JPH03188231A - Surface hardened color platinum alloy - Google Patents

Abstract

PURPOSE:To obtain the hard Pt alloy developing into multicolors and suitable for ornaments by compacting an ornamental member by an alloy of metals easy to form a compound with boron and platinum and subjecting the green compact to boronizing treatment. CONSTITUTION:To the powder of Pt, one or >=2 kinds among Be, Mg, Ca, Sr, Ba, Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Th, U, Zr, Hf, V, Nb, Ta, Mo, W, Mn, etc., brought into reaction with B and forming a colored compound are added and mixed so that the total amt. will be regulated to 5 to 40wt.%, and the mixture is granulated, is thereafter pressurized and compacted, e.g., into a disk shape and is thereafter sintered in a vacuum furnace. The sintered compact is immersed into molten salt constituted of a borax and boron carbide and is subjected to boronizing treatment. The Pt alloy developing into various color tones according to the kinds of elements to be used together with Pt, having high hardness owing to borides and suitable for ornaments can be obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] This invention relates to a colored platinum alloy used for decorative articles.

[Summary of the invention]

Conventionally, platinum or platinum alloys have had a silvery white color tone. In this method, an alloy of platinum and a metal that forms boride is made, and boron is diffused and penetrated through the surface of the alloy, producing boride with colors such as red, blue, and black on the surface layer.

[Conventional technology]

Conventionally, methods for making platinum alloys multicolored include 1)
Utilizes the color of platinum's intermetallic compounds.

(2) Composite platinum with oxides, carbides, nitrides, etc.

are considered, but all have one tone of intensity.

Due to problems with its appearance as a decorative item, it has not been commercialized.

On the other hand, as a surface treatment, an example has been reported in which a gold alloy in which Cr, Fe, and Ni are added to gold is subjected to boriding treatment to harden the surface. (Fukuhisa Matsuda, Metal Magazine, July 1983
However, these Cr, Fe,
Ni boride is hard and has excellent abrasion resistance, making it suitable for industrial applications, but its color is silvery white, making it unsuitable for decorative items.

[Problem to be solved by the invention]

Developing a new color by focusing on the boron treatment of the top layer gold.

Even if pure platinum is subjected to boriding treatment, no boride is created, so
New colors cannot be obtained with borides.

In this invention, we will develop various platinum alloys that can be colored in multiple colors by subjecting them to boriding treatment, and apply them to ornaments.

[Means to solve the problem]

A platinum alloy was created by alloying platinum with an additive metal that easily forms a compound with boron. Boron was diffused into the surface of this alloy to form borides of these additive metals in the surface layer. The additive metal may form an alloy with platinum, form a solid solution with platinum, or may disperse in the platinum alloy without forming a solid solution. In either case, the added metal forms a boride through the boriding process, and the color tone of its surface is strongly influenced by the boride, resulting in red, blue, black, etc., and its hardness depends on the type of boride.
Vickers hardness H varies depending on the ratio of gold and additive metals.
It ranges from V200 to Hv1500, and its depth is 0.
It was about the same size as 06 ■, and was excellent as a scratch-resistant, glossy decorative item.

The added metals are Be, Mg, Ca, Sr, Ba, Sc.
, Y, La, Ce, Pr, Nd, Sm.

Eu, Gd, Tb, Dy, Ho, Br, Tm, Yb, L
u, Th, U, Zr, Hf, V, Nb, T3, MO, W
, Mn, and the amount added is 5 to 40.
%. Table 1 shows the color tones of these added metal borides. (Cited document: Handbook of High Melting Point Compounds, Nisso Press) (Effect) The reason for limiting the amount added is from 5% to 40% is that below 5%, the color tone of boride is produced, and when it exceeds 40%, the color tone is poor. However, this is because the brittleness peculiar to borides appears and the strength required for decorative items cannot be met.

Next, an explanation will be given along with examples.

Table 1 [Example 1] 80 parts of Pt powder and 20 parts of Sm powder were pulverized, mixed and granulated in a ball mill for 4 hours, and then pressure-molded into a disk having a diameter of 10 cm. This molded body was placed in a vacuum furnace and
It was sintered at ℃ for 3 hours. After removing the thin scale on the surface of this fired crystal, it was subjected to boriding treatment.

In the boriding treatment, a molten salt consisting of 60 parts of borax and 40 parts of boron carbide was maintained at 850°C and immersed therein for 3 hours. Thereafter, it was taken out from the molten salt to obtain a boride-dispersed platinum alloy.

The polished surface of the obtained disc was blue with a metallic luster and had decorative value. A part of it was cut out and its cross section was observed under a microscope.

Blue samarium poride (SmBb) was dispersed in the surface layer, the layer thickness was 0.05 fl, and the hardness was HVIloo.

[Example 2] 1 n of Hf was applied to the surface of a Pt plate measuring 10 x 30 x 1 m by the ion blasting method. This Pt plate was heated in a vacuum at 800° C. for 3 hours to diffuse and infiltrate Hf into the Pt plate, thereby forming a platinum-hafnium alloy only in the surface layer. This plate is embedded in a mixed powder consisting of 8 parts of boron carbide powder, 1 part of boron carbide powder, and 1 part of ammonium chloride powder.75
The mixture was kept at 0° C. for 5 hours to obtain a boride-dispersed platinum alloy.

The polished surface of the obtained plate was blackish gray with a metallic luster and had decorative value. Further, the layer thickness was 3n, and the hardness was Hv560.

〔Effect of the invention〕

With this invention, the color of platinum alloys, which was previously limited to white and silver, can now be produced in almost any color, including red, blue, and black, expanding its use for decoration.

that's all

Claims (1)

[Claims] Be, Mg, Ca, Sr, Ba, Sc, Y, La, Ce
, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho,
Er, Tm, Yb, Lu, Th, U, Zr, Hf, V,
A Pt alloy containing one or more of Nb, Ta, Mo, W, and Mn in a total of 5 to 40% (by weight, the same hereinafter) and the remainder being Pt is subjected to boriding treatment. Surface hardened color platinum alloy.