Rainbow chromating of zinc coatings Unichrome YL 22

GOST R 9.316-2006 Unified system of protection against corrosion and aging (USZKS). Thermal diffusion zinc coatings. General requirements and control methods (as amended)

NATIONAL STANDARD OF THE RUSSIAN FEDERATION

Unified system of protection against corrosion and aging

THERMODIFUSION ZINC COATINGS

General requirements and control methods

Unified system of corrosion and aging protection. Thermodiffusion zinc coatings. General requirements and control methods

OKS 25.220.40 77.060

Date of introduction 2007-07-01

Preface

The goals and principles of standardization in the Russian Federation are established by Federal Law No. 184-FZ of December 27, 2002 “On technical regulation,” and the rules for applying national standards of the Russian Federation are GOST R 1.0-2004 “Standardization in the Russian Federation. Basic provisions"

Standard information

1 DEVELOPED AND INTRODUCED by the Technical Committee for Standardization TC 213 “Metal and other inorganic coatings” and TC 214 “Protection of products and materials from corrosion”

2 APPROVED AND ENTERED INTO EFFECT by Order of the Federal Agency for Technical Regulation and Metrology dated September 21, 2006 N 204-st

3 INSTEAD GOST R 51163-98

Information about changes to this standard is published in the “National Standards” index, and the text of changes and amendments is published in the monthly published “National Standards” information indexes. In the event of revision or cancellation of this standard, the corresponding notice will be published in the published information index “National Standards”. Relevant information, notifications and texts are also posted in the public information system - on the official website of the Federal Agency for Technical Regulation and Metrology on the Internet

An amendment was made, published in IUS No. 2, 2007

The amendment was made by the legal bureau "Code"

Introduction

Thermal diffusion galvanizing of product surfaces is intended to increase their corrosion resistance.

Thermal diffusion zinc coating is anodic in relation to ferrous metals and electrochemically protects steel from corrosion. It has strong adhesion (adhesion) to the base metal due to the mutual diffusion of iron and zinc in the surface intermetallic phases, so the coating does not peel off or chip under impacts, mechanical loads and deformations of the processed products. GOST 9.302-88 does not establish a test method for assessing the adhesion of thermal diffusion zinc coatings. The methods for testing the adhesion strength of zinc coatings established in GOST 9.302-88 are widely used and recommended for assessing the adhesion strength between different layers of thermal diffusion zinc coating, however, in some cases other tests may be more acceptable, which should be established in agreement with the consumer.

The advantage of thermal diffusion coating technology compared to galvanic coatings is not only its superior corrosion resistance, but also the fact that it does not cause irreversible hydrogen embrittlement of the metal during the application process (directly in the container). Treatment of the product before and after coating must exclude the possibility of hydrogen embrittlement. Hydrogen embrittlement in high-strength steel products must be excluded, therefore, when this requirement is specified by the consumer, the absence of hydrogen embrittlement is determined in accordance with the requirements of this standard.

Thermal diffusion zinc coating precisely follows the contours of the products; it is uniform in thickness over the entire surface, including products of complex shapes and threaded connections.

Thermal diffusion zinc coating mainly consists of an iron-zinc -phase of variable composition containing up to 10% iron.

Due to the presence of iron impurities on the surface of the coating, when exposed to high humidity or condensation, a brown coating may appear on the surface of a galvanized product, which is not a sign of the appearance of foci of corrosion of the base metal. In order to preserve decorative properties and further increase corrosion resistance, parts coated with thermal diffusion galvanizing are subjected to subsequent additional surface treatment. Additionally, post-treatment of zinc coatings is designed to slow or prevent the formation of white corrosion products on surfaces exposed to high humidity atmospheres, salt water, marine atmospheres or cycles of condensation and drying.

Appendix A (for reference). Quality control of the prepared surface

Appendix A (reference)

A.1 To control the quality of the prepared surface of the product before coating, from 2% to 5% of the total number of samples, but not less than four products, are taken from the batch. Single products and structures (brackets, consoles, supports, blocks of rigid crossbars) are subjected to complete control.

A.2 Fasteners are controlled for the necessary tolerance for coating using a standard die, nut and other devices specified in the technological documentation.

A.3 Methods for quality control of the prepared surface - according to GOST 9.402.

TYPES AND THICKNESS OF COATINGS

2.1. When choosing coatings you should consider:

purpose of fittings;

purpose of the coating (protective - for internal parts or protective and decorative - for others);

material;

operating conditions for the fittings are U1.1 and UHL(HL)1.1 according to GOST 15150.

2.2. The choice of the type and thickness of the protective and protective-decorative coating is carried out in accordance with the table.

________

1 Used to cover keys for suitcases and business briefcases.

2 Used to cover accessories for wallets, school bags and backpacks, as well as provided that the roughness parameter ( Ra

) on the front surface before coating is not more than 0.16 microns.

3 Used for fittings manufactured by order of the USSR Ministry of Defense.

4 Used by agreement with the consumer.

5 The brand of paint and varnish coating and the regulatory and technical documentation for it are indicated.

6 Instead of the designation “color” and after the designation “tn” the color of the coating is indicated.

7 Used for internal parts, as well as upon customer request.

8 Used for buttons.

9 The electrically conductive sublayer is not regulated.

2.3. Technological processes for producing metallic and non-metallic inorganic coatings in accordance with GOST 9.305.

2.4. Designation of coatings according to GOST 9.306.

2.5. Maximum thickness of metal coatings according to GOST 9.303.