GB/T 19823-2020. Thermal spraying-Procedures for the application of thermally sprayed coatings for engineering components.
1 Scope
GB/T 19823 specifies the general process procedures for thermal spray coatings used to improve the surface performance of parts or to repair and remanufacture scrap parts. Due to the diversity of thermal spraying processes, the shapes of sprayed parts, and the physical and chemical properties of coatings, this standard does not provide a decisive solution for specific part coatings.
GB/T 19823 is applicable to the general situation of selecting thermal spraying process procedures and coating materials. This standard does not apply to thermally sprayed zinc, aluminum and their alloy coatings resistant to atmospheric corrosion on steel structures. The applicable standard for thermally sprayed zinc, aluminum and their alloy coatings is GB/T 9793. This standard also does not apply to self-fluxing alloy remelting coatings. The applicable standard for self-fluxing alloy remelting coatings is GB/T 16744.
2 Normative references
The following documents are essential for the application of this document. For all references with dates, only the versions with dates apply to this document. For all references without dates, the latest versions (including all amendments) apply to this document.
GB/T 11373 Pretreatment of the surface of thermally sprayed metal parts
GB/T 18719 Thermal spraying terminology and classification (GB/T 18719-2002, ISO 14917:1999, MOD)
GB/T 19824 Thermal spraying Requirements for the assessment of thermal spraying operators (GB/T 19824-2005, ISO 14918:1998, MOD)
GB/T 37421 Thermal spraying Characterization and testing of thermal sprayed coatings (GB/T 37421-2019, ISO 14923: 2003, MOD)
EN 15520 Thermal spraying Recommended practice for structural design of components with thermally sprayed coatings This standard specifies the general
process specifications for thermal spray coatings used to improve the surface properties of parts or to repair and remanufacture scrap parts. Due to the diversity of thermal spraying processes, the shapes of sprayed parts, and the physical and chemical properties of coatings, this standard does not provide a decisive solution for specific part coatings. This standard applies to the general selection of thermal spraying process specifications and coating materials. This standard does not apply to thermal spraying zinc, aluminum and their alloy coatings for steel structures to resist atmospheric corrosion. The applicable standard for thermal spraying zinc, aluminum and their alloy coatings is GB/T 9793. This standard also does not apply to self-fluxing alloy remelting coatings. The applicable standard for self-fluxing alloy remelting coatings is GB/T 16744.

ICS25.220.20
National Standard of the People's Republic of China
GB/T19823—2020
Replaces GB/T19823—2005
Thermal spraying
Thermal spraying-Procedures for the application of thermally sprayed coatings for engineering parts coatings for engineering components (ISO 14921:2010, MOD)
2020-06-02Release
State Administration for Market Regulation
National Administration of Standardization
Release
2021-04-01Implementation
GB/T 19823—2020
Foreword
Scope
Normative references
Terms and definitions
Principles of coating design and coating implementation
Pre-processing for turning, milling and grinding||tt ||Masking
Surface pretreatment method
Thermal spraying
Post-coating inspection
Sealing
Post-coating processing
Final inspection
Prepared documents:
Appendix A (informative appendix)
Appendix B (informative appendix)
Appendix C (informative appendix)
References
Flowchart for evaluating the suitability of thermal spraying processes
Determining the optimal coating systemExpected goals Inspection items Thermal spraying process procedures application records
Foreword
This standard was drafted in accordance with the rules given in GB/T1.1-2009. GB/T19823-2020
This standard replaces GB/T19823-2005 "Application steps of thermal spray coatings for thermal sprayed engineering parts". Compared with GB/T19823-2005, the main technical changes of this standard are as follows: - Modified "Normative reference documents" (see Chapter 2, Chapter 2 of the 2005 edition); - Added "Terms and definitions" (see Chapter 3); - Added "Preparation documents" (see Chapter 13). This standard uses the redrafting method to modify and adopt ISO14921:2010 "Application steps of thermal spray coatings for thermal spray engineering parts". The technical differences and reasons between this standard and ISO14921:2010 are as follows: Regarding normative reference documents, this standard has made technically different adjustments to adapt to my country's technical conditions. The adjustments are concentrated in Chapter 2 "Normative reference documents". The specific adjustments are as follows: · Replace ISO2063 with GB/T9793, which is equivalent to the international standard (see Chapter 1), and GB/T9793 is listed as a reference;
· Replace EN13507 with GB/T11373 (See Chapter 7); · ISO14920 is replaced by GB/T16744, which is modified to adopt the international standard (see Chapter 1), and GB/T16744 is listed as a reference;
· ISO14917 is replaced by GB/T18719, which is modified to adopt the international standard (see Chapter 3); · ISO14918 is replaced by GB/T19824, which is modified to adopt the international standard (see Chapter 8); · ISO14923 is replaced by GB/T37421, which is modified to adopt the international standard (see Chapter 9). This standard has made the following editorial changes:
The content of Chapter 1 "Scope" has been rearranged according to GB/T1.1-2009. 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 (SAC/TC57). The drafting units of this standard are: Foshan Advanced Surface Technology Co., Ltd., Spray Technology Co., Ltd., Beijing Mining and Metallurgical Technology Group Co., Ltd., Wuhan Materials Protection Research Institute Co., Ltd., and Ruili Group Ruian Auto Parts Co., Ltd. The main drafters of this standard are: Li Zhigang, Yu Yueguang, Liang Dong, Chen Tongzhou, Liu Jianhui, Shen Jie, Cao Qing, Gao Mingchuan, Liang Weijian, Ye Yonghong, Zhang Zaiwei.
The previous versions of the standards replaced by this standard are: GB/T19823-2005.
1 Scope
Application steps of thermal spray coatings for thermal spray engineering parts GB/T19823-2020
This standard specifies the general process specifications for thermal spray coatings used to improve the surface performance of parts or repair and remanufacture of scrap parts. Due to the diversity of thermal spraying processes, the shapes of sprayed parts, and the physical and chemical properties of coatings, this standard does not provide a decisive solution for specific parts coatings.
This standard applies to the general situation of selecting thermal spraying process specifications and coating materials. This standard does not apply to thermal spraying zinc, aluminum and their alloy coatings resistant to atmospheric corrosion on steel structures. The applicable standard for thermal spraying zinc, aluminum and their alloy coatings is GB/T9793. This standard is also not applicable to self-fluxing alloy remelting coatings. The applicable standard for self-fluxing alloy remelting coatings is GB/T16744. 2 Normative references
The following documents are essential for the application of this document. For any referenced document with a date, only the version with the date is applicable to this document. For undated referenced documents, the latest version (including all amendments) shall apply to this document GB/T11373 Pretreatment of the surface of thermally sprayed metal parts GB/T18719#
Thermal spraying Terminology and classification (GB/T18719-2002, ISO14917:1999, MOD) GB/T19824#
Thermal spraying Requirements for the assessment of thermal spraying operators (GB/T19824-2005, ISO14918:1998, MOD) GB/T37421
Thermal spraying Characterization and testing of thermal sprayed coatings (GB/T37421-2019, ISO14923:2003, MOD) EN1552o Thermal spraying Recommended practice for structural design of components with thermally sprayed coatings (Therms praying—Recommendations for constructional design of components with thermally sprayed 3 Terms and definitions
The terms and definitions defined in GB/T 18719 apply to this document. 4 Principles of coating design and coating implementation
4.1 General principles
The factors to be considered in the principles of parts and coating implementation are described in the process shown in Appendix A. If any of the clauses 4.2 to 4.4 are not met, thermal spraying technology is not recommended
The determination of whether the new part can be sprayed is made by evaluating the sprayed parts and the sprayed area. If the coating specification determines the coating material, the influencing factors to be considered will be reduced. 4.2 Pre-inspection of parts before repair
The parts must be inspected before the thermal spraying process to determine whether they are suitable for spraying. It should be noted that: when the workpiece is a rotating part, the concentricity and straightness of the part should be checked; when the workpiece is a reciprocating sliding part, the geometric shape of the part should be checked, and the geometric shape error of the part should be corrected if necessary; check whether there are cracks or other damages on the surface of the workpiece to be sprayed that affect the performance of the coating. If there are defects that cannot be eliminated, spraying construction cannot be carried out;
GB/T19823—2020
Determine the spraying area and range of the part;
- Check and remove any residual coating on the surface of the workpiece; Check and determine the surface hardness of the workpiece.
4.3 Part substrate
Whether the thermal spray coating can meet the expected goals should consider the following factors: whether the substrate material is not suitable for the thermal spraying process or whether there are factors that need to be specially considered during the spraying process. Under normal circumstances, thermal spray coatings will not increase the strength of the parts, so the impact of any reduction in the original part size on the strength should be considered.
Surface treatment methods, spraying materials, and spraying processes may affect the fatigue strength of parts. A special surface hardening process such as nitriding treatment residual gas may have an adverse effect on surface pretreatment, coating bonding strength and coating porosity.
When the hardened layer hinders normal surface treatment, it must be fully considered that it limits the application of the coating system and affects the subsequent coating performance.
In order to obtain a complete coating, a complete coating preparation process must be formulated. Spray pretreatment requirements, spraying and testing, spray gun and related electrical and gas connections, spray distance and spray angle must all be considered. 4.4 Coating
Spraying process and spraying materials have a great influence on coating performance. In order to determine the most suitable coating system, the following factors need to be considered: bonding strength requirements;
-thickness requirements;
-surface condition (roughness) requirements;
-surface load, thermal spray coatings are not suitable for parts that are sensitive to line contact or point contact stress;-final coating performance requirements, such as resistance to different types of mechanical wear, corrosion, chemical attack, high temperature, thermal cycle and other environmental conditions;
-When the porosity in the coating does not meet the requirements, it should be sealed with appropriate sealants and sealing methods;-coating oxide content, which can be controlled by process parameters and the selection of spraying materials when necessary. Appendix B lists in detail the inspection items required to achieve the optimal coating system for the intended purpose. 5 Turning, milling, grinding pre-processing
When parts are re-prepared for coating, all residual coatings should be completely removed. The possibility of the pre-treatment affecting the coating with special requirements, such as improving fatigue strength, should be considered.
Perform pre-cutting processing, cut off the wear profile and ensure uniformity of coating thickness. When coating new parts, the area to be sprayed should be cut down. The amount of cutting down is the coating thickness. The boundary edge between the sprayed area and the non-sprayed area should maintain a continuous transition of arc or chamfer to embed the coating into the part. These contour designs are recommended in EN15520. For shaft parts, the machined surface should maintain concentricity with the relevant axis to ensure the uniformity of the coating thickness. Pre-cutting should be carried out as far as possible without the use of lubricants, especially for porous matrix materials. If necessary, the pre-processed parts should be degreased. 6 Masking
The surface of the workpiece that does not need to be sprayed should be masked with appropriate materials. The ideal masking material should have the ability to resist the impact during sandblasting and the ability to withstand the heat during spraying. Otherwise, different masking materials should be used in the sandblasting and spraying processes. Measures should be taken at all times to ensure that the masking material does not contaminate the surface to be sprayed. 7 Surface preparation methods
Before surface preparation, the contamination generated by the surface to be treated should be removed and purified directly GB/T19823—2020
Appropriate surface preparation methods can achieve the maximum bonding strength between the coating and the metal substrate. Sandblasting is a common method to achieve this goal. The surface preparation method should be carried out in accordance with GB/T11373. If there are differences, the contracting parties shall reach an agreement through consultation. 8 Thermal spraying
After surface preparation, spraying should be carried out as soon as possible using the process parameters given in the thermal spraying process specification. Between spraying and sandblasting, reasonable precautions should be taken to prevent contamination of the pretreated surface. Before spraying, the surface to be sprayed should be properly preheated directly to avoid contamination and local overheating of the surface to be sprayed. Before and during spraying, the surface should be heated sufficiently to prevent moisture condensation. During spraying, it is necessary to control the temperature of the coating to avoid excessive residual stress, which determines the coating performance. Dust inclusions in the coating should be minimized. All spraying equipment should be operated according to the manufacturer's instructions. The equipment operator shall obtain the qualification in accordance with GB/T19824, or obtain the equivalent qualification through negotiation between the parties. 9 Post-coating inspection
After the coating cools to room temperature, the coating shall be inspected in the following ways: visually inspect the coating in accordance with GB/T37421;
Measure the coating thickness.
If peeling, cracking, or any other unqualified defects are observed, the coating shall be completely removed, and the pretreatment and spraying shall be carried out again in accordance with the spraying process specification or a newly revised spraying process specification. 10 Sealingwww.bzxz.net
When necessary, the thermal spray coating can be sealed. There are a series of different sealers and sealing methods to choose from. The sealing treatment shall be carried out in accordance with the method provided by the supplier.
The sealing treatment shall be carried out immediately after the coating is sprayed. If the sealer contains a solvent, the sealing shall be carried out after the coating cools to room temperature.
11 Post-coating processing
The coating can be processed by turning, milling, grinding, etc. Refer to the mechanical processing and post-processing methods of thermal spray coatings recommended by ISO14924.
2 Final inspection
The final inspection items of the coating are as follows:
GB/T19823—2020
Dimensional accuracy is within the specified tolerance range;
Achieve the specified surface roughness;
Visually inspect coating defects, such as pores, scratches, cracks, and peeling (see GB/T37421);-Remove excess coating;
Part cleanliness;
Other provisions, such as indicators required by the contract 13
Prepare documents
In order to meet the requirements of quality management, establish records including all production procedures. If necessary, all test data should be included. Appendix C is an example of applying thermal spray production process procedure records. This record can also serve as a guiding document for thermal spraying operation specifications. Appendix A
(Informative Appendix)
Flowchart for evaluating the adaptability of thermal spraying process
See Figure A.1 for the flow chart for evaluating the adaptability of thermal spraying process. Surface treated parts Grinding or electrochemical can be removed Cleared Figure A.1 Matrix material Too hard to sandblast Part surface Damage Geometric shape Meet spraying requirements Thermal spraying Flow chart for evaluating the suitability of thermal spraying process Other surfaces Treatment methods Can be removed Can be improved GB/T19823—2020 Thermal spraying is not recommended1
Base material
Too hard to
Sandblasting
Part surface
Damage
Geometric shape
Meet spraying
Requirements
Thermal spraying
Flowchart for evaluating the suitability of thermal spraying process
Other surfaces
Treatment method
Can
Remove
Can
Improve
GB/T19823—2020
Thermal spraying is not recommended1
Base material
Too hard to
Sandblasting
Part surface
Damage
Geometric shape
Meet spraying
Requirements
Thermal spraying
Evaluation of thermal spraying process adaptability flow chart
Other surfaces
Treatment method
Can
Remove
Can
Improve
GB/T19823—2020
Thermal spraying is not recommended
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