JP3410025B2 - Carbide cermet spray-coated member and method of manufacturing the member - Google Patents

Description

Detailed Description of the Invention

[0001] The present invention is a carbide cermet thermal spray coating that can be mechanically ground to sharp objects finish angle relates to a process for the preparation of the coating under member with such members, particularly various plastic, paper, leather, etc. We propose a surface coating technology for machine tools such as blades, precision molds, extrusion screw shafts, dies and dies, which are used for cutting products, soft metal sheets, foils, etc., especially at the corners.

[0002]

2. Description of the Related Art Generally, a thermal spraying method is used for metals (including alloys),
Ceramics, powdered materials such as cermet are melted by the combustion energy of plasma or flammable gas, and sprayed on the surface of the base material to form a sprayed coating, thereby improving the surface of the base material. Widely used in industry. For example, sprayed coatings of metals and alloys
It is used for rust prevention and corrosion protection of steel structures, and for imparting heat resistance and high temperature oxidation resistance to high temperature exposed parts used in boilers, gas turbines, heat treatment furnaces, etc. On the other hand, oxide ceramics are used for electrical insulation (Al ₂ O ₃ ) and heat resistance (ZrO ₂ ), and carbide ceramics are in the form of cermets containing metals such as Ni, Co, Cr. , Mainly used as a wear resistant film.

However, the conventional thermal spray coating is mainly applied for the purpose of improving the function in the plane of the member, and for example, the thermal spray coating is mechanically sharpened to reinforce the corners and edges of the member. There is no example of industrial construction that is used after processing. For example, a typical hard carbide cermet material WC-Co thermal spray coating is, as disclosed in Japanese Examined Patent Publication No. 7-26188 and Japanese Unexamined Patent Publication No. 1-87006, wear resistance of a flat portion of a member and soft non-ferrous metal. To prevent adhesion of
Further, the one disclosed in Japanese Patent Application Laid-Open No. 1-225761 is only used as a material for improving the molten metal erosion resistance of the flat portion of the member.

[0004]

As described above,
So far, thermal spray coatings have been used to improve the heat resistance, corrosion resistance, wear resistance, etc. of the surface of various members, especially the flat surface, that is, the “face”.
The reality is that it is not considered to improve the function of the edge part (hereinafter referred to as the edge part).

A main object of the present invention is to establish a technique of utilizing a carbide-based cermet thermal spray coating for reinforcing an edge portion of a steel base material such as a blade or a precision mold. Another object of the present invention is to propose a thermal spray coating member and a method for producing the same for sharpening the corners of a thermal spray coating obtained by machining so that the thermal spray coating can be used as a cutting edge of a blade, for example. It is in. That is, the present invention is
After forming a hard carbide cermet sprayed coating, this coating is cut and polished by machining to form an edge part, and the roundness R of this edge part (JIS B0701, conforming to the roundness regulation of the machine part) is 50 μm or less. Suitable as a blade with good sharpness and excellent wear resistance, and as a member for finishing the edge part of the die for injection molding of precision molds and dies or plastics that requires high precision. The present invention is intended to propose a thermal spray coating member used for the above and an advantageous manufacturing method thereof.

[0006]

Means for Solving the Problems As a result of earnest research to realize the above-mentioned objects, the inventors have come up with the following means for solving the problems according to the gist configuration. That is, the present invention is, firstly , on the surface of a steel substrate, in which the distance (λ) between the carbide-based dispersed particles in a metal matrix is 2.12 to 5.05 μm .
Dispersed so that 囲内 covered by the following carbide cermet sprayed coating formed by, and a feature that the rounded R of the corner portion formed by machining the portion of the sprayed coating is finished to 50μm or less Carbide cermet thermal spray coating member. The above-mentioned carbide cermet spray coating has a particle size of 0.1 to 3 μm.
m selected from WC, Cr ₃ C ₂ , B ₄ C, TiC, ZrC and Nb
Select from one or more carbides and Ni, Cr, Co and Mo
Charcoal consisting of one or more metals or their alloys
Compound cermet primary particles are formed under the interposition of a binder.
Aggregated particles that are agglomerated and agglomerated to a particle size of 5 to 60 μm
Carbide cermet thermal spray material composed of
It is formed by shooting

[0007]

In the present invention, the above-mentioned carbide cermet thermal spray coating has a particle diameter of 0.1 to ₃ μm, WC, Cr ₃ C ₂ ,
One or more carbides selected from B ₄ C, TiC, ZrC and Nb
And one or more selected from Ni, Cr, Co and Mo.
Carbide cermet made of metal or these alloys
The primary particles are granulated under the interposition of a binder to give a particle size of 5
Consists of aggregated particles aggregated to ~ 60 μm
Rukoto formed by thermally spraying a carbide cermet spraying material which is preferably configured.

Furthermore, the present invention is characterized in that the surface of a steel substrate is
Temperature: the 2000 ° C. to 3000 thermal spraying a combustible gas combustion flame as a heat source of ° C., the following carbide cermet spraying material, by impinging in per second 180m or more flight speed, mutual carbide particles dispersed in a metal matrix Set the interval (λ) to 2.
Dispersing to form carbides cermet thermal spray coating in the range of 12～5.05Myuemu, roundness R of the corner portion of the thermal spray coating
It is a method for producing a carbide cermet spray-coated member, which is characterized in that machining such as grinding or polishing is performed so as to be 50 μm or less. Serial particle diameter of _{0.1~3μm, WC, Cr 3 C 2} , B 4 C, TiC, ZrC Contact
And one or more carbides selected from Nb and Ni, Cr, Co
And one or more metals selected from Mo and Mo
The primary particles of carbide cermet consisting of
Granules under the interposition of a sander, the particle size is 5-60 μm
Carbide sarme composed of agglomerated particles
Thermal spray material.

[0010]

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The background of the development of the present invention will be described below. Generally, a method of forming a thermal spray coating of hard carbide or carbide cermet is well known in order to modify the surface of a steel substrate such as a steel knife or a die. Typical of the carbide cermet,
TiC, ZrC, HfC, VC, TaC, NbC, WC, B ₄ C, SiC or
Carbide composed of at least one of Cr ₃ C ₂ and N,
A metal or alloy (hereinafter, alloy is also referred to as metal) made of at least one kind of i, Co, Cr, or Mo is used. However, although the thermal spray coating formed by using these carbide cermets has excellent wear resistance, simply machining this thermal spray coating, for example, cutting or polishing, makes it possible to obtain the corner shape because it is a ceramic. It cannot be sharpened so that the roundness R is 50 μm or less.

As a result of research on this cause, the inventors have found the following facts. That is, since the sprayed coating originally has a layer formed by an aggregate of fine particles stacked and deposited, if it is cut by machining or if the cut portion is polished smoothly, a large load is imposed on the coating, resulting in a sprayed coating. The phenomenon that particles locally fall off frequently occurs. In particular, when trying to shape a corner by mechanically grinding a ceramic sprayed coating, the roundness R of the corner inevitably results in a broad finish of more than 100 μm, let alone form a sharp edge that also serves as a cutting edge. I couldn't do it.

Therefore, the following items were examined again for the carbide cermet thermal spray coating for the edge member of the present invention, such as a knife and a precision mold. (1) Thermal spraying heat source: plasma or combustible gas (including liquid fuel) Considering the superiority of combustion flame, (2) Flight velocity of thermal spraying particles:
The flight speed of the thermal spray material particles flying in the heat source (10
0 to 350 m / sec) with a laser velocimeter to find a suitable velocity, (3) Types of spray material and particle size: WC, Cr
Suitable particle size (5-60) of carbide cermet materials obtained by adding one or more of Ni, Co, Cr and Mo to ₃ C ₂ , B ₄ C, TiC, ZrC and NbC.
μm), (4) Machinability of sprayed coating and finish of corners: Examining edge characteristics finished by mechanical grinding or diamond polishing,

As a result of repeated experiments on the above items, it was found that it was necessary to adopt the following conditions in order to obtain the predetermined effects desired by the thermal spray coating of the present invention. (1) As a thermal spray heat source, a plasma jet is suitable for melting carbides because it can obtain high temperatures, but in a thermal spray environment, decomposition and oxidation reactions of carbides are intense, and a dense thermal spray coating cannot be formed. Rather, the heat source temperature is 2000 ℃ ~ 3000 ℃
It has been found that even if the degree is small, the use of the combustion flame of a combustible gas and the explosion energy thereof causes less alteration of the carbide and makes it easier to obtain the film intended by the present invention. (2) The flying speed of sprayed particles is required to be high speed of 180 m / sec or more. At lower speed, many pores are formed in the sprayed coating, and the interparticle bonding force is insufficient, so machining is performed. It was found that the particles that fell off were conspicuous and that sharp angle finishing could not be done. (3) As the thermal spray material, satisfactory results were obtained for all the tested carbides and metal components, but it was found that the metal component content needs to be adjusted within the range of 5 to 35 wt%. The reason is that if the metal content is less than 5 wt%, the coating becomes fragile, and as a result, some of the secondary agglomerated particles that have been sprayed may fall off locally during machining, and 35 wt%
The thermal sprayed coating containing more metal components causes a problem in terms of wear resistance due to a decrease in hardness, and as described below, the mutual spacing of the carbide-based dispersed particles constituting the coating becomes too large. It turns out that I cannot achieve the purpose of. (4) As the thermal spray material, the above-mentioned carbide (including composite carbide and carbide-based intermetallic compound) cermet is suitable, and it is necessary to use secondary agglomerated particles of this cermet, and the agglomerated particle diameter is 5 A size in the range of up to 60 μm is preferred. The agglomerated particles are secondary particles obtained by granulating primary fine particles having a size of 0.1 to 3 μm obtained by crushing a carbide cermet through a binder such as a liquid organic polymer material, that is, It was found that the one composed of agglomerated particles was optimal. The reason for this is that the secondary agglomerated particles are
Particles larger than 60 μm are not sufficiently heated in the thermal spray heat source and have a low density, and only a thermal spray coating having a weak interparticle bonding force can be formed. On the other hand, the secondary agglomerated particles are 5μ
If the particle size is smaller than m, it becomes difficult to supply the particles to the thermal spray gun, and the film forming rate is slow, which causes a problem in productivity.

As described above, if the agglomerated particles of 5 to 60 μm are formed by the granulation method using the fine particles of about 0.1 to 3 μm, the supply to the thermal spray gun becomes smooth, and in the heat source. A sufficient temperature rise can be obtained, and the formed thermal spray coating is dense and has good adhesion and interparticle bonding strength, and a thermal spray coating having sufficient properties to withstand sharp-angled finishing by machining can be obtained.

FIG. 1 is a thermal spray (powder) suitable for the purpose of the present invention.
3 is an electron micrograph of the material. This material is an example of agglomerated particles in which fine primary particles of 88 wt% WC-12 wt% Co are used and the particle size is adjusted to a range of 10 to 60 μm by a granulation method using a binder.

Further, FIG. 2 shows 88 wt% WC-12 wt% Co thermal spray (powder) produced by a melting method using plasma or the like.
A photograph of the appearance of the material is shown, in which the primary particles are not agglomerated but a single melt-bonded solid particle,
Even if the starting material (primary particles) has the same chemical composition and particle size, it is not an agglomerate of primary particles and cannot form the thermal spray coating that is the object of the present invention.

FIG. 3 schematically shows the surface of the thermal spray material of the present invention and the thermal spray coating formed under the thermal spray conditions, and schematically shows this. That is, although the metal component 2 exists as a binder around the fine primary particles 1, the thermal spray coating according to the present invention has a very small primary particle, and further, is formed by collision at a high flight speed. Because
The feature is that the mutual spacing of particles is very small.

In the present invention, the properties of the sprayed coating formed by spraying the agglomerated particles are as follows.
It is necessary that the carbide particles dispersedly present in the metal matrix have the following conditions, particularly the dispersed state of the carbide dispersed particles, that is, the particle spacing within a suitable range. The mutual spacing λ of the particles was determined as follows.
Letting N _{L be} the number of carbide particles per unit length cut out by an arbitrary straight line L _{x in the} field of view of an electron microscope, and N _S be the number of carbide particles contained in an arbitrary unit area, λ = (1-f) / N _L ...... (1) where, f is the volume fraction of carbide particles, also when the average particle diameter d _m of carbides, d _m, f is is respectively determined as follows. d _m = (4 / π) (N _L / N _S ) …… (2) f = (8 / 3π) (N ² _L / N _S ) …… (3)

In the carbide cermet sprayed coating for coating the surface of the member according to the present invention, the number λ calculated using the above formula (1) is 2.12 to
It is preferable that the thickness is in the range of 5.05 μm, and it has been found that such a thermal sprayed coating can be cut and polished at an acute angle by machining. The interval λ is 2.
A thermal spray coating smaller than 12 μm is difficult to manufacture only by a thermal spraying process, while a thermal spray coating with λ greater than 5.05 μm has low hardness and poor wear resistance, and the corner roundness R when machined Is difficult to finish so that it is less than 50 μm. Further, even if the roundness R can be finished to 50 μm or less, it is not preferable because it has poor wear resistance and therefore has a drawback that the edge portion is rounded in a short time during use.

[0021]

Example 1 In this example, WC-Ni / Cr cermet was selected as a thermal spray material, and gas plasma (Ar) and a combustible gas combustion flame (a mixture of ethylene / acetylene with oxygen of 50%) was used as a thermal source of thermal spray.
200μm on carbon steel (SS400) using pressurized combustion (MPa)
After the thick film was formed, the porosity, adhesion and X-ray diffraction of each spray coating were examined to examine the state of oxidation and decomposition of the spray material components due to high temperature exposure. The WC-Ni / Cr cermet used in this example had a density of 0.
Fine particles of 5 to 3 μm are granulated with a pelletizer by adding an organic binder, and agglomerated particles whose particle size is adjusted to a range of 10 to 35 μm, and molten solid particles which are melted and spheroidized to 10 to 40 μm by a plasma heat source. It is a kind.

Table 1 summarizes the above results. As is clear from the results shown in Table 1, the thermal spray coating formed by using the molten solid particles formed by the thermal spraying method using plasma as a heat source has a higher porosity than that using a combustion flame as a heat source. Quality (3-8%) and low adhesion (50-6
In addition, the oxidation and decomposition of WC (for example, W ₂ C, W ₃ Co ₃ C, etc.) by the high temperature plasma gas was remarkable. It should be noted that such a tendency was more strongly recognized in the thermal spray coating made of solid particles melt-granulated by plasma, as compared with the thermal spray coating made of agglomerated particles produced by the granulation method according to the present invention. In this respect, it has been found that the thermal spray coating formed by the method conforming to the present invention is dense and has a strong inter-particle bonding force, and the corners can be sharpened by machining.

[0023]

[Table 1]

Example 2 In this example, as the thermal spray material, a melting method (solid particles) was used.
Carbide cermet particles: WC-12wt% Co produced by two different methods, the agglomeration method and the agglomeration method, and the flight speed of the sprayed particles is determined by the spraying method using the combustion flame of combustible gas as the heat source. This is an example of spraying the corners of a steel block (50 mm × 50 mm × 100 mm) in the range of 100 to 350 m / sec while adjusting the supply pressure. FIG. 4 (a) shows the order of forming the thermal spray coating on the steel block. First, including the corner part of this steel block, 50μm thick at the position of a, then b
The process of forming a sprayed coating having a thickness of 50 μm at the position of, and finally having a thickness of 30 μm at the position of c was once and repeated three times. Next, using the steel block on which the above-mentioned sprayed coating (a, b, c) was formed as a test piece for machining, a diamond tool was used to form a 100 μm-thick grinding coating (as shown in FIG. 4 (b)). After finishing to d), the edge e of the processed film was observed with a magnifying glass, and the roundness R of the finished edge e was optically measured.

Table 2 is a summary of the above results. As is clear from the results shown in this table, coatings sprayed with solid particles produced by the melting method (No. 1 ~ 6)
In the case of all of the processed edges, a minute particle missing portion was observed in the processed edge portion e. On the other hand, in the case of sprayed agglomerated particles produced by the granulation method, when the flight speed of the sprayed particles is slow (N
o. 7-10), the lack of particles was observed at the edge part, but at the edge part e of the thermal spray coating formed by flying particles with a high speed of 180 m / sec or more, no particles were missing at all. It was not seen, and it was confirmed that the roundness R of the processed edge portion e was finished to 50 μm or less. The No. 13 test piece described in Table 2 is an additional observation result of the edge portion machined using high speed tool steel (SKH2) for reference.

[0026]

[Table 2]

Example 3 This example is a thermal spray test piece obtained in the experiment of Example 2.
The surfaces (Nos. 7 to 12 in Table 2) after machining were observed with an electron microscope, and the mutual spacing λ of the carbide dispersed particles in the carbide cermet sprayed coating was measured by the method shown in FIG. FIG. 5 summarizes the results. As is clear from the results shown in this figure, the mutual spacing λ of the carbide particles of the thermal spray coating obtained under the condition that the flight speed of the thermal spray particles is small is generally large and its density is coarse. On the other hand, when a thermal spray material of the same quality and the same particle size is formed at a high flight speed, the density of the carbide particles becomes high, and the thermal spray coating obtained under the condition of 180 to 300 m / sec is It was found that the film was capable of achieving the object, and it was found that the range of the mutual spacing of the carbide particles of 2.12 to 5.05 μm was effective.

Example 4 In this example, a carbide cermet other than the WC-Co type carbide and a cermet thermal spray coating containing a plurality of carbides were machined in the same manner as in Example 2 by grinding the corner portion and finishing the corner. The roundness R of part e was tested. The thermal spray material in this example is composed of agglomerated particles produced by the granulation method,
The flight speed of particles in the thermal spray heat source was 210 to 240 m / sec. Subjected試溶morphism materials: (1) TiC -18wt% Ni -5wt% Cr-1wt% Mo (2) NbC -13wt% Ni-8wt% Cr (3) WC-2.5 wt% Cr 3 C 2 -12wt% Co- 1 wt% Fe (4) WC-1.8 wt% Cr ₃ C ₂ -8 wt% Co-5 wt% Cr As a result of grinding and polishing each film by machining, all the carbide cermet films have edge particles. It was confirmed that there was no loss and R was 20 μm or less.

Example 5 In this example, the sharpness of this blade was examined in the case of applying it to a blade as a thermal spray coating member conforming to the present invention. The WC-12wt% Co cermet thermal spray material was used for the thermal spray coating, and the thermal spray coating was formed on the surface of the cutting edge of a carbon steel blade having a tip angle of 60 ° as shown in FIG. After that, the cutting edge portion was machined into a sharp edge. As a result, in the edge portion e made of the sprayed coating, there is no loss of particles at the cutting edge portion, and the roundness R of this cutting edge is 50μ.
It was confirmed that it was sharply finished with m or less. In forming the sprayed coating, the flight speed of the sprayed particles was in the range of 250 to 280 m / sec, and the heat source was a burning flame of white kerosene and oxygen. Therefore, using this thermal spray coating cutting edge with a sharp angle, old newspaper was cut 10,000 times, but the sharpness did not deteriorate at all, and it was necessary to re-polish it like a metal cutting edge even after use. Without using it, it well withstood to use as a cutting edge and showed sufficient characteristics as a cutting tool.

[0030]

As described above, by using the carbide cermet sprayed particles produced by the granulation method, the flight speed of the particles can be controlled by the spraying method using the combustion flame of combustible gas as a heat source.
If the film is formed under the condition of 80 m / sec or more, a dense thermal spray coating with a strong collision energy and an excellent interparticle bonding force can be obtained. With such a sprayed coating, it is possible to finish it into an acute angle (R ≦ 50 μm) by machining.
Therefore, while the conventional carbide cermet thermal spray coating is used exclusively for surface modification as a high hardness, wear resistant coating, the present invention requires a precise and accurate machining angle. It is useful as a coating for edge reinforcement that takes advantage of the properties such as hardness, wear resistance, and non-wetting property and peeling property possessed by carbides in dies, dies, and blades that are used, and organic and inorganic sheets, It can be used as the cutting edge of film blades. As a result, the field of application of the carbide cermet thermal spray coating is further expanded, and it can greatly contribute to the improvement of productivity and quality in each industrial field.

[Brief description of drawings]

FIG. 1 is an electron micrograph of a carbide cermet thermal spray material, which is an agglomerated particle according to the present invention, produced by a granulation method.

FIG. 2 is an electron micrograph of a carbide cermet thermal spray material composed of conventional solid particles produced by a plasma melting method.

FIG. 3 is a schematic view of a state in which the surface of a carbide cermet sprayed coating is microscopically observed.

FIG. 4 is an explanatory diagram showing the relationship between the flight speed of thermal spray particles and the mutual spacing of the carbide particles on the surface of the coating film obtained.

FIG. 5 (a) is a shape condition and order of carbide cermet thermal spraying formed at a corner portion of a tool steel block,
(b) is a schematic diagram showing a state where the thermal spray coating of (a) is machined to an acute angle.

FIG. 6 is a schematic diagram of a carbide cermet sprayed coating formed on the surface of a base material (blade) having an acute angle of 60 °.

Claims (2)

(57) [Claims] 1. A surface of a steel substrate having a metal matrix in which carbide-based dispersed particles have an interval (λ) of 2.12 to 5.05.
dispersed so as to be in the range of μm was coated with the following carbide cermet sprayed coating formed by, and the roundness R of the corner portion formed by machining the portion of the sprayed coating is finished to 50μm or less A carbide cermet thermal spray coating member characterized by: The above-mentioned carbide cermet spray coating has a particle size of 0.1 to 3 μm.
m selected from WC, Cr ₃ C ₂ , B ₄ C, TiC, ZrC and Nb
Select from one or more carbides and Ni, Cr, Co and Mo
Charcoal consisting of one or more metals or their alloys
Compound cermet primary particles are formed under the interposition of a binder.
Aggregated particles that are agglomerated and agglomerated to a particle size of 5 to 60 μm
Carbide cermet thermal spray material composed of
It is formed by shooting 2. A temperature of 2000 ° C. to 30 on the surface of a steel base material.
By the thermal spraying method using a combustible gas combustion flame of 00 ℃ as a heat source,
By colliding the following carbide cermet thermal spraying materials at a flight speed of 180 m / sec or more, the carbide-based dispersed particles are dispersed in the metal matrix within the range of 2.12 to 5.05 μm between the mutual dispersion (λ) and the carbide cermet thermal spray coating. And a machining process such as grinding or polishing is performed on the portion of the thermal spray coating so that the roundness R of the corner portion is 50 μm or less, and a method for producing a carbide cermet thermal spray coating member. One or more kinds of carbides selected from WC, Cr ₃ C ₂ , B ₄ C, TiC, ZrC and Nb having a grain size of 0.1 to ₃ μm, and one or more kinds selected from Ni, Cr, Co and Mo A carbide cermet thermal spray material composed of agglomerated particles obtained by agglomerating primary particles of a carbide cermet composed of the above metal or an alloy thereof under a binder intervening to agglomerate to a particle size of 5 to 60 μm.