KR101634132B1

KR101634132B1 - A method for preparing molding material for dental prosthesis

Info

Publication number: KR101634132B1
Application number: KR1020150052656A
Authority: KR
Inventors: 양용석; 양준석
Original assignee: 양용석; 양준석
Priority date: 2015-04-14
Filing date: 2015-04-14
Publication date: 2016-06-29

Abstract

The present invention discloses a manufacturing method of molding materials for dental prothesis and, more specifically, a manufacturing method of molding materials for dental prothesis using powder metallurgy (PM) which allows an alloy powder to have certain physical properties by pressing and sintering the alloy powder to be easily machined. The manufacturing method of molding materials for dental prosthesis comprises the following steps of: forming an alloy including nickel, chromium, molybdenum, silicon manganese, and iron into a fine alloy powder having 200 mesh or less by using an atomizing method; and pressing and sintering the alloy powder to have a certain shape density.

Description

Technical Field [0001] The present invention relates to a method for preparing a dental prosthesis molding material for powder metallurgy (PM)

The present invention relates to a method of manufacturing a dental prosthesis molding material, and more particularly, to a method of manufacturing a dental prosthesis molding material by pressing and sintering an alloy powder so as to facilitate cutting work so as to have predetermined physical properties.

There are many ways to manufacture dental prostheses with metal, among which the use of CAD / CAM technology for ceramic or metal block milling of the frame. In this case, the patient is scanned for the dentition or prism model and the frame is milled based on this scan model. The main disadvantage of this method is that it is difficult to machine the metal block by milling. That is, since the strength of the metal block is too great to mill it, an expensive milling machine is required, and the milling tip mounted on the milling machine is frequently replaced, resulting in a problem in that the manufacturing cost of the prosthesis is increased. This is because it is difficult to obtain proper physical properties for dental prosthesis manufacturing. That is, the conventional dental prosthesis metal material has a disadvantage in that it is difficult to perform polishing because of its high strength and hardness as a metal ingot in the form of a cast. In addition, it is very difficult to capture the casting timing for each metal to meet the specifications for the dental prosthesis.

To solve this conventional problem, several methods of fabricating metal blocks with alloy powder have already been proposed, but none of these methods actually succeeded. In the conventional alloy casting method, there is a problem of peroxidation phenomenon and cracking due to overheating for melting the casting. Beryllium is added to decrease the melting point of the metal as one of the methods to solve this problem. However, It is inappropriate.

Ni (nickel) belongs to a group, such as one of the transition metals, palladium (Pd), platinum (Pt). Nickel is a hard, metallic, lustrous silver white metal with a high ductility and toughness and a weaker magnetic property than iron or cobalt. Chemical reactivity is relatively small, more stable than iron, and forms oxide protective coatings in air. Nickel agglomerates are classified as corrosion resistant metals because they react very slowly with oxygen, water, most dilute acids or alkalis at room temperature.

It is well known that nickel-base alloys are widely used in heat engines (for example, combustion engines, stationary gas turbines, rotating gas turbines). This is because nickel-base alloys are extremely robust in the temperature range of 700 - 900 ° C.

Chromium is a metal with a silver-white luster. The? -Type body-centered cubic structure has a lattice constant of 2.88 占 and a hexagonal structure of? 2.72 占 and c = 4.42 占. The β-form is normal to the anus and transitions to the mold at 800 ° C. Properties are very stable at room temperature, and are not invaded by air and water. When immersed in an oxidizing acid such as nitric acid, chromic acid, phosphoric acid, chloric acid, perchloric acid, or aqua regia, a solid oxide thin film layer is formed on the surface of the metal and becomes passive and does not dissolve. This is why chromium and chromium alloys are corrosion resistant.

Molybdenum is a silver-white metal that is sintered or melted. Mechanically strong from cryogenic temperature to high temperature. It is mainly used for tool steel, high-speed steel, stainless steel special steel, heat resistant steel, high tensile steel, etc., because it is mainly added to steel to increase hardenability and toughness and increase strength.

Alloy powders are widely used in the manufacture of sintered materials by powder metallurgy. The main feature of powder metallurgy is that the appropriate metal powders and alloy powders are compacted and sintered at elevated temperatures.

Korean Patent No. 0543834 discloses an alloy powder composed of iron, nickel, cobalt, copper, tin and a small amount of aluminum, chromium, molybdenum and tungsten, Discloses an alloy powder composed of molybdenum, tungsten, radon, rubidium, rhenium and osmium, but it is used for defense materials and weapons, and Korean Patent Publication No. 2003-0043991 discloses a nickel-chromium- Tungsten alloys are described, but these are technologies used in the manufacture of heat engines.

It is an object of the present invention to provide a molding material having physical properties suitable for manufacturing a dental prosthesis.

The present invention provides a denture prosthesis molding which can easily be cut using milling machines in a dental casting machine by providing an alloy made of a predetermined component without using harmful additives to the human body, And to provide a method for manufacturing a material.

According to an aspect of the present invention, there is provided a method of manufacturing a semiconductor device, comprising: forming an alloy including nickel, chromium, molybdenum, silicon manganese, and iron into a fine alloy powder of 200 mesh or less using an atomizing technique; And compressively sintering the alloy powder at a predetermined molding density.

The metal block using the alloy powder of the present invention is not only easy to cut, but also can be cast easily by a flask.

Therefore, it can be used for a dental prosthesis material having excellent mechanical properties.

1 is a graph showing the yield strength test results of a molding material according to the present invention, and Fig.
2 is a graph showing a melting section of the molding material according to the present invention.

Hereinafter, the present invention will be described in detail with reference to examples.

An alloy melt is prepared by melting in a molten state 67.3% by weight of nickel, 21.7% by weight of chromium, 9.14% by weight of molybdenum, 0.47% by weight of iron and 1.39% by weight of silicon manganese.

The molten alloy is made into a powder having a size of 200 mesh or less by using an atomizing technique. When the particle size of the powder exceeds 200 mesh, the voids are increased during compression molding, and excessive shrinkage and deformation may occur and bubbles may be generated.

The prepared alloy powder is pressed at a load of 350 ton or more to have a molding density of 6 g / cm ³ or more. To achieve a green density of 6 ~ 7g / cm ³ (most preferably from 6.5g / cm ³⁾ is very important bar, the powder is directly bonded in the process of sintering the compressed powder, when molded to achieve the density of the value, or It can be deposited into a single block. When the molding density is less than 6 g / cm ³ , the porosity of the molded article is increased, and conformational changes may occur during sintering. When the molding density exceeds 7 g / cm ³ , the strength and hardness of the sintered and compacted molding material become too high and the workability becomes low.

In the sintering and compression process of the alloy powder, the melting point of nickel is 1,455 ° C.

However, an important factor in sintering is the direct deposition of alloy powder, which requires that the sintering at temperatures of at least 1,000 ° C changes the physical and mechanical properties of the metal. That is, since the physical and mechanical properties of the metal can not be changed at a temperature lower than 1,000 ° C., the molded product sintered and compacted may be broken even by a light impact.

Therefore, according to the present invention, sintering at a temperature of 1,350 ° C or more for 8 hours or more is required to directly bond the alloy powders to each other, thereby changing the physical and mechanical properties of the alloy powders, resulting in a forming density of 6 to 7 g / cm ³ , The strength is 360 to 370 MPa and the metal porcelain bond strength is 30 MPa or more.

As shown in Fig. 2, the solidification point of the molded product using compression sintering is 1,372.9 캜, but the solidifying point of pure nickel is 1,455 캜. Therefore, there is an advantage that the solidifying point can be lowered by 82 캜 and compression-sintered. Compression-sintered molded articles made of nickel alone are generally not suitable for dental molding materials because they have a molding density of 8.9 g / cm < ³ > or more.

An alloy melt is prepared by melting in a molten state 67.3% by weight of nickel, 21.7% by weight of chromium, 9.14% by weight of molybdenum, 0.47% by weight of iron and 1.39% by weight of silicon manganese.
The prepared alloy melt is made into a powder having a size of 200 mesh or less by using an atomizing technique to prepare an alloy powder.
The prepared alloy powder was compression-sintered, and the product was obtained by pressing at a pressure of 350 ton while maintaining the temperature at 1,000 ° C or higher.

The obtained product was tested with five specimens having a diameter of 98 mm, a height of 10 mm and a weight of 514.33 g. The table below is the average for five samples.

Physical Characteristics density 6.7 g / cm3 Melting zone Freezing point 1372 ° C Melting point 1406 ° C Mechanical properties Yield strength 366 ㎫ Elongation 11% Coefficient of thermal expansion 13.7 × 10 ^-6 × K ^-1 Metal-ceramic bonding properties 30 MPa

The physical properties of the molding material according to the present invention as described above were compared with the reference standard (ISO standard) of the medical device.

number Test Items Test basis Judgment One Stability There should be no foreign matter, impurities, etc., and there should be no problem in use. fitness 2 size Base value (diameter 98 mm, height 10 mm) Within ± 5%
. fitness 3 weight Specified value (514.33) g ±
It should be within 5%. fitness 4 density (6.7) g / ㎤ ± 5% of the standard value. fitness 5 Yield strength 270 MPa or more
And shall be within ± 10% of the value given by the manufacturer. 6 Elongation 5% or more, and it should be more than 70% of the value suggested by the manufacturer. 7 Melting zone Liquidus Base value ± 50 ℃ Solidus Base value ± 50 ℃ 8 Elemental content The content of cadmium and beryllium should be less than 0.02 wt.%. 9 Corrosion resistance If the total release of metal ions is less than 200 ㎍ / ㎠
. 10 Coefficient of thermal expansion It shall be within ± 0.5 × 10 ^-6 K ^-1 . 11 Bond strength of metal and porcelain 25 MPa or more. fitness 12 Composition ratio Raw materials Wt.% (Composition) fitness Ni 67.4 ± 2.0 Cr 22 ± 2.0 Mo 9 ± 1.0 Si 1 ± 1.0 Mn 0.1 ± 1.0 Fe 0.5 ± 1.0

* The above-mentioned laboratory was conducted at Kyunghee University dental materials testing and development center.
In the above test, the molding density test is an average value obtained by preparing five samples, immersing each sample in ethanol, ultrasonic washing for 2 minutes, washing with distilled water, and drying thoroughly.
Six test specimens were prepared by using Porcelain furnace, Highbake-II Plus 2500A (Jae Myung Industrial Co., Korea), Digital caliper, CD-15CPX (Mitutoyo Co., Japan) And measured using a universal testing machine, Instron 3367 (Instron Co., USA).
The metal-porcelain bonding test consists of the following steps.
Specimen size: length (25 ± 1) mm × width (3 ± 0.1) mm × thickness (0.5 ± 0.05) mm
Opaque porcelain is raised symmetrically with a length of (8 ± 0.1) mm and a width of 2 mm on one side of the sample.
The porcelain is placed on the specimen so that it has a rectangular shape with a total thickness of (1.1 ± 0.1) mm after firing. The ceramic ceramics process and specimen production were submitted by the company.
The thickness of the metal layer is measured with a digital caliper and the sample is placed on the center of the support of the bending tester so that the ceramic layer comes to the opposite side of the load and is both symmetrical.
The distance between the supporting points of the sample is 20 mm, the diameter of the supporting part is 2.0 mm, and the load part located between the supporting points is 2.0 mm in diameter.
Measure the fracture load (N) by applying a force at the center of the specimen at a load speed (1.5 ± 0.5) mm / min.
A graph for obtaining a coefficient k from a function of the thickness dM of the metal and the Young's modulus EM is obtained.
The metal-ceramic bond strength (τb) of each specimen is calculated in MPa.
τb = k. F _fail
k: thickness of metal layer dM (0.5 + - 0.05) mm and Young's modulus of metal
F _fail : Breaking load applied to specimen (N)

As a result of the test, the average bonding strength was 30 MPa.

Claims

A method of manufacturing a dental prosthesis molding material,
Preparing an alloy powder having a size of 200 mesh or less by atomizing the molten alloy in a molten state with 67.3 wt% of nickel, 21.7 wt% of chromium, 9.14 wt% of molybdenum, 0.47 wt% of iron and 1.39 wt% of silicon manganese ; And
The prepared alloy powder is pressed at a load of 350 ton or more and sintered at a temperature of 1,000 ° C or more for 8 hours or longer to have a predetermined density and a predetermined physical property at a forming density of 6 to 7 g / cm ³ , 370 MPa, and the metal porcelain bonding strength is 30 MPa or more. A method for manufacturing a dental prosthesis molding material by a powder metallurgy method.

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