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GB/T 18684-2002: Specifications of zinc/chromate coating Delivery: 9 seconds. True-PDF full-copy in English & invoice will be downloaded + auto-delivered via email. See step-by-step procedure Status: Valid
Similar standardsGB/T 18684-2002: Specifications of zinc/chromate coating---This is an excerpt. Full copy of true-PDF in English version (including equations, symbols, images, flow-chart, tables, and figures etc.), auto-downloaded/delivered in 9 seconds, can be purchased online: https://www.ChineseStandard.net/PDF.aspx/GBT18684-2002GB NATIONAL STANDARD OF THE PEOPLE’S REPUBLIC OF CHINA ICS 25.220.20 A 29 Specifications of Zinc/Chromate coatings Issued on March 10, 2002 Implemented on August 1, 2002 Issued by. General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China Table of ContentsForeword... 3 1 Scope... 4 2 Normative References... 4 3 Definition... 4 4 Classification... 4 5 Documents that are required to be supplied to supplier... 5 6 Technical requirements... 5 7 Sampling... 6 8 Test methods... 7 Appendix A... 9 Appendix B... 11ForewordAppendix A and B in this Standard are informative. This Standard was proposed by the China Machinery Industry Federation. This Standard shall be under the jurisdiction of the China Standardization Technology Committee of Metallic and Non-metallic Coatings. The responsible drafting organizations of this Standard. Wuhan Research Institute of Materials Protection, and Nanjing Hongguang Parachute Equipment Factory. The participating drafting organizations of this Standard. Wuhan Yongtaihe Metal Anticorrosion Technology Co., Ltd., and Beijing Yongtaihe Metal Anticorrosion Technology Co., Ltd. The main drafters of this Standard. Wu Yong, Xue Zhongyou, Zhang Weiming, Li Chunyan and Zhang Hongwei. Specifications of Zinc/Chromate coatings1 ScopeThis Standard specifies the technical requirements and test methods of zinc/chromate coatings of steel parts and components.2 Normative ReferencesThe following normative documents contain the provisions which, through reference in this text, constitute the provisions of this Standard. For the dated reference, the subsequent amendments (excluding corrigendum) or revisions of these publications do not apply. However, the parties who reach an agreement based on this Standard are encouraged to use the latest edition of these documents. For undated references, the latest edition of the normative document referred to applies. GB/T 5270-1985 Metallic Coatings on Metallic Substrates - Electrodeposited and Chemically Deposited Coatings - Review of methods available for testing adhesion (eqv ISO 2819.1980) GB/T 6462 Metallic and oxide coatings - Measurement of Coating Thickness - Microscopical method (eqv ISO 1463) GB/T 10125-1997 Corrosion Tests in Artificial Atmospheres - Salt Spray Tests (SS) (eqv ISO 9227.1990)3 DefinitionThe following definition is applicable to this Standard. Zinc/Chromate coatings Using water-based zinc/chromate coatings to dip-coat, brush-coat or spray onto the surface of steel parts or components, then it is baked to form into the inorganic anticorrosion coating of which the main ingredients are the flake zinc and zinc chromate.4 ClassificationThe zinc/chromate coatings are divided into 4 classes shown in Table 1 according to the coating quantity and coating thickness.5 Documents that are required to be supplied to suppliera) Number of this Standard; b) Required coating class of the workpiece to be coated; c) The final heat-treatment temperature of the workpiece to be coated.6 Technical requirements6.1 Appearance The basic color of zinc/chromate coatings shall be silver gray; it can also be other colors by modifying, such as black, and so on. The zinc/chromate coatings shall be continuous, without defects such as miss-coating, bubble, peel-off, crackle, mottle and impurity. 6.2 Coating quantity and coating thickness The coating quantity and coating thickness of different classes shall not be lower than the requirements specified in Table 1. 6.3 Adhesion strength The coating must not be peeled off and bottom-exposed, after conducting adhesion strength test for coating according to the method in 8.3.However, it is allow that the adhesive tape is color-change and and is adhered with zinc and aluminum dust granules. 6.5 Water resistant test property For class 3 and 4 coatings, after it is conducted for water resistant test according to the requirements of 8.5, the coating must not be peeled off from the matrix or bottom-exposed. For class 1 and 2 coatings, it is exempted from water resistant test.7 Sampling7.1 In the same batch of products, it is required to randomly sample 3 samples for each test for experiment. If any sample among which is nonconformance after testing, then it is required to randomly sample another 3 samples to conduct the same test one more time. If there is any sample is still nonconformance, then this batch of products shall be deemed as nonconformance. 7.2 For assembly OR part or component of which the mass of single-part exceeds 150 g, it may cut a part of the workpiece as the sample for testing. In order to avoid the matrix of bare steel at incision impacting the test result, it shall adopt coating, wax or adhesive tape to protect the incision.8 Test methods8.1 Appearance To inspect with the naked eye under the nature diffused light. 8.2 Coating and test 8.3 Adhesion Strength Test Adopt adhesive tape test method to inspect the adhesive strength between zinc/chromate coatings and matrix; the tape test shall be conducted according to the requirements of Clause 1.4 in GB/T 270-1985. 8.4 Salt spray test The salt spray test shall be conducted according to the requirements of Clause 3.2.1 in GB/T 10125-1997. 8.5 Water resistant test Soak the sample into de-ionized water of 40°C ±1°C; continuous soak for 240h; take out the sample; dry at room temperature; then, conduct the adhesive strength test according to the requirements of 8.3; 8.6 Humid heat test The humid heat test shall be conducted in humid heat test box; the humid heat test box shall be able to adjust and control the temperature and humidity.Appendix A(Informative) Calculation method of coating surface area A.1 Shim bolt (pole) nut A.1.1 Flat shim A.2 Workpiece of complicated shape A.2.1 To calculate by resolving into simple sharp To resolve the surface of workpiece of complicated shape into surfaces of several simple shapes; the surface area of workpiece of complicated shape is equal to the sum of surface areas of several simple shapes. For example. Note. S is the surface area of workpiece of complicated shape. S1, S2, S3, S4, S5, S6 and S7 is the surface area of 7 simple shapes of ①, ②, ③, ④, ⑤, ⑥ and ⑦ respectively in above figure. A.2.2 To calculate in profile modeling of plotting paper Take a piece of plotting paper od which the area is X (dm2) as standard paper; and weigh its mass as b (g). In addition, take a piece of plotting paper to model for a surface of coated workpiece. Then weigh the mass of profile modeling paper as a (g). Calculate the area of profile modeling paper, that is, the surface area S (dm2) of coated workpiece, according to the following formula.Appendix B(Informative) The application and limit of zinc/chromate coatings B.1 The application of zinc/chromate coatings The zinc/chromate coatings is a kind of high anticorrosion coating; the production process have no pollution to the environment basically. Compared with electro galvanizing, electro tinning, hot galvanizing, the advantages and application of zinc/chromate coatings are as follows. B.1.4 Not producing hydrogen brittleness For the steel workpiece of high strength of which the tensile strength Rm≥N/mm2, it will not produce hydrogen brittleness when coating with zinc/chromate coatings. Adopting zinc/chromate coatings to replace electro galvanizing, electro tinning for the protection of the surface of these kinds of workpieces may avoid the hazard of hydrogen brittleness. In addition, in order to avoid the hydrogen brittleness, the preliminary treatment shall also adopt the processes such as solvent de-oiling, mechanical de-rusting which will not produce hydrogen brittleness. B.1.5 Good deep-coating property Because of electrostatic shield effect, the sections such as deep-hole and slit of workpiece AND inner wall are difficult to be electroplated with zinc/ chromate; therefore, the aforesaid sections of workpieces can not be protected by adopting electroplate method. However, zinc/chromate coatings may enter these sections of workpieces and form into zinc/chromate coatings; therefore, the zinc/chromate coatings are very suitable to these kinds of workpieces. B.1.6 Good coatable property zinc/chromate coatings have good coating property. It not only enriches the appearance color of workpieces, but also further improves the corrosion-resisting property. B.1.7 Not producing bimetallic corrosion with aluminium and its alloy The zinc/chromate coatings will not produce bimetallic corrosion with aluminium and its alloy; it can be used to the surface protection of steel workpieces which contact with aluminium and its alloy. ......Source: Above contents are excerpted from the full-copy PDF -- translated/reviewed by: www.ChineseStandard.net / Wayne Zheng et al. Tips & Frequently Asked Questions:Question 1: How long will the true-PDF of English version of GB/T 18684-2002 be delivered?Answer: The full copy PDF of English version of GB/T 18684-2002 can be downloaded in 9 seconds, and it will also be emailed to you in 9 seconds (double mechanisms to ensure the delivery reliably), with PDF-invoice.Question 2: Can I share the purchased PDF of GB/T 18684-2002_English with my colleagues?Answer: Yes. 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