Thermal spray technology is a surface processing technique that involves depositing heated spray materials, such as spherical tungsten powder and spherical nickel powder, onto a substrate using high-pressure airflow. It can deposit metals, alloys, metal oxides, and ceramics onto different substrates, providing functionalities such as corrosion resistance, wear resistance, and high-temperature resistance. This versatile process accounts for approximately one-third of the total output value in the field of surface engineering.
The classification of thermal spray processes.
According to the information provided, thermal spraying can be classified into different types based on heat sources. The dominant type is plasma spraying, followed by high-speed flame spraying, which holds a 25% market share. Arc spraying has emerged as the third most popular technique, replacing traditional flame spraying methods.
Plasma spraying
Plasma spraying is a thermal spray method that uses a plasma arc to spray molten or semi-molten powder materials onto a workpiece surface, forming a coating. It imparts different physical and chemical properties to components, such as hardness, wear resistance, heat resistance, and corrosion resistance. It can spray almost all solid materials, especially high-melting-point ceramics. The development of this technology focuses on improving spray gun power and powder feeding methods, enhancing performance and application range.
Supersonic flame spraying
Supersonic flame spraying is a method that utilizes a high-temperature heat source generated by the continuous combustion of oxygen and fuel to heat and spray fine powder materials in a supersonic jet. It achieves high-quality coatings by increasing the velocity of the sprayed particles, such as spherical molybdenum powder or stainless steel 316L spherical powder. The quality of the coating is closely related to the particle velocity. Supersonic flame spraying can produce dense coatings with high bonding strength and is suitable for spraying metal-ceramic materials. It has high spraying efficiency but requires a large consumption of oxygen, resulting in higher costs.
Arc spraying
Arc spraying is a coating process that uses two consumable metal wires as electrodes. These wires are connected to a DC power supply and fed into a spraying gun. When the wire ends touch, an arc is formed, melting the wire ends. Compressed air is injected behind the arc, atomizing the molten metal into fine particles. These particles are then propelled onto the substrate, forming a coating. It's important to use metal wires with conductive properties for arc spraying.
Flame spraying
Flame spraying uses combustion heat to melt coating material, which is then propelled onto the workpiece surface to form a coating. Three forms of flame-spraying materials are powders, wires, and rods. Powder flame spraying is common and versatile, while wire flame spraying is used for large-scale operations. Rod flame spraying is suitable for ceramic materials with lower costs but challenges for continuous operations.
Explosive Spraying - Flame Class
Explosion spraying is a technique used to apply coatings to surfaces by using the energy and force generated by an explosion. It involves mixing gases, igniting them to create an explosion, and then spraying the molten powder material onto the workpiece. This method is known for its high bond strength and low porosity in the coatings. However, the coating uniformity may be inconsistent due to the intermittent nature of explosions.
Explosion spraying is not suitable for spraying high-melting point materials like ceramics because the flame temperature is not very high. However, it is effective in preventing the high-temperature decomposition of carbides. This technique is commonly used for spraying carbide or metal-ceramic coatings. Although it can be costly, it can achieve coating densities of up to 99.9%.
Each type has its unique advantages and application range, and appropriate materials and techniques can be selected according to specific application requirements.
Heeger Materials is a reputable supplier offering Thermal Spraying Powder products at competitive prices, which are widely used in research and science fields. If you're interested, feel free to contact us at [email protected] for a quote, and we guarantee a response within 24 hours.