WO2006063110A2

WO2006063110A2 - Coated strip and method therefor

Info

Publication number: WO2006063110A2
Application number: PCT/US2005/044376
Authority: WO
Inventors: Donald G. Faulkner; George A. Barr; Rex B. Griffin; Mark S. Wabalas; Harold Lloyd Crowder; Franz W. Kellar
Original assignee: Hiduraflex Llc
Priority date: 2004-12-10
Filing date: 2005-12-09
Publication date: 2006-06-15
Also published as: WO2006063110A3

Abstract

A nozzle includes an elongated metallic strip (10) having an exterior surface, and at least one orifice formed therethrough, the orifice having an interior surface (12). A carbon-based coating (14) having an amorphous microstructure is disposed on substantially all of the exterior surface and the interior surface (12). A method of coating a nozzle or strip includes providing an elongated metallic strip (10) having an exterior surface, and depositing a carbon-based coating (14) having an amorphous microstructure on substantially all of the exterior surface.

Description

COATED STRIP AND METHOD THEREFOR

BACKGROUND OF THE INVENTION

[0001 ] This invention relates generally to wear coatings and surface treatments and their manufacture, and more particularly to a method for applying wear treatment to strips.

[0002] Hydroentanglement is a process in which jets of high-pressure water, for example about 200 bar (3000 PSI), are used in place of needles to produce nonwoven fiber products such as composite fabrics and the like. The jets are typically produced by pumping water through thin metallic strips having a plurality of small-diameter, closely-spaced orifices formed therein. The high-velocity flow produces rapid wear in the orifices, which eventually become too enlarged to act as suitable nozzles. There have been attempts to coat such strips with anti-wear coatings. Unfortunately, it is difficult to apply such coatings to the interior of the orifices, leaving them unprotected. Furthermore, the hydroentanglement process creates a significant amount of vibration and acoustic energy which tends to cause relatively brittle prior art coatings and other known surface treatments to break up and separate from the substrate.

BRIEF SUMMARY OF THE INVENTION

[0003] Accordingly, it is an object to provide a method of applying a durable coated nozzle strip.

[0004] It is another object of the invention to provide a method of applying a durable anti-wear coating to nozzle strips.

[0005] These and other objects are met by the present invention, which according to one aspect provides a nozzle including: an elongated metallic strip having an exterior surface, and at least one orifice formed therethrough, the orifice having an interior surface; and a carbon-based coating having an amorphous microstructure disposed on substantially all of the exterior surface and the interior surface.

[0006] According to another aspect of the invention, the coating exhibits a flexural capability of at least about 35%.

[0007] According to another aspect of the invention, a plurality of spaced-apart orifices are formed through the strip, each orifice having an interior surface, wherein the coating is disposed on substantially all of the interior surfaces.

[0008] According to another aspect of the invention, the strip comprises stainless steel.

[0009] According to another aspect of the invention, the strip has opposed first and second sides, and a layer of residual compressive stress exists on one side, and a layer of residual tensile stress exists on the second side.

[0010] According to another aspect of the invention the coating has a thickness of about 2 μm to about 6 μm.

[0011] According to another aspect of the invention, the coating has a thickness of about 2 μm to about 3 μm.

[0012] According to another aspect of the invention, a method of coating a nozzle includes: providing an elongated metallic strip having an exterior surface, and at least one orifice formed therethrough, the orifice having an interior surface; and depositing a carbon-based coating having an amorphous microstructure on substantially all of the exterior surface and the interior surface.

[0013] According to another aspect of the invention, the coating is deposited using chemical vapor deposition.

[0014] According to another aspect of the invention, the step of depositing the coating includes: providing a holding fixture adapted to maintain the strip in a spiral shape; forming the strip in a spiral shape and mounting the strip in the holding fixture; depositing the coating on the strip; removing the strip from the holding fixture; and unwinding the strip into a flattened shape.

[0015] According to another aspect of the invention, the holding fixture includes a base, an upwardly-extending central post, and a plurality of radially-extending arms.

[0016] According to another aspect of the invention, at least one of the arms includes a clip at an outer end thereof adapted to receive and stabilize the strip.

[0017] According to another aspect of the invention, the base includes at least one clip disposed thereon and adapted to receive and stabilize the strip.

[0018] According to another aspect of the invention a method of coating a strip includes: providing an elongated strip having an exterior surface; providing a holding fixture adapted to maintain said strip in a spiral shape; forming said strip in a spiral shape and mounting said strip in said holding fixture; depositing a flexible wear- resistant coating on substantially all of said exterior surface; removing said strip from said holding fixture; and unwinding said strip into a flattened shape.

BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The invention may be best understood by reference to the following description taken in conjunction with the accompanying drawing figures in which:

[0020] Figure 1 is a schematic perspective view of a perforated nozzle strip coated in accordance with the present invention;

[0021] Figure 2 is an enlarged perspective view of a portion of the nozzle strip of Figure 1 ;

[0022] Figure 3 is a schematic side view of a coating apparatus for use with the present invention;

[0023] Figure 4 is a schematic perspective view of a holding fixture for use with the present invention having a nozzle strip mounted therein;

[0024] Figure 5 is a top view of the holding fixture of Figure 4;

[0025] Figure 6 is a side view of the holding fixture of Figure 4; and

[0026] Figure 7 a schematic cross-sectional view of a nozzle strip coated in accordance with the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0027] Referring to the drawings wherein identical reference numerals denote the same elements throughout the various views, Figures 1 and 2 depict an exemplary nozzle strip 10 constructed in accordance with the present invention. As used herein, the term "nozzle strip" is used to refer to a relatively thin, metallic strip having a plurality of small-diameter orifices formed therein. Such nozzle strips are common in hydroentanglement equipment. However, the present invention is equally suitable for other applications, such as non-perforated strips. In the illustrated example, the nozzle strip 10 is made from a steel alloy, for example stainless steel, and has an overall width "W" of about 12 mm (0.5 in.) to about 25 mm (1 in.) and a thickness "T" of about 0.5 mm (0.02 in.) to about 1 mm (0.04 in.). Other metals, ceramics, etc. may be used as well. It has a row or rows of small- diameter orifices 12 formed therein, at a spacing of about 1500 orifices per meter. In the illustrated example the orifice diameter "D" is about 128 microns (0.004 in.) The overall length "L" of the nozzle strip 10 varies; in the illustrated example it may be from about 600 mm (24 in.) to about 6 m (236 in.)

[0028] The entire surface of the nozzle strip 10 and at least a portion of the interior of each orifice 12 has a coating 14 of a carbon-based coating material deposited thereon. This material has an amorphous non-crystalline microstructure and exhibits a flexural capability of approximately 35% or better. This enables the coating 14 to endure significant vibration without cracking or detaching from the substrate. Such coatings may be obtained from HiDuraFlex LLC, Huntersville, NC, 28078.

[0029] Figure 3 illustrates a coating apparatus 16 for applying the coating 14 to the nozzle strip 10. The coating apparatus 16 is a plasma assisted chemical vapor deposition (PACVD) apparatus of a known type. It includes a processing chamber 18 which receives the workpiece, a hydrocarbon gas source 20, an RF field generator 22 of a known type, and a vacuum pump 24.

[0030] Prior art coating chambers are typically not large enough to practically coat nozzle strips 10 of the dimensions described above. Accordingly, the present invention provides a holding fixture 26, shown in Figures 4, 5, and 6, which allows the nozzle strip 10 to be formed in a spiral shape during the coating process. The holding fixture 26 includes a base 28, a central post 30, and a plurality of radially- extending arms 32. The height and position of each of the arms 32 may be adjustable if desired. Some of the arms 32 include arcuate clips 34 at their outer ends to receive and stabilize the nozzle strip 10. The uppermost arm 32 has an upper clamp block 36 attached to its outer end which serves to securely fasten a first end of the nozzle strip 10. A lower clamp block 38 is attached to the base 28 and serves to securely fasten a second end of the nozzle strip 10.

[0031] The coating process proceeds as follows. First, the uncoated nozzle strip 10 is formed into an extended spiral or coil shape (see Figure 4) and placed in the holding fixture 26. The arms 32 are arranged in a preselected pattern so that the elastic limit of the nozzle strip 10 will not be exceeded as it is coiled into place. Therefore, no permanent deformation of the nozzle strip 10 takes place. The holding fixture 26 is then placed in the coating chamber 18.

[0032] The nozzle strip 10 is then plasma cleaned in a known manner to eliminate any foreign material or contaminants from the surface thereof. The coating 14 is then deposited all over the exterior of the nozzle strip 10 and into the orifices 12 using a plasma assisted chemical vapor deposition (PACVD) process. The RF field which generates the plasma is specially manipulated so that the coating material is deposited "around the corner" between the surface of the nozzle strip 10 and the orifices 12. That is, the coating process does not require a direct line-of- sight to the orifices 12 to achieve a satisfactory coating therein.

[0033] Once the coating cycle is complete, the holding fixture 26 is removed from the coating chamber 18. The nozzle strip 10 is then removed from the holding fixture 26 and unwound into a flat shape. Because of the high flex capability of the coating 14, the nozzle strip 10 may be flattened without cracking or loss of the coating 14. It has been found that a nozzle strip 10 coated as described above used is approximately 10 times more wear resistant than an uncoated nozzle strip, when used in a hydroentanglement process. It is also noted that, when the nozzle strip 10 is unwound, a layer of residual compressive stress is formed on one side 40 (see Figure 7) and a layer of residual tensile stress is formed on the opposite side 42. The coating 14 retains substantially sharp, square corners at the intersections of the orifices 12 with the sides 40 and 42. In the illustrated example, the coating 14 has a thickness "t" from about 2 μm (0.08 mil) to about 6 μm (0.24 mil), and more specifically from about 2 μm (0.08 mil) to about 3 μm (0.12 mil). When the nozzle strip 10 is used for hydroentanglement, it is advantageous to orient the first side 40 so that it is exposed to the more severe wear conditions, as a surface under compressive stress is more resistant to fatigue and cracking. For example, in Figure 7, the first side 40 would be used as the discharge face for the water jet, denoted "J".

[0034] The foregoing has described coated nozzle strip, apparatus for applying a coating to such a strip, and a method for applying such a coating. While specific embodiments of the present invention have been described, it will be apparent to those skilled in the art that various modifications thereto can be made without departing from the spirit and scope of the invention. Accordingly, the foregoing description of the preferred embodiment of the invention and the best mode for practicing the invention are provided for the purpose of illustration only and not for the purpose of limitation.

Claims

WHAT IS CLAIMED IS:

1. A nozzle, comprising: an elongated metallic strip having an exterior surface, and at least one orifice formed therethrough, said orifice having an interior surface; and a carbon-based coating having an amorphous non-crystalline microstructure disposed on substantially all of said exterior surface and said interior surface.

2. The nozzle of claim 1 wherein said coating exhibits a flexural capability of at least about 35%.

3. The nozzle of claim 1 including a plurality of spaced-apart orifices formed therethrough, each having an interior surface, wherein said coating is disposed on substantially all of said interior surfaces.

4. The nozzle of claim 1 wherein said strip comprises stainless steel.

5. The nozzle of claim 1 wherein said strip has opposed first and second sides, and a layer of residual compressive stress exists on one side, and a layer of residual tensile stress exists on said second side.

6. The nozzle of claim 1 wherein said coating has a thickness of about 2 μm to about 6 μm.

7. The nozzle of claim 6 wherein said coating has a thickness of about 2 μm to about 3 μm.

8. A method of coating a nozzle, comprising: providing an elongated metallic strip having an exterior surface, and at least one orifice formed therethrough, said orifice having an interior surface; and depositing a carbon-based coating having an amorphous microstructure on substantially all of said exterior surface and said interior surface.

9. The method of claim 8 wherein said coating is deposited using chemical vapor deposition.

9. The method of claim 8 wherein said step of depositing said coating includes: providing a holding fixture adapted to maintain said strip in a spiral shape; forming said strip in a spiral shape and mounting said strip in said holding fixture; depositing said coating on said strip; removing said strip from said holding fixture; and unwinding said strip into a flattened shape.

10. The method of claim 9 wherein said holding fixture includes a base, an upwardly-extending central post, and a plurality of radially-extending arms.

11. The method of claim 10 wherein at least one of said arms includes a clip at an outer end thereof adapted to receive and stabilize said strip.

12. The method of claim 8 wherein said base includes at least one clip disposed thereon and adapted to receive and stabilize said strip.

13. The method of claim 8 wherein said coating has a thickness of about 2 μm to about 6 μm.

14. The method of claim 8 wherein said coating has a thickness of about 2 μm to about 3 μm.

15. A method of coating a strip, comprising: providing an elongated strip having an exterior surface; providing a holding fixture adapted to maintain said strip in a spiral shape; forming said strip in a spiral shape and mounting said strip in said holding fixture; depositing a flexible wear-resistant coating on substantially all of said exterior surface; removing said strip from said holding fixture; and unwinding said strip into a flattened shape.

16. The method of claim 15 wherein said strip comprises a metal.

17. The method of claim 15 wherein said holding fixture includes a base, an upwardly-extending central post, and a plurality of radially-extending arms.

18. The method of claim 17 wherein at least one of said arms includes a clip at an outer end thereof adapted to receive and stabilize said strip.

19. The method of claim 18 wherein said base includes at least one clip disposed thereon and adapted to receive and stabilize said strip.