Mixed carbide and its use

Abstract

Mixed carbide with a composition according to the formula (Ti x Mon y Me z )C i , where Me is at least one transition metal selected from the group consisting of zirconium, hafnium, vanadium, niobium, tantalum, chromium, tungsten, and mixtures thereof, z is in the range of 0.01 to 0.20, i is in the range from 0.60 to 1.00, and where x + y + z = 1 and the ratio x / y results in a value in the range from 1.5 to 9.0.

Description

[0001] The present invention relates to a mixed carbide having a composition according to the formula (Ti x Mon y Me z )C i , where Me is at least one transition metal selected from the group consisting of zirconium, hafnium, vanadium, niobium, tantalum, chromium, tungsten, and mixtures thereof, z is in the range from 0.01 to 0.20, i is in the range from 0.60 to 1.00, and where x + y + z = 1 and the ratio x / y results in a value that is in the range from 1.5 to 9.0. The present invention also relates to uses of the mixed carbide according to the invention.

[0002] Wear protection coatings to extend the service life of tools and functional components (e.g. extruders / conveyor screws, water turbines, brake discs, components of agricultural machinery, etc.) are currently produced by thermal coating processes (e.g. laser deposition welding, thermal spraying, etc.) from tungsten carbides (WC, WSC, SWSC), titanium carbide (TiC) or chromium carbides (Cr3C2, Cr7C3, Cr 23 C6) with a metallic matrix (Co, Ni, Fe-based alloys).

[0003] The miscibility, i.e., the formation of solid solutions, of the carbides of transition metals of subgroups IV, V, and VI of the Periodic Table of Elements is well known in principle (R. KIEFFER, F. BENESOVSKY: Hartstoffe. Vienna: Springer-Verlag, 1963. - ISBN: 978-3-7091-7152-3; H. HOLLECK: Binäre und ternäre Carbide- und Nitridesysteme der Übergangsmetalle. Stuttgart: Gebrüder Bornträger, 1984 (Materialskundlich-Technische Reihe). - ISBN: 978-3-443-23007-4). While binary carbides are also frequently used in technical applications and have been specifically developed (e.g., DE 197 04 242 C1), the potential of ternary solid solutions remains untapped. Only US Pat. No. 5,563,107 A describes dense, fine-grained ceramic bodies for binary and ternary solid solutions, including TiC-TaC-HfC, in addition to WC. Whether such materials could meet specific requirements in the field of surface technology is not yet known.

[0004] US 2023 / 0406713 A1 relates to a complex carbide for applications in mining and mineral processing where an additional metal is required, wherein the additional metal is a transition metal.

[0005] AT 14861 U1 describes an ion implanter comprising at least one component made of a refractory metal from the group consisting of W, W alloy, Mo, and Mo alloy. The surface of this component has, at least in some regions, a layer formed, at least in some regions, from at least one compound of at least one element selected from the group consisting of C, B, and N with at least one element selected from the group consisting of W and Mo.

[0006] Depending on the hard material (carbide), there are various disadvantages to currently available solutions. Tungsten carbide-based coatings are usually expensive, heavy (high density of W), based on tungsten, a critical raw material (CRM), and often exhibit cracks due to the different thermal expansion coefficients (TC) of the carbide and the metal matrix. Titanium carbide exhibits poorer wettability and thus a higher risk of defect formation, and chromium carbide-based coatings are usually significantly lower in hardness. Furthermore, tungsten and chromium carbides react intensively with many matrix materials, meaning the hard materials dissolve.

[0007] Based on this, the object of the present invention was to provide a mixed carbide which has a comparatively high hardness and a comparatively low density and preferably also a comparatively high thermal expansion coefficient and a comparatively good wettability (with typical metal binders).

[0008] This problem is solved by a mixed carbide having the features of patent claim 1. Patent claims 10 and 11 specify possible uses of the mixed carbide. The dependent patent claims represent advantageous developments.

[0009] According to the invention, a mixed carbide having a composition according to the formula (Ti x Mon y Me2)C i , provided, whereby Me is at least one transition metal selected from the group consisting of zirconium, hafnium, vanadium, niobium, tantalum, chromium, tungsten, and mixtures thereof, z is in the range of 0.01 to 0.20, i is in the range from 0.60 to 1.00, andwhere x + y + z = 1 (or x + y + z = 1.00) and the ratio x / y results in (or corresponds to) a value that is in the range from 1.5 to 9.0.

[0010] Where x and y are both > 0 (or > 0.00) and < 1 (or < 1.00). For example, x is in the range from 0.01 to 0.98 and / or y is in the range from 0.01 to 0.98, provided that the ratio x / y results in (or corresponds to) a value in the range from 1.5 to 9.0.

[0011] Preferably, x is in the range of 0.48 to 0.89 and / or y is in the range of 0.08 to 0.40.

[0012] The mixed carbide according to the invention with the composition according to the formula (Ti x Mony Me z )C i can also be used as a mixed carbide composition according to the invention according to the formula (Ti x Mon y Me z )C i be referred to.

[0013] The mixed carbide according to the invention is characterized by its special composition, which is based on a combination of special carbide-forming transition metals, including Ti and Mo, whose defined ratios to one another lead to a surprising combination of advantageous properties of the mixed carbide. Due to its special composition, the mixed carbide according to the invention exhibits a comparatively high hardness, a comparatively high thermal expansion coefficient, a comparatively low density, and comparatively good wettability with typical metal binders. Furthermore, the mixed carbide according to the invention contains no CRM substance or only a comparatively low proportion of CRM substances.

[0014] The mixed carbide according to the invention can be produced, for example, by processing corresponding individual carbide powders, such as TiC, Mo2C, and TaC, using a conventional powder technology. This comprises solution-based powder preparation of the individual carbide powders, e.g., TiC, Mo2C, and TaC, in a ball mill, cold isostatic pressing as a shaping process, and compressed gas-assisted sintering. A powder can be obtained by subsequent crushing and grinding of the sintered body. By fractionating the powder (e.g., sieving), the powders can be obtained with an average particle size in the range of 25 µm to 90 µm and 0.5 to 5 µm.Another production route for powders with an average particle size in the range of 0.5 to 5 µm is carbothermal reduction, in which corresponding metal oxide powders, for example TiO2, MoO3 and Ta2O5, react with carbon under inert conditions and mixed carbides with an average particle size in the range of 0.5 µm to 5 µm are obtained.

[0015] A preferred embodiment of the mixed carbide according to the invention is characterized in that the mixed carbide exists as a single-phase cubic phase. Whether the mixed carbide exists as a single-phase cubic phase can be determined, for example, by X-ray diffraction (XRD).

[0016] According to a further preferred embodiment of the mixed carbide according to the invention, the mixed carbide is present as a (mixed carbide) powder. In this case, the mixed carbide according to the invention can also be referred to as mixed carbide powder according to the invention.

[0017] A further preferred embodiment of the mixed carbide according to the invention is characterized in that the powder (or the mixed carbide powder) consists of particles having an average particle size in the range of 0.5 µm to 99 µm. The average particle size can be determined, for example, by laser diffraction, e.g., according to DIN ISO 13320:2022-12. Particle size analysis – laser diffraction method.

[0018] According to a further preferred embodiment of the mixed carbide according to the invention, the powder consists of particles having an average particle size in the range of 25 µm to 90 µm. The average particle size can be determined, for example, by laser diffraction, e.g., according to DIN ISO 13320:2022-12. Particle size analysis – laser diffraction method. Such a mixed carbide powder is highly suitable for use together with at least one metal and / or at least one metallic alloy for applications in surface technologies, e.g., laser cladding and / or powder plasma cladding (PTA).

[0019] A further preferred embodiment of the mixed carbide according to the invention is characterized in that the powder consists of particles having an average particle size in the range of 0.5 µm to 5 µm. The average particle size can be determined, for example, by laser diffraction, e.g., according to ISO DIN ISO 13320:2022-12. Particle size analysis – laser diffraction method. Such a mixed carbide powder is highly suitable for use together with at least one metal and / or at least one metallic alloy for the production of composite powders by agglomeration (e.g., by spray drying) and sintering.

[0020] A further preferred embodiment of the mixed carbide according to the invention is characterized in that the mixed carbide (or the mixed carbide powder) has a proportion of impurities containing at least one elemental metal of < 0.5 wt. %, based on the total weight of the mixed carbide (or the mixed carbide powder). The at least one elemental metal is preferably selected from the group consisting of cobalt, iron, nickel, and mixtures thereof. The proportion of impurities containing at least one elemental metal can be determined, for example, by means of inductively coupled plasma optical emission spectrometry (ICP-OES) according to DIN 51086-2:2004-07.“Testing of oxidic raw materials and base materials for ceramics, glass and glazes - Part 2: Determination of Ag, As, B, Ba, Be, Bi, Ca, Cd, Ce, Co, Cr, Cu, Er, Eu, Fe, La, Mg, Mn, Mo, Nd, Ni, P, Pb, Pr, S, Sb, Se, Sn, Sr, Ti, V, W, Y, Yb, Zn, Zr by inductively coupled plasma optical emission spectrometry (ICP OES)”, e.g. after a suitable fusion process, for example carbonate / peroxide-based fusion process.

[0021] According to a further preferred embodiment of the mixed carbide according to the invention, Me is at least one transition metal selected from the group consisting of tungsten, niobium, tantalum, chromium, and mixtures thereof.

[0022] A further preferred embodiment of the mixed carbide according to the invention is characterized in that - x is in the range from 0.48 to 0.89, preferably from 0.52 to 0.88, and / or - y is in the range from 0.08 to 0.40, preferably from 0.09 to 0.37, and / or - z is in the range of 0.05 to 0.20.

[0023] A further preferred embodiment of the mixed carbide according to the invention is characterized in that the mixed carbide - has a (Vickers) hardness in the range from 1500 HV 0.1 to 3000 HV 0.1, preferably from 1900 HV 0.1 to 2700 HV 0.1, and / or - a thermal expansion coefficient in the range of 6.0 10 -6 K -1 up to 9.0 · 10 -6 K -1 , preferably 6.5 · 10 -6 K -1 up to 8.5 · 10 -6 K -1 , and / or - a density in the range of 4.8 g / cm 3 up to 6.5 g / cm 3 , preferably 5.0 g / cm 3 up to 6.3 g / cm 3 , and / or - a wettability characterized by a wetting angle (relative to a metal melt or metal alloy melt) in the range from 10° to 50°, preferably from 10° to 30°.

[0024] The (Vickers) hardness can be determined, for example, by optically measuring the diagonals of the indentation after loading with a Vickers indenter, according to ISO 14705:2016-12. Advanced ceramics – Hardness testing of monolithic ceramics at room temperature.

[0025] The thermal expansion coefficient can be determined, for example, by measuring the thermal expansion of a sample as a function of temperature according to DIN 51045-4:2007-01. Determination of the change in length of solid bodies under the influence of heat using the dilatometer method – Part 4: Testing of fired heavy clay materials.

[0026] The density can be determined, for example, using He pycnometry, according to DIN 66137–2:2019–03. Determination of the density of solids – Part 2: Gas pycnometry.

[0027] Wettability can be determined, for example, using optical dilatometer tests. The mixed carbide in the form of a polished sintered body as a substrate is heated under an inert atmosphere with a defined shaped body consisting of the metal or metal alloy to be tested (e.g. stainless steel 316 or 316L). When the melting point of the metal or metal alloy is reached or exceeded, the shaped body softens and forms a wetting angle with the surface of the mixed carbide. A constant wetting angle is established after 5 minutes at (approx.) 50 to 100 °C above the melting point of the respective metal or metal alloy. It can be determined by graphically evaluating the images. This measurement method is based on the standard DIN 51730:2022-02. Testing of solid fuels - Determination of ash melting behavior with regard toThe analysis, graphical evaluation of the image acquisition, and determination of the wetting angle are based on the standard DIN EN ISO 19403-2:2020-04. Paints and varnishes – Wettability – Part 2: Determination of the surface free energy of solid surfaces by measuring the contact angle (ISO 19403-2:2017); German version EN ISO 19403-2:2020.

[0028] The present invention additionally relates to the use of the mixed carbide according to the invention, which is in the form of a powder consisting of particles having an average particle size in the range from 25 µm to 90 µm, together with at least one metal and / or at least one metallic alloy for applications in surface technologies (or at least one surface technology), preferably in laser deposition welding and / or powder plasma deposition welding (PTA). In other words, the mixed carbide powder according to the invention, which consists of particles having an average particle size in the range from 25 µm to 90 µm, can be used together with at least one metal and / or at least one metallic alloy for applications in surface technologies (or at least one surface technology), wherein the surface technologies (orThe at least one surface technology is preferably laser cladding and / or powder plasma cladding (PTA). Preferably, the at least one metal and / or the at least one metallic alloy consists of iron (Fe), nickel (Ni), cobalt (Co), manganese (Mn), and / or chromium (Cr) and / or alloys such as Inconel, Stellite, 316 (steel 316 or 316L), or 430 (steel 430 or 430L). Surface technologies are understood to mean processes or technologies for treating surfaces.

[0029] The present invention also relates to a method for treating surfaces in which a) a powder mixture is provided which comprises the mixed carbide according to the invention in the form of a powder (or the mixed carbide powder according to the invention), which consists of particles with an average particle size in the range from 25 µm to 90 µm, and at least one metal and / or at least one metallic alloy, wherein the at least one metal and / or the at least one alloy preferably consists of iron (Fe), nickel (Ni), cobalt (Co), manganese (Mn) and / or chromium (Cr) and / or alloys such as Inconel, Stellite, 316 (steel 316 or 316L) or 430 (steel 430 or 430L), and b) at least one surface is treated using the provided powder mixture (by a surface technology), preferably by laser cladding and / or by powder plasma cladding (PTA).

[0030] The aforementioned preferred embodiments of the mixed carbide according to the invention are also considered to be preferred embodiments for the mixed carbide according to the invention used in the process according to the invention for treating surfaces.

[0031] The present invention further relates to the use of the mixed carbide according to the invention, which is in the form of a powder consisting of particles having an average particle size in the range from 0.5 µm to 5 µm, together with at least one metal and / or at least one metallic alloy for the production (or manufacture) of composite powders by agglomeration (of powder particles), preferably spray-drying (of powder particles), and sintering (of the agglomerated powder particles). In other words, the mixed carbide powder according to the invention, which consists of particles having an average particle size in the range from 0.5 µm to 5 µm, can be used together with at least one metal and / or at least one alloy for the production (or manufacture) of composite powders by agglomeration (of powder particles) and sintering (of the agglomerated powder particles), wherein the agglomeration is preferably carried out by spray-drying.Preferably, the at least one metal and / or the at least one metallic alloy consists of iron (Fe), nickel (Ni), cobalt (Co), manganese (Mn) and / or chromium (Cr) and / or alloys such as Inconel, Stellite, 316 (steel 316 or 316L) or 430 (steel 430 or 430L).

[0032] The present invention also relates to a method for the production (or manufacture) of composite powders, in which a) a powder mixture is provided which contains the mixed carbide according to the invention in the form of a powder (or the mixed carbide powder according to the invention), which consists of particles with an average particle size in the range from 0.5 µm to 5 µm, and at least one metal and / or at least one metallic alloy, wherein the at least one metal and / or the at least one alloy preferably consists of iron (Fe), nickel (Ni), cobalt (Co), manganese (Mn) and / or chromium (Cr) and / or alloys such as Inconel, Stellite, 316 (steel 316 or 316L) or 430 (steel 430 or 430L), b) the particles of the powder mixture provided are agglomerated, preferably by spray drying, and c) the agglomerated particles are sintered.

[0033] The aforementioned preferred embodiments of the mixed carbide according to the invention are also considered to be preferred embodiments for the mixed carbide according to the invention used in the process according to the invention for the production (or manufacture) of composite powders.

[0034] The present invention will be explained in more detail with reference to the following examples, without limiting it to the specific embodiments and parameters shown here. Example 1

[0035] The production of a mixed carbide with the composition (Ti 0,60 Mon 0,35 Ta 0,05 )C 0,9, which is in the form of a powder consisting of particles with an average particle size in the range of 25 µm to 90 µm, is produced using classic powder technology, which consists of solution-based powder processing of Ti, Mo, and Ta carbides in a ball mill, cold isostatic pressing as a shaping process at 300 MPa, and compressed gas-assisted sintering at 1900 °C under argon. Subsequent crushing and grinding of the sintered body resulted in a powder. After fractionation, a powder with an average particle size of 83 µm is obtained, measured according to DIN ISO 13320:2022-12, "Particle size analysis - Laser diffraction method." The mixed carbide has a hardness of 2421 HV. 0,1 , determined according to ISO 14705:2016-12 “Advanced performance ceramics - Hardness test of monolithic ceramics at room temperature”, a thermal expansion coefficient of 7.2 10 -6 K -1, determined according to DIN 51045-4:2007-01. Determination of the change in length of solid bodies under the influence of heat using the dilatometer method – Part 4: Testing of fired heavy clay materials, a density of 6.2 g / cm 3, determined according to DIN 66137-2:2019-03. Determination of the density of solids - Part 2: Gas pycnometry, and a wettability characterized by a wetting angle of 13° compared to 316L (steel 316L). The wettability was determined using optical dilatometer tests by heating the mixed carbide in the form of a polished sintered body as a substrate with a defined shaped body consisting of the metal or metal alloy to be tested under an inert atmosphere. When the melting point of the metal or metal alloy is reached or exceeded, the shaped body softens and forms a wetting angle with the surface of the mixed carbide. A constant wetting angle is established after 5 minutes at (approx.) 50 to 100 °C above the melting point of the respective metal or metal alloy. It can be determined by graphically evaluating the images. This measurement method is based on the standard DIN 51730:2022-02.Testing of solid fuels – Determination of ash melting behavior with regard to the analysis, graphical evaluation of the image recording, and determination of the contact angle is carried out in accordance with DIN EN ISO 19403-2:2020-04. Paints and varnishes – Wettability – Part 2: Determination of surface free energy of solid surfaces by measuring the contact angle (ISO 19403-2:2017); German version EN ISO 19403-2:2020. Example 2

[0036] The production of a mixed carbide with the composition (Ti 0,65 Mon 0,28 W 0,07 )C 0,8, which is in the form of a powder consisting of particles with an average particle size in the range of 0.5 µm to 5 µm, which can be used together with at least one powder containing or consisting of at least one metal and / or at least one alloy for the production (or manufacture) of composite powders by agglomeration and sintering, is carried out using classic powder technology, which consists of the solution-based powder preparation of Ti, Mo, and W carbides or metallic starting materials in a ball mill, cold isostatic pressing as a shaping process at 300 MPa, and gas-assisted sintering at 1900 °C. A powder was obtained by subsequent crushing and grinding of the sintered body. After fractionation, a powder with an average particle size of 4.5 µm is obtained, measured according to DIN ISO 13320:2022-12. Particle size analysis – laser diffraction method.The mixed carbide has a hardness of 2635 HV. 0,1 , determined according to ISO 14705:2016-12. Advanced technical ceramics – Hardness test of monolithic ceramics at room temperature, a thermal expansion coefficient of 7.0 10 K determined according to DIN 51045-4:2007-01. Determination of elongation of solid bodies under the influence of heat by the dilatometer method – Part 4: Testing of fired heavy clay materials, a density of 5.7 g / cm 3 , determined according to DIN 66137-2:2019-03. Determination of the density of solids - Part 2: Gas pycnometry and a wettability characterized by a wetting angle of 14° compared to 430 (steel 430 or 430L), whereby the wettability was determined as in Example 1.

[0037] The resulting mixed carbide powder is suspended with 430 powder (or 430 steel powder) using a suitable mass preparation process, and flowable granules are obtained via spray granulation. Subsequent heat treatment, including debinding at 400 °C under an H2 atmosphere and pressurized gas-assisted sintering at 1475 °C under argon, gentle milling, and fractionation, results in a flowable composite powder. Example 3

[0038] The production of a mixed carbide with the composition (Ti 0,71 Mon 0,10 Nb 0,19 )C 0,85, which is in the form of a powder consisting of particles with an average particle size in the range of 0.5 µm to 5 µm and can be further processed together with at least one powder containing or consisting of at least one metal and / or at least one alloy for the production (or manufacture) of composite powders by agglomeration and sintering, is carried out via a carbothermal reduction of Ti, Mo, niobium oxides, and carbon at 1500 °C under exclusion of air. The resulting powders have an average particle size of 3.5 µm, measured according to DIN ISO 13320:2022-12. Particle size analysis – laser diffraction method, a hardness of 2612 HV 0,01 , determined according to ISO 14705:2016-12. “Advanced performance ceramics – Hardness test of monolithic ceramics at room temperature, a thermal expansion coefficient of 7.0 10 -6 K -1, determined according to DIN 51045-4:2007-01. Determination of the change in length of solid bodies under the influence of heat using the dilatometer method – Part 4: Testing of fired heavy clay materials, a density of 5.2 g / cm 3 , determined according to DIN 66137-2:2019-03. Determination of the density of solids - Part 2: Gas pycnometry and a wettability characterized by a wetting angle of 19° compared to 316 (steel 316 or 316L), whereby the wettability was determined as in Example 1.

[0039] The resulting mixed carbide powder is suspended with 316 powder (or steel 316 or 316L) using a suitable mass preparation process, and flowable granules are obtained via spray granulation. Subsequent heat treatment, including debinding at 400 °C under an H2 atmosphere and pressurized gas-assisted sintering at 1475 °C under argon, gentle milling, and fractionation, results in a flowable composite powder.

Claims

[1] Mixed carbide with a composition according to the formula (Ti x Mon y Me z )C i , where Me is at least one transition metal selected from the group consisting of zirconium, hafnium, vanadium, niobium, tantalum, chromium, tungsten, and mixtures thereof, z is in the range of 0.01 to 0.20, i is in the range from 0.60 to 1.00, and where x + y + z = 1 and the ratio x / y results in a value in the range from 1.5 to 9.

0. [2] Mixed carbide according to the preceding claim, characterized by that the mixed carbide exists as a single-phase cubic phase. [3] Mixed carbide according to one of the preceding claims, characterized by that the mixed carbide is in the form of a powder, the powder preferably consisting of particles having an average particle size in the range from 0.5 µm to 99 µm. [4] Mixed carbide according to claim 3, characterized bythat the powder consists of particles having an average particle size in the range of 25 µm to 90 µm. [5] Mixed carbide according to claim 3, characterized by that the powder consists of particles having an average particle size in the range of 0.5 µm to 5 µm. [6] Mixed carbide according to one of the preceding claims, characterized by that the mixed carbide has a proportion of impurities with at least one elemental metal of < 0.5 wt.%, based on the total weight of the mixed carbide, wherein the at least one elemental metal is preferably selected from the group consisting of cobalt, iron, nickel and mixtures thereof. [7] Mixed carbide according to one of the preceding claims, characterized by that Me is at least one transition metal selected from the group consisting of tungsten, niobium, tantalum, chromium, and mixtures thereof. [8] Mixed carbide according to one of the preceding claims, characterized by, that - x is in the range from 0.48 to 0.89, preferably from 0.52 to 0.88, and / or - y is in the range from 0.08 to 0.40, preferably from 0.09 to 0.37, and / or - z is in the range of 0.05 to 0.

20. [9] Mixed carbide according to one of the preceding claims, characterized by that the mixed carbide - has a hardness in the range of 1500 HV 0.1 to 3000 HV 0.1, preferably from 1900 HV 0.1 to 2700 HV 0.1, and / or - a thermal expansion coefficient in the range of 6.0 10 -6 K -1 up to 9.0 · 10 -6 K -1 , preferably 6.5 · 10 -6 K -1 up to 8.5 · 10 -6 K -1 , and / or - a density in the range of 4.8 g / cm 3 up to 6.5 g / cm 3 , preferably 5.0 g / cm 3 up to 6.3 g / cm 3 , and / or - wettability characterized byhas a wetting angle with respect to a metal melt or metal alloy melt in the range of 10° to 50°, preferably 10° to 30°. [10] Use of the mixed carbide according to claim 4 together with at least one metal and / or at least one metallic alloy for applications in surface technologies, preferably in laser deposition welding and / or powder plasma deposition welding. [11] Use of the mixed carbide according to claim 5 together with at least one metal and / or at least one metallic alloy for the production of composite powders by agglomeration, preferably spray drying, and sintering.