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Types of Piston Ring's Surface Treatments

2024/7/10
The main purposes of piston ring surface treatment include: reducing wear, preventing corrosion, improving durability, sealing, and lubricity, etc. This ensures long-term reliable operation of the engine, improves engine performance and fuel efficiency, and reduces energy consumption and emissions. There are many ways to treat the piston ring surface, such as phosphated, sandblasting, chromed, nitriding, DLC, etc.

Phosphated: The surface of the piston ring is usually dyed black by chemical immersion, which can form a dense black oxide film on the surface. This treatment can not only improve the wear resistance and heat resistance of the surface, but also its compatibility with lubricating oil, thereby improving the sealing performance of the piston ring. Black dyeing is a simple, economical, and effective surface treatment method that is widely used on the piston rings of various engines.

Sandblasting: By spraying high-speed sand particles on the surface of the piston ring, a uniform layer of rough texture can be produced with a matte metallic appearance. This treatment increases surface area and improves lubricant adhesion, thereby improving sealing performance. In addition, sandblasting can also remove the oxide layer and tiny defects on the surface, increasing its wear resistance and fatigue resistance.

Chromed: The method commonly used for piston rings is chromium electroplating. Chromium plating can form a dense chromium alloy film on the surface with excellent hardness, wear resistance, and corrosion resistance. This can not only enhance the mechanical performance indicators of piston rings, but also beautify their appearance, helping to improve the overall product image. Compared with black dyeing, electroplating treatment is relatively complex and costly, but it can improve surface properties.

Nitriding: Placing the piston ring in an ammonia environment allows the nitrogen atoms produced by the decomposition of ammonia at high temperatures to penetrate into the surface of the piston ring to create a nitride layer. This can greatly improve the surface hardness and wear resistance. Compared with electroplating, the nitride film is denser, more uniform, and has more advantages in terms of resistance to wear and corrosion. The metal color of the nitride piston ring will be more yellowish brown. In addition, the nitride film also has good lubricity and thermal stability and performs well in high-load, high-temperature engine environments. Therefore, nitriding treatment is usually used in piston rings that require higher performance, such as high-power racing cars or heavy engineering machinery.

Diamond-Like Carbon (DLC): This technology deposits an amorphous carbon film on the surface of the piston ring. Its hardness, wear resistance, and low friction coefficient are comparable to or even surpass those of the nitriding treatment. In terms of appearance, unlike the matte black produced by black dyeing, the color of the DLC piston ring is gloss black and deeper. The DLC treatment can greatly extend the service life of piston rings and effectively reduce the increase in fuel consumption and emissions caused by wear. This surface treatment is especially suitable for high-power, high-speed engines and can maintain good sealing under extreme working conditions. Compared with other treatment methods mentioned above, DLC technology is relatively more complex and expensive, but it can have excellent mechanical properties. C.T.I. has been researching in the field of DLC for many years. Through unremitting exploration and innovation, it finally made a major breakthrough and successfully applied for two new DLC patents (USA: 905744B2, Taiwan: M300746). These patented technologies are not only innovative in material composition and structure, but also reach industry-leading levels in terms of performance indicators. We will continue to deepen basic research and focus on promoting patented technologies.

In general, the above-mentioned surface treatment technologies have their own characteristics. In practical applications, the most suitable solution needs to be selected based on the working conditions and performance requirements of different engines. As technology continues to advance, we may see more innovative surface treatment methods being used in the field of piston rings in the future to meet increasingly stringent performance requirements.

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