Tribology coatings for mobility applications - Lesson 2: Highly resilient DLC coatings for extreme applications
Welcome to lesson two of the Ionbond Summer School!
Last time, we learned what a DLC coating is, why it is so widely used in the mobility sector, and which factors are important for its design.
Today, we are diving into highly resilient DLC coatings for extreme applications.
Extremely highly loaded components
Although the loads in typical passenger cars and trucks with internal combustion engines are not insignificant, they are comparatively low compared to those in racing or off-road applications.
Another example of high loads is electric mobility, which is becoming increasingly important, particularly in the passenger car sector but also for trucks.
Due to the greater weight of vehicles and the higher torque and motor speeds, components such as differentials are subjected to greater stress than in lighter vehicles powered by internal combustion engines.
Another challenge is the change in lubrication conditions. We must remember that the tribological system must always be considered holistically.
Therefore, existing coatings must be further developed and optimized to meet the new requirements and compensate for the increasing loads.
Example: Differential Pin in Electric Vehicles
Coating structure
An example of such a customized coating system is shown for the differential pin.
The first layers of the coating structure are similar to the Tribobond 42 system introduced in the previous lesson. The chromium layer serves as an adhesion promoter to the base material.
The crystalline CrN layer combines high hardness with high fracture toughness, making it ideally suited as a support layer by absorbing the applied load and the resulting deformation of the subsequent layers.
This is particularly important because amorphous layers, such as the DLC layer, would otherwise be overloaded. Therefore, the design of this layer is of particular importance in terms of its structure.
The CrN layer is bonded to the carbon-containing layers via an additional Cr or CrC intermediate layer.
Functional DLC layers
This interface system is followed by two layers: a ta-C intermediate layer and a DLC top coating.
The "t" stands for tetragonal, a specific configuration of the DLC layer that, due to its high sp³ content and virtually no hydrogen content, is characterized by very high hardness and wear resistance.
This layer forms the functional layer in tribological contact.
The DLC layer above it serves as a running-in layer, meaning that its primary function is not wear protection but rather the polishing of the counter surface.
This modification is particularly necessary when the counter surface is relatively rough and cannot be smoothed through post-processing - a good example of why a holistic understanding of the tribological system is essential.
Post-treatment
However, in addition to the advantages mentioned above, the coating system also has one disadvantage.
Its production requires a high degree of ionization, which limits the available manufacturing methods.
Cathodic arc evaporation is an established industrial process, but due to the nature of the process, it leads to the formation of so-called droplets on the surface.
To prevent these hard droplets from detaching from the coating during tribological contact and acting as abrasive particles, post-polishing of the surface is absolutely necessary.
Questions?
Discuss your challenges with André Hieke
André Hieke, Global Product Manager Mobility, will be glad to support you.
We will get back to you as soon as possible
André Hieke
Global Product Manager Mobility
André Hieke
Global Product Manager Mobility
Ionbond Summer School
Discover all our lessons on the performance-enhancing properties of tribology coatings for mobility applications
Lesson 1: How are tribology coatings designed?
Available on 4. August 2026
In this lesson, we explore how coatings for mobility applications are designed, the factors that must be considered during development, and why DLC coatings provide key advantages for specific application requirements.
Lesson 2: Highly resilient DLC coatings for extreme applications
Available on 11. August 2026
We are diving into highly resilient DLC coatings designed for demanding mobility applications where components are exposed to high loads, increased torque, changing lubrication conditions, and rough counter surfaces.
Lesson 3: Tribology coatings for hydrogen applications
Available on 18. August 2026
We'll explore challenges like corrosion resistance, long-term reliability, stable friction behaviour, and protection against hydrogen diffusion which tribological coatings face in applications involving alternative fuels.
Lesson 4: Coating solutions for aerospace
Available on 25. August 2026
We take a closer look at coating solutions for aerospace and how coating solutions help protect critical parts against wear, corrosion, oxidation, erosion, and fatigue while supporting higher efficiency and longer service life.
Lesson 5: Coating solutions for radar antennas
Available on 1. September 2026
In this lesson, we explore the future of autonomous driving and the role of radar antennas in Advanced Driver Assistance Systems. These critical components require coating solutions that combine strong adhesion, high electrical conductivity, corrosion protection, uniform layer distribution, and cost-effective manufacturing at scale.