A vitreous enamel coating highly thermally matched to a metal substrate and a method for producing the same

Abstract

This invention provides an enamel coating with high thermal compatibility with a metal substrate and its preparation method, belonging to the field of surface protective coating technology. The enamel coating is characterized by core-shell structured multiphase quartz particles dispersed within the enamel matrix. By ball milling the original single-phase quartz particles to obtain fine quartz particles with fresh cleavage surfaces, and then activating them at high temperature to obtain core-shell structured multiphase quartz particles, these are added to the enamel glaze matrix to obtain an enamel coating with high thermal compatibility with the metal substrate. This effectively solves the problem of cracking and peeling of enamel coatings due to insufficient thermal compatibility with the metal substrate. The technical solution provided by this invention is energy-saving, environmentally friendly, low-cost, and its process stability and controllability are superior to existing technologies.

Description

Technical Field

[0001] This invention belongs to the field of surface engineering and protective coating technology, specifically relating to an enamel coating that is highly thermally matched with a metal substrate and its preparation method. Background Technology

[0002] Enamel coating, as a time-honored technology, continues to play a unique and irreplaceable role in modern industry. For example, hot-end components of aircraft engines operating in marine environments face severe high-temperature corrosion challenges. Research by Russian and Chinese researchers in this field shows that enamel coatings exhibit significantly superior high-temperature corrosion resistance compared to traditional alloy coatings. It has been reported that due to the high density of the glassy state of enamel coatings, some hot-end components of the Russian PD120 liquid oxygen / kerosene high-pressure staged combustion rocket engine also utilize enamel coatings for fire-resistant protection. Furthermore, Russia has also achieved good results in resisting hydrogen permeation in nuclear reactor components. Thermal storage water heaters require enamel coatings to enhance their corrosion resistance. Thermal power plants utilize the acid resistance of enamel coatings to improve the corrosion resistance of air preheaters. Clearly, the ancient enamel technology continues to play a vital role in modern industry. However, it is well known that enamel coatings typically have a much lower coefficient of thermal expansion than commonly used metal materials, leading to frequent enamel chipping due to excessive thermal stress. Therefore, improving the thermal compatibility between the enamel coating and the metal substrate is crucial for enhancing the service life and safety of the enamel coating.

[0003] Current reports on improving the anti-stripping performance of enamel coatings include two approaches. One approach is to redesign and optimize the enamel glaze formulation [see reference: Chen Tao, A High-Performance Enamel Glaze, Chinese Patent, CN201210548990.3], thereby achieving comprehensive performance compatible with the metal substrate. However, the effectiveness of this method is limited by the type of metal substrate. Another approach is to enhance its strength by adding refractory ceramic oxide particles such as alumina or metal particles [see reference: Du Zhuan, Chen Lin, Meng Guohui, Zhu Changfa, Zhao Ding, Wang Guoqiang, Research Progress on Enamel Coating Modification Technology and Application, Materials Protection, 2023(56)158-168+182], thereby improving its resistance to thermal stress damage. This method has played a role to some extent, but it has failed to solve the problem of thermal compatibility at its source.

[0004] This invention employs a novel approach, utilizing the phase transformation of active multiphase particles in conjunction with the deformation of enamel uranium to achieve a high thermal expansion effect, thus realizing a high degree of thermal matching with the metal substrate. This approach can be based on existing enamel glazes without requiring redesigned formulations or high-temperature melting, and its thermal expansion coefficient can be controlled, making it applicable to various metal substrates. Furthermore, the process is low-cost, energy-efficient, and environmentally friendly. Adopting this approach will more effectively improve the service life and safety of enamel coatings. Summary of the Invention

[0005] This invention provides an enamel coating that is highly thermally matched with a metal substrate and its preparation method, effectively solving the problem that enamel coatings are prone to cracking and peeling due to insufficient thermal expansion coefficients with the metal substrate.

[0006] The technical solution of this invention is:

[0007] A highly thermally compatible enamel coating and its preparation method are disclosed. The enamel coating contains a core-shell structured multiphase quartz particle phase and a silicate enamel glaze matrix phase. The preparation method involves: firstly, ball milling coarse-sized original single-phase quartz particles to obtain fine quartz particles with fresh cleavage surfaces; then, activating the newly prepared fine quartz particles in a high-temperature furnace to obtain core-shell structured multiphase quartz particles; next, mixing the activated multiphase quartz particles into enamel glaze and spraying or brushing them onto the substrate; and finally, controlling the dissolution and phase transformation process of the multiphase quartz particles by adjusting the firing temperature and time to obtain a highly thermally compatible enamel coating with the metal substrate.

[0008] The core-shell structured multiphase quartz particle phase has a core-shell structure consisting of a quartz or phosphorus quartz phase as the shell and a quartz phase as the core.

[0009] The core-shell structured multiphase quartz particles have a particle size of 2-6 micrometers and an initial core / shell size ratio of 100-1000.

[0010] The core-shell structured multiphase quartz granular phase has a particle content of 35%-65% by volume.

[0011] The enamel matrix is ​​a silicate-based glass phase. In addition, it may contain ceramic phase particles such as alumina, zirconium oxide, and chromium oxide with a total volume fraction not exceeding 25%.

[0012] The original single-phase quartz particles have a size of 10-50 micrometers, while the quartz particles with fresh cleavage surfaces obtained by ball milling are controlled to a size of 2-6 micrometers.

[0013] The high-temperature activation furnace has a temperature of 1000℃-1400℃ and an activation time of 2-10 minutes.

[0014] Multiphase quartz particles are mixed into enamel glaze using a slow stirring method, with a speed of 20-200 rpm and a stirring time of 2-5 minutes.

[0015] The firing temperature for enamel is 800℃-1000℃, and the firing time is 10-1200 minutes.

[0016] Advantages of this invention:

[0017] The enamel coating prepared by this invention can achieve the effect of controlling the thermal expansion coefficient of the enamel coating without changing the glass phase composition of the enamel glaze. Therefore, for existing enamel glaze systems, there is no need to redesign the formula and carry out a high-energy-consuming high-temperature melting process, which can significantly improve its thermal compatibility with the metal substrate.

[0018] The preparation method provided by this invention has the advantages of being energy-saving, environmentally friendly, low-cost, and having high process stability and controllability. Attached Figure Description

[0019] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments:

[0020] Figure 1 Thermal expansion curve of multiphase particle-modified enamel coating;

[0021] Figure 2 Microstructure of the enamel coating modified by multiphase particles after phase transformation. Detailed Implementation

[0022] The present invention will be further explained below with reference to specific implementation schemes, but it is not limited to the present invention. The structures, proportions, sizes, etc. shown in the accompanying drawings are only used to complement the content disclosed in the specification, so as to enable those skilled in the art to understand and read, and are not intended to limit the conditions under which the present invention can be implemented. Therefore, they have no substantial technical significance. Any modification of the structure, change of the proportion relationship or adjustment of the size, without affecting the effect and purpose that the present invention can produce, should still fall within the scope of the technical content disclosed in the present invention.

[0023] Example 1

[0024] This embodiment describes an enamel coating with high thermal compatibility with a metal substrate and its preparation method. First, raw single-phase quartz particles with D90 = 50 micrometers are ball-milled for 40 hours to obtain fine quartz particles with D90 = 5 micrometers and fresh cleavage surfaces. Then, these fine quartz particles are activated in a 1050°C furnace for 3 minutes to obtain core-shell structured multiphase quartz particles. The activated multiphase quartz particles are then mixed into enamel glaze at a volume ratio of 55%, stirred at 100 rpm for 5 minutes, sprayed onto the substrate, and fired at 1000°C for 10 minutes. The resulting enamel coating's thermal expansion curve is shown below. Figure 1 As shown, the coefficient of thermal expansion increases by more than 60%.

[0025] Example 2

[0026] This embodiment describes an enamel coating with high thermal compatibility with a metal substrate and its preparation method. First, raw single-phase quartz particles with D90 = 40 micrometers are ball-milled for 20 hours to obtain fine quartz particles with D90 = 4 micrometers and fresh cleavage surfaces. Then, these fine quartz particles are activated in a 1000°C furnace for 4 minutes to obtain core-shell structured multiphase quartz particles. The activated multiphase quartz particles are then mixed into an enamel glaze at a volume ratio of 45%, stirred at 80 rpm for 3 minutes, brushed onto the substrate, and fired at 1000°C for 60 minutes. The resulting enamel coating's thermal expansion curve is shown below. Figure 1 As shown, the coefficient of thermal expansion increases by more than 90% at 200℃.

[0027] Example 3

[0028] This embodiment describes an enamel coating with high thermal compatibility with a metal substrate and its preparation method. First, raw single-phase quartz particles with D90 = 15 micrometers are ball-milled for 10 hours to obtain fine quartz particles with D90 = 3 micrometers and fresh cleavage surfaces. These fine quartz particles are then activated in a 1000°C furnace for 2 minutes to obtain core-shell structured multiphase quartz particles. The activated multiphase quartz particles are then mixed into an enamel glaze at a volume ratio of 45% and 10% alumina, stirred at 150 rpm for 2 minutes, and sprayed onto a substrate. The mixture is then fired at 1000°C for 180 minutes. The resulting enamel coating's thermal expansion curve is shown below. Figure 1 As shown, the coefficient of thermal expansion increases by approximately 400% at 200℃.

[0029] Example 4

[0030] This embodiment describes an enamel coating with high thermal compatibility with a metal substrate and its preparation method. First, raw single-phase quartz particles with D90 = 10 micrometers are ball-milled for 5 hours to obtain fine quartz particles with D90 = 3.5 micrometers and fresh cleavage surfaces. These fine quartz particles are then activated in a 1000°C furnace for 2 minutes to obtain core-shell structured multiphase quartz particles. The activated multiphase quartz particles are then mixed with 45% by volume and 3% by volume of zirconium oxide into an enamel glaze, stirred at 50 rpm for 5 minutes, and sprayed onto a substrate. The mixture is then fired at 1000°C for 1200 minutes. The resulting enamel coating's thermal expansion curve is shown below. Figure 1 As shown, the coefficient of thermal expansion increases by approximately 550% at 200℃. The microstructure morphology of the multiphase particle-modified enamel coating after phase transformation is shown below. Figure 2 As shown. Matters not covered in this invention are common knowledge.

[0031] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. An enamel coating that is highly thermally compatible with a metal substrate, characterized in that: The enamel coating contains core-shell structured multiphase quartz particles and silicate enamel glaze matrix phase; the core-shell structured multiphase quartz particles have an outer shell composed of cristobalite or phosphogypsum phase and an inner core composed of quartz phase; the size of the core-shell structured multiphase quartz particles is 2-6 micrometers, and the initial core / shell size ratio is 100-1000; the content of the core-shell structured multiphase quartz particles is 35%-65% by volume.

2. The enamel coating with high thermal compatibility with the metal substrate according to claim 1, characterized in that: It also contains ceramic phase particles of alumina, zirconium oxide, and chromium oxide in total volume fraction not exceeding 25%.

3. A method for preparing an enamel coating with high thermal compatibility with a metal substrate according to claim 1, characterized in that: The specific preparation method is as follows: ① First, the coarse original single-phase quartz particles are ball-milled to obtain fine quartz particles with fresh cleavage surfaces; ② The fine quartz particles prepared above are put into a high-temperature furnace for activation to obtain core-shell structured multiphase quartz particles; ③ The activated multiphase quartz particles are mixed into enamel glaze and sprayed or brushed onto the substrate; ④ The dissolution and phase transformation process of the multiphase quartz particles are controlled by adjusting the firing temperature and time to obtain an enamel coating that is highly thermally matched with the metal substrate.

4. The method for preparing an enamel coating with high thermal compatibility with a metal substrate according to claim 3, characterized in that: The original single-phase quartz particles have a size of 10-50 micrometers, while the quartz particles with fresh cleavage surfaces obtained by ball milling are controlled to a size of 2-6 micrometers.

5. The method for preparing an enamel coating with high thermal compatibility with a metal substrate according to claim 3, characterized in that: High-temperature activation furnace temperature 1000 o C-1400 o C, activation time 2-10 minutes.

6. The method for preparing an enamel coating with high thermal compatibility with a metal substrate according to claim 3, characterized in that: Multiphase quartz particles are mixed into enamel glaze using a slow stirring method, with a speed of 20-200 rpm and a stirring time of 2-5 minutes.

7. The method for preparing an enamel coating with high thermal compatibility with a metal substrate according to claim 3, characterized in that: The firing temperature of enamel is 800. o C-1000 o C, time 10-1200min.

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