic consolidation to the degree which provided satisfactory mechanical and electrical properties. During the drawing the fibres deformed proportionally with copper matrix therefore their content in the cross section remained unchanged.
Źródło:
Archives of Metallurgy and Materials; 2016, 61, 2B; 911-916
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of Volume Percentage of Reinforcement on the Microstructure and Mechanical Properties of an Al6061-T6/SiC Surface Composite Fabricated Through Friction Stir Processing
Autorzy:
Ansari, Abdul Jabbar
Anas, Mohd
Powiązania:
https://bibliotekanauki.pl/articles/2201914.pdf
Data publikacji:
2023
Wydawca:
Stowarzyszenie Inżynierów i Techników Mechaników Polskich
Tematy:
friction stir processing
AMMCs
aluminium metal matrix composite
silicon carbide
microstructure
surface composites
composite material
Opis:
In this research, aluminium metal matrix composites (AMMCs) have been manufactured through friction stir processing (FSP) by reinforcing nano-sized SiC particles in an Al6061-T6 alloy. The consequences of the volume percentage of reinforced SiC particles on mechanical properties and microstructural features were analyzed for the developed AMMCs. Microstructural evaluation of a cross-section of a friction stir processed (FSPed) sample has been conducted through Electron backscatter diffraction (EBSD) Energy dispersive spectroscopy (EDS) and a scanning electron microscope (SEM) technique. Microhardness tests were conducted athwart the cross section of FSPed specimen to obtain microhardness feature. A tensile test of FSPed samples has been conducted on a universal testing machine (UTM). Homogeneous distributions of SiC particles were found in the stir zone without any consolidation of particles. The size of the reinforcement particles was decreased slightly by increasing the volume fraction. It has been found that increasing the volume fraction of SiC particles, enhance the tensile strength and microhardness, but decreases the ductility of the aluminium. The maximum ultimate tensile strength (UTS) and microhardness were obtained as 390 MPa and 150.71 HV, respectively, at 12% volume percentage of reinforcement particles. UTS and microhardness of the FSPed Al/SiC have been improved by 38.29% and 59.48% respectively as compared to Al6061-T6. The brittle nature of the FSPed Al/SiC has increased due to a rise in the volume fraction of nanosized SiC particles, which causes a decrease in ductility.
Źródło:
Advances in Science and Technology. Research Journal; 2023, 17, 2; 247--257
2299-8624
Pojawia się w:
Advances in Science and Technology. Research Journal
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 44

Ta witryna wykorzystuje pliki cookies do przechowywania informacji na Twoim komputerze. Pliki cookies stosujemy w celu świadczenia usług na najwyższym poziomie, w tym w sposób dostosowany do indywidualnych potrzeb. Korzystanie z witryny bez zmiany ustawień dotyczących cookies oznacza, że będą one zamieszczane w Twoim komputerze. W każdym momencie możesz dokonać zmiany ustawień dotyczących cookies