where c denotes the mean grain size, [A.sub.C-C], [A.sub.C-Ti], and [A.sub.C-Ni] denote areas under (C-C), (
C-Ti + C-[Ti.sup.*]), and (C-Ni) peaks in XPS C1s spectrum, [M.sub.a-C], [M.sub.TiC], and [M.sub.Ni] denote atomic weights of amorphous carbon, titanium carbide, and nickel, and [[rho].sub.a-C], [[rho].sub.TiC], and [[rho].sub.Ni] denote mass densities of amorphous carbon, titanium carbide, and nickel.