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R. Jasionowski, D. Przetakiewicz and W. Przetakiewicz

Abstract

Seawater is an aggressive environment which causes the necessity of using corrosion protection of hulls of ships. Cathodic protection is an effective prevention method which has been applied in this area for many years. In this method, potential of the ship’s hull is reduced by using galvanic anodes (so-called protectors), which are additionally exposed to cavitation erosion.

Results of cavitation erosion resistance investigation of alloys commonly used in cathodic protection of hulls of ships, are presented in this paper. The tests were carried out on the three, most often applied materials which are zinc, aluminium and magnesium alloys. The investigated samples were subjected to cavitation conditions in a jet-impact laboratory stand. Destruction mechanism of the surface layer affected by working liquid was described. The highest cavitational erosion resistance among all studied alloys was exhibited by AlMg alloy.

Open access

K. Gawdzińska, J. Grabian, M. Szweycer and W. Przetakiewicz

Abstract

The Department of Marine Materials Engineering, Maritime University of Szczecin, has conducted research on the technology of metallic composites, focusing on composite aluminium foams stabilized with ceramic particles. One technology which enables efficient, inexpensive and diversified - in terms of foam structure - control of foam properties is the foundry technology consisting in gas injection into liquid metal. This method requires precise control of the process parameters, especially regarding temperature stabilization, as well as precise injection of the gas into the metal. The process of foaming of liquid aluminium or its silicon alloys can also be conducted using ceramic particles. This is a metallic-ceramic composite foaming process (patent PL 211439 B1). The paper presents the process of structure forming of metallic-ceramic foams.

Open access

K. Gawdzińska, L. Chybowski and W. Przetakiewicz

Abstract

Owing to its properties, metallic foams can be used as insulation material. Thermal properties of cast metal-ceramic composite foams have applications in transport vehicles and can act as fire resistant and acoustic insulators of bulkheads. This paper presents basic thermal properties of cast and foamed aluminum, the values of thermal conductivity coefficient of selected gases used in foaming composites and thermal capabilities of composite foams (AlSi11/SiC). A certificate of non-combustibility test of cast aluminum-ceramic foam for marine applications was included inside the paper. The composite foam was prepared by the gas injection method, consisting in direct injection of gas into liquid metal. Foams with closed and open cells were examined. The foams were foaming with foaming gas consisting of nitrogen or air. This work is one of elements of researches connected with description of properties of composite foams. In author's other works acoustic properties of these materials will be presented.

Open access

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

Abstract

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.

Open access

K. Gawdzińska, L. Chybowski, W. Przetakiewicz and R. Laskowski

Abstract

Metal matrix composites (MMCs) are still scarcely described due to various combinations of used materials and a wide array of technologies. Applying the Failure Mode and Effect Analysis (FMEA) method to describe the quality of metal composite castings may contribute to eliminating specific (characteristic only to these materials) defects. This part of the analysis determines the criticality numbers, meaning the frequency of a given failure, detectability level and significance of a given failure to the group of specific composite casting failures. It contributes to establishing the priority number (P), which is a measure used to assess risk, a notion essential in discussing quality in a composite casting.