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1

Synergia w spiekanych kompozytach ziarnistych

Pędzich Z., Grabowski G., Wojteczko A.

Szkło i Ceramika

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2018

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R. 69, nr 2

20--24

PL

Artykuł opisuje, na wybranych przykładach, możliwości udoskonalenia właściwości fizycznych spiekanych materiałów polikrystalicznych poprzez wytwarzanie kompozytów. Wszelkie technologie spiekania proszków wielofazowych, dążąc do uzyskania jak najwyższego zagęszczenia wyrobu, prowadzą do otrzymania materiałów, które znajdują się w skomplikowanym stanie naprężeń wewnętrznych. Jednocześnie spiekanie układów wielofazowych przebiega w sposób, który zdecydowanie modyfikuje parametry mikrostrukturalne finalnego materiału. Kolejną cechą, oczywistą z punktu widzenia definicji kompozytu, jednak konieczną do podkreślenia, jest obecność granicy międzyfazowej, która może w istotny sposób modyfikować właściwości materiałów. W pracy, na przykładzie realnych tworzyw z układu Al2O3/ZrO2, wskazano właściwości kompozytów polikrystalicznych, które mogą zostać poprawione w kompozycie w sposób synergiczny – takie jak odporność na kruche pękanie, podatność na pękanie podkrytyczne, odporność na zużycie kawitacyjne.

EN

The article describes, on the selected examples, the possibilities of improving the physical properties of sintered polycrystalline materials by producing composites. All technologies of sintering multi-phase powders aiming at obtaining the highest density of the product, lead to obtaining materials that are in a complicated state of internal stresses. At the same time, sintering of multiphase systems proceeds in a way that significantly modifies the microstructural parameters of the final material. Another feature, obvious from the point of view of the definition of a composite, but necessary to emphasize, is the presence of an interface, which can significantly modify the properties of materials. In the work, on the example of real materials from the Al2O3/ZrO2 system, the properties of polycrystalline composites, which can be improved in the composite in a synergistic manner, such as fracture toughness, subcritical crack resistance, resistance to cavitation wear, are indicated.

2

Możliwości poprawy odporności na erozję kawitacyjną staliwnych zaworów hydraulicznych

Orłowicz A.W., Mróz M., Radoń M., Kupiec B., Jacek M., Sobolewska P.

Przegląd Spawalnictwa

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2018

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R. 90, nr 4

56--58

PL

Powierzchnie wewnętrzne gniazd uszczelniająco-odwadniających zaworów hydraulicznych są zwykle odwzorowane przez wkładki wykonane ze stopu miedzi, które są mechanicznie połączone z korpusem zaworu. Wskutek gwałtownych zmian ciśnienia wody, wkładki te mogą ulec poluzowaniu, co powoduje nieszczelność zaworów. W pracy zaproponowano nowe rozwiązanie poprzez zastosowanie powłoki natryskiwanej plazmowo. Przedstawiono wyniki badań odporności na erozję kawitacyjną dotychczas stosowanego materiału wkładki ze stopu CuZn39Pb2Al oraz materiału powłoki wykonanej z proszku WCCoCr 86104. Oceniono strukturę geometryczną powierzchni kraterów kawitacyjnych (parametr Rt). Stwierdzono, że powłoka naniesiona plazmowo charakteryzuje się zdecydowanie wyższą odpornością na erozję kawitacyjną, w porównaniu do dotychczas stosowanego materiału wkładki ze stopu CuZn39Pb2Al.

EN

Inner surfaces of sealing-draining seats in hydraulic valves are usually reproduced by inserts made of a copper alloy joined mechanically with valve housing. As a result of sudden variations in water pressure, they can be subject to loosening which leads to deterioration of valve tightness. In the paper, a new solution is proposed for finishing surfaces of valve seats by application of a plasma-sprayed coating. The solution is validated by results of cavitation erosion resistance test performed for both the CuZn39Pb2Al alloy used earlier for the inserts and the material of coating made of WCCoCr 86104 powder. The resistance assessment was based on geometrical structure of cavitation craters (parameter Rt). It has been found that the plasma-sprayed coating demonstrated a definitely higher resistance to cavitation erosion compared to CuZn39Pb2Al alloy used earlier for valve seat inserts.

3

A Possibility to Improve Resistance of Cast-iron Hydraulic Valves to Cavitation Wear

Orłowicz A. W., Tupaj M., Mróz M., Kupiec B., Jacek M., Radoń M.

Archives of Foundry Engineering

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2018

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Vol. 18, iss. 4

31--34

EN

A common problem encountered in hydraulic valves is a progressing deterioration of tightness of their water flow cutting-off seats. The seats are provided usually with a copper-alloy insert joined mechanically with cast-iron valve housing. The problem of unreliability of such joints can be solved by providing surface of the seat with a coating, deposited with the use of HVOF method and resistant to abrasive and cavitation wear. The tests were carried out for a sealing-draining seat insert made of CuZn39Pb2Al brass used to date and a specimen taken from the cast-iron valve housing which was the substrate for a plasma-sprayed coating of powder containing 86.1% Cr, 7.2% Ni, and 6.7% C. The coating, 345 ± 15 μm thick, was characterized with good quality of bonding with cast-iron substrate and high compactness of the material. The cavitation wear test on materials used in the study were carried out with the use of Vibra-Cell ultrasonic liquid processor (Sonics) equipped with a piezoelectric probe operating at the frequency of 20 kHz. Based on profilograms taken along a line crossing centers of cavitation craters, measurements of the height parameter Rt, and microscopic observations of surfaces it has been found that the coating plasma-sprayed onto substrate of nodular cast iron demonstrated higher resistance to cavitation compared to copper-alloy inserts used so far in cast-iron hydraulic valves. Cavitation craters on the material used typically for valve seats to date were more distinctly outlined and deeper compared to craters observed on the coating. Larger were also sizes of local tear-outs which resulted in larger difference between the peaks line and the valleys line.

4

Numerical analysis of the cavitation effect occurring on the surface of steel constructional elements

Linek T., Tański T., Borek W.

Archives of Materials Science and Engineering

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2017

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Vol. 85, nr 1

24--34

EN

Purpose: The aim of the work is to present the results of own investigations concerning the geometric optimisation of constructional elements working in the environment of cavitation wear together with a computer numerical analysis. The engineering material used for constructional elements working in the environment of cavitation wear is steel, commonly used for pressure devices working at elevated temperatures, P265GH, acc. to PN-EN 10028:2010. Design/methodology/approach: SOLID EDGE ST 7 software, for synchronous designing, was used for the parametrisation of the shape, distribution, configuration and size of openings in constructional elements. Five models, with a different spacing and number of openings, were proposed for the optimisation of internal geometry of the cavitation generator and for the investigations; the models were then subjected to a numerical analysis using specialised software, ANSYS FLUENT v.16, employed for modelling the effects associated with fluid mechanics (Computational Fluid Dynamics - CFD). The data was implemented for this purpose in the software used, such as: density, yield point, tensile strength, heat conductivity coefficient for steel P265GH, material surface roughness, medium (water) flow rate, constant pressure loss of medium, pressure of steam saturation in a medium; and such data was called boundary conditions. Findings: The authors’ principal accomplishment is the optimisation of the shape, the selection of the most appropriate geometry of a constructional element generating the maximum number of cavity implosions in the environment of a flowing medium (water), with the use of computer tools dedicated to engineering design: a 3D and numerical computer analysis of fluid mechanics, CFD. Moreover, an attempt was made in this work to develop a methodology for characterisation of the phenomena accompanying the environment of cavitation wear. Practical implications: A possibility of examining the phenomena and a process of wear of a constructional element made of P265GH grade steel for pressure devices working at elevated temperatures. The demonstration and presentation of potential places, areas and sizes of erosion existing on constructional elements working in the environment of cavitation wear.

5

Cavitation Erosion Resistance Of FeAl Intermetallic Alloys And Al2O3 – Based Ceramics

Jasionowski R., Pędzich Z., Zasada D., Przetakiewicz W.

Archives of Metallurgy and Materials

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2015

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Vol. 60, iss. 2A

671--675

EN

The problem of the devastation of fluid-flow machinery components is very complex, because it consists of processes of erosion and corrosion. The most dangerous factor is the cavitation phenomenon, which is very difficult to eliminate through the use of design solutions. Usage of materials with greater resistance to cavitation erosion seems to be an obvious effective method of prevention. Such materials as FeAl intermetallic alloys and ceramic materials may be considered as reasonable candidates for this purpose. In the presented work, cavitation erosion resistance of FeAl intermetallic alloys and Al2O3 – based ceramic materials, was investigated and compared.

PL

Problem niszczenia elementów maszyn przepływowych jest bardzo złożony, ponieważ składa się z procesów erozyjnych i korozyjnych. Najbardziej niebezpiecznym czynnkiem jest zjawisko kawitacji, które bardzo trudno jest wyeliminować poprzez stosowanie rozwiązań konstrukcyjnych. Skutecznym rozwiązaniem jest stosowanie materiału o większej odporności na erozję kawitacyjną. Takimi materiałami mogą być stopy intermetaliczne FeAl lub materiały ceramiczne. W pracy przedstawiono porównanie odporności na erozję kawitacyjną stopów intermetalicznych FeAl i materiałów ceramicznych na bazie Al2O3.

6

EBSD Strain Analysis of CuZn10 Alloy in As-cast State and After Plastic Working and Annealing During Cavitational Wear

Jasionowski R., Zasada D., Polkowski W.

Archives of Foundry Engineering

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2013

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Vol. 13, iss. 2 spec.

53--60

EN

Electron backscatter diffraction (EBSD) system in conjunction with scanning electron microscope (SEM) allows performing full material characterization which include analysis of individual grain orientations, crystal orientation, global and local texture, phase identification and distribution or microstrain mapping. EBSD technique may be also applied for assessing lattice strain introduced during local plastic deformation due to its close relationship with development of dislocation substructure. The aim of this study was analysis of surface deformation by EBSD method of CuZn10 alloy in as-cast state and after plastic working and annealing, with different grain size at the beginning of the cavitation destruction process. The local changes of plastic deformation inside each grain were expressed by Grain Orientation Spread (GOS) and Kernel Average Misorientation (KAM) parameters.

7

Destruction Mechanism of Z10400 Zn-based Alloy Subjected to Cavitational Erosion

Jasionowski R., Zasada D., Polkowski W.

Archives of Foundry Engineering

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2013

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Vol. 13, iss. 2 spec.

48--52

EN

Z10400 zinc-based alloy has a very good casting properties and high resistance to corrosion. These two advantages make that Z10400 zinc-based alloy is commonly used for cathodic protection of hulls of ships. Cathodic anodes made of Z10400 zinc-based alloy in the propeller and flap rudder areas are also additionally exposed to the cavitation erosion. The aim of this work was to determine the cavitation erosion resistance of Z10400 zinc-based alloy, which is applied as protectors in cathodic protection of hulls of ships. The examination of cavitational erosion was carried out on a jet-impact measuring device. Study of the mechanism of the destruction of Z10400 alloy based on analysis was performed with scanning electron microscope Quanta 3d FEG and electron back scattered diffraction (EBSD) method.

8

The method for determination of the beginning of cavitational wear through comparison of mass decrement and destroyed surface increment on the example of FeAl36 alloy

Jasionowski R., Przetakiewicz W., Zasada D.

Archives of Foundry Engineering

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2011

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Vol. 11, iss. 2 spec.

103--107

EN

Cavitational erosion is the phenomenon of mechanical destruction of a material due to the implosion of cavitational bubbles. Cavitational resistance is the ability of material to oppose the effect of cavitation being determined most frequently by analysing the kinetics of destruction of a material being examined on a given device. Materials with the highest resistance to cavitational destruction are characterised by the longest incubation period and smaller destruction rate. The carried out laboratory tests of resistance to cavitational erosion showed that determination of the beginning of cavitational wear is very difficult because the kinetics of cavitational destruction depends on: test bed type, tested material and test time. The aim of presented study was to propose a method for determination of the beginning of cavitational wear through comparison of mass decrement and destroyed area increment curves on the example of FeAl36 intermetallic alloy subjected to the cavitational wear on a flux-impact test stand.

9

The effect of structure on the cavitational wear of FeAl intermetallic phase-based alloys with cubic lattice

Jasionowski R., Przetakiewicz W., Zasada D.

Archives of Foundry Engineering

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2011

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Vol. 11, iss. 2 spec.

97--102

EN

The process of cavitational erosion induces destruction of a material which consists of plastic strains, mass decrements, phase changes, grain fragmentation and surface micro- and macro-geometry changes. Heterogeneity of this process causes the destruction of a solid body due to cavitation to be hard to predict. Examinations of many materials showed that the course of cavitation wear is basically affected by structure which allows for orientation and size of grains and their shape, fraction of small and large angle boundaries, type of phases (in multi-phase materials), interposition of their grains, grain volume fraction as well as distribution of impurities and possible defects of materials, such as cracks, pores and non-metallic inclusions. The aim of this study was to examine the effect of structure on the cavitational wear of FeAl intermetallic phase-based alloys with cubic lattice.

10

The influence of grain size of Ni3Al alloy on cavitation wear of Ni3Al intermetallic after cold rolling and recovery during incubation period

Zasada B., Zarański Z., Jasionowski R.

Inżynieria Materiałowa

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2010

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Vol. 31, nr 3

650-653

EN

Study of the grain size influence on cavitation wear of Ni3Al-based alloy with additives of zirconium and boron, after homogenization annealing, cold-rolling and heat-treatment, is presented in this work. Samples with grain size of 5, 20 or 40 ~m were obtained as a result of application of different plastic working and heat treatment parameters. Cavitation wear tests were performed with a beam impact test station. Based on the results of complex structural and topographic analysis, the mechanism of the destruction of the surface layer due to the cavitation, has been described. We have observed that initial microcracks and material decrements were created at the grain boundaries zones. Further devastation of investigated alloy surface is an effect of material strengthening and spallation in the critically deformed areas or whole grains. Results of cavitation tests of investigated Ni3Al-based alloy have not shown significant grain size influence on this type of erosive resistance. While, it was found that Ni3Al-based alloys after plastic working and heat treatment posses cavitation resistance similar to Ni3Al and FeAl alloys in as-cast state. Additionally, investigated Ni3Al-based alloy has demonstrated better cavitation resistance during incubation period in comparison to aluminum alloys, copper alloys and widely applied steels.

PL

W pracy przedstawiono analizę wpływu wielkości ziarna w stopie na osnowie fazy międzymetalicznej Ni3Al na rozwój zużycia kawitacyjnego w okresie inkubacji. Badania prowadzono na stopie Ni3Al z dodatkiem boru i cyrkonu, w stanie po wygrzewaniu ujednorodniającym, przeróbce plastycznej i cieplnej. W wyniku kontrolowanego procesu walcowania i rekrystalizacji badanego stopu na osnowie fazy międzymetalicznej Ni3Al uzyskano wielkość ziarna osnowy na poziomie 5, 20 lub 40 um. Badania odporności na zużywanie kawitacyjne przeprowadzono na stanowisku pomiarowym typu strumieniowo-uderzeniowego. Na podstawie przeprowadzonych kompleksowych badań strukturalnych i topograficznych opisano mechanizm niszczenia warstwy wierzchniej poddanej oddziaływaniu erozji kawitacyjnej. Zaobserwowano, że pierwsze mikropęknięcia i ubytki materiału, w wyniku oddziaływania strumienia cieczy roboczej, powstają w strefach granic ziaren. Dalsze niszczenie powierzchni analizowanego stopu następuje na skutek umacniania i wypadania krytycznie odkształconych obszarów lub całych ziaren. Na podstawie przeprowadzonych badań zużycia kawitacyjnego w okresie inkubacji nie odnotowano istotnego wpływu wielkości ziarna na ten typ erozji. Stwierdzono natomiast, że stopy po przeróbce plastycznej i cieplnej wykazują porównywalną odporność na zużycie kawitacyjne do odlewniczych intermetali Ni3Al i FeAl. Odnotowano, że analizowany stopy w okresie inkubacji, charakteryzuje się lepszą odpornością na zużycie kawitacyjne w porównaniu ze stopami aluminium, miedzi oraz powszechnie wykorzystywanymi stalami.

11

Odporność na erozję kawitacyjną wybranych stopów na osnowie faz międzymetalicznych FeAl i Ni3Al

Jasionowski R., Przetakiewicz W., Zasada D., Grabian J.

Inżynieria Materiałowa

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2006

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Vol. 27, nr 3

160-163

PL

W pracy przedstawiono wyniki badań odporności na zużycie kawitacyjne wybranych stopów intermetalicznych z układu Fe-Al i Ni3Al, przy użyciu stanowiska pomiarowego typu strumieniowo-uderzeniowego. Stopy te wykazały dobrą odporność na ten typ erozji w porównaniu ze stopami miedzi. Większą odporność na zużycie kawitacyjne wykazały stopy intermetaliczne z układu Fe-Al.

EN

The paper presents results of investigation cavitation erosion resistance of the chosen alloys based on intermetallic FeAl and Ni3Al phase, using the flux-impact measuring device. This intermetallic alloys proved to have good resistance from this type of erosion in comparison with copper-base alloys. It was found the good resistance intermetallic FeAl of cavitation erosion.

12

Zużycie ceramiki TZP i kompozytu TZP/WC w różnych warunkach

Łukasik K., Pędzich Z.

Tribologia

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2001

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nr 6

1087-1101

PL

Artykuł porównuje zużycie spieków polikrystalicznego dwutlenku cyrkonu (TZP) i kompozytu ziarnistego TZP/WC w dwu różnych testach zużycia. Pierwszy to próba rysowania (scratch test), drugi próba niszczenia kawitacyjnego. Wyniki testów pokazują, że wprowadzenie do osnowy TZP węglika WC poprawia wydatnie odporność na zarysowania, obniża jednak zdecydowanie odporność na zużycie kawitacyjne.

EN

Presented paper compares wear rates of TZP and TZP/WC sintered bodies tested in different conditions - scratch test and cavitation wear test. Results of investigations clearly indicate that introduction of WC particles into TZP matrix improves resistance for scratching. But such composite is much weaker compared to the matrix material during cavitation wear test.