COLD GAS SPRAY COATING METHODS AND COMPOSITIONS

Info

Publication number: 20180258539
Type: Application
Filed: Jun 29, 2015
Publication Date: Sep 13, 2018
Applicant: OERLIKON METCO (US) INC. (Westbury, NY)
Inventors: Scott WILSON (Zurich), Alexander BARTH (Wohlen), Montia NESTLER (Ridgefield, NJ), Satya N. KUDAPA (Sterling Heights, MI)
Application Number: 15/568,703

Abstract

Cold gas spray coating methods, compositions and articles. A cold gas spray method is described including spraying a composition containing at least one nickel or iron based material blended with a softer, shear-deformable, secondary phase metal and/or metal alloy, onto a surface to deposit a dense, porous coating. The compositions used in and articles produced by such methods are also described.

Description

Description

TECHNICAL FIELD

The field of art to which this invention generally pertains is cold gas spray coating.

BACKGROUND

Cold gas spray coating is a coating deposition method which uses powder material accelerated at high speeds through gas jets which adheres to a surface during impact. Metals, polymers and ceramics are some representative materials which can be deposited using cold gas spray techniques. Unlike thermal spraying methods, such as plasma spraying, arc spraying, and flame spraying, for example, the powders are not externally melted during spraying. The technology has particular utility in the area of parts repair. For example, there have been problems associated with corrosion and wear of metal alloys that are used to fabricate many different types of components. This can represent a costly and significant problem associated with large and expensive articles, such as transmission and gearbox housings for rotary aircraft, for example. Cold gas spray coating provides one method of repairing such parts. The process has also been used to repair aircraft engines, gas turbines, and parts used in the oil and gas industry, etc. While the basic technology has been found to be a cost effective and environmentally acceptable technology for providing such repair and other surface protection purposes, there is a constant search in this area for ways to make, use and improve this process in more efficient and effective ways, which can also potentially increase its usefulness and applicability.

The compositions and methods described herein meet the challenges described above, including, among other things, achieving more efficient and effective processing.

BRIEF SUMMARY

A cold gas spray method is described including spraying a composition containing a primary phase of at least one nickel or iron based material blended with a softer, shear-deformable, secondary phase metal and/or metal alloy, to deposit a dense, or porous coating on a substrate.

Additional embodiments include: the method described above where the primary phase of nickel or iron based material contains one or more of steel, stainless steel, nickel alloy, nickel superalloy, cobalt alloy, titanium alloy, and intermetallics: the method described above where the primary phase of nickel or iron based material contains one or more of nickel cladding, nickel powder, blended nickel-aluminum powder, and ceramic; the method described above where the secondary phase contains one or more of copper, aluminum, silver, zinc, platinum, palladium, and alloys thereof; the method described above where the secondary phase contains nickel particles at least partially clad with aluminum flakes; the method described above where the ceramic contains one or more of YSZ, alumina, tungsten carbides, CrC, TiO₂, TiO_{x=1.7 to 1.9}, and SiC; the method described above where the ceramic is clad with a soft ductile alloy; the method described above where the coating is at least 1 millimeter thick; the method described above where the coating has substantially no residual stress, low porosity, low oxide content, and substantially no internal cracking; the method described above where the composition is sprayed at an average velocity of at least about 600 meters per second, at spray plume temperatures less than about 1000° C., at a feed rate greater than about 20 grams per minute; the method described above where the primary and secondary phase metals are combined by one or more of mechanical blending, mechanical alloying, mechanical cladding, agglomeration by spray drying, pelletizing, chemical vapor deposition, physical vapor deposition, electrochemical deposition and/or plasma densification; the method described above where the agglomeration comprises agglomeration of nano-scale powders; the method described above where the physical vapor deposition comprises fluidized bed physical vapor deposition; the method described above where the chemical vapor deposition, physical vapor deposition, and/or electrochemical deposition comprises deposition of at least one secondary phase metal on the outer surface of at least one primary phase metal.

Additional embodiments also include: a composition particularly adapted for use in cold spray coating, comprising at least one primary phase of nickel or iron based material blended with a softer, shear-deformable, secondary phase metal and/or metal alloy; the composition described above where the primary phase of nickel or iron based material contains one or more of steel, stainless steel, nickel alloy, nickel superalloy, cobalt alloy, titanium alloy, and intermetallics; the composition described above where the primary phase of nickel or iron based material contains one or more of nickel cladding, nickel powder, blended nickel-aluminum powder, and ceramic; the composition described above where the secondary phase contains one or more of copper, aluminum, silver, zinc, platinum, palladium, and alloys thereof; the composition described above where the secondary phase contains nickel particles at least partially clad with aluminum flakes the composition described above where the ceramic contains one or more of YSZ, alumina, tungsten carbides, CrC, TiO₂, TiO_{x=1.7 to 1.9}, and SiC; the composition described above where the ceramic is clad with a soft ductile alloy; and the coated articles produced with the compositions and by the methods described above.

These, and additional embodiments, will be apparent from the following descriptions.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows representative pressures vs. velocities for particles described herein.

FIGS. 2, 3, 4 and 5 show schematic representations of some embodiments of the processes described herein.

FIGS. 6, 7, 8, 9, 10 and 11 show micrographs of some of the embodiments of the processes described herein.

FIG. 12 shows some processing parameter embodiments of the processes described herein.

FIGS. 13 and 14 show micrographs of some of the embodiments of the processes described herein.

DETAILED DESCRIPTION

The particulars shown herein are by way of example and for purposes of illustrative discussion of the various embodiments of the present invention only and are presented in the cause of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects of the invention. In this regard, no attempt is made to show details of the invention in more detail than is necessary for a fundamental understanding of the invention, the description making apparent to those skilled in the art how the several forms of the invention may be embodied in practice.

The present invention will now be described by reference to more detailed embodiments. This invention may, however, be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for describing particular embodiments only and is not intended to be limiting of the invention. As used in the description of the invention and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. All publications, patent applications, patents, and other references mentioned herein are expressly incorporated by reference in their entirety.

Unless otherwise indicated, all numbers expressing quantities of ingredients, reaction conditions, and so forth used in the specification and claims are to be understood as being modified in all instances by the term “about.” Accordingly, unless indicated to the contrary, the numerical parameters set forth in the following specification and attached claims are approximations that may vary depending upon the desired properties sought to be obtained by the present invention. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should be construed in light of the number of significant digits and ordinary rounding approaches.

Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contains certain errors necessarily resulting from the standard deviation found in their respective testing measurements. Every numerical range given throughout this specification will include every narrower numerical range that falls within such broader numerical range, as if such narrower numerical ranges were all expressly written herein.

Additional advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed.

Powder material mixtures when subjected to impact induced high shock stresses exhibit a variety of dominant and in some cases complimentary effects (see, for example, Eakins D E, Thadhani N N, “Shock Compression of Reactive Powder Mixtures”, International Materials Reviews, 2009,Vol:54, ISSN:0950-6608, Pages:181-213, hereinafter referred to as the Eakins article; also Boslough M. B., “Shock-induced Chemical Reactions in Ni—Al Powder Mixtures: Radiation Pyrometer Measurements”, Chemical Physical Letters, Vol. 150, 5/6, August 1989, p618-622, hereinafter referred to as the Boslough article; and Do, I .P. H., Benson D. J. “Micromechanical Modeling of Shock-Induced Chemical Reactions in Heterogeneous Multi-Material Powder Mixtures.” Int. Journal of Plasticity, Vol 17, 4, 2001, p.641-668) hereinafter referred to as the Do article; all of which are herein incorporated by reference):

- 1) Shear deformation to large strains with modified microstructures and high defect concentrations.
- 2) Physical changes such as phase changes e.g. phase transformations in iron and metastable steels and metal alloys (see, for example, E. Moin, L. E. Murr, Mater. Sci. Eng., 37 (3) (1979) 249 and C. J. Heathcock, B. E. Protheroe, A. Ball, Wear, 81 (1982) 311-327), or melting.
- 3) Chemical changes where reaction kinetics are accelerated by the shock energy to produce reactions such as degradation, oxidation or exothermic reactions.

These effects have recently been well documented in the literature (e.g. see the Eakins article noted above) with informative models developed to predict propensity for material combinations to chemically react or physically combine with one another to produce new stable, or metastable, materials with commercial potential, purely through the introduction of impact or shock energy.

Key parameters useful for attempting to predict the propensity of powder material combinations to chemically react with each other or, alternatively, physically combine with one another by mechanical deformation and mixing without chemical reaction, have been observed to be the following (e.g. see the Eakins article noted above):

$1) Impedance Difference = \frac{ρ_{A} C_{A} - ρ_{B} C_{B}}{ρ_{B} C_{B}} \times 100 2) Yield strength difference = \frac{σ_{A} - σ_{B}}{σ_{B}} \times 100$

Where:
ρ_A=density of powder material A, ρ_B=density of powder material B
C_A=speed of sound in material A, C_B=speed of sound in material B
σ_A=yield strength material A, σ_B=yield strength material B

Based on these equations, the following “Impedance difference” and “yield strength difference” calculations can be made using typically available data for three common materials namely Nickel, INCONEL 718 superalloy and pure Aluminum (room temperature) (see Table 1 below). Combinations of Nickel and INCONEL 718 result in a very large yield strength difference of 884% and small impedance difference of 4.9%. Combinations of Nickel and Aluminum have a much higher impedance difference of 150% with a lower yield strength difference of 320%.

Large differences in yield and impedance difference can result in large degrees of deformation inhomogeneity and inter-material mixing when they are subjected to sufficiently high impact shocks, yet the high values have been found by experimental shock testing of powder compacts (e.g. see the Eakins article noted above) (approx. 3.5 GPa) to be ineffective in terms of promoting chemical reactions between powder materials that have exothermic reaction potential e.g. between Ni and Al. Chemical reactions e.g. exothermic reactions, have been shown to be promoted for material combinations subjected to high shock stresses where impedance and yield strength differences are both low e.g. between Nickel and Silicon (e.g. see the Eakins article noted above), or Niobium and Silicon (e.g. see the Do article noted above).

TABLE 1 Yield Density: Speed of Yield Impedance strength Material ρ sound: C Strength: σ difference difference Units kg/m³ m/s Mpa % % (room temp.) (room temp.) typical value typical value Nickel 8912 4796 105 Ni vs. Ni vs. INCONEL INCONEL 718: 4.9 718: 884 INCONEL 8190 4974 1034 718 Aluminum 2700 6320 25 Al vs. Ni: Al vs. Ni: 150 320

In relating the abovementioned observations on shock deformation of compacted particles to cold gas spraying, metallic alloy powder particles are accelerated to velocities of at least 500 m/s (meters/second) and higher. Particle impact stresses produced on a rigid surface can be estimated using peak pressure calculations where the impedance is multiplied by 0.5×particle velocity (see, for example, R. C. Dykhuizen, M. F. Smith, D. L. Gilmore, R. A. Neiser, X. Jiang, S. Sampath, “Impact of High Velocity Cold Spray Particles”, Journal of Thermal Spray Technology, December 1999, Volume 8, Issue 4, pp 559-564).

For particle velocities above 500 m/s, peak contact pressures easily reach above 4 GPa for Aluminum and are some three times higher for harder INCONEL 718 and Nickel powders (FIG. 1). The range of impact stresses are similar if not higher than those observed in impact shock experiments (e.g. see the Eakins article noted above). These conditions are conducive for compaction and mechanical mixing phenomena to compacted Hugoniot dense solid. Cold gas spraying combination of alloys such as Nickel and INCONEL 718 have high mechanical mixing potential given the large yield strength difference between them and this is borne out by the high deposition efficiencies observed on cold gas spraying for example INCONEL718 powder with up to 10 wt. % pure nickel powder at the conditions shown in FIG. 12 herein, for example.

Distributing the softer nickel powder onto the entire exposed surface areas of the functional matrix alloy powder particles (e.g. INCONEL 718 powder particles of typical average diameter of 25 micron) is ideal but thoroughly impractical given the need for a higher weight percentage of nickel powder in the blend, which will inevitably negatively impact the desired mechanical, physical and chemical properties needed for engineering and commercial usage. A way to overcome this is by cladding individual INCONEL 718 particles with a thin layer of nickel e.g. 2-3 micron that can be applied using electrochemical (autoclave cladding) or chemical vapor deposition techniques as described herein. Here the amount of extra nickel added to the INCONEL 718 is of the order of 5-15wt. % and is able to function to maximum benefit by covering 100% of all INCONEL 718 particle surfaces. A typical micrograph showing such a cold gas sprayed microstructure is shown in FIG. 13 herein.

While shock compression models show that the promotion of coating densification by exothermic reactions between reactive species such as Ni and Al powders are generally not possible due to the very high yield stress difference and impedance difference measurements seen (Table 1) for these two materials, chemical reaction (exothermic) processes can be initiated if there is a large differential in particle morphology and particle size under sufficiently high impact shock stress conditions (e.g. see the Eakins article noted above) or very high impact shock stresses e.g. 14 GPa (e.g. see the Boslough article noted above). In this regard, if the particle morphologies are significantly different e.g. round particle Ni vs. smaller and flake-like Al, then chemical reactivity is observed to increase and promote exothermic reactions between Ni and Al. A part of this invention was to utilize this concept and make use of the addition of nickel particles that are clad or partially clad with aluminum flakes as a secondary “exothermic and reactive” phase that was then blended together with INCONEL 718 powder. The resultant high density microstructures and high deposition efficiencies produced through the use of such a blend are shown, for example, in FIGS. 6 to 11, 13 and 14 herein, further demonstrating the efficacy.

As stated above, cold gas deposition processes are described herein to produce dense and porous coatings. These coatings have particular applicability for aero component repair, for producing bondcoats, porous and dense metallic coatings, porous and dense metal matrix (ceramic filler) composites, and abradable coatings, among others.

The cold gas spray method described herein describes the use of binary or ternary blends of alloy combinations to deposit, primarily, thick (e.g. 1 mm with typical coating thickness ranges of above 0.2 millimeter up to 1.5 mm or more, e.g., up to 10 mm) nickel based superalloy type coatings by cold gas spray, but can be extended to other similar coating systems. Use of a harder superalloy powder e.g. INCONEL 718 together with a smaller amount (typical compositions being e.g. 5, 10, 15 or 20 wt. % with the possibility of compositions having up to 45wt %) of a soft, shear-deformable, secondary phase powder or cladding such as pure nickel or Ni—Al composite powders (or variants of Ni—Al composite powders with Al contents of typically 20 wt. % to a maximum of approximately 30 wt. %) which softens and generate heat energy during the massive shear deformation processes arising during cold spray. The heat energy is generated by plastic deformation processes or a combination of plastic deformation and exothermic reactions e.g. between unreacted Ni and Al. In addition, the concept can be altered by using fine, hard ceramic powder particles instead of/or together with the softer metal phase with the theory that the ceramic phases also generate shear mismatch and heat when deposited with a superalloy phase. The use of such unique alloy blends reduces the need for development of higher temperature/higher velocity cold gas spray parameters and equipment.

The process described herein has particular utility for repair coatings for nickel superalloy components, and especially those with high deposition efficiencies (>80% deposition efficiency), to at least 1 mm thick, with little or no residual stress (coating does not spall off or bend), low porosity i.e. <2%, low oxidation/oxide content arising from deposition process, and minimal internal cracking of coating i.e. cracks between splats; will supersede current high velocity oxy-fuel (HVOF) or Air Plasma Spray repair solutions which tend to have higher residual stress, higher porosity, higher oxidation; will reduce the need for development of “higher temperature/higher velocity” cold gas spray parameters and equipment through the use of these unique material combinations.

The process described herein, utilizes the mismatch in physical, mechanical and chemical properties between two (or more) components of a blend of alloy components where: Component 1 is a nickel superalloy such as INCONEL 718 or other superalloy such as HASTELLOY (registered trademark of Haynes International, Inc.) C276, INCONEL 625; or Component 1 is a nickel alloy such as NiCrAl, NiCrAlMo. or NiAlMo; or Component 1 is an Iron based alloy such as FeNiAlMo and Component 2 is: A softer, more ductile alloy such as Nickel, Ni-5wt %Al, Ni-20wt %Al or Al-12Si alloy, with a total weight percent less than that of Component 1, with typical ranges of 3, 4, 5, 6, 7, 8, 9 and 10 wt. % of total blend content.

The uniqueness of this approach includes the following. The blend of component 1 and 2 is sprayed using conventional cold gas spray (kinetic spray) using the following minimum basic parameters: powder particle feed spray velocities that exceed at least 600 meters/second on average, spray plume temperatures that are less than approximately 1000° C., powder feed rates that are greater than 20 gram/minute. During the spray deposition process the softer, more ductile Component 2: is deformed in preference to the harder and stiffer Component 1, deforms to very high plastic strains by compressive shear between the harder surfaces of Component 1 particles and is extruded into the voids and gaps between splats (particles of material that deform on impact) of Component 1, generates heat (friction heat and deformation energy) during the high plastic strain deformation process that assists with softening of both Components 1 & 2, generates heat during the high plastic strain deformation process via exothermic reaction between two or more components in Component 2, e.g. exothermic reaction between Nickel and Aluminum, or by an exothermic reaction between Component 2 and Component 1, is prone to adiabatic shear plastic deformation processes that encourage rapid shear localization and heat generation, with resultant high strain deformation and extrusion/melting processes.

The result of the aforementioned is deposition of nickel superalloys, (traditionally very difficult to deposit using cold gas spray with typical “best case” deposition efficiencies of around 70%, i.e., 30% of the material sprayed bouncing or failing off) with a minimum of defects and sufficient strength (similar to that attained with air plasma spray coatings, e.g., about 34 MPa or about 5000 psi) using the assistance of a small amount of a ductile or ductile/exothermic second phase that assist with welding of nickel superalloy particles together by hot-deformation (or exothermic) reactions and minimal influence on overall chemistry of the superalloy coating.

Exemplary variations of the above can include the following: where Component 2 is changed to: a fine powder material that is much harder than Component 1 such as a ceramic e.g. alumina or yttria stabilized zirconia (YSZ); a fine powder material that is much harder than Component 1 such as a ceramic e.g. alumina or YSZ that is clad with a soft ductile alloy such as nickel or composite Ni-Al powder. The outcome of using such a variation is to utilize the high hardness and elastic modulus mismatch of the ceramic to initiate high plastic shear strains onto the surfaces, with eventual penetration into the surfaces of the Component 1 particle surfaces during the deformation/impact process. In addition, since ceramics tend to have low thermal diffusivity/conductivity, the generation of high friction heating effects at the contact interfaces between ceramic and metal alloy surfaces is likely to be greatly enhanced and assist with welding and diffusion processes.

Further exemplary variations of the above can include: where Component 2 is changed to: Aluminum bronze alloy e.g. Cu 9.5Al 1 Fe or Cu 10Al or bronze alloy of similar composition. In addition, Component 1 further alloy variations can include: NIMONIC 80A and variants. e.g. Ni (bal.) 18Cr 2Ti 1.5Al11Si 0.2Cu 3Fe 1 Mn 2Co 0.1 C 0.15Zr; NIMONIC 75 and variants; INCONEL 600, INCONEL 617, INCONEL 625 and variants; HASTELLOY W, HASTELLOY N, HASTELLOY X, HASTELLOY C, HASTELLOY B and variants; Haynes 214, Haynes 230 and variants; CMSX-4 alloy and variants; Cobalt based alloys such as commonly known STELLITE™ (Kennametal Stellite Company) or STELLITE-like alloys; CoNiCrAlY and NiCrAlY alloys typically used as bondcoats for thermal barrier coatings.

Further exemplary variations of the above can include Component 1 using one (or more) of the alloys above (powder morphology): Component 1 powder is clad with a thin layer of nickel metal e.g. about 0.5 to about 5 microns thick (or close to this range) using electroless chemical cladding techniques, or chemical autoclave cladding or chemical vapor deposition techniques; Alternatives to using nickel cladding include metal variants such as copper, zinc, aluminum, iron and alloys of these with nickel.

EXAMPLE 1

The following blends were sprayed as described below: Sample 1: a blend of INCONEL 718 with 5 wt. % Metco 480NS (Ni-5Al); Sample 2: a blend of INCONEL 718 with 5 wt % pure Nickel; Sample 3: a blend of HASTELLOY C276 with 5 wt % pure Nickel. The above powders were sprayed using cold gas spray parameters using a conventional Kinetiks 8000 gun typically under the following conditions: Temperatures (process flow gas): 900° C.-950° C.; Process flow gas (m³/h) : 92-94; Gas pressure: 40 bar; Spray distances: 40-60 mm; Coating thickness: approx. 1 mm; Powder feed rate: 30-34 g/min. For the selected the parameters, deposition efficiencies of over 80% were obtained, and at least 88% deposition efficiencies were obtained for each powder blend using an optimised parameter.

Micrographs of the coatings are shown in FIGS. 5 to 10 and 14. All coatings had measured porosities below 1.6% Hardness (Vickers HV03 (ASTM E384)) of each coating was measured and are as shown in the figures. Typically 450-460 HV03 was the range obtained for all as-sprayed coatings.

EXAMPLE 2

Some examples of material combinations which can be used are shown in the following tables, Tables 2 to 4.

TABLE 2 Second Phase Base Alloy Addition Approximate Second Approximate Size Range Phase Size Range Base Alloy μm Addition Weight % μm INCONEL −30 to +5 Nickel 3 to 10 −30 to +5/ 718 −45 to +11 INCONEL −30 to +5 Ni—5Al 3 to 10 −30 to +5/ 718 −45 to +11 INCONEL −30 to +5 Ni—20Al 3 to 10 −125 to +45 718 INCONEL −30 to +5 Ni—Al—Mo 3 to 10 −125 to +45 718 INCONEL −30 to +5 Ni 5Mo 5.5Al 3 to 10 −90 to +45 718 INCONEL −30 to +5 NiCrAlMo 3 to 10 −90 to +45 718 INCONEL −30 to +5 NiCrAl 3 to 10 −125 to +45 718 INCONEL −30 to +5 Al—12Si 3 to 10 −125 to +45 718 INCONEL −30 to +5 Alumina 3 to 10 −30 to +5 718 INCONEL −30 to +5 8YSZ 3 to 10 −30 to +5 718

TABLE 3 Base Alloy Second Phase Approximate Second Approximate Size Range Phase Size Range Base Alloy μm Addition Weight % μm NiCrWMo −30 to +5 Nickel 3 to 10 −30 to +5/ (e.g., HASTELLOY C276) −45 to +11 NiCrWMo −30 to +5 Ni—5Al 3 to 10 −30 to +5/ −45 to +11 NiCrWMo −30 to +5 Ni—20Al 3 to 10 −125 to +45 NiCrWMo −30 to +5 Ni—Al—Mo 3 to 10 −125 to +45 NiCrWMo −30 to +5 Ni 5Mo 5.5Al 3 to 10 −90 to +45 NiCrWMo −30 to +5 NiCrAlMo 3 to 10 −90 to +45 NiCrWMo −30 to +5 NiCrAl 3 to 10 −125 to +45 NiCrWMo −30 to +5 Al—12Si 3 to 10 −125 to +45 RENE ® 80 (READE) −30 to +5 Nickel 3 to 10 −30 to +5/ Ni14Cr4Mo3Al5Ti9.5Co4W −45 to +11 RENE 80 −30 to +5 Ni—5Al 3 to 10 −30 to +5/ −45 to +11 RENE 80 −30 to +5 Ni—20Al 3 to 10 −125 to +45 RENE 80 −30 to +5 Ni—Al—Mo 3 to 10 −125 to +45 RENE 80 −30 to +5 Ni 5Mo 5.5Al 3 to 10 −90 to +45 RENE 80 −30 to +5 NiCrAlMo 3 to 10 −90 to +45 RENE 80 −30 to +5 NiCrAl 3 to 10 −125 to +45 RENE 80 −30 to +5 Al—12Si 3 to 10 −125 to +45 FeNiAlMo −30 to +5 Nickel 3 to 10 −30+5/ −45 to +11 FeNiAlMo −30 to +5 Ni—5Al 3 to 10 −30+5/ −45 to +11 FeNiAlMo −30 to +5 Ni—20Al 3 to 10 −125 to +45 FeNiAlMo −30 to +5 NiCrAl 3 to 10 −125 to +45

TABLE 4 Nickel Nickel Ni—Al Softer Main Cladding* Powder** Powder** Alloy** Ceramics Component (NC) (NB) (NiAl) (SA) (CER) Steels (St) (St) + ≥5- (St) + ≥5- (St) + ≥5- (St) + ≥5- (St) + ≥5- 20 wt % (NC) 40 wt % (NB) 40 wt % (NiAl) 40 wt % (SA) 40 wt % (CER) Stainless (SS) + ≥5- (SS) + ≥5- (SS) + ≥5- (SS) + ≥5- (SS) + ≥5- Steels (SS) 20 wt % (NC) 40 wt % (NB) 40 wt % (NiAl) 40 wt % (SA) 40 wt % (CER) Nickel (NA) + ≥5- (NA) + ≥5- (NA) + ≥5- (NA) + ≥5- (NA) + ≥5- Alloys (NA) 20 wt % (NC) 40 wt % (NB) 40 wt % (NiAl) 40 wt % (SA) 40 wt % (CER) Nickel (NSA) + ≥5- (NSA) + ≥5- (NSA) + ≥5- (NSA) + ≥5- (NSA) + ≥5- Superalloys 20 wt % (NC) 40 wt % (NB) 40 wt % (NiAl) 40 wt % (SA) 40 wt % (CER) (NSA) Cobalt (CA) + ≥5- (CA) + ≥5- (CA) + ≥5- (CA) + ≥5- (CA) + ≥5- Alloys (CA) 20 wt % (NC) 40 wt % (NB) 40 wt % (NiAl) 40 wt % (SA) 40 wt % (CER) Titanium (TA) + ≥5- (TA) + ≥5- (TA) + ≥5- (TA) + ≥5- Alloys (TA) 20 wt % (NC) 40 wt % (NB) 40 wt % (NiAl) 40 wt % (SA) Intermetallics (INT) + ≥5- (INT) + ≥5- (INT) + ≥5- (INT) + ≥5- (INT) 20 wt % (NC) 40 wt % (NB) 40 wt % (NiAl) 40 wt % (SA) Ceramics (CER) (CER) + ≥5- (CER) + ≥5- (CER) + ≥5- (CER) + ≥5- 20 wt % (NC) 40 wt % (NB) 40 wt % (NiAl) 40 wt % (SA) *Clad layer over surface of powder core **Blended

EXAMPLE 3

Some examples of material combinations which can be used and representative properties are shown in the following table.

TABLE 5 Coating Attribute/ Average/ Material state Property Units typical Minimum Maximum Inconel 718 + as-sprayed Coating g/cm³ 7.35 7.10 7.60 5% wt. % density Ni-5 wt % Al Inconel 718 + as-sprayed porosity % 0.6 0.00 2.00 5% wt. % Ni-5 wt % Al Inconel 718 + as-sprayed Deposition % 72 60.6 89.0 5% wt. % efficiency Ni-5 wt % Al Inconel 718 + as-sprayed Tensile MPa Greater than 34 is 5% wt. % strength 36 MPa specified Ni-5 wt % Al according to lower limit ASTM C 633 Inconel 718 + as-sprayed Hardness HV300gf 460.30 420 499 5% wt. % (Vickers (kg · mm⁻²) Ni-5 wt % Al diamond) Inconel 718 + Annealed Hardness HV300gf 251.6 229 276 5% wt. % (1060° C./2 h (Vickers (kg · mm⁻²) Ni-5 wt % Al in vacuum) diamond) Inconel 718 + as-sprayed Coating mm 10 0 15 5% wt. % and annealed thickness Ni-5 wt % Al

Representative steel and stainless steel alloys useful with the processes described herein can comprise: Fe balance (bal.) +qCr+rAl+sMo+tCo+xMn+xNi+zC+uN+wV in any combination, where: q, r, s, t, x, y, z, u, w=any value between 0 to 50 wt (weight) % provided that the sum thereof is no greater than 70%.

Representative nickel alloys useful with the processes described herein can comprise: Ni (bal.) +qCr+rAl+sMo+tCo+xMn+xFe+zC+uY+vCu+wSi in any combination, where: q, r, s, t, x, y, z, u, v =any value between 0 to 50 wt % provided that the sum thereof is no greater than 70% wt %.

Representative cobalt alloys useful with the processes described herein can comprise: Co (bal.) +qCr +rAl +sMo +tNi +xY +xFe +zC +uCu +wSi in any combination, where: q, r, s, t, x, y, z, u, wSi =any value between 0 to 50 wt % provided that the sum thereof is no greater than 70% wt %.

Representative nickel super alloys useful with the processes described herein can comprise: INCONEL 718, HASTELLOY (Haynes International) C276, INCONEL (Special Metals Corporation) 625, NiCrAl, NiCrAiMo, NiAlMo, NIMONIC™(Special Metals Corporation) 80A, Ni 18Cr 2Ti 1.5A11Si 0.2Cu 3Fe 1 Mn 2Co 0.1 C 0.15Zr, NIMONIC 75, INCONEL 600, INCONEL 617, INCONEL 625, HASTELLOY W, HASTELLOY N, HASTELLOY X, HASTELLOY C, HASTELLOY B, Haynes 214, Haynes 230, CMSX-4 alloy, Cobalt based alloys, STELLITE, CoNiCrAlY and/or NiCrAlY alloys.

Representative titanium alloys useful with the processes described herein can comprise: Ti-6Al-4V and all titanium alloy grades 6 to 38.

Representative intermetallics useful with the processes described herein can comprise: NiAl, NiAl₃, Ni₃Al, TiAl, Ti₃Al, Fe₃Al, Ni₃Si, CrSi₂, MoSi2, NbSi₂, TaSi₂, VSi₂, and TiSi₂.

Representative ceramics useful with the processes described herein can comprise: YSZ, Alumina, tungsten carbides, CrC, TiO₂, TiO_{x=1.7 to 1.9}, SiC and powders with a size range of about 3 to about 120 micrometers mean diameter.

Representative nickel cladding useful with the processes described herein can comprise: electroless deposited nickel, chemically vapor deposited nickel (CVD) or chemically autoclave clad nickel, nickel metal ≥97wt. %, cladding thickness ranges of about 0.2 to about 15 micrometers thick, cladding surface coverage of a minimum of about 10% of surface area to about 100% of surface area of powder particle (core).

Representative nickel powder useful with the processes described herein can comprise: nickel powder, nickel metal ≥97wt. % Ni, and size ranges of about 3 to about 50 micrometers mean diameter.

Representative nickel-aluminum powders useful with the processes described herein can comprise: nickel clad aluminum, typically Ni+xAl where x=about 5 to about 30 wt %, Ni5Al type such as Diamalloy 4008NS, Metco 450NS, Metco 450P, and Metco 480NS, Ni 20Al type such as Metco 404NS, Metco 1101, and Metco 2101ZB. Also, NiAlMo such as Ni 5Mo 5.5Al agglomerated (mechanically clad) powders, e.g. Metco 447NS.

Representative softer alloys useful with the processes described herein can comprise: copper and typical alloys of copper: including: Cu (bal.) +xNi+yAl+zZn+uSn in any combination, where: x, y, z, u=any value between 0 to about 50 wt % provided that the sum thereof is no greater than 70 wt %; aluminum and typical alloys of Al: including: Al(bal.) +xCu+xMg+yMn+zZn+uSi in any combination, where: x, y, z, u=any value between 0 to about 50 wt % provided that the sum thereof is no greater than 70 wt %; silver metal ≥97wt. % Ag, and silver alloys; zinc metal ≥97wt. % Zn and zinc alloys; platinum and palladium metal ≥97wt. % Pt or Pd, and Pt and Pd alloys.

FIG. 2 demonstrates the dynamic impact/contact between the particles where particle velocity is generally >500 m/s. The particle size ranges A & B generally are <50 microns. There will be one or more of a flow (yield) strength mismatch between materials A and B where: A >B; hardness mismatch between materials A and B where: A>B; elastic (Young's) modulus mismatch between materials A and B where: A>B. Generation of friction heat at interfaces between A & B due to deformation (forging) processes will be localized mostly in material B.

In FIG. 3, shows resultant forging and friction welding where, e.g., Component 1 (A) can be e.g. INCONEL 718, and Component 2 (B), e.g. Nickel or Ni-5Al. Softer shearable second phase material such e.g. Nickel or Ni-5Al or other soft alloy is introduced, which deforms/shears easily, generates heat by friction contact /shear between harder INCONEL 718 particles, for example; generates heat by friction/exothermic reaction e.g. NiAl. Other approaches which can also be used are combinations of powders that either react during spraying or can be diffusion treated post deposition.

In FIG. 4, Component 41 can be e.g. INCONEL 718, and Component 42 can be nickel or nickel-5 Al or other soft alloy. The softer shearable second phase material such e.g. Nickel or Ni-5Al or other soft alloy is introduced and: deforms/shears easily generating heat by friction contact /shear between harder INCONEL 718 particles, and/or generates heat by friction/exothermic reaction, e.g. NiAl. High shear zone 43 indicates friction heating. Other approaches which can be used are a combination of powders that either react during spraying or can be diffusion treated post deposition.

In FIG. 5, Component 1 (51) can be, e.g. INCONEL 718 and Component 2 (52) can be e.g. alumina or YSZ. High shear zone 53 indicates friction heating. This zone can also be generated, e.g., by introducing a harder, ceramic, non-shearable second phase material such e.g. alumina or YSZ, which generates heat by friction contact /shear between softer INCONEL 718 particles.

FIGS. 6 and 7 show micrographs of an embodiment of a process described herein where a INCONEL 718 plus 5% NiAl alloy is applied by conventional cold gas processing to a substrate (61, not shown in FIG. 7) utilizing a KINETICS® 8000 gun (Sulzer Metco), the coating material (62 and 71) is Sample 1, the porosity is 1.6%, and the micro hardness is 453 HVO.3 s=32 (ASTM E384).

FIGS. 8 and 9 show micrographs of an embodiment of a process described herein where a INCONEL 718 plus 5% NiAl alloy is applied by conventional cold gas processing to a substrate (81, not shown in FIG. 9) utilizing a Kinetic 8000 gun, the coating material (82 and 91) is Sample 2, the porosity is 1.5%, and the micro hardness is 460 HVO.3 s=26.

FIGS. 10 and 11 show micrographs of an embodiment of a process described herein where a HASTELLOY C276 plus 5% NiAl alloy is applied by conventional cold gas processing to a substrate (101, not shown in FIG. 11) utilizing a Kinetic 8000 gun, the coating material (102 and 111) is Sample 3, the porosity is 1.2%, and the micro hardness is 468 HVO.3 s=28.

FIG. 12 shows some exemplary cold gas spray parameters and deposition efficiencies (shown in the circles on the graph). See also Table 6 below using Sample 2.

FIG. 13 shows an example of a cold gas sprayed coating microstructure (conventionally etched after coating, e.g, with a dilute solution of copper sulfate) comprised of INCONEL 718 (131) with softer outer layer of pure nickel (132) which was clad on INCONEL 718 particles using a conventional electrochemical coating method prior to cold gas spraying.

FIG. 14 shows an example of a cold gas sprayed INCONEL 718 coating (142) deposited onto an INCONEL 718 substrate (141). The typical composition of the powder used was INCONEL 718 5 wt % Ni5Al which was cold gas sprayed to a thickness of over 10 mm.

TABLE 6 Carrier Process Process Deposition Gas Gas Spray Run Gas Temp. Gas Efficiency Pressure Pressure Distance No. ° C. m³/hour % (bar) (bar) mm 1 900 94 60 6 40 60 2 900 92 79 10 40 60 3 900 94 65 6 40 40 4 900 92 86 10 40 40 5 950 94 69 6 40 40 6 950 92 90 10 40 40

Thus, the scope of the invention shall include all modifications and variations that may fall within the scope of the attached claims. Other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following claims.

Claims

1. A cold gas spray method comprising spraying a composition containing a primary phase of at least one nickel or iron based material blended with a softer, shear-deformable, secondary phase metal and/or metal alloy, to deposit a dense, or porous coating on a substrate.

2. The method of claim 1, wherein the primary phase of nickel or iron based material contains one or more of steel, stainless steel, nickel alloy, nickel superalloy, cobalt alloy, titanium alloy, and intermetallics.

3. The method of claim 1, wherein the primary phase of nickel or iron based material contains one or more of nickel cladding, nickel powder, blended nickel-aluminum powder, and ceramic.

4. The method of claim 1, wherein the secondary phase contains one or more of copper, aluminum, silver, zinc, platinum, palladium, and alloys thereof.

5. The method of claim 1, wherein the secondary phase contains nickel particles at least partially clad with aluminum flakes.

6. The method of claim 3, wherein the ceramic contains one or more of YSZ, alumina, tungsten carbides, CrC, TiO2, TiOx=1.7 to 1.9, and SiC.

7. The method of claim 3, wherein the ceramic is clad with a soft ductile alloy.

8. The method of claim 1, wherein the coating is at least 1 millimeter thick.

9. The method of claim 1, wherein the coating has substantially no residual stress, low porosity, low oxide content, and substantially no internal cracking.

10. The method of claim 1, wherein the composition is sprayed at an average velocity of at least about 600 meters per second, at spray plume temperatures less than about 1000° C., at a feed rate greater than about 20 grams per minute.

11. The method of claim 1, wherein the primary and secondary phase metals are combined by one or more of mechanical blending, mechanical alloying, mechanical cladding, agglomeration by spray drying, pelletizing, chemical vapor deposition, physical vapor deposition, electrochemical deposition and/or plasma densification.

12. The method of claim 11, wherein the agglomeration comprises agglomeration of nano-scale powders.

13. The method of claim 11, wherein the physical vapor deposition comprises fluidized bed physical vapor deposition.

14. The method of claim 11, wherein the chemical vapor deposition, physical vapor deposition, and/or electrochemical deposition comprises deposition of at least one secondary phase metal on the outer surface of at least one primary phase metal.

15. A composition particularly adapted for use in cold spray coating, comprising at least one primary phase of nickel or iron based material blended with a softer, shear-deformable, secondary phase metal and/or metal alloy.

16. The composition of claim 15, wherein the primary phase of nickel or iron based material contains one or more of steel, stainless steel, nickel alloy, nickel superalloy, cobalt alloy, titanium alloy, and intermetallics.

17. The composition of claim 15, wherein the primary phase of nickel or iron based material contains one or more of nickel cladding, nickel powder, blended nickel-aluminum powder, and ceramic.

18. The composition of claim 15, wherein the secondary phase contains one or more of copper, aluminum, silver, zinc, platinum, palladium, and alloys thereof.

19. The composition of claim 15, wherein the secondary phase contains nickel particles at least partially clad with aluminum flakes

20. The composition of claim 17, wherein the ceramic contains one or more of YSZ, alumina, tungsten carbides, CrC, TiO x=1.7 to 1.9, and SiC.

21. The composition of claim 17, wherein the ceramic is clad with a soft ductile alloy.

22. The coated article produced by the method of claim 1.