CN101775570B - A method for preparing large-area high-performance colored stainless steel by laser oxidation coloring - Google Patents

Abstract

The invention discloses a method for preparing large-area high-performance color stainless steel by laser oxidation coloring, relating to the field of material surface modification. The steps are as follows: 1) treating the stainless steel to be a certain size; 2) carrying out pre-treatment on the treated stainless steel; 3) carrying out large-area color treatment of laser oxidation after pre-treatment; and 4) preparing the large-area high-performance color stainless steel by simple after treatment to the stainless steel with oxidation coloring. The method uses optical-heat-chemical effect oflaser to generate oxide films with difference types and thicknesses, colors the surface of the stainless steel together by self color of the oxide films and interference effect of the films, and adopts a specially-made rotating laser head to prepare large-area curved or flat color stainless steel. The large-area color stainless steel prepared by the invention has more stable color film layer, rich color, good reproducibility, high hardness and good wear resistance, also has simple technique, easy operation and no pollution and is suitable for batch production on large scale.

Description

A method for preparing large-area high-performance colored stainless steel by laser oxidation coloring

technical field

The invention relates to the field of material surface modification, in particular to a method for preparing large-area high-performance colored stainless steel by laser oxidation and coloring.

Background technique

Stainless steel is an important application material in modern industry. Because of its excellent characteristics such as high strength, corrosion resistance, easy processing and glossy surface, it is widely used in aerospace, petrochemical, automobile, machinery, instrumentation, medicine, It has been widely used in energy and architectural decoration. With the progress of society, the rapid development of economy in all walks of life and the improvement of people's living standards, the single color of stainless steel can no longer meet the demand, and the color diversity of stainless steel has become inevitable. For this reason, people are actively researching coloring treatment technology, and strive to obtain stainless steel with rich colors, so as to expand its scope of use.

The research on colored stainless steel can be traced back to the first patent proposed by W.H.Hatfield and H.Green in 1927, but the patent did not enter the practical stage at that time. The process with real practical value is the acidic aqueous solution impregnation method proposed by the British European Co., Ltd. in 1972, also known as the acidic oxidation method, commonly known as the "Inco" method, which is mainly used for surface coloring of metal materials. The process is to immerse the polished stainless steel in the chromic anhydride-sulfuric acid mixed solution, and oxidize the surface of the stainless steel to form oxide films of different thicknesses as time changes. This transparent film can produce different colors due to light interference, so it is mainly used Used in the manufacture of colored stainless steel. However, when the composition and temperature of the solution change slightly, the thickness of the oxide film can not be obtained by controlling the time to control the oxide film color with good reproducibility. In order to effectively control the color of the coloring process, T.E.Evans et al. used a saturated calomel electrode as a reference electrode to measure the potential-time curve of the stainless steel sample during the coloring process, and the color with good reproducibility can be obtained.

The domestic production of colored stainless steel is currently in its infancy. According to relevant reports in domestic journals, many technical issues are still in the research stage, and most of the coloring methods use the Inco method. Although the Inco method is mature, the solution formula is simple, and it is widely used, due to the use of a large amount of CrO ₃ and H ₂ SO ₄ , hexavalent chromium is carcinogenic, and H ₂ SO ₄ is quite corrosive. Great harm to the environment. In addition, the existing surface coloring methods (including chemical coloring and electrochemical coloring) have certain defects, such as: (1) the wear resistance of the surface film is not strong enough; (2) the reaction temperature is relatively high, and the energy consumption is large. The color is easy to be uneven, and the acid mist is volatile; (3) three processes are required: chemical coloring, electrolytic film solidification, sealing, and (4) high power consumption, etc., which lead to the slow development of colored stainless steel production in my country and internationally , and the requirement of higher surface finish is also one of the main obstacles restricting its application. For various reasons, many surface finishing scholars have been looking for other research methods to color stainless steel, and it is also necessary to seek a new green technology for coloring stainless steel.

The anodic oxidation coloring disclosed in Chinese invention patent 200310103374.8, the preparation method is to put the pretreated metal or alloy into the anodic oxidation coloring solution, and color the oxide film layer with luster obtained by coloring for a certain period of time. However, this method can only produce a single coloring effect, and when the oxide films of different thicknesses are superimposed, the color will be uneven, which brings difficulties to the subsequent fixation and use of the oxide film.

Due to its good monochromaticity, directivity and coherence, laser has been widely used since its generation. Among them, laser oxidation technology has unique advantages such as clean and pollution-free, easy adjustment of process parameters, and simple post-processing, making it one of the most active branches in the field of oxidation in recent years. The invention uses the photo-thermal-chemical effect of laser to oxidize the surface of stainless steel to generate oxide films of different types and thicknesses, and the color of the stainless steel surface is colored through the interference of the color of the oxide itself and the film, and at the same time through the continuous laser process parameters Change the modulation of the energy of the spot and use a special rotating laser head to prepare large-area curved or flat colored stainless steel. The large-area colored stainless steel color film layer prepared by the invention is relatively stable, rich in color, good in reproducibility, high in hardness, good in wear resistance, simple in process, easy to operate, free of pollution, and suitable for large-scale batch production. At present, there is no relevant report on the preparation of large-area high-performance colored stainless steel by coloring stainless steel with continuous laser oxidation at home and abroad.

Contents of the invention

The purpose of the present invention is to overcome the deficiencies of the existing surface coloring technology and provide a method for preparing large-area high-performance colored stainless steel by laser oxidation coloring, which is characterized in that different types of stainless steel are oxidized on the surface of stainless steel by using the photo-thermal-chemical effect of laser light. With oxide films of different thicknesses, the surface of stainless steel is colored through the interference of the color of the oxide itself and the film. At the same time, through the change of continuous laser process parameters and the modulation of spot energy, a special rotating laser head is used to prepare large-area curved surfaces. or flat colored stainless steel. The method comprises the steps of:

1) Grind the wire-cut stainless steel with No. 280-1400 water abrasive paper until the roughness is less than Ra3.0μm, and then use metallographic sandpaper to finely grind the stainless steel after the above treatment until the roughness is less than Ra2.0μm, and then use alcohol on the Clean in ultrasonic at 20°C-60°C for 10min-25min, and dry quickly in hot air after taking it out;

2) Place the stainless steel treated in step 1) on the X-Y computer-controlled workbench, use different laser process parameters and workbench speeds to carry out laser oxidation and coloring large-area treatment, and use the photo-thermal-chemical action of the laser to obtain Oxide film on stainless steel surface in different colors;

3) The colored stainless steel treated in step 2) is cleaned with alcohol for 10min-25min in an ultrasonic wave at 20°C-60°C to obtain a clean, stable and high-performance large-area colored stainless steel.

The moving speed of the X-Y computer-controlled worktable is 2mm/s-20mm/s, the continuous laser power is 50W-500W, the laser rectangular spot size is 0.5mm×1mm-4mm×5mm, and the laser action time is 1s-5s. The defocus amount is 0.01mm-10mm, and the spot overlap rate is 10%-50%.

The laser is a continuous laser, the oxygen is transported coaxially, and the oxygen flow rate is 1L/min-3L/min, or the oxygen in the air is directly used.

The laser spot is a rectangular spot with uniform energy after modulation.

The surface oxide film is a single oxide film or an oxide composite film composed of various oxides. The presence of the composite film makes the surface of the stainless steel present more colorful colors.

The stainless steel is Fe-Cr-Ni series stainless steel material.

The colored stainless steel after laser oxidation and coloring only needs simple follow-up treatment without complex sealing treatment.

The method for preparing large-area high-performance colored stainless steel by laser oxidation coloring proposed by the present invention has the following advantages:

1) The method of the invention has simple process steps, is easy to operate, is green and pollution-free, has low cost, and is suitable for mass production;

2) The method of the present invention is to oxidize and color it below the melting point of stainless steel, without substantially changing the shape and size of the stainless steel;

3) The color stainless steel colored film layer that the inventive method makes is relatively stable, and color is rich, and reproducibility is good, and is firmly combined with matrix, and surface hardness, abrasion resistance etc. all have significantly improved;

4) The large-area colored stainless steel prepared by the method of the present invention has good decoration and beautification effects.

Detailed ways

The method for preparing large-area high-performance colored stainless steel by laser oxidation and coloring proposed by the present invention is based on the principle that different oxides (Fe, Fe, Oxides of Cr, Ni, Mn, etc.) and oxide films of different thicknesses, that is, the oxide film on the surface of stainless steel is a single oxide film or an oxide composite film composed of various oxides. The existence of the composite film makes the stainless steel surface appear more Colorful colors. The color of the stainless steel surface is formed by the color of the oxide formed after continuous laser treatment and the oxide film of different thickness through the interference of light. According to the principle of light interference, if the composition of the surface oxide film changes without changing the thickness of the oxide film, on the one hand, the color of the oxide itself will change, and on the other hand, its refractive index will also change, so that the interference The color of the back also changes. If the composition of the surface oxide film is not changed, but only the thickness of the oxide film is changed, different colors will also appear. The composition of the above oxide film and the thickness of the oxide film are all achieved by changing the laser process parameters (power, spot size, defocus, action time and spot overlap rate, etc.), while using a special rotating laser head Prepare large-area curved or flat colored stainless steel.

The following are embodiments of the invention:

Example 1:

1. Steps

1) Grind the wire-cut stainless steel on a pre-grinder to a roughness of Ra3.0μm with No. 280-1000 sandpaper, and then use metallographic sandpaper to finely grind the stainless steel after the above treatment to a roughness of Ra1.5μm, and then use alcohol Wash in ultrasonic wave at 20°C for 10 minutes, and dry quickly in hot air after taking it out;

2) Place the stainless steel treated in step 1) on the X-Y computer-controlled workbench, and carry out laser oxidation and coloring treatment in an environment with an oxygen flow rate of 1L/min: the X-Y computer-controlled workbench moving speed is 2mm/s, The continuous laser power is 50W, the laser rectangular spot size is 0.5mm×1mm, the laser action time is 1s, the defocusing distance is 0.01mm, and the spot overlap rate is 10%, and a blue-black oxide film on the stainless steel surface is obtained;

3) Wash the colored stainless steel treated in step 2) with alcohol in an ultrasonic wave at 20° C. for 10 minutes, take it out, and quickly dry it in hot air to obtain a clean and stable colored stainless steel.

2. Performance

1) Use the scratch method to measure the bonding performance of the colored film on the stainless steel surface and the substrate, according to the national standard GB5270-85.

2) Use the HXD-1000 microhardness tester to test the microhardness of the colored stainless steel surface, the experimental load is 200g, and the loading time is 15s. The surface microhardness test is to test five points in parallel and equidistant at different places on the colored stainless steel surface after laser oxidation and coloring treatment, and take the average value. The results are shown in Table 1.

Table 1 Size and properties of oxide film on stainless steel surface after laser oxidation coloring treatment

Example 2:

1. Steps

1) Grind the wire-cut stainless steel on a pre-grinding machine to a roughness of Ra2.0μm with 280-1200 sandpaper, and then use metallographic sandpaper to finely grind the stainless steel after the above treatment to a roughness of Ra1.0μm, and then use alcohol Wash in ultrasonic at 30°C for 15 minutes, and dry quickly in hot air after taking it out;

2) Place the stainless steel treated in step 1) on the X-Y computer-controlled workbench, and carry out laser oxidation and coloring treatment in an environment with an oxygen flow rate of 2L/min: the X-Y computer-controlled workbench moving speed is 5mm/s , the continuous laser power is 150W, the laser rectangular spot size is 1mm×1mm, the laser action time is 2s, the defocusing distance is 5mm, and the spot overlap rate is 20%, and a golden oxide film on the surface of stainless steel is obtained;

3) Wash the colored stainless steel treated in step 2) with alcohol for 15 minutes in an ultrasonic wave at 30°C, take it out and quickly dry it in hot air to obtain a clean, stable, and high-performance colored stainless steel.

2. Performance

The bonding performance of the stained film on the stainless steel surface and the substrate and the microhardness test method are the same as in Example 1, and the results are shown in Table 2.

Table 2 Size and properties of oxide film on stainless steel surface after laser oxidation coloring treatment

Example 3:

1. Steps

1) Grind the wire-cut stainless steel on a pre-grinding machine to a roughness of Ra1.5μm with sandpaper No. Wash in ultrasonic wave at 40°C for 20 minutes, and dry quickly in hot air after taking it out;

2) Place the stainless steel treated in step 1) on the X-Y computer-controlled workbench, and carry out laser oxidation and coloring treatment in an environment with an oxygen flow rate of 3L/min: the X-Y computer-controlled workbench moving speed is 10mm/s, The continuous laser power is 300W, the laser rectangular spot size is 1.5mm×2mm, the laser action time is 3s, the defocusing distance is 5mm, and the spot overlap rate is 30%, and a bright purple red stainless steel surface oxide film is obtained;

3) Wash the colored stainless steel treated in step 2) with alcohol for 20 minutes in an ultrasonic wave at 40°C, take it out, and quickly dry it in hot air to obtain a clean, stable, and high-performance colored stainless steel.

2. Performance

The bonding performance of the stained film on the stainless steel surface and the substrate and the microhardness test method are the same as in Example 1, and the results are shown in Table 3.

Table 3 Size and properties of oxide film on stainless steel surface after laser oxidation coloring treatment

Example 4:

1. Steps

1) Grind the wire-cut stainless steel on a pre-grinder to a roughness of Ra2.0μm with No. 280-1200 sandpaper, and then use metallographic sandpaper to finely grind the stainless steel after the above treatment to a roughness of Ra1.0μm, and then use distilled water , Alcohol cleaning in 50 ℃ ultrasonic wave for 25 minutes, after taking out, quickly dry in hot air;

2) Place the stainless steel treated in step 1) on the X-Y computer-controlled workbench, and carry out laser oxidation and coloring treatment in the air: the X-Y computer-controlled workbench moving speed is 15mm/s, and the continuous laser power is 400W. The size of the rectangular spot is 2mm×3mm, the laser action time is 4s, the defocusing distance is 5mm, and the overlap rate of the spot is 40%, and a light yellow oxide film on the surface of stainless steel is obtained;

3) The colored stainless steel treated in step 2) is cleaned in an ultrasonic wave at 50° C. for 25 minutes, and then quickly dried in hot air after being taken out to obtain a clean, stable, and high-performance colored stainless steel.

2. Performance

The bonding performance between the colored film on the stainless steel surface and the substrate and the microhardness test method are the same as in Example 1, and the results are shown in Table 4.

Table 4 Size and properties of oxide film on stainless steel surface after laser oxidation coloring treatment

Example 5:

1. Steps

1) Grind the wire-cut stainless steel on a pre-grinding machine to a roughness of Ra1.5μm with sandpaper No. Wash in ultrasonic wave at 60°C for 25 minutes, and dry quickly in hot air after taking it out;

2) Place the stainless steel treated in step 1) on the X-Y computer-controlled workbench, and carry out laser oxidation and coloring treatment in the air: the X-Y computer-controlled workbench moving speed is 20mm/s, and the continuous laser power is 500W. The size of the rectangular spot is 4mm×5mm, the laser action time is 5s, the defocusing distance is 10mm, and the overlap rate of the spot is 50%, and the oxidation film on the surface of stainless steel with purple and light green colors is obtained;

3) Wash the colored stainless steel treated in step 2) with alcohol for 25 minutes in an ultrasonic wave at 60°C, take it out and quickly dry it in hot air to obtain a clean, stable, and high-performance colored stainless steel.

2. Performance

The bonding performance of the stained film on the stainless steel surface and the substrate and the microhardness test method are the same as in Example 1, and the results are shown in Table 5.

Table 5 Size and properties of oxide film on stainless steel surface after laser oxidation coloring treatment

Claims (6)

1. A method for preparing large-area high-performance colored stainless steel by laser oxidation coloring, characterized in that, the photo-thermal-chemical effect of laser light is used to oxidize the surface of stainless steel to generate oxide films of different types and different thicknesses. The interference of color and thin film makes the surface of stainless steel colored together. At the same time, through the change of continuous laser process parameters and the modulation of spot energy, the rotating laser head is used to prepare large-area curved or flat colored stainless steel. The specific steps are as follows: 1) Grind the wire-cut stainless steel with No. 280-1400 water abrasive paper until the roughness is less than Ra3.0μm, and then use metallographic sandpaper to finely grind the stainless steel after the above treatment until the roughness is less than Ra2.0μm, and then use alcohol on the Clean in ultrasonic at 20°C-60°C for 10min-25min, and dry quickly in hot air after taking it out; 2) Place the stainless steel treated in step 1) on the X-Y computer-controlled workbench, use different laser process parameters and workbench moving speeds to carry out laser oxidation and coloring large-area treatment, and obtain the band through the photo-thermal-chemical action of the laser. There are oxide films on the surface of stainless steel with different colors; the moving speed of the X-Y computer-controlled worktable is 2mm/s-20mm/s, the continuous laser power is 50W-500W, and the laser rectangular spot size is 0.5mm×1mm-4mm× 5mm, laser action time 1s-5s, defocus amount 0.01mm-10mm, spot overlap rate 10%-50%; the laser is a continuous laser; 3) The colored stainless steel treated in step 2) is cleaned with alcohol for 10min-25min in an ultrasonic wave at 20°C-60°C to obtain a clean, stable and high-performance large-area colored stainless steel. 2. A method for preparing large-area high-performance colored stainless steel by laser oxidation and coloring according to claim 1, characterized in that the oxygen is transported coaxially, and the oxygen flow rate is 1L/min-3L/min, or directly in the air of oxygen. 3. A method for preparing large-area high-performance colored stainless steel by laser oxidation and coloring according to claim 1, wherein the laser spot is a rectangular spot with uniform energy after modulation. 4. A method for preparing large-area high-performance colored stainless steel by laser oxidation and coloring according to claim 1, wherein the surface oxide film is a single oxide film or an oxide composite composed of various oxides. film. 5. The method for preparing large-area high-performance colored stainless steel by laser oxidation and coloring according to claim 1, wherein said stainless steel is a Fe-Cr-Ni series stainless steel material. 6. A method for preparing large-area high-performance colored stainless steel by laser oxidation and coloring according to claim 1, characterized in that, the colored stainless steel after laser oxidation and coloring only needs simple post-treatment without complicated sealing deal with.