Porous Metals Are Materials With Interconnected Pores Engineering Essay

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Porous metals are materials with interconnected pores. Porous metals refer to the metals with a large volume fraction of porosity, whereas the term foam applies to porous metals fabricated through the foaming process [21]. Porous metals have become the new trend materials due to their low densities, good mechanical properties and some specialized functions like air and water permeability, high energy absorption, novel physical, mechanical, thermal, electrical and acoustic properties [22].

These materials increase their opportunities in the field with a wide range of applications, such as shock and impact energy absorbers, dust filters, engine exhaust mufflers, porous electrodes, high temperature gaskets, silencers, flame arresters, heaters, heat exchangers, catalyst and construction materials [23]. Recent development and advancement of new technologies focuses on porous materials are considered for both engineering and biomedical application as these materials is biocompatible [25].

One of the metals is copper. Copper is a metal that conducts heat extremely well in its solid state and therefore the thermal properties of porous copper are of particular interest, especially when implemented as heat exchangers, heat sinks for power electronics, air-cooled condenser towers and regenerators [24].

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In this present study, the aim of the project is to investigate the effect of predetermined space holder size on thermal properties of porous copper. The porous copper will be fabricated and copper feedstock is used as raw material. Meanwhile, the NaCl will use as space holder. The powder metallurgy method is used in order to fabricate porous copper. There are three sub processes in this method which are powder technology, powder processing and characterization properties and testing.

The processes include which are blending the mixing material of copper feedstock and the NaCl, follow by Metal Injection Molding (MIM) according to the size of mold, water immersion, and sintering process. The product fabricated then will be analyze and testing using several method in order to test the thermal conductivity and hardness of the product.

Basically, powder metallurgy is the art and science of producing fine metal powders and then making objects from individual, mixed or alloyed metal powders with or without the inclusion of non metallic constituents. There are some advantages uses of powder metallurgy process. Firstly, its can fabricate the product of combination of metals and non metals. Besides, fine surface finish is achieved. No material is wasted as scrap. Porous parts can be produced which is not possible by any other method. Furthermore, highly qualified or skilled person is not required for handling powder metallurgy method. Large scale production of small parts with this process gives efficient results. Production of cemented carbide tools is possible only by this process. It eliminates numerous machining operations. Powder metallurgy parts can be easily brazed, welded, soldered. Process is economical as mass production process.

Problem statement

Nowadays, copper are widely used in industrial applications due to many factors such as an excellent corrosion resistance, superior electrical and thermal conductivity and mechanical workability. Thus, copper is widely used in heating and cooling systems, a conductor in electrical power lines, and pipelines for domestic and industrial water utilities including sea water.

A specialist in metallic and ceramic cellular materials, Nadler said the challenge of the project was creating structures porous enough to be chemically converted in a consistent way means to retaining sufficient mechanical strength to withstand processing and remain stable in finished devices.

For this current study, the different of size of space holder will be mix with the copper feedstock. Meanwhile the composition of mixture between copper feedstock and space holder is remaining constant. The thermal conductivity and strength of the porous copper produce then is analyzed by testing development.

Objective

Production of porous copper samples through powder metallurgical method and a space holder which is NaCl ( Salt). The objectives of the thesis are:

1.4.1 To fabricate porous copper samples with different size of space holder using powder metallurgy method.

1.4.2 To study the characteristics of the porous copper samples by using Scanning Electron Microscopy (SEM) and X-ray diffraction (XRD).

1.4.3 To analyze the strength and thermal property of porous copper samples

1.4.4 To investigate the porosity of porous copper samples

1.4.5 To compare the different of strength and thermal conductivity between porous copper samples and 100% of copper feedstock sample.

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Research Scope

The purpose of this project is to analyze the thermal properties of porous copper on the effect of different size of space holder. This project will use Copper feedstock as raw material and salt (NaCl) as space holder. The powder metallurgy method is selected in order to fabricate the porous copper. In fabricating the samples, the size of space holder are varies for 180µm 250µm 300µm and 355µm. meanwhile, the composition of mixture is constant for 100% which consist of 70% of copper feedstock and 30% of space holder.

The Copper feedstock will be mix with different size of space holder for blending or mixture process. Then, this mixture will go through  process  injection molding. The product specimens from injection molding wills go through water immersion in order to remove space holder. As space holder is removed, the product samples will go through sintering process. The purpose of sintering is to create one solid piece by heated the specimen to a temperature below the melting point. After that, the product will test and be analyzing through some method by using machine in order to get the thermal properties and hardness criteria of the porous copper.

Then, the samples will be analyzing using X-Ray diffraction (XRD) and Scanning Electron Microscopic (SEM). The XRD is used to analyze for the phase changes by the fabricate product. Meanwhile, the SEM is for analyzing the microstructure and porosity of the product.

Literature Study/ Review

Introduction

This part will emphasized the evaluative report of studies found in the literature that related to the present research. All information gathered will describe, summarize, and evaluate for the current thesis. This part will give a theoretical basis for the research and relative guide to determine the nature of the research. Before go further, knowing the characteristic of the raw material, copper and space holder, salt (NaCl) is very important.

Copper is metal with a reddish in color. The copper has face centered cubic crystalline structure. It is softer than zinc and can be polished to a bright finish. Copper has low chemical reactivity. In moist air it slowly forms a greenish surface film called patina this coating protects the metal from further attack.

(http://www.lenntech.com/periodic/elements/cu.htm#ixzz2DqrFtqRn )

The boiling point for copper is 2567°C. Besides, the density and melting point for copper is approximately 8.96 g/cm3 and 1083 °C. The specific physical and chemical properties of copper are key factors in the success of this material and its extensive and diversified use. In the periodic table of elements copper is in the same group as gold and silver in which it shares many of the same characteristics, also being defined as "semi" noble metal if not a true noble metal. 

Its characteristics in terms of reliability, longevity, safety, workability, protection of human health, and environmental sustainability are a guarantee for the industries and end users of the products. One of the advantages of copper which is extremely high electrical conductivity is absolutely key feature for its use in the electric and electronics industries. Copper also is an excellent thermal conductivity, heat and pressure resistance, antibacterial properties  and reliability make it the reference material for heating systems, drinking water, air conditioning or refrigeration and gas tubing. It is also extremely malleable and ductile material.

Copper also has good aesthetic characteristics such as durability, corrosion resistance and mechanical behavior are critical factors for its architectural applications. For example in mechanical components, transport vehicles, consumer goods, and minting the marine industry. The combination of all these characteristics makes copper an irreplaceable metal. (http://www.kme.com/en/unique_characteristics_of_copper)

Meanwhile, for this current study the salt (NaCl) is use as space holder. The common salt is 99.9% sodium chloride. It is obtained from the terrestrial salt deposits which are mined, heat-blasted and chemically treated. Due to these processes, salt is stripped of all minerals other than sodium and chloride. The physical properties of salt (NaCl) has a face centered cubical structure. It is a crystalline solid that is odorless and colorless or white. Its density is 2.165g/cm3. The salt (NaCl) is soluble in water, glycerol, ethylene glycol, and formic acid but insoluble in Hydrochloric acid (HCl). The melting point of sodium chloride is 801 °C and its boiling point is 1465 °C.

(Read more at Buzzle: http://www.buzzle.com/articles/table-salt-vs-sea-salt-difference-between-sea-salt-and-table-salt.html)

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Characterization of copper feedstock

2.2.1 Porous copper in application

Nowadays, the increase in demand for industrial application has lead to the growth of powder metallurgy which has created porous sintered metals for various applications[29].

It is approximate 60% copper is used in electrical equipment construction, such as roofing and plumbing. Besides, about 20% of copper is used on industrial machinery such as heat exchangers (15%) and alloys (5%). For example is copper alloy. Bronze and brass is established to produce copper alloys which was strong enough to make guns and cannons, and also was known as gun metal. Another example which is cupronickel consist of copper and nickel, was the preferred metal for low denomination coins.

( http://www.lenntech.com/periodic/elements/cu.htm#ixzz2Dr2R97G5)

As a result of its excellent electrical conductivity, copper's most ideal use especially in electrical equipment such as wiring and motors due to easily worked, can be drawn into fine wire. Furthermore, as copper slowly corrodes, it is used in roofing, guttering, and as rainspouts on buildings. It is also used in plumbing and in cookware and cooking utensils. In addition, copper sulfate is used as a fungicide and as an algicide in rivers, lakes and ponds. Meanwhile, copper oxide in Fehling's solution is widely used in tests for the presence of simple sugars namely monosaccharides.

(http://www.chemicool.com/elements/copper.html)

2.2.2 Feedstock packing density

2.2.2.1 Tap density

The tapped density is an increased bulk density attained after mechanically tapping a container containing the powder sample. The tapped density is obtained by mechanically tapping a graduated measuring cylinder or vessel containing the powder sample. After observing the initial powder volume or mass, the measuring cylinder or vessel is mechanically tapped, and volume or mass readings are taken until little further volume or mass change is observed. The mechanical tapping is achieved by raising the cylinder or vessel and allowing it to drop, under its own mass, a specified distance by either of three methods as described below. Devices that rotate the cylinder or vessel during tapping may be preferred to minimize any possible separation of the mass during tapping down.

Meanwhile, The bulk density of a powder is the ratio of the mass of an untapped powder sample and its volume including the contribution of the interparticulate void volume. Hence, the bulk density depends on both the density of powder particles and the spatial arrangement of particles in the powder bed.

( world Health Organization, March 2012 "S.3.6. BULK DENSITY AND TAPPED DENSITY OF POWDERS" Final text for addition to The International

Pharmacopoeia )

2.2.2.2 Apparent Density

Apparent density is similar to the true density except the volume of closed pores is also included. Tablets or excipient materials may have closed cells or bubbles that are not accessible to the probe gas. In this instance, gas pycnometry produces the apparent density. If the true density of a powder is known and the density of a tablet composed of this same material differs, the closed pore volume can be determined. Closed pore volume may be linked to press performance and die filling,

(micrx.com/repository/files/Density_and_Porosity)

2.2.2.3 Theoretical density

True density is the density of the solid material excluding the volume of

any open and closed pores. Depending on the molecular arrangement of the material, the true density can equal the theoretical density of the material and therefore be indicative of how close the material is to a crystalline state or the proportions of a binary mixture. True density measurements can be preformed on APIs, excipients, blends, and monolithic samples such as tablets. MPS uses Micromeritics Instrument Corporation's highprecision gas pycnometers, which are accurate to 0.02% of the sample volume to determine true density.

Characteristic of Porous Metal

2.3.1 Porosity and density

The nature of the porosity is controlled by several processing variables such as green density, sintering temperature and time, alloying additions, and particle size of the initial powders [1]. With an increase in porosity fraction (>5%), the porosity tends to be interconnected in nature, as opposed to the situation where pores are isolated (<5%) [1].

Porosity has a large effect on the heat transfer performance. Pore size has a much less effect on the heat transfer performance compared to porosity. The porosity is determined by the powder particle shape, by the powder size distribution, by the powder surface texture and by other powder characteristics which are dependent on the material processing method [12].

Increasing sintered density resulted in lower fraction, smaller average pore size, and more spherical pore shape. Increase pore size was directly correlated with an increase in the irregularity of pore shape [6].

2.3.2 Shapes and size pores

The number of cells or pores across the cross sectional area of the specimen increases with increasing the percentage of porosity. This means that the larger the number of pores, the greater the possibility of instability during compression [2]. The distribution of pores may also be inhomogeneous, because of the broad distribution of particle sizes in the sintered powder mixture, resulting in "pore clusters" where strain localization may also take place [8].

In many investigation, crack initiation was reported at pores or pore clusters located at or near the specimen surface. Holmes and Queeney [9] proposed that the relatively high stress concentration at pores, particularly surface pores, is responsible for localized slip leading to crack initiation. Christian and German [10] showed that total porosity, pore size, pore shape and pore spacing are important factors that control the fatigue behavior of powder metallurgy materials. In general, more irregular pores will have a higher stress concentration than perfectly round pores [1]

Meanwhile, the pore size of the porous metal does not have any significant affect on the thermal conductivity [4]. For the same porosity, smaller pores have a higher specific surface area, leading to greater flow resistance. Larger pores, on the other hand, generally result in less straight or longer flow path. Both can lead to lower coolant permeability and thus lower convectional heat transfer. Compared with porosity, however, the effect of pore size is much less significant [7].

2.3.3 Strength and thermal properties of porous metal

Strength

At any fixed strain value, the strength of the copper foam decreases with increasing porosity. It can be said that the higher the porosity, the thinner the cell walls [2]. The strength of the foam proved to decrease as the content of porosity increases. This is due to reducing the thickness of the cell walls and struts that are resulted by increasing the porosity [2].

Mechanical Properties such as ductility, tensile strength, shear strength, collapse strength, burst strength, and fatigue life of porous materials are highly dependent on the porosity and the processing method [13, 14]. Tensile strength, Young Modulus, Strain to Failure and fatigue strength all increased with a decrease in porosity.

In addition, mechanical properties increase significantly as the pore size and the percentage of porosity decreases [15,16,17,18]. Alternatively, permeability decreases as the pore size and the percentage of porosity decreases. Therefore, an optimum balance of mechanical properties and permeability must be achieved to meet the application. Processing methods and materials can be normally selected to create a porous copper P/M material which will meet the minimum mechanical properties and provide the maximum permeability.

THERMAL CONDUCTIVITY

On the other hand, copper conducts heat extremely well in its solid state and therefore the thermal properties of porous copper are of particular interest, especially when implemented as heat exchangers, heat sinks for power electronics, air cooled condenser towers and regenerators [3].

The relatively low quantity of metal within a porous copper sample means that the thermal conductivity will be relatively low, when compared to the parent metal [4].

The thermal conductivity of a porous copper sample is therefore mainly dependant on the relative density or porosity of the specimen, but is also dependant on the integrity and morphology of the cell walls or the morphology of the cells.

If the relative density of the porous metal is increased, the connectivity between pores will decrease, resulting in a reduction in radiative heat transfer between pores through interconnecting channels. Radiation through the cell walls is not possible in a case of optically non transparent metals. Radiation within the cells can be ignored, when the thermal conduction of the cell wall material is greater than 20 W m-1 K-1 [11].

The thermal conductivity of a porous copper sample is mainly determined by its relative density, or porosity [4]. Other material properties such as thermal conductivity, thermal expansion, fatigue, electrical conductivity and magnetic properties are also highly dependent on porosity and generally decrease as porosity increases [19,20].

Porous copper through powder metallurgy process

2.4.1 Definition of powder metallurgy process

Powder Metallurgy is science of producing metal powders and making finished or semi finished objects from mixed or alloyed powders with or without the addition of nonmetallic constituents.

The four most common porous P/M materials are bronze, stainless steel, nickel and nickel based alloys. Other materials such as titanium, aluminum, copper, platinum, gold, silver, iron, iron aluminide (Fe3Al), niobium, tantalum and zirconium are fabricated into porous materials from powder [8]. The size distribution of the particles can be a direct result of the powder manufacturing process or can be altered by sieving or air classification techniques. The characteristics, sintering conditions and commercial availability of a powder will determine whether the desired material can be manufactured into a porous structure. [12]

Selection of the fabrication method is dependent on the powder characteristics and the type of porosity required by the application. The preparation of the powders, the use of additives, the compaction methods and the sintering conditions must be carefully controlled to produce uniform and repeatable porous characteristics.[12]

2.4.2 Mixing and blending process

Blending is a process in which powders of the same nominal composition but having different particle sizes are intermingled. Blending process is done for obtaining a uniform distribution of particle sizes. For example, powders consisting of different particle sizes are often blended to reduce porosity. Besides, this process also used for intermingling of lubricant with powders in order to modify metal to powder interaction during compaction.

Next is Mixing process. The purpose of mixing process is to combining powders of different chemistries such as metal and nonmetal powders. The process can be done in dry or wet condition. Liquid medium like alcohol, acetone, benzene or distilled water are used as milling medium in wet milling. Ball mills or rod a mill is used for mixing hard metals such as carbides.

Consequently, the mixing method is depending on the extent of mixing. Mixing can be classified into three part which are perfectly mixed or uniform mixing, random mixed and totally unmixed. The mixing process should be stopped when random mixture is achieved. Otherwise, if over mixing happen, its may leads to reduced flow characteristics of the mixture.

2.4.3 Injection Molding Process

2.4.4 Sintering Process

Sintering process is performed at controlled atmosphere to bond atoms metallurgical during this process, bonding will occurs by diffusion of atoms which is done at 70% of absolute melting point of materials. It serves to consolidate the mechanically bonded powders into a coherent body having desired on service behavior. Densification occurs during sintering process and improvement in physical and mechanical properties are seen.

It is the process of consolidating either loose aggregate of powder or a green compact of the desired composition under controlled conditions of temperature and time. In this process, the high temperature materials resulting from chemical reaction between the individual constituents, will give very good bonding. Reaction sintering occurs when two or more components react chemically during sintering to create final part.

Sintering of porous metal is a critical balance between maximizing material properties and maximizing the open porosity and permeability. However, since permeability and material properties such as strength and ductility are generally inversely related, the desired balance of these characteristics normally occurs in a very small processing window [29,30]. Sintering requires the proper compromise of temperature, time at temperature and atmosphere to arrive at the desired porosity characteristics. Porous components which are not adequately sintered exhibit poor mechanical properties due to lower density and to insufficient inter particle neck growth. Porous components which are exposed to excessive sintering conditions will result in lower permeability and higher densities than desired. The preheat and cooling portions of the sintering cycle must also be closely controlled to achieve the proper metallurgical properties. The cooling conditions must be designed to provide maximum corrosion resistance and to avoid oxidation.

Sintering Temperature must be selected by considering the material, the powder shape and the powder particle size distribution. Sintering is normally accomplished at 70 - 90% of the material melting temperature. Finer powder particles require a lower sintering temperature since the surface energy driving force to initiate bond growth is much higher than for a coarser particle. Sintering at too high a temperature will also cause the formation of very large pores and non uniform porosity just prior to melting. Controlling the furnace temperature within +/- 1% of the optimum sintering temperature will achieve the best porosity uniformity and reproducible properties.

Sintering Time must be monitored to allow for a minimum exposure time at the desired sintering temperature. Sintering for at least 30 - 60 minutes at the maximum sintering temperature is recommended for most materials for sufficient bond formation and growth. Inadequate sintering time can lead to large variations in part shrinkage and final density causing porosity and permeability variations. The sintering time at temperature must allow for the temperature of the furnace load to stabilize at the desired temperature especially when batch size and furnace recovery can widely vary. Excessive sintering will unnecessarily reduce permeability due to pore size reduction and pore closure without significantly improving mechanical properties.

Sintering Atmosphere selection is critical for determining the metallurgical properties of the porous metal product. Since porous materials have much higher surface area than a similar size structural part, the atmosphere has more contact with surfaces throughout the part rather than just near the surface. Porous parts also contain relatively large amounts of trapped air in the pores which must be removed by purging or good atmosphere circulation in the furnace.

Introduction

This chapter will introduce with more details on the procedure regarding to the present research. This part will consist of phases or the flow of the project which will guide the researcher in selecting the best choice of techniques that might be appropriate at each stage of the project. Besides, this part also helps in order to plan, manage, control and evaluate research in order to achieve the objactives of the present study.

In the present study, the method selected for producing the porous copper is Powder Metallurgy with injection molding. The flow chart of the procedure regarding to the experiment is shown in figure below.

In this experiment, copper feedstock is used as the raw material and salt NaCl as the space holder. The experiment will conduct with various size of feedstock. Meanwhile, the composition of the mixture between copper feedstock and space holder is remaining constant.

Copper (Cu) Feedstock

Sodium Chloride (NaCl)

+

Blending / Mixing

Injection Molding

Water Immersion

Sintering

Final Product

Characterization of copper feedstock

Basically, the copper feedstock characterization is really important in order to know what type of binder that consists in the copper feedstock. Besides, the properties of copper feedstock itself and the binder consist will be known by characterization process. This step is very important before proceed to Powder Metallurgy process and the injection Molding.

In order to characterize the copper feedstock, the Thermogravimetric Analysis (TGA) and Differential scanning calorimetry (DSC) is used. Thermogravimetric Analysis (TGA) measures the mass change of a material as a function of temperature and time, in a controlled atmosphere. It is ideally used to assess volatile content, thermal stability, degradation characteristics, aging/lifetime breakdown, sintering behavior and reaction kinetics.

Meanwhile, Differential Scanning Calorimetry (DSC) measures specific heat capacity, heat of transition, and the temperature of phase changes and melting points.DSC also measures the rate of heat flow, and compares differences between the heat flow rate of the test sample and known reference materials. The difference determines variations in material composition, crystallinity and oxidation.

Besides, density of copper feedstock also needs to be identified. There are three type of density need to be measured which are Pycnometer density, Apparent density and Tap density. These 3 density also known as powder packing density. The concern of identifying the powder packing density is to observe the different values of density between Pycnometer density, Apparent density and Tap density.

3.2.1 Apparent density

The Arnold meter method is selected in order to observe the apparent density of copper feedstock. The aim of this experiment is to obtain the loose powder density. The formula used to identify the apparent density;

ρ=

where; m = mass of loose powder

v = volume of loose powder

3.2.2 Tap density

The important characteristic is tapped density is to abtain maximum packing density of a powder (or blend of powders) achieved under the influence of well defined, externally applied forces. In this experiment, the Autotap machine is used in order to obtain the Tap density of the copper feedstock. The general formula of density is used in determination of Tap density. Given the formula;

ρ=

where; m = mass of loose powder

v = volume of loose powder

3.2.3 Pycnometer density

Pycnometer device is used in order to get the pycnometer density as well known as the absolute or theoretical value of the density the copper feedstock and space holder (NaCl). This device is available in Chemistry Lab in Universuti Malaya. The sample of copper feedstock and space holder is sent for evaluation. From the result, the theoretical density of copper feedstock is 5.578 g/cm³. Meanwhile, the theoretical density for space holder is 2.1392 g/cm³.

Experimental Procedure

In the present study, the experimental procedure is the most important in order to achieve the objective of the research. Identification of each stage in experimental procedure is very essential in obtaining the perfect sample. Figure below shows the experimental procedure that will hold in making porous copper by using copper feedstock as the raw material and salt (NaCl) as the space holder. The experiment will be organized in order to study the effect of predetermine space holder size on the thermal properties of porous copper.

Sieving Process of space holder (NaCl)

Formulation of mixture composition

Mixing Process

Injection Molding

Water Immersion

Sintering Process

3.3.1 Sieving process

Sieve machine is a machine that uses a series of progressively finer screens to sort abrasive grains into similar sizes. For this experiment, sieve machine is used to get the space holder size of 180µm 250µm 300µm and 355µm.

C:\Users\ASPIRE 4755G\Desktop\apparatus\DSC_0366.jpg

Figure 3.3.1.a Sieve Machine

3.3.2 Formulation mixing process

For this experiment, the percentage of mixture composition is constant about 100% which consist 70% of copper feedstock and 30% of space holder.

3.3.3 Mixing Process

The aim of these operations is to make homogeneous product using

the minimum amount of energy and time

C:\Users\ASPIRE 4755G\Desktop\apparatus\DSC_0364.jpg

3.3.4 Injection Molding process

3.3.5 Water immerse process

Sintering process

The thermal treatment of a powder or compact at a temperature below the melting point of the main constituent, for the purpose of increasing its strength by bonding together of the particles. sintering temp is in general nothin but the temp at which the grains of solid formed from powder start connecting through its boundries and merge so forms a larger grain. its generally between 2/3rd of melting temp of that material. The idea of sintering is heating a powder until it is hot enough to stick to itself, then reshaping it and letting it set. The temperature used is always lower than the melting point of the material.

3.4 Method to analyze of sample

3.4.1 Scanning electron microscopy (SEM)

The scanning electron microscope (SEM) uses a focused beam of high-energy electrons to generate a variety of signals at the surface of solid specimens. The signals that derive from electron-sample interactions reveal information about the sample including external morphology (texture), chemical composition, and crystalline structure and orientation of materials making up the sample

3.4.2 X-Ray diffraction (XRD)

X-ray powder diffraction (XRD) is one of the most powerful technique for qualitative and quantitative analysis of crystalline compounds. The technique provides information that cannot be obtained any other way. The information obtained includes types and nature of crystalline phases present, structural make-up of phases, degree of crystallinity, amount of amorphous content, microstrain & size and orientation of crystallites.

3.4.3 Thermal Conductivity Test

3.4.4 Hardness Test

3.4.5 % Porosity

3.4.6 Expected Result

2.3.1 Density and Porosity

Porosity is defined as the percentage of void spaces present in the solid [15]. Porous materials are also named as cellular solids, which means an assembly of cells with solid edges or faces, packed together to fill the space. These materials are very common in nature, and the examples include wood, cork, sponge and coral [16]. Porous materials and metallic foams with cellular structure are well known for its interesting combination of physical and mechanical properties, such as high thermal conductivity, low specific weight and high permeability. The man made porous or cellular materials were established in pyramids of Egypt for the purpose of wooden artefacts which is at least 5000 years ago, cork for bungs in wine bottles were also established in roman times (27 BC). The recent development in scientific world gives the opportunities for the man- made cellular materials which is useful for lightweight structural and functional applications [17].

Methodology

Introduction

This chapter will introduce with more details on the procedure regarding to the present research. This part will consist of phases or the flow chart which will guide the researcher in their choice of techniques that might be appropriate at each stage of the project and also help in order to plan, manage, control and evaluate research.

In the present study, the method selected for producing the porous copper is Powder Metallurgy with injection molding. The flow chart of the procedure regarding to the experiment is shown in figure below.

Metal injection molding (MIM) has emerged as a viable method of producing complex shaped parts at a competitive cost. The MIM process uses a combination of powder metallurgy and injection molding technologies to produce net-shape parts and is comprised of five main sub processes which are raw materials selection (powder/binder), feedstock preparation, injection molding, debinding, and sintering. One of the advantages of powder injection molding is its ability to produce parts with complex geometry without machining. However, to stay within the ever tighter tolerances demanded by component manufacturers' customers, MIM parts have to be produced with a high degree of dimensional control in order to minimize the dimensional variability of critical dimensions.

This project will carry out to investigate the effect of size salt (NaCl) on thermal properties of porous copper. Some method involve in order to determine the thermal properties of porous copper such as Differential scanning calorimetry (DSC), Thermo gravimetric Analysis (TGA), X-ray powder diffraction (XRD).

The experimental result will compare with the actual result of copper as shown below.