Abstract: In a method for electrolytically forming on a metal surface a composite coating having improved hardness and wear resistance, a compound containing phosphorous is added into the plating electrolyte, with the phosphorous content being in a quantity of between about 0.1 to 4.2 g/l with minute particles of a required property suspended therein thereby to coprecipitate a nickel phosphide together with the minute particles, whereby the physical and chemical properties of the composite coating are remarkably improved.

Abstract: This disclosure relates to a roof plate assembly comprising a plurality of individual roof plates interlocked with one another by means of a plurality of anchoring pieces, and fastened to a batten or the like. The anchoring pieces connect the trailing end of each roof plate with the leading end of the following roof plate. The anchoring pieces and the roof plates are interlocked with one another by means of bent stop portions having portions spaced from one another with sufficient clearance to absorb dimensional inaccuracies during assembly. Each roof plate further includes a suspending piece which depends from its leading end and abuts the trailing end of the preceding roof plate to provide, in combination with the anchoring piece, a double connection at the trailing end of each roof plate.

Abstract: Fine particles of a very hard material such as silicon carbide and either a solid lubricant such as carbon fluoride or a lubricant such as a powdered organic high polymer are dispersed in a metal plating solution, and a metal object to be plated is immersed as a cathode, together with a metal rod as an anode, in the plating bath, and then a suitable current is passed through the bath to cause coprecipitation of the fine particles and lubricant in the metal deposit. The plated coating layer thus obtained is electro-polished or chemically or mechanically polished and a given thickness of the metal layer is removed to leave the fine particles as tiny protrusions from the lowered surface. In this way a low-abrasion surface is produced on the metal object.