Philippe Lours | Ecole des Mines d'Albi (original) (raw)
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Papers by Philippe Lours
Un marqueur fluorescent thermosensible a ete developpe pour application haute temperature (1173 K... more Un marqueur fluorescent thermosensible a ete developpe pour application haute temperature (1173 K-1423 K). Il offre la possibilite de determiner l'histoire thermique avec une meilleure resolution thermique que les peintures thermochromes conventionnelles, et pourrait etre facilement mis en oeuvre sous forme de revetement par des procedes sol-gel.
Industrial Ceramics, 1999
Mineral polymer cements are new synthetic refractory materials similar to natural tecto-alumino-s... more Mineral polymer cements are new synthetic refractory materials similar to natural tecto-alumino-silicates. They can be used as binder phase in refractory concretes. Such concretes present some attractive properties such as low shrinkage and low thermal expansion coefficient which make them good candidates for high temperature applications The aim of this study is to characterise a new refractory material made of a mineral polymer cement reinforced with cordierite aggregates for applications as ceramic moulds for titanium superplastic forming at 925 degrees C. In a first part, the structural transformations of the concrete during the first heating have been characterised. A set of optimal conditions has been determined taking into account the stabilisation heat treatment in order to decrease the binder shrinkage influence and to minimise crack formation. In a second part, the mechanical properties have been measured by three point bending tests and compressive tests from room tempera...
Les marqueurs photoluminescents sont une solution pour la mesure de temperature de surface et en ... more Les marqueurs photoluminescents sont une solution pour la mesure de temperature de surface et en profondeur de materiaux utilises dans de nombreux secteurs industriels. Ces marqueurs grâce a l’evolution permanente des proprietes d’emission de fluorescence avec la temperature et la duree d’exposition constituent un indicateur de l’histoire thermique de ces materiaux. Ces evolutions doivent etre caracterisees precisement pour construire les courbes d’etalonnage propres a chaque marqueur utilise.
Surface and Coatings Technology, 2021
Additive Manufacturing offers an innovative route for producing high-quality parts in various fie... more Additive Manufacturing offers an innovative route for producing high-quality parts in various fields. A bi-material system, consisting in a NiCrAlY bond coat deposited onto a Ni-based Alloy 625 substrate, was manufactured by laser powder bed fusion (LPBF). Test samples were prepared and included sol-gel ceramic ZrO2(Y2O3) top coats as well as a specific grain boundary serration (GBS) heat treatment for promoting high temperature resistance. These specimens were subjected to very severe thermal shock cycles between 950 °C and 300 °C, characterized by steep heating and air quenching rates in a state-of-the-art burner rig designed to render gas turbine conditions, and their integrity was compared. While LPBFed NiCrAlY coatings were relatively spared from degradations due to thermal shocks, ceramic top coats exhibited clear spallation. Poor bonding was particularly experienced by specimens subjected to the GBS heat treatment due to the unavoidable formation therein of surface oxides. Nu...
Tool steel modified AISI H11 was oxidized at 600degreesC in mixtures of dry air and water vapor (... more Tool steel modified AISI H11 was oxidized at 600degreesC in mixtures of dry air and water vapor (0 to 30.8 vol% H2O). Either ``time-controlled'' tests (90 hours exposure) or ``wcight-controlled'' tests (oxidation up to 1.5 mg.cm(-2)) were performed. Depending on the H2O-amount added to dry air, two d istinct o xidation k inetics a re o bserved. T he e xternal o xide s cale i s iron-rich (Fe,Cr)(2)O-3. Lattice parameters are determined from the Grazing Incidence XRD patterns. ``Time-controlled'' and ``weight-controlled'' tests show no significant variation of the lattice parameters ``a'' and ``c'' with increasing water vapor in the oxidizing media. The Vegard's law applied to the mean values (a) over bar = 5.036 +/- 0.003 Angstrom and (c) over bar= 13.73 +/- 0.05 Angstrom gives an average composition of 4.7 mol% Cr2O3 in (Fe,Cr)(2)O-3. Texture is characterized by performing Rocking Curves. It strongly depends on the oxidation time a...
The spallation during cooling or thermal cycling of alumina scales grown at high temperature on P... more The spallation during cooling or thermal cycling of alumina scales grown at high temperature on PM2000 alloy is directly observed and recorded using CCD cameras. This simple and direct method permits to determine easily and accurately the scale spallation kinetics. In addition, it provides many insights on the spallation mechanisms and processes and their evolution as well as on the effect of substrate microstructure on spallation.
Cyclic oxidation failure of Atmospheric Plasma Sprayed Thermal Barrier Coatings systems (APS TBCs... more Cyclic oxidation failure of Atmospheric Plasma Sprayed Thermal Barrier Coatings systems (APS TBCs), commonly used to insulate hot sections in gas turbines, usually results from the spallation of the ceramic top coat. Consequently, in order to predict such spalling phenomena, understanding the mechanisms for cracks initiation and propagation in thermal barrier coatings is of utmost concern for engine-makers. Failure of the TBC is strongly related to the thermal and mechanical properties of each component of the multi-materials system (substrate, bond coat and ceramic) but also to the response of the TBC as a whole. The purpose of the work is to assess the mechanical behaviour of thick TBC using experimental approach for TBC standard lamellar, porous and microcracked microstructure (classically obtained through APS coatings). The experimental characterisation of the mechanical behaviour of the ceramic top coat of the TBC is addressed on specifically designed and prepared free-standing...
CROMeP experience in superplastic forming tool materials is related. Heat resistant cast steels, ... more CROMeP experience in superplastic forming tool materials is related. Heat resistant cast steels, ceramic refractories and vitreous silica based ceramics are investigated in terms of their resistance to the specific mechanical and thermal constraints of the SPF process.
Surface and Coatings Technology
Un marqueur fluorescent thermosensible a ete developpe pour application haute temperature (1173 K... more Un marqueur fluorescent thermosensible a ete developpe pour application haute temperature (1173 K-1423 K). Il offre la possibilite de determiner l'histoire thermique avec une meilleure resolution thermique que les peintures thermochromes conventionnelles, et pourrait etre facilement mis en oeuvre sous forme de revetement par des procedes sol-gel.
Industrial Ceramics, 1999
Mineral polymer cements are new synthetic refractory materials similar to natural tecto-alumino-s... more Mineral polymer cements are new synthetic refractory materials similar to natural tecto-alumino-silicates. They can be used as binder phase in refractory concretes. Such concretes present some attractive properties such as low shrinkage and low thermal expansion coefficient which make them good candidates for high temperature applications The aim of this study is to characterise a new refractory material made of a mineral polymer cement reinforced with cordierite aggregates for applications as ceramic moulds for titanium superplastic forming at 925 degrees C. In a first part, the structural transformations of the concrete during the first heating have been characterised. A set of optimal conditions has been determined taking into account the stabilisation heat treatment in order to decrease the binder shrinkage influence and to minimise crack formation. In a second part, the mechanical properties have been measured by three point bending tests and compressive tests from room tempera...
Les marqueurs photoluminescents sont une solution pour la mesure de temperature de surface et en ... more Les marqueurs photoluminescents sont une solution pour la mesure de temperature de surface et en profondeur de materiaux utilises dans de nombreux secteurs industriels. Ces marqueurs grâce a l’evolution permanente des proprietes d’emission de fluorescence avec la temperature et la duree d’exposition constituent un indicateur de l’histoire thermique de ces materiaux. Ces evolutions doivent etre caracterisees precisement pour construire les courbes d’etalonnage propres a chaque marqueur utilise.
Surface and Coatings Technology, 2021
Additive Manufacturing offers an innovative route for producing high-quality parts in various fie... more Additive Manufacturing offers an innovative route for producing high-quality parts in various fields. A bi-material system, consisting in a NiCrAlY bond coat deposited onto a Ni-based Alloy 625 substrate, was manufactured by laser powder bed fusion (LPBF). Test samples were prepared and included sol-gel ceramic ZrO2(Y2O3) top coats as well as a specific grain boundary serration (GBS) heat treatment for promoting high temperature resistance. These specimens were subjected to very severe thermal shock cycles between 950 °C and 300 °C, characterized by steep heating and air quenching rates in a state-of-the-art burner rig designed to render gas turbine conditions, and their integrity was compared. While LPBFed NiCrAlY coatings were relatively spared from degradations due to thermal shocks, ceramic top coats exhibited clear spallation. Poor bonding was particularly experienced by specimens subjected to the GBS heat treatment due to the unavoidable formation therein of surface oxides. Nu...
Tool steel modified AISI H11 was oxidized at 600degreesC in mixtures of dry air and water vapor (... more Tool steel modified AISI H11 was oxidized at 600degreesC in mixtures of dry air and water vapor (0 to 30.8 vol% H2O). Either ``time-controlled'' tests (90 hours exposure) or ``wcight-controlled'' tests (oxidation up to 1.5 mg.cm(-2)) were performed. Depending on the H2O-amount added to dry air, two d istinct o xidation k inetics a re o bserved. T he e xternal o xide s cale i s iron-rich (Fe,Cr)(2)O-3. Lattice parameters are determined from the Grazing Incidence XRD patterns. ``Time-controlled'' and ``weight-controlled'' tests show no significant variation of the lattice parameters ``a'' and ``c'' with increasing water vapor in the oxidizing media. The Vegard's law applied to the mean values (a) over bar = 5.036 +/- 0.003 Angstrom and (c) over bar= 13.73 +/- 0.05 Angstrom gives an average composition of 4.7 mol% Cr2O3 in (Fe,Cr)(2)O-3. Texture is characterized by performing Rocking Curves. It strongly depends on the oxidation time a...
The spallation during cooling or thermal cycling of alumina scales grown at high temperature on P... more The spallation during cooling or thermal cycling of alumina scales grown at high temperature on PM2000 alloy is directly observed and recorded using CCD cameras. This simple and direct method permits to determine easily and accurately the scale spallation kinetics. In addition, it provides many insights on the spallation mechanisms and processes and their evolution as well as on the effect of substrate microstructure on spallation.
Cyclic oxidation failure of Atmospheric Plasma Sprayed Thermal Barrier Coatings systems (APS TBCs... more Cyclic oxidation failure of Atmospheric Plasma Sprayed Thermal Barrier Coatings systems (APS TBCs), commonly used to insulate hot sections in gas turbines, usually results from the spallation of the ceramic top coat. Consequently, in order to predict such spalling phenomena, understanding the mechanisms for cracks initiation and propagation in thermal barrier coatings is of utmost concern for engine-makers. Failure of the TBC is strongly related to the thermal and mechanical properties of each component of the multi-materials system (substrate, bond coat and ceramic) but also to the response of the TBC as a whole. The purpose of the work is to assess the mechanical behaviour of thick TBC using experimental approach for TBC standard lamellar, porous and microcracked microstructure (classically obtained through APS coatings). The experimental characterisation of the mechanical behaviour of the ceramic top coat of the TBC is addressed on specifically designed and prepared free-standing...
CROMeP experience in superplastic forming tool materials is related. Heat resistant cast steels, ... more CROMeP experience in superplastic forming tool materials is related. Heat resistant cast steels, ceramic refractories and vitreous silica based ceramics are investigated in terms of their resistance to the specific mechanical and thermal constraints of the SPF process.
Surface and Coatings Technology