FR2950959A1 - SUPPORT DEVICE FOR LOADING PLATES - Google Patents

Abstract

A support device (100) for loading plates or substrates in a heat treatment furnace (200), the device comprising a handle and a loading portion for supporting substrates or plates within the oven. The device comprises at least first and second structural members (110, 120) of thermostructural composite material, the first member (110) forming the handle of the device while the second member (120) forms the loading portion of said device. The first and second elements (110, 120) are assembled together by a removable fastening system (160). One or more unit elements (130) may further be added to lengthen the support device.

Description

Background of the invention

The present invention relates to the field of support devices, also called shovels, used for charging batches of plates or "wafers" in heat treatment furnaces.

These devices consist of a body comprising a handle for handling the plates (transporting the plates in the oven and outside thereof) extended by a loading part which supports a lot of plates generally arranged in a basket. Known loading carriers generally consist at least in part of monolithic silicon carbide (SiC) such as the material Crystrar® Reaction Bonded (RB) from the company Saint Gobain which is a silicon-SiC material. Thanks in particular to a very low coefficient of thermal expansion and a high Young's modulus, this type of material has high thermomechanical properties, which makes it possible to reduce the stresses on the plates, and in particular those of large dimensions (up to 30 cm side or diameter). However, the loading supports made of monolithic ceramic material remain fragile in the face of both mechanical and thermal shocks (in particular during the cooling phases). Once damaged, even locally, it is all the support that must be changed. In addition, the production of monolithic ceramic material supports requires the use of a specific mold for each support size. Therefore, the number of sizes available for these supports is limited to the number of existing molds. The maximum length available today for these supports is less than 2.5 m. However, there is a need for load carriers of various sizes, particularly long lengths, in order to provide supports adapted to the many different sizes of existing furnaces.

Object and summary of the invention

The present invention aims to overcome the aforementioned disadvantages by providing a support device for loading plates in a heat treatment furnace which can be made in different sizes easily, that is to say without requiring the use of molds. specific for each size of support, and this while having a good resistance to thermomechanical stresses. These objects are achieved by means of a support device for loading plates or substrates in a heat treatment furnace, characterized in that it comprises at least first and second structural members made of thermostructural composite material, the first element forming the handle of the device while the second element forms the loading part of said device, and in that said first and second elements are assembled together by a removable fastening system. By making the support device of the invention from unitary elements, it is possible to easily form devices of various sizes. Each element is made of thermostructural composite material (ceramic matrix composite materials (CMC)) which is known for its good mechanical properties and its ability to retain these properties at high temperature. Thus, it is possible to form charging devices having lengths greater than 2.5 m which remain resistant even in the presence of significant thermomechanical stresses.

Furthermore, the elements of the support device of the invention being linked together by removable links, it is possible to repair or change only the damaged element while retaining the rest of the device.

Each element can be made of a thermostructural composite material best suited to the environmental conditions to which it must be subjected. The first element forming the handle of the device will not be exposed to temperatures as high as the second and third elements since it is not introduced into the oven. However, it undergoes significant torsional and bending stresses because it corresponds to the part of the support by which the support is manipulated when a load is present on the second and third elements.

The first element comprises a honeycomb core of refractory material and a skin made of a fibrous reinforcement of carbon fibers or ceramic, said reinforcement being densified by a matrix at least partly ceramic. According to one aspect of the invention, the matrix comprises a first carbon phase and a second silicon carbide phase. In another aspect, the skin of the first element consisting of a reinforcement is made of carbon fiber densified by a silicon carbide matrix. The second element is intended to undergo significant thermal shocks especially during removal from the oven. According to a first embodiment of the invention, the second element comprises a fibrous reinforcement obtained by three-dimensional weaving of carbon or ceramic son and densified by a matrix at least partly ceramic.

According to one aspect of the invention, the matrix comprises a first carbon phase and a second silicon carbide phase. According to another aspect of the invention, the reinforcement of the second element is made of carbon fibers and the matrix is a silicon carbide matrix.

According to another embodiment of the invention, the second element comprises a porous core of refractory material, an intermediate layer comprising a portion of the refractory material, a ceramic phase and a refractory solid filler, and a ceramic skin covering said intermediate layer. .

According to one aspect of the invention, the skin is silicon carbide.

According to yet another embodiment of the invention, the support device further comprises a third element of thermostructural composite material, this third being assembled to the second element by a removable fixing system thus forming an extension of the loading portion of the device. Other unitary elements may be added to extend the loading portion of the device of the invention. According to the invention, each added element is assembled to the adjacent element by a removable fastening system.

The third element comprises a porous core of refractory material, an intermediate layer comprising a portion of the refractory material, a ceramic phase and a refractory solid filler, and a ceramic skin covering said intermediate layer. Each removable fastening system may comprise one or more screws. formed of a carbon fiber reinforcement densified by a ceramic matrix. Each removable fastening system may further comprise one or more junction plates for connecting two adjacent elements of said device.

According to one variant, two adjacent structural elements are interconnected by overlapping the ends opposite the two structural elements, said ends each having a portion of reduced thickness having a complementary shape with respect to the other portion.

Brief description of the drawings

Other characteristics and advantages of the invention will emerge from the following description of particular embodiments of the invention, given by way of non-limiting example, with reference to the appended drawings, in which: FIG. 1 is a view schematic exploded view of a loading support device according to an embodiment of the invention; FIGS. 1A and 1B are detail views showing the fastening systems of the elements of the device of FIG. 1, FIG. 2 is a schematic view showing the support device of FIG. 1 after assembly, FIG. 3 is a schematic view. showing the loading of plates on the loading support device of FIG. 2; FIG. 4 is a schematic perspective view showing the loading of the plates in a heat treatment furnace by means of a loading support device according to FIG. 'invention. Detailed description of an embodiment

Figure 1 shows a support device or shovel 100 for loading plates or substrates in a heat treatment furnace according to one embodiment of the invention. The support device 100 comprises a first element 110 forming the handle of the support, a second element 120 and a third element 130, the second and third elements forming the loading part of the support device which is intended to be introduced into the oven heat treatment. In the embodiment presented here, the loading device comprises three unitary elements. However, the loading device according to the invention may also comprise only two elements 25 such as, for example, the first element 110 forming the handle of the device and the second element 120 which, in this case, alone forms the loading part. of the device. Conversely, the loading device according to the invention may comprise more than three unitary elements. In general, the number of unit elements is chosen as a function of the length of the loading device that is to be achieved. The first element 110 has a parallelepipedal shape and has a first end 111 adapted to cooperate with a stand 140 allowing the handling of the support device and a second end 112 adapted to be fixed to a first end 121 of the second element 120. The second end 112 has a first portion 1111 extended by a second portion of reduced thickness 1121 (Figure 1A). The second element 120 has a first end 121 adapted to be fixed on the second end 112 of the first element. More precisely, the first end 121 comprises a first portion 1210 extended by a second portion of reduced thickness 1211. The portions of reduced thickness 1121 and 1211 have an identical length so as to completely overlap during assembly of the first and second portions. second elements 110 and 120 as shown in Figure 2. In addition, the ends 112 and 121 having complementary shapes, they define, once assembled, two flat bearing surfaces for holding plates 161 and 162 disposed respectively of each side of the ends 112 and 121. The attachment of the first element 110 with the second element 120 is provided by a removable fastening system 160 comprising the plates 161 and 162 and screws 1631 and 1641. More specifically, the first element is assembled with the second element by clamping plates 161 and 162, by means of screws 1631 and 1641 passing through both ends 112 and 121 via orifices 1124 and 1224 formed respectively in these two ends. The plate 161 comprises two orifices 1610 having a thread adapted to cooperate with that of the two screws 1641 and two orifices 1611 for the other two screws 1631. Similarly, the plate 162 has two orifices 1620 having a thread capable of cooperating with the two screws 1631 and two holes 1621 passage for the other two screws 1641. The second element 120 extends from its first end 121 by a flared portion 122 which itself is extended by a portion 123 having a geometry adapted to receive a basket 180 (Figures 3 and 4).

The third element extends longitudinally between a first end 131, intended to be connected to the second end 124 of the second element 120, and a second end 132 forming the free end of the support device 100. The third element 130 has identical geometry to that of the portion 123 of the second element 120.

The first end 131 of the third element is fixed to the second end 124 of the second element 120 by a removable fastening system 170 comprising retaining plates 126, 127, 133 and 134 and screws 128 and 135. In order to maintain the continuity of formed between the portion 123 of the second element 120 and the third element 130, the plates 126, 127, 133 and 134 are respectively disposed in recesses 1270, 1280, 1330 and 1340 formed in the second and third elements 120 and 130 (FIG. ). The fixing of the third element 130 with the second element 120 is ensured by the clamping of the plates 126, 127, 133 and 134, by means of the screws 128 and 135 passing through the two ends 131 and 124 via orifices 1310 and 1240 formed respectively in these two ends. The plates 126 and 127 each comprise respectively two orifices 1260 and 1270 having a thread capable of cooperating with that of the screws 135 and two orifices 1261 and 1271 passing through the screws 128. Similarly, the plates 133 and 134 each respectively comprise two orifices. 1330 and 1340 having a thread adapted to cooperate with that of the screws 128 and two orifices 1331 and 1341 passage for the screws 135. The plates 161, 162 and the screws 1641, 1631 form a first removable fastening system 160 which allows disassembly first and second elements 110 and 120. Similarly, the plates 126, 127, 133 and 134 and the screws 128 and 135 form a second removable fastening system 170 which allows the second and third elements 120 and 130. Other systems removable fasteners can of course be considered. According to the invention, the first element 110 comprises a honeycomb core of refractory material and a skin consisting of a fibrous reinforcement of carbon or ceramic fibers, in particular SiC, the reinforcement being densified by a matrix at least partly ceramic.

In the example described here, a preform of the core of the first element 110 is machined in a block of carbon foam. Many materials can be used to make the preform of the soul. In general, any refractory material, porous or cellular, of low density and machinable can be used.

The skin reinforcement of the first element 110 is made from a fibrous texture made of carbon fibers or SiC. The fibrous textures used can be of various types such as, in particular: braid, two-dimensional fabric (2D), three-dimensional fabric (3D) obtained by 3D or multilayer weaving, knit, felt, unidirectional web (UD) of yarns or multidirectional cables or plies (nD) obtained by superposing several UD plies in different directions and bonding the UD plies together, for example by sewing, by chemical bonding agent or by needling. It is also possible to use a fibrous structure formed of several superimposed layers of fabric, braid, knit, felt, plies, cables or others, which layers are bonded together, for example by sewing, by implantation of threads or rigid elements or by needling. . The reinforcement is then densified by a matrix at least partly ceramic.

In the case of a skin made of composite material C / SiC (reinforcement of carbon fiber and SiC matrix) or SiC / SiC (SiC fiber reinforcement and SiC matrix), the densification of the reinforcement can be carried out liquid by impregnating the latter with a precursor resin of an SiC matrix such as, for example, a polycarbosilane (PCS) or polytitanocarbosilane (PTCS) or polysilazane (PSZ) type resin. In the case of a skin of CC / SiC material (carbon fiber reinforcement and matrix comprising a carbon phase, generally closer to the fibers, and a silicon carbide phase), the reinforcement is further impregnated, before the impregnation with the precursor resin of SiC, with a precursor resin of the carbon matrix such as a phenolic type resin. After impregnation, the reinforcement is disposed on the core preform and is held in shape on the latter using a holding tool. The resin or resins are then converted (polymerization / carbonization) by heat treatment. The impregnation and polymerization / carbonization operations can be repeated several times if necessary to obtain specific mechanical characteristics. The densification of the fiber preform may also be carried out, in a known manner, by gaseous means by chemical vapor infiltration of the carbon matrix (CVI). A densification combining liquid and gaseous route is sometimes used to facilitate implementation, limit costs and production cycles.

A first element 110 is thus obtained which has a relatively low mass while having a very good resistance to bending and twisting. According to one embodiment of the invention, the second element 120 comprises a fiber reinforcement densified by a matrix at least partly ceramic. The fiber reinforcement is obtained by three-dimensional weaving (3D) carried out in a known manner by means of a Jacquard weaving loom on which a bundle of warp yarns or strands has been arranged in a plurality of layers, the warp yarns being linked by weft threads.

3D weaving can be interlock weave. "Interlock" weaving is here understood to mean a weave in which each layer of weft threads binds several layers of warp yarns with all the threads of the same weft column having the same movement in the plane of the weave. .

Other known types of woven three-dimensional may be used, such as those described in WO 2006/136755 whose content is incorporated herein by reference. The fibrous reinforcement of the second member 120 may be woven from carbon fiber yarns or ceramic such as silicon carbide. As weaving of the fibrous blank varies in thickness and width, a number of warp threads are not woven, which makes it possible to define the desired contour and thickness, which is continuously variable, reinforcement. An example of an evolutive 3D weave making it possible in particular to vary the thickness of a blank of a reinforcement is described in document EP 1 526 285. The densification of the fibrous reinforcement consists in filling the porosity of the reinforcement, in all or part of the volume of it, by the constituent material of the matrix.

In the case of the production of the second element 120 made of composite material C / SiC (reinforcement of carbon fibers and SiC matrix) or SiC / SiC (SiC fiber reinforcement and SiC matrix), the densification of the reinforcement can be carried out by a liquid route by impregnating the latter with a precursor resin of an SiC matrix such as, for example, a polycarbosilane (PCS) or polytitanocarbosilane (PTCS) or polysilazane (PSZ) type resin. In the case of a skin of CC / SiC material (carbon fiber reinforcement and matrix comprising a carbon phase, generally closer to the fibers, and a silicon carbide phase), the reinforcement is further impregnated, before the impregnation with the precursor resin of SiC, with a precursor resin of the carbon matrix such as a phenolic type resin. After impregnation, the reinforcement is maintained in shape on the latter using a holding tool. The resin or resins are then converted (polymerization / carbonization) by heat treatment. The impregnation and polymerization / carbonization operations can be repeated several times if necessary to obtain specific mechanical characteristics. The densification of the reinforcement may also be carried out, in a known manner, by gaseous means by chemical vapor infiltration of the carbon matrix (CVI). A densification combining liquid and gaseous route is sometimes used to facilitate implementation, limit costs and production cycles. A second element 110 is thus obtained which has a very good resistance to bending and to thermal shocks. According to another embodiment, the second element 120 comprises a porous core made of refractory material, an intermediate layer comprising a part of the refractory material, a ceramic phase and a refractory solid filler, and a ceramic skin covering said intermediate layer. The preform of the core is machined in a thermostructural composite material starting from very low density but which has sufficient rigidity to allow its machining. The constituent material of the preform may be any type of refractory material provided that it is porous and machinable. The materials used may be, for example, carbon, silicon carbide, alumina, etc. They may be in various forms such as a foam or a composite material comprising a fiber reinforcement consolidated by a matrix, such as the composite materials C / C or C / SiC formed from a fibrous reinforcement or carbon foams or silicon carbide which has, for example, a volume ratio of porosity greater than or equal to 80%.

For example, the porous core is formed from a carbon / carbon composite material (C / C) formed of a carbon fiber reinforcement pre-densified or consolidated by a carbon matrix. This material can be machined easily, for example by milling, which makes it possible to produce complex shapes.

The reinforcement is formed of a carbon fiber felt having a relatively low fiber ratio. The fibers are linked together by a carbon matrix. Consolidation of the reinforcement may be performed by liquid impregnation thereof with a liquid composition containing a carbon precursor and then carbonizing at a controlled temperature and pressure. Alternatively, the consolidation can be performed by gas. In this case, the reinforcement is placed in an oven in which a reactive gas phase is admitted. The pressure and the temperature prevailing in the furnace and the composition of the gas phase are chosen so as to allow the diffusion of the gas phase within the porosity of the preform to form the matrix by deposition, in contact with the fibers, of a solid material resulting from a decomposition of a constituent of the gas phase or a reaction between several constituents. Whatever the method used to consolidate the fiber reinforcement, the densification must be adjusted to mechanically bind the carbon fibers at least at their intersections by the matrix while maintaining a volume ratio of porosity of the resulting material important (eg greater than or equal to at 80%). Once the machining of the core preform has been completed, a liquid coating composition is prepared comprising a refractory solid filler in the form of a powder, in particular a ceramic powder, a ceramic precursor polymer and an optional solvent for the polymer. The liquid composition preferably comprises a polymer solvent of the ceramic precursor, the quantity of solvent being chosen in particular to adjust the viscosity of the composition. The liquid composition can be applied by brush, brush or other method, for example by spray guns. It can be applied in several successive layers. After each layer, an intermediate crosslinking of the ceramic precursor polymer can be carried out. The ceramic material obtained by the liquid route can be SiC, the ceramic precursor polymer can then be chosen from PCS and PTCS, precursors of SiC or from silicones. Other ceramic materials can be obtained by liquid means such as Si3N4 silicon nitride from pyrolysed polysilazane under ammonia gas or boron nitride BN from polyborazine. The solid filler may comprise a refractory powder, in particular a ceramic powder such as a carbide powder such as SiC, a nitride or boride powder. The particle size of the powder is chosen so that the grains have an average size of preferably less than 100 microns, for example between 5 and 50 microns. The particle size is indeed chosen so that the powder grains have a sufficiently small dimension to penetrate the surface porosity of the composite material, but not too small to allow a superficial diffusion of gas in the preform during the subsequent step of chemical vapor infiltration. In this way, a good adhesion of the coating formed during this subsequent step of chemical vapor infiltration can be obtained by anchoring in the surface porosity of the material. According to an advantageous feature of the process, a mixture of ceramic powders having at least two different average particle sizes is used in order to meet these conditions. The mass amount of solid filler in the liquid composition is preferably from 0.4 to 4 times the amount by weight of ceramic precursor polymer. The preform then comprises on all its external surfaces a coating layer which at least partially closes the macroporosities of the material of the preform to a limited depth from the surface of the part. The part thus comprises a lower porosity layer in the vicinity of its surface in comparison with its initial porosity which is always present in the heart of the room and which forms the core of the structure. This intermediate coating layer is a barrier that will limit the diffusion of gases to preserve the porosity of the core and allow the formation of a surface deposit during the chemical infiltration step. After ceramization, a ceramic deposition is performed by chemical vapor infiltration on all the external surfaces of the part. This deposit makes it possible to gradually fill in the residual porosity, to consolidate the assembly formed by the phase resulting from the crosslinking of the precursor and the solid filler, and to form a uniform coating of ceramic which forms a ceramic skin on all the external surfaces of the room. This skin gives the necessary stiffness to the entire structure.

The infiltration is carried out in an oven in which is admitted a gaseous precursor of ceramics, especially SiC such as methyltrichlorosilane (MTS) giving SiC by decomposition of the MTS. The monolithic SiC thus obtained has a Young's modulus of about 420 GPa, which makes it possible to have a significant stiffness on the surface of the part.

However, other gaseous precursors of ceramics can be used depending on the desired stiffness or other properties. The nature of the reaction gas phases and the pressure and temperature conditions necessary to obtain various ceramic deposits by chemical vapor infiltration are well known per se.

The diffusion of the gaseous precursor into the preform to form the matrix by deposition, in contact with the fibers, is essentially at the level of the coating layer. Indeed, because of their small size and their reduced number at this point, the porosities are quickly clogged by the matrix deposition. As a result, the diffusion of gases deeper into the material is hampered and a deposit is formed on the surface of the workpiece. This deposit is firmly anchored in the initial porosity of the coating layer, itself anchored in the material of the core of the structure.

A laminated structure is thus obtained which comprises a core essentially made of porous C / C composite material sandwiched between an intermediate layer mainly comprising a portion of the C / C composite material whose matrix is further composed of a ceramic phase and the solid filler. , and a ceramic skin.

The second element thus obtained has a low apparent density (less than or equal to 1) while having a high stiffness imparted by the ceramic skin, which allows the second element 120 to be both light and very resistant vis-à-vis -vis the bending and thermal shock.

The third element 130 comprises a porous core of refractory material, an intermediate layer comprising a portion of the refractory material, a ceramic phase and a refractory solid filler, and a ceramic skin covering said intermediate layer. It is made in the same manner as that described above for the second element 120. The third element 130 therefore also has both a low mass and a very good resistance to the bending and thermal shock. The screws 1631, 1641, 128 and 135 used to fix the elements 110, 120 and 130 between them are preferably made of composite material C / SiC in order to limit the differential expansion with these elements. These screws are, for example, made from a fiber reinforcement obtained by three-dimensional weaving of carbon fiber son and densified by an SiC matrix (liquid and / or gaseous route). The removable fastening systems between the elements 110, 120 and 130 can be made by a "mid-wood" type fitting, that is to say by overlapping and screwing (directly in the ends of the elements or via plates of maintenance) of the two ends of the elements to be assembled as described above for the assembly of the first element 110 with the second element 120. The elements 110, 120 and 130 may also be interconnected by holding plates or junction screwed together as described above for the assembly of the second element 120 with the third element 130. As illustrated in Figure 3, once assembled, the support device 100 is adapted to be used in the same way as the support devices or shovels of the art prior. Indeed, a basket 180 in which are placed plates or wafer 190 to be treated, is deposited, via a support 183, on the second and third elements 120, 130, the basket 180 further comprising two stools 181 and 182 for depositing the basket on the oven floor. The assembly can then be manipulated to deposit the basket 180 containing the plates 190 in a furnace 200 for heat treatment (Figure 4). The second and third elements 120 and 130 having a very good resistance to bending and thermal shock, the plates 190 can be deposited in the oven and removed from it without risk of breaking the support device of the invention.

Claims (17)

REVENDICATIONS1. A support device (100) for loading plates or substrates (190) in a heat treatment furnace (200), said device comprising a handle and a loading portion for supporting the substrates or plates within the furnace, characterized in that the device comprises at least first and second structural members (110, 120) of thermostructural composite material, the first member (110) forming the handle of the device while the second member (120) forming the loading portion said device, and in that said first and second elements (110, 120) are assembled together by a removable fastening system (160). 2. Device according to claim 1, characterized in that the first element (110) comprises a core of honeycomb refractory material and a skin made of a fibrous reinforcement of carbon fiber or ceramic, said reinforcement being densified by a matrix at less partly ceramic. 3. Device according to claim 2, characterized in that the matrix comprises a first carbon phase and a second silicon carbide phase. 4. Device according to claim 2, characterized in that the skin of the first element (110) consists of a reinforcement is made of carbon fiber densified by a silicon carbide matrix. 5. Device according to any one of claims 1 to 4, characterized in that the second element (120) comprises a fibrous reinforcement obtained by three-dimensional weaving of carbon or ceramic son and densified by a matrix at least partly ceramic . 6. Device according to claim 5, characterized in that the matrix comprises a first carbon phase and a second silicon carbide phase. 7. Device according to claim 5, characterized in that the reinforcement of the second element (120) is made of carbon fibers and in that the matrix is a silicon carbide matrix. 8. Device according to any one of claims 1 to 4, characterized in that the second element (120) comprises a porous core of refractory material, an intermediate layer comprising a portion of the refractory material, a ceramic phase and a refractory solid charge , and a ceramic skin covering said intermediate layer. 9. Device according to claim 8, characterized in that the refractory material of the porous core consists of a carbon fiber reinforcement consolidated by a carbon matrix. 10. Device according to claim 8, characterized in that the skin is silicon carbide. 11. Device according to any one of claims 1 to 10, characterized in that it further comprises a third element (130) of thermostructural composite material, said third element (130) being assembled to said second element (120) by a removable fastening system (170). 12. Device according to claim 11, characterized in that the third element (130) comprises a porous core of refractory material, an intermediate layer comprising a portion of the refractory material, a ceramic phase and a refractory solid filler, and a ceramic skin. covering said intermediate layer 13. Device according to claim 12, characterized in that the refractory material of the porous core consists of a carbon fiber reinforcement consolidated by a carbon matrix. 14. Device according to claim 12, characterized in that the skin is silicon carbide. 15. Device according to any one of claims 1 to 14, characterized in that each removable fastening system (160; 170) comprises one or more screws (1631, 1641; 128, 135) formed of a fibrous reinforcement in carbon densified by a ceramic matrix. 16. Device according to claim 15, characterized in that each removable fastening system (160; 170) further comprises one or more junction plates (161, 162; 126, 127, 133, 134) for connecting two adjacent elements. said device. 17. Device according to claim 15 or 16, characterized in that at least two adjacent structural elements (110, 120) are interconnected by overlapping the ends (112, 121) facing the two structural elements, said ends (112, 121) each having a portion of reduced thickness (1121, 1211) having a complementary shape with respect to the other portion. 25