Flash sintering is an electrical field-assisted consolidation technology and represents a very novel technique for producing ceramic materials, which allows to decrease sensibly both processing temperature and time. Starting from 2010, when flash sintering was discovered, different ceramic materials with a wide range of electrical properties have been successfully densified. Up to date, the research on flash sintering has been mainly focused on ionic and electronic conductors and on semiconductor ceramics. In the present work, we studied the flash sintering behavior of a resistive technical ceramic like alumina also in the presence of magnesia silicate glass phase typically used for activating liquid phase sintering. The materials were studied by using different combinations of electric field and current density. Physical, structural and microstructural properties of sintered samples were extensively investigated by Archimedes’ method, SEM, XRD, XPS and pholuminescence spectroscopy. Light emission and electrical behavior during the flash process were studied,as well. The results point out the applicability of flash sintering to alumina and glass-containing alumina using electrical-field in excess of 500 V/cm, allowing an almost complete densification at temperatures lower than 1000°C. Different densification mechanisms were pointed out in the two systems, namely “solid state flash sintering” and “liquid phase flash sintering” for pure alumina and glass containing alumina, respectively. The glass addition allows a significant reduction of the current and power dissipation needed for densification, by promoting liquid phase sintering. The results suggest that unconventional mass transport phenomena are activated by the current flow in the ceramic body and they can be very likely attributed to partial reduction of the oxide induced by the electrical current. The hypothesis that the oxide gets partially reduced during DC-flash sintering experiments is supported by several experimental findings. Finally, strong affinities between flash sintering and other physical processes, like dielectric breakdown, were pointed out.

Nel corso dell'Ottocento, Torino fu uno dei principali centri di elaborazione e diffusione delle teorie evoluzionistiche in Italia. Le ricerche furono indirizzate dapprima dal modello trasformistico di Lamarck e, a partire dagli anni '60, dalla teoria darwiniana. Il lavoro ricostruisce lo sviluppo delle indagini in zoologia e in alcune discipline ad essa collegate, come la paleontologia e l'antropologia, approfondendo anche il dibattito nato sui periodici scientifici, le opere divulgative e i giornali. Tale ricostruzione si accompagna ad uno studio delle interferenze tra gli orientamenti teorici adottati dagli scienziati e le fasi del cambiamento politico-sociale che si succedettero nel corso del secolo.

This PhD thesis focuses on the investigation and development of a feasible technology route for fabricating multifunctional flexible electronic devices through heterogeneous integration of organic/inorganic materials on polymeric substrates. The three types of printing technologies investigated during this research include: (a) Transfer printing of inorganic semiconductors processed through standard microfabrication techniques, (b) Spray coating for deposition of organic dielectrics and metal patterns, and (c) Screen-printing of solution based transducer materials. Fabrication of electronic devices based on transfer printing of high-mobility inorganic semiconductor materials (i.e. Si), aided by high-resolution possible with microfabrication technology, was explored for high performance electronics. A cost-effective processing of printable materials is desired and therefore, through printing technologies, this thesis also explored ways to bring closer the well-established microfabrication and conventional printing tools. Due to commercial interests, the major research focus in flexible electronics thus far has been on applications such as photovoltaics and displays. However, this research is focused on active/passive electronics for sensing applications like electronic skin, which is of significant interest in robotics for safe human-robot interaction and other manipulation and exploration tasks. Optimization of the Transfer Printing for translating Si microwires from SOI (silicon on insulator) wafers on secondary flexible substrates has been investigated. Processing steps have been improved for fabrication of Si microwires on donor wafers and dry transferring them onto flexible PI (polyimide) and PET (polyethylene terephthalate) substrates. The downscaling of Si in the form of microwires and using them as building block for active devices such as field effect transistors were explored in this thesis. The microwires retain the high carrier mobility, robustness, high performance and excellent stability. Arrays of MISFETs (metal insulator field effect transistors) structures were successfully fabricated and the response variations were compared. The differently doped Si microwires were analyzed in an asymmetric metal semiconductor metal (MSM) structures under planar and bend mode conditions. The optical response as well as the thermoelectric properties of the alternately doped pn-Si microwires were also investigated. A feasible fabrication route is presented, where combination of transfer printing for Si microwires and development of the subsequent post-processes by additive manufacturing techniques i.e. Screen-printing, Spray coating and Micro-spotting are mainly investigated. The Si microwires are employed as the semiconductor in the MISFET devices whereas screen-printed metal patterns are used for back-gate and deposition of dielectric layer is performed through spray coating. In parallel, screen-printing is also used for development of large area pressure sensor patches using two different materials i.e. P(VDF-TrFE) (Polyvinylidene Fluoride Trifluoroethylene) and nanocomposites of MWCNTs/PDMS (multiwall carbon nanotubes mixed with poly(dimethylsiloxane) for measuring dynamic and static contact events. Promising results have been achieved by developing a cost-effective way of manufacturing an all Screen-Printed flexible pressure sensors using piezoelectric transducer through P(VDF-TrFE) and piezoresistive based MWCNT/PDMS nanocomposites. Active electronic circuitry is needed for signal conditioning, amplification or processing of the sensory data on the flexible foils, which is deemed to be developed through Si microwires based technology in the next phase of the project. Ultimate goal of the PhD study was to develop a fabrication platform by combining three different printing technologies for large area sensor patches. Major challenges involved in the development of flexible device designs and printing technologies are highlighted and addressed with dependable solutions. The research concludes with proposing an innovative approach towards heterogeneous integration of large area sensory cells made of organic materials to the active devices based on inorganic semiconductors such as Si microwires. This technological platform for heterogeneous integration of devices made of diverse materials (organic, inorganic etc.) on soft substrates is believed to be a step-change needed to advance flexible electronics towards manufacturing.

Accurate statistical characterization of nanomaterials is crucial for their use in emerging technologies. This work investigates how different structural characteristics of metal nanoparticles influence the line profiles of the corresponding powder diffraction pattern. The effects of crystallite size, shape, lattice dynamics, and faulting are all systematically studied in terms of their impact on the line profiles. The studied patterns are simulated from atomistic models of nanoparticles via the Debye function. This approach allows for the existing theories of diffraction to be tested, and extended, in an effort to improve the characterization of small crystallites. It also begins to allow for the incorporation of atomistic simulations into the field of diffraction. Molecular dynamics simulations are shown to be effective in generating realistic structural models and dynamics of an atomic system, and are then used to study the observed features in the powder diffraction pattern. Furthermore, the characterization of a sample of shape controlled Pt nanoparticles is carried out through the use of a developed Debye function analysis routine in an effort to determine the predominant particle shape. The results of this modeling are shown to be in good agreement with complementary characterization methods, like transmission electron microscopy and cyclic voltammetry.

Cuprite (Cu2O) and tenorite (CuO) have been extensively studied because of their potential use in several electronic applications, which include solar cells and gas sensors, just to mention the most appealing ones. Both materials are p-type semiconductors, the one with a wide bandgap (Cu2O, 2.0 eV-2.2 eV), the other with a much narrower one (CuO, 1.2 eV-1.8 eV), and both show interesting optical properties in the visible and near-visible range. This Thesis work is devoted to the synthesis, characterisation and application of nanostructured copper oxides in the field of renewable energies. Within this broad scope the Thesis focuses on: • production of defect-free nanocrystals (Cu2O & CuO) and investigation of the correlation between experimental parameters and resulting microstructure; • production of highly defective nanocrystalline Cu2O powders, with the estimation of the effect of milling on microstructure and phase transformations; • production of inks for photonic applications in photovoltaic cells. Reverse micelle microemulsions (a bottom-up approach) have been employed for the production of the defect-free nanocrystals. Models have been proposed for the nanocrystal formation and growth, validated by means of several techniques such as X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM), UV-Visible and Fourier Transform InfraRed spectroscopy (UV-Vis and FTIR). The produced nanocrystals show good crystallinity with Cu2O and CuO exhibiting cuboidal and rod-like structures, respectively. The nanometric nature of the primary domains (20 nm – 4 nm) leads to quantum confinement phenomena highlighted by photoluminescence measurements. A top-down approach has been exploited to produce highly defective particles to be possibly employed in new-generation intermediate-band solar cells. A high-energy mill, suitably modified to work in controlled temperature and environment, allowed the production of highly defective copper oxides with little or no phase transformation and contamination from the mill. Finely dispersed powders with a high density of line defects (ρ ≈ 4×10-16 m-2) were ultimately obtained. The effect of milling on the microstructure evolution was investigated using both traditional and synchrotron radiation XRD line profile analysis supported by High Resolution TEM and SEM. The synthesised powders were employed for the production of copper oxide inks for photonic applications. Those inks would allow solar cells to be directly printed on a substrate, with a dramatic reduction of production costs and the possibility of coating objects of any shape. Sprayed films usually need high consolidation temperatures: the proposed formulation, on the contrary, allows sintering of the ink-derived films at a relatively low temperature (below 600 °C), thus making possible the deposition on inexpensive substrates such as aluminium. Prototype solar cells based on the copper oxide inks have been fabricated using simple coating techniques. Results can be considered as a first step towards the production of fully recyclable solar cells, made of low-cost raw materials and realized by cost-effective deposition techniques.

In the last years it has been widely proven that the introduction of very small amounts of inorganic nanoparticles in polymeric matrices can lead to noticeable improvements of their mechanical properties, in terms of elastic modulus and tensile properties at yield and at break. Linear low density polyethylene (LLDPE) is widely applied in several industrial applications, especially for the production of transparent high performance film for the packaging industry. The objective of this work is to study the role played by different kinds of amorphous silica (SiO2) micro and nanoparticles on the viscoelastic and fracture behaviour of LLDPE based composites, prepared through a melt compounding process. Different typologies of silica filler have been considered : hydrophilic and hydrophobic fumed silica nanoparticles with different surface area, precipitated silica microparticles, and silica glass microbeads. In this way it has been possible to study the influence of the filler dimensions and morphology on the viscoelastic behaviour of the prepared composites, both in the molten and in the solid states, and on their fracture properties. In the first part of the work, a detailed microstructural characterization was performed to assess the different morphologies and surface properties of the utilized powders. Furthermore a detailed analysis of the dispersion state of the fillers in the matrix and of the thermal behaviour of the prepared composites was also conducted through optical and electron microscopy. In the second part of the work, viscoelastic behaviour of the composites in the molten state was studied through dynamic rheological tests. It was evidenced how the introduction of fumed silica nanoparticles and precipitated silica microparticles could lead very strong enhancement both of the storage (G’) and shear moduli (G’’), and of the viscosity (η), at low frequencies, especially by using high surface area fumed silicas at an high filler loading, while glass filled microcomposites showed the traditional rheological behaviour of microparticles filled polymeric systems, with marginal enhancements of rheological properties. Elaboration of new rheological models allowed us to find important correlations between fitting parameters and microstructural situation of the samples. Viscoelastic behaviour in the solid state was analyzed through quasi-static tensile tests, creep tests and dynamic tensile tests. Elastic moduli of the prepared composites resulted to be strictly related to the surface area of the filler rather than by its dimensions. Even in this case a new model, taking into account the physical interfacial interaction between the matrix and particles, proposed to explain experimental results. The same conclusions could be drawn for the creep behaviour, with important improvements of the creep stability of the material due to the introduction of fumed silica nanoparticles, especially at high filler amounts. Moreover, the limit of the linear viscoelastic region was extended by adding fumed silica nanoparticles. Furthermore, a non linear tensile creep approach was successfully applied to study the dependence of the creep behaviour from the free volume of the samples. The application of the classic time-temperature superposition principle was successfully adopted to the nanocomposite samples, evidencing that the reinforcing effect provided by the nanoparticles was more effective at high temperatures or longer times. Burgers model was adopted to model temperature dependent creep data, revealing interesting correlations between fitting parameters and nanofiller surface area. For as concern tensile dynamic mechanical properties, the introduction of the nanofiller lead to an increase of dynamic moduli (E’ and E’’) and to a lowering of tanδ values, especially when high surface area nanoparticles and elevated filler amounts were used. Even in this case dynamic properties of the material were mainly ruled by the surface area of the filler. The last part of the work was centered on the analysis of the fracture behaviour. Tensile properties at yield and at break increased with the surface area of the nanofiller and were positively affected by the presence of the organosilane on the surface of the nanoparticles. Tensile impact tests confirmed the enhancement of the fracture toughness provided by the nanoparticles. The application of the Essential Work of Fracture (EWF) approach led to the conclusion that the introduction of fumed silica nanoparticles produced a considerable improvement of the essential work of fracture (we) with the nanofiller surface area.

This thesis considers a nanotechnology approach based on the production of metals pre-treatments and organic coatings (a complete protection system at all) designed from the nanoscale. The final aim is to develop protection systems with improved corrosion protection properties and a low environmental impact. In particular, multifunctional silane hybrid molecules were used to design sol-gel pre-treatments for metals and to modify the inner structure of UV curable waterborne organic coatings. In the first part of this thesis thin (hundreds of nanometers) sol-gel films consisting of an experimental mixture of hybrid silicon alkoxides molecules were applied onto aluminium and hot dip galvanized (HDG) steel for the development of effective and environmentally friendly corrosion protection systems A chemical and electrochemical characterization of the sol-gel films highlighted their good corrosion protection properties both for aluminium and HDG steel. To test the effectiveness of the sol-gel coatings as coupling agent between metallic substrates and organic coatings (paints) both a powder coating paint and a cataphoretic coating paint were applied on the silane pre-treated substrates. The electrochemical measurements and the accelerated tests carried out on these protection systems proved the capability of these sol-gel conversion coatings to improve the corrosion protection properties of the traditional protective cycles. The performance of the silane pre-treatments was also compared to commonly used surface conversion coatings for metals. The result of this comparison evidenced that the corrosion protection properties ensured by the sol-gel conversion treatment is comparable or higher than most of the commonly used pretreatments. A study about the incorporation of inorganic nanoparticles into these sol-gel films gave evidences of an improved corrosion resistance due to the addition of certain amount of montmorillonite nanoparticles in the sol-gel matrix. The same hybrid silicon alkoxide molecules used to perform the pre-treatments were used modify the inner structure of UV curable waterborne coatings in order to improve the corrosion protection properties maintaining the environmental compatibility of the protecting system. The design, application and characterisation of urethane, acrylic and epoxy waterborne UV curing coatings modified with the hybrid silicon molecules in order to obtain nanostructured waterborne films with improved corrosion resistance and thermomechanical properties were studied. The characterization proved the great potential of the silicon alkoxide molecules as a tool to modify the properties of the organic matrix of the paint: silicon alkoxides can promote the self assembly of inorganic nanoparticles into the matrix or can act as an effective coupling agent between inorganic nanoparticles and the polymeric matrix. Silicon alkoxide molecules were proved to be an efficient tool to design a protection system from the nanoscale leading to the prospective of an accurate control of the overall properties of the macroscopic systems.

Aluminium alloys are characterized by a low specific weight, which make them highly interesting for structural applications. Mechanical properties are lower than those of steels, so the possibility to obtain an increase by means of the structural refining (either nano- or ultra-fine grained structure) would extend their applications in several fields. Bulk nanocrystalline metals and alloys can be produced by high energy milling of powders and their consolidation by sintering techniques characterized by a low thermal load in order to minimize grain growth. This is an alternative approach to other methods based on severe plastic deformation, with the advantage of obtaining near-net shape parts, within the limits of the Powder Metallurgy (PM) route. Even in the case of the part cannot be obtained directly a preform can be produced by Powder Metallurgy and finished by hot working. In this case, Powder Metallurgy is used to produce preforms with geometry closer to the final one than that attainable by other technologies, reducing production costs and raw material consumption. It is well known that nanostructure (D < 100 nm) of Al alloys can be obtained by high energy milling technique. During milling, the grain size is determined by equilibrium between recovery and formation of defects due to heavy plastic deformation. Face centered cubic (FCC) materials, as Al and alloys, are difficult to reduce by mechanical milling. The opposite occurs with body centred cubic (BCC) and hexagonal close packet (HCP) metals due to relatively defects accumulation and difficult of fast recovery kinetics. A valid alternative is the cryogenic milling, where the powders are milled in slurry formed with liquid nitrogen. Cryomilling takes advantage due to low temperature of the liquid nitrogen that either suppresses or limits recovery and recrystallization and leads to finer grain structure faster. In addition cryogenic milling does not require use of process control agent (PCA) that can contaminate the powder with carbon and oxygen. A very important factor to preserve the nanostructure of a material is its thermal stability that depends on the balance between driving and resisting forces. It is well known that the smaller the grain size, the bigger the tendency to grain growth. In most cases, the thermal stability of a nanostructure depends on the lattice defects stored between and within grains, and on the particles such as nitrides and oxides precipitated at the grain boundaries. It is really important achieve an equilibrium between grain size and thermal stability of the material to avoid grain growth on sintering. Moreover, if the powder particles are very fine, sintering becomes hard because of the oxide layer that surrounds the particles. Bulk nanomaterials can be produced through several PM techniques. Hot isostatic press (HIP), dynamic consolidation, hot extrusion and spark plasma sintering (SPS) are effective to achieve a full dense material. In the frame of the near-net shape technologies, SPS is a novel technology that has large potentiality, because of the lower temperature and shorter time required. In this process a pulse electric current flows directly on the powders and a high heating efficiency is offered. It is known that Al powders are hardly sinterable due to oxide layer on their surface. This layer has to be broken in order to form a solid neck between the particles. SPS has been used to produce nanostructured Al and iron alloys starting from nanostructured powders. A bimodal microstructure can be formed during SPS sintering due to the localized overheating generated by the sparks and low thermal stability of the material. It is well known that a bimodal microstructure reveals an improvement of ductility which is the most critical characteristics of nanostructured metals. In a simplistic view, ultra-fine/nano crystallites are responsible for high strength and micrometric grains provide increased ductility. Additional strategies of ductility improvement provides deformation at low temperatures/high strain rates, which furnishes accumulation of dislocations within nanocrystalline/UFG, resulting in increased strain hardening and enhancement of strain rate sensitivity of the flow stress. Hot workability of metals depends on several parameters. Temperature and strain rate affect the flow stress and the strain rate sensitivity. The former increases on decreasing grain size, until the deformation process is determined by dislocation motion. In FCC materials, particularly in Al and its alloys, refining grains to UFG level promotes an increase in strain rate sensitivity. The hot workability is usually defined as the quantity of deformation that a material can undergo without cracking and reaching desirable deformed microstructures at a given temperature and strain rate. Improving workability means increasing the processing ability and the properties of the materials. Hot workability can be studied by the approach of the power dissipation maps. In this PhD work, the production of nanometric Al 2024 alloy powder by cryomilling, ultra-fine grained/micrometric material consolidated by SPS, and its further deformability at high temperature was studied. The results are presented in three chapters. Chapter 1 reports the methodology to obtain the nanostructured 2024 alloy powder. Many aspects such as the evolution of the microstructure, the role of liquid nitrogen during milling and the thermal stability are studied in order to have an insight on the kinetics (1). The study of the thermal stability of the nanostructured powder is presented, as well. Chapter 2 describes the SPS experiments of the as-atomized and as-milled powders and the characterization of the consolidated material. Chapter 3 reports the hot compression experiments on the atomized and milled samples, and discusses the differences in the deformation behaviour on the basis of the starting microstructure and of its evolution during deformation.

State-of-the-art friction materials for applications in disc brake systems are constituted by composite materials, specifically formulated to ensure proper friction and wear performances, under the sliding contact conditions of braking events. The bases of typical friction compound formulations usually include 10 to 30 different components bonded with a polymeric binder cross-linked in situ. Main requests to be fulfilled during braking are an adequate friction efficiency and enough mechanical resistance to withstand the torque generated by forces acting on the disc brake. Generally, each component confers distinctive properties to the mixture and their primary function can be classified in the following categories: binders confer mechanical strength to friction material guaranteeing pad compactness during use, abrasives increase friction efficiency and improve compound wear resistance, solid lubricants are responsible for stabilizing friction coefficient and contrasting the build-up effect, reinforcements increase mechanical strength improving wear minimization and stabilization. Furthermore, other modifying components such as fillers and functionalizers are involved which are not directly related to friction efficiency, e.g. cheap materials, pigments, etc. Organic brake pads for disc-brake applications are based on phenolic resin binders, generally it requires three main manufacturing steps: raw material blending, where friction compound components are mixed by blenders. Hot-molding, where blended friction mix is pressed against a metallic support at controlled high pressure (>2kN/cm2), temperature (150-200 °C) and pressing time (3-10 minutes). Brake pads post-curing, to complete the hardening of polymeric binder. This last step for phenolic resin is usually performed in a batch convective oven at temperature above 150 °C for 4-12 h, or alternatively using a continuous process, such as IR in-line tunnel ovens where the process time is 10-15 min, the oven heater temperature is between 500 and 700 °C and brake pad superficial temperature is easily above 300 °C. Such kind of formulations and manufacturing process reflects the generally acknowledged state of the art as regards organic friction materials for passenger cars and light trucks. In this panorama the idea of introducing a completely inorganic binder matrix would represent nowadays an extremely appealing topic in the field considering potential improvements of this alternative approach. The complete elimination of the organic binder would reduce emission of phenol-formaldehyde hazardous derivatives generated at high-temperature e.g. volatile organic compounds, highly toxic polyaromatic hydrocarbons etc… Nature and toxicity of the organic compounds released at high temperature was investigated on brake pads manufacturing and compared with preliminary studies recently published. Introducing an inorganic hydraulically bonded matrix in place of the traditional organic-based binders would lead to a substantial reduction of the total embodied energy and water of brake pads considering low-temperature manufacturing process and inorganic binders properties. Primary production embodied energy for phenolic resin is estimated in the range of 75 - 83 MJ/kg (cradle to gate), while primary production water usage (embodied water) is in the range of 94 - 282 l/kg. As a matter of comparison, examples of the embodied energy for inorganic binders typically used for concrete construction are: Portland cements 4.9 MJ/kg, fly ash 9.3 MJ/kg, metakaolin 1.4 MJ/kg, silica fume 0.036 1.4 MJ/kg. The embodied water for these raw materials usually is less than 0.048 l/kg. Well-known properties of such peculiar inorganic materials exploiting the hydraulic activity of binders when exposed to water or alkaline environment. The only energy demanding compound was the alkaline solution (e.g. for sodium hydroxide and sodium silicate the embodied energy is respectively of 22MJ/kg and 16 MJ/kg). New brake pad manufacturing process allowed the substitution of commonly implied highly energy-consuming procedures with low-temperatures steps. Friction material components except binders were blended together with conventional plow-blade blender forming a dry friction-mix, then this dry friction-mix is blended with the inorganic binder and water or alkaline activators in a planetary mixer forming a wet friction-mix. Eventually wet friction mix is cold-pressed onto a metal back-plate without the need for further treatments at high temperature. It immediately emerges the energetic benefit connected to the manufacturing process of this inorganic binder-based brake pads. After brake pad production, the behavior of these inorganic materials was compared to traditional phenolic-based friction materials. Brake pads were tested on a full scale automotive brake dynamometer and on a real vehicle (in terms of performance and particle emission) following custom and international standard procedures. The aim of this work was to produce brake pad prototypes with friction material based on an inorganic hydraulic binder at performance comparable to commercial brake pads with organic-matrix based friction materials. The results obtained so far resulted particularly promising and paved the way to further developments of these novel class of friction materials.

Solid Oxide Fuel Cell (SOFC) is an upcoming technology seen with great expectations for the production of electrical energy with good efficiency and minimal environmental impact. Successful commercialization of SOFCs has however been hindered despite the optimistic promises made by some developers. This slackened commercialization of SOFCs technology is mainly due to the high cost associated with SOFC production and its limited long term stability. The long term stability of conventional Anode Supported-Solid Oxide Fuel Cell (AS-SOFC) with Ni based anode is tested by its limited tolerance towards redox cycling and rapid thermal cycling. The introduction of new generation SOFC, the so called Metal Supported- Solid Oxide Fuel Cell (MS-SOFC) has shown to overcome the drawbacks associated with the conventional AS-SOFC. Thus, MS-SOFC is looked upon as the potential candidate for the rapid commercialization of SOFC technology. In MS-SOFC design, the cell is supported on a porous metal substrate instead of expensive and non-reliable anode as in AS-SOFC. In this design the thickness of the functional layers (anode, cathode and electrolyte) is kept thin as possible (in the order of 10-50m) just necessary for electrochemical activities while the support being provided by the metal substrate. Although MS-SOFC can be fabricated by different routes, co-sintering of metal/anode/electrolyte multilayers in non-oxidizing atmosphere at high temperatures (1300 to 1400oC) is the most promising as far cost efficiency and industrial scale up is concerned. The cathode is usually applied after high temperature processes and sintered in situ during operation in this route. This fabrication approach however has some drawbacks associated with it. This work is basically on the development of materials and optimization of the multilayer design for the production of MS-SOFC by cost-effective co-sintering approach. YSZ (Y2O3 stabilized ZrO2), Ni-YSZ cermet, and ferritic stainless steel are considered for the electrolyte, anode and the support respectively. The anode and electrolyte were modified with the help of suitable dopants and the multilayer design was also altered in order to facilitate the co-sintering, preventing or reducing the generally encountered issues in this fabrication route. Coarsening of Ni in Ni-YSZ anode cermet and over-sintering of anode during high temperature co-sintering is a well-known issue. Ni coarsening reduces the number of triple phase boundaries (TPB) thereby affecting electrochemical performance. The electrical conductivity of the anode also degrades due to Ni coarsening. In current work, the effect of Al doping on Ni-YSZ anode sintering in Metal Supported-Solid Oxide Fuel Cell (MS-SOFC) was studied. It was found that, the addition of Al into the anode accounts for a finer microstructure if compared to undoped Ni-YSZ anode material. The electrical conductivity of the Al-doped anode was also found to increase considerabely and such result may be attributed to the fine microstructure caused by the segragation of Al2O3 formed during the course of sintering on the grain boundaries of both Ni and YSZ, thus inhibiting the sintering. 5wt% Al-doped NiO used for Ni-YSZ anode material gave the finest microstucture and the highest electrical conductivity at room temperature although it showed the lowest bulk density. Overall, Al-doped Ni-YSZ anode material was found to be a suitable material for the anode in MS-SOFC produced by co-sintering. The modification of the reduction kinetic of NiO and the interaction between the anode and steel during the fabrication of Metal Supported Solid Oxide Fuel Cells (MS-SOFC) is also studied in the present work. With the aim to limit NiO reduction under inert atmosphere at high temperature, doping elements such as Al and Ce were considered for NiO powders modification and anode production. In order to simulate the reactions at the metal/anode interface, NiO/YSZ/steel composites were prepared with pure and Al-doped NiO. A sudden volume expansion above 10000C followed by substantial shrinkage above 12000C was observed for the composites when sintered in Ar at 14000C. Such volume expansion can be related to the oxidation of steel due to the RedOx reaction between NiO and steel. Moreover, it was found that the volume expansion, i.e. the steel oxidation, can be minimized to a good extent when Al-doped NiO is used. Hence it is proposed that Al-doped NiO is a promising candidate material to be used for anodes in high temperature sintering of MS-SOFC. Other problems encountered during co-sintering of multilayers for MS-SOFC include delamination, cracking, bending, and interdiffusion of Fe,Cr and Ni between anode and the substrate. In another section of work, green multilayers were produced by tape-casting for the fabrication of MS-SOFC half-cell by co-sintering. The binder loss step during co-sintering was optimized so as to prevent the cracking of the multilayers due to the binder loss events. Intermediate layers (layer between metal support and rest of the layers) composed of metal-ceramic powder composite were also investigated to prevent delamination and to inhibit interdiffusion of the elements.CeO2-steel, YSZ-steel, and LDC(La doped Ceria)-steel powder composites were considered for investigation to use as intermediate layer. Out of the different multilayer design considered for investigation, YSZ/(Al-NiO)-YSZ/LDC-steel/steel multilayer design was found to be a good compromise so as to give a half-cell, with good bonding between the layers, which is camber free, and with moderate interdiffusion of elements between the substrate and the anode. It was however found in all the designs that complete densification of YSZ electrolyte could not be obtained. In order to address the issue of limited densification of YSZ electrolyte during co-sintering, Fe was considered for doping YSZ. A comparative study was done on Fe doped YSZ samples for sintering in air and argon atmosphere, with the aim to analyze the effect of Fe as sintering aid under MS-SOFC fabrication by co-sintering conditions. Samples showed enhanced densification with increasing Fe concentration in both the sintering atmospheres thus concluding that Fe can be used as a sintering aid for YSZ even in argon. The samples sintered in argon atmosphere were however characterized by larger lattice parameter, density and grain size. The increase in lattice parameter can be attributed to the oxygen vacancies generated under low p(O2) in argon atmosphere. The microstructural analysis of the samples showed the presence of small amount of secondary phase, and the concentration of such phase was seen to be higher in the argon sintered samples. Comparison of colors of argon and air sintered samples indicates the reduction and/or precipitation of Fe dopant in samples sintered in argon. Gas tight dense electrolyte could be obtained for MS-SOFC fabricated by co-sintering when Fe doped YSZ is employed for electrolyte, although the performance of the cell was quite poor.