SCRATCH-RESISTANT LIGHTWEIGHT BOARD

Description

[0001] The invention relates to a method for producing a lightweight panel, comprising the steps: Producing a fiber-reinforced base plate by embedding a fiber material in a base matrix material and mechanically bonding it to the base matrix material, producing and applying a coating to a surface of the base plate. Furthermore, the invention relates to a plate material comprising: a fiber-reinforced base plate with a fiber material embedded in a base matrix material and mechanically bonded to the base matrix material, a coating on a surface of the base plate,

[0002] Panel materials of the aforementioned type and corresponding processes for their production are important in various fields of technology. Such panel materials are often used as lining or cladding materials in vehicle construction, for example, in rail vehicles, coaches, aircraft, or road vehicles. Another area of ​​application is ducts or cladding in the interior of buildings or for building facades.

[0003] US 2017 / 0182719 A1 discloses a method for producing a composite structure with a surface film according to the preamble of claim 1.

[0004] The surface film comprises, in particular, a novolac epoxy resin structure, ceramic particles, an amine-based hardener, and an inorganic filler. US Pat. No. 5,391,425 discloses a fiber-reinforced composite material and a corresponding manufacturing process.

[0005] In these applications, the panel material's lightweight, corrosion-resistant, and sufficiently rigid properties are particularly appreciated. At the same time, the manufacturing process enables cost-effective mass production, making it financially viable for many applications.

[0006] Such a panel material is initially designed in its basic structure for certain mechanical properties, namely flexural strength, tensile strength, impact strength and compressive strength, and can usually be designed accordingly in these properties by appropriate selection of matrix material and fiber material.

[0007] In a typical application, such a lightweight panel is used as a floorboard, covered with carpets or other coverings. Such carpets or coverings are subject to a certain degree of wear, necessitating replacement at regular intervals. In other applications, the lightweight panel can be covered with a decorative film or similar covering. Here, too, the need arises for these coverings to be replaced for decorative reasons, for example, when an aircraft or vehicle interior is to be given a new cabin design.

[0008] During replacement, although this is generally not permitted by labor regulations, it is sometimes necessary to use cutting tools such as utility knives, either to facilitate the removal of the old carpet / covering or to ensure the precise installation of the new carpet / covering. For example, the carpet / covering can be cut into strips so that they can then be more easily torn off as strips.

[0009] However, this cutting often results in scoring or even partial severing of the underlying composite materials. In particular, this can cause notch effects or cross-sectional reductions in the surface, which can lead to a loss of strength and stiffness of the lightweight panel.

[0010] In principle, it is desirable to keep mechanical damage to the surface of such panel materials as low as possible or to prevent it, since such mechanical damage could endanger the structural integrity of the panel if entire layers of fiber material were to be cut through. However, usual measures such as the use of durable materials cannot be used with such panel materials, as this would make the panels too heavy.

[0011] Against this background, there is a need for a panel material that maintains its structural integrity over the long term while being manufactured cost-effectively. It is preferred that the weight advantages of the lightweight panel are not, or only slightly, reduced.

[0012] This problem is solved according to the invention by a method according to claim 1.

[0013] The introduced particles cause any cutting tool, e.g. the cutter knives mentioned above, to be blunt after a cutting length of just a few centimeters, thus preventing or at least reducing further damage to the underlying laminate, particularly to the fibers of the laminate.

[0014] The fiber-reinforced base plate according to the invention can be a solid fiber-reinforced plate, but can also be constructed as a sandwich plate, i.e., composed of a cover layer and a base layer, or typically of two cover layers sandwiching a middle layer. The base layer or middle layer is typically made of a lightweight, less mechanically resilient material than the cover layer(s). The cover layers are typically fiber-reinforced materials, and the middle layer or base layer can, for example, be a honeycomb structure with air-filled cavities. In this embodiment, the coating according to the invention is then applied to the outer surfaces of the cover layer.

[0015] According to the invention, a coating is applied by embedding ceramic particles in a layered matrix material and mechanically bonding them thereto. The ceramic particles are enclosed in the layered matrix material, which means that the ceramic particles are enclosed on all sides by the layered matrix material or, if they are located in the area of ​​a surface of the coating, are almost enclosed on all sides with the exception of a small surface area of ​​the particle that faces the environment. Ceramic particles are understood to be bodies with small dimensions, which are present, for example, in heaped powder or granulate form, and are therefore generally pourable.A particle for the application according to the invention preferably has a balanced ratio of height, width and depth, with, for example, approximately equal dimensions in the three spatial directions, but can also have a shape elongated in one or two directions such as a rod or platelet shape, wherein the ratio to achieve the objectives of the invention preferably does not exceed 1:2 to 1:5. A ceramic material is understood to be a material that, in contrast to plastic or metal, consists of a ceramic, for example an oxide ceramic, a carbide ceramic or a nitride ceramic. The coating is applied by materially bonding the coating to the base plate and mechanically fastened, whereby a materially bonding of the layer matrix material to the base matrix material takes place.The bonding of the coating therefore primarily results from the adhesive bond between the layer matrix material and the base matrix material, which can also be formed as a cohesive bond if the chemical properties of the two matrix materials match. A cohesive bond is understood here as a bond that derives its mechanical bonding force from adhesive or cohesive forces. The cohesive bond according to the invention does not exclude the presence of other, supporting bonding mechanisms, for example, positive bonding mechanisms or force-locking bonding mechanisms, which can be implemented between the coating and the top plate by appropriate geometric designs in the transition area between the layer and the base plate.

[0016] According to a first preferred embodiment, the ceramic particles have a grain size of more than 10 µm, preferably more than 20 µm, in particular more than 30 µm, and / or less than 300 µm, less than 150 µm or preferably less than 75 µm, in particular less than 50 µm. According to this embodiment, the ceramic particles have a minimum grain size and / or a maximum grain size. A grain size is generally understood here to mean that the grain size defines the dimension of the grain in any direction, i.e. in the case of a minimum grain size, the grain is not smaller than the minimum grain size in any direction and in the case of a maximum grain size, it is not larger than the maximum grain size in any direction.The grain size range defined in this way achieves particularly favorable resistance of the coatings to mechanical influences such as scratches or erosive influences, without impairing the mechanical adhesion of the layer to the base plate.

[0017] Preferably, a mixture of different grain sizes within these range limits can be used, whereby different grain sizes is understood to mean a non-monomodal mixture of grain sizes. Such a non-monomodal mixture can, for example, be composed of two different monomodal grain mixtures; it can also be represented by a broad Gaussian distribution extending from the lower to the upper range limit, whereby it should be understood that a grain size distribution with a Gaussian distribution typical for the respective grains is not understood to be a mixture of different grain sizes. The use of a mixture of different grain sizes has the advantage that smaller particles can settle in the gaps between larger particles, thereby creating a dense packing of the grains, which provides particularly good cut protection.It is even more preferred if the base matrix material and the layer matrix material are identical. By designing the base matrix material and the layer matrix material identically, a particularly mechanically resilient, cohesive bond between the two matrix materials can be achieved, in particular a highly resilient bond, or, if the base matrix material is rendered chemically active during the application of the coating, for example, through a dissolving or melting process, even cohesive bonding mechanisms.

[0018] In addition to an identical base matrix material and layer matrix material, the base matrix material and layer matrix material can also be different but can be partially dissolved with a similar solvent, or different but have the same melting point. This development ensures that both the base matrix material and the layer matrix material can be converted into a chemically or physically active state by dissolving or heating, which promotes the strong bond between the base plate and the coating.

[0019] It is even more preferred if the production and application of the coating includes heating the layer matrix material. According to this embodiment, the layer matrix material is heated during the production and application of the coating, thereby achieving either physical activation to achieve better bonding or partial melting or complete melting of the layer matrix material to achieve better bonding.

[0020] According to the independent method claim, the production and application of the coating comprises applying the layer matrix material to the surface of the base plate and subsequently applying the ceramic particles to the layer matrix material, wherein the layer matrix material is not cured at least at the beginning of the application of the ceramic particles. According to this embodiment, the application of the layer matrix material and the application of the ceramic particles take place with a time delay. Accordingly, at least at the beginning of the application of the layer matrix material, no application of the ceramic particles takes place, which consequently precludes pre-mixing of the layer matrix material with the ceramic particles for this initial phase. This creates a particularly favorable boundary layer to the base matrix material, i.e. the surface of the base plate, which is not interrupted by ceramic particles and thus promotes adhesion.In a subsequent step, the ceramic particles can then be applied. This can occur after the application of the layered matrix material has been fully completed, or it can completely overlap with the application of the layered matrix material. Likewise, the application of the ceramic particles can only partially overlap with the application of the layered matrix material, so that ceramic particles are still applied even after the application of the layered matrix material has been completed, in this case to the surface of the layered matrix material. Fundamentally, these process configurations achieve an increase in the particle density, i.e., the number of particles per unit volume in the coating in a direction starting from the boundary layer to the base material.This allows the particle density to be particularly high, especially on the surface of the coating facing the environment, which provides particularly favorable properties against mechanical influences such as scratches and erosion. In particular, this modified manufacturing process can achieve a gradual increase in particle density, with the particle density increasing from the boundary layer to the base material with increasing distance from this boundary layer in the coating.

[0021] It is even more preferred if the ceramic particles have a Mohs hardness greater than 6, preferably greater than 7, in particular greater than 8 or greater than 9. It has been shown that ceramic particles with a Mohs hardness in this range provide particularly favorable properties against mechanical influences, which are also generated, for example, by hardened steel blades, and at the same time achieve good bonding in the layer matrix material, without the risk of embrittlement and dissolution of the particles due to the stresses caused by inhomogeneity or unequal chemical properties.

[0022] According to the independent claims, the ceramic particles are a metal carbide or metal oxide. The layer matrix material is a thermoset.

[0023] This selection of ceramic particles and layered matrix material is particularly well-suited to achieving a resilient bond between the particles within the layered matrix material, on the one hand, and a good bond between the layered matrix material and the base matrix material, on the other. In particular, the layered matrix material and the base matrix material can be identical or identical in terms of melting point or solvent solubility.

[0024] It is even further preferred if the ceramic particles are introduced into the coating with a volume fraction of more than 60% or more than 70%, preferably in the range from 75% to 85% of the volume of the coating. According to this embodiment, a significantly high volume fraction of ceramic particles is provided in the coating, whereby it is to be understood that 60% or 70% or more or 75% to 85% of the volume of the coating is provided by the volume of the particles in the coating. In this case, it is to be understood that this volume fraction is understood as the average value of the volume fraction of the particles in the layer, so that with, for example, a gradual build-up of the layer, a higher volume fraction of the particles in certain regions of the layer, coupled with a correspondingly lower volume fraction of the particles, even below 60%, in other regions of the layer, also falls under this development.

[0025] According to a further preferred embodiment, the coating is applied to the surface of a workpiece mold and subsequently the base matrix material is introduced into the workpiece mold and bonded to the coating. According to this embodiment, the coating is applied to a surface of a workpiece mold, in particular to an inner side of a workpiece mold, wherein the workpiece mold serves to produce the entire component. This surface can be flat or curved, depending on the desired geometry of the workpiece or sheet material to be produced with it. Applying the coating to the surface of a workpiece mold has the advantage that it can produce a defined surface of the coating which faces the environment during later use.This defined surface is defined by the surface of the workpiece shape and can be particularly smooth or have an intended structure. The manufacturing process is similar to the so-called gelcoat process, which is known for the production of boat hulls, but in the method of use according to the invention has the advantage that the particles embedded in the coating are advantageously integrated into the coating, do not protrude from it, and thus favorable surface properties can be achieved. Production can take place using a so-called wet-on-wet process, in which the coating is not yet fully cured at the time the base matrix material is applied, i.e. is still reactive enough to form a liquid compound. If necessary, the surface can be heated for this purpose in order to improve adhesion to the base matrix material.Alternatively, the bond between the base matrix material and the coating can also be made after the coating has completely cured in the workpiece mold.

[0026] A further aspect of the invention is a plate material according to the independent material claim.

[0027] The base plate can preferably be manufactured using the method described above. The plate material is characterized in that a fiber-reinforced base plate is provided with a coating comprising ceramic particles embedded in and bonded to a layered matrix material. This creates a layer on the base plate that is robust and resistant to mechanical influences. The coating is bonded to the base plate by a material bond between the layered matrix material and the base matrix material. This ensures that the coating is not detached from the base plate by mechanical influences of a typical magnitude and therefore provides permanent mechanical protection.

[0028] The plate material according to the invention can be developed in that the ceramic particles have a grain size of more than 10µm, preferably more than 20µm, in particular more than 30µm, and / or less than 300µm, preferably less than 75µm, in particular less than 50µm.

[0029] Furthermore, the plate material can be further developed by making the base matrix material and the layer matrix material identical.

[0030] A further development provides that the coating comprises a fabric material.

[0031] According to the independent material claim, the coating comprises a layer facing the surface of the base plate and a coating surface opposite the surface of the base plate, and in the region of the coating surface, a volume fraction of the ceramic particles in the coating is greater, in particular at least twice as large, than a volume fraction of the ceramic particles in the coating in the layer facing the base plate.

[0032] Finally, a further development provides that the plate material is produced according to a process or one of the process features described above.

[0033] With regard to the plate material and the further developments explained in relation to it, it is to be understood that the properties, characteristics and advantages of this plate material correspond to those previously described with regard to the corresponding process characteristics of the manufacturing process for a plate material.

[0034] A preferred embodiment is described with reference to the accompanying figures. They show: Figure 1 a first embodiment not falling within the claims. Figure 2 a second embodiment of the invention and Figure 3 a third embodiment of the invention.

[0035] In Figure 1 , which is not covered by the claims, a section of a plate material provided with a coating is symbolically shown in a sectional side view. Basically, it should be understood that the thickness of the coating in Figure 1 and the Figures 2 and 3 is not reproduced to scale with respect to the thickness of the base plate, but is shown enlarged without scale for better explanation. In principle, the ratio between the thickness of the coating and the thickness of the base plate in the invention can be implemented within a wide range, for example within a range of 1:25 to 1:100 and can, if the thickness of the base plate fluctuates, also be variable on a workpiece. In particular, the thickness of the coating can be essentially constant for the entire workpiece, but can be implemented differently locally for the base plate.

[0036] The base plate 10 is in the embodiment according to Figure 1designed as a flat plate and consists of a base matrix material 11 and non-oriented short fibers 11 embedded therein. The base plate has a surface 12 to which a coating 20 is applied. The coating 20, in turn, consists of a coating matrix material 21 and ceramic particles 22 embedded therein. A fluid bond is formed between the coating and the base plate by adhesive forces that act essentially between the base matrix material and the coating matrix material. The particles 22 are homogeneously distributed in the layer matrix material, so that in every layer plane, i.e., at every depth of the layer and at every location in the layer, there is essentially the same particle density in the sense of a number of particles per unit volume of the coating.The coating has a surface 23 which is parallel to the surface 13 of the base plate and is also substantially flat and smooth.

[0037] Figure 2 shows a second embodiment in which the basic geometry of coating and base plate is consistent with Figure 1 In this embodiment, the base plate 110 is designed as a fabric-reinforced composite material with three fabric layers 112a, b, c embedded in a base matrix material 111. The fabric layers 112a, b, c are parallel to one another in the exemplary embodiment, but can also be embedded in the base matrix material in different orientations to one another.

[0038] The base plate 110, in turn, has a surface 113 to which a coating 120 is applied and affixed with a liquid material. The coating comprises a layered matrix material 121 in which ceramic particles 122 are embedded. The coating 120 has a surface 123 facing the environment.

[0039] The coating 120 has an upper layer level 124 adjacent to the surface 123 and a lower layer level 125 adjacent to the surface 113 of the base plate. In the upper layer level 124, the particles are present at a high particle density, i.e., many particles are embedded per unit volume of the coating. In the lower layer level 125, in contrast, a lower particle density is present. The particle density changes continuously or gradually from the surface 123 to the surface 113, so that there is no sharp transition between the high particle density in the region of the surface 123 and the lower particle density in the region of the surface 113.

[0040] The Figure 2The distribution of particle density within the coating shown can be achieved in various ways in terms of manufacturing technology. In principle, the viscosity of the layer matrix material, the density ratio of the particles to the layer matrix material, and the temporal curing process of the layer matrix material after the time of addition of the particles generally play a role. In principle, according to a first manufacturing method, the different particle density in the coating can be achieved by applying the layer matrix material to the base plate in a first manufacturing step, and in a second, subsequent step, the particles are applied to the surface 123 and then penetrate the coating - for example due to gravity. This gravity-induced penetration process of the particles can alternatively also be brought about by other forces, for example centrifugal forces.The timing of particle addition in relation to the viscosity progression of the layer matrix material after this addition until complete curing or reaching a viscosity at which the particles can no longer move within the layer matrix material is crucial for the particle density progression. In principle, the timing of particle application to the surface can be chosen such that a time interval remains after this time until the layer matrix material cures, causing partial penetration of the particles into the layer matrix material, thereby producing the different particle densities with a higher particle density at the surface of the coating and a lower particle density in the depth of the coating.

[0041] An alternative manufacturing method is possible by applying the layer matrix material to a workpiece mold. In this case, the particles can already be premixed with the layer matrix material before application to the workpiece mold, or the particles can be applied to the layer matrix material after the layer matrix material has been applied to the workpiece mold. In this case of the manufacturing process, movement of the particles up to the layer surface 123 is increasingly desired and can be brought about by gravity or other forces. By allowing the particles to move for a sufficiently long time in the layer matrix material, collection of the particles on the surface 123 can be achieved, thereby reducing the particle density in the depth of the layer compared to the particle density on the surface of the layer.In this case, the time of curing of the layer matrix material or the time of reaching such a high viscosity that there is no longer any particle mobility within the layer matrix material is chosen such that at this time there are still particles present in the depth of the layer, but a predominant part of the particles has moved to the surface 123 of the coating and thus the different particle density is achieved.

[0042] Figure 3 shows a third embodiment of the invention. In this embodiment, the base plate 210 is identical to the base plate 10 of the first embodiment according to Figure 1 and comprises a base matrix material 211 with unoriented short fibers 212 arranged therein. The base plate, in turn, has a surface 213 to which a coating 220 is applied.

[0043] The coating 220 has been prefabricated as a prepreg and has two fiber reinforcement layers 227a, b. The fiber reinforcement layers 227a, b are embedded in a layered matrix material 221. Furthermore, ceramic particles 222 are embedded in the layered matrix material 221.

[0044] The fiber reinforcement layers 227a, b divide the coating 220 into three layer levels 226a, b, and c. The uppermost layer level 226a is adjacent to and adjacent to a coating surface 223. This uppermost layer level 226a has a high particle density.

[0045] The middle layer level 226b lies between the two fiber reinforcement layers 227a, b and has a lower particle density than the upper layer level 226a.

[0046] The lower layer level 226c lies between the surface 213 and the lower fiber reinforcement layer 227b. The lower layer level 226c has a lower particle density than the middle layer level 226b.

[0047] The different particle densities in the layer planes 226a, b, and c are achieved by penetrating different amounts of particles into the layer planes during prepreg production. The fiber reinforcement layers 227a, b act as a membrane and prevent particles from passing from one layer plane to the other.

Claims

1. Method for manufacturing a lightweight panel, comprising the steps: - producing a fibre-reinforced base plate (10, 110, 210) by embedding a fibre material (12, 122, 212) in a base matrix material (11, 111, 211) and mechanically bonding it to the base matrix material (11, 111, 211), - producing and applying a coating (20, 120, 220) to a surface of the base plate (10, 110, 210), wherein - producing and applying the coating (13, 20) includes embedding ceramic particles (22, 122, 222) in a layer matrix material (21, 121, 221) and bonding the ceramic particles (22, 122) to the layer matrix material (121), and - applying the coating includes adhesively bonding the coating (13, 20) to the base plate (10, 110, 210), comprising adhesively bonding the layer matrix material (21, 121, 221) to the base matrix material (11, 111, 211), wherein, in the step of producing and applying, ceramic particles (22, 122, 222) comprising a metal carbide or metal oxide are introduced, and a duromer is used as the layer matrix material (21, 121, 221), characterised in that producing and applying the coating comprises applying the layer matrix material (21, 121, 221) to the surface of the base plate (10, 110, 210) and subsequently applying the ceramic particles (22, 122, 222) to the layer matrix material (21, 121, 221), wherein the layer matrix material (21, 121, 221) is not cured at least at the beginning of the application of the ceramic particles (22, 122, 222).

2. Method according to claim 1, characterised in that the ceramic particles (22, 122, 222) have a grain size - greater than 10µm, preferably greater than 20µm, in particular greater than 30µm, and / or - less than 300µm, preferably less than 75µm, in particular less than 50µm.

3. Method according to claim 1 or 2, characterised in that the base matrix material (11, 111, 211) and the layer matrix material (21, 121, 221) are identical.

4. Method according to one of the preceding claims, characterised in that producing and applying the coating comprises heating the layer matrix material (21, 121, 221) and / or the particles (22, 122, 222) to be introduced.

5. Method according to one of the preceding claims, characterised in that the ceramic particles (22, 122, 222) have a Mohs hardness greater than 6, preferably greater than 7, in particular greater than 8.

6. Method according to one of the preceding claims, characterised in that, in the step of producing and applying the coating, a layer facing the surface of the base plate (10, 110, 210) and a coating surface facing the surface of the base plate (10, 110, 210) are produced, and that in the region of the coating surface, a volume fraction of the ceramic particles (22, 122, 222) in the coating is greater than a volume fraction of the ceramic particles (22, 122, 222) in the coating in the layer facing the base plate (10, 110, 210).

7. Method according to one of the preceding claims, characterised in that the ceramic particles (22, 122, 222) are introduced into the coating with a volume fraction of more than 75% of the volume of the coating.

8. Plate material comprising: a fibre-reinforced base plate (10, 110, 210) with a fibre material (12, 122, 212) embedded in a base matrix material (11, 111, 211) and mechanically bonded to the base matrix material (11, 111, 211), a coating on a surface of the base plate (10, 110, 210), wherein the coating comprises a layer matrix material (21, 121, 221) and ceramic particles (22, 122, 222) embedded in the layer matrix material (21, 121, 221) and bonded to the layer matrix material (21, 121, 221), and the layer matrix material (21, 121, 221) is adhesively bonded to the base matrix material (11, 111, 211), wherein the ceramic particles (22, 122, 222) are made of a metal carbide or metal oxide, and the layer matrix material (21, 121, 221) is formed as a duromer, characterised in that the coating has a layer facing the surface of the base plate (10, 110, 210) and a coating surface facing the surface of the base plate (10, 110, 210), and that in the region of the coating surface, a volume fraction of the ceramic particles (22, 122, 222) in the coating is greater than, in particular at least twice as large as, a volume proportion of the ceramic particles (22, 122, 222) in the coating in the layer facing the base plate (10, 110, 210).

9. Plate material according to claim 8, characterised in that the ceramic particles (22, 122, 222) have a grain size - of more than 10µm, preferably more than 20µm, in particular more than 30µm, and / or - of less than 300µm, preferably less than 75µm, in particular less than 50µm.

10. Plate material according to claim 8 or 9, characterised in that the base matrix material (11, 111, 211) and the layer matrix material (21, 121, 221) are identical.

11. Plate material according to one of the preceding claims, characterised in that the coating comprises a fabric material.

12. Method according to one of the preceding claims, characterised in that the coating is applied to the surface of a workpiece mould, and subsequently the base matrix material (11, 111, 211) is introduced into the workpiece mould and bonded to the coating.