Os implantes cone morse apresentam um travamento e vedamento por meio de atrito entre as paredes do implante e do pilar protético. Nos sistemas convencionais do tipo Hexágono externo e interno, para reduzir o afrouxamento dos parafusos protéticos, são utilizados materiais de cobertura de superfície, como carbono e ouro. Não foram encontradas referências na literatura da utilização desse tipo de deposição em componentes do sistema cone morse. O propósito desse estudo é mensurar, registrar e avaliar os valores do torque de desaperto em pilares protéticos dos tipos sólido e parafuso passante do sistema cone morse com a deposição de carbono na zona de atrito do pilar protético. Foram utilizados 40 implantes cone morse com seus respectivos pilares divididos em 4 grupos (n=10): G1- pilar sólido; G2- pilar sólido com deposição de carbono na zona de atrito do sistema morse; G3- estudo somente do parafuso do pilar passante; G4- estudo somente do parafuso do pilar passante com deposição de carbono na ponta ativa; G5- estudo somente do pilar passante sem ação do parafuso; G6- estudo somente do pilar passante revestido em carbono na zona de atrito do sistema morse sem ação do parafuso. Cada pilar recebeu uma seqüência de 5 apertos e desapertos (20Ncm para o pilar sólido e 10Ncm para o parafuso passante). Os resultados mostraram no teste estatístico ANOVA para dois fatores de variação (desaperto e carbono), haver diferença estatística significante entre os grupos: G1 maior que G2 (p < 0,01); G4 maior que G3 (p < 0,01); G6 maior que G5 (p < 0,01). Esse estudo concluiu que o grupo controle G1 mostrou maior valor através da media aritmética (23,706 Ncm) em relação ao grupo experimental G2 (22,114 Ncm); o grupo experimental G4 mostrou maior valor através da media aritmética (8,218 Ncm) em relação ao grupo controle G3 (7,354 Ncm) e o grupo experimental G6 mostrou maior valor através da media aritmética (10,268 Ncm) em relação ao grupo controle G5 (6,906 Ncm), mostrou também que não houve diferença significativa (p > 0,01) para o fator desaperto em todos os grupos estudados, ou seja, não houve interferência da deformação do material com a repetição dos ciclos de aperto e desaperto. / The morse taper implants present a locking and sealing by means of the attrition between implants internal walls and the abutment. In the external and internal conventional hexagon system, to reduce the prosthetic screw loosing, its used covering surface materials, as carbon and gold. Literature reference using these kind of surface deposition were not found in morse taper abutment implants. The aim of this study is to measure, register and evaluate the removal torque values in morse taper solid abutment and passing screw abutment with carbon deposition in attrition zone. They were used 40 morse taper implants with their respective abutments divided in 4 groups (n = 10): G1 solid abutment; G2 - solid abutment with carbon deposition in attrition zone; G3 evaluation only in the screw of the passing abutment; G4 - evaluation only in the screw of the passing abutment with carbon deposition in the screw thread; G5 - evaluation only in the passing abutment without the screw action; G6 - evaluation only in the passing abutment with carbon deposition in attrition zone without the screw action. Each abutment received a sequence of 5 tightening and removal torque (20Ncm in solid abutment and 10Ncm in passant screw abutment). The results of ANOVA statistic test for two factors of variation (removal torque and carbon), showed that there is significant statistic difference between the groups: G1 higher than G2 (p < 0.01); G4 higher than G3 (p < 0.01); G6 higher than G5 (p < 0.01). This study concluded that control group G1 showed a higher value through the arithmetical media (23.706Ncm) in relation of the experimental group G2 (22.114Ncm); the experimental group G4 showed higher value through the arithmetical media (8.218Ncm) in relation of the control group G3 (7.354Ncm) and the experimental group G6 showed higher values through the arithmetical media (10.268Ncm) in relation of the control group G5 (6.906Ncm), and also showed that there was not significant difference (p < 0.01) to the removal torque factor in all the groups studied, that is, there was not a material deformation interference with the tightening and removal torque cycles repetition.

Currently available solid lubricants only perform well under a limited range of environmental conditions. Unlike them, oxides are thermodynamically stable and relatively inert over a broad range of temperatures and environments. However, conventional oxides are brittle at normal temperatures; exhibiting significant plasticity only at high temperatures (>0.5Tmelting). This prevents oxides' use in tribological applications at low temperatures. If oxides can be made lubricious at low temperatures, they would be excellent solid lubricants for a wide range of conditions. Atomic layer deposition (ALD) is a growth technique capable of depositing highly uniform and conformal films in challenging applications that have buried surfaces and high-aspect-ratio features such as microelectromechanical (MEMS) devices where the need for robust solid lubricants is sometimes necessary. This dissertation investigates the surface and subsurface characteristics of ALD-grown ZnO/Al2O3 nanolaminates and ZrO2 monofilms before and after sliding at room temperature. Significant enhancement in friction and wear performance was observed for some films. HRSEM/FIB, HRTEM and ancillary techniques (i.e. SAED, EELS) were used to determine the mechanisms responsible for this enhancement. Contributory characteristics and energy dissipation modes were identified that promote low-temperature lubricity in both material systems.

The purpose of the project work was to build knowledge of the tribological behaviour of self-lubricating laser cladding, with and without external solid lubricant during conditions relevant for hot metal forming of aluminium. The materials used during the project were plates coated with a Ni-based self-lubricating clad and a reference sample of work tool steel. The self-lubricating laser clad was applied using a high power direct diode laser. The external solid lubricant used was a graphite dispersion. The external solid lubricant was applied on the samples using a spraying technique, leaving a dry layer of solid graphite on the plates. To test the tribological behaviour of the plates, linear reciprocating friction and wear tests were performed both under lubricated and dry conditions. During the dry tests, different surface roughness of the plates where investigated. The pins for the tribological test were made of AA7075. Parameters chosen for the tribological tests were based on conditions during hot forming of aluminium. After having taken images of the plates using scanning electron microscopy, and using a 3D optical profiler, the wear volume and material transfer was evaluated, and wear mechanism analysis was performed.   The tribological behaviour of polished Ni-based laser clad under dry conditions is comparable to that of the reference sample at its best performance. Using a mirror polished Ni-based laser clad under dry condition can be an option to not using external solid lubricant during hot forming of aluminium. Also, the surface roughness of the self-lubricating clad under dry conditions does not affect the coefficient of friction.

Pour répondre aux problématiques d’usure précoce des pièces mécaniques causée par des pressions et températures élevées d’utilisation, des nanolubrifiants constitués de nanocarbones fluorés, connus pour leurs faibles coefficients de frottement et haute stabilité thermique ont été synthétisés. Pour améliorer ces propriétés, des précurseurs nanocarbonés de dimensionnalités différentes, et des procédés de synthèse gaz-solide variés ont été employés. Ainsi, une structure fermée comme les nanofibres de carbone NFCs (1D, tubulaire), ouverte comme le mélange nanodisques / nanocônes de carbone NDCs (majoritairement 2D, discotique) et intermédiaire avec les noirs de carbone graphitisés NCGs (0D, sphérique) ont été fluorés, d’une part avec le fluor moléculaire gazeux et d’autre part avec le fluor atomique produit par décomposition thermique d’un agent solide. Les mécanismes de fluoration / défluoration ont été proposés à l’aide de différentes techniques de caractérisation complémentaires (RMN du solide, MEB, MET, AFM, DRX) pour l’ensemble des matrices étudiées. Des matériaux présentant un gain de stabilité thermique de plusieurs dizaines de degrés comparativement aux matériaux fluorés de la littérature ont été élaborés, et une nouvelle méthode de synthèse dite « fluoration flash » a été mise au point pour étendre encore cette tenue en température. Les bonnes propriétés tribologiques de ces matériaux ont également été démontrées, notamment à 160°C et ceci quel que soit le mode de fluoration. Par la suite, des vernis à base de résines siliconées et chargés en nanofibres de carbone fluorées ont été formulés. Le revêtement composite présente une stabilité thermique supérieure à 400°C comme démontré par l’étude de son mécanisme de dégradation en température, notamment par couplage ATG-FTIR. D’un point de vue tribologique, les coefficients de frottement mesurés à température ambiante et 160°C sont inférieurs à 0,1 et les tribofilms obtenus ont été caractérisés par analyse MEB et EDX. / To address some issues to premature wear caused by high pressures and temperatures used on aircraft parts, nanolubricants made of fluorinated nanocarbons were synthesized. They are known for their low friction coefficients and high thermal stability in air. To improve these properties, carbonaceous nanomaterial precursors with different dimensionalities, and various gaz-solid synthesis methods were investigated. Thus, a closed structure such as carbon nanofibres (1D, tubular), opened such as carbon nanodiscs/nanocones (2D in majority, discotic) and intermediate with graphitized carbon blacks(0D, spherical) were fluorinated, firstly with molecular fluorine gas, and secondly with atomic fluorine released by the thermal decomposition of a solid fluorinating agent. Mechanisms of fluorination/defluorination were proposed thanks to complementary characterization techniques (solid NMR, SEM, TEM, AFM, XRD) for all the studied compounds. Materials with a gain of thermal stability of several tens of degrees compared to fluorinated materials of the litterature were prepared, and a new synthesis way called “flash fluorination” has been developed to further expand the thermal stability in air. Good tribological properties of these materials have been also demonstrated, including high temperature (160°C) regardless of the fluorination method. Then, polysiloxane resins loaded with fluorinated carbon nanofibres were formulated. The composite coatings exhibit thermal stability above 400°C as demonstrated by the study of the degradation mechanism as a function of the temperature, in particular by coupling TGA-FTIR. From a tribological point of view, friction coefficients measured at room temperature and 160°C are below 0.1 and the tribofilms obtained were characterized by SEM and EDX analysis.

La dégradation des contacts tribologiques sous une sollicitation de fretting est un phénomène complexe lié à l’interaction entre deux corps sous une faible amplitude de débattement, ce qui limite la durée de vie des pièces de manière significative. La lubrification solide est de plus en plus utilisée dans les applications tribologiques pour réduire les frottements et protéger la surface du substrat contre l'usure par fretting. La performance du revêtement dépend de nombreux facteurs tels que les conditions de sollicitation, les propriétés du substrat, du contre-corps et du revêtement et l'adhérence entre le revêtement et le substrat. Les objectifs de cette thèse sont de discuter le frottement et le comportement en usure du revêtement sous différentes conditions et d'analyser l'effet des paramètres d’essai sur le coefficient de frottement et la durée de vie du revêtement, ce qui peut être effectivement utile pour l'évaluation de la qualité des revêtements. Les tests de fretting sont menés pour comprendre les relations entre le comportement tribologique d'un vernis à base de MoS2 et les conditions d’essai. Le revêtement est étudié pour différentes valeurs de force de contact, amplitude de déplacement, configuration de contact, position du revêtement, nature du substrat et épaisseur. L'effet de chaque facteur est évalué par l'analyse de variance. L'analyse de régression est utilisée pour prévoir la performance du revêtement. L'observation de l'évolution de la trace d’usure est réalisée pour expliquer l’importance des facteurs et les coefficients dans les équations de prédiction. En outre, l'analyse de fiabilité est utilisée pour décrire et prévoir le taux de survie du revêtement sous certaines conditions d’essai. Enfin, un modèle linéaire de durée de vie est évalué afin de prendre en compte l'amplitude de déplacement variable. / Fretting wear is considered as a complex wear phenomenon related to interaction between two sliding bodies under very low displacement amplitude, which limits the lifetime of elements significantly. Solid lubricant is more and more applied in tribological applications to reduce friction and protect the substrate surface from fretting wear. The performance of coating depends on many factors such as running conditions, properties of substrate, counterbody and coating, and adhesion between coating and substrate. The objectives of this thesis are to discuss the friction and wear behavior of the coating under different running conditions, and to analyze the effect of test parameters on the friction coefficient and lifetime of the coating, which can be effectively helpful for the evaluation of quality of the coating. Fretting experiments are carried out to understand the relationships between the tribological behavior of a MoS2 based varnish coating and running conditions. The coating is investigated under different contact forces, different displacement amplitudes, different contact configurations, different coating positions, different substrates and different thicknesses. The rank of effect of factors is evaluated by the analysis of variance. Regression analysis is used to predict the performance of coatings under certain running conditions. The observation of evolution of wear scar is applied to explain the rank of factor and coefficients in the prediction equations. Furthermore, the reliability analysis is used to describe and predict the survival rate of coatings under certain running conditions. Finally, a linear model for lifetime is assessed in order to take into account variable displacement amplitude.

Dans ce travail, nous avons examiné de près les propriétés tribologiques et mécaniques de composites thermoplastiques chargés de différentes fractions massiques de particules de lubrifiant solide. Pour la matrice thermoplastique, nous avons retenu le polyamide 6-6 et le polycarbonate alors que les lubrifiants solides envisagés sont le graphite et le bisulfure de molybdène. L’élaboration des composites a été établie à l’aide d’une première méthodologie de moulage par injection directe. Une deuxième méthodologie d’élaboration, qui fait intervenir une étape de prétraitement du lubrifiant solide avant injection afin d’améliorer l’adhésion à l’interface matrice/lubrifiant solide, a été également utilisée. Pour les différents composites élaborés, les comportements tribologiques ont été analysés par l’intermédiaire d’un microtribomètre de type pion/plan à mouvement linéaire alterné. L’impact de la méthodologie d’élaboration sur les propriétés d’adhésion à l’interface charge/matrice a été exploré. Les moyens expérimentaux utilisés reposent principalement sur les tests de traction uniaxiale couplés à des tests de micro-rayage et des caractérisations microstructurales complémentaires (fractographie, tomographie X). Les propriétés mécaniques et micromécaniques mesurées ont été corrélées aux observations microstructurales. / Through this work, we focused on the tribological and mechanical properties of thermoplastic composites containing different weight fractions of solid lubricant filler. For the thermoplastic matrixes, we choose polyamide 6-6 and polycarbonate and the solid lubricants considered were graphite and molybdenum disulfide. Composites were developed by direct injection molding process as a first methodology. A second one is also used based on particles pretreatment before injection molding in order to improve the adhesion in the filler/matrix interface. Friction experiments were conducted using a reciprocating microtribometer. The effect of the development methodology on the adhesion properties in the filler/matrix interface was explored. The experimental tools were principally based on uniaxial tensile tests coupled to scratch tests and complementary microstructural characterizations (fractography, X-ray tomography). The measured mechanical and micromechanical properties were correlated to the microstructural observations.

High hardness and good wear resistance have been revealed for the high-entropy alloy (HEA) system AlCoCrFeNiTi, confirming the potential for surface protection applications. Detailed studies to investigate the microstructure and phase formation have been carried out using different production routes. Powder metallurgical technologies allow for much higher flexibility in the customisation of materials compared to casting processes. Particularly, spark plasma sintering (SPS) enables the fast processing of the feedstock, the suppression of grain coarsening and the production of samples with a low porosity. Furthermore, solid lubricants can be incorporated for the improvement of wear resistance and the reduction of the coefficient of friction (COF). This study focuses on the production of AlCoCrFeNiTi composites comprising solid lubricants. Bulk materials with a MoS2 content of up to 15 wt % were produced. The wear resistance and COF were investigated in detail under sliding wear conditions in ball-on-disk tests at room temperature and elevated temperature. At least 10 wt % of MoS2 was required to improve the wear behaviour in both test conditions. Furthermore, the effects of the production route and the content of solid lubricant on microstructure formation and phase composition were investigated. Two major body-centred cubic (bcc) phases were detected in accordance with the feedstock. The formation of additional phases indicated the decomposition of MoS2.