This standard specifies the method for determining the mass of conversion coating per unit area on metal materials. This method is applicable to: - Phosphate film on steel; - Phosphate film on zinc and cadmium; - Phosphate film on aluminum and aluminum alloys; - Chromate film on zinc and cadmium; - Chromate film on aluminum and aluminum alloys. This method is only applicable to conversion coatings without any additional covering layer (such as oil film, water-based or solvent-based polymer film or wax film). GB/T 9792-2003 Conversion coating on metal materials - Determination of film mass per unit area - Gravimetric method GB/T9792-2003 Standard download decompression password: www.bzxz.net
This standard specifies the method for determining the mass of conversion coating per unit area on metal materials. This method is applicable to: - Phosphate film on steel; - Phosphate film on zinc and cadmium; - Phosphate film on aluminum and aluminum alloys; - Chromate film on zinc and cadmium; - Chromate film on aluminum and aluminum alloys. This method is only applicable to conversion coatings without any additional covering layer (such as oil film, water-based or solvent-based polymer film or wax film).

This standard is revised and adopted IS03892:2000 "Determination of the mass of conversion coating per unit area on metallic materials - Gravimetric method" (English version). This standard is redrafted based on ISO3892:2000 and modified as follows: - The foreword of ISO3892 is cancelled; - "this standard" is replaced by "this international standard"; for ease of operation, 4.3.1 specifically stipulates ammonium dichromate 20g/L (prepared with ammonia water with a mass fraction of 25% to 30%). This standard Replaces GB/T9792-1988 "Determination of the mass of the conversion coating per unit area on metal materials by gravimetric method". Compared with GB/T9792-1988, the main changes of this standard are as follows: the stripping temperature of zinc phosphate coating on steel is changed from 70℃±5℃ to 75℃±5℃ (1988 edition 4.1.1, 4.1.2, this edition 4.2.2.2);
Except for the determination of manganese phosphate coating and iron phosphate coating on steel, when conducting the determination of other conversion coatings, the stripping, cleaning, drying and weighing procedures of the specimens are changed from the original Repeating the operation several times to achieve constant quality is changed to requiring only one operation (1988 edition 4.1.2, this edition 4.2.2.2, 4.3.2, 4.4.2; 1988 edition 4.2.2, this edition 4.5.2; 1988 edition 4.3.1.2, this edition 4.6.1.3; 1988 edition 4.3.2.2, this edition 4.6.2.2); the definition of fresh film of chromate film and amorphous phosphate film on aluminum and aluminum alloy is changed to: film dried at 25℃~45℃ for 3h5h (1988 edition 4.3 .1, 4.6.1.1 of this edition). This standard is proposed by the China Machinery Industry Federation. This standard is under the jurisdiction of the National Technical Committee for Standardization of Metallic and Non-metallic Coatings. The drafting unit of this standard: Wuhan Institute of Material Protection. The main drafters of this standard: Wang Jurong, Xie Yundan, Bi Yan, Yu Jingqin, Li Xinqing. The previous versions of the standards replaced by this standard are: GB/T9792-1988.
Conversion coating on metal materials
Determination of film mass per unit area
Gravimetric method
GB/T 9792—2003
Warning: The materials, practices, and equipment listed in this standard may be hazardous if appropriate precautions are not taken. This standard does not purport to address all safety issues associated with its application. It is the responsibility of the user of this standard to establish appropriate health and safety practices and determine the applicability of appropriate regulatory authorities before using this standard.
1 Scope
This standard specifies a method for determining the mass per unit area of ​​conversion coatings on metallic materials. This method is applicable to:
Phosphate films on steel;
Phosphate films on zinc and cadmium;
Phosphate films on aluminum and aluminum alloys;
Chromate films on zinc and cadmium;
Chromate films on aluminum and aluminum alloys.
This method is only applicable to conversion coatings without any additional covering layer (such as oil film, water-based or solvent-based polymer film or wax film). This method does not specify the presence or absence of bare spots in the measurement area or the location of the conversion coating thickness below the specified minimum thickness. Furthermore, the individual values ​​obtained for each measuring surface are the average thickness of the conversion coating over the measuring surface. No further mathematical analysis of the individual measured values, for example for statistical testing purposes, is possible. 2 Apparatus
2.1 Apparatus
made ​​of glass or other suitable material not corroded by the test solution, in which the test piece is stripped of the conversion coating. 2.2 Analytical balance
with a sensitivity of 0.1 mg, used to weigh the test piece before and after the conversion coating is dissolved. 2.3 Electrolytic apparatus
for electrolytic dissolution of chromate films on zinc and cadmium. 3 Test piece
The maximum mass of the test piece shall be 200 g, and the total surface area shall be large enough to enable the mass loss before and after stripping to be measured with the required sensitivity and in accordance with the requirements of the relevant material or product specifications. In order to obtain satisfactory accuracy of the measurement results, the total surface area of ​​the test piece shall comply with the provisions of Table 1.
Table 1 Total test surface area
Estimated mass of conversion coating per unit area (mA)/(g/m2)mA1Www.bzxZ.net
≤ma10
10
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