Local wear protection for demountable automotive aluminum draw bars by thermal spray coatings
There are constantly increasing requirements concerning light-weight concepts in automotive design due to energysaving demands. Additionally reduction of component weight is desired for demountable parts to permit easier handling. One innovative development example in this field is a draw bar consisting of precipitation hardened aluminum featuring significant weight reduction compared to presently applied steel draw bars. However, low wear resistance of aluminum alloys makes sophisticated addition of wear resistant parts in the area of the positive fit necessary. This leads to increased machining time, further costs for purchasing and machining of adapted additional components and further assembling steps. A study on the capability of thermal spray coating deposition in the positive fit area for substitution of the sophisticated wear protection system is carried out. Different HVOF coating systems with variable thicknesses are tested concerning their capability to withstand bending stress. The optimum combination of Ni20Cr bond coats and Cr3C2 - 25 Ni20Cr top coats is applied for prototype production. The prototypes are tested concerning their performance under dynamical load and in corrosion tests. All produced prototypes pass both mechanical and corrosion tests. Prototypes, on which arc-sprayed Ni20Cr coatings are deposited as a low-cost solution, are still in tests.
A. Wank, B. Wielage, T. Grund, C. Rupprecht, Chemnitz / D, K. Angermann, Hartha / D, T. Schnick, Kriftel / D