Process for chromium-silicon treatment of metal surfaces

Abstract

The application discloses a metal piece surface chromium-silicon treatment process and relates to the technical field of film coating processes.The application comprises the following steps: in step one, a detection device is used to inspect raw materials, the surface of the raw materials that pass the inspection is subjected to polishing and cleaning, and the cleaned raw materials are dried to complete the pretreatment of products to be coated; in step two, the products are placed into a vacuum coating machine to be coated, the vacuum coating machine is operated, the target material is set as Ti, main bombardment is carried out, the bombardment time is 70-210s, and a plurality of Ti layers are sputtered on the surface of the products to form a bottom layer; in step three, the target material is set as CrSi, acetylene is added as a reaction gas, a plurality of chromium-silicon composite layers are formed on the surface of the bottom layer, and the forming of the film layer of the products is completed; and in step four, the target material is set as Cr, a chromium metal layer is sputtered on the surface of the chromium-silicon layer, the products are taken out, a chemical vapor deposition method is used, the chromium metal layer is subjected to an oxidation reaction with oxygen or air at high temperature, a dense chromium oxide film is formed, and the coating is completed. The silicon material is added to ensure the insulation effect of the products.

Description

Technical Field

[0001] This invention relates to a coating process, and more specifically, to a chromium-silicon surface treatment process for metal parts. Background Technology

[0002] PVD (Polyvinyl Dioxide) is applied to stainless steel parts, which already possess excellent properties. PVD further enhances their appearance, significantly increasing their added value. However, customers are no longer satisfied with this and are demanding even higher performance from this process. While most metals on the market are conductive, and coating materials are also conductive, current practices sometimes require surface insulation treatment for specific situations.

[0003] Existing metal insulation treatments mostly employ painting and electrophoresis, but while these two processes can achieve insulation, the processing yield is low and the quality is unstable.

[0004] Therefore, a new solution is needed to address this problem. Summary of the Invention

[0005] To solve the above-mentioned technical problems, the present invention provides a chromium-silicon surface treatment process for metal parts.

[0006] The technical solution of this invention is:

[0007] A chromium-silicon surface treatment process for metal parts includes: Step 1, inspecting the material using testing equipment, cleaning and polishing the surface of the qualified material, and drying it after cleaning to complete the pretreatment of the product to be coated.

[0008] Step 2: Place the product into a vacuum coating machine for coating. Run the vacuum coating machine, set the target material to Ti, and perform main bombardment for 70-210 seconds to sputter several Ti layers onto the product surface to form the bottom layer.

[0009] Step 3: Set the target material to CrSi, add the reactive gas acetylene, and form several chromium-silicon composite layers on the bottom surface to complete the formation of the product film.

[0010] Step 4: Set the target material to Cr, and sputter a chromium metal layer on the surface of the chromium silicon layer. Remove the product and use chemical vapor deposition to oxidize the chromium metal layer with oxygen or air at high temperature to form a dense chromium oxide film, thus completing the coating of the entire product.

[0011] Step 5: After the coating is completed, an inspection is performed on the undercarriage. After the inspection is completed, the product is shipped.

[0012] The present invention is further configured such that, in step two, the heating temperature setting range inside the vacuum coating machine is 150-250℃, and the vacuum requirement is set at 1.0*10. (-2)Pa, the rotation speed range of its vacuum coating machine is set to 10-14Hz.

[0013] The invention is further configured such that, in step two, during the primary bombardment of the base layer, the number of Ti layers is set to three; the first bombardment time is 10-30 seconds; the second and third bombardment times are both 30-90 seconds; argon gas is added at a flow rate of 60-100 L / min during the first and second bombardments; and the argon gas flow rate is 130-170 L / min during the third bombardment. The pressure range for the three bombardments is 1*10. -1 -6.5*10 -1 Pa.

[0014] The present invention is further configured such that the duty cycle of the three bottom-layer bombardment bias power supply is 30-70%, the negative voltage range of the first and second bias power supplies is 250-350V, the negative voltage range of the third bias power supply is 100-200V, and the second and third bombardments both use cylindrical arc targets with target current ranges of 60-160A.

[0015] The invention is further configured such that, in step three, the number of chromium-silicon layers is set to ten, wherein the bombardment time for the first layer is 70 minutes, the bombardment time for the second layer is 3 minutes, the bombardment time for the third layer is 5 minutes, the bombardment time for the fourth layer is 20 minutes, the bombardment time for the fifth and sixth layers is 30 minutes each, the bombardment time for the seventh to ninth layers is 60 minutes each, the bombardment time for the tenth layer is 10 seconds, and the pressure range for the first layer is 2*10. -1 -6.5*10 -1 Pa, the pressure range for the remaining layers from the second to the ninth is 3*10 Pa. -1 -6.5*10 -1 Pa.

[0016] The present invention is further configured such that the argon flow rate during the first layer bombardment is 100-200 L / min, the argon flow rate during the second layer bombardment is 50-250 L / min, the argon flow rate during the third layer bombardment is 150-350 L / min, the argon flow rate during the fourth layer bombardment is 200-300 L / min, and the argon flow rate during the fifth to tenth layers bombardment is 150-350 L / min; the duty cycle of the bias power supply for the first layer bombardment is 30-50%, and the negative voltage range of its bias power supply is 60-100V; the duty cycle of the bias power supply for the second to tenth layers bombardment is 20-40%, and the negative voltage range of its bias power supply is 40-80V.

[0017] The invention is further configured such that the vacuum coating machine is equipped with six cylindrical targets. In step three, during the chromium-silicon layer formation, the first layer uses the second, third, fifth, and sixth cylindrical targets, each with a target current range of 21-31A; the second to ninth layers use the first to fourth cylindrical targets. In the second layer, the target current range of the first cylindrical target is 6-16A, the target current range of the second cylindrical target is 11.5-21.5A, the target current range of the third cylindrical target is 13-23A, and the target current range of the fourth cylindrical target is 10-20A; in the third to ninth layers, the target current range of the first cylindrical target is 13.5-23.5A, the target current range of the second cylindrical target is 11.5-21.5A, the target current range of the third cylindrical target is 13-23A, and the target current range of the third cylindrical target is 15-25A.

[0018] The beneficial technical effects of this invention are:

[0019] By adding a non-metallic silicon target to the original chromium metal material, a chromium-silicon high-resistivity film layer is formed, thereby effectively increasing the resistivity. The multi-layer design and controlled coating time further expand the resistivity to achieve an insulating effect and good stability. The outermost layer is formed by chemical vapor deposition, which allows the chromium metal layer to undergo an oxidation reaction with oxygen or air at high temperature, forming a dense chromium oxide film. Chromium oxide also has a good insulating effect, ensuring the overall insulation effect of the product surface. Attached Figure Description

[0020] Figure 1 This is a flowchart of the present invention. Detailed Implementation

[0021] In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, the specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings and examples. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0022] A chromium-silicon surface treatment process for metal parts, such as Figure 1 As shown, it includes the following steps:

[0023] Step 1: Use testing equipment to inspect the material, and then polish and clean the surface of the qualified material. After cleaning, dry it to complete the pretreatment of the product to be coated.

[0024] Step two: Place the product into the vacuum coating machine for coating. Set the heating temperature inside the vacuum coating machine to 200℃ and the vacuum requirement to 1.0*10. (-2)The vacuum coating machine's rotating frame speed is set to 12Hz. This rotation speed ensures more uniform target bombardment. The vacuum coating machine is operated with the target material set to Ti for primary bombardment, lasting 140 seconds, sputtering three Ti layers onto the product surface to form the base layer. The pressure of each of the three bombardments is controlled at 1*10. -1 Pa, and the duty cycle of the bias power supply for the three bombardments was 50% each. The second and third bombardments both used cylindrical arc targets with a target current of 110A each.

[0025] The first bombardment lasted 20 seconds, with an argon flow rate of 80 L / min and a negative voltage of 300 V for the bias power supply. The second bombardment lasted 60 seconds, with an argon flow rate of 80 L / min and a negative voltage of 300 V for the bias power supply. The third bombardment lasted 60 seconds, with an argon flow rate of 150 L / min and a negative voltage of 150 V for the bias power supply.

[0026] Step 3: Set the target material to CrSi and form ten chromium-silicon composite layers on the bottom surface. The first two layers are formed without reactant gas, creating chromium-silicon layers. The last eight layers are formed with acetylene as the reactant gas, creating CrSiC layers, thus completing the product film formation. The bombardment time is as follows: the first layer is bombarded for 70 minutes, the second for 3 minutes, the third for 5 minutes, the fourth for 20 minutes, the fifth and sixth for 30 minutes each, the seventh to ninth for 60 minutes each, and the tenth for 10 seconds. The pressure of the first layer is 2*10. -1 Pa, the pressure of the remaining layers from the second to the tenth layer is 3*10 Pa. -1 Pa;

[0027] The argon flow rate during the second bombardment is 150 L / min, the argon flow rate during the third bombardment is 250 L / min, the argon flow rate during the fourth bombardment is 250 L / min, and the argon flow rate during the fifth to tenth bombardments is 250 L / min. The duty cycle of the bias power supply for the first bombardment is 40%, and the negative voltage of the bias power supply is 80V. The duty cycle of the bias power supply for the second to tenth bombardments is 30%, and the negative voltage of the bias power supply is 60V.

[0028] During the molding of the chromium-silicon composite layer, the first layer uses the second, third, fifth, and sixth cylindrical targets, each with a target current of 26A; the second to ninth layers use the first to fourth cylindrical targets. In the second layer, the target current of the first cylindrical target is 11A, the second cylindrical target is 16.5A, the third cylindrical target is 18A, and the fourth cylindrical target is 15A; in the third to ninth layers, the target current of the first cylindrical target is 18.5A, the second cylindrical target is 16.5A, the third cylindrical target is 18A, and the third cylindrical target is 20A.

[0029] Step four: Set the target material to Cr, and sputter a chromium metal layer on the surface of the chromium-silicon layer. Remove the product and use chemical vapor deposition to allow the chromium metal layer to undergo an oxidation reaction with oxygen or air at high temperature to form a dense chromium oxide film, completing the coating of the entire product. Chromium oxide also has a good insulating effect, ensuring the insulation effect of the overall product surface.

[0030] Step 5: After the coating is completed, an inspection is performed on the undercarriage. After the inspection is completed, the product is shipped.

[0031] Example 2: The difference from Example 1 is that;

[0032] Step two, the pressure of the three bombardments at the bottom layer is controlled at 3*10. -1 Pa, the duty cycle of the bias power supply for the three bombardments was 60% for all three. The second and third bombardments used a cylindrical arc target with a target current of 150A for both. The argon flow rate for the first bombardment was 100L / min, and the negative voltage of the bias power supply for the first bombardment was set to 350V. The argon flow rate for the second bombardment was 100L / min, and the negative voltage of the bias power supply for the second bombardment was set to 350V. The argon flow rate for the third bombardment was 170L / min, and the negative voltage of the bias power supply for the third bombardment was set to 200V.

[0033] Step 3: Ten chromium-silicon composite layers are formed on the bottom surface. The first layer is left untreated to form a chromium-silicon layer, while the following nine layers are treated with acetylene to form a CrSiC layer. The pressure for each of the first to tenth layers is 6.5 x 10⁻⁶. -1 Pa; the argon flow rate during the second bombardment is 200 L / min, the argon flow rate during the third bombardment is 350 L / min, the argon flow rate during the fourth bombardment is 300 L / min, and the argon flow rate during the fifth to tenth bombardment is 350 L / min; the duty cycle of the bias power supply for the first bombardment is 50%, and the negative voltage of its bias power supply is 100 V; the duty cycle of the bias power supply for the second to tenth bombardment is 40%, and the negative voltage of its bias power supply is 80 V.

[0034] The remaining steps are the same as in Example 1.

[0035] Comparative Example 1: The difference between this example and Example 1 is that;

[0036] Step two: The Ti layer is one layer, the bombardment time is 1 minute, the argon flow rate is 120 L / min, and the pressure for both bombardments is 3.5 × 10⁻⁶. -1 Pa, the duty cycle of the bottom bombardment bias power supply is 50%, and the negative voltage of the bias power supply is 200V.

[0037] Step 3: The number of chromium-silicon composite layers is nine, and the pressure of the first layer is 2*10. -1 Pa, the pressure of the remaining layers from the second to the ninth is 6.5*10 Pa. -1 Pa; the argon flow rate during the second bombardment is 150 L / min, the argon flow rate during the third bombardment is 250 L / min, the argon flow rate during the fourth bombardment is 250 L / min, and the argon flow rate during the fifth to ninth bombardments is 250 L / min; the duty cycle of the bias power supply for the first bombardment is 40%, and the negative voltage of its bias power supply is 80 V; the duty cycle of the bias power supply for the second to ninth bombardments is 30%, and the negative voltage of its bias power supply is 60 V.

[0038] The surface of the product after the above coating is completed is inspected. The inspection items are as follows.

[0039] 1. Use a cross-cut adhesion tester to test the adhesion of the product surface;

[0040] Check that the appearance is normal before the test, with no discoloration, bubbles, cracks, peeling or other defects, and wipe the paint surface clean with a dust-free cloth; hold the cutting tool, keep the tool surface perpendicular to the test surface during scribing to prevent the cutting edge from lifting the coating, the scribing direction forms an angle of 30 to 60° with the sample, apply force uniformly to the cutting tool (the force shall be subject to that the cutting edge just penetrates the coating to reach the substrate), a guide grid device shall be used for a single-edged cutting tool, form 10×10 continuous small square grids on the coating with a uniform cutting speed. (When the film thickness is 0-60μm, the small grid is 1mm×1mm; when the film thickness is above 60μm, the small grid is 2mm×2mm). If 10×10 small grids cannot be scribed on the test area, scribe as many grids as possible; brush debris off the test area clean with a brush or a dust-free cloth, and make a judgment according to the qualification criteria; perform the following operations after judging as OK, and terminate the test if it is judged as NG; pull out a section of NI CH IBANCT405AP-24 tape at a uniform speed, remove the foremost section, and then cut off a tape of about 55mm. Place the center point of the tape above the grid, with the direction parallel to a group of cutting lines, then smooth the part of the tape above the grid area with a nail to ensure good contact between the tape and the coating (note that nails are not allowed to scratch the tape and the shell coating), and the length of the tape shall exceed the grid by at least 20mm; after applying the tape and standing for (90±30)s, hold the free end of the tape, pull it down rapidly within 0.5 to 1.0s at an angle as close to 60° as possible, and test the same position once; check the peeling condition of the paint coating; after the test, all surfaces (top, bottom, left, right) are required to be covered, a single sample shall include at least 2 test areas, and the test result is considered qualified when the cross-cut rating is greater than or equal to 5B;

[0041] 2. Boiled water cross-cut test

[0042] Check that the appearance is normal before the test, with no discoloration, bubbles, cracks, peeling or other defects, and wipe the surface clean with a dust-free cloth; heat purified water and keep it at 80°C; completely immerse the test sample in hot water, take it out after boiling in water for 30min, and let it stand at room temperature for 2 hours; check whether there is any abnormality on the surface of the sample coating, conduct an adhesion test, the product is considered qualified when the cross-cut rating is greater than or equal to 5B and the maximum diameter of new bubble points meets the requirements: when the diameter D of the bubble point is less than 0.1 (S < 0.008), it shall be ignored, but it is unqualified if there are a large number of such bubble points locally; it is unqualified when there are more than 2 bubble points with diameter 0.1 ≤ D ≤ 0.5; it is unqualified when the diameter D of the bubble point is greater than 0.5.

[0043] 3. Insulation impedance test

[0044] Before measurement, be sure to ensure that the equipment to be tested is in a power-off state to avoid the risk of electric shock; connect the test leads of the insulation resistance tester to the measuring point and the grounding terminal of the equipment to be tested respectively; ensure the connection is firm to avoid errors caused by poor contact; turn on the insulation resistance tester and set an appropriate range and measurement time. During the test, observe the reading on the display screen of the test instrument, and an impedance greater than or equal to 2MΩ is regarded as qualified.

[0045] 4. Perform high and low temperature test using a thermal shock testing chamber

[0046] Place the sample in the temperature chamber at room temperature, adjust the temperature of the temperature chamber to 80°C, keep it for 72 hours, then adjust the temperature to 20°C and keep it for 2 hours, then take out the product, and then use a cross-cut tester to conduct adhesion detection; it is qualified if the detection result meets the above requirements; then place the sample in the temperature chamber at room temperature, adjust the temperature of the temperature chamber to -40°C, keep it for 72 hours, then adjust the temperature to 20°C and keep it for 2 hours, then take out the product, and then use a cross-cut tester to conduct adhesion detection; it is qualified if the detection result meets the above cross-cut grade requirements, then the high and low temperature test is completed; and the temperature change rate of the above temperature chamber is 1°C / min in all cases.

[0047] 5. Perform salt spray test using a salt spray tester

[0048] Check that the appearance is free of abnormalities before the test, with no discoloration, bubbles, cracks, peeling, etc., and wipe the surface clean with a dust-free cloth; place the samples in the test chamber according to the typical configuration simulating market use (front exposure), and fix them on the fixture in the salt spray chamber (the product forms an angle of 60° to 75° with the horizontal plane); keep the samples independent from each other, so that the freely precipitated salt spray does not affect each other, and it should be avoided that corrosive substances fall from one surface treatment layer to another surface treatment layer; expose the surface treatment layer to the salt spray environment and keep spraying continuously; after the test is completed, remove the surface treatment layer from the test chamber and check the appearance of the sample; then gently rinse it with warm water not higher than 38°C, wipe it dry with a dust-free cloth, place it at room temperature for 2 hours, then check the sample and conduct adhesion test; it is qualified if the test result meets the above cross-cut grade requirements, then the salt spray test is completed;

[0049] 6. Pencil hardness

[0050] Check that the appearance has no abnormalities before the test, and there is no discoloration, bubbles, cracks, falling off, etc., and wipe the paint surface clean with a dust-free cloth; sharpen the pencil to expose the cylindrical lead core with a length of about 3mm (note: do not damage the lead core), hold the pencil so that it forms a 90° angle with the No. 400 sandpaper, and continuously draw circles on the sandpaper to rub the end face of the lead core until a lead core with a flat end face and a sharp edge is obtained; install the pencil on a special pencil hardness tester, the load applied to the pencil tip is 1kgf, the front end of the pencil lead contacts the surface to be tested, and the included angle between the pencil lead and the surface to be tested is 45°. Push the pencil to slide forward for a length of about 5mm at a speed of 0.5mm / s to 1mm / s (if the length of the sample is less than 5mm, the test shall be conducted on the sample surface as much as possible), draw a total of 5 lines at different positions, and rotate the pencil by about 60° after each drawing; after the test is completed, erase the black pencil scratches on the surface of the paint coating with an eraser and compare with the untested sample, and it is regarded as qualified if the test meets the requirement of 9H.

[0051]

[0052]

[0053] The above description is only the preferred embodiments of the present invention, and is not used to limit the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made without departing from the technical principle of the present invention, and these improvements and modifications shall also be regarded as the protection scope of the present invention.

Claims

1. A chromium-silicon surface treatment process for metal parts, characterized in that: include, Step 1: Use testing equipment to inspect the materials, and then polish and clean the surface of the qualified materials. After cleaning, dry them to complete the pretreatment of the products to be coated. Step 2: Place the product into a vacuum coating machine for coating. Run the vacuum coating machine, set the target material to Ti, and perform main bombardment for 70-210 seconds to sputter several Ti layers onto the product surface to form the bottom layer. Step 3: Set the target material to CrSi, add the reactive gas acetylene, and form several chromium-silicon composite layers on the bottom surface to complete the formation of the product film. Step 4: Set the target material to Cr, and sputter a chromium metal layer on the surface of the chromium silicon layer. Remove the product and use chemical vapor deposition to oxidize the chromium metal layer with oxygen or air at high temperature to form a dense chromium oxide film, thus completing the coating of the entire product. Step 5: After coating is completed, perform a hanging inspection; after the inspection is completed, ship the product. In step three, the number of chromium-silicon layers is set to ten. The bombardment time for the first layer is 70 minutes, the second layer for 3 minutes, the third layer for 5 minutes, the fourth layer for 20 minutes, the fifth and sixth layers for 30 minutes each, the seventh to ninth layers for 60 minutes each, and the tenth layer for 10 seconds. The pressure range for the first layer is 2. 10 -1 -6.5 10 -1 Pa, the pressure range for the remaining second to ninth layers is 3 Pa. 10 -1 -6.5 10 -1 Pa.

2. The chromium-silicon surface treatment process for metal parts according to claim 1, characterized in that: In step two, the heating temperature setting range inside the vacuum coating machine is 150-250℃, and the vacuum requirement is set at 1.

0. 10 （-2） Pa, the rotation speed range of its vacuum coating machine is set to 10-14Hz.

3. The chromium-silicon surface treatment process for metal parts according to claim 1, characterized in that: In step two, during the primary bombardment of the Ti layer, the number of Ti layers is set to three. The first bombardment time is 10-30 seconds, the second and third bombardments are both 30-90 seconds, and argon gas is added at a flow rate of 60-100 L / min during the first and second bombardments, and at a flow rate of 130-170 L / min during the third bombardment. The pressure range for the three bombardments is 1. 10 -1 -6.5 10 -1 Pa.

4. The chromium-silicon surface treatment process for metal parts according to claim 3, characterized in that: The duty cycle of the three bottom-layer bombardment bias power supply is 30-70%. The negative voltage range of the first and second bias power supplies is 250-350V, and the negative voltage range of the third bias power supply is 100-200V. The second and third bombardments both use cylindrical arc targets, and the target current range is 60-160A.

5. The chromium-silicon surface treatment process for metal parts according to claim 1, characterized in that: The argon flow rate range for the first bombardment is 100-200 L / min, for the second bombardment it is 50-250 L / min, for the third bombardment it is 150-350 L / min, for the fourth bombardment it is 200-300 L / min, and for the fifth to tenth bombardments it is 150-350 L / min. The duty cycle of the bias power supply for the first bombardment is 30-50%, and the negative voltage range of the bias power supply is 60-100V. The duty cycle of the bias power supply for the second to tenth bombardments is 20-40%, and the negative voltage range of the bias power supply is 40-80V.

6. The chromium-silicon surface treatment process for metal parts according to claim 5, characterized in that: The vacuum coating machine is equipped with six cylindrical targets. In step three, during the chromium-silicon layer formation, the first layer uses the second, third, fifth, and sixth cylindrical targets, each with a target current range of 21-31A. The second to ninth layers use the first to fourth cylindrical targets. In the second layer, the target current range of the first cylindrical target is 6-16A, the second cylindrical target is 11.5-21.5A, the third cylindrical target is 13-23A, and the fourth cylindrical target is 10-20A. In the third to ninth layers, the target current range of the first cylindrical target is 13.5-23.5A, the second cylindrical target is 11.5-21.5A, the third cylindrical target is 13-23A, and the third cylindrical target is 15-25A.

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