JPS6227032B2 - - Google Patents

Description

[Detailed description of the invention]

This invention has high hardness and toughness, and has excellent wear resistance and thermal shock resistance, and is therefore suitable for high-speed cutting of materials such as steel and cast iron, which require these characteristics, as well as high-feed cutting and deep-cutting. The present invention relates to a sialon-based sintered material that exhibits excellent performance when used as a cutting tool for heavy cutting such as bearings, wire drawing dies, and other wear-resistant tools. Conventionally, the parent phase is composed of β-sialon having the composition formula: Si ₆ −zAlzOzN ₈ −z (0.1≦z≦5.0), and the dispersed phase is carbides of Ti, Zr, Hf, Ta, Mo, and W. and nitrides, and these two
One or two types of solid solutions (hereinafter collectively referred to as metal carbon/nitride dispersed phase)
It is well known that sialon-based sintered materials composed of more than one species are used as cutting tools. In addition, the above β-sialon is
It can be easily formed by sintering a mixed powder consisting of the main powders of Si ₃ N ₄ powder, Al ₂ O ₃ powder, and AlN powder in an N ₂ atmosphere. However, the above conventional sialon-based sintered materials
Although it has high hardness and excellent wear resistance, it lacks toughness and has poor thermal shock resistance, so it cannot be used for heavy cutting of steel or cast iron, which particularly requires toughness and thermal shock resistance. Currently, the cutting edge is prone to breakage and has a short service life. Therefore, the present inventors conducted research to impart high toughness and excellent thermal shock resistance to the conventional sialon-based sintered material, which has the above-mentioned high hardness and excellent wear resistance. Part of the metal carbon/nitride dispersed phase in the sintered material,
Alternatively, if the entire structure is composed of needle-like crystals (beard crystals), that is, whiskers, and β-sialon is represented by the composition formula: Si ₆ −zAlzOzN ₈ −z, the z value is limited to within the range of 0.2 to 3.0. As a result, they found that the resulting sialon-based sintered material has high toughness and excellent thermal shock resistance while maintaining high hardness and excellent wear resistance. Therefore, this invention was made based on the above knowledge, and contains a metal carbon/nitride dispersed phase: 2 to 30% by volume, and further contains, if necessary, the same dispersed phase forming component. Mg, Y, Al,
One of the oxides of Si, Ti, Zr, and Hf (hereinafter collectively referred to as metal oxide dispersed phase)
A species or two or more species: 1 to 20% by volume, and the remainder is a composition formula as a matrix forming component:
Si ₆ −zAlzOzN ₈ −z (however, 0.2≦z≦3.0) has a composition consisting of β-SiAlON and inevitable impurities, and more than 30% by volume of the carbon/nitride dispersed phase of the above metal is acicular crystals ( It is characterized by a sialon-based sintered material composed of whiskers). The acicular crystals of the metal carbon/nitride dispersed phase in the sialon-based sintered material of the present invention have a short fibrous shape, and are usually distributed in contact with each other at many points. By adjusting the direction of the acicular crystals, it is possible to impart directionality to the strength of the sialon-based sintered material itself. Next, the reason why the component composition of the sialon-based sintered material of the present invention is limited as described above will be explained. (a) Metallic carbon/nitride dispersed phase These components have the effect of improving the hardness of the material and thus the wear resistance, but if their content is less than 2% by volume, the desired durability cannot be achieved. If the content exceeds 30% by volume, the toughness of the material will deteriorate.
Its content was determined to be 2 to 30% by volume. (b) Metal oxide dispersed phase These components are uniformly dispersed in the matrix to improve sinterability, suppress grain growth, and improve the toughness and thermal shock resistance of the material. Since it has the effect of further improving the effect, it is included as necessary, but if the content is less than 1% by volume, the desired effect of improving the above effect cannot be obtained, whereas if it is contained in excess of 20% by volume, the above effect will not be improved. The content was determined to be 1 to 20% by volume because no improvement effect was obtained in the action, but rather a tendency for deterioration appeared. (c) Acicular crystals If the content is less than 30% by volume relative to the carbon/nitride dispersed phase of the metal, the desired high toughness and excellent thermal shock resistance cannot be ensured. Must be at least % capacity. In addition, if the content of the metal carbon/nitride dispersed phase in the material is relatively small, the proportion of needle crystals should be increased; If the amount is large, the proportion should be relatively reduced, thereby maintaining good sinterability and ensuring high toughness. (d) Value of z β-sialon having a composition with a z value of less than 0.2 has poor sinterability and cannot secure the desired high hardness (wear resistance);
In β-SiAlON having a composition with a value exceeding 3, the toughness of _the material _decreases significantly.
It was set as 3. Next, the sialon-based sintered material of the present invention will be specifically explained using examples. Example As a raw material powder, Si ₃ N ₄ powder with an average particle size of 1 μm for forming β-sialon, and 0.6 μm
m of Al ₂ O ₃ powder, and the same 1 μm of AlN powder, further having an average particle size within the range of 0.8 to 1.5 μm.
TiC powder, ZrC powder, HfC powder, NbC powder, TaC
powder, _Mo2C powder, and WC powder, also from 0.8
TiN powder with an average particle size within the range of 1.5μm,
ZrN powder, HfN powder, NbN powder, TaN powder,
(Ti, Hf)C powder, (Zr,Nb,W)C powder,
(Hf, Nb) N powder and (Ti, W) CN powder,
Furthermore, all of them are needle-shaped crystals with a diameter of 1 to 4μ.
m, length: with dimensions within the range of 5 to 100 μm
TiC whiskers, ZrC whiskers, HfC whiskers, NbC whiskers, TaC whiskers, TiN whiskers, ZrN whiskers, HfN whiskers, NbN
Whiskers, TaN whiskers, and even 0.5-1.5μ
MgO powder with average particle size in the range of m, Y ₂ O ₃
Powder, Al ₂ O ₃ powder, SiO ₂ powder, TiO ₂ powder, ZrO ₂ powder, and HfO ₂ powder were prepared, and these raw material powders were blended into the compositions shown in Table 1, and then mixed in a ball mill. After mixing for an hour,
1ton/ ^cm2 pressure

【table】

[Table] By forming compacts by force and then sintering these compacts under _N2 atmosphere at a temperature of 1700°C for 1 hour, the composition can be substantially changed. Sintered materials 1 to 18 of the present invention having the same composition as
Comparative sintered materials 1 to 5, none of which contained needle-like crystals, were manufactured. Next, the resulting sintered materials of the present invention 1-
18 and comparative sintered materials 1 to 5, the Vickers hardness and transverse rupture strength were measured, and SNP432
Cutting chips with the shape of (0.1 mm x 25° chamfer honing), work material: FC-25 (hardness: H _B 200), cutting speed: 200 m/mm, feed: 0.5 mm/rev, A high-feed continuous cutting test was conducted under the following conditions: depth of cut: 2.0 mm, cutting time: 10 mm, and the flank wear width and rake face wear depth of the cutting edge were measured after the test. 8 (Hardness: H _B 320) square material, Cutting speed: 120m/mm, Depth of cut: 3mm, Feed: Variable, Cutting time: 1 minute for each feed, Intermittent cutting test was conducted under the following conditions, and no damage occurred on the cutting edge. The feed was measured at the point in time. These measurement results are also shown in Table 1. From the results shown in Table 1, the sintered material 1 of the present invention
-18 all have high hardness and toughness, as well as excellent wear resistance and thermal shock resistance, so they exhibit excellent cutting performance in high feed, cutting, and interrupted cutting. Needle crystals (whiskers)
Comparative sintered materials 1 to 5 that do not contain any of these materials have particularly low toughness and poor thermal shock resistance, so it is clear that they do not show sufficiently satisfactory results in any cutting. As mentioned above, the sialon-based sintered material of the present invention has high hardness and toughness, and also has excellent wear resistance and thermal shock resistance, so it can be used in steel, cast iron, etc. that require these properties. high-speed cutting,
In particular, it exhibits excellent performance over a long period of time, not only when used as a cutting tool for heavy cutting, but also when used as a wear-resistant tool for bearings, wire drawing diamonds, etc.

Claims (1)

[Claims] 1. Ti, Zr, Hf, Nb as dispersed phase forming components,
One of carbides and nitrides of Ta, Mo, and W, and solid solutions of two or more of these (hereinafter collectively referred to as metal carbon/nitride dispersed phase)
Species or two or more species: 2 to 30% by volume, Compositional formula as matrix forming component: Si ₆ -zAlzOzN ₈
-z (however, 0.2≦z≦3.0) and unavoidable impurities; A high-toughness sialon-based sintered material characterized by being composed of whiskers. 2 Ti, Zr, Hf, Nb as dispersed phase forming components,
One of carbides and nitrides of Ta, Mo, and W, and solid solutions of two or more of these (hereinafter collectively referred to as metal carbon/nitride dispersed phase)
Species or two or more species: 2 to 30% by volume, Mg, Y, Al, also as dispersed phase forming components,
One or more oxides of Si, Ti, Zr, and Hf: 1 to 20% by volume, compositional formula as a matrix forming component: Si ₆ -zAlzOzN ₈
-z (however, 0.2≦z≦3.0) and unavoidable impurities; A high-toughness sialon-based sintered material characterized by being composed of whiskers.