project

The project report / dissertation titled _________________________________________

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is the bonafide work of Mr./ Ms. ______________________________________________, and bearing student number ______________ is carried out under my supervision. I certify that the work presented in the project report / dissertation is carried out by him / her, and that he / she has achieved the set objectives of the project / dissertation. Information derived from the published work of others has been acknowledged in the text and a list of references is given at the end of the report. I have personally checked this final report for originality / plagiarism through the Turnitin website and, to the best of my knowledge and belief, satisfied that the report is free from plagiarism.

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ACKNOWLEDGEMENT

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ABSTRACT

Aluminum plays an important role in a number of industrial applications such as construction and electrical engineering. It is also quite applicable in the transport industry where it is used in the manufacturing and production of machinery used in the aircraft building. Although aluminum and its alloys are quite useful, they are subject to corrosion as are a result of chemical interaction with the surroundings and hence do not the best materials for engineering applications. One of the main significant problem faced by aluminum components used in the aircraft is pitting corrosion. An experimental analysis of components of aluminum in aircraft to identify corrosion will be carried out in this project. Findings indicate severe corrosion of nose landing component leading to its failure. Pitting corrosion refers to the restricted high metal dissolution as a result of depletion of the passive film on the metal surface that acts as a protective cover. This study aims at bringing into discussion an analysis of corrosion in the aluminum alloy (7076) mainly used in aircraft components. Therefore, this project identifies the details on materials, undertaking taste samples on the identified materials, and measures are undertaken to improve corrosion resistance. Hence, development of the two types of coating, and testing their levels of resistance to corrosion.

This experiment identifies two types of heat treatment experiments useful in testing samples with and without coating condition. An examination will be carried out on the behavior of the metal using hardness testing before and after heat treatment, measurement of the surface roughness, corrosion test under wet conditions. Analysis of these results finally will be carried out to achieve the objectives successfully.

‏Keywords: Aluminum alloy (7076) , Pitting corrosion, Hardness testing, Heat treatment.

TABLE OF CONTENTS

The content shall follow the abstract and indicate the page numbers of the chapters, sections, sub-sections, appendices and references. The number and titles of all the items must be clearly entered with page numbers against them.

LIST OF TABLES

Inside the body of the report use Table captions: Arial, size 11. Decimal type notations will be used for numbering the tables in a chapter (e.g. Table 1.1, Table 4.2 etc.)

LIST OF FIGURES

Inside the body of the report use Figure captions: Arial, size 11. Decimal type notations will be used for numbering the figures/photos, charts and drawings in a chapter (e.g. Figure 3.2 , Figure 4.2 etc.)

LIST OF SYMBOLS AND ABBREVIATIONS

Chapter name & title

Nomenclature will follow the contents. Its purpose will be to define all the symbols, abbreviations, Greek or Latin letters, superscripts etc.

1

10

CHAPTER 1 INTRODUCTION

Corrosion is the deterioration of materials by chemical interaction with the surrounding environment, it is a natural phenomenon which can be controlled by correcting the condition when an early warning signs occurs. Airframe issues related to corrosion have plagued the aerospace industry for decades. The metals of aircraft components are exposed to different forms of corrosion, there are many agents which accelerates the corrosion process such as prolonged exposure to corrosive factors including moisture, slats and industrial fluids. The main source of corrosion is water vapor containing salt that combines with the oxygen in the air. The appearance of corrosion differs depending on the type of the metal, on the aluminum alloy surface it shows as pitting which is combined with white or gray powdery deposit. This project will provide an experimental study on the corrosion analysis of aluminum alloy where 75% of aircraft structures are made of aluminum as shown in Figure 2.

Figure 1.1 Pitting Corrosion

Figure 1.2 Aircraft material

1.2 The aim of the project:

To perform an experimental study about corrosion analysis of aluminum alloy material used in aircraft component.

· Identify the causes of corrosion.

· Carry out the corrosion resistance process experimentally.

· Analyze the obtained result.

· Implement roughness measurement of the coated samples followed by corrosion test with sea water and acid.

Understanding and analyzing the corrosion behavior is important, there are many factors regarding the significance of corrosion study including economic, by implement corrosion control process, the useful life of aircraft can be extended, therefore the maintenance cost will be reduced. Also, the best insurance against corrosion associated failures is studying and testing the metals used in the design of the planes in order to select the proper ways to control the problem to increase the safety of public.

CHAPTER SUMMARY

CHAPTER 2: LITERATURE REVIEW

2. Introduction.

Adeyemi Dayo Isadare, Bolaji Aremo, Mosobalaje Oyebamiji Adeoye, Oluyemi John Olawale, Moshood Dehinde Shittu, (2013) work entails a detailed explanation of their experiment which involved an examination of annealing on micro-structural morphology as well as mechanical properties of 7075 Al alloy. Additionally, the experiment evaluated the relationship between age hardening on microstructural characteristics of 7075 alloy. The researchers concluded from the experiment results that annealing heat treatment had the power to do away with micro-segregation. Age hardening heat treatment was also observed to bring an improvement on mechanical characteristics of the Alloy (Isadare, Aremo, Adeoye, Olawale & Shittu, 2013). This work perfectly fits the topic since it shed light on how the project topic can be handled. This stem from the fact that the work reveals that age hardening heat treatment can improve the mechanical property of the aluminum alloy. One such characteristic is resistance to corrosion. To make the allow resistant to corrosion by other elements or acids using the results from Adeyemi Dayo Isadare, Bolaji Aremo, Mosobalaje Oyebamiji Adeoye, Oluyemi John Olawale, Moshood Dehinde Shittu (2013) work it’s hence recommendable to do age hardening heat treatment.

Patricia Kavalco, Canale Lauralice and George Totten (2009) research entails the study of intergranular corrosion (IGC). The researchers investigated how intergranular corrosion could be used to reduce corrosion. In the study, it was found out that the cooling rate of any aluminum alloy determined the rate of pitting corrosion. The slower the rate of cooling the fewer chances an aluminum allow being affected by corrosion. On the other hand, if an alloy was quickly cooled the impact would be that the alloy would be easily corroded by corrosive reagents or chemicals (Kavalco, Lauralice & Totten, 2009). On that note, the authors recommend that while making any aluminum allow it was crucial to give attention to the cooling rate. In the event that the alloy will be exposed to highly corrosive agents, it is advisable to have the cooling rate very slow and vice versa. This work is useful in informing the topic that is corrosion in Aluminum alloy. With the findings from the source, one can state that corrosion in aluminum alloys is dependent on the rate of cooling of the alloy during its making.

Jasim Salman, Shaymaa Alsada and Khadim Al-Sultani (2013) work discusses the results of their experiment. The experiment was set up to investigate the impact of sodium chloride, polyethylene glycol and boron on aluminum alloy. The authors wanted to know whether the combination of these solutions or elements could improve the feature of the 7075-T6 alloy. The target features were corrosion resistance, toughness as well as thermal aging behavior. The researchers took 3.5% NaCl, 30% polyethylene glycol and Boron solution and treated 7075- T6 alloy with. The results indicated that the solution improved the toughness feature of the alloy by 50%. However, the corrosion property was not significantly influenced by the solution. This indicates that the solution cannot be used to improve the corrosion resistance of the alloy (Salman, Alsada& Al-Sultani, 2013). Generalizing the case to other types of aluminum alloys one can draw an insight that a mixture of boron, sodium chloride and polyethylene glycol have no properties in improving the corrosive resistance feature of an aluminum alloy. On that note, the work is significant in this topic since it gives direction on elements and solution which should not be used while improving the resistance features of an aluminum alloy.

Tolga Dursun and Costas Soutis (2014) work is about their review on the recent aluminum technology employed in aircraft industry which is one area aluminum alloys are industrially exploited. The authors learned that the technology has led to having damage tolerant, strong, tough and corrosion resistant alloys. The review shows that a combination of Aluminum and zinc leads to a very strong alloy. Mixing Aluminum and copper results to a high damage resistant alloy. Of key importance in this context is mixing aluminum and lithium that is AL-Li. The outcome is an alloy with improved properties such that the alloy is has higher fracture toughness and is corrosion resistant (Dursun& Soutis, 2014). This work is essential in the study of this topic from the angle that it shows the right chemical composition that can be used to have a high corrosion resistant alloy.

The work entails a history of aerospace technology with aluminum alloys in focus. Also, entails classification of aluminum alloys. The classification is based on temperatures used to heat and cool the alloys. This is because the temperatures are a significant determinant of the strength property as well as other features (Rambabu, Prasad& Wanhill, 2017). Additionally, the work entails weaknesses or gaps in the current aluminum technology used in aerospace. These gaps are crucial in handling the topic given that they will show areas that require more research in improving the corrosion resistance feature of aluminum alloys.

2.6 Aluminium alloy corrosion of aircraft structures: modelling and simulation.

To prevent corrosion occurrences, Aluminum and its alloys were properly handled using various protection methods that prevent corrosion of the aircraft. These methods include: waxing, painting, zinc-chromate priming, coating using thin layer of Alclad, anodizing and coating with a liquid protective solution (DeRose, 2013 pg. 23-29).

Barrier coating using materials such as paint, plastic, wax or powder was applied and left out for some time for later observations. Aluminum was also coated using a thin layer of pure aluminum. Pure aluminum was successfully sprayed on the aluminum flat and round coupons at low temperatures. Hardness test was then carried out before and after the heat treatment Demo, (Steiner, Friedersdorf, and Putic, 2010 pg. 1-9). Aluminum specimen was heated at 500 Celsius and then quenched in cold oil. Hardness of the heat-treated specimen and those without heat treated specimen was measured in and recorded. Resistance to corrosion of the samples was evaluated in 3.5 % sodium chloride solution by weight loss method. Corrosion test was also conducted in wet conditions which included seawater and hydrochloric water conditions. Roughness measurements were also conducted on the final product.

2.7 Milestone case histories in aircraft structural integrity.

We found out that epoxy, nylon and urethane which are types of powders, which were heated and placed on the aluminum surface to form a thin film layer offered protection from corrosion. Plastic and waxes which were sprayed onto the aluminum surfaces acted as a coating to offer protection to aluminum surface from mixing with other corrosive elements that lead to corrosion (Wanhill, Molent, Barter and Amsterdam, 2015 pg. 346) People have come up with current painting systems in the aircraft components that combine different painting layers which have been designed to serve different functions. They are usually applied in three layers. The first spray paint acts as the inhibitor which decreases the activity of the aluminum and its alloys or blocks it from combining or reacting with other corrosive elements. The second and intermediate layers of paint coats are applied to add to the overall thickness of the paint and to make sure that no aluminum surface is left exposed (Kiyak, 2012 pg. 9-16) The last and finish coat is primarily designed to offer resistance to the environmental factors such as humidity, pH concentration and alkaline concentration of the surrounding. We also found out that pure aluminum coating component insulates and protects aluminum from corroding. This helped in reducing the extent of corrosion.

2.8 Can pitting corrosion change the location of fatigue failures in aircraft?

Regarding hardness test, it was found out that after heat treatment at 500 °C and subsequent quenching in oil of aluminum component the hardness and corrosion resistance of pure aluminum improved whereas before heat treatment, the hardness and corrosion resistance of the material was low. Concerning corrosion in wet areas, we found out that aluminum corrodes faster or quicker when placed in wet areas. This is because the water component acts as a catalyst in the process of corrosion (Crawford, Loader, Liu, Harrison, and Sharp, 2014 pg. 304-314). When Aluminum, which is the material used to make aircrafts, is left unprotected in certain areas such as salty areas near the ocean or sea waters, it will form an oxide layer and corrodes almost immediately. Because of the corrosive action of this strongest of acids like hydrochloric acid on metals like aluminum, normally, non-metal materials are preferred, when possible (Jaya, Tiong, and Clark, 2012 pg. 64-73). Aluminum have useful corrosion resistance in low concentrations of HCl. The corrosivity increases dramatically as the concentration of HCl and temperature increase. This led to an increased rate and extent of corrosion. Therefore, the extent of destruction was higher in wet areas as compared to that one in dry areas.

2.9 Recent developments in advanced aircraft aluminium alloys. Materials & Design.

The main disadvantage of using coating as a method of preventing corrosion is that the coating components need to be reapplied over and over again which is tiring and expensive. Poorly applied coatings always fail and can lead to increased rate and increased extent of corrosion (Dursun and Soutis, 2014 pg. 862-871). Sometimes, there might exist some volatile organic components in certain coatings which make them vulnerable to corrosion.

2.10

This section provides some past researches and works related to corrosion; each author studied the topic from different areas including the relationship between age hardening on microstructural characteristics of Al 7075 alloy which concluded from the experiment results that annealing heat treatment had the power to do away with micro-segregation. Also, investigation on how intergranular corrosion could be used to reduce corrosion where the authors recommend that while making any aluminum allow it was crucial to give attention to the cooling rate. Moreover, another author discussed the impact of sodium chloride, polyethylene glycol and boron on aluminum allow. In addition to another review shows that a combination of Aluminum and zinc leads to a very strong alloy. As well as the classification of aluminum alloy were studied, and the author concluded that the classification is based on temperatures used to heat and cool the alloys. This is because the temperatures are a significant determinant of the strength property as well as other features. Also, barrier coating is one of the easiest and cheapest methods in preventing corrosion in aircraft components made of aluminum. It was very effective in preventing corrosion but only if proper procedures were carried out carefully. Coating, therefore, insulates, beautifies and increases the aircraft’s life expectancy. It is also easy to apply and reflects 80% of ultraviolet rays. Though it faces certain challenges, it is very effective in preventing corrosion in aluminum, an aircraft component.

CHAPTER 3 EXPERIMENTAL SETUP

3. Introduction.

This chapter includes the steps

3.1 Samples preparation.

For an accurate and fast cutting of the Aluminum alloy sheet, a mechanical guillotine called Morgan Rushworth RGMS is used.

Figure 3.2 Aluminum alloy sheet before cutting

Figure 3.1 Morgen Rushworth RGMS

The working principle of this machine is:

1. Place the Aluminum sheet on the

Figure 3.3 Aluminum alloy sample after cutting

Then, using metal stamps and hammer the numbering step is done by applying the following procedure:

1. Place the desired number stamp on the sample.

2. Strike twice on the stamp using the hammer.

3. The number will appear on the sample.

4. Repeat the steps using different numbers for different samples.

Figure 3.4 Metallic Stamp

Figure 3.5 Hammer

Figure 3.6 Samples After Numbering

3.2 Coating step.

In this step I used three types of coating: Al2O3 (Aluminum Oxide), Zinc and Underbody Rubber coating.

3.2.1 Aluminum Oxide coating:

To achieve this type of coating an Aluminum Oxide powder, Aluminum paint and a brush is needed. The procedure is:

1. Prepare a mixture of 25 ml of Aluminum paint with 250 g of Al2O3.

2. Place the mixture in the rotary shaker for one hour.

3. Apply the Aluminum oxide mixture on the sample using a brush.

4. Put the coated sample in a place to be exposed to air for three hours in order to dry then apply an extra layer if needed.

Figure 3.7 Aluminum Oxide and Aluminum paint.

Figure 3.8 During the painting step.

Figure 3.9 Sample after applying the first layer of coating.

3.2.2 Zinc coating:

Zinc spray provide …….

The following is the procedure for Zinc coating:

1. Shake the can well before using.

2. Spray evenly on the samples about 20 cm distance from the surface.

3. Put the coated sample in a place to be exposed to air for three hours in order to dry.

4. Repeat the second step until the desired thickness is obtained.

Figure 3.11 The samples after zinc coating.

Figure 3.10 Zinc spray and the samples before coating.

3.2.3 Underbody Rubber coating:

This type of coating is………………………..

The following is the procedure for underbody rubber coating:

1. Shake the can well before using.

2. Spray evenly on the samples about 20 cm distance from the surface.

3. Put the coated sample in a place to be exposed to air for three hours in order to dry.

4. Repeat the second step until the desired thickness is obtained.

Figure 3.12 Underbody Rubber Spray.

Figure 3.13 Samples after rubber coating.

3.3 Heat Treatment.

Heat treatment is …………………………

3.3.1 Annealing.

Metallographic and hardness test piece samples to 470 °C, soaking them at this temperature for 2 hours and then furnace cooled. (paraphrase this paragraph)

3.3.2 Precipitation hardening.

Metallographic and hardness test piece samples at a temperature of 465 °C for 2 hours followed by rapid quenching in cold water. These quenched samples were then subjected to a precipitation hardening treatment (age hardening) by heating them to 120 °C, holding them at this temperature for 3 hours and then followed by air cooling to room temperature. As shown in figures below. (paraphrase this paragraph).

3.4 Hardness Test.

Using Rockwell hardness test which is …………………..

The working principle of this device as following:

1. Select the proper indenter depending on the type of the alloy to be measured, for Aluminum Alloy 1/8 ball is used.

2. Turn the device on.

3. Place the sample to be measured on top of the anvil.

4. Rotate the anvil adjustment clock wise in order to rise the anvil till it touch the surface of the sample.

5. The reading will appear on the screen, write it down and repeat the steps using different coating samples.

Figure 3.15 Indenter used for testing.

Figure 3.14 Rockwell hardness tester.

3.5 Roughness Measurements.

Roughness is ……

The following are steps to measure the roughness of the samples:

1. This device is connected to the computer software, first turn on the computer.

2. Place the sample to be measured as shown on Figure, notice the movement of the tip on the surface of the sample for about 5 seconds.

3. The surface roughness measurements will show on the computer screen.

4. Repeat the steps using different coating samples.

Figure 3.17 During roughness measurement for zinc sample.

Figure 3.16 Roughness device (Mitutoyo) connected to computer software.

3.6 Corrosion Test in sea water.

Sea water ……………………

The samples with and without coating were immersed in sea water for 8 days and the weight was measured.

3.7 Corrosion Test in Hydrochloric Acid (HCl).

In this step, a solution of 100ml of HCl and 900ml of H2O was prepared and the samples with and without coating were treated with the solution for 10 minutes and the weight of the sample before and after the test were measured in order to monitor the weight loss.

Figure 3.18 Apparatus used.

Figure 3.19 HCl solution.

Figure 3.20 Sample initial weight.

Figure 3.21 Sample weight after sea water test.

Figure 3.22 Sample weight after HCl test.

CHAPTER SUMMARY.

CHAPTER 4 RESULTS AND DISCUSSIONS

4. Introduction.

4.1 Hardness Test (before and after heat treatment).

Table 4.1 Hardness readings before heat treatment.

Table 4.2 Hardness readings after heat treatment.

Figure 4.1 Hardness Readings Before Heat Treatment.

Figure 4.2 Hardness Readings After Heat Treatment.

As a result, the hardness after heat treatment increase……….

Observed that zinc has highest hardness value…….

4.2 Roughness measurements.

Figure 4.1 Zinc Sample Roughness Profile.

Figure 4.2 Underbody Rubber Sample Roughness Profile.

Figure 4.3 Aluminum Oxide Sample Roughness Profile.

Figure 4.4 Without Coating Sample Roughness Profile.

4.3 Weight loss.

This step involves two parts, sea water for 8 days followed by hydrochloric solution for about 5 minutes. The following table shows the weight loss of each coating type.

CHAPTER SUMMARY.

CHAPTER 7 CONCLUSIONS

Present the conclusions based on the results

CHAPTER 8 RECOMMENDATIONS/FUTURE WORK

Give suggestions for future work based on conclusions

REFERENCE

1. Aircraft Material, 2015. [Online]. Available from: https://image.slidesharecdn.com/presentation-thehistoryofaircraft-151221144928/95/presentation-the-history-of-aircraft-20-638.jpg?cb=1450709452 [Accessed: 6 December 2018].

2. Dursun, T. & Soutis, C., 2014. Recent developments in advanced aircraft aluminum alloys, Materials and design, 18(2), pp.23-29.

3. Isadare, A., Aremo, B., Adeoye, M., Olawale, O. & Shittu, M., 2012. Effect of heat treatment on some mechanical properties of 7075 aluminium alloy. Materials Research, 16(1), pp.190-194.

4. Kavalco, P., Lauralice, C.& Totten, G., 2009. Quenching of aluminum alloys: cooling rate, strength, and inter-granular corrosion‖, Heat treating progress, 11(2), pp.44-52.

5. Pitting Corrosion on aircraft engine crankshaft, 2017. [Online]. Available from: https://publicapps.caa.co.uk/docs/33/CAP1570_Corrosion.jpg. [Accessed: 8 December 2018].

6. Publicapps.caa.co.uk, 2017. Corrosion and Inspection of General Aviation Aircraft. [Online] Available at: https://publicapps.caa.co.uk/docs/33/CAP1570_Corrosion.pdf [Accessed: 8 December 2018].

8. Salman, J., Alsada, S. & Al-Sultani, K., 2013. Improvement Properties of 7075-T6 Aluminum Alloy by Quenching in 30% Polyethylene Glycol and Addition 0.1%B‖, Research Journal of Material Sciences, 15(4), pp.32-42.

9. Dursun, T. and Soutis, C., 2014. Recent developments in advanced aircraft aluminium alloys. Materials & Design (1980-2015), 56, pp.862-871

10. Crawford, B.R., Loader, C., Liu, Q., Harrison, T.J. and Sharp, P.K., 2014. Can pitting corrosion change the location of fatigue failures in aircraft?. International Journal of Fatigue, 61, pp.304-314.

11. Wanhill, R.J.H., Molent, L., Barter, S.A. and Amsterdam, E., 2015. Milestone case histories in aircraft structural integrity.

12. Crawford, B.R., Loader, C., Liu, Q., Harrison, T.J. and Sharp, P.K., 2014. Can pitting corrosion change the location of fatigue failures in aircraft?. International Journal of Fatigue, 61, pp.304-314.

13. Demo, J., Steiner, A., Friedersdorf, F. and Putic, M., 2010, March. Development of a wireless miniaturized smart sensor network for aircraft corrosion monitoring. In 2010 IEEE Aerospace Conference (pp. 1-9). IEEE.

14.

APPENDIX I

Use extra appendixes or sections as per your requirements, the appendix may contain data, formula sheet, programmes, and extra diagrams which is required for the work and etc. as applicable for the work.

TURNITIN REPORT

Provide the first page of the Turnitin report

TECHNICAL PROJECT PROPOSAL

Provide the revised / approved TP proposal

Hardness Readings Before Heat Treatment.

Reading (g) Aluminum Oxide Zinc Underbody Rubber Without coating 132.1 139.80000000000001 135.19999999999999 129.6

Hardness Test After Heat Treatment

Reading (g) Aluminum Oxide Zinc Underbody Rubber Without coating 132.1 139.80000000000001 135.19999999999999 129.6

RProfile

[mm]

[um]

RProfile

[mm]

[um]

RProfile

[mm]

[um]

RProfile

[mm]

[um]

Surface roughness measurments

Rz (µm) Zinc Aluminum Oxide Underbody Rubber Without coating 7.06 8.44 11.18 1.81 Rq (µm) Zinc Aluminum Oxide Underbody Rubber Without coating 1.32 2.7 1.44 0.35

Type of coating

Measurment of surface roughness Rz and Rq