JPS6253474B2 - - 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. β expressed by the composition formula: Si ₆ -zAlzOzN ₈ -z (O<z≦4.3) - Attempts have been made to use sialon-based ceramic sintered materials containing sialon as a main component as cutting tools, but when this sialon-based ceramic sintered material is used for high-speed cutting of steel, cast iron, etc. Fe in work material
Due to the high reactivity with the cutting edge, both flank wear and rake face wear on the cutting edge develop significantly, and the current situation is that the wear resistance (cutting life) is not sufficiently satisfactory. 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
A green compact press-molded from a mixed powder containing 0.5 to 10% by weight is heated to 1800 to
When sintering at a temperature within the range of 2500℃, during sintering,
Most of the oxide powder decomposes, and this decomposition product
O ₂ and carbon C on the surface of the composite carbonitride solid solution powder react, 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.
Since the remaining 0.01 to 1% by weight (hereinafter % indicates weight%) of the oxide suppresses grain growth of the composite carbonitride solid solution, the obtained ceramic is dense and has high strength. Furthermore, as mentioned above, the composite carbonitride solid solution has a cored two-phase structure, resulting in high hardness, high toughness,
In other words, they found that it has excellent abrasion resistance and high transverse rupture strength. This invention was made based on the above findings, and includes: (1) one or two of MgO and CaO:
0.01 to 1%, and the rest is (Ti, W) CN, (M ₁ , 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 is blended into a single-phase composite carbonitride solid solution powder mainly composed of Ti and W consisting of any one of ~. A cutting tool having the composition and structure shown in (1) above is produced by sintering a compact press-molded from a mixed powder made of A method for producing composite carbonitride solid solution ceramics for use in carbonitrides. It has the following characteristics. Next, the reason why the blending amount and content of MgO and CaO and the sintering temperature are limited as described above in the ceramics and the manufacturing method thereof of the present invention 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 of it remains in the ceramics to suppress grain growth of the composite carbonitride solid solution phase, thereby densifying and strengthening the ceramics. However, if the amount is less than 0.5%, not only will the desired sinterability improvement effect not be obtained, but the amount present in the ceramic will be less than 0.01%, and the desired grain growth suppressing effect will not be achieved. On the other hand, 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 deterioration of toughness and fracture resistance. Since it becomes noticeable, its amount should be reduced.
The content was set at 0.5-10%, and the content was set at 0.01-1%. (b) Sintering temperature When the temperature is less than 1800℃, MgO and
CaO is not sufficiently decomposed, and therefore no improvement in sinterability can be expected.
Since most of MgO and CaO remain in the ceramic, cavities are more likely to occur, and as a result, the toughness and fracture resistance of the ceramic decrease.
If the temperature exceeds 2500℃, the composite carbonitride solid solution will grow grains and the toughness and fracture resistance of the ceramic will decrease.
The temperature was set at 2500℃. Note that the composite carbonitride solid solution of the present invention, that is, (M ₁ , Ti, W) CN, (Ti, M ₂ , W) CN,
and (M ₁ , Ti, M ₂ , W) CN, M ₁
(Ti, W)・Part of Ti in CN is 10 to 40
It is desirable to contain it in a substituted form within the range of atomic %, and in this case, if M ₁ is Zr and Hf,
The wear resistance of ceramics has been further improved, and if M ₁ is V, Nb, and Ta, the toughness and fracture resistance are further improved, and
M ₂ is also (Ti, W) a part of W in CN
It may be contained in a substituted form within the range of 10 to 30 atom %, and in this case, the sinterability is further improved. 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 grain size: 0.4μm
MgO powder and 0.5 μm CaO powder were prepared, and 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 ^dried . It is press-formed into a green compact using pressure, and then this green compact is also passed through the first
By sintering under the conditions shown in the table, ceramics 1 to 26 of the present invention and comparative ceramics 1 were prepared.
-5 were produced, respectively. Comparative ceramics 1 to 26 are all under one of the conditions of blending composition (final component composition) and sintering temperature (those marked with * in Table 1).

【table】

【table】

[Table] was manufactured under conditions outside the scope of this invention. Next, regarding the resulting ceramics of the present invention 1 to 26 and comparative ceramics 1 to 5,
In addition to measuring the content of MgO and CaO, we also observed the structure using a metallurgical microscope, and also measured the Bitkers hardness to evaluate wear resistance and the transverse rupture strength to evaluate toughness. We observed the state of bore generation in accordance with the above. These results are also shown in Table 1. From the results shown in Table 1, ceramics 1 to 26 of the present invention all have high hardness and toughness, as well as a dense cored two-phase structure, whereas comparative ceramics 1 to 5 do not. As can be seen, it is clear that if either the compounding composition (component composition) or the sintering temperature is out of the scope of the present invention, the hardness and toughness will be poor, and moreover, the occurrence of bores will increase. It is. Note that comparative ceramics 2 are ceramics 1 to 26 of the present invention.
Similarly, the composite carbonitride solid solution had a cored two-phase structure, but Comparative Ceramics 1,
In all of No. 3, No. 4, and No. 5, the composite carbonitride solid solution had a one-phase structure. In addition, regarding the above-mentioned ceramics 1 to 26 of the present invention and comparative ceramics 1 to 5, chip shape: SNP432 (honing: 0.2 × 25
), Work material: SNCM-8 (hardness: H _B 220) round bar, Cutting speed: 350m/min, Feed: 0.2mm/rev., Depth of cut: 1.5mm, Cutting time: 10min, under the following conditions. Steel continuous high-speed cutting test, and chip shape: SNP432 (honing: 0.1×25
゜), Work material: FC25 (Hardness: H _B 140) square material, Cutting speed: 500m/min, Feed: 0.2mm/tooth, Depth of cut: 2mm, Cutting time: 10min, High speed milling of cast iron under the following conditions. conduct a test,
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 tested for the purpose of evaluating toughness and fracture resistance. The number of chipped cutting edges (number of chipped cutting edges/number of tested cutting edges) was checked. These results are shown in Table 1. Table 1 also shows cutting test results of commercially available Al ₂ O ₃ --TiC ceramics and Si ₃ N ₄ --Al ₂ O ₃ ceramics under the same conditions for comparison purposes. From the results shown in Table 1, ceramics 1 to 26 of the present invention have high hardness and toughness, and are therefore extremely superior to comparative ceramics 1 to 5, 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.
Species: 0.01 to 1% by weight, and the remainder has a composition consisting of a composite carbonitride solid solution mainly composed of Ti and W and unavoidable impurities, and the composite carbonitride solid solution has a cored two-phase structure. Composite carbonitride solid solution ceramics for cutting tools characterized by having a microstructure. 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,
Contains one or more of Hf, V, Nb, and Ta as a substitute in the 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 Pressed from a mixed powder made by blending 0.5 to 10% by weight of one or two of Mg and Ca oxide powders to a single-phase composite carbonitride solid solution powder mainly composed of Ti and W. 1. A method for producing composite carbonitride solid solution ceramics for cutting tools, which comprises sintering a compacted compact at a temperature within the range of 1800 to 2500°C in a non-oxidizing atmosphere. 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.