JPH057122B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a high-speed cutting chip that has excellent wear resistance, thermal shock resistance, and mechanical shock resistance, and is suitable for industrial mass production. Conventionally, Al ₂ O ₃ -TiC-based materials with excellent wear resistance have been generally known as tool materials for high-speed cutting, but due to insufficient thermal shock resistance and mechanical shock resistance. However, it was not suitable for use in high-speed intermittent cutting, such as milling, in which thermal and mechanical shocks are constantly applied to the cutting edge. Therefore, as a tool material suitable for high-speed interrupted cutting, it has excellent mechanical strength, hardness, and thermal shock resistance.
Si ₃ N ₄ has received great promise in recent years. However, Si ₃ N ₄ has problems such as poor wear resistance and being a difficult-to-sinter material. In order to solve these problems, various research institutes are conducting research, for example, one of TiC, TiN and TiCN.
5 to 40% by weight of at least one species, 10 to 10% by weight of one or more of AlN and 6 other oxides of rare earth elements, and
A material for cutting tools having a composition consisting of the remainder of Si ₃ N ₄ has been proposed (Japanese Patent Laid-Open No. 56-32377), but it still does not have the expected level of wear resistance and requires a hot pressing method. Therefore, all of them lack practicality as high-speed cutting tool materials for mass production due to high manufacturing costs and other reasons. As a result of various research, the inventors discovered that Si ₃ N ₄ and
By using TiN as the main component and adding the composite oxide described below as a sintering aid,
A sintered body that maintains the excellent properties of Si ₃ N ₄ , has the wear resistance and high toughness of TiN, and is manufactured by a cold press method that can be mass-produced, and furthermore, It has been discovered that a high-speed cutting tool with further improved wear resistance can be obtained by providing a coating layer, which will be described later, on the surface of the sintered body. The present invention was made based on the above findings, and consists of 50 to 85% Si ₃ N ₄ , 10 to 45% TiN and the balance at least Y ₂ O ₃ and Dy ₂ O ₃ as a sintering aid on a weight basis. 1 type, AlN, and Al ₂ O ₃ , the sintering aid has a total ratio of the above at least one type to the latter two in a range of 3/1 to 1/3; A sintered body having an AlN content of 5 to 60% of the total amount of the latter two is used as a base, and a coating layer made of Al ₂ O ₃ is provided on the surface of the base. This article focuses on high-speed cutting chips. In addition, the second invention related to the above specified invention is:
A large amount of coating is formed on the surface of the above-mentioned substrate by an inner layer consisting of at least one layer among AlN layer and AlON layer or at least one layer among TiC layer and TiN layer, and an outer layer consisting of _three Al ₂ O layers thereon. This is a high-speed cutting chip characterized by being provided with a layer. Next, the reason why the types and composition ranges of the components constituting the substrate of the cutting tip of the present invention are limited as described above will be explained. Si ₃ N ₄ and TiN are the main components of the substrate, and Si ₃ N ₄ in particular is essential because it has excellent properties as described above. As a starting material, an α-type material is suitable, and a particle size of 2 μm or less is desirable. TiN forms a dense dispersed phase even at high temperatures, which improves the toughness of the sintered body, and also has the effect of preventing crater wear when used as a cutting tool, as is known. If it is less than 10%, the effect is poor, and if it exceeds 45%, it becomes susceptible to thermal shock and easily deteriorates, so the content should be reduced to 10%.
Limited to ~45%. The sintering aid enhances the sinterability of the above-mentioned main components and makes it possible to manufacture the cutting chip substrate of the present invention by a cold press method that can be industrially mass-produced. If it is less than 5%, the effect is poor, and 40%
If the content exceeds 5%, the base material becomes soft at high temperatures and cannot withstand high-speed cutting, so the content was limited to 5% to 40%. At least one pair of Y ₂ O ₃ and Dy ₂ O ₃
The reason why the ratio of the total amount of AlN and Al ₂ O ₃ is limited to 3/1 to 1/3 is that this range maximizes the sinterability and the mechanical strength of the sintered body. Furthermore, out of the total amount of AlN and Al ₂ O ₃ , AlN is 5 to 60
The reason why it is limited to % is to increase hardness without reducing strength; less than 5% is less effective, and more than 60% reduces strength. Next, a general method for manufacturing the cutting tip of the present invention will be described. The cutting chip substrate of the present invention is produced by cold-pressing a mixed powder of each component constituting the substrate at a pressure of 1 ton/cm ² or more, and molding the molded product at a temperature of 1550 to 1750 in a nitrogen atmosphere.
It is obtained by firing under the conditions of ℃ and holding time of 10 to 120 minutes. In this case, sintering will not occur if the temperature does not reach 1550°C, and if the temperature exceeds 1750°C, the Si ₃ N ₄ component will be active and foaming will occur. After the cutting chip substrate thus obtained is polished into a predetermined shape, a desired coating layer is provided on its surface. Possible methods for forming the coating layer include physical vapor deposition methods such as ion plating method and reactive sputtering method, and chemical vapor deposition method (hereinafter abbreviated as "CVD method").
The CVD method is preferable because it allows a wider selection range of coating layer components and has a faster reaction rate. When following the CVD method, the coating layer of Al ₂ O ₃ is applied by loading the polished cutting chip substrate into a reaction vessel and applying 1000
AlCl ₃ , CO ₂ and
It is provided by injecting H ₂ gas to cause a precipitation reaction as shown in the following reaction formula (1) on the surface of the cutting chip substrate. (1) 2AlCl ₃ +3CO ₂ +3H ₂ →Al ₂ O ₃ +6HCl+3CO Also, the coating layers of AlN, AlON, TiC and TiN are
Inject the mixed gases on the left side of reaction equations (2), (3), (4), and (5) shown below into the reaction vessel and react in the same manner as the precipitation reaction of reaction equation (1). provided by. (2) 2AlCl ₃ +N ₂ +3H ₂ →2AlN+6HCl (3) 2AlCl ₃ +2CO ₂ +3H ₂ +N ₂ →2AlON+6HCl+2CO (4) TiCl ₄ +CH ₄ →TiC+4HCl (5) 2TiCl ₄ +N ₂ +4H ₂ →2TiN+8HCl The coating layer is Al ₂ O Although a single coating layer consisting of only ₃ may be used, first a layer produced by one or more of the precipitation reactions shown in reaction formulas (2) to (5) above is provided, and then a layer formed by one or more of the precipitation reactions shown in reaction formula (1) is provided. By the precipitation reaction shown in
Multiple coating layers can also be provided by providing a layer of Al ₂ O ₃ . If the thickness of the coating layer is less than 0.3 μm, it will have little effect on improving wear resistance, and the effect will increase as the thickness increases, but if it exceeds 5 μm, peeling will easily occur during cutting, making it unusable. However, the coating layer used in the cutting tip of the present invention is extremely resistant to peeling compared to conventional coatings. The reason for this is that the coefficient of thermal expansion of TiN, 8.5×10 ^-6 /℃, is comparable to the coefficient of thermal expansion of Al ₂ O ₃ , which has the largest coefficient of thermal expansion among the coating layers, 7.8×10 ^-6 /℃.
This is thought to be due to the fact that the large difference between the coefficient of thermal expansion of the substrate and that of the coating layer, which conventionally caused peeling, was eliminated, and the adhesion between the substrate and the coating layer became better, as a result of including it in the substrate. . Examples are shown below. Example As starting materials, Si ₂ N ₄ powder with an average particle size of 0.7 μm (α-type Si ₃ N ₄ content 90%), TiN with an average particle size of 2 μm, and TiN with an average particle size of 0.7 μm
m Al ₂ O ₃ , 1.2 μm Y ₂ O ₃ and 1.0 μm Dy ₂ O ₃ ,
Using the same 1.2 μm AlN, these powders were blended with the component composition shown in Table 1, mixed and ground using a wet ball mill, and dried. 5 parts by weight of paraffin as a binder was added to 100 parts by weight of the dried mixed powder, kneaded, and cold-pressed to form granules at a pressure of 1500 kg/cm ² . To remove the binder, the compact was heated in a vacuum at a temperature of 800°C. After firing under the conditions of , holding time for 30 minutes, followed by firing in a nitrogen atmosphere at a temperature of 1650°C for a holding time of 30 minutes.
By sintering for 60 minutes and polishing the sintered body, sintered bodies 1 to 1 for bending test with a size of 4 x 8 x 25 mm were obtained.
0 was manufactured. Incidentally, the compositions of sintered bodies 1 to 5 are included in the composition range of the substrate of the cutting tip of the present invention, and the compositions of sintered bodies 6 to 10 are included in the composition range of the substrate of the cutting tip of the present invention. It is something that cannot be done. Also, for comparison, Al ₂ O ₃ 70%, TiC 25%,
Conventional sintered bodies consisting of 4% Hb ₂ O ₅ and 1% MgO were manufactured by hot pressing method, and sintered bodies 1 to 10
A sintered body 11 was obtained by polishing in the same manner as above. Using the obtained sintered bodies 1 to 11, the relative specific gravity,
Transverse rupture strength and hardness were measured and the results are shown in Table 2. The hardness values in Table 2 are Rockwell hardness values measured using a Superficial testing machine with a load of 45N.

【table】

【table】

[Table] As shown in Table 2, sintered bodies 1 to 5 having compositions falling within the composition range of the substrate of the cutting tip of the present invention have excellent properties equivalent to those of the conventional sintered body 11. It is something. On the other hand, sintered bodies 6 to 10 having compositions outside the composition range of the substrate of the cutting tip of the present invention were significantly inferior in transverse rupture strength, and were also slightly inferior in specific gravity and hardness. . Therefore, as long as the substrate of the cutting tip of the present invention falls within the above-mentioned range, it has the same mechanical strength, sinterability, and hardness as the conventional sintered body produced by the hot press method. It is possible to manufacture those with the cold pressing method. Next, another sintered body obtained in parallel with the same manufacturing process as the sintered body for bending test was polished into SNGN432 shape (chamber 0.1mm x -25°) and RNGN432 shape, and this was used as a cutting chip. Cutting chips 1 to 10, 1 were prepared by using a substrate of
a, 1b, 1c, 1d and 1e were manufactured.
Although the CVD equipment itself is well known, the reaction rate and thickness of the coating layer vary slightly depending on the conditions of use, so it should be noted that the flow rate of the mixed gas to be injected is
The H ₂ and N ₂ gases were set at 4 times and 7 times the theoretical amount, respectively, and the other gases were kept approximately at the theoretical amount, and the pressure inside the reaction vessel was maintained at 500 Torr in the case of TiN precipitation reaction, and in other cases. 30~
It was kept at 50Torr. The thickness of the coating layer varies depending on the inflow time of the mixed gas, but preliminary tests showed that for Al ₂ O ₃ , AlN, and AlON, 0.5 μm is precipitated per unit time, and for TiC and TiN, the thickness of the coating layer is 0.5 μm per unit time. It was confirmed that 1 μm was deposited per unit time, and the inflow time was determined so that the coating layer had a desired thickness.

[Table] No coating layer is provided on the surface of the substrate to achieve this.
These cutting chips were tested and tested under the conditions shown in Table 4.
Measure the flank wear width V _B (mm) after cutting for minutes,
In the test, the number of impacts (hereinafter referred to as "N") until the cutting edge broke was measured, and the results are shown in Table 5. For comparison, cutting chips 1f, 5a and 1 without a coating layer are also shown.
1 was also tested under the conditions shown in Table 4, and the results are shown in Table 5. The reason why two types of tests were conducted was to evaluate wear resistance from _VB , and to evaluate thermal shock resistance and mechanical impact resistance from N.

【table】

[Table] Note *1) Chips 1d, 1f, and 5a suffered severe wear during milling, so cutting was interrupted before the cutting edge broke and the number of impacts was measured. Note *2) For chip 1e, during lathe cutting,
During milling, peeling occurred after 1 minute and 1 pass, respectively. As shown in Table 5, chips 1 to 5, 1a, 1b, and 1c (hereinafter referred to as "products within the range") whose substrate compositions are within the scope of the present invention are chips whose substrate compositions are within the scope of the present invention. It has significantly superior abrasion resistance, thermal shock resistance, and mechanical shock resistance compared to chips 6 to 10, which are not included. This means that when the same coating layer is provided, by using a substrate having a composition falling within the scope of the present invention, the excellent characteristics of each component constituting the substrate will be exhibited. It shows. Products within the range include chips 1d, 1e, 1f, 5
It has significantly superior properties compared to a and 11. This applies even if the composition of the substrate falls within the scope of the present invention or even if the substrate has properties equivalent to those of products within the scope, if no coating layer is provided or if the coating layer is not provided. If the thickness of the cutting tip is inappropriate, a cutting tip with performance comparable to or lower than that of a conventional cutting tip will be obtained. This shows that by providing the coating layer used in the chip with an appropriate thickness, it is possible to further improve the wear resistance, thermal shock resistance, and mechanical shock resistance. As described above, the high-speed cutting chip of the present invention has mechanical strength and hardness equivalent to conventional high-speed cutting chips, and has wear resistance superior to conventional products.
Since it has thermal shock resistance and mechanical shock resistance, it is suitable for use in high-speed continuous cutting, and since it is manufactured by a cold press method, it is also suitable for mass production.

Claims (1)

[Claims] 1. 50 to 85% by weight of Si ₃ N ₄ , 10 to 45% of TiN, and the balance is at least one of Y ₂ O ₃ and Dy ₂ O ₃ as a sintering aid, AlN, and Al ₂ O. ₃ , the sintering aid has a ratio of the total amount of at least one of the above to the latter two from 3/1 to 1/3, and the amount of AlN of the latter two is 3/1 to 1/3. A high-speed cutting chip characterized in that the base is a sintered body having a content of 5 to 60% of the total amount, and a coating layer made of Al ₂ O ₃ is provided on the surface of the base. 2 A composition containing 50 to 85% Si ₃ N ₄ , 10 to 45% TiN, and the balance containing at least one of Y ₂ O ₃ and Dy ₂ O ₃ as a sintering aid, AlN, and Al ₂ O ₃ on a weight basis. In the sintering aid, the ratio of the total amount of the at least one of the above to the latter two is 3/1 to 1/3, and the amount of AlN of the latter two is 5/5 to the total amount of the latter two. ~60% of the sintered body is used as a base, and at least one layer of AlN layer and AlON layer or TiC layer and
A high-speed cutting chip characterized in that a multilayer coating layer is provided, comprising an inner layer made of at least one TiN layer and an outer layer made of _three Al ₂ O layers thereon.