Method for infiltrating a body with an si-containing material; friction or sliding body made of c / sic or sic / sic producible by the method; use of a body having a portion made of pbn in an LSI method

Abstract

The present invention relates to a method for the liquid infiltration of a porous body with a liquid, Si-containing material, for example an LSI method, comprising: providing a first auxiliary body (10) having a portion (18) which comprises pyrolytic boron nitride, pBN, (20) (S101); providing an Si-containing material (12) on the portion (18) which comprises pBN (20) in order to heat the Si-containing material (12) on the portion (18) comprising pBN (20) to a temperature at which the Si-containing material (12) is liquefied (S102), and providing a porous body (14) to be infiltrated, such that the Si-containing material (12) infiltrates (S103) the porous body (14) to be infiltrated in liquid form, after the Si-containing material has been liquefied on the portion (18) which comprises pBN (20).

Description

[0001] Method for infiltrating a body with a Si-containing material; friction or sliding body made of SiC or SiC / SiC producible by the method; use of a body having a section made of PBN in an LSI process

[0002] The present invention relates to a method for liquid infiltration of a porous body with a liquid, Si-containing material, a friction or sliding body producible / produced by the method and a use of an auxiliary body having a section made of pyrolytic boron nitride (pBN) in an LS l process for liquefying Si on the section made of pBN.

[0003] Various processes for liquid infiltration of porous bodies with a liquid, Si-containing material, such as the LSI process (liquid silicon infiltration process or liquid siliconizing process), can be used, for example, in the production of C / SiC (carbon fiber reinforced silicon carbide) and SiC / SiC (silicon carbide fiber reinforced silicon carbide). The C / SiC bodies or SiC / SiC bodies produced in this way can be used, for example, as friction or sliding bodies, for example, as brake discs in high-performance sports cars. Si-containing materials can be used, for example, as silicon or silicon-containing alloys (such as aluminum-silicon alloys or iron-silicon alloys).

[0004] In the various processes for liquid infiltration of porous bodies with a liquid, Si-containing material, such as the LSI process, a graphite crucible is usually used which is / is coated with boron nitride paint (BN paint). The BN paint contains hexagonal BN as a BN component. For example, DE 19749462 C1 and EP 0134254 A1 disclose a graphite tub and a graphite plate, respectively, which are / are coated with a suspension containing BN powder and water, and CN 110483086 A discloses a crucible which contains BN. In each case, this is hexagonal BN, particularly because pBN is not usually used in powder form and due to the ease of manufacture and good availability of hexagonal BN compared to pBN. At least one so-calledA wick made of a porous material (e.g. C / C) and a Si-containing material (e.g. Si powder) are added. A porous body to be infiltrated (also called the workpiece; e.g. made of C / C) is then placed on the wick. The whole thing is then heated up (usually in a furnace) until the Si-containing material melts (e.g. to a temperature of 1420°C or more) and the liquid Si-containing material first infiltrates the pores of the wick and then the pores of the workpiece (e.g. is sucked into them, e.g. through capillary action). If the porous body to be infiltrated is made of C / C and the Si-containing material is Si, a reaction to form C / SiC takes place during and / or after infiltration. The graphite crucible used cannot be cleaned or reused without extensive cleaning.reprocessing because the BN ink cannot fully protect the graphite and the liquid, Si-containing material (e.g. Si) reacts with the graphite. In addition, such a graphite crucible can usually only be used two to three times before it needs to be replaced because cleaning or reprocessing is often no longer possible. Thus, the known processes for liquid infiltration of porous bodies with a liquid, Si-containing material, such as the LSI process, can require a large amount of material and / or personnel, which can, for example, increase the costs of manufacturing infiltrated workpieces. Crucibles made of pBN are known in principle, but have not yet been used in processes for liquid infiltration of porous bodies with a liquid, Si-containing material, such as the LSI process.

[0005] The inventors of the present invention have surprisingly found that by providing or using a (first) auxiliary body with a section comprising pBN (such as a crucible made of pBN) in processes for liquid infiltration of a porous body with a liquid, Si-containing material (for example LSI processes), for example, cleaning or reprocessing of the (first) auxiliary body can be simplified and / or the (first) auxiliary body can be reused, for example, without complex cleaning or reprocessing and / or the (first) auxiliary body can be reused, for example, more frequently (for example up to ten times or more) than the bodies known from the prior art. In this respect, the inventors of the present invention have surprisingly found that providing or using a (first) auxiliary body with a section comprising pBN (such as a crucible made of pBN) in processes for liquid infiltration of a porous body with a liquid, Si-containing material (for example LSI processes).Using a (first) auxiliary body with a section comprising pBN in processes for liquid infiltration of a porous body with a liquid, Si-containing material (for example, LSI processes) offers advantages that justify the (possibly) higher costs and the (possibly) more complex production of the (first) auxiliary body.

[0006] It can be considered an object of the present invention to provide a method for liquid infiltration of a porous body with a liquid, Si-containing material, for example an LSI method, with which material and / or personnel costs can be reduced.

[0007] Alternatively or additionally, it may be considered an object of the present invention to provide a method for liquid infiltration of a porous body with a liquid, Si-containing material, for example an LSI method, with which the costs for the production of bodies infiltrated with a Si-containing material (for example Si) can be reduced.

[0008] Alternatively or additionally, it may be considered an object of the present invention to provide an improved and / or efficient and / or economical method for liquid infiltration of a porous body with a liquid, Si-containing material, for example an improved and / or efficient and / or economical LSI method.

[0009] Alternatively or additionally, it can be considered an object of the present invention to provide an auxiliary body with which an LSI method can be carried out efficiently and / or economically and / or with reduced material and / or personnel expenditure.

[0010] Alternatively or additionally, it can be considered an object of the present invention to provide a friction or sliding body, for example a brake disc, which can be manufactured (or can be manufactured) with reduced material and / or personnel expenditure and / or efficiently and / or economically and / or whose manufacturing costs can be reduced.

[0011] To this end, the present invention provides a method for liquid infiltration of a porous body with a liquid, Si-containing material (for example, LSI method) according to claim 1, a use of an auxiliary body according to claim 16, and a friction or sliding body according to claim 18. Further advantageous embodiments of the present invention are described in the dependent claims.

[0012] According to a first aspect of the invention, a method for liquid infiltration of a porous body with a liquid, Si-containing material (for example, an LSI method) may, for example, comprise: providing (for example, at least) a first auxiliary body having (for example, at least) a portion comprising pyrolytic boron nitride (pBN); providing (for example, at least) a Si-containing material on the portion comprising pBN in order to heat the Si-containing material on the portion comprising pBN to a temperature at which the Si-containing material is liquefied; and providing (for example, at least) a porous body to be infiltrated such that the Si-containing material, after being liquefied on the portion comprising pBN, infiltrates the porous body to be infiltrated in liquid form. pBN is produced in particular by means of CVD processes and can have a high purity.

[0013] By providing the first auxiliary body with the section comprising pBN, and by providing, heating, and liquefying the Si-containing material on this section, a reaction of the Si-containing material with the first auxiliary body can be at least reduced. This can, for example, simplify cleaning or reprocessing of the first auxiliary body and / or the first auxiliary body can, for example, be reused without complex cleaning or reprocessing. Furthermore, the first auxiliary body can, for example, be reused more frequently (for example up to ten times or more) than the known graphite crucibles (see above). Furthermore, for example, a wick used in the known methods (see above) can be dispensed with, since a sufficiently good surface quality of the infiltrated body can be achieved even without it, in particular its underside (or(i.e., its side facing the first auxiliary body) and / or a sufficiently uniform infiltration of the porous body to be infiltrated is enabled. Thus, for example, material and / or personnel expenditure can be reduced and / or the costs for producing bodies infiltrated with a Si-containing material can be reduced.

[0014] The first auxiliary body can, for example, be a body coated with pBN, for example, a graphite crucible coated with pBN. The pBN layer of a body coated with pBN can, for example, have a thickness such that a reaction of the Si-containing material with the material of the coated body is at least reduced and / or prevented. A pBN layer can, for example, be applied to a body to be coated using a CVD process. The first auxiliary body can, for example, consist (at least substantially) of pBN.

[0015] The method may, for example, comprise heating the Si-containing material provided on the section comprising pBN to a temperature at which the Si-containing material is liquefied. The method may, for example, comprise liquefying the Si-containing material provided on the section comprising pBN (for example, by heating, for example, by heating the Si-containing material provided on the section comprising pBN). The method may, for example, comprise infiltrating the provided porous body to be infiltrated with the liquefied Si-containing material (for example, with the liquefied Si-containing material provided on the section comprising pBN).

[0016] The method may, for example, further comprise: providing (for example at least) a second auxiliary body made of a porous material, such that the Si-containing material, after its liquefaction on the section comprising pBN, infiltrates the second auxiliary body in liquid form; wherein the porous body to be infiltrated (for example at least in sections) can be provided such that the Si-containing material, which has infiltrated the second auxiliary body, infiltrates the porous body to be infiltrated (for example at least in sections) from the second auxiliary body in liquid form. As a result, for example, the porous body to be infiltrated can be infiltrated particularly uniformly with the Si-containing material. In this respect, for example, by carrying out a single

[0017] Infiltration processes can achieve a sufficiently good infiltration result, and performing multiple infiltration processes on the porous body to be infiltrated can be eliminated. This can, for example, reduce material and / or personnel expenditure and / or reduce the costs for producing bodies infiltrated with a Si-containing material.

[0018] The method may, for example, comprise infiltrating the provided second auxiliary body with the liquefied, Si-containing material (for example, with the liquefied Si-containing material provided on the section comprising pBN). The method may, for example, comprise infiltrating the provided porous body to be infiltrated with the liquefied, Si-containing material (for example, from within the second auxiliary body, for example, with the (liquefied) Si-containing material that has infiltrated the second auxiliary body).

[0019] The Si-containing material can, for example, be Si with a purity of 97% by weight or more, for example 97.5% by weight or more, for example 98% by weight or more, for example 98.5% by weight or more, for example 99% by weight or more. The Si-containing material can, for example, be a Si-containing alloy, for example an Al-Si alloy or an Fe-Si alloy. The Si-containing material can, for example, have 70% by weight or more, for example 80% by weight or more, for example 90% by weight or more, for example 95% by weight or more, Si. In particular, if the Si-containing material is Si with a purity of 97% by weight or more, cleaning or reprocessing of the first auxiliary body can be particularly simple and / or the first auxiliary body can, for example, be particularly easy to reuse without complex cleaning or reprocessing.

[0020] The porous body to be infiltrated can, for example, comprise or consist (at least essentially) of a C / C material (C / C: carbon fiber reinforced carbon) and / or a SiC / C material (SiC / C: silicon carbide fiber reinforced carbon).

[0021] In particular, if the porous body to be infiltrated comprises or consists (at least substantially) of a C / C material or a SiC / C material and if the Si-containing material is Si with a purity of 97% by weight or more, for example, a C / SiC body or a SiC / SiC body can be produced with reduced material and / or personnel expenditure and / or efficiently and / or economically and / or their production costs can be reduced, for example.

[0022] The second auxiliary body may, for example, comprise or consist (at least substantially) of a porous carbon, for example a C / C material.

[0023] The porous body to be infiltrated and the second auxiliary body can, for example, comprise the same materials or consist (at least substantially) of the same materials. This allows, for example, the porous body to be infiltrated to be infiltrated particularly uniformly with the Si-containing material. In this respect, a sufficiently good infiltration result can be achieved, for example, by performing a single infiltration process, and performing multiple infiltration processes on the porous body to be infiltrated can be eliminated. Thus, for example, material and / or personnel expenditure can be reduced and / or the costs for producing bodies infiltrated with a Si-containing material can be reduced.

[0024] The Si-containing material can, for example, be exposed to a temperature in the range of 1410°C to 1650°C and a pressure in the range of 0.01 mbar to 100 mbar for a period of 5 minutes to 180 minutes. This can, for example, achieve uniform infiltration of the porous body to be infiltrated with the Si-containing material and / or make cleaning or reprocessing of the first auxiliary body particularly simple and / or allow the first auxiliary body to be reused particularly easily without complex cleaning or reprocessing.

[0025] The Si-containing material can, for example, be exposed to a temperature in the range of 1500°C to 1800°C and a pressure in the range of 10 mbar to ambient pressure (e.g., 1013 mbar) for a period of 5 minutes to 180 minutes. This can, for example, achieve uniform infiltration of the porous body to be infiltrated with the Si-containing material and / or facilitate cleaning or decontamination.

[0026] Reprocessing of the first auxiliary body can be simplified and / or the first auxiliary body can be reused without complex cleaning or reprocessing.

[0027] The Si-containing material can, for example, be exposed to a temperature in the range of 1550°C to 1750°C and a pressure in the range of 10 mbar to ambient pressure (e.g., 1013 mbar) in an Ar atmosphere for a period of 5 to 45 minutes. This can, for example, achieve particularly uniform infiltration of the porous body to be infiltrated with the Si-containing material and / or cleaning or reprocessing of the first auxiliary body can be particularly simple and / or the first auxiliary body can be particularly easily reused without complex cleaning or reprocessing. The process can, for example, be carried out in a furnace (e.g., a vacuum furnace). A furnace (e.g., a vacuum furnace) can be used, for example, to heat the Si-containing material.The first auxiliary body, the Si-containing material and the porous body to be infiltrated (as well as the optional second auxiliary body) can be provided or arranged, for example, in a furnace (for example a vacuum furnace).

[0028] The method may, for example, further comprise: a cooling step following the infiltration of the porous body, wherein the cooling is carried out at least partially in an N2 atmosphere at a pressure of 500 mbar or more, for example 600 mbar or more, for example 700 mbar or more, for example 800 mbar or more. It has surprisingly been found that, for example, cleaning or reprocessing of the first auxiliary body can be particularly simple and / or the first auxiliary body can be reused particularly easily without complex cleaning or reprocessing.

[0029] Without being bound to this theory, the inventors suspect that an equilibrium exists between BN dissolved in the liquefied, Si-containing material (which has dissolved from the section comprising pBN) and gaseous N2, which can be influenced or shifted by the addition of N2 during cooling. As a result, a concentration or amount of BN dissolved in the liquefied, Si-containing material can be increased during cooling, so that an amount of recrystallized BN formed during cooling can be increased. In other words, the inventors suspect that by adding N2 during cooling, a loss of BN from the section comprising pBN can be reduced, so that a service life of the section comprising pBN can be increased and consequently the first auxiliary body can be used more frequently.

[0030] The Si-containing material may, for example, be provided on a surface of recrystallized BN of the portion comprising pBN. The portion comprising pBN may, for example, comprise or consist (at least substantially) of pBN and recrystallized BN. The portion comprising pBN may, for example, comprise or consist (at least substantially) of pBN, recrystallized BN, and a material of a base body to which pBN has been applied. The portion comprising pBN may, for example, comprise or consist (at least substantially) of a layer (for example, a surface layer) of recrystallized BN, which may, for example, be arranged at the surface of the portion, and a layer of pBN, which may, for example, be arranged directly adjacent to (for example, in direct contact with) the layer of recrystallized BN.The surface of recrystallized BN (of the section comprising pBN) and / or a layer (e.g., surface layer) of recrystallized BN from which the surface of recrystallized BN (of the section comprising pBN) is formed (see below) can, for example, be arranged directly adjacent to (e.g., in direct contact with) pBN. Below and / or next to the surface of recrystallized BN (of the section comprising pBN) and / or the layer (e.g., surface layer) of recrystallized BN from which the surface of recrystallized BN (of the section comprising pBN) is formed (see below), pBN can, for example, be arranged. As a result, for example, a reaction of the Si-containing material with the first auxiliary body can be particularly well at least reduced.

[0031] Without being bound to this theory, the inventors suspect that the surface made of recrystallized BN (of the section comprising pBN), for example due to its structure (which may, for example, comprise crystallites with a platelet-like, rod-like and / or particle-like structure; see below), can reduce a contact area between Si and BN, whereby, for example, a reaction of the Si-containing material with the first auxiliary body can be at least particularly well reduced and, as a result, for example, the first auxiliary body can be reused particularly frequently.

[0032] The method may, for example, include a preliminary break-in process for forming the surface of the recrystallized BN portion of the pBN-containing section. In the break-in process, for example, the first auxiliary body may be subjected to isolated break-in in the absence of the porous body to be infiltrated and the optional second auxiliary body to pretreat a surface of the pBN-containing section.

[0033] The recrystallized BN surface of the portion comprising pBN may be formed, for example, by means of a pre-break-in process in which the first auxiliary body is subjected to isolated breaking in in the absence of the porous body to be infiltrated and the optional second auxiliary body to pretreat a surface of the portion comprising pBN.

[0034] The break-in process may, for example, comprise: providing Si having a purity of 97 wt% or more, for example 97.5 wt% or more, for example 98 wt% or more, for example 98.5 wt% or more, for example 99 wt% or more, on a pBN surface of the portion comprising pBN; exposing the Si to a temperature in the range of 1400°C to 1500°C for a period of 1 min to 120 min to liquefy the Si and dissolve BN from the pBN surface of the portion comprising pBN into the liquefied Si; cooling the liquefied Si and the BN dissolved therein, so that the recrystallized BN surface of the portion comprising pBN is formed.

[0035] The cooling may, for example, be carried out at least partially in an N2 atmosphere at a pressure of 500 mbar or more, for example 600 mbar or more, for example 700 mbar or more, for example 800 mbar or more.

[0036] Without being bound by this theory, the inventors suspect that an equilibrium exists between BN dissolved in the liquefied Si (which was dissolved in the liquefied Si from the pBN surface of the section containing pBN) and gaseous N2, which can be influenced or shifted by the addition of N2 during cooling. This can lead to a concentration or

[0037] Amount of BN dissolved in the liquefied Si can be increased upon cooling, so that an amount of recrystallized BN formed upon cooling can be increased.

[0038] It was surprisingly found that the running-in process or the running-in of the first auxiliary body can, for example, make cleaning or reconditioning the first auxiliary body particularly easy and / or the first auxiliary body can be reused particularly easily without complex cleaning or reconditioning.

[0039] The Si-containing material may, for example, be provided on a pBN surface of the portion comprising pBN. The portion comprising pBN may, for example, consist (at least substantially) of pBN. The portion comprising pBN may, for example, comprise or consist (at least substantially) of pBN and a material of a base body to which pBN has been applied. If the Si-containing material is provided on a pBN surface of the portion comprising pBN, a layer of recrystallized pBN may, for example, be formed during the process.

[0040] The first auxiliary body can, for example, be a crucible or a section thereof. The first auxiliary body can, for example, be a single piece. The first auxiliary body can, for example, have multiple parts or be composed of multiple parts.

[0041] The first auxiliary body can be shaped, for example, and the second auxiliary body can be provided, for example, such that the liquefied, Si-containing material flows to the second auxiliary body and infiltrates it in liquid form. The first auxiliary body can be bowl-shaped, for example, and the second auxiliary body can be arranged, for example, at a lowest point of the bowl, so that the liquefied, Si-containing material flows to the second auxiliary body and infiltrates it in liquid form.

[0042] A contact angle between a / the surface of the section comprising pBN (e.g., the surface of recrystallized BN and / or the surface of pBN) and the liquefied, Si-containing material can be, for example, greater than 85° (e.g., 90° or more). As a result, for example, a contact area between the liquefied, Si-containing material and the first auxiliary body can be small, which can simplify cleaning or reprocessing of the first auxiliary body and / or allow the first auxiliary body to be easily reused without complex cleaning or reprocessing.

[0043] The infiltrated body can be, for example, a friction or sliding body, such as a brake disc, or a portion thereof. As a result, a friction or sliding body, such as a brake disc, can be manufactured with reduced material and / or personnel expenditure and / or efficiently and / or economically, and / or its manufacturing costs can be reduced, for example.

[0044] The surface of recrystallized BN of the portion comprising pBN may, for example, be formed by a layer of recrystallized BN having a thickness (e.g., layer thickness) of 1 pm or greater (e.g., in the range of 1 pm to 100 pm), for example, 5 pm or greater (e.g., in the range of 5 pm to 50 pm), for example, 10 pm or greater (e.g., in the range of 10 pm to 50 pm). The portion comprising pBN may, for example, have a surface layer of recrystallized BN having a thickness (e.g., layer thickness) of 1 pm or greater (e.g., in the range of 1 pm to 100 pm), for example, 5 pm or greater (e.g., in the range of 5 pm to 50 pm), for example, 10 pm or greater (e.g., in the range of 10 pm to 50 pm). The layer of recrystallized BN (of the portion comprising pBN) may, for example, be located directly adjacent to (e.g., in direct contact with) pBN.For example, pBN can be arranged beneath and / or adjacent to the layer of recrystallized BN (the section containing pBN). This can, for example, particularly effectively at least reduce a reaction of the Si-containing material with the first auxiliary body, and / or the layer can, for example, be formed or maintained particularly simply or expediently. Such a layer (with the stated thickness or layer thickness) can, for example, be formed or maintained using the aforementioned run-in process.

[0045] The thickness (e.g., layer thickness) of the layer of recrystallized BN can be determined optically, for example, from a sectional view of the first auxiliary body. For this purpose, the first auxiliary body can be cut essentially orthogonally to a surface of the first auxiliary body, and the cut surface can then be examined, for example, using a scanning electron microscope. The thickness (e.g., layer thickness) of the layer of recrystallized BN can be determined, for example, at an (at least essentially) central location of the surface or layer of recrystallized BN of the section comprising pBN.

[0046] The surface of recrystallized BN of the section comprising pBN can, for example, comprise or consist of crystallites of recrystallized BN with a size in the range from 0.1 pm to 15 pm (for example, in the range from 0.1 pm to 10 pm). The crystallites can, for example, have a platelet-shaped, rod-shaped, and / or particulate structure. For the purposes of this application, a platelet-shaped structure can be understood, for example, as a structure whose extension in two mutually orthogonal spatial directions is ten times or more than its extension in a third spatial direction orthogonal to the two mutually orthogonal spatial directions.For the purposes of this application, a rod-shaped structure can be understood, for example, as a structure whose extension in two orthogonal spatial directions is one-tenth or less than its extension in a third spatial direction orthogonal to the two orthogonal spatial directions. For the purposes of this application, a particulate structure can be understood, for example, as a structure whose extension in three orthogonal spatial directions differs by a maximum factor of two.

[0047] At least a portion of the section comprising pBN can be produced, for example, by means of a CVD process, for example from NH3 and BCl3 or BF3, for example at a pressure of 30 mbar or less and a temperature of 1600°C or greater. For example, the pBN (for example the pBN of the section comprising pBN) can be produced, for example, from NH3 and BCl3 or BF3, for example at a pressure of 30 mbar or less and a temperature of 1600°C or greater. In this way, for example, the section comprising pBN or the pBN can be expediently formed or obtained. Alternatively or additionally, for example, the section comprising pBN or the pBN can be designed as a self-supporting body.

[0048] For example, the pBN of the section containing pBN may have a purity of 99.9% by weight or more.

[0049] According to a second aspect of the invention, an auxiliary body comprising a section of pyrolytic boron nitride, pBN, can be used, for example, in an LSI process for liquefying Si on the pBN section. This allows, for example, an LSI process to be carried out efficiently and / or economically and / or with reduced material and / or personnel expenditure.

[0050] The first auxiliary body can be used, for example, in the manufacture of a friction or sliding body, for example, a brake disc. This allows, for example, a friction or sliding body, for example, a brake disc, to be manufactured with reduced material and / or personnel expenditure and / or efficiently and / or economically, and / or its manufacturing costs can be reduced.

[0051] According to a third aspect of the invention, a friction or sliding body, for example a brake disc, comprising a C / SiC body and / or a SiC / SiC body, can be produced, for example, using a method described above according to the first aspect of the invention. As a result, a friction or sliding body, for example a brake disc, can be produced with reduced material and / or personnel expenditure and / or efficiently and / or economically, and / or its production costs can be reduced.

[0052] Exemplary, but not limiting, embodiments of the invention are illustrated in the figures and are explained in more detail below.

[0053] Figure 1 shows a method for liquid infiltration of a porous body with a liquid Si-containing material, for example an LSI method, according to a first embodiment of the invention.

[0054] Figure 2 shows a method for liquid infiltration of a porous body with a liquid Si-containing material, for example an LSI method, according to a second embodiment of the invention.

[0055] Figure 3 shows a method for liquid infiltration of a porous body with a liquid Si-containing material, for example an LSI method, according to a third embodiment of the invention.

[0056] Figure 4 shows a method for liquid infiltration of a porous body with a liquid Si-containing material, for example an LSI method, according to a fourth embodiment of the invention.

[0057] Figure 5 shows a method for liquid infiltration of a porous body with a liquid, Si-containing material, for example, an LSI method, according to a fifth embodiment of the invention. Figure 6 shows a method for liquid infiltration of a porous body with a liquid, Si-containing material, for example, an LS I method, according to a sixth embodiment of the invention.

[0058] Figure 7 shows an upstream run-in process of a method for liquid infiltration of a porous body with a liquid, Si-containing material, for example an LSI method, according to a seventh embodiment of the invention.

[0059] Figure 8 shows a sectional view through a first auxiliary body 10 with Si-containing material 12 provided thereon and a porous body 14 to be infiltrated provided thereon according to an eighth embodiment of the invention.

[0060] Figure 9 shows a sectional view through a first auxiliary body 10 with Si-containing material 12 provided thereon and a porous body 14 to be infiltrated provided thereon or partially therein according to a ninth embodiment of the invention.

[0061] Figure 10 shows a sectional view through a first auxiliary body 10 with Si-containing material 12 provided thereon and with two second auxiliary bodies 16 provided thereon and a porous body 14 to be infiltrated provided thereon according to a tenth embodiment of the invention

[0062] Figure 11 shows a detailed view 24 from Figure 8 according to an eleventh embodiment of the invention.

[0063] Figure 12 shows a detailed view 24 from Figure 8 according to a twelfth embodiment of the invention.

[0064] Figure 13 shows a plan view of a pBN surface of the portion comprising pBN of the first auxiliary body according to a thirteenth embodiment of the invention, taken by means of a scanning electron microscope.

[0065] Figure 14 shows a plan view of a recrystallized BN surface of the portion comprising pBN of the first auxiliary body according to a fourteenth embodiment of the invention, taken by means of a scanning electron microscope.

[0066] Figure 15 shows a sectional view of the first auxiliary body, cut substantially orthogonally to a surface of the first auxiliary body and recorded by means of a scanning electron microscope.

[0067] In the following description, reference is made to the accompanying drawings which form a part hereof, and in which is shown by way of illustration specific embodiments in which the invention may be practiced.

[0068] It is understood that other embodiments may be utilized and structural or logical changes may be made without departing from the scope of the present invention. It is understood that the features of the embodiments described herein may be combined with one another unless specifically stated otherwise. The following description is therefore not to be construed in a limiting sense, and the scope of the present invention is defined by the appended claims.

[0069] In the figures, identical or similar elements are provided with identical reference numerals where appropriate.

[0070] As shown, for example, in Figures 1-15, a method for liquid infiltration of a porous body with a liquid, Si-containing material (for example, an LSI method) may, for example, comprise providing a first auxiliary body 10 having a section 18 comprising pyrolytic boron nitride, pBN, 20 S101, providing a Si-containing material 12 on the section 18 comprising pBN 20 in order to heat the Si-containing material 12 on the section 18 comprising pBN 20 to a temperature at which the Si-containing material 12 is liquefied S102, and providing a porous body 14 to be infiltrated such that the Si-containing material 12, after being liquefied on the section 18 comprising pBN 20, infiltrates the porous body 14 to be infiltrated in liquid form S103.

[0071] As shown, for example, in Figures 2, 4, 6 and 10, the method may further comprise, for example, providing a second auxiliary body 16 made of a porous material such that the Si-containing material 12, after being liquefied on the section 18 comprising pBN 20, infiltrates S104 the second auxiliary body 16 in liquid form, wherein the porous body 14 to be infiltrated is provided such that the Si-containing material 12, which has infiltrated the second auxiliary body 16, infiltrates the porous body 14 to be infiltrated out of the second auxiliary body 16 in liquid form.

[0072] The Si-containing material 12 may, for example, be Si with a purity of 97% by weight or more. Alternatively, the Si-containing material 12 may, for example, be a Si-containing alloy.

[0073] The porous body 14 to be infiltrated may, for example, comprise or consist (at least substantially) of a C / C material (carbon fiber reinforced carbon material) and / or a SiC / C material (silicon carbide fiber reinforced carbon material).

[0074] The second auxiliary body 16 may, for example, comprise or consist (at least substantially) of a porous carbon (for example a C / C material).

[0075] The porous body 14 to be infiltrated and the second auxiliary body 16 may, for example, comprise the same materials or consist (at least substantially) thereof, for example a C / C material or a SiC / C material.

[0076] The Si-containing material 12 can, for example, be exposed to a temperature in the range of 1410°C to 1650°C and a pressure in the range of 0.01 mbar to 100 mbar for a period of time from 5 min to 180 min (these conditions can also be referred to as “low-temperature processes / windows”).

[0077] The Si-containing material 12 can, for example, be exposed to a temperature in the range of 1500°C to 1800°C and a pressure in the range of 10 mbar to ambient pressure (e.g., 1013 mbar) for a period of 5 minutes to 180 minutes (these conditions can also be referred to, for example, as a "high-temperature process / window"). In the "high-temperature process / window," it can, for example, be particularly advantageous to work with a retracted, first auxiliary body (i.e., with a first auxiliary body that has undergone the (upstream) retraction process described herein).

[0078] The Si-containing material 12 can, for example, be exposed to a temperature in the range of 1550°C to 1750°C and a pressure in the range of 10 mbar to ambient pressure (for example 1013 mbar) in an Ar atmosphere for a period of 5 min to 45 min.

[0079] For example, as shown in Figures 3-6, the method may further comprise a cooling step following the infiltration of the porous body 14, wherein the cooling is carried out at least partially in an N2 atmosphere at a pressure of 500 mbar or more S105.

[0080] For example, as shown in Figure 12, the Si-containing material 12 may be provided on a recrystallized BN 22 surface of the portion 18 comprising pBN 20. Recrystallized BN 22 surfaces of the portion 18 comprising pBN 20 are also shown, for example, in Figures 14 and 15.

[0081] For example, as shown in Figures 5 and 6, the method may include a pre-break-in process to form the surface of recrystallized BN 22 of portion 18 comprising pBN 20.

[0082] As shown, for example, in Figures 5 and 6, the surface of recrystallized BN 22 of the portion 18 comprising pBN 20 may be formed, for example, by means of a pre-break-in process in which the first auxiliary body 10 is subjected to an isolated break-in in the absence of the porous body 14 to be infiltrated and optionally the second auxiliary body 16 in order to pretreat S106 a surface of the portion 18 comprising pBN 20.

[0083] As shown, for example, in Figure 7, the break-in process may, for example, comprise providing Si with a purity of 97 wt% or more on a pBN 20 surface of section 18 comprising pBN 20, S106a, exposing the Si to a temperature in the range of 1400°C to 1500°C for a period of time of 1 min to 120 min to liquefy the Si and to dissolve BN from the pBN 20 surface of section 18 comprising pBN 20 into the liquefied Si S106b, cooling the liquefied Si and the BN dissolved therein such that the recrystallized BN 22 surface of section 18 comprising pBN 20 is formed S106c, wherein optionally the cooling may be carried out at least partially in an N2 atmosphere at a pressure of 500 mbar or more.

[0084] For example, as shown in Figure 11, the Si-containing material 12 may be provided on a pBN 20 surface of the portion 18 comprising pBN 20. A pBN 20 surface of the portion 18 comprising pBN 20 is also shown, for example, in Figure 13

[0085] As shown, for example, in Figures 11 and 12, a section 18 comprising pBN 20 may be understood, for example, as a section 18 comprising or consisting (at least substantially) of pBN 20 and recrystallized BN 22 (Figure 12; see also Figures 14 and 15), or as a section 18 consisting (at least substantially) of pBN 20 (Figure 11; see also Figure 13). Furthermore, a section 18 comprising pBN 20 may be understood, for example, as a section 18 comprising or consisting (at least substantially) of pBN 20 and a support material (for example graphite) to which the pBN 20 has been applied, or as a section 18 comprising or consisting (at least substantially) of pBN 20, recrystallized BN 22 and a support material (for example graphite) to which the pBN 20 has been applied.

[0086] For example, as shown in Figure 11, the portion 18 comprising pBN 20 may consist (at least substantially) of pBN 20 (see also Figure 13). For example, as shown in Figure 12, the portion 18 comprising pBN 20 may consist (at least substantially) of pBN 20 and recrystallized BN 22 (see also Figures 14 and 15). For example, as shown in Figures 12 and 15, the portion 18 comprising pBN 20 may comprise a (first) layer (e.g., surface layer) of recrystallized BN 22 forming a surface of the portion 18 comprising pBN, and a (second) layer of pBN 20 arranged adjacent thereto, which is in direct contact with the (first) layer of recrystallized BN 22. Recrystallized BN can be formed, for example, by means of and / or during the (upstream) run-in process described above.Alternatively or additionally, recrystallized BN can be formed, for example, by means of and / or during the process for liquid infiltration of a porous body described above. In this respect, recrystallized BN can be formed, for example, using the (upstream) run-in process described above, but this is not mandatory.

[0087] The first auxiliary body 10 can, for example, be a crucible or a portion thereof. The first auxiliary body 10 can, for example, be shaped in such a way, and the second auxiliary body 16 can, for example, be provided in such a way that the liquefied, Si-containing material 12 flows to the second auxiliary body 16 and infiltrates it in liquid form.

[0088] For example, as shown in Figures 8-12, a contact angle between a / the surface of the portion 18 comprising pBN 20 (e.g., the surface of recrystallized BN 22 or the surface of pBN 20) and the liquefied Si-containing material 12 may be greater than 85° (a contact angle of 90° is shown in Figures 8-12, respectively).

[0089] The infiltrated body 14 may be, for example, a friction or sliding body, for example a brake disc, or a portion thereof.

[0090] As shown, for example, in Figure 15, the surface of recrystallized BN 22 of the section 18 comprising pBN 20 can be formed, for example, from a layer of recrystallized BN 22 with a thickness (e.g., layer thickness) of 1 pm or more (e.g., in the range from 1 pm to 100 pm), for example, 5 pm or more (e.g., in the range from 5 pm to 50 pm), for example, 10 pm or more (e.g., in the range from 10 pm to 50 pm). In Figure 15, the recrystallized BN 22 and the pBN 20 can be distinguished based on the brightness of the corresponding substance in the scanning electron micrograph. In the embodiment shown in Figure 15, the layer of recrystallized BN 22 has a thickness of approximately 15 pm. To obtain the micrograph shown in Figure 15, the first auxiliary body was cut substantially orthogonally to a surface of the first auxiliary body.The resulting cut surface was then examined using a scanning electron microscope.

[0091] As shown, for example, in Figure 14, the surface of recrystallized BN 22 of section 18 comprising pBN 20 may, for example, comprise crystallites of recrystallized BN 22 with a size in the range of 0.1 pm to 15 pm (e.g., 0.1 pm to 10 pm). The crystallites may, for example, have a platelet-like (Figure 14, right side), rod-like, and / or particulate (Figure 14, left side) structure.

[0092] At least a portion of the section 18 comprising pBN 20 may be produced, for example, by a CVD process. The pBN 20 (for example, the pBN of the section 18 comprising pBN 20) may be produced, for example, by a CVD process. The CVD process may be carried out, for example, using NH3 and BCl3 or BF3, at a pressure of 30 mbar or less and a temperature of 1600°C or greater. The pBN (for example, the pBN of the section comprising pBN, for example, the pBN produced by the CVD process) may, for example, have a purity of 99.9% by weight or more.

[0093] An auxiliary body 10 (for example, the first auxiliary body 10) having a section 18 of pyrolytic boron nitride, pBN, 20 can be used, for example, in an LSI process for liquefying Si on the section 18 of pBN 20, for example in the production of a friction or sliding body, for example a brake disc.

[0094] A friction or sliding body, for example a brake disc, can have, for example, a C / SiC body or a SiC / SiC body, which can be produced or is produced using one of the methods described above.

[0095] List of reference symbols: 10 first auxiliary body; 12 Si-containing material; 14 porous body to be infiltrated; 16 second auxiliary body; 18 section comprising pBN; 20 pBN; 22 recrystallized BN; 24 detailed view.

Claims

Claims:

1. A method for liquid infiltration of a porous body with a liquid, Si-containing material, for example LS l method, comprising Providing a first auxiliary body (10) with a section (18) comprising pyrolytic boron nitride, pBN, (20) (S101), Providing a Si-containing material (12) on the section (18) comprising pBN (20) to heat the Si-containing material (12) on the section (18) comprising pBN (20) to a temperature at which the Si-containing material (12) is liquefied (S102), and Providing a porous body (14) to be infiltrated such that the Si-containing material (12), after its liquefaction on the section (18) comprising pBN (20), infiltrates the porous body (14) to be infiltrated in liquid form (S103).

2. The method of claim 1, further comprising Providing a second auxiliary body (16) made of a porous material such that the Si-containing material (12), after being liquefied on the section (18) comprising pBN (20), infiltrates the second auxiliary body (16) in liquid form (S104), wherein the porous body (14) to be infiltrated is provided such that the Si-containing material (12), which has infiltrated the second auxiliary body (16), infiltrates the porous body (14) to be infiltrated from the second auxiliary body (16) in liquid form.

3. The method according to claim 1 or 2, wherein the Si-containing material (12) is Si with a purity of 97% by weight or more.

4. Method according to one of claims 1 to 3, wherein the porous body (14) to be infiltrated comprises or consists of a C / C material and / or a SiC / C material.

5. Method according to claim 2 or according to claim 3 or 4, when dependent on claim 2, wherein the second auxiliary body (16) comprises or consists of a porous carbon, for example a C / C material.

6. The method according to claim 2 or according to any one of claims 3 to 5, when dependent on claim 2, wherein the porous body (14) to be infiltrated and the second auxiliary body (16) comprise or consist of the same materials.

7. The method according to any one of claims 1 to 6, wherein the Si-containing material (12) is exposed to a temperature in the range of 1410°C to 1650°C and a pressure in the range of 0.01 mbar to 100 mbar for a period of time of 5 min to 180 min.

8. The method according to any one of claims 1 to 6, wherein the Si-containing material (12) is exposed to a temperature in the range of 1500°C to 1800°C and a pressure in the range of 10 mbar to ambient pressure for a period of 5 min to 180 min.

9. The method according to claim 8, wherein the Si-containing material (12) is exposed to a temperature in the range of 1550°C to 1750°C and a pressure in the range of 10 mbar to ambient pressure in an Ar atmosphere for a period of 5 min to 45 min.

10. The method according to any one of claims 1 to 9, further comprising a cooling step following the infiltration of the porous body (14), wherein the cooling is carried out at least partially in an N2 atmosphere at a pressure of 500 mbar or more (S105).

11. The method according to any one of claims 1 to 10, wherein the Si-containing material (12) is provided on a surface of recrystallized BN (22) of the portion (18) comprising pBN (20).

12. The method according to claim 11, wherein the surface of recrystallized BN (22) of the portion (18) comprising pBN (20) is formed by means of a preliminary running-in process in which the first auxiliary body (10) is subjected to an isolated running-in in the absence of the porous body (14) to be infiltrated and the optional second auxiliary body (16) of claim 2 in order to pretreat a surface of the portion (18) comprising pBN (20) (S106).

13. The method of claim 12, wherein the run-in process comprises Providing Si with a purity of 97 wt% or more on a surface of pBN (20) of the section (18) comprising pBN (20) (S106a), Exposing the Si to a temperature in the range of 1400°C to 1500°C for a period of 1 min to 120 min to liquefy the Si and to dissolve BN from the surface of pBN (20) of the section (18) comprising pBN (20) into the liquefied Si (S106b), Cooling the liquefied Si and the BN dissolved therein so that the surface of recrystallized BN (22) of the portion (18) comprising pBN (20) is formed (S106c), wherein optionally the cooling is carried out at least partially in an N2 atmosphere at a pressure of 500 mbar or more.

14. The method according to any one of claims 1 to 10, wherein the Si-containing material (12) is provided on a pBN (20) surface of the portion (18) comprising pBN (20).

15. The method according to any one of claims 1 to 14, wherein the first auxiliary body (10) is a crucible or a portion thereof, and / or wherein the first auxiliary body (10) is shaped and the optional second auxiliary body (16) of claim 2 is provided such that the liquefied Si-containing material (12) flows to the optional second auxiliary body (16) of claim 2 and infiltrates it in liquid form, and / or wherein a contact angle between a / the surface of the portion (18) comprising pBN (20), for example the surface of recrystallized BN (22) of claim 11 or the surface of pBN (20) of claim 14, and the liquefied Si-containing material (12) is greater than 85°.

16. Method according to one of claims 1 to 15, wherein the infiltrated body (14) is a friction or sliding body, for example a brake disc, or a portion thereof.

17. The method of claim 11 or any one of claims 12, 13, 15 or 16 when dependent on claim 11, wherein the surface of recrystallized BN (22) of the portion (18) comprising pBN (20) is covered by a layer of recrystallized BN (22) is formed with a thickness of 1 pm or greater, for example 5 pm or greater, for example 10 pm or greater.

18. The method according to claim 11 or any one of claims 12, 13, 15, 16 or 17 when dependent on claim 11, wherein the surface of recrystallized BN (22) of the portion (18) comprising pBN (20) comprises crystallites of recrystallized BN (22) having a size in the range of 0.1 pm to 15 pm, and wherein the crystallites optionally have a platelet-shaped, rod-shaped and / or particulate structure.

19. The method according to any one of claims 1 to 18, wherein at least a part of the portion (18) comprising pBN (20) is produced by means of a CVD process.

20. The method according to claim 19, wherein at least a part of the section (18) comprising pBN (20) is produced by means of a / the CVD process from NH3 and BCl3 or BF3, optionally at a pressure of 30 mbar or less and a temperature of 1600°C or greater.

21. The method according to any one of claims 1 to 20, wherein the pBN of the portion comprising pBN has a purity of 99.9% by weight or more.

22. Use of an auxiliary body (10) having a section (18) of pyrolytic boron nitride, pBN, (20) in an LSI process for liquefying Si on the section (18) of pBN (20).

23. Use according to claim 22 in the manufacture of a friction or sliding body, for example a brake disc.

24. Friction or sliding body, for example a brake disc, comprising a C / SiC body or a SiC / SiC body, producible / produced by a method according to one of claims 1 to 21.

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