Metallic coatings on metallic substrates?Electrodeposited and chemically deposited coatings?Revies of methods available for testing adhesion
Some standard content:
ICS 25. 220. 20
National Standard of the People's Republic of China
GB/T 5270—2005/IS0 2819:1980 replaces GB/T5270:1985
Metallic coatings on metallic substrates
Deposited layers
Electrodeposited and chemicallydeposited coatings--Review of methods available for testing adhesion(ISO2819:1980,IDT)
Published on June 23, 2005
General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China Administration of Standardization of the People's Republic of China
Implemented on December 1, 2005
GB/T 5270—2005/IS0 2819:1980 This standard is a revision of ISO 270-1985. This standard adopts ISO 2819:1980E (English version of "Commentary on adhesion strength test methods of electrodeposited and chemically deposited metallic coatings on metal substrates") This standard was redrafted according to the editorial requirements of ISO 2819 (BT1.1). This standard makes the following modifications to ISO 2819: - Cancel the previous trademark of ISO 2819, supplement the table of contents: ... Replace "this international standard" with "this standard" - For convenience For the convenience of use, the Chinese standard which adopts the international standard is quoted. Appendix A of this standard is an informative appendix. This standard was proposed by China Machinery Industry Federation. This standard was issued by China Technical Committee for Standardization of Metallic and Non-metallic Coverings. This standard is mainly drafted by: Machinery Industry Surface Coating Product Quality Supervision and Inspection Center. The previous versions of the standard replaced by this standard are: G13/T52701985
1 Scope
CB/T 5270—2005/TS0 2819: 1980 Review of test methods for adhesion strength of electrodeposited and chemically deposited metallic coatings on metallic substrates
This standard describes several test methods for checking the adhesion strength of electrodeposited and chemically deposited coatings. They are limited to qualitative tests. Table 2 shows the applicability of each test to some commonly used metallic coatings. Most of these tests will damage the coating and the part, while some tests will only damage the coating. Even if the adhesion strength of the coating is acceptable in the non-destructive test of the test specimen, the test specimen should not be considered to be undamaged. For example, the friction and polishing test (see 2.1) may make the specimen unusable, and the thermal shock test (see 2.12) may produce unacceptable metallographic changes:
This standard does not describe some quantitative test methods for the adhesion strength of metallic coatings to the base metal that have been developed in various periods. Because such tests require special instruments and considerable skill in practice, this makes them unsuitable for quality control tests of production parts. However, some quantitative test methods may be useful for research and development. When specific methods for differential strength tests are specified in national standards for specific coatings, the methods described in this standard should be used in preference. Prior agreement between the supplier and the buyer should be obtained. 2 Test methods
2.1 Friction and polishing test
If the periphery of the plated part is polished, the deposit tends to harden and absorb friction heat. If the coating is thin, the coating will separate from the base metal in the area of poor adhesion under these test parts in the form of peeling. When the shape and size of the plated part permit, a smooth tool can be used to rub the plated surface of no more than 6 cm for about 15 seconds. A steel rod with a diameter of 6 mm and a smooth hemispherical end is a suitable rubbing tool. The pressure used during rubbing is to wipe off the coating in each stroke, but not to cut the coating. As the friction continues, the bubbles continue to increase, indicating that the adhesion strength of the coating is poor. If the mechanical properties of the coating are poor, the blister may break and peel from the substrate. This test should be limited to thinner deposits. 2.2 Steel ball friction polishing test
Steel ball polishing is often used for polishing. However, it can also be used to test the adhesion strength. Use a steel ball with a diameter of about 3 tmI and soap solution as a lubricant on a roller or vibrating polisher. When the adhesion strength of the coating is very poor, blistering may occur. This method is suitable for thinner deposits.
2.3 Shot peening test
Use gravity or compressed air to spray iron or steel balls on the surface being tested. The impact of the steel balls causes the deposit to deform. If the adhesion strength of the coating is poor, blistering will occur. In general, the shot peening intensity that causes the non-adherent coating to peel varies with the thickness of the coating. Thin coatings require less shot peening intensity than thick coatings. This test is carried out by connecting the nozzle to a container that emits iron or steel shot (about 0.75 mm in diameter) with a tube of 15 mm in length and 19 mm in inner diameter. Compressed air with a pressure of 0.07 MPa to 1.21 MPa is sent into the above device. The distance between the nozzle and the sample is 3 mm to 12 mm. This method is most suitable for checking the adhesion strength of electroplated layers with a thickness of 100 μm to 500 μm in electroplating products (see Appendix A). It uses a standard pneumatic box to spray steel shot. If the adhesion strength of the silver coating is poor, it will stretch and bubble. 2.4 Peel test This test is suitable for basically intact covering layers with a surface thickness of less than 125 μm. A tinned carbon copper strip or tinned brass strip of approximately 75 mm × 10 mm 0.5 mm GB/T 52702005/IS0 2819:1980
is bent into a right angle at 10 mm from one end, and the shorter side is flat welded to the covering layer. A load is applied to the side to be welded and perpendicular to the surface of the weld. If the adhesion strength of the covering is weaker than the weld, the covering will peel off from the substrate. If the adhesion strength of the covering is greater than the weld, fracture will occur at the weld or in the layer. This method is not widely used. C. The temperature reached during the welding operation may change the adhesion strength. In addition, a hardened synthetic resin adhesive with appropriate tensile strength can be used instead of welding to complete this test. Another test (tape test) is to use a fiber adhesive tape with an adhesion value of about 8N per 25mm width. The adhesive surface of the tape is applied to the cover to be tested using a fixed weight roller, and all air bubbles must be carefully eliminated. After a period of 10 seconds, a steady pulling force perpendicular to the surface of the cover is applied to the tape to pull the tape off. If the adhesion strength of the cover is high, the cover will not separate: batch test is especially used for adhesion test of the cover on the conductors and contacts of printed circuits. The test area of the plated conductor should be greater than 30 mm2.
2.5 File test
Saw off a piece of the workpiece with the cover, put it in a vise, and file it with a coarse grinding tool (only a row of saw teeth) in order to file off the cover. File along the direction from the base metal to the coating at an angle of about 45° to the mirror edge surface. The coating should not separate. This test is not suitable for very thin coatings and soft coatings such as zinc or cadmium. 2.6 Grinding and sawing test
Grind the edge of the plated sample with a grinding wheel along the cutting direction from the base metal to the deposited layer. If the adhesion strength of the coating is poor, the deposited layer will crack from the base metal. A hacksaw can be used instead of a grinder. It is important that the direction of the saw's sawing is so that the tilt applied is to separate the coating from the base metal. The grinding test is particularly effective for harder coatings such as nickel and chromium. 2.7 Chisel test
In general, the chisel test can be applied to thicker (greater than 125u) coatings. One test method is to place a sharp chisel on the back of the protruding part of the coating and give it a strong hammering. If the adhesion strength of the covering layer is high, the covering layer will crack or be cut off without affecting the bond between the base metal and the covering layer. Another "chisel test" is carried out in conjunction with the "steel engraving test". This test is to saw the specimen perpendicular to the covering layer. If the adhesion strength of the covering layer is not very good, it will break obviously. If no separation is found at the fracture, use a sharp chisel to chisel up the edge of the covering layer as much as possible. If the covering layer can be peeled off from the edge at a considerable distance, it means that its adhesion strength is poor or weak. Before each test, the chiseled edge should be sharpened. bZxz.net
Using a knife instead of a chisel can be used for testing thinner covering layers. The specimen can be gently tapped with or without a hammer. The chisel test is not suitable for soft-plated materials such as zinc-destroying saws.
2.8 Scribe and cross-cut test
Use a hardened steel scribe with a sharp edge of 30° to make two parallel lines about 2 mm apart. When making two parallel lines, sufficient pressure should be applied to cut through the coating and cut into the base metal in one stroke. If any part of the coating between the lines peels off from the base metal, the coating is considered to have failed this test. Another test is to scratch a square grid with a side length of 1m. At the same time, observe whether the coating in this area falls off from the base metal. 2.9 Bend test
The bend test is to bend and fold the product with the coating. The degree and characteristics of the deformation vary with the base metal, shape and characteristics of the coating and the relative thickness of the two layers.
The test is generally carried out by hand or clamps to remove the specimen as quickly as possible, first bending to one side and then to the other side until the specimen is broken. The speed and radius of the bend can be controlled by appropriate machinery. This test produces obvious shear stress between the base metal and the deposited layer. If the deposited layer is ductile, the shear stress is greatly reduced. Due to the plastic flow of the covering layer, the covering layer is not damaged even when the base metal has broken. The brittle deposited layer will crack. However, even so, this test can obtain some data on the adhesion strength. The fracture must be checked to see if the deposit has peeled off or if the deposit can be removed by force or chisel. Any signs of peeling, chipping or flaking are indicative of poor adhesion. GB/T5270-2005/ISO2819,1980
Specimens with either an inner or outer covering may fail. Although, in some cases, more data can be obtained by checking the inner edge of the bend, the properties of the covering are generally observed on the outside of the specimen. 2.10 Winding test
In this test, the specimen (strand is a strip or wire) is wound around a yoke. Each part of the test is standardized, namely: the length and width of the strip, the winding speed, the uniformity of the winding action and the self-diameter of the rod (shaft) around which the specimen is wound. Any signs of peeling, chipping or flaking are indicative of poor adhesion. Specimens with either an inner or outer covering may change. The properties of the coating are generally observed on the outside of the specimen, although in some cases more data may be obtained by examining the inside of the bend. 2.11 Tensile Test
This is applicable only to certain types of plated parts. A tensile stress is applied to the part until it breaks. The coating near the fracture will generally show some cracking. There is no obvious detachment of the coating from the base metal. 2.12 Heat Test
The adhesion strength of many deposits can be determined by heating the specimen with the coating and then cooling it suddenly. The principle of this test is that the thermal expansion coefficient between the coating and the base metal is different. Therefore, this test is applicable to cases where the expansion coefficient between the coating and the base metal is significantly different. The test is conducted by heating the specimen in a furnace for a sufficient time to reach the appropriate temperature listed in Table 1. This temperature is maintained within a tolerance of 10°C. For easily oxidized metals, heating should be carried out in an inert atmosphere, a reducing atmosphere, or in a suitable liquid. Then, the sample is placed in water or air temperature to cool rapidly. The recovered layer should not separate from the base metal, such as bubbling, flaking or delamination. It should be noted that heating generally improves the adhesion strength of the electrodeposited layer. Therefore, any test method that requires heating of the sample cannot help to indicate the adhesion strength of the electroplated state. Table 1 Hot-spot test temperature
Base metal
Zinc alloy
Pb and copper alloys
Aluminum and aluminum alloys
2.13 Deep-draw test
Chromium, nickel. Nickel: lead, copper-nickel
300℃
Layer metal
150℃
150℃
150℃
150℃
The most commonly used deep-draw tests for plated metal sheets are the Erichsen cup test and the Romanov flange cap test. They are used to deform the deposit and the base metal into a cup or rim cap shape by a plunger. In the Erickson test, a spherical sample plug with a diameter of 20 mm is pushed into the sample at a speed of 0.2 mm/s~-6 mm/s by a suitable hydraulic device until it reaches the required depth. The deposit with poor adhesion strength will peel off from the base metal in a sheet after a few millimeters of deformation. However, due to the penetration of the punch, even if the base metal has cracked, the well-attached deposit will not peel off. The Romanov test instrument is composed of a general punch press and an adjustable die used in conjunction with a rim cap. The flange diameter is 63.5mm and the cap diameter is 38mm. The depth should be adjusted from D:m1 to 12.7mm. Generally, the sample is tested until the fracture occurs. The undamaged part of the deep-drawn piece shows that the deep-drawing effect affects the structure of the deposit. These methods are particularly suitable for deposits of harder metals, such as nickel or tantalum.
1) In other cases, diffusion of the coating into the substrate may produce a brittle layer. Therefore, it is cracking that causes the peeling, not adhesion. 2) For details of this method, see GB.T6 Standard 3 Color and shape cup convex test. GB/T 5270-2005/1S0 2819:1980 In all cases, the results obtained must be carefully analyzed. Because it includes the ductility of the deposit and the base metal, 2.14 Cathode test
The plated test piece is used as a cathode in the liquid, and only nitrogen is precipitated at the cathode. When hydrogen is diffused through a certain coating, pressure is accumulated at any discontinuity between the coating and the base metal, causing bubbling of the coating. In a 5% sodium hydroxide (density 1.054 g/ml) solution, the sample is treated at a current density of 1 A/dm at 90℃ for 2 min. Small bubbles will form at the points with poor adhesion in the coating. If no bubbles occur after 15 minutes of coating, it can be considered that the adhesion of the coating is good. In addition, sulfuric acid (5% by weight) solution can be used at 60°C, current density of 10A/dm2, and after 5min~15 minutes, bubbles will occur in the layer with poor adhesion: the electrolytic test is limited to the coating that can be released through the cathode. This test is more suitable for nickel or chrome-chromium coatings with poor adhesion. Metal coatings such as lead, tin, zinc, copper or cadmium are not suitable for this test method. Applicable to adhesion strength test of various metal coatings Covering metal
Adhesion strength test
Friction polishing
Steel ball polishing
Brake separation?Braze welding method?
Peeling (adhesive method)
Bending and winding
Grinding and pot
Deep lead (Erickson)
Deep flange cap)
Steel shot peening
Extremely sharp
Method: Black dot·Indicates the test method applicable to the coating, pot
Inlaid ten roads
Gong·Jin alloy
A.1 Scope
Appendix A
(Informative Appendix)
GB/T 5270—2005/ISO 2819: 1980 Shot peening method to determine the adhesion strength of silver deposits (100 μm to 600 μm) This test method is suitable for evaluating the adhesion strength of silver wash deposits on steel with a thickness of between 1 μm and 60 μm. The test results are only qualitative. This method does not destroy the parts. The adhesion strength of the coating obtained by this method is satisfactory. A.2 References
GB/F4956 Measurement of the thickness of non-magnetic coatings on magnetic metal substrates Magnetic method A.3 Test equipment
A,3.1 Shot peening equipment
General compressed air or centrifugal shot peening equipment, A, 3.2 Steel shot
Steel balls with an average diameter of 0.4 mm and a hardness of not less than 350 HV30. Measure their size by the sieve method. And, they must be prepared to be equivalent to the sizes listed in Table A.1,
Screen weight mm
Shot control rate/%
A 10g steel shot sample must be taken out of the nozzle at least once a week for screening to check the size of the shot. A.4 Procedure
Before shot peening, all parts are first heated at 190℃ for 10 hours to eliminate stress and cover all surfaces that do not need to be shot peened.
Use non-destructive methods (e.g., according to GB/T4956) to measure the thickness of the silver coating, discard the parts with a silver coating thickness less than 0.10 mm or greater than 0.60 mm, and the difference between the maximum and minimum thickness is greater than 0.125 mm. All qualified parts are marked with the mark of the highest thickness, and the trial batches are grouped, among which the thickness difference of qualified products should not be less than 0.125 mm. The minimum shot peening intensity relative to the thickest measured thickness as shown in Figure A, 1,Shot peening of the silver-plated surface. Before each batch of treatment begins, the shot peening intensity must be adjusted according to the Alman A test (see A, 6). Alman A test samples should be measured at least once an hour to control the shot peening intensity. Remove the surface mask from the shot peened parts and visually inspect the shot peened surface. It should be fully blasted. If there are areas with waterfall blasting, it must be re-blasted. Check whether there are areas where steel shots are embedded in the coating. Blow away any remaining shots with air. A.5 Assessment
Carefully check the surface of the silver-plated layer with naked eyes. During the test, the silver-plated layer with poor adhesion strength will form bubbles or peel, or the coating itself will fall off
GB/T5270--2005/IS02819:1980
A.6 Adjustment of shot peening intensity
Use a carbon steel plate with a hardness of 400HV30~500HV30 and a thickness of 1.6mm, cut into a size of (76±0.2)mm×(19+0.1)mm and grind to a thickness of (1.30+0.02)mm (test sample A). When measured according to the following regulations, its flatness deviation should not exceed the arc height of 38m. Hold the test sample as shown in Figure A.2 and shot peen the exposed surface. After shot peening, remove the sample from the fixture and test the curvature of the unpeened surface with a depth gauge. Support the sample on four balls with a diameter of 1, forming a rectangle of 32 mm × 16 mm. Point the center pointer of the depth gauge at the center of the sample so that the sample pushes the depth gauge symmetrically. At a depth of more than 32 mm indicated by the depth gauge, measure the arc height of the center of the sample to an accuracy of 25 mm. Adjust the shot peening conditions as needed to obtain the required arc height. o.55
Figure A, 1
Maximum strength
Minimum nitrogen content
Silver thickness/ncm
Relationship between silver coating thickness and shot peening intensity
@4 mm~5 mm steel positioning needle
Steel 1Specific
Shot peening test sample
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