Application of DLC Coatings in Internal Combustion Engine Components

2025-07-29

Industry Background

Wear in internal combustion engines is an inevitable phenomenon during operation, serving as a critical factor affecting engine lifespan, performance, and reliability. Fundamentally, wear involves the gradual loss of surface materials on friction pairs through oxidation and corrosion. Coatings play an extensive and vital role in engine components. Diamond-like carbon (DLC) coatings, as a promising lubricating coating, significantly enhance engine efficiency, reliability, durability, emissions, and fuel economy due to their exceptional tribological properties. Additionally, the relatively low deposition temperatures of DLC coatings prevent dimensional changes or surface roughness alterations in components. These unique characteristics make DLC coatings widely adopted in automotive engine parts. Below are key application areas and functions of DLC coatings in engine components:

1. Piston Rings

Coating types: PVD-CrN, DLC

Functions:

Friction reduction: Minimizes frictional losses between piston rings and cylinder liners, improving mechanical efficiency and fuel economy.

Enhanced wear resistance: Resists abrasive wear, adhesive wear, and fretting wear, extending service life of both piston rings and cylinder liners.

Improved running-in performance: Facilitates faster and smoother initial break-in processes.

Reduced oil consumption: Superior sealing capabilities and wear resistance help control oil migration into the combustion chamber.

Application of DLC Coatings in Internal Combustion Engine Components (1)

2. Valves (Valve Stem Ends/Stems)

Coating types: PVD-CrN, DLC

Functions: Reduce frictional wear against valve guides or rocker arms, enhance wear resistance, and prevent scuffing.

Application of DLC Coatings in Internal Combustion Engine Components (2)

3. Tappets/Rocker Arms

Coating types: DLC, PVD-TiN

Functions: Mitigate frictional wear with camshaft lobes, prevent pitting and scuffing, reduce friction losses and operational noise.

Application of DLC Coatings in Internal Combustion Engine Components (3)

4. Piston Pins

Coating types: DLC

Functions: Increase surface hardness and wear resistance, minimize frictional wear between piston pins, connecting rod bushings, and piston pin bores.

Application of DLC Coatings in Internal Combustion Engine Components (4)

DLC Coating Performance:

Coating Name	Material	Appearance	Thickness	Hardness	Friction Coefficient	Deposition Temperature
DLC	a-C:H	Bright Black	2-4（Adjustable per requirements）	≈2500HV	＜0.1	<200℃