JPH0459967A - Method for reforming surface with laser beam - Google Patents

Abstract

PURPOSE:To partially reform the surface-layer part of a material to be reformed by forming a patterned thin film on the material surface and irradiating the entire surface with a laser beam to heat it. CONSTITUTION:A patterned thin film 3 is formed on the surface of a metallic material 1 to be reformed, and the entire surface of the material 1 is irradiated with a laser beam 7 from a laser 5. When a compd. having a higher absorptivity for the beam 7 than the material 1 is used for the thin layer 3, the lower part of the compd. is preferentially and selectively heated by the beam 7, the lower part of the layer 3 (oblique line part 4) is melted or vaporized, and the surface part is reformed. Consequently, when a metallic layer having a high laser beam reflectivity is used as the thin layer 3, the thin layer 3 at the lower part of the metallic layer is not heated so much, and an oblique line part 6 is preferentially and selectively heated and reformed. When the same metal is used ass the metal having a different absorptivity, the metals are patterned to change their surface roughness, and the absorptivities for the laser beam are different from each other.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Field of Application) The present invention aims to irradiate the surface of an object to be modified, such as a metal material or a ceramic material, with a laser to transform the surface layer of the object to be modified. The present invention relates to a laser surface modification method for partially modifying a surface.

(Conventional Technology) In recent years, there has been an increasing demand for products with higher functionality and higher added value, and with these demands, expectations for the development of new materials have also increased. In addition, surface modification of materials is particularly expected because new functions can be added without damaging the base material, and composite effects can be effectively obtained.

The following various methods have been proposed for modifying the surface of a material.

A coating layer is provided on the 0 surface by a physical vapor deposition method (evaporating a material and depositing it on the surface, such as vacuum evaporation, sputtering, or ion blasting).

■Provide a coating layer by chemical vapor deposition (thermal CVD, plasma CVD, etc., where deposition is deposited on the surface of a material mainly by reaction between gas phases).

■Provide a coating layer by coagulating and depositing a liquid material on the surface, such as by thermal spraying or overlaying.

■By infiltrating specific elements (carbon-carburizing, nitrogen-nitriding,
AI-aluminizing, ion implantation, etc.) changes the state of the surface layer.

■Changing the state of a material by heating it, etc.

Surface modification methods generally modify only the surface by heating, so the entire material is unlikely to be affected.

Therefore, only the surface properties can be improved without impairing the original material properties.

Among these, when a laser is used as a heating source, high-density energy can be obtained compared to other heat sources, so that not only surface modification can be easily performed, but also rapid heating and cooling can be performed easily.

Therefore, the possibility of surface modification involving non-equilibrium processes, which has been difficult until now, is considered possible.

In particular, carbon dioxide lasers (CO2 laser lasers) are expected to be capable of continuous high output oscillation. From these viewpoints, surface modification using lasers as a heat source has been in the spotlight in recent years.

By the way, another feature of lasers is ease of control. Laser light can be easily focused and reflected by lenses and mirrors, so it is possible to irradiate laser light to any location on the surface of the material to be modified. Taking advantage of this feature, it is also possible to partially modify the surface of the material.

However, this requires a complicated control system such as laser position control, and it is also necessary to change the control program depending on the application.

(Problems to be Solved by the Invention) For the reasons described above, a method for easily partially modifying the surface layer of a material has been desired.

In consideration of the above facts, the present invention aims to provide a laser surface modification method that can easily partially modify the surface layer of a material using a laser.

[Structure of the invention] (Means for solving the problem) In order to achieve the above object, the invention described in claim (1) provides the following:
A patterned thin layer is formed on the surface of the object to be modified, and the entire surface of the object on which the patterned thin layer is formed is irradiated with a laser to heat the surface layer of the object. It is characterized by the fact that it does not partially modify the material.

The invention as set forth in claim (2) is characterized in that the patterned thin layer is a compound having a high heat absorption rate for the laser.

The invention according to claim (3) is characterized in that the patterned thin layer is a material layer with high laser reflectivity.

The invention according to claim (4) is characterized in that the patterned thin layer is formed on the surface of the object to be modified in a rough state.

The invention described in claim (5) is characterized in that the entire surface of the object to be modified is irradiated with a laser in a gas atmosphere that forms a compound with the object to be modified.

The invention according to claim (6) is characterized in that after irradiating a laser beam onto a modification target on which a patterned thin layer has been formed, the modification target is rapidly cooled. Then, after forming a thin layer on the surface of the object to be modified by heating, and after forming a patterned compound layer with high heat absorption rate of the laser on the surface of this thin layer,
A laser surface modification method characterized by irradiating the entire surface with a laser to preferentially heat the thin layer at the bottom of the compound layer to form a thin compound layer.

The invention of claim (8) covers the above claims (1) to (
7) A surface-modified object whose surface has been modified by the laser surface modification method described above.

(Operation) According to the invention described in claim (1), a patterned thin layer is formed on the surface of the object to be modified.

This patterned thin layer has a pattern in which, for example, a portion to be modified and a portion not requiring modification are separated. With a thin layer formed on the surface of the object to be modified,
The entire surface of the object to be modified is irradiated with a laser. At this time, the laser may be a laser beam that has been diffused by an optical system or the like, and by scanning the laser over the surface of the object to be modified without detailed position control, the laser beam can be applied to the entire surface of the object to be modified. irradiate.

As a result, the surface of the object to be modified below the thin layer or the object to be modified on which the thin layer is not formed is modified. Therefore, the surface layer of the material can be easily partially modified using the racer.

According to the invention of claim (2), the patterned thin layer is a compound with high heat absorption rate, and after forming this compound on the surface of the object to be modified, a laser beam is applied to the entire surface of the object to be modified. irradiate.

The compound may be of any type as long as it has a higher laser absorption rate than the base metal, and examples include oxides, carbides, and nitrides.

When these compound layers are formed in advance on a surface that requires surface modification using methods such as sputtering, vacuum evaporation, thermal spraying, or powder coating, and then the entire surface is irradiated with a laser, the laser selectively affects only the areas on which the compound layer has been formed. The absorbed substance to be modified at the bottom of the compound layer is selectively heated and modified.

As a method of changing the laser absorption rate, in addition to forming a compound layer, metal layers having different absorption rates may be formed.

According to the invention of claim (3), the patterned thin layer is a material layer having a higher laser reflectance than the object to be modified, and after this material layer is formed on the surface of the object to be modified, the material layer is modified. Irradiates the entire object with a laser.

As a result, the object to be modified that is not covered with the material layer is selectively heated and modified.

According to the invention of claim (4), the patterned thin layer patterns the surface of the object to be modified to form a set. Laser irradiation is performed in this state. Since the reflectance of a surface in a rough state decreases, parts of the surface other than those in a rough state are selectively irradiated with a laser to be heated and modified.

According to the invention of claim (5), the entire surface is irradiated with a laser in a gas atmosphere that forms a compound with the object to be modified. The surface of the object to be modified other than the material layer or the rough surface is selectively heated and modified.

According to the invention of claim (6), after forming the patterned thin layer, it is irradiated with a laser and rapidly cooled.

After the patterned thin layer forms a layer with high laser absorption, the entire surface of the object to be modified is irradiated with the laser, and the object to be modified under this layer is preferentially heated and then rapidly cooled. .

As a result, the lower part of the layer with high laser absorption rate is preferentially heated and modified.

If the patterned thin layer is a layer with high laser reflectance, the entire surface of the object to be modified is irradiated with the laser, and this thin layer is used to remove objects other than the object covered by the thin layer. The surface of the material is selectively heated and modified.

The laser reflectance is low on the surface of the modified object that is formed in a patterned thin layer or in a rough state, and the surface of the modified target that is rough and has a high absorption rate is heated. After that, cool it down quickly.

As a result, the crude object to be modified is modified.

According to the invention of claim (7), after forming a patterned compound with high laser absorption rate, the entire surface is irradiated with a laser. The object to be modified at the bottom of the compound layer is preferentially heated and modified.

Moreover, the object modified by the inventions of claims (1) to (7) can be easily partially modified.

(Example) Next, embodiments of the present invention will be described with reference to the drawings.

First example A first embodiment will be described using FIG.

After forming a patterned thin layer 3 on the surface of the metal material 1 to be modified, the entire surface of the metal material 11 is irradiated with laser light 7 by the laser irradiation device 5 . In this case, the entire surface may be irradiated at once by diffusing the laser using an optical system or the like, or the entire surface may be irradiated by scanning the laser over the surface of the thin layer 3 under appropriate conditions.

Assuming that the patterned thin layer 3 is a compound layer having a higher absorption rate for the laser beam 7 than the metal material 1, the lower part of this compound is preferentially and selectively heated by the laser beam 7. This heating causes the lower part of the compound layer 3 (first
In the figure, the shaded area 4) is melted or evaporated, and the surface layer is modified.

Any type of compound may be used as long as it has a higher laser absorption rate than metal materials.

Examples include oxides, carbides, and nitrides.

The compound layer 3 may be formed in advance on a portion of the metal surface that requires surface modification by a method such as sputtering, vacuum evaporation, thermal spraying, or powder coating.

Furthermore, if the patterned thin layer 3 is a metal layer with different absorption coefficients, for example, a metal layer with high laser reflectivity,
The thin layer 3 below the metal layer is heated less, and the portion other than the metal, that is, the portion indicated by diagonal lines 6 in FIG. 1, is heated and modified preferentially and selectively.

In addition, in the case of the same metal with different absorption rates, by patterning and changing the surface roughness, taking advantage of the difference in the absorption rate of the relay, the surface can be partially roughened by Ar sputtering, sandblasting, etc. You can also do it.

After forming the patterned thin layer as described above,
By irradiating the entire surface with the laser, the metal is heated, melted, and evaporated in the areas where the laser is selectively absorbed, thereby partially changing the surface shape and modifying the metal.

Further, when the object to be modified is an alloy, selective evaporation occurs due to differences in vapor pressure of the constituent elements, resulting in a compositional change. Further, the base material may be modified by changing its structure by annealing or heating. Furthermore, in these modification methods, if laser irradiation is performed in an oxygen atmosphere such as the air, oxides can be formed partially, and if laser irradiation is performed in a nitrogen atmosphere, nitrides can be partially formed.

In addition, in laser surface modification, since only the surface is heated, it is likely to be rapidly cooled after modification, and a non-equilibrium may be formed and the intended equilibrium layer may not be formed. In this case, the object to be modified may be heated within a range that does not change the quality of the object.

Second Embodiment In the second embodiment, as shown in FIG. 2, after forming a patterned thin layer 9 on the surface of a metal material 11, which is an object to be modified, a metal material t,1 and a compound are formed. This is an example in which the entire surface of a metal material is irradiated with a laser in a gas atmosphere that forms a .

When the patterned thin layer is a highly reflective metal layer,
Third Embodiment In which the surface of the metal material is roughened to reduce its reflectance, and then the laser is irradiated in a gas atmosphere that forms a compound with the metal.The third embodiment is the same as the first embodiment until halfway through. Yes, but
The laser irradiation area is rapidly cooled after irradiation.

Another method for rapid cooling is to form a metal layer or compound layer on the surface of the metal material that has a higher laser reflectance than the metal material, and then irradiate the entire surface of the metal with a laser to remove the metal parts other than the compound layer. is preferentially heated and then rapidly cooled.

Alternatively, the surface roughness of the surface of the metal material 1 is made rougher than that of the metal to reduce the laser reflectance, and then the entire surface of the metal is irradiated with a laser, the rough metal portion is heated preferentially, and then rapidly cooled. do.

The rapid cooling method involves spraying cooling gas after laser irradiation,
The cooling structure may be made of metal material. By rapid cooling, it is possible to maintain the metal or alloy in a high-temperature liquid phase state and make it amorphous or fine-quality, thereby modifying the surface.

In this case, the type of alloy is an alloy whose component elements have a negative mixing enthalpy and an atomic dimension of 0.8 or less. Alternatively, an alloy containing iron, cobalt, or nickel as a main component and containing boron and silicon is desirable because it easily becomes amorphous or has a fine quality.

In addition, partial hardening can be achieved by hardening through crystal transformation, particularly through crystal transformation, by rapid cooling. after that,
It is also possible to change the surface shape by selectively removing only the non-hardened portions by colliding fine particles with Ar sputtering, sandblasting, etc.

Fourth Embodiment In the fourth embodiment, as shown in FIG.
After forming a metal or compound layer that easily forms a compound with the metal by heating on the surface of the metal layer, a compound layer having a higher laser absorption rate than the metal layer or compound layer is formed on the metal layer or compound layer. Alternatively, a metal layer 13 is formed. Thereafter, the entire surface is irradiated with a laser 7 to preferentially heat the metal portion below the compound layer to form a compound layer of the metal.

This method is similar to the first embodiment in terms of the method of partially modifying the surface, but a metal or compound layer that easily forms an alloy or compound with the object to be modified is formed in advance, and the layer is preferentially heated. An alloy or compound layer is selectively formed at the bottom of the exposed area to modify it.

A good combination is a metal whose enthalpy of formation with the metal element to be modified is a negative value or a compound whose free energy of formation is a negative value. For example, when the object to be modified is AI, metals such as Nb, Ti, St, or Fe oxide; when the object to be modified is Ni, Al5Ti, W, etc.; when the object to be modified is Ti, AI, Ni, etc. Examples include.

In addition, in each of the above embodiments, an example of a metal material was explained as an object to be modified, but the present invention is not limited to this, and the present invention can also be applied to non-metal materials such as ceramics.

Next, an experimental example of the laser surface modification method of the above embodiment will be explained.

First Experimental Example The surface of a Ti-6AI-4V plate was covered with a thin stainless steel plate having 10 island-shaped holes of 1 mm in diameter, and then a Ti02 layer of 500 nm thick was formed only in the hole portions by sputtering. Then output 1. A kW CO2 laser was scanned over a width of 20 mm in an oscillation mode (100 Hz) in an Ar gas atmosphere. As a result, only the lower part of the Tie 2 layer was melted and the surface was modified.

Second Experimental Example 100 holes with a diameter of 1 mm were made on the surface of a Ti-6AI-4V plate.
After covering the hole with a thin stainless steel plate, a 500 nm thick TlO2 layer was formed only on the hole portion by sputtering. After that, carbonated leather with an output of 1 kW was heated to N2 by the method shown in Figure 2.
Oscillation mode (1,00Hz
) was scanned over a width of 20 mm. As a result, T i
O, only the lower part of the formation layer is heated to form a TiN layer,
Surface modified.

Third Experimental Example After covering the surface of a carbonated steel plate with a thin stainless steel plate in stripes with a width of 2 mm, a paste made by kneading Fed powder with a particle size of 5 μm or less with a mixed solution of ethyl cellulose and terpineol was applied.
It was applied to a thickness of 0 μm or less. When the thin stainless steel plate was removed after heating at 150° C. for 10 minutes and drying, three Fed layers with a width of 2 mm were formed.

Next, the entire surface of the carbon steel plate was irradiated with a CO2 laser having an output of 1 kW in defocus mode.

Immediately after this, Ar gas was blown to cool it down. As a result, Fe
The carbon steel plate at the bottom of the O3 layer had a large volume that had undergone martensitic transformation, and the surface had been modified.

Fourth Experimental Example When fine alumina particles were sprayed onto a carbon steel plate prepared in the same manner as in the third experimental example, the surface-modified portions remained in the form of convex stripes.

Fifth Experimental Example After covering the surface of a 15 w% Cr4B-Ni alloy plate with a stainless steel plate in stripes with a width of 1 mm, Fe with a grain size of 5 μm or less was
When a paste obtained by kneading d3 powder with a mixture of ethyl cellulose and terpineol was applied to a thickness of 10 μm or less, a FeO3 layer with a width of 1 mm was formed. Then output 1
6 with a kW carbon dioxide racer in defocus mode
The alloy plate was irradiated in 001'orrAr. Immediately thereafter, Ar gas was blown to cool it down. The alloy part below the Fed3 coating layer became amorphous and surface-modified.

Sixth Experimental Example A volume of 5000 m of Tt was deposited on the surface of a Ni plate by vacuum deposition. Next, it was covered with a thin stainless steel plate in which 100 holes with a diameter of 1 mm were made, and a Tie layer of 500 nm was formed only on the hole portions by sputtering. Thereafter, as shown in FIG. 3, the alloy plate was irradiated with a carbon dioxide laser having an output of 1 kW in a defocus mode at 60 O TorrAr.

The lower part of the TiO2 layer is heated preferentially and a Ni-Ti compound is formed.

After the surface of the 7th experimental example Si3N, ceramic plate 2 was ff1- with a stainless steel plate with 1.0 holes with a diameter of 1 mm,
A Cu layer with a thickness of 500 nm was formed only in the holes by vacuum evaporation. Thereafter, as shown in FIG. 4, a carbon dioxide gas racer with an output of 1 kW was used in an oscillation mode (100 Hz) in an Ar atmosphere to scan over a width of 2 Q mm. As a result, only the lower part of the Cu formation layer was evaporated and the surface was modified.

Eighth Experimental Example 3iNi was deposited on the surface of a 3N4 ceramic plate by vacuum evaporation.
was deposited to a thickness of 300 nm. Next, it was covered with a thin stainless steel plate with 10 holes each having a diameter of 1 mm, and a Ti02 layer of 300 nm was formed only on the hole portions by sputtering. Then output 1. Scanning was performed over a width of 20 mm using a kW carbon dioxide laser.

As a result, the reduced Si and N1 were alloyed with the Si and N4 under the TiO2 layer, resulting in surface modification.

Ninth Experimental Example T1 was increased to 3 on the surface of an AIN ceramic plate by vacuum deposition.
00 nm was deposited. Next, after covering with a thin stainless steel plate with 10 holes of 1 mm in diameter, TiO2 was applied by sputtering.
A layer of 300 nm was formed only in the hole portion. Then output 1k
A W carbon dioxide laser was scanned over a width of 2 mm in an oscillation mode in a vacuum atmosphere. As a result, T
In the lower AIN where the iO2 layer was formed, the reduced Al and Ti were alloyed and the surface was modified.

10th Experimental Example Ni and T were deposited on the surface of an AIN ceramic plate by vacuum deposition.
300 nm of each layer was deposited. Next, it was covered with a thin stainless steel plate with 10 holes each having a diameter of 1 mm, and then a 300 nm TiO2 layer was formed only on the hole portions by sputtering. After that, a carbon dioxide laser with an output of 3 kW was applied to a 20 mm x 2 area using an integration mirror in a vacuum atmosphere.
An area of 0 mm was irradiated simultaneously. As a result, T i Q
In the two-layered lower AIN, reduced A1, Ni and Ti
was alloyed and surface modified.

11th Experimental Example By the same method as in the 10th Experimental Example above, Ti
After forming the O2 layer, an area of 20 mm x 20 mm was simultaneously irradiated with a carbon dioxide laser with an output of 3 kW in a vacuum atmosphere using an integration mirror. As a result, in the lower AIN where the TiO2 layer is formed, the reduced A
1, an alloy layer of Ni and Ti was formed. A substrate with high thermal conductivity, high withstand voltage, and high heat dissipation properties can be easily manufactured.

12th Experimental Example After covering the resin substrate surface with a thin stainless steel plate that had been hollowed out into a spiral shape, Fe-Co-B with a particle size of 5 μm or less was
A paste prepared by kneading -Si alloy powder with a mixed solution of ethyl cellulose and terpineol was applied to a thickness of 10 μm or less. After drying by heating at 150° C. for 10 minutes, the thin stainless steel plate was removed, and as shown in FIG. 6, an alloy powder layer 25 was formed in a spiral shape. Then the output 1k
Set the W carbon dioxide laser to defocus mode and set it to 60
The alloy layer was irradiated in 0 TorrAr. Immediately thereafter, Ar gas was blown to cool it down. The alloy in the coated alloy layer was amorphous and exhibited good magnetism.

13th Experimental Example After covering the surface of the cutting edge of a carbon steel tool with a thin stainless steel plate in the form of stripes with a width of 2 mm, a paste made by kneading Fe2O powder with a grain size of less than 5 μm with a mixture of ethyl cellulose and terpineol was applied to a thickness of less than 10 μm. did. When the thin stainless steel plate was removed after heating and drying at 150° C. for 10 minutes, a Fe2O3 layer with a width of 2 mm had been formed. Next,
The surface of this tool was irradiated with a carbon dioxide laser with an output of 1 kW in oscillation mode. Immediately thereafter, Ar gas was blown onto the glass to cool it. The carbon steel under the Fe2O3 coating layer had a large volume of martensitic transformation and was surface modified. When the hardness of the surface modified portion was measured using a Vickers hardness meter, it showed a high hardness of 400 Hv on average, and a good tool was obtained.

As described above, according to each of the above-mentioned Examples and Experimental Examples, there is no need for complicated control or a control program depending on the application, so it is possible to easily partially modify the surface layer of the object to be modified. I can do it.

[Effects of the Invention] As explained above, according to the laser surface modification method of the present invention, it is possible to easily partially modify the surface layer of materials such as metals and ceramics using a laser. Further, an excellent effect can be obtained in that various excellent parts can be provided.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram showing an apparatus for modifying the surface of an object to be modified by the laser surface modification method according to the present invention and a state in which the object is being modified, and Fig. 2 is a gas atmosphere. Fig. 3 is an explanatory diagram showing a state in which a laser is irradiated inside the object; Fig. 4 is an explanatory diagram showing the state in which the surface is irradiated with a laser after coating the alloy powder, Fig. 5 is a plan view showing a semiconductor circuit-shaped substrate, and Fig. 6 is a plan view showing the surface of the resinous substrate. It is. ], 11, ]7.18...Metal material (modification target) 3
．． 9.13...Compound layer 7...Laser light 13...Metal layer Fig. 1 Hidekazu Miyoshi, Patent Attorney tA Fig. 2 Fig. 5, Ar gas Fig. 4 Fig. 6

Claims (8)

[Claims] (1) A laser surface modification method of modifying the surface of the modification target by irradiating the surface of the modification target with a laser, the method comprising forming a patterned thin layer on the surface of the modification target. A laser surface modification method characterized in that the entire surface of the modification target on which the patterned thin layer is formed is irradiated with a laser to modify the surface layer of the modification target. (2) The method for modifying a laser surface according to claim (1), wherein the patterned thin layer is a compound having a high laser heat absorption rate. (3) The method for modifying a laser surface according to claim 1, wherein the patterned thin layer is a material layer having high laser reflectance. (4) Claim (1) characterized in that the patterned thin layer is formed with the surface of the object to be modified in a rough state.
The described laser surface modification method. (5) Laser surface modification according to claim (3) or claim (4), characterized in that the entire surface of the object to be modified is irradiated with a laser in a gas atmosphere that forms a compound with the object to be modified. Method. (6) Claim (2), (3) or (4), characterized in that after irradiating the object to be modified with a laser on which a patterned thin layer has been formed, the object to be modified is rapidly cooled. The described laser surface modification method. (7) After forming a thin layer on the surface of the object to be modified by heating, a patterned compound layer with high heat absorption rate of the laser is formed on the surface of this thin layer, and the entire surface is irradiated with the laser. ,
A laser surface modification method characterized by preferentially heating a thin layer at the bottom of a compound layer. (8) A surface-modified object whose surface has been modified by the laser surface modification method according to claims (1) to (7).