JPH0417636A - Copper alloy for metallic industrial art casting having pear-skin tone - Google Patents

Abstract

PURPOSE:To easily manufacture lustrous Cu alloy industrial art castings having a pear-skin tone at a low cost by casting a molten metal obtd. by adding specified amounts of CuO, Sn and specified metals to Cu. CONSTITUTION:A Cu alloy having a compsn. contg., by weight, 0.2 to 10.0% CuO, 0.2 to 10.0% Sn, total <=40.0% of one or >=2 kinds among the metals such as Zn, Pb, As, Ni, Ag and Au with Sn and the balance Cu is refined by a high frequency electric furnace. This Cu alloy molten metal is cast to manufacture Buddhist altar fittings, flower vases, tea-things, desk wear or the like. The industrial art objects made of the Cu alloy having a beautiful pear-skin tone can be manufactured at a low cost.

Description

[Detailed Description of the Invention] [Object of the Invention] (Field of Industrial Application) The present invention relates to copper alloys for metal crafts such as Buddhist utensils, flower vases, tea utensils, deskware, etc. The purpose of the present invention is to provide an excellent copper alloy for metal craft casting.

(Prior art) In general, copper alloys for metal craft casting are mainly brass-based alloys and bronze-based alloys, and are used for various types of decorative and practical items such as Buddhist altar fittings, flower vases, tea utensils, deskware, etc. has been done. These decorative and practical items have an astringent taste,
The surface is finished in a satin finish to give it a sense of solidity and luxury.

In particular, zinc is 8 to 20% by weight as a copper alloy that exhibits a matte finish.
, α single-phase brass with the balance being copper is used.

This alloy is refined and the crystals are embossed, resulting in a speckled pattern made up of countless small crystals, giving it a satin-like appearance. It is also known that annealing makes the crystals even clearer, and it is used in metal craft castings such as flower vases and tea utensils.

On the other hand, fine irregularities can be created on metal crafts using physical and chemical methods such as sandblasting, in which particles of refractories, metals, or resins are sprayed onto the metal surface, and etching, which uses the corrosive action of ferric chloride. A method is used in which the material is formed to give a matte finish.

However, in the conventional alloys mentioned above, the size of the crystal grains becomes uneven depending on the shape and wall thickness of the cast product, and the crystal grains are thicker near the final solidification of the sprue, runner, etc. than in other parts. Therefore, in order to make the crystal grains uniform by controlling the solidification of the entire cavity, it is necessary to control the casting method, the temperature of the molten metal, the mold, etc. in a very precise manner.

Furthermore, in the conventional method described above, heat treatment is performed to make the satin-like pattern clearer, but when alpha single phase brass is annealed at 200° C. or lower, there is a problem in that low-temperature annealing hardening occurs.

Furthermore, sandblasting and etching methods have the disadvantage that the smoothness of the processed area is impaired and the satin-like appearance lacks luster.

In view of these points, the present inventors developed a method of adding tin oxide or a master alloy consisting of tin and tin oxide to a copper-based alloy in order to produce metal crafts with a satin finish. Suggested patent application number: Japanese Patent Application No. 2-13083), α
We have made it possible to create a satin-like appearance using not only single-phase brass but also various copper alloys.

(Problems to be solved by the invention) Since tin oxide has a high melting point, it takes time to melt, and because it is in powder form, it scatters during stirring and adheres to the crucible wall, resulting in poor workability. In order to solve this problem, an ingot of a master alloy consisting of tin and tin oxide was prepared in advance, and the ingot was mixed with copper and other necessary materials.

However, due to the poor reactivity between tin and tin oxide, it takes time to manufacture the master alloy, which causes problems such as evaporation and loss of tin and worsening the working environment. . Furthermore, tin oxide is more expensive per unit weight than other components, making the product much more expensive than conventional products.

The present invention has been made in view of these points,
The purpose of the present invention is to provide a copper alloy for metal craft casting, which has a conventional lustrous satin finish and is significantly improved in workability, at a lower cost.

[Structure of the Invention] (Means for Solving the Problem) The steel alloy for metal craft casting of the present invention, which has solved this problem and exhibits a satin tone, has an oxidized steel of 0.2 to IO, O3i setting,
0.2 to 10.0% by weight of tin, and 1 m or more selected from the group consisting of zinc, lead, arsenic, nickel, silver, and gold, in a total amount of 40.0% by weight with the above tin. It is characterized by containing the following, with the remainder consisting of copper and unavoidable impurities.

A portion of the tin in the copper alloy reduces copper oxide through a reaction during melting, and exists in the molten metal as tin oxide. After casting and polishing this molten metal, it is immersed for a certain period of time in an aqueous solution containing a small amount of copper sulfate, patina, etc., or it is immersed in a small amount of an aqueous solution of acetic acid, steel sulfate, patina, etc. During the coloring process, the tin oxide-containing phase precipitated during molten metal solidification differs in color from other phases, resulting in a fine spot-like pattern of the tin oxide-containing phase precipitated throughout the casting. It was discovered that the material rose to the surface and exhibited a beautiful satin-like appearance similar to that produced by adding tin oxide and a master alloy of tin.

Copper oxide is added and blended while stirring the molten metal, dispersed uniformly in the molten metal, and tin is oxidized by a reaction in the molten metal to produce a copper alloy containing tin oxide. However, the concentration of tin in the molten metal The reaction between copper oxide and tin does not proceed due to problems such as scattering during stirring and adhesion to the crucible wall because it is in powder form.

For this reason, it is desirable to prepare an ingot of a master alloy consisting of tin and copper oxide in advance, to oxidize the tin at this point, and to mix the ingot with copper and other necessary materials.

By the way, this reaction for producing an ingot has excellent reactivity because it is an exothermic reaction, and the workability during production of a master alloy ingot is very good.

After casting, the molten metal of a copper alloy containing tin oxide, which is obtained by oxidizing tin with copper oxide, decreases in temperature and eventually solidifies. The solidification rate varies depending on the type of mold, such as a sand mold or a metal mold, but in all cases, a phase containing initial tin oxide precipitates during the cooling process of the molten metal, then other phases precipitate, and eventually solidification ends.

As a result, a cast product that has undergone such a solidification process has a phase containing fine tin oxide dispersed throughout the cast product.

If the content of copper oxide is less than 0.2% by weight, the amount of tin oxide precipitated during solidification will be small (the desired matte finish will not be achieved), and if the content exceeds 10% by weight, the amount of oxide in the cast product will be low. The copper oxide content was limited to 0.2 to 101% by weight because the copper oxide content increases and becomes hard and brittle, resulting in a decrease in rigidity.

Tin is necessary to generate tin oxide in the mother alloy with copper oxide, and if the tin content is less than 0.2% by weight, the amount of tin oxide precipitated during solidification will be small and the desired matte finish will not be achieved. . On the other hand, like zinc and lead, it has a lower melting point than copper, so it lowers the melting temperature of copper alloys and improves the flowability of molten metal. Moreover, if it exceeds 10.0% by weight, it becomes hard and brittle, and the rigidity also decreases, as in the case of tin oxide. Therefore,
The tin content is 0.2 to 10. The cap was limited to 1%.

The amounts of zinc and lead to be added are determined as appropriate as the remainder of tin oxide and other necessary alloy compositions.

When arsenic is contained in a copper alloy, it has the effect of making the surface blackish in a coloring method in which the copper alloy is immersed for a predetermined time in a coloring solution, that is, an aqueous solution containing a small amount of copper sulfate, verdigris, etc. Due to its coloring effect, 80% copper by weight can be used as needed.
It is added and blended in a mother alloy containing 20% by weight of arsenic. Arsenic 0.
2! If the amount is less than %, the coloring property is poor (the degree of blackening decreases,
If it exceeds 1.5% by weight, the degree of blackening will be high and the satin finish will be impaired. Preferably it is 0.2 to 1.5i%.

By including nickel, silver, gold, etc. in copper alloys, beautiful metal crafts can be obtained. They are respectively called nickel silver, IN copper, and shakudo, and each is a copper-based alloy used for boat fishing.

As mentioned above, if IN or two or more materials selected from the group consisting of zinc, lead, arsenic, nickel, silver, and gold and tin are contained in the copper alloy in a total amount exceeding 40.0% by weight, , the colorability deteriorates, and as a result, the satin-like tone is impaired.

[Example code] Next, one embodiment of the present invention will be described.

An alloy having the composition shown in Table 1 was melted in a small high-frequency electric furnace and cast into a sand mold to obtain a test material of 5 mm thick x 50 mm diameter, and the cast surface was milled by 1 mm. Next, add 1 layer of water after degreasing.
80 mixed with 2g of each copper sulfate and patina in 000cc
The test material was immersed in a spot liquid at ~90°C for 15 minutes, and the appearance of satin tone was visually observed to evaluate. The degree of occurrence of satin tone is classified into three types: O, O, and X, with 01 indicating clear expression, 01 indicating expression, and × indicating no expression, and the results are shown in Table 1 along with comparative alloy compositions. It was shown to.

The results are shown in Table 1, and copper alloys Nos. 1 to 7 and 12 according to the present invention exhibiting a satin tone had a spotted pattern due to the precipitation of tin oxide, and exhibited a satin tone. Note that Comparative Examples Nos. 8 to 11 did not exhibit a matte finish.

The following margin [Effects of the Invention] As can be easily understood from the above description, the steel alloy for metal craft casting exhibiting a matte finish of the present invention contains not only brass and bronze but also nickel, copper, and gold. It is now possible to create a beautiful satin finish even on copper alloys, and it is also cheaper than before, so it is very useful in metal craft castings such as Buddhist altar fittings, flower vases, tea ceremonies, and desk wear.

Claims (4)

[Claims] (1) In weight% (1) Copper oxide 0.2-10.0% (2) Tin 0.2-10.0% (3) One or more selected from the group consisting of zinc, lead, arsenic, nickel, silver, and gold, together with the above tin, in a total amount of 40.0% or less (4) A copper alloy for metal craft casting, which exhibits a satin finish and is characterized by the remainder being copper and unavoidable impurities.