Method for manufacturing a component, component and gas hob

Abstract

A method for manufacturing a component for a gas hob, the method comprising treating a surface by plasma electrolytic oxidation.

Claims

1-15. (canceled)

16. A method, comprising treating a surface of a substrate by plasma electrolytic oxidation for manufacturing a component for a gas hob.

17. The method of claim 16, wherein the component is a gas burner, a pan support or a profile part of the gas hob.

18. The method of claim 17, wherein the profile part of the gas hob is a rear profile, front profile or side profile.

19. The method of claim 16, wherein the substrate is a semi-finished product made of an aluminum alloy.

20. The method of claim 19, wherein the aluminum alloy comprises copper and/or magnesium and/or silicon.

21. The method of claim 19, wherein the aluminum alloy is AlSi9Cu3(Fe), AlSi11Cu2(Fe) or AlMgSi1.

22. The method of claim 16, wherein the surface of the substrate is treated by plasma electrolytic oxidation to manufacture a coating on the surface.

23. The method of claim 22, wherein the surface of the substrate is treated by plasma electrolytic oxidation until the coating has a thickness between 40 and 50 μm.

24. The method of claim 22, wherein the coating comprises Al.sub.2O.sub.3 and/or CuAl.sub.2O.sub.4 and/or MgCu.sub.2O.sub.4 and/or AlSiOOH and/or Al.sub.2Si.sub.2O.sub.5(OH).sub.2.

25. The method of claim 16, further comprising pretreating the surface of the substrate with abrasive particles.

26. The method of claim 16, wherein the surface of the substrate is treated by plasma electrolytic oxidation by immersing the surface of the substrate in an electrolyte, with the electrolyte comprising an alkaline solution, free chrome and/or free vanadium and/or free nickel.

27. The method of claim 16, wherein the surface of the substrate is treated by plasma electrolytic oxidation for a time period between 5 to 50 min.

28. The method of claim 16, wherein the surface of the substrate is treated by plasma electrolytic oxidation at a process temperature between 10-30 ° C.

29. The method of claim 23, wherein the thickness of the coating is manufactured at a coating rate between 1 and 5 μm/min.

30. A component for a gas hob, said component being manufactured by treating a surface of a substrate by plasma electrolytic oxidation.

31. The component of claim 30, wherein the component is a gas burner, a pan support or a profile part of the gas hob.

32. The component of claim 31, wherein the profile part is a rear profile, front profile or side profile.

33. The component of claim 30, wherein the surface of the substrate includes a coating at a thickness between 40 and 50 μm.

34. The component of claim 33, wherein the coating comprises Al.sub.2O.sub.3 and/or CuAl.sub.2O.sub.4 and/or MgCu.sub.2O.sub.4 and/or AlSiOOH and/or Al.sub.2Si.sub.2O.sub.5(OH).sub.2.

35. A gas hob comprising a component, said component being manufactured by treating a surface of a substrate by plasma electrolytic oxidation.

Description

[0045] Further embodiments, features and advantages of the present invention will become apparent from the subsequent description and dependent claims, taken in conjunction with the accompanying drawings, in which:

[0046] FIG. 1 shows a schematic view of a gas hob;

[0047] FIG. 2 shows schematically a PEO process;

[0048] FIG. 3 shows a schematic cross-section of a component; and

[0049] FIG. 4 shows a block diagram of a method for manufacturing the component.

[0050] In the Figures, like reference numerals designate like or functionally equivalent elements, unless otherwise indicated.

[0051] FIG. 1 shows a gas hob 1. The gas hob 1 comprises a top sheet 2 at which a gas burner 3 and a pan support 4 are arranged. The pan support 4 is configured to hold a pan or pot above the gas burner 3. Preferably, a further gas burner 5 or gas burners and a further pan support 6 or pan supports are provided. One pan support 6 may, for example, be provided for one gas burner 3. Alternatively, the pan support 4 may be provided for two, three, four or five gas burners surrounding the same. In particular, the gas hob 1 comprises a profile part 7, 8, 9, in particular a rear profile 7 and/or a side profile 8, 9. The profile part may e.g. be provided as front profile.

[0052] FIG. 2 shows a PEO process 10. A receptacle 11 is provided which contains an electrolyte 12. A substrate 17 is immersed into the electrolyte 12. The substrate 17 is for example a semi-finished gas burner 3, 5, pan support 4, 5 or the profile part 7, 8, 9, in particular a rear 7 or side profile 8, 9, from FIG. 1. Further, the substrate 17 is connected to a voltage source 14 as an anode. Furthermore, a cathode 15 is connected to the voltage source 14. The cathode 15 may be a separate body immersed in the electrolyte 12. Alternatively, the receptacle 11 may be used as cathode. The substrate 17 is provided as semi-finished product having a surface 16 which is in contact with the electrolyte 12 during the PEO process.

[0053] PEO is a high voltage electrochemical process which generates a plasma-discharge in the metal-electrolyte interface so that the surface 16 may be transformed into a hard and dense ceramic oxide coating 18 (see FIG. 3). The composition of such a ceramic coating involves oxides and components of the electrolyte 12. Plasma discharges occur when the voltage applied exceeds a “breakdown value” (usually several hundred volts). PEO process involves creation of a plasma discharge around the substrate 17 immersed in a bath of electrolyte 12. The electrolyte 12 may comprise silicate, phosphates, fluorides, free of chrome and/or vanadium and/or nickel, in particular having a total salt content less than 4%. The pH of the electrolyte 12 varies between 10-12. Therefore, the electrolyte 12 and the PEO process are environmentally acceptable. The mechanism of oxide layer formation during the PEO process may involve oxide growth with subsequent fusing, re-crystallization of the oxide film and also partial substrate metal dissolution at microscopic levels.

[0054] During the PEO process 10 the voltage source 14 preferably produces a voltage between 200-900V. As the PEO process 10 uses controlled high voltage power, the productivity of this process is high. A density of current is preferably less than 0.3A/cm.sup.2. A process temperature is e.g. between 10-30° C. when treating the surface 16.

[0055] Further advantages of PEO are that e.g. it is not necessary to pretreat the surface 16. Alternatively, the surface 16 can be polished or grinded for increasing a bonding effect to the hard ceramic coating 18 (see FIG. 3). Components 3, 4, 5, 6, 7, 8, 9 treated with PEO show a high corrosion resistance. For example, when using aluminum as substrate being treated with PEO, the component 3, 4, 5, 6, 7, 8, 9 can stay more than 2000 hours inside the salt spray chamber until corrosion appears, according to ISO 9227. Compared to that, a substrate treated with hard anodizing achieves 1000 hours, a substrate treated with electroless nickel plating achieves 500 hours, and hard chrome achieves less than 100 hours. The external porosity of the PEO coating is appropriate for the application of paint or lacquer. Further, it is possible manufacture a colored surface by adding suitable reagents to the electrolyte 12.

[0056] FIG. 3 shows a cross-section of the component 3, 4, 5, 6, 7, 8, 9. The component 3, 4, 5, 6, 7, 8, 9 comprises the substrate 17 and a coating 18 on the substrate 17, wherein the coating 18 is manufactured by PEO. Preferably, the substrate 17 is made of an aluminum alloy which comprises copper and/or magnesium and/or silicon. The aluminum alloy is e.g. AlSi9Cu3(Fe), AlSi11Cu2(Fe) or AlMgSi1. The coating 18 is manufactured on the former surface 16 which is now covered by the coating 18. A thickness 19 of the coating 18 may be between 20 and 50 μm, in particular 40 and 50 μm. The coating 18 comprises α, γ-Al.sub.2O.sub.3 and/or CuAl.sub.2O.sub.4 and/or MgCu.sub.2O.sub.4 and/or AlSiOOH and/or Al.sub.2Si.sub.2O.sub.5(OH).sub.2

[0057] In particular, the coating 18 comprises α and or γ-Al.sub.2O.sub.3 (e.g. up to 70%) and/or CuAl.sub.2O.sub.4 and/or MgCu.sub.2O.sub.4, in particular when the substrate 17 is an Al-Cu-Mg alloy. Preferably, the coating 18 may comprise α and/or γ-Al.sub.2O.sub.3, preferably 10-20%, in particular mainly mullite (Al.sub.6O.sub.13Si.sub.2), in particular when the substrate 17 is an Al-Si alloy having more than 0,5% silicon (high Si alloys). In particular, the coating comprises α-Al.sub.2O.sub.3 (e.g. up to 60%) and/or γ-Al.sub.2O.sub.3 and/or AlSiOOH and/or Al.sub.2Si.sub.2O.sub.5(OH).sub.2, in particular when the substrate 17 is an Al-Si alloy having less than 0,5% silicon (lower Si alloys).

[0058] It is advantageous to provide a thickness 19 of the coating 18 which is less than 50 microns in order to achieve the minimum possible porosity that is important to facilitate the cleaning of these parts in use.

[0059] Aluminum treated with PEO may achieve a Vickers hardness around 2000 HV, in particular 2000 HV 10 or 2000 HV 30 (according to ISO 6507-1 to ISO 6507-4). and is, thus, harder than hard chrome, hardened tool steel, hard anodized aluminum, stainless steel, mild steel and aluminum. For example, a Vickers hardness of 1150±83 HV, in particular 1150±83 HV 10 or in particular 1150±83 HV 30 (according to ISO 6507-1 to ISO 6507-4). of the component 3, 4, 5, 6, 7, 8, 9 has been tested when using AlMgS.sub.1, for the substrate 17 and a thickness 19 of the coating 19 between 44 and 50 μm. In this example, the surface 16 has been polished with greenstone (e.g. 25 min) before applying PEO. Further, a current density of 220 mA/cm.sup.2, a voltage between 300-600 V, a process temperature between 10-30 ° C. and a coating rate between 1-5 μm/min has been provided as process parameters of the PEO process 10 (see FIG. 2). As electrolyte 12 an aqueous alkaline solution having free Cr and V has been used. It has been observed that the pretreatment of the surface 16 with abrasive particles result in a more homogenous coating growth with a higher coating rate resulting in a greater thickness 19 of the coating 18.

[0060] FIG. 4 shows a block diagram of the method for manufacturing the component 3, 4, 5, 6, 7, 8, 9 for the gas hob 1. In a step S1 the substrate 17, in particular a semi-finished product, having the surface 16 is provided. In an optional step S2 the surface 16 is pretreated by means of degreasing and/or polishing the same. In a step S3 the substrate 16 is immersed into the electrolyte 12. In a step S4 the substrate 16 is connected as the anode to the voltage source 14. In a step S5 a voltage between 200-900 V, in particular 300-900 V, 400-900 V or 500-900 V, is applied by means of the voltage source 14. After forming the coating 18 on the substrate 17 a step S6 of painting the component 3, 4, 5, 6, 7, 8, 9 or an additional coating can be provided.

[0061] Although the present invention has been described in accordance with preferred embodiments, it is obvious for the person skilled in the art that modifications are possible in all embodiments.

[0062] Reference Numerals:

[0063] 1 gas hob

[0064] 2 top sheet

[0065] 3 burner

[0066] 4 pan support

[0067] 5 burner

[0068] 6 pan support

[0069] 7 profile

[0070] 8 profile

[0071] 9 profile

[0072] 10 PEO process set up

[0073] 11 receptacle

[0074] 12 electrolyte

[0075] 14 voltage source

[0076] 15 cathode

[0077] 16 surface

[0078] 17 substrate

[0079] 18 coating

[0080] 19 thickness

[0081] S1 step

[0082] S2 step

[0083] S3 step

[0084] S4 step

[0085] S5 step

[0086] S6 step