In the harsh environments of rivers and oceans, ship and vessel components are constantly subjected to corrosion, wear, and cyclic loads. Traditional repair technologies, due to their limitations, often fail to meet the growing demand for high reliability, long lifespan, and low-cost maintenance in modern shipping and defense equipment. In this context, revêtement laser technology, as an advanced “remanufacturing” engineering method, is emerging as a revolutionary solution to address the challenges in ship repair.

1. Bottlenecks and Limitations of Traditional Repair Technologies

To understand the value of laser cladding, it is essential to first recognize the shortcomings of traditional repair methods:

• Electroplating: The repair layer is extremely thin (usually only a few micrometers) and has poor load-bearing capacity. More importantly, the waste solution produced during electroplating, which contains heavy metals, incurs high disposal costs and poses significant environmental pressures, making it obsolete in many regions.
• Projection thermique: The bond between the coating and the substrate is mainly mechanical, resulting in a low bonding strength. Under high-speed, high-load, or impact conditions, the coating can easily peel off, compromising reliability.
• Arc/Plasma Transferred Arc Cladding: While the bonding strength is high, the excessive heat input leads to a wide heat-affected zone and severe deformation. Many precision or thin-walled components are scrapped due to dimensional deviations after repair, causing repair costs to increase instead of decrease.

2. Laser Cladding Technology: Principles and Core Advantages

Rechargement laser is an advanced surface modification technology. The process involves precisely delivering a specific mixture of alloy powders to the area to be repaired on the workpiece through a powder feeding system. A high-energy density laser beam is used to melt the powder and a thin layer of the base material surface. After rapid cooling and solidification, a metallurgically bonded functional cladding layer is formed.

Compared to the traditional methods mentioned above, the advantages of laser cladding are systemic:

1. Excellentes performances d'adhérence: The cladding layer is metallurgically bonded to the substrate, with bonding strength reaching over 90% of the base material’s strength, fundamentally eliminating the risk of coating delamination.
2. Minimal Heat Input and Deformation: The laser energy is highly concentrated with a short action time (rapid heating and cooling), resulting in minimal thermal influence on the workpiece. This makes it possible to control the deformation of precision parts such as shafts and rudder shafts to an extremely low level (even to the micrometer scale), avoiding the need for secondary processing or correction.
3. Controllable Coating Composition and Excellent Performance: Due to the low dilution rate (usually below 5%), the composition of the cladding layer is primarily determined by the powder used, allowing the design performance to be retained to the maximum extent. This means:
   • Restauration dimensionnelle: “Homogeneous repair” with materials similar to the base material.
   • Mises à niveau de performance: Use of advanced alloy powders (such as nickel-based, cobalt-based, or metal-ceramic composite materials) to achieve surface modification, making the repaired components perform better than new parts.
4. Flexibility in Processing and Functional Gradient: Through programming, the laser path and powder feeding rate can be easily controlled to achieve precise repair of complex surfaces (such as propellers or pump housings). Furthermore, by changing the powder formulation, coatings with gradient compositions and properties can be prepared, effectively alleviating internal stress caused by the physical property differences between the substrate and the coating.
5. Respectueux de l'environnement et rentable: The process has no harmful emissions, making it a green manufacturing method. By restoring and even improving the performance of expensive scrap parts, it aligns with the concept of “remanufacturing,” saving up to 70% of costs and more than 60% of energy consumption, offering significant economic and social benefits.

3. Typical Applications of Laser Cladding in Ship Repair

Rechargement laser technology provides perfect solutions to many of the challenging repair problems in the marine industry:

• Ship Shaft Systems (e.g., stern shafts, intermediate shafts): Traditional repair methods involve complicated straightening procedures and may lead to reduced fatigue strength. Laser cladding enables near-net-shape repair with minimal deformation, and after a light grinding, the repaired component can be used, significantly shortening the repair time.
• Cast Iron and Stainless Steel Components: Repairing these materials poses the challenge of cracks in the cladding layer. By precisely controlling laser parameters (such as power, scanning speed, and preheating temperature) and selecting the right powders, revêtement laser can effectively suppress carbon segregation and the formation of brittle phases, achieving high-quality, crack-free repairs.
• Critical Hydraulic Components (e.g., plungers, cylinder liners): A layer of high-hardness, corrosion-resistant cobalt-based tungsten carbide composite material can be cladded onto their surface, enhancing wear resistance several times over.
• Complex Components (e.g., propellers, rudder blades): Using robots or five-axis machines, precise local repairs can be performed on cavitation and corrosion areas of the blades, restoring their hydrodynamic shape.

4. Conclusion et perspectives d'avenir

Laser cladding technology is more than just a repair method; it is a la remise à neuf technology that gives components a “second life.” With its unique advantages of metallurgical bonding, low dilution, low heat input, and high flexibility, it has successfully overcome the inherent defects of traditional repair processes.

As the cost of lasers decreases, the process databases improve, and intelligent control becomes more widespread, revêtement laser technology will see even broader applications in shipbuilding and repair. It not only saves ship owners and military forces substantial costs in spare parts procurement and scrapping but also enhances the reliability and lifespan of equipment, providing solid support for shipping safety and national defense capabilities. The future for the promotion and application of laser cladding technology is immensely promising.