Substrate provided with a plurality of layers, at least one of which includes metal oxides and is topped directly by a metal coating layer that contains at least 8% by weight nickel and at least 10% by weight chromium, the remainder being iron, additional elements and the impurities resulting from the fabrication process, wherein this metal coating layer is topped directly by an anticorrosion coating layer. A corresponding fabrication method is also provided.

Various methods including applying a coating material with an additive to an article are disclosed. The coating material may be in a powder form before a thermal spraying used to apply the coating material. The coating material may comprise a chromium nitride, a chromium carbide, a chromium silicide, or a tungsten carbide. Additional materials may be added, e.g., a molybdenum alloy such as molybdenum-chromium. In one aspect, thermal spraying includes melting the coating material, propelling the molten coating material toward the article to be coated, and coating the article with the molten coating material. In another aspect, the coated article is one or more piston rings.

A process of converting an outer layer of an object made of a refractory metal, such as titanium, into a carbide of the refractory metal. A molten metal, such as molten lithium, is placed adjacent the outer surface of the object. The lithium does not react with the titanium, nor is it soluble within the titanium to any significant extent at the temperatures involved. The molten lithium contains elemental carbon, that is, free carbon atoms. At high temperature, the carbon diffuses into the titanium, and reacts with titanium atoms to form titanium carbide in an outer layer. Significantly, no other atoms are present, such as hydrogen or oxygen, which can cause problems, because they are blocked by the molten lithium.

A bi-layer protective coating for a metal component, the bi-layer protective coating comprising a bond coating that is metallurgically fused to a substrate of the metal component, wherein the bond coating comprises one or more rare metals and a top coating that is mechanically bonded to the bond coating, wherein the top coating comprises one or more metal oxides, or one or more metal carbides.

Certain configurations of coated articles that are corrosion resistant are described. In some embodiments, the article comprises a substrate and a corrosion resistant coating disposed on an entire surface or a portion of the surface of the substrate. The corrosion resistant coating can resist degradation after exposure to strong acids with a negative pH with a corrosion rate of less than 20 mils/year. The coating can also, if desired, exhibit a hardness of more than 600 Vickers hardness (HV), as measured based on the ASTM E92-17 standard.