Mahle International Gmbh

Mahle Metal Leve S/a

Nuno Costa

Juliano Avelar Araujo

Paulo Jose Da Rocha Mordente

Juliano A Araujo

José Valentim Lima Sarabanda

Davi Antonio Da Silva

Paulo José Da Rocha Mordente

Juliano Avelar ARAÚJO

A piston ring for internal combustion engines provided with a ferrous alloy base includes an annular outer surface on which a coating including at least one outer layer is applied deposited on an adhesive layer, the outer layer being provided with a variable thickness, in such a way that the thickness of the outer layer gradually increases from 90&#xb0; and 270&#xb0; towards 0&#xb0; and 360&#xb0; respectively, with the thickness attaining its maximum value in the region of 10&#xb0; and 350&#xb0; and slightly decreasing towards 0&#xb0; and 360&#xb0; so as to ensure an optimal working condition, minimizing the contact pressure and consequently the accelerated wear in the vicinities of the ends of the ring, in addition to preventing and/or impeding the detachment of the outer layer of the coating.

Piston ring for internal combustion engines

A piston ring for an internal-combustion engine may include a body having a substantially annular external surface and a physical vapor deposition coating layer disposed on the external surface. The body may include a gap defined between a first end and a second end. The piston ring may also include a first half in a region of the gap and a second half opposite the first half. The coating layer of the first half may have a thickness gradient, and the coating layer may define a greater thickness in a vicinity of the first end and the second end and a reduced thickness in regions further away from the vicinity of the first end and the second end. The coating layer of the second half may have a uniform thickness.

Internal-combustion engine piston ring, process for obtaining a piston ring, and internal-combustion engine

A sliding element for use in an internal combustion engine may include a ferrous base having a peripheral sliding surface covered by a protective surface layer, the protective surface layer including at least one nitride applied via at least one of physical vapour deposition and a nitrided layer. The peripheral sliding surface may have a diamond like carbon (DLC) coating disposed thereon. The coating may include at least one of (a) one or more transition layers composed of WC1-x and (b) an adhesive layer of metallic chromium with a crystal structure. The coating may include an intermediate layer of metal DLC, the metal may be tungsten in a multilayer structure of a-C:H:W and a-C:H, and an outer layer of metal-free DLC.

Sliding element for use in internal combustion engine

A sliding component for an internal combustion engine may include a ferrous base having a peripheral sliding surface covered with a protective layer including at least one of a nitride applied via physical vapor deposition and a nitrided layer. The base may include a coating of carbon of a diamond-like carbon type. The coating may include at least one of (i) a transition layer including a composition of WCand (ii) a layer of metallic chromium of crystalline structure disposed between the ferrous base and an outer layer of amorphous carbon. The coating may also include an intermediate layer of a nanocrystalline phase of carbides in a multilayer structure having a first sub-layer including a composition different than a second sub-layer disposed under the outer layer.

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Coimbra, Portugal

Nuno Costa