Abstract: A friction material has a first layer of a fibrous base material and a second layer of at least one type of friction modifying particle on a top surface of the fibrous base material. The second layer has an average thickness of about 30-200 &mgr;m and a surface coverage of about 80% to about 100%, such that the top layer has a permeability lower than the first layer.

Abstract: A permeameter provides normal and lateral permeability measurements on porous materials. The permeability measurements can be made on compressed or uncompressed samples and can be made at room temperature or at elevated temperatures. A wide variety of fluids, gas or liquid, can be used as the penetrating test fluid depending on the application and the porosity of porous sample. The penetrating test fluid is forced through the sample under pressure. The load, the fluid displacement, and the time are recorded and used in the calculations of permeability, porosity, pore size distribution, average pore size and the number of pores per unit area.

Abstract: A permeameter provides normal and lateral permeability measurements on porous materials. The permeability measurements can be made on compressed or uncompressed samples and can be made at room temperature or at elevated temperatures. A wide variety of fluids, gas or liquid, can be used as the penetrating test fluid depending on the application and the porosity of porous sample. The penetrating test fluid is forced through the sample under pressure. The load, the fluid displacement, and the time are recorded and used in the calculations of permeability, porosity, pore size distribution, average pore size and the number of pores per unit area.