JPS597777B2 - Tough cermet - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cermet with excellent toughness, heat resistance, wear resistance, and high-temperature strength. A cermet whose toughness has been improved by adding titanium nitride (hereinafter referred to as TiN) to the recommended cermet is already on the market.

It is true that by adding TiN to the TiC cermet, grain growth of hard dispersed phase particles during sintering in the cermet production is suppressed, so the wear resistance and toughness of the cermet are improved. Furthermore, when the cermet is used as a cutting tool material, it has a low affinity with the workpiece material during cutting, resulting in improved properties such as a reduction in the amount of wear. Since the wettability with the phase tends to decrease, sintering irregularities and pores are formed in the manufactured cermet, and the strength cannot be avoided.

From the above-mentioned viewpoint, the present inventors conducted research to improve the wettability of the hard dispersed phase particles with the binder phase in a nitrogen-containing cermet, and to improve the strength of the binder phase itself. (a) Titanium carbonitride (with a C/N atomic ratio of 1 or more, formed by heating to an appropriate temperature and causing a thermal reaction in an atmosphere of vacuum, inert gas, or nitrogen gas) 1 to 40 atoms equivalent to Ti atoms (hereinafter referred to as TiCN) are Zr, Hf, V, Nb, Ta, Cr, Mo,
The hard particles having a crystal structure substituted with one or more of W and W have characteristics of good wettability with a metal binder phase and little grain growth during sintering.

Therefore, a cermet containing 70 to 95 weight percent of the hard particles as a dispersed phase has excellent toughness.

Hb) As a binder phase component, Co + N i +,
kl is suitable.

(c) In the binder phase consisting of the above C o 1 N i + A 7, in terms of weight ratio and in a state satisfying both conditions of and 0.1, Fe: 0.1 to 10%, W: 1 to 20%, Mo: 1~
When one or more of Cr: 20% and Cr: 1 to 20% is contained, the binder phase is solid solution strengthened, and the high temperature strength of the cermet is further improved.

The findings shown in sections (a) to (c) above have been obtained.

This invention was made based on the above findings, and the reason for the numerical limitations based on the above findings will be explained below.

(1) Dispersed phase and binder phase When the content of the dispersed phase is less than 70%, the content of the binder phase correspondingly becomes too high, exceeding 30%, and heat resistance and abrasion resistance are impaired. Therefore, the content of the dispersed phase must be 70% or more.

However, if the content of the dispersed phase exceeds 95%, that is, the content of the binder phase is too small, less than 5%, many pores will remain after sintering, making it impossible to secure the desired toughness in the cermet. Therefore, the content of the dispersed phase should be reduced to 7.
The content of the binder phase was limited to 0 to 95%, and the content of the binder phase was limited to 5 to 30%.

(2) Dispersed phase (1) C/N atomic ratio If the C/N atomic ratio of the dispersed phase is less than 1, that is, the amount of N is greater than the amount of C, wetting between the dispersed phase and the binder phase during sintering. This is undesirable because the hardness is poor and metal oozes out easily, and furthermore, the hardness of the hard phase itself decreases, resulting in a decrease in wear resistance, making it impossible to obtain a tough and wear-resistant cermet. /N atomic ratio was limited to 1 or more.

■ Zr, Hf, V, Nb, Ta, Cr, M
o, and W When a part of Ti in TiCN is replaced with these components, the high-temperature strength of the cermet is improved, and when Mo and W are substituted in particular, the wettability with the binder phase metal is further improved. However, if the substitution ratio is less than 1 atomic % of the Ti equivalent portion of T i CN, the desired effect of improving properties cannot be obtained, so it is necessary to carry out the substitution at the lower limit value or more.

However, if more than 40 atoms of itETicN, which corresponds to Ti, are substituted, the excellent oxidation resistance and wear resistance of TiCN will be degraded. Don't let it happen.

(3) Binding phase In order to impart excellent heat resistance and toughness to the cermet, the binding phase was composed of Co +N i +At.

■Ni%/Co%+Ni%In order to further improve the high-temperature strength of cermets, solid solution strengthening of the binder phase and improvement of wettability were once necessary.
It is necessary to set the ratio of ±N i % to 0.2 to 0.8.

That is, if the ratio is less than 0.2 or more than 0.8, either Ni or Co will be contained in too large a quantity, and the solid solution strengthening of the binder phase will not be sufficient, resulting in This means that it does not have sufficient properties to be used as a cutting tool material that requires high-temperature strength.

■ At%/Co%+Ni%+A7%In the bonded phase containing A7 in Ni and Co, Ni3A
7 (Ti) type intermetallic compound is finely precipitated, which strengthens the binder phase, and since these precipitated particles precipitate in a consistent state with the matrix, the cermet can withstand high temperatures without deteriorating its toughness. This results in high strength.

However, if the ratio is less than 0.001, C of the A7 component
If the content of AA and Ni components is too small, the desired effect cannot be obtained in the above-mentioned action, and on the other hand, if the ratio exceeds 0.1, the content of AA becomes relatively too large and NiAA The ratio was determined to be 0.001 to 0.1, since this is undesirable as a brittle mold compound would precipitate.

■Fe, W, Mo, and Cr As mentioned above, these components have the effect of forming a solid solution in the binder phase and strengthening it, thereby improving the high-temperature strength of the cermet, so high-temperature strength is particularly required. However, if the content is less than 0.1% in the binder phase, the desired solid solution strengthening cannot be achieved; If the content exceeds the above upper limit, the oxidation resistance of the cermet will decrease and the wettability with the dispersed phase will also decrease. Therefore, the content should not exceed the above upper limit.

Regarding W', Mo, and Cr, if the content is less than 1% each, the desired solid solution strengthening cannot be achieved, whereas if each is contained in the binder phase in excess of 20%, intermetallic compounds are formed. Since the binder phase becomes brittle due to the formation of
limited to.

Next, the cermet of the present invention will be specifically explained with reference to Examples.

Example First, for the purpose of preparing (Ti,M)CN powder (M: substituted component) as a raw material powder, TiC powder having an average particle size of 1.5 μm, TiCO. 8 No. 2 powder, TiC
0.6No. 4 powder, TiN powder, ZrC powder, TaC
Powder, HfC powder, C r s C 2 powder, and 1 μm WC powder, Mo2C powder, VC powder, and NbC powder are prepared, and after blending these powders into a predetermined composition and mixing, vacuum Medium, 1550-1700
By thermally reacting at a predetermined temperature within the range of °C for 2 hours to form a solid solution, and after cooling, pulverizing in a ball mill, all of them have an average particle size of 1 μm, and are shown in Table 1. Various types of (Ti, M)CN with compositions
A powder was produced.

Next, the various (Ti, M)CN powders obtained as a result, the average particle diameters prepared for the purpose of manufacturing conventional cermets:
TiC powder with 1.5 μm and TiN powder, Co powder, Ni powder, and Fe powder with 1 μm;
Using 5 μm Ni-A,4 alloy (containing 30% AI) powder and Cr powder, and 0.7 μm W powder and Mo powder as raw material powders, these raw material powders were blended into the composition shown in Table 1. The mixture is wet-mixed in a high-speed rotating mill using carbide balls, dried, and then press-molded into a green compact.
The cermet 1 of the present invention, which has substantially the same composition as the blended composition, is produced by sintering the cermet 1 in vacuum at a temperature of 1,400 to 1,500°C under conditions of holding the temperature for 1 hour.
-28 and conventional cermets were produced, respectively.

Next, the transverse rupture strength and Rockwell hardness (A scale) of the resulting cermets 1 to 28 of the present invention and the conventional cermet were measured, and the work material: JIs. Continuous steel high-speed cutting test under the conditions of sNcM-s (hardness: HB220), depth of cut: 1.5 mm, feed: 0.45 M/rev-, cutting speed: 220 m/mirb, cutting time: 15 min+, and work material: JIS. An interrupted steel cutting test was conducted under the following conditions: S45C (hardness: HB250), depth of cut: 1.5mm, feed: change value, cutting speed: 14077z/min, cutting time: 2min for each feed, and the former In the continuous steel high-speed test, the rake face wear width of the cutting edge was measured, and in the latter, interrupted steel cutting test, the feed was gradually increased and the feed was checked at the point when a breakage occurred on the cutting edge.

The results of these measurements are shown in Table 2. From the results shown in Table 2, cermets 1 to 28 of the present invention all have higher strength (higher transverse rupture strength) than conventional cermets, and therefore exhibit excellent fracture resistance, especially in the interrupted steel cutting test. It is also clear that the continuous copper high-speed cutting test shows excellent wear resistance.

As mentioned above, the cermet of the present invention has excellent toughness, heat resistance, wear resistance, and high-temperature strength, so it can be used particularly as a tool material in a wide range of applications from low-speed cutting to high-speed cutting, and hot compression dies. It exhibits extremely useful properties when used as hot processing tools that are exposed to high temperatures for relatively long periods of time, such as hot extrusion punches, hot wire drawing rolls, and hot forging dies.

Claims (1)

[Claims] 1. 1 to 40 atoms equivalent to Ti atoms of titanium carbonitride having a C/N atomic ratio of 1 or more are substituted with Zr, Hf, V, Nb
, Ta , Cr , Mo , and a hard dispersed phase having a crystal structure substituted with one or more components of W: 70 to 95 weight coefficient, and 0.001 to 0.1. C content that satisfies
A tough cermet characterized by comprising: 5 to 30% by weight of a binder phase consisting of o 10N i 10A 1 and inevitable impurities. 2 1 to 40 atoms equivalent to Ti atoms of titanium carbonitride having a C/N atomic ratio of 1 or more are added to Zr, Hf, V, Nb
, Ta, Cr, Mo, and W: Hard dispersed phase having a crystal structure substituted with one or more components of 70 to 95 weight ratio, Fe: 0.1 to 10 weight ratio, W: 1 to 20 weight ratio, Mo: 1 to 20 weight ratio, 7 Cr: 1 to 20 weight ratio. A tough cermet characterized by comprising a binder phase consisting of Co+Ni+A1 having a content of 0.01 to 0.1 and an unavoidable impurity: 5 to 30% by weight.