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Passenger Car Friction Results
The test was performed in accordance with the internationally standardized AK master test program SAE J 2522.
All friction values achieved were at the level of friction linings that are in general use in automobiles that are currently utilized. If the individual test sequences are considered in more detail, it is conspicuous that the friction values of the pads with higher proportions of HAR wollastonite have a slightly lower friction value at the beginning of the test. This assertion is put into perspective again after the fading series at temperatures of 500-600 °C. See Fig. 13.
The pad wear was at a similar level for all recipes. However, the pad wear for the recipe with a 15% (recipe 4) proportion of HAR wollastonite tends to be somewhat higher than the other pads.
The results obtained are shown in Fig. 14.
In Fig. 15 it shows that all recipes have similar disk wear and are well in range for use in passenger car brake pads.
Fig. 13 Passenger car friction values of the recipes investigated
Fig. 14 Pad wear in g of the recipes investigated
Fig. 15 Disk wear in g of the recipes investigated
Fig. 16 SEM image of a brake pad not subjected to a load; scale: 1:1,000
Incorporation of HAR Wollastonite in Comparison to Mineral Fiber
Scanning electron microscope images (SEM images) of the brake pads subjected and not subjected to a load show the incorporation of the fibers into the brake pad recipes. The mineral fibers and the HAR wollastonite needles show the same incorporation behavior.
These SEM images from recipe 2 are shown in Figs. 16 and 17.
The incorporation of HAR wollastonite fiber into the phenolic resin can be improved even further through the use of silane-treated HAR wollastonite. The surface-modified HAR wollastonite types have higher friction values at the beginning of the test. A smaller spread of the friction value progression is achieved by the surface treatment. The friction values of silane-treated HAR wollastonite are shown in Fig. 18.
Fig. 17 SEM image of a brake pad subjected to a load; scale 1:1,000
Fig. 18 Friction values of a silane-treated HAR wollastonite
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