The Influence of Al2O3 Powder Morphology on the Properties of Cu-Al2O3 Composites Designed for Functionally Graded Materials (FGM)

Journal of Materials Engineering and Performance, Jul 2016

In order to meet the requirements of an increased efficiency applying to modern devices and in more general terms science and technology, it is necessary to develop new materials. Combining various types of materials (such as metals and ceramics) and developing composite materials seem to be suitable solutions. One of the most interesting materials includes Cu-Al2O3 composite and gradient materials (FGMs). Due to their potential properties, copper-alumina composites could be used in aerospace industry as rocket thrusters and components in aircraft engines. The main challenge posed by copper matrix composites reinforced by aluminum oxide particles is obtaining the uniform structure with no residual porosity (existing within the area of the ceramic phase). In the present paper, Cu-Al2O3 composites (also in a gradient form) with 1, 3, and 5 vol.% of aluminum oxide were fabricated by the hot pressing and spark plasma sintering methods. Two forms of aluminum oxide (αAl2O3 powder and electrocorundum) were used as a reinforcement. Microstructural investigations revealed that near fully dense materials with low porosity and a clear interface between the metal matrix and ceramics were obtained in the case of the SPS method. In this paper, the properties (mechanical, thermal, and tribological) of composite materials were also collected and compared. Technological tests were preceded by finite element method analyses of thermal stresses generated in the gradient structure, and additionally, the role of porosity in the formation process of composite properties was modeled. Based on the said modeling, technological conditions for obtaining FGMs were proposed.

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The Influence of Al2O3 Powder Morphology on the Properties of Cu-Al2O3 Composites Designed for Functionally Graded Materials (FGM)

Journal of Materials Engineering and Performance The Influence of Al O Powder Morphology 2 3 on the Properties of Cu-Al O Composites Designed 2 3 for Functionally Graded Materials (FGM) Agata Strojny-Ne˛ dza 0 Katarzyna Pietrzak 0 Witold We˛ glewski 0 0 Agata Strojny-Ne ̨dza and Katarzyna Pietrzak, Institute of Electronic Materials Technology , 133 Wolczynska str., 01-919 Warsaw , Poland; and Witold Weglewski, Institute of Fundamental Technological Research , 5B Pawinski str., 02-106 Warsaw , Poland. Contact In order to meet the requirements of an increased efficiency applying to modern devices and in more general terms science and technology, it is necessary to develop new materials. Combining various types of materials (such as metals and ceramics) and developing composite materials seem to be suitable solutions. One of the most interesting materials includes Cu-Al2O3 composite and gradient materials (FGMs). Due to their potential properties, copper-alumina composites could be used in aerospace industry as rocket thrusters and components in aircraft engines. The main challenge posed by copper matrix composites reinforced by aluminum oxide particles is obtaining the uniform structure with no residual porosity (existing within the area of the ceramic phase). In the present paper, Cu-Al2O3 composites (also in a gradient form) with 1, 3, and 5 vol.% of aluminum oxide were fabricated by the hot pressing and spark plasma sintering methods. Two forms of aluminum oxide (aAl2O3 powder and electrocorundum) were used as a reinforcement. Microstructural investigations revealed that near fully dense materials with low porosity and a clear interface between the metal matrix and ceramics were obtained in the case of the SPS method. In this paper, the properties (mechanical, thermal, and tribological) of composite materials were also collected and compared. Technological tests were preceded by finite element method analyses of thermal stresses generated in the gradient structure, and additionally, the role of porosity in the formation process of composite properties was modeled. Based on the said modeling, technological conditions for obtaining FGMs were proposed. functionally gradient materials; hot pressing; metal matrix composites; microstructure; spark plasma sintering; thermal conductivity 1. Introduction Rapid progress in technology requires new materials with special properties. Composite materials are an answer to the constantly increasing demand for materials with improved structural and operating parameters, and enable required properties and features to be shaped deliberately to a degree unavailable for traditional types of monolithic materials. Metal matrix composites (MMCs) and functionally graded materials (FGMs) were developed to reach better parameters, especially high-temperature resistance to wear and corrosion, mechanical strength, thermal and electric conductivity, and magnetic properties. In particular, FGMs make suitable candidates for materials whose properties vary depending on the distance from the material surface (Ref 1). The idea of functionally graded materials was intensively developed in early 1984 in Japan, where it was proposed to increase adhesion and minimize the thermal stress in metal-ceramic composites developed for reusable rocket engines (Ref 2). At present, graded materials are widely used in power, aircraft, aerospace, electronics, automotive, and chemical industries (Ref 3). Copper is characterized by high electrical and thermal conductivity, which makes copper a great prospective component of metal matrix composite materials. However, poor adhesion to widely used reinforcements, chemical reactions at interfaces, and quick oxidization of Cu can create serious problems with the formation of the strong bonds at the interface between composite components (Ref 4, 5). Copper matrix composites with different ceramic reinforcements (AlN, SiC, C, Al2O3) are extensively used in aerospace industry in products that are subjected to severe thermal and mechanical loadings such as rocket thrusters and components in aircraft engines (Ref 6, 7). A thruster is a drive unit of stabilizing motors used in rockets. It constitutes an element of an outlet in combustion engines, entered by gases from the combustion chamber. This particular part is exposed to the unfavorable impact of external factors such as high temperature, abrasive wear, and corrosion, hence being a frequently replaced element of the engine. The most common defects include layer degradation or numerous cracks resulting from a chemical reaction with exhaust gases (Ref 8). At present, a material used for thrusters is copper alloy, showing low resistance to wear. The application of a gradient material composed of Cu-Al2O3 composite layers with a slight addition of aluminum oxide is expected to enhance tribological properties, at the same time preserving good thermal properties. The selection process of the composition of the gra (...truncated)


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Agata Strojny-Nędza, Katarzyna Pietrzak, Witold Węglewski. The Influence of Al2O3 Powder Morphology on the Properties of Cu-Al2O3 Composites Designed for Functionally Graded Materials (FGM), Journal of Materials Engineering and Performance, 2016, pp. 3173-3184, Volume 25, Issue 8, DOI: 10.1007/s11665-016-2204-3