JPS63103071A - Surface coated sintered hard alloy - Google Patents

Abstract

PURPOSE:To improve the wear resistance of a sintered alloy by forming a tough inside layer enriched with a binder and outside layer consisting of a betasolid soln. and hard material on the surface of a sintered hard alloy consisting of carbide or carbonitride of metals and Co, etc., as a binder, coating with carbide or carbonitride of Ti. CONSTITUTION:A cutting tool, etc., consisting of the sintered hard alloy are produced by mixing the powder of the Fe family metal such as Co as the binder at the time of sintering with the powder of the hard material such as carbide or carbonitride of group 4a, 5a, 6a elements of the periodic table such as WC, TiCN and TaC and press-molding the mixture, then subjecting the molding to high-temp. sintering in a vacuum. The inside layer consisting of the hard carbide, etc., contg. the binder such as Co at a high ratio is formed to 2-40mum thickness on the surface of such alloy and the layer of the carbide, etc., contg. <=4% binder and contg. the beta solid soln. as the essential component is formed to 1-10mum thickness thereon. The alloy is in succession heated to 700-900 deg.C in a gaseous mixture composed of TiCl4, H2, org. CN compd. and N2, by which the hard layer of TiCN or TiN is formed on the surface.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a surface-coated cemented carbide with significantly improved wear resistance that is industrially useful as cutting tools and wear-resistant parts.

[Prior art]

Cemented carbide is a sintered material mainly composed of carbides of groups 4a, 5a, and 6a, and iron group metals. Carbide fine particles are dispersed in iron group metals (hereinafter referred to as bond metals), and the hardness of the carbides and the bond metals are It has properties that combine toughness. As the amount of bonded metal increases, toughness increases, but wear resistance decreases, so cemented carbide having various compositions are used depending on the application. On the other hand, advances have been made in technology that improves wear resistance while limiting deterioration in toughness by forming a surface layer that is more wear-resistant than on a base made of cemented carbide, and various surface-coated tool materials have been put into practical use. There is. Furthermore, before surface coating, a hardened and/or softened cemented carbide surface layer is provided on the substrate for the purpose of improving wear resistance and impact resistance.

Listed below are the manufacturing methods and characteristics of conventionally manufactured hardened and/or softened surface layers of surface-coated cemented carbide.

(1) Method for Forming a Laminated Alloy The inner layer is made of a cemented carbide with excellent wear resistance, and the inside is made of a cemented carbide with excellent toughness. Manufactured from two types of alloy powder. Laminated alloys are not only difficult to manufacture;
Very little is manufactured today as it offers little improvement in wear resistance.

(2) Method by adding nitrides By adding a small amount of group 4a nitrides, a β-free layer is generated on the surface (a layer that does not contain β phase over several tens of microns from the surface) and crack propagation from the coating after coating. Improve your sexuality.

(3) Method of enriching the bonding metal A method of enriching the bonding metal with the highest toughness to improve impact resistance as a surface coating alloy.

The surface of the cemented carbide treated according to these purposes is coated with carbides and carbonitrides by chemical vapor deposition by reacting chloride vapor of Ti metal with methane gas or nitrogen in a hydrogen atmosphere at 900°C to 100°C. Ti on heated cemented carbide
It is manufactured by forming a thin film of carbide or nitride. Coating alloys currently on the market include titanium carbonitride coating alloys, titanium nitride coating alloys, Al□○, coating alloys.

and multi-layer coated alloys thereof, all of which have high wear resistance, and a coating of 2 to 20 microns increases the wear resistance of cemented carbide by 3 to 10 times.

[Problem that the invention seeks to solve]

The majority of surface-treated coating alloys currently on the market are tungsten carbide, cobalt, and titanium carbide.

The surface of a cemented carbide for cutting, whose main component is tantalum carbide, is coated with carbides, nitrides, and oxides.It is widely used for cutting cast iron and steel, but it often causes abnormal wear when cutting steel. In some cases, the coating layer may not be able to exhibit its excellent abrasion resistance. The reason for this is observed from the progress of wear in steel cutting. After part of the coating layer disappears due to wear or minute chips, wear progresses rapidly from the disappeared part.
There is a phenomenon where the cutting edge does not wear uniformly and wears locally. Furthermore, when high heat and high pressure are applied to the cutting edge of a tool, the cemented carbide base becomes softened and plastically deformed, so that the wear resistance of the coating layer may not be sufficiently exhibited.

[Means for solving problems]

The present invention relates to surface-treated cemented carbide based on the discovery of a new phenomenon, which solves all the performance problems of conventional coated cemented carbide, and makes it more wear resistant and versatile. It provides tool materials.

In the present invention, the surface of a cemented carbide made of carbides, carbonitrides, and iron group metals of groups 4a, 5a, and 6a has a thickness of 1 to 100 ml, which is made of carbides mainly composed of ferrous metals and β-solid solutions with an average content of 4% or less. ~
In a cemented carbide consisting of an outer layer of 10 microns and an inner layer of 2 to 40 microns thick made of the carbide and softer than the base, the coating layer is heated in a titanium tetrachloride-hydrogen-organic CN compound and/or nitrogen mixed gas. 700℃～900'
The present invention relates to a surface-coated cemented carbide characterized in that the surface of the cemented carbide is coated with titanium carbonitride and/or titanium nitride.

Although it is extremely rare for cutting tools to be used as cutting tools mainly consisting of less than 4% iron group metal and β-solid solution, it is applied as a thin layer of 1 to 10 microns on a highly tough cemented carbide. If so, it is extremely advantageous for improving wear resistance. A suitable thickness is 1 to 10 microns. If the diameter is less than 1 micron, the effect will be small, and if it exceeds 10 microns, the toughness of the tool will decrease.

In the present invention, iron group metals are added to the surface of a cemented carbide made of carbides, carbonitrides, and iron group metals of groups 4a, 5a, and 6a to a depth of 1 to 10 microns by adjusting the gas atmosphere during sintering. At the same time, a surface layer enriched with bonding metals with a thickness of 2 to 40 microns is formed inside the carbide, and then titanium tetrachloride-hydrogen- This is a cemented carbide coated with titanium carbonitride and/or titanium nitride by heating in an organic CN compound and/or nitrogen mixed gas at 700°C to 900°C.

Titanium carbonitride and titanium nitride coating treatment by chemical vapor deposition includes titanium tetrachloride, hydrogen, and organic CN compounds.

It is carried out in a mixed gas consisting of nitrogen. The partial pressure of the organic CN compound should be lower than that of titanium tetrachloride, and 1 of the hydrogen partial pressure.
/10 or less is suitable. Reaction temperature is 700-900℃
is suitable. When a titanium carbonitride coating is applied to a cemented carbide whose surface is enriched with β solid solution under the above conditions, the adhesion of the coating is improved because the β solid solution is large and the binder phase is reduced. The present invention further provides titanium tetrachloride and titanium tetrachloride-H2 organic CN.
By using a compound and/or nitrogen mixed gas, the temperature during vapor deposition is lowered, and a decarburized layer (
η-Carbide, MGC) decreases 5 strength decreases from 90 to 9
It was reduced to 5%.

Figure 1 shows the results of micro Vickers hardness measurements from the surfaces of a conventional titanium carbide-coated cemented carbide and the alloy of the present invention.The hardness of the conventional product decreased from the coating to that of the cemented carbide. On the other hand, the product of the present invention has an outer layer rich in β solid solution with high hardness and reduced amount of bonding metals, and an inner layer rich in bonding metals and low hardness, which are located between the cemented carbide and from the f-blind to the substrate. The hardness is changing.

The surface-treated cemented carbide of the present invention is suitable for high-speed cutting of steel and castings. That is, it has better heat resistance and resistance to compositional deformation than conventional coated alloys. It is also suitable for cutting that requires a good surface finish.

The reason for this is that the β solid solution and the outer layer have high hardness, and even if the coating is worn out, the β solid solution and the outer layer wear progresses slowly, which is effective in preventing abnormal wear.

Furthermore, the inner softened layer reduces crack propagation from the coating and improves chipping resistance.

Examples will be described in detail below.

〔Example〕

Example 1 Commercially available WC powder (average particle size: 4 μm), TiCN powder (average particle size: 1 μm), TaC powder (average particle size: 1.2 μm), Go grain powder (1 μm), and Ni powder (1 μm) were prepared. It was blended into a composition equivalent to Alloy P30, wet-pulverized and mixed in a ball mill for 96 hours, and after drying, ITo
Press molding was performed at a pressure of n/aJ. Then 1400 in vacuum
Sintered at ℃, and after sintering, CH4, N, and gases were introduced stepwise and slowly cooled to form an outer layer mainly made of nitride and an inner layer enriched with bonding metals, followed by low-temperature chemical vapor deposition. T by law
A chip of the present invention was manufactured by coating 1CN with a thickness of 6 μm.

Next, it was wrapped to a mirror surface, and the hardness of the intermediate layer was measured using a micro Vickers (load of 500 g).

Although FIG. 1 shows an example in which the outer layer is 5 μm and the inner layer is 20 μm, the thickness of the intermediate layer can be changed by controlling CH4, N, gas partial pressure, and cooling rate.

The amount of bonded phase can be varied. Furthermore, when changing the ratio of C and N in the substrate, it is necessary to adjust the CH4 and N2 gas partial pressures.

Example 2 A cutting test was conducted using the alloy of Example 1 under the following conditions, and its performance was evaluated. For comparison purposes, a conventional CVD chip was also tested.

■Life test material 30M440 (Hs40) chip S
NMN432 (Honing 0.03+om) Cutting speed 200 m/min Feed 0, 2 mm/rev depth of cut
2m Cutting time 10+in Evaluation Flank wear ■ Fracture resistance test Work material 30M440 (Hs40) (4 grooves) Insert SNMN432 (honing 0.03mm)
Cutting speed 100 m/min Feed 0.3~1゜Omm/rev Depth of cut 2 m Cutting time 1 min Evaluation Start from 0.3 an/rev, and if cleared, increase feed by 0.05 an/rev and conduct further cutting test. Subsequently, the feed rate was increased sequentially.

The chip of the present invention has a flank wear amount V B = 0, 12
m m, the comparative chip has VB=0.13 mrn, which is not much different, but when intermittent cutting is involved, the feed rate that does not cause chipping is 0.7 mm/rev for the inventive chip, whereas the comparative chip has a feed rate of 0.7 mm/rev. There was a big difference of 3 mrn/rev. It is clear that the alloy of the present invention exhibits performance that combines wear resistance and toughness by forming an intermediate layer.

〔Effect of the invention〕

The surface-coated cemented carbide of the present invention improves the plastic deformation resistance, wear resistance, and chipping resistance of the substrate by providing an outer layer rich in β solid solution and an inner layer rich in bonding metal between the substrate and the coating layer,
By exhibiting the effect of surface coating, wear resistance, heat resistance, and welding resistance are greatly improved, making it suitable as a cutting tool.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the results of measuring the micro-Vickers hardness of the intermediate layer of the present invention.

Claims (1)

[Claims] The surface of the cemented carbide made of carbides, carbonitrides, and iron group metals of groups 4a, 5a, and 6a contains an average of 4% or less of ferrous metals and β
- An outer layer with a thickness of 1 to 10 microns consisting of carbides, carbonitrides, and iron group metals mainly composed of solid solutions, and an outer layer with a thickness of 2 to 40 micrometers, which is softer than the substrate and consists of the carbides, carbonitrides, and iron group metals.
In a cemented carbide consisting of an inner layer of microns, the coating layer is heated in a titanium tetrachloride-hydrogen-organic CN compound and/or nitrogen mixed gas to coat the surface of the cemented carbide with titanium carbonitride and A surface-coated cemented carbide characterized by being coated with/or titanium nitride.