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New bearing coatings withstand water, acids, cleaning agents and other corrosive media

Tuesday, August 7th, 2007

A new high-grade martensitic hardening steel has been developed for rolling bearings, which offers maximum corrosion resistance under extreme conditions, for example, in dry running applications or when the bearings are in contact with aggressive media such as water, acids and cleaning agents.
Based on the consistent refinement of high-grade NIROSteels, Schaeffler’s new Cronitect® martensitic hardening steel achieves a very high hardness through its unique chemical composition, in combination with a new thermo-chemical surface layer treatment process. Cronitect® is therefore able to withstand extreme conditions, including salt spray testing in accordance with DIN 50021 SS without any problems, even after 600 hours.
Cronitect’s resistance to corrosion is many times better than that of conventional NIROSteels. Rolling bearings that use Cronitect come in either a sealed or non-sealed version.
The name Cronitect is derived from the chemical composition of the material and from its special heat treatment process. The ‘tect’ suffix is found in other Schaeffler coating products and refers to the material’s excellent corrosion protection.
Schaeffler recently opened a new development centre for the surface coating of components at its headquarters in Herzogenaurach, Germany. The new centre offers opportunities to develop new processes and combinations of unique materials and coatings technologies. The opening of the new centre represents a further expansion of the company’s R&D activities.
Mrs. Maria-Elisabeth Schaeffler, Partner of INA-Holding Schaeffler KG, emphasised the outstanding importance of R&D for Schaeffler, particularly with regard to innovation: “By opening the new Surface Technology Centre, our group of companies is intensifying its commitment to the future, particularly in nanotechnology, and is expanding its expertise in rapidly converting research results into innovative and efficient products.”
Schaeffler is a leader in the area of innovative surface and coating technology. The functionality of surfaces for a range of applications is optimised using special manufacturing and treatment processes. Examples are wear resistance, sliding characteristics, shine or appearance, electrical and thermal conductivity, as well as corrosion protection. Under its established brands Corrotect® and Triondur®, Schaeffler offers a successful range of coated components.
The importance of coating technology will continue to increase due to growing product requirements in industry and vehicle manufacturing. The Surface Technology Centre now provides development engineers at Schaeffler with facilities and extra capacity, which open up new possibilities, particularly for combining different processes and materials.
Tribological coating systems (coating systems that are optimised for friction and are wear-resistant) can be developed and implemented using the PVD/PACVD development facility. The coating material is either in the form of a solid (Physical Vapour Deposition) or in the form of a gas (Plasma Assisted Chemical Vapour Deposition) and is vaporised in a vacuum. In contrast to conventional coating methods, it is possible to produce unique compositions of different materials and coatings with this environmentally friendly vacuum process.
There is also an electroplating development facility that is used for developing corrosion protection coatings that are environmentally friendly. For example, part of the focus is now on developing new coatings that are hexavalent chromium-free (Cr-VI) and that comply with the stringent requirements of the new EU directive on end-of-life vehicles.
Both development facilities also enable cost-oriented, function-oriented combinations of different vapour deposition processes and coating systems. The Surface Technology Centre, in combination with Schaeffler’s R&D facilities, will enable the Group to rapidly implement customised, nanotechnology-based solutions for its customers.

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