ANALYSIS ABOUT THE EFFECT OF COMPOSITION
OF GREEN BODIES ON MULLITE BONDED SILICON
CARBIDE
MUHAMMAD AFFENDI BIN MUSTAFA
UNIVERSITI TEKNIKAL MALAYSIA MELAKA
Analysis About t he Effect of Composit ion of
Green Bodies on Mullit e Bonded Silicon
Carbide
Thesis submitted in accordance with the partial requirements of the Universiti Teknikal Malaysia Melaka for the Degree of Bachelor of Engineering (Honours) Manufacturing (Material Engineering)
By
Muhammad Affendi bin Must afa
APPROVAL
This thesis submitted to the senate of UTeM and has been accepted as partial fulfillment of the requirements for the degree of Bachelor of Manufacturing Engineering (Manufacturing Process). The members of the supervisory committee are as follow:
……… Main Supervisor
DECLARATION
I hereby, declared this thesis entitled “Analysis About the Effect of Composition of Green Bodies on Mullite Bonded Silicon Carbide.” is
the results of my own research except as cited in references
Signature : ………
Author’s Name : Muhammad Affendi bin Mustafa ………
ABSTRACT
ABSTRAK
DEDICATION
“Thanks to my parents, my family, my friends and all persons that involve in this
ACKNOWLEDGEMENT
TABLE OF CONTENTS
List of Abbreviations, Symbols, Specialized Nomenclature………... xiii
1. INTRODUCTION………. 1
1.1 Introduction to Silicon Carbide……….……….……. 1
1.2 Problem Statement……….……. 2
2.2.3 Modified Lely Process………... 10
2.3 The Structure of Silicon Carbide…….………... 12
2.5 Mechanical Properties of SiC.……….………... 19
2.6 Mullite-Bonded SiC………...…. 20
2.6.1 Process of Preparing Mullite-Bonded SiC………. 21
2.6.2 Effect of Composition in Mullite-Bonded SiC……….. 22
3. METHODOLOGY……….………... 25
3.1.3.1 Ball Mill Procedure…………..………... 27
3.1.4 Powder Compaction...………...……. 27
3.1.4.1 Procedure of Powder Compaction……….. 28
3.1.5 Sintering Process………...……. 29
3.1.5.1 Procedure of Sintering…….………... 30
3.1.6 Sample Dimensioning………...………. 30
3.1.6.1 Length and Width………... 30
3.1.6.2 Thickness……… 31
3.2 Sample Testing……… 32
3.2.1 Three Point Bending Test (Flexural Strength)………... 33
3.2.2 Scanning Electron Microscope……….. 34
3.2.3 X-ray Diffraction……… 35
4. RESULT………. 36
4.2 Three Point Bending Test (Flexural Strength)……..……….……. 38
4.2.1 Sample 1 with an alumina content of 40 wt%... 39
4.2.2 Sample 2 with an alumina content of 32.3 wt%... 39
4.2.3 Sample 3 with an alumina content of 25 wt%... 40
4.2.4 Sample 4 with an alumina content of 20 wt%... 40
4.2.5 Comparison of Flexural test result………. 41
4.3 Scanning Electron Microscope observation……….……….. 43
4.3.1 Alumina particle size……….. 43
4.3.2 Silicon Carbide particle size………... 44
6. CONCLUSION AND RECOMMENDATION...……….. 65
6.1 Conclusion………...……….……….…….. 65
6.2 Recommendations……… 66
7. REFERENCES...……… 67
8. APPENDICES
A Flexural graph for sample 1 B Flexural graph for sample 2 C Flexural graph for sample 3 D Flexural graph for sample 4 E Alumina phase diagram F SEM for sample 1 G SEM for sample 2 H SEM for sample 3 I SEM for sample 4
LIST OF FIGURE
1.1 Flow chart of sample preparation………...……….. 4
2.1 Drawing of the original electric smelting furnace. This type of furnace was later applied for the production of SiC by Acheson……….. 6
2.2 Cross section of an Acheson furnace before and after the furnace has been fired………... 8
2.3 Cross section of a Lely furnace………. 10
2.4 Schematic drawing of a modified Lely setup………... 11
2.5 The tetragonal bonding of a carbon atom with the four nearest silicon neighbors. The distances a and C-Si are approximately 3.08Å and 1.89Å respectively……….. 13
2.6 The stacking sequence of double layers of the three most common SiC polytypes………... 14
2.7 The [1120] plane of the 6H-SiC polytype……… 16
2.8 The [1120] plane of the 4H-, 3C-, and 2H-SiC polytypes……… 17
2.9 The Miller indices describing the hexagonal structure. The c-axis refers to the last index, whereas the first three describes the directions of the basal plane……….. 18
2.10 XRD patterns of the sintered SiC porous ceramics with different Al2O3 content. (a) 5 wt.% Al2O3, (b) 10 wt.% Al2O3, (c) 15 wt.% Al2O3, (d) 20 wt.% Al2O3, (e) 30 wt.% Al2O3. Source: Weiguang Chi, Dongliang Jiang, Zhengren Huang, Shouhong Tan (2004)……… 24
3.1 Flow chart of sample preparation………... 26
3.2 The ball mill machine………... 28
3.3 The hydraulic press machine……… 30
3.4 The sintering machine………... 31
3.5 The Flow Chart of Testing Process………... 34
3.6 The three point bending illustration……….. 35
4.1 Alumina, 40 wt%... 39
4.2 Alumina, 32.3 wt%... 39
4.3 Alumina, 25 wt%... 39
4.4 Alumina, 20 wt%... 39
4.5 Sample for flexural testing (base on alumina percentage)…...………. 40
4.6 Flexural strength of mullite bonded silicon carbide base on alumina content………... 43
4.7 Flexural modulus of mullite bonded silicon carbide base on alumina content………... 44
4.8 SEM of alumina particle size……… 45
4.9 SEM of silicon carbide particle size………. 46
4.10 SEM of mullite bonded silicon carbide with alumina content 40 wt% using 1000 X magnify………... 47
4.11 SEM of mullite bonded silicon carbide with alumina content 40 wt% using 4000 X magnify………... 47
4.12 SEM of mullite bonded silicon carbide with alumina content 32.3 wt% using 1000 X magnify………... 48
4.13 SEM of mullite bonded silicon carbide with alumina content 32.3 wt% using 4000 X magnify………... 48
4.14 SEM of mullite bonded silicon carbide with alumina content 25 wt% using 1000 X magnify………... 49
4.15 SEM of mullite bonded silicon carbide with alumina content 25 wt% using 4000 X magnify……….. 49
4.16 SEM of mullite bonded silicon carbide with alumina content 20 wt% using 1000 X magnify……….. 50
4.17 SEM of mullite bonded silicon carbide with alumina content 20 wt% using 4000 X magnify………... 50
4.18 Sample 1 (Alumina content 40 wt%)……… 51
4.20 Sample 3 (Alumina content 25 wt%)……… 53
4.21 Sample 4 (Alumina content 20 wt%)……… 54
5.1 Graph of weight loss percentage………... 56
5.2 Graph of density……… 56
5.3 Flexural strength of mullite bonded silicon carbide base on alumina content………... 58
5.4 Flexural modulus of mullite bonded silicon carbide base on alumina content………... 59
5.5 Needlelike mullite apparent on sample 1 with alumina content, 40 wt%... 60
5.6 The microstructure on cross-section of sample 2 with alumina content, 32.3 wt%... 61
5.7 The microstructure on cross-section of sample 3 with alumina content, 25 wt%... 61
LIST OF TABLE
2.1 The mechanical properties of SiC………. 11
2.2 Comparison of properties of sintered porous SiC with different content of Al2O3……….. 23
3.1 The composition of Mullite Bonded SiC………... 27
4.1 The type of sample prepared………. 38
4.2 Data of density and weight loss of samples……….. 39
4.3 Data of flexural test for sample Al2O3 40 wt%... 41
4.4 Data of flexural test for sample Al2O3 32.3 wt%... 41
4.5 Data of flexural test for sample Al2O3 25 wt%... 42
4.6 Data of flexural test for sample Al2O3 20 wt%... 42
4.7 The average result of flexural test for mullite bonded silicon carbide…….. 43
5.1 Form phases and their ranking in each samples as detected from intensities of XRD patterns……….
LIST OF ABBREVIATIONS, SYMBOLS, SPECIALIZED
μ - Micro G - Giga M - Mega
Pa - Pascal
ASTM - American Standard Testing Material SI - Standard International
CHAPTER 1
INTRODUCTION
1.1 Introduction to Silicon Carbide
Silicon carbide is a type of ceramic composed of tetrahedral of carbon and silicon atoms with strong bonds in the crystal lattice. These particular bonds produce a very hard and strong material. Silicon Carbide is immune by any acids or alkalis or molten salts up to 800° C. When expose in air, SiC forms a protective silicon oxide coating at temperature of 1200° C and can withstand the heat for up until 1600° C. The high thermal conductivity joint together with low thermal expansion and high strength resulted for this material to have an excellent thermal shock resistant quality. The overall reaction of producing Silicon Carbide is SiO2 + 3C = SiC + 2CO.There
is a various type of how to produce SiC whereas it is divided into two type of growth. The two type of growth is bulk growth technique and epitaxial growth technique. SiC with only a few or no grain boundary impurities is capable maintaining their strength to a very high temperature which is approaching 1600° C without any strength loss. Silicon Carbide only go through decomposing when heated to about 2700° C. Silicon carbide was originally produced by a high temperature electro-chemical reaction of sand and carbon. Widely use as an abrasive, Silicon Carbide is marketed under such familiar trade names as Carborandum and Crystolon.
Silicon carbide does not occur naturally on Earth so it cannot be mined like other minerals, hence the need for its synthesis in a high temperature furnace. The only occurrence of silicon carbide in nature is in meteorites, and it has been described by some researchers as a gift from the stars. Mineralogists call natural silicon carbide moissanite after the man who first identified it in a meteorite in 1905.
1.2 Problem Statement
The purpose of this project is to investigate the maximum capability of porous ceramic. Porous ceramic are hydrophilic and have the capability to transport a polar of substance like water through its capillary. This unique capability has become extremely important for porous ceramic to act as a filter to liquid substance. Although ceramic have very good mechanical properties such as high strength, high thermal conductivity, high hardness and high elastic modulus, but ceramic is a very brittle material. Porous ceramic tend to be even more brittle than solid ceramic. With that reason, this project has been conducted to study the mechanical properties of porous ceramic. There is actually a numerous type of porous ceramic available nowadays, but this project has focus on to study the hardest porous ceramic which is silicon carbide. There are several processes to produce the porous silicon carbide and this project is responsible to choose the best process to produce the product.
1.3 Objectives
The objective of this study is:
i) To study the properties of Mullite-bonded Silicone Carbide with various green body’s composition.
ii) To study the flexural strength of Mullite-bonded Silicone Carbide with various green body’s composition.
iii) To analyze on the effect of composition to Mullite-bonded Silicon Carbide.
iv) To identify the optimum composition of the green body of prepared Mullite-bonded Silicone Carbide
1.4 Scope of the Study
Determine the composition
Mix the composition to get homogeneous
mixture
Compact the mixture
Sintered the green bodies at certain temperature and period
Cut the sample to required dimension
CHAPTER 2
LITERATURE REVIEW
2.1 Overview of Silicon Carbide
Figure 2.1: Drawing of the original electric smelting furnace. This type of furnace was later applied for the production of SiC by Acheson
