Un nouveau procédé d’élaboration de CMC par voie liquide a été développé ; il met en œuvre l’utilisation de charges réactives afin d’obtenir un composite à bas coût. Afin de préserver le renfort en fibres Nicalon, ces charges doivent réagir sous azote à une température inférieure à 1100°C. Deux charges réactives répondant ces critères et présentant une prise de volume intéressante ont été identifiées : AlB2 et TiSi2.Le broyage planétaire de ces charges a été étudié afin d’évaluer l’influence de l’affinement de la microstructure sur les propriétés. Des poudres de surface spécifique élevée et de granulométrie proche l’échelle nanométrique ont été obtenues. La nitruration des charges a été analysée et un effet de taille a pu être mis en évidence sur la réactivité du TiSi2.Les poudres broyées ont été mises en suspension pour être imprégnées au sein de préformes. Les échantillons ont ensuite subi une étape de nitruration à 1100°C, cruciale pour la cohésion de la matrice. Un cycle PIP a ensuite été réalisé pour diminuer la porosité résiduelle.L’oxydation des matériaux obtenus a été étudiée dans des conditions correspondant à l’application aéronautique visée. Les propriétés mécaniques des composites élaborés ont été évaluées par des essais de flexion 3 points. La combinaison de l’utilisation de la charge réactive TiSi2 et d’un polysiloxane a permis d’obtenir un composite dont la contrainte à rupture est remarquable compte tenu du faible nombre d’étapes nécessaires à son élaboration par voie liquide. / A new CMC manufacturing process has been developped ; the active filler technique is used in order to obtain a low cost composite. Active fillers must react under nitrogen atmosphere at a temperature below 1100°C so that the Nicalon fiber reinforcement is not damaged. Two active fillers meeting these criteria and offering an interesting volume expansion have been identified : AlB2 et TiSi2.The planetary milling of these fillers has been explored in order to assess the influence of microstructure refinement on properties. Powders with high specific surface areas and of granulometry close to the nanometric scale were obtained. The nitridation of the active fillers was examined and a size effect on TiSi2 reactivity was displayed.Milled powders were used in colloidal suspensions in order to be impregnated in preforms. Samples were subsequently nitrided at 1100°C ; this step was crucial for matrix cohesion. A PIP cycle was eventually performed in order to reduce residual porosity.The oxydation behaviour of materials was studied in conditions corresponding to the considered aeronautics application. Mechanical properties of composites were estimated by 3 point bending tests. Combining the use of TiSi2 and of a polysiloxane enabled to obtain a composite whose maximum bending stress was remarkable considering the limited number of steps required for its processing.

Planetary ball milling (PBM) is a well-known technique for efficient size reduction and homogenization of materials that has been used for many decades in various engineering and industrial processes. More recently, it has emerged as a unique top-down nanofabrication approach for nanomaterials based on nanoscale grinding. However, its potential application in nanostructured thin film fabrication has not been fully explored, as only a limited number of studies have been carried out. In this work, the effects of different grinding parameters (speed, time and solvents) were used to create previously unstudied nanoscale grinding conditions for nanostructured thin film materials via PBM with distinct and novel properties: Nanoparticles of silicon, titanium disilicide (TiSi2) and zinc oxide (ZnO) ground in different solvents (deionized (DI) water/ ethylene glycol (EG)/isopropyl alcohol) resulted in colloidal suspensions (or nanoinks) that could be used to coat various substrates (wafers, glass, flexible substrates, etc.) via drop casting, doctor blading or dip coating. Thin film properties such as wettability, electrical conductivity and gas sensing behavior are studied. The fabricated thin film coating properties could be tuned depending on the combination of starting powder materials, grinding parameters and resulting nanoparticle size/geometry: The influence of surface chemistry, solvent type, particle geometry, surface roughness and defects was shown to alter the conductivity and surface wettability of the resultant films. Thus, thin films formed using PBM nanoinks allow varied and tunable properties for advanced multi-functional coatings and devices. To demonstrate the feasibility of PBM nanoinks for thin film device applications, ZnO nanoinks were used to create chemiresistive gas sensors that operate at room temperature. By varying grinding parameters (speed, time and solvent) thin film sensors with differing particle sizes and porosity were produced and tested with air/oxygen against hydrogen, argon and methane target gas species, in addition to relative humidity. Grinding speeds of up to 1000 rpm produced particle sizes and RMS thin film roughness below 100 nm, as measured by atomic force microscopy and scanning electron microscopy. Raman spectroscopy, photoluminescence and x-ray analysis confirmed the purity and structure of resulting films. The peak gas sensor response was found for grinding parameters of 400 rpm (average particle size 275 nm) and 30 minutes (average particle size 225 nm) in EG and DI water, respectively, which could be correlated to an increased film porosity and an enhanced electron concentration resulting from adsorption/desorption of oxygen ions on the surface of ZnO nanoparticles. Similarly, gas response and dynamic behavior were found to improve as the operating temperature was increased between 100 and 150 °C. These results demonstrate the use of low-cost PBM nanoinks to optimize the active materials for solution-processed thin film gas/humidity sensors that can operate at room temperature for use in environmental, medical, food packaging, laboratory, and industrial applications. Overall, the nanogrinding technique can produce large amounts of nanoparticle suspension with variable particle sizes for creating thin films with tunable properties. By adjusting grinding parameters, the nanoparticle shape/size and properties can be varied resulting in nanoparticle inks for inexpensive coatings on various substrates and for use in different applications. / Graduate