JPS58181845A - Tough cermet - Google Patents

Abstract

PURPOSE:To provide cermet for a cutting tool improved in toughness, heat resistance and wear resisting property, obtained by compounding Al4C3 in TiC type cermet containing nitride of a Group IVa, Va metal, a Group VIa metal (carbide) and a ferrous metal. CONSTITUTION:Tough cermet consisting of 5-30wt% one kind or more Group IVa, Va metal nitride such as TiN, ZrN, HfN, VN, NbN or TaN, 3-40wt% one kind or more Group VIa metal(carbide) such as Cr, Mo, W, Mo2C or WC, 2.85-30wt% one kind or more ferrous metal such as Ni or Co and the remainder TiC and inevitable impurities. Because the cermet with this composition is improved in compatibility of a hard phase containing nitride and a combined phase metal and lowered in a sintering temp., a cermet sintered body with a minute structure is obtained. In addition, because wear resisting property and plastic deformation resistance are enhanced, sufficient capacities are exhibited in high speed cutting.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cermet for cutting tools that has excellent toughness and heat and wear resistance.

Cermet is a composite material consisting of ceramic and metal, and is said to have both the heat resistance and hardness of ceramic and the strength and toughness of metal, and is widely used in various cutting tools, friction materials, self-lubricating materials, IS materials, etc. This is what is being done.

In particular, as cutting tools, tools mainly made of a combination of titanium carbide and metal nickel, or a combination of titanium carbide or titanium nitride and metal nickel have been used. In particular, when a combination of titanium carbide and titanium nitride is used as the ceramic component, high-temperature hardness and thermal conductivity are improved compared to titanium carbide alone.

However, when titanium carbide and titanium nitride are combined as the ceramic components, the titanium nitride tends to wet with the metal components, so that the toughness or wear resistance cannot be improved to a satisfactory extent. As a solution to this problem,
A cermet formed by combining zirconium carbide, tartar carbide, niobium carbide, tungsten, molybdenum, aluminum nitride, etc. with titanium carbide and titanium nitride as a ceramic component, and using an iron group metal as a metal component (Patent Application Publication No. 30209, 1972) No. 2 was developed and is known to have excellent cutting characteristics, mechanical properties, etc.

However, although the cutting properties and mechanical properties were improved by adding aluminum nitride, etc. to the cermet as described above, during vacuum sintering in the manufacturing process of the alloy, titanium nitride decomposes nitrogen and generates bore holes. There was a problem in which alloy defects such as Sakae and Sakae occurred, resulting in a decrease in strength. Furthermore, this phenomenon was accelerated by the need to increase the sintering temperature due to the addition of titanium nitride. Furthermore, titanium nitride itself has poor wettability with iron group metals, so it has many bores, which causes a decrease in strength, and even if it is strengthened with aluminum nitride, sufficient strength cannot be obtained.
In particular, it is hardly used for heavy cutting, milling cutting with large impact, or interrupted cutting, and even when used for high-speed cutting, it has poor wear resistance and plastic deformation resistance.

In order to solve the above-mentioned problems, the present inventors conducted extensive research and discovered that the conventional drawbacks could be overcome by adding aluminum carbide to a titanium carbide cermet containing nitrides such as titanium nitride. , completed the invention.

That is, the gist of the present invention is that the following component (a)
■One or more selected from a and Va group metal nitrides of the Periodic Table of the Elements: 5 to 30% (b) One or more selected from Via group metals and their metal carbides =3g4011a1% (C) One or more selected from iron group metals: 2.85 to 30% by weight (d) Aluminum 1512: 0.15 to 8% by weight (
e) Titanium carbide and unavoidable impurities: The tough cermet is characterized by consisting of the remainder.

Here, the IVa group of the periodic table of elements is a group consisting of T1, Zr, and Hf, and the Va group is a group consisting of V,
The group consisting of Nb and Ta, the group ①a means the group consisting of Cr, MO and W, and the iron group metal means the group consisting of Fe, Co and Ni.

Among the components used in the present invention, nitrides of IV group a metals are represented by the chemical formulas TiN, ZrN, and HfN, and nitrides of group Va metals are represented by chemical formulas VN, N
b N, Ta N, ■ AA group metals include chromium, molybdenum, tungsten, Vla group a metal carbides include chemical formulas Cr5C2, Cr7Ca, MQz
The cermets of the present invention include those represented by C, MOC, W2C, and WCr, iron group metals such as iron, cobalt, and nickel, aluminum carbide represented by the chemical formula A and aCS, and titanium carbide represented by the chemical formula TiC. Applicable as a composition component.

Among the above components, IVa and Va group metal nitrides have the effect of inhibiting the grain growth of the alloy as well as improving the crater wear resistance, and their content is preferably 5 to 30%, and if it is less than 5%, the above The effect is weakened, and if it exceeds 30%, the wear resistance decreases.

In addition, ■ AA group metals and their carbides have the effect of improving the wettability between the hard phase of the ceramic and the binder phase of the metal, and their content is preferably 3 to 40%, and if it is less than 3%, the above effects will be weakened. If it exceeds 40%, the double carbonitride phase formed around titanium carbide becomes brittle, reducing the strength and oxidation resistance of the alloy. Furthermore, the amount of titanium carbide is relatively reduced, resulting in a decrease in wear resistance.

In addition, iron group metals act as a binder phase, and their content -
is preferably 2.85% to 30%; if it is less than 2.85%, the strength of the alloy will decrease, and if it exceeds 30%, the hardness of the alloy will decrease and its wear resistance will deteriorate.

In addition, aluminum carbide significantly improves the wettability between the hard phase and the binder phase, and also has the effect of lowering the sintering temperature, so its content is preferably 0.15 to 8%, and less than 0.15%. The above effects are not sufficient, and if it exceeds 8%, the strength and cutting characteristics will deteriorate.

Furthermore, in addition to the above-mentioned components, titanium carbide as a hard phase and unavoidable impurities account for the remainder, and the cermet of the present invention is mainly composed of these components. When substituted with , it is possible to improve not only the wettability between the hard phase and the binder phase but also the heat resistance. The content is preferably 40% or less of the original titanium carbide, and if the substitution exceeds 40%, the above effects will be weakened and the amount of titanium carbide will also be relatively reduced, which is a characteristic of titanium carbide. Wear resistance decreases.

Next, each component used in cermet production is in powder form for ease of mixing and molding, and generally has a particle size of 10 μm or less. Moreover, each component may not be used alone, but in the form of a solid solution of carbide and carbide, carbide and nitride, or nitride and nitride.

The method for manufacturing a molded cermet using the above-mentioned raw materials is one that is normally adopted for manufacturing cermets. After drying, the wet mixture is pressurized and shaped using a cold mold, and then sintered, which is the cold forming sintering method. A slurry is created with a solvent and cast into a porous mold such as a plaster mold. In the casting sintering method, ceramic powder is mixed with a binder and lubricant in advance, molded and primary sintered to form a porous sintered body of 1M3!it, which is then sintered. Infiltration method in which metal and ceramic powders are mixed with a plastic binder and injection molded, the binder is blown off and sintered after injection molding, hot press method in which pressure is applied during sintering, and HI
Methods such as the P method and the CAP method can be adopted. These sinterings are generally carried out in an inert or reducing gas at 1250 to 1 L.
, 00°C for 0.1 to 3 hours.

As detailed above, the cermet of the present invention manufactured by sintering using each of the above components is obtained by blending aluminum carbide into a titanium carbide-based cermet containing nitrides of Group A or Va metals, including titanium nitride. , the wettability between the hard phase containing nitride and the binder phase metal is significantly improved, and the sintering temperature is also significantly lower than that of conventional cermets containing titanium nitride in an amount of several percent to several tens of percent. Therefore, a cermet sintered body with a small bore and a fine structure can be obtained. Furthermore, the cermet of the present invention has excellent mechanical properties and cutting properties, making it suitable for heavy cutting, high-impact milling, interrupted cutting, and cutting in which the size and direction change. It exhibits excellent characteristics in profile cutting, and has sufficient performance in high-speed cutting due to significantly improved wear resistance and plastic deformation resistance.

Next, the present invention will be specifically explained using examples.

Example 1 Using the raw material powders shown in Table 1 that are commercially available as raw materials for sintered alloys for cutting tools, these raw material powders were blended with each sample number and component composition shown in Table 2, and this mixture was prepared. were wet mixed using a stainless steel ball mill and carbide balls. Next, after drying this mixture, it was molded at a press pressure of 2t/-,
The transverse rupture strength (TR8) and hardness of the cutting tool chips obtained by sintering for 1 hour at an air temperature of 1i1300 to 1350°C were measured. Thereafter, it was polished to the dimensions of 5NP432 and a cutting test was conducted under the cutting conditions shown in Table 3.

The obtained results are listed in Table 2 together with the composition of each example. Incidentally, a cermet of a comparative example was also prepared by the same method and measured in the same manner, and is also listed in Table 2. However, sample No. 1- of comparative example
As for Sample No. 10, it was impossible to sinter at a sintering temperature of 1350°C or lower, so sintering was performed separately at 1420°C.

From the above results, ■WC and MO as group a metal carbides.
Sample 1-8 of the comparative example, in which the total amount of 2C exceeds 45% and component (b) exceeds 40%, has almost the same hardness as that of the present invention, but has a lower transverse rupture strength. (T.R.
8> was low, the amount of wear in the cutting test was large, and the number of cuttings until the chip broke was small, resulting in unsatisfactory performance.

Also, conversely, if MO2C is 1% and (b
) Comparative sample 1-9 with a component of less than 3% had low TR3 and hardness, had a large amount of wear in the cutting test, and had an extremely small number of cuttings until chipping. Also, <d)
Comparative sample 1-10, which did not contain any aluminum carbide as a component, had similarly unsatisfactory performance, and in particular, the number of cuttings until chip breakage was small. In addition, Comparative Example Sample 1-11, in which the (a) component is less than 5%, and Comparative Example Sample 1-12, in which the (C) component is less than 2.85%, have no problems with hardness and wear (■), but have chip defects. The number of cuts until then was small. In addition, sample 1 of a comparative example in which the component (C) exceeds 30%
-13, <d) Comparative example sample 1-1 with component exceeding 8%
Comparative sample 1-15, in which the amount of gastric excretion of components 4 and (e) exceeds 40%, was unsatisfactory in terms of hardness, wear amount, and number of cuts until chip breakage, and in particular, the results of the cutting test for sample 1-13 were unsatisfactory. The performance was extremely low.

Example 2 Similarly, the raw material powders shown in Table 1 were used and blended into the component compositions of each example shown in Table 4. Thereafter, chips for cutting tools were obtained in the same manner as in Examples 1 to 7. Transverse rupture strength＜TR8
) and hardness were measured, and a cutting test was conducted under the cutting conditions shown in Table 5. The obtained results are listed in Table 4 together with the composition of each example. Incidentally, a cermet of a comparative example was also prepared by the same method and measured in the same manner, and is also listed in Table 4. However, in Comparative Example 6, it was impossible to sinter at a sintering temperature of 1350°C or lower, so a separate 1-hour open sintering process was performed at 1450°C.

From the above results, Comparative Example Sample 2-6, which contains a large amount of TiN and NbN as IV a or Va group metal nitrides, with a total of 41%, is excellent in R8, but has low hardness and wear in the cutting test. - and the amount of plastic deformation was large, resulting in unsatisfactory performance. On the other hand, sample 2-7 of the comparative example, which does not contain group (a) and Va group metal nitrides, has a low hardness and is considerably low in TR3, and the wear layer and plastic deformation amount in the cutting test are extremely large, which is unsatisfactory. It was performance. Furthermore, Comparative Sample 2-8, which did not contain any aluminum carbide, had even worse performance in hardness and cutting tests than Sample 2-7.

In addition, sample 2-1 of the present invention and sample 2-8 of the comparative example have almost the same composition, but sample 2-1 containing aluminum carbide can be sintered at 1340°C, and the above-mentioned sample 2-1 has the same composition. like <1
It was sintered at a much lower temperature than Sample 2-8, which was not sintered at 450°C, and the present invention also contributes to energy saving.

Agent: Patent Attorney Tsutomu Setatetsu

Claims (1)

[Claims] 1. The following (a), (b), (C), (d) and (e)
) A strong cermet characterized by consisting of the following components. <a> One or more selected from IV a and Va group metal nitrides of the Periodic Table of the Elements: 5 to 30% by weight (b) One or two selected from Via group metals and their metal carbides Species or more: 3-40% (C) One or more selected from iron group metals: 2
．． 85-30% by weight (d) Aluminum carbide: 0.15-8% by weight (
e) Titanium carbide and inevitable impurities: remainder 2 <e
), less than 40% of titanium carbide is IV a and Va
The tough cermet according to claim 1, which is substituted with one or more selected from M metal carbides. 3 (a) Component has the chemical formula TiN, ZrN, HfN,
One or more types selected from VN, Nb N, and TaN, (b) component has the chemical formula Cr, one or more types selected from MO, W, MO2C, and WC, and (C) component has the chemical formula Ni1CO. The tough cermet according to claim 1 or 2, which is one or more selected from.