JPS5939768A - Abrasion resistant silicon nitride base sintered body - 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 The present invention provides ceramics for machining, especially cutting tools.
■Regarding abrasive silicon nitride-based sintered bodies suitable for wear materials and load-bearing materials.

Silicon nitride has excellent heat resistance, thermal shock resistance, mechanical strength at high temperatures, oxidation resistance, corrosion resistance to chemicals, and corrosion resistance to molten metals, as well as high hardness, so it is used as a high-temperature electrical insulation material and electronic components. It is widely used in materials, physical and chemical products, metal industry refractories, nuclear reactor materials, phase materials for M, J-ID power generation, and high-temperature Ml mortuary parts such as jet engines, rocket nozzles, and turbine blades. .

Since Si3N4 is a substance with strong covalent bonding properties, it is difficult to obtain a high-density sintered gold compared to oxides and substances such as At203 and Z ro 2 which have strong ionic bonding properties. For this reason, the reaction sintering method or the hot pressing method is mainly used as the sintering method for Si3N4. In addition to this, S i
A method of obtaining a high-density pre-sintered body of <3N is generally carried out by adding a sintering aid such as kt203, AIN, MgO, Y2O3, etc. to Si3N4 and sintering at 4113 pressure.

A sintered body in which MgU 2 is added as a sintering aid to 5L3N4 is produced by the reaction of Mg (J) with Si 3N4 during the sintering process, which generates a low melting point liquid phase and promotes sinterability. After that, there is a drawback that Mg0 remaining in the grain boundaries and lower silicates contained deteriorate the high temperature characteristics of the sintered body.In addition, the sintered body in which Y2O3 = 2 is added as a sintering aid to Si3N4, Although it has excellent high-temperature properties as a sintered body, it has a drawback that its strength is low because its sinterability promotion effect during the sintering process is weak and a dense sintered body cannot be obtained.

In the direction of improving all these drawbacks, jet engines,
Sialon-based sintered bodies are silicon nitride-based sintered bodies that have been proposed mainly for high-temperature structural parts such as rocket nozzles and turbine blades. The sialon-based sintered body is a sintered body in which At 203 or ktN gold is added as a solid solution to S i 3N4 as a sintering aid, and a sintered body in which At 203 or ktN gold is added as a sintering aid to S i 3N4.
Alternatively, it is collectively referred to as a Si3N4-based sintered body containing ktN and other additives such as Y2O3 and At solid solution. The sialon-based sintered body of these 7t et al. has Az + Os, which has a strong ionic bonding property, in the 5ixN4 lattice, and ktN is dissolved in solid solution, so the original covalent bonding property of Si3N4 decreases and the characteristics of the sintered body are affected. At the same time, low number oxides in which At elements participate in the sintering process improve sinterability, but on the other hand, after sintering, At
The brittle glass phase involving elements is Sialon (5iAt
ON) has the disadvantage that it remains at the grain boundaries of the particles and drastically reduces the high-temperature properties of the sintered body. During cutting, the tip of a cutting tool's cutting tool undergoes a combination of complex forms such as high-temperature compression, thermal shock, oxidation, corrosion, skid wear, adhesive wear, and scratch wear. When a sialon-based sintered body is used as such a cutting tool material, under dry cutting conditions, the wear resistance at high temperatures is inferior to that of At20s-based ceramics due to the glass phase remaining in the grain boundaries of the sialon-based sintered body. Under wet cutting conditions using water-soluble cutting oil, the AtN component of the elements that make up all of Xialon undergoes hydrolysis and decomposition and evaporation, which is significant] - The disadvantage is that wear resistance is poor because tool damage is induced. There is. As research and development other than the sialon-based sintered body, an attempt has been made in Japanese Patent Application Laid-Open No. 113803/1983 to apply it to Yamasan-April cutting tools.

This Japanese Patent Application Publication No. 49-113803 uses MgO and Y2O3 as sintering aids in S+aN4, and uses MgO and Y2O3 as sintering aids.
This is a sintered body characterized by solid solution in the spinel compound 2SjaW4A. Shi/Shinakara R4gO and Y2O
3 shows a simple binary eutectic phase diagram, MgO・Y2O
Tresvy shows that the spinel type compound of 3 does not exist.
atski i et al. (1zr, Akad, Nauk
88SR.

Neorg; Mater, 7 (11) 2020
(1971)) reported. Suppose that a spinel compound called MgO・Y2O3 with strong ionic bonding is 5
Even if it is dissolved in IsNa, the original covalent bonding property of 8i3N4 deteriorates, and under severe cutting conditions such as when completely cutting cast steel, it is impossible to obtain performance superior to conventional At20s ceramics. . In fact, JP-A-49-1
For 13803, the At-8i alloy, which belongs to light cutting, has a cutting speed of 300 m/min, a depth of cut of 1.5 mm, and a feed rate of 0.
．． When cutting for 2 minutes under cutting conditions of 3mm/rev, side flank wear tends to be extremely large at 0.1〆5~0.2mm, which is a practical problem for ceramics for high-speed cutting tools. .

The present invention solves the above-mentioned drawbacks and problems, and achieves high-speed cutting that is impossible with conventional cutting tool materials, beyond the cutting speed range used with conventional cutting tool materials.
Tool materials that can be used even in the 11J region 1 - magnesium oxide, 0.5 to 10 weight of yttrium oxide, 0.1 to 5 weight of carbides and nitrides of group 4a, 53゜6a transition metals, A mixture of at least one binder phase reinforcing agent selected from mono-metal compounds and composite metal compounds of carbonitrides, carbonates, nitrides, carbonaceous oxides, residual silicon nitride, unavoidable impurities, and grapes; It is a sintered body obtained by sintering.

The present invention uses MgU, which has a weak effect of increasing high-temperature strength but contributes to promoting sinterability, in the binder phase, which is a sintering aid of 5iaN4 and Si3N4, and MgU, which has a weak effect of promoting sinterability but increases one-temperature strength. It was confirmed that a dense sintered body could be obtained by adding Y2O32, and this 8 i 3N4-MgO-
S i without reducing the compactness of Y203-based qX8 glue
A method for improving the wear resistance at high temperatures, which is a drawback of 3N4-MgO-Y203-based sintered bodies.As a result of independent research, we found that a 4a, 5a, 6a group migration gold maple compound containing carbon and/or nitrogen was used. i3N4-Mgo-Y20
The present invention has been made based on the objective of completely improving the wear resistance of 3-series sintered bodies at high temperatures.

That is, the wear-resistant arsenic nitride-based sintered body of the present invention has S i 3
MgO and Y2O32 are added to the binder phase, which is a sintering aid, to make the N42 dense sintered body, and this binder phase is used as a binder phase strengthening agent to improve wear resistance at high temperatures. Tsum: Ij4 A-1pd77N shaku4/shi+
jAn At least one selected from monometallic compounds and composite metal compounds of nitrides, carbonitrides, carbonates, nitrides, carbonitrides, and composite metal compounds are dispersed therein. In this way, when Si3N4, the binder phase, and the binder phase reinforcing agent are completely sintered, the binder phases MgO and Y2O3 promote the sinterability of Si3N4 and make a dense sintered body, and the binder phases MgO and Y2O3 oxidizes a portion of the surface of the binder phase strengthener,
Moreover, since S i 3N4 reacts with a part of the binder phase reinforcing agent, the densification of the sintered body is further promoted. It is also believed that the binder phase reinforcing agent increases wear resistance at high temperatures by being partially oxidized and dispersed in the binder phase MgO and Y2O3. The binder phase strengthening agent used here is carbon and/or nitrogen containing 4a, 5a,
4a, which is a Group 6a transition metal compound, has a nitrogen compound in particular because of its reactivity with Si3N4.

Group 5a and 6a transition metal compounds are preferred.

The wear-resistant silicon nitride-based sintered body of the present invention has as many e groups as possible as a starting material (preferably an average grain size of 5μ or less).
It is desirable to use S i 3N4 powder with a low oxygen content, and the binder phase is M g O and Y2O3, and the binder phase reinforcement is a carbide of group 4a, 5a, 6a transition metal,
At least one selected from nitrides, carbonitrides, carbonates, nitrides, single metal compounds of carbonitrides, and composite metal compounds may be added or mixed individually. In order to completely suppress the coarsening and rod-like formation of 5r3N< particles in the structure of the sintered body, is it made into a composite compound of a binder phase and a binder phase reinforcing agent? A method in which it is added to and mixed with 5iaNi as a starting material is preferable.

In the wear-resistant silicon nitride-based sintered body of the present invention, when kt is contained, a glassy phase remains in the grain boundary phase of Si3N4, and the starting material powder is used to completely reduce the characteristics of the 'jA lees necessary for cutting tools. As an impurity contained in gold, it is necessary to reduce the At content as much as possible, and it is also necessary to avoid contamination of At during the manufacturing process.

For example, it is preferable not to use At-containing materials for containers, balls, etc. used when mixing and pulverizing raw materials. S i 3N4 is α-8i3Na and β-
The uninvented wear-resistant silicon nitride-based sintered body in which 8isN4 has been confirmed may mainly use α-8i3N4 as a starting material, or α-8i3N4 and β-8i3N.
4 may be used as the starting material, or may be used primarily as the starting material β-8i 3N4 and/or β-8
A mixture of isN4 and amorphous silicon nitride may be used as the starting material. Sintering methods include normal sintering (pressureless sintering), sintering under pressure in a vacuum or non-oxidizing atmosphere,
There are methods such as hot pressing, and these sintering methods can be combined with hydrostatic pressing (HIP) to fully promote the densification of the sintered body.

Here I will explain the reason for limiting the numerical values.

MgO, which is a binder phase, has a weak effect of promoting sintering when the O, S content is less than -, and when the amount exceeds 0% by weight, the MgO after sintering becomes
Since the high-temperature strength of the sintered body decreases due to an increase in g-containing lower silicates, it was decided that the MgO content should be 0.5~]O heavy hereditary.

If Y2O3, which is a binder phase, is less than 0.5% by weight, it has little effect on the high-temperature strength of the sintered body, and if it increases by 10% by weight, the binder phase 1, which is a combination of 4gO and Y2Ch, increases. Y2O3 decreases wear resistance at high temperatures.
The content was determined to be 05 to 10 weight percent.

4a, 5a% & a group far transfer which is a binder phase strengthening agent
At least one metal compound selected from mono-metallic compounds and composite metal compounds of carbides, carbonitrides, carbonitrides, carbonates, nitrides, and carbonitrides of the genus 6,0.1% by weight Below the crack, it is dispersed in the binder phase and -CI++l+ at the force temperature.
+t Jl 24; Gender? The flavoring effect is weak, and if the amount exceeds 5ton 1i, the inherent madder temperature properties of 5i3Nv, especially the heat resistance side impact properties, will decrease, so the binder phase strengthening agent should be 0.1 to 5% by weight.
I decided.

Next, referring to Examples, the wear-distributing silicon nitride-based sintered body of the invention will be explained in detail.

Example J Using the compound powder, each sample was blended in the proportions shown in Table 1, and added to each blended sample in W Sun solvent.
The mixture was mixed and ground in a stainless steel container together with VC-based cemented carbide balls. After removing all the solvent from the obtained mixed powder by evaporation, B
Filled in a carbon mold coated with N powder and filled with N2
After replacing the inside of the furnace with gas, molding pressure of 15 () ~ 400%,
Pressure sintering was performed at a temperature of 1700 to 1900°C for a time of 60 to 120 minutes. The manufacturing conditions for each sample are shown in Table 1, and the properties of the obtained sintered bodies are shown in Table 2. The results of Table 2,
It was confirmed that the wear-resistant silicon-based sintered body of the present invention achieved high density and high hardness, and also had excellent heat attack resistance. In the thermal shock test conducted here, the sample was held at each temperature for 20 minutes and then completely immersed in water at approximately 20°C (room temperature) to check whether any cracks had occurred in the sample. It showed the highest temperature V+ that could be tolerated without occurrence of.

Table 2 Example 2 Using powders of MgO and Y2O3 as the binder phase and a binder phase reinforcing agent, a metal compound of a group 4a, 5a, or 6a transition metal and a composite metal compound at a predetermined ratio. Combined with
After heating in vacuum at 1400 to 1600° C. for 1 hour, the mixture was ground and mixed to produce a composite compound powder consisting of a binder phase and a binder phase reinforcing agent. This composite compound powder and S i 3N with an average particle size of 1μ
Each sample was mixed in the proportions shown in Table 3 using four powders, mixed and ground in the same manner as in Example 1, and then sintered. The manufacturing conditions for each sample are shown in Table 3, and the properties of the obtained sintered bodies are shown in Table 4. The properties of the sintered body were determined in the same manner as in Example 1.

Example 3 Sample number 2.5.8.9 shown in the first garment in Example 1
Among the sintered bodies and sample number 2 shown in Table 3, sample number 1 was used.
2.15 sintered body sounds each Cl5Jle semi-SNP 43
The wear-resistant silicon nitride-based sintered body of the present invention molded into two shapes and commercially available Azz03 ceramics and Sialon ceramics were molded into the same shape and used for comparison, and also under the following conditions (g) and (13). A cutting test was conducted.

(5) Turning test conditions Work material Fe12 Chip shape 5NP432 Honing 0.1×-3
0' Cutting speed 600 rn/min Depth of cut 1.5 mm Feed rate 0.7 m/rev Cutting time 3Qmin (19 Norais cutting test nested workpiece material J='CD55 Chip enlargement 5NP432 Honing 0IX-3
0' cutting speed 140 m/min depth of cut
1.5 mm feed speed 0.18 gates, / t 00 t h (5)
Table 5 shows the cutting test results under conditions (13) and (13). As shown in Table 5, the wear-resistant silicon nitride-based sintered body of the present invention is significantly superior to conventional Az*03 ceramics and sialon ceramics in both wear resistance and surface chipping resistance. This was confirmed.

In addition, the wear-resistant silicon nitride-based sintered body of the present invention can be used satisfactorily even under severe cutting conditions such as high speed and high feed, which was generally considered impossible with conventional cutting tool materials, and it can be used in a new 9-cut machining area. It is hoped that this will pave the way for

From Example 1.2.3 in Table 5 onwards, the present invention I', 'I:
The abrasive silicon nitride base 1 Akatsuki body can be used for cutting tools, Attachment 1 for dust L, corrosion resistant material applied to Si3N + inherent corrosion resistance 4, and conventional ceramics for structural use. It can be judged that the industrial value of the IIF Noh notes, which have been used for a long time, is extremely high.

Claims (1)

[Claims] 0.5 to 10% by weight of magnesium oxide, 0.5 to 10% of yttrium oxide, and 0.1 to 5% by weight of 4;]
, carbides, nitrides, carbonitrides of group 5a and 6a transition metals,
The composition must include at least one binder phase strengthener selected from mono-metal compounds and composite metal compounds of carbonates, nitrides, and carbonitrides, remaining silicon nitride, unavoidable impurities, and gold. A wear-resistant silicon-based sintered body characterized by: