Nitride coated piston ring

Abstract

A piston ring and a method of forming a piston ring. A masking agent is applied to a selective area on an exterior surface of a piston ring. The masking agent inhibits the subsequent application of additional coatings to the selective area on the exterior surface of the piston ring. In one form, the masking agent may inhibit the subsequent application of a nitride layer to the selective area on the exterior surface of the piston ring. A recess may be formed in an outer peripheral side of the piston ring, and a thermal spray coating may be formed within the recess in the outer peripheral side of the piston ring.

Claims

1. A method of forming a piston ring comprising: providing a piston ring body formed of a base metallic material and having an upper lateral side, a lower lateral side, an outer peripheral side, an inner peripheral side, and first and second corners where the upper and lower lateral sides terminate into the outer peripheral side; applying a masking agent to an entire exterior surface of the piston ring body; removing a portion of the masking agent from a first selective area on the exterior surface of the piston ring body along the upper lateral side and the lower lateral side of the piston ring body to expose the base metallic material; applying a nitride layer to the first selective area on the exterior surface of the piston ring body, wherein the remaining portion of the masking agent on the exterior surface of the piston ring body inhibits application of the nitride layer to areas on the exterior surface of the piston ring body other than the first selective area; removing the masking agent from a second selective area along the outer peripheral side and along the first and second corners of the piston ring body to expose the base metallic material; forming a recess in the outer peripheral side of the piston ring body; and forming a thermal spray coating within the recess in the outer peripheral side of the piston ring body.

2. The method of claim 1 wherein the piston ring body is formed of stainless steel.

3. The method of claim 1 wherein the masking agent is applied to the entire exterior surface of the piston ring body by a two-step electro-chemical deposition process.

4. The method of claim 1 wherein the masking agent is applied to the entire exterior surface of the piston ring body by (i) depositing a first layer of nickel plating on the entire exterior surface of the piston ring body using an electrolytic deposition process, and then (ii) depositing a second layer of nickel plating over the first layer of nickel plating on the entire exterior surface of the piston ring body using an electro-less deposition process.

5. The method of claim 4 wherein the first layer of nickel plating is deposited on the entire exterior surface of the piston ring body at a first thickness and the second layer of nickel plating is deposited on the entire exterior surface of the piston ring body at a second thickness greater than the first thickness.

6. The method of claim 1 wherein the nitride layer is applied to the first selective area on the exterior surface of the piston ring body using a nitride diffusion process.

7. The method of claim 1 wherein the first corner of the piston ring body comprises an outer peripheral end portion of the upper lateral side and an upper end portion of the outer peripheral side, and the second corner of the piston ring body comprises an outer peripheral end portion of the lower lateral side and a lower end portion of the outer peripheral side, and wherein the nitride coating is not applied to the first and second corners of the piston ring body such that the base metallic material of the piston ring body is exposed along the outer peripheral end portions of the upper and lower lateral sides and along the upper and lower end portions of the outer peripheral side.

8. The method of claim 7 comprising: coating the upper and lower end portions of the outer peripheral side of the piston ring body with a chromium plating, a chromium-ceramic coating, or a HVOF coating.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Referring now to the drawings, illustrative examples are shown in detail. The drawings represent the exemplary illustrations described in this application. The drawings are not to scale. Certain features may be exaggerated to better illustrate, and explain an innovative aspect of an exemplary illustration. The exemplary illustrations presented in this application are not intended to be exhaustive, limiting or restricting to the precise form and configuration shown in the drawings. Exemplary illustrations of the present invention are described in detail by referring to the drawings as follows:

(2) FIG. 1 illustrates a side view of a piston ring, without any coating or plating according to an exemplary illustration;

(3) FIG. 2a illustrates a nickel plated piston ring, according to another exemplary illustration; the piston ring has a plated coating of nickel metal;

(4) FIG. 2b illustrates a nickel plated piston ring, according to another exemplary illustration; the piston ring has a plated coating of nickel metal;

(5) FIG. 3 illustrates a piston ring with the nickel plating removed and a nitride coating on the upper and lower lateral sides of the piston ring, according to another exemplary illustration;

(6) FIG. 4 illustrates a piston ring with plating removed from selected areas according to another exemplary illustration;

(7) FIG. 5 illustrates a piston ring with a recessed area present on the outer surface of the piston ring according to another exemplary illustration;

DETAILED DESCRIPTION

(8) The discussion that follows and also to the drawings, illustrative embodiments are shown in detail. Certain features may be exaggerated, removed, or partially sectioned to better illustrate and explain the present disclosure. The descriptions set forth in this application are not intended to be exhaustive limit or restrict the claims in any way to the precise form.

(9) The present disclosure provides using a plated nickel metal 210 to inhibit the formation of coatings 350, 360 on the surface of the piston ring. This disclosure suggests the use of a two-layer, nickel metal masking and plating layer 210 applied to the piston ring.

(10) The first step of the plating process deposits a layer of nickel 210 on to the surfaces of the piston ring, 110,120,130 and 140. FIG. 1 illustrates one exemplary shape of the piston ring used in the present embodiment.

(11) Electrolytic plating, in general, is the process used in electroplating and is analogous to a galvanic cell acting in reverse. The part to be plated is the cathode of the circuit. In this embodiment, the anode is made of the metal to be deposited on the part. Both components are immersed in a solution called an electrolyte containing one or more dissolved metal salts as well as other ions that permit the flow of electricity.

(12) A second layer of nickel is applied onto the electrolytic deposited first layer. The second layer of nickel is applied using a best known electro-less deposition method used in the automotive industry. In general, an electro-less nickel plating solution might contain a water-soluble nickel salt, a reducing agent, and other components required to effectively and properly produce the required coating.

(13) Electro-less plating, in general, is an auto-catalytic chemical technique used to deposit a layer of pure nickel or nickel alloy on a solid work piece, such as metal or plastic. The process may rely on the presence of a reducing agent which reacts with the metal ions in the plating bath to deposit metal.

(14) Both plated nickel layers can be deposited over the entire surface or selected surfaces of the piston ring. The inner peripheral diameter 140, the upper lateral side, 110, the lower lateral side 120, and the outer peripheral diameter 130 can be covered with the nickel plating 210.

(15) Both plating processes used to coat the piston ring body 105 use best known predetermined nickel plating parameters and chemistry on the ring body. Using predetermined processing parameters allows for repeatability of the plating operation. Repeatability in the plating process provides a uniform application of the nickel metal 210 illustrates the plated ring before any plating metal is removed.

(16) Because the plated nickel acts a s a barrier to subsequent coating formation, certain areas of the nickel plating must be removed so nitride can be deposited. The nickel plating can be removed from the inner peripheral diameter of the ring 140. The nickel plating is removed essentially the entire upper 110 and lower lateral 120 sides of the piston ring. The plating layer can be removed with any mechanical, electro-chemical or chemical methods that lend themselves to the embodiment of this application.

(17) The wear resistant nitride coating 350, is applied to selected ring surfaces after the plating metal has been removed from specific areas on the ring. The nitride process is used in the embodiment of this description may have a greater wear resistance that the base metal of the piston ring body 105.

(18) The exemplary piston ring may be formed of a base metallic material 105, e.g., steel. Exemplary piston rings may be employed in an outer circumferential groove of a piston (not shown). The piston may be received within an engine block (not shown) defining an inner bore surface or cylinder liner surface.

(19) The piston ring has a outer peripheral diameter surface 130, this outer peripheral diameter surface may include an exemplary HVOF coating 360. This outer peripheral diameter surface also has the base metal of the piston ring exposed 460, 470, 480 and 490. All surfaces may contact the cylinder liner wall (not shown).

(20) As best seen in FIG. 4, the piston ring essentially presents three surfaces to the piston ring groove (not shown) and cylinder liner surface (not shown). A nitride coating 350, a HVOF coating 360, and uncoated piston ring metal surfaces 460,470,480, and 490 all may be present on the piston ring simultaneously.

(21) Piston rings can be manufactured from solid wire composed of the piston ring base material. In some embodiments of this disclosure the wire is extruded or bent. These operations can ultimately form the recess 575, present on the outer peripheral diameter surface 130, of the piston ring. In other embodiments of this disclosure, the wire is subjected to a localized grinding process that forms the recess 575, present on the outer peripheral diameter 130 of the piston ring.

(22) FIG. 5 illustrates one exemplary shape of the piston ring used in the present embodiment. The recess 575, present in the outer peripheral diameter surface may be formed by a grinding operation. FIG. 3 illustrates one exemplary plating configuration used to mask surfaces of a piston ring. As depicted in FIG. 4, surfaces 460, 470, 480, and 490 of the piston ring are not coated with the wear resistant nitride surface. The nickel plating 210 depicted in FIG. 3, prevents the formation of a nitride on these surfaces.

(23) A HVOF thermal spray coating 360 may be applied to specific areas on the surface of the piston ring. The following thermal spray application methods are listed as examples and do not define every method that may be utilized to form the HVOF coating within the recess 575. HVOF, arc spray, and/or flame spray can be used to apply the HVOF coating 360.

(24) The material selected to form a desired thermal spray coating 360 may be introduced into the spray device such that the material melt or partially melt. When the HVOF material contacts the piston ring outer radial surface 130, inside the recess 575, of the piston ring, the HVOF coating is formed. The HVOF coating process is used to fill the recess 575 that may be present on the outer radial surface of the piston ring.

(25) HVOF spray parameters used to deposit an exemplary layer of coating on the piston ring surface and within the recess located on the outer radial surface of the piston ring: sprayer: High-speed frame thermal sprayer JP-5000 (manufactured by Praxair/TAFA), gas flow rate, e.g. oxygen: gas flow volume 1900 scfh (893 l/min), flow rate of fuel, e.g. kerosene: 5.1 gph (0.32 l/min) Thermal spray distance, barrel end to target surface e.g.: 380 mm, barrel length: 4 inches (approximately 100 mm), powder supply rate: Approximately 80 g/min.

(26) With regard to the processes, systems, methods, heuristics, etc. described herein, it should be understood that, although the steps of such processes, etc. have been described as occurring according to a certain ordered sequence, such processes could be practiced with the described steps performed in an order other than the order described herein. It further should be understood that certain steps could be performed simultaneously, that other steps could be added, or that certain steps described herein could be omitted. In other words, the descriptions of processes herein are provided for the purpose of illustrating certain embodiments, and should in no way be construed so as to limit the claimed invention.

(27) Accordingly, it is to be understood that the above description is intended to be illustrative and not restrictive. Many embodiments and applications other than the examples provided would be upon reading the above description. The scope of the invention should be determined, not with reference to the above description, but should instead be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. It is anticipated and intended that future developments will occur in the arts discussed herein, and that the disclosed systems and methods will be incorporated into such future embodiments. In sum, it should be understood that the invention is capable of modification and variation and is limited only by the following claims.

(28) All terms used in the claims are intended to be given their broadest reasonable constructions and their ordinary meanings as understood by those skilled in the art unless an explicit indication to the contrary in made herein. In particular, use of the singular articles such as “a,” “the,” “said,” etc. should be read to recite one or more of the indicated elements unless a claim recites an explicit limitation to the contrary.