JPS646261B2 - - Google Patents

Description

[Detailed description of the invention]

Conventionally, gold alloys, silver alloys, and gold-silver-palladium alloys have been used as alloys for dental casting. However, in recent years, where prices of precious metals such as gold, silver, and palladium have fluctuated significantly, nickel-chromium alloys for casting have attracted attention. Conventional nickel-chromium alloys for casting often have relatively high melting points.
Since melting and casting is difficult with a city gas-oxygen mixed flame, melting and casting is carried out using a high-frequency induction heating melting and casting machine or an electric arc heating melting and casting machine. In addition, there are only a few alloys on the market that can be melted with a city gas-oxygen mixed flame, but they are hard and difficult to cut and polish, or they have many casting defects and a high incidence of defective products. Either. The present invention lowers the melting temperature and is capable of high-frequency induction heating melting, electric arc heating melting, and city gas-oxygen mixed flame melting, and is soft and easy to cut and polish, making it convenient for technical work and treatment work for dentists. There are various advantages when the device is placed in the patient's oral cavity. The main ones are as follows. This alloy has a relatively low melting point and the viscosity of the molten metal during melting is low, so it is easy to melt and cast using a city gas-oxygen mixed gas flame, and there are few casting defects and no defective products. Since this alloy has low hardness, it is easy to cut and polish not only for technical work but also when dentists perform occlusal adjustment in the oral cavity. This alloy causes less wear on the natural opposing teeth during occlusion after being placed in the oral cavity. The present invention relates to a nickel-chromium alloy for dental casting that is suitable for such uses. The conditions that should be met as a nickel-chromium alloy for dental casting are as follows. (b) No discoloration in the oral cavity. (b) The hardness of the alloy must be within 220 bits so that cutting and polishing can be easily performed. (c) The melting temperature must be within 1370℃ so that it can be easily melted by high-frequency induction heating, electric arc heating, and city gas-oxygen mixed flame. (d) After casting, the surface of the cast body should be smooth, there should be no casting defects, and there should be no defective products. The scope of the claims will be examined in order to satisfy the four conditions (a) to (d) above, and the reasons for the limitations will be explained as follows. For item (a), it was decided to add less than 7 to 15% chromium. The reason for this is that if it is less than 7%, there is a risk of discoloration, so the minimum content was set at 7%. On the other hand, chromium 15
If it is added in an amount exceeding 15%, the hardness of item (b) will increase and cutting and polishing will become difficult, so the maximum value was set to less than 15%. The reason for adding 1.0 to 4.0% silicon is to lower the melting temperature in item (c) and to reduce the viscosity of the molten metal during melting in item (d) to improve castability. It also has a great deoxidizing effect. If less than 1% of silicon is added, the melting temperature in item (c) will not be lowered, and the castability in item (d) cannot be improved, so the minimum amount of silicon was set at 1%. If more than 5% is added, the hardness in item (b) will increase and it will become brittle, so the maximum content was set at 5%. Addition of manganese lowers the melting temperature in item (c) and has a large desulfurization effect. But 1
If added in excess of 1%, a film will be formed on the surface of the molten metal during melting, making it difficult to judge the timing of casting, so the maximum addition was set at 1%. The purpose of adding molybdenum is to improve the casting surface of the cast body after casting in item (d), reduce casting defects, and eliminate the occurrence of defective products. Molybdenum is less than 3%
Since it is impossible to eliminate the occurrence of defective products in item (d), the minimum value is set at 3%.Additionally, if it exceeds 10%, the melting temperature in item (c) will increase, and the hardness in item (b) will increase. The maximum was set at 10% because of the increase in The addition of boron not only lowers the melting temperature in item (c), but also has a deoxidizing effect, or improves the mold release effect between the cast body and the investment material after casting, and smooths the surface of the cast body in item (d). This is to make it happen. However, if it is added in excess of 0.1%, the hardness of item (b) increases, making cutting and polishing difficult. It also causes high-temperature cracking and increases the number of defective products in item (d), so the maximum value was set at 0.1%. Furthermore, adding copper is effective in lowering the melting temperature in item (c), and also has the effect of reducing the hardness in item (b), making it softer and easier to cut and polish. Addition of germanium or gallium is most effective for lowering the melting temperature in item (c).
The more germanium and gallium are added, the more effective it is, but if more than 2% germanium or 0.5% gallium is added, the hardness of item (b) will increase and become brittle, so the maximum germanium 2%, Or 0.5% gallium. and germanium
Since the effect is not significant when the addition amount is less than 0.5% or the addition amount of gallium is less than 0.05%, the minimum addition amount is set to 0.5% germanium or 0.05% gallium. Next, the explanation will be supplemented by giving examples. Example

【table】

[Table] When the alloy of the present invention was cast by a conventional method, good results were obtained in terms of castability, casting surface, cutting abrasiveness, and compatibility.

Claims (1)

[Claims] 1. Chromium: 7 to less than 15%, manganese: 1.0% or less, silicon: 1.0 to 5.0%, molybdenum: 3.0 to 10%, boron: 0.1% or less, germanium or/and gallium, by weight ratio : Nickel-chromium alloy for dental casting, consisting of 0.05 to 2.0%, the balance being nickel. 2 In terms of weight ratio, chromium: 7 to less than 15%, manganese: 1.0% or less, silicon: 1.0 to 5.0%, molybdenum: 3.0 to 10%, boron: 0.1% or less, copper: 1.0 to
5.0% germanium or/and gallium:
A nickel-chromium alloy for dental casting, consisting of 0.05 to 2.0%, the balance being nickel.