Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F41—WEAPONS
  • F41H—ARMOUR; ARMOURED TURRETS; ARMOURED OR ARMED VEHICLES; MEANS OF ATTACK OR DEFENCE, e.g. CAMOUFLAGE, IN GENERAL
  • F41H5/00—Armour; Armour plates
  • F41H5/02—Plate construction
  • F41H5/04—Plate construction composed of more than one layer
  • F41H5/0414—Layered armour containing ceramic material
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F41—WEAPONS
  • F41H—ARMOUR; ARMOURED TURRETS; ARMOURED OR ARMED VEHICLES; MEANS OF ATTACK OR DEFENCE, e.g. CAMOUFLAGE, IN GENERAL
  • F41H5/00—Armour; Armour plates
  • F41H5/02—Plate construction
  • F41H5/04—Plate construction composed of more than one layer
  • F41H5/0442—Layered armour containing metal

Definitions

• the invention relates to a shielding element, in particular for anti-ballistic protection, the impact surface of which has a shape particularly suitable for this function, a protection system comprising such an element and the method of manufacture of such an element.
• the invention finds its application in particular as armor used for bulletproof vests or other armor making it possible to protect vehicles (land, sea or air) or fixed installations (building, perimeter wall, guard post in particular).
• the additional mass associated with wearing an anti-ballistic protection element such as armor or armor is an essential criterion whether it concerns the protection of people but also with regard to vehicles. In particular, it is a question of avoiding an excessive weighting which is an obstacle to rapid movements and limits their range of action.
• the publication EP 1380809 A2 discloses for example a system comprising two layers of material, the first denser layer A formed at the surface by a carbide and a metal, for example a silicon carbide SiC and metallic silicon Si, and a second layer B more porous formed by carbide, for example silicon carbide. It is proposed by US6389594B1 an outer shell (or "outershell” in English) of the monolithic ceramic armor which is put under compressive stress. This envelope is made of a polymer material based on aramid or other anti-ballistic materials, in particular based on glass fibers.
• the object of the present invention is therefore to provide a new product, different from the products currently used in the field, and the ballistic performance of which is improved, at equal surface density.
• the present invention relates to a shielding element in the form of a monolithic body, for example a plate, a tube or a more complex shape such as a helmet, having a surface upper (or impact surface), in particular of straight or curved shape, comprising grains of a material qualified as hard.
• Said body may be provided on its inner face (or opposite to the impact face) with a rear coating for dissipating energy, preferably made of a material of lower hardness than that of the material constituting the body of the. protection element.
• the present invention relates to a shielding element, in the form of a monolithic body having an exterior face or impact face and an interior face, opposite to said impact face, said interior and exterior faces being of preferably substantially parallel, preferably mutually parallel in which: said body is made of a sintered material, the surfaces of said inner and outer faces are greater than or equal to 100 cm 2 , said body being characterized in that at least a portion of said impact face of said body is textured, such that, the average thickness E m between said outer and inner faces of said body on said portion is greater than 4 mm, -on this portion and along a plane i of internal section of said body parallel to said inner face, with 0 ⁇ i ⁇ 100 and i corresponding in percentage to the fraction of said mean thickness E m in plane i, starting from the inner face and in the direction of the impact face, Ai being the area occupied by the only material at thickness E i , at an intermediate surface located between the surface of the interior face of area A 0 and the outer surface of area A
• -AT i decreases continuously or discontinuously (for example by steps) according to i, when A i ⁇ A 0 (or again when E i > E 50 ) -AT 75 ⁇ 0.2 ⁇ A 0, -0.03 ⁇ A 0 ⁇ A 95 ⁇ 0.5 ⁇ A 0, preferably 0.04 ⁇ A 0 ⁇ A 95 ⁇ 0.2 ⁇ A 0. - AT 100 ⁇ 0.1 ⁇ A 0.
• the area of the intermediate surface of material along said plane of parallel internal section can be easily measured by a section of said body and preferably by non-destructive methods such as tomography and the use of software. computer-assisted drawing, for example. It is understood that the area A i occupied by the material alone also includes its possible porosity.
• the advantage of the present invention lies in an optimal choice of the profile of the element, making it possible to increase the initial contact surface with the projectile, without a substantial increase in material. Such an embodiment makes it possible to deflect the projectiles and to reduce their perforating power given the thickness of the non-textured part of the armor element necessary for the absorption of part of the energy due to the impact. in order to consequently limit its fragmentation.
• - A 75 ⁇ 0.9 ⁇ A 0 Preferably, A 75 ⁇ 0.6 ⁇ A 0 . More preferably A 80 ⁇ 0.4 ⁇ A 0. - AT 80 ⁇ 0.8 ⁇ A 0 .
• a 85 ⁇ 0.6 ⁇ A 0 More preferably A 85 ⁇ 0.5 ⁇ A 0 . More preferably A 85 > 0.15 ⁇ A 0. - AT 90 ⁇ 0.5 ⁇ A 0 .
• a 90 ⁇ 0.4 ⁇ A 0 More preferably A 90 ⁇ 0.3 ⁇ A 0 or even A 90 ⁇ 0.2 ⁇ A 0 .
• Area A 95 corresponding to the intermediate surface of material measured along an internal section plane of said body parallel to the inner face at 95% of the average thickness of said body starting from the inner face towards the impact face is greater than 3%, preferably greater than 4%, and / or less than 30% , preferably less than 20%, preferably less than 15% or even less than 10% of the area of the inner face or A 0 .
• a 100 corresponding to the material surface on the upper face (or impact face) of said body according to a section plane at the level of its average thickness is less than or equal to 20% of A 0 , preferably less than 10% of A 0 preferably less than 7% preferably less than 5% of A 0 . More preferably A 100 tends towards 0. - From a value of i greater than at least 50, the relative variation (A i + 2 -AT i ) ⁇ 100 / A i is less than 30%. - From a value of i greater than at least 75, the relative variation (A i + 2 -AT i ) ⁇ 100 / A i is less than 20%.
• E i from which the area A i decreases is greater than 4mm.
• the surface of the inner face is greater than 150 cm 2 , greater than 200cm 2 , greater than 250 cm 2 , preferably greater than 400 cm 2 , preferably greater than 500 cm 2 , or even greater than 1000 cm 2 , -
• the width or diameter of the inner face is greater than 20 cm.
• - Said body has an average thickness E m greater than 7mm, preferably greater than 10mm, preferably greater than 15 mm, preferably greater than 20 mm, - More preferably, in particular: - Said body according to the invention, on at least a portion of its face of impact, has a plurality of patterns corresponding to a local variation in the thickness of said body. This local variation in thickness can follow a function or a profile whose curve in a plane perpendicular to the section plane can exhibit one or more changes of curvature.
• - Said patterns can have the following characteristics: - The patterns are preferably protuberances or protuberances, in the form of cones, pyramids with a polygonal base, or else patterns whose profile is sinusoidal.
• the width or diameter ⁇ of the patterns of said portion is between 1 and 5 times the thickness E m , preferably between 1.5 and 4 times the thickness E m .
• the width or diameter ⁇ of the patterns of said portion is greater than or equal to 3mm and / or less than or equal to 40mm.
• the height h of the patterns is less than 0.5 times the thickness E m , preferably h is between 0.05 0.5 times the thickness E m .
• the height of the patterns of said portion is greater than or equal to 0.5mm and / or less than or equal to 5mm.
• the spacing D between two neighboring patterns corresponding to the greatest distance measured between their respective centers is less than 5 times the thickness E m , preferably less than 4 times the thickness E m , more preferably less than 3.5 times the thickness E m .
• the spacing D between two neighboring patterns corresponding to the greatest distance measured between the respective centers of two patterns is less than or equal to 40mm.
• the spacing D is adapted as a function of the caliber of the projectile vis-à-vis which the armor is intended.
• the spacing D is preferably equal to twice the caliber of the projectile plus or minus 30%. For example for a caliber of 7.62mm, D is equal to 15.2 +/- 4.6mm.
• the patterns are contiguous that is, their spacing is substantially equal to their width or diameter.
• the number of patterns per 100 cm 2 of said impact surface (exterior) is greater than 10, preferably greater than 20.
• the pattern extends by translation in one or preferably in two different directions, these two directions preferably being perpendicular to each other.
• a pattern can be more complex and composed of superimposed sub-patterns in order to deflect projectiles of different caliber, each sub-pattern being adapted to a particular threat.
• FIG. 10 or FIG. 11 illustrates an example of such an embodiment.
• the sub-patterns correspond to the same basic shape according to a different scale, for example in a homothetic manner or in a fractal structure.
• the general shape of the pattern is sinusoidal and / or comprises sub-patterns in the form of harmonics, in particular of different amplitudes or heights.
• the distribution of the patterns on the impact surface is regular, that is to say that patterns of the same morphology (height and width) are spaced at the same distance.
• said body has a flat inner face.
• the inner face and the impact face are substantially parallel.
• said body has an apparent density of less than 8 g / cm 3
• the grains of the material constituting said body have an average equivalent diameter less than 500 micrometers and a Vickers hardness greater than 3 GPa, preferably greater than 10 GPa.
• the material constituting said body comprises grains of metallic material and / or ceramic and / or cermet.
• - Said grains have a maximum equivalent diameter less than or equal to 500 micrometers, preferably less than or equal to 400 micrometers or even less than or equal to 300 micrometers.
• the maximum equivalent diameter of said grains is greater than 5 micrometers, preferably greater than 10 micrometers or even greater than 50 micrometers.
• - Said ceramic and / or cermet grains are preferably linked by a matrix, said matrix comprising or consisting of a phase of silicon nitride and / or of a phase of silicon oxynitride, said matrix representing between 5 and 40% by weight, preferably between 15 and 35% by weight, of said material constituting the ceramic body.
• - Said grains consist of a carbide or a metal boride. More preferably, they are grains of silicon carbide or of boron carbide or a mixture of these two carbides.
• the material constituting said body comprises only grains of silicon carbide, optionally with a metallic phase, preferably comprising the element silicon.
• said body preferably ceramic, has an apparent density of less than 5 g / cm 3 , preferably less than 3.2 g / cm 3 , preferably a bulk density of less than 3.0 g / cm 3 .
• the constituent grains of the material constituting said body consist essentially of SiC, preferably in alpha form.
• said material constituting said body has an open porosity greater than 5%, preferably greater than 6%, more preferably greater than 7% or even greater than 8%, and less than 14%, preferably less than 13%, of more preferably less than 12%.
• - said body has a mass to surface ratio or a surface density, measured in kg / m 2 , greater than 60 and / or preferably less than 200.
• - Said body can be a plate, a tube or another shape making it possible to produce a faceplate, a shield, a bodywork element of a vehicle, a radome, a helmet , from which the shielding element according to the invention can be chosen.
• the invention also relates to an anti-ballistic protection device comprising the shielding element according to the invention, in which: said body is provided on its inner face or opposite to the impact face with a rear dissipation coating energy, consisting of a material of lower hardness than that of the material constituting said body, in which the material constituting the back coating is chosen from PE polyethylenes, in particular ultra high density polyethylenes (UHMPE), glass fibers or carbon, aramids, metals such as aluminum, titanium or their alloys or steel.
• the ceramic body-rear coating assembly is surrounded by an envelope of a containment material.
• the confinement material constituting the envelope is chosen from glass or carbon fibers or aramids.
• FIGS. 2d, 2e and 2f relate to profiled shielding bodies according to the invention.
• - Figure 3 represents the evolution of the surface A i /AT O depending on the thickness E i / E m for different examples of realization.
• a thickness of zero (0) corresponds to the surface plane A 0 of the lower face and a thickness equal to 100 corresponds to the plane according to the maximum thickness E m .
• - Figure 4 illustrates a shielding body of which a portion of the impact surface has contiguous patterns.
• FIG. 10 represents an impact surface of two shielding elements according to the invention comprising a complex pattern made up of sub-patterns, of sinusoidal type with harmonics.
• - Figure 11 shows an impact surface of two shielding elements according to the invention comprising a complex pattern consisting of pyramid-type sub-patterns with regular steps.
• FIG. 12 shows a 3-dimensional view of a shielding body according to Example 8.
• FIG 13 shows a 3-dimensional view of a shielding body according to Example 9.
• - Figure 14 shows a 3-dimensional view of a shielding body according to example 10.
• Figure 1 shows schematically in section an example of a shielding body 10 according to the invention, in the form of a monolithic body having one face exterior 20 (or impact face) and an interior face 30 (opposite to said impact face).
• the body has a plate shape of medium thickness E m and of total length 40. The average thickness is determined as indicated below and takes into account the texturing of the outer surface on the textured portion 50.
• the textured portion (50) represents 10%, preferably more than 20%, more than 30%, more than 40%, more than 50%, or even more than 75% or even 100% of the surface. exterior of the monolithic body of the shielding element.
• the outer face 20 is textured such that the area Ai of a plane i of internal section at the intermediate thickness E i , decreases starting from the inner face 30 of area A 0 from a value of i greater than at least 50, i corresponding in percentage to the fraction of said average thickness E m to plan i.
• Area A 100 corresponding to the area of material at the level of the mean thickness E m .
• E sm is the thickness E i from which the area Ai decreases.
• the body On the portion 50 of its impact face, the body has a plurality of patterns corresponding to a local variation in the thickness of said body.
• a pattern 60 has a height h 1, a width ⁇ 1 and a center C 1 . Spacing D 1-2 between pattern 60 with center C 1 and the one next to center C 2 is also represented. Definitions: The following indications and definitions are given, in relation to the preceding description of the present invention: By mean thickness E m of said body is meant the average thickness over the portion of the body comprising the texturing.
• portion of surface is understood to mean the minimum polygonal surface surrounding a family of patterns, this surface being delimited by straight line segments tangent to the peripheral patterns.
• a family of patterns is for example made up of patterns such that the distance between two immediately neighboring patterns is less than five times the width or the diameter of the largest pattern.
• a portion can group together patterns of the same morphology and / or of the same height or width.
• the center of a pattern is the barycenter of the surface of said pattern projected perpendicularly onto the plane corresponding to the inner face of the body.
• the center is the top of the pyramid which becomes the center of the base by projection perpendicularly on the plane corresponding to the interior face.
• a plate is a geometric shape of which the area of the largest face is at least 5 times, preferably 10 times greater than its thickness.
• equivalent diameter of a grain is meant the half-sum of the greatest length of the grain and the greatest width of the grain, measured in a direction perpendicular to said greatest length.
• the term “hard material” is understood to mean a material the hardness of which is sufficiently high to justify its use in armor or armor elements.
• the maximum and average equivalent diameters are conventionally determined from observation of the microstructure of the material constituting the ceramic body, conventionally by means of images taken by SEM (scanning electron microscopy) on a section of the sintered product. It has been verified in the examples which follow that said microstructure is substantially identical, whatever the orientation of the section.
• the term “bulk density of a product” is understood to mean the ratio equal to the mass of the product divided by the volume occupied by said product. It is classically determined by the Archimedes method. The ISO 5017 standard specifies, for example, the conditions for such a measurement.
• Cermet is meant a composite material composed of a ceramic reinforcement and a metal matrix.
• matrix is understood to mean a phase which may or may not be crystallized, ensuring a substantially continuous structure between the grains. It is obtained, during the preparation of the material, typically during its firing, from the constituents of the starting charge and optionally from the constituents of the gaseous environment of this starting charge and / or from a metal molten from infiltrating into the porosity of said material during or after its firing.
• a matrix substantially surrounds the grains of the granular fraction, that is to say coats them.
• the sintering of a material is a method of manufacturing parts such as the shielding element according to the invention consisting in heating a mixture comprising a powder without leading it to melting. Under the effect of heat, the grains weld together, which forms the cohesion of the part.
• the ceramic grains are linked by the matrix. During firing or sintering, they substantially retain the shape and chemical nature which they presented in the starting charge.
• the matrix and the grains together represent 100% of the mass of the product.
• one or more metals are preferably added to the feed, which react with the nitrogenous atmosphere in order to form one or more nitrogenous crystallized phases.
• the resulting increase in volume advantageously makes it possible to fill the pores of the matrix and / or to compensate for the shrinkage caused by the sintering of the grains.
• This reactive sintering thus makes it possible to improve the mechanical strength of the sintered product.
• the reactively sintered products thus exhibit a significantly lower closed porosity than that (s) of other sintered products under similar temperature and pressure conditions. During firing, the reactively sintered products show substantially no shrinkage.
• the crystallographic composition of the material constituting the monolithic body is normally obtained by X-ray diffraction and Rietveld analysis.
• the crystallized phases, in particular the nitrogenous crystallized phases, were measured by X-ray diffraction and quantified according to the Rietveld method.
• the elemental nitrogen (N) contents in the sintered products were measured using LECO analyzers (LECO TC 436DR; LECO CS 300). The values are given in percentages by mass.
• the residual silicon in metallic form in the sintered material or after firing is normally measured according to the method known to those skilled in the art and referenced under ANSI B74-151992 (R2000).
• the Vickers hardness of grains can be measured using a standard pyramidal diamond point with a square base and an angle at the apex between faces equal to 136 °. The imprint made on the grain therefore has the shape of a square; the two diagonals d1 and d2 of this square are measured using an optical device.
• the hardness is calculated from the force applied to the diamond tip and the average d-value of d 1 and D 2 according to the following formulation: The strength and duration of the support are also normalized.
• the reference standard for ceramic or cermet materials is ASTM C1327: 03 Standard Test Method for VICKERS Indentation Hardness of Advanced Ceramics.
• the reference standard is ISO6507-1. Unless otherwise indicated, in the present description, all the percentages are percentages by weight.
• the shielding element according to the invention allows in particular protection against any type of projectiles, for example a bullet, a shell, a mine or an element projected during the detonation of explosives, such as fragments, bolts, nails.
• a first ceramic part as described above associated with another less hard and preferably ductile material, on the rear face, conventionally called “backing”, such as polyethylene fibers ( ex: Tensylon TM, Dyneema®, Spectra TM), aramid (ex: Twaron TM, Kevlar®), glass fibers, or metals such as for example steel or aluminum alloys, in the form of plates.
• backing such as polyethylene fibers (ex: Tensylon TM, Dyneema®, Spectra TM), aramid (ex: Twaron TM, Kevlar®), glass fibers, or metals such as for example steel or aluminum alloys, in the form of plates.
• Glues for example based on polyurethane or epoxy polymers, are used to bind the various elements constituting the shielding element.
• the material of the monolithic body fragments and has the main role of breaking the perforating power of the projectiles.
• the role of the rear face, associated with the material constituting said body is to consume the kinetic energy of the debris and to maintain a certain level of confinement of said body further optimized by the confinement envelope.
• the mean and maximum equivalent grain diameters were determined from observation of the microstructure of the material constituting the ceramic body, conventionally by means of images taken by scanning electron microscopy on a section of the sintered product.
• Table 1 Different shapes have been produced from molds the geometric surface of which has been modified in order to vary the profile of said surface. For each configuration, the thickness was adjusted in order to obtain a constant surface density of material whatever the examples. The different profiles are shown in Figure 2. The profile of Example 1 corresponds to a flat plate without patterns.
• the profiles of examples 2 to 7 present a sinusoidal profile whose height h varies according to the function a ⁇ cos (b ⁇ x), x being the abscissa in an axis of the cutting plane parallel to the rear face, x varying from 0 to ⁇ / b.
• the geometric characteristics of the plates thus produced are collated in table 2.
• three assemblies were made by gluing the face of the ceramic plate opposite the impact to a polycarbonate sheet using 3M 950 double-sided tape TM from 3M. Each assembly was then placed in front of thirty 10 mm thick polycarbonate sheets.
• the whole was subjected to a shot at 15 meters distance with a 7.62x51mm P80 caliber at a speed of 820m / s.
• Ballistic performance was assessed by measuring the depth of penetration of the bullet into the polycarbonate plates. An index was calculated on the basis of a reference plate set at 100. The higher the index, the higher the depth proportionally and the lower the ballistic performance.
• a 0 is the area occupied by the material on the interior surface of the plate.
• E m (in mm) is the average thickness of the body, in the sense previously described.
• E sm (in mm) is the thickness E i from which the area Ai decreases, ie the thickness from which the texturing appears in the plate, measured from the inner face of the plate (see figure 1).
• AT 75 (in mm 2 ) is the area occupied by the material alone (i.e.
• AT 95 is the area occupied by the material alone (i.e. excluding the unfilled surfaces between each pattern), along a cutting plane parallel to the inner face of the plate and located at a distance from said face internal equal to 95% of the thickness E m .
• AT 100 is the area occupied by the material alone (i.e. excluding the unfilled surfaces between each pattern), along a cutting plane parallel to the inner face of the plate and located at a distance from said face interior equal to the thickness E m .
• the E ratio sm / E m corresponds to the value of i from which the surface of an intermediate area A i is less than area A 0.
• [Table 2] * according to the invention ** comparative "NA" not applicable
• the evolution of the surface A i /AT O depending on the thickness E i / E m for different exemplary embodiments is shown in Figure 3.
• Examples according to the invention 4, 5 and 6 exhibit significantly improved ballistic performance with respect to the comparative examples in particular Example 1 (flat plate without pattern).
• Example 2 and 7 shows that the selection of the height, the width and the spacing of equal patterns so as to obtain a profile such as E sm is between 0.5 ⁇ E m and 0.95 ⁇ E m improves ballistic performance.
• Example 3 shows in particular that despite the increased spacing of larger patterns, the choice of a profile suitable according to the invention with a surface AT 95 corresponding shielding element greater than 3% of the inner surface A O (AT 95 > 0.03 A 0 ) significantly increases performance.
• the present invention is not limited to the embodiments described and shown, provided by way of examples.
• Example 8 representative of the publication US2015253114A1, shows a profile with spikes in the form of a cone, the surface A 95 less than 3% of A 0 . It appears from the results reported in Table 2 above that this profile is less efficient than that of Example 4 having a surface A 95 greater than 3% of A 0 .
• Comparative example 9 clearly shows, on the contrary, that a less “pointed” profile, that is to say such that the surface A 95 is greater than 50% of A 0 leads to a lower ballistic performance than Examples 5 and 6 of equivalent unit surface density.
• Comparative example 10 the impact surface of which is formed by truncated pyramids, shows that a surface A 100 greater than 10% of A 0 leads to a lower ballistic performance in contrast to Example 5 according to the invention.

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• General Engineering & Computer Science (AREA)
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• Aiming, Guidance, Guns With A Light Source, Armor, Camouflage, And Targets (AREA)

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