Comportement tribologique de polymères thermoplastiques chargés de lubrifiants solides

Généralement les polymères thermoplastiques ne présentent pas des propriétés tribologiques très intéressantes. Afin de les améliorer il a été procédé à l'incorporation de lubrifiants solides, Graphite et MoS2 afin d'améliorer ces propriétés. Une évaluation tribologique de ces polymères chargés est présentée. Celle-ci a été effectuée sur un micro tribomètre alternatif en configuration bille plan et ce pour divers taux de chargement

Contribution à l'étude du comportement tribologique et des propriétés mécaniques de polymères thermoplastiques chargés de lubrifiants solides en poudre

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.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

Contribution to study of tribological behavior and mechanical properties of thermoplastic polymers field with solid lubricants in powder

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

Modification des propriétés tribologiques du PC via l'incorporation des particules de MoS2

International audienceModification des propriétés tribologiques du PC via l'incorporation des particules de MoS

Improvement in the tribological performance of polycarbonate via the incorporation of molybdenum disulfide particles

International audienceThe present study undertakes the assessment of the effect of the incorporation of molybdenum disulfide (MoS2) flakes on the tribological behavior of polycarbonate (PC) matrix. Five weight ratios of the MoS2 particles in the PC matrix were considered in the range of 0–10 wt%. The composites were developed by direct injection molding. The determination of various tribological parameters after wear testing (friction coefficient, wear volume loss, and profilometric traces) and microscopical observations by scanning electron microscopy (SEM) were combined in an attempt to understand the effect of the solid lubricant in the composites’ tribological performance. It was found that the tribological properties were improved by the addition of MoS2 particles. Maximum reductions in the friction coefficient and wear were obtained with an MoS2 mass content of about 7 to 10 wt%. It seems that MoS2 decreases the polymer surface melting by dissipating the generated heat. Under sliding conditions, the incorporation of MoS2 particles enhances the abrasive component in the wear mechanism, which is manifested by the formation of scratches in the two bodies in contact

Microstructure, friction and wear analysis of PMMA based composites with solid lubricant

International audienceMicrostructure, friction and wear analysis of PMMA based composites with solid lubrican

Mechanical and tribological response of ABS polymer matrix filled with graphite powder

International audienceThermoplastic-based polymer composites containing solid lubricant filler have been developed using a hot compression molding technique. The thermoplastic polymer is Acrylonitrile Butadiene Styrene (ABS) which is of great importance in applications such as bearing and slider material. The solid lubricant employed is graphite powder. Four mass ratios of the graphite particles in the ABS matrix were considered in the range of 0–7.5%. The mechanical properties of ABS composites were investigated using tensile test. The results show that the mechanical properties decrease significantly with the increase of graphite particles amount. Friction experiments were also conducted using a reciprocating tribometer recentlydeveloped in our laboratory. For each of the considered mass ratio, evolutions of the friction coefficient, the weight losses and the wear scar micrograph with respect to the number of sliding cycles were analyzed. Severe adhesive wear mechanism is activated for the ABS without graphite particles. Addition of graphite in ABS matrix exhibits lower friction coefficient and weight losses, whose values decrease asthe weight fraction of graphite increases in the polymer matrix. Based on scanning electron microscopy (SEM) observations, the worn surface of the filled ABS composites reveals the development of a specific third body which reduces friction and wear. The best friction coefficient and weight loss were obtained with 7.5% in weight (7.5 wt%) of graphite

Microstructure, friction and wear analysis of thermoplastic based composites with solid lubricant

Thermoplastic based composites containing different weight fractions of molybdenum disulfide (MoS2) solid lubricant were developed by injection molding. Polymethyl methacrylate (PMMA) and polycarbonate (PC) were chosen for the thermoplastic matrices. In order to characterize the interfacial adhesion between the matrices and the filler, we observed the fracture morphologies of selected composites. Micrographs of the fractured surfaces showed removal of MoS2 particles by microcraking as well as the presence of voids in the case of PMMA/MoS2 composites. These observations were confirmed by complementary images obtained using the X-ray tomography. The addition of an appropriate coupling agent may improve the adhesion between the MoS2 particles and the polymer matrix. Tribological behavior of the composites was also investigated using a ball-on-flat microtribometer with a high chromium steel ball antagonist. It was found that the addition of MoS2 particles didn’t improve the tribological performance of the composite in the case of PMMA matrix unlike the case of PC matrix where the friction coefficient was considerably reduced

On the Structural, Thermal, Micromechanical and Tribological Characterizations of Cu-Filled Acrylonitrile Butadiene Styrene Micro-Composites

The purpose of this work was to investigate the structural, thermal, micromechanical and tribological properties of novel polymer/metal composite materials for bearing applications. Copper (Cu)-filled Acrylonitrile Butadiene Styrene (ABS) composites were mixed in a laboratory scale by an internal mixer with two blade impellers, and then injection-molded. Neat ABS, ABS+5wt% Cu, ABS+10wt% Cu, and ABS+15wt% Cu were the four materials that were tested. The dispersion of Cu particles in the ABS matrix was investigated using Scanning Electron Microscopy (SEM) and a micro-tomography scan. The filler particles have a uniform distribution in the matrix, according to the observations. The incorporation of Cu filler also refined an increase in the glass transition temperature from Differential Scanning Calorimetry (DSC) and less intensity in the amorphous phase by X-ray diffraction (XRD). Nanoindentation tests were carried out to characterize the micro-mechanical behavior of the composites. Friction and wear analysis were also examined using a pin-on-disk tribometer. Compared with neat ABS, all the micro-composites showed much higher indentation hardness, Vickers hardness, and indentation elastic modulus. It was also concluded that the incorporation of Cu filler into ABS simultaneously improved the friction and wear properties of the composites, which contributed to the suitability of the micro-filled composites with hard metallic particles for a wider range of mechanical components for bearing applications.publishe