JPH04198437A - Manufacture of hard alloy - Google Patents

Abstract

PURPOSE:To improve the wear resistance and cuttability in a hard alloy while the amt. of iron group metals in a bonding phase is reduced by subjecting raw material mixed powder to compacting and preliminary sintering and thereafter executing hot isostatic pressing in the atmosphere of a high pressure inert gas at the temp. lower than the liquid phase appearing one or above. CONSTITUTION:Raw material mixed powder constituted of a hard phase constituted of one or more kinds among the carbides, nitrides and carbon nitrides of Na, Va and VI a group metallic elements and <=2wt.% iron group metallic bonding phase is compacted. This green compact is subjected to preliminary sintering at 1300 to 1600 deg.C and is furthermore sintered by hot isostatic pressing in the atmosphere of a high pressure inert gas of >=50kg/cm<2> at the temp. lower than the liquid phase appearing one or below. In this way, a hard alloy excellent in wear resistance and cuttability as an alloy for high pressure water-jet pumps and for tools such as cutting, sliding and wire drawing dies can be obtd.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention is applicable to high-pressure water nozzles, cutting, sliding, wire drawing dies, and other tools such as cemented carbide, cermet, and ceramic that have excellent cutting properties and wear resistance. This relates to a method of manufacturing hard alloys such as.

<Conventional technology and its issues> Conventionally, hard alloys for tools with good wear resistance and excellent cutting properties have been produced by combining a hard phase consisting of carbides, nitrides, etc. of group IVa, Va, and VIa metal elements with iron group metals. It is well known that it is obtained from the phase.

However, the amount of iron group metal used as a binder phase in hard alloys to date is mostly 2 to 20% by weight. It has been recognized that if the amount is less than 2% by weight, the resulting hard alloy has no practical properties such as impact resistance and toughness.

Furthermore, it was recognized that if it exceeds 20% by weight, the high-temperature hardness decreases, which is undesirable.

Furthermore, as in the present invention, grain size of 1μ made of carbides, nitrides, and carbonitrides of IVa, Va, and VIa group metal elements.
Hard alloys obtained by vacuum sintering or sintering under normal pressure or reduced pressure using the following hard phases and 2% by weight or less of iron group metal as the binder phase have a composition with a small amount of liquid phase. Because it has poor cohesion and cannot obtain good density (nests) and structure, there is a limit to its wear resistance, especially frictional wear resistance and cutting wear resistance.
It was not preferred as a hard alloy for high-pressure water nozzles or cutting tools.

<Means for Solving the Problems> In view of the above, the present invention is based on studies to obtain a hard alloy with an iron group metal content of the binder phase of 2% by weight or less and excellent resistance to frictional wear and cutting wear. This is the result obtained.

That is, the present invention applies to group IVa, group Va, and V of the periodic table of elements.
When producing a hard alloy that has a hard phase mainly composed of one or more of carbides, nitrides, and carbonitrides of group Ia metal elements, and that consists of the hard phase and 2% by weight or less of an iron group metal binder phase, the hard phase The raw material mixed powder constituting the binder phase was molded and heated at 1300
A hard alloy characterized by preliminary sintering at ~1600°C and then hot isostatic press sintering in a high-pressure inert gas atmosphere of 50 kg/cm2 or more at a temperature lower than the liquid phase appearance temperature or higher. The present invention provides a method for manufacturing.

<Operation> The present invention uses a small amount of binder phase of 2% by weight or less based on the powder constituting the hard phase consisting of one or more of carbides, nitrides, and carbonitrides of metal elements of group IVa, group Va, and group VIa. Although the iron group metal powder has a composition with a small amount of liquid phase, it is possible to accelerate sintering by hot isostatic pressure heating at high temperature and high pressure after preliminary sintering, making it possible to avoid conventional vacuum or normal pressure sintering. It is possible to obtain a hard alloy with excellent wear resistance, which cannot be obtained by other methods.

In order to obtain a good hard alloy in this invention, the particle size of the hard phase material powder is also a major factor, and the particle size is suitably 1 μm or less.

This is because the hardness of the obtained hard alloy is insufficient if it is 1μ or more, and the finer the particle size, the more uniform dispersion becomes possible and the toughness is improved.

Further, as the hard phase material, one or more powders of carbides, nitrides, and carbonitrides of metal elements of IVa group, Va group, and VIa group are used, but it is preferable that the powder is previously subjected to solid solution treatment.

This invention uses a mixed powder obtained by wet-mixing raw material powders for a hard phase and a binder phase in a ball mill, pre-sintering the powder, and then sintering it in a hot isostatic press. It is preferable to perform the sintering continuously under the same conditions in the same furnace as the preliminary sintering because the pressure during press sintering can be lowered.

Pre-sintering conditions are 1300-1600℃ in a vacuum atmosphere.
For sintering by hot isostatic pressing, it is appropriate to perform sintering by hot isostatic pressing at 1300 to 1600° C. for 1 hr under a pressure of 80 kg/cm 2 or higher in an atmosphere of an inert gas such as argon.

<Example> Hereinafter, this invention will be explained in detail with reference to Examples.

Example 1 93.7% by weight of We with average particle size of 0.5μ, average particle size of 1
μ Mo5.5% by weight, Go 0.4% by weight, VCo,
A raw material powder was prepared by mixing 4% by weight in a wet ball mill for 8 hours.

Using this raw material powder, preliminary sintering was performed at 1400° C. for 1 hour under vacuum.

Next, this sintered body was sintered by hot isostatic pressing in argon gas at 1000 kg/cm2 at 1320° C. for 1 hour to obtain a hard alloy.

Example 2 Using the same raw material powder as in Example 1, preliminary sintering was first performed at 1400°C under vacuum for 1 hour, and then in the same furnace under an argon gas atmosphere at 1400°C under a pressure of 80 kg/cm2.
Sintering was performed continuously by hot isostatic pressing for 1 hour to obtain a hard alloy.

When the density, hardness, transverse rupture strength, etc. of the hard alloys obtained in Examples 1 and 2 were measured, the results shown in Table 1 were obtained.

In addition, as a comparative example, using the same raw material powder, 1450
A hard alloy obtained by sintering at a temperature of 1 hr was measured.

As a result, it was found that the hard alloy produced by the method of the present invention was superior.

Table 1 <Effects of the Invention> As explained above, according to the present invention, although the amount of iron group metal as a binder phase is as small as 2% by weight or less, it can be used for cutting, sliding, and wire drawing dies for high-pressure water jet nozzles. It was recognized that a hard alloy with excellent wear resistance, hardness and cutting properties can be obtained as an alloy for tools such as.

Claims (3)

[Claims] (1) The main component is a hard phase consisting of one or more of carbides, nitrides, and carbonitrides of metal elements of Groups IVa, Va, and VIa of the Periodic Table of the Elements, and the hard phase and 2% by weight or less of iron When producing a hard alloy consisting of a group metal binder phase, the raw material mixed powder constituting the hard phase and the binder phase is molded, pre-sintered at 1300 to 1600°C, and then further sintered at a temperature lower than the liquid phase appearance temperature or higher. A method for producing a hard alloy, comprising hot isostatic press sintering in a high-pressure inert gas atmosphere of 50 kg/cm^2 or more. (2) The hard alloy according to claim (1), characterized in that the hard phase is a powder treated in advance with a solid solution treatment of a compound of a carbide, nitride, or carbonitride of a group IVa, Va, or VIa metal element. manufacturing method. (3) The method for producing a hard alloy according to claim (1) or (2), wherein the hard phase powder has a particle size of 1 μm or less.