A method for forming a ceramic coating on the surface of an aluminum alloy substrate by plasma electrolytic oxidation.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- FRENI BREMBO S P A O PIU BREVEMENTE BREMBO
- Filing Date
- 2021-10-21
- Publication Date
- 2026-06-16
Smart Images
Figure 0007874631000002 
Figure 0007874631000003 
Figure 0007874631000004
Abstract
Claims
1. A method for producing a ceramic coating on the surface of an aluminum alloy substrate by electrolytic plasma oxidation, (a) A step of immersing the substrate together with the counter electrode in an alkaline electrolytic aqueous solution, (b) A step of applying a potential sufficient to generate a spark discharge on the surface of a substrate for a predetermined processing time, so as to form the coating consisting mainly of aluminum oxide and oxides of the alloying elements of the alloy. Includes, The aforementioned electrolytic aqueous solution is 9-14 g / L Na ２ SiO ３ , 2.3–2.8 g / L of potassium ３ PO ４ , Na 5 g / L or more ２ WO ４ ・2H ２ O, 0.4 to 1.5 g / L of Na ３ AlF ６ , NaOH of a concentration such that the electrolytic aqueous solution has a pH between 11.8 and 12.0 and a conductivity between 9.5 and 10.5 mS / cm Methods that include...
2. The aforementioned electrolytic aqueous solution contains 9 to 11 g / L of Na ２ SiO ３ The method according to claim 1, including the method described in claim 1.
3. The aforementioned electrolytic aqueous solution contains 10 g / L of Na. ２ SiO ３ The method according to claim 2, including the method described in claim 2.
4. The electrolytic aqueous solution contains 2.4 to 2.6 g / L of K ３ PO ４ The method according to any one of claims 1 to 3, including the method described in any one of claims 1 to 3.
5. The aforementioned electrolytic aqueous solution contains 2.5 g / L of K ３ PO ４ The method according to claim 4, including the method described in claim 4.
6. The aforementioned electrolytic aqueous solution contains 5 g / L of Na ２ WO ４ ・2H ２ The method according to any one of claims 1 to 5, comprising O.
7. The aforementioned electrolytic aqueous solution contains 0.4 to 0.6 g / L of Na ３ AlF ６ The method according to any one of claims 1 to 6, including the method described in any one of claims 1 to 6.
8. The aforementioned electrolytic aqueous solution contains 0.5 g / L of Na ３ AlF ６ The method according to claim 7, including the method described in claim 7.
9. The method according to any one of claims 1 to 8, wherein the electrolytic aqueous solution contains NaOH at a concentration such that it has a pH of 11.9 and a conductivity of 10.0 mS / cm.
10. The method according to any one of claims 1 to 9, wherein the electrolytic aqueous solution contains 0.8 to 1.2 g / L of NaOH.
11. The method according to claim 10, wherein the electrolytic aqueous solution contains 0.9 to 1.1 g / L of NaOH.
12. The method according to claim 10, wherein the electrolytic aqueous solution contains 1.0 g / L of NaOH.
13. The aforementioned electrolytic aqueous solution 10 g / L Na ２ SiO ３ , 2.5 g / L of K ３ PO ４ , 5g / LのNa ２ WO ４ ・2H ２ O、 0.5 g / L Na ３ AlF ６ , 1.0 g / L NaOH, Includes, The method according to claim 1, wherein the electrolytic aqueous solution has a pH of 11.9 and a conductivity of 10.0 mS / cm.
14. The method according to any one of claims 1 to 13, wherein the alkaline electrolytic aqueous solution is cooled by a cooling system.
15. The method according to claim 14, wherein the alkaline electrolytic aqueous solution is maintained at a temperature between 25°C and 45°C for the predetermined processing time.
16. The method according to any one of claims 1 to 15, wherein the potential is kept constant for the predetermined period of time.
17. The method according to claim 16, wherein the potential is maintained at a value between 300 and 400 V for the predetermined period of time.
18. The method according to claim 16, wherein the potential is maintained at 350V for the predetermined period of time.
19. During the predetermined processing time, 20 to 25 A / dm ２ The method according to any one of claims 1 to 18, wherein a current having the current density is applied to a substrate.
20. During the predetermined processing time, 25 A / dm ２ The method according to claim 19, wherein a current having the current density is applied to the substrate.
21. The method according to any one of claims 1 to 20, wherein a current having a frequency of at least 50 Hz is applied to the substrate.
22. The method according to claim 21, wherein a current having a frequency of 50 Hz is applied to the substrate.
23. The method according to any one of claims 19 to 22, wherein the current can be applied in a continuous or pulsed mode.
24. The method according to any one of claims 1 to 23, wherein the processing time for a predetermined period is 20 to 40 minutes.
25. The method according to claim 24, wherein the processing time for a predetermined period is 30 minutes.
26. The potential is kept constant at a value of 350V for the predetermined processing time, and the current is 25A / dm² during the predetermined processing time. ２ The method according to any one of claims 1 to 25, wherein a current having a current density equal to and a frequency equal to 50 Hz is continuously applied to the substrate, and the predetermined processing time is 30 minutes.
27. The method according to any one of claims 1 to 26, comprising a pretreatment step (c) of the substrate performed prior to steps (a) and (b), wherein the pretreatment consists of subjecting the substrate to a caustic treatment and then washing the substrate with distilled water.
28. The method according to claim 27, wherein the caustic treatment is obtained by immersing the substrate in an aqueous solution of NaOH maintained at a temperature of 60°C to 70°C for a predetermined time, and the predetermined immersion time is 5 to 15 minutes.
29. The method according to claim 28, wherein the caustic treatment is obtained by immersing the substrate in an aqueous solution containing 50 g / L of NaOH maintained at 60°C for a predetermined time, the predetermined immersion time being 10 minutes.
30. The method according to any one of claims 27 to 29, wherein in step (c) of the pretreatment of the substrate, after caustic treatment and subsequent washing with distilled water, the substrate is immersed in an acid bath for a predetermined time and then washed with distilled water.
31. The method according to claim 30, wherein the acid bath consists of an aqueous solution of nitric acid, and the predetermined immersion time in the acid bath is 5 to 15 seconds.
32. The method according to claim 31, wherein the predetermined immersion time in the acid bath is 10 seconds.
33. The post-treatment step (d) of the substrate is performed after steps (a) and (b), wherein the post-treatment is Wash the aforementioned substrate with distilled water. The surface of the substrate is cleaned with alcohol, and Dry at room temperature The method according to any one of claims 1 to 32, comprising:
34. The method according to any one of claims 1 to 33, wherein the ceramic coating consists of a non-porous, compact layer, and has a porous layer on its surface having a thickness not exceeding 5% of the total thickness of the coating.
35. The method according to claim 34, wherein the ceramic coating consists only of the non-porous compact layer.
36. The method according to claim 34 or 35, wherein the ceramic coating has a roughness Ra ≤ 2 μm and a hardness HV 0.01 ≥ 1.
400.
37. The method according to any one of claims 1 to 36, wherein the substrate is an aluminum-silicon alloy, and the resulting ceramic coating is a layer mainly composed of a mixture of aluminum oxide, silicon oxide, and aluminum-silicon mixed oxide.
38. The method according to any one of claims 1 to 37, wherein the substrate consists of components of a brake system.
39. The method according to claim 38, wherein the base material comprises a disc brake system.
40. The method according to claim 38, wherein the base material comprises a brake caliper, a brake caliper piston, or a brake disc bell.