JPS6244572A - Surface coated tool - Google Patents

Abstract

PURPOSE:To improve the wear and chipping resistances of a tool by coating the surface of a sintered hard WC alloy or cermet with TiCN and/or TiN under prescribed conditions. CONSTITUTION:The surface of a sintered hard WC alloy or cermet is coated with TiCN and/or TiN by chemical vapor deposition at 700-900 deg.C. The thickness of a layer formed by the chemical vapor deposition is regulated to 1-5mum. The layer is composed of alternately deposited two or more TiCN and TiN layers having <=2mum thickness as single layer. Thus, the wear and chipping resistances of the resulting tool are improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a tool coated with a hard material. In particular, it relates to surface-coated tools that are effective in wear resistance and chipping resistance.

[Prior art and its problems]

By coating a hard substance on WC-based cemented carbide or cermet,
Improvements in wear resistance and fracture resistance have conventionally been carried out. However, coating by CVD (chemical vapor deposition) cannot exhibit sufficient performance due to problems such as a decarburized layer that forms at the boundary between the base material and the coating and abnormal growth of coating particles. This tendency is particularly strong in milling tools that perform interrupted cutting. Therefore, for milling, PVD method (physical vapor deposition method) is used.
is applied. However, the PVD method has problems with adhesion and cannot exhibit sufficient performance due to build-up and shedding of the film.

In view of the above, an object of the present invention is to provide a surface-coated tool that has excellent fracture resistance, particularly mechanical impact resistance when used as a milling tool.

[Means for solving problems]

That is, the present invention applies the MT-CVD method (medium temperature chemical vapor deposition method), which allows coating at low temperatures, compared to the conventional CVD method, which has problems such as reducing the decarburized layer and preventing abnormal growth of coating particles. Multi-frequency f of TiCN and TiN
Excellent wear resistance as a milling tool by setting li 1 to 5 μm and the thickness of each single layer to 2 μm or less,
We obtained the knowledge that fracture resistance can be ensured.

The present invention has been made based on the above findings, and T
The iCN and TiN coating layer causes the following reaction between the organic CN compound, titanium tetrachloride and hydrogen (nitrogen),
The surface was coated.

2TiCQ, +2CH1(CN)+3H, →2Ti'(
CN)+6H(ll+2cH,cQ2TiCQ,+N2
+4H,→2TiN+HCl2 The deposition temperature was 750 degrees for TiCN and 800 degrees for TiN. The multilayer coating of TiCN and TiN obtained as a result is characterized by having finer particles and less decarburized layer at the boundary between the coating and the base material compared to coatings made by conventional CVD method.

Furthermore, it is desirable that the single layer thickness of the TiCN or TiN layer be 2 μm or less; if the thickness is more than 2 μm, the crystals of the film will become coarse, the toughness will decrease, and the surface will become rough and uneven.
This is because it is a drawback as a price tool.

In addition, the reason why the thickness of the rII layer is set to 1 to 5 μm is that if it is less than 1 μm, the desired wear resistance cannot be maintained.
This is because if the layer thickness exceeds .mu.m, the adhesion will decrease and it will be easy to peel off due to mechanical impact.

〔Example〕

Next, the surface-coated tool of the present invention will be specifically explained using examples.

Example 1 94%WC-6%Go (same weight percentages), TiCN on cemented carbide (chip model number SNMA432)
(C/N=7/3), TiN films were alternately coated with each layer having a thickness of 1 μm and a total thickness of 4 μm. This sample is designated as A. At the same time, for comparison, 4μ of TiC was placed on the above cemented carbide.
m coated. This sample is designated as B. These two types of samples were cut using a lathe under the following cutting conditions.

Work material S CN440 Cutting speed 200 m/min Feed 0.3 mm/rev Depth of cut 2 mm Tested. Sample B, a comparative product, reached the end of its life after 15 minutes due to wear, whereas Sample A according to the present invention showed good cutting performance even after cutting for 30 minutes.

Example 2 T i CN2c cermet h (65%T i CN-
10%WC-10%TaC-15%Ni) as the base
NMN4324. - Processing, Table 1 by MT-CVD method
It was coated with a film like this.

The sample was subjected to an intermittent test using a 6-inch cutter (DN type) under the following conditions.

Work material SCN440 Cutting speed 200m/min Feed: 0.15mm/blade Cut 2mm The results are also shown in Table 1.

Next, a life test was conducted by changing only the feed to 0.05++n/blade. The results are also shown in Table 1.

From the results in Table 1, the adhesion of the film by multilayer coating is improved;
It is clear that it exhibits excellent wear resistance and chipping resistance.

〔Effect of the invention〕

As mentioned above, the surface-coated tool of the present invention exhibits excellent wear resistance and chipping resistance by applying multilayer coating and MT-CVD method, and is suitable for coating not only cemented carbide but also cermet. It is suitable.

Claims (1)

[Claims] 1) A tool in which the surface of a WC-based cemented carbide or cermet is coated with TiCN and/or TiN, characterized in that the coating method is a chemical vapor deposition method carried out at 700 to 900°C. Coated tools. 2) In claim 1, TiCN and TiN
1. A surface-coated tool comprising a coating layer having a thickness of 1 to 5 μm, a single layer having a thickness of 2 μm or less, and at least two or more layers alternately coated.