RU2224809C1 - Deformable alloy based on nickel for ceramic-metal dental prosthetics with increased physico-mechanical characteristics - Google Patents

Abstract

FIELD: metallurgy; production of alloys based on nickel for manufacture of ceramic-metal dentures. SUBSTANCE: the invention is dealt with metallurgy, in particular, with the based on nickel alloys with increased physico-mechanical characteristics, that may be used for manufacture of the metal skeletons of dentures with a ceramic covering. Technical result of the invention is increase of hot deformability of the alloys and increase of output of good product at metallurgical hot conversion, and also increase of a level of mechanical characteristics and decrease of temperature factor of linear extension at preservation of a level of corrosion-resistance and casting properties, as well as workability by stomatological abrasives and polishability of the alloy. The alloy on the basis of nickel for ceramic-metal dentures contains: carbon, silicon, manganese, chromium, molybdenum, niobium, iron; boron and yttrium at the following ratio of components (in mass %): carbon - no more than 0.03, silicon - 0.9-1.6, manganese - 0.3-0.8, chromium - 23.0-26.0, molybdenum - 8.5-10.5, niobium - 0.8-1.7, iron - no more than 0.5, boron - 0.001-0.020, yttrium - 0.001-0.020, nickel and inevitable impurities - the rest. At that nickel contents makes of no more than 64 mass %, and the total content of molybdenum and niobium is bound with the following dependence: [%Mo] + [%Nb] = 9.7 - l 1.7. EFFECT: increased hot deformability of the alloys, output of good product at metallurgical hot conversion, corrosion-resistance and casting properties, workability by stomatological abrasives and polishability. 2 tbl, 3 ex

Description

The invention relates to the field of metallurgy, in particular to nickel-based alloys intended for the manufacture of metal frames for ceramic-coated dentures.

Alloys intended for these purposes must meet the requirements of the international standard ISO 6871-2-94 “Dental casting alloys based on metal. Part 2. Nickel-based alloys ”, as well as the Russian standards GOST R 51767-2001“ Billets from nickel-based alloys for prosthetic dentistry ”and GOST R 51736-2001“ Dental metal-ceramics for dental prosthetics ”.

In accordance with these requirements, alloys for casting cermet dentures must:

- have good casting properties: high fluidity and minimal shrinkage, allowing to obtain accurate thin-walled castings of metal frames of dentures (crowns, bridges);

- have sufficient strength and ductility to prevent deformation of the prosthesis in the patient's oral cavity; in accordance with the above standards, the tensile strength of the alloy (σ _0.2 must be at least 250 N / mm ² with a relative elongation of at least 3% and a Vickers hardness of at least 150 HV10;

- have a low temperature coefficient of linear expansion (TEC) close to the TEC value of the ceramic coating;

- provide high adhesion with ceramic cladding by creating a strong oxide film on the surface of the alloy;

- have high corrosion resistance in the oral cavity, be non-toxic and not carcinogenic;

- It is well processed by dental abrasives and polished.

In addition, according to the All-Russian Research and Testing Institute of Medical Technology (VNIIIMT), to exclude the occurrence of allergic reactions in patients using nickel-based dental alloys (manifested in a burning sensation of the mucous membrane, its swelling, etc.), they should contain no more 65% nickel, as well as at least 20% chromium and 4% molybdenum. In this case, the resulting oxide film prevents the migration of nickel ions into the environment (oral cavity).

Known alloy based on Nickel for dentures, including ceramic, containing the following components, wt.%:

Chrome 22.0 - 25.0

Molybdenum 5.5 - 7.5

Silicon 2.0 - 4.5

Boron 0.25 - 0.50

Aluminum ≤0.2

Iron ≤0.5

Carbon ≤0.05

Copper ≤0.5

Manganese ≤0.5

Sulfur ≤0.01

REM 0.05 - 0.20

Nickel Else

(European patent No. 0275843 B1 IPC C 22 C 19/05, A 61 K 6/04, publ. 08.07.1992).

The properties of the alloy are as follows: hardness HV10 = 200-210; yield strength σ _0.2 = 266 N / mm ² ; tensile strength σ _in = 470-518 N / mm ² ; elongation δ = 6.5-8%; LTEC in the temperature range of 25-600 ° C 14.3 ÷ 15.1 × 10 ^-6 K ^-1 .

This alloy, although it has values of strength, ductility and hardness that meets the requirements specified in the above standards, but based on the experience of dental practice, this level of properties is low, since it practically corresponds to the lower level specified in the standards. In addition, this alloy has a rather high TEC value, which limits the possibility of lining it with various porcelain masses.

Known alloy based on Nickel for the manufacture of molded dentures with a ceramic coating, containing the following components, wt.%:

Chrome 23 - 25

Molybdenum 9 - 10

Silicon 1.4 - 1.9

Iron 0.5 - 1.0

Manganese 0.1 - 0.3

Carbon 0.008 - 0.02

Cerium 0.03 - 0.1

Nickel Else

(RF patent No. 2048574, C 22 C 19/05, publ. 11/20/1995).

Alloy properties: tensile strength σ _in = 530-570 N / mm ² , elongation δ = 27-28%, Vickers hardness 200-220 HV10, TECL = 13.9 × 10 ^-6 deg ^-1 in the temperature range 25- 500 ° C.

Despite the fact that the physicomechanical properties of this analogue are higher than those of the previous one, based on the experience of dental practice, they are not sufficient for the manufacture of long-length metal-ceramic bridges.

The closest analogue of the invention is an alloy for dentures based on Nickel, containing the following components, wt.%:

Nickel 58 - 68

Chrome 18 - 23

Molybdenum 6-10

Niobium + Tantalum 1 - 4

Iron 0.02 - 2.0

Silicon 0.01 - 0.5

Manganese 0.01 - 0.4

Titanium 0.01 - 0.2

Aluminum 0.01 - 1.0

Carbon 0.01 - 0.1

REM 0.05 - 5

(German patent No. 2946863, IPC C 22 C 19/05, A 61 K 6/04, publ. 11/19/1987 - prototype).

Typical properties of the alloy: tensile strength σ _in - 527.3 N / mm ² , yield strength σ _0.2 - 379.7 N / mm ² , elongation - 8%, hardness HV - 200, TLCR - 14 × 10 ^-6 hail ^-1 .

This alloy has higher yield strengths, however, ductility (elongation) remains at a low level with practically the same as the previous alloy, sufficiently large TEC values.

The problem to which the invention is directed, is to create a deformable nickel-based dental alloy for cermet dentures that combines the following set of properties:

- good deformability in the hot state, that is, manufacturability during metallurgical redistribution;

- increased mechanical characteristics (strength and ductility);

- low values of thermal expansion coefficient in the range of crystallization temperature of ceramics 20-500 (600) ° С, close to thermal expansion coefficient of ceramics, and good adhesion to it;

- high corrosion resistance and biocompatibility with tissues of the oral cavity, lack of toxicity and carcinogenicity;

- good casting properties, machinability with dental abrasives and polishability.

The technical result of the invention is to increase the hot deformability of the alloy and increase the yield during metallurgical processing, as well as to increase the level of mechanical characteristics and decrease the thermal expansion coefficient while maintaining the level of corrosion and casting properties, as well as machinability with dental abrasives and polishability of the alloy.

The specified technical result is achieved in that the nickel-based alloy for metal-ceramic dentures containing carbon, silicon, manganese, chromium, molybdenum, niobium, iron, according to the invention, to further increase hot deformability and the complex of physicomechanical properties, it additionally contains boron and yttrium in the following ratio of components, wt.%:

Carbon Not more than 0.03

Silicon 0.9 - 1.6

Manganese 0.3 - 0.8

Chrome 23.0 - 26.0

Molybdenum 8.5 - 10.5

Niobium 0.8 - 1.7

Iron Not more than 0.5

Boron 0.001 - 0.020

Yttrium 0.001 - 0.020

Nickel and Inevitable Impurities Else

the nickel content is not more than 64 wt.%, and the total content of molybdenum and niobium is due to the following relationship:

[% Mo] + [% Nb] = 9.7-11.7

A carbon content in excess of 0.03% impairs the machinability of cermet dentures with dental abrasives.

A silicon content of less than 0.9% does not provide high-quality casting of thin-walled dentures, and an increase in its content of more than 1.6% can lead to the formation of fusible eutectics and a decrease in the hot deformability of the alloy and yield during metallurgical processing.

Manganese in an amount of less than 0.3% does not provide fluidity of the alloy, and its content of more than 0.8% reduces the mechanical characteristics.

When the chromium content is less than 23%, the strength and corrosion resistance of the alloy are reduced.

With an increase in molybdenum above the upper limit (10.5%), ductility decreases and the melting point increases; when the molybdenum content is below the lower limit (8.5%), increased strength properties are not provided.

A niobium content of less than 0.8% does not have a significant effect on the properties of the alloy, and more than 1.7% is impractical, since the elastic modulus and ductility of the metal are reduced.

The iron in the alloy should be less than 0.5%, since otherwise it increases the shrinkage of the alloy during casting and reduces the quality of the oxide film responsible for the strength of the ceramic-metal compound.

Microalloying with boron and yttrium in amounts of less than 0.001% is ineffective, and more than 0.020% is impractical, but within the specified ranges from 0.001 to 0.020% of each, they provide a cast alloy structure with relatively clean grain boundaries, which further increases the ability of the alloy to hot plastic deformation and thereby thereby increasing yield in metallurgical processing.

The nickel content should not exceed 64% in order to guarantee the prevention of the migration of nickel ions into the environment (oral cavity), which can cause allergic reactions in the human body (as mentioned above).

Alloying with molybdenum and niobium in the amount of less than 9.7% will not provide low TEC values, and their total content over 11.7% will reduce the hot deformability of the alloy.

The invention is illustrated by the following examples.

Alloys were cast in strict vacuum technology in a vacuum induction furnace on a clean charge with ingot casting. After high-temperature heating, the ingot was forged on a hammer into a bar, which was cut into measuring billets of 15–20 g. Samples were cast from these billets by centrifugal casting using the technology adopted in denture laboratories in dental clinics in accordance with ISO 6871-2-94 and GOST R 51767-2001, which were then tested according to the methods recommended in the above standards.

The chemical composition and properties of the proposed alloys are shown in tables 1 and 2, respectively.

From the data given in table 2, it follows that the strength and plastic properties of the proposed alloys are higher than the level of properties of the prototype. The same can be said about the value of the thermal expansion coefficient, since the lower it is, the larger the type of porcelain masses this alloy can have strong adhesion.

In addition, hot plastic deformation showed that the yield for the proposed compositions No. 1-3 is higher than the same indicator for the known alloy (prototype) by 20%.

Conducted corrosion, sanitary-chemical and toxicological tests of the proposed object of the invention, as well as strength tests of ceramic-metal compounds showed that the alloy fully meets all the requirements for nickel-based alloys for dental prosthetics.

Thus, the proposed alloy exceeds the prototype in terms of physical and mechanical properties and manufacturability in the metallurgical process.

Claims (1)

Nickel-based alloy for ceramic-metal dentures containing carbon, silicon, manganese, chromium, molybdenum, niobium and iron, characterized in that, to increase hot deformability and the complex of physicomechanical properties, it additionally contains boron and yttrium in the following ratio of components, wt .%: Carbon Not more than 0.03 Silicon 0.9-1.6 Manganese 0.3-0.8 Chrome 23.0-26.0 Molybdenum 8.5-10.5 Niobium 0.8-1.7 Iron Not more than 0.5 Boron 0.001-0.020 Yttrium 0.001-0.020 Nickel and Inevitable Impurities Else the nickel content is not more than 64 wt.%, and the total content of molybdenum and niobium is due to the following relationship: [% Mo] + [% Nb] = 9.7-11.7.