JPS6256355A - Antiabrasive tough ceramic cutting tool - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to A, 1203-Z rO□ series ceramic tools, and particularly to improvements in wear resistance and toughness.

[Conventional technology]

At20. In order to improve the toughness of ceramics, Z
Adding rO2 is well known, and West German Publication No. 2549652 describes the addition of ZrO2 dispersed in At20.
It has been reported that toughness is improved by microcracks generated by transformation during cooling of O□. However, this method did not lead to an improvement in strength due to latent microcracks and cracks.

After that, in U.S. Patent No. 4,331,048 and Japanese Patent Publication No. 58-15074, ZrO□ in the sintered body was left as a tetragonal (phase), and when this t phase was stressed, monoclinic ( An idea has been proposed to achieve stress relaxation and toughness through stress-induced transformation into the m-phase). In this case, it is known in the literature (Z, Workmtoffteeh
It is difficult to see from Vol. 13 P, 138) that Z in the sintered body
It is said that it is necessary to reduce the particle size of rO2 to 0.52 μm or less.

In order to solve this difficulty, a method of chemically stabilizing using Y has been proposed in US Pat. No. 4,316,964 and the literature (
J, Mat, Sei, Vol. 17, P, 247-263.
), and excellent strength has been reported.

~ [Problem to be solved by the invention] However, as described in the literature, this proposal has the disadvantage that the toughness decreases as the usage temperature increases, and the temperature rises during usage. When used in cutting tools, the characteristics of high toughness cannot be fully utilized. Figure 1 is a diagram taken from the above-mentioned literature.
This is an example showing that strength deteriorates with temperature. The reason for this is that the toughening caused by the addition of ZrO□ is due to the transformation from the t-phase to the m-phase due to stress.As the temperature rises, the t-phase, which is a high-temperature phase, becomes too stable and transforms to the m-phase under stress. This is thought to be because it disappears. To prevent this, it is sufficient to lower the stability of the t-phase.

An object of the present invention is to propose an Ato5-based cutting tool that has particularly excellent toughness under high temperature and high pressure.

[Means for solving problems]

Therefore, the ceramic cutting tool of the present invention contains 18 to 30 moles of Z r O2 and 1.5 to 2.5 moles of D7 oxide relative to the ZrO□, and the remainder is substantially A.
t205, and 80% or more of ZrO2 is present in the t phase.

The most suitable amount of Dy oxide is 2 molar of the amount of ZrO2. Therefore, 1.5 to 2.5 molti around this 2 molti is desirable.

In the present invention, the oxide of Y can be contained in a proportion of 0.05 to 0.5 mole relative to Z r z .

The oxide of Dy has the effect of stabilizing the t-phase like the oxide of Y, but its behavior is slightly different from that of the oxide of Y. In other words, the t-phase generally becomes more stable as the temperature increases, but Dy
The inventors have found that the oxide of Y has less tendency to stabilize the t-phase at high temperatures. Therefore, even at high temperatures, stress causes transformation from t-phase to m-phase, and toughness is maintained.

Dy oxides have a slightly higher t-4m transformation point than Y oxides at room temperature, and the amount of t phase present is slightly lower.
Adding a small amount of Y2O3 improves this point.

Cutting tools are subjected to high temperature and high load stress during machining, but by stabilizing ZrO□ with Dy oxide in this way, toughness is maintained from room temperature to high temperature, so good cutting properties can be expected.

Figure 2 shows the changes in strength and hardness by changing the amount of Z r 02 in the t phase.
% range, both hardness and bending strength are high, and good performance as a cutting tool can be expected.

Figure 3 shows the relationship between the amount of t-phase stabilizer added and the bending strength at 1000°C. The amount of Zr added is
It can be seen that high bending strength is exhibited in the range of 1.5 to 2.5 mol of O□ violet. If it is less than 1.5 mo1%, the stabilization of the t-phase is insufficient, and if it exceeds 2.5 mo1%, the tendency of stabilization of the t-phase is marked at around 1000° C., and toughening cannot be expected. When Y2O3 is added, the phase tends to be more stable and the high-temperature transverse rupture strength value is relatively low.

FIG. 4 shows the change in bending strength with temperature. Z
The transverse rupture strength value of the material in which 2 mo1% of Y2O3 is added to rO2 is high at room temperature, but it decreases significantly when the temperature exceeds 400°C. When 2 mol of Dy20° is added to ZrO□, the bending strength at room temperature is Y2O.

No decrease in strength is observed even at slightly lower or higher temperatures compared to . The reason for the low bending strength at room temperature is the amount of Y2O transformed into the m phase.
This is thought to be because the number is slightly higher than that of .

Z r O5 with 2 mol of Dy2O3 and 0.
When 1 mo1% of Y2O3 is added, high bending strength is exhibited from room temperature to high temperature. This is because the addition of a small amount reduced the amount of transformation to m-phase at low temperatures.

FIG. 5 shows the change in bending strength when Y2O is further added to Dy2O3 in an amount of 2 mo1% based on Z ro 2.

If the amount of Y2O3 added is less than 0.05 mol%, the flexural strength at room temperature will be low (and if it exceeds 9.5 mol, the flexural strength at high temperature will decrease. Therefore, the amount of Y2O should be 0.05-0. 5
A range of mol.

〔Example〕

Table 1 shows the seven ranks of wear amounts of ceramic tools with various compositions. The cutting conditions are shown in Table 2.

Table 1 (mol) O indicates the present invention Table 2 As described above, the present invention, which is excellent in hardness and bending strength at room temperature and high temperature, also showed excellent wear resistance in the cutting test.

〔Effect of the invention〕

As described above, the present invention improves the temperature dependence of strength by selecting the D7 oxide as a stabilizer for the high temperature phase of ZrO2, and produces ceramics and resins with excellent cutting characteristics. The present invention provides cutting tools. Note that the use of Houtgeles or hot isostatic pressing (HIP) as a consolidation method does not reduce the effects of the present invention in any way.

[Brief explanation of the drawing]

Figure 1 shows At205-29.3 mol '16 Zr
A diagram showing the temperature dependence of bending strength in a material in which 2 mo1% of Y2O5 is added to O2. Figure 2 is a diagram showing the relationship between the amount of ZrO2, bending strength, and hardness. Figure 3 is a diagram showing the relationship between bending strength and hardness at high temperatures. A diagram showing the relationship between ZrO□ stabilization and stabilizer colorant amount, FIG. 4 is a diagram showing the change in bending strength with temperature, and FIG. 5 is a diagram showing the relationship between D720. FIG. 3 is a diagram showing changes in bending strength when Y2O3 is added as a stabilizer for Z r O2 in addition to Z r O2. Figure 1 Temperature Figure 2 Amount of ZrO2 (mol'/,) Figure 3 Amount of phase stabilizer (moL' to ZrO2) Figure 4 Temperature Figure 5

Claims (2)

[Claims] (1) Wear resistance and toughness characterized by containing 18 to 30 mol % of ZrO_2 and Dy oxides in a ratio of 1.5 to 2.5 mol % to the ZrO_2, with the remainder consisting essentially of Al_2O_3 Excellent ceramic cutting tools. (2) Ceramic cutting with excellent wear resistance and toughness, characterized in that it contains Y oxide in a proportion of 0.05 to 0.5 mol% relative to ZrO_2 in the first aspect of the claims. tool.