A rotor assembly for a gas turbine engine according to an example of the present disclosure includes, among other things, a rotor that has a hub carrying one or more rotatable blades. The rotor is mechanically attached to a shaft, and an annular seal is carried by the shaft. The annular seal includes a substrate, a first layer disposed on the substrate, and a second layer disposed on the first layer and arranged to establish a sealing relationship with the rotor. The second layer includes a solid lubricant that has molybdenum trioxide (MoO3). A method of sealing for a gas turbine engine is also disclosed.