JPH0129652B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a ceramic tool material that has excellent thermal shock resistance and wear resistance and is suitable for high-speed cutting. Si ₃ N ₄ has extremely high toughness among ceramic materials, and has a low coefficient of thermal expansion of 3.5×10 ^-6 /°C, so it has excellent thermal shock resistance and is highly anticipated as a tool for high-speed cutting. However, there are the following problems in industrially manufacturing Si ₃ N ₄ as ceramic tools. (1) It lacks wear resistance (2) Crater wear is large when cutting steel (3) Since it is a difficult-to-sinter material, hot pressing is required and manufacturing costs are high. Widespread research has been conducted to solve these problems. For example, in JP-A-56-32377, it is 5 to 40%.
More than one type of TiC, TiCN, TiN and less than 10%
Cutting tools made of AlN, Al ₂ O _3, etc. and Si ₃ N ₄ have been proposed, but although crater wear can be suppressed,
It has poor wear resistance and poor sinterability, requiring hot pressing. The present invention was made to solve this problem, and as shown in the drawings, Si ₃ N ₄ , TiN, and Y ₂ O ₃ ,
In the triangular coordinates showing the weight percent of the sintering aid, the ratio of one type or mixture of Dy ₂ O ₃ to the mixture of AlN and Al ₂ O ₃ containing 5 to 60% AlN is from 3/1 to 1/3. ,
Point A (Si ₃ N ₄ 84% by weight, TiN 5% by weight, sintering aid 11%
weight%), point B (Si ₃ N ₄ 55% by weight, TiN 5% by weight,
40% by weight of sintering aid) and point C (55% by weight of Si ₃ N ₄ ,
Nitriding characterized by mixing the above three components in the area surrounded by the line connecting TiN (34% by weight, sintering aid 11% by weight), molding, and sintering at 1550°C to 1750°C in a non-oxidizing atmosphere. The present invention provides a physical ceramic tool. Here, Si ₃ N ₄ is the main component, and the α type is suitable as a starting material, and the particle size is
It is best to have a diameter of 2μ or less. TiN also improves the toughness of Si ₃ N ₄ and has the effect of preventing crater wear when used as a cutting tool, as is well known. If it is less than 5%, there is little effect. As a result of investigating the relationship between expansion coefficient and thermal shock resistance through various cutting experiments, the result was 5×10 ^-6 /
Because it deteriorates when the coefficient of thermal expansion exceeds ℃,
The amount of TiN was determined to be below the relevant amount, that is, 34%.
Next, the sintering aid is intended to improve sintering properties and enable the cold press method that can be industrially mass-produced, and also to improve the wear resistance of Si ₃ N ₄ and TiN, which are inherently prone to wear. This is what I did. If it is less than 11%, the wear resistance is poor and sintering is difficult, so hot pressing is required. If it exceeds 40%, it tends to soften at high temperatures and cannot withstand high-speed cutting.
AlN containing 5-60% of Y ₂ O ₃ and Dy ₂ O ₃ and AlN
The reason why the ratio of the mixture of Al ₂ O ₃ and Al 2 O 3 was limited to 3/1 to 1/3 is because this range is the easiest to sinter, and at the same time the strength of the sintered body is high. AlN and
The reason why AlN is limited to 5 to 60% in the Al ₂ O ₃ mixture is to increase hardness without reducing strength; less than 5% is less effective, and more than 60% reduces strength. It's for a reason. The ceramic for tools of the present invention can be obtained by pulverizing and mixing the above-mentioned raw materials using a ball mill or the like, molding them, and then sintering them. The suitable sintering temperature is 1550℃~1750℃,
It will not sinter below 1550℃, and above 1750℃ it will not sinter.
Vigorous volatilization of the Si ₃ N ₄ component causes foaming. Of course, it can also be manufactured by the hot press method or the HIP method, but it is difficult to mass-produce it industrially. Example 1 Si ₃ N ₄ (average particle size 0.7 μm, α-Si ₃ N ₄ 90%), TiN
(average particle size 2μm), Al ₂ O ₃ (average particle size 0.7μm), Y ₂ O ₃
(average particle size 1.2μm) using AlN (average particle size 1.2μm),
The compositions shown in Table 1 were prepared and mixed and ground using a ball mill. Here, the weight ratio of Al ₂ O ₃ and AlN was 1:1. Paraffin was added to this powder in an amount of 5% by weight, and the powder was press molded at 1.5 ton/cm ² . After removing the binder from this molded body in a vacuum at 800°C, it was heated and fired at 1650°C for 1 hour in an N ₂ atmosphere. The obtained sintered body was polished into a cutting test sample of SNGN432 (chamber diameter: 0.1 mm) and a 4 x 8 x 25 mm sample for bending strength measurement. Evaluation of cutting performance was performed under the conditions shown below, and Table 2
shows the flank wear width V _B (mm) after cutting for 30 minutes in Test 1, and the crater wear depth K _T (mm) after cutting for 5 minutes in Test 2. Cutting test conditions Test 1 Test 2 Work material FC25 SCM440 Cutting speed 400m/min 200m/min Feed 0.2mm/rev 0.3mm/rev Depth of cut 2mm 1mm Cutting time 30 minutes 5 minutes As shown in Table 2, composition without TiN ( No.14)
Then, in 1 to 2 minutes, K _T becomes too large and becomes defective.
In the composition with too much TiN (No. 13), V _B is large,
Chipping occurred in test 2. In the composition with a small amount of sintering aid (No. 6), chipping occurred in Test 2, and in the composition with a large amount of sintering aid (No. 7), V was large. Furthermore, the composition with a large Y ₂ O ₃ / (Al ₂ O ₃ + AlN) mixture ratio (No. 10) has a large V _B , while the composition with a small V B (No. 11)
In test 2, chipping occurred. As described above, it was found that those with compositions within the triangle ABC in the figure have superior cutting performance compared to those with compositions outside ABC.

【table】

【table】

[Table] Example 2 The composition shown in Table 3 was prepared and manufactured using the same manufacturing method as in Example 1. In addition to test 1, test 3 with the following conditions was added to the test method, and the results are shown in Table 3.
It is also shown in . Test 3 Test tip shape RNGN 432 Work material Inconel 718 (heat-resistant Ni alloy) Cutting speed 250 m/min Feed 0.2 mm/rotational depth of cut 0.5 mm Cutting time 2 minutes Evaluation Boundary wear at the cutting edge V _B ′,
Details of V _B ' are shown in Figure 2.

【table】

[Table] As shown above, the addition of AlN improves wear when cutting cast iron, especially when cutting Inconel.
This is noticeable when cutting 718. In the above example, the explanation was given as a cutting tool.
The ceramic tool of the present invention is not limited to this, but can also be applied to heat-resistant and wear-resistant parts for machines that are subject to vibration and heat, such as wire drawing dies, impact dies, etc.

[Brief explanation of drawings]

FIG _{. 1} is _a triangular coordinate diagram showing the composition range of _the ceramic tool _of the present _{invention . 3}
FIG. 3 shows the weight percentage of sintering aids having a mixture ratio of 3/1 to 1/3. FIG. 2 is a perspective view of the cutting edge showing the boundary wear V _B ' at the cutting boundary in cutting test 3, where 1 is V _B and 2 is V _B '.

Claims (1)

[Claims] 1 Si ₃ N ₄ , TiN, and Y ₂ O ₃ as shown in the drawing,
In the triangular coordinates showing the weight percent of the sintering aid, the ratio of one type or mixture of Dy ₂ O ₃ to the mixture of AlN and Al ₂ O ₃ containing 5 to 60% AlN is from 3/1 to 1/3. ,
Point A (Si ₃ N ₄ 84% by weight, TiN 5% by weight, sintering aid 11%
weight%), point B (Si ₃ N ₄ 55% by weight, TiN 5% by weight,
40% by weight of sintering aid) and point C (55% by weight of Si ₃ N ₄ ,
Nitriding characterized by mixing the above three components in the area surrounded by the line connecting TiN (34% by weight, sintering aid 11% by weight), molding, and sintering at 1550°C to 1750°C in a non-oxidizing atmosphere. Manufacturing method for physical ceramic tools.