DR. MOHD ZULKEFLI BIN SELA MAT JUNEeprints.utem.edu.my/15331/1/THE EFFECT OF STAINLESS... · Lebih sedekad yang lalu, kemajuan pesat telah dibuat dalam memahami dan pembangunan konduktif

SUPERVISOR DECLARATION

" I declare that I have read this thesis and in my opinion this report is sufficient in terms

of scope and qua I ity for the award of the degree of Bachelor of Mechanical Engineering

(Structure & Materials)"

Signature

Supervisor

Date

: ...... ~ .............. . : DR. MOHD ZULKEFLI BIN SELA MAT

: 28 JUNE 2013

DR. MOHD ZULKEFLI BIN SELAMAT Pensyarah Kanan

Fakulti Kejuruteraan Mekanikal Universiti Teknikal Malaysia Melakl

© Universiti Teknikal Malaysia Melaka

THE EFFECT OF STAINLESS STEEL ON THE PROPERTIES OF GRAPHITE

POL YPROPYLENE COMPOSITE FOR BIPOLAR PLATE

FAIRUZ F AZILLAH BINTI SHUIIlMI

This report is submitted to Faculty of Mechanical Engineering as a

requirements to get award of

Degree of Mechanical Engineering ( Structure & Material)

Faculty of Mechanical Engineering

Universiti Teknikal Malaysia Melaka

JUNE2013


DECLARATION

"I hereby declare that the work in this report is my own except for swnmaries

and quotations which have been duly acknowledgment."

Signature

Author

Date

: ......... ~ .. : .... . ....... . ..... .

: F AIRUZ F AZILLAH BINTI SHUHIMI

: 28 JUNE 2013


ii

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ACKNOWLEDGEMENT

Assalamualaikum w.b.t

Very grateful to Allah S.W.T because of Allah' s endowment, I can execute this

Final Year Project 1 report at the right time. I would like to take this opportunity to

express my deepest heartfelt and thank to all those who have guided and supported me

during my Final Year Project either directly or indirectly.

First of all I would like to thank GOD for this opportunity, and to my parents and

siblings for their love and support. I would like to thank Dr. Mohd Zulkefli bin Selamat

as supervisor, Mr Mohd Syakir bin Ahmad as him assistant researcher and all lecturers

with respect to their direction, guidance, assistance and unselfish support. Special thanks

to my nice appreciation to panels during presentation, Dr. Mohd Fadzli bin Abdollah,

Dr.Olawale Friday, Mr. Omar bin Bapokutty for their valuable advice and nice support

on behalf of me to satisfy this project. Also thanks to all the technicians and staffs from

Department of Mechanical Engineering for their instruction, continuous support and

supervision.

Finally, I would also like to thank those individuals who have contribute to the

success of my training and whose name are not mentioned. They may be my family

members, other FKM staff, friends, and individuals I meet during project progress.

Thank you for all the support and contribution for the success of my Final Year Project

at Universiti Teknikal Malaysia Melaka.


iv

ABSTRACT

Over the past decade, rapid progress has been made in the understanding and

development of Conductive Polymer Composites (CPC) as conducting materials. This

project is aimed to study the effects of stainless steel (St) loading on the electrical and

mechanical properties of Graphite (G)/ Stainless steel (St)/ polypropylene (PP)

composite of bipolar plates for polymer electrolyte membrane fuel cells (PEMFC). St is

selected as second filler because it offers good electrical conductivity, high bulk thermal

conductivities, good corrosion resistance and constant particle shape. The analysis of the

G/St/PP composites ratio and the properties of G, St and PP together with the impact of

Graphite (G) as a main filler and Stainless Steel (St) as second filler whereas

polypropylene (PP) as a binder has been carry out. The impact of fillers on the

composite properties was evaluated as well as the ratio of the weight percentage (wt%)

of the composite with 80% for multi-filler material and 20% binder material. The St wt

% is vary from 5 wt % up to 30 wt % of total wt % of multi-filler materials. After

formation of composite through compression molding, the effects of St in G/St/PP

composite have been determined through various tests such as electrical conductivity,

flexure strength, density and hardness before can be used as composition of G/St/PP

composite for bipolar plate. The result showed the analysis for Flexural Strength, Bulk

Density and Shore Hardness meet the required characteristics of bipolar plate as in the

Department of Energy (DOE). But for electrical conductivity, the results showed a very

slight increase which is less than 1 OOS/cm.


v

ABSTRAK

Lebih sedekad yang lalu, kemajuan pesat telah dibuat dalam memahami dan

pembangunan konduktif Polimer Komposit (CPC) yang mengendalikan bahan-bahan.

Projek ini bertujuan untuk mengkaji kesan daripada keluli tahan karat (St) pada sifat

sifat elektrik dan mekanikal Grafit (G) I keluli tahan karat (St) I polipropilena (PP)

komposit plat dwikutub bagi polimer elektrolit sel bahan api membran. St dipilih sebagai

pengisi kedua kerana ia menawarkan kekonduksian elektrik yang baik, konduktiviti haba

yang tinggi, ketahanan kakisan yang baik dan bentuk zarah yang berterusan. Analisis

nisbah komposit G I St I PP dan sifat-sifat G, St PP dan bersama-sama dengan kesan

Grafit (G) sebagai pengisi utama dan keluli tahan karat (St) sebagai pengisi kedua

manakala polipropilena (PP) sebagai pengikat telah menjalankan. Kesan pengisi pada

sifat-sifat komposit telah dinilai serta nisbah peratusan berat (% berat) dengan 80%

untuk bahan pelbagai pengisi dan 20% bahan pengikat. Berat St°/o yang berbeza-beza

dari 5% sehingga 30% daripada jumlah berat bahan pelbagai pengisi. Selepas

pembentukan komposit melalui pengacuan mampatan, kesan St dalam G I St I PP

komposit telah ditentukan melalui pelbagai ujian seperti kekonduksian elektrik,

kekuatan lenturan, kepadatan dan kekerasan sebelum boleh digunakan sebagai

komposisi G I St I PP gubahan plat dwikutub. Hasilnya menunjukkan analisis untuk

kekuatan lenturan, ketumpatan dan kekerasan memenuhi ciri-ciri yang diperlukan plat

dwikutub oleh Jabatan Tenaga. Tetapi bagi kekonduksian elektrik, keputusan

menunjukkan peningkatan yang sangat sedikit iaitu kurang daripada 1 OOS/cm.


CHAPTER

CHAPTER I

CONTENT

TITLE

TITLE PAGE

DECLARATION

ACKNOWLEDGEMENT

ABSTRACT

ABSTRAK

CONTENT

LIST OF FIGURE

LIST OF TABLE

LIST OF APPENDIX

LIST OF SYMBOLS

LIST OF ABBREVIATION

INTRODUCTION

1.1 BACKGROUND

1.1.1 Proton exchange membrane

fuel cell

1. I .1.1 Polymer Electrolyte

Membrane Fuel Cell

PAGES

11

lll

iv

v

vi-ix

X-Xl

XU

xiii

xiv

xv

1

3

Operation 4

1.1.2 Component of PEMFC 5

1.1 .2.1 Membrane Electrolyte

Assembly (MEA) 7


vi

CHAPTER2

1.2

1.3

1.4

1.1.2.2 Catalysts

OBJECTIVE

SCOPE OF STUDY

PROBLEM STATEMENT

LITERATURE REVIEW

2.1 CONDUCTIVE POLYMER

COMPOSITES

2.1.1 Conductively Filled Polymers

2.1.2 Polymers Filled with Conductive

Solids

2.2 BIPOLAR PLATE MATERIALS

2.2.1 Filler

2.2.1. l Graphite

2.2.1.2Stainless Steel

2.2.2 Binder

2.2.2.1 Polypropylene

2.3 FABRICATION OF BIPOLAR PLATE

2.3.1 Injection Molding

2.3.1.1 Equipment

2.3.1.2 Power Requirements

2.3.2 Compression Molding

2.3.2.1 Basic Process of

Compression Molqing

2.3.2.2 Advantages

2.3.2.3 Disadvantage

2.4 TESTING METHOD

2.4.1 Electrical Properties

2.4.2 Mechanical Properties


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8

9

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11

12

14

15

15

19

23

23

25

25

26

26

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27

28

28

29

29

30

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CHAPTER3 METHODOLOGY

3.1 CHARACTERIZATION OF

RAW MA TERI.AL 33

3.2 PRE-MIXING 35

3.3 MELT COMPOUNDING 36

3.4 CRUSH AND PULVERIZE 37

3.5 COMPRESSION MOLDING 38

3.6 TESTING

3.6.1 Electrical Properties 41

3.6.2 Mechanical Properties

3.6.2.1 Flexural Testing 42

3.6.2.2 Bulk Density Testing 43

3.6.2.3 Shore Hardness Testing 43

CHAPTER4 RESULT AND ANALYSIS

4.1 ELECTRICAL CONDUCTIVITY

TEST RESULT 44

4.1.1 Determination of Electrical

Conductivity 45

4.2 FLEXURAL TEST 47

4.3 BULK DENSITY 48

4.4 SHORE HARDNESS 49

CHAPTERS DISCUSSION

5.1 DISCUSSION OF RESULT

5.1.1 Electrical Conductivity Testing 51

5.1.2 Flexural Testing 52

5.1.3 Bulk Density Testing 52

5.1.4 Shore Hardness Testing 53


5.2 DISCUSSION OF PROBLEM

ENCOUNTERED

5.2.1 Materials flows out of the mold

5.2.2 Material attached to the mold

5.2.3 Mold plate loose

5.2.4 Surface of sample not uniform

and broken

5.3 SOLUTIONS

CHAPTER6 CONCLUSION AND RECOMMENDATION

6.1 CONCLUSION

6.2 RECOMMENDATION

REFERENCES

BIBLIOGRAPHY

APPENDIX


54

54

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56

57

58

59

65

67

ix

x

LIST OF FIGURE

BIL TITLE PAGE

Figure I.I Fuel cell 2

Figure I.2 Polymer Electrolyte Membrane Fuel Cell (PEMFC) 3

Figure I.3 Operation of PEMFC 4

Figure I.4 The illustration of components of PEMFC 5

Figure I.5 Bipolar Plates 6

Figure 2.I Dependence of composite conductivity on the volume I2

fraction of conductive fillers

Figure 2.2 Schematic representation of conductive particles dispersed 13

in a polymer matrix at different particle volume fractions

Figure 2.3 Classification of materials for BPs used in PEM fuel cells I4

Figure 2.4 Graphite Specimen I6

Figure 2.5 Graphite Unit Cell I7

Figure 2.6 Stainless steel AISI 3I6 (Fe/CrI8/NilO/Mo3) 20

Figure 2.7 Polypropylene 23

Figure 2.8 Chemical structures for polypropylene 23

Figure 2.9 Injection Molding Machine 25

Figure 2.IO Jandel Four Point Probe 29

Figure 2.I I Zwick Shore hardness tester and flexural testing machine 30

Figure 2.I2 Density Meter Tester 30

Figure 3.I Flow Chart Methodology 32

Figure 3.2 Powder of material (a) G, (b) St and (c) PP 33


xi

Figure 3.3 Measured the weight of graphite and stainless 34

steel due the percentage

Figure 3.4 Ball Mill machine 35

Figure 3.5 Steel Ball 35

Figure 3.6 Measure the weight of St/G and PP 36

Figure 3.7 Internal Mixer Machine 36

Figure 3.8 Outcomes from Internal Mixer Machine (St/GIPP) 37

Figure 3.9 Crusher machine 37

Figure 3.10 Outcomes of crusher process 37

Figure 3.11 Centrifugal Mill machine 38

Figure 3.12 Outcomes of pulverize process 38

Figure 3.13 Four-Point Probe Tester 41

Figure 3.14 Cutter machine 42

Figure 3.15 Standard sizes for Flexural 42

Figure 3.16 Three Point Flexural Test 42

Figure 3.17 Setting the sample to the supporting span 42

Figure 3.18 Electronic Densimeter 43

Figure 3.19 Standard size for density test 43

Figure 3.20 Digital Shore Hardness 43

Figure 4.1 Graph of conductivity versus St wt% 45

Figure 4.2 Graph of flexural strength versus St wt% 47

Figure 4.3 Graph of Density versus St wt.% 48

Figure 4.4 Graph of shore hardness versus St wt% 49

Figure 5.1 Materials flow out of the mold 54

Figure 5.2 Material attached to the mold 54

Figure 5.3 Mold plate loose 55

Figure 5.4 Surface of sample broken 55

Figure 5.5 Mold plate sprayed with lubricant oil 56


xii

LIST OFT ABLE

BIL TITLE PAGE

Table 2.1 Principal property of filler 16

Table 2.2 Composition ranges for 316L stainless steel 22

Table 2.3 Mechanical properties of 316L stainless steel 22

Table 2.4 Typical physical properties for 316L grade

stainless steels 22

Table 2.5 Properties of polypropylene 24

Table 2.6 The power requirement of injection molding by 26

different material

Table 3.1 Raw material properties of G/St/PP 33

Table 3.2 Composition based on weight percentages 34

Table 4.1 Average result for Conductivity of St/GIPP 45

Table 4.2 Data from top and bottom of composite 20% St 45

Table 4.3 Average result for Flexural Strength of St/GIPP 47

Table 4.4 Bulk Density of St/GIPP 48

Table 4.5 Shore hardness St/GIPP 48

Table 5.1 U.S Department of Energy (US DOE) 51


BIL

A

B

c D

E

F

LIST OF APPENDIX

TITLE

FLOW CHART OF STUDY

GANTT CHART FINAL YEAR PROJECT 1 & 2

ASTM C611 ELECTRICAL RESISTIVITY

ASTM D790-03 FLEXURAL TEST

ASTM C559-90 BULK DENSITY

ASTM C886-98 HARDNESS


PAGE

67

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69

71

77

78

xiii

xiv

LIST OF SYMBOL

PEMFC = Proton Exchange Membrane Fuel Cell I Polymer Electrolyte

Membrane Fuel Cell

PEM = Polymer Electrolyte Membrane

BPs = Bipolar Plate

DC = Direct Current

H20 =Hydrogen

02 =Oxygen

MEA = Membrane Electrolyte Assembly

G =Graphite

St = Stainless Steel

pp = Polypropylene

PPS = Polyphenylene sulfide

PVDF = Polyvinylidene fluoride

CPCs = Conductive Polymer Composites

IP Cs = Inherently Conducting Polymers

SP Es = Solid Polymer Electrolytes

Cr = Chromium

Ni =Nickel

Mo = Molybdenum

LDPE = Low-Density Polyethylene

HDPE = High-Density Polyethylene

MFR = Melt Flow Rate

MFI = Melt Flow Index

DOE =US-Department of Energy


Wt.%

Siem

MP a

Cm

µA

g/cm3

LIST OF ABBREVIATION

= Weight Percentage

= Siemens/centimeter

= Mega Pascal

= centimeter

= micron Ampere

= gram/centimeter3

W ·m- = Watt per metre

µA cm/\ (-2) =Micro ampere(s) per square centimeter

µm

nm

ncm

E

mK

oc

= micrometer

=nanometer

= ohm-centimeter

=Young's Modulus

= milli Kelvin

= Degree Celsius


xv

1

CHAPTER 1

INTRODUCTION

1.1 BACKGROUND

One of the maJor factors limiting fuel cell commercialization is the

development of bipolar plates, which are one of PEMFC's key components. Several

types of materials are currently used in bipolar plates, including non-porous graphite

plates, metallic plates with or without coating and a number of composite plates .

The bipolar plate is one of the most important components in a PEM fuel cell.

A polymer composite bipolar plate possessing high strength and high stiffness has been

developed by making use of carbon fiber network in a specific form as the filler

component. The bipolar plates are in weight and volume the major part of PEM fuel cell

stack, and also a significant effect to the stack cost.


2

Figure 1.1: Fuel cell

So far, many different materials for bipolar plates have been investigated and an

alternative solution consists in polymer composite that combine the process ability and

mechanical properties of the polymeric phase and the conductivity of the carbon fillers.

Both thermo-set resins and thermoplastics were considered and combined to many

different carbon fillers. [ 1]

The interests and limitations of these formulations are presented in terms of

process ability and most relevant properties. A composite material is made by combining

two or more materials to give a unique combination of improved properties, such that

each component retains its physical identity.

In order to improve their commercial liability, many scientific and

technological efforts are being performed on fuel cell systems. On the technical point of

view, bipolar plates should fulfill functional challenges besides ensuring the mechanical

strength of the stack. As a result an optimal material for bipolar plate application should

present an unusual balance of properties, essentially high electrical conductivity and

good mechanical strength.


3

1.1.1 Proton exchange membrane fuel cell

Proton exchange membrane fuel cell (PEMFC), also known as polymer

electrolyte membrane (PEM) fuel cells are a type of fuel cell being developed for

transport applications as well as for stationary fuel cell applications and portable fuel

cell applications. Their distinguishing features include lower temperature/pressure

ranges (50 to I 00 °C) and a special polymer electrolyte membrane.

PEMFC are electrochemical devices that convert the chemical energy of

reactants (a fuel and an oxidant) directly to electrical energy in the form of low voltage

direct current (DC) electricity and heat. They have been receiving significant attention

due to their high power density, energy efficiency, and environmentally friendly

characteristics. [2]

Power

llcat

End-plate gos and cooling manifold

Bipolar now-rlate interconnect

--- Membrane l:leclrol)~C sscmbl} tMEA)

Figure 1.2: Polymer Electrolyte Membrane Fuel Cell (PEMFC) [7]


4

1.1.1 .1 Polymer Electrolyte Membrane Fuel Cell Operation

I. Pure hydrogen constantly flows from a simple cylinder containing

compressed hydrogen into the fuel cell and onto the anode it is then split

into hydrogen ions and electrons.

2. The electrons cannot pass through the electrolyte therefore ; they pass

through the external circuit creating an electric charge.

3. The electrolyte is sandwiched between the anode and cathode, which 1s

permeable to protons but does not conduct electrons. Hydrogen ions

(protons) permeate across the electrolyte to the cathode. Electrons flow

through an external circuit and provide power.

4. Oxygen is fed into the fuel cell onto the cathode (positive electrode). The

cathode combines electrons, protons and oxygen to form the by product

which is water. The water then leaves the cell . This is a continuous process

so as hydrogen and oxygen is supplied. [3]

.-.-- Ol (Oxygen) from Air

HHt(8S"C) Watu or Air Cool•d

Flow Fi•ld Plate

~----- Gas Diffusion Elec:tro<H (Cathode)

------ Cit.al~!

Figure 1.3: Operation of PEMFC [4]


5

1.1.2 Component of PEMFC

The components of PEMFC are bipolar plates, electrolyte membrane with

anode and cathode(MEA) and catalyst.

Bipolar Plate

Cita,yst MEA . catalyst

Bipolir Plit'

Figure 1.4: The illustration of components of PEMFC

1.1.2.1 Bipolar Plate

Bipolar plates are responsible for collecting and transporting electrons from the

anode and cathode, as well as, connecting individual fuel cells in series to form a fuel

cell stack of the required voltage. They are also responsible, for providing thermal

conduction to help regulate fuel cell temperature and removing heat from the electrodes,

delivering fuel gas and air to the membrane electrode assembly (MEA), and carrying

exhaust gas and product water away from the MEA.


6

Figure 1.5: Bipolar Plate [5]

In polymer electrolyte membrane fuel cell (PEMFC) design, bipolar plate should require

as follows [6]:The requirement also the target of DOE requirement for bipolar pate.

a. Good electrical conductivity (> 100 S cm/\(-1) bulk conductivity)

b. High Shore Hardness (>40)

c. Good bulk density (- 1.85 g cm/\(-3))

d . Good flexural strength (>25 MPa)

e. High tensile strength (>41 MPa)

f. Low permeability for hydrogen (<2x [ 10 ] /\(-6) cm/\3)

g. High thermal conductivity(> I 0 W cm/\(-1 ))

h. High chemical and corrosion resistance (< I µA cm/\(-2))

1. Low surface contact resistance

J. Mechanical stability toward compression forces

k. Low-cost material being process-able with mass production techniques

I. Low weight and volume

m. Recyclable materials.


7

1.1.2.2 Membrane Electrolyte Assembly (MEA)

A key component of a PEM fuel cell is the Membrane Electrolyte Assembly or

MEA. The MEA consists of two electrodes, the anode and the cathode. These are porous

carbon electrodes, which are each coated on one side with a low amount of platinum

catalyst and separated by a proton exchange membrane (PEM). The PEM is the

electrolyte in this assembly. It is a thin sheet that is only pe1meable for protons and

water. It must allow hydrogen protons to pass through but prohibit the passage of

electrons and gases. [8]

1. Anode - The anode, the negative side of the fuel cell , has several jobs . It

conducts the electrons that are freed from the hydrogen molecules so they can

be used in an external circuit. Channels etched into the anode disperse the

hydrogen gas equally over the surface of the catalyst.

2. Cathode - The cathode, the positive side of the fuel cell , also contains channels

that dist1ibute the oxygen to the surface of the catalyst. It conducts the electrons

back from the external circuit to the catalyst, where they can recombine with

the hydrogen ions and oxygen to forn1 water.

3. Polymer electro lyte membrane - The polymer electrolyte membrane (PEM)-a

specially treated material that looks something like ordinary kitchen plastic

wrap- conducts only positively charged ions and blocks the electrons. The

PEM is the key to the fuel cell technology; it must pe1mit on ly the necessary

ions to pass between the anode and cathode. Other substances passing through

the electrolyte would dismpt the chemical reaction.[9]


8

1.1.2.3 Catalysts

The PEMFC catalysts are the reaction sites where the electrochemical reactions

occur. They are usually very thinly coated onto carbon paper or cloth.The catalyst is a

porous platinum coating on the anode which speeds up the reaction.

The platinum coating prevents the formation of hydrogen peroxide which 1s

highly corrosive to the fuel cell.

In a fuel cell, hydrogen gas flows to the anode. There, with the help of the

catalyst, the molecules are broken down into protons (hydrogen ions) and electrons. The

positively charged protons go through the porous membrane and migrate toward the

cathode. [l OJ

1.2 OBJECTIVE

The main objectives of this analysis are to analyze regarding composites and

therefore the electrical conductivity of G, St and PP together with the impact of Graphite

as a main filler and Stainless Steel as second filler. This analysis evaluated as well as the

ratio of the weight percentage of the composite.

Those objectives evaluated are to assist and complete this study:

1. To study the effect of Stainless steel on the properties of GI PP composite.

2. To determine the critical loading of St in GIPP composite for bipolar plate.


Documents

DR. MOHD ZULKEFLI BIN SELA MAT JUNEeprints.utem.edu.my/15331/1/THE EFFECT OF STAINLESS... · Lebih sedekad yang lalu, kemajuan pesat telah dibuat dalam memahami dan pembangunan konduktif