Method of manufacturing a composite object, method of using a composite object, beam pipe module

Abstract

The disclosure relates to methods of manufacturing a composite object. A disclosed method comprises positioning a stack (2) of layers against a non-planar moulding surface (4) of a moulding device and curing the stack of layers to form a composite object (8). Before the curing, the stack comprises a set of fibre-matrix layers (21) and a set of isotropic layers (22).

Description

[0001] METHOD OF MANUFACTURING A COMPOSITE OBJECT, METHOD OF USING A COMPOSITE OBJECT, BEAM PIPE MODULE

[0002] The present disclosure relates to manufacturing composite objects and is particularly applicable in the context of vacuum vessels or electromagnetic shielding applications and / or in other applications where thin walls are desirable and / or sealing or shielding is required.

[0003] Vacuum vessels having thin walls are useful in various applications. In beam pipes for particle accelerators, for example, it is desirable to maintain extreme high vacuum (XHV) in a beam pipe region where particle collisions take place while at the same time positioning detectors, which cannot normally be in the XHV region, as close as possible to where the particle collisions take place. The thinner the wall of a vacuum vessel separating the detector from the XHV region, the nearer the detector can be positioned to the colliding particles.

[0004] Various challenges limit how thin a vacuum vessel wall can be made while still providing sufficient XHC performance and mechanical strength. Machining limitations may mean that walls need to be manufactured with nominal thicknesses that are significantly higher than is theoretically required for strength to account for manufacturing inaccuracies. The range of materials that can be used may be limited to those that are XHC compatible. For example, materials that outgas significantly will not be suitable for use in the XHC environment.

[0005] A further challenge in the context of beam pipes is that it is desirable to minimise loss of signal due to particles emitted from particle collisions in the beam pipe interacting with material forming walls of the vacuum vessel. Using materials with low atomic number (Z), such as beryllium, can reduce such losses but materials with low Z can be hazardous, difficult to machine, and / or unsuitable for use in an XHC environment for other reasons (e.g., due to outgassing etc.).

[0006] It is an object of the present disclosure to provide methods that at least partially address the issues mentioned above or other issues.

[0007] According to an aspect, there is provided a method of manufacturing a composite object, comprising: positioning a stack of layers against a non-planar moulding surface of a moulding device; and curing the stack of layers to form a composite object having a surface conforming to a shape of the moulding surface, wherein, before the curing of the stack of layers: the stack of layers comprises a set of fibre-matrix layers, the set of fibre-matrix layers containing a single fibre-matrix layer or a plurality of fibre-matrix layers, each fibre-matrix layer comprising reinforcing fibres and a matrix material; and the stack of layers comprises a set of isotropic layers, the set of isotropic layers containing a single isotropic layer or a plurality of isotropic layers each isotropic layer being formed from isotropic material, wherein: one or more of the isotropic layers comprises a hermetic film; and / or one or more of the isotropic layers comprises a metallic sheet.

[0008] Thus, a composite object is formed by a process involving one or more isotropic layers, which may comprise metallic sheets for example, being incorporated directly into a lamination process along with fibre-matrix layers. The result has been found to provide a structure that combines properties of the two different types of layer in a more optimal way than is possible using other approaches. In particular, it is possible to provide composite objects having advantages associated with typical laminated composites, such as the ability to form objects with extremely low, precisely defined, and uniform thicknesses and / or low Z number, together with advantages associated with isotropic layers, such as hermetic sealing and, in the case of isotropic layers comprising metallic sheets, electromagnetic shielding. Integrating metallic sheets into the lamination process provides increased precision, reliability and robustness in comparison to alternative approaches involving coating or adhering metallic material to pre-formed composite objects. For example, coating methods will typically have to use thicker layers of metal and composite material to achieve satisfactory performance, which may mean the composite object has to be thicker than necessary.

[0009] In an embodiment, each of one or more the isotropic layers has a thickness in the range of about 1 micron to about 100 microns. In the case where the isotropic layers comprise metallic sheets, the metallic sheets may have a thickness in the range of about 1 micron to about 100 microns. The method is particularly advantageous for forming extremely thin materials. Relative to alternative approaches for forming objects of similar dimensions using non-composite materials, such as by machining or etching of metals, the present approach typically allows thickness to be controlled with greater precision, which allows manufacturing tolerances to be tightened. A nominal thickness can thus be chosen that is closer to the minimum thickness required for the object to achieve a required mechanical strength, without risk of manufacturing deviations causing mechanical failure of the manufactured object.

[0010] In an embodiment, material from at least one of the set of isotropic layers forms a hermetic layer of the composite object after the curing of the stack of layers. The hermetic layer may provide a seal between a portion of the composite object formed by material from the fibre-matrix layers and a region on an opposite side of the hermetic layer. The hermetic layer may form an outer layer of the composite object, wherein “outer" refers to the hermetic layer facing an outside region outside of the solid structure defining the composite object, such as a vacuum region or a gaseous region. The outside region may be an enclosed region surrounded by the composite object or an exterior region outside of any enclosed region. Arranging the layers in the stack to form a hermetic layer in this manner provides a composite object in which the reinforcing fibres and matrix material can be sealed away from a region on the opposite side of the hermetic layer. This configuration is particularly valuable, for example, where the composite object is used as part of a vacuum vessel, where the hermetic layer would face into the vacuum region and the sealing action would prevent outgassing from the reinforcing fibres and matrix material compromising the quality of the vacuum. The inventors have demonstrated that such arrangements are compatible with XHV levels of vacuum.

[0011] In an embodiment, two of the hermetic layers are provided on opposite sides of the composite object, thereby sealing the material from the fibre-matrix layers from an environment outside of the composite object on both sides of the composite object in a thickness direction of the composite object for at least a portion of the composite object. In comparison to where a hermetic layer is provided on only one side of the composite object, providing hermetic layers on both sides of the composite object provided increased flexibility for positioning the composite object in a vacuum region. For example, a larger portion or substantially all of the composite object may be positioned in the vacuum region. The hermetic layers may encapsulate all of the material from the fibre-matrix layers, allowing all of the composite object to be placed inside the vacuum region.

[0012] In an embodiment, the stack comprises a first portion comprising an exposed metallic sheet with openings and a second portion peripherally supporting the first portion and comprising one or more fibre-matrix layers encapsulated by isotropic layers on opposite sides of the stack. The first portion provides electromagnetic shielding while reducing an amount of material acting as a barrier between opposite sides of the composite object in the first portion, which may be advantageous in the context of a beam pipe module for example, where reducing barrier material may reduce signal loss due to absorption when detecting entities propagating through the composite object. The second portion provides structural support while the encapsulation ensures that the fibre-matrix layers do not compromise any required high vacuum.

[0013] In an embodiment, the set of isotropic layers comprises a plurality of the isotropic layers and at least a subset of the isotropic layers are spaced apart from each other by one or more of the fibre-matrix layers. Providing multiple metallic sheets interleaved between layers of reinforcing fibre and matrix provides a composite object having effective electromagnetic shielding. Providing multiple sheets helps to ensures complete shielding even for complex geometries. Optionally, different portions of the stack comprise different numbers and / or thicknesses of isotropic layers in a thickness direction of the stack. Thus a balance between electromagnetic shielding and thickness may be made to vary for different portions of the composite object. The amount of metallic sheets throughout the composite object can be varied flexibly in a range of ways to provide bespoke electromagnetic performance. For example, a first portion of the composite object may be configured to have maximum thinness at the expense of lower electromagnetic shielding by having fewer, thinner or no metallic sheets in the thickness direction of the corresponding portion of the stack while a second portion of the composite object may be configured to have higher electromagnetic shielding at the expense of greater thickness by having more and / or thicker metallic sheets in the thickness direction of the corresponding portion of the stack.

[0014] In an embodiment, the isotropic layers comprise a primary metallic sheet and one or more secondary metallic sheets; each of the secondary metallic sheets is: separable from the primary metallic sheet in the stack prior to the curing of the stack; and shaped and positioned to fuse with the primary metallic sheet during the curing of the stack to form a metallic layer having greater coverage than the primary metallic sheet. Thus, distinct separable metallic sheets are provided in the stack to extend coverage of a metallic layer formed by the metallic sheets. The secondary metallic sheets may for example fill gaps that would otherwise have been left by the primary metallic sheet. This approach may be particularly useful for geometries that cannot be covered by simple folding of a single sheet of material.

[0015] According to an aspect, there is provided a beam pipe module comprising: a composite object obtainable by the method of any of embodiments of the disclosure; and one or more detectors configured to detect entities propagating through the composite object to the detector, wherein: the composite object comprises a hermetic layer formed from material from at least one of the set of isotropic layers; the hermetic layer is configured to provide a seal between a portion of the composite object formed by material from the fibre-matrix layers and a region on an opposite side of the hermetic layer; and the one or more detectors are positioned on the same side of the hermetic layer as the portion of the composite object formed by material from the fibre-matrix layers.

[0016] The method of forming the composite object is particularly advantageous in the context of a beam pipe module because of the ability to precisely and reliably achieve low thickness, mechanical robustness and / or compatibility with high vacuum requirements. The composite object can be safely formed of low Z materials, thereby minimizing unwanted absorption of entities passing through the composite object. The thinness also contributes to reducing absorption. The thinness also makes it possible to reduce a separation r between detectors and the origin of entities of interest, which reduces signal losses dependent on the separation r (which typically vary as r3).

[0017] Arrangements of the disclosure will be further described by way of example only with reference to the accompanying drawings.

[0018] Figure 1 schematically depicts a framework of a method for manufacturing a composite object.

[0019] Figure 2 is a schematic side sectional view of a portion of a moulding device with a stack of layers positioned against a moulding surface, the stack of layers comprising a metallic sheet as an outer layer.

[0020] Figure 3 depicts the arrangement of Figure 2 after curing.

[0021] Figure 4 depicts the arrangement of Figure 3 after detachment of the moulding device.

[0022] Figure 5 is a schematic side sectional view of a portion of a moulding device with a stack of layers positioned against a moulding surface, the stack of layers comprising metallic sheets interleaved with fibre-matrix layers.

[0023] Figure 6 is schematic top view of a primary metallic sheet on a moulding device showing example positioning of a secondary metallic sheet to cover a gap and / or seam.

[0024] Figure 7 is a side sectional view along a radial direction of a cylindrical portion of a stack having a first portion comprising an exposed metallic sheet with openings and second portions peripherally supporting the first portion and comprising fibre-matrix layers encapsulated by isotropic layers on radially inner and outer sides of the stack.

[0025] Figure 8 is a side sectional view of a composite object formed from a stack in which different portions of the stack comprise different numbers of isotropic layers in a thickness direction of the stack.

[0026] Figure 9 schematically depicts a portion of an example vacuum vessel comprising a beam pipe module.

[0027] Figures 10 and 11 are perspective and side views showing a composite object comprising a stack of layers.

[0028] Figure 12 is a side sectional view of a moulding device before the stack of Figures 10 and 11 is formed around it.

[0029] Figure 13 is a side sectional view, stretched vertically to exaggerate layer thicknesses, of the illustrative region of the moulding device of Figure 12 after application of a single fibre-matrix layer onto a selected portion of the moulding device that extends into the illustrative region (from the left in the orientation of the figure).

[0030] Figure 14 is a side sectional view of the arrangement of Figure 13 after a subsequent step comprising applying a single isotropic layer onto a different selected portion of the moulding device that extends into the illustrative region (from the right in the orientation of the figure).

[0031] Figure 15 is a top view of a portion of the moulding device after application of a self- adhesive strip of copper foil along a seam formed in the step corresponding to Figure 14.

[0032] Figure 16 is a side sectional view of the illustrative region after a further isotropic layer has been applied that forms a conductive link piece at one end of the seam covered in the step of Figure 15.

[0033] Figure 17 is a top view of the portion of the moulding device shown in Figure 15 showing application of a conductive link piece at the other end of the seam.

[0034] Figures 18-25 are side sectional views of the illustrative region showing further fibrematrix layers being progressively added to the stack in a region extending to the right of a discontinuity over different distances.

[0035] Figures 26 and 27 depict an additional layer being applied to form an aluminium insert. Figure 26 depicts an end portion of the moulding device. Figure 27 depicts a magnified version of the portion within the box shown in Figure 26 with the vertical scale magnified to exaggerate layer thicknesses for visibility.

[0036] Referring initially to Figures 1 and 2, the present disclosure provides a method of manufacturing a composite object.

[0037] Step SI comprises positioning a stack 2 of layers against a non-planar moulding surface 4 of a moulding device 6. The layers are typically thin layers, defined as layers have a local thickness that is everywhere much smaller than dimensions of the layer perpendicular to the thickness. The non-planar moulding surface 4 may have any shape apart from a single flat plane. The moulding surface 4 may comprise portions that are smoothly curved and / or portions that are locally planar. In the example of Figure 2, the portion of the moulding surface shown in the figure contains sub-portions that are locally planar but which are oriented differently relative to each other to define a surface that is non-planar overall.

[0038] Referring to Figure 3, step S2 comprises curing the stack 2 to form a composite object 8 having a surface conforming to a shape of the moulding surface 4. The curing comprises applying a temperature above room temperature to the stack 2 and / or applying a pressure above atmospheric pressure to the stack 2. Typically, a temperature above 80 degrees C, for example between about 120 and 140 degrees C, may be applied. Typically, a pressure above 500kPa, for example between about 600 and 800 kPa, may be applied.

[0039] Referring to Figure 4, step S3 comprises detaching the moulding device from composite object 8.

[0040] Before the curing of the stack of layers (step S2), the stack of layers comprises a set of fibre-matrix layers 21 and a set of isotropic layers 22. The set of fibre-matrix layers 21 contains a single fibre-matrix layer 21 or a plurality of fibre-matrix layers 21. The set of isotropic layers 22 contains a single isotropic layer 22 or a plurality of isotropic layers 22.

[0041] In the example shown in Figure 2, the set of fibre-matrix layers 21 comprises six fibre-matrix layers 21 and the set of isotropic layers 22 comprises a single isotropic layer 22. In the example shown in Figure 5, the set of fibre-matrix layers 21 comprises four fibrematrix layers 21 and the set of isotropic layers 22 comprises three isotropic layers 22. The numbers of fibre-matrix layers 21 and isotropic layers 22 in the sets may be different (higher or lower) in other embodiments.

[0042] Each of the fibre-matrix layers 21 comprises reinforcing fibres and a matrix material. The curing of step S2 may be configured to cure the matrix material to cause the matrix material to become rigid and hold the reinforcing fibres together. The matrix material may comprise any material suitable for holding the reinforcing fibres together. The matrix material may comprise a resin or a plastic impregnated with a resin. The resin may comprise a polymer. The resin may comprise a thermosetting material. Curing of the thermosetting material may cause cross-linking between polymer units and provide high rigidity and the ability to withstand high temperatures without losing rigidity. Examples of thermosetting materials that can be used with methods of the disclosure include: polyester, vinyl ester, epoxy, phenolic resin, cyanate ester, polyurethane, polyimide, and bismaleimide. Alternatively, the resin may comprise a thermoplastic material. Examples of thermoplastic materials that can used with methods of the disclosure include: polyamide, polyethylene, polypropylene, PEEK, thermoplastic polyimide, thermoplastic polyurethane, polycarbonate, PLA, polysulfone, polyphenylene sulphide.

[0043] The reinforcing fibres may, for example, comprise one or more of the following: carbon fibres; aramid fibres; glass fibres; quartz fibres; ceramic fibres; metallic fibres; hemp fibres; sisal fibres; and flax fibres.

[0044] Each isotropic layer 22 is formed from (e.g., consists of) isotropic material. One or more of the isotropic layers may comprise a hermetic film, such as a polyimide film. Additionally or alternatively, one or more of the isotropic layers may comprise a metallic sheet. The metallic sheet may be a continuous metallic sheet or, as described below, may comprise one or more openings. The metallic sheet may have a range of different compositions. The metallic sheet may for example comprise, consist essentially of, or consist of, copper or aluminium. The method may comprise processing the metallic sheet to improve adhesion properties. The processing may include plasma coating or an abrasive / surface roughening procedure (e.g., sandblasting) for example.

[0045] In some embodiments, each of one or more the isotropic layers 22 (e.g., metallic sheets) has a thickness in the range of about 1 micron to about 100 microns, optionally less than about 50 microns, optionally less than about 25 microns. In some embodiments, as exemplified in Figures 1 to 4, material from at least one of the set of isotropic layers 22 forms a hermetic layer 82 of the composite object 8 after the curing of the stack 2 of layers. The hermetic layer 82 may form an exposed surface of the composite object, which may be referred to as an outer layer. The hermetic layer 82 may be a metallic outer layer. In the particular example shown, the material is provided by the single isotropic layer 22 in the stack 2 of Figure 2. This single isotropic layer 22 is incorporated into the composite object 8 during the curing of step S2. The hermetic layer 82 is configured to provide a seal between a portion 81 of the composite object 8 formed by material from the fibre-matrix layers 21 and a region 30 (Figure 4) on an opposite side of the hermetic layer 82. The hermetic layer 82 is thus incorporated into the composite object as an intrinsic part of the lamination process but while keeping all material from the fibre-matrix layers 21 on one side of the hermetic layer 82. The region 30 can thus be protected from potentially problematic properties of the material from the fibre-matrix layers 21, such as outgassing from cured matrix material, while the composite body as a whole can benefit from other properties of the material from the fibre-matrix layers 21 such as precise thickness control, lightness, low Z number, high mechanical strength, etc.

[0046] As mentioned above, the fibre-matrix and isotropic layers 21, 22 are typically relatively thin, such that the method is particularly beneficial for forming composite objects 8 having thin walls. For example, the method may be particularly beneficial for forming a composite object 8 in which a minimum thickness of the composite object 8 in a direction perpendicular to an outer surface 84 of the composite object 8 is less than 1000 microns, optionally less than about 500 microns, optionally less than about 250 microns. Furthermore, the method is capable of forming composite objects that are uniformly thin with high accuracy. In some embodiments, over at least 90%, preferably over at least 95%, preferably over at least 99%, preferably over substantially all, of an outer surface 84 of the composite object 8, a thickness of the composite object 8 in a direction perpendicular to the outer surface 84 varies by less than about 100 microns, optionally by less than about 50 microns.

[0047] The method also allows the hermetic layer 82 (e.g., metallic outer layer) to be extremely thin and uniformly formed. In an embodiment, over at least 90%, preferably over at least 95%, preferably over at least 99%, preferably over substantially all, of an outer surface 84 of the hermetic layer 82, a thickness of the hermetic layer 82 in a direction perpendicular to the hermetic layer 82 is in the range of about 1 micron to about 100 micron, optionally less than about 50 microns, optionally less than about 25 microns. In an embodiment, over at least 90%, preferably over at least 95%, preferably over at least 99%, preferably over substantially all, of an outer surface 84 of the hermetic layer 82, a thickness of the hermetic layer 82 in a direction perpendicular to the metallic outer layer 82 varies by less than about 1 micron.

[0048] In some embodiments, as exemplified in Figure 5, the set of isotropic layers 22 comprises a plurality of the isotropic layers 22. In the example shown, the set comprises three isotropic layers 22. At least a subset of the isotropic layers 22 are spaced apart from each other by one or more of the fibre-matrix layers 21. In the example shown, a single fibrematrix layer 21 is provided between each pair of adjacent isotropic layers 22. In other embodiments, more than one, for example two, three, four or five, fibre- matrix layers 21 may be provided between each of one or more pairs of isotropic layers 22. In some embodiments, a plurality of the isotropic layers 22 may additionally or alternatively be positioned in the stack to contact each other directly, with no intervening isotropic layer 22 at least in a region of contact.

[0049] In an embodiment, the isotropic layers 22 comprise a primary metallic sheet and one or more secondary metallic sheets. Each of the secondary metallic sheets may be separable from the primary metallic sheet in the stack 2 prior to the curing of the stack 2. Each of the secondary metallic sheets may be shaped and positioned to fuse with the primary metallic sheet during the curing of the stack 2 to form a hermetic layer 82 (e.g., metallic layer) having greater coverage than the primary metallic sheet.

[0050] The extension of coverage may comprise filling one or more gaps 86 in coverage when the primary metallic sheet is folded to conform with the shape of the moulding surface 4 prior to curing. Alternatively or additionally, each of one or more of the secondary metallic sheets 222 may be shaped and positioned to overlap with a seam of the primary metallic sheet 221 when the primary metallic sheet 221 is folded to conform with the shape of the moulding surface 4 prior to curing. An example configuration is shown schematically in Figure 6, which is a schematic top view of a primary metallic sheet 221 on a moulding device showing example positioning of a rectangular secondary metallic sheet 222 (indicated by the broken line box). In this case a relevant portion of the moulding surface 4 may be substantially frustoconical with an axis running parallel to the plane of the page. The primary metallic sheet 221 is wrapped around the radial outside of the moulding surface 4 in such a way as to come into contact with itself in a seam region 41 while leaving a longitudinal oriented gap in in a gap region 42. The secondary metallic sheet 222 in the shape and position shown covers the seam region 41 and the gap region 42 and thereby ensures that the metallic layer 82 formed by curing step S2 spans integrally across where the seam region 41 and gap region 42 were located, thus ensuring structural integrity and continuity in the properties provided by the metallic layer 82, Including for example sealing between one side of the metallic layer 82 and the other and / or providing suitable electromagnetic shielding properties.

[0051] Figure 7 shows an example of an embodiment of a stack 2 configured to produce a composite object 8 in which two of the two of the hermetic layers 82 are provided on opposite sides of the composite object 8. The hermetic layers 82 seal the material from the fibre-matrix layers 21 from an environment outside of the composite object 8 on both sides of the composite object 8 in a thickness direction of the composite object 8 (a vertical direction in the orientation of Figure 7) for at least a portion of the composite object 8. Optionally, the hermetic layers 82 may encapsulate all of the material from the fibre-matrix layers 21, thereby allowing all of the composite object to be positioned within a high vacuum region.

[0052] In the example of Figure 7, the stack 2 comprises a first portion 2A comprising an exposed metallic sheet 22A (a portion of an isotropic layer) with openings 22B. The openings 22B pass through the metallic sheet 22A. The stack 2 is configured such that the composite object 8 formed by the curing will have corresponding openings that pass through the composite object from one side of the composite object to the other side of the composite object. The exposed metallic sheet 22A may be exposed on both sides of the metallic sheet 22A and / or otherwise configured such that the composite object 8 comprises a portion having an exposed metallic surface on both sides of the composite object 8 with openings that pass through the composite object 8 from one side of the composite object to the other side of the composite object. Thus, material from the first portion 2A forms an exposed metallic surface on both sides of the composite object 8 with openings (corresponding to the openings 22B) that pass through the composite object 8 from one side of the composite object 8 to the other side of the composite object 8. The stack 2 further comprises two second portions 2B. The second portions 2B peripherally support the first portion 2A. The second portions 2B each comprise one or more fibre-matrix layers 21. The fibre-matrix layers 21 are encapsulated by isotropic layers 22 on opposite sides (above and below in the orientation shown in Figure 7) of the stack 2.

[0053] Figure 8 depicts an example of an embodiment in which different portions of the stack 2 comprise different numbers of isotropic layers 22 in a thickness direction of the stack 2. Each of the isotropic layers 22 may comprise a metallic sheet. In other embodiments (not shown), different portions of the stack 2 may alternatively or additionally comprise different thicknesses of isotropic layers 22. A result of providing the different numbers and / or thicknesses of isotropic layers 22 may be that a total thickness of material from the isotropic layers 22 in the composite object 8 is different in different portions of the composite object 8. In the example of Figure 8, the stack 2 comprises a left portion 2L, a right portion 2R, a top portion 2T and a bottom portion 2B. The right portion 2R, top portion 2T and bottom portion 2B each have four isotropic layers 22 in a thickness direction (e.g., vertical for the top and bottom portions and horizontal for the right portions). The left portion 2L has only two isotropic layers 22 and is thinner than the other portions. The left portion 2L may provide lower electromagnetic shielding but has the advantage of being thinner. The other portions may provide higher electromagnetic shielding but are thicker.

[0054] Composite objects 8 formed using methods of the present disclosure may in principle be used in a wide range of situations. The method is, however, particularly beneficial in the context of providing an arrangement that allows devices such as detectors to be positioned close to a vacuum region without being in the vacuum region (although the detectors themselves may be in another vacuum region, such as a vacuum region held at a lower level of vacuum).

[0055] In accordance with the above, a method of using a composite object 8 in a vacuum vessel 90 is provided. An example scenario is illustrated schematically in Figure 9, which depicts a portion of an example vacuum vessel 90. The structure is highly simplified relative to a typical practical implementation. It is understood that the vacuum vessel 90 extends above and below the portion shown in Figure 9. Any suitable combination of pumping devices, conduits, controllers and construction details for a vacuum vessel and for establishing, maintaining and monitoring a vacuum level in a vacuum region 92 of the vacuum vessel 90 may be used. In the particular example shown, the vacuum vessel 90 is configured as part of a beam pipe for high energy particle physics experimentation. An axis 94 of the beam pipe is indicated schematically by the broken line. Particles propagate along the axis 94 and undergo collisions.

[0056] A portion of the vacuum vessel 90 is defined by a beam pipe module 96. The beam pipe module comprises a composite object 8 (or a plurality of composite objects 8). The or each composite object 8 is obtainable or obtained using any of the methods of the present disclosure. The composite object 8 is arranged in the vacuum vessel 90 such that material from at least one of the set of isotropic layers 22 forms a hermetic layer 82 (see Figure 4), such as a metallic outer layer, having an outer surface 84 facing into the vacuum region 92 of the vacuum vessel 90. The hermetic layer 82 provides a seal between the vacuum region 92 and a portion 81 of the composite object 8 formed by material from the fibre-matrix layers 21 on a side of the hermetic layer 82 opposite to the vacuum region 92.

[0057] The beam pipe module 96 further comprises one or more detectors 92. The or each detector 92 is positioned on the side of the hermetic layer 82 opposite to the vacuum region 92. The detectors 92 are thus positioned on the same side of the hermetic layer 82 as the portion 81 of the composite object 8 formed by material from the fibre-matrix layers 21. The or each detector 92 is configured to detect entities propagating through the composite object 8 to the detector 92 from the vacuum region 92. The entities thus propagate through both the portion 81 of the composite object 8 formed by material from the fibre-matrix layers 21 and through the hermetic layer 82. The entities may comprise any detectable sub-atomic particle expected to result from particle collisions occurring in the portion of the beam pipe passing through the beam pipe module 96.

[0058] The vacuum region 92 may typically be maintained at extreme high vacuum (XHV). A chamber 98 containing the detectors 92 may also be held at a sub -atmospheric pressure but will typically be held at a lower vacuum level (i.e., higher pressure) than the vacuum region 92 due to the reduced needs for high vacuum in this area and the challenges of achieving high vacuum in regions containing structure such as detectors and their connections etc.

[0059] DETAILED EXAMPLE

[0060] The following section provides example implementation details in the context of applying methods of the present disclosure to form a composite object 8 formed from a stack 2 containing fibre-matrix layers 21 comprising carbon fibres in a resin matrix and isotropic layers 22 comprising copper sheets.

[0061] Figures 10 and 11 are perspective and side views showing a final composite object 8 comprising a stack 2 of layers. Metallic end inserts 7 are provided at axial opposite ends of the composite object 8. A sequence of example steps of building up the stack 2 starting from a clean moulding device 6 will now be described with reference to Figure 12 onwards, focussing (arbitrarily) on an illustrative region 100 indicated by a broken line box in Figures 11 and 12.

[0062] Figure 12 is a side sectional view of the moulding device 6 before the stack 2 is formed around it. A non-planar moulding surface 4 is thus exposed at this stage. A release compound may be applied to the moulding surface 4 at this stage. Such a release compound may, however, be omitted, for example where methods of mould release are used where such a release would not be relevant, such as where melt out or wash out tooling is used.

[0063] Figure 13 is a side sectional view, stretched vertically to exaggerate layer thicknesses, of the illustrative region 100 of the moulding device 6 of Figure 12 after application of a single fibre-matrix layer 21 onto a selected portion of the moulding device 6 that extends into the illustrative region 100 (from the left in the orientation of the figure). The fibre-matrix layer 21 is wrapped once around the circumference of the moulding device 6. The fibrematrix layer 21 comprises carbon fibres in a resin matrix. The carbon fibres are oriented unidirectionally at 90 degrees to the longitudinal axis of the moulding device.

[0064] Figure 14 is a side sectional view of the arrangement of Figure 13 after a subsequent step comprising applying a single isotropic layer 22 onto a different selected portion of the moulding device 6 that extends into the illustrative region 100 (from the right in the orientation of the figure). The isotropic layer 22 applied in the step shown in Figure 14 does not overlap with the fibre-matrix layer 21 applied in the step shown in Figure 13. The isotropic layer 22 is wrapped once around the circumference of the moulding device 6. The isotropic layer 22 consists of non-self-adhesive copper foil. The isotropic layer 22 applied in this step is an example of the primary metallic sheet 221 discussed earlier, and labelled as such in Figure 15 discussed below.

[0065] In a subsequent step, as depicted in Figure 15, a self-adhesive strip of copper foil, forming a secondary metallic sheet 222, is positioned over a seam formed by wrapping the primary metallic sheet 221 around the circumference of the moulding device 6. As discussed earlier, the secondary metallic sheet 221 ensures that a hermetic layer 82, which in this case is a metallic layer, formed by curing the stack 2 later on will spans integrally across where the seam was located, thus ensuring structural integrity and continuity in the properties provided by the hermetic layer 82, including for example sealing between one side of the hermetic layer 82 and the other and / or providing suitable electromagnetic shielding properties. The seam is 20mm wide and 488mm long in the particular example shown. The illustrative region 100 corresponds to a portion near the leftmost edge of the arrangement shown in Figure 15.

[0066] In a subsequent step, a debulking operation is applied by applying vacuum to a bag provided outside of the part formed stack 2 (causing the bag to press down uniformly on the stack).

[0067] In a subsequent step, as depicted in Figure 16, which is a side sectional view of the illustrative region 100, a further isotropic layer 22 is applied. The further isotropic layer 22 comprises copper foil and spans over the top of portions of a previously positioned fibrematrix layer 21 (on the left) and a previously positioned isotropic layer 22 (on the right). The isotropic layer 22 deposited in this step provides a link between the region to the left of the discontinuity 102 and the region to the right of the discontinuity and is aligned along the seam shown in Figure 15. This isotropic layer 22 may be referred to as a conductive link piece and is important for impedance and RF performance in this particular example. Although not shown in Figure 16, the link should extend longitudinally on each side of the discontinuity by at least about 4.9-5.0mm.

[0068] In a subsequent step, as depicted in Figure 17, a further isotropic layer 22 equivalent to that positioned in the step described above with reference to Figure 16 is provided at the opposite end of the seam, thereby providing a further conductive link piece.

[0069] In subsequent steps, as depicted in Figures 18-25, further fibre-matrix layers 21 are progressively added to the stack 2 in a region extending to the right of the discontinuity 102 over different distances. In each case a small portion enters the illustrative region 100 and is depicted in the figures. In the configuration of Figures 18 and 19, the respective latest fibrematrix layers 21 extend longitudinally 20mm away from the discontinuity 102. In the configuration of Figures 20 and 21, the latest fibre-matrix layer 21 extends longitudinally 15mm away from the discontinuity 102. In the configuration of Figures 22 and 23, the respective latest fibre-matrix layers 21 extend longitudinally 10mm away from the discontinuity 102. In the configuration of Figures 24 and 25, the respective latest fibre-matrix layers 21 extend longitudinally 5mm away from the discontinuity 102. Thus, the resulting outer surface of the stack 2 in the region of the discontinuity 102 is thus made to taper smoothly. Each of the fibre-matrix layers 21 applied comprises carbon fibres in a resin matrix. The carbon fibres are oriented in each case unidirectionally at 90 degrees to the longitudinal axis of the moulding device.

[0070] In a subsequent step, a debulking operation is applied by applying vacuum to a bag provided outside of the part formed stack 2 (causing the bag to press down uniformly on the stack).

[0071] In a subsequent step, as depicted in Figures 26 and 27, an additional layer 104 may be applied to form an aluminium insert. Figure 26 depicts an end portion of the moulding device 6. Figure 27 depicts a magnified version of the portion within box 106 shown in Figure 26 with the vertical scale magnified to exaggerate layer thicknesses for visibility. A release agent may be applied to mould facing surfaces of the additional layer 104. Carbon facing surfaces may be keyed (roughened), for example using 1000 grit.

[0072] In a subsequent step, a debulking operation is applied by applying vacuum to a bag provided outside of the part formed stack 2 (causing the bag to press down uniformly on the stack).

[0073] Further steps may be carried out to apply further fibre-matrix layers 21 and to perform further debulking operations before the stack 2 and moulding device 6 are transferred to a curing device such as an autoclave for curing the stack 2 to form the composite object 8. In an example implementation, the temperature may be increased by 5 degrees C per minute to 121 degrees C and held at that temperature at a pressure of 100 psi (690kPa) for 240 minutes. The temperature may then be ramped down at a rate of 10 degrees C per minute. Various other configurations are possible. For example, a cure could alternatively be performed at 135 degrees C and lOOpsi (690kPa) for 240 minutes.

[0074] Cross reference to related application

[0075] This application claims priority from United Kingdom patent application number 2400341.0 filed on 10 January 2024, the contents of which are hereby incorporated by reference.

Claims

CLAIMS1. A method of manufacturing a composite object, comprising: positioning a stack of layers against a non-planar moulding surface of a moulding device; and curing the stack of layers to form a composite object having a surface conforming to a shape of the moulding surface, wherein, before the curing of the stack of layers: the stack of layers comprises a set of fibre-matrix layers, the set of fibre-matrix layers containing a single fibre-matrix layer or a plurality of fibre-matrix layers, each fibre-matrix layer comprising reinforcing fibres and a matrix material; and the stack of layers comprises a set of isotropic layers, the set of isotropic layers containing a single isotropic layer or a plurality of isotropic layers, each isotropic layer being formed from isotropic material, wherein: one or more of the isotropic layers comprises a hermetic film; and / or one or more of the isotropic layers comprises a metallic sheet.

2. The method of claim 1, wherein the metallic sheet comprises copper or aluminium and / or the method comprises processing the metallic sheet to improve adhesion properties, the processing optionally including plasma coating or an abrasive / surface roughening procedure.

3. The method of claim 1 or 2, wherein the formed composite object is such that material from at least one of the set of isotropic layers forms a hermetic layer having an exposed surface and is capable of providing a seal between a vacuum region adjacent to the exposed surface and a portion of the composite object formed by material from the fibre-matrix layers on a side of the hermetic layer opposite to the vacuum region, the seal being optionally compatible with maintaining the vacuum region at extreme high vacuum.

4. The method of any preceding claim, wherein the reinforcing fibres comprise one or more of: carbon fibres; aramid fibres; glass fibres; quartz fibres; ceramic fibres; metallic fibres; hemp fibres; sisal fibres; and flax fibres.

5. The method of any preceding claim, wherein the matrix material comprises a resin or a plastic impregnated with a resin.

6. The method of any preceding claim, wherein the curing comprises applying one or more of the following to the stack of layers: a temperature above room temperature, such as above 80 degrees C; and a pressure above atmospheric pressure, such as above 500kPa.

7. The method of any preceding claim, wherein each of one or more the isotropic layers has a thickness in the range of about 1 micron to about 100 microns.

8. The method of any preceding claim, wherein material from at least one of the set of isotropic layers forms a hermetic layer of the composite object after the curing of the stack of layers.

9. The method of claim 8, wherein the hermetic layer is configured to provide a seal between a portion of the composite object formed by material from the fibre-matrix layers and a region on an opposite side of the hermetic layer.

10. The method of claim 9, wherein the hermetic layer forms an exposed surface of the composite object.

11. The method of any of claims 8 to 10, wherein over at least 90% of a surface of the hermetic layer, a thickness of the hermetic layer in a direction perpendicular to the hermetic layer is in the range of about 1 micron to about 100 micron.

12. The method of any of claims 8 to 11, wherein over at least 90% of a surface of the hermetic layer, a thickness of the hermetic layer in a direction perpendicular to the hermetic layer varies by less than about 1 micron.

13. The method of any of claims 8 to 12, wherein two of the hermetic layers are providedon opposite sides of the composite object, thereby sealing the material from the fibre-matrix layers from an environment outside of the composite object on both sides of the composite object in a thickness direction of the composite object for at least a portion of the composite object.

14. The method of any preceding claim, wherein a minimum thickness of the composite object in a direction perpendicular to an outer surface of the composite object is less than 1000 micron.

15. The method of any preceding claim, wherein over at least 90% of an outer surface of the composite object, a thickness of the composite object in a direction perpendicular to the outer surface varies by less than 100 about microns.

16. The method of any preceding claim, wherein the set of isotropic layers comprises a plurality of the isotropic layers.

17. The method of claim 16, wherein at least a subset of the isotropic layers are spaced apart from each other by one or more of the fibre-matrix layers.

18. The method of any preceding claim, wherein different portions of the stack comprise different numbers and / or thicknesses of isotropic layers in a thickness direction of the stack.

19. The method of any of claims 16 to 18, wherein: the isotropic layers comprise a primary metallic sheet and one or more secondary metallic sheets; each of the secondary metallic sheets is: separable from the primary metallic sheet in the stack prior to the curing of the stack; and shaped and positioned to fuse with the primary metallic sheet during the curing of the stack to form a metallic layer having greater coverage than the primary metallic sheet.

20. The method of claim 19, wherein the extension of coverage comprises filling one or more gaps in coverage when the primary metallic sheet is folded to conform with the shape of the moulding surface prior to curing.

21. The method of claim 19 or 20, wherein each of one or more of the secondary metallic sheets is shaped and positioned to overlap with a seam of the primary metallic sheet when the primary metallic sheet is folded to conform with the shape of the moulding surface prior to curing.

22. The method of any preceding claim, wherein the stack comprises a first portion comprising an exposed metallic sheet with openings and a second portion peripherally supporting the first portion and comprising one or more fibre-matrix layers encapsulated by isotropic layers on opposite sides of the stack, the stack being optionally configured such that material from the first portion forms an exposed metallic surface on both sides of the composite object with openings that pass through the composite object from one side of the composite object to the other side of the composite object.

23. A method of using a composite object in a vacuum vessel, comprising: providing a composite object obtainable by the method of any of claims 1 to 22 or manufacturing a composite object using the method of any of claims 1 to 22; and arranging the composite object in a vacuum vessel such that material from at least one of the set of isotropic layers forms a hermetic layer having a surface facing into a vacuum region of the vacuum vessel, the hermetic layer providing a seal between the vacuum region and a portion of the composite object formed by material from the fibre-matrix layers on a side of the hermetic layer opposite to the vacuum region, the vacuum region being optionally maintained at extreme high vacuum.

24. The method of claim 23, further comprising using a detector on the side of the hermetic layer opposite to the vacuum region to detect entities propagating through the composite object to the detector from the vacuum region.

25. A beam pipe module comprising: a composite object obtainable by the method of any of claims 1 to 22; and one or more detectors configured to detect entities propagating through the composite object to the detector, wherein: the composite object comprises a hermetic layer formed from material from at least one of the set of isotropic layers; the hermetic layer is configured to provide a seal between a portion of the composite object formed by material from the fibre-matrix layers and a region on an opposite side of the hermetic layer; and the one or more detectors are positioned on the same side of the hermetic layer as the portion of the composite object formed by material from the fibre-matrix layers.

26. A composite object obtainable by the method of any of claims 1 to 22.

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