JPS6343781A - High corrosion resistant platinum clad material - Google Patents

Abstract

PURPOSE:To obtain the high corrosion resistant platinum clad material having excellent corrosion resistance and joining strength by using a high corrosion resistant metal as the core material and coating a platinum layer on the surface of this metal directly or via the intermediate layer consisting of a specific alloy. CONSTITUTION:An intermediate layer 2 is formed in cylindrical shape at the outer side in the radial direction of the core material 1 of a high corrosion resistant metal and a platinum layer 3 is formed in cylindrical shape at the outer side in the radial direction of the intermediate layer 2. The intermediate layer is taken of Ag-Pd alloy or Ni base alloy and the high corrosion resistant metal of Ti or Ti base alloy.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a platinum clad material with excellent corrosion resistance, which is used as ornaments such as eyeglass frames and rings, or as plating electrodes, medical parts, touch pads, etc. It is something.

[Prior Art] Precious metals such as gold and silver and their alloys are prized as molding materials or coatings for ornaments, arts and crafts, and the like. When using noble metals such as gold and silver as coating materials, the surface of a relatively inexpensive metal material (core material) is coated with the noble metal, and Ot! is used as a composite material. 8 has been done. However, such composite materials have the disadvantage that pitting may occur depending on the combination of the core material and the noble metal layer after years of use. Another drawback was that the bonding strength between the core material and the noble metal layer was not sufficient.

In recent years, a technology has been developed to form a noble metal layer on the surface of Ti or Ti alloy (hereinafter sometimes simply referred to as T1).
A method for coating noble metal foil with a thickness of .mu.m is already known (Japanese Patent Application Laid-Open No. 71547/1983). According to this, under conditions where different metals come into contact, the metal with a lower potential becomes the anode, and from the viewpoint that the larger the potential difference between the two, the faster corrosion progresses, Ti, which has a small potential difference with the noble metal, should be used as the core material. is recommended. However, even with this technique, the bonding strength between the Ti surface and the noble metal was not sufficient.

On the other hand, platinum (PT), like gold and gold alloys, is used in ornaments and as a corrosion-resistant metal, but the amount produced is smaller than that of platinum, and it is prized as an expensive metal. This kind of platinum...
In order to make full use of the potential, it has been desired to create a composite material that is relatively inexpensive and highly corrosion resistant, and is made of a solid core coated with a platinum layer.

[Problems to be Solved by the Invention] The present invention has been made under the above-mentioned circumstances, and as is clear from the above-mentioned purpose, the present invention aims to provide excellent corrosion resistance and joint strength. The object of the present invention is to provide a highly corrosion-resistant platinum crat material that exhibits excellent corrosion resistance.

[Means for Solving the Problems] The structure of the present invention achieves the above objects and 11 uses a highly corrosion-resistant metal as a core material, and directly or Ag-
The gist is that the platinum layer is covered with an intermediate layer made of a Pd alloy or a Ni-based alloy.

[Function] In order to achieve the above object, the present inventors conducted various studies and found that a highly corrosion-resistant metal used as a core material in manufacturing a highly corrosion-resistant platinum clad material (hereinafter simply referred to as platinum clad material) as a composite material. We have discovered that a desired platinum clad material can be obtained by coating the surface of the metal with a platinum layer either directly or by interposing a specific intermediate layer, depending on the type of metal.
The present invention has now been completed. For example, when Ti or a Ti-based alloy is used as the core material, a suitable intermediate layer is interposed, or when Ni or a Ni-based alloy is used as the core material, a platinum layer is directly coated on the surface of the core material. This makes it possible to realize a platinum clad material that can be fully utilized as ornaments and chemical instruments.

The platinum clad material constructed according to the present invention is manufactured, for example, as follows. That is, after creating a composite billet by coating the surface of a corrosion-resistant metal as a core material with a platinum layer directly or through an intermediate layer, the composite billet is subjected to hot isostatic pressure at an appropriate temperature that will not form a harmful alloy layer. After extrusion, plastic processing such as drawing is performed to a predetermined size. By going through such a process, it is possible to further strengthen the interfacial bonding strength of the platinum crat material. The platinum layer does not need to be pure platinum; any platinum alloy can be used, and any Ni alloy, Ti alloy, etc. as a core material may be used as long as they have corrosion resistance. Furthermore, there are no particular restrictions on the Ag-Pd alloy and Ni alloy used as the intermediate layer.

[Example] Hereinafter, the present invention will be explained in more detail with reference to Examples.

Example 1 First, a case where Ti (including Ti alloy) is used as the core material will be described. In this case, it is necessary to interpose an intermediate layer between the core material surface and the platinum layer, which is important in order to maintain the interfacial bond strength at a certain level and also to prevent corrosion due to the potential between the layers. is an element.

The inventors have used Ta, Ni-Cr-Co-Mn alloy, Zr, and
Ag-Pd was chosen. The measurement results of the self-potential of these old materials are shown in Table 1 below.

The measurement was performed by immersing the material in a 5% NaC] aqueous solution at room temperature, and a saturated calomel electrode (SCE) was used as the reference electrode.

Table 1 In the materials mentioned above, the self-potential takes a negative value except for the Ag-Pd alloy, and it is expected that the corrosion resistance of Ti (or Ti alloy) will improve if such a material is used as an intermediate layer. Ru. The natural potential referred to here is extremely important information for understanding the mechanism of the corrosion process of metals, and is a different concept from the standard potential.
ion potential).

Next, a billet with each material shown in Table 1 as an intermediate layer
We created the composite, processed the wire, and investigated the properties of the resulting composite. Among the materials in Table 1, Zr was excluded from the investigation because it became brittle when the intermediate layer cylinder was welded from a plate and had difficulty in weldability.

The 11th WI is a schematic explanatory diagram showing the structure of a billet. In FIG. 1, an intermediate layer 2 (thickness 0.5 mmt) is formed in a cylindrical shape on the radially outer side of a core material 1 (outer diameter 65 mmφ), and a platinum layer 3 is further formed on the radially outer side of the intermediate layer 2.
(*0.5 mmt) It is formed into a cylindrical shape. As the platinum layer 3, Pt900 (Pt90%; PdlO%
) was used. The gaps between the core material 1, intermediate layer 2, and platinum layer 3 are set to 0.1 to 0.2 mm, and dummy blocks 4 and 5 are provided at both ends of the core material 1 in the axial direction, respectively. Then, the end of the platinum layer 3 is welded and fixed to the dummy block 4.5.

With the billet assembled as shown in FIG.
Then seal it. A billet like this is heated to 650℃~800℃.
1 by heating in the temperature range of °C and hot isostatic extrusion.
After extruding into a bar with a diameter of 8 to 25 mm, the surface of the bar and the soundness of the intermediate layer 2 were confirmed. The extrusion pressure at this time was approximately 6200 kg/cm2 at an extrusion ratio of 14.7. Then, using the bar material, each pass with a drawing die
Finishing was performed to obtain a diameter of 2.0 mm with an area reduction rate of 5 to 20%.

Next, the present inventors investigated the weldability of the intermediate layer 2 (when processed into a cylindrical shape) during billet preparation, the difficulty of extrusion and wire drawing during processing, and the interfacial bonding status after processing. and corrosion resistance were evaluated. The results are shown in Table 2 below. Corrosion resistance test is salt water 1! The JI fog test was conducted using a method (CASS method) using a corrosive solution containing salt, acetic acid, and copper chloride.

As a result, the following evaluations were obtained.

(1) Regarding the weldability of the intermediate layer 2 during billet preparation, it was possible to process the weldability without any problem.

(2) For hot extrusion, N1-Cr-C.

-Mn alloy and Ag-Pd alloy were extruded without any problem, whereas Ta was used, cracks occurred and no sound material could be obtained.

(3) Regarding the difficulty of wire drawing and the interface bonding situation, Ni
No problem occurred when using the -Cr-Co-Mn alloy and the Ag-Pd alloy, respectively. Note that the bonding situation referred to here refers to the core material 1 and the platinum layer 3 in the intermediate layer 2.
means the relationship between both parties.

(4) Regarding corrosion resistance test, Ni-Cr-Co
- When Mn alloy or Ag-Pd alloy was used as the intermediate layer 2, did slight corrosion progress under long-term test conditions?
It was durable enough for use.

(5) Regarding ease of heat treatment, the relationship between heat treatment temperature and intermetallic compound formation status was investigated. As a result, N i
When -Cr-Co-Mn alloys or Ag-Pd alloys are used, a slight intermetallic compound layer is generated at temperatures above 650°C, and it is recognized that this layer grows to some extent as time passes and the temperature rises. Ta.

Therefore, N i -Cr -Co -M n and Ag-P
When using the d-alloy as the intermediate layer 2, it is necessary to pay particular attention to the processing temperature and time during brazing. In other words, if the processing conditions are good, N1-Cr
-Co-Mn and Ag-Pd alloys are sufficiently usable as the intermediate layer 2.

As is clear from the results in Table 2, Ti as core material 1
In the case of cladding platinum using the intermediate layer 2, Ni-Cr-Co-Mn and Ag-Pd can be used. On the other hand, Ta is not preferable for the intermediate layer 2 because it causes cracks. In addition, when considering corrosion resistance and alloy layer formation, when N1-Cr-Co-Mn or Ag-Pd is used as an intermediate layer, it can withstand use sufficiently depending on the application or as long as care is taken during construction. Platinum clad material can be realized.

Example 2 As is clear from the above example, N is used as the intermediate layer 2.
Considering that a sound platinum clad material was obtained even when i-Cr-Co-Mn was used, it is clear that the interfacial bondability between the Ni-based alloy and platinum is good. Therefore, the present inventors attempted to use Ni (or Ni-based alloy) as the core material 1 and directly coat the surface of the core material 1 with the platinum layer 3. The billet structure in this case is the same as that shown in FIG. 1 except that the intermediate layer 2 is not provided, and all other conditions are the same. The results are shown in Table 3 below.As is clear from the results in Table 3, Ni (or Ni-based alloy)
When the yield was 1, good results were obtained even when the platinum layer 3 was directly coated on the surface of the core material 1. That is, in the past, when Ni (or Ni-based alloy) was used as the core material 2 and the surface of the core material was coated with a layer of noble metal such as gold or silver, there was a drawback that pitting corrosion occurred after many years of use. However, such a tendency was not observed for platinum.

[Effects of the Invention] As described above, according to the present invention, by employing the above-described configuration, a platinum clad material that exhibits excellent effects in both corrosion resistance and bonding strength was realized.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing an example of a billet structure constructed according to the present invention. 1... Core material 2... Intermediate layer 3... Platinum layer 6... Deaeration pipe 4.5... Tummy block Figure 1

Claims (2)

[Claims] (1) A highly corrosion-resistant platinum clad material, characterized in that a highly corrosion-resistant metal is used as a core material, and a platinum layer is coated on the surface of the metal directly or via an intermediate layer made of an Ag-Pd alloy or a Ni-based alloy. (2) The highly corrosion resistant metal is Ti or a Ti-based alloy, and Ag
- The highly corrosion-resistant platinum clad material according to claim 1, which is coated with a platinum layer via a Pd alloy or a Ni-based alloy. (3) The highly corrosion-resistant platinum clad material according to claim 1, wherein the highly corrosion-resistant metal is Ni or a Ni-based alloy, and is directly coated with a platinum layer.