It has excellent mechanical strength and good construct-ability; the anti-corrosion layer has good resistance to soil stress; the anti-corrosion layer has good flexibility; the required current density of the cathodic protection is small, which can reduce the number of cathodic protection stations.
(1) Its composition is selected and planned by people.
(2) It is artificially made rather than natural.
(3) At least rich in two independent different phases.
(4) Its function depends on the function of each constituent phase.
(5) Its components have a repeating geometric shape so that the material can be considered microscopically uniform.
(6) It has excellent properties not possessed by a single component material.