JPS605673B2 - Surface-coated cemented carbide with good peeling resistance - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a surface-coated cemented carbide using a WC-based cemented carbide as a base material, and particularly to one having improved peeling resistance.

Components of the hard coating layer applied to the base material of WC-based cemented carbide,
Many proposals have been made and implemented regarding configurations and corresponding manufacturing methods.

However, cutting tools, which are the main application for surface-coated cemented carbide, have the disadvantage that large cutting forces are applied at high temperatures during use, which causes the coating to peel off and expose the base material, increasing tool wear. Ta.

The present invention was made to eliminate this drawback, and W
Peeling resistance characterized by surface-coated cemented carbide using C-based cemented carbide as a base material, characterized in that WC particles in the surface layer of the cemented carbide base material in contact with the hard coating layer are larger than WC particles inside the base material. The content is a cemented carbide with a good surface coating.

The reason why peeling resistance is improved by dispersing coarse WC on the surface is not yet clear, but the mechanical bonding force increases due to the increased unevenness of the base material surface, and in the case of face cutting etc. It is thought that the fact that the base metal surface is less likely to be plastically deformed in response to the surface temperature rise and deep shearing force that occurs in this process is effective in maintaining the hard layer.

The size of the coarse WC on the surface is not particularly limited, but the effect is significant when the average grain size is 1.3 or more times larger than the average grain size of the internal WC.

In order to show the structure and effects of the present invention, examples of the present invention and comparative examples for comparison will be described below.

Example 1 A powder was prepared so that the total carbon content of the WC-5.5%Co alloy was slightly higher than the theoretical carbon content, and the compact obtained by compacting the powder was heated to a low temperature of about 1 square Hg. 1500 pm 0,3 in vacuum
I gave 0 minutes of dawn pay.

The inside of the false body consisted of approximately 3.5 French WC, and a large amount of 5 to 10 French WC was generated only on the surface. This base material has TICo. 4NO. 50 o. , about 10 mountains were covered. This is designated as sample A. Comparative Example 1 A powder was prepared so that the total carbon content of the WC-5.5%Co alloy was less than the theoretical carbon content, and the powder compact obtained by compacting the powder was heated to 2 × 10-2 side Hg. 150 pi○ in the vacuum of
Sintering was performed for 30 minutes.

The surface of the Akatsuki body is almost the same as the inside, with an average diameter of 3.5 Buddhas.
It was an aggregate consisting of C. This was coated on TICMN ship 0M under the same conditions as in Example 1. This is designated as sample B.
End face cutting was performed using Sample A and Sample B as cutting tools under the following conditions.

Work material: JIS standard S5 skin steel Cutting speed: 55 to 150/min Feed rate: 0.2 Yanagi/rev Depth of cut: 1.5 side Sample B was processed in 2 passes (although peeling occurred on the surface). Sample A
It was still normal after 10 passes, and the surface remained.

Example 2 A very thin layer of organic adhesive was applied to the surface of a semi-sintered body of WC-6%Co alloy, and approximately 10 μm of WC powder was adhered to the surface. It was a 60 minute race.

The surface of this sintered body is covered with approximately one layer of 10mm WC, covering the internal aggregates made of WC with an average grain size of 31mm, and the gaps between the 10mm WC are solidified by Co leached from the inside. was combined with. This is followed by o. 5NO. Approximately 7A of 5
A coating consisting of was applied in the gas phase. This sample is designated as C.
Comparative Example 2 Example 2 was applied to a WC-6%Co alloy without coarse WC on the surface.
under the same conditions as HfCo. 5NO. 5 was coated, and this was designated as sample D.

Wet cutting was performed using Sample C and Sample D as cutting tools under the following conditions.

Work material: JIS standard FC3 steel Cutting speed: 150 m/m Ten Feed rate: 0.3 side/rev Depth of cut: 1.5 side Flank surface peeling occurred in sample D after 3 steps, but in sample C Even after 6 inches of cutting, normal wear was still observed.

Example 3 Apply a very thin layer of organic adhesive to the surface of a semi-sintered body of WC-3%TIC-5%TaC-6%Co alloy, adhere 10 pieces of WC powder to that surface, dry it, and then vacuum It dawned at 1400 oo in 60 minutes. The surface of this sintered body is covered with approximately one layer of WC of 10 mm, and the inside is coated with WC of 3 mm of average grain size.
The gaps between C were strongly bonded by Co leached from inside. Add to this a small 4N small 50o per day. A coating of approximately 4# thick was applied in the gas phase. This sample is designated as E. Comparative Example 3 WC-3%TIC-5%TaC- without coarse WC on the surface
mCo. was added to the 6% Co alloy under the same conditions as in Example 3. 4NO
．． Sample F was coated with 50M to a thickness of about 4 mm.

Wet cutting was performed using Sample E and Sample F as cutting tools under the following conditions. Work material: JIS standard SCM21 steel Cutting speed: 80/min Feed rate: 0.2 side/rev Depth of cut: 1.5 ribs Sample F had peeling on the flank surface at 18 h, but sample E
showed normal wear even after cutting for 3 hours.

As described above, the surface-coated cemented carbide of Example 1 without and Example 3 clearly has superior peeling resistance compared to the surface-coated cemented carbide of Comparative Example 1 without and Comparative Example 3, respectively, and the effect of the present invention is is appearing. In the above examples, adjusting the amount of carbon and adhering powder were used as a method to obtain coarse WC on the surface.
Regardless of the method used, the effects of the present invention will be exhibited as long as the surface layer in which coarse WC is dispersed is firmly bonded.

In the above examples, a vapor phase chemical vapor deposition method was used as the coating method for the hard coating layer, but the present invention may be applied even if other coating methods are used or the components of the hard coating layer are different from those in the above examples. The effect of improving the peeling resistance of the invention is exhibited.

Since the present invention provides a surface-coated cemented carbide suitable as a material for cutting tools, its industrial value is great.

Claims (1)

[Claims] 1. In a surface-coated cemented carbide using a WC-based cemented carbide as a base material, the WC particles in the surface layer of the cemented carbide base material in contact with the hard coating layer are larger than the WC particles inside the base material. Surface cemented carbide with good peelability.