JPS59217676A - Silicon nitride-base sintering material for cutting tool - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a silicon nitride cemented sintered material having excellent thermal shock resistance and wear resistance, and particularly suitable for use in high-speed cutting of steel and cast iron. This relates to binding materials.

[Prior art and its problems]

In recent years, various research and development efforts have been made to enable high-speed cutting of steel and cast iron. It is a general trend, and at the moment it is 300m, /
One goal is stable cutting at a cutting speed of m.

At this cutting speed, aluminum oxide (hereinafter referred to as Al
It has been established that high-speed cutting can be achieved by making improvements to machine tools, based on the premise that an A-203 sintered material containing 2O3 as a main component is used as a cutting tool. be.

However, when the above-mentioned A7203-based sintered material is used as a cutting tool for rapid continuous cutting of steel, for example, it exhibits excellent wear resistance, but when used for milling of cast iron, for example, , due to insufficient thermal shock resistance and mechanical properties at high temperatures, the cutting edge is prone to chipping due to mechanical and thermal wear-in, and therefore cutting tools made of Al2O3-based sintered materials
At present, it is extremely difficult to stably cut both steel and cast iron at a cutting speed of m,/m.

Therefore, attention has been focused on silicon nitride (hereinafter referred to as Si3N4), which has a small coefficient of thermal expansion, that is, excellent thermal shock resistance, and has excellent hardness and mechanical strength at subtemperatures.
Si3N4 containing this 813N4 as the main JJy component
Attempts have been made to use the base sintered material as a cutting tool for deep-speed cutting of steel and cast iron, but the Si3N4 has high reactivity with iron and therefore suffers from severe wear, making it unsuitable for high-speed cutting.
It had extremely low versatility.

[Purpose of the research and findings based on the research] From the above-mentioned viewpoints, the present inventors have developed an excellent Si3N4-based sintered material with excellent heat shock resistance, sphericity, high-temperature hardness, and high-temperature strength. As a result of research aimed at imparting wear resistance, it was found that molded aluminum (hereinafter referred to as AAN), aluminum oxide (hereinafter referred to as Al2O3), and IJium (hereinafter referred to as Al2O3) were added to Si3N4, which does not have very good sinterability.
A remarkable sintering improvement effect can be obtained by including the three components of Ti carbide, nitride, and carbonitride (hereinafter referred to as TiC and TiN, respectively).
, TiCN) is included as a dispersed phase forming component, the wear resistance is significantly improved without impairing the excellent properties of Si3N4. The resulting Si3N
It has been found that when the 4-unit sintered material is used as a cutting tool for cutting steel and cast iron at high speeds of 300 m/s or more, it exhibits extremely excellent cutting performance in all cases.

[Components of the invention]

Therefore, this invention was made based on the above knowledge, and in weight% (hereinafter, "ch" indicates weight%), Tic, TiN, and TiCN as dispersed phase forming components.
One or more of the following: 6 to 40 chi, AIN, A
It is characterized by a Si3N4-based sintered material for cutting tools, which contains the three components 12O3 and Y2O3 as essential components, with a content of 5 to 10%, Si3N4, and inevitable impurities: leakage.

[h″i, reason for limiting the composition range]

Next, the reason why the component composition of the 5131tJ four-group sintered material of the present invention is limited as described above will be explained.

fal TiC, TiN, and T1CN These products contain 513N4, which is dispersed during accumulative growth and is oxidized at high temperatures.
It has the effect of suppressing the reaction with E and thereby improving the wear resistance of the material, but if the content is less than 6, the desired effect cannot be obtained, whereas if it is contained in excess of 40. , the content of Si3N4 decreases relatively, and Si3N4 content decreases relatively.
Since it would not be possible to sufficiently exhibit the excellent characteristics of N4, the content was determined to be between 6 and 40.

(b) AlN 181 to 03 + ¥203 These 3 IN components form a solid solution together, form a glass phase, and react with 513N4, which does not have very good sinterability, significantly improving the sinterability of the material. This has the effect of densifying the material and improving its strength, but if its content is less than 5%, the desired effect cannot be obtained, while if it is contained in excess of 10%, it will cause problems at the grain boundaries. If the glass phase precipitates too much, the excellent properties of Si3N4, namely thermal shock resistance, high-temperature hardness, and high-temperature strength, will be impaired. Established.

The Si3N4-based sintered material of the present invention can be produced by a normal powder metallurgy method, but since Si3N4 does not have very good sintering properties, sintering by hot pressing or ordinary sintering may be used. Preferably, a dense sintered material is obtained by subsequently applying hot isostatic pressing.

〔Example〕

Next, the Si3N4-based sintered material of the present invention will be explained using examples.

As raw material powder, Si3N4 powder with an average particle size of 2 μm,
1.271 m of Tic powder, 1.2μ+n'l
"iN powder, 1.3 μrn TiCN powder, 1°0 μm A7N powder, 0.5 pm Al2O3 powder, and 0.8 pm Y2O3 powder were prepared, and these raw material powders were summarized in Table 1. After mixing in a wet ball mill and drying, the mixture is sintered or hot pressed under the conditions shown in Table 1 (in the case of normal sintering, the mixed powder is made into a compact). The Si3N4-based sintered material 1 of the present invention is formed by molding, using a graphite mold in the case of hot pressing, and, if necessary, applying hot isostatic pressing (hereinafter referred to as HIP) in the case of normal sintering. ~
12 were produced respectively.

Next, a cutting tip in accordance with the Cemented Carbide Tool Society Standard (CIS) SNG'N432 was made from the Si3N4-based sintered materials 1 to 12 of the present invention obtained as a result and the 4□03-based sintered material from @Sales. Cutting, work material: JIS @SNCM-8, cutting edge: 0.
Chamfer honing of 1m x -25°, cutting speed: 300m/III++1, depth of cut: 2mm, feed: 0.2mm/rev, m local speed continuous cutting test under the following conditions, and work material: FC
-25, Dimensions of cut material: Width 120 + IO++ x Length 320 mm, Cutting speed II: 500 m'/ = 1 depth of cut: 2 mm, Feed per tooth 2 0.2 mm/tooth, Cutter diameter = 160 mm, A υj pig iron speed milling test was conducted under the following conditions: cutting edge: 0.1mm
The cutting time until the flank wear width of the cutting edge reached 0.2+Ml was measured. The results of these measurements are shown in Table 2. Furthermore, Table 2 shows the Vickers hardness and transverse rupture strength at room temperature and 1000°C.

From the results shown in Table 2, the Si3N4-based sintered materials 1 to 12 of the present invention all have high hardness and high strength at room temperature and high temperature, and have excellent wear resistance in high-speed cutting of both steel and pig iron. It is clear that the material has an extremely long service life.

On the other hand, the commercially available A6203-based sintered material has high hardness at room temperature and high temperature, so it exhibits excellent wear resistance equivalent to the Si3N4-based sintered material of the present invention in continuous high-speed cutting of steel. Due to poor impact resistance, high-speed milling of cast iron results in cutting [overall effect].As mentioned above, the 5i3N4-based sintered material of the present invention
It has the excellent thermal shock resistance and mechanical strength at material temperature of i3N4, and has excellent wear resistance, so it has extremely excellent cutting performance, especially when used as a cutting tool for high-speed cutting of steel and cast iron. It demonstrates this.

Applicant: Mitsubishi Metals Corporation Agent Tomi 1) Kazuo and 1 other person

Claims (1)

[Scope of Claims] 26 to 40% by weight of one or more of titanium carbides, nitrides, and carbonitrides as dispersed phase forming components; 3 of aluminum nitride, aluminum oxide, and yttrium oxide; 1. A silicon nitride tight sintered material for a cutting tool, characterized in that it has a composition of 5 to 10% of components, and the remainder consists of silicon nitride and unavoidable impurities.