Anodizing of aluminum and aluminium alloys-Measurmeent of mean specific adrasion resistance of anodic oxidation coatings with an adrasive jet test apparatus
Some standard content:
National Standard of the People's Republic of China
Anodizing of aluminium and aluminium alloys---Measurement of mcanspecific adrasion resistance of anodic oxidation coatingswith an adrasive jct test apparatusGB/T 12967.1.-- 91
This standard is equivalent to the international standard ISO8252-1987 "Measurement of mcanspecific adrasion resistance of anodic oxidation coatingswith an adrasive jct test apparatus for anodic oxidation of aluminium and aluminium alloys".
The wear resistance of anodic oxidation film can reflect the potential ability of the oxide film to resist friction and wear. It is an important quality indicator of anodic oxidation film.
1 Subject content and scope of application
This standard specifies a test method for measuring the average wear resistance of anodic oxidation film of aluminium and aluminium alloys with an adrasive jct test apparatus and comparing it with the wear resistance of standard specimens and agreed reference specimens. This standard is applicable to the inspection of all oxide films with a thickness of not less than 5um, especially for small specimens with a diameter of 2mm in the inspection area and specimens with uneven surfaces.
If the inspection surface of the specimen is very flat, it is recommended to use the wheel wear method for inspection. When the clamping device of the instrument can accommodate the inspected parts, it is not necessary to cut the specimen. When layered inspection is required, it is recommended to proceed according to the provisions of the wheel wear method. Since different batches of abrasives will cause certain errors in the test results, this test is only a relative inspection. 2 Reference standards
GB4957 Non-conductive coating thickness measurement method on non-magnetic metal substrates 3 Definitions
The following definitions are used when applying this standard.
3. 1 Standard test specimen standard test specimen The specimen prepared according to the conditions given in Appendix C.
3.2 Agreed reference specimen The specimen prepared according to the conditions agreed by both the supplier and the buyer. 3.3 Test specimen test specimen
The sample to be inspected.
4 Principle
Under strictly controlled conditions, dry air or inert gas streams spray dry silicon carbide particles onto a small test area of the sample until the metal substrate is exposed. The wear resistance of the oxide film can be expressed by the blasting time or the weight of silicon carbide used for blasting. The test results should be compared with the results of the standard sample (Appendix C) or the agreed reference sample. State Technical Supervision Bureau approved 1992-0301 implementation on June 4, 1991
GB/T12967.191
When a suitable blasting instrument is selected and equipped with an eddy current instrument with a small probe, the blasting time at each point is gradually increased so that a layered test can be carried out (see Appendix B).
5 Apparatus
5.1 Abrasive jet tester (see Figures A1~A3)
5.1.1 The tester is made of glass, brass, stainless steel or other hard materials. It is mainly composed of two tubes. The tubes are coaxially fixed. The outer tube is connected to the purified and dried compressed air or inert gas generator. The flow rate of the supplied gas is strictly controlled by the control valve. The dry powder is mixed with the air at the outlet end of the inner tube and directly sprayed on the surface of the anodized sample. 5.1.2 There are no strict regulations on the structure of the abrasive jet tester. It is only required that it should have good reproducibility and accurate measurement in multiple consecutive tests.
5.1.3 Although the structure of some abrasive jet testers is reasonably designed, it is difficult to produce a batch of abrasive jet devices that can give the same test results and do not produce errors due to certain factors in actual production. The design scheme recommended in Appendix A has proved to be satisfactory in practice.
5.2 Specimen support
5.2.1 The support is an inclined platform on which the specimen is firmly fixed. The specimen surface is usually at an angle of 45°~55° to the axis of the nozzle.
5.2.2 The blasting effect is different at different angles. The larger the angle, the smaller the elliptical test area, the faster the wear, and the more obvious the final test point.
5.3 Air or inert gas
5.3.1 The air or inert gas required for the outer tube is usually provided by an air compressor or a gas cylinder. The air supply is accurately controlled by a regulating valve, a flow meter or a pressure gauge near the instrument. 5.3.2 The compressed air or inert gas should be dry or low-humidity. Low-humidity air can be produced by passing compressed air through a container to condense water vapor. Dry compressed air can also be produced by passing compressed air or inert gas into a tube containing silica gel. 5.3.3 In practical applications, the optimum flow rate of compressed air or inert gas is 40 to 70 L/min and the pressure is 15 kPa. During the test, once the flow rate of compressed air or inert gas is selected, it should be kept as constant as possible throughout the test. 5.4 Feed Funnel
The feed funnel is used to store abrasives and feeds them at a constant rate of 20±1 to 30±1 g/min. 5.5 Abrasive
5.5.1 Silicon carbide particles are recommended for the abrasive used in the abrasive jet tester. The particle size of the abrasive is preferably 106 and 105 μm. 5.5.2 The abrasive should be free of moisture and should be placed in a flat tray and dried at 105°C before use. Then coarse sieving (a sieve with a nominal mesh size of 180 to 300 μm can be used) to ensure that there are no large particles or strips in the abrasive, as these substances will affect the flow rate of the abrasive. The dried abrasive can be stored in a clean sealed container. It can be reused 50 times, but the dry media should be sieved again before each use.
5.5.3 The environmental temperature has little effect on the test results, but if the undried abrasive is used, it will have a greater impact on the test results.
5.6 Timer
The timer can be selected according to the needs.
6 Test steps
6.1 Standard specimen
Prepare the specimen according to the conditions in Appendix C.
6.2 Specimen
Cut the specimen of suitable size according to the test terms as needed and possible, but the inspection surface of the specimen should not be damaged. 114
6.3 Instrument calibration
GB/T 12967.1--91
6.3.1 Select the wear of the standard specimen and mark it. According to the method specified in GB4957, use an eddy current meter to accurately measure the thickness (d) of the anodic oxide film on each test surface.
6.3.2 Fix the selected standard sample on the sample support, with its test surface facing the nozzle and at a precise angle to the nozzle. 6.3.3 During the test, add a sufficient amount of silicon carbide to the feed funnel. If the wear resistance is measured by the amount of abrasive, the abrasive mass in the feed funnel should be weighed accurately to 8.6.3.4 Adjust the flow rate and pressure of compressed air or inert gas to the selected value (see 5.3.3). And keep it at this selected value from beginning to end during each test.
Note: ① For the standard sample and the sample, the flow rate of compressed air and inert gas should be adjusted to the same wear rate. The optimal wear rate and pressure can be provided by the instrument manufacturer.
② For hard anodized film, soft film, and thin film, the above parameters are different. 6.3.5 The flow and timing of the abrasive should be carried out simultaneously. The abrasive should be sprayed freely during the entire test cycle. 6.3.6 When inspecting under visual conditions, pay close attention to the sample being inspected. When a small black spot appears in the center of the wear surface and the diameter of the black spot expands to 2 mm, the sandblasting and the timer should be stopped immediately to end the test. 6.3.7 Record the test time in seconds. If necessary, weigh the remaining abrasive in the feed funnel to the nearest ! g. 6.3.8 From the two weighings (6.3.3 and 6.3.7), calculate the mass of silicon carbide required to penetrate the oxide film, expressed in grams. From the above process, the wear resistance parameter S of the standard sample is obtained, expressed in seconds or grams. 6.3.9 Make at least two more measurements on other parts of the standard sample (6.3.1 to 6.3.7). 6.4 Correction of the jet flow
6.4.1 Overview
Due to the differences between each nozzle and the wear of the nozzle during use. Therefore, before the test, the instrument must be calibrated with a standard specimen according to the provisions of 6.3 in order to obtain the required abrasion coefficient (see 6.1). 6.4.2 Changes of jet flow and wear characteristics over time In a series of tests, the 6.3. Inspect 1 to 2 times a day according to the steps specified in Article 6.3 to correct for changes in the jet flow or wear characteristics at any time.
6.4.3 Nozzle replacement
After the nozzle is replaced, retest according to the steps specified in Article 6.3 to correct for changes in the jet characteristics. 6.5 Testing
According to the steps specified in Article 6.3, replace the standard sample with the sample to be tested and then conduct the test. 6.6 Use of protocol reference samples
6.6.1 In some cases, for example, in order to achieve self-control of quality, protocol reference samples can be used for comparison in the test. 6.6.2 When necessary, or with the agreement of both the supplier and the buyer, the protocol reference sample can be used to replace the standard sample and calibrated according to the steps specified in Article 6.3.
Results
7.1 Abrasion blasting coefficient
The calculation formula of abrasion blasting coefficient is as follows:
Wu Zhong: k---abrasion blasting coefficient.g/um or s/um; original film thickness of the test surface on the standard sample.um; ds
--wear resistance parameter of the standard sample, s or g. ds
Note: Under the specified conditions, if the abrasion blasting coefficient of the instrument used has been obtained, when the instrument is used for testing again: the test data must be multiplied by this coefficient.
7.2 Average wear resistance
12967.191
The average wear resistance R of a certain part of the oxide film surface is expressed based on the value obtained on the standard sample. The calculation formula is as follows: Rky
Where: S…·wear resistance of the sample under test (see 6.3.7), s or g; d—the original film thickness of the test surface on the sample under test (see 6.3.1), um; Note: ①The average wear resistance is a dimensionless ratio. The average wear resistance of the standard sample is 10 (see 7.1). .(2)
②The term average wear resistance means that the wear resistance of the anodic oxide film may change along the thickness direction. Therefore, the measured value should be the average performance of the entire film thickness
7.3 Test results based on the protocol reference sample If the blasting test is based on the protocol reference sample, the relative average wear resistance Rrel is expressed as a percentage, and the calculation formula is as follows:
Where: S,—wear resistance of the protocol reference sample, s or g; dn
Original film thickness on the test surface of the protocol reference sample, um. dr
The data on the sample and the protocol reference sample used should be the average of no less than three measurement results. 8 Test report
The test report shall include the following contents:
Specimen number;
This standard number;
Model of the abrasive blasting apparatus used, the angle between the test surface and the nozzle; abrasive particle size, flow rate and pressure of the gas used; number of test points and position of the test surface;
Calculated value of average wear resistance characteristic R, or calculated value of relative average wear resistance characteristic Rrel; some phenomena during the test, and characteristics on the test surface. (3)
GB/T12967.1
Appendix A
Structure of abrasive blasting test apparatus
(Supplement)
A1 Although there are no strict requirements for the structure of the abrasive blasting apparatus, it must comply with the general principles of Chapter 4. Two more suitable instrument structures are recommended here (see A2~A3).
A2 Figure A1 shows the basic structure and design of the abrasive blasting machine, but it does not include accessories, specimens and abrasive collection boxes. Figure A2 shows the structure of the nozzle. The nozzle is generally made of brass and stainless steel, and the design requires the nozzle to have strong wear resistance. When the nozzle is at an angle of 55° to the specimen, the grinding speed is high and the final abrasive blasting point is very obvious. Abrasive flow regulator
Supply hopper
Mercury pressure gauge
One-step seat
Outer diameter: medium 4.0±0.1
Inner diameter: medium 2.5±0.1
Sample loading platform
High-resistance rubber tube
Basic structure of abrasive jet tester
k force gauge
Control valve
12967.1 91
Taper 2M
O-ring
A=Φ 2. 0±0. 1
B=$2.5±0.01
C= 3.0 ±0.01
Figure A2 Nozzle structure
GB/T12967.1—91
A3Figure A3 shows the basic structure and design of another relatively satisfactory abrasive jetting apparatus. The manufacturing material can be selected arbitrarily. However, it is recommended that the outer tube (8.5mm) should be made of glass. Since the outer tube is easily damaged and affects the accuracy of the test results, it is recommended to fix it with a detachable metal bad for replacement.
·Supply hopper
Pressure gauge
Metal sleeve
-Push fit
Inner tube (inner diameter: #2.5±0.2)
(Outer diameter: 4.0±0.2)
Outer tube (inner diameter: 96.5±0.1)
(Outer diameter: the minimum should be 8.5)
"Push into the metal sleeve to fix
Shoe sample table
Figure A3 Another basic structure of the grinding tester Air supply port
During the test, the final spray point is obvious. For each air flow rate, a specific glass tube should be selected. The angle between the sample and the nozzle is usually 45°, but it is specified in this standard as 45°~~55°. 149
GB/T 12967.1 - 91
Appendix B
Layered test method for wear resistance
(Supplement)
This appendix specifies a test method for determining the wear resistance of each layer of anodized film of aluminum and aluminum alloys along the thickness direction. B1 Principle
A series of blasting for increasing time is carried out on various parts of the specimen, the longest time being until the oxide film is completely penetrated (see 6.3.6). Finally, the wear resistance characteristics at each specified depth of the film thickness are calculated. B2 Apparatus
The instruments specified in Chapter 4 are used. | |tt||B3 Test steps
B3.1 Test specimenbZxz.net
B3.1.1 The size of the test specimen shall not be less than 70mm×70mm. B3.1.2 Mark the positions of 6~12 test points on the surface of the test specimen, and the arrangement spacing of the points along the length and width of the test specimen is 10mm and 20mm respectively.
B3.1.3 Use an eddy current thickness gauge to accurately measure the original film thickness at each test point with a probe with a diameter of less than 1mm according to the method specified in GB4957.
B3.2 Inspection||t t||B3.2.1 Prepare the instrument according to the provisions of Articles 6.3 and 6.4, and perform the measurement according to the steps described in B3.2.2 to B3.2.5. B3.2.2 Place the ·th test point on the sample under the nozzle at the correct angle, and blast until the oxide film is just worn through. Note the time, and then divide this time by the remaining number of test points, the value obtained is tmin. B3.2.3 Follow the same steps, blast the second point for tmin, blast the third point for 2tmin, and so on until all points are tested. . Record the amount of silicon carbide used for blasting at each point. B3.2.4 After all given test points have been blasted, remove the sample, wipe the test surface with a soft cloth, and accurately measure the remaining film thickness of each test position according to the method specified in GB4957. When confirming whether the film thickness is zero, it can be confirmed with the help of a low-voltage continuous probe. B4 Result expression
B4.1 Calculation of each blasting point
Thickness of the film worn away, um;
b. The corresponding wear value is calculated using the following formula: tK or mK Wherein the blasting coefficient;
t --blasting time, s;
mThe mass of silicon carbide used, g.
B4.2 Curve drawing, with the thickness of the film worn away (micrometers) as the horizontal coordinate and the corresponding wear value as the vertical coordinate. The slope of each point on the curve is the wear resistance characteristic of the oxide film at that depth layer.
Note: This method is not applicable to oxide films with a thickness of less than 5um. The part of the curve below this value can be extrapolated from the point close to it. The result obtained from this part of the curve will often have a certain error with the experimental result. GB/T 12967.1--91
Appendix C
Preparation of standard specimens
(reference)
The standard specimens for wear resistance test should be prepared from polished aluminum plates or bright rolled aluminum plates. c1
Aluminum grade: A199.5(13);
Hardening state: Y2;
Standard specimen size: 140mm×70mm;
Standard specimen thickness: 1.0~1.6mm.
C3 degreasing treatment can be carried out by weak inspection and washing, electrochemical polishing, and chemical polishing. Oxidation tank liquid composition
sulfuric acid concentration: 180±2g/L;
aluminum ion degree: 5~10g/L;
the rest: water.
C5 anodizing conditions
temperature: 20±0.5℃;
current density: 1.5±0.1A/dm2,
stirring method: compressed air;
time: 45 min;;
film thickness: 20±2μm.
sealing requirements: in deionized water containing 1g ammonium acetate per liter (pH 5.5~~6.5), seal the hole for 60min under boiling conditions. When the C6 standard sample is oxidized in the tank liquid, it should be placed vertically with the axis horizontal. The anode surface is kept under strong stirring, and the current should be stable with fluctuations not exceeding 5%. No more than 20 standard samples are oxidized each time, and the volume of the electrolyte is not less than 10L for each sample. Note: () When the anodizing conditions are strictly controlled, very accurate samples can be prepared with good reproducibility. (2) The provisions of this Appendix C are adopted, and the fixed deviation of the standard sample is ±10%. Additional notes:
This standard was proposed by China Nonferrous Metals Industry Corporation. This standard was drafted by Northeast Light Alloy Processing Plant. The main drafters of this standard are Gao Kangzhi and Wang Ziyi. 451
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