JPS5929667B2 - Sintered material for cutting tools with excellent toughness and wear resistance - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a dense sintered material containing cubic boron nitride that exhibits excellent cutting properties when used for cutting high-hardness steel, which requires particularly excellent wear resistance and toughness. This relates to binding materials.

In recent years, sintered materials for cutting tools that exhibit relatively good cutting properties when cutting under harsh operating conditions have been developed, with cubic boron nitride as the main component (generally containing 90% by volume or more) and a small amount of metal components. A sintered material that contains iron (in this case, iron group metals and tungsten carbide are mixed into containers etc. during mixing of raw material powder and high-temperature, high-pressure sintering) was proposed.
The sintered material, which is commercially available and is certainly a good choice, is stable up to high temperatures of about 1100°C and contains cubic boron nitride, which has extremely high hardness second only to diamond, as a main component, so it has excellent wear resistance. Moreover, it has properties that make it difficult to react with iron group metals and their alloys.
It is used for cutting high-hardness steel and Ni-based heat-resistant alloys.

However, although the conventional sintered materials mentioned above have high hardness as mentioned above, they do not have sufficient toughness, and this lack of toughness tends to cause chipping wear during cutting. At present, it is not possible to fully demonstrate the excellent wear resistance that it has.

From the above-mentioned viewpoints, the present inventors conducted research to obtain a sintered material for cutting tools that has excellent toughness and wear resistance, and as a result, the sintered material has the following characteristics: , and thermal conductivity are both high, while the coefficient of thermal expansion is small, and furthermore, the skeleton structure is easy to form, and the skeleton structure has high flexural strength and wettability with the sintering aid metal constituting the binder phase. (b)
A sintering aid metal consisting of one or more of Al*NtscomFesMn and Si, which promotes the formation of a skeleton structure and provides strong bonding of the skeleton; (c) cubic nitridation having high hardness; When composed of boron, three of the cubic boron nitride and the cubic high melting point compound solid solution are strongly bonded by the sintering aid metal.
A sintered material is obtained which has a dimensional skeleton structure and therefore has excellent toughness due to the skeleton structure and excellent wear resistance due to the cubic boron nitride. They obtained the knowledge that it shows extremely excellent cutting performance when used for.

This invention was made based on the above knowledge, and the sintered material for cutting tools is made of: the cubic crystal high melting point compound solid solution: 1O to 60 volume ratio, the sintering aid metal = 0.2 to 5 volume ratio. It is characterized by having a component composition consisting of the cubic boron nitride and unavoidable impurities: the remainder.

Next, in the sintered material of the present invention, the reason why the component composition range and the cubic high melting point compound solid solution are limited as described above will be explained.

■ Cubic crystal high melting point compound solid solution (a) Content Cubic crystal high melting point compound solid solution used as raw material powder (
(Tim*Tan, Wl-m n) (Cx*Ny m
01x y ) z ) Powders include, for example, TiC powder, TiN powder, TiO powder, TaC powder, TaN powder,
After blending and mixing WC powder in appropriate proportions, 150
It is prepared by a solid solution method at a high temperature of 0°C or higher or a solid solution synthesis method involving other reduction reactions, but if the content is less than 10% by volume, a skeleton structure with high toughness cannot be sufficiently formed. However, if the content exceeds 60% by volume, the hardness decreases significantly and it becomes impossible to secure the desired wear resistance. 10
~60 capacity staff.

(b) Value of m If the value of m is less than 0.4, the Ti content is too small to ensure the desired high temperature hardness and chemical stability; If the Ti content is too high, the excellent bending strength and thermal conductivity of the cubic high melting point compound solid solution will decrease. It was set as 0.8.

(c) Value of n If the value of n is less than 0.1, the good thermal conductivity provided by the Ta component will decrease, and the flexural strength of the skeleton structure formed in the sintered material will decrease. On the other hand, if the value exceeds 0.5, the high temperature hardness will decrease, so the value should be set to 0.1 to 0.5.
It was determined that

In addition, the value of (1-m-n) indicating the content ratio of W is 0.1
It is best to set the value to ~0.5, and if the value is less than 0.1, W
If the content is too small, the above-mentioned properties of the cubic high melting point compound solid solution will deteriorate, while if the value exceeds 0.5, the W content will be too large and WCl will not dissolve in the solid solution. This is because if the compound remains and forms a single compound solid solution, it will not be possible to remove the compound.

(C)・X value When the value of X is less than 0.1, the C content is too low and high temperature hardness decreases,
If the value of
~0.9.

(a) Value of y If the value of y is less than 0.1, the C content becomes relatively too large and the thermal conductivity decreases; on the other hand, if it increases beyond 0.9, the relative The value of y was determined to be 0.1 to 0.9, since high-temperature hardness decreases if the C content is too low.

Also, regarding the value of O (combined oxygen) 1-x-y, 0.0
It is desirable that the value is within the range of 1 to 0.5, because if this value is less than 0.01, oxidation resistance will decrease and wear will progress quickly, while if it exceeds 0.5, O This is because the content of C and N becomes relatively small compared to the amount of steel, and the high-temperature hardness decreases.

(e) When the value of z value 2 is less than 0.8, the content of (T i + Ta + W) relative to the content of (C0N10) becomes relatively large, and the high temperature hardness decreases. Nashi, on the other hand 1.0
Conversely, if the value exceeds 2, the content of (Tj+Ta+W) decreases, making it difficult to form a single compound solid solution, and free carbon becomes present, so the value of 2 is set to 0. It was set as 8 to 1.0.

(2) Content of sintering aid metal The sintering aid metal promotes the formation of a three-dimensional skeleton structure consisting of cubic boron nitride and cubic high melting point compound solid solution, and has wettability with both of the above components. A I # N 1 which has good properties and has the effect of strongly binding with both of the above components.
g CO# Fe m Mn One or more of two or more of s and Si is used, but if the content is 0.
If the amount is less than 2 volumes, the desired effect cannot be obtained,
Moreover, extremely high temperatures and pressures are required during sintering, and on the other hand, if the content exceeds 5 volume, the high temperature hardness will decrease, so the content should be reduced from 0.2 to
5 capacity staff.

Further, the sintered material of the present invention is manufactured using a known ultra-high pressure and ultra-high temperature generator.

That is, a cubic high melting point compound solid solution powder, a cubic boron nitride powder, and a sintering aid metal powder are blended in a predetermined ratio and mixed in an iron ball mill using a dry or wet mixing method to form a homogeneous mixed powder. , the mixed powder is sealed in a container made of steel or high-melting point metal, and then charged into an ultra-high pressure and ultra-high temperature generator as described in Japanese Patent Publication No. 38-14-1980, and the pressure and temperature are raised to produce the final product. pressure 4
0 to 60 Kb and a temperature of 1,200 to 1,800°C.1 It is manufactured by maintaining this maximum pressure and temperature for several minutes to several tens of minutes, and then releasing the pressure after cooling.

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

Example 1 As a raw material powder, (Tio
, 6 TaO, I W□, 3 ) (Co, 72
No, 2300.05).

,9. A cubic high melting point compound solid solution powder with an average particle size of 0.8 μm having the composition = 20 volume, a cubic boron nitride powder with a volume of 9 volume of the same 1.0 μm, and a Ni powder with the same 1.0 μm
The mixed powder was mixed and dried for 24 hours in a cemented carbide ball mill using acetone as a solvent.

Next, the resulting mixed powder was made into a powder having a diameter of 10 mmφ.
Stainless steel (SUS) with dimensions of x height lOmrn
304) It was packed into a tube and sealed by welding a lid made of the same material while drawing a vacuum.

The tube filled with the mixed powder and sealed was placed in a known ultra-high pressure and ultra-high temperature generator, and the maximum applied pressure was 60 Kb.
, held for 10 minutes at a maximum heating temperature of 1400°C,
The sintered material of the present invention was produced by releasing pressure and cooling.

The resulting sintered material of the present invention has substantially the same composition as the raw material powder (T ig, 6 T'a0.1 wo, 3
) (C0,72NO,2300,05)0.95, and had a skeleton structure in which the cubic crystal high melting point compound solid solution particles and the cubic boron nitride element were tightly bonded.

Next, the above-mentioned sintered material of the present invention and the above-mentioned conventionally known cubic boron nitride-based sintered material, namely C
A cutting edge is formed by cutting and polishing from a cubic boron nitride-based sintered material having a composition containing o: 6 volume fraction and the remainder substantially consisting of cubic boron nitride L. Made of WCC cemented carbide. A cutting tool made of a sintered material of the present invention and a cutting tool made of a conventional sintered material were manufactured by brazing with chip silver solder.

Regarding both of the above cutting tools, Work material: JIS, SNCM-8 (HRC: 52), Cutting speed: 120rn/rrIin, Feed rate: 0.1 ho/revs, Depth of cut: 0. A dry cutting test was conducted under the conditions of I I&, and the flank wear was 0 and 2.
When we measured the cutting time to reach 1 mm, the cutting tool made of the sintered material of the present invention required 58 minutes, whereas the cutting tool made of the conventional sintered material reached the above wear amount in 4 minutes. It is clear from these results that the cutting tool made of the sintered material of the present invention exhibits excellent cutting performance.

Example 2 A solid solution powder of a cubic high-melting point compound having an average particle size of 1.2 μm prepared in advance by a known high-temperature synthesis method so as to have the component composition shown in Table 1, and a cubic crystal high melting point compound solid solution powder having an average particle size of 1 μm Boron nitride powder and sintering aid metal powder of the same 1.0 μm were mixed, and these mixed powders were sintered under the same conditions as in Example 1 to obtain sintered materials 1 to 10 of the present invention and comparative sintered materials. Binder materials 1 to 3 were each produced.

Note that Comparative Sintered Materials 1 to 3 have compositions that are outside the scope of the present invention.

For the purpose of comparison, a powder having a different composition (see Table 1) from the cubic high melting point compound solid solution powder according to the present invention but having the same average particle size and prepared by the same high-temperature synthesis method was also prepared. High melting point compound solid solution powder, TiC powder, and Ti
N powder is used, and cubic boron nitride powder of the same average particle size and sintering aid metal powder are added to it so that it has the composition shown in Table 1. Comparative sintered materials 4 to 8 were prepared by preparing blended powders containing boron nitride powder as a main component, and sintering these blended powders under the same conditions as in Example 1, respectively.

A cutting tool was manufactured in the same manner as in Example 1 from the resulting sintered materials 1 to 1O of the present invention and comparative sintered materials 1 to 8, and the following was carried out: Work material: JIS, SNCM-8 (HRC: 50) , Cutting speed: 100rrL/min, Feed: 0.15mm/revs, Depth of cut: Q, 2mm.

A dry cutting test was conducted under the following conditions, and the cutting time until the flank wear reached 0.2 mm was measured.

The measurement results are also shown in Table 1.

As is clear from the results shown in Table 1, the sintered material of the present invention containing a solid solution of a cubic high melting point compound having the above-mentioned predetermined composition can be used for cutting steel, especially high-hardness steel. It shows excellent cutting performance.

As mentioned above, the sintered material of the present invention has excellent toughness and wear resistance required for cutting steel, especially high-hardness steel, and Ni-based heat-resistant alloy.

Claims (1)

[Claims] 1 Compositional formula: (Tim*TansW1-m-n) (C
x#Ny*01X'/)ZsHowever, m: O-4~0.8 In: 0.1~0.5
ax: 0.1-0.9, y: 0.1-0
．． 9, 1-x-y: 0.01-0.5 #Z
: Cubic crystal high melting point compound solid solution expressed by 0.8-1.0=lO-60 volume ratio, 1 of Al*N15co*FemMn5 and Si
A sintering aid for cutting tools with excellent toughness and wear resistance, characterized by comprising a sintering aid metal of 0.2 to 5 volumes, cubic boron nitride, and unavoidable impurities: residue. Sintered material.