FLOOR COVERING AND DEVICE AND METHODS ASSOCIATED WITH IT

Description

Scope of the invention

[0001] The invention relates to a soil, in particular a test soil, and an associated manufacturing method. The invention also relates to a device, in particular a test device, and an associated method. State of the art

[0002] Soils, especially road soils, are used to design and test new materials and products intended for use on soils, for example for the manufacture of tire components.

[0003] Thus, during the design of a part of a tire, for example a material for a tire tread, the characterization of its behavior under stress, for example under engine or braking torque or under drift or under ground / tire slip differential, is important.

[0004] Tests on external tracks, for example on a braking track, are relatively expensive, time-consuming and hardly reflect long-term tire wear.

[0005] With this in mind, measures can be taken to reproduce in the laboratory, on a tribometer, the friction between the part of the tire, for example made of rubber, and the road surface, which is responsible for a large part of the effort generated in the contact area of ​​the tire with the road surface.

[0006] However, known soils do not allow for measurements in the laboratory that are representative of behavior on a road surface.

[0007] Indeed, it is observed that the coefficients of adhesion measured on laboratory test devices such as tribometers are significantly lower than those on road surfaces, typically by a factor of two.

[0008] US 8 800 358 B2 discloses a tire testing device. Summary of the invention

[0009] One object of the invention is to provide a soil that overcomes these drawbacks. Another object of the invention is to provide a soil for laboratory testing that can represent the characteristics of a road surface and is sufficiently robust for repeated use.

[0010] For this purpose, a floor according to claim 1 is provided.

[0011] It is thus possible to obtain a soil which has the desired characteristics, for example those of a road surface, and which can be tested repeatedly while retaining its friction characteristics despite such repeated use, which ensures the relevance of the tests carried out.

[0012] The invention also relates to a device for testing an element, comprising: such a soil, and means of applying the element to the soil and of setting the element and the soil in relative motion.

[0013] The invention is advantageously complemented by the following features, taken alone or in any of their technically possible combinations: The device is a rolling machine; the device is a tribometer.

[0014] The invention further relates to a method for manufacturing such soil according to claim 8.

[0015] The invention is advantageously complemented by the following features, taken alone or in any of their technically possible combinations: a step of generating a relief of the substrate, a step of generating a relief of the substrate by additive manufacturing, for example in ceramics, a step of generating the relief by machining, for example by laser machining, laser machining is a laser machining of a mass comprising tungsten carbide, laser machining is a laser machining of a mass comprising stainless steel, a step of generating the relief by laser surface melting from a stainless steel powder, the step of obtaining the substrate further includes a step of modulating the generated relief.

[0016] The invention further relates to a method of testing an element using such a device, comprising applying the element to the ground and / or setting the element in relative motion with respect to the ground. Brief description of the figures

[0017] Other features and advantages of the invention will become apparent from the following description of embodiments. See the attached drawings. THE figures 1a and 1b represent soils, the figure 1a representing an example that is not part of the claimed invention. figure 2 represents a manufacturing process according to an example of an embodiment of the invention, the figure 3 represents a device according to an example of an embodiment of the invention, and the figure 4 represents a test method according to an example of an embodiment of the invention, the figure 5a represents a reference soil according to an example of an embodiment of the invention, the figure 5b represents a relief of the reference ground treated according to an example of an embodiment of the invention, and the figure 5c represents the reference ground relief of the figure 5b converted according to an example of an embodiment of the invention, the figure 6represents friction coefficient measurements as a function of kinematic length according to an example embodiment of the invention. Detailed description of the invention Manufacturing process

[0018] With reference to the figure 2 , a process for manufacturing a soil is described, for example a soil such as is described below. Substrate generation

[0019] The process includes a step 21 for obtaining a substrate 110, for example, a substrate 110 as described below. The step for obtaining the substrate 110 may be a step for generating the substrate 110 or for supplying the substrate 110.

[0020] Step 21 may include a step 212 for determining a relief feature to be reproduced. Relief can be defined as a non-planar texture, for example, variations in elevation relative to a median plane. The relief to be reproduced may be macro-relief. Macro-relief can be defined in relation to micro-relief. Alternatively, or in addition, macro-relief can be defined as relief measurable with the precision of an average texture depth measurement, for example, as described below. Macro-relief may correspond to relief with a characteristic size on the order of a centimeter, for example, centimeter-sized.

[0021] This makes it possible to know the desired relief for the ground.

[0022] Step 212 may include a step 2121 for obtaining data relating to a relief to be reproduced, for example by means of data processing, for example by a data processing unit, for example by a processor. The data relating to a relief to be reproduced may thus be stored beforehand, for example by means of storage, for example by a storage unit, for example by memory. The data relating to a relief to be reproduced are thus available without the need to carry out any further measurements beforehand.

[0023] Alternatively or in addition, step 212 may include a step 2122 for obtaining a reference soil. Step 2122 for obtaining a reference soil may be a step for manufacturing a reference soil.

[0024] In reference to the figure 5aA reference soil is described. The reference soil may include aggregates. The aggregates may be crushed natural rock aggregates and / or aggregates of approximately 1 cm in size. Such a reference soil structure exhibits good resistance to polishing and high small-scale aggressiveness due to its relief, far exceeding the characteristics that natural rock might exhibit.

[0025] The reference soil can be a road core sample. The road can be a road surface, for example, an external road surface. The road surface can include concrete and / or bitumen and / or crushed natural rock. Step 2122 can therefore include a road core sample. The road core sample can include a sample of the road surface. The reference soil is, for example, a mosaic soil, meaning that it includes at least one area where the aggregates are arranged adjacent to each other; such a soil is particularly suitable for use with a tribometer.

[0026] The reference ground can thus provide a relief model that we wish to reproduce for the ground.

[0027] The reference ground may include a textured 510 ring. The 510 ring may include the relief to be reproduced. The 510 ring may be arranged and / or extend between a radius of 21 mm and a radius of 48 mm. Such dimensions may be adapted to the sizes of tribometer specimens for such applications. The tribometer may be a rotational kinematic tribometer or a linear tribometer.

[0028] Step 212 may include a step 2123 for measuring a reference ground relief, for example, the relief to be reproduced. This makes it possible to obtain an image of the reference ground surface. Step 2123 may be performed using a profilometer, for example, an optical profilometer, for example, by structured light projection and / or by interferometric measurement and / or by confocal measurement. The profilometer may include a sensor with a field size on the order of 10 x 10 cm, for example, a sensor with a resolution of 100 µm. The profilometer is, for example, a µsurf expert model profilometer such as those marketed by nanofocus. Thus, at the end of step 2123, a measured reference ground relief can be obtained, for example, in the form of data corresponding to the measurement of the reference ground relief.

[0029] Step 212 may include a step 2124 for processing the reference ground relief data measured in step 2123. Step 2124 may include recombination of the reference ground relief measured in step 2123. Step 2124 may include filtering the reference ground relief measured in step 2123, for example, low-pass filtering, for example, low-pass filtering with a cutoff wavelength of 300 µm, for example, sliding support spatial filtering, for example, sliding support spatial filtering with a support size of 300 µm. Step 2124 may include rectification of the reference ground relief measured in step 2123, for example, rotation of a relief plane, for example, of a mean plane, the mean plane being a mean plane of the relief peaks, for example, obtained by linear regression. Step 2124 can be implemented by means of data processing.Thus, at the end of step 2124, a processed reference ground relief is obtained, for example, in the form of data corresponding to the measurement of the reference ground relief carried out after data processing. The method may include the display and / or representation of the processed reference ground relief, for example, on a terminal. An example of a processed reference ground relief corresponding to a surface, obtained in step 2124, is illustrated by the figure. figure 5b .

[0030] For example, it is thus possible to obtain the profilometry that one seeks to reproduce for the soil.

[0031] Step 212 may include a step 2125 of converting the reference ground relief, for example measured in step 2123 and / or processed in step 2124, into a solid. Step 2125 may include transforming the reference ground relief from a two-dimensional representation to a three-dimensional representation, for example, transforming it into a three-dimensional file. Step 2125 may be implemented using data processing means. Thus, at the end of step 2125, a converted reference ground relief is obtained, for example, in the form of data corresponding to the measurement of the reference ground relief carried out, possibly after data processing and conversion. The method may include displaying and / or representing the converted reference ground relief, for example, on a terminal. An example of a reference ground relief converted to a solid, obtained in step 2125, is illustrated by the figure 5c .

[0032] Data thus obtained can form a set of instructions to be provided to a production and / or manufacturing device, for example a machining machine, for the production of the ground, in particular the substrate and / or relief.

[0033] Step 212 may include a step 2126 of recording the relief of the reference ground, for example measured in step 2123 and / or processed in step 2124 and / or converted into solid in step 2125. The recording may be carried out on the storage means, for example by means of the data processing means.

[0034] Step 212 may include a step 2127 for manufacturing a prototype based on the recording made in step 2126 and / or the data obtained in step 2121. Manufacturing may be carried out by 3D printing. The prototype may be made of resin. This allows for validation of the relief obtained via step 212.

[0035] Step 21 may include a step 213 for generating a relief of the substrate 110, for example, a first relief of the substrate, for example, macro-relief. The relief of the substrate may be generated according to the relief to be reproduced, determined in step 212, for example, recorded in step 2126.

[0036] The relief can be generated in step 213 by removing material, for example by an ablative technique.

[0037] The relief can be generated by machining.

[0038] Relief can be generated by laser, for example by laser machining. Relief can be created by laser machining, for example by continuous or pulsed laser machining, for example by nanosecond laser machining, for example with a beam diameter focused on the surface between 10 and 100 µm, for example between 25 and 35 µm, for example on the order of 30 µm. Relief can be created by laser machining of a part, in particular a solid piece.

[0039] The part can be a metallic part, in particular a metal mass, for example comprising steel, for example stainless steel, for example X4CrNiMoN21-9-4 stainless steel. The metal mass can be a steel mass, for example stainless steel, for example X4CrNiMoN21-9-4 stainless steel.

[0040] The part may include a carbide, for example tungsten carbide. The part may be a solid piece of carbide, for example tungsten carbide.

[0041] The part may have general dimensions of the order of those of the final part, and / or may be smooth, and / or may have a thickness greater than at least one order of magnitude greater than the intended texture depth, for example by about one order of magnitude.

[0042] This machining process allows for the creation of the surface profile through material removal. This technique is particularly advantageous for generating a surface representative of a new asphalt road surface, especially with regard to the wet rubber-soil adhesion coefficient.

[0043] The relief can be generated by machining by removing material with a cutting tool, the cutting tool having for example a cutting edge.

[0044] The relief can be generated in step 213 by additive manufacturing.

[0045] The relief can be generated by printing, for example, by 3D printing. The relief can be generated in ceramic. Such a step 213 may include one or more stages of ceramic powder deposition and / or firing. This technique can allow for the generation of the entire substrate.

[0046] The relief can be generated by laser surface melting ("Surface Laser Melting" in Anglo-Saxon terminology), for example from a powder, for example a steel powder, for example stainless steel, for example X4CrNiMoN21-9-4 stainless steel. Such a technique can allow the entire substrate to be generated.

[0047] The resulting relief can be the final relief of the soil substrate 110. Alternatively, the process can include a modification of the relief generated in step 213.

[0048] The process, for example step 21, may thus include a step 214 for modulating the generated relief, for example by modulating roughness, for example by modulating amplitude, for example by adjusting micro-relief or micro-roughness, of the relief generated in step 213, for example so as to obtain a second relief of the substrate. The process, for example step 21, may thus include a step 214 for attenuating the generated relief, for example by attenuating roughness, for example by reducing amplitude, for example by adjusting micro-relief or micro-roughness, of the relief generated in step 213. Alternatively or in addition, the process, for example step 21, may thus include a step 214 for amplifying the generated relief, for example by amplifying roughness, for example by increasing amplitude, for example by adjusting micro-relief or micro-roughness, of the relief generated in step 213.

[0049] In this case, the surface relief generated in step 213 is an initial surface relief modified in step 214 during the soil manufacturing process. Modulated roughness features include, for example, micro-reliefs and / or micro-roughness. Micro-relief can be defined, for instance, in relation to macro-relief, with macro-relief having a greater amplitude than micro-relief. Alternatively, or in addition, micro-relief can be defined as a surface relief with a size less than 100 µm. Alternatively or in addition, micro-relief can be defined as relief of a size less than the precision permitted by the relief generation technique implemented in step 213, for example by machining or ablation, in particular laser machining or ablation, for example measurable with the precision of an average texture depth measurement, for example as described below, but not controllable by the relief generation technique implemented in step 213.Micro-roughness refers, for example, to a surface feature whose wavelength is smaller than the smallest roughness described by the surface recorded in step 2127 and / or the surface data obtained in step 2121, and / or smaller than the accuracy allowed by the surface generation technique implemented in step 213, for example, by machining or ablation, particularly laser machining or ablation. This makes it possible to approximate the micro-reliefs measured on the soils to be reproduced in the laboratory, for example, road surfaces.

[0050] The modulation can be performed by laser. Step 214 can therefore include a first step 2141 of modulation by laser surface melting. This makes it possible to remelt the surface of the relief, for example, to modulate local roughness. Step 214 can include a second step 2142 of modulation by femtosecond pulsed laser, for example, subsequently or as an alternative to the first step 2141. Step 214, and preferably steps 2141 and / or 2142, is preferably carried out after a step 212 in which the relief is generated by additive manufacturing, in particular by 3D printing.

[0051] Thus, at the end of step 21, the relief of the substrate 110 is obtained. The relief of the substrate may define or correspond to the relief of a usable surface 120 as described below. The portion of the substrate 110 where the relief is located may form at least partially or entirely the usable surface 120. Alternatively, a treatment such as described below, for example, the formation of a surface coating, may be applied to the relief, for example, so as to form at least partially or entirely the usable surface 120. In this case, the usable surface is at least partially positioned above the relief of the substrate 110. Surface finishing

[0052] The process includes a surface treatment step 22. Step 22 includes a step 222 for obtaining, for example, forming, for example, depositioning, a surface coating 122 comprising titanium nitride and / or chromium nitride. The surface coating may also comprise amorphous carbon and / or tungsten carbide. The surface coating may be a surface coating as described below.

[0053] This makes it possible to increase surface hardness, particularly the hardness of a surface in use, for example as described below. This allows for high resistance to polishing.

[0054] Step 22 is preferably implemented when step 213 of relief generation has been carried out by laser surface melting and / or by nanosecond laser machining of a stainless steel block.

[0055] The process can be carried out so that the material chosen for the substrate guarantees a high level of hardness without surface coating, preferably when application means 312 as described below include a suitable motor to move relative the element 32. Validation

[0056] The process may include a step 23 for validating the soil obtained in steps 21 and / or 22. Validation may be carried out under dry and / or wet friction conditions. It may include measurement with a tribometer, in particular a linear tribometer, and / or with a rolling machine. Validation may also include comparing the measurement with a friction curve. Ground

[0057] With reference to figures 1a and 1b A soil is described. The soil is, for example, a test soil, for example, a test soil for an element, for example, a test soil for a tire and / or a part of a tire and / or rubber.

[0058] The soil comprises a substrate 110. Substrate 110 has a Young's modulus between 100 and 1000 GPa, preferably between 100 and 500 GPa. Such a Young's modulus far exceeds that of a rubber, which is at most 3 to 10 GPa, for example, in compression within the vitreous domain. Such a Young's modulus also exceeds that of aluminum. Thus, even during use, the rubber remains significantly more deformable than the substrate, which, by comparison, does not deform.

[0059] The floor comprises a usable surface area 120. This usable surface area is a surface coating as described below. The floor exhibits a Vickers hardness at this usable surface area 120, ranging from 1300 to 10000 kgf / mm², preferably between 1500 and 3500 kgf / mm². This usable surface area allows the floor to achieve significant hardness.

[0060] "kgf" ​​means kilogram-force, and 1 kgf = 9.80665 N.

[0061] This makes it possible to obtain a surface with the desired characteristics, such as those of a road surface, that can be repeatedly tested while retaining its friction characteristics despite such repeated use, thus ensuring the validity of the tests performed. Such a surface is particularly effective for testing adhesion characteristics, for example, on dry and / or wet surfaces.

[0062] The soil, for example, is obtained by the manufacturing process described above.

[0063] Furthermore, such a soil can also be effective for testing tire / soil stress characteristics, for example, using a test setup as described below, where known soils are either unable to provide a topography representative of a road surface or exhibit excessive wear requiring overly frequent soil changes. Unlike known soils, this method avoids both cost and reproducibility issues.

[0064] Indeed, the prior art soils used in laboratories do not reproduce the characteristics of a road surface and / or wear out prematurely, which greatly impairs the reproducibility of tests using prior art soils.

[0065] One of the mechanisms of tire grip on wet surfaces stems from the deformation of the rubber as it slides across the surface. Due to the viscoelasticity of the tire material, this deformation leads to energy dissipation, which translates directly into friction forces. Therefore, understanding and controlling surface roughness is critical to ensuring the reliability of laboratory friction measurements compared to full-tire grip measurements on a braking track.

[0066] Road surfaces are generally composed of bituminous binder and crushed rock aggregates whose petrographic nature and size vary from one surface to another. In terms of roughness, road surfaces are distinguished by their multi-scale nature (characteristic roughness size ranging from 1 cm to 1 µm or even less) and their quasi-fractal structure.

[0067] One of the challenges overcome by the soil described here, which improves the relevance of laboratory measurements, is ensuring that the surface roughness against which the tire rubs during a test accurately represents the characteristics of a road surface. In this regard, the term kinematic length can be defined as the cumulative length of the tire that slides over a point on the ground. In real-world contact between a tire's rubber and the road surface of a heavily used braking track, the kinematic length seen from a point on the ground during two years of use of the braking track is on the order of ten meters.Conversely, in the laboratory, the characterization of numerous operating points of the rubber (pressure, speed, temperature), combined with the fact that friction always occurs at the same location, leads to significantly greater kinematic lengths seen from a point on the ground, by several orders of magnitude (approximately 10 km per aggregate in one year of laboratory use). This results in a significantly faster manifestation of rock polishing / erosion phenomena in the laboratory than on external tracks. This manifests itself in consistently lower levels of adhesion in the laboratory compared to external tracks, and these levels change considerably over the life of the surface.

[0068] Current state of the art shows that no natural rock can limit the polishing mechanism and maintain levels of adhesion comparable to those of external tracks.

[0069] The floor described here, which can be obtained using the process described above, overcomes these drawbacks thanks to the elastic modulus of the substrate and the hardness of its surface area and / or the material of the surface coating.

[0070] The substrate 110 may comprise or be formed from a mass, for example a metallic mass. The substrate 110 may comprise steel, for example stainless steel, for example X4CrNiMoN21-9-4 stainless steel and / or austenitic stainless steel, for example X2CrNi18-9 stainless steel, and / or carbide, for example tungsten carbide, and / or ceramic, for example zirconia ceramic, for example Zr700 zirconia. The substrate 110 may comprise or be formed and / or made of a steel mass, for example stainless steel, for example X4CrNiMoN21-9-4 stainless steel and / or austenitic stainless steel, for example X2CrNi18-9 stainless steel, tungsten carbide and / or ceramic, for example zirconia ceramic, for example Zr700 zirconia.

[0071] The floor can have a Vickers hardness of between 1300 and 10000 kgf / mm 2< at the level of the surface of use 120, preferably between 1500 and 3500 kgf / mm 2<.

[0072] The floor has a 130 surface coating. This increases surface hardness, particularly in the area of ​​use, resulting in high resistance to polishing.

[0073] The surface coating 130 can have a thickness between 0.1 and 100 µm, preferably between 2 and 5 µm, preferably 3 µm. The coating thickness can thus be chosen so as not to modify the roughness amplitude, and therefore not to modify the friction response of the substrate.

[0074] The surface coating 130 may comprise amorphous carbon (known as "Diamond-Like Carbon" in Anglo-Saxon terminology) and, according to the invention, comprises titanium nitride and / or chromium nitride. The coating may thus comprise tungsten carbide.

[0075] The surface coating 130 includes the usable surface 120.

[0076] The 120 mm usable surface can be used as a test surface. The 120 mm usable surface can be adapted so that the item to be tested is applied to it.

[0077] The usable surface 120 may have a relief as described above.

[0078] The average texture depth at the surface of use 120 is between 0.3 and 1.7 mm, for example 1 mm. The average texture depth is established in accordance with European Commission Regulation (EU) No 228 / 2011 of 7 March 2011, Annex V 3.1(4).

[0079] The coefficient of friction between a tire and the ground at the level of the contact surface 120 can be between 0.5 and 2. Such a coefficient of friction is measured, for example, by a steady-state linear friction test under wet conditions, for example, when the contact surface 120 and / or the ground is immersed in water, for a cumulative sliding length, or kinematic length, of 100 mm, at 4 bar, for a speed of 1 m / s, at a water temperature of 25°C. The cumulative sliding length, or kinematic length, is the amount of relative displacement of two surfaces, for example, those of the tire and the ground, combined in the ground frame of reference.

[0080] The rubber used to establish the coefficient of adhesion can be a rubber with a composition representative of the rubbers used in tire tread compound.

[0081] The rubber for establishing the coefficient of adhesion can be characterized by a loss factor tan(δ) and a complex modulus G*.

[0082] The dynamic property max(tan(δ)) is measured, for example, on a viscoelastic analyzer 5 (Metravib V A4000), according to ASTM D 5992-96. The measurement involves recording the response of a vulcanized composition sample (e.g., a cylindrical specimen 4 mm thick and with a cross-section of 400 mm²) subjected to sinusoidal alternating simple shear loading at a frequency of 10 Hz under standard temperature conditions (e.g., 23°C) according to ASTM D 1349-99. The recorded response is then subjected to a peak-to-peak strain amplitude sweep from 0.1 to 50% (forward cycle), and then from 50% to 1% (reverse cycle). The result used is the loss factor tan(δ). For the reverse cycle, the maximum observed value of tan(δ) is indicated.

[0083] The complex modulus is measured, for example, as follows. The measurement involves recording the response of a vulcanized compound sample subjected to sinusoidal alternating simple shear loading during a temperature sweep. The sample is subjected to sinusoidal loading at an imposed stress of 0.7 MPa and a frequency of 10 Hz, with the temperature ranging from -60°C to 100°C, at a rate of 1.5°C per minute. The temperature of the maximum tan(δ) of the rubber compound in the recorded response is denoted "Tg (°C) max(tan(δ))". Another result used is the complex dynamic shear modulus (G*), for example, at 60°C. For readability, G* results will be expressed as a base of 100, with 100 being assigned to the control. A result less than 100 indicates a decrease in the value concerned, and conversely, a result greater than 100 will indicate an increase in the value concerned.

[0084] The surface in use, for example the floor, may have a shape including at least one curved portion, for example an arc of a circle. The surface in use, for example the floor, may have a shape including at least one closed curve, for example a circle. The floor can thus form a steering wheel.

[0085] The working surface, for example the ground, may have a shape comprising at least one portion forming a strip, for example a closed strip, for example a track shape. Such a working surface or ground may be used with a flat track roller as described below.

[0086] The soil can be shaped into a test specimen. The soil can have dimensions adapted to form a test specimen suitable for use by a test device as described below. Device

[0087] With reference to the figure 3A device 31 for testing an element 32 is described. The device 31 includes a floor 1 as described above. The device 31 includes means 312 for applying the element 32 to the floor 1, for example, the element 32 to the application surface 120, and / or for setting the element 32 and the floor 1 in relative motion.

[0088] The application means 312 may include an applicator adapted to apply the element 32 to the ground 1. The applicator may include an arm.

[0089] The movement can be rectilinear or rotational. The movement can be a movement of the ground, with element 32 remaining fixed.

[0090] The application means 312 may include a motor and / or a shaft and / or an arm adapted to put the element 32 and the ground into relative motion.

[0091] Component 32 may be or include a tire and / or a part of a tire and / or a rubber compound. Component 32 may be or include at least a portion of a wheel, for example, a wheel.

[0092] The application means 312 can be adapted to regulate the speed of the element 31 relative to the ground, for example a linear speed or an annular speed, for example a rotational speed. The speed can be between 0.5 and 1.5 m / s, for example between 0.9 and 1.2 m / s.

[0093] The device may include temperature control means to control the ambient temperature and / or the initial temperature of element 31. The device and / or an assembly or system comprising the device may include temperature control means. These temperature control means may include a temperature control device, for example, a thermostat, a heater, a resistor, and / or a cooling device. The device is configured, for example, to control the temperature to maintain it between 20 and 30°C, for example, at 25°C.

[0094] The device may include means for measuring at least one physical quantity, for example, one or more physical quantities. The measuring means may include a sensor for measuring at least one physical quantity, for example, force and / or moment.

[0095] The device may include data processing means, for example by a data processing unit, such as a processor. The data processing means are, for example, the same as those already described in the manufacturing process and / or the same as those described in the usage process below.

[0096] Device 31 can be a tribometer, for example a linear tribometer or a tribometer having a rotational configuration or rotary tribometer.

[0097] The application means 312 can be adapted to apply a normal force to the ground, for example normal to a median plane, for example normal to a median plane corresponding to the surface of use, for example so as to control an average contact pressure of the element 32 on the ground.

[0098] The application means 312 are, for example, adapted to move the element 31 tangentially to the ground, for example, to the surface of use. When the tribometer is linear, the displacement can be a rectilinear translation. Alternatively, when the tribometer is rotary, the displacement can follow an annular path, for example, be a rotation.

[0099] The measuring methods can be adapted to measure a force, in particular a tangential force. The physical quantity or quantities, for example the force, can be measured at the interface between element 32 and the ground.

[0100] The device, for example the means of data processing, can be adapted to determine at output a dimensionless coefficient of friction by normalizing the tangential force by the normal force.

[0101] Device 31 can be a roller. The roller can be a device adapted to roll element 32. The roller can be adapted to control the orientation of element 32, for example, the orientation of the median plane of element 32, for example, the orientation of the median plane of the wheel or wheel portion of element 32, so as to apply stresses to element 32. Alternatively or in addition, the roller can be adapted to control the speed of element 32 so as to apply stresses to element 32. Alternatively or in addition, the roller can be adapted to control the torque applied to element 32, for example, at the center of element 32, for example, at the center of the wheel or wheel portion of element 32.

[0102] The means 312 can be adapted to apply a force from the element 32 to the ground, for example a force of increasing intensity over time, for example until a force setpoint is reached.

[0103] The measuring instruments can be adapted to measure a force and / or a moment. At least one physical quantity, for example the force, can be measured at the center of the element, for example at the center of the wheel of element 32.

[0104] The device, for example the data processing means, can be adapted to determine the adhesion of the element to the ground, for example from the force and / or moment measured by the measuring means.

[0105] The roller can be a "flat-track" type roller. For such a roller, the surface of use, for example the ground, can have a shape including at least one portion forming a strip as described above. Method of use

[0106] In reference to the figure 4 A method for testing the element is described. The element can be tested using device 31.

[0107] The process may include a step 41 of applying element 32 to soil 1.

[0108] The process may include a step 42 of measuring the behavior of element 32 on the ground 1, in particular on the use surface 110. Rolling machine

[0109] The device is or includes, for example, the rolling machine as described above.

[0110] Step 41 can be implemented without relative and / or absolute rotation of the element and / or the ground. Step 41 can then include the application of a force from the element 32 on the ground, for example a force increasing in intensity over time, for example until a set force value is reached.

[0111] Alternatively, or in addition to another step 41 of applying the element to the ground, step 41 may include rotating the ground relative to the element, for example, so that the ground causes the element to rotate, resulting in both the ground and the element rotating in the laboratory frame of reference. The rotation of the element 32 may be regulated, in terms of torque and / or slip rate, for example, according to a control setpoint. The control setpoint may include a zero or non-zero torque setpoint at a predetermined value. The control setpoint may include a zero or non-zero slip rate setpoint at a predetermined value.

[0112] Alternatively, or as a complement in another step 41 of applying the element to the ground, an animation can be applied to the element 32, for example a variation in the drift angle of the element relative to the ground and / or a variation in the camber angle of the element relative to the ground and / or a variation in load, and / or a variation in the rate of slip.

[0113] Step 42 may include the measurement of one or more forces and / or one or more moments, for example at the center of the wheel when element 32 includes a wheel as described above.

[0114] The process may include obtaining adhesion of the element to the ground, for example by means of treatment, for example from measurements of force(s) and moment(s). Tribometer

[0115] The device is or includes, for example, the tribometer as described above.

[0116] Step 41 may include the application of a normal force to the ground, for example normal to a median plane, for example normal to a median plane corresponding to the area of ​​use, for example so as to control an average contact pressure of the element 32 on the ground.

[0117] Step 41 may involve applying element 31 tangentially to the ground, for example, to the work surface. When the tribometer is linear, the displacement may be a rectilinear translation. Alternatively, the displacement may follow an annular path, for example, a rotation.

[0118] Step 41 may include control of the ambient temperature and / or the initial temperature of element 31. The device and / or an assembly or system comprising the device may include means for temperature control.

[0119] Step 42 may include the measurement of a force, in particular a tangential force. At least one physical quantity, for example the force, may be measured at the interface between element 32 and the ground.

[0120] The process may include determining at the output a dimensionless friction coefficient by normalizing the tangential force by the normal force, for example by the processing means. Detailed example

[0121] With reference to the figure 6 , a detailed example is described implementing a test floor which is not part of the claimed invention.

[0122] The soil substrate is metallic, made of X4CrNiMoN21-9-4 stainless steel, the relief of which was generated by pulsed laser machining from a solid, for example by nanosecond pulsed laser machining.

[0123] The surface coating of the soil consists of amorphous carbon of approximately 3 µm.

[0124] The reproduced relief corresponds to a reference ground.

[0125] For the test floor, only the rim of the reference floor between a radius of 30 mm and a radius of 46 mm is textured to show the relief.

[0126] The reference soil surface was previously converted into a solid and recorded to allow the fabrication of the test soil.

[0127] The evolution of the test soil under friction is tested using a tribometer. figure 6 represents the evolution of the maximum normalized friction coefficient as a function of the kinematic length in m on a logarithmic scale, at a speed of 1.2 m / s, a pressure of 4 bars, and an ambient temperature of 25°C.

[0128] The friction test surface is observed at different stages of polishing, measured in kinematic lengths (1, 25, 250, 1000, 2500 m). The lapping is carried out at a single operating point (4 bar, 1.2 m / s, 25°C).

[0129] The test soil offers a very high level of normalized coefficient of friction (µ), even at very high cumulative sliding or kinematic lengths.

[0130] Furthermore, during the measurement the test soil changes very little visually.

[0131] The presence of the amorphous carbon coating does not noticeably alter the reliefs, and improves the resistance to polishing performance.

[0132] Curves 601 and 602 represent the evolution observed on a sandstone lapping surface. Curve 603 of the test surface is completely unaffected by polishing.

Claims

1. Ground surface comprising a substrate (110) having a Young's modulus of between 100 and 1000 GPa, comprising a surface coating forming a working surface, wherein the surface coating contains titanium nitride and / or chromium nitride, the working surface having a relief, the mean texture depth of which is comprised between 0.3 and 1.7 mm.

2. Ground surface according to Claim 1 having at a working surface (120) a Vickers hardness of between 1300 and 10000 kgf / mm2, the surface coating further containing amorphous carbon and / or tungsten carbide.

3. Ground surface according to either one of Claims 1 to 2, wherein the surface coating has a thickness of between 2 and 5 µm.

4. Ground surface according to any one of Claims 1 to 3, wherein the substrate has a Young's modulus of between 100 and 500 GPa, and / or wherein the ground surface has, on the working surface, a Vickers hardness of between 1500 and 3500 kgf / mm2, and / or wherein the substrate contains stainless steel and / or tungsten carbide and / or ceramic.

5. Ground surface according to any one of the preceding claims, wherein the coefficient of grip between a rubber and the ground surface at the working surface of the ground surface is between 0.5 and 2, the rubber being a rubber having a composition representative of the rubbers used in a tyre tread compound.

6. Test device for testing a component, comprising: - a ground surface according to any one of the preceding claims, and means (312) for pressing the component against the ground surface and / or for creating relative movement between the component and the ground surface.

7. Test device according to Claim 6, wherein the device is a rolling device, or wherein the device is a tribotester and wherein the component comprises a rubber, the device being configured such that the coefficient of grip between the rubber and the ground surface at the working surface of the ground surface is between 0.5 and 2.

8. Method for manufacturing a ground surface according to any one of Claims 1 to 5, the method comprising a step (21) of obtaining the substrate and a surface treatment step comprising a step of forming the surface coating that forms the working surface.

9. Method according to Claim 8, wherein the step of obtaining the substrate comprises a step (212) of determining a relief to be reproduced, the step (212) of determining a relief to be reproduced comprising a step (2122) of obtaining a reference ground surface, for example by taking a core sample of a road, and a step (2123) of measuring a relief of the reference ground surface.

10. Method according to any one of Claims 8 to 9, wherein the step of obtaining the substrate comprises a step (213) of generating a relief on the substrate by additive manufacturing using a ceramic, or wherein the step of obtaining the substrate comprises a step (213) of generating a relief by machining, for example by laser machining.

11. Method according to Claim 10, wherein the laser machining is laser machining of a solid lump containing tungsten carbide, or wherein the laser machining is laser machining of a solid lump containing stainless steel.

12. Method according to any one of Claims 10 to 11, wherein the step of obtaining the substrate comprises a step (213) of generating the relief by surface laser melting using a stainless steel powder.

13. Method according to any one of Claims 8 to 12, wherein the step of obtaining the substrate further comprises a step (214) of modulating the relief generated.

14. Test method for testing a component by means of the device of any one of Claims 6 to 7, involving pressing the component onto the ground surface and / or creating relative movement between the component and the ground surface.