Fecrni-steel alloys as carbide binders

Abstract

In the present disclosure is detailed a powder consisting by total weight of: Iron (Fe) 6.6 - 7.9 wt%, Carbon (C) 5.2 - 5.7 wt%, Chromium (Cr) 3.9 - 4.5 wt%, Nickel (Ni) 2.2 - 3.0 wt%, Molybdenum (Mo) 0.6 - 0.75 wt%, Silicon (Si) 0.1 - 0.22 wt%, Manganese (Mn) 0.07 - 0.1 wt%, the balance being tungsten (W) and unavoidable impurities, which when used in a HVOF and / or a HVAF process provides tungsten carbide embedded in a high-alloyed stainless-steel binder. As the binder is free of cobalt it provides a sustainable yet cost beneficial replacement for conventional binders for carbide products.

Description

[0001] TITLE OF INVENTION

[0002] FeCrNi-steel alloys as carbide binders

[0003] TECHNICAL FIELD

[0004] In the field of powder technology for HVOF and HVAF applications there is suggested a range of stainless-steel alloys as carbide binders for, in particular, tungsten carbide .

[0005] BACKGROUND

[0006] Tungsten / chromium Carbide powders are hard materials (hardness »1000 HV) , used for dense coatings. They can be sprayed using High-Velocity Oxygen-Fuel (HVOF) and High- Velocity Air-Fuel (HVAF) spray methods onto various metallic parts and structures to improve the surface resistance of these parts and structures to severe wear and corrosion. Conventional carbide powders consist of hard WC or CraC2 particles in a binder matrix, for which the CoCr powders are used. Different alloying elements, e.g., Ni, Fe, Ti, etc., may be added to the matrix to improve mechanical, corrosion, and spray-ability properties, c.f. e.g., J. Garcia et al. (J. Garcia, V. Collado Cipres, A. Blomqvist and B. Kaplan, "Cemented carbide microstructures: a review," International Journal of Refractory Metals and Hard Materials, vol. 80, pp. 40-68, 2019.)

[0007] In the recent years, use of some elements, such as Co and Ni in particular, has become of concern due to their harmful characteristics to the environment and health and there have been attempts to replace these elements by less harmful elements in the binder, c.f., e.g., M. Walbriihl et al. (M Walbriihl, D. Linder, K. Agren and A. Borgenstam, "Diffusion modeling in cemented carbides: Solubility assessment for Co, Fe and Ni binder systems," International Journal of Refractory Metals and Hard Materials, vol. 68, pp . 41-48, 2017) .

[0008] It is known that conventional binders can be replaced by high-alloyed steels, or atomized powders, c.f., e.g., J. Garcia et al. Herein, the present inventors introduce new alloys that suitable for use as a binder matrix for in particular as a binder for carbides such as tungsten carbide or diverse chromium carbides, which alloys are sustainable yet cost beneficial replacements for conventional carbide products .

[0009] These newly developed alloys are excellent candidate for coating components e.g., in aerospace or power generating technologies such as e.g., sliding tubes, sliding pistons, axles, bolts, bushings, flanges, etc. The developed alloys can also be used to coat grinding rolls, crushers, and / or calender rolls. In addition, since the alloys are Co-free materials, they can also find use in the food industry, for example for packaging rolls for plastic foils.

[0010] BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1: Phase diagram of agglomerated / sintered carbide, made of 85% WC particles and 15% binder calculated using Thermo-Calc.

[0012] Figure 2: Cross section of agglomerated / sintered carbides, made of 85% WC particles and 15% binder.

[0013] Figure 3: Material consumption versus coverage rate for different spray techniques and parameters, as an index of efficiency and productivity. Figure 4: Cross section of the coating achieved by JP spraying, in different magnifications. A scalebar 50 pm, B scalebar 20 pm.

[0014] Figure 5: Cross section of the coating achieved by DJ spraying, in different magnifications. A scalebar 50 pm, B scalebar 20 pm.

[0015] Figure 6: NSS tested coupons after 1008 hours for A JP- sprayed and B DJ-sprayed samples.

[0016] Figure 7: Gas permeability test results for coated samples.

[0017] Figure 8: Hardness measurements for sprayed samples using different techniques and parameters.

[0018] Figure 9: Roughness measurements for sprayed samples using different techniques and parameters.

[0019] Figure 10: Young modulus measurements for sprayed samples using different techniques and parameters.

[0020] Figure 11: Material consumption for spraying versus war resistance for sprayed samples.

[0021] Figure 12: SEM image and EDX map of elements showing different types of carbides in a Ni-rich FCC matrix .

[0022] Figure 13: Corrosion resistance measures as Cavitation index vs. material used in spraying.

[0023] It is to be understood, that the embodiments shown in the figures are for illustration of the present invention and cannot be construed as being limiting on the present invention. Unless otherwise indicated, the drawings are intended to be read (e.g., cross-hatching, arrangement of parts, proportion, degree, etc.) together with the specification, and are to be considered a portion of the entire written description of this disclosure. DETAILED DESCRIPTION

[0024] In a first aspect and embodiment thereof, there is herein detailed an iron-chrome-nickel stainless-steel alloy consisting by total weight of the alloy of:

[0025] Chromium (Cr) 26.0 - 30.0 wt%

[0026] Nickel (Ni) 15.0 - 18.0 wt%

[0027] Molybdenum (Mo) 4.0 - 5.0 wt%,

[0028] Silicon (Si) 1.00 - 1.50 wt%

[0029] Manganese (Mn) 0.50 - 1.00 wt%

[0030] Carbon (C) 0.15 - 0.25 wt % the balance being iron (Fe) and unavoidable impurities not exceeding 0.3 wt%.

[0031] As detailed in the below experimental section, the stainless- steel alloys of the present invention are useful as sustainable binders for carbides, such as tungsten carbide.

[0032] In general, the amount of unavoidable impurities shall not exceed 0.3 wt% in total, but preferably shall not exceed 0.2 wt%. It is preferred that any individual impurity does not exceed 0.1 wt% by itself and more preferred that any individual impurity does not exceed 0.05 wt% by itself. However, it is a benefit of the present alloys that they are not detrimentally influenced by impurities, which allows for a wider range of sourcing materials for the manufacture of the alloys, such as e.g., fines from metal working.

[0033] In embodiments of the iron-chrome-nickel stainless-steel alloy, chromium (Cr) is present from 26.5 wt%, preferably from 27.0 wt%, more preferably from 27.5 wt% or even more preferably from 28.0 wt%. In further embodiments thereof, chromium (Cr) is present to 29.5 wt%, preferably to 29.0 wt% or more preferably to 28.5 wt%. In embodiments of the iron-chrome-nickel stainless-steel alloy, chromium (Cr) is present from 26.5 wt% to 29.5 wt%, preferably from 27.0 wt% to 29.0 wt%, or even more preferably from 27.5 wt% to 28.5 wt%.

[0034] In embodiments of the iron-chrome-nickel stainless-steel alloy, nickel (Ni) is present from 15.5 wt%, preferably from 16 wt%, or more preferably from 16.5 wt%. In further embodiments thereof, nickel (Ni) is present to 17.5 wt%, preferably to 17 wt%, or more preferably to 16.5 wt%.

[0035] In embodiments of the iron-chrome-nickel stainless-steel alloy, nickel (Ni) is present from 15.5 wt% to 17.5 wt%, preferably from 16.0 wt% to 17.0 wt%, and more preferably from 16.2 wt% to 16.8 wt%.

[0036] In embodiments of the iron-chrome-nickel stainless-steel alloy, molybdenum (Mo) is present from 4.1 wt%, preferably from 4.2 wt%, from 4.25 wt%, more preferably from 4.3 wt%, even more preferably from 4.4 wt%, or most preferably from 4.5 wt%. In further embodiments thereof, molybdenum (Mo) is present to 4.9 wt%, preferably to 4.8 wt%, to 4.75 wt%, more preferably to 4.7 wt%, and most preferably to 4.6 wt% or to 4.5 wt % .

[0037] In embodiments of the iron-chrome-nickel stainless-steel alloy, molybdenum (Mo) is present from 4.1 wt% to 4.9 wt%, preferably from 4.2 wt% to 4.8 wt%, more preferably from 4.3 wt% to 4.7 wt%, even more preferably from 4.4 wt% to 4.6 wt%, and most preferably from 4.45 wt% to 4.55 wt%.

[0038] In embodiments of the iron-chrome-nickel stainless-steel alloy, silicon (Si) is present from 1.10 wt%, preferably 1.15 wt%, more preferably from 1.20 wt%, or most preferably from 1.25 wt%. In further embodiments thereof, silicon (Si) is present to 1.40 wt%, preferably to 1.35 wt%, more preferably to 1.30 wt%, or even more preferably to 1.25 wt%.

[0039] In embodiments of the iron-chrome-nickel stainless-steel alloy, silicon (Si) is present from 1.10 wt% to 1.40 wt%, preferably from 1.15 wt% to 1.35 wt%, more preferably from 1.20 wt% to 1.30 wt%, or most preferably from 1.22 wt% to 1.28 wt% .

[0040] In embodiments of the iron-chrome-nickel stainless-steel alloy, manganese (Mn) is present from 0.60 wt%, preferably from 0.65 wt%, more preferably from 0.70 wt%, or most preferably from 0.75 wt%. In further embodiments thereof, manganese (Mn) is present to 0.90 wt%, preferably to 0.85 wt%, more preferably to 0.80 wt% or most preferably to 0.75 wt% .

[0041] In embodiments of the iron-chrome-nickel stainless-steel alloy, manganese (Mn) is present from 0.60 wt% to 0.90 wt%, preferably from 0.65 wt% to 0.85 wt%, more preferably from 0.70 wt% to 0.80 wt%, or most preferably from 0.72 wt% to 0.78 wt% .

[0042] In embodiments of the iron-chrome-nickel stainless-steel alloy, carbon (C) is present from 0.16 wt%, preferably from 0.17 wt%, more preferably from 0.18 wt%, even more preferably from 0.19 wt%, or most preferably from 0.20 wt%. In embodiments thereof, carbon (C) is present to 0.24 wt%, preferably to 0.23 wt%, more preferably to 0.22 wt%, even more preferably to 0.21 wt%, or most preferably to 0.20 wt%. In these carbon concentration ranges fines from other metal working process advantageously can be used with the present alloys without the risk of rendering the alloys of the invention brittle.

[0043] In embodiments of the iron-chrome-nickel stainless-steel alloy carbon (C) is present from 0.16 wt% to 0.24 wt%, preferably from 0.17 wt% to 0.23 wt%, more preferably from 0.18 wt% to 0.22 wt%, or even more preferably from 0.19 wt% to 0.21 wt% .

[0044] In general, and as is evident e.g., from the phase diagram of Figure 1, the alloys of the present invention are suitable for their intended purpose across all herein given ranges of concentrations of the elements, whether by themselves or in combination with the further elements of the alloy. Consequently, selecting concentration ranges, which are towards the center of the broadest ranges imply moving the thereby selected alloys away from the phase boundaries of the alloys' phase diagram.

[0045] The alloys of the invention preferably can be manufactured by pre-alloying the elements of the alloy, e.g., pre-alloying from a pre-mixed composition of the constituting elements, usually as a powder mixed composition. Generally, the prealloyed alloys of the invention are then subsequently formulated into powders, preferably for HVOF and / or HVAF spray coating, by e.g., atomizing, such as e.g., wateratomizing, the pre-alloyed elements, whereby a pre-alloyed stainless-steel powder suitable for further uses and containing the alloys of the invention is obtained. However, direct formation from a mixed powder of the constituting elements is equally possible, if less practical in use e.g. in HVOF and / or HVAF spray coating. In an embodiment of the pre-alloyed iron-chrome-nickel stainless-steel powder, the pre-alloyed iron-chrome-nickel stainless-steel powder comprises at least 80% by weight of the pre-alloyed iron-chrome-nickel stainless-steel powder contained within a sieved fraction of the pre-alloyed iron- chrome-nickel stainless-steel powder having a si ze distribution from 1 pm to 100 pm, preferably from 2 . 5 pm to 75 pm, or even more preferably from 5 pm to 50 pm, as measured by sieving in accordance with I SO-14232-1-2017-E , Particle distribution by sieving, and / or preferably comprises at least 85% by weight , at least 90% by weight , or more preferably at least 95% by weight of the pre-alloyed iron-chrome-nickel stainless-steel powder having a si ze distribution from 2 . 5 pm to 100 pm as measured by sieving in accordance with I SO- 14232-1-2017-E , Particle distribution by sieving .

[0046] An advantage of the alloys of the present invent ion is that when formulated as powder having a powder si ze suitable for HVOF and / or HVAF spray coating, they can be mixed with carbide powders , equally of a powder si ze suitable for HVOF and / or HVAF spray coating, and then the mixed powder can be spray coated directly onto a suitable surface for providing a binder alloy containing carbides on the said surface .

[0047] The benefits of the invention are exemplified herein below in the context of an agglomerated / sintered carbide product is , made from 85 wt% WC particles and 15 wt% binder . The binder and carbides are dry sprayed together and sintered at constant temperature of 1138 ° C for maximum two hours , thereby forming the desired tungsten carbide / stainless-steel alloy complex . Chemical composition element ranges for the forming of suitable tungsten carbide / stainless-steel alloy complexes are given in Table 1 below . Table 1 : WC / alloy complexes , Tungsten (W) balance

[0048] Consequently, in an embodiment there is herein detailed a powder comprising a pre-alloyed binder powder of an iron- chrome-nickel stainless-steel alloy in an embodiment as herein detailed above , the powder further comprising a metal carbide powder .

[0049] It is a maj or advantage of the alloys of the present invention that these can be formulated as pre-alloyed binder powders and desired amounts of metal carbide powders added, e . g . , by in-mixing . This not only broadens the range and the composition of metal carbide powders , which can be added, making the hard-coatings independent on the formation chemistry of the constituent powders , but also it allows for lower deposition temperatures , since rather than providing coating temperatures necessary for metal carbide formation, it is now only necessary to provide energy for melting prealloyed binder powder and not the metal carbides .

[0050] The actual concentration and composition of the metal carbide powder in the final pre-alloyed binder powder composition will normally be at the discretion of an end-user . However, in embodiments of the pre-alloyed binder composition the at least one metal carbide is selected from one or more powders of a nickel carbide , a chromium carbide , a vanadium carbide , a tungsten carbide (WC) , a molybdenum carbide, a silicon carbide, a manganese carbide, an aluminum carbide, a titanium carbide, a niobium carbide, a tantalum carbide, a hafnium carbide, or a zirconium carbide, preferably is selected from one or more of a nickel carbide, a chromium carbide, a vanadium carbide, a tungsten carbide (WC) , a molybdenum carbide, a silicon carbide, a manganese carbide, or an aluminum carbide, more preferably is selected from one or more of a nickel carbide, a chromium carbide, a vanadium carbide, a molybdenum carbide, or a tungsten carbide (WC) , most preferably a tungsten carbide (WC) .

[0051] For the uses to which the present iron-chrome-nickel stainless-steel alloys with tungsten carbide (WC) are commercially intended by the present applicant, the present inventors have established that, optimally, tungsten carbide shall be present in the Ni-based powder compositions of the present invention from 83 wt% to 87 wt%, but preferably about 85 wt%.

[0052] Accordingly, in a further aspect of the present invention, there is herein detailed a powder for forming an iron-chrome- nickel stainless-steel alloy, the powder consisting by total weight of:

[0053] Chromium (Cr) 26.0 - 30.0 wt%

[0054] Nickel (Ni) 15.0 - 18.0 wt %

[0055] Molybdenum (Mo) 4.0 - 5.0 wt%,

[0056] Silicon (Si) 1.00 - 1.50 wt %

[0057] Manganese (Mn) 0.50 - 1.00 wt%

[0058] Carbon (C) 0.15 - 0.25 wt % the balance being iron (Fe) and unavoidable impurities not exceeding 0.3 wt%. In embodiments thereof, chromium (Cr) is present from 26.5 wt%, preferably from 27.0 wt%, or more preferably from 27.5 wt%; and / or wherein chromium is present to 29.5 wt%, preferably to 29.0 wt%, or more preferably to 28.5 wt%.

[0059] In embodiments thereof, nickel (Ni) is present from 15.5 wt%, preferably from 16.0 wt%, or more preferably from 16.5 wt%; and / or wherein nickel (Ni) is present to 17.5 wt%, or preferably to 17.0 wt%.

[0060] In embodiments thereof, molybdenum (Mo) is present from 4.1 wt%, preferably from 4.2 wt%, more preferably from 4.3 wt%, even more preferably from 4.4 wt%, or most preferably from 4.5 wt%; and / or wherein molybdenum (Mo) is present to 4.9 wt%, preferably to 4.8 wt%, more preferably to 4.7 wt%, or most preferably to 4.6 wt%.

[0061] In embodiments thereof, silicon (Si) is present from 1.10 wt%, preferably from 1.15 wt%, more preferably from 1.20 wt%, or most preferably from 1.25 wt%; and / or wherein silicon (Si) is present to 1.40 wt%, preferably to 1.35 wt%, or more preferably to 1.30 wt%.

[0062] In embodiments thereof, manganese (Mn) is present from 0.60 wt%, preferably from 0.65 wt%, more preferably from 0.70 wt%, or most preferably from 0.75 wt%; and / or wherein manganese (Mn) is present to 0.90 wt%, preferably to 0.85 wt%, or more preferably to 0.80 wt%.

[0063] In embodiments thereof, carbon (C) is present from 0.16 wt%, preferably from 0.17 wt%, more preferably from 0.18 wt%, even more preferably from 0.19 wt%, or most preferably from 0.20 wt%; and / or wherein carbon (C) is present to 0.24 wt%, preferably to 0 . 23 wt% , more preferably to 0 . 22 wt% , or most preferably to 0 . 21 wt% .

[0064] In a further aspect , there is herein detailed an iron-chrome- nickel stainless-steel alloy according to any of the above embodiments , formed by alloying a powder according to any herein detailed above embodiments .

[0065] In a further aspect , there is herein detailed the iron- chrome-nickel stainless-steel alloy is a pre-alloyed stainless-steel powder .

[0066] In an embodiment of the pre-alloyed iron-chrome-nickel stainless-steel powder, the pre-alloyed stainless-steel powder comprises at least 80% by weight of the pre-alloyed stainless-steel powder contained within a sieved fraction of the pre-alloyed stainless-steel powder having a si ze distribution from 1 pm to 100 pm, preferably from 2 . 5 pm to 75 pm, or even more preferably from 5 pm to 50 pm, as measured by sieving in accordance with I SO-14232-1-2017-E , Particle distribution by sieving, and / or preferably comprises at least 85% by weight , at least 90% by weight , or more preferably at least 95% by weight of the pre-alloyed stainless-steel powder having a si ze distribution from 2 . 5 pm to 100 pm as measured by sieving in accordance with I SO-14232-1-2017-E , Particle distribution by sieving .

[0067] In further embodiments of the powder comprising a pre-alloyed iron-chrome-nickel stainless-steel powder of an iron-chrome- nickel stainless-steel alloy, the powder further comprises a metal carbide powder . In preferred embodiments thereof , the metal carbide powder is selected from one or more powders of a nickel carbide , a chromium carbide , a vanadium carbide , a tungsten carbide , a molybdenum carbide , a silicon carbide , a manganese carbide, an aluminum carbide, a titanium carbide, a niobium carbide, a tantalum carbide, a hafnium carbide, or a zirconium carbide; preferably is selected from one or more of a nickel carbide, a chromium carbide, a vanadium carbide, a tungsten carbide, a molybdenum carbide, a silicon carbide, a manganese carbide, or an aluminum carbide; more preferably is selected from one or more of a nickel carbide, a chromium carbide, a vanadium carbide, a tungsten carbide (WC) , or a molybdenum carbide; or most preferably is tungsten carbide (WC) .

[0068] In even more preferred embodiments thereof, powder comprising a pre-alloyed iron-chrome-nickel stainless-steel powder, the powder contains from 13 wt% to 17 wt% of an iron-chrome- nickel stainless-steel pre-alloyed powder and from 83 to 87 wt% of a tungsten carbide (WC) powder; most preferably 15 wt% of an iron-chrome-nickel stainless-steel pre-alloyed powder and 85 wt% of a tungsten carbide (WC) powder.

[0069] In preferred embodiments, the powder comprises at least 80% by weight of the tungsten carbide (WC) powder contained within a sieved fraction of the tungsten-based powder having a size distribution from 1 pm to 100 pm, preferably from 2.5 pm to 75 pm, or even more preferably from 5 pm to 50 pm, as measured by sieving in accordance with ISO-14232-1-2017-E, Particle distribution by sieving, and / or preferably comprises at least 85% by weight, at least 90% by weight, or more preferably at least 95% by weight of the tungsten-based powder having a size distribution from 2.5 pm to 100 pm as measured by sieving in accordance with ISO-14232-1-2017-E, Particle distribution by sieving.

[0070] Surprisingly, the present inventors have established experimentally (c.f. below) that by thermal spraying of a tungsten-based powder composition as detailed herein below, it is possible to form the iron-chrome-nickel stainless-steel binder alloys of the present disclosure concomitantly with primarily metal carbides of tungsten (and some minor amounts of chromium carbides) . The iron-chrome-nickel stainless- steel binder alloys then deposit from the gas-phase containing inclusions of the desired tungsten carbides in high amounts.

[0071] Accordingly, in a second aspect of the present invention and embodiments thereof, there is herein detailed a tungsten- based powder consisting by total weight of powder of:

[0072] Iron (Fe) 6.6 - 7.9 wt%

[0073] Carbon (C) 5.2 - 5.7 wt %

[0074] Chromium (Cr) 3.9 - 4.5 wt %

[0075] Nickel (Ni) 2.2 - 3.0 wt %

[0076] Molybdenum (Mo) 0.60 - 0.75 wt%

[0077] Silicon (Si) 0.10 - 0.22 wt%

[0078] Manganese (Mn) 0.07 - 0.10 wt % the balance being tungsten (W) and unavoidable impurities not exceeding 0.3 wt%.

[0079] In an embodiment of the tungsten-based powder, the content of carbon (C) is from 5.25 to 5.7 wt%, from 5.3 to 5.7 wt%, or from 5.5 to 5.7 wt%; preferably from 5.35 to 5.7 wt%, from 5.35 to 5.65 wt%, from 5.4 to 5.65 wt%, or from 5.45 to 5.65 wt%; or more preferably from 5.5 to 5.6 wt%.

[0080] In an embodiment of the present invention, the tungsten-based powder of the invention is alloyed, whereby is formed an iron-chrome-nickel stainless-steel alloy of the present invention according to one of the embodiments of the iron- chrome-nickel stainless-steel alloy detailed above, together with various metal carbides, but primarily tungsten carbide. The resulting alloy with inclusions (c.f. Figure 2) contains the iron-chrome-nickel stainless-steel alloy as a binder with inclusions of the formed carbides. As such, a tungsten-based powder as detailed above can serve as a precursor for obtaining the iron-chrome-nickel stainless-steel alloys of the present invention after alloying.

[0081] In an embodiment of the tungsten-based powder, the content of nickel (Ni) is from 2.2 to 2.7 wt%. Preferably, nickel (Ni) is from 2.3 to 2.6 wt%, or more preferably from 2.4 to 2.5 wt % .

[0082] In an embodiment of the tungsten-based powder, the content of iron (Fe) is from 6.8 wt% to 7.7 wt%, preferably from 7.0 wt% to 7.5 wt%, or more preferably from 7.2 wt% to 7.4 wt%.

[0083] In an embodiment of the tungsten-based powder, the content of chrome (Cr) is from 4.0 wt% to 4.4 wt%, preferably from 4.1 wt% to 4.3 wt%.

[0084] As concerns the further alloying elements of molybdenum (Mo) , silicon (Si) and manganese (Mn) , these can be varied freely within their maximum ranges. Their presence, however, remain mandatory or the iron-chrome-nickel stainless-steel alloy of the present invention cannot form during alloying of a tungsten-based powder of the present invention as disclosed above .

[0085] In some embodiments, however, the content of molybdenum (Mo) can be from 0.61 wt%, from 0.63 wt%, or preferably from 0.65 wt%; and / or the content of molybdenum can be to 0.74 wt%, to 0.72 wt%, or preferably to 0.70 wt%. In other embodiments, however, the content of silicon (Si) can be from 0.11 wt%, from 0.12 wt% from 0.13 wt%, or preferably from 0.14 wt%; and / or the content of silicon (Si) can be to 0.21 wt%, to 0.20 wt%, 0.19 wt%, or preferably to 0.18 wt% .

[0086] In further embodiments, however, the content of manganese (Mn) is from 0.075 wt% or from 0.80 wt%; and / or the content of manganese (Mn) is to 0.095 wt% or to 0.090 wt%.

[0087] The tungsten-based powder can be obtained using methods otherwise known as such, e.g., by atomizing the constituting metals as a composite powder, or from a melt by partially or, preferably, fully alloying the constituting metals. In the event of the partial alloy powder or non-pre-alloyed metal powder is used, the alloying takes place during the application (e.g., spray application) of the cermet powders.

[0088] In an embodiment of the tungsten-based powder, the tungsten- based powder consists of from 13 to 17 wt% of a stainless- steel pre-alloyed powder according to the above first aspect and embodiments thereof, and from 83 to 87 wt% of a tungsten carbide (WC) powder.

[0089] In an embodiment of the tungsten-based powder, the tungsten- based powder comprises at least 80% by weight of the tungsten-based powder contained within a sieved fraction of the tungsten-based powder having a size distribution from 1 pm to 100 pm, preferably from 2.5 pm to 75 pm, or even more preferably from 5 pm to 50 pm, as measured by sieving in accordance with ISO-14232-1-2017-E, Particle distribution by sieving, and / or preferably comprises at least 85% by weight, at least 90% by weight, or more preferably at least 95% by weight of the tungsten-based powder having a size distribution from 2 . 5 pm to 100 pm as measured by sieving in accordance with I SO-14232-1-2017-E , Particle distribution by sieving .

[0090] In an embodiment thereof , the tungsten-based powder comprises at least 90% by weight of the tungsten-based powder contained within a sieved fraction of the tungsten-based powder having a si ze distribution from 5 pm to 25 pm as measured by sieving in accordance with I SO-14232-1-2017-E , Particle distribution by sieving . In preferred embodiments thereof , the tungsten- based powder comprises at least 95% by weight , at least 97% by weight , or more preferably at least 99% by weight , or even more preferably at least 99 . 5% by weight contained within a sieved fraction of the tungsten-based powder having a si ze distribution from 5 pm to 25 pm as measured by sieving in accordance with I SO-14232-1-2017-E , Particle distribution by sieving .

[0091] In an embodiment thereof , the tungsten-based powder comprises at least 90% by weight of the tungsten-based powder contained within a sieved fraction of the tungsten-based powder having a si ze distribution from 15 pm to 45 pm as measured by sieving in accordance with I SO-14232-1-2017-E , Particle distribution by sieving . In preferred embodiments thereof , the tungsten- based powder comprises at least 95% by weight , at least 97% by weight , or more preferably at least 99% by weight , or even more preferably at least 99 . 5% by weight contained within a sieved fraction of the tungsten-based powder having a si ze distribution from 5 pm to 25 pm as measured by sieving in accordance with I SO-14232-1-2017-E , Particle distribution by sieving .

[0092] In an aspect of the present invention, the tungsten-based powder is a cermet powder consisting of from 83 wt% to 87 wt% of the total mass of the powder provided as a pre-formed tungsten carbide (WC) powder and from 13 wt% to 17 wt% of the total mass of the powder provided as a stainless-steel pre-alloyed powder according to any aspect thereof detailed herein above .

[0093] In an embodiment thereof , the cermet powder comprises at least 80% by weight of the cermet powder contained within a sieved fraction of the cermet powder having a si ze distribution from 1 pm to 100 pm, preferably from 2 . 5 pm to 75 pm, or even more preferably from 5 pm to 50 pm, as measured by sieving in accordance with I SO-14232-1-2017-E , Particle distribution by sieving, and / or preferably comprises at least 85% by weight , at least 90% by weight , or more preferably at least 95% by weight of the cermet powder having a si ze distribution from 2 . 5 pm to 100 pm as measured by sieving in accordance with I SO-14232-1-2017-E , Particle distribution by sieving .

[0094] In an aspect of the present invention, there is herein detailed the use of a tungsten-based or a cermet powder according to any one of embodiments detailed herein for the coating of a surface by means of a thermal spray method .

[0095] Further detailed herein is a cermet formed from a tungsten- based or a cermet powder according to any one of embodiments detailed herein by means of a thermal spray method, preferably a cermet having a composition corresponding to any composition of the herein disclosed tungsten-based or cermet powders .

[0096] Accordingly, there is herein detailed a cermet powder consisting of from 83 wt% to 87 wt% of the total mass of the powder provided as a pre-formed tungsten carbide (WC) powder and from 13 wt% to 17 wt% of the total mass of the powder provided as a stainless-steel pre-alloyed powder according to the herein detailed embodiments ; preferably consisting of 85 wt% of the total mass of the powder provided as a preformed tungsten carbide (WC) powder and 15 wt% of the total mass of the powder provided as a stainless-steel pre-alloyed powder according to the herein detailed embodiments .

[0097] In a preferred embodiment thereof , the cermet powder comprises at least 80% by weight of the cermet powder contained within a sieved fraction of the cermet powder having a si ze di stribution from 1 pm to 100 pm, preferably from 2 . 5 pm to 75 pm, or even more preferably from 5 pm to 50 pm, as measured by sieving in accordance with I SO-14232- 1-2017-E , Particle distribution by sieving, and / or preferably comprises at least 85% by weight , at least 90% by weight , or more preferably at least 95% by weight of the cermet powder having a si ze distribution from 2 . 5 pm to 100 pm as measured by sieving in accordance with I SO-14232-1- 2017-E , Particle distribution by sieving .

[0098] In a further aspect , there is herein detailed the use of a tungsten-based powder according to any one of the herein detailed embodiments for the coating of a surface by means of a thermal spray method .

[0099] In a further aspect , there is herein detailed a composition comprising an iron-chrome-nickel stainless-steel alloy and tungsten carbide (WC) formed by alloying a tungsten-based powder according to any of the herein detailed embodiments .

[0100] In a preferred composition thereof , the tungsten carbide (WC) is present as inclusions in a Ni-rich FCC-stainless-steel matrix . Further detailed herein is a shaped object having a coating with a cermet according to any embodiment of the herein detailed cermets .

[0101] Further detailed herein is a method for the production of a cermet according to any embodiment of the herein detailed cermet , or of a shaped object according to any of the herein detailed embodiments , the method having the steps : provision of a tungsten-based or cermet powder according to one or more of herein detailed embodiments in a form or formulation that is suitable for thermal spraying; carrying out of a thermal spraying process using the powder; obtaining of the cermet , or of the object .

[0102] EXPERIMENTAL

[0103] Coating properties were tested for different HVOF spray parameters .

[0104] HVOF thermal spray systems use different fuels to produce coating for industrial machines ' parts . The resulting coatings in general are hard, thick, and dense . In this work, two different jet guns were used for thermal spraying of the samples : Diamond jet gun (DJ) , and high-pressure jet gun ( JP ) . The fuel for the DJ consisted of O2+H2+air and for the JP it was a mixture of oxygen and argon .

[0105] The high-pressure jet gun ( JP-5000 ) is designed for liquidfuel (kerosene ) and oxygen operation . Fuel and oxygen are fed into the gun, atomi zed by the coaxial stabili zer, and ignited in the combustion chamber, resulting in a supersonic flame . Spray powder from the powder feeder is fed radially into the supersonic flame through two powder ports positioned directly after the combustion chamber . The spray stream is accelerated through a converging / diverging noz z le several times the speed of sound . The spray particles are heated to a molten or semi-molten state and propelled at high velocity, impacting the coating surface in a plastic state . Table 2 provides an overview of the spray parameters used in the present experiments .

[0106] Table 2 : Spray parameters for high-pressure jet gun (JP-5000)

[0107] The DiamondJet process uses oxygen, fuel gas and air to produce a high-pressure annular flame , which provides uniform heating of the axially introduced powder spray material . The gas stream is accelerated through a converging / diverging noz z le to supersonic speeds . The gas stream propels the powder particles towards the substrate . Individual particles deform plastically upon impact , tenaciously bonding the coating to the substrate . Table 3 details the spray parameters used for the present experiments .

[0108] Table 3 : Spray parameters for Diamond jet gun

[0109] Different spray parameters were tested, e.g., powder feeder, nozzle size, combustion pressure, etc., c.f., Tables 2 and 3. Parameters were adjusted in a way that a dense coating with optimal deposition efficiency is achieved. These parameters are general ones used and producible in any ordinary spray shop. Separate coupons were sprayed with the same parameters for different tests.

[0110] Powder sizes were determined in accordance with ISO-14232 - 1-2017-E Particle distribution by sieving and are stated as 95% of the powder mass falling inside the given size exclusion interval.

[0111] Hardness, roughness, gas permeability, Young's modulus, and wear resistance were measured for each spray parameter.

[0112] After spraying, coated samples were analyzed with optical microscope to measure the coating thickness and porosity and additionally examined using electron microscopy.

[0113] In further tests, the carbon content of samples was measured after spraying. As will be further discussed below, the content of carbon is sensitive for the herein disclosed alloys and for their suitability for use as binders as discussed herein .

[0114] Another set of coupons were placed in the natural salt spray chamber and evaluated after specific periods of time to study the corrosion properties . Corrosion resistance of the material was also evaluated based on gas permeability and cavitation tests , c . f . Figure 13 .

[0115] Finally, coated samples were analyzed using SEM / EDX analysis to find a better understanding of the final product .

[0116] Calphad-based calculation

[0117] Figure 1 shows the phase diagram for the presently developed alloys as calculated using Thermo-Calc software , steel database TCFE12 .

[0118] Composition range marked with green lines in the figure shows composition range of carbon content for the final carbide in wt% , which will result in cubic carbides as hard phase in an FCC matrix as binder .

[0119] Although this composition range is wider than the one suggested in table 1 , carbon burn out during thermal spraying should be considered .

[0120] I f the lower limit of this range i s taken for the composition ( »5 . 2 wt% ) , after carbon burns out , the composition will be shifted to the phase field containing MgC, known as q-carbide which is a brittle phase with low corrosion resistance .

[0121] Optimal carbon content requires a narrower window for these alloys for avoiding formation of q-carbide after spraying . The arrow in Figure 1 shows the optimal concentration range for carbon, wherein, even after burning out , the coating' s chemical composition will be as desired, when the coating takes place at about 1200 ° C .

[0122] Sprayed coupons

[0123] Figure 2 shows (EM) a cross section of the agglomerated / sintered carbides , wherein the product examined was made of 85 wt% WC particles and 15 wt% binder . Dark cubic WC carbides can be seen in a sintered binder with l ight color in this figure .

[0124] Sprayed coupons were cut and analyzed by a LEICA DM6 M light optical microscope , to measure the coating thickness and porosity .

[0125] Figure . 3 shows indexes correlated to deposition efficiency and coating' s thickness for different spraying methods and parameters . Other products (named Amperit® 618 (WC 15FeCrAl ) and 558 (WC 10Co4Cr) ) are compared with this product .

[0126] Most of the trails for this product fall in the high- product ivity / high-ef f iciency area of the plot ( compatible with, and in some cases better than the existing products ) which shows that this product is cost-beneficial for spraying, through which a dense coating can be achieved .

[0127] Figures 4 and 5 show cross section of the coating using JP and DJ techniques respectively . Using both techniques a dense even coating can be achieved with 0 . 1-0 . 5 % porosity, which is on par or better than what can be achieved with to existing commercial products . The carbon content of all the samples was measured using a Leco ; CS-200 / CS- 600 apparatus based on non-dispersive infrared absorption after burning in an oxygen flow . Results confirm that all samples contain more than 5 . 3 wt% carbon and, consequently, did not suffer from carbon burnup during spraying .

[0128] Corrosion Properties

[0129] Corrosion properties of the coating were studied by natural salt spray (NSS ) test using a SC1000 Weiss GmbH machines according to standard ASTM B117 . Samples were placed in the chamber and inspected after specific times , i . e . , after 168 , 336 , 504 , 672 , 840 and 1008 hours . Figure 6 shows the tested coupons after 1008 hours for both techniques and barely any rust on the surface can be seen on them after completion of the study period . Slight corrosion has happened in the mounting area which is expected as salt can di ffuse and accumulate there .

[0130] Gas Permeability

[0131] Gas permeability test results (measured using a GPT-03 machine in accordance with standard I SO 4022 ) are shown in Figure 7 for the coated samples . Possibly, the gas permeability results corroborate the excellent corrosion resistance , as they show that these coatings are very dense , and that gas ( and by comparison liquid salt solutions ) cannot easily penetrate and attack the sample and base material even at high pressures .

[0132] Mechanical Properties Mechanical properties of the coatings were measured. Results for hardness, roughness and Young's modulus are shown in Figures 8 to 10.

[0133] Hardness is generally an important factor when selecting between different classes of carbides. In the present work, Hardness (HV) was measured using a Struers Dura Scan machine according to standard ISO 6507,1-4:2018.

[0134] Hardnesses for tungsten carbides are generally expected to be above 1000 HV. The present product shows a general hardness of »1200 HV, which makes it an excellent candidate for the intended applications.

[0135] Roughness of coated samples were measured based on standards DIN EN ISO 4287 and ASME B46.1, using a MarSurf PS10 machine. The results presented in Figure 9 show an average value of 2-4 Ra for this product which is in the general accepted range for this property among different carbides (c.f., J. Garcia et al . ) .

[0136] Young' s modulus represents elastic properties of material and is correlated to hardness. The measurements were done using a LA-wave V2-1 Fraunhofer IWS apparatus. The average value of 240-290 GPa (Figure 10) is expected for a hard material and makes it a good candidate for applications where heavy loading is applied.

[0137] Wear resistance of the coated samples was measured according to ASTM G65 (Figure 11) using a built-in machine. Volume loss is shown versus material consumption for spraying in this figure . Figure 11 shows that all coatings show excellent wear resistance , i . e . , very low volume loss for medium powder consumption in comparison with Amperit® 618 and 558 . This makes the present product significantly beneficial from cost point of view and a strong candidate for application where wear properties play an important role .

[0138] SEM Analysis

[0139] A Hitachi SU6600 Scanning Electron Microscope was used to analyze coated samples . Figure 12 shows the cross section together with EDX map for high-content elements , using voltage of 15kV . The results are aligned with thermodynamic calculation, i . e . , different types of carbides in a Ni-rich FCC stainless-steel matrix .

[0140] CLOS ING COMMENTS

[0141] Although the present invention has been described in detail for purpose of illustration, it is understood that such detail is solely for that purpose , and variations can be made therein by those skilled in the art in practicing the claimed subject matter, from a study of the drawings , the disclosure , and the appended claims .

[0142] The term " compris ing" as used in the claims does not exclude other elements or steps . The indefinite article "a" or "an" as used in the claims does not exclude a plurality . A unit may fulfill the functions of several means recited in the claims . A reference sign used in a claim shal l not be construed as limiting the scope .

Claims

CLAIMS1. An iron-chrome-nickel stainless-steel alloy consisting by total weight of alloy of: Chromium (Cr) : 26.0 - 30.0 wt%, Nickel (Ni) : 15.0 - 18.0 wt % , Molybdenum (Mo) : 4.0 - 5.0 wt%, Silicon (Si) : 1.00 - 1.50 wt % ,Manganese (Mn) : 0.50 - 1.00 wt%, Carbon (C) : 0.15 - 0.25 wt % , the balance being iron (Fe) and unavoidable impurities not exceeding 0.3 wt%.

2. An iron-chrome-nickel stainless-steel alloy according to claim 1, wherein chromium (Cr) is present from 26.5 wt%, preferably from 27.0 wt%, or more preferably from 27.5 wt%; and / or wherein chromium is present to 29.5 wt%, preferably to 29.0 wt%, or more preferably to 28.5 wt%.

3. An iron-chrome-nickel stainless-steel alloy according to either claim 1 or claim 2, wherein nickel (Ni) is present from 15.5 wt%, preferably from 16.0 wt%, or more preferably from 16.5 wt%; and / or wherein nickel (Ni) is present to 17.5 wt%, or preferably to 17.0 wt%.

4. An iron-chrome-nickel stainless-steel alloy according to any preceding claim, wherein molybdenum (Mo) is present from 4.1 wt%, preferably from 4.2 wt%, more preferably from 4.3 wt%, even more preferably from 4.4 wt%, or most preferably from 4.5 wt%; and / or wherein molybdenum (Mo) is present to 4.9 wt%, preferably to 4.8 wt%, more preferably to 4.7 wt%, or most preferably to 4.6 wt%.

5. An iron-chrome-nickel stainless-steel alloy according to any preceding claim, wherein silicon (Si) is present from 1.10 wt%, preferably from 1.15 wt%, more preferably from 1.20 wt%, or most preferably from 1.25 wt%; and / or wherein silicon (Si) is present to 1.40 wt%, preferably to 1.35 wt%, or more preferably to 1.30 wt%.

6. An iron-chrome-nickel stainless-steel alloy according to any preceding claim, wherein manganese (Mn) is present from 0.60 wt%, preferably from 0.65 wt%, more preferably from 0.70 wt%, or most preferably from 0.75 wt%; and / or wherein manganese (Mn) is present to 0.90 wt%, preferably to 0.85 wt%, or more preferably to 0.80 wt%.

7. An iron-chrome-nickel stainless-steel alloy according to any preceding claim, wherein carbon (C) is present from 0.16 wt%, preferably from 0.17 wt%, more preferably from 0.18 wt%, even more preferably from 0.19 wt%, or most preferably from 0.20 wt%; and / or wherein carbon (C) is present to 0.24 wt%, preferably to 0.23 wt%, more preferably to 0.22 wt%, or most preferably to 0.21 wt%.

8. The iron-chrome-nickel stainless-steel alloy of any of the claims 1 to 7 as a pre-alloyed stainless-steel powder.

9. A pre-alloyed stainless-steel powder according to claim 8, wherein the pre-alloyed stainless-steel powder comprises at least 80% by weight of the pre-alloyed stainless-steel powder contained within a sieved fraction of the pre-alloyed stainless-steel powder having a size distribution from 1 pm to 100 pm, preferably from 2.5 pm to 75 pm, or even more preferably from 5 pm to 50 pm, as measured by sieving in accordance with ISO-14232-1-2017- E, Particle distribution by sieving, and / or preferablycomprises at least 85% by weight, at least 90% by weight, or more preferably at least 95% by weight of the prealloyed stainless-steel powder having a size distribution from 2.5 pm to 100 pm as measured by sieving in accordance with ISO-14232-1-2017-E, Particle distribution by sieving .

10. A powder comprising a pre-alloyed powder according to either claim 8 or claim 9 of an iron-chrome-nickel stainless-steel alloy according to any of the claims 1 to 7, the powder further comprising a metal carbide powder .

11. A powder comprising a pre-alloyed stainless-steel powder according to claim 10, wherein the metal carbide powder is selected from one or more powders of a nickel carbide, a chromium carbide, a vanadium carbide, a tungsten carbide, a molybdenum carbide, a silicon carbide, a manganese carbide, an aluminum carbide, a titanium carbide, a niobium carbide, a tantalum carbide, a hafnium carbide, or a zirconium carbide; preferably is selected from one or more of a nickel carbide, a chromium carbide, a vanadium carbide, a tungsten carbide, a molybdenum carbide, a silicon carbide, a manganese carbide, or an aluminum carbide; more preferably is selected from one or more of a nickel carbide, a chromium carbide, a vanadium carbide, a tungsten carbide (WC) , or a molybdenum carbide; or most preferably is tungsten carbide (WC) .

12. A powder comprising a pre-alloyed stainless-steel powder according to any of the claims 10 or 11, wherein the powder contains from 13 wt% to 17 wt% of an iron-chrome- nickel stainless-steel pre-alloyed powder according toeither claim 8 or claim 9, and from 83 to 87 wt% of a tungsten carbide (WC) powder; preferably 15 wt%, of an iron-chrome-nickel stainless-steel pre-alloyed powder according to either claim 8 or claim 9, and 85 wt% of a tungsten carbide (WC) powder.

13. A powder comprising a pre-alloyed stainless-steel powder according to claim 12, wherein the powder comprises at least 80% by weight of the tungsten carbide (WC) powder contained within a sieved fraction of the tungsten-based powder having a size distribution from 1 pm to 100 pm, preferably from 2.5 pm to 75 pm, or even more preferably from 5 pm to 50 pm, as measured by sieving in accordance with ISO-14232-1-2017-E, Particle distribution by sieving, and / or preferably comprises at least 85% by weight, at least 90% by weight, or more preferably at least 95% by weight of the tungsten-based powder having a size distribution from 2.5 pm to 100 pm as measured by sieving in accordance with ISO-14232-1-2017-E, Particle distribution by sieving.

14. A powder for forming an iron-chrome-nickel stainless- steel alloy, the powder consisting by total weight of: Chromium (Cr) : 26.0 - 30.0 wt%, Nickel (Ni) : 15.0 - 18.0 wt % , Molybdenum (Mo) : 4.0 - 5.0 wt%, Silicon (Si) : 1.00 - 1.50 wt % ,Manganese (Mn) : 0.50 - 1.00 wt%,Carbon (C) : 0.15 - 0.25 wt % , the balance being iron (Fe) and unavoidable impurities not exceeding 0.3 wt%.

15. A powder for forming an iron-chrome-nickel stainless- steel alloy according to claim 14, wherein chromium (Cr)is present from 26.5 wt%, preferably from 27.0 wt%, or more preferably from 27.5 wt%; and / or wherein chromium is present to 29.5 wt%, preferably to 29.0 wt%, or more preferably to 28.5 wt%.

16. A powder for forming an iron-chrome-nickel stainless- steel alloy according to either claim 14 or claim 15, wherein nickel (Ni) is present from 15.5 wt%, preferably from 16.0 wt%, or more preferably from 16.5 wt%; and / or wherein nickel (Ni) is present to 17.5 wt%, or preferably to 17.0 wt% .

17. A powder for forming an iron-chrome-nickel stainless- steel alloy according to any of the claims 14 to 16, wherein molybdenum (Mo) is present from 4.1 wt%, preferably from 4.2 wt%, more preferably from 4.3 wt%, even more preferably from 4.4 wt%, or most preferably from 4.5 wt%; and / or wherein molybdenum (Mo) is present to 4.9 wt%, preferably to 4.8 wt%, more preferably to 4.7 wt%, or most preferably to 4.6 wt%.

18. A powder for forming an iron-chrome-nickel stainless- steel alloy according to any of the claims 14 to 17, wherein silicon (Si) is present from 1.10 wt%, preferably from 1.15 wt%, more preferably from 1.20 wt%, or most preferably from 1.25 wt%; and / or wherein silicon (Si) is present to 1.40 wt%, preferably to 1.35 wt%, or more preferably to 1.30 wt%.

19. A powder for forming an iron-chrome-nickel stainless- steel alloy according to any of the claims 14 to 18, wherein manganese (Mn) is present from 0.60 wt%, preferably from 0.65 wt%, more preferably from 0.70 wt%, or most preferably from 0.75 wt%; and / or whereinmanganese (Mn) is present to 0.90 wt%, preferably to 0.85 wt%, or more preferably to 0.80 wt%.

20. A powder for forming an iron-chrome-nickel stainless- steel alloy according to any of the claims 14 to 19, wherein carbon (C) is present from 0.16 wt%, preferably from 0.17 wt%, more preferably from 0.18 wt%, even more preferably from 0.19 wt%, or most preferably from 0.20 wt%; and / or wherein carbon (C) is present to 0.24 wt%, preferably to 0.23 wt%, more preferably to 0.22 wt%, or most preferably to 0.21 wt%.

21. An iron-chrome-nickel stainless-steel alloy according to any of the claims 1 to 7 formed by alloying a powder according to any of the claims 14 to 20.

22. An iron-chrome-nickel stainless-steel alloy according to claim 21 as a pre-alloyed stainless-steel powder.

23. A pre-alloyed iron-chrome-nickel stainless-steel powder according to claim 21, wherein the pre-alloyed stainless- steel powder comprises at least 80% by weight of the prealloyed stainless-steel powder contained within a sieved fraction of the pre-alloyed stainless-steel powder having a size distribution from 1 pm to 100 pm, preferably from 2.5 pm to 75 pm, or even more preferably from 5 pm to 50 pm, as measured by sieving in accordance with ISO-14232-1-2017-E, Particle distribution by sieving, and / or preferably comprises at least 85% by weight, at least 90% by weight, or more preferably at least 95% by weight of the pre-alloyed stainless-steel powder having a size distribution from 2.5 pm to 100 pm as measured by sieving in accordance with ISO-14232-1- 2017-E, Particle distribution by sieving.

24. A powder comprising a pre-alloyed iron-chrome-nickel stainless-steel powder according to either claim 22 or claim 23 of an iron-chrome-nickel stainless-steel alloy according to any of the claims 1 to 7, the powder further comprising a metal carbide powder.

25. A powder comprising a pre-alloyed iron-chrome-nickel stainless-steel powder according to claim 24, wherein the metal carbide powder is selected from one or more powders of a nickel carbide, a chromium carbide, a vanadium carbide, a tungsten carbide, a molybdenum carbide, a silicon carbide, a manganese carbide, an aluminum carbide, a titanium carbide, a niobium carbide, a tantalum carbide, a hafnium carbide, or a zirconium carbide; preferably is selected from one or more of a nickel carbide, a chromium carbide, a vanadium carbide, a tungsten carbide, a molybdenum carbide, a silicon carbide, a manganese carbide, or an aluminum carbide; more preferably is selected from one or more of a nickel carbide, a chromium carbide, a vanadium carbide, a tungsten carbide (WC) , or a molybdenum carbide; or most preferably is tungsten carbide (WC) .

26. A powder comprising a pre-alloyed iron-chrome-nickel stainless-steel powder according to any of the claims 24 or 25, wherein the powder contains from 13 wt% to 17 wt% of an iron-chrome-nickel stainless-steel pre-alloyed powder according to either claim 21 or claim 22, and from 83 to 87 wt% of a tungsten carbide (WC) powder; preferably 15 wt%, of an iron-chrome-nickel stainless- steel pre-alloyed powder according to either claim 21 or claim 22, and 85 wt% of a tungsten carbide (WC) powder.

27. A powder according to claim 26, wherein the powder comprises at least 80% by weight of the tungsten carbide (WC) powder contained within a sieved fraction of the tungsten-based powder having a size distribution from 1 pm to 100 pm, preferably from 2.5 pm to 75 pm, or even more preferably from 5 pm to 50 pm, as measured by sieving in accordance with ISO-14232-1-2017-E, Particle distribution by sieving, and / or preferably comprises at least 85% by weight, at least 90% by weight, or more preferably at least 95% by weight of the tungsten-based powder having a size distribution from 2.5 pm to 100 pm as measured by sieving in accordance with ISO-14232-1- 2017-E, Particle distribution by sieving.

28. A tungsten-based powder consisting by total weight of powder of :Iron (Fe) 6.6 - 7.9 wt%Carbon (C) 5.2 - 5.7 wt %Chromium (Cr) 3.9 - 4.5 wt %Nickel (Ni) 2.2 - 3.0 wt %Molybdenum (Mo) 0.60 - 0.75 wt%Silicon (Si) 0.10 - 0.22 wt%Manganese (Mn) 0.07 - 0.10 wt % the balance being tungsten (W) and unavoidable impurities not exceeding 0.3 wt%.

29. A tungsten-based powder according to claim 28, wherein the content of carbon (C) is from 5.3 to 5.7 wt%, preferably from 5.5 to 5.7 wt%.

30. A tungsten-based powder according to any of the claims 28 or 29, wherein the content of nickel (Ni) is from 2.2 to 2.7 wt%. preferably from 2.3 to 2.6 wt%, or more preferably from 2.4 to 2.5 wt%.

31. A tungsten-based powder according to any of the claims 28 to 30, wherein the content of iron (Fe) is from 6.8 wt% to 7.7 wt%, preferably from 7.0 wt% to 7.5 wt%, or more preferably from 7.2 wt% to 7.4 wt%.

32. A tungsten-based powder according to any of the claims 28 to 31, wherein the content of chrome (Cr) is from 4.0 wt% to 4.4 wt%, preferably from 4.1 wt% to 4.3 wt%.

33. A tungsten-based powder according to any of the claims 28 to 32, wherein the content of molybdenum (Mo) is from 0.61 wt%, from 0.63 wt%, or preferably from 0.65 wt%; and / or the content of molybdenum is to 0.74 wt%, to 0.72 wt%, or preferably to 0.70 wt%.

34. A tungsten-based powder according to any of the claims 28 to 33, wherein the content of silicon (Si) can be from 0.11 wt%, from 0.12 wt% from 0.13 wt%, or preferably from 0.14 wt%; and / or the content of silicon (Si) can be to 0.21 wt%, to 0.20 wt%, 0.19 wt%, or preferably to 0.18 wt% .

35. A tungsten-based powder according to any of the claims 28 to 34, wherein the content of manganese (Mn) is from 0.075 wt% or from 0.80 wt%; and / or the content of manganese (Mn) is to 0.095 wt% or to 0.090 wt%.

36. A tungsten-based powder according to any of the claims 28 to 35, wherein from 83 wt% to 87 wt% of the total mass of the powder is provided as a pre-formed tungsten carbide (WC) powder.37 . A tungsten-based powder according to any of the claims 28 to 36 , consisting of from 13 wt% to 17 wt% of a stainless-steel pre-alloyed powder according to either claim 8 or claim 9 , and from 83 to 87 wt% of a tungsten carbide (WC) powder; preferably 15 wt% of a stainless- steel pre-alloyed powder according to either claim 8 or claim 9 , and 85 wt% of a tungsten carbide (WC) powder .38 . A tungsten-based powder according to any of the claims 28 to 37 , wherein the tungsten-based powder comprises at least 80% by weight of the tungsten-based powder contained within a sieved fraction of the tungsten-based powder having a si ze distribution from 1 pm to 100 pm, preferably from 2 . 5 pm to 75 pm, or even more preferably from 5 pm to 50 pm, as measured by sieving in accordance with I SO-14232-1-2017-E , Particle distribution by sieving, and / or preferably comprises at least 85% by weight , at least 90% by weight , or more preferably at least 95% by weight of the tungsten-based powder having a si ze distribution from 2 . 5 pm to 100 pm as measured by sieving in accordance with I SO-14232-1-2017-E , Particle distribution by sieving .39 . A cermet powder consisting of from 83 wt% to 87 wt% of the total mass of the powder provided as a pre-formed tungsten carbide (WC) powder and from 13 wt% to 17 wt% of the total mass of the powder provided as a stainless- steel pre-alloyed powder according to either claim 8 or claim 9 ; preferably consisting of 85 wt% of the total mass of the powder provided as a pre-formed tungsten carbide (WC) powder and 15 wt% of the total mass of the powder provided as a stainless-steel pre-alloyed powder according to either claim 8 or claim 9 .40 . A cermet powder according to claim 36 , wherein the cermet powder comprises at least 80% by weight of the cermet powder contained within a sieved fraction of the cermet powder having a si ze distribution from 1 pm to 100 pm, preferably from 2 . 5 pm to 75 pm, or even more preferably from 5 pm to 50 pm, as measured by sieving in accordance with I SO-14232-1-2017-E , Particle distribution by sieving, and / or preferably comprises at least 85% by weight , at least 90% by weight , or more preferably at least 95% by weight of the cermet powder having a si ze distribution from 2 . 5 pm to 100 pm as measured by sieving in accordance with I SO-14232-1-2017-E , Particle distribution by sieving .41 . A cermet having a composition according to any one of claims 28 to 35 .42 . Use of a tungsten-based powder according to any one of claims 28 to 35 for the coating of a surface by means of a thermal spray method .43 . A composition comprising an iron-chrome-nickel stainless-steel alloy and tungsten carbide (WC) formed by alloying a tungsten-based powder according to any of the claims 28 to 35 .44 . A composition according to claim 40 , wherein the tungsten carbide (WC) is present as inclusions in a Ni-rich FCC- stainless-steel matrix .

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