Method for manufacturing coated metal substrate

Abstract

To provide a method for manufacturing a coated metal substrate that renders surface coatings on wear-prone metal substrates, mechanically and chemically more stable and thus more wear-resistant and prolong the service life.SOLUTION: A method for manufacturing a coated metal substrate includes entirely or partially coating a surface of a metal substrate using tungsten, molybdenum, tungsten or molybdenum alloys as a thermal spray material with thermal spraying or build-up welding. The surface of a metal substrate is coated by means of thermal spraying using tungsten or a tungsten alloy as a thermal spray material.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a coated abradable metal substrate and a method for producing the same. In particular, the present invention relates to an improved filling chamber for pressure (die) casting machines (Druckgiessmaschiene). [Background technology]

[0002] The inner surface of the filling chamber of a pressure die casting machine is most worn in the area of ​​the feed opening. By mechanically injecting hot casting material, for example liquid aluminum, through the feed opening, it always appears (impacts) at the same position below the feed opening on the inner surface of the filling chamber. After a longer use of the filling chamber, seepage can occur in the area below the feed opening, which can impede the sliding of the pressure piston in the chamber and expose the pressure piston to greater wear. In the case of vacuum pressure casting, it is furthermore more difficult to reliably generate the required vacuum. For this reason, a filling chamber is known from DE 42 29 338 C2, which consists of a jacket element with a separable cylindrical insert element. In this case, the insert element extends axially from the outer end of the filling chamber into the feed opening, its inner end abuts with its outer circumferential surface against the inner wall of the filling chamber in a narrow ring-shaped area, while its outer end is guided coaxially in relation to the filling chamber from a centering ring that is fitted between its outer periphery and the inner wall of the filling chamber. This already creates a filling chamber for the pressure die caster, whose main wear areas are directly replaceable in the pressure die caster, however, it would be desirable for this type of insert to have a longer service life.

[0003] Furthermore, from DE 102 05 246 B4, a filling chamber for a pressure die casting machine is known, which has a feed opening for liquid casting material, in which a cooling device is provided in the filling chamber wall in the area facing the feed opening. The cooling device is formed from a disk which can be fitted from the outside into the filling chamber wall and which is provided with at least one guide channel for the coolant. This measure is intended, inter alia, to increase the service life of the filling chamber insert.

[0004] EP 3 184 203 A1 likewise describes a filling chamber for a pressure die casting machine, the cylindrical inner surface of which serves as a sliding surface for a pressure piston, the filling chamber having a feed opening for the liquid casting material and a removable cylindrical insert along whose inner surface the pressure piston slides and which has a radial opening for a jacket filling which is in communication with the feed opening of the filling chamber. In this case, the inner surface of the removable insert is at least partially made of molybdenum or a molybdenum alloy. The removable insert is made of a metallic sleeve (steel) and an inner bush made of molybdenum or a molybdenum alloy (Mo / Mo alloy).

[0005] In the above case, where a cylindrical insert is used to protect the supply port or the filling chamber and can be replaced by a new insert in the event of wear, relatively quick removal is achieved in the case where wear of the sliding surface for the pressure piston occurs very frequently.

[0006] WO 00 / 10752 A1 relates to a casting tool for casting moulding parts made of non-ferrous metals (e.g. made of Al or Mg). In this case, the casting mould is made of a heavy metal alloy (e.g. W alloy) or is correspondingly coated on its side that bears against the moulding part. For this purpose, a heavy metal alloy is used in the form of a sintered element.

[0007] US 2017 / 0266719 A1 describes a pressure die casting machine and a corresponding casting method, where certain equipment parts are provided with a coating that is much less chemically reactive with the metals to be used for casting (such as Al, Cu, Ti and their alloys) than the iron alloys used in the prior art. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] DE 42 29 338 C2 [Patent Document 2] DE 102 05 246 B4 [Patent Document 3] EP 3 184 203 A1 [Patent Document 4] WO 00 / 10752 A1 [Patent Document 5] US 2017 / 0266719 A1 Summary of the Invention [Problem to be solved by the invention]

[0009] However, there is still the problem of increasing the replacement intervals for the above-mentioned inserts or the service life of the pressure die caster in general or of its most wear-prone part, the filling chamber, in order to make the casting process as efficient and uninterrupted as possible.Furthermore, there is the problem of making surface coatings, especially on wear-prone metallic substrates, mechanically and chemically more stable and thus more wear-resistant in general. [Means for solving the problem]

[0010] According to a first aspect of the present invention, a method for producing a coated metal substrate is provided. The method comprises coating the surface of a metal substrate completely or partially by thermal spraying or overlay welding using tungsten, molybdenum, a tungsten alloy or a molybdenum alloy as a thermal spray material. Contains It is characterized by: DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] A preferred embodiment of the invention is now presented. (Mode 1) See the first aspect of the present invention above. (Mode 2) In the method according to mode 1, The surface of the metal substrate is preferably coated by thermal spraying using tungsten or a tungsten alloy as the spray material. (Mode 3) In the method according to mode 1 or 2, The metal substrate is preferably the inner surface of a fill chamber or fill chamber insert of a pressure casting machine. (Mode 4) In the method according to any one of modes 1 to 3, The tungsten alloy is preferably an alloy containing more than 50% by mass of tungsten. (Mode 5) In the method according to any one of modes 1 to 4, The tungsten alloy is preferably a WNiFe alloy containing more than 50% by mass of tungsten or a WMoNiFe alloy in which the sum of the proportions of tungsten and molybdenum is more than 50% by mass. (Mode 6) In the method according to mode 1, The molybdenum alloy is preferably TZM molybdenum, consisting of 0.5% by mass titanium, 0.08% by mass zirconium, 0.01-0.04% by mass carbon, and the balance up to 100% by mass molybdenum. (Mode 7) In the method according to mode 1 or 2, The metal substrate is preferably the surface of a moulding tool, a piston, a camshaft or a shunt. (Embodiment 8) In the method according to embodiment 3, Preferably, the pressure casting machine is an aluminium pressure casting machine. (Mode 9) In the method according to any one of Modes 1 to 8, The thermal spray is preferably an arc spray. (Mode 10) In the method according to Mode 9, The arc spraying is preferably a single wire method. (Form 11) In the method according to form 9 or 10, Preferably, air is used as the atomizing gas.

[0012] The above object is achieved according to the invention in that the inner surface of the filling chamber or the inner surface of the insert for the filling chamber according to the invention is completely or partially coated with tungsten or a tungsten alloy. This also generally applies to abrasive metal substrates.

[0013] It is known that the greatest wear in the filling chamber occurs in its injection zone. For example, during aluminum pressure casting, low-iron Al alloys attack the steel of the filling chamber or of the installed replaceable bushings, causing leaching, especially in this zone. To eliminate these disadvantages, the inner surface of the filling chamber, which is usually made of steel, is preferably completely coated with tungsten or a tungsten alloy, at least in the injection zone. The present invention also includes the lining of the inner surface of the insert for the filling chamber, which is preferably made of steel, again completely or partially, with tungsten or a tungsten alloy.

[0014] The invention therefore includes a filling chamber for a pressure casting machine, the cylindrical inner surface of which serves as a sliding surface for a pressure piston and which has a supply port for liquid casting material, for example aluminum in the case of an aluminum pressure casting machine. In a preferred embodiment, the filling chamber has an insert member, preferably made of steel, which is provided on its outer circumferential surface with an opening that connects with the supply port of the filling chamber. In this case, the inner surface of the filling chamber or the inner surface of the insert member is completely or partially, in this case preferably in the injection area, applied with tungsten or a tungsten alloy or coated with tungsten or a tungsten alloy. The insert member has a length of approximately ¼ of the length of the filling chamber and a wall thickness of approximately half the wall thickness of the filling chamber.

[0015] The use of tungsten or tungsten alloys for the above applications is also included in the present invention.

[0016] The insert according to the invention differs from the insert described in EP 3 184 203 A1 in that it is not an exchangeable bush in the form of a sleeve system in which a molybdenum insert is fitted snugly and precisely into a steel outer sleeve, but rather the inner surface of the insert according to the invention, which is generally made of steel, is completely or partly coated with tungsten or a tungsten alloy.

[0017] Apart from this difference and the type of coating, which is important for the durability of the insert, the insert according to the invention corresponds to that described in EP 3 184 203 A1, insofar as this is the case, explicit reference is made to Figure 1 of the filling chamber described in said publication and its description, for example in paragraph

[0029] , and insofar as this may also serve as a description of the filling chamber according to the invention.

[0018] As coating material for the inner surface of the filling chamber or the insert according to the invention, tungsten or tungsten alloys are used, although it is still preferred that the inner surfaces of the filling chamber and the insert are completely coated. The alloys can be binary, ternary or quaternary alloys or alloys with further (metallic) components. Examples of such alloys are WNiFe alloys, which preferably contain more than 50% by weight of tungsten (W) or WMoNiFe alloys, where the sum of W and Mo is more than 50% by weight of the finished alloy.

[0019] Particularly preferred alloys contain more than 50% by weight of tungsten.Particularly preferred forms of tungsten and tungsten alloys are wire and powder.Production is carried out by powder metallurgy methods, which are in principle known to those skilled in the art.Furthermore, tungsten and corresponding tungsten alloys are offered by various manufacturers and metal trading companies, especially on the Internet.

[0020] The above embodiments for the preferred covering or coating materials also apply generally to the coating of metal substrates.

[0021] In addition to the selection of a suitable coating material for producing a chemically, thermally and mechanically stable coating on the filling chamber or metal substrate, it has been found (according to the present invention) that the coating method is also of great importance. In this regard, the linear thermal expansion coefficient α of tungsten (α=4.5×10 at 20° C.) is -6 (1 / K)) and steel (at 20°C α = 11-13 × 10 -6 It should be noted that the thermal and mechanical stability of tungsten coatings on steel substrates is quite difficult to apply, since the thermal and mechanical stability of tungsten coatings on steel substrates differs greatly from that of steel substrates.

[0022] The surface coating method of thermal spraying has been found to be particularly suitable for the purposes of the present invention. This method, in one embodiment of the present invention, leads to a significantly greater hardening of the sprayed layer, typically with a Vickers hardness of >800 HV, whereas, for example, tungsten alloys otherwise only have a hardness of 280-400 HV. In addition to a significant improvement in chemical / thermal and mechanical stability, surface coatings applied by thermal spraying are also characterized by a particularly high melt resistance, for example to liquid aluminum, and are therefore preferred and particularly suitable for use in aluminum pressure casting machines.

[0023] Thermal spray processes include the following methods: Arc Spraying Wire flame spraying method (or rod type) Powder flame spraying High velocity thermal spraying method / high velocity flame spraying method (HVOF:high velocity oxy fuel) Laser spraying (method) Cold Spray Method Detonation (explosion) thermal spraying (method) Plasma spraying (method) PTA (plasma transferred arc)

[0024] By choosing the thermal spray method as the coating technique, a highly advantageous hardness of the coating is achieved for use, which is crucial for a drastic increase in the service life of the thus coated filling chambers and inserts and metal substrates.

[0025] All these methods are in principle usable for the purposes of the present invention.

[0026] In addition to the tungsten-based material (additive material (spray material)), the invention therefore also relates to a coating method for applying (spraying) the material. The method of thermal spraying is a surface coating method. According to the standardized definition (DIN EN 657), the additive material, i.e. the so-called spray material, is melted, developed or completed inside or outside the spray torch, accelerated in the form of spray powder in a gas flow and impinges on the surface of the component to be coated. In the process, the component surface is not melted (unlike overlay welding) but is thermally loaded only to a small extent. The layer formation takes place in that the spray particles flatten more or less strongly on impact with the component surface, depending on the method and material, and remain attached mainly by mechanical bonding, building up the spray layer in a layer-by-layer manner. The qualitative properties of the spray layer are low porosity, good bonding to the component, crack-free and uniform microstructure. The layer (coating) properties achieved are essentially influenced by the temperature and velocity of the spray particles at the moment of their impact on the surface to be coated. The surface condition (cleanliness, activity, temperature) also influences quality properties such as adhesion strength.

[0027] As energy carriers for the development or completion of the melting of the sprayed (deposited) material, an electric arc (arc spraying), a plasma stream (or jet) (plasma spraying), a fuel-oxygen flame or a fuel-oxygen high-velocity flame (traditional high-velocity flame spraying), a preheated high-velocity gas (cold gas spraying) and a laser beam (laser (beam) spraying) are used. According to the DIN standard EN657, spraying methods are classified according to these criteria.

[0028] When W or W alloys (W / W alloys) are used as wires, the preferred method is wire arc spraying. For powdered W / W alloys, plasma spraying is particularly suitable.

[0029] The above-mentioned methods of thermal spraying are known in the prior art and therefore to the person skilled in the art; see, for example, http: / / www.gts-ev.de / html_d / ts-info.htm or the information catalog LINSPRAY® “Gase und Know-how beim thermischen Spritzen”, Linde AG, Geschaeftsbereich Linde Gas, Unterschleissheim (Germany).

[0030] For the purposes of the present invention, it has been found that particular representatives of coating methods known in principle from the prior art, appropriately modified for the purpose of solving the object of the present invention, give surprising results with regard to the quality of the applied coatings and, in this case, especially with regard to the hardness achieved.

[0031] Basically, thermal spraying methods and also methods for the build-up welding of coating materials are preferred according to the invention, whereby thermal spraying methods offer a wide range of application possibilities with a great variety of applicable materials.

[0032] Among the thermal spraying methods, in particular arc spraying, both in the so-called two-wire mode and especially preferably in the single-wire mode, is preferred according to the invention. The preferred coating material is tungsten or a tungsten alloy.

[0033] A preferred coating or thermal spraying method will now be described in detail by way of example with reference to FIG. 1, without, however, limiting the subject matter of the present invention. [Brief description of the drawings]

[0034] [Figure 1] FIG. 2 is a schematic diagram of a spray head of an example of a single wire type spray device. EXAMPLES

[0035] Figure 1 shows a schematic diagram of the spray head of an example of a single-wire spray device. Electrode 1 (a tungsten electrode) is rotatably mounted around the wire.

[0036] The arc is generated between the two wires in the double-wire system, or between the tungsten electrode 1 and the spray wire 7 in the single-wire spray as shown in Figure 1. In this case, the emitted electrons, i.e. the arc, first pass through the shielding gas 2, in this case argon or an argon-hydrogen mixture, and then through a mixture of the shielding gas 2 and the atomizing gas (Zerstaeubergas) consisting of N2 or air, ionizing the gas and generating a plasma 4, which is heated to approximately 15,000 °C. The plasma 4 consists of the shielding gas 1, i.e. argon or an argon / hydrogen (Ar / ArH2) mixture, and the atomizing gas 5. The electrode 1 is protected by the constant flow of the shielding gas 2 around it. The arc 4 then melts the spray wire 7, after which the atomizing gas 5, which has a very high pressure or a very high velocity, atomizes the molten droplets of the spray wire 7. The atomized spray wire containing atomizing gas and shielding gas is indicated by the reference number 8. The atomizing gas flow does not have to flow in a ring around the shielding gas 2, as in plasma welding, but can also be admitted, for example, via nozzles. In this case, the atomizing gas nozzle 6 shown in FIG. 1 would not be necessary and would be replaced by separate nozzles.

[0037] The spatial separation of the electrode 1 and the wire 7 allows the use of the more convenient nitrogen gas instead of the noble gas, although the electrode 1 can still rotate around the wire 7. Thus, an increase in hardness to approximately 600 HV is already achieved compared to the starting material having approximately 300 HV. It has been found (according to the present invention) that by using air as the atomizing gas 5, a further substantial increase in hardness to approximately 900 HV can be achieved. For the single-wire spraying method using a wire made of W or a W alloy, it is preferable to use a current in the range of 60 to 159 A.

[0038] The invention provides, inter alia, a longer service life for the highly loaded filling chambers and therefore also for the corresponding pressure casting machines, and includes coated filling chambers or corresponding inserts, a method for coating these components, a correspondingly constructed pressure casting machine and the use of tungsten or tungsten alloys for (fully or partially) coating the filling chambers or filling chamber inserts. These statements also generally apply according to their meaning to the metal substrates coated according to the invention.

[0039] In this regard, the following can be pointed out:

[0040] W / W alloys are less brittle and less susceptible to oxidation than molybdenum (Mo) or molybdenum alloys. The preferred thermal spraying according to the present invention allows for protection not only of the insert member, but also of the entire filling chamber.

[0041] The spraying leads to a strong hardening of the material, which not only improves the dissolution (or leaching) by the liquid melt, but also at the same time improves the mechanical wear resistance. Thus, the hardness of tungsten or typical tungsten alloys increases for example from 250-300 / 400 HV to more than 800 HV (for example 900 HV) for a sprayed layer (HV is Vickers hardness). Such hardening (hardness increase) does not occur, for example, in the case of iron or nickel alloys used up to now. The method using thermal spraying also allows the repair of worn inserts of the filling chamber in a simple manner. In this case, it is not necessary that these were originally provided with a coating.

[0042] Furthermore, the following embodiments and usage forms have been found, which are also included in the present invention.

[0043] In addition to thermal spraying, the welding or overlaying of W / W alloys to the substrate to be protected also results in an improvement of the thermal, chemical and mechanical properties of the (coated) surface. The hardness of the welded overlay W / W alloys is likewise significantly improved compared to the reference (standard) values, but generally does not reach the values ​​achievable by thermal spraying. The overlaying is carried out by conventional welding methods such as WIG welding, MIG welding or MAG welding.

[0044] Thermal spraying or welded build-up on the substrate surface - as explained for W / W alloys - also leads to a significant improvement in the thermal, chemical and mechanical properties (hardness) in the case of molybdenum or molybdenum alloys. Thus, for the purposes of the present invention, the coating of metal substrate surfaces by thermal spraying or welded build-up with Mo / Mo alloys is likewise included in the present invention, as described, for example, in EP 3 184 203 B1 (see paragraphs

[0009] to

[0012] ), which description is incorporated herein by reference for the purposes of disclosure.

[0045] Finally, the application of W / W alloys or Mo / Mo alloys according to the invention, still preferably W / W alloys, is not limited to coating the inner surfaces of the filling chambers and filling chamber inserts of pressure (mold) casting machines, but concerns all wear-prone areas, for example in the casting of aluminum, zinc and copper and corresponding alloys. The use of the coatings applied according to the invention therefore includes all parts that are subjected to load during the casting process, and their use includes all possible further wear-prone areas, such as coatings for forming tools, camshafts, shunts, pistons and comparable fields of use for aluminum, copper and steel. These are examples of wear-prone metal substrates in the sense of the invention.

[0046] Possible embodiments of the present invention are now described. [Appendix 1] Use of tungsten, molybdenum, tungsten alloys or molybdenum alloys for coating abrasive metal substrates. The coating is carried out by thermal spraying or overlay welding onto the substrate surface. [Appendix 2] The above-mentioned use of tungsten or tungsten alloy for coating a substrate surface by thermal spraying. [Appendix 3] In the above use, the abradable metal substrate is the inner surface of a filling chamber or a filling chamber insert member of a pressure casting machine. [Appendix 4] In the above use, the tungsten alloy is an alloy containing more than 50 mass% tungsten. [Appendix 5] In the above use, the tungsten alloy is a WNiFe alloy containing more than 50 mass% tungsten, or a WMoNiFe alloy in which the sum of the proportions of tungsten and molybdenum is more than 50 mass%. [Appendix 6] In the above use, the molybdenum alloy is TZM molybdenum consisting of 0.5 mass % titanium, 0.08 mass % zirconium, 0.01-0.04 mass % carbon, and the balance up to 100 mass % molybdenum. [Appendix 7] In the above use, the wearable metal substrate is a wearable area of ​​a metal casting system, a molding tool, a piston, a camshaft or a surface of a shunt. [Appendix 8] Metal substrates whose surfaces are completely or partially coated with tungsten, molybdenum, tungsten alloys or molybdenum alloys by thermal spraying or overlay welding. [Appendix 9] In the above metal substrate, the coated surface is the inner surface of a filling chamber or a filling chamber insert member of a pressure casting machine. [Appendix 10] A pressure casting machine having the above-mentioned filling chamber or filling chamber insert member. [Appendix 11] The above pressure casting machine is an aluminum pressure casting machine. [Appendix 12] A method for coating a surface of a metal substrate, in which tungsten, molybdenum, a tungsten alloy or a molybdenum alloy is applied to the surface of the metal substrate by thermal spraying or overlay welding. [Appendix 13] In the above method, the coating is applied by arc spraying. [Appendix 14] In the above method, the arc spraying is a single wire method. [Appendix 15] In the above method, air is used as the atomizing gas. [Appendix 16] A thermal spray material containing tungsten, molybdenum, a tungsten alloy or a molybdenum alloy for arc spraying used to coat the surface of an abradable metal substrate. [Appendix 17] A thermal spray material containing tungsten or a tungsten alloy for arc spraying used to coat the surface of an abradable metal substrate. [Appendix 18] In the above thermal spray material, the abradable metal substrate is the inner surface of a filling chamber or a filling chamber insert member of a pressure casting machine. [Appendix 19] In the above thermal spray material, the tungsten alloy is an alloy containing more than 50 mass% tungsten. [Appendix 20] In the above thermal spray material, the tungsten alloy is a WNiFe alloy containing more than 50 mass% tungsten, or a WMoNiFe alloy in which the total ratio of tungsten and molybdenum is more than 50 mass%. [Appendix 21] In the above thermal spray material, the molybdenum alloy is TZM molybdenum consisting of 0.5 mass % titanium, 0.08 mass % zirconium, 0.01 to 0.04 mass % carbon, and the remainder up to 100 mass % molybdenum. [Supplementary Note 22] In the above thermal spray material, the abradable metal substrate is a wear-prone area of ​​a metal casting system, a molding tool, a piston, a camshaft, or a surface of a shunt. [Appendix 23] Metal substrates whose surfaces are completely or partially coated with tungsten, molybdenum, tungsten alloys or molybdenum alloys by arc spraying. [Appendix 24] In the above metal substrate, the coated surface is the inner surface of a filling chamber or a filling chamber insert member of a pressure casting machine. [Appendix 25] A pressure casting machine having the above-mentioned filling chamber or filling chamber insert member. [Appendix 26] The above pressure casting machine is an aluminum pressure casting machine. [Appendix 27] A method for coating a surface of a metal substrate, in which tungsten, molybdenum, a tungsten alloy or a molybdenum alloy is applied to the surface of the metal substrate by arc spraying. [Appendix 28] In the above method, the arc spraying is a single wire method. [Appendix 29] In the above method, air is used as the atomizing gas. [Appendix 30] A method for producing a coated metal substrate. The method involves completely or partially coating the surface of a metal substrate by thermal spraying or overlay welding using tungsten, molybdenum, a tungsten alloy or a molybdenum alloy as a thermal spray material. [Appendix 31] In the above manufacturing method, The surface of the metal substrate is coated by thermal spraying with tungsten or tungsten alloy as the spray material. [Appendix 32] In the above manufacturing method, The metal substrate is the interior surface of a fill chamber or fill chamber insert of a pressure casting machine. [Appendix 33] In the above manufacturing method, The tungsten alloy is an alloy containing more than 50% by mass of tungsten. [Appendix 34] In the above manufacturing method, The tungsten alloy is a WNiFe alloy containing more than 50% by mass of tungsten, or a WMoNiFe alloy in which the sum of the proportions of tungsten and molybdenum is more than 50% by mass. [Appendix 35] In the above manufacturing method, The molybdenum alloy is TZM molybdenum, consisting of 0.5% by weight titanium, 0.08% by weight zirconium, 0.01-0.04% by weight carbon, and the balance up to 100% by weight molybdenum. [Appendix 36] In the above manufacturing method, The metal substrate may be the surface of a mold tool, a piston, a camshaft, or a shunt. [Appendix 37] In the above manufacturing method, The pressure casting machine is an aluminum pressure casting machine. [Appendix 38] In the above manufacturing method, The thermal spray is an electric arc spray. [Appendix 39] In the above manufacturing method, The arc spraying is a single wire process. [Appendix 40] In the above manufacturing method, Air is used as the atomizing gas. [Explanation of symbols]

[0047] 1 Cathode (tungsten electrode) 2 Shielding gas (argon / argon hydrogen) 3 Shielding gas nozzle 4 Arc (plasma consisting of shielding gas Ar / ArH2) 5. Atomization gas (N2 or air) 6 Gas nozzle for atomizing gas 7 Spray (thermal spray) wire 8 Atomized spray (thermal spray) wire (including atomizing gas and shielding gas)

Claims

1. 1. A method for producing a coated metal substrate, comprising the steps of: The method comprises coating the surface of a metal substrate completely or partially by thermal spraying or overlay welding using tungsten, molybdenum, a tungsten alloy or a molybdenum alloy as a thermal spray material. Contains A method comprising:

2. 10. The method of claim 1 , The surface of the metal substrate is coated by thermal spraying using tungsten or a tungsten alloy as a thermal spray material. A method comprising:

3. The method according to claim 1 or 2, The metal substrate is an inner surface of a filling chamber or a filling chamber insert of a pressure casting machine. A method comprising:

4. In the method according to any one of claims 1 to 3, The tungsten alloy contains more than 50% by mass of tungsten. A method comprising:

5. In the method according to any one of claims 1 to 4, The tungsten alloy is a WNiFe alloy containing more than 50% by mass of tungsten, or a WMoNiFe alloy in which the sum of the proportions of tungsten and molybdenum is more than 50% by mass. A method comprising:

6. 10. The method of claim 1 , The molybdenum alloy is TZM molybdenum, which consists of 0.5% by weight titanium, 0.08% by weight zirconium, 0.01-0.04% by weight carbon, and the balance up to 100% by weight molybdenum. A method comprising:

7. The method according to claim 1 or 2, The metal substrate is a surface of a molding tool, a piston, a camshaft, or a shunt. A method comprising:

8. 4. The method of claim 3, The pressure casting machine is an aluminum pressure casting machine. A method comprising:

9. The method according to any one of claims 1 to 8, The thermal spray is an arc spray. A method comprising:

10. 10. The method of claim 9, The arc spraying is a single wire method. A method comprising:

11. 11. The method according to claim 9 or 10, Air is used as the atomizing gas. A method comprising:

Images