Abstract: A high-hardness metal skin film is formed of an aggregate of metal crystals. The area rate A of pyramid-shaped metal crystals in a surface of the skin film is in a range of A.gtoreq.40%. The aggregate contains at least one element selected from boron (B), carbon (C) and hydrogen (H) as an added element, wherein the B content is in a range of B.gtoreq.0.01% by weight, the C content is in a range of C.gtoreq.0.03% by weight, and the H content is in a range of H.gtoreq.0.01% by weight. The skin surface takes on an intricate aspect due to the presence of a large number pyramid-shaped metal crystals and hence, has a good oil retention. In addition, the wear of each pyramid-shaped metal crystal is inhibited by an increase in hardness produced with the containment of boron and/or carbon and/or hydrogen and therefore, the oil retention is maintained.

Abstract: A slide surface construction which is an inorganic skin film formed of an aggregate of Fe crystals having a body-centered cubic structure. The aggregate includes a large number of {222} oriented Fe crystals with their {222} planes (by Miller indices) oriented toward a slide surface. At least some of these {222} oriented Fe crystals are hexangular pyramid-shaped Fe crystals having six ridge lines. These Fe crystals having six ridge lines ensure that the oil retention of the slide surface construction can be improved, and a slide load acting on the slide surface can be finely divided.