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Thermal Spraying Zirconia Powder
Zirconia coatings are among the most representative functional ceramic coatings used in thermal spraying technology. Their core applications extend far beyond the traditional realms of wear and corrosion resistance, particularly in high-end technological fields.
Product Description
Thermal Spraying Zirconia Powder
Prepared using nano-sized raw materials through a process involving pulping, spray drying, and high-temperature sintering. The thermally sprayed calcium oxide-stabilized zirconia coating remains stabilized in the tetragonal phase and does not transform into the monoclinic phase even during cooling and temperature reduction, thereby ensuring the coating’s thermal cycling and thermal shock resistance.
Let’s do a comprehensive analysis. Thermal Spraying Zirconia Zirconium dioxide ) Powder Performance and applications.
Zirconia coatings are the most representative in thermal spraying technology. Functional ceramic coating First, its core applications extend far beyond the traditional realms of wear and corrosion resistance, especially in high-end technology fields.
I. Core Performance and Key Challenges: Stabilization Treatment
Pure zirconia has a fatal flaw: Phase transition problem It exhibits three crystal structures at different temperatures:
* Monoclinic phase ( m-ZrO₂ ) Room temperature ~1170°C
* Four-way interaction ( t-ZrO₂ ) ： 1170°C ~ 2370°C
* Cubic phase ( c-ZrO₂ ) ： >2370°C
As the coating cools from the high temperature of spraying down to room temperature, Four-way interaction ( t ) will transition to the monoclinic phase ( m ) Transformation and accompanied by 3-5% volume expansion This volume change generates significant stress within the coating, leading to cracking, warping, and even delamination from the substrate.
Solution: Stabilization treatment
To obtain a usable zirconia coating, it is necessary to add [something] to the zirconia powder. Stabilizer (For example, Y₂O₃, MgO, CaO, CeO₂ etc.), enabling it to remain stable even at room temperature. Tetragonal phase or cubic phase Avoid destructive phase transitions.
Therefore, the zirconia powders used in thermal spraying are all... Stabilized zirconia , the most common are:
1. Yttria-stabilized zirconia ( YSZ, Yttria-Stabilized Zirconia ) ： Most mainstream and with the best performance The choice, typically for 7-8% Y₂O₃ (Weight ratio). It offers optimal combined thermal and mechanical performance.
2. Magnesium-stabilized zirconia MSZ, Magnesia-Stabilized Zirconia )
3. Calcium-stabilized zirconia CSZ, Calcia-Stabilized Zirconia )
II. Excellent Performance of Stabilized Zirconia Coatings
After stabilization, the zirconia coating exhibits the following outstanding performance:
1. Extremely low thermal conductivity (the most critical performance)
* Its thermal conductivity is nearly the lowest among all ceramic materials (approximately...). 1.5–2.0 W/m·K , approximately that of aluminum oxide. 1/3 ). This makes it a Excellent thermal insulation material 。
2. Excellent thermal barrier performance ( TBC - Thermal Barrier Coating )
* Combining low thermal conductivity with high-temperature resistance, it can create a significant temperature gradient between high-temperature components and heat sources. ΔT ), effectively protecting metal substrates (such as turbine blades) from high-temperature erosion.
3. Excellent high-temperature stability and resistance to molten metal corrosion
* Melting point as high as 2700°C , can do 1600°C Working for extended periods in the above-mentioned high-temperature environment.
* It exhibits extremely strong resistance to corrosion by molten metals such as aluminum, zinc, copper, and iron, as well as their slag.
4. High toughness and thermal shock resistance
* Compared to other ceramics, zirconia—especially YSZ ) Exhibits relatively high fracture toughness. It has a moderate coefficient of thermal expansion ( ~10×10⁻⁶/°C ) is closer to the metal matrix, therefore Thermal shock resistance (Its ability to withstand rapid temperature changes) is excellent.
5. Chemically inert
* It can resist the corrosion of various chemicals at high temperatures.
III. Major Thermal Spray Processes
The performance of zirconia coatings is strongly dependent on the spraying process; different processes determine the final microstructure and intended applications of the coating.
Process | Applicable Scenarios and Features |
Atmospheric Plasma Spraying APS ) | The most commonly used and cost-effective process The coating exhibits a typical layered structure and a certain porosity. 5-15% ), this microstructure Further reduced thermal conductivity. , very suitable Thermal Barrier Coating ( TBCs ) 。 |
Electron beam - Physical Vapor Deposition (PVD) EB-PVD ) | High-end craftsmanship The coating features a unique columnar crystalline structure, exhibits extremely high strain tolerance, and demonstrates excellent thermal shock resistance. It is primarily used for... Aeroengine high-pressure turbine blade of the TBCs The cost is extremely high. |
Suspension Plasma Spraying (SPS) and Solution Precursor Plasma Spraying (SPPS) | Emerging processes Use liquid. feedstock (suspension or precursor solution), enabling the preparation of new materials with finer microstructures and enhanced durability. TBCs , is a direction for future research. |
IV. Main Uses and Application Fields
The applications of zirconia coatings can be divided into two major fields: Thermal Barrier Coating and Molten-metal-resistant coating 。
(1) Thermal Barrier Coatings TBCs – Thermal Barrier Coatings ) - High-end applications
This is a zirconia coating. The most important and valuable use It is primarily used in the aerospace and energy sectors.
1. Aero Engines and Gas Turbines ：
* Turbine blade Applied as a coating on the surface of nickel-based superalloy blades, it can reduce the blade surface temperature. 100-300°C This allows for an increase in the gas inlet temperature, significantly improving engine efficiency and thrust, or extending blade life.
* Combustion chamber inner wall Protect the combustion chamber from being eroded by high-temperature flames.
2. Diesel engine:
* Piston top 、 Cylinder head 、 Valve Apply to the following areas TBCs It can reduce heat loss, improve thermal efficiency, and lower emissions.
(2) Coatings Resistant to Molten Metal Erosion and Hot Corrosion - Industrial applications
Thanks to its excellent chemical inertness and thermal shock resistance, it finds wide applications in the metallurgical and industrial fields.
1. Metallurgical industry ：
* Continuous casting roll Protect the roller surface from wear and thermal fatigue caused by high-temperature steel billets.
* Molten metal contact component Such as浇注口, flow channels, and thermocouple protective sleeves, which resist erosion by molten aluminum, zinc, steel, and other metals.
2. Glass industry ：
* Components that come into contact with molten glass, such as stirring rods and feed channel components, are designed to prevent glass adhesion and extend component lifespan.
3. Chemical Engineering and Energy ：
* It is also used in certain reactor components that require high-temperature insulation and corrosion protection.
Summary
Feature | Description | Uses it brings |
Extremely low thermal conductivity | One of the best insulating ceramics | Thermal Barrier Coating ( TBCs ) Protecting high-temperature components of engines and gas turbines |
High melting point and chemical inertness | High temperature resistance, resistant to molten metals / Glass erosion | Molten-metal-resistant coating Corrosion-resistant components for metallurgy and the glass industry |
High toughness & Thermal shock resistance | More resistant to rapid temperature changes than other ceramics. | Ensure TBCs Does not peel off under drastic temperature changes. |
Must be stabilized | Add Y₂O₃ Stabilizers prevent phase transitions from causing damage. | To obtain YSZ 、 MSZ Available materials |
In summary, Thermal spraying of zirconia (especially YSZ ) Coating The core value lies in its Excellent thermal insulation performance and Excellent high-temperature performance It is not only indispensable for modern aerospace engines. “ Thermal protective clothing ” It is also a key advanced material for enhancing equipment performance and extending component lifespans in numerous high-temperature industrial applications.
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