Specification for chemical conversion on aluminum and aluminum alloys
Some standard content:
Military Standard of the People's Republic of China for Electronic Industry FL0180
SJ20813\u20142002
Specification for chemical conversion on aluminum and aluminum alloys Issued on 2002-01-31
Implementation on 2002-05-01
Approved by the Ministry of Information Industry of the People's Republic of China 1 Scope
Military Standard of the People's Republic of China for Electronic Industry Specification for Chemical Conversion on Aluminum and Aluminum Alloys
Specification for chemical conversion on aluminum and aluminum alloysSJ20813\u20142002
1.1 Subject Content
This specification specifies the requirements and quality assurance provisions for chemical conversion films formed on the surface of aluminum and aluminum alloys by chemical reaction. 1.2 Scope of Application
This specification applies to the surface treatment of aluminum and aluminum alloy parts with high requirements for corrosion resistance in military electronic equipment. 1.3 Classification
Aluminum and aluminum alloy surface chemical conversion film is divided into the following two types: 1A Best corrosion protection chemical conversion film, used for surfaces to be painted or unpainted. 3
Anti-corrosion chemical conversion film, used for surfaces with low resistance requirements. 2 Reference documents
GB9792-88 Conversion film on metal materials Determination of film mass per unit area Gravimetric method GB/T17460--1998 Chemical conversion film Rinse and unrinsed chromate conversion film on aluminum and aluminum alloys GJB150.11-86 Environmental test methods for military equipment Salt spray test GJB179A-96 Counting sampling inspection procedures and tables GJB385A-96 Aliphatic polyurethane enamel and matching primer for aircraft skin 3 Requirements
3.1 Qualification appraisal
Products submitted in accordance with this specification should be qualified products or approved products. 3.2 Materials
The materials used to produce the chemical conversion coating shall be qualified materials that comply with the relevant standards. Added chemicals (such as fluorides added to maintain the effectiveness of the bath) shall not reduce the performance of the chemical conversion coating. 3.3 Cleaning
Before coating, the base metal shall be mechanically and chemically cleaned, and a continuous water film shall be formed on the surface after rinsing with water (see 6.4). It is prohibited to use iron-containing abrasives such as steel wool, iron oxide or steel wire for cleaning operations to prevent other metal particles from being embedded in the base metal and accelerating the corrosion of aluminum and aluminum alloys. For parts that have been treated with chemical conversion coatings, if there is local contamination, they should be cleaned without damaging the base metal and the chemical conversion coating. If the chemical conversion coating is damaged, the damaged area should be re-cleaned and treated, otherwise the part should be rejected. Ministry of Information Industry of the People's Republic of China Issued on January 31, 2002 rkAoNikAca
2002-05-01 Implementation
3.4 \u200b\u200bConstruction
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Unless otherwise specified, chemical conversion coating treatment shall be carried out by spraying, coating, or impregnation after mechanical processing and heat treatment operations such as forming, punching, welding, etc. are completed. Assemblies containing non-aluminum parts shall not be treated unless the non-aluminum parts are properly protected, otherwise the non-aluminum parts may be corroded, brittle or damaged during the treatment process. 3.5 Samples
Samples used for identification inspection and process control inspection are 76mm wide, 254mm long, and thicker than 0.5mm. Except as specified below, the treatment of samples shall be carried out together with the production of parts, including all pre-treatment and post-treatment (such as cleaning and rinsing). Unless otherwise specified in the contract or order (see 6.2), process control panels may be any of the following: a. One set of panels for each alloy (including heat treatment conditions) during the monthly process control period. b. 2024-T3 aluminum alloy panels for Type 1A conversion coatings and 6061-T6 aluminum alloy panels for Type 3 conversion coatings. If required, 2024-T3 panels may be substituted for 6061-T6 panels for Type 3 conversion coatings (see 6.8). When castings require treatment, the panels shall be cleaned by other appropriate means (see 3.3) and treated with the castings. 3.5.1 Preparation of Paint Adhesion Panels
Unless otherwise specified (see 6.2), the paint coating on panels used for paint adhesion testing shall be the paint system used in the production article or the paint system specified in 3.5.1.1.
3.5.1.1 Epoxy Primer Coating
The sample shall be sprayed with a layer of No. 8 epoxy polyamide primer that meets the requirements of GJB385A. Before testing in accordance with 4.7.2, the dry film thickness of the primer applied shall be 15 to 23 um and dried in accordance with the primer specifications. 3.6 Corrosion resistance
The samples treated with chemical conversion film should have the following anti-corrosion ability after the salt spray test (see Table 1): Table 1 Salt spray test time
Corrosion resistance
Identification inspection
Process control inspection
Chemical conversion film type
Sample alloy type
2024-T3, 7075-T6
6061-T6
2024-T3
6061-T6
Salt spray test time (h)
a. Each sample shall have no more than 5 isolated spots or depressions, with a diameter of no more than 0.8mm. The area within 6mm from the edge, mark or clamping point shall be excluded. Loss of color shall not be a reason for rejection. b. No more than 15 isolated spots or depressions with a diameter not greater than 0.8 mm on all five specimens. 3.7 Paint Adhesion
When the specimens are painted with the product paint system or the paint system specified in 3.5.1.1, no interlayer separation shall occur between the paint coating and the chemical conversion film or between the chemical conversion film and the base metal when tested in accordance with 4.7.2. If the chemical conversion film-treated parts are used directly without painting, the paint adhesion test may be omitted with the approval of the purchaser (see 6.2). 3.8 If the contact resistance of the type 3 chemical conversion coating is specified (see 6.2), a resistance test shall be carried out. The test method, number of tests and resistance value shall be specified separately by the purchaser. 3.9 Mass of Type 1A Chemical Conversion Coating
The mass of the type 1A chemical conversion coating on aluminum and aluminum alloy surfaces shall not be less than 0.431 g/m2. The test method is shown in 4.7.3. 3.10 Appearance
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The chemical conversion film shall be uniform, continuous, without powdery or loose parts; without cracks, scratches, cracks or other defects that are harmful to the protective performance and paint adhesion. Only with the special approval of the ordering party, the use of colorless chemical conversion film is allowed (see 6.2 and 6.6) 4 Quality Assurance Provisions
4.1 Inspection Responsibility
Unless otherwise specified in the contract or order, the contractor shall be responsible for completing all inspections specified in this specification. If necessary, the ordering party or the superior appraisal agency has the right to inspect any inspection item described in the specification. 4.1.1 Qualified Qualifications
All products must meet all requirements in Chapter 3 of this specification. The inspections specified in this specification shall become an integral part of the contractor's entire inspection system or quality program. If the contract includes inspection requirements not specified in this specification, the contractor shall also ensure that the products submitted for acceptance meet the contract requirements. Quality consistency sampling does not allow the submission of products that are known to be defective, nor can the ordering party be required to accept defective products.
4.2 Inspection categories
The inspection categories specified in this specification are as follows: a. Identification inspection.
b. Process control inspection.
c. Quality consistency inspection.
4.3 Identification inspection
Identification inspection must be carried out in a laboratory approved by the relevant competent authorities. The samples used should be taken from products produced using conventional production equipment and processes, and the samples used should be processed together with the products. 4.3.1 Inspection procedures
Samples and samples should be subjected to the inspections specified in Table 2. Table 2 Identification inspection
Inspection or test items
Appearance
Anti-undercutting ability
Paint adhesion
Contact resistance
(if required)
Chemical conversion film
Requirement clause
3.10
3.10
3.8 and
6.1.2.1
Method clause
4.7.4
4.7.4
4.7.1
4.7.1
4.7.2
4.7.2
6.1.2.1
4.7.3
Type and quantity of sample units to be inspected
5 (sample)
5 (sample)
5 (sample plate)
5 (sample plate)
2 (sample plate)
2 (sample plate)
1 (sample plate)
2 (sample plate)
4.3.2 Failure
If one or more technical indicators fail to meet the requirements, the appraisal inspection fails and the appraisal approval cannot be given. 4.3.3 Retention of appraisal qualification
The appraisal qualification retention period is 24 months. A report containing the following contents shall be submitted within 30 days after the end of each 24-month cycle.3
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If the report cannot be submitted on time, the product may lose its qualification for identification. In addition to periodic submission of inspection data. At any time within 24 months, if the inspection data show that the identified product cannot meet the requirements of this specification, the contractor shall immediately report to the identification agency.
&, Summary of the results of the completed product delivery inspection: b. Summary of the test results of the identification verification inspection. 4.4 Process Control Inspection
4.4.1 Process Control Inspection and Solution Analysis
To ensure continuous control of the treatment process, the test samples (see 3.5) shall be tested in accordance with Table 3. In addition to the test items in Table 3, all treatment solutions on the production line shall be chemically analyzed (see 6.9) to verify that the chemical concentration of the solution remains within the determined optimum performance range (see 4.4.1.1 and 4.4.2). Process control inspection can determine the chemical conversion coating that meets the requirements of this specification and approve the production equipment and process.
Table 3 Process Control Inspections
Inspection Items
Corrosion Protection
Paint Adhesion
(Wet Tape Method)wwW.bzxz.Net
Type
Number of Sample Plates
4.4.1.1 Frequency of Process Control Inspections and Solution Analysis Sample Preparation Clause
3.5.1 to 3.5.1.1
3.5.1 to 3.5.1.1
Requirement Clause
Test Method
Clause
4.7.1
4.7.1
4.7.2
4.7.2
The solution shall be analyzed once a week. The inspection items specified in Table 3 Process Control Inspections shall be tested once a month. In addition, the monthly test interval should not exceed 35 days. If the production is stopped for 35 days or longer, the process control inspection and solution analysis should be carried out when the production is resumed.
4.4.2 Solution Analysis Records
The operator shall record the formula of each treatment solution, the amount of chemical additives added to the solution and the history of all solution analyses performed. If specified in the contract, these records and test reports shall be provided to the purchaser. These records shall be kept for not less than 1 year after the completion of the contract or order.
4.4.3 Nonconformance
Nonconformance to the process control requirements in Table 3 shall be immediately stopped. The cause of the nonconformance shall be found and corrected before production is resumed. All products produced during the period when the process control sample failed will be judged as nonconforming unless the contractor can prove that the products can meet the requirements of this specification after re-inspection. Unless otherwise specified, parts that have been painted or assembled shall not be reworked.
4.5 Quality consistency inspection
4.5.1 Batch
Each batch consists of chemical conversion coating products of the same type, the same treatment method and submitted for acceptance at the same time. Unless otherwise specified, the number of a batch should not exceed the total number of parts or components produced in 1 day (see 6.2). 4.5.2 Sampling method and acceptance criteria
The samples for visual inspection shall be selected from the parts or components of each batch. Unless otherwise specified in the contract or order (see 6.2), the sampling method shall be carried out in accordance with GJB179A standard. The acceptance standard is general inspection level I, and the AQL value is 1.5. 4
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4.5.3 Appearance inspection
The samples for appearance inspection shall be selected in accordance with 3.5, and the results shall meet the requirements of 3.10. 4.5.4 Unqualified
If any situation does not meet the quality consistency requirements, the batch shall be rejected. 4.6 Repair
Unless otherwise specified by the ordering party, the mechanically damaged part of the chemical conversion film can be repaired. The repair area should not exceed 5% of the total area. If the area exceeds 5%, the repair can only be carried out after obtaining the approval of the ordering party. 4.7 Inspection method
4.7.1 Corrosion resistance test
Prepare five specimens for corrosion resistance test in accordance with Article 3.5. After the chemical conversion film treatment, the specimens should be dried at 16\u2103\uff5e38\u2103 for 24h, and then the salt test for the time specified in Article 3.6 should be carried out in accordance with GJB150.11. The appearance inspection should meet the requirements of Article 3.6. 4.7.2 Adhesion test
Prepare two specimens for adhesion test according to 3.5.1 and 3.5.1.1. Immerse the test specimens in distilled water for 24 hours, take them out and wipe them dry with a soft cloth. After 1 minute, use a stylus to draw two parallel lines with a spacing of 25 mm and through the coating. Immediately stick a 25 mm wide tape (the peel strength of the tape is at least 70 g/mm) on the coating and roll it 8 times with a rubber roller (diameter 80 mm, width 45 mm, hardness 70-80 IRHD). Peel off the tape quickly. The result should meet the requirements of 3.7. 4.7.3 Chemical conversion film quality test
The test method is shown in GB9792. The result should meet the requirements of 3.9. 4.7.4 Appearance
Appearance inspection should be carried out under normal light and visually inspected with the aid of a 5-fold magnification observer. The inspector should have normal vision or 1.0 corrected vision. The film layer should be checked for defects such as powdery or loose, cracked, scratched, cracked, etc. 5 Delivery Preparation
5.1 Packaging Requirements
When the parts treated with chemical conversion film are transported, stored and packaged, the physical properties and other properties of the chemical conversion film layer should be kept unchanged.
5.2 Delivery Method
The ordering party shall specify the specific packaging and transportation method or delivery method in the ordering documents. 6 Notes
6.1 Intended Use
6.1.1 Type 1A
Type 1A chemical conversion film is suitable for anti-corrosion treatment of surfaces that do not require paint coating, and is also suitable for improving the adhesion of aluminum and aluminum alloy surfaces to paint. This type of chemical conversion film can be used for structural components that do not require paint on the inner surface but require paint on the outer surface.
6.1.2 Type 3
Type 3 chemical conversion film is suitable for anti-corrosion treatment that requires low resistance characteristics in the electronics industry. The main difference between Type 1A and Type 3 is the thickness of the chemical conversion film. The thickness of the chemical conversion film varies with the electrical treatment time. The Type 3 chemical conversion film is thinner and is therefore more susceptible to corrosion than the Type 1A chemical conversion film. If paint is required around the electrical contact surface, the Type 3 chemical conversion film can also increase the adhesion of the paint on the aluminum and aluminum alloy surfaces. 5
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6.1.2.1 Resistance test
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Add an electrode with a pressure of 1.4MPa on the Type 3 chemical conversion film. The resistance should not be greater than 5m2. After 168h of salt spray test, the resistance should not be greater than 10mQ. The test equipment and circuit are shown in Figures 1 and 2 (other similar methods can also be used). The test electrode should be copper or copper-plated silver. The upper electrode area is 6.45cm2, and the lower electrode is slightly larger than the upper one. The 10 test areas on each sample are shown in Figure 3. In addition to the thickness of the chemical conversion film (see 6.1.2), the surface roughness of the sample and the flatness of the contact electrode have a greater impact on the resistance value.
6.1.2.1.1 Roughness of the sample surface
After the sample with a rough surface is pressed by the contact electrode, a lower resistance value will be measured due to the rupture of the chemical conversion film. This conclusion also applies to the contact electrode.
6.1.2.1.2 Flatness of the contact electrode
If the electrode surface is uneven, the actual contact area will be lower than the theoretical value, and a smaller contact area will result in a higher resistance value. The same conclusion also applies to the sample.
6.2 Contents of ordering documents
The following contents shall be stated in the contract or order: a. Name and number of this specification.
Type of chemical conversion film (see 1.3).
Application method (if there are restrictions, see 3.4). Colorless chemical conversion film (if required, see 3.10). d.
For Type 3 chemical conversion coating, whether to omit the paint adhesion test (see 3.7). For Type 3 chemical conversion coatings, is resistance testing required (see 3.8 and 6.1.2). f.
When resistance testing is required, the required resistance value, number of tests and test method shall be indicated (see 3.8 and 6.1.2). Alloy material and heat treatment requirements for the preparation of process control samples (if different from those specified in 3.5) h.
Applicable paint system (see 3.5.1.1). Batch quantity (if different from those specified, see 4.5.1). j
k. Sampling method (if different from those specified, see 4.5.2). 1. Delivery method.
6.3 Interchangeability
Various commercial solutions that meet this specification can provide chemical conversion coatings with equivalent performance. Their composition, processing procedures, application methods (spraying, brushing, dipping), and equipment required for the processing procedures may vary, but they are not interchangeable. For parts required to be treated in accordance with this specification, the part drawing shall indicate the type of chemical conversion coating (type 1A or type 3) and the paint system required to be applied. If the type of conversion coating is not specified, type 1A conversion coating is recommended. Pressure gauge
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Correction spring attack
Copper electrode
Figure 1 Schematic diagram of the film contact resistance measurement device
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Hydraulic pump
Note:
1. The roughness of the electrode contact surface
should not be greater than the surface after being polished with 000 metallographic
sandpaper.
2. After the upper and lower surfaces of the electrodes are in contact, the contact surface should meet the requirements of being opaque
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Figure 2 Contact resistance measurement circuit diagram
S: Sample
E: Electrode
M: Microohmmeter
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Test area
Figure 3 Sample surface resistance measurement area
Unit: mm
6.4 Cleaning agent
It is preferred to use a non-corrosive cleaning agent, especially for forged alloys. If a corrosive cleaning agent is used, pitting or pitting should be avoided. This is particularly important when using an alkaline cleaning agent, because aluminum tends to dissolve more than other alloying elements present (such as copper), so alkaline cleaning should be avoided. If an alkaline cleaner is used, it should be followed by an acid neutralization step. 6.5 Wear resistance
The wear resistance of chemical conversion coatings is relatively low. Only under appropriate operating conditions, chemical conversion coatings are quite durable, but severe wear or corrosion can easily remove chemical conversion coatings. Usually, careful operation does not cause significant damage to chemical conversion coatings. -niKAoNiiKAca
6.6 Appearance
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A simple way to evaluate chemical conversion coatings is to observe the amount of color, appearance consistency, smoothness and adhesion to the base metal (see 3.5). The appearance inspection is to ensure that the correct cleaning and treatment process is used to make the chemical conversion coating on the entire part have sufficient protective properties. The color of the chemical conversion coating can range from colorless, rainbow or brown. The following situations have color uniformity problems: a. When several alloys are treated with the same chemical conversion, the color of the chemical conversion coating on different alloys may be different. b. Due to the high impurity content and severe oxidation on the surfaces of aluminum welds and aluminum castings, the color of the chemical conversion film on these surfaces may be different from other surfaces.
C. Strong spots may be caused by the retention of chemical droplets when the parts are taken out of the treatment tank. A small amount of spots will not cause the performance of the chemical conversion film to decrease, but the parts should be washed with clean water quickly after treatment to make the spots as small as possible. Visual inspection cannot show whether the protective performance of the chemical conversion film is reduced due to contamination or overheating and drying damage. If a colorless chemical conversion film is required, inspection difficulties may occur because the appearance inspection cannot show the presence of the chemical conversion film. This chemical conversion film can be inspected using the simple method specified in Appendix A of GB/T17460. 6.7 Judgment of corrosion spots or pits
Usually, corrosion spots or pits usually show scattered or linear characteristics. 6.8 Sample (2024-T3)
Due to the high copper content, 2024-T3 aluminum alloy plate is more susceptible to salt spray than 6063-T6 aluminum alloy plate. 6.9 Analysis of the solution
The analysis of the solution shall include at least the concentration, pH value and overflow, the range of which shall be specified by the supplier. It should be noted that most conversion materials do not react fully with aluminum and aluminum alloy surfaces at low temperatures. In cold climates, the parts should be placed in a heated device for conversion coating treatment.
6.10 Paint Adhesion
The parts should be dried according to the supplier's recommendations before painting. When the parts treated with chemical conversion coating are stored for a long time before painting, they should be cleaned and dusted according to 3.3 to restore surface activity. Due to the large amount of solvent in the paint, too thick chemical conversion coating may cause problems such as reduced paint adhesion (such as blistering). 6.11 Effect of Temperature on Corrosion Protection
Unpainted chemical conversion coatings will lose their corrosion protection if the temperature is higher than 60\u00b0C during drying, assembly or maintenance. Generally, the corrosion protection decreases accordingly with increasing temperature and exposure time. This is due to dehydration of the coating and the formation of insoluble chromates inside.
Additional Notes:
This specification is proposed by the Electronics Process Standardization Technical Committee of the Ministry of Information Industry. This specification is under the jurisdiction of the Fourth Electronics Research Institute of the Ministry of Information Industry. This specification is drafted by the Fourteenth Electronics Research Institute of the Ministry of Information Industry. The main drafters of this specification are Zhu Yongming, Zhu Jianjun, Li Yuwen, and Zhang Zhude. Project code: B94004.5). The purpose of the appearance inspection is to ensure that the correct cleaning and treatment process is used so that the chemical conversion film on the entire part has sufficient protective performance. The color of the chemical conversion film can be colorless, rainbow or brown. The following situations have color uniformity problems: a. When several alloys are treated with the same chemical conversion, the color of the chemical conversion film of different alloys may be different. b. Due to the high impurity content and severe oxidation on the surface of aluminum welds and aluminum castings, the color of the chemical conversion film on these surfaces may be different from other surfaces.
C. Strong spots may be caused by the retention of chemical droplets when the parts are taken out of the treatment tank. A small amount of spots will not cause the performance of the chemical conversion film to decrease, but the parts should be cleaned with clean water quickly after treatment to make the spots as small as possible. The appearance inspection cannot show whether the protective performance of the chemical conversion film is reduced due to contamination or damage caused by overheating and drying. If a colorless chemical conversion film is required, there may be inspection difficulties because the appearance inspection cannot show the existence of the chemical conversion film. This chemical conversion film can be inspected using the simple method specified in Appendix A of GB/T17460. 6.7 Determination of Corrosion Spots or Depressions
Generally, corrosion spots or depressions usually show scattered or linear characteristics. 6.8 Sample (2024-T3)
Due to the high copper content, 2024-T3 aluminum alloy plates are more susceptible to salt spray than 6063-T6 aluminum alloy plates. 6.9 Analysis of Solutions
Analysis of solutions shall include at least concentration, pH value and overflow, and the range shall be specified by the supplier. It should be noted that most conversion materials do not react fully with aluminum and aluminum alloy surfaces at low temperatures. In cold climates, parts should be placed in a heated equipment for conversion coating treatment.
6.10 Paint Adhesion
Parts should be dried in accordance with the supplier's recommendations before painting. When parts treated with chemical conversion coatings are stored for a long time before painting, they should be cleaned to remove dust and restore surface activity in accordance with Section 3.3. Due to the large amount of solvents in the paint, too thick chemical conversion film may cause problems such as reduced paint adhesion (such as blistering). 6.11 Effect of temperature on anti-corrosion performance
When drying, assembling or maintaining, the unpainted chemical conversion film will lose its anti-corrosion performance if the temperature is higher than 60\u00b0C. Generally, with the increase of temperature and exposure time, the anti-corrosion performance decreases accordingly. This is due to the dehydration of the coating and the formation of insoluble chromates inside.
Additional remarks:
This specification is proposed by the Electronic Process Standardization Technical Committee of the Ministry of Information Industry. This specification is under the jurisdiction of the Fourth Institute of Electronics of the Ministry of Information Industry. This specification is drafted by the Fourteenth Institute of Electronics of the Ministry of Information Industry. The main drafters of this specification are: Zhu Yongming, Zhu Jianjun, Li Yuwen, Zhang Zhude. Project code: B94004.5). The purpose of the appearance inspection is to ensure that the correct cleaning and treatment process is used so that the chemical conversion film on the entire part has sufficient protective performance. The color of the chemical conversion film can be colorless, rainbow or brown. The following situations have color uniformity problems: a. When several alloys are treated with the same chemical conversion, the color of the chemical conversion film of different alloys may be different. b. Due to the high impurity content and severe oxidation on the surface of aluminum welds and aluminum castings, the color of the chemical conversion film on these surfaces may be different from other surfaces.
C. Strong spots may be caused by the retention of chemical droplets when the parts are taken out of the treatment tank. A small amount of spots will not cause the performance of the chemical conversion film to decrease, but the parts should be cleaned with clean water quickly after treatment to make the spots as small as possible. The appearance inspection cannot show whether the protective performance of the chemical conversion film is reduced due to contamination or damage caused by overheating and drying. If a colorless chemical conversion film is required, there may be inspection difficulties because the appearance inspection cannot show the existence of the chemical conversion film. This chemical conversion film can be inspected using the simple method specified in Appendix A of GB/T17460. 6.7 Determination of Corrosion Spots or Depressions
Generally, corrosion spots or depressions usually show scattered or linear characteristics. 6.8 Sample (2024-T3)
Due to the high copper content, 2024-T3 aluminum alloy plates are more susceptible to salt spray than 6063-T6 aluminum alloy plates. 6.9 Analysis of Solutions
Analysis of solutions shall include at least concentration, pH value and overflow, and the range shall be specified by the supplier. It should be noted that most conversion materials do not react fully with aluminum and aluminum alloy surfaces at low temperatures. In cold climates, parts should be placed in a heated equipment for conversion coating treatment.
6.10 Paint Adhesion
Parts should be dried in accordance with the supplier's recommendations before painting. When parts treated with chemical conversion coatings are stored for a long time before painting, they should be cleaned to remove dust and restore surface activity in accordance with Section 3.3. Due to the large amount of solvents in the paint, too thick chemical conversion film may cause problems such as reduced paint adhesion (such as blistering). 6.11 Effect of temperature on anti-corrosion performance
When drying, assembling or maintaining, the unpainted chemical conversion film will lose its anti-corrosion performance if the temperature is higher than 60\u00b0C. Generally, with the increase of temperature and exposure time, the anti-corrosion performance decreases accordingly. This is due to the dehydration of the coating and the formation of insoluble chromates inside.
Additional remarks:
This specification is proposed by the Electronic Process Standardization Technical Committee of the Ministry of Information Industry. This specification is under the jurisdiction of the Fourth Institute of Electronics of the Ministry of Information Industry. This specification is drafted by the Fourteenth Institute of Electronics of the Ministry of Information Industry. The main drafters of this specification are: Zhu Yongming, Zhu Jianjun, Li Yuwen, Zhang Zhude. Project code: B94004.
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