JB/T 7703-1995 Technical requirements for thermal spraying ceramic coatings
Some standard content:
Mechanical Industry Standard of the People's Republic of China
JB/T 7703-95
Technical Conditions for Thermal Spray Ceramic Coatings
Published on June 20, 1995
Ministry of Machinery Industry of the People's Republic of China
Published
Implementation on January 1, 1996
Mechanical Industry Standard of the People's Republic of China
Technical Conditions for Thermal Spray Ceramic Coatings
1 Subject Content and Scope of Application
JB/T 7703-95
This standard specifies the thermal spray ceramic powder materials, processes and coating design representation methods, ceramic coating quality inspection, packaging and transportation of sprayed ceramic coating products and spraying safety operation rules. It provides a guide for the general technical conditions of the thermal spray ceramic coating process. This standard is applicable to the plasma spraying process of ceramic powder materials to prepare surface functional coatings such as corrosion resistance, wear resistance, heat resistance, insulation, thermal barrier, insulation, radiation, etc., to improve the performance of products. This standard also provides guidance for the preparation of ceramic coatings by flame spraying, supersonic flame spraying and detonation spraying.
2 Reference standards
GB6462
GB8642
GB9790
GB11373
GB 11374
GB11375
GB12607
GB 12608
Microscopic measurement method of cross-sectional thickness of metal and oxide coatingsDetermination of bonding strength of thermal spray coatings
Vickers and Knoop microhardness tests for metal coatings and other related coatingsGeneral rules for surface pretreatment of thermally sprayed metal parts
Non-destructive measurement method of thermal spray coating thicknessSafety in thermal spraying operations
Design and naming method for thermal spray coatings
Naming method for thermal spray coating materials
3 Thermal spray ceramic materials, processes and coating design representation methods3.1 Commonly used ceramic coating materials for thermal spraying
According to the provisions of GB12608, thermal ceramic powder materials use Arabic numerals as classification codes, and the last two Arabic numerals are serial numbers. P7××× indicates that 7 is the code for the major category of ceramic coatings, and the second digit is A. The brands, compositions and properties of commonly used thermal spray ceramic powder materials are listed in Appendix A (Supplement) Table A1. 3.2 Process methods for thermal spray ceramic coatings
There are six types of thermal spray processes applicable to ceramic powder materials. According to the provisions of GB12607, their symbols are listed in Appendix B Table B1. 3.3 Design and representation methods for thermal spray ceramic coatings The design and representation methods of thermal spray ceramic coating systems shall be implemented in accordance with the provisions of GB12607. Take the thermal spray coating system of plasma spraying A10+13%TiOz ceramic composite powder (P7112) on steel substrate, sandblasting pretreatment, NiCr alloy powder (P1501) primer, sealing, grinding and finishing as an example, the coating design representation method is as follows: Ministry of Machinery Industry. Approved on June 20, 1995
Implemented on January 1, 1996
JB/T 7703-95
TS2·P1501/.71121/3
4General rules for thermal spraying ceramic coating process
Coating finishing, grinding
Coating post-treatment, sealing
Surface ceramic coating materials
Bonded base materials
Gas-stabilized plasma spraying
Sandblasting pretreatment
Thermal spraying code
Thermal spraying ceramic coating is a process system. First, the performance requirements for the coating should be determined according to the service conditions or failure analysis of the product, and the appropriate thermal spraying materials, equipment and processes should be selected accordingly. Then, the thermal spraying process is implemented, including: surface pretreatment of the substrate, thermal spraying process, coating sealing and finishing, and coating quality inspection. Each process must be carried out strictly in accordance with the operating procedures, and the next process can only be carried out after passing the inspection.
This standard only provides general rules for the process of thermal spraying ceramic coating. The specific index parameters of specific products, specific coatings, and specific processes should be determined by special standards.
4.1 Coating system design
4.1.1 Determine the functional requirements of the coating
The service conditions of the product to be sprayed, or the reasons for the failure of the product during use, should be accurately understood to determine the functional requirements of the coating. 4.1.2 Selection of coating materials
Only by being familiar with and mastering rich and comprehensive material science knowledge can we correctly and reasonably design the coating system and select coating materials. For information on this aspect, please refer to the ninth chapter of the "Technical Manual of Mechanical Manufacturing Process Materials" "Technical Manual of Thermal Spraying Materials" (Machinery Industry Press, 1993, first edition).
4.1.2.1 Selection of ceramic coating materials: The selection of ceramic coating materials for a specific purpose should be based on the requirements for the coating function determined by the service conditions of the coating, and comprehensively consider the various properties of different ceramic materials, such as hardness, melting point, thermal conductivity, corrosion resistance, wear resistance and electrical properties, and make comparative selections. Commonly used thermal spray ceramic materials are shown in Table A1 of Appendix A. 4.1.2.2 Selection of primer coating materials: When the adhesion between the sprayed substrate material and the ceramic coating material is poor, a primer coating is often used to improve the bonding performance between the substrate and the coating. The primer coating material has one or more of the following characteristics: a. "Self-bonding" effect: Under the high temperature of the thermal spray flame, the different components of the coating material can undergo an exothermic chemical reaction, so that the coating and the substrate form a micro-area metallurgical bond. The most typical and widely used "self-bonding" primer coating material is nickel-aluminum composite powder. b. "Roughening" effect: The surface of the bonding bottom layer is more irregular than the surface of the substrate treated by sandblasting, so the ceramic coating can form a stronger mechanical fit with it.
c. "Curtain grid shielding effect: The primer coating has better oxidation resistance and corrosion resistance than the substrate material, and acts as a shielding curtain between the ceramic coating and the substrate, which can minimize the oxidation or corrosion of the substrate caused by the inherent porosity of the thermal sprayed ceramic coating. d. "Buffering effect: The thermal expansion coefficient of the primer coating is between that of the substrate and the ceramic coating, and it has sufficient toughness under mechanical and thermal loads, which can play a "buffering" role on the stress caused by the different expansion coefficients of the substrate and the ceramic coating. The commonly used "self-bonding" primer coating material is Ni-Al composite powder. In addition, there are NiCrAl, NiCrAIY, CoCrAIY composite powders. Other primer coating materials include Mo (not suitable for working in oxidizing atmospheres above 400°C) and NiCr alloy (satisfactory as a bonding base for ceramic coatings at high temperatures of 1000°C). When spraying ceramic coatings on low-melting-point materials such as plastics, tin, zinc, aluminum, and copper are often used as primer coating materials.
4.1.2.3 Step coating: When the physical properties between the metal substrate and the ceramic coating interface, such as toughness, thermal expansion and crystal structure, are different 2
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is very large, which may lead to increased internal stress of the ceramic coating, poor adhesion to the substrate, and coating failure. The solution to this problem is to use a stepped coating structure to achieve a gradual transition in the distribution ratio and performance between the substrate and the surface ceramic coating. Examples of stepped coating systems are as follows:
a. A primer coating of about 0.1 mm thick;
b. A mixture of primer coating material/surface ceramic material is sprayed in a ratio of 65/35, with a coating thickness of about 0.1 mm mzc. Spray the mixture of primer coating material/surface ceramic material in a ratio of 35/65, with a coating thickness of about 0.1mm yuan d. 0.1mm thick surface ceramic coating.
This step coating system can also be improved with three layers, using a 50/50 mixture coating as the middle layer. 1.1.3 Substrate material selection
The substrate material used for thermal spray ceramic coatings is usually a metal-based material, such as steel, aluminum, titanium, copper, bronze and refractory metals. However, other inorganic materials such as ceramics Porcelain, metal ceramics, and even organic materials. In short, almost all solid materials can be used as substrates, and their properties can be improved by spraying ceramic coatings.
4.1.4 Selection of thermal spraying process and equipment
4.1.4.1 Selection of thermal spraying process: There are six thermal spraying processes suitable for spraying ceramic coatings, as shown in Appendix B Table B1. The determination of the spraying process should be based on the melting point, thermal conductivity, thermal shock resistance and bonding strength requirements of the ceramic coating material, combined with production efficiency, cost and other comprehensive considerations.
Gas-stabilized plasma spraying process is the most commonly used process for spraying various ceramic coatings. Powder flame spraying process is widely used in parts maintenance and small-scale product production. Supersonic flame spraying is an emerging and rapidly developing process. 4.1.4.2 Selection of thermal spraying equipment: According to the functional requirements of the ceramic coating, the coating material and the spraying process selection, the corresponding thermal spraying equipment is selected. The adjustment and operation of the equipment must be carried out strictly in accordance with the manufacturer's instructions. 4.2 Basic procedures for spraying ceramics
Taking plasma spraying ceramic coating as an example, the basic operating procedures are listed in Table 1. Table 1 Basic procedures for spraying ceramics
Step 1
Clean the workpiece
Avoid covering the workpiece
Pretreatment of the substrate surface
Ceramic material selection
Tooling
Install the spray gun
Adjust the water source system
Adjust the air source system
Load the material
Start the electrical system
Point the gun and adjust the gun
Spray
Sealing treatment
Fine finishing
Before roughening the substrate surface, according to the requirements, use solvent cleaning, degreasing, heating, etc. to remove all dirt on the surface to be sprayed
Use appropriate masking methods such as rubber, steel, masking tape, etc. to protect all parts that do not require surface pretreatment. Use clean, sharp and appropriate abrasives for sandblasting to achieve the required roughness. According to the needs, the bonding bottom layer can also be sprayed continuously. According to the functional requirements of the coating, select the ceramic coating material (refer to Table A1 in Appendix A), determine the appropriate particle size and particle size distribution. According to the shape and size of the substrate, select the fixture, mechanical turntable and mobile device. According to the needs, select the straight gun head, angled gun head or extended gun head, and select the rotating or movable spray gun bracket. According to the requirements of the equipment manual, adjust the water source and the cooling system. The water temperature at the outlet of the spray gun should not be higher than 15℃. Open the main gas, auxiliary gas and powder feeding gas source according to the procedure, and adjust to the required parameters. Load the powder into the powder hopper or spray bucket of the powder feeder. Start the power supply, start the exhaust fan, and adjust the various electrical parameters. According to the regulations, light the gun, start the arc, and adjust the various parameters to achieve stable and concentrated beams, obtain the best flame flow, make the ceramic particles fully molten or at least fully softened, have the best particle speed, and form the best coating quality. Ensure that the travel speed of the spray gun is uniform as much as possible and keep the spray distance unchanged. According to the thermal sensitivity of the substrate, coating characteristics and thickness, select the travel speed and spray distance of the spray gun, and select the optimal powder feeding rate. For corrosion-resistant and insulating coatings, the hole sealing treatment should be carried out immediately after spraying. If necessary, grinding can be carried out, and the hole sealing treatment is often carried out before grinding. 3
4.3 Substrate surface and preparation and pretreatment
4.3.1 Substrate surface and processing requirements
JB/T 7703-95
The design and processing requirements of the substrate surface for specific products (such as surface roughness, geometric tolerance, chamfer, undercut, etc.) are implemented by the special standards for specific products.
4.3.2 Pretreatment of the substrate surface
The quality of the substrate surface pretreatment directly affects the bonding performance between the coating and the substrate. It is one of the key links for the success of the entire thermal spraying process and should be highly valued. It is particularly important to point out that the compressed air used for sandblasting and spraying must be dry and oil-free; the abrasive used for sandblasting should be clean and sharp to ensure that the substrate surface is clean, fully roughened, and freshly activated. The surface is not allowed to be contaminated after pretreatment. The substrate surface pretreatment shall be carried out in accordance with the provisions of GB11373. The surface of the steel workpiece substrate to be sprayed with ceramic coating should be sandblasted to the highest level, "white", that is, Sa3 level.
4.4 Thermal Spraying Process
The correct thermal spraying process should make the ceramic powder particles to be sprayed in a molten or very soft state and sprayed at high speed onto the pretreated substrate surface to form a high-quality coating.
There are many factors that affect the thermal spraying process, mainly including coating materials (melting point, heat capacity, thermal conductivity of ceramic materials and particle size and particle size distribution of powder); heat source (temperature and temperature distribution of flame flow, flame flow velocity and velocity distribution, heat transfer rate of flame flow to ceramic particles, particle velocity and particle residence time in flame flow); substrate (properties and geometric dimensions of substrate, required coating thickness) and coating Layer performance (coating porosity requirements, etc.) should be considered comprehensively. 4.4.1 Shielding and temperature control of the substrate
4.4.1.1 Shielding of the substrate: Before spraying, the area in contact with the spraying area should be shielded to prevent the spray particles from adhering to these areas.
Commonly used masking materials include steel strips, copper strips, special engineering strips for thermal spraying or other equivalent materials. In product production, it is more economical to use permanent masking parts (such as shields). Water-based anti-stick masking paint can also be used to evenly apply to areas that do not need to be sprayed. 4.4.1.2 Preheating of the substrate: Before spraying, the substrate can be evenly preheated to not less than 120°C to remove moisture. However, the substrate temperature must be carefully controlled and must not exceed 250°C, otherwise it will easily lead to oxidation of the substrate surface. The surface reduces the bonding performance. 4.4.1.3 Control of substrate overheating: When spraying ceramic coatings on thin-walled parts or substrates that are prone to deformation and structural changes (such as some aluminum alloys), be careful to avoid overheating of the substrate.
When spraying thick ceramic coatings, the insulation effect of the sprayed coating and the temperature gradient accumulated in the coating may cause problems with the coating.
Overheating of the workpiece may cause layered cracks or delamination of the coating after cooling to room temperature. Adjust the distance from the spray gun to the substrate, adjust the movement speed of the spray gun and the linear speed of the workpiece to fully dissipate heat and cool the substrate, which is beneficial to prevent failure caused by overheating of the substrate. Auxiliary cooling air can also be provided to prevent overheating of the workpiece. 4.4.2 Control of thermal spraying process parameters
4 4.2.1 Spraying equipment: Different thermal spraying equipment produces different flame flow temperatures and velocities. Different spray gun structures and even nozzle models also affect the characteristics of the flame flow. Therefore, the corresponding spraying equipment, spray gun and nozzle structure should be selected according to the selected ceramic coating material. 4.4.2.2 Power supply: The electric power of the plasma spraying process directly affects the temperature and velocity of the plasma flame flow, thereby affecting the melting state and particle velocity of the ceramic particles. Adjusting the flow and pressure of the main gas and auxiliary gas to ensure the optimization of the plasma electric power is crucial to obtaining high-quality coatings.
4.4.2.3 Spraying distance: When the ceramic particles in the jet flame flow hit the substrate surface at the maximum speed, the distance between the nozzle and the substrate is the optimal spraying distance. The spraying distance of the plasma spraying process varies between 6 and 20 cm. The smaller the spray distance, the denser the coating and the better the bonding strength, but the substrate is prone to overheating: the larger the spray distance, the higher the coating porosity and the lower the bonding strength. The optimal spraying distance should be determined and maintained through experiments. Use mechanical devices for spraying as much as possible, and install the spray gun in a fixed manner, which is conducive to reducing human influence, keeping the spray distance unchanged, and the moving speed of the spray gun uniform.
4.4.2.4 Spray gun moving speed and workpiece linear speed: The reasonable matching of the spray gun moving speed and the workpiece moving linear speed has an important influence on the A
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thickness of each coating, the uniformity of the coating and the heating condition of the substrate, and should be determined and maintained through experiments. 4.4.2.5 Powder feeding rate and coating thickness control: The powder feeding rate should be appropriately adjusted according to factors such as the density, melting point, heat capacity, thermal conductivity, and particle size of the ceramic powder material. In short, the maximum powder feeding amount that can make almost all ceramic particles melt in the plasma flame flow should be appropriate. If the powder feeding rate is too large, some unmelted "green particles" will be produced, affecting the coating quality: if the powder feeding rate is too small, the deposition rate will be reduced and the substrate will be easily overheated. The optimal powder feeding rate should be determined and maintained by experiments. The thickness of the ion-sprayed ceramic coating surface can be adjusted between tens of microns and several millimeters. The thickness of the water-stabilized plasma sprayed ceramic coating can reach 20mm. It is generally appropriate for the spray gun to deposit about 0.025mm in a single pass on the base surface, and to ensure complete coverage of the substrate, the minimum average thickness is usually about 0.075mml. The thickness requirements for specific ceramic coatings should be determined by tests based on the requirements of service conditions. 4.4.2.6 Operator experience: In addition to modern computer-controlled plasma spray robots, the thermal spraying process is also greatly affected by the experience and skills of the operator, and the problems encountered in the thermal spraying of ceramic materials are different from those of traditional metal spraying. Therefore, the relevant personnel should be trained more systematically and fully familiar with the process procedures before they can take up their posts for actual operation. 4.5 Sealing and rough processing of ceramic coatings 4.5.1 Sealing treatment
All thermal sprayed ceramic coatings have some pores. The porosity varies greatly. The porosity of explosion spraying and supersonic flame spraying accounts for only 1% of the coating volume, while the porosity of special porous ceramic coatings can be as high as 30%. Most of these pores are interconnected. Therefore, the coating is permeable to liquids and gases. To prevent the possible penetration or corrosion of liquids and gases to the substrate, these pores must be sealed. The selection of sealing agent should be determined according to the use conditions of the coating (corrosion resistance, insulation, heat resistance, etc.)
For corrosion-resistant coatings with different service temperatures, a series of sealing materials are available: microcrystalline wax can be used for sealing under conditions below 60°C; for conditions of use between 60 and 250°C, some resin-based sealing agents are effective, and some silicone-based resin sealing agents can be used for a long time at 450°C. When the temperature exceeds 450°C, inorganic high-temperature resistant coatings can be used for sealing. To correctly select the sealer suitable for specific conditions, it is best to consult the relevant manufacturers and obtain all relevant physical and chemical properties. The methods of applying the sealer include vacuum impregnation, spraying and brushing. For the pores in thermal sprayed ceramic coatings, spraying and brushing methods can usually be effectively sealed.
4.5.2 Finishing
The surface roughness R value of thermal sprayed ceramic coatings is generally more than 3.75um. Many applications require a smaller surface roughness, which can be achieved by grinding finishing. The grinding finishing of ceramic coatings is the final key link in the process of spraying ceramic coating products. If it is not handled properly, all the previous efforts will be wasted.
Because ceramic coatings are brittle, have low bonding strength with the substrate, are thin, and have certain pores in the coating, the grinding of ceramic coatings is significantly different from the grinding of integral materials: 4.5.2.1 Grinding equipment: Traditional grinders can be used for grinding ceramic coatings, but the grinders are required to have good rigidity and small vibration. 4.5.2.2 Abrasives and grinding tools: In order to achieve the best grinding efficiency and economy, it is best to use a diamond grinding wheel for rough grinding and then a fine green silicon carbide grinding wheel for fine grinding. The abrasive particle size and binder used for the grinding wheel should be selected according to the specific purpose. 4.5.2.3 Grinding fluid: When grinding ceramic coatings, a large flow of coolant should be used to prevent any local overheating. It is best to use water containing corrosion inhibitors as the coolant, and do not use water-based emulsified oil coolants, which can easily cause the coating to be contaminated and discolored. 4.5.2.4 Grinding process parameters: When grinding ceramic coatings, it should be avoided that the grinding wheel squeezes the coating to produce microcracks or cracks. Therefore, the grinding wheel linear speed and feed rate should be kept small. The specific parameters should be determined through experiments. 5 Ceramic coating quality inspection
5.1 Inspection items and inspection methods
5.1.1 Appearance
Visual inspection of the effective surface should be uniform in color, and no cracks, bumps, weak bonding, foreign matter adhesion or other defects that are harmful to use are allowed.
5.1.2 Thickness
JB/T 7703-95
Use a measuring tool to directly measure the thickness of the coating, or use a metallographic method to measure the thickness of the coating cross section, or use a non-destructive thickness gauge. Follow the provisions of GB6467 or GB11374. The thickness should meet the requirements of the agreement. 5.1.3 Bonding strength
The bonding strength between the coating and the substrate shall be tested in accordance with GB8642. It shall meet the requirements of the agreement. 5.1.4 Hardness
The hardness of the wear-resistant ceramic coating shall be measured in accordance with the provisions of GB9790 and shall meet the requirements of the agreement. 5.1.5 Porositywww.bzxz.net
The porosity of the corrosion-resistant coating after sealing shall be checked by the iron reagent method. There shall be no pores on the coating surface leading to the substrate. 5.1.6 Thermal shock resistance
The thermal shock resistance of the heat-resistant coating shall be tested by the following method. The coating shall not be allowed to crack, peel or warp. Test method: Use the product as the sample, or use the same material and prepare the sample under the same conditions as the product. The substrate size is 50mm long, 50mm wide and 5-6mm thick. Adjust the test temperature, i.e. 800℃ for alumina and 900℃ for zirconia. Then, put the sample and the bracket into the heating furnace for heating. After reaching the temperature, keep the temperature for 10 minutes and take it out. Then put them into clean water at room temperature for quenching. Observe whether the coating on the surface of the sample has cracks, peeling or warping. The heating furnace uses a resistance furnace with a temperature fluctuation range of ±5℃. It is best to use stainless steel as the bracket and stainless steel wire mesh as the support surface.
5.1.7 Other properties
Other properties of ceramic coatings, such as friction coefficient, emissivity, dielectric constant, requirements for microstructure, etc., can be tested according to the methods specified in the agreement.
5.2 Items to be tested
All ceramic coatings, in addition to the appearance must meet the requirements of Article 5.1.1, are recommended to be tested according to the following items according to their different applications.
5.2.1 Ceramic coatings for wear resistance
Required to test thickness, bonding strength and hardness. Carry out in accordance with the provisions of Articles 5.1.2, 5.1.3 and 5.1.4 respectively. And meet the requirements. 5.2.2 Ceramic coatings for corrosion resistance
Required to test thickness, bonding strength and porosity. Carry out in accordance with the provisions of Articles 5.1.2.5.1.3 and 5.1.5 respectively. And meet the requirements. 5.2.3 Ceramic coatings for heat resistance
Required to test thickness and thermal shock resistance. Carry out in accordance with the provisions of 5.1.2 and 5.1.6 respectively, and meet the requirements. 6 Safety of thermal spraying ceramic coating operation
Thermal spraying ceramic coating is a high-temperature spraying operation using combustible gas or inert gas. It must be stored, transported and used in strict accordance with the relevant regulations on high-pressure, flammable and explosive gases. Operators must be familiar with and master the safe operating procedures of thermal spraying equipment and processes. Only after obtaining a certificate of qualification can the operation be carried out. The safe operation of spraying ceramic coating shall be carried out in accordance with the provisions of GB11375. 7 Marking, packaging and storage and transportation of thermal spraying ceramic coating products 7.1 Marking
Thermal spraying ceramic coating products should have a signboard with at least the following content: product name, coating design code, production date, production batch number, inspection certificate, manufacturer.
7.2 Packaging and storage and transportation
Thermal spraying ceramic coating products should be packaged in single pieces such as shockproof foam plastics and transported in wooden boxes or containers. It is strictly forbidden to drop or hit. There should be a "fragile" mark on the packing box.
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Visual inspection of the effective surface should be uniform in color, without cracks, lumps, weak bonding, foreign matter adhesion or other defects that are harmful to use.
5.1.2 Thickness
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Use a measuring tool to directly measure the thickness of the coating, or use a metallographic method to measure the thickness of the coating cross section, or use a non-destructive thickness gauge. Follow the provisions of GB6467 or GB11374. The thickness should meet the requirements of the agreement. 5.1.3 Bonding strength
The bonding strength between the coating and the substrate shall be tested in accordance with GB8642 and shall meet the requirements of the agreement. 5.1.4 Hardness
The hardness of the wear-resistant ceramic coating shall be measured in accordance with the provisions of GB9790 and shall meet the requirements of the agreement. 5.1.5 Porosity
The porosity of the corrosion-resistant coating after sealing shall be checked by the iron reagent method. There shall be no pores on the coating surface that lead to the substrate. 5.1.6 Heat Shock Resistance
The heat shock resistance of the heat-resistant coating shall be tested according to the following method. The coating shall not be allowed to crack, peel or warp. Test method: Use the product as the sample, or use the same material and prepare the sample under the same conditions as the product. The substrate size is 50mm long, 50mm wide and 5-6mm thick. Adjust the test temperature, that is, 800℃ for alumina and 900℃ for zirconia. Then, put the sample and the bracket into the heating furnace for heating. After reaching the temperature, keep the temperature for 10 minutes and take it out. Then put them into clean water at room temperature for quenching. Observe whether the coating on the surface of the sample has cracks, peeling or warping. The heating furnace uses a resistance furnace with a temperature fluctuation range of ±5℃. It is best to use stainless steel as the bracket and stainless steel wire mesh as the support surface.
5.1.7 Other properties
Other properties of ceramic coatings, such as friction coefficient, emissivity, dielectric coefficient, requirements for microstructure, etc., can be tested according to the methods specified in the agreement.
5.2 Items to be inspected
For all ceramic coatings, in addition to the appearance that must meet the requirements of Article 5.1.1, it is recommended to inspect the following items according to the agreement depending on their application.
5.2.1 Ceramic coatings for wear resistance
Required to inspect thickness, bonding strength and hardness. Carry out in accordance with the provisions of Articles 5.1.2, 5.1.3 and 5.1.4 respectively, and meet the requirements. 5.2.2 Ceramic coatings for corrosion resistance
Required to inspect thickness, bonding strength and porosity. Carry out in accordance with the provisions of Articles 5.1.2, 5.1.3 and 5.1.5 respectively, and meet the requirements. 5.2.3 Ceramic coatings for heat resistance
Required to inspect thickness and thermal shock resistance. Carry out in accordance with the provisions of Articles 5.1.2 and 5.1.6 respectively, and meet the requirements. 6 Operational safety of thermal spraying ceramic coatings
Thermal spraying ceramic coatings are sprayed at high temperature using combustible gas or inert gas. They must be stored, transported and used in strict accordance with the relevant regulations on high pressure, flammable and explosive gases. Operators must be familiar with and master the safety operating procedures of thermal spraying equipment and processes. Only after obtaining a certificate of conformity can the operation be carried out. The safe operation of spraying ceramic coatings shall be carried out in accordance with the provisions of GB11375. 7 Marking, packaging and storage and transportation of thermal spraying ceramic coating products 7.1 Marking
Thermal spraying ceramic coating products should have a signboard with at least the following contents: product name, coating design code, production date, production batch number, inspection certificate, and manufacturer.
7.2 Packaging and storage and transportation
Thermal spraying ceramic coating products should be packaged in single pieces such as shockproof foam plastics and transported in wooden boxes or containers. It is strictly forbidden to drop or hit them. The packaging box should have a "fragile" product mark.
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Visual inspection of the effective surface should be uniform in color, without cracks, lumps, weak bonding, foreign matter adhesion or other defects that are harmful to use.
5.1.2 Thickness
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Use a measuring tool to directly measure the thickness of the coating, or use a metallographic method to measure the thickness of the coating cross section, or use a non-destructive thickness gauge. Follow the provisions of GB6467 or GB11374. The thickness should meet the requirements of the agreement. 5.1.3 Bonding strength
The bonding strength between the coating and the substrate shall be tested in accordance with GB8642 and shall meet the requirements of the agreement. 5.1.4 Hardness
The hardness of the wear-resistant ceramic coating shall be measured in accordance with the provisions of GB9790 and shall meet the requirements of the agreement. 5.1.5 Porosity
The porosity of the corrosion-resistant coating after sealing shall be checked by the iron reagent method. There shall be no pores on the coating surface that lead to the substrate. 5.1.6 Heat Shock Resistance
The heat shock resistance of the heat-resistant coating shall be tested according to the following method. The coating shall not be allowed to crack, peel or warp. Test method: Use the product as the sample, or use the same material and prepare the sample under the same conditions as the product. The substrate size is 50mm long, 50mm wide and 5-6mm thick. Adjust the test temperature, that is, 800℃ for alumina and 900℃ for zirconia. Then, put the sample and the bracket into the heating furnace for heating. After reaching the temperature, keep the temperature for 10 minutes and take it out. Then put them into clean water at room temperature for quenching. Observe whether the coating on the surface of the sample has cracks, peeling or warping. The heating furnace uses a resistance furnace with a temperature fluctuation range of ±5℃. It is best to use stainless steel as the bracket and stainless steel wire mesh as the support surface.
5.1.7 Other properties
Other properties of ceramic coatings, such as friction coefficient, emissivity, dielectric coefficient, requirements for microstructure, etc., can be tested according to the methods specified in the agreement.
5.2 Items to be inspected
For all ceramic coatings, in addition to the appearance that must meet the requirements of Article 5.1.1, it is recommended to inspect the following items according to the agreement, depending on their application.
5.2.1 Ceramic coatings for wear resistance
Required to inspect thickness, bonding strength and hardness. Carry out in accordance with the provisions of Articles 5.1.2, 5.1.3 and 5.1.4 respectively, and meet the requirements. 5.2.2 Ceramic coatings for corrosion resistance
Required to inspect thickness, bonding strength and porosity. Carry out in accordance with the provisions of Articles 5.1.2, 5.1.3 and 5.1.5 respectively, and meet the requirements. 5.2.3 Ceramic coatings for heat resistance
Required to inspect thickness and thermal shock resistance. Carry out in accordance with the provisions of Articles 5.1.2 and 5.1.6 respectively, and meet the requirements. 6 Operational safety of thermal spraying ceramic coatings
Thermal spraying ceramic coatings are sprayed at high temperature using combustible gas or inert gas. They must be stored, transported and used in strict accordance with the relevant regulations on high pressure, flammable and explosive gases. Operators must be familiar with and master the safety operating procedures of thermal spraying equipment and processes. Only after obtaining a certificate of conformity can the operation be carried out. The safe operation of spraying ceramic coatings shall be carried out in accordance with the provisions of GB11375. 7 Marking, packaging and storage and transportation of thermal spraying ceramic coating products 7.1 Marking
Thermal spraying ceramic coating products should have a signboard with at least the following contents: product name, coating design code, production date, production batch number, inspection certificate, and manufacturer.
7.2 Packaging and storage and transportation
Thermal spraying ceramic coating products should be packaged in single pieces such as shockproof foam plastics and transported in wooden boxes or containers. It is strictly forbidden to drop or hit them. The packaging box should have a "fragile" product mark.
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