JPH0229741B2 - - Google Patents

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention is a method for forming a uniform surface-coated amorphous alloy layer of a predetermined composition on a metallic material by scanning a beam with high energy density. This relates to the method of providing the information.

[Prior Art] Originally, some of the properties required of metal materials are sufficient if only the surface layer of the metal material possesses them, and it is not necessarily necessary that the entire metal material possesses them. A lot.

Conventionally, various plating methods such as fusion plating, chemical plating, electroplating, diffusion permeation plating, vapor phase plating, and vacuum plating have been used to create metal surface coating layers that impart these properties to the surface layer of metal materials. method, melting method, and other methods are used.

However, with these methods, most of the metals that can be coated are single substances, and there are limits to the types of metals that can be coated.In many cases, the density of defects is high, and uniform coating is difficult to achieve, as well as the underlying metal. In many cases, the adhesion is insufficient. Therefore, it has been difficult to expect high strength, high wear resistance, high corrosion resistance, special surface activity, etc. from the surface coating layer formed by the conventional method.

Usually, alloys are crystallized in the solid state, but
If the alloy composition is limited and the alloy is rapidly solidified from a molten state, an amorphous structure similar to that in the liquid state, which does not have a crystalline structure, can be obtained even in the solid state. Such alloys are called amorphous alloys.

This amorphous alloy has excellent mechanical properties such as significantly higher strength, hardness, and wear resistance than conventional practical metal materials, and is not susceptible to radiation damage, and depending on its composition, It exhibits high corrosion resistance and special surface activity.

In the past, several proposals have been made to form an amorphous coating layer on a metal surface.
The idea can be seen in Publication No. 148752. this is,
The coating material is attached to the metal substrate and its surface is
After rapidly melting by scanning with a spot-shaped heating source having an energy density of 10 ⁴ Watt/cm ² or more, 10 ³ is brought into contact with a cooling medium arranged in an L-shape behind the scanning direction and the pitch direction. This is a method of rapid cooling at a cooling rate of ℃/second or higher.

[Problems to be Solved by the Invention] However, in the above-mentioned method, consideration is not taken to prevent the coating material, which has once become amorphous, from crystallizing due to heating of the adjacent portion. In other words, since the molten coating material is rapidly cooled by contact with a cooling medium at a high cooling rate of 10 ³ °C/sec or more to obtain an amorphous layer, in reality, rapid cooling is not possible. This is difficult and almost impractical.

The present invention is an amorphous alloy that covers the base metal as part of the composition without requiring special cooling means by controlling the amount of heat input, that is, this amorphous alloy is tightly adhered to the base metal. The object of the present invention is to provide a method for producing a continuous surface coating layer without defects.

[Means for Solving the Problems] In the method for creating a surface-coated amorphous alloy layer according to the present invention, a surface-coated amorphous alloy layer is formed by irradiating a high-energy density beam onto a metal layer stacked on a base metal surface. In the method for creating a crystalline alloy layer, the metal layer and the metal layer each have a predetermined composition such that the molten composition of the metal layer and a part of the surface layer of the base metal becomes a desired amorphous alloy composition. a step of preparing a base metal; and irradiating a beam with sufficient irradiation energy density to melt both the metal layer and a part of the surface layer of the base metal from above the metal layer stacked on the surface of the base metal. Irradiation is performed for a predetermined irradiation time, and the molten metal locally melted by the beam is rapidly solidified by heat conduction to the base metal, while the molten metal is
Obtaining a continuous band-shaped amorphous alloy layer of the amorphous alloy having the desired composition by performing a solidification operation continuously; A step of forming overlapping and adjacent band-shaped amorphous alloy layers by the same continuous melting and solidifying operation and repeating this, and the product of the irradiation time by the local irradiation and the irradiation energy density is 5J.・It is controlled to sec/cm ² or less.

More preferably, the irradiation energy density is
The local irradiation time is controlled to be 5000 J/cm ² or less and the irradiation time of the local irradiation to be 5×10 ⁻³ sec or less.

[Operation] To obtain the desired surface-coated amorphous alloy layer,
The surface layer, which has a predetermined composition in the molten state, must be rapidly cooled. At this point, the laser beam
By appropriately controlling the energy density and irradiation time, high energy density beams such as electron beams are suitable for locally melting any surface metal layer while avoiding temperature rise in the periphery. ing. In other words, since the molten volume determined by the melting area and penetration depth per unit time due to localized beam irradiation is sufficiently small relative to the base metal, the molten area is The rapid solidification of can be successfully carried out without the need for external contact cooling means.

The present inventors utilized the characteristics of such a high energy density beam to simultaneously melt, alloy, and homogenize the pre-applied or coated metal and the base metal from the surface to a predetermined thickness for a short period of time. , by repeating a process based on rapid cooling by dissipating heat to a large volume of surrounding solid metal so that the process overlaps with the previous process, so that a predetermined composition is obtained, Moreover, it has been discovered that it is possible to form a surface-coated amorphous alloy layer of a desired thickness in close contact with the base metal in the form of a continuous surface covering the base metal.

That is, the gist of the present invention is to provide a method for creating a surface-coated amorphous alloy layer by irradiating a metal layer stacked on a base metal surface with a high energy density beam, comprising: preparing the metal layer and the base metal each having a predetermined composition so that the molten composition with a part of the base metal surface layer becomes a desired amorphous alloy composition; and the surface of the base metal. A beam having an irradiation energy density sufficient to melt both the metal layer and a part of the base metal surface layer is irradiated from above the metal layer layered thereon for a predetermined irradiation time, and the beam is used to The locally melted molten metal is rapidly solidified by heat conduction to the base metal.
Obtaining a continuous band-shaped amorphous alloy layer of the amorphous alloy having the desired composition by performing a solidification operation continuously; A step of forming overlapping and adjacent band-shaped amorphous alloy layers by the same continuous melting and solidifying operation and repeating this, and the product of the irradiation time by the local irradiation and the irradiation energy density is 5J.・It is controlled to sec/cm ² or less.

More preferably, the irradiation energy density is
The local irradiation time is controlled to be 5000 J/cm ² or less and the irradiation time of the local irradiation to be 5×10 ⁻³ sec or less.

Hereinafter, the present invention will be described in detail. The conditions that the present invention must satisfy are as follows.

(a) The molten alloy has a composition that can be made amorphous. (b) The molten alloy is rapidly cooled and solidified to become amorphous. (c) There is no need for special external contact cooling means. (d) Aspects To form an amorphous coating layer having a shape, the present invention satisfies the following requirements.

(1) For example, a normal metal such as carbon steel is used as the base metal, and this base metal is also a part of the composition of the amorphous alloy. (2) The composition of the molten metal is changed to non-crystalline by rapid cooling and solidification. Limiting the average composition of the metal layer previously provided on the surface of the base metal so that it becomes a crystalline alloy (3) Using an external contact cooling member by dissipating heat by heat conduction to the surrounding large volume of the base metal. (4) For (3) above, a high energy density beam with a controlled irradiation energy density that melts the metal layer and a part of the underlying metal surface layer is locally irradiated from above the metal layer. (5) Furthermore, for the above (3), the irradiation area and molten volume per unit time of local irradiation must be sufficiently small relative to the base metal (6) Furthermore, for the above (3), , controlling the irradiation time of a locally irradiated high energy density beam (7) melting and locally alloying the metal layer previously provided on the surface of the base metal and a part of the surface layer of the base metal;
This local molten alloying is continued to form a continuous strip-shaped alloy layer.The operations to realize the above (6) and (7) are as follows:
Although it is possible to irradiate the beam in pulses for a short time and move the irradiation locations one after another, it is industrially preferable to move the beam continuously or to move the base metal material side of the irradiated object relative to each other. moving and as a result scanning the metal surface with the same beam,
By controlling this scanning time, it is possible to control the irradiation time to the local area.
The alloy layer can be formed into a continuous band-like alloy layer.

(8) Repeat the same continuous molten alloying operation by partially overlapping the obtained strip-shaped alloy layer in the longitudinal direction to expand the surface area of the surface coating alloy layer,
Finally, a planar surface coating alloy layer of a predetermined size is formed on the base metal material.By the way, when covering the surface of the base metal with a planar surface coating alloy layer of a certain size, it is necessary to If the surrounding solids are not overheated,
If the composition of the molten alloy is appropriate and the penetration depth and melting area (i.e., molten volume) of the molten alloy are limited to the extent that it can be rapidly cooled, quenching to amorphize the molten alloy can be performed. is sufficiently guaranteed by heat absorption by the surrounding base metal.
This is clear from the quenching principle of the single roll method, which is widely used to produce amorphous alloy plates by the liquid quenching method.

However, by controlling the irradiation energy density, the irradiation area per unit time is sufficiently small.
Even if the irradiation time is controlled, if the melting and quenching treatment is repeated so as to partially overlap the amorphous portion as described in (8) above, unnecessary excessive high energy density beam irradiation may result. This may lead to an increase in the melt volume (increase in the melt depth) and severe heating of the surrounding solid phase metal, in which case the rapidly solidified and amorphous metal is heated again and crystallizes at the boundary. It is to become Therefore, the following requirement (9) becomes necessary.

(9) Limiting the upper limit of the amount of heat input to the local melting zone However, since the local melting zone is extremely small,
Also, since the irradiation time for local irradiation is extremely short, the actual amount of heat input to the local melting zone cannot be measured strictly. Therefore, the amount of heat input is defined only by expressing it as the product of the irradiation energy density on the irradiation side and the irradiation time by local irradiation, not on the receiving side.

In the present invention, the amount of heat input expressed as the product of the irradiation energy density and the irradiation time by local irradiation is
This is to suppress it to 5 J·sec/cm ² or less, thereby stably obtaining an amorphous alloy layer.

In other words, the amount of heat input to the local melting zone is defined only by expressing it as the product of the irradiation energy density on the irradiation side and the irradiation time for local irradiation, not on the receiving side, but it depends on the type of high energy density beam and the irradiation time. Due to differences in absorption rates depending on the material composition and material condition of the metal layer and underlying metal, not all of the irradiation energy is converted into heat to the metal layer and underlying metal.

In other words, the amount of heat input expressed as the product of the irradiation energy density and the irradiation time due to local irradiation varies variously depending on the type of energy beam used, the composition of the base metal and the metal layer, etc.

For example, in the actual embodiment disclosed in this invention,
A generally applied energy beam, that is, a CO ₂ laser, is used to amorphize the molten alloy when the composition is appropriate and can easily become an amorphous alloy by rapid cooling, as described above. The heat input amount expressed as the product of this irradiation energy density and the irradiation time due to local irradiation is 0.188 (J・sec/cm ² ) and 0.105 (J.
sec/cm ² ).

As described later, each of these examples contains P in the alloy.
Contains. Thus, it is known that the infrared absorption rate of an alloy containing P in the alloy is about 50%. That is, the amount of heat actually used for melting is approximately 50/100 (=0.5) times the amount of heat that is the product of the irradiation time and energy density by local irradiation specified in each example. In other words,
The amount of heat actually used for melting is approximately 0.094
(J·sec/cm ² ) and 0.525 (J·sec/cm ² ).

On the other hand, it is known for its low infrared absorption rate.
The infrared absorption rate of metals such as Ni, Al, and Cu is approximately 2%.
It is known that In other words, when amorphousization is performed only with these metals with low infrared absorption, only about 2% of the product of local irradiation time and energy density becomes the amount of heat used for melting, which will be discussed later. It is understood that a greater amount of heat is required than in the example.

Therefore, assuming that an alloy with low infrared absorption rate is to be made amorphous, and considering the upper limit of the product of irradiation time and energy density by local irradiation, for example, the actual melting estimated from Example 1 Approximately 100/2 of the amount of heat used (0.094 (J・sec/cm ² ))
(=50) times. That is, 0.094 x 50 = 4.7 (J sec/cm ² ), and when making an alloy with low infrared absorption rate amorphous, the amount of heat input expressed as the product of the irradiation energy density and the irradiation time for local irradiation is Also, 5J・sec/cm ²
It is as below.

In addition, conditions are also stipulated for (3) above, ``performing rapid solidification without using an external contact cooling member by heat dissipation by heat conduction to the surrounding large volume base metal''. . That is, the conditions of the irradiation time and irradiation energy density for local irradiation are each limited to some extent.

For example, if the irradiation time for local irradiation is increased to heat and melt the area over a long period of time, the molten volume will become large and excessive, making it impossible to rapidly solidify from the peripheral area, and furthermore, it will be impossible to rapidly solidify from the surrounding area. The amorphous portion becomes crystallized when heated again. Therefore, the irradiation time for realistic local irradiation is 5
It is desirable that it be less than ×10 ^-3 .

Conversely, when irradiating a localized melting area with a high energy density beam in an extremely short period of time, in order to melt a predetermined area to a predetermined penetration depth,
Requires large energy sources that emit significantly high energy densities.

Further, when scanning with a beam having such a significantly high energy density, the scanning speed of the beam must be extremely fast in order to shorten the irradiation time as described above.

Therefore, a high power beam source and a high speed scanning mechanism are required, and in either case the apparatus is expensive and therefore impractical.

Therefore, considering commonly available laser equipment and scanning drive mechanisms, the irradiation energy density is
It is necessary to keep it below 5000J/ ^cm2 .

In the present invention, the reason why it is necessary to simultaneously melt and alloy the metal layer previously provided on the surface of the base metal and a part of the surface layer of the base metal is as follows.

That is, when only the metal layer previously provided on the surface of the base metal is melted without simultaneously melting and alloying the metal layer previously provided on the surface of the base metal and a part of the surface layer of the base metal. This is because the generated surface metal layer is likely to peel off from the base metal, making it difficult to create a surface coating metal layer that adheres to the base metal, and heat conduction from the molten metal to the base metal is insufficient. This is because it is difficult to rapidly cool the molten metal, making it difficult to create a surface-covering amorphous alloy layer.

The metal layer layered on the base metal surface in advance can be provided by various methods such as applying metal powder, plating, and thermal spraying. After the metal layer is sufficiently bonded to the base metal material by heating in various atmospheres including active gas, if a surface oxidation layer is formed by heating, it may be removed if necessary. As a result, when a high energy density beam is irradiated from above the metal layer, the surface coating layer is removed during or after the high energy density beam irradiation due to the bonding between the previously provided metal layer and the underlying metal material. It does not peel off from the underlying metal,
Heat conduction from the molten metal to the underlying metal is also ensured sufficiently.

Note that in order to make the alloy amorphous by melt quenching to create a surface-coated amorphous alloy layer, it is often necessary for the alloy to contain one or more metalloids. Therefore, the metal layer previously provided on the base metal surface according to the present invention may contain not only metals but also semimetals, and sometimes nonmetals. Furthermore, since these metalloids and nonmetals generally have high vapor pressure and are easily oxidized, some of the metalloids and nonmetals are lost through evaporation or oxidation during melting. If it is necessary to add metalloids and non-metals, it may be necessary to add an excess of metalloids and non-metals to the previously provided coating metal layer by estimating the amount lost through evaporation or oxidation.

On the other hand, irradiation with a high energy density beam in the atmosphere is usually performed while wiping an inert gas such as nitrogen gas onto the metal in order to prevent the irradiated metal from being oxidized. To prevent scattering of the metal layer components applied to the surface by spraying an inert gas or moving the metal, apply an appropriate liquid binder such as liquid paraffin to the underlying metal surface to keep it moderately moist. Alternatively, it is necessary to sprinkle the liquid on the base metal surface that has been wetted with the above liquid, and if necessary, dry or heat-treat the liquid to make the metal layer adhere to the base metal surface and prevent scattering. do. In addition, applying several layers of metal powder, applying multilayer coating using one or more of various plating methods, thermal spraying methods, and other methods, performing both metal coating and metal powder application, etc. is suitable for high energy density beam processing and presents no problems. Further, depending on the purpose, it is effective to repeat the application of metal powder or metal coating and high energy density beam treatment, or to repeatedly apply high energy density beam treatment to one surface layer.

Furthermore, the high energy density beam that can be used in the present invention is not limited to a laser beam or an electron beam, but any beam with an energy density that can melt a limited volume of metal surface in a short time can be used. Can be used in principle. Furthermore, irradiating the metal with a plurality of beams simultaneously is effective in shortening the processing time. In addition, in order to avoid temperature rise of the metal due to high energy density beam irradiation, it is also effective to cool the irradiated part with water or the like to achieve the present invention.

[Example] Next, the explanation of the present invention will be supplemented by Examples, and the effects will be shown.

Example 1 This is an example of coating a mild steel round bar with an amorphous Ni-Fe-Cr-P alloy layer.
-14Fe-14Cr-18P (however, in this example to create a surface-coated amorphous alloy layer, all values in formulas expressing material composition are atomic percentages), a mild steel with a diameter of 20 mm was used. The round bar was plated with Ni-25P to a thickness of 50 μm, and further plated with Cr to a thickness of 10 μm.

Rotate this at a rotation speed of 440 rpm according to Figure 1, and rotate it 70 μm in the direction parallel to the axis during one rotation.
moved continuously. During this rotation and movement, a 400W CO ₂ laser is used to reduce the beam diameter.
Irradiation was performed at a diameter of 100 μm. That is, the scanning speed in this case is 2π×440/60 (cm/sec) The area processed in 1 second is 2π×440/60×0.01 (cm ² ) The energy density is 400÷(2π×440/60×0.01) = 868.12 (J/cm ² ) Irradiation time for local irradiation is 0.01 ÷ (2π x 440/60) = 2.17 x 10 ^-4 (sec), and energy density x irradiation time is 868.12 x 2.17 x 10 ^-4 = It was 0.188 (J·sec/cm ² ).

In this example, P is contained in the alloy.
Thus, it is known that the infrared absorption rate of an alloy containing P in the alloy is about 50%.
That is, the amount of heat actually used for melting is approximately 0.5 times the amount of heat that is the product of the irradiation time and the energy density by local irradiation specified in this example.
It is estimated that the amount of heat actually used for melting was 0.188×0.5=0.094 (J·sec/cm ² ).

As a result, the Cr plating layer, the Ni-P plating layer, and the mild steel rod inside the plating layer were uniformly molten and alloyed to a depth of 10 μm, and then rapidly cooled.
An amorphous Ni-14Fe-14Cr-18P alloy layer with a thickness of 70 μm was formed in close contact with the underlying mild steel round bar. Since the surface coating layer is amorphous, it can be etched by nital etching (a) and oxalic acid electrolytic etching (b), which reveal a metal structure on crystalline carbon steel or stainless steel, as shown in Figures 3a and b. However, the metal structure of the crystal was not revealed. In addition, as shown in Figure 3c, d, e, and f, in amorphous alloys, Ni, Fe, Cr, P
was found to be evenly distributed. (however,
Figure 3 a and b are backscattered electron images, c is NiKα (n=
2), e is an X-ray image of CrKα (n=1), f is pKα (n=1), respectively) Example 2 An example of coating a mild steel plate with an amorphous Fe-Cr-P-C alloy layer. The amorphous Fe-
7Cr-12P-6C (However, in this example, in which a surface-coated amorphous alloy layer is produced, all values in the formula expressing the composition of the substance are atomic percent). White pig iron and phosphorus were used to coat the mild steel plate with the alloy. Ferric chloride and electrolytic chromium were mixed in a weight ratio of 5:4:1, then crushed and passed through a 300-mesh sieve to form a powder, which was then sprinkled onto a 10 mm thick mild steel plate wetted with liquid paraffin to prepare a surface for laser beam treatment. And so. 200W for this
A CO ₂ laser beam was irradiated with a beam diameter of 100 μm on the metal surface. Irradiation was started from one end of the mild steel plate in the x direction according to the irradiation method shown in Figure 2, and the beam was scanned in the x direction by relatively moving the mild steel plate in one direction in the x direction at a speed of 43.6 cm/sec. Ta. When the beam irradiation reached the other end of the mild steel plate, the mild steel plate was translated in the y direction by 70 μm, and then returned to the other side in the x direction at the same speed as above. That is, the scanning speed in this case is 43.6 (cm/sec) The area treated in 1 sec is 43.6×0.01 (cm ² /sec) The energy density is 200÷(43.6×0.01)=458.72 (J/cm ² ) Local irradiation The irradiation time was 0.01÷43.6=2.29×10 ⁻⁴ (sec), and the energy density×irradiation time was 458.72×2.29×10 ⁻⁴ =0.105 (J·sec/cm ² ).

Furthermore, since P is contained in the alloy in this example, the amount of heat actually used for melting in this example was 0.105×0.5=0.094 (J・sec/cm ² ). Guessed.

By repeating the above scanning, the entire surface of the mild steel plate was scanned with the laser beam without any gaps. As a result, amorphous Fe−8Cr−13P− was formed with an average thickness of about 50 μm.
We were able to coat the 7C alloy in close contact with the base.

[Effects of the Invention] As explained above, according to the present invention, by controlling the upper limit of the amount of heat input using the parameters on the irradiation side of the high-energy density beam, the base metal can be heated to a composition with no special cooling means. This method has the advantage that it is possible to obtain an amorphous alloy that partially covers the base metal, and to form this amorphous alloy into a continuous plane as a defect-free surface coating layer that adheres to the base metal.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a method of beam-processing a metal round bar, and FIG. 2 is a schematic diagram of a method of beam-processing a metal plate. Figure 3 shows Ni-P on carbon steel round rod.
These are cross-sectional views of a material that has been plated and Cr-plated and then subjected to laser beam processing according to the method of the present invention, in which a... cross-sectional backscattered electron image after nital etching, b... cross-sectional reflection after oxalic acid electrolytic etching. Electron image, c...NiKα X-ray image, d...FeKα X-ray image, e
...CrKα X-ray image, pKα X-ray image.

Claims (1)

[Claims] 1. A method for creating a surface-coated amorphous alloy layer by irradiating a metal layer stacked on a surface of a base metal with a high-energy density beam, comprising the steps of: a step of preparing the metal layer and the base metal, each having a predetermined composition so that the molten composition with a part of the metal layer becomes a desired amorphous alloy composition; A beam with an irradiation energy density sufficient to melt both the metal layer and a part of the underlying metal surface layer is irradiated from above the metal layer for a predetermined irradiation time, and the beam is used to locally melt the metal layer and a portion of the base metal surface layer. While rapidly solidifying the molten metal by heat conduction to the base metal, the molten metal
Obtaining a continuous band-shaped amorphous alloy layer of the amorphous alloy having the desired composition by performing a solidification operation continuously; A step of forming overlapping and adjacent band-shaped amorphous alloy layers by the same continuous melting and solidifying operation and repeating this, and the product of the irradiation time by the local irradiation and the irradiation energy density is 5J. - A method for creating a surface-coated amorphous alloy layer, which is characterized by controlling the layer to sec/cm ² or less. 2. The irradiation energy density is 5000 J/cm ² or less,
2. The method for producing a surface-coated amorphous alloy layer according to claim 1, wherein the irradiation time of the local irradiation is controlled to be 5×10 ⁻³ sec or less.