JPH03188233A - Surface hardened color silver alloy - Google Patents

Abstract

PURPOSE:To obtain the Ag alloy developing into multicolors, having high hardness and suitable for ornaments by subjecting a green compact by an alloy of metals easy to form a compound with boron and Ag to boronizing treatment. CONSTITUTION:To the powder of Ag, 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 and Mn 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 and is thereafter pressurized and compacted, e.g. into a disk shape. The green compact is sintered in a vacuum furnace, is thereafter immersed into molten salt constituted of a borax and boron carbide and is subjected to boronizing treatment. The Ag alloy developing into various color tones different according to the kinds of the above metals to be used together with Ag, 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 silver alloy used for decorative articles.

[Summary of the invention]

Conventionally, the color tone of silver or silver alloys was only silver-white. In this method, an alloy of silver and a metal that forms boride is made, and boron is diffused and penetrated from 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 silver alloys multicolored include fl, l.
Utilizes the color of silver intermetallic compounds.

(2) Composite silver 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 containing (:, r, Fe, and Ni added to the gold) was subjected to boriding treatment to harden the surface. (Fukuhisa Matsuda, Metal Magazine, 1983) 7
Monthly issue 40-4 1 However, these Cr, Fe, N
The boride of i is hard and has excellent abrasion resistance, making it suitable for industrial applications; however, all of the borides exhibit a silvery white color and are not suitable for ornaments.

[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 silver is borated, it does not produce boride, so new colors cannot be obtained from boride.

In this invention, we will develop various silver 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 silver alloy was created by alloying silver with boron and an additive metal that easily forms a compound. Boron was diffused into the surface of this alloy to form borides of these additive metals in the surface layer. Additive metals may form an alloy with silver and form a solid solution with the silver, or may disperse in the silver alloy without forming a solid solution. In either case, the added metal forms a boride through the boriding process,
Its surface color is red and blue, strongly influenced by borides.

Its hardness varies depending on the type of boride and the ratio of gold to additive metals, but its Pinkers hardness ranges from Hv200 to Hv1500.The depth is about 0.06mm, and it is scratch-resistant and glossy. It was an excellent ornament.

The added metals are 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,
One or more of Nb, Ta, Mo, W, and Mn was added in an amount of 5 to 40%. Table 1 shows the color tones of these added metal borides. (Cited document: Handbook of High Melting Point Compounds, Nisso Press) [Operation] 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 Ag powder and 20 parts of Sm powder were crushed, mixed and granulated in a ball mill for 4 hours, and then pressure-molded into a disk having a diameter of 10 m. This molded body was placed in a vacuum furnace and heated to 1050°C.
It was sintered 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 silver 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 boride (SmB&) was dispersed in the surface layer, the layer thickness was 0.05 m-, and the hardness was HVIloo.

[Example 2] Hf was applied to the surface of a 10 x 30 x 1 m Ag plate by an ion blasting method. This Ag plate was heated at 800° C. for 3 hours in a vacuum to diffuse and infiltrate Hf into the Ag plate to form a silver-hafnium alloy only in the surface layer. This plate was 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.750
C. for 5 hours to obtain a boride-dispersed silver alloy.

The polished surface of the obtained plate was blackish gray with a metallic luster and had decorative value. Further, the layer thickness was 3- and the hardness was HV560.

〔Effect of the invention〕

With this invention, the color of silver alloys, which was previously limited to white and silver, can now be produced in almost any color, including red, three 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, TbDy, Ho, E
r, Tm, Yb, Lu, Th, U, Zr, Hf, V, N
b, Ta, Mo, W, Mn in a total of 5 to 40% (wt%, same hereinafter) of one or more types, and the rest is Ag, and is characterized by being subjected to boriding treatment. Surface hardened color silver alloy.