JP2829304B2 - Zr alloy plating method on ceramic - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for plating Zr or a Zr alloy on ceramic by electroplating. [0002] [Conventional technology and its problems] A composite material in which ceramic is coated with Zr or a Zr alloy has excellent corrosion resistance and heat resistance, and has a small thermal neutron absorption cross-sectional area. Expected. Conventionally, ceramics are generally Z
As a method of coating with an r or Zr alloy, there are a vacuum deposition method, a CVD method, and a brazing method. The vacuum evaporation method and the CVD method have a complicated apparatus configuration due to the high boiling point of Zr, and none of them has been put to practical use on a mass production scale. The brazing method also has a complicated apparatus configuration due to the high boiling point of Zr and is poor in adhesion, smoothness and uniformity. For this reason, there has been a demand for a coating method which can be mass-produced relatively inexpensively and has excellent adhesion, smoothness and uniformity. [0003] [Means for solving the problem] The present invention relates to a metal part of a metal electrode with ceramic in which a ceramic is brought into contact with a metal in a plating bath of a LiCl-KCl-based molten salt containing Zr ions. By electrolytically depositing Zr and simultaneously plating Zr or Zr alloy on ceramic,
Zr and Zr alloy can be coated on the ceramic. These films grow two-dimensionally on the ceramic from the contact portion between the metal and the ceramic. Zr, Ti, Fe, Ni on metal part of metal electrode with ceramic
Is used, a Zr film is formed on the ceramic, and when Al is used for the metal part, a Zr-Al alloy film is formed on the ceramic. The composition of the Zr-Al alloy changes depending on the plating conditions. The plating conditions were such that the Zr ion concentration of the plating bath was 1.5 × 10 ⁻² mol / dm ²
Then, in order to maintain the balance of the Zr ion concentration, metal Zr was used for the anode, and the anode was dissolved in Zr. Also set the bath temperature to 5
The temperature is set to 00 to 560 ° C., and plating is performed at a current density of 0.4 to 1.5 A / dm ² by a direct current or a pulse current. It is desirable to stir the bath to achieve more uniform plating. The reason for setting the bath temperature in the range of 500 to 560 ° C. is that Zr ions take divalent and tetravalent valences in the range of 450 to 560 ° C., and the abundance ratio changes depending on the temperature.
Since it has the property of being tetravalent at around 0 ° C. and divalent at around 550 ° C., Zr precipitates at 450 ° C. in a two-step reaction such as Zr (IV) → Zr (II) → Zr, Zr cannot be deposited stably. That is, low-valent ions are required to stably precipitate Zr, so that plating at 500 ° C. or lower is difficult. Also Z
rCl ₄ has a considerably high volatility at around 450 ° C., and a uniform plating cannot be obtained because the concentration of Zr ions in the bath decreases. Conversely, if the temperature is higher than 560 ° C., there is a disadvantage that the bath is decomposed. Next, regarding the current density, when the current density is lower than 0.4 A / dm ² , Zr is deposited on the metal part but plating on the ceramic becomes difficult, and when the current density is higher than 1.5 A / dm ^2. In addition, uniform plating with good adhesion cannot be obtained, and precipitates in a powdery or dendritic form. [0004] [Example] [0005] Example 1 A ceramic plate-like test piece containing Al ₂ O ₃ as a main component (2
mm thickness × 20 mm length × 10 mm width) was used as a plating base material, the surface was degreased with acetone, pickled and washed with 10% nitric acid, and dried.
Ti, Fe, Ni 2 mm thick x 9 mm long x 10 mm wide). Next, after drying the electrode with ceramic, electroplating was performed under the following conditions using a molten salt plating bath in a dry Ar atmosphere. As a result, the plating surface of each of the electrodes of any material was gray, and Zr plating with uniform and good adhesion was formed. [0006] Example 2 The same ceramic plate test piece as in Example 1 was attached so as to be in contact with the electrode serving as the cathode (material: Al 2 mm thick x 9 mm length x 10 mm width). Plating was applied. As a result, the plating surface has a silvery white color,
Uniform and good adhesion Zr-Al alloy plating was formed. As a result of composition analysis, the composition of the film was Zr45.1a.
t% and Al 54.9 at%. [Plating conditions] Bath composition: LiCl: KCl = 58.5 mol%: 4
1.5 mol% bath temperature: 540 ° C. Additive: Zr ion 1.5 × 10 ⁻² mol / d
m ² current density: 0.4~0.9A / dm ² positive electrode: Zr at between: 3 hours

Claims (1)

(Claim 1) [Claim 1] In a plating bath of a molten salt containing Zr ions, Zr is electrolytically deposited on a metal portion using an electrode in which ceramic is brought into contact with a metal, and at the same time, ceramic is deposited. Zr plating method on a ceramic, wherein Zr plating is performed on the ceramic. [Claim 2] In a plating bath of a molten salt containing Zr ions, Zr is electrolytically deposited on an Al portion using an electrode in which ceramic is brought into contact with a metal, and Zr-
A method for plating a Zr-Al alloy on a ceramic, comprising plating an Al alloy.