They have the property of excellent resistant-corrosion,high mechanical strength, high thermal conductivity, good self-lubrication, used as seal faces,bearings and tubes in spacecraft,machinery, metallurgy,printing and dyeing, foodstuff, hamaceutical, auto industry and so on.When the sic faces are combined with graphite faces the friction is the smallest and they can be made into mechanical seals which are able to work in highest working requirements.