JPH0579449B2 - - Google Patents

Description

[Detailed description of the invention]

【0001】

[Industrial Application Field] The present invention relates to Al ₂ O ₃ −ZrO ₂
The present invention relates to a method for manufacturing a coated ceramic tool with high toughness and high durability using a ceramic sintered body as a base material.

[0002]

[Prior art] Conventional Al ₂ O ₃ system and Al ₂ O ₃ −
TiC ceramic tools have the advantage of high hardness at high temperatures, but on the other hand, they do not necessarily have good strength or toughness, so they are not suitable for rough machining, and they are not suitable for use in modern machine tool NC tools.
Under the current situation, the reliability of the tool as a tool is poor.

[0003] On the other hand, ZrO ₂ ceramic tools, as disclosed in JP-A-55-140762,
ZrO ₂ ceramic as the base material has a transverse rupture strength
ZrO ₂ has excellent properties comparable to cemented carbide, such as 100Kg/mm ² or more and toughness (Kic) 30Kg/mm ^3/2 or more.
Ceramic system contains ZrO ₂ as the main component, CaO,
It is obtained by adding oxides such as MgO and Y ₂ O ₃ to partially stabilize high-temperature stable phases such as tetragonal and cubic crystals even at room temperature.

[0004] Furthermore, according to JP-A- _52-86413 , JP-A-54-60308, and JP-A-54-61215, which disclose Al ₂ O 3 -ZrO ₂ based ceramics, Al ₂ O ₃ matrix By dispersing _ZrO2 in
It is known to exhibit considerably high toughness.

【0005】

[Problems to be Solved by the Invention] However, such conventional ZrO ₂ ceramics and Al ₂ O ₃
- When ZrO ₂ ceramic is used as a cutting tool material, it has superior strength and toughness compared to Al ₂ O ₃ ceramic and Al ₂ O ₃ -TiC ceramic, so it is suitable for rough machining. However, when the material to be cut is, for example, tough and difficult-to-cut ductile cast iron or steel, both flank wear and crater wear become noticeable. For this reason, conventional
Tools made of ZrO ₂ -based ceramics or Al ₂ O ₃ -ZrO ₂ -based ceramics had poor wear resistance and were unable to perform adequately as cutting tools. Furthermore, in order to cut these difficult-to-cut materials at high speed, high impact resistance is essential for their durability.

[0006] The basic purpose of the present invention is to solve the problems of such conventional methods, and it has sufficient high strength and high toughness, and has high durability especially for difficult-to-cut materials. The purpose is to provide ceramic tools.

【0007】

[Means for Accomplishing the Object] To this end, the method for manufacturing a ceramic tool of the present invention provides high strength and adhesion to a base material having sufficient strength and toughness without deteriorating the original properties of the base material. Provide a coating layer with That is, in the first aspect, the present invention uses Al ₂ O ₃ -ZrO ₂ ceramic as a base material and a coating layer formed on the surface of Al 2 O 3 -ZrO 2 ceramic as a base material.
A highly durable ceramic tool with high toughness and high impact resistance is provided by forming at least one ceramic of TiCN, Al ₂ O ₃ and AlON by CVD method.

[0008] In the second aspect of the present invention, the above object is to produce a base made of an Al ₂ O ₃ -ZrO ₂ ceramic sintered body having a composition of 1 to 50 wt% ZrO ₂ and the remainder substantially Al ₂ O ₃ . (a) forming an inner layer made of TiC, TiN, TiCN, or a combination thereof on the surface of the material by CVD; (b) forming an intermediate layer made of AlON on the surface of the inner layer by CVD.
and (c) forming an outer layer made of Al ₂ O ₃ on the surface of the intermediate layer by CVD.
This is achieved by a method for manufacturing a coated ceramic tool with high toughness and high durability, characterized in that it includes the step of forming it by a method.

[0009] In the third aspect of the present invention, the above object is to provide a base made of an Al ₂ O ₃ -ZrO ₂ ceramic sintered body having a composition of 1 to 50 wt% ZrO ₂ and the remainder substantially Al ₂ O ₃ . It is characterized by comprising the following steps: (a) forming an inner layer made of AlON by CVD on the surface of the material; and (b) forming a layer made of Al ₂ O ₃ on the surface of the inner layer by CVD. This is achieved by a method of manufacturing a coated ceramic tool with high toughness and high durability.

[0010] The composition of the Al ₂ O ₃ -ZrO ₂ ceramic sintered body as the base material is ZrO ₂ 1 to 50 wt%, the balance substantially consisting of Al ₂ O ₃ , preferably ZrO ₂ 1 to 30 wt%.
%, the remainder should be substantially Al ₂ O ₃ . This is because by setting ZrO ₂ to 1 wt% or more, the strength, particularly the toughness, of the base material is significantly improved. Also, 50wt% _ZrO2
When the content is below (more preferably below 30 wt%), the coating layer can be formed to a predetermined thickness at high temperatures without deteriorating the properties of the base material (especially necessary in the case of CVD).

[0011] Conventionally, holding a ZrO ₂ sintered body at a high temperature of nearly 1000°C causes a phase transition accompanied by a rapid volume change.

[Equation 1] (monoclinic tetragonal), which was thought to cause rapid strength deterioration of the base material. However, according to the present invention,
By setting the ZrO _{2 content} to 50 wt% or less, it became possible to form a film at high temperatures without causing deterioration of the base material.

【0012】

[Preferred Embodiment] Among these, ZrO ₂ preferably contains a rare earth oxide stabilizer such as CaO, MgO, Y ₂ O ₃ , etc., but does not necessarily need to contain it. When the stabilizer is included, the total amount of CaO or MgO is preferably 15 wt% or less based on ZrO ₂ , and the amount of Y ₂ O ₃ is preferably 9 wt% or less based on ZrO ₂ . In this case, ZrO ₂ has tetragonal ZrO ₂ in its total amount.
It is preferable to have a partially stabilized structure containing 5wt% or more. In addition, when adding ZrO 2 to Al ₂ O ₃ during _{production, partially stabilized ZrO 2 is} added to Al ₂ O ₃
Alternatively, monoclinic ZrO ₂ and a stabilizer may be added alone to Al ₂ O ₃ .

[0013] On the other hand, when no stabilizer is included, it is preferable to use ZrO ₂ with an average particle size of 0.3 μm or less. During the addition of ZrO ₂ to Al ₂ O ₃ , fine ZrO ₂
This is because when ZrO 2 is dispersed in Al ₂ O ₃ , ZrO ₂ remains as a tetragonal crystal, resulting in an Al ₂ O ₃ —ZrO ₂ ceramic base material with good toughness.

[0014] The preferred firing conditions for the Al ₂ O ₃ -ZrO ₂ ceramic base material are an oxidizing atmosphere, a temperature of 1350 to 1650°C, and a treatment time of several minutes to several hours. This is because, if the temperature is lower than 1350°C, the firing will not be carried out sufficiently, and if the temperature exceeds 1650°C, the growth of crystal grains will become significant and both the strength and toughness of the base material will deteriorate. The base material constructed in this way has a transverse strength of about 60 Kg/mm ² or more and a fracture toughness Kic of about 20 Kg/mm ^3/2 or more.

[0015] Next, according to the first viewpoint, ceramics as a coating material include TiC, TiN, TiCN, Al ₂ O ₃
or AlON or a combination of these components (however, AlON is not preferred as an outer layer),
The surface of the base material may be coated in a single layer or in multiple layers. When the above components are combined and multi-layered, the coating layer should have two or more layers, for example, an inner layer, an intermediate layer, and an outer layer as shown in Table 1 (AlON is preferable as the intermediate layer). . According to the second and third viewpoints, the outer layer is
Al ₂ O ₃ is most suitable (because Al ₂ O ₃ has a high microbits height of 2000 Kg/mm ² or more). Al ₂
O The inner layer (inner layer or middle layer) of _{the 3} layers is AlON
is optimal (to increase the adhesion of the hard Al ₂ O ₃ layer and prevent peeling).

[0016] The coating method in this case is generally
PVD method (Physical Vapor Deposition) and CVD
(Chemical Vapor Deposition) and other physical or chemical deposition film formation methods are possible, but in terms of the adhesion homogeneity of the coating material and the coating speed, the present invention uses the reaction-based CVD method as described below. use

[0017] TiCl ₄ +CH ₄ →TiC+4HCl 2TiCl ₄ +N ₂ +4H ₂ →2TiN+3HCl 2TiCl ₄ +2CH ₄ +N ₂ →2TiCN+8HCl 2AlCl ₃ +3CO ₂ +3H ₂ →Al ₂ O ₃ +3CO+6HCl 2AlCl+2CO ₂ +N ₂ +3H ₂ →2AlON＋2CO＋6HCl

[0018] Especially for Al ₂ O ₃ and AlON layers,
Unless the CVD method is used, it is difficult to form a practical film that meets the purpose of the present invention (particularly in terms of film formation speed and film stability). The details of the coating method for TiC, TiN, TiCN, Al ₂ O ₃ and AlON will not be described because they are known per se, but generally a fairly high temperature is essential (800° C. or higher, preferably about 950 to 1100° C.).

[0019] There are many methods of providing various coating layers on cemented carbide by the CVD method, including Japanese Patent Publication No. 42013 (TiC), and TiN and TiCN are based on Japanese Patent Publication No. 51-24982,
Al ₂ O ₃ is JP-A-48-217, TiC, TiN/Al ₂ O ₃ and
The double coating of AlON/Al ₂ O ₃ was
13201 and JP-A-54-29185, and similar coating methods can be used. However, since all of these have cemented carbide as a base material, they are not suitable for high-speed cutting. Furthermore, regarding conventional ceramic base materials containing _ZrO2 , after firing (cooling)
Maintaining the temperature at a high temperature of 1000℃ or higher causes phase transformation in _ZrO2 with a large volume change in this temperature range.

[Equation 2] (Monoclinic Tetragonal) occurs, resulting in a significant deterioration in strength, which was considered contraindicated. However, according to the present invention, it is surprising that, contrary to such expectations, a dramatic and remarkable improvement in properties has been achieved.

[0020] The thickness of the coating layer is 0.3 to 15 μm. This is because if it is less than 0.3 μm, its function as a coating material will be weakened, and if it exceeds 15 μm, grain growth will cause it to be easily peeled off during coating. Al ₂
In the case of coating O ₃ , the thickness of the Al ₂ O ₃ layer is preferably about 0.3 to 5 μm.

[0021] Ceramic tools constructed in this manner not only have high strength and toughness that can withstand repeated high-impact cutting of tough materials, but also exhibit excellent properties in terms of wear resistance. . As a result, highly reliable cutting tools can be produced that can be used in highly automated cutting machines. This will be explained based on the following embodiments.

【0022】

[Example] The raw materials used for the base material were Al ₂ O ₃ with a purity (wt%) of 99.9% and an average particle size of 0.6 μm, and monoclinic ZrO ₂ with a purity of 99% or more and an average particle size.
0.2μm, raw material CaO purity 98% for _CaCO3 ,
The purity of MgO was 97% or higher, and the purity of Y ₂ O ₃ was 99.9% or higher. Each sample of the base material has a composition as shown in Table 2, and after wet-mixing the specified raw materials, drying, adding a binder, and granulating it, pressure is applied.
Press molding was performed at 1.5Kg/cm ² . This powder compact is
After removing the binder by calcination, it was fired in an electric furnace at 1400 to 1650°C for 1 hour. This fired body was polished to a size of 4 x 8 x 25 mm.

[0023] The characteristics of each sample thus prepared are as shown in Table 2. As is clear _from Table 2, each sample has a transverse _rupture strength of 50 kg/
mm ² or less and toughness (Kic) of 10 Kg/mm ^3/2 or less, it shows significantly higher transverse rupture strength and toughness.

[0024] The method for measuring each characteristic of the sample is as follows. (1) Bending strength is measured according to JIS B4104.
The average value of 5 is shown. (2) Fracture toughness was determined based on ASTM Special Technical Publication No. 410 using a specimen with a width of 4 mm, a thickness of 5 mm, and a length of 25 mm.
A notch of 0.5 mm and width of 0.15 mm was made, and the measurement was performed using the three-point bending notch method with a span of 20 mm. The measured value is the average value of each five samples. (3) The crystal system was determined by X-ray diffraction using Geigerflex RAD-γA manufactured by Rigaku Corporation. First, a specimen mirror-polished with 15 μm diamond paste was measured by X-ray diffraction, and the monoclinic ZrO ₂

[Mathematical 3] From the ratio of the integrated intensity Im of the (111) plane and the (111) plane, and the sum It + Ie of the integrated intensity of the (111) plane of tetragonal ZrO ₂ and the (111) plane of cubic ZrO ₂ , the monoclinic The amount of crystalline _ZrO2 was determined.
The sintered body was then crushed to 325 meshes, subjected to X-ray diffraction under the same conditions, and monoclinic ZrO ₂ and cubic ZrO ₂ were again separated.
The integrated intensities I′m and I′e were determined. At this time, the residual tetragonal ZrO ₂ in the sintered body is subjected to mechanical stress due to the crushing, and it is thought that all of it transforms into monoclinic ZrO ₂ , so from I'e/(I'm + I'e) Crystal ZrO ₂
Once the amount of tetragonal ZrO 2 was determined, the amount of tetragonal ZrO ₂ was also determined.

[0025] Next, each of these samples
It was processed into the shape of SNGN432TN (throwaway chip shape representation method according to JIS008B), and a predetermined coating layer was formed on the surface of this molded product (base material) by CVD method. Specifically, _H2 gas was flowed as a carrier gas into the reaction vessel in which the substrate was set, and the above-mentioned chemical reaction was caused to adhere to the surface of the substrate (see Table 3). The internal pressure of the reaction vessel is
In the case of coating TiC, Al ₂ O ₃ and AlON, the coating was 100 mb, in the case of TiCN it was 300 mb, and in the case of TiN it was 500 mb, and the temperature inside the reaction vessel was set at 1050°C. The coating speed is 1μm/1μm for TiC, TiN, and TiCN.
hr, Al ₂ O ₃ and AlON were set at 0.5 μm/hr.

[0026] Using the ceramic tool (sample) obtained in this way, ductile cast iron (FCD55)
(Test 1) and turning (Test 2) of chromium molybdenum alloy steel (SCM44C). The cutting conditions are shown in Table 4.

[0027] The results of this cutting test are as shown in Table 3, and as can be seen from this table, in Test 1, samples Nos. 2 to 8 were able to withstand approximately 4000 to 5000 impacts. On the other hand, reference samples No. 1 and 9 were damaged after 2000 to 2500 impacts. these
Both groups No. 2 to 8, 10 and No. 4a to 4g have extremely long lifespans (10 to 50 times or more) compared to Comparative Examples 1 to 4. It can be seen that the ₂ O ₃ -ZrO ₂ ceramic is particularly effective for milling ductile cast iron at a given film thickness. Test 2 also shows that the Al ₂ O ₃ --ZrO ₂ ceramic formed with a predetermined coating layer has excellent flank wear resistance in turning steel. The effect of the AlON layer is No.
This is clear by comparing 4a, No. 4 and No. 4b, 4d, respectively.

【0028】 ■■■ Turtle shell [0002] ■■■

【0029】 ■■■ Turtle shell [0003] ■■■

【0030】 ■■■ Turtle shell [0004] ■■■

【0031】 ■■■ Turtle shell [0005] ■■■

【0032】

[Effects of the Invention] As explained above, according to the present invention, Al ₂ O ₃ − mainly composed of Al ₂ O ₃ as a base material
In addition to using ZrO ₂ ceramic, a predetermined thin film of TiC, TiN,
By forming a coating layer made of at least one type of ceramic from TiCN, Al ₂ O ₃ , and AlON using the CVD method, it exhibits extremely high strength and toughness (impact resistance) without causing deterioration of the base material. Ceramic tools can be manufactured (first perspective).
As a result, it has the effect of exhibiting excellent wear resistance that cannot be obtained with conventional ceramic tools.
Especially in the second and third viewpoints, high hardness Al ₂ O ₃
(outer layer) through AlON (its inner layer) together.
The fact that the ZrO ₂ base material could be formed using the CVD method without deteriorating its strength was beyond the expectations of those skilled in the art.

[0033] Ceramic tools manufactured according to the present invention can be used not only as tools for cutting and turning, but also as wire drawing dies and other metal processing tools that are required to have wear resistance, toughness, and hardness. Can be applied.

Claims (8)

[Claims] [Claim 1] ZrO ₂ 1 to 50wt%, the remainder substantially
_{TiC , TiN , _}
A method for manufacturing a coated ceramic tool with high toughness and high durability, characterized in that a coating layer made of TiCN, Al ₂ O ₃ , AlON, or a combination thereof is formed by a CVD method. 2. The manufacturing method according to claim 1, wherein the coating layer is formed to have a thickness of 0.3 to 15 μm. [Claim 3] ZrO ₂ 1 to 50wt%, the remainder substantially
(a) Forming an inner layer made of TiC, TiN, TiCN, or a combination thereof on the surface of a base material made of an Al ₂ O ₃ -ZrO ₂ ceramic sintered body having a composition of Al ₂ O ₃ by a CVD method. (b) An intermediate layer made of AlON is placed on the surface of the inner layer.
(c) CVD forming an outer layer made of Al ₂ O ₃ on the surface of the intermediate layer;
A method for manufacturing a coated ceramic tool with high toughness and high durability, the method comprising: forming the tool by a method. 4. The manufacturing method according to claim 3, wherein the coating layer consisting of the inner layer, intermediate layer, and outer layer is formed to have a thickness of 0.3 to 15 μm. 5. The manufacturing method according to claim 3 or 4, wherein the outer layer of Al ₂ O ₃ is formed to have a thickness of 0.3 to 5 μm. [Claim 6] ZrO ₂ 1 to 50 wt%, the remainder substantially
(a) Forming an inner layer made of AlON by CVD method on the surface of a base material made of an Al ₂ O ₃ -ZrO ₂ ceramic sintered body having a composition of Al ₂ O ₃ ; (b) On the surface of the inner layer. , a step of forming a layer consisting of Al ₂ O ₃ by CVD method. 7. The manufacturing method according to claim 6, wherein the inner layer and the covering layer consisting of _three Al ₂ O layers are formed to have a thickness of 0.3 to 15 μm. 8. The manufacturing method according to claim 7, wherein the Al ₂ O ₃ layer is formed to have a thickness of 0.3 to 5 μm.