JP2005521794A5

JP2005521794A5 -

Info

Publication number: JP2005521794A5
Application number: JP2003580609A
Authority: JP
Filing date: 2002-09-23
Publication date: 2006-01-05
Anticipated expiration: 2022-09-23

Claims

A process for forming a ceramic film on a metal and an alloy in an electrolytic cell in which a first electrode is attached and is filled with an aqueous alkaline electrolyte, in which an article to which another electrode is connected is immersed. In a process in which a pulse current is supplied between the electrodes so that the process is performed by a plasma discharge method,
i) supplying a high frequency bipolar current pulse having a predetermined frequency range to the electrode;
ii) a process of generating acoustic vibration in a predetermined sound wave frequency range in the electrolyte solution, the process including a step in which the frequency range of the acoustic vibration overlaps the frequency range of the current pulse.

The coating is made of a metal such as Mg, Al, Ti, Nb, Ta, Zr, or Hf or an alloy thereof, or Al—Be, Ti—Al, Ni—Ti, Ni—Al, Ti—Nb, Al—Zn, Al—. Al ₂ O _3, the process of claim 1, such as Mg-Al ₂ O ₃ is formed on the compound or complex.

Each current pulse has an initial steeply increasing portion of the current that reaches its maximum value in a time not greater than 10% of the total duration of the pulse, and the subsequent current first decreases rapidly, and then less than 50% of the maximum value The process according to claim 1 or 2, wherein the process has a shape including a portion that gradually decreases until.

4. A process according to any preceding claim, wherein the acoustic vibration causes aerohydrodynamic saturation of the electrolyte with oxygen.

The process according to claim 4, wherein oxygen or air is supplied to the electrolyte.

The process according to any one of claims 1 to 5, further comprising the step of introducing ultra-dispersed solid particles into the electrolyte and generating a stable aqueous sol by the acoustic vibration.

The process according to claim 6, wherein the solid particles have a particle size not larger than 0.5 μm.

The process according to claim 6 or 7, wherein the solid particles are composed of a compound in the form of a metal oxide, boride, carbide, nitride, silicide, or sulfide.

The process according to claim 1, wherein the plasma discharge method is a plasma electrolytic oxidation method.

The process according to claim 1, wherein the ceramic coating is formed at a rate of 2 to 10 μm / min.

Process according to any one of claims 1 to 10 having a current density current from 3 200A / dm ² applied to the article.

The process of claim 11, wherein the current applied to the article has a current density of 10 to 60 A / dm ² .

13. The current pulse has a pulse duration of at least 500 Hz.
The process described in any of the above.

The process of claim 13, wherein the pulse duration is in the range of 1,000 to 10,000 Hz.

An apparatus for forming a ceramic coating on metals and alloys comprising an electrolytic cell having electrodes, a source for sending pulsed current to the electrodes, and at least one acoustic vibration generator.
i) the source is adapted to supply a high frequency bipolar current pulse in a predetermined frequency range to the electrode;
ii) the at least one acoustic vibration generator is adapted to generate acoustic vibrations in the electrolyte contained in the vessel, the acoustic vibrations being pre-determined to overlap the frequency range of the current pulses A device having a sonic frequency range.

The source has an initial steeply increasing portion of current where each current pulse reaches a maximum value within a time period not greater than 10% of the total duration of the pulse, and the subsequent current initially decreases rapidly and then reaches a maximum value. 16. The apparatus of claim 15, wherein said apparatus is adapted to have a shape that includes a portion that gradually decreases to 50% or less.

17. An apparatus according to claim 15 or 16, wherein the at least one acoustic generator is an aero-hydraulic resonator having at least one input for flowing an electrolyte.

18. The acoustic vibration generated by the at least one aerohydraulic resonator is controlled by changing the pressure of the electrolyte flow at the input of the aerohydraulic resonator. The device described.

15. A ceramic coating formed on a metal or alloy by the process of any one of claims 1-14.

A ceramic coating formed on a metal or alloy using the apparatus according to any one of claims 15-18.

21. A ceramic coating according to claim 19 or 20, wherein the coating has a porous outer layer with a thickness not greater than 14% of the total coating thickness.

The ceramic coating according to claim 21, wherein the porous outer layer comprises a thickness not greater than 10% of the total coating thickness.

23. The ceramic coating of claim 22, wherein the porous outer layer comprises a thickness that is not greater than 8% of the total coating thickness.

24. A ceramic coating according to any one of claims 19 to 23 , wherein the coating has a low roughness (Ra) surface of 0.6 to 2.1 [mu] m.

15. The ceramic coating according to claim 1 , wherein the ceramic coating is formed on a metal or alloy by a plasma discharge process and has a low roughness (Ra) surface of 0.6 to 2.1 [mu] m.

The ceramic coating according to any one of claims 19 to 25 , wherein the coating has a dense fine polycrystalline structure having a microhardness of 500 to 2100 HV.

27. A ceramic coating according to any one of claims 19 to 26 having a total thickness of 2 to 150 [mu] m.

A process of forming a ceramic coating on metals and alloys in an electrolytic cell to which a first electrode is attached and which is filled with an aqueous alkaline electrolyte, in which the article to which the other electrode is connected is immersed. Supplying a high-frequency bipolar current pulse having a predetermined frequency range to the electrodes in a process of supplying a current pulse between the electrodes so that the process can be performed by a plasma discharge method,
An initial steeply increasing portion of the current where the current pulse reaches a maximum value in less than 10% of the total duration of the pulse, followed by a rapid decrease in current first and then to less than 50% of the maximum value A process having a shape including a gradually decreasing portion.

29. The process of claim 28, further comprising generating acoustic vibrations in a predetermined acoustic frequency range in the electrolyte so that the acoustic vibration frequency range overlaps the current pulse frequency range.

An apparatus for forming a ceramic coating on a metal and an alloy, comprising: an electrolytic cell having an electrode; a power source for sending a pulsed current to the electrode; and at least one acoustic vibration generator; A high frequency bipolar current pulse in a predetermined frequency range can be supplied, and the power source includes an initial steep increase portion of the current where each current pulse reaches a maximum value in less than 10% of the total duration of the pulse; , An apparatus that can have a shape that includes a portion where the subsequent current decreases rapidly initially and then gradually decreases to less than 50% of the maximum value.

The at least one acoustic vibration generator can generate an acoustic vibration in an electrolyte when confined in the electrolytic cell, and the acoustic vibration has a predetermined acoustic frequency range that overlaps a frequency range of the current pulse. Item 30. The apparatus according to Item 30.