Bulkhead feedthrough

Abstract

The invention relates to a bulkhead feedthrough and to a method for manufacturing such a bulkhead feedthrough, the bulkhead feedthrough comprising a metal housing (10), at least one pin (20) made of copper or copper alloy that has a diameter of at least 1 mm and passes all the way through the housing (10), and at least one cylindrical sleeve (30) made of glass surrounding the at least one pin (20), wherein the material of the sleeve (30) is a tellurium oxide-based glass.

Description

Description Title of the invention: Partition crossing Technical Field

[0001] This disclosure relates to a bulkhead fitting and a method of manufacturing such a bulkhead fitting. Prior art

[0002] In electronics, bulkhead connectors are devices that allow one or more lines to pass through a bulkhead, such as a machine casing or a room enclosure, without compromising the seal of the bulkhead.

[0003] One of the most widely used solutions to date is described in US patent 7,364,451 B2. However, these bulkhead fittings have the disadvantage of using five different types of components for 4 different types of materials, not to mention the elastomer seal ensuring the seal between the bulkhead fitting and the bulkhead itself. These bulkhead fittings thus comprise 1) a metal pin, 2) a glass insert, 3) several ceramic inserts, 4) a metal housing and 5) a thermoplastic housing.

[0004] These bulkhead crossings thus present multiple interfaces between different materials, which makes them not very robust at high temperatures due to the differential expansion phenomena appearing at each of the interfaces.

[0005] In particular, the thermoplastic material used for part of the housing of this bulkhead fitting belongs to the PEEK (PolyEther Ether Ketone) group which has a coefficient of thermal expansion of the order of 50 ppm / °C, which represents a significant deviation from the coefficients of thermal expansion of the metallic and ceramic components of these same bulkhead fittings. i

[0006] In addition, the thermoplastic materials of the PEEK group, although among the most efficient in terms of thermal and mechanical resistance, have a glass transition temperature around 150°C and a melting temperature around 350°C.

[0007] However, in the energy industry, bulkhead fittings can be subject to extremely severe operating conditions: they can be exposed simultaneously to very high pressures, which can reach 2000 bars, and to high temperatures, which can exceed 200°C. It is therefore understandable that this known configuration is not satisfactory for such more demanding applications.

[0008] Other bulkhead feedthrough configurations are also known, notably in US Patents 7,901,247 B2 and US Patent 7,442,081 B2, but all of these configurations also include a housing element made of thermoplastic material, making them unsuitable for the intended high pressure and high temperature applications.

[0009] There is therefore a real need for a bulkhead crossing and a method of manufacturing such a bulkhead crossing which are free, at least in part, from the drawbacks inherent in the aforementioned known configurations. Statement of the invention

[0010] The present disclosure relates to a bulkhead feedthrough, comprising a metallic housing, comprising a front surface, a rear surface and a peripheral surface, configured to be engaged in a through passage of a partition, the peripheral surface of the housing comprising at least one peripheral groove configured to receive a seal intended to be crushed between the housing and the internal surface of the passage, at least one metallic pin, having a diameter greater than or equal to 1 mm, completely passing through the housing and projecting, on one side, on the front surface of the housing and, on the other side, on the rear surface of the housing, and at least one cylindrical sleeve made of glass, surrounding said at least one pin at least from the front surface to the rear surface of the housing so as to electrically insulate said at least one pin from the housing, wherein said at least one pin is made of copper or copper alloy, said pin possibly having undergone a surface treatment, wherein the material of the sleeve is a tellurium oxide-based glass having the composition consisting of, in mole percentage: - from 50 to 80% of TeO2, advantageously from 50 to 70%; - from 8 to 40% of ZnO, advantageously from 15 to 35%; - from 2 to 25% of TiO2, advantageously from 2 to 10% - from 0 to 20% of an oxide o x O y , advantageously from 2 to 10%, a being an element chosen from the group consisting of Ba, Ce, Er, Sb, Y, La and B, x being an integer equal to 1 or 2 and y an integer equal to 1, 2 or 3; - possibly ZnF2 in a content of 2 to 10%, advantageously 3 to 8%, - and unavoidable impurities, provided that ZnF2 is present when o x O y is BaO, said composition being essentially free of lead oxide, sodium oxide, potassium oxide and vanadium oxide.

[0011] In this configuration, we understand that the glass sleeve completely crosses the partition wall and therefore opens out on both sides of the partition, thus finding itself exposed to the environments, which may be very different, on each side of the partition.

[0012] Such a configuration is made possible by the glass composition selected by the inventor. Indeed, this glass composition offers both good electrical insulation between the metal pin and the housing, also metal, good mechanical and thermal resistance of the seal between the pin and the housing and, above all, good hermeticity ensuring good sealing of the bulkhead crossing, including at high pressure and high temperature. It will be noted that the pressure to which the partition wall crossing is for example an axial pressure, that is to say directed along the axis of the partition wall crossing.

[0013] In particular, ZnO allows the glass composition to have good stability. TiO2 provides excellent durability to the glass. Furthermore, the oxide o x O yadditional, optional, allows to improve the stability, wettability and / or the coefficient of thermal expansion of the glass.

[0014] The MIL-STD-883 standard of April 2016 is one of the standards explaining the method for measuring the leak rate for electronic components. According to conditions A4, the part is hermetically fixed (using a seal and suitable tightening) on ​​a vacuum chamber. It is advantageous to have the lowest possible pressure in this chamber to have the best sensitivity. Indeed, the lower the pressure, the fewer gas molecules there are in the chamber and therefore residual helium, which reduces background noise. The standard requires a pressure lower than 0.13 mbar (0.1 torr). This chamber is connected to a calibrated mass spectrometer to achieve the expected helium leak rate. Calibration must be done at each period of use, using a calibrated diffusion-type leak. The tightness of the assembly must be checked with a flat metal plate. This is done by spraying the plate with helium using a gun.If the detector does not detect helium during this check, the assembly is correct and the parts can be tested in the same way, by spraying them with helium.

[0015] A good level of hermeticity of bulkhead penetration (for example lxlO 11 mbarl / s) depends mainly on the sealing achieved at the interfaces of the conductive metal components and those made of insulating mineral materials. The inventor has thus measured that the partition penetrations obtained have a level of hermeticity less than or equal to 10 11 mbar.l / s measured according to this Mil-STD-883 standard of April 2016.

[0016] The bulkhead penetrations obtained retain this good level of airtightness after the repetitive thermal shock test defined in one of the standards Mil-DTL-26482 of February 2017, Mil-DTL-38999 of February 2015 and Mil-DTL-83723 of November 2009. This test, the methodology of which varies depending on the standards, is considered the most relevant and applied systematically for the hermetic version.

[0017] From there, since this glass composition selected by the inventor makes it possible to ensure the desired hermeticity, including when the glass sleeve completely passes through the bulkhead, the use of a thermoplastic element directly in contact with the pin over at least part of its length is no longer necessary. The inventor then took advantage of this improved glass sleeve to propose a completely metallic housing, also completely passing through the bulkhead, without any thermoplastic portion or even insert.

[0018] Thus, in the absence of thermoplastic material exposed to the severe environmental conditions of the bulkhead penetration, the mechanical (particularly in terms of rigidity and dimensional stability) and thermal resistance of the bulkhead penetration are improved.

[0019] Furthermore, the bulkhead fitting configuration defined above is particularly simple to design and manufacture insofar as it comprises only three components or types of components (apart from the seal(s) which will subsequently be added to the bulkhead fitting, before it is installed in the through-passage of the bulkhead) which are the metal housing, the metal pin and the glass sleeve or insert arranged between the housing and the pin. There is therefore no other part between the housing and the sleeve, nor any other part between the sleeve and the pin, which considerably simplifies the design and manufacture, and therefore the associated costs.Generally, the housing and sleeve are each formed from a single piece, which considerably simplifies design and manufacturing, and therefore the associated costs compared to a configuration where, for example, the sleeve and / or the housing would each be formed from several parts with possibly different materials from one part to another. In the present configuration only one type of interface is present: metal / glass. Due to a limited number of components and type of interface, the probability of manufacturing defects is reduced and the production reject rate is therefore also reduced. The risks. malfunction of such a bulkhead fitting in a harsh environment (high temperature and / or pressure) are also reduced for the same reasons. Such a bulkhead fitting does not contain any substance or chemical element likely to pollute the environment and which would be covered by European standards or directives.

[0020] Additionally, the use of an all-metal enclosure improves the bulkhead's robustness, dimensional stability, aesthetic appearance, and assembly options. It also reduces the number of interfaces between the bulkhead's various components, improving its high-temperature performance, particularly in the face of differential expansion issues.

[0021] In this respect, this glass composition has the additional advantage of having a coefficient of thermal expansion close to that of metallic materials, in particular those used for the housing and the spindle.

[0022] The coefficient of thermal expansion is measured in this presentation on a TMA from TA instrument (TMA 2940), with a ramp of 2° / min from 30 °C to 250 °C.

[0023] Advantageously, the composition of the tellurium oxide-based glass is free of Bi2O3.

[0024] More advantageously, the composition of the tellurium oxide-based glass is free of AI2O3, F and / or PbF2.

[0025] In general, unavoidable impurities in the composition of tellurium oxide glass can be chosen from lead (Pb), iron (Fe), copper (Cu), arsenic (As), antimony (Sb), calcium (Ca), carbonate (CO3), magnesium (Mg), potassium (K), sodium (Na), phosphorus (P), chlorine (Cl), silicon (Si), sulfur (S) and mixtures thereof.

[0026] The total content of unavoidable impurities is generally less than or equal to 0.1105% (1105 ppm).

[0027] For the purposes of this disclosure, the term “tellurium oxide glass” means any glass whose main component of the composition is tellurium oxide. (TeCh), advantageously of which TeCb is present in a content higher than the other components, even more advantageously in a content of at least 50% in molar percentage, even more advantageously of at least 60% in molar percentage.

[0028] More generally, within the meaning of the present disclosure, it is considered that a material is based on a given element when this element is the main element in the composition of the material, advantageously when this element is present in a content greater than the other components, even more advantageously in a content of at least 50% in molar percentage, even more advantageously of at least 60% in molar percentage.

[0029] In some embodiments, the housing has a length, measured between its front surface and its rear surface, greater than or equal to 10 mm, preferably greater than or equal to 30 mm.

[0030] In some embodiments, the peripheral surface of the housing comprises a shoulder delimiting two housing portions having different contours. This shoulder may constitute a stop when fixing the bulkhead in the bulkhead.

[0031] In some embodiments, the housing is configured to be secured within the bulkhead passage.

[0032] In some embodiments, the housing includes a fastening portion configured to cooperate with a fastening portion of the bulkhead passage, the fastening portion preferably including at least one thread.

[0033] In some embodiments, the alloy or metal of the housing has a coefficient of thermal expansion greater than 16 ppm / °C. Thus, the metal of the housing has a coefficient of thermal expansion relatively close to the other materials of the bulkhead, which reduces differential expansion phenomena.

[0034] In some embodiments, the alloy or metal of the housing is stainless steel, in particular 304L or 316L. These alloys have a coefficient of thermal expansion of the order of 17 ppm / °C.

[0035] In some embodiments, the alloy or metal of the housing is selected from the group consisting of nickel and nickel-based alloys, in particular Ni-Fe, Ni-Fe-Cr or Ni-Fe-Cr-Mo. These alloys have a coefficient of thermal expansion of the order of 13 ppm / °C.

[0036] In some embodiments, the bulkhead passage includes at least one seal installed in the at least one peripheral groove of the peripheral surface of the housing. This seal is useful for reducing the leakage rate in the bulkhead passage after the bulkhead passage is secured.

[0037] In some embodiments, the at least one seal is an O-ring.

[0038] In some embodiments, the at least one seal is an elastomeric seal.

[0039] In some embodiments, the bulkhead passage includes two gaskets, each installed in a different peripheral groove of the peripheral surface of the housing, configured to be squashed between the housing and the inner surface of the passage.

[0040] In some embodiments, said at least one pin has a diameter greater than or equal to 2 mm, preferably greater than or equal to 3 mm.

[0041] In some embodiments, the at least one pin is solid.

[0042] In some embodiments, said at least one pin has a length greater than or equal to 30 mm, preferably greater than or equal to 50 mm.

[0043] In some embodiments, the at least one pin protrudes at least 5 mm, preferably at least 10 mm, from each of the front and rear surfaces of the housing.

[0044] In some embodiments, said at least one pin comprises, at at least one of its ends, a solder barrel or a crimping barrel.

[0045] In some embodiments, the at least one pin is made of a copper-based alloy comprising beryllium, zinc, nickel, tin and / or zirconium, possibly coated. This can notably be a Cu-Be or Cu-Be-Co alloy. These alloys offer a good compromise between electrical, mechanical and thermal properties. They also have a coefficient of thermal expansion between 16 and 18 ppm / °C.

[0046] In some embodiments, at least one pin is provided with a coating comprising at least one nickel-based layer at least 1 μm thick. Such a nickel layer promotes the adhesion of the glass sleeve to the pin, which makes it possible to improve the hermeticity of the bulkhead feedthrough, in particular at high pressure and high temperature.

[0047] In some embodiments, the thickness of the nickel-based layer is between 1 and 10 μm, preferably between 4 and 8 μm.

[0048] In some embodiments, the nickel-based layer comprises phosphorus, the content of which is preferably between 6 and 9% by mass.

[0049] In some embodiments, the nickel-based layer of the coating of at least one pin is oxidized at least on the surface. This further promotes the adhesion of the glass to the pin. In particular, the glass composed of TZT or TZTC oxides has a strong affinity with the oxidized Ni-P alloy.

[0050] In some embodiments, the coating of at least one pin comprises a copper-based underlayer at least 0.1 μm thick. Preferably, this underlayer is made of pure copper, with any unavoidable impurities. This copper underlayer promotes the adhesion of the nickel layer to the pin, which further improves the hermeticity of the bulkhead feedthrough.

[0051] In some embodiments, the thickness of the copper-based underlayer is between 0.2 and 1 μm.

[0052] In some embodiments, the bulkhead feedthrough comprises several pins, possibly at least ten and even at least twenty pins, each pin having a diameter greater than or equal to 1 mm, passing right through the housing and projecting, on one side, on the front surface of the housing and, on the other side, on the rear surface of the housing, wherein a separate glass sleeve surrounds each pin at least from the front surface to the rear surface of the housing. This makes it possible to run multiple channels through a single bulkhead fitting, simplifying enclosure configuration and reducing the risk of leakage. In addition, the use of individual sleeves allows the characteristics, including thickness, of each sleeve to be adapted to the specific features of the pin it surrounds.

[0053] In some embodiments, at least two pins have different diameters.

[0054] In certain embodiments, said at least one sleeve has a thickness greater than or equal to 0.3 mm, preferably greater than or equal to 0.7 mm, for example between 0.3 and 2.0 mm, preferably between 0.7 and 1.5 mm.

[0055] In some embodiments, the bulkhead fitting comprises multiple sleeves having different thicknesses.

[0056] In some embodiments, the composition of the tellurium oxide-based glass comprises oxide o x O y selected from the group consisting of Y2O3, CeO2, Sb2O3, Er2O3, La2O3, B2O3 and BaO, in particular from the group consisting of CeO2, Sb2O3, La2O3, Y2O3 and B2O3, more particularly it is CeO2.

[0057] In certain embodiments, the coefficient of thermal expansion of the tellurium oxide-based glass composition is between 11 and 22 ppm / °C, advantageously between 12 and 16 ppm / °C. This coefficient of thermal expansion is then close to or even lower than that of the pin and the housing, which reduces the differential expansion phenomenon and therefore increases the resistance of the bulkhead feedthrough to high temperature.

[0058] In some embodiments, the tellurium oxide glass composition has a chemical durability of between 1.10' 6 and 1.10' 8 g / (cm 2 .min) determined in Soxhlet at 95°C in demineralized water and continuously renewed according to ISO 16797 standard of April 2004.

[0059] In certain embodiments, the composition of the tellurium oxide-based glass has a glass transition temperature (Tg) of less than 500°C, advantageously between 250 and 400°C, in particular between 300 and 380°C. A low glass transition temperature makes it possible to obtain a glass-metal seal at a lower temperature. However, a glass transition temperature (Tg) that is too low is not advantageous in the context of the present invention because it is appropriate to obtain a partition penetration having a temperature resistance of up to 200°C. A glass transition temperature (Tg) that is too low for the glass causes creep of the glass at these operating temperatures which can lead to loss of hermeticity. The Tg is measured using DSC (Differential scanning calorimetry): DSC setaram (DSC 131). The measurement is carried out from 20 to 580 °C with a ramp of 10 °C / min. The temperatures Tg and Tx are the onset temperatures (start of the phenomenon).

[0060] In some embodiments, the at least one sleeve is sealed between the at least one pin and the housing by glass-to-metal sealing.

[0061] In some embodiments, the bulkhead penetration has a helium leak rate of less than or equal to 10 11 mbar.l / s at 2000 bars and 200°C.

[0062] It should be noted that the bulkhead fitting only comprises a metal housing, a metal pin and a glass sleeve placed between the metal housing and the metal pin (with the exception of the aforementioned seal(s).

[0063] The present disclosure further relates to an assembly or system comprising: - a partition in which a partition passage is formed, - a partition feedthrough in accordance with the brief disclosure above and which is inserted into the partition passage. The partition feedthrough may be fixed to the partition and in particular to the partition passage by various fixing means.

[0064] The present disclosure also relates to a method of manufacturing a bulkhead feedthrough according to any one of the preceding embodiments, comprising the following successive steps: a) providing a metallic housing comprising a front surface, a rear surface and a peripheral surface; b) providing a pin, made of copper or copper alloy, optionally coated, having a diameter greater than or equal to 1 mm; c) providing a cylindrical preform of glass based on tellurium oxide having the composition as defined in any one of the preceding embodiments, the cylindrical preform having a longitudinal passage; d) inserting the pin into the longitudinal passage of the cylindrical preform and inserting the assembly formed by the pin and the cylindrical preform into a through passage of the housing; e) maintaining contact between the pin, the cylindrical preform and the housing using suitable tooling; f) heating the assembly formed by the pin, the cylindrical preform and the housing to a temperature and for a time sufficient to obtain the glass-metal seal; and g) recovering the assembly thus sealed.

[0065] By means of such a method, using glass preforms having a composition in accordance with those of the disclosure, it is possible to obtain a bulkhead feedthrough as presented above, with the advantages and technical effects indicated. In particular, the use of such a glass-metal sealing step from glass preforms makes it possible to obtain very good adhesion of the glass both on the pin and on the housing and therefore to achieve very good levels of hermeticity, including at high pressure and high temperature.

[0066] In some embodiments, the method further comprises, after step b) and before step d), the following step: b') pretreatment of the pin resulting in providing the pin with a coating comprising at least one nickel-based layer of at least 1 μm thickness. As explained previously, such a nickel layer promotes the adhesion of the glass to the pin.

[0067] In some embodiments, step b') comprises at least the following step: b2) nickel plating of the pin. This step can in particular be an auto-catalytic nickel plating step, preference for the medium-phosphorus type. Autocatalytic nickel plating is preferred to electrolytic nickel plating because it makes it easier to obtain thicker deposits.

[0068] In certain embodiments, step b2) is carried out between 75 and 100°C, preferably between 85 and 90°C, for a period of between 15 and 30 minutes, preferably between 20 and 25 minutes.

[0069] In some embodiments, step b') comprises, after step b2), the following step: b3) baking at at least 45°C for at least 3 minutes. This step allows at least part of the surface of the nickel layer to be oxidized. As explained previously, this further promotes the adhesion of the glass to the pin.

[0070] In certain embodiments, step b3) is carried out between 45 and 85°C, preferably between 55 and 75°C, for a period of between 3 and 10 minutes, preferably between 3 and 7 minutes.

[0071] In some embodiments, step b') comprises, before step b2), the following step: bl) copper plating of the pin. This step can notably be a cyanide copper plating step. As explained previously, such a copper layer promotes the adhesion of the nickel layer to the pin.

[0072] In certain embodiments, step b1) is carried out between 50 and 70°C, preferably between 55 and 65°C, for a duration of between 0.5 and 2 minutes, preferably between 0.5 and 1.5 minutes.

[0073] In some embodiments, step b1) is performed with a current density of between 0.5 and 2 A / dm 2 , preferably between 0.7 and 1.3 A / dm 2 .

[0074] In certain embodiments, step b') further comprises at least one degreasing step, preferably cathodic and / or anodic, a pickling step and / or a rinsing step.

[0075] In certain embodiments, the method further comprises, after step b) and before step d), the following step: b*) mechanical alteration of all or part of the area which will be covered by the glass sleeve resulting in providing the surface of the pin with a roughness Ra at least equal to 3.2 pm, preferably at least equal to 6.3 pm. This step, carried out for example by sandblasting, increases the roughness of the surface of the pin, which helps the glass adhere to the pin.

[0076] In certain embodiments, step b*) is carried out so as to obtain a roughness Ra of between 3.2 and 50 pm, preferably between 6.3 and 30 pm. Such roughness allows good adhesion of the glass to the pin, even when one or more coatings are deposited on the pin subsequently to the mechanical alteration step.

[0077] In certain embodiments, when the method comprises a step b') of pre-treatment of the spindle, step b*) is carried out before step b'). This avoids altering the coating(s) deposited on the spindle.

[0078] In some embodiments, the method further comprises, after step g), the following step: h) installing a seal in a peripheral groove of the peripheral surface of the housing.

[0079] In some embodiments, step b) comprises providing multiple pins, step c) comprises providing multiple preforms, and step d) comprises inserting each pin into the longitudinal passage of a separate preform and inserting the assembly into a single housing.

[0080] In certain embodiments, the temperature of step f) is between 350 and 500°C, preferably between 400 and 500°C.

[0081] In some embodiments, the duration of step f) is between 30 and 80 minutes.

[0082] The above-mentioned features and advantages, as well as others, will appear on reading the detailed description which follows, of examples of embodiments of the bulkhead crossing and the proposed manufacturing process. This detailed description refers to the accompanying drawings. Brief description of the drawings

[0083] The attached drawings are schematic and are intended primarily to illustrate the principles of the presentation.

[0084] In these drawings, from one figure to another, identical elements (or parts of elements) are identified by the same reference signs. In addition, elements (or parts of elements) belonging to different embodiments but having a similar function are identified in the figures by numerical references incremented by 100, 200, etc.

[0085] [Fig. 1] Figure 1 is a sectional view of a first example of a bulkhead crossing.

[0086] [Fig. 2] Figure 2 is a sectional view of the bulkhead fitting of Figure 1, fixed in a bulkhead.

[0087] [Fig. 3] Figure 3 is a sectional view of an alternative embodiment of the first example of partition wall crossing.

[0088] [Fig. 4] Figure 4 is a sectional view of another example of a bulkhead fitting comprising several pins. Description of the embodiments

[0089] In order to make the disclosure more concrete, examples of bulkhead fittings and methods of manufacturing such bulkhead fittings are described in detail below, with reference to the accompanying drawings. It is recalled that the invention is not limited to these examples.

[0090] Figure 1 represents, in section along a vertical plane passing through its main axis A, a first example of a partition wall crossing 1. It comprises a housing metal 10, a metal pin 20, a glass sleeve 30 and two elastomer seals 40.

[0091] The housing 10 has a shape of revolution around the main axis A. It thus comprises a front surface 11, a rear surface 12 and a peripheral surface 13. The front 11 and rear 12 surfaces are planar and orthogonal to the main axis A. The peripheral surface 13 comprises a main portion 13a, having the largest diameter, and a reduced portion 13b, having a diameter smaller than that of the main portion 13a; a radial shoulder 14 is thus formed at the junction between the main portion 13a and the reduced portion 13b. The peripheral surface 13 also comprises a projection portion 13c, of diameter smaller than that of the main portion 13a; a radial shoulder 15 is thus formed at the junction between the main portion 13a and the projection portion 13c.

[0092] The peripheral surface 13 has, at its main portion 13a, at least one peripheral groove 16, here two in number, circumferential and extending 360° along the peripheral surface 13.

[0093] The peripheral surface 13 also has, at its reduced portion 13b, a thread 17. The peripheral surface 13 further has, at its projection portion 13c, a circumferential bead 18.

[0094] The metal housing 10 further comprises a longitudinal passage 19 extending axially, along the main axis A, from the front surface 11 to the rear surface 12, the longitudinal passage 19 thus opening on each side of the bulkhead passage 1.

[0095] In this example, the housing 10 measures 3.7 cm, axially between its front surface 11 and rear surface 12; the diameter of its main portion 13a measures 1 cm.

[0096] The metal pin 20 takes the form of a straight and solid rod extending axially along the longitudinal passage 19 of the housing 10. The metal pin 20 projects from each side of the housing 10. Each end of the pin 20 can be rounded.

[0097] In this example, the diameter of the pin 20 is equal to 1.6 mm; the length of the pin is equal to 5.7 cm; it protrudes 1 cm on each side on the front surface 11 and the rear surface 12.

[0098] The glass sleeve 30 is provided around the metal pin 20 so as to electrically insulate the latter from the metal housing 10. The glass sleeve extends from the front surface 11 of the housing 10 to its rear surface 12, thus having the same length as the housing 10.

[0099] In this example, the length of the glass sleeve 30 is thus equal to 3.7 cm; its thickness is equal to 0.9 mm.

[0100] Finally, the bulkhead bushing 1 comprises two elastomeric O-rings 40, each seal 40 being installed in a peripheral groove 16 of the housing 10.

[0101] Figure 2 then represents the same bulkhead crossing 1 installed and fixed in a bulkhead 90 and forming together with the latter an assembly or system. This bulkhead 90 has a longitudinal passage 91 completely crossing the bulkhead 90 between its front surface 92 and its rear surface 93.

[0102] The passage 91 has a main portion 91a, of larger diameter, and a reduced portion 91b, of smaller diameter than that of the main portion 91a; a radial shoulder 94 is thus formed at the junction between the main portion 91a and the reduced portion 91b. The reduced portion 91b further comprises a thread 95.

[0103] The diameter of the main portion 91a of the passage 91 is adjusted to the diameter of the main portion 13a of the housing 10 and the diameter of the reduced portion 91b of the passage 91 is adjusted to the diameter of the reduced portion 13b of the housing 10. Thus, the bulkhead bushing 1 can be inserted into the passage 91 of the bulkhead by screwing the thread 17 of the housing 10 into the tapping 95 of the passage until the shoulder 14 of the housing is in abutment against the shoulder 94 of the passage 91. The sealing of the assembly is enabled by the adjustment of the diameters and the crushing of the O-rings 40 between the bottom of the peripheral grooves 16 of the housing 10 and the internal surface of the passage 91 of the bulkhead 90.

[0104] Figure 3 shows a bulkhead feedthrough 101 according to an alternative embodiment. In this alternative, the metal housing 110 and the glass sleeve 130 are unchanged. On the other hand, the metal pin 120 is configured differently.

[0105] Indeed, in this variant, the metal pin 120 comprises, at one of its ends, in this case its rear end, a welding barrel 121 instead of a simple rod.

[0106] Figure 4 shows another example of a bulkhead crossing 201 comprising several metal pins 220.

[0107] In this other example, the housing 210 is configured in a similar manner to the housing 10 of the first example, except that its diameter is larger to accommodate a greater number of pins 220. The metal housing 210 thus comprises a front surface 211, a rear surface 212 and a peripheral surface 213 comprising a peripheral groove 216, a shoulder 214 and a thread 217. On the other hand, the housing 210 comprises several longitudinal passages 219, all parallel, extending along the main axis A from the front face 211 to the rear face 212.

[0108] Each metal pin 220 is similar to the metal pin 20 of the first example, except that their diameters may vary, both relative to the first example and between them. Thus, in the example shown in Figure 4, the central pin is thicker than the peripheral pins. Although not shown, at least some pins 220 may of course include a solder cup similar to that of Figure 3.

[0109] Each metal pin 220 is further provided with an individual glass sleeve 230. Each glass sleeve 230 is similar to that of the first example, except that their thicknesses may vary, compared to the first example, but also between them. Thus, in the example shown in Figure 4, the sleeve of the central pin is thicker than the sleeves of the peripheral pins.

[0110] Examples of the manufacturing process for such bulkhead fittings will now be described.

[0111] Example 1 - In this first example, corresponding to the example shown in Figure 1, the housing 10 is made of 304L stainless steel (Fe-74%, Cr-18%, Ni-8%) having the reference UNS S30403.

[0112] Pin 20 is obtained from a 1.6 mm pin made of copper and beryllium alloy (Cu-97.5%, Be-2.0%, Co-0.5%), generally known as Cu-Be and under the reference UNS C17200. This pin is then subjected to the following pretreatment.

[0113] The spindle is first subjected to a sandblasting operation on all or part of the area which will be covered by the glass sleeve 30. This sandblasting step makes it possible to mechanically alter the surface condition of the spindle in order to obtain a roughness Ra greater than 6.3 pm. This sandblasting is followed by a double rinse.

[0114] The spindle is then subjected to cathodic degreasing, carried out at 40°C, for 2 minutes, and with a current density of 1 A / dm 2 , then anodic degreasing, carried out at 40°C, for 1 minute, and with a current density of 1 A / dm 2 These degreasing operations are followed by a double rinse.

[0115] The spindle is then subjected to METEX M629 pickling, carried out at 30°C for 1 minute. This pickling is followed by a double rinse.

[0116] The pin is then subjected to cyanide copper plating, carried out at 60°C, for 1 minute, and with a current density of 1 A / dm 2 This cyanide copper plating step provides the Cu-Be pin with a surface layer of pure copper with a thickness of between 0.2 and 1.0 pm. This step is followed by a double rinse.

[0117] The copper-plated pin is then subjected to MP nickel plating, carried out at 88°C for 22 minutes. This MP (medium phosphorus) nickel plating step, also called chemical or auto-catalytic nickel plating, provides the pin with a surface layer of nickel-phosphorus alloy that bonds favorably to the pure copper underlayer of the pin. This layer in Nickel-phosphorus alloy has a phosphorus content of between 6 and 9% by mass. This nickel-phosphorus alloy layer has a thickness of at least 6 μm. This step is followed by a double rinse.

[0118] The copper-plated and nickel-plated pin is then oven-dried at 65°C for 5 minutes. This oven-dried step allows the Ni-P alloy layer to be oxidized in a controlled manner, which will promote the subsequent adhesion of the glass of the sleeve 30.

[0119] At the end of these pre-treatment steps, a pin 20 is thus obtained, ready to be mounted in the housing 10.

[0120] A cylindrical glass preform is then provided, this cylindrical preform being intended to form the glass sleeve 30. This glass has a so-called TZT composition including tellurium oxide, zinc oxide and titanium oxide. More precisely, in this first example, the composition of the glass is as follows: TeO2-65%, ZnO-30%, TiO2-5% (in molar percentages).

[0121] The cylindrical preform is then engaged around the pin 20 and the assembly is engaged in the longitudinal passage 19 of the housing 10. Then, to produce the glass-metal seals, the metal-glass preform assembly is held in place using suitable tools. Heating is carried out in an oven, without a protected atmosphere, at 420°C for 45 minutes.

[0122] The bulkhead crossing 1 thus obtained then has mechanical resistance to a pressure of 2000 bar and thermal resistance to a temperature of 280°C.

[0123] The insulation resistance is measured using a megohmmeter at 500V DC. The insulation resistances obtained reach the detection limit of the device (20 Gohm).

[0124] Helium leak tightness is measured using a helium leak detector (ASM 142 from Adixen) according to MIL-STD-883, conditions A4. The resulting bulkhead penetration has a level of tightness expressed as a helium leak rate of less than 10 11 mbar.l / s following this measurement method defined by the Mil-STD-883 standard of April 2016.

[0125] The bulkhead penetration maintains the same level of airtightness after a so-called thermal shock test defined in the Mil-DTL-38999 standard of February 2015, which consists of subjecting the bulkhead penetration to 10 cycles of passage from cold water at 4°C to hot water at 90°C in less than 5 seconds for each passage.

[0126] In particular, comparative tests were conducted to compare the present embodiment with a similar configuration in which the pin is supplied and sealed without the pretreatment step. Among these tests, the pumping time to achieve a pressure of less than 300 mbar in the enclosure whose wall includes the bulkhead penetration to be tested was measured. In general, the glass-metal seal is considered to be good and has sufficient hermeticity when this pumping time is less than 15 seconds.

[0127] In these comparative tests, more than 30% of the bulkheads including a pin that had not been pretreated in Example 1 had pumping times greater than 15 seconds. Conversely, this percentage was reduced to practically 0 for the bulkheads whose pin had been pretreated.

[0128] Furthermore, all the materials chosen have the additional advantage of not containing any substance or chemical element subject to the restriction stipulated by the European RoHS (Restriction of Hazardous Substances) directive.

[0129] Other embodiments have been tested and are presented below. Only the differences from Example 1 are shown.

[0130] Example 2 - In a second example, the components are: - 1 case in 304L stainless steel (Fe-74%, Cr-18%, Ni-8%) referenced in UNS S30403; - 1 pin with a diameter of 1.6 mm in C17200 alloy having received the pretreatment of Example 1; and - 1 TZTC glass insulator preform with a nominal composition in molar percentages (TeO2-65%, ZnO-27%, TiO2-5%, CeO2-3%).

[0131] The bulkhead penetration is obtained by a glass / metal sealing operation at 420°C for 45 minutes, presenting a mechanical resistance to a pressure of 2000 bar and a thermal resistance to a temperature of 300°C. The bulkhead penetration obtained has a hermeticity level of less than 10 11 mbar.l / s and maintains the same airtightness after the same thermal shock test.

[0132] Example 3 - In a third example, the components are: - 1 case in 304L stainless steel (Fe-74%, Cr-18%, Ni-8%) referenced in UNS S30403; - 1 pin with a diameter of 1.6 mm in C23000 alloy having received the pretreatment of Example 1; - 1 TZTC glass insulator preform with a nominal composition in molar percentages (TeO2-65%, ZnO-27%, TiO2-5%, CeO2-3%).

[0133] The bulkhead penetration is obtained by a glass / metal sealing operation at 420°C for 45 minutes, presenting a mechanical resistance to a pressure of 2000 bar and a thermal resistance to a temperature of 300°C. The bulkhead penetration obtained has a hermeticity level of less than 10 11 mbar.l / s and maintains the same airtightness after the same thermal shock test.

[0134] Example 4 - In a fourth example, the components are: - 1 Ni-Fe alloy case called Invar with a nominal composition (Ni-36%, Fe-64%) referenced in UNS K93600; - 1 pin with a diameter of 1.6 mm in C17200 alloy having received the pretreatment of Example 1; and - 1 TZTC glass insulator preform with a nominal composition in molar percentages (TeO2-65%, ZnO-20%, TiO2-7%, CeO2-8%).

[0135] The bulkhead penetration is obtained by a glass / metal sealing process at 430°C for 60 minutes, presenting a mechanical resistance to a pressure of 2000 bar and a thermal resistance to a temperature of 300°C. The bulkhead penetration obtained has a hermeticity level of less than 10 11 mbar.l / s and maintains the same airtightness after the same thermal shock test.

[0136] Example 5 - In a fifth example, the components are: - 1 Ni-Cr-Fe alloy case with a nominal composition (Ni-76%, Cr-16%, Fe-8%) referenced in UNS N06600; - 1 pin with a diameter of 1.6 mm in C17200 alloy having received the pretreatment of Example 1; and - 1 TZTC glass insulator preform with a nominal composition in molar percentages (TeO2-60%, ZnO-20%, TiO2-10%, CeO2-10%).

[0137] The bulkhead penetration is obtained by a glass / metal sealing process at 400°C for 1 hour, presenting a mechanical resistance to a pressure of 2000 bar and a thermal resistance to a temperature of 300°C. The bulkhead penetration obtained has a hermeticity level of less than 10 11 mbar.l / s and maintains the same airtightness after the same thermal shock test.

[0138] Example 6 - In a sixth example, the components are: - 1 Ni-Cr-Fe alloy case with a nominal composition (Ni-64%, Cr-15%, Fe-5%, Mo-16%) referenced in UNS N 10276; - 1 pin with a diameter of 1.6 mm in C17200 alloy having received the pretreatment of Example 1; and - 1 TZTC glass insulator preform with a nominal composition in molar percentages (TeO2-60%, ZnO-20%, TiO2-5%, CeO2-15%).

[0139] The bulkhead penetration is obtained by a glass / metal sealing process at 400°C for 1 hour, presenting a mechanical resistance to a pressure of 2000 bar and a thermal resistance to a temperature of 300°C. The bulkhead penetration obtained has a hermeticity level of less than 10 11 mbar.l / s and maintains the same airtightness after the same thermal shock test.

[0140] Example 7 - In a seventh example, the components are: - 1 case in 316L stainless steel with nominal mass composition (Fe-72%, Cr-16%, Ni-10%, Mo-2%) referenced in UNS S31603; - 1 pin with a diameter of 4 mm in C17200 alloy having received the pretreatment of Example 1; and - 1 TZTC glass insulator preform with a nominal composition in molar percentages (TeO2-70%, ZnO-15%, TiO2-5%, CeO2-10%).

[0141] The bulkhead penetration is obtained by a glass / metal sealing operation at 420°C for 45 minutes, presenting a mechanical resistance to a pressure of 2000 bar and a thermal resistance to a temperature of 300°C. The bulkhead penetration obtained has a hermeticity level of less than 10 11 mbar.l / s and maintains the same airtightness after the same thermal shock test.

[0142] Example 8 - In an eighth example, the components are: - 1 304L stainless steel case; - 3 pins of diameter 1.6 mm in alloy having received the pretreatment of Example 1; and - 3 TZTC glass insulator preforms with a nominal composition in molar percentages (TeO2-65%, ZnO-27%, TiO2-5%, CeO2-3%).

[0143] The bulkhead feedthrough, therefore including three pins in a single housing, is obtained by a glass / metal sealing operation at 420°C for 45 minutes, presenting a mechanical resistance to a pressure of 2000 bar and a thermal resistance to a temperature of 300°C. The bulkhead feedthrough obtained has a hermeticity level of less than 10' 11 mbar.l / s and maintains the same airtightness after the same thermal shock test.

[0144] Example 9 - In a ninth example, the components are: - 1 Ni-Cr-Fe alloy case referenced in UNS N06600; - 3 pins of diameter 1.6 mm and 2 pins of diameter 3 mm, all 5 in alloy C17200 having received the pretreatment of Example 1; and - 5 TZTC glass insulator preforms with a nominal composition in molar percentages (TeO2-65%, ZnO-27%, TiO2-5%, CeO2-3%).

[0145] The bulkhead penetration, therefore including three small diameter pins and two larger diameter pins, is obtained by a glass / metal sealing operation at 420°C for 45 minutes, presenting a mechanical resistance to a pressure of 2000 bar and a thermal resistance to a temperature of 300°C. The bulkhead penetration obtained has a hermeticity level of less than 10 11 mbar.l / s and maintains the same airtightness after the same thermal shock test.

[0146] Although the present invention has been described with reference to specific exemplary embodiments, it is obvious that modifications and changes may be made to these examples without departing from the general scope of the invention as defined by the claims. In particular, individual features of the various illustrated / mentioned embodiments may be combined in additional embodiments. Therefore, the description and drawings should be considered in an illustrative rather than restrictive sense.

[0147] It is also obvious that all the characteristics described with reference to a method are transposable, alone or in combination, to a device, and conversely, all the characteristics described with reference to a device are transposable, alone or in combination, to a method.

Claims

Claims

1. Bulkhead feedthrough, comprising a metal housing (10), comprising a front surface (11), a rear surface (12) and a peripheral surface (13), configured to be engaged in a through passage (91) of a partition (90), the peripheral surface (13) of the housing (10) comprising at least one peripheral groove (16) configured to receive a seal (40) intended to be crushed between the housing (10) and the internal surface of the passage (91), at least one metal pin (20), having a diameter greater than or equal to 1 mm, completely passing through the housing (10) and projecting, on one side, on the front surface (11) of the housing (10) and, on the other side, on the rear surface (12) of the housing (10), and at least one cylindrical sleeve (30) made of glass,surrounding said at least one pin (20) at least from the front surface (11) to the rear surface (12) of the housing (10) so as to electrically insulate said at least one pin (20) from the housing (10), wherein said at least one pin (20) is made of copper or copper alloy, optionally coated, wherein the material of the sleeve (30) is a tellurium oxide-based glass having the composition consisting of, in molar percentage:, - from 50 to 80% of TeO2, advantageously from 50 to 70%; - from 8 to 40% of ZnO, advantageously from 15 to 35%; - from 2 to 25% of TiO2, advantageously from 2 to 10% - from 0 to 20% of an oxide o x O y , advantageously from 2 to 10%, a being an element chosen from the group consisting of Ba, Ce, Er, Sb, Y, La and B, x being an integer equal to 1 or 2 and y an integer equal to 1, 2 or 3; - possibly ZnF2 in a content of 2 to 10%, advantageously 3 to 8%, - and unavoidable impurities, provided that ZnF2 is present when oxOy is BaO, said composition being essentially free of lead oxide, sodium oxide, potassium oxide and vanadium oxide.

2. A bulkhead passage according to claim 1, wherein the peripheral surface (13) of the housing (10) comprises a shoulder (14) delimiting two housing portions (13a, 13b) having different contours, and wherein the housing (10) comprises a fixing portion (17) configured to cooperate with a fixing portion (95) of the passage (91) of the partition (90), the fixing portion preferably comprising at least one thread (17).

3. A bulkhead fitting according to claim 1 or 2, wherein the alloy or metal of the housing (10) is selected from the group consisting of stainless steel, nickel and nickel-based alloys.

4. A bulkhead bushing according to any one of claims 1 to 3, wherein said at least one pin (20) has a length greater than or equal to 30 mm, preferably greater than or equal to 50 mm, and wherein said at least one pin (20) projects at least 5 mm, preferably at least 10 mm, on each of the front (11) and rear (12) surfaces of the housing (10).

5. Bulkhead fitting according to any one of claims 1 to 4, wherein said at least one pin (120) comprises, at at least one of its ends, a welding barrel (121) or a crimping barrel.

6. A bulkhead feedthrough according to any one of claims 1 to 5, wherein at least one pin (20) is provided with a coating comprising at least one copper-based underlayer of at least 0.1 pm thickness, and one nickel-based layer of at least 1 pm thickness.

7. A bulkhead feedthrough according to any one of claims 1 to 6, comprising a plurality of pins (220), each pin (220) having a diameter greater than or equal to 1 mm, passing right through part the housing (210) and projecting, on one side, on the front surface (211) of the housing (210) and, on the other side, on the rear surface (212) of the housing (210), and in which a separate glass sleeve (230) surrounds each pin (220) at least from the front surface (211) to the rear surface (212) of the housing (210).

8. A bulkhead according to any one of claims 1 to 7, wherein the composition of the tellurium oxide glass comprises tellurium oxide x O y selected from the group consisting of Y2O3, CeO2, Sb2O3, Er2O3, La2O3, B2O3 and BaO, in particular from the group consisting of CeO2, Sb2O3, La2O3, Y2O3 and B2O3, more particularly it is CeO2.

9. A bulkhead fitting according to any one of claims 1 to 8, wherein the bulkhead fitting has a helium leak rate of less than or equal to 10' 11 mbar.l / s at 2000 bars and 200°C.

10. A bulkhead fitting according to any one of claims 1 to 9, wherein the bulkhead fitting comprises only a metal housing, a metal pin and a glass sleeve disposed between the metal housing and the metal pin.

11. Set comprising: - a partition (90) in which a partition passage (91) is formed, - a bulkhead passage (1) according to any one of claims 1 to 10 and which is inserted into the bulkhead passage (91).

12. Method for manufacturing a bulkhead feedthrough according to any one of claims 1 to 10, comprising the following successive steps: a) providing a metallic housing (10), comprising a front surface (11), a rear surface (12) and a peripheral surface (13); b) providing a pin (20), made of copper or copper alloy, optionally coated, having a diameter greater than or equal to 1 mm; c) providing a cylindrical glass preform based on tellurium oxide having the composition as defined in any one of claims 1 to 8, the cylindrical preform having a longitudinal passage; d) inserting the pin (20) into the longitudinal passage of the cylindrical preform and inserting the assembly formed by the pin (20) and the cylindrical preform into a through passage (19) of the housing (10); e) maintaining contact between the pin (20), the cylindrical preform and the housing (10) using suitable tooling; f) heating the assembly formed by the pin (20), the cylindrical preform and the housing (10) to a temperature and for a time sufficient to obtain the glass-metal seal; and g) recovering the assembly (1) thus sealed.

13. Method according to claim 12, further comprising, after step b) and before step d), the following step: b') pretreatment of the pin (20) resulting in providing the pin (20) with a coating comprising at least one nickel-based layer of at least 1 μm thickness, this step b 7 ) comprising at least the following step: b2) nickel plating of the pin.

14. The method of claim 13, wherein step b 7 ) further comprises, prior to step b2) of nickel plating the pin, a step bl) of copper plating the pin.

15. The method of claim 13, wherein step b 7 ) includes, after step b2), the following step: b3) steaming at at least 45°C for at least 3 minutes.

16. A method according to any one of claims 12 to 18, characterized in that the method comprises: 15, further comprising, after step b) and before step d), the following step: b*) mechanical alteration of all or part of the area which will be covered by the glass sleeve resulting in providing the surface of the pin with a roughness Ra at least equal to 3.2 pm, preferably at least equal to 6.3 pm.

17. A method according to claims 13 and 16, wherein step b*) of mechanical alteration is carried out before step b 7 ) pretreatment of the spindle (20).

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