Melt infiltration of ceramic preforms for functionally graded materials

Erdamar, Caner
The aim of this work was to produce ceramic-metal composite which shows combination of high hardness and high flexural strength by a combination of hard front layer and tough back layer by Functionally Graded Materials (FGM) process. Composition is the most important variable to obtain gradual changing green/bulk density and/or porosity which are the requirements of an FGM sample. Three different layers of FGM with gradual changing green density and/or porosity were pressed following by ball milling of different weight % of boron carbide and silicon carbide particles with different particle sizes. Each green body was sintered, and then, pressure melt infiltration process was applied to fill porosities with aluminum alloy in order to reach the near theoretical density. Finally, the material was characterized by phase analysis, particle size and distribution analysis, green/bulk density and porosity measurements, optical microscope and SEM analyses, three point bending test, hardness measurement and XRD analysis. Flexural strength measured for FGM B4CSiC-Al composites having dimensions of 12 cm length, 4 cm width, 2.3 cm thickness is nearly 348 ± 40 MPa.


Crack problem for a functionally graded layer on an elastic foundation
Kadıoğlu, Fevzi Suat; Yahşi, Selçuk (1998-01-01)
In this paper internal and edge crack problems for an FGM layer attached to an elastic foundation are considered. This model can be used to simulate circumferential crack problem for a thin walled cylinder. It is assumed that the mechanical properties of the layer are varying in thickness direction. Crack is assumed to be perpendicular to the surfaces. For this geometry stress intensity factors are calculated for a number of different crack surface tractions. By using the calculated stress intensity factors...
Mixed-mode fracture analysis of orthotropic FGM coatings under mechanical and thermal loads
İlhan, Küçük Ayşe; Dağ, Serkan; Department of Mechanical Engineering (2007)
In this study, it is aimed to investigate the mixed-mode fracture behavior of orthotropic functionally graded material (FGM) coatings bonded to a homogeneous substrate through a homogeneous bond-coat. Analytical and computational methods are used to solve the embedded cracking problems under mechanical or thermal loading conditions. It is assumed that the material property gradation of the FGM coating is in the thickness direction and cracks are parallel to the boundaries. The principal axes of orthotropy a...
Development of functionally graded aluminum matrix composite materials for defense industry applications
Yılmaz, Taha; Kalkanlı, Ali; Department of Metallurgical and Materials Engineering (2019)
Functionally graded materials (FGMs) are advanced class of composite materials that have a gradual change in composition and structure over the entire material and many different properties can be obtained by altering the structure. Therefore, they have many different application areas. This study aims to develop functionally graded aluminum matrix composite materials for defense applications. Firstly, porous ceramic pellets and preforms, made of alumina (Al2O3) and olivine ((Mg,Fe)SiO4), were produced with...
Microstructural characterization and tensile properties of hot pressed Al-SiC composites prepared from pure Al and Cu powders
Ögel, Bilgehan; Gürbüz, Rıza (2001-03-31)
A conventional hot pressing method was used to produce Al-Cu-SiC particulate metal matrix composites. The matrix alloy was prepared from elemental powders of Al and 5 wt.% Cu. The composite comprises 13.3 or 27.2 vol.% SiCp with an average size of 10 mum. The powder mixtures were hot pressed uniaxially under nitrogen atmosphere. It is shown that Cu aids in the Formation of a liquid phase. Practically pore free structures are obtained after pressing at 600 degreesC, Elastic modulus, tensile strength and yiel...
Nonlinear Vibrations of a Functionally Graded Material Microbeam with Geometric Nonlinearity
Uz, Canan; Ciğeroğlu, Ender (2017-02-02)
In this paper, nonlinear vibration analysis of micro scale functionally graded material (FGM) beams with geometric nonlinearity due to large deflection is studied using modified couple stress theory (MCST). MCST is a nonlocal elasticity theory which includes a material length scale parameter since the size of an atomic microstructure becomes comparable to the length of the microbeam. Equations of motion of the micro scale FGM beam are obtained by using Hamilton's principle. Nonlinear free vibrations of the ...
Citation Formats
C. Erdamar, “Melt infiltration of ceramic preforms for functionally graded materials,” Thesis (M.S.) -- Graduate School of Natural and Applied Sciences. Metallurgical and Materials Engineering., Middle East Technical University, 2019.