JPH04304332A - Sintered hard alloy excellent in wear resistance and breaking resistance - Google Patents

Abstract

PURPOSE:To obtain a sintered hard alloy excellent in wear resistance and breaking resistance by dispersing specific percentages of TiN-coated TiC whiskers into a specific sintered hard alloy consisting of binding phase of Co, Ni, and Fe and dispersed phase of WC. CONSTITUTION:A WC-base sintered hard alloy is obtained by providing a composition consisting of, by weight, 4-15% of one or more elements among Co, Ni, and Fe as binding phase forming components and the balance WC, as dispersed phase forming component, with inevitable impurities. If necessary, the above dispersed phase forming component may have a composition consisting of <=40% of one or more kinds among the carbides, nitrides, and carbonitrides of Ti, Ta, Nb, and W and solid solution thereof and the balance WC. Whiskers are incorporated similarly as dispersed phase forming component by 5-30% into the above sintered hard alloy. At this time, TiC whiskers coated with TiN are used as the above whiskers. It is preferable that the surface of the resulting sintered hard alloy is further coated with a hard layer consisting of single layer or multilayer of the carbides, nitrides, and carbonitrides of Ti, Zr, and Hf and Al2O3.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] This invention is a cemented carbide suitable for high-efficiency machining such as high-speed continuous cutting and high-feed interrupted cutting, which has excellent wear resistance and chipping resistance. The present invention relates to a cemented carbide whose surface is coated with a hard layer, which is suitable for processing.

0002

[Prior Art] In recent years, titanium carbide (hereinafter referred to as TiC), titanium carbonitride (hereinafter referred to as TiCN), and titanium nitride (hereinafter referred to as TiCN) have been developed as cemented carbide with excellent wear resistance and chipping resistance. , TiN), etc., have been provided which have improved chipping resistance (see Japanese Patent Application Laid-Open No. 2-71904). Cemented carbide coated with a hard layer is also available (Japanese Unexamined Patent Application Publication No. 2002-2010)
(See Publication No. 71906).

The cemented carbide described in JP-A-2-71904 contains Co, Ni, Fe (
One or more of the following (hereinafter referred to as iron group metals):
carbides, nitrides, and carbonitrides of Ti, Ta, Nb, and W, and solid solutions of two or more of these (however,
Excluding W carbides, all of these will be referred to as (Ti, Ta,
One or two of the following: Nb, W) (expressed as C/N)
A cemented carbide containing 0.5 to 30% by weight of tungsten carbide or more, with the remainder consisting of tungsten carbide as a dispersed phase forming component and unavoidable impurities, as well as TiC whiskers, TiCN whiskers, and TiN whiskers as dispersed phase forming components. Contains 3 to 40% by weight of one or more whiskers based on the entire cemented carbide,
Furthermore, the cemented carbide described in JP-A-2-71906 has Ti on the surface of the whisker-dispersed cemented carbide.
A hard layer consisting of a single layer or a multilayer of two or more of carbides, nitrides, carbonitrides, carbonitrides, and Al2O3 is coated with an average thickness of 0.5 to 20 μm. That's what happens.

0004

However, the conventional cemented carbide containing the TiC whisker, TiCN whisker and TiN whisker dispersed in the cemented carbide has the following problems. That is, (1) TiC whiskers and TiCN whiskers are
Because the strength of the whiskers themselves decreases when they react with iron group metals, which are the binder phase forming components of cemented carbide, cemented carbide containing TiC whiskers and TiCN whiskers dispersed in the base material has poor wear resistance. and lack of fracture resistance,
When this cemented carbide is used as a cutting tool for high-speed continuous cutting or high-feed intermittent cutting under conditions that are more severe than conventional ones, abnormal wear and damage to the cutting edge tend to occur. (2) In general, if the whiskers are tightly adhered to the dispersion base, the propagated cracks will cut the whiskers, making it impossible to obtain sufficient fracture resistance. Therefore, in order to improve the fracture resistance of whisker-containing cemented carbide, it is necessary to disperse and contain whiskers with even higher strength.
It is said that chipping resistance is further improved by making the adhesion between the whiskers and the substrate insufficient and maintaining the condition in which the whiskers in the substrate are pulled out when a crack occurs (hereinafter, the strength is increased by pulling out the whiskers). (The effect of improving this is called the pull-out effect). However, the above TiC
Whiskers and TiCN whiskers have excellent adhesion to the cemented carbide substrate, so the above-mentioned pulling effect cannot be fully exhibited. Therefore, cemented carbide containing TiC whiskers and TiCN whiskers dispersedly is particularly suitable for high-feed intermittent applications. Fracture resistance cannot be obtained when used for cutting. (3) On the other hand, TiN whiskers have an excellent pulling effect due to their low adhesion and reactivity with the cemented carbide substrate, but since the strength of the TiN whiskers themselves is low, a Hard metals do not have sufficient wear resistance and chipping resistance.

[0005]

[Means for Solving the Problems] Therefore, the present inventors obtained a cemented carbide containing dispersed whiskers that has sufficient wear resistance in high-speed cutting and sufficient fracture resistance in high-feed interrupted cutting. As a result of research, we decided to use a TiC whisker as the core, which has the highest strength among TiC whiskers, TiCN whiskers, and TiN whiskers, and coated the surface of this TiC whisker with TiN, which has low adhesion and reactivity with the substrate. Whiskers (hereinafter referred to as TiN coated TiC whiskers)
Cemented carbide made by dispersing TiC whiskers, TiCN whiskers, and TiN whiskers in a cermet base has better wear resistance and resistance than conventional cemented carbide made by dispersing one or more of TiC whiskers, TiCN whiskers, and TiN whiskers. They obtained the knowledge that it shows a deficiency.

The present invention was made based on this knowledge, and contains 4 to 15% by weight of one or more iron group metals as a binder phase-forming component, and if necessary, As dispersed phase forming components, (Ti, Ta
, Nb, W) One or more of C/N: 40
% by weight or less, with the remainder consisting of tungsten carbide as a dispersed phase forming component and unavoidable impurities, and TiN coating TiC whisker as a dispersed phase forming component in the proportion of 5 to 30% by weight of the entire cemented carbide. It is characterized by a cemented carbide containing 5 to 30% by weight of the TiN coated TiC whiskers dispersed in the surface of the cemented carbide.
, Zr, Hf carbide, nitride, carbonitride and carbonitride oxide, and aluminum oxide. Hard metals also have characteristics.

Next, the reason why the composition of the cemented carbide of the present invention is limited as described above will be explained.

(a) Iron group metal These components have the effect of strongly bonding with the dispersed phase and improving strength and toughness, but their content is 4% by weight.
If the content is less than 15% by weight, the desired effect cannot be obtained, while if the content exceeds 15% by weight, the hardness will be significantly lowered and the wear resistance will be reduced.
It was set at 5% by weight.

(b) (Ti, Ta, Nb, W)C/N These components have the effect of increasing the hardness of the alloy and improving its wear resistance, so they may be included as necessary. However, if the content exceeds 40% by weight, the fracture resistance will decrease, so the content was set at 40% by weight or less.

(c) TiN coating TiC whiskers These components have the effect of dramatically improving fracture resistance as described above, but if their content is less than 5% by weight, the desired excellent fracture resistance cannot be achieved. On the other hand, if the content exceeds 30% by weight, it becomes difficult to disperse and distribute it uniformly in the substrate, causing local unevenness in the material. It was set at 30% by weight.

[0011]

EXAMPLES Next, the present invention will be specifically explained based on examples.

Example 1 Raw material powders include WC powder and various powders (Ti, Ta, Nb,
W) Prepare C/N powder, Co powder, Ni powder, and Fe powder, and also prepare TiN coated TiC whiskers, TiC whiskers, and TiN whiskers having an aspect ratio (length/diameter) in the range of 10 to 100. did.

[0013] These raw material powders were blended into the compositions shown in Tables 1 to 3, wet mixed in a ball mill for 72 hours, then lightly mixed with or without whiskers, dried, and then mixed at 10T/cm2. It is press-molded into a green compact using pressure, and this green compact is heated to 1 x 10-2 torr.
Vacuum sintering at a temperature of 1380 to 1400°C, or a temperature of 1380 to 1400°C and a pressure of 20°C.
Hot pressing was performed under the conditions of 0 kg/cm2, and the sintered body vacuum sintered under the above conditions and the hot pressed body were polished to form a chip with the shape of SPP422, and TiN coated TiC whiskers were dispersed. The present invention cemented carbide indexable tips (hereinafter referred to as the present invention carbide tips) 1 to 15 and the comparative cemented carbide indexable tips 1 to 2 (hereinafter referred to as the comparative cemented carbide tips), and TiC whiskers or Conventional cemented carbide indexable tips 1 to 9 containing TiN whiskers dispersed therein (hereinafter referred to as conventional cemented carbide tips) were manufactured, respectively.

[0014] The carbide tips 1 to 15 of the present invention described above are as follows:
The TiN coated TiC whiskers are dispersed and contained within the range of 5 to 30% by weight of the entire cemented carbide that satisfies the conditions of this invention, and the comparative cemented carbide chips 1 and 2 each contain 5% by weight outside the scope of this invention. % and less than 30% by weight
It contains a super TiN coating and TiC whiskers dispersed therein.

[0015]

[Table 1]

[0016]

[Table 2]

[0017]

[Table 3]

[0018] The various carbide tips manufactured in this way were subjected to cutting test A. Work material: SCM440 (hardness: HB 200) square material;
Cutting speed: 150m/min, Feed: 0.5mm/rev, Depth of cut: 2mm, Cutting oil: A high feed intermittent cutting test was conducted on steel under the following conditions: Cutting time until flank wear width reached 0.3mm were measured and the state of the cutting edge was observed, and the results are shown in Tables 4 and 5.

[0019]

[Table 4]

[0020]

[Table 5]

From the results shown in Tables 1 to 5 above, it is clear that Ti
The carbide chips 1 to 15 of the present invention containing 5 to 30% by weight of N-coated whiskers are all common TiC chips.
It can be seen that the cutting time until the flank wear width reaches 0.3 mm in high-feed intermittent cutting is longer than that of the conventional carbide tips 1 to 9 containing dispersed whiskers or TiN whiskers, and the cutting edge condition is also good.

[0022] Furthermore, even if the carbide tip contains TiN coated TiC whiskers dispersed in the base material,
It can be seen that if the dispersed content is less than 5% by weight, the fracture resistance is poor, while if the content exceeds 30% by weight, uneven wear of the cutting edge occurs, making it unusable as a cutting tool.

Example 2 The carbide tips 10, 12, and 15 of the present invention prepared in Example 1, comparative carbide tips 1 and 2, and conventional carbide tips 8 and 9 were used as substrates, and the surfaces thereof were subjected to conventional chemical vapor deposition. Coated cemented carbide chips of the present invention (hereinafter referred to as comparative coated chips) 16 to 24 and comparative coated cemented carbide chips (hereinafter referred to as comparative coated chips) having coating layers having the compositions shown in Tables 6 to 7 were prepared using the method. )3
- 4 and conventional coated cemented carbide chips (hereinafter referred to as conventional coated chips) 10 to 18 were produced.

[0024] Using these various coated tips, high-feed intermittent cutting was carried out under exactly the same conditions as in the cutting test A of Example 1, and furthermore, cutting test B: Work material: SCM415 (hardness: HB 150). Round bar,
A high-speed continuous cutting test was conducted under the following conditions: cutting speed: 250 m/min, feed: 0.2 mm/rev, depth of cut: 1.5 mm, cutting oil: present, and the flank wear width was 0.
．． The cutting time up to 3 mm was measured, and the results are shown in Table 8.

[0025]

[Table 6]

[0026]

[Table 7]

[0027]

[Table 8]

From the results in Tables 6 to 8, it can be seen that coating the surface with a hard layer improves the wear resistance as a whole, but compared to the coated chips 16 to 24 of the present invention coated with a coating layer with the same component composition and the conventional coated chips. chip 10
-18, the present invention coated chips 16-24
It can be seen that all of the chips have better wear resistance and chipping resistance than the conventionally coated chips 10 to 18. Furthermore, even if the TiN coated TiC whiskers are dispersed and contained, it can be seen that Comparative Coated Chips 3 and 4, which contained the TiN coated TiC whiskers in an amount other than 5 to 30% by weight of the present invention, all have inferior performance as cutting tools.

[0029]

[Effects of the Invention] The cemented carbide of the present invention has excellent wear resistance and chipping resistance, so when used as a cutting tool, it lasts for a long time compared to conventional whisker-containing cemented carbide. It exhibits excellent cutting performance and brings excellent industrial effects.

Claims (4)

[Claims] Claim 1: One or more of Co, Ni, and Fe as a bonding phase forming component: 4 to 15% by weight
, and the remainder is tungsten carbide as a dispersed phase forming component and unavoidable impurities. Whisker is also added as a dispersed phase forming component to a tungsten carbide based cemented carbide having a composition of 5 to 30% by weight based on the entire alloy. A cemented carbide having excellent wear resistance and chipping resistance, wherein the whisker is a titanium carbide whisker coated with titanium nitride. 2. One or more of Co, Ni, and Fe as a bonding phase forming component: 4 to 15% by weight
and further contains Ti, Ta, N as dispersed phase forming components.
Contains 40% by weight or less of one or more of b and W carbides, nitrides, carbonitrides, and solid solutions of two or more of these (excluding W carbides), with the remainder A tungsten carbide-based cemented carbide having a composition consisting of tungsten carbide as a dispersed phase-forming component and inevitable impurities, and containing 5 to 30% by weight of whiskers as a dispersed phase-forming component in the entire alloy. In the alloy, the whisker is a titanium carbide whisker coated with titanium nitride, a cemented carbide having excellent wear resistance and chipping resistance. 3. On the surface of the cemented carbide of claim 1, Ti,
It is characterized by being coated with a hard layer consisting of a single layer or a multilayer of two or more of carbides, nitrides, carbonitrides and carbonitrides of Zr, Hf, and aluminum oxide. A cemented carbide with excellent wear resistance and chipping resistance. 4. On the surface of the cemented carbide of claim 2, Ti,
It is characterized by being coated with a hard layer consisting of a single layer or a multilayer of two or more of carbides, nitrides, carbonitrides, and carbonitrides of Zr, Hf, and aluminum oxide. Cemented carbide with excellent wear resistance and chipping resistance.