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CERTESS Carbon - Tribological coatings

In recent years, a new generation of coatings has developed strongly, with considerable commercial success. These Diamond-Like Carbon (DLC) coatings present the advantage of possessing high hardness (1,500 -3,200 HV) but also a coefficient of friction much lower than that of conventional hard layers such as TiN, TiCN, etc. (5 to 10 times lower).
 
This unique combination of properties has opened up new possibilities, permitting the improvement of technical parts like engine components, etc. Moreover, these coatings are generally bio- compatible and therefore suitable for food contact and medical applications. 
 
So as to meet the various operating conditions encountered by technical components used for automotive and other generic industrial applications, HEF has developed a range of DLC coatings capable of meeting all friction reduction requirements.
 
HEF is thus heavily involved in the development of technologies aimed at reducing fuel consumption and CO2 emissions in the automotive industry, the solutions developed by HEF now being used by engine manufacturers worldwide for the improvement of friction:
  • In rocker arm systems
  • In mobile coupling systems
  • In transmission systems
 
These coatings generally comprise several layers of various materials such as Cr, CrN, Si, W and WC- C combined with a top layer of amorphous carbon enriched or not with hydrogen.
The selection of the sub-layer is based on several factors such as the adherence requirements, the wear mode, the type of contact, the friction regimes encountered during operation, the load applied and other metallurgical considerations.
 
These coatings offer a unique combination of high hardness and low coefficient of friction, compared with the conventional PVD coating (TiN, CrN, AlTiN, etc.) and soft coatings (such as solid lubricants: molybdenum disulphide).

HEF is a leading supplier of tribological coatings and has a wide range of solutions. On account of control of processes and materials and its tribology expertise, the HEF Group has, moreover, the ability to adapt its coatings to suit specific requirements.
Some of the most common commercial variants of HEF's DLC coatings are indicated below.
 

CERTESS™ CARBON

Coatings

 Architecture 

Thickness

Hardness*

Treatment temperature

Maximum use temperature*

Coefficient of friction(dry)*

 Applications

 

  

  

Certess™DT

    

    

     a-C:H

Metal doped

  

Generally 2-4 µm

 

Adaptable to suit the application

 

 

 

 

 

1200-1800Hv

 

150

-

350°C

 

  depending on substrate

  

 

 

350°C

   

 

    0,20

       -

    0,25

 

Adhesive wear resistance of mechanical parts

Automotive components, dry lubrication

 

 

 

 

  

Certess™DCX

 

 

 

 

 

  

Generally 2-4 µm

 

Adaptable to suit the application

 

 

 

 

 

 

  

 

Generally 2500-3000Hv

Complete range: 1000-3000Hv

 

 

 

 

 

  

      150

        -

     350°C

 

  depending on substrate 

 

 

 

 

 

  

 

 

 

    350°C

 

 

 

 

 

 

  

 

     0,11

        -

     0,15

 

 

 

 

 

 

Abrasive wear resistance of mechanical parts in heavily loaded contacts,

 

Reduction of friction losses for automotive components

 

 

 

 

     Cr,N

       +

    a-C:H

 

 

 

Certess™DCY

Cr

+

WC,C

+

a-C:H

  

Certess™DCZ

CrN

+

WC,C

+

a-C:H

 
 *Depending on test protocol