JPS6047903B2 - Low karat gold alloy for casting with golden color - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a low-strength rat gold alloy for casting, and more specifically, a castable rat gold alloy that exhibits a golden color similar to that of high-strength rat gold alloys and has high corrosion resistance despite having a low gold content. It is related to the gold alloy used for the purpose.

For example, gold alloys used as cast prosthetic materials such as dental inlays, crowns, and bridges are made by using a gold-silver-copper-palladium base alloy and adding appropriate amounts of platinum, indium, zinc, etc. corrosion resistance and mechanical strength,
The melting temperature etc. are adjusted.

These gold alloys have a beautiful golden color and good corrosion resistance, so they are extremely suitable for the above-mentioned uses. Recently, however, the price of gold has been on the rise, and in order to cope with the current situation, research is being actively carried out on gold alloys with lower gold content. -72921 No. 5
No. 2-29424, 53-472, 55-583
No. 44, Special Publication No. 56-479, No. 56-47941
No. etc. have been proposed. However, these rare gold alloys have fatal defects in that they exhibit the golden color characteristic of gold alloys and have poor corrosion resistance, and cannot have commercial value as precious metal materials. The inventors of the present invention have focused on the above-mentioned circumstances, and have conducted intensive research in an attempt to develop a gold alloy for casting that exhibits a golden color and corrosion resistance comparable to that of a 14-force rat gold alloy, even though it is a 14-force rat gold alloy. We have been progressing.

The present invention was completed as a result of such research, and its composition is: gold: 30 to 50% (weight %: the same below), silver: 5 to 35%, palladium: 5 to 15%, copper: 10
~20% and indium: 10-18% or more,
Or these elements and iridium: 0.1% or less,
The gist is that it consists of at least one element selected from the group consisting of platinum: 2% or less and zinc: 5% or less, and exhibits a golden color and high corrosion resistance comparable to 14-rat gold alloy. S5ru. The reasons for determining the types and blending ratios of alloying elements in the present invention will be explained below.

Gold: 30-50% It is an essential element for gold alloys, but in order to achieve the original purpose of reducing costs by making it a low-strength rat, 50%
is set as the upper limit.

On the other hand, the lower limit was set to ensure a golden color and high corrosion resistance comparable to 14-strength gold alloy, and if it is less than 30%,
Even if other alloy components are properly adjusted as described below,
It becomes impossible to obtain a satisfactory golden color and corrosion resistance. Silver: 5-35% Silver is an element that alloys well with gold, copper, and palladium.

In other words, it is a basic element that does not impair physical properties and is necessary to form a gold-colored, highly corrosion-resistant alloy, which will be described later. That is, for the same reason as gold, when gold and other elements are added, the composition range can be limited to 5 to 35% by itself as a base alloy element. Palladium 5-15% Palladium has the effect of giving the alloy a golden color and increasing its corrosion resistance, as well as increasing its melting temperature and improving its mechanical strength.In order to effectively exhibit these effects, it must be contained at 5% or more. Must be.

However, if it is too large, the golden color will diminish and it will turn white, and the melting temperature will become too high, making it rather brittle, so it is necessary to keep it below 15%. Indium Ni 10-18% Indium is the most important element in the present invention, and must be contained in an amount of 10% or more in order to exhibit a stable golden color even if the gold content is low.

Moreover, if it is too large, the melting temperature of the alloy becomes too low and the mechanical strength becomes poor, so it is necessary to suppress it to 18% or less. Copper: 10-20% Copper is an extremely important element for improving strength, and must be contained in an amount of 10% or more in order to achieve the purpose.

In addition, if the amount is too high, the corrosion resistance will decrease and the golden color will be lost after a short period of use, and the alloy will become too hard and have poor workability, so it is necessary to limit it to 20% or less. The essential constituent elements in the present invention are as described above, and if necessary, 1 selected from the group consisting of 0.1% or less iridium, 2% or less platinum, and 5% or less zinc.
By blending more than one element, the physical properties of the gold alloy can be further improved.

) That is, as is well known, iridium is effective in enhancing the effect of grain refinement in gold alloys, but at 0.1%
Exceeding this is not preferable because it impairs the uniform solid solution alloy structure and unnecessarily increases the price. Platinum is expected to have the same effect as iridium, and is effective in increasing the strength of the alloy, but if it exceeds 2%, the occurrence of cavities will increase somewhat, and the price will increase unnecessarily, which is not desirable. In addition, zinc refines the grains of cast alloys and acts as a matrix reinforcement and deoxidizing agent, which is extremely beneficial in further improving the physical properties of gold alloys. However, if it is too large, the elongation rate of the alloy decreases, so it must be kept at 5% or less. Although the contents of the individual constituent elements of the gold alloy according to the present invention are as described above, it is not necessarily appropriate to define the effects of these constituent elements only by their respective contents, and the actual formulation In this case, the optimum value should be selected and determined from among the above-mentioned preferred content ratios, while also considering the interaction of all the constituent elements.

Next, in order to further clarify the structure and effects of the present alloy, the differences will be explained while comparing it with known gold alloys.

Table 1 shows the composition, physical properties, and color tone of known gold alloys and the gold alloy of the present invention.

From Table 1, it can be considered as follows. Alloy No. l
is a commercially available dental 14-force rat gold alloy, alloy No. 2 is the same dental low-strength rat gold alloy, alloy No. 3 is the same dental silver alloy, and NO. Because of the high Au content of L, the alloy surface after polishing has a golden color, but the surface skin immediately after casting has a black color.

Even when the Au content is high as described above, the surface texture immediately after casting cannot necessarily be said to be good. Moreover, NO. with low Au content. 2 and silver alloy NO. The color tone of No. 3 immediately after casting was poor, and the surface texture after polishing did not exhibit a golden color. The reason why the Pd content is increased as the Au content decreases is to improve corrosion resistance. Alloy No. Nos. 4 and 5 are low-strength rat gold alloys, which were developed for use in baking porcelain, and have a high content of Pd and Pt, and are naturally white in color and are highly molten alloys. In other words, although it is a low-strength rat gold alloy, its purpose of use is completely different from that of the present invention. Alloy N
O. Nos. 6 to 8 were developed as low-strength rat gold alloys for casting, and although they are inexpensive, they do not have the golden color characteristic of gold alloys and have low commercial value. Alloy No. Nos. 9 to 11 are special gold alloys whose quality was improved by adding Ga without using Ag as an alloy component, but the color tone is no different from known low-strength rat gold alloys. Alloy No. 12 was invented for decorative purposes.

This does not contain In in its constituent elements, has a high Cu content, and has a low Pd content of 3%, so it cannot be expected to have high corrosion resistance for dental use. Alloy No. 13 is a silver alloy containing no Au at all, and naturally does not exhibit a golden color.

In this case, In is blended for the purpose of improving the corrosion resistance of the silver alloy, and the above-mentioned effect unique to the present invention (the effect of promoting golden color development due to Au) can be expected. Nor. Alloy No. 14 to 16 are comparative examples in which the amount of any constituent element is outside the specified range, and alloy NO.
．． 14 has an extremely poor color tone due to insufficient In content, and alloy No. 15 has poor corrosion resistance due to insufficient Pd content.

Furthermore, alloy NO. Since the amount of Cu in l6 is insufficient, the physical properties, particularly the elongation rate, are low and it cannot be put to practical use. In contrast to these, alloy NO.
Examples 17 to 20 are examples that satisfy all the requirements of the present invention, and have excellent mechanical properties on average, and exhibit a yellow surface immediately after casting, and a beautiful golden color after polishing.

Also, alloy NO. For l7-23, JIS-T6
When a discoloration test (observing the state of discoloration after being immersed in a 0.1% sodium sulfide aqueous solution at 37°C for an extended period of time) in accordance with Ill3 was conducted, no discoloration was observed, indicating that the product had excellent corrosion resistance. It was confirmed that The present invention is roughly constructed as described above, and provides a casting alloy that has corrosion resistance comparable to a 14-strength rat gold alloy and five golden colors, despite being a low-strength rat gold alloy with a low gold content. It turned out to be possible.

Claims (1)

[Claims] 1. Gold: 30-50% (weight %: same below), Silver: 5-50%
35%, palladium: 5-15%, copper: 10-20% and indium: 10-18%, and is characterized by having a golden color and high corrosion resistance. 2 Gold: 30-50% (weight%: same below), Silver: 5-50%
35%, palladium: 5-15%, copper: 10-20% and indium: 10-18%, iridium: 0.1%
A low carat gold alloy for casting, characterized by having a golden color and high corrosion resistance, comprising at least one element selected from the group consisting of platinum: 2% or less and zinc: 5% or less.