KR20070084839A - Method for producing a ceramic dental prosthesis - Google Patents

Abstract

A method for producing a ceramic artificial tooth is provided to obtain an optimal pre-sintering temperature in terms of the durability of a tool without generating the problem of surface roughness and contraction ratio at the time of complete sintering. A method for producing a ceramic artificial tooth includes the steps of: obtaining a preliminary sintered body by forming zirconia ceramic having more than 98% of ZrO2 at a pressure of 100-200MPa in a press, and performing preliminary sintering at 540-570deg.C; cutting preliminary sintered bodies by using a ball nose cutter; and cutting the preliminary sintered bodies with a cutting speed of 16,000-18,000rpm, a transfer range of 700-800mm/min and a cutting depth of 0.5-1.0mm. The diameter of the ball nose mill is 0.8-4mm, and the inclination angle of the ball nose mill ranges from minus 2 to minus 4 degrees.

Description

Method for producing a ceramic dental prosthesis

1 is an electron micrograph showing the wear surface of the ball end mill showing the wear inhibiting layer formed on the wear surface of the ball end mill.

Figure 2 is a surface analysis photograph showing the Zr component analysis results of the wear inhibitory layer formed on the wear surface of the ball end mill.

<Description of the code | symbol about the principal part of drawing>

1 wear part of ball end mill 2 wear suppression layer

3: Not worn side of ball end mill

The present invention relates to a method for producing a denture made of ceramic.

Metals and ceramic materials are known as materials used for dentures. In order to produce dentures of high precision and complex form, metals are mainly used. Titanium alloys (TiAℓ6N, TiAℓ6Nb) are known as metals used for denture, and unlike the metals well known in other dental corrections, titanium alloys are resistant to fluctuations in pH values of intraoral fluids occurring in the oral cavity. Have Titanium and its alloys can be processed very easily by well-known metalworking methods, and thus, dentures of complex shapes can be easily manufactured with extremely high precision. However, a drawback of dentures made of titanium and titanium alloys is that their strength is often not satisfied. Another drawback is that metal dentures must be encapsulated in order to conceal the inherent color of the metal from aesthetic reasons and to exhibit the same color as natural teeth.

When ceramic materials are used as dentures, there is a problem that dental patients are difficult to use because the price is significantly higher than metal dentures, although the strength is excellent and the color matching which is indispensable for metal dentures is not necessary.

Ceramic dentures must be precisely shaped and dimensioned to meet their specific purpose. Accurate manufacture of shapes and dimensions is only possible with ceramic dentures if the dentures are processed in a relatively soft, porous state. In this state, a tolerance comparable to the tolerance of metal dentures can be achieved. However, the ceramic denture in the porous state is difficult to use because of its low strength and low wear resistance.

In addition, after the high-density sintering of ceramic materials, the hardness is high, so cutting is impossible except for diamond tools. Diamond tools are not only expensive but also wear severely even for diamond tools. The dimensional accuracy becomes worse.

Therefore, in order to be able to process using a cutting tool which is cheaper than a diamond tool, the cutting process should be carried out while presintered at a temperature lower than the complete sintering temperature, and then complete sintering. However, even after pre-sintering, the pre-sintered body is cut to the required shape and dimensions, so that shrinkage occurs during complete sintering. Furthermore, since the denture has a complex three-dimensional shape rather than a simple shape, the shrinkage rate at each point As it appears differently, the problem arises that the shape and dimensions of the dentures required cannot be matched.

Therefore, in order to minimize the shrinkage rate at the time of complete sintering, it is necessary to increase the presintering temperature as much as possible. However, when the presintering temperature is high, the hardness inevitably becomes high, so that the wear of the tool generally increases. As mentioned earlier, fast tool wear has two important meanings. One is the shorter tool life and the higher the machining cost. The other is that dentures have a three-dimensional complex shape, which requires CNC machining. Even if the cutting process by the program, there is a problem that the shape and dimensions vary according to the wear of the cutting tool.

In addition, since cutting of brittle materials is performed by a cutting mechanism due to brittle fracture, unlike cutting of general metallic materials, tool wear does not necessarily accelerate as the preliminary sintering temperature is high, that is, the hardness is high. Lower sintering temperatures, ie lower hardness, do not necessarily result in longer tool wear. Since the ceramic material is also a brittle material, it may be possible to exhibit such tool wear characteristics.

On the other hand, the surface roughness of the fully sintered ceramic material tends to decrease the surface roughness value after complete sintering as the presintered body having a low presintering temperature is cut. In other words, as the presintered body having a high presintering temperature is cut, the surface roughness value after complete sintering may increase.

Zirconia (zirconium oxide) ceramic has high toughness compared to other ceramic materials, has high stability in the oral cavity of the human body, and can be close to the color of natural teeth (natural teeth). It is used a lot.

Among the manufacturing costs of zirconia ceramic dentures, the cutting tool cost is the highest, and the most suitable presintering temperature considering the tool wear, the surface roughness of the cutting surface and the shrinkage rate has not yet been identified, and thus the presintering is performed at an inappropriate temperature. Manufacturers of dentures had a problem of high manufacturing costs.

In addition, a ball end mill tool is used as a cutting tool for processing zirconia ceramic dentures. The shape and grade of the ball end mill tool have a great influence on the tool wear and the tool life when cutting the ceramic. If the shape and material of the ball end mill do not match the properties of the presintered body, which is the workpiece, there is a problem that the tool life is significantly shortened.

The present invention has been made to solve the above problems, and in the production of zirconia ceramic dentures, there is no problem in terms of surface roughness after complete sintering and shrinkage rate during complete sintering, and is optimal in terms of tool life. The aim is to provide temperature and optimum ball end mill conditions.

In the present invention, a zirconia ceramic having a ZrO ₂ of 98% or more is used as the ceramic.

The present inventors have conducted a number of experiments to derive the optimum manufacturing conditions of ceramic dentures, and as a result, in the manufacture of ceramic dentures, a) ZrO ₂ with zirconia ceramics of 98% or more was formed in a press at a pressure in the range of 100 to 200 MPa. Thereafter, presintering was carried out at a temperature in the range of 540 ° C. to 570 ° C. to obtain a pre-sintered body. B) The ball end mill was made of cemented carbide tool K10, and the first layer of the K10 cemented carbide substrate was TiN coated. Phosphorus second layer is composed of a composite nitride layer of Ti and AℓN. The composite nitride layer has a structure in which the aluminum nitride phase is dispersed and distributed at a ratio in the range of 20 to 30 area% in the structure observation by scanning electron microscopy. The pre-sintered body is cut using a ball end mill with a diameter in the range of 0.8 to 4 mm, an inclination angle in the range of -2 to 4 degrees, and a clearance angle in the range of 9 to 11 degrees; c) Cutting speed 16000 ~ 18000rpm range, the transfer was confirmed for 700 ~ 800㎜ / min range, the depth of cut is in the case of a 0.5 ~ 1.0㎜ range, the wear-suppressing layer to suppress the wear of the tool to the ball end mill wear surface created.

Therefore, in the present invention, a) ZrO ₂ is 98% or more, after zirconia ceramics are molded in a press at a pressure in the range of 100 to 200 MPa, and then presintered at a temperature in the range of 540 ° C to 570 ° C to obtain a pre-sintered body, b) ball The grade of the end mill is cemented carbide tool K10, and the first layer is TiN coated on the base material of K10 cemented carbide, and the second layer, the surface layer, is composed of a composite nitride layer of Ti and AℓN, and the composite nitride layer is a scanning electron. In the observation of the microscope, the aluminum nitride phase had a structure distributed and distributed at a ratio of 20 to 30 area%, and the ball end mill had a diameter of 0.8 to 4 mm, a tilt angle of -2 to -4 degrees, and a clearance angle of 9 The pre-sintered body is cut using a ball end mill in the range of ～ 11 degrees. C) The cutting speed is in the range of 16000 to 18000 rpm, the feed is in the range of 700 to 800 mm / min, and the depth of cut is in the range of 0.5 to 1.0 mm. It is preferable.

In the present invention, the preliminary sintering temperature is in the range of 540 ° C to 570 ° C, when the presintered body subjected to presintering at a temperature of 539 ° C or lower and a temperature of 571 ° C or higher is cut off on the wear surface of the ball end mill 1. This is because the wear-inhibiting layer 2 which suppresses the formation is not produced.

The grade of the ball end mill used for cutting in the present invention is a carbide tool K10, the first layer is a TiN coating on the base material of K10 cemented carbide, the second layer of the surface layer is composed of a composite nitride layer of Ti and Al The composite nitride layer is composed of distributed tissues distributed at a ratio of 20 to 30 area% in the histological observation by scanning electron microscopy. The tilt angle of the ball end mill is -2 to -4 degrees, and the allowable angle is 9 to The use of the ball end mill in the range of 11 degrees is because the wear inhibiting layer which easily suppresses the wear on the wear surface of the ball end mill is easily generated only under such conditions.

In addition, the cutting speed ranged from 16000 to 18000 rpm, feed ranged from 700 to 800 mm / min, and cutting depth ranged from 0.5 to 1.0 mm. This is because the wear inhibiting layer 2 that suppresses is easily produced.

EXAMPLE

Embodiment of Tables 1 to 4. Example 1 a) ZrO after ₂ is subjected to molding in a press to 98% less than zirconia ceramics with a pressure of 150MPa, subjected to preliminary sintering at a temperature of 560 ℃ obtain a presintered body, b) ball-end The grade of wheat is carbide tool K10, the first layer is TiN coating on the base material of K10 cemented carbide alloy, the second layer is the surface layer is composed of a composite nitride layer of Ti and AℓN and the composite nitride layer is a scanning electron microscope The preliminary sintered body was formed by using a ball end mill having a diameter of 25 mm, an inclination angle of -3 degrees, and a clearance angle of 10 degrees. C) The cutting experiment was performed at a cutting speed of 17000 rpm, a feed of 750 mm / min, and a cutting depth of 0.8 mm.

Comparative Examples 2 to 5 of Table 1 are the same as in Example 1 except for changing the preliminary sintering temperature.

Comparative Examples 6 to 7 of Table 2 are the same conditions as in Example 1 except for changing the area ratio of the aluminum nitride phase of the surface layer coating part. Comparative Example 8 has the same conditions as in Example 1 except that the first layer coating is made of TiCN, and Comparative Examples 9 to 10 have the same conditions as in Example 1 except that the tool grades are different. Comparative Example 11 has the same conditions as in Example 1 except that the first layer coating and the surface layer coating are different, and Comparative Examples 12 to 13 are the same as Example 1 except that only the first layer coating is carried out, and Comparative Example 14 Are the same conditions as in Example 1 except that the tool grade was changed and only the first layer coating was carried out, and Comparative Example 15 was the same as in Example 1 except that the coating was not performed at all. The conditions were the same as in Example 1 except that the coating was not performed at all.

Comparative Example 17-21 of Table 3 are the same conditions as Example 1 except having changed the inclination angle or clearance angle of the ball end mill.

Comparative Examples 22 to 26 of Table 4 are the same conditions as in Example 1 except that the cutting speed, feed or cutting depth are different when the pre-sintered body is cut with a ball end mill.

TABLE 1

TABLE 2

TABLE 3

TABLE 4

As shown in Table 1 to Table 4 above, in the case of Example 1 within the range of the manufacturing method in the present patent, wear is suppressed on the wear surface formed on the wear part 1 of the ball end mill as shown in FIG. Although the abrasion suppression layer 2 was produced | generated, in the comparative example 2 thru | or the comparative example 26, the abrasion suppression layer which suppresses abrasion on the abrasion surface of a ball end mill was not produced. Of course, no wear inhibiting layer is formed on the unworn face 3 of the ball end mill. 2 is a Zr component analysis of the wear suppression layer 2 formed on the wear surface of the ball end mill. White dots indicate that there are many Zr components at that point.

Table 5 shows the average tool life time when the wear inhibiting layer 2 was formed on the wear surface of the ball end mill and when it was not produced. When such a wear restraint layer 2 is formed on the wear surface formed on the wear part 1 of the ball end mill, the tool life is three times longer than the case where the wear restraint layer is not produced. Since the initial component of the ball end mill does not have a Zr component, the Zr component of the zirconia ceramic, which is a work material, is attached to the ball end mill, and it is believed that the Zr component reacts with other elements to form a strong anti-wear layer. Of course, the Zr component does not appear on the unworn side 3 of the ball end mill.

TABLE 5

In the production of zirconia ceramic dentures, there is no problem in terms of surface roughness after complete sintering and shrinkage rate during complete sintering when the conditions of the presintering temperature and the ball end mill of the present invention are applied. Lifespan is more than three times better.

Claims (1)

In the manufacture of ceramic dentures, a) ZrO ₂ is 98% or more of zirconia ceramics formed by pressing at a pressure in the range of 100 to 200 MPa, and then presintered at a temperature in the range of 540 ° C. to 570 ° C. to obtain a pre-sintered body. b) The grade of ball-end mill is carbide tool K10, and the first layer is TiN coating on the base material of K10 cemented carbide alloy, the second layer is the surface nitride layer composed of a composite nitride layer of Ti and AℓN. In the structure observation by scanning electron microscopy, the aluminum nitride phase was distributed and distributed in the proportion of 20-30 area%, and the ball end mill had a diameter of 0.8-4 mm, an inclination angle of -2-4 degrees, and a clearance angle. The pre-sintered body is cut using the ball end mill in the range of 9 to 11 degrees. C) Cutting speed is in the range of 16000 to 18000 rpm, feed is in the range of 700 to 800 mm / min, and cutting depth is in the range of 0.5 to 1.0 mm. Above example The process for producing a ceramic dentures, characterized in that for cutting a sintered body.

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