WARSAW UNIVERSITY OF TECHNOLOGY
Politechnika Warszawska
Faculty of Power and Aeronautical Engineering
Wydział Mechaniczny Energetyki i Lotnictwa
Division of Thermodynamics
Zakład Termodynamiki
Thermal Analysis of Composites Using DSC
Prepared by:
SAMET BÜYÜKKÖMÜRCÜ
Group: Aero-Eng-2014
Date: ??/07/2017
Supervisor/Promotor: Karol Pietrak, dr inż.
İçindekiler Tablosu
CHAPTER 1 4
1.1. INTRODUCTION: 5
1.2. Purpose of Experiment 6
1.3. Mechanism of DSC 7
1.4. Comparing Calorimetry Methods4 8
1.4.1. Adiabatic Calorimeters 8
1.4.2. Reaction Calorimeters 8
1.4.3. Bomb Calorimeters 8
1.4.4. Calvet-Type Calorimeters 8
1.4.5. Constant-Pressure Calorimeters 8
1.4.6. Differential Scanning Calorimeters (DSC) 8
1.5. Aluminium Alloys for Aerospace Applications 9
1.5.1. Introduction 9
1.5.2. Classification and Designation 10
1.5.3. Typical Aerospace Applications of Aluminium Alloys 11
1.5.4. Aluminium Alloy 1050A 12
CHAPTER 2 13
2.1. Preparation of DSC Method 13
2.2. Background 13
2.3. Experimental 13
REFERENCES 15
LIST OF TABLES 15
OBJECTIVES AND SCOPES OF THE PROJECT
Differential scanning calorimetry is a method that measures the
difference in the heat flow to a sample and to a reference sample as a
function of time or temperature under heating conditions. It is also one of the most common thermal analysis.
In the first chapter of this study, purpose of our experiment explained. First, to understand the mechanism of the DSC, available methods of measuring calorimeters will be explained briefly. Detailed explanations will be discussed in the second chapter.
In the end of the first chapter, place of the aluminium alloys in aviation will be explained with giving their real examples in the industry.
In the second chapter, procedures will be take place step-by-step.
In the third chapter, all data that we collect in this study will be discussed and concluded. Comparison between theoretical and practical results will also take place in third chapter.
Final conclusions will be in fourth chapter as the end of the report for this study.
Literatures can find out in the end of the report.
BLANK PAGE
Chapter 1
INTRODUCTION:
Heat Capacity
Heat capacity or thermal capacity is a measurable physical quantity equal to the ratio of the heat added to (or removed from) an object to the resulting temperature change.1 The heat capacity is therefore an extensive variable since a large quantity of matter will have a proportionally large heat capacity.
Specific Heat Capacity
The specific heat capacity of a substance is the amount of energy needed to change the temperature of 1 kg of the substance by 1°C. Different substances have different specific heat capacities.2
Thermal Conductivity
Thermal conductivity is the property of a material to conduct heat. It is evaluated primarily in terms of Fourier's Law for heat conduction.
Density
The density can have defined as a substance is its mass per unit volume. The symbol most often used for density is ρ. Mathematically, density is defined as mass divided by volume [3].
ρ=m/v
Purpose of Experiment
The main purpose of the DSC method is to get knowledge about specific heat capacity of the material under different temperatures and conditions. In our case, environmental conditions kept stable but the temperature is raised linearly from between 20 to 130 Celsius. About seven hundred steps has been observed for each sample during the measurements. Obtained results has been converted with using special computer program to get final result that we interest on. Detailed information about DSC method will be given on following chapters.
Different results were obtained in different temperatures, this was the main goal for us to understand. Specific heat capacity of the elements may change in different temperatures! The reasons of these results will be discussed in third chapter.
table.1.af.1
Table.1. a represents specific heat capacity for some common material/elements.
Mechanism of DSC
DSC, differential scanning calorimetry, is basically measures specific heat value of the materials with using two samples: reference sample and sample.
fig.1.a
When the furnace is heated, heat flows through the disk to the samples. When the differences of samples are ideally symmetrical, the same heat flows through the sample and reference pans. Basically, difference between reference sample and sample gives us ability to find material’s specific heat value.
ΔT = Ts- Tr
Ts: Temperature of the sample. Tr: Temperature of the reference sample.
Heat Flux DSC is available for temperatures between -190 oC and 1600 oC.
The maximum heating rates are about 100 k/min.
Comparing Calorimetry Methods [4]
Adiabatic Calorimeters
Adiabatic calorimeters have a few uses, but the most common one when you want to measure the thermal runaway, thermal instability or the energy from reaction and decomposition processes.
Reaction Calorimeters
There are four different types of reaction calorimeters;
Heat flow
Heat balance
Flux
Power compensation calorimeters
Reaction calorimeter can be used to measure endothermic and exothermic reactions. Also, reactions can be either chemical or physical process.
Bomb Calorimeters
Bomb calorimetry is typically used to measure the enthalpy of combustion in a reaction. As such, these types of calorimeters are robust, generally made of steel and use an oxygenated atmosphere. Due to the rigidity of the calorimeter itself, most reactions in bomb calorimeters occur at a constant volume. These calorimeters can withstand the explosive effects of both the induced pressure and the exothermic release during the reaction process.
Calvet-Type Calorimeters
Whilst not as widely-used, calvet-type calorimeters can be used for measuring the enthalpy change during sublimation reactions and for measuring the behaviour of a material. This type of calorimeter uses sensors to determine the latent heat of transitions or the heat capacity of a system.
Constant-Pressure Calorimeters
Constant-pressure measures the change in enthalpy of a solution-based reaction whilst maintaining a constant pressure. These are the simplest types of calorimeters, and a common example is the one used by high-school students to measure the heat of a reaction using a polystyrene cup, a lid with two holes, a thermometer and a stirring rod.
Differential Scanning Calorimeters (DSC)
(See page 7)
Aluminium Alloys for Aerospace Applications
Introduction
Aluminium alloys have been the main airframe materials since they started replacing wood in the late 1920s. In future aircrafts, aluminium alloys will likely be diminished by the increasing use of composite materials.
’’The advantages of aluminium are that it is a mostly low cost, lightweight metal that can be heat treated to high-strength levels. Aluminium is one of the most easily manufactured of the high-performance materials. Disadvantages of aluminium alloys concern a low modulus of elasticity, rather low elevated-temperature capability, and in high-strength alloys the susceptibility to corrosion [5].’’
Yield strengths versus year of introduction of Al alloys (fig.2.a)
fig.2.a5
Dramatic acceleration in aluminium alloys have took place since they were first introduced. These improvements, shown in fig.2.a, are a result of increasing understanding of chemical composition, impurity control and the effects of processing and heat treatment
Classification and Designation
Aluminium alloys are categorized as heat treatable or non-heat treatable, depending on whether they respond to precipitation hardening. The heat treatable alloys contain elements that decrease in solid solubility with decreasing temperature, and in concentrations that exceed their equilibrium solid solubility at room temperature and moderately higher temperatures. The most important alloying elements in this group include copper, lithium, magnesium and zinc. [6,7]
fig.3.a[6]
Fig.3.a: The principal types of aluminium alloys.
Typical Aerospace Applications of Aluminium Alloys
In future, commercial aircraft will probably be ‘surrounded’ by the increasing use of composite materials, the high-strength aluminium alloys are, and will remain, important airframe materials. Even in military aircrafts, which already have composite material percentages in the range of 40–50 %, aluminium still has a significant role [5].
Since aluminium is lightweight, relatively low cost and metal that can be treated to high strength levels. Also, one of the most easily fabricated high performance material.
fig.4.a
Fig.4.a Engineering property requirements for main structural areas in a transport aircraft:
CYS: compressive yield strength; E: elastic modulus; TS: tensile strength; DT: damage tolerance properties
Aluminium Alloy 1050A
In our study, Aluminium Alloy 1050A has been used during the tests.
Aluminium alloy 1050 is one of the most popular kind for general sheet metal work where we need moderate strength. It also known with its high ductility, excellent corrosion and highly reflective finish features.
Because of those features which are mentioned above, it is one of the most common material in manufacturing of; Food industry containers, pyrotechnic powder, architectural flashings, lamp reflectors, cable sheathing, etc.
Fig.7. a.: CHEMICAL COMPOSITION,
Fig.5. a.: GENERIC PHYSICAL PROPERTIES,
Fig.6. a.: MECHANICAL PROPERTIES
fig.6. a.
Fig.5.a
Fig.7. a.
CHAPTER 2
2.1. Preparation of DSC Method
DSC samples must be dry, clean and small enough to fit into the pans.
Sample preparation procedures are as follows;
Weight of the sample must be known.
We must be avoiding of using naked hands while holding and placing samples into the aluminium pan.
If available, forceps must be used to avoid having false results.
2.2. Background
DSC measures the energy produced or absorded as a function of time.
It also can be used to analyse melting, crystallization, resin curing, etc. Differential scanning calorimetry may also be applied to processes concerning a change in heat capacity of a material.
The sample is taking place in an aluminium pan. And the sample pan and an empty reference pan are placed on platforms within the DSC chamber.
There are two different way to use DSC method;
Measuring the electrical energy provided to heaters below the pans necessary to maintain the two pans at the same temperature.
Measuring the heat flow as a function of sample temperature.
2.3. Experimental
Two samples have been used; reference sample & sample. Temperature of the test was started from 20 Celsius to 130 Celsius. Temperature of the samples has been increased by device. Results has been collected automatically by software step by step. After about 30 minutes, measurement process has been finished.
Results have been automatically collected and calculated the specific heat value by software which is provided by the manufacturer of the device.
Results will be shown in next chapter in a table.
Chapter 3
3.1. Obtained Results
References
BD Dictionary; Web Finance Inc.; (June, 2017); What is business; businessdictionary.com/definition/business
Aremu, Mukaila Ayanda; Nature, Purpose and Scope of Business; Nature of Business; Page 2; Nigeria, 2011
Aremu, Mukaila Ayanda; Nature, Purpose and Scope of Business; Nature of Business; Page 2; Nigeria, 2011
ASM Engineered Materials Handbook Desk Edition (Online), Thermal Analysis and Properties of Polymers, Differential Scanning Calorimetry
LIST OF TABLES
Table 1.1. Hierarchical structure of a company…………………………………………………13
Table 1.2. Advantages and disadvantages of hierarchical structure of management…………………………………………………………………………………………………………14