Brake Noise; Brake Dust - Audi A6 Getting To Know Manual

Brakes

Brake Noise

The majority of today's vehicles use semi-metallic brake pads, which offer
excellent performance. Because of the metal-to-metal contact involving
semi-metallic pads, the sounds generated by the brake system under
normal operation can be greater than the sounds produced by vehicles
equipped with previous-generation brake pads. Depending on the local
environment, weather conditions and individual driving patterns, sounds
from the braking system may be more or less apparent.
Frequent, aggressive brake application increases the wear of brake
components and can reduce the potential for brake noise. Frequent, light
brake application allows glazing to develop on the brake surface, which
increases the potential for brake noise.

Brake Dust

Brake dust is a result of friction created by brake pads
and discs during braking. As brake pads and discs
make contact during braking, they wear down, which
causes dust particles to be expelled. This is a normal
characteristic of all brake systems and is not an indicator
of a defect.
Important Warnings and Safety Information, which you must read are listed on
the last panel under Brakes.
Brakes