A Brief Introduction to Spraying Equipment

With the application of high-tech scientific technology, the technical level of industrial production continues to improve, and the comprehensive performance requirements for mechanical parts are increasing. Enhancing the comprehensive use of materials and improving the surface performance of materials to give them multiple functions has become a topic of close attention. Thermal spraying technology is one of the effective techniques in the field of surface engineering to impart new functions to the material surface. This technology is interdisciplinary, has broad functionality, promotes resource regeneration, and employs diverse methods. It is widely used in various construction fields such as aerospace, transportation, power and energy, petrochemicals, metallurgy and mining, machinery manufacturing, light industry, textiles, and biomedicine, playing a significant role.

Thermal spraying technology involves heating the spraying material to a molten or semi-molten state using a heat source and then spraying it at a certain speed onto the pretreated substrate surface to form a coating. This method aims to impart special functions to the substrate surface.

Thermal spraying technology can be divided into combustion methods and electric heating methods based on the heat source used.

1. Combustion Method: Utilizes high temperatures generated by an oxy-acetylene flame.
2. Electric Heating Method: Generates high temperatures through intense and sustained discharge arcs between two electrodes.

Regardless of the heat source used, the principle is to melt the spraying material using the high temperature generated for spraying.

Combustion Method:

Wire flame spraying uses an oxy-acetylene flame as the heat source and the spraying material in wire form. It is commonly known as gas spraying. Common spray gun models are SQX-I and SQX-II.

Applications of Thermal Spraying:

1. Corrosion Protection of Metal Materials: Corrosion issues are prevalent in all areas of the economy and daily life, causing significant economic loss and harm. For a long time, various corrosion protection methods have been improved. The application of spraying technology in corrosion protection provides long-term protection (decades or even hundreds of years) for steel structures and is the preferred method for various anti-corrosion projects. For example, the world-renowned Oriental Pearl Tower in Shanghai uses thermal spraying for corrosion protection, with a protection period exceeding 50 years without maintenance. Similarly, the gates of reservoirs, which are in constant contact with water and have significant corrosion problems, achieve excellent corrosion protection and cathodic protection function with thermal spraying. This method can be applied on-site and is widely used in transmission towers, steel structures of high-rise buildings (like the Shanghai Information Tower), lighthouse structures on highways, steel structures for wind power generation, etc., providing long-term corrosion protection.

2. Boiler "Four Pipes" Corrosion Protection: The "Four Pipes" in power plant boilers are subjected to wear, corrosion, and high temperatures during operation. The repair costs for "Four Pipes" due to wear and corrosion account for more than 50% of the total maintenance costs. Using thermal spraying methods with specialized materials to create wear-resistant and corrosion-resistant coatings can extend the service life of pipes and reduce maintenance costs.

3. Repairing Machine Parts: Repairing machine parts is another important application of thermal spraying. For example, shaft parts' wear can be repaired by spraying appropriate materials using thermal spraying methods, restoring the parts' dimensions. This application is widely used in various fields of the machinery industry. A typical example is the repair of printing rollers. After surface wear, high-carbon steel or stainless steel is sprayed on, and after grinding, the roller is as good as new, a common practice in the printing industry.

4. Preparation of Special Surfaces: For some mechanical parts, the surface needs to achieve specific mechanical and physical properties, and thermal spraying methods can achieve these requirements effectively. For example, in the papermaking industry, spraying a layer of stainless steel coating on the iron-based dryer significantly extends its service life. Similarly, preparing special coatings on various storage tanks in the chemical industry can prevent various forms of corrosion, enhancing durability.

5. Electronics Manufacturing Industry: The electronics manufacturing industry has numerous applications of thermal spraying, making it a valuable technology in this field.