JPS59110776A - Surface coated sintered hard alloy - Google Patents

Abstract

PURPOSE:To enhance the heat resistance and the toughness of the titled alloy, by applying an Al2O3 and/or ZrO2 layer having a predetermined thickness on the surface of a sintered alloy consisting of a predetermined hard phase and a bonding phase. CONSTITUTION:The titled alloy is formed by coating the surface of a sintered hard alloy with a thin layer with a thickness of 0.1-2mum comprising Al2O3 and/or ZrO2 directly or through an intermediate layer. The hard phase of the aforementioned sintered hard alloy comprises a transient metal belonged to the Groups IVa, Va, VIa of the Periodic Table and carbide and/or nitride of one or more of B and Si while the bonding phase comprising one or more of a metal selected from a group consisting of Fe, Co, Ni, Cr, Mo, W, Ti and Al. This surface coated sintered alloy is excellent in heat resistance and toughness.

Description

Detailed Description of the Invention (a) Technical Field The present invention relates to the improvement of a hard alloy for cutting tools that can be cut at high speeds, using a sintered hard base as a base, and having a hard and highly wear-resistant surface on the surface. It is a coated hard alloy coated with a substance.

(b) Background of the technology Cutting tool materials used in machining include high-speed steel,
As the cutting speed increases, various materials such as cemented carbide (WC-Co), cermet, and hexaramic are being put into practical use. The characteristics required for cutting tools are high hardness, high toughness, heat-resistant strength, and wear resistance, but recent improvements in machining speed,
Due to improvements in efficiency, requirements have become increasingly strict, and high-speed cutting at a cutting speed of several hundred m/min or more is now required.

Cermets, which have carbonitride as a hard phase and bond it with metal, are candidates for materials that meet this demand. This is, for example, FetC with transition metal carbonitride as the main hard phase, which is made by adding TasMoeW etc. to Ti carbonitride.
o sNi tMo eWt/V tTi A hard alloy bonded with one or more metals selected from Ti and sintered. So-called nitrogen-containing cermet is a cutting tool that greatly improves the heat resistance strength and thermal fatigue toughness of conventional TiC-based hard alloys that do not contain nitrogen. It is widely used as a tool. However, in recent years in the field of cutting processing, there has been a growing demand for increasing the cutting speed to a greater extent than before in order to improve efficiency. For example, in continuous turning of steel, the cutting speed is 500 m/min.
There is a growing demand for tools that can withstand the above areas. In such a region, even the above nitrogen-containing cermets are hardly of practical use due to their lack of heat-resistant strength, and only AlaOs-Tic ceramics are suitable for practical use. It is true that this AlzOs-TiC ceramic is practical from the viewpoint of wear resistance, but its application range is extremely narrow because it lacks toughness.

In addition, cemented carbide (WC-Ti) has recently been put into practical use in a wide range of fields.
The so-called coated cemented carbide, which has a substrate made of (C--Co, etc.) and whose surface is coated with AlzOs, cannot be put to practical use because the cutting edge of the tool deforms at high cutting speeds as described above.

(c) Purpose of the invention The present invention aims to improve the heat resistance of nitrogen-containing cermets and improve the heat resistance of nitrogen-containing cermets.
- The toughness, which is a drawback of TiC ceramics, is greatly improved, and an alloy for cutting tools that can be used in the high-speed cutting range of steel is provided.

B) Disclosure of the Invention In order to understand in detail the phenomena that occur during high-speed cutting of steel, the present inventors used various types of steel with different hardness as stiffening materials, and used nitrogen-containing cermet and K120S-Tic steel lamira mix l.
As a result of conducting high-speed cutting tests using gO,+ coated cemented carbide and P-10 cemented carbide as tools, surprising findings were obtained.

In other words, nitrogen-containing cermets, which were conventionally thought to be unable to withstand high-speed cutting due to their poor heat resistance and the plastic deformation of the tool edge when cutting at high speeds,
It was found that even in the range of 0 m/min, the tool cutting edge did not deform until crater wear progressed. In contrast, P-10 cemented carbide and AI! The cutting edge of the 20a-coated cemented carbide tool was instantly plastically deformed and could not be cut at all.

Furthermore, when comparing AJIIOa-TiC ceramic and nitrogen-containing cermet, ceramic has overwhelmingly good crater wear resistance. Ceramic has a longer life in areas where crater wear occurs, but in areas where crater wear does not occur, ceramic has an overwhelmingly good resistance to crater wear. The nitrogen-containing cermet actually had a longer life. This probably reflects the difference in toughness between the two.

Based on the above surprising findings, the inventors discovered that crater wear lI
It was thought that oxides such as Al2O5 are rich in carbon dioxide, and that nitrides, carbides, etc. oxidize when exposed to high temperatures in the air, impairing crater wear resistance. Therefore, we thought that if we coated the surface of nitrogen-containing cermet with a thin layer of oxide for crater wear resistance, we could obtain a cutting tool that has both toughness and wear resistance in the high-speed cutting range. .

According to this idea, we actually applied 1-metal A to nitrogen-containing cermet.
When we prototyped an alloy coated with lzOs, the expected effects were obtained.

The alloy of the present invention is used as a substrate in the periodic table I Va + V
a mVIa group transition all transition metal LZr tHf +Vt
Nb tTa +Cr +Mo 1w ) and B +
A hard layer is made of one or more carbides and/or nitrides selected from S i , and Fe e Co
A sintered alloy having a binder phase of one or more metals selected from +5-Ni +Cr +Mo1wl'ri and Al is used, and AI! QOs and/or Zr
It is a coated sintered hard alloy coated with a thin layer of O2 with a thickness of 0.1 to 20 microns. Then, as an intermediate layer between the substrate and the above-mentioned oxide thin layer on the surface, the periodic table IVatVaeVI
It is a coated sintered hard alloy having a coating layer of one or more carbides and/or nitrides of group a transition metals with a thickness of 0.1 to 10μ.

If the klsosrZroa coating is less than 0.1μ, there is no effect of improving wear resistance such as crater resistance, and if it is more than 20μ, the overall strength will be significantly lowered, which is undesirable.

Providing the above-mentioned intermediate layer between the substrate and the outer coating layer has the effect of improving the adhesion strength between the ceramic layer and the substrate, but if it is less than 0.1μ, there is no effect on the adhesion strength, and lOμ
Above this, the strength is significantly lowered, which is undesirable.

As a method for coating MhOs*ZrOs and a carbide or nitride as an intermediate layer on the substrate, the usual chemical vapor deposition method (CvD) or physical vapor deposition method (PVD) is preferable, but the method is not limited to the above-mentioned coating method. .

Next, a detailed explanation will be given using examples.

Example 1゜As a substrate (Ti + Ta yMo 1w) (C+
A commercially available nitrogen-containing cermet (model number 5NG432) in which carbonitride (N) is bonded with Ni and Co is coated with 1 μm of AlgOs on the surface by CVD.
B was coated with 1μ of ZrO2. For comparison, the untreated nitrogen-containing cermet (C), commercially available AJ20g-TiC ceramic (D), and commercially available AA'20
No. 8 coated cemented carbide (E) was prepared and a cutting test was conducted under the conditions shown in Table 1.

The results were as follows.

A: Both crater wear and flank wear were extremely small at a cutting time of 10 minutes.

B: Cuttable for 11 minutes and 4.8 seconds C: Flank wear was slight, but crater wear progressed, and the cutting edge became damaged at 6 minutes and 15 seconds due to the progress of crater wear, making cutting impossible.

D = Wear was slight, but boundary wear progressed significantly, and the cutting edge broke in 6 minutes and 35 seconds, making cutting impossible.

E: Cutting could only be done for 15 seconds due to plastic deformation of the tool tip.

Example 2゜The same nitrogen-containing cermet as Example 1 (model number 5NG4.3
2) The surface of the tool was first coated with 2μ of TiN using the CVD method, and then A77gOa was further coated on top of it. Cutting tests were conducted under the cutting conditions shown in Table 1 & C.12
Cutting was possible up to minute 28 seconds.

Example 3゜The same nitrogen-containing cermet as in Example 1 (model number C3N4.3
MT) The chip was coated with 2μ of Ti(CN) by a known ion blating method, and then coated with 1μ of k120s using a CVD method. Let this be F. Moreover, the material without coating treatment is designated as G.

A cutting test was conducted using this cutting tool under the conditions shown in Table 2.

As a result, G could only be cut for 8 minutes and 25 seconds, whereas F of the present invention could be cut for 14 minutes and 12 seconds.

Example 4 37% by weight of Tic, 3% by weight of TiN, 20% by weight of TaN
A nitrogen-containing cermet was prepared by blending 15 wt% wc, 10 wt% Mo2C''k, 10 wt% Ni, and 5 wt% Co, and using a normal powder metallurgy method.

(Model number TNMG 882 ENA). This surface was coated with 3.0μ of Ti (CN) by the ion plating method, and then coated with 1.0μ of k120s by the CVD method, and when the H1 commercially available alumina coating (same model number) was designated as ■, the following: A cutting test was conducted under the following conditions.

Cutting conditions: Work material: 5Cr420 (HB=190.95ru
L* x 300m bottom] Cutting speed: 550 m/min Feed: 0.25m bottom/rev.

Depth of cut: 0.8 to 1.0 ruL Holder: PTGNR2020 to 83 As a result, 23 pieces could be cut in H, but none could be cut in ■ due to plastic deformation of the cutting edge. Note that up to 12 pieces of the nitrogen-containing cermet without coating could be cut.

Example 5 A cutting test was conducted under the following conditions using a commercially available cubic boron nitride (CBN)-TiN ultra-high pressure sintered body (model number 5NG432) coated with 1μ of AlQO8 by ion blasting.

Cutting conditions Knee l〇- Work material: SCM415 (HB=180) Cutting speed:
1000m/min.

Delivery: 0.4.5B/re
v.

Depth of cut: 2.0 Holder: FNIR-44A The above tip of the present invention has flank wear of 0.1 after cutting for 5 minutes.
1 yield, crater wear (depth) was 0.03ruL, whereas the one without coating had flank wear of 9.38ax and crater wear of 0.14vux after cutting for 1 minute.

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Claims (1)

[Claims] (1) Transition metals of group rVaoVasVla of the periodic table and B. At least one carbide and/or nitride hard phase of Si, Fe sCo tNi sCr eMo tWt
AI! is applied directly or via an intermediate layer to the surface of a sintered hard alloy whose binder phase is one or more metals selected from the group consisting of Ti tAl ! A surface-coated sintered hard alloy characterized by being coated with a thin layer of +Og and/or Zr02 with a thickness of 0.1 to 20μ. (2. In claim (1), Ajp+O
The intermediate layer between the thin layer of s and/or ZrOs and the sintered hard alloy surface of the substrate corresponds to the periodic table IVa*Va*VIa.
One or more thin layers of carbides and/or nitrides of one or more group transition metals, with a total thickness of 0.1μ to 1
A surface-coated sintered hard alloy characterized by a coating layer of Oμ.