JPS6251228B2 - - Google Patents

Description

[Detailed description of the invention]

This invention provides a composite carbonitride solid solution system that has high hardness and toughness and exhibits excellent cutting performance when used as a cutting tool for high-speed cutting of steel, cast iron, etc., which particularly require these properties. This article relates to ceramics and their manufacturing methods. In general, in the field of cutting tools, there has been a trend in recent years to require cutting at high cutting speeds to improve productivity. Although it has excellent toughness, it does not have sufficient wear resistance, so it does not show a satisfactory cutting life when used under severe conditions such as high-speed cutting. Therefore, attempts have been made to use ceramic sintered materials mainly made of aluminum oxide, which have high hardness, that is, sufficient wear resistance, in the above fields, but these oxide-based ceramics, on the other hand, have poor toughness. Because it is a product, its uses are limited. Furthermore, silicon nitride-based ceramic sintered materials have recently attracted attention as materials for cutting tools. However, this material is difficult to sinter because silicon nitride is a compound with strong covalent bonds, and for this reason hot pressing is often used for its manufacture. However, when hot pressing is used, although a dense sintered material can be obtained, it is impossible to produce a sintered material with a complicated shape, and productivity is low. In addition, β
-Si ₃ N ₄ A compound in which part of the Si in the lattice is replaced with Al and part of the N is replaced with O, i.e. compositional formula: Si _6-z Al _z O _z N _8-z (0<z≦4.3) Attempts have also been made to use a sialon-based ceramic sintered material mainly composed of β-SiAlON represented by , as a cutting tool; Constituent Si and work material
Due to its high reactivity with Fe, flank wear and rake face wear on the cutting edge develop significantly, and the current situation is that it does not exhibit sufficiently satisfactory wear resistance (cutting life). Therefore, from the above-mentioned viewpoint, the present inventors have found that steel and cast iron, which have both high strength and high toughness, can be produced under normal sintering conditions without using the hot pressing method or the like, and which particularly require these characteristics. As a result of research to produce a material that exhibits excellent cutting performance when used as a cutting tool for high-speed cutting such as
W) Powder denoted by CN; Composite carbon of Ti, W, and one or more of Zr, Hf, V, Nb, and Ta substituted in a range of 10 to 40 atom % of Ti. Nitride solid solution {hereinafter referred to as (M ₁ , Ti, W)CN, therefore
M ₁ contains substituted Ti in the range of 10 to 40 atom%
Powder containing one or more of Zr, Hf, V, Nb, and Ta; Ti, W, and one of Cr and Mo containing W by substitution in the range of 10 to 30 atom %; species or two
Composite carbonitride solid solution with species {hereinafter, (Ti, M ₂ ,
W) CN, therefore M ₂ represents one or two of Cr and Mo substituted in the range of 10 to 30 atom % of W} powder, M ₁ , Ti, M ₂ and a composite carbonitride solid solution with W {hereinafter referred to as (M ₁ , Ti, M ₂ , W)CN}
Powder, a single-phase composite carbonitride solid solution powder consisting of any one of the above ~ mainly composed of Ti and W, and Mg and Ca oxide (hereinafter referred to as MgO and CaO) powder. One or two of these:
0.5 to 10% by weight and one or more of Al, Y, and Zr oxide (hereinafter referred to as _Al2O3 , _{Y2O3 ,} and _ZrO2 ) powders: 1 to ₁₀ % by weight When a green compact press-molded from a mixed powder containing Most of it decomposes, and this decomposition produces O ₂
Then, carbon (C) on the surface of the composite carbonitride solid solution powder reacts, and C on the surface of the composite carbonitride solid solution powder decreases, but at the same time, from inside the composite carbonitride solid solution powder, The W and C components, which are the constituent components of this, diffuse preferentially to the surface, and as a result, the interior of the composite carbonitride solid solution powder becomes Ti and N components due to the reduced diffusion of the W and C components. rich, while the surface part has W diffused from the inside.
and C component, W and C relatively compared to the inside.
The composite carbonitride solid solution has a cored two-phase structure rich in components, and sintering is significantly promoted by the surface portion rich in W components of the composite carbonitride solid solution having such a cored two-phase structure. However, as mentioned above, most of it decomposes and reacts during sintering.
The remaining 0.01 to 1% by weight (hereinafter % indicates weight%) of MgO and CaO suppresses the grain growth of the composite carbonitride solid solution, as well as _{Al2O3 , Y2O3 ,} and _ZrO2. The obtained ceramics are dense and have high strength, and as mentioned above, the composite carbonitride solid solution has a cored two-phase structure, so it has high hardness and high toughness. It has excellent wear resistance and high transverse rupture strength, and even better oxidation and wear resistance due to finely and uniformly dispersed Al ₂ O ₃ , Y ₂ O ₃ , and ZrO ₂ We have obtained the knowledge that it becomes possible to have . This invention was made based on the above findings, and includes: (1) one or two of MgO and CaO:
0.01 _{to 1%, one or more of Al2O3, Y2O3 , and ZrO2} : 1 to 10%, and the remainder _is (Ti, W)CN, ( _M1 , Ti, W) CN, (Ti, M ₂ , W) CN, (M ₁ , Ti, M ₂ , W) CN, consisting of any one of the above ~
A composite carbonitride solid solution ceramic for a cutting tool, which has a composition consisting of a composite carbonitride solid solution containing Ti and W as main components and inevitable impurities, and wherein the composite carbonitride solid solution has a cored two-phase structure. and (2) (Ti, W) CN powder, (M ₁ , Ti, W) CN powder, (Ti, M ₂ , W) CN powder, (M ₁ , Ti, M ₂ , W) CN powder, and above. 0.5 to 10% of one or two of MgO powder and CaO powder to a single-phase composite carbonitride solid solution powder mainly composed of Ti and W consisting of any one of ~; _{Al2O3 powder} ,
A green compact is press-molded from a mixed powder containing 1 to 10% of one or more of Y ₂ O ₃ powder and ZrO ₂ powder at 1700 to 2100°C in a non-oxidizing atmosphere. A method for producing composite carbonitride solid solution ceramics for cutting tools having the composition and structure shown in (1) above by sintering at a temperature within the range of . It has the following characteristics. Next, in the ceramics and the manufacturing method thereof of the present invention, MgO and CaO, and Al ₂ O ₃ ,
The reason why the blending amount and content of Y ₂ O ₃ and ZrO ₂ and the sintering temperature were determined as above will be explained. (a) Blending amount and content of MgO and CaO Most of these components decompose during sintering as described above, and the decomposed O ₂ reacts with the composite carbonitride solid solution powder to form a cored two-phase It forms a structural structure and promotes sinterability, and a small amount remains in the ceramics to form a complex carbonitride solid solution phase, as well as from Al ₂ O ₃ , Y ₂ O ₃ , and ZrO _{2 .} It has the effect of suppressing grain growth of the oxide phase, thereby making ceramics denser and stronger, but if the amount is less than 0.5%, not only will the desired sinterability improvement effect not be obtained, but the ceramics The amount remaining in the grain is less than 0.01%, and the desired grain growth suppressing effect cannot be obtained.
If the blending amount exceeds 10%, the residual amount in the ceramic will exceed 1%, and a large number of cavities will occur in the ceramic, resulting in significant deterioration of toughness and fracture resistance. The blending amount was determined to be 0.5-10%, and the content was determined to be 0.01-1%. (b) Blend amount and content of Al ₂ O ₃ , Y ₂ O ₃ , and ZrO ₂ These components have the effect of further improving the oxidation resistance and wear resistance of ceramics by dispersing them finely and uniformly. If the blending amount, i.e., the content, is less than 1%, the desired improvement effect on the above action will not be seen, while if the blending amount, i.e., the content, exceeds 10%, the toughness and fracture resistance of the ceramics will decrease. Therefore, the blending amount, that is, the content, was determined to be 1 to 10%. (c) Sintering temperature If the temperature is less than 1700℃, MgO and
CaO is not sufficiently decomposed, and therefore no improvement in sinterability can be expected.
Most of MgO and CaO remain in the ceramics, reducing the toughness and fracture resistance of the ceramics. On the other hand, when the temperature exceeds 2100°C, Al ₂ O ₃ , Y ₂ O ₃ , and
Since ZrO ₂ also decomposes in the same way as MgO and CaO, not only can further improvements in the oxidation resistance and wear resistance of ceramics be no longer expected, but also the toughness and fracture resistance will decrease. Therefore, the sintering temperature was determined to be 1700-2100℃. Regarding the composite carbonitride solid solution of this invention, that is, (M ₁ Ti, W)CN, (Ti, M ₂ , W)CN, and (M ₁ ,Ti, M ₂ ,W)CN, M ₁ is ( Ti,
W) It is desirable to contain a part of Ti in CN in a substituted form within the range of 10 to 40 atomic %. In this case, if M ₁ is Zr or Hf, the wear resistance of the ceramics will be further improved. , and if M ₁ is V, Nb, and Ta, the toughness and fracture resistance are further improved, and M ₂ is the same (Ti, W).
Part of W in CN is within the range of 10 to 30 atomic%
It is desirable to contain it in the form of substitution with Cr and Mo, which further improves sinterability. Next, the ceramics of the present invention and the method for producing the same will be specifically explained using examples. Examples As raw material powders, various single-phase composite carbonitride solid solution powders each having the compositional formula shown in Table 1 (the numbers in parentheses indicate the atomic ratio) and each having an average particle size of 1 μm were used. , average particle size: 0.5μm
Al ₂ O ₃ powder, 0.6 μm Y ₂ O ₃ powder, 0.5 μm
ZrO ₂ powder, 0.4μm MgO powder, and 0.5μm
m of CaO powder was prepared, these raw material powders were blended into the composition shown in Table 1, wet pulverized and mixed in a ball mill for 72 hours, and after drying, 15 kg/m of CaO powder was prepared.
By press-forming into a compact at a pressure of mm ² and then sintering this compact under the conditions also shown in Table 1, a book having the composition shown in Table 1 is produced. Invention ceramics 1-33 and comparative ceramics 1-6 were produced, respectively. In addition, Comparative Ceramics 1 to 6 all have conditions in which either the compounding composition (final component composition) or the sintering temperature (those marked with * in Table 1) are outside the scope of this invention. It is manufactured by. Next, regarding the resulting ceramics 1 to 33 of the present invention and comparative ceramics 1 to 6,
We measured Bitkers hardness for the purpose of evaluating wear resistance and transverse rupture strength for the purpose of evaluating toughness.
The state of pore generation and metallurgical microstructure were observed in accordance with ASTM standards. These results are shown in Table 2. From the results shown in Table 2, ceramics 1 to 33 of the present invention all have high hardness and toughness, as well as a dense cored two-phase structure, whereas comparative ceramics 1 to 6 have As can be seen, it is clear that if either the blending composition (component composition) or the sintering temperature is outside the range of the present invention, the hardness and toughness will be poor, and moreover, more pores will occur. It is. In addition,
Comparative ceramics 3 are ceramics 1 to 1 of the present invention.
Similar to 33, the composite carbonitride solid solution had a cored two-phase structure, but Comparative Ceramics 1,
In all of Nos. 2, 4, 5, and 6, the composite carbonitride solid solution had a one-phase structure. In addition, regarding the ceramics 1 to 33 of the present invention and comparative ceramics 1 to 6, chip shape: SNP432 (honing: 0.2×25
゜), Work material: SNCM-8 (hardness: H _B 240) round bar, Cutting speed: 400m/min Feed: 0.2mm/rev., Depth of cut: 1.5mm, Cutting time: 10min, under the following conditions. Steel continuous high speed cutting test, and

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[Table] Chip shape: SNP432 (honing: 0.1×25
゜）, Work material: FC25 (hardness: H _B 150) square material, Cutting speed: 500m/min Feed: 0.25mm/rev., Depth of cut: 3mm, Cutting time: 10min, Intermittent high-speed cutting of cast iron under the following conditions. In the former cutting test, the flank wear width of the cutting edge was measured for the purpose of evaluating wear resistance, and in the latter cutting test, 10 cutting edges were measured for the purpose of evaluating toughness and fracture resistance. A test was conducted to check the number of cutting edges that were damaged (number of broken cutting edges/number of tested cutting edges). These results are shown in Table 2. Table 2 also lists commercially available Al ₂ O ₃ -30% TiC ceramics (conventionally referred to as ceramics 1) and Si ₃ N ₄ -10% for comparison purposes.
The cutting test results of Al ₂ O ₃ -5% AlN ceramics (conventionally referred to as Ceramics 2) under the same conditions are also shown. From the results shown in Table 2, ceramics 1 to 33 of the present invention have high hardness and toughness, and are therefore extremely superior to comparative ceramics 1 to 6, which are inferior in hardness and toughness, and commercially available ceramics, which are particularly inferior in toughness. It is clear that the material exhibits excellent wear resistance and chipping resistance. As described above, according to the method of the present invention, composite carbonitride solid solution ceramics having high hardness and high toughness and a dense structure can be produced without using a method such as hot pressing, Moreover, when the resulting composite carbonitride solid solution ceramics are used as a cutting tool for high-speed cutting of steel, cast iron, etc., industrially useful effects such as extremely long-term excellent cutting performance can be obtained. It is.

Claims (1)

[Claims] 1. One or two of oxides of Mg and Ca.
Composite carbon containing: 0.01 to 1% by weight, 1 to 10% by weight of one or more of the oxides of Al, Y, and Zr, and the remainder being mainly composed of Ti and W. A composite carbonitride solid solution ceramic for a cutting tool, characterized in that the composite carbonitride solid solution has a composition consisting of a nitride solid solution and unavoidable impurities, and the composite carbonitride solid solution has a cored two-phase structure. 2. The composite carbonitride solid solution ceramic for a cutting tool according to claim 1, wherein the composite carbonitride solid solution is composed of a composite carbonitride solid solution of Ti and W. 3 The composite carbonitride solid solution contains Ti, W,
Zr containing substitution in the range of 10 to 40 atom% of Ti,
The composite carbonitride solid solution system for a cutting tool according to claim 1, characterized in that it is made of a composite carbonitride solid solution with one or more of Hf, V, Nb, and Ta. Ceramics. 4 The composite carbonitride solid solution contains Ti, W,
The cutting tool according to claim 1, characterized in that it is made of a composite carbonitride solid solution with one or two of Cr and Mo containing 10 to 30 at % of W by substitution. Composite carbonitride solid solution ceramics. 5 The composite carbonitride solid solution contains Ti, W,
Zr containing substitution in the range of 10 to 40 atom% of Ti,
Substituted with one or more of Hf, V, Nb, and Ta in a range of 10 to 30 atom% of W
The composite carbonitride solid solution ceramic for cutting tools according to claim 1, characterized in that it is made of a composite carbonitride solid solution with one or two of Cr and Mo. 6. One or two of Mg and Ca oxide powders: 0.5 to 10% by weight, Al,
One or two of Y and Zr oxide powders
A green compact formed by press molding a mixed powder containing 1 to 10% by weight of seeds or more, in a non-oxidizing atmosphere,
A method for producing composite carbonitride solid solution ceramics for cutting tools, characterized by sintering at a temperature within the range of 1700 to 2100°C. 7 The above composite carbonitride solid solution powder is a single-phase
7. A method for producing a composite carbonitride solid solution ceramic for a cutting tool according to claim 6, characterized in that the composite carbonitride solid solution ceramic is made of a composite carbonitride solid solution powder of Ti and W. 8 The above composite carbonitride solid solution powder is a single-phase
It is composed of a composite carbonitride solid solution powder of Ti, W, and one or more of Zr, Hf, V, Nb, and Ta substituted in the range of 10 to 40 at% of Ti. A method for producing composite carbonitride solid solution ceramics for cutting tools as set forth in claim 6. 9 The composite carbonitride solid solution powder has a single phase.
The scope of the above-mentioned claims is characterized in that it consists of a composite carbonitride solid solution powder of Ti, W, and one or two of Cr and Mo containing 10 to 30 atom % of W by substitution. 7. A method for producing a composite carbonitride solid solution ceramic for cutting tools according to item 6. 10 The above composite carbonitride solid solution powder is a single-phase
Ti, W, and one or more of Zr, Hf, V, Nb, and Ta substituted in a range of 10 to 40 atom% of Ti, and one or more of Zr, Hf, V, Nb, and Ta in a range of 10 to 30 atom% of W. A composite carbonitride solid solution ceramic for a cutting tool according to claim 6, characterized in that the composite carbonitride solid solution powder is composed of a composite carbonitride solid solution powder with one or two of substituted Cr and Mo. Manufacturing method.