Si3N4/SiC Nanocomposites: Microstructural Analysis & Strength

This report presents a detailed microstructural analysis and strength estimation of Silicon Nitride/Silicon Carbide (Si3N4/SiC) nanomaterials using ANSYS software. The study investigates the mechanical properties of the nanocomposite, including Young’s Modulus, creep resistance, and fracture toughness, to estimate the material's strength. Different mass fractions of the nanomaterial are simulated, and the results are compared with experimental data from existing literature. The analysis reveals that SiC dispersion enhances the toughness and strength of the material by inhibiting the propagation of cracks within the granular boundaries of the matrix. The report also covers experimental methods, including X-ray diffraction and oxidation behavior analysis, to provide a comprehensive understanding of the nanomaterial's properties. Desklib offers a wealth of similar solved assignments and past papers for students seeking to deepen their understanding of materials science and engineering.

Microstructural Analysis of Nanomaterials 1
MICROSTRUCTURAL ANALYSIS AND STRENGTH ESTIMATION OF NANO
COMPOSITES
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Microstructural Analysis of Nanomaterials 2
Abstract
This study details the simulation of a Silicon nitride/Silicon Carbide nanomaterials were
simulated using the ANSYS software in order to analyze the microstructure of the nanomaterials
and aid in the estimation of the strength of the material. The mechanical properties of the
modelled nanocomposite were used to estimate the fracturing toughness of the material which
translates to the strength of the material. Different mass fractions of the nanomaterial were used
to simulate the model and a comparative analysis of the experimental values from previous
literature on the subject and the simulated results was used. Some of the mechanical properties
that were analyzed in this study include the Young’s Modulus, Creep rates and resistances of
materials, fracture toughness, strength, and even the oxidation behaviors. The study helped to
determine that the methodology of SiC dispersion is able to improve the mechanical properties of
toughness and strength of the material due to the inhibition status of the SiC nanocomposites
within the granular boundaries of the matrix. This was further rationalized following insights
from the microstructural analysis of the material.

Microstructural Analysis of Nanomaterials 3
Acknowledgement
I would like to acknowledge the supervision and guidance of my moderators, who have
worked together with me to ensure that this project is completed successfully. I would also like
to acknowledge the support that my family has shown me during the execution of this project, as
well as the contribution of my friends and classmates to my ability to complete the project on
time.
Specifically, I would like to appreciate my supervisor in this project, xxxx, who offered
his expert advice to ensure that the report was executed in the right conditions and following all
the necessary instructions. My gratitude towards him is as a result of the patience, as well as the
academic and professional advice that he offered throughout this project to ensure that excellent
results are obtained for the project. This provided me with the right conditions and guidelines for
conducting the study and making the right inferences. His contribution was particularly helpful
in the comprehension of the changes of the mechanical behavior of the nanomaterial when the
nanoparticle phase continues to be added while making a nanomaterial. This allowed me to be
aware of the impact of these mechanical behavior changes and how they are related to the
microstructure of the nanocomposite.

Microstructural Analysis of Nanomaterials 4
Table of Contents
Chapter 1: Introduction...............................................................................................................................9
Aim and Objectives................................................................................................................................10
Scope.....................................................................................................................................................10
Chapter 2: Literature Review.....................................................................................................................11
Mechanical Behavior of Ceramic Nanomaterials...................................................................................11
The Si3 N 4 /SiC nanomaterial.............................................................................................................13
Microstructural Conditions of the Si3 N 4 /SiC nanomaterial.............................................................13
Preparation of Si 3 N 4 /SiC nanomaterial...........................................................................................16
Chapter 3: Methodology...........................................................................................................................17
Experimental Analysis............................................................................................................................17
ANSYS simulation...................................................................................................................................19
Chapter 4: Research Results and Discussion..............................................................................................20
ANSYS Simulation..................................................................................................................................20
Geometrical Simulation.....................................................................................................................21
Material Application..........................................................................................................................21
The Equivalent Deformation..............................................................................................................22
Stress –Strain Curve of Loading in Tensile and Compressive Conditions...........................................23
Equivalent Von Misses.......................................................................................................................25
Experimental Methods..........................................................................................................................26
Microstructural Analysis....................................................................................................................26
X-Ray diffraction................................................................................................................................27
Mechanical Properties.......................................................................................................................28
Creep Behavior..................................................................................................................................30
Oxidization behavior..........................................................................................................................31
Discussion..............................................................................................................................................33
Chapter 5: Conclusion and Recommendations..........................................................................................36
Chapter 6: References...............................................................................................................................40
Chapter 6: Appendix..................................................................................................................................42

Microstructural Analysis of Nanomaterials 5
List of Figures
Figure 1: Overall geometry in ANSYS.........................................................................................................20
Figure 2: Material Application...................................................................................................................21
Figure 3:Equivalent deformation...............................................................................................................22
Figure 4: The curve of tensile stress against strain for different loading conditions.................................23
Figure 5: The curve of compressive stress against strain for different loading conditions........................24
Figure 6: Equivalent Von Misses................................................................................................................24
Figure 7: SEM microstructure of Plasma Etched Si3 N4/SiC nanomaterial with a SiC reinforcement of 1%
by weight...................................................................................................................................................26
Figure 8: SEM microstructure of Plasma Etched Si3 N4/SiC nanomaterial with a SiC reinforcement of 5%
by weight...................................................................................................................................................26
Figure 9: X-ray diffraction results...............................................................................................................27
Figure 10: A graph depicting the behavior of creep rate in relation to temperatures at different stresses.
.................................................................................................................................................................. 29
Figure 11: surface layer of oxidation behavior of Si3 N4/SiC nanomaterial with 5% weight SiC.................30
Figure 12: surface layer of oxidation behavior of Si3 N4/SiC nanomaterial with 5% weight SiC.................31
Figure 13: surface layer of oxidation behavior of Si3 N4/SiC nanomaterial with 1% weight SiC.................31
Figure 14: surface layer of oxidation behavior of Si3 N4/SiC nanomaterial with 1% weight SiC.................32

Microstructural Analysis of Nanomaterials 6
List of Tables
Table 1: A summary of the mechanical properties of the materials through experimentation analysis. .28

Microstructural Analysis of Nanomaterials 7
Abbreviations
SiC -Silicon Carbide
Si3N4- Silicon Nitride

Microstructural Analysis of Nanomaterials 8
Microstructural Analysis and Strength Estimation of Nano Composites
Chapter 1: Introduction
Nanocomposites refer to multiphase solid materials where one of the phases of the
material has either one or two or even three of its dimensions being very small at less than 100
nanometers. Nanomaterials also refer to materials whose structure has distances in the nanoscale
between the individual phases that comprise of the material. The nanoscale implies that the
dimensions of the building blocks utilized in the design and development of nanomaterials is in
the nanometer range for purposes of improving their mechanical and physical properties.
Choosing nanocomposite materials whose nanostructures have distance of around 100 nm
ensures that the flexibility of the particles is reinforced, and also that the dislocation movement
of the nanoscale phase matrix thus achieving higher material strengths (Kašiarová, et al., 2009).
Microstructurally, the materials depict exceptionally high levels of surface to volume
ratio of the non-scale phase thus guaranteeing a higher degree of reinforcement. It also results
into a high aspect ratio, as the nanoscale material can be made of materials with different
structures ranging from particles to yield nanoparticles, sheets or even fibers that yield
nanotubes. Due to the dimensions of the nanoscale phase, the surface area of the interface of the
reinforcement and the matrix of the composite is greater in magnitude in these materials than the
other materials and this yields higher amounts of strength of the material. In addition, since the
surface area of reinforcement in nanomaterials is exceptionally high, there is very little impact
that the nanoscale phase reinforcement material affects the physical and mechanical properties of
the entire material (Kašiarová, et al., 2009). Instead, the nanoparticles incorporates into the
matrix may facilitate the electrical and thermal properties of the material, as well as the
mechanical parameters of resistance to damage and wear, as well as stiffness and strength. The

Microstructural Analysis of Nanomaterials 9
nanoscale phase of the nanomaterial is incorporated into the matrix phase during the
manufacturing and processing stages where the nanoscale phase material is literally dispersed
into the matrix phase. The quantity of the nanoscale phase material dispersed into the matrix
phase is determined through its mass fraction, which is defined as the percentage of the
nanoscale phase in the matrix by weight (Biasini and Bellosi, 2008). The arrangement of this
nanoscale phase and its orientation within the matrix is also important in the determination of the
thermal conductivity of the nanomaterial.
Aim and Objectives
The aim of this study was to conduct a microstructural analysis and strength estimation of
nanomaterials and Silicon nitride/Silicon carbide nanomaterials were considered. These materials
continue to receive immense levels of attention in the industrial and academic worlds due to the
mechanical properties that the two materials demonstrate in high temperature conditions. The
material is known to demonstrate low toughness and resistance to fracture, thus requiring it to be
reinforced using a nanoscale reinforcement matrix that will improve these mechanical properties
of the new material (Biasini and Bellosi, 2008).
Scope
The nanocomposite will be developing by incorporating Silicon Nitrite nanoscale particles into a
Silica Carbide matrix to develop a material with a high fracture toughness for resisting damage
and wear, as well as high mechanical strength in different thermal conditions. The study will
implement the use of finite element analysis methods in order to simulate the preparation of the
Si3 N4 / SiC nanomaterial and to conduct a microstructural analysis and thus estimate the strength
of the material.

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Chapter 2: Literature Review
As ceramic nanomaterial continue to find increasing industrial applications in industrial
sectors such as electronics, automotive, aerospace, consumer products development, medical,
and military uses among others, the need to improve their structural and mechanical properties is
also greatly increased. These ceramic materials that are generally classified into nitrides,
carbides, borides, oxides and oxy-nitrides present a broad variety in the in their properties and
thus impacting their applicability in industry for different purposes. Some of the important
physical, mechanical, and even structural properties that affect the application of the material in
industry include the high temperature stability of the material, as well as its fracture toughness,
brittleness, stiffness and strength (Greil, Petzow, and Tanaka, 2007, 21). Ceramic materials
however demonstrate very low levels of fracture toughness and thus it limits the structural
properties that make the material applicable in some industry sectors. Fracture toughness can be
described as the resistance a material shows towards failing after the initiation of weak points
and a crack has already occurred. When a material has a high level of fracture toughness, the
material therefore demonstrates an ability to remain durable regardless of the possibility of the
occurrence of failure on the material. Thus enhancing the mechanical properties of ceramic
materials through improving their structures to form strong nanocomposites can be effective in
improving the applicability of such material in industry.
Mechanical Behavior of Ceramic Nanomaterials
An example of a ceramic material which can be converted into a nanomaterial is Silica
Carbide (SiC) which is widely applied in the engineering field due to is high level of strength, a
resistance to corrosion and creep as well as its high temperature performance characteristics.
This material demonstrates a high level of yield strength and hardness levels of 9GPa and
2800/mm2 respectively, yet has a low fracture toughness level of 4.6MPa (Hermann, et al. 2008).

Microstructural Analysis of Nanomaterials 11
This is due to the fact that the material contains strong covalent bonds between the silicon and
carbide atoms, yet ionic bonds form up the microstructure of the material. These ionic bonds
determine the mechanical and physical properties of SiC. Thus any improvement on the
microstructure of this material will result in an improvement of the toughness of this material.
After the development of a crack, any loading conditions that have an impact on the
surface having the crack risk the occurrence of failure for the material. Loading conditions that
continue to occur on the material could easily result in a continuation of the development of the
crack to failure r fracture, resulting in the failure of the entire structure of the material. Since
ceramic materials have a mechanical property of high brittleness, the material is hardly ever able
to resist the development of the crack when lines of weakness due to loading action occur on the
material. As such, ceramic materials also experience low toughness and thus the applicability of
the material in industry is highly limited by the low levels of fracture toughness (Balázsi, et al.
2003).
Researchers from different parts of the world have contributed to the development of new
methods that can be used to improve the fracture toughness of ceramic materials. Several
methodologies have been proposed as a result of the contribution of these researchers, namely
bridging the crack, blunting it, or even relaxing the field of strain on the area of the material that
is affected by a crack. The first procedure details the process of blunting the crack such that it
follows a predetermined cause of failure to encourage the possibility of repairing the structure.
Bridging a crack in ceramics would entail the incorporation of new material to bridge the crack
and ease all the loading tension felt on the area to discourage the progression of the crack (Greil,
Petzow and Tanaka, 2007). Finally the method of easing and relaxing the field of strain on the
affected area on the material would entail an identification of the strains that contribute to the

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progression of the crack. In easing the strains felt in that area, the strain conditions are able to
redistribute themselves in order to reduce and even permanently stop the progression of a crack,
paving way for the implementations of other interventions to prevent the impact of the crack.
The Si3 N4 /SiC nanomaterial
When considering the ceramics-based on the material known as silicon carbide (SiC)
different forms of modelling can be incorporated in order to devise workable solutions about the
deformation and toughness improvement of ceramic materials. These methodologies utilize both
atomic and technological modelling solutions through enriching silicon carbide ceramic
materials with nanodiamond composites, carbon nanoparticles as well as the development of
nanoscale tubes or films where some of the silicon atoms are replaced by carbon atoms. These
new additions into the structure of the ceramic material are able to improve the toughness and
strength of the material through considerations of atomic level structural linkages and even
through the study of simulated materials (Hirano and Niihara, 2015, 251). The method allows for
the alteration of the structure of the material to incorporate alternating layers of brittle and
ductile materials which has an impact of increasing the strength and toughness of the material.
As such the strength and toughness of the SiC material can be improved by changing the
structure of the material to incorporate alternating layers of brittle and ductile material through
the preparation of a Si3 N4 /SiC nanomaterial. This can be achieved through the doping of
Yttrium with SiC sample with Carbon.
Microstructural Conditions of the Si3 N4 /SiC nanomaterial
With modelling and simulation, complex simulations of different improved software
systems that allow the analysis and assessment of the properties of the modelled material are
simulated. The simulation is able to demonstrate the microstructural conditions of the newly