JPS6125779B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for forming an amorphous, rapidly solidifying surface coating layer on a metal surface.

In general, thermal spraying technology is widely used in general machinery, construction, shipbuilding, vehicles, chemical equipment, etc. to improve corrosion resistance and wear resistance.

Thermal spraying includes gas spraying, high frequency spraying, plasma spraying, etc., but these methods cannot eliminate pores in the sprayed coating.

In addition, to prevent the deterioration of corrosion resistance caused by these pores, it is possible to seal the pores by spraying plastic on top of the thermal sprayed coating, or by using a self-fusing alloy consisting of a nickel-based alloy or a cobalt-based alloy. An operation (fusing) is performed by heating and melting it using an acetylene flame, an electric furnace, etc. to close the pores.

However, the plastic film has low mechanical strength and is easily peeled off. Furthermore, when a fusing operation is performed using an acetylene flame, an electric furnace, etc., the temperature reaches a temperature of 1000° C. or higher, which tends to change the structure of the base material and cause deformation due to heat.

The object of the present invention is to compensate for the above-mentioned drawbacks and to provide a new method for forming a metal surface coating that combines special coating materials and processing conditions.

Recently, some types of alloys (combinations of transition metal elements and metalloid elements) have been rapidly solidified from a molten state at a cooling rate of 10 ⁵ to ^{10 7} °C/sec, resulting in a state similar to that of a liquid, with no long-period order in the atomic arrangement. This structure results in an amorphous state, and a material with excellent strength, corrosion resistance, magnetism, optical properties, etc. can be obtained, and a mass production method for this amorphous material is being established.

Here, the amorphous state refers to a state in which diffraction lines characteristic of crystals are not obtained by ordinary X-ray or electron beam diffraction, and a halo pattern similar to that in a liquid state is obtained.

However, in order to obtain the above-mentioned high cooling rate, the thickness of the product is usually about 0.1 mm or less, and the product shape is limited to filament, foil, ribbon, etc.

Therefore, the present inventor proposed a method of imparting the excellent corrosion resistance of the amorphous alloy to steel and metal products by attaching or alloying a coating material made of a combination of a transition metal element and a metalloid element to the surface, By rapidly melting and solidifying the surface again, a surface treatment method with excellent corrosion resistance was developed.
It has already been filed as No. 66834.

The present invention is based on the invention of JP-A No. ^52-66834 , and is based on the efficiency when using a spot-like high-energy heating source such as an argon arc, plasma arc, electron beam, or laser having an energy ^density of 10 4 Watt/cm 2 or more. The present invention provides a method for forming a surface coating.

That is, the present invention is a method of easily obtaining a continuous planar amorphous coating or rapidly solidifying coating using a spot-shaped high-energy heating source.

As shown in Fig. 1, the method of the present invention is to first coat the surface of a metal base material such as a steel plate with 5 to 30 (atomic)% of one or more of B, C, Si, P, Cr, Mo, W,
A coating material consisting of 0.2 to 30 (atomic)% of one or more of Mn, Ti, and A, with the balance being one or more of Fe, Ni, and Co, is applied to a coating material ranging from tens of micrometers to several tens of micrometers by thermal spraying or diffusion treatment. a step of depositing it to a thickness of 100 μm, then a step of scanning the surface with a spot-shaped high energy density heating source to rapidly melt it, and behind the spot-shaped heating source in the scanning direction and behind the pitch direction, 10 ³ °C /
It consists of a step of rapid solidification at a cooling rate of seconds or more.

Note that the cooling rate during solidification is 10 ³ °C/sec or more, and the energy density of the spot-shaped heating source is
10 ⁴ Watt/cm ² or more is used for Pd ₈₀ , which is currently the alloy that most easily becomes amorphous by rapid cooling from a liquid.
The critical cooling rate required for solidification of Si ₂₀ (atomic %) was experimentally determined to be higher than the above value;
Furthermore, it has been experimentally confirmed that a power density of 10 ⁴ Watt/cm ² or more is required to obtain such a cooling rate using a spot heating source and heat conduction to the base material.

Furthermore, the reason why the combination of components shown in the claims is required is based on the following empirical facts.

Formation of an amorphous metal largely depends on the type and amount of added elements.

5 to 30 of one or more metalloid elements
(atomic %) Those containing it tend to become amorphous.

When it becomes amorphous due to rapid solidification, the critical temperature at which it transitions from liquid to solid is called the vitrification temperature (Tg), and the melting temperature is called (Tm).
Increasing the cooling rate, lowering Tm by supercooling, and increasing Tg temperature by increasing viscosity are effective in making the material amorphous. For this purpose, a eutectic alloy component is suitable, and it is thought that the lowering of the solidification temperature due to this alloying has an effect on the formation of an amorphous material.

Therefore, in the present invention, we selected Fe, Co, and Ni among Group 8 transition elements from the viewpoint of use as base components, and B, C, and Si, which lower the melting point, form a eutectic alloy, and facilitate amorphization. , P, etc. are added in an amount of 5 to 30 (atomic) % of one or more metalloid elements such as Cr, Mo, W, Mn, Contains 0.2 to 30 (atomic)% of one or more of Ti, A, etc.

For example, 10% Cr is added to the Fe-P ₁₃ -C ₇ (atomic%) component.
(atomic %), corrosion resistance exceeding that of currently used stainless steel can be obtained.

Corrosion resistance is similarly improved by adding several percent or more of Mo and W. In addition, Mn improves hardness, and A and Ti are 0.2
Addition of ~1% improves roll separation and facilitates production.

In the present invention, such amorphous coating constituent elements are attached to the surface of a base material, and this is melted by heat from a spot-shaped high-density energy heating source to form an amorphous coating on the surface of the base material. However, it is difficult to obtain an amorphous coating simply by scanning the coated surface using a spot-like high energy density heating source with a spot diameter of several tens of micrometers to several millimeters. FIGS. 2 and 3 are shown to explain the reason. Third
The figure shows a coating material 2 of an amorphous component (a combination of transition metal elements and metalloid elements) attached in advance to the surface of a steel or metal base material 3, which is melted by a spot-shaped high energy density heating source, and the base material is melted. The bead portion 1, which has been rapidly solidified by heat conduction to the unmelted portion, is covered with an amorphous metal or a rapidly solidified structure. Further, FIG. 2 shows the case where a spot-shaped high-energy density heating source is moved and scanned by a distance h in the pitch direction in order to obtain a planar amorphous metal coating. In this case, the bead portion 4 scanned later becomes amorphous, but the bead portion 1, which was previously amorphous, is crystallized by heating due to the heat flow movement that occurs during this rapid solidification. That is, if a spot-like high energy density heating source is simply scanned, the resulting coating will crystallize.
In addition, 5 is the overlapping part of the first bead and the second bead,
6 is a heat affected zone.

Furthermore, FIGS. 4 and 5 show that the depth of amorphization changes by changing the energy or heating time of the spot-shaped high-energy density heating source. FIG. 5 shows a state in which the substrate 3 has become amorphous up to the boundary with the base material 3, and FIG.

Therefore, the present invention provides cooling medium that cools the back of the spot-shaped high-density energy density heating source in the scanning direction and the back of the pitch direction in an L-shape. However, it is characterized in that it prevents crystallization due to heating of adjacent parts.

6 to 10 show an example of an apparatus for carrying out the present invention. FIG. 6 shows the entire device, and FIG. 7 to 10 show the main parts thereof. In FIGS. 7 and 8, a spot-shaped high-density energy heating source 10 is placed behind the scanning direction using a cooling medium, and brought into direct contact with the molten metal surface to rapidly solidify the molten metal (amorphous film-forming metal). fulfill the role of The cooling medium 9 also serves to prevent the heat flow of the spot-like high-density energy heating source from raising the temperature of the treated coating, which has already become amorphous due to rapid solidification, to the crystallization temperature. The cooling media 8 and 9 may be constructed integrally as shown in FIG. 7, or may be constructed separately. In short, it is sufficient that they are arranged in an L-shape with respect to the beam 10' irradiated from the spot-shaped high-density energy heating source. The cooling media 8 and 9 are generally made of silver, copper, iron, or cemented carbide, which have good thermal conductivity, but depending on the crystal structure after solidification, ceramics may be used, or argon, helium, nitrogen, etc. A method of spraying gas or liquid may also be used. Further, by adjusting the material, refrigerant, pressure, etc. of the cooling medium 8, the cooling rate, coating thickness, crystal structure, etc. can be easily controlled. 11 is a cooling water passage for the cooling media 8 and 9; 12 is a pipe material to be coated; 13 is a final treatment section of the pipe material; and 13' is a treated section. Reference numeral 14 denotes a fixing base for the spot-shaped high-density energy heating source 10 (hereinafter referred to as the heating source), and the fixing base is configured to be movable in the pitch direction by a moving guide 15 and a moving screw 16. There is. 17 is a cylinder for pressing the cooling mediums 8 and 9; 18 is a rotary joint for supplying cooling water into the pipe material 12; 19 is a power source when a plasma torch is used as the heating source 10; 20 is the heating source 1.
Lead wire connecting 0 and power supply 19, 21 is pipe material 1
The rotary support part 2, 22, is a chuck that holds the pipe material 12.

Therefore, in order to carry out the coating treatment, one end of the pipe material 12, on which the amorphous coating element of the above composition has been adhered to the surface, is fixed with a chuck 22, and the other end is fixed with a rotary joint 1.
8, and rotated at a predetermined speed by a rotation mechanism (not shown) while flowing cooling water into the pipe material 12 from the rotary joint 18, and heat source 10 is applied to the surface.
A beam 10' having an energy density of 10 ⁴ Watt/cm ² or more is irradiated. As a result, the amorphous coating element melts to a predetermined thickness, and immediately after that, the heating source 1
It comes into contact with the cooling medium 8 located behind 0, and is rapidly cooled and solidified into an amorphous state. Since the pipe material 12 is rotating at a predetermined speed as described above, the beam 10' continuously scans the surface of the pipe material 12, and the surface of the pipe material 12 is coated with an amorphous material. When the pipe material 12 goes around once, the heating source 10
is moved in the pitch direction (pipe material 1
2 axis direction) and continue the work again. What is important at this time is that in the present invention, the heating source 1
Since the cooling body 9 is provided in the direction of the zero pitch, the treated part 13' adjacent to the part being coated comes into contact with the cooling body 9 and is cooled. Therefore, it is possible to prevent the treated area 13' from being affected by heat from the area currently being treated and rising to the crystallization temperature, so that by repeating the above action, the entire surface can be coated. can.

Next, the features of the present invention will be listed.

1. By using a spot-shaped heating source (heating with a high energy density of 10 ₄ Watt/cm ² or more), a coating film with excellent continuous and planar corrosion resistance and abrasion resistance can be obtained.

2. The crystal structure of the coating (amorphous, semi-crystalline, microcrystalline, etc.) can be changed by selectively using the heating source and the cooling medium arranged in an L-shape, which is one of the points of the present invention, and by adjusting the scanning speed. ), furthermore, the depth of the remelting layer can be easily adjusted.

3 If the coating material is attached to the steel or metal surface using the thermal spraying method, unlike the general thermal spraying-fusing process, it is possible to do so by cooling the base material without preheating it. A coating film with excellent corrosion resistance can be obtained without causing a change in the structure of the base material or applying thermal strain.

4. Few internal bubbles, inclusions (oxides), etc.
A uniform remelted coating layer is obtained.

This is an effect obtained by using a spot-shaped high energy density heating source and by applying pressure by using an L-shaped cooling medium, especially a solid material (steel, tool steel, ceramic, etc.) for the cooling body 8.

Furthermore, applying high frequency vibration to the cooling body 8 or the base material greatly reduces the number of bubbles in the remelted coating layer. (However, when applying high-frequency vibration, the adhesion of the coating material to the metal surface must be made strong by using plasma spraying, explosive thermal spraying, etc., or it is best to use thermal diffusion bonding to obtain a strong coating. (This is a key point.) Next, examples of the present invention will be shown.

Example 1 Using the apparatus shown in FIGS. 6 to 9, Ni ₇₅ -Si ₈ -B ₁₇ (atomic %) powder with a particle size of 200 to 300 mesh was deposited on the surface in advance to a thickness of 150 μm by plasma spraying. A thin-walled pipe (Material: SS41, diameter: 1 inch, length: 300 mm) was used as the processing material, and while the inside of this pipe was water-cooled, a 10 ⁵ Watt/cm ² argon plasma arc was used as a spot-shaped high-energy heating source to cool the pipe. The contact pressure between media 8 and 9 and the pipe surface is 2 Kg/cm ² , the distance between the pipe surface and the spot-shaped high-energy heating source is 3 mm, the pipe movement (rotation) speed is 1 m/sec, and the overlap rate is 10%.
Coating treatment was performed.

The obtained coating is coated by thermal spraying on the outermost surface of the coating layer.
Only 40 μm was melted and solidified, and the rest remained as sprayed. The hardness of this rapid melting part is Hv900
The material was extremely hard, and when the corrosion loss was measured after being immersed in H ₂ SO ₄ at 80° C. for 6 hours, the loss was 2.3%, indicating that it can be used as a corrosion-resistant material.
According to an X-ray diffraction photograph, the crystal structure of this treated part (rapidly melted and solidified part) had a halo characteristic of an amorphous structure.

Example 2 Coating work was carried out under the same conditions as in Example 1 except that copper warp was used as the cooling medium 8 and Ar gas was used as the cooling medium 9. The properties of the rapidly melting and solidifying film obtained were that the hardness value was 10% higher than in Example 1, and the corrosion resistance was lower by about 8%. In addition, in the X-ray diffraction photograph, in addition to a halo pattern characteristic of amorphous materials, rings characteristic of crystals were observed.

Example 3 The coating material on the pipe surface was Fe ₇₀ ―P ₁₃ ―C ₇ ―
The work was carried out under the same conditions as in Example 1 except that Cr ₁₀ (atomic %) was used. Compared to Example 1, the melting depth was smaller at 25 μm, but the corrosion resistance was 5%.
The corrosion loss after the 6-hour immersion test in H ₂ SO ₄ at 80° C. was less than 1%, which was a good result. In addition, a halo pattern was observed in the X-ray diffraction photograph.

[Brief explanation of the drawing]

Fig. 1 is a process diagram of the method of the present invention, Fig. 2 is an explanatory drawing showing problems when simply scanning using a spot heating source, and Figs. FIG. 6 is an explanatory diagram showing an apparatus for carrying out the present invention, FIG. 7 is a side view showing the main parts thereof, FIG. 8 is a front view, and FIG. 9 is a perspective view. be. DESCRIPTION OF SYMBOLS 1...Bead part, 2...Coating material, 3...Base material, 4...Bead part, 5...Bead overlap part, 6
... Heat affected zone, 7 ... Alloy diffusion zone, 8, 9 ... Cooling medium, 10 ... Heat source, 11 ... Cooling water passage,
12...Pipe, 13...Pipe unprocessed part, 14
...Heating source fixing table, 15...Fixing table moving guide,
16...screw, 17...pressing cylinder, 18
...Rotary joint, 19...Power source, 20...Lead wire, 21...Rotary support, 22...Chick.

Claims (1)

[Claims] 1. A surface coating method in which a coating material is attached to the surface of a metal material, rapidly heated to a temperature equal to or higher than the melting point of the coating material, and then rapidly cooled immediately after melting, B.
One or more types of C, Si, P 5 to 30 (atoms)
%, 0.2 to 30 (atomic)% of one or more of Cr, Mo, W, Mn, Ti, A, the balance being Fe, Ni, Co
A coating material consisting of one or more of the following is adhered to the surface of a metal base material, and the surface is rapidly melted by scanning with a spot-shaped heating source having an energy density of 10 ⁴ Watt/cm ² or more. A cooling medium placed in an L-shape behind the heating source in the scanning direction and in the pitch direction performs rapid cooling at a cooling rate of 10 ³ °C/sec or more, and forms an amorphous film of any thickness on the surface of the metal substrate. A method for forming a surface coating on a metal, the method comprising forming a molten solidified layer.