A glass powder and a preparation process thereof, in particular to a glass powder for plasma spraying ceramic coating modification and a preparation process thereof.
With the continuous development of modern science and technology, the corrosive environment of various industrial sectors, especially metallurgy, chemical industry, aerospace, energy and other sectors, has become more and more harsh, and the corrosion problem has become more and more serious. In some cases, when ordinary metal materials and even special alloy materials are difficult to meet their corrosion resistance requirements, ceramic coatings show their unique corrosion resistance and are more and more widely used. Most ceramic materials show strong chemical inertness due to their stable crystal structure and strong chemical bonding force, and are not easily corroded by free electron transfer like metal materials. In the natural environment, including the atmosphere, water and other environments, the corrosion rate of ceramic materials is very small, and the ceramic coating is often obtained on the surface of the metal substrate by plasma spraying for the field of corrosion resistance. Plasma spraying is a spraying method in which high-quality composite coatings are obtained by melting high-melting-point materials through high-temperature, high-speed, high-enthalpy flame flow with plasma arc as heat source, and is especially suitable for preparing ceramic coatings. Due to the advantages of high hardness, high corrosion resistance and wear resistance, ceramic coatings are widely used in mechanical surface protection. Among various ceramic coatings, Al2O3-13wt.%TiO2 (AT13) composite oxide ceramic coating has been widely used in nearly 100 kinds of parts and components of aerospace, military, water conservancy and other related equipment. However, since the plasma spraying process determines the layered structure of the obtained coating, defects such as pores and micro-cracks are inevitably generated during the spraying process. The existence of these defects provides a channel for the penetration of corrosive media. In a corrosive environment, the corrosive medium reaches the coating/metal interface through the defects of the ceramic layer, and serious electrochemical corrosion occurs on the metal surface. Once the corrosive liquid infiltrates, the corrosion reaction develops rapidly, the corrosion products expand, and the residual residue inside the ceramic coating The stress causes the micro-cracks to expand, causing the coating to crack and peel, which greatly reduces the service life of the coating in a corrosive environment and limits the application of plasma sprayed ceramic coatings in the corrosion-resistant industry. The existence of structural defects such as pores and cracks in the coating not only reduces the corrosion resistance of the coating, but also reduces the mechanical properties of the coating. The generation of cracks even affects the bonding properties of the coating. It can be seen that improving the density of the coating, reducing the porosity or closing the pores is one of the key elements to improve the service life of the coating.
Over the years, many scholars have carried out research on improving the density of coatings and improving the corrosion resistance of ceramic coatings, which can be mainly divided into process improvement and post-treatment. Since the characteristics of the plasma spraying process itself determine the existence of defects, the degree of density enhancement through process improvement methods is limited. There are also many post-treatment methods, such as sealing treatment, that is, sealing the pores, through-holes and micro-cracks on the surface of the coating to improve the corrosion resistance and wear resistance of the coating. In recent years, a variety of sealing methods have been developed at home and abroad, such as direct sealing with sealing agents, sealing with sol-gel, heating diffusion-laser irradiation, etc., and sealing with the properties of powder materials themselves. Hole processing and electroplating sealing methods.
Sol-gel sealing can increase the density of the coating and improve the bonding strength, but the temperature control is strictly limited, and it is difficult to obtain satisfactory results. When the temperature exceeds 300°C, due to the inorganicization of the sealing agent itself, a strong vitreous sealing layer is formed, and at the same time, a large shrinkage occurs, and the sealing layer is cracked again, which deteriorates the corrosion resistance. Using laser irradiation for hole sealing treatment can obtain a dense surface layer, but the laser process parameters are not easy to control, and too high power may cause problems such as cracks and peeling of the ceramic coating. In response to this problem, Liscano et al. used an organic sealing agent to infiltrate the ceramic coating in advance, and then used laser remelting to obtain good results. However, the cost of laser remelting is high, and it is easy to generate secondary stress inside the coating, which reduces the bonding performance of the coating.
Using the properties of the powder material itself to seal the pores is also a common treatment method at present. Some use some metal-ceramic composite powders to have a good self-sealing effect, so that the micropores in the coating are welded by themselves, forming a dense and non-porous Coating, such as patent No. 201510591945.X. Sealing agent direct sealing method has been widely used due to its simple operation and easy implementation, but the corrosion resistance effect of this method is limited by the properties of the sealing agent, which cannot fundamentally solve the problem and achieve long-term corrosion resistance.
Whether the prepared coating is subjected to post-heating treatment to bridge the micro-cracks inside the coating and improve the coating density, or to seal the pores with organic resin, it cannot meet the actual needs of good effect and low cost, and the heating effect is not good. Significantly, organic resin can improve the corrosion resistance of the coating, but it increases the cost virtually, and the post-treatment method can only cure the symptoms but not the root cause. Therefore, consider starting from the source to improve the properties of the spray powder, thereby improving the quality of the coating. Taking Al2O3-13wt.%TiO2 commonly used in plasma spraying as an example, the morphology and particles of the powder are polygonal rather than circular, which determines that the droplets obtained by high-speed and high-enthalpy heating by plasma flame cannot be completely spread into flat sheets. , that is, there are a lot of pores in the coating obtained after the droplet spreading.
Glass powder is an amorphous amorphous substance with no fixed melting point but a low softening temperature. As the temperature increases, the viscosity of the glass melt will decrease significantly, becoming a liquid-like low-viscosity melt with better fluidity. If glass powder is doped into the ceramic powder for spraying, it is bound to increase the fluidity of the molten powder to spread, play the role of a high-temperature inorganic binder, and fill the pores between the ceramic particles, fundamentally reduce the porosity, and form a denser coating. Whether the glass powder can fully fill the pores and bond with the ceramic material depends on the fluidity of the glass powder in the molten state and the wetting of the glass powder and the ceramic material. The introduction of Sb2O3 into the formula can reduce the transition temperature of the glass. Improve the fluidity of glass and improve the chemical stability of glass. In addition, both Sb2O3 and Cr2O3 can reduce the surface tension of glass, among which Cr2O3 has the most significant effect. The reduction of surface tension can reduce the wetting angle between glass and ceramic materials, thereby improving its wetting effect, so that the glass melt can be fully filled into the ceramic pores. middle.
Silicate glass is one of the commonly used glass systems, with high chemical stability, wide glass-forming region, easy to form amorphous glass, and low cost. Therefore, silicate glass powder with high chemical stability was developed and doped into the ceramic powder in an appropriate proportion to prepare a glass powder-doped AT13 ceramic coating with dense and excellent corrosion resistance, which is expected to realize the ceramic coating. long-lasting corrosion protection.
Based on the rich practical experience and professional knowledge in the design and manufacture of such products for many years, and the application of the theory, the inventor actively conducts research and innovation, in order to create a glass powder that can improve the corrosion resistance of plasma sprayed ceramic coatings and its preparation technology to make it more practical. After continuous research, design, and repeated trial production of samples and improvements, the present invention with practical value was finally created.
Technical implementation elements:
The main purpose of the present invention is to overcome the defects of the existing corrosion-resistant ceramic coating treatment methods, and provide a glass powder for plasma spraying ceramic coating modification and a preparation method thereof, which is more suitable for practical use and has industrial advantages. use value.
The purpose of the present invention and the solution to its technical problems are achieved by adopting the following technical solutions.
A glass powder for plasma spraying ceramic coating modification, calculated according to mass percentage, comprising the following components,
SiO2: 55~59%,
CaO: 8~11%,
MgO: 2~5%,
Al2O3: 5~15%,
K2O: 2~5%,
Na2O: 10~15%,
R2O3: 0.8~1.8%.
Further, the R2O3 includes one or a combination of Cr2O3 and Sb2O3.
Further, the R2O3 includes Cr2O3 and Sb2O3, and the mass percentage of the Cr2O3 is 0.5-1%, and the mass percentage of the Sb2O3 is 0.3-0.8%.
A preparation method of glass powder for plasma spraying ceramic coating modification, comprising the following operation steps:
Step 1, ingredients: weigh the constituent raw materials of the glass powder in proportion;
Step 2, mixing: fully stirring the constituent raw materials weighed in the step 1, and mixing evenly to obtain batching materials;
Step 3, preheating: carrying out preheating treatment on the batching material that was mixed evenly in the step 2;
Step 4, melting: the batching material preheated in step 3 is melted to obtain molten glass;
Step 5, forming: pouring the melted and clarified glass liquid into a preheated graphite mold to form a glass sample;
Step 6, annealing: annealing the formed glass sample, and cooling with the furnace;
Step 7, into powder: break and grind the glass sample formed in the step 6 to obtain the glass powder.
Further, the preheating in step 3 is performed in an annealing furnace.
Further, the melting in the fourth step is carried out in a high temperature furnace.
Further, during the melting process in the fourth step, the heating temperature is 1600° C., and the temperature is kept for 2 hours.
Further, during the annealing in the sixth step, the annealing temperature is 750°C.
Further, the glass powder obtained in the seventh step is passed through a 500-mesh sieve.
A method for using glass powder for plasma spraying ceramic coating modification. The glass powder is prepared by doped AT13 powder, and the glass powder and the ceramic powder are fully mixed in a mass ratio of 1: (5~20) to obtain a mixed powder.
By adopting the above technical solution, the following technical effects can be achieved:
In the present invention, the glass powder matching the performance parameters such as particle size and fluidity of the existing ceramic powder is doped into the ceramic powder in an appropriate ratio, fully filling the pores after the polygonal ceramic particles are formed, and then obtains the glass powder by plasma spraying. Coatings containing crystalline phase and amorphous phase greatly reduce the porosity and micro-cracks of the coating due to the existence of the glassy state, thereby improving the density of the ceramic coating, greatly improving the service life of the coating, thereby expanding its coating. The scope of application has important practical value and economic significance.
Description of drawings
Figure 1 shows the morphology and element distribution of glass powder doped AT13 powder in Example 1 of the present invention, wherein (a) is the morphology of glass powder doped AT13 powder, (b) is the energy spectrum analysis of glass powder doped AT13 powder ;
Figure 2 shows the morphology and element distribution of the glass powder doped AT13 coating in Example 1 of the present invention, wherein (a) is the morphology of the glass powder doped AT13 coating, and (b) is the energy spectrum analysis of the glass powder doped AT13 coating ;
Figure 3 shows the morphology and element distribution of the glass powder in Example 2 of the present invention, wherein (a) is the morphology of the glass powder, and (b) is the energy spectrum analysis of the glass powder;
Figure 4 shows the surfaces of the glass powder doped ceramic coating and the single ceramic coating of the present invention immersed and corroded for 1000 hours, wherein (a) is the glass powder doped AT13 coating, and (b) is the pure AT13 ceramic coating.
Detailed ways
In order to further illustrate the technical means and effects adopted by the present invention to achieve the predetermined purpose of the invention, a kind of glass powder for plasma spraying ceramic coating modification, its preparation method and its application according to the present invention are described in detail. Its effect is described in detail as follows.
The present invention provides a glass powder for plasma spraying ceramic coating modification, which is calculated according to mass percentage and includes the following components:
SiO2: 55~59%,
CaO: 8~11%,
MgO: 2~5%,
Al2O3: 5~15%,
K2O: 2~5%,
Na2O: 10~15%,
R2O3: 0.8~1.8%.
R2O3 includes one or a combination of Cr2O3 and Sb2O3, preferably R2O3 includes Cr2O3 and Sb2O3, and the mass percentage of Cr2O3 is 0.5-1%, and the mass percentage of Sb2O3 is 0.3-0.8%.
In addition, the present invention also provides a preparation method of glass powder for plasma spraying ceramic coating modification, comprising the following operation steps:
Step 1, ingredients: weigh the constituent raw materials of the glass powder in proportion;
Step 2, mixing: fully stir the constituent raw materials weighed in step 1, and mix them evenly to obtain batching materials;
Step 3, preheating: preheating the uniformly mixed batch materials in step 2;
Step 4, melting: the batching material preheated in step 3 is melted to obtain molten glass;
Step 5, forming: pour the melted and clarified glass liquid into a preheated graphite mold to form a glass sample;
Step 6, annealing: the formed glass sample is annealed and cooled with the furnace;
Step 7, powder formation: break and grind the glass sample formed in step 6 to obtain glass powder.
The preheating in step 3 is performed in an annealing furnace.
The melting in step 4 is carried out in a high temperature furnace. And in the fourth step of melting, the heating temperature is 1600° C., and the temperature is kept for 2 hours.
During the annealing in step 6, the annealing temperature is 750°C, and the furnace is cooled.
The glass powder obtained in step 7 is passed through a 500-mesh sieve to obtain glass powder with moderate particle size.
The invention also provides a method for using glass powder for plasma spraying ceramic coating modification. The glass powder is prepared by doping AT13 powder, and the glass powder and the ceramic powder are fully mixed in a mass ratio of 1: (5~20) to obtain Mix powder.
In order to further illustrate the present invention, the glass powder for plasma spraying ceramic coating modification provided by the present invention, its use method and its use method are described in detail below with reference to specific embodiments.
Example 1
Ingredients: Calculated according to mass percentage, weigh the following components: SiO2: 55%, CaO: 10%, MgO: 2%, Al2O3: 13%, K2O: 2%, Na2O3: 17.2%, Cr2O3: 0.5%, Sb2O3 : 0.3%.
Example 2
Ingredients: Calculated by mass percentage, weigh the following components: SiO2: 58.2%, CaO: 10%, MgO: 5%, Al2O3: 11.5%, K2O: 3%, Na2O: 11%, Cr2O3: 0.8%, Sb2O3 : 0.5%.
The above Examples 1 and 2 are prepared by the following methods: according to the components listed in Example 1 or 2 and their proportions, take each component raw material and fully stir, mix evenly, and obtain a batch material, and the above-mentioned weighed composition raw materials are fully Stir and mix evenly to obtain the batching material. The above-mentioned uniformly mixed batches were preheated in an annealing furnace, and the temperature in the annealing furnace was set to 750°C. The preheated batch is melted in a high temperature furnace, and the heating temperature is 1600 ° C
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