Abstract:
A metal matrix composites is used to laser clad a surface, such as a base metal machine element, and provide high wear and corrosion resistance, particularly useful for protecting surfaces in a salt water environment. The composites may comprise up to 25 wt % Mo and up to 20 wt % WC particles in a Nickel Alloy matrix; a nickel Alloy containing 5-30% Chromium, 0-20% Molybdenum, and 0-10% Tungsten or Niobium, with the balance being Nickel.

Description:
CROSS-REFERENCE TO RELATED PATENT APPLICATIONS 
       [0001]    This application claims priority from Provisional Application U.S. Application 61/305,852, filed Feb. 18, 2010, incorporated herein by reference in its entirety. 
     
    
     FIELD OF THE DISCLOSURE 
       [0002]    This disclosure relates to metal matrix composites used to clad a surface and provide high wear and corrosion resistance. The technology disclosed is particularly useful for protecting surfaces in a salt water environment. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0003]      FIG. 1  is a series of metallographic photographs of porosity and dilution that foreshadow corrosion. 
           [0004]      FIG. 2  is a series of photographs illustrating wet/dry corrosion results of coated rods. 
           [0005]      FIG. 3  is a photomicrograph representative of an MMC6 flat plate sample. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0006]    Machines and equipment often are required to function in harsh applications where they are subject to corrosion. Specific examples include the off-shore, oil/gas equipment and many military applications that require that hydraulic cylinders with rod coatings function dependably in harsh marine environments. 
         [0007]    Many hydraulic systems rely on hard chrome, nickel-chrome, plasma thermal spray, or High Velocity Oxygen Fuel (HVOF) thermal spray coating methods to protect components that have proven ineffective in marine conditions involving a corrosive, salt water environment. 
         [0008]    These existing coating technologies do not meet the corrosion, wear, impact, or fatigue resistance needed for the field conditions encountered by loaded structures in a marine environment. Thermal sprays and electrolytic hard chrome coatings are porous and weakly bonded to the base material, which tend to corrode quickly in marine environments and spall under load conditions typical of a hydraulic piston rod. 
         [0009]    For example, offshore oil drilling platforms typically employ cylinder tensioning systems, called Direct Acting Tensioners (DAT), where the piston rod is submerged in the ocean. These approximately 50 foot long cylinder rods are required to function in the most difficult combination of conditions: saltwater corrosion, temperature extremes, tensile and bending load fatigue, and constant cyclic sliding wear motion with the ocean swell. Industry experience indicates that even advanced forms of existing coating technology, such as HVOF over carbon steel or stainless steel substrates, do not meet the corrosion, wear, or fatigue resistance needed for the aggressive marine field conditions, such as those encountered by the hydraulic cylinders on a oil drilling vessel. 
         [0010]    The technology disclosed is not limited to hydraulic cylinders in marine environments. The technology has broad application in a number of environments, including, by way of example and not by way of limitation: new hydraulic piston rods (replacing prior coating technology); repair of old chrome or thermal spray piston rods; boiler tubes &amp; pressure vessel cladding; corrosion resistant rebars &amp; dowels for construction &amp; infrastructure; wear blocks for bearing surfaces on flat or round slides; marine propeller shafting; hard-facing pads on drills; and any other environment where corrosion and wear need to be minimized. 
         [0011]    Based on industry reports, only a cost prohibitive, uncoated rod of solid Alloy 625 has been shown to provide 12+ years of field operation. Weld overlays with highly corrosion resistant Alloys (CRA), such as Alloy 625, have the potential to provide the performance of a solid CRA at a fraction of the cost. A weld overlay is a fusion process where a desirable material is metallurgically bonded to a base material to provide different properties at the surface of the base material. Hard facing for wear resistance and cladding for corrosion resistance are two common weld overlay applications. 
         [0012]    When properly applied, Alloy 625 can provide sufficient corrosion protection, and it also has a low hardness when compared with other hard facings, and therefore, provides only limited wear resistance. 
         [0013]    The metallographic examination in  FIG. 1  indicates that the porosity and bonding of the HVOF process are inadequate for the rigors of structural cyclic load service in corrosive marine conditions. The left three pictures illustrate high porosity, cracking, and rapid corrosion resulting from chrome electroplating, thermal spray, and traditional weld overlay methods. Traditional weld overlays reveals poor process heat control, significant dilution in excess of 20%, and significant weld boundary defects. These processing defects lead to pitting corrosion in 100-1000 hrs of cyclic wet/dry saltwater testing, conducted by a protocol similar to ISO 14993 (4), as shown in the left three pictures of  FIG. 2 . 
         [0014]    The disclosed precision laser technology provides improved levels of process control and more wear/corrosion resistant chemistries to provide a metallurgical bond with a nearly seamless transition from the low cost base material to a highly corrosion resistant coating, as illustrated by the right-most pictures of Tables 1 and 2. Further, laser powder deposition cladding allows for the creation of unique Alloy blends and wear particle combinations, called metal matrix composites (MMC), that are not available in solid form or by other coating processes. Laser cladding involves the use of a laser beam to provide a focused, uniform, and precise source of heat that has superior control to arc forms of heating used in other welding and weld overlay processes, such as metal-inert gas (MIG), tungsten-inert gas (TIG), and plasma transfer arc (PTA) processes. 
         [0015]    Thermal spray processes such as plasma and HVOF may be able to provide similar powder chemistries, but cannot provide the same degree of metallurgical bonding as laser cladding. Other fusion process used in traditional weld overlay may be able to provide an adequate metallurgical bond, but cannot provide the chemistry or quality of the disclosed laser processing methods and compositions, which provide a MMC suitable for powder deposition laser cladding that testing shows to be a viable rod coating for such applications as hydraulic piston rods in demanding marine environments. 
         [0016]    The amount of base material melted into the coating to create the metallurgical bond is called dilution. Dilution can be measured using Energy Dispersive X-ray (EDAX) analysis or can be calculated from a prepared cross section. 
         [0000]    
       
         
           
             
               Dilution 
                
               
                   
               
                
               % 
             
             = 
             
               
                 Area 
                  
                 
                     
                 
                  
                 of 
                  
                 
                     
                 
                  
                 base 
                  
                 
                     
                 
                  
                 material 
                  
                 
                     
                 
                  
                 melted 
               
               
                 
                   Area 
                    
                   
                       
                   
                    
                   of 
                    
                   
                       
                   
                    
                   base 
                 
                 + 
                 deposit 
               
             
           
         
       
     
         [0017]    Traditional coating methods, when employing typical process parameters, yield a dilution of greater than 10%. It has generally been thought that higher dilution provides the benefits of improved metallurgical compatibility, thereby creating good welds. However, based on the present disclosure, it has been determined that, contrary to the accepted view, high levels of dilution can lead to the previously described corrosion failures, with lower levels of dilution providing superior results. 
         [0018]    In an attempt to provide a superior rod coating, various Alloys and MMCs were evaluated. Based on experimental results, Alloy 625LCF (U.S. Pat. No. 4,765,956) was selected as a base matrix material due to commercial availability, laboratory reports, process cladability evaluations, and field reports. Other alloys may also be used, including Alloy 625 (UNS N06625), Alloy 626 (UNS N06626), Alloy 622 (UNS N06022), and Alloy 686 (UNS N06686), Alloy 59 (UNS N06059), or similar powder composition as marketed by Deloro Stellite under trade name Nistelle Super C. 
         [0019]    A number of wear and metal particles were selected for MMC sampling in an attempt to improve the corrosion resistance and wear resistance of the base Alloy 625. Molybdenum (Mo) and Tungsten Carbide (WC) proved to be soluble and maintained even dispersions in the Alloy 625 powder. Tables 1 and 2 describe the Alloy 625, Mo, WC, and substrate steel that were used in subsequent evaluations. Such alternatives as alumina, titania, chrome oxide, and nano-scale WC were evaluated and determined not to be compatible with the physical mixing process, the fluidized Argon delivery process, or both. It should be noted that additional powder processing methods known to those skilled in the art, such as use of chemical binders, custom milling, selective sintering, agglomeration, and the like, may be deployed to correct issues of particle dispersion and accommodate a wider range of materials. For example, small wear particles might be bonded to larger carriers that ultimately disperse and melt into the surrounding matrix. 
         [0020]    When using the process conditions described below, the Mo was found to stay as particle form in the fully fused Alloy 625 matrix with only a slight diffusion of the particle into the surrounding matrix. While not wishing to be bound by any theory, applicants believe that this controlled diffusion strengthened the nickel matrix and allowed the use of Mo loadings for corrosion resistance that have not been known to be available in any other fused coating or homogeneous chemistry, wrought, nickel Alloy. As discussed below, this resulted in improved corrosion, wear, erosion, abrasion, coefficient of friction values over previous Alloy 625 materials. The addition of WC provided further improvements to the wear resistance without reducing the corrosion resistance of the 625 Alloy matrix. 
         [0000]    
       
         
               
             
               
               
               
               
               
             
               
               
               
               
               
             
           
               
                 TABLE 1 
               
             
             
               
                   
               
               
                 Powder Data 
               
             
          
           
               
                   
                   
                   
                 Melt  
                 Typical 
               
               
                 Powder 
                   
                 Particle Size/ 
                 Temper- 
                 Density 
               
               
                 Name(s) 
                 Chemistry 
                 Morphology 
                 ature 
                 “as Clad” 
               
               
                   
               
             
          
           
               
                 Alloy 625 
                 Ni 21.5Cr 9Mo  
                 −177 + 44 μm 
                 2350-  
                 0.305 lb/in 3   
               
               
                   
                 3.5Nb &lt;1Fe  
                 Spheroidal,  
                 2460° F. 
                  8.44 g/cm 3   
               
               
                   
                 &lt;0.5Si 
                 Gas  
                 1290- 
                   
               
               
                   
                   
                 Atomized 
                 1350° C. 
                   
               
               
                 Molybdenum 
                 Mo &lt;1 Other 
                 −91 + 37 μm 
                 4753° F. 
                  10.3 g/cm 3   
               
               
                 (Metal 
                   
                 Spheroidal, 
                 2623° C. 
                   
               
               
                 Particle) 
                   
                 Agglomerated 
                   
                   
               
               
                 Tungsten 
                 W 3.8C 
                 −45 + 15 μm 
                 5198° F. 
                  15.8 g/cm 3   
               
               
                 Carbide 
                   
                 Spheroidal,  
                 2870° C. 
                   
               
               
                 (Wear 
                   
                 Fused 
                   
                   
               
               
                 Particle) 
                   
                   
                   
                   
               
               
                   
               
             
          
         
       
     
         [0000]    
       
         
               
             
               
               
               
               
               
             
               
               
               
               
               
             
           
               
                 TABLE 2 
               
             
             
               
                   
               
               
                 Substrate Data 
               
             
          
           
               
                 Substrate 
                   
                 Melt  
                   
                   
               
               
                 Name 
                 Chemistry 
                 Temp 
                 Hardness 
                 Density 
               
               
                   
               
             
          
           
               
                 1018 Steel 
                 Fe .81Mn .21Si  
                 2640° F. 
                 71 RHB 
                 0.283 lb/in 3   
               
               
                   
                 .21Cu .17C .08Cr 
                   
                   
                   
               
               
                   
               
             
          
         
       
     
         [0021]    Equipment used for evaluations included a 4000 Watt (W) high powered diode laser with a 5 mm spot, a 2 mm weld overlap, and a 25 mm standoff from the work piece. The base metal substrate geometry to be coated was supported in a rotary, if round, or placed on a work table, if flat. The system utilized a powder feeder with an inert cover gas, typically 99.99% pure Argon. All %&#39;s are on a dry weight basis. The powder was fed into a funnel-shaped nozzle that was coaxial with the laser. The laser was able to provide uniform heat to melt the fed powder, along with a small amount of the base material, which were maintained under inert gas cover. 
         [0022]    The individual powders were weighed and physically blended in 5-10 pound batches until uniform dispersion was visually confirmed. Such batches typically required 5 to 10 minutes of blending to provide adequate dispersion. The powder mixture was then funneled into the powder feeder to the laser sampling process. The laser power, cladding speeds, powder feed rates, and preheat temperatures were varied to obtain superior porosity, dilution, and particulate dispersions. 
         [0023]    Table 3 summarizes the chemistry of the experimental MMC mixtures. The WC particles can be classified synonymously as wear particles, while the Mo particles can be synonymously referred to as metallic particles. Tables 4-7 summarize process parameters used in evaluation of round samples and flat samples, respectively, using the materials described in Table 3. (HAZ=depth of heat effective zone and HV=Vickers hardness value.) These process conditions do not represent the entire limits by which the process could be applied by one skilled in the art. The process parameters and MMC mixtures are believed to be able to provide similar utility with other nickel alloy matrixes and with other available wear particles in either nano or micro powder sizes, provided adequate methods are used for particle dispersion, as was discussed above. 
         [0000]    
       
         
               
             
               
               
               
               
               
             
               
               
               
               
               
             
           
               
                 TABLE 3 
               
             
             
               
                   
               
               
                 MMC Experimental Mixture 
               
             
          
           
               
                   
                   
                 Weight % 
                 Weight % 
                 Weight % 
               
               
                   
                 Alloy 
                 WC Particles 
                 Mo Particles 
                 Alloy 625 
               
               
                   
                   
               
             
          
           
               
                   
                 Alloy 625 
                 0 
                 0 
                 100 
               
               
                   
                 MMC1 
                 10 
                 0 
                 90 
               
               
                   
                 MMC2 
                 20 
                 0 
                 80 
               
               
                   
                 MMC3 
                 0 
                 10 
                 90 
               
               
                   
                 MMC4 
                 0 
                 20 
                 80 
               
               
                   
                 MMC5 
                 0 
                 25 
                 75 
               
               
                   
                 MMC6 
                 10 
                 10 
                 80 
               
               
                   
                 MMC7 
                 5 
                 5 
                 90 
               
               
                   
                 MMC8 
                 7.5 
                 7.5 
                 85 
               
               
                   
                 MMC9 
                 3 
                 3 
                 94 
               
               
                   
                   
               
             
          
         
       
     
         [0000]    
       
         
               
             
               
               
               
               
               
               
             
               
               
               
               
               
               
             
           
               
                 TABLE 4 
               
             
             
               
                   
               
               
                 Round Samples 
               
               
                 Round Samples on 1.5 inch OD 1018 cold finished steel bar 
               
             
          
           
               
                   
                   
                   
                 Porosity 
                   
                 HAZ  
               
               
                 Sample 
                   
                   
                 (ASTM 
                 HAZ 
                 Hardness 
               
               
                 ID 
                 Chemistry 
                 Dilution 
                 E2109) 
                 Depth 
                 (HV) 
               
               
                   
               
             
          
           
               
                 — 
                 MIG overlay  
                 48.0% 
                 &lt;1% 
                 .087″ 
                 164 
               
               
                   
                 Alloy 625 
                   
                   
                   
                   
               
               
                 — 
                 Comparative  
                 27.0% 
                 &lt;1% 
                 .045″ 
                 282 
               
               
                   
                 Laser 625 
                   
                   
                   
                   
               
               
                 1 
                 Alloy 625 
                  2.0% 
                 &lt;1% 
                 .020-.022″ 
                 229 
               
               
                 2 
                 MMC1 
                  2.6% 
                 &lt;1% 
                 .030-.032″ 
                 202 
               
               
                 3 
                 MMC2 
                  1.6% 
                 &lt;1% 
                 .027-.028″ 
                 196 
               
               
                 4 
                 MMC3 
                  1.5% 
                 &lt;1% 
                 .027-.028″ 
                 208 
               
               
                 5 
                 MMC4 
                  2.6% 
                 &lt;1% 
                 .026-.028″ 
                 194 
               
               
                 6 
                 MMC5 
                  2.5% 
                 &lt;1% 
                 .026-.028″ 
                 216 
               
               
                 7 
                 MMC6 
                  2.6% 
                 &lt;1% 
                 .019-.021″ 
                 200 
               
               
                 8 
                 MMC7 
                  2.3% 
                 &lt;1% 
                 .019-.024″ 
                 233 
               
               
                   
               
             
          
         
       
     
         [0000]    
       
         
               
             
               
               
               
               
               
               
               
               
             
           
               
                 TABLE 5 
               
             
             
               
                   
               
               
                 Rounds Sample Results 
               
             
          
           
               
                   
                   
                   
                 Substrate 
                 Laser 
                   
                   
                   
               
               
                 Sample 
                   
                   
                 Hardness 
                 Power 
                 Preheat 
                 Powder 
                 Cladding 
               
               
                 ID 
                 Chemistry 
                 Substrate 
                 (HV) 
                 (W) 
                 (F.) 
                 Feed 
                 Velocity 
               
               
                   
               
               
                 — 
                 MIG overlay Alloy 625 
                 1.5″ 1018 Steel Bar 
                 166 
                 NA 
                 NA 
                 NA 
                 NA 
               
               
                 — 
                 Comparative Laser 625 
                 1.5″ 1018 Steel Bar 
                 232 
                 NA 
                 NA 
                 NA 
                 NA 
               
               
                 1 
                 Alloy 625 
                 1.5″ 1018 Steel Bar 
                 187 
                 2720 
                 265 
                 40.4 g/min 
                 98.4 in/min 
               
               
                 2 
                 MMC1 
                 1.5″ 1018 Steel Bar 
                 176 
                 2640 
                 325-350 
                 39.0 g/min 
                 98.4 in/min 
               
               
                 3 
                 MMC2 
                 1.5″ 1018 Steel Bar 
                 168 
                 2480 
                 490-510 
                 42.1 g/min 
                 98.4 in/min 
               
               
                 4 
                 MMC3 
                 1.5″ 1018 Steel Bar 
                 172 
                 2560 
                 290-305 
                 39.0 g/min 
                 98.4 in/min 
               
               
                 5 
                 MMC4 
                 1.5″ 1018 Steel Bar 
                 167 
                 2640 
                 300 
                 39.3 g/min 
                 98.4 in/min 
               
               
                 6 
                 MMC5 
                 1.5″ 1018 Steel Bar 
                 188 
                 2640 
                 300 
                 39.0 g/min 
                 98.4 in/min 
               
               
                 7 
                 MMC6 
                 1.5″ 1018 Steel Bar 
                 180 
                 2640 
                 450-475 
                 40.9 g/min 
                 98.4 in/min 
               
               
                 8 
                 MMC7 
                 1.5″ 1018 Steel Bar 
                 201 
                 2680 
                 350-400 
                 39.3 g/min 
                 98.4 in/min 
               
               
                   
               
             
          
         
       
     
         [0000]    
       
         
               
             
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
             
           
               
                 TABLE 6 
               
             
             
               
                   
               
               
                 Flat Samples 
               
               
                 Flat Samples on 0.725 inch thick 1018 steel 
               
             
          
           
               
                   
                   
                   
                   
                 Macro 
                 Macro 
                   
                 HAZ 
               
               
                 Sample 
                   
                   
                 Porosity 
                 Hardness 
                 Hardness 
                   
                 Hardness 
               
               
                 ID 
                 Chemistry 
                 Dilution 
                 (ASTM E2109) 
                 (15N) 
                 (HV*) 
                 HAZ Depth 
                 (HV) 
               
               
                   
               
             
          
           
               
                 9 
                 Alloy 625 
                 3.3% 
                 &lt;1% 
                 67.9 
                 225 
                 .026-.027″ 
                 239 
               
               
                 10 
                 MMC1 
                 2.4% 
                 &lt;1% 
                 79.8 
                 384 
                 .017-.019″ 
                 227 
               
               
                 11 
                 MMC2 
                 2.1% 
                 &lt;1% 
                 82.9 
                 446 
                 .022-.023″ 
                 235 
               
               
                 12 
                 MMC3 
                 2.2% 
                 &lt;1% 
                 70.0 
                 247 
                 .022-.026″ 
                 231 
               
               
                 13 
                 MMC4 
                 1.8% 
                 &lt;1% 
                 77.7 
                 346 
                 .021-.024″ 
                 222 
               
               
                 14 
                 MMC6 
                 2.1% 
                 &lt;1% 
                 84.2 
                 475 
                 .026-.028″ 
                 214 
               
               
                 15 
                 MMC7 
                 2.8% 
                 &lt;1% 
                 81.1 
                 415 
                 .031-.032″ 
                 241 
               
               
                 16 
                 MMC8 
                 2.5% 
                 &lt;1% 
                 81.0 
                 402 
                 .031-.032″ 
                 245 
               
               
                 17 
                 MMC9 
                 3.4% 
                 &lt;1% 
                 77.0 
                 327 
                 .023-.025″ 
                 225 
               
               
                   
               
               
                 *Converted from 15N 
               
             
          
         
       
     
         [0000]    
       
         
               
             
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
             
           
               
                 TABLE 7 
               
             
             
               
                   
               
               
                 Flat Sample Results 
               
             
          
           
               
                   
                   
                   
                 Substrate 
                 Laser 
                   
                   
                   
               
               
                 Sample 
                   
                   
                 Hardness 
                 Power 
                 Preheat 
                 Powder 
                 Cladding 
               
               
                 ID 
                 Chemistry 
                 Substrate 
                 (HV) 
                 (W) 
                 (F.) 
                 Feed 
                 Velocity 
               
               
                   
               
             
          
           
               
                 9 
                 100% 625 
                 0.725″ 1018 Steel Plate 
                 208 
                 2720 
                 270 
                 38.8 g/min 
                 98.4 in/min 
               
               
                 10 
                 MMC1 
                 0.725″ 1018 Steel Plate 
                 204 
                 2560 
                 700 
                 38.7 g/min 
                 98.4 in/min 
               
               
                 11 
                 MMC2 
                 0.725″ 1018 Steel Plate 
                 206 
                 2640 
                 420-440 
                 39.1 g/min 
                 98.4 in/min 
               
               
                 12 
                 MMC3 
                 0.725″ 1018 Steel Plate 
                 198 
                 2640 
                 400 
                 37.8 g/min 
                 98.4 in/min 
               
               
                 13 
                 MMC4 
                 0.725″ 1018 Steel Plate 
                 205 
                 2560 
                 440-450 
                 38.6 g/min 
                 98.4 in/min 
               
               
                 14 
                 MMC6 
                 0.725″ 1018 Steel Plate 
                 195 
                 2440 
                 620 
                 38.5 g/min 
                 98.4 in/min 
               
               
                 15 
                 MMC7 
                 0.725″ 1018 Steel Plate 
                 201 
                 2840 
                 350-375 
                 38.6 g/min 
                 98.4 in/min 
               
               
                 16 
                 MMC8 
                 0.725″ 1018 Steel Plate 
                 174 
                 2720 
                 475 
                 38.4 g/min 
                 98.4 in/min 
               
               
                 17 
                 MMC9 
                 0.725″ 1018 Steel Plate 
                 187 
                 2720 
                 475 
                 38.2 g/min 
                 98.4 in/min 
               
               
                   
               
             
          
         
       
     
         [0024]    Dilution rates for the samples of Tables 4 and 6 were found to be well below 5% and ranged from 1.5% to 3.4%. The addition of Mo and WC provided increasing hardness with increasing percentages of each. However, an interaction between Mo and WC was noted, where the combination of Mo and WC provided a synergistic effect of greater hardness at lower levels of loading than the hardness provided when either particle was used alone and in greater amounts. 
         [0025]    As shown in Table 8, the disclosed process and materials yield samples with significantly better corrosion resistance when compared to competitive fusion technologies. While conventional materials failed rapidly in a ISO 14993 cyclic wet/dry saltwater corrosion test (modified to include additional heat and UV features), the tabulated materials, based on the disclosed technology, have shown no corrosion through the time periods reported. The addition of 10 wt % Mo particles yielded a significant improvement in corrosion resistance as measured by ASTM G48 temperatures. The addition of 20 wt % Mo yielded a sample that was beyond ASTM G48 test capabilities, representing a significant pitting corrosion resistance over base Alloy 625. Based on testing, the addition of 7.5% Mo provides corrosion protection beyond the capabilities of ASTM G48, which indicates the material, when applied as disclosed, will provide unparalleled, perhaps practically infinite, corrosion resistance in a marine environment. 
         [0000]    
       
         
               
             
               
               
               
               
             
               
               
               
               
             
           
               
                 TABLE 8 
               
             
             
               
                   
               
               
                 Sample Corrosion Results 
               
             
          
           
               
                   
                 ISO 14993  
                 ASTM G48  
                 ASTM G48  
               
               
                   
                 modified 
                 Critical 
                 Critical 
               
               
                   
                 Saltwater  
                 Pitting  
                 Crevice  
               
               
                   
                 Corrosion * 
                 Temperature 
                 Temperature 
               
               
                 Chemistry 
                 (hrs) 
                 (° C.) 
                 (° C.) 
               
               
                   
               
             
          
           
               
                 MIG overlay Alloy 625 
                 500 
                 NA 
                 NA 
               
               
                 Comparative Laser 625 
                 980 
                 NA 
                 NA 
               
               
                 Alloy 625 
                 &gt;6528 
                 65 
                 35 
               
               
                 MMC 1 
                 &gt;5064 
                 65 
                 35 
               
               
                 MMC 2 
                 &gt;5064 
                 NA 
                 NA 
               
               
                 MMC 3 
                 &gt;5064 
                 80 
                 65 
               
               
                 MMC 4 
                 &gt;5064 
                 &gt;85 
                 &gt;85 
               
               
                 MMC 5 
                 NA 
                 NA 
                 NA 
               
               
                 MMC 6 
                 &gt;3528 
                 &gt;85 
                 &gt;85 
               
               
                 MMC 7 
                 &gt;3528 
                 75 
                 60 
               
               
                 MMC 8 
                 NA 
                 &gt;85 
                 &gt;85 
               
               
                 MMC 9 
                 NA 
                 75 
                 60 
               
               
                   
               
               
                 * Test Completed. No corrosion present at hrs reported. 
               
             
          
         
       
     
         [0026]    Wear testing was conducted in conformance with the ASTM G 133 (A) standard, both under dry wear and lubricated wear conditions. Dry wear test conditions were: 
       Stroke=10 mm 
     Normal Force=1000 gf 
     Speed=100 rpm 
       [0027]    Duration=20,000 cycles
 
Rider Material=aluminum oxide
 
Rider Radius=0.125 inch
 
       Temperature=Room 
       [0028]    For lubricated wear conditions, a standard grade Mobil DTE® 24 light hydraulic oil ISO 32 was applied at the contact area using approximately 1 mL for each test. Lubricated wear test conditions were: 
       Stroke=10 mm 
     Normal Force=25 N 
     Speed=100 rpm 
       [0029]    Duration=20,000 cycles
 
Rider Material=aluminum oxide
 
Rider Radius=0.125 inch
 
       Temperature=Room 
       [0030]    Referring to Table 9, the addition of Mo increases hardness and dry wear resistance continued to improve as Mo loading increased. The addition of WC provided additional improvements. However, the addition of 5 wt % Mo and 5 wt % WC to Alloy 625 provided performance comparable to higher loadings of either particle alone. The improved wear resistance and increased hardness of the dual particle system is combined with the added benefit of improved impact resistance, when compared to similar wear particle mixtures only. In comparison to the base Alloy 625 as tabulated in Table 10, it provided a 69% reduction in abrasive wear, an 80% reduction in sliding rider wear and an 11% reduction in lubricated sliding wear. The dry coefficient of friction (COF) also improved, demonstrating a reduction of 25%. Remarkably, the 84% increase in hardness did not reduce the impact toughness as the similar wear particle only formulations did, as shown by the bold values in Table 10. 
         [0031]    Maximizing impact toughness against wear resistance is critical for corrosion resistance in a rugged marine environment as any small crack will ultimately lead to rapid corrosion failure. The preferred embodiment of wear, impact toughness, corrosion resistance, hardness, and COF, was found to be a mixture of 7.5% Mo and 7.5% WC. This mixture demonstrated a 69% reduction in abrasive wear, an 87% reduction in dry sliding wear, and a 47% reduction in lubricated sliding wear. The dry COF was reduced by 27% and the lubricated COF reduced by 5%. While the hardness improved 79%, the impact toughness was only reduced by 39% to an application acceptable  100  in-lbs impact toughness. 
         [0032]    Wear testing was performed in conformance with the ASTM G174 (B) standard. The test conditions were: 
         [0000]    Normal force mass=100 g
 
Spindle speed=100 rpm
 
Test duration=100 belt passes
 
Abrasive media=3 micrometer (μm) aluminum oxide microfinishing tape
 
Test specimen width=0.3˜2 inches
 
Loop speed=0.0266 m/s
 
         [0033]    Scar width was optically measured and converted to a wear volume by the geometric calculations of ASTM G77. Each scar was measured three times: edge, center, edge. 
         [0034]    Erosion testing was performed in conformance with the ASTM G 76 standard. The impingement angle was 60 degrees and the distance between the nozzle and sample was 10 mm. The blasting pressure was 6 psi, using a 50 μm aluminum oxide test abrasive at a flow rate between 0.06 and 0.1 g/s. Each test was terminated when 20 g of abrasive hit the test specimen. 
         [0000]    
       
         
               
             
               
               
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
               
             
           
               
                 TABLE 9 
               
             
             
               
                   
               
               
                 Sample Wear Results 
               
             
          
           
               
                 Test Method 
                 Alloy 625 
                 MMC1 
                 MMC2 
                 MMC3 
                 MMC4 
                 MMC6 
                 MMC7 
                 MMC8 
                 MMC9 
               
               
                   
               
             
          
           
               
                 ASTM G133 Dry Wear (in 3  × 10 −8 ) 
                 9947 
                 2216 
                 1600 
                 4339 
                 2342 
                 1608 
                 1975 
                 1286 
                 1588 
               
               
                 ASTM G133 Lubricated Wear (in 3  × 10 −8 ) 
                 144 
                 67 
                 114 
                 147 
                 100 
                 20 
                 127 
                 76 
                 98 
               
               
                 ASTM G174 Abrasion (mm 3  × 10 −3 )/m 
                 1.47 
                 0.32 
                 0.14 
                 1.73 
                 0.9 
                 0.39 
                 0.46 
                 0.46 
                 0.68 
               
               
                 ASTM G76 Erosion Mass Loss (mg) 
                 5.3 
                 4.9 
                 4.7 
                 5.1 
                 4.6 
                 5.5 
                 4.6 
                 5.8 
                 5.2 
               
               
                 ASTM G133 COF Dry 
                 0.59 
                 0.48 
                 0.49 
                 0.52 
                 0.48 
                 0.54 
                 0.44 
                 0.43 
                 0.47 
               
               
                 ASTM G133 COF Lubed 
                 0.20 
                 0.20 
                 0.20 
                 0.18 
                 0.19 
                 0.21 
                 0.20 
                 0.19 
                 0.19 
               
               
                 Impact Strength (in-lbs) 
                 &gt;160 
                 44 
                 20 
                 &gt;160 
                 &gt;160 
                 28 
                 &gt;160 
                 100 
                 &gt;160 
               
               
                 Hardness (HV*) 
                 225 
                 384 
                 446 
                 247 
                 346 
                 475 
                 415 
                 402 
                 327 
               
               
                   
               
               
                 *Converted from 15N 
               
             
          
         
       
     
         [0000]    
       
         
               
             
               
               
               
               
               
               
               
               
               
             
           
               
                 TABLE 10 
               
             
             
               
                   
               
               
                 MMC Sample Results Relative to base Alloy 625 
               
             
          
           
               
                 Alloy 625 Vs. 
                 MMC1 
                 MMC2 
                 MMC3 
                 MMC4 
                 MMC6 
                 MMC7 
                 MMC8 
                 MMC9 
               
               
                   
               
               
                 % Reduced Dry Wear 
                   78 % 
                   84 % 
                 56% 
                 76% 
                   84 % 
                   80 % 
                   87 % 
                 84% 
               
               
                 % Reduced Lubricated Wear 
                 53% 
                 20% 
                 −3% 
                 30% 
                   86 % 
                   11 % 
                   47 % 
                 31% 
               
               
                 % Reduced Abrasion 
                 78% 
                 90% 
                 −18%  
                 39% 
                 73% 
                   69 % 
                   69 % 
                 54% 
               
               
                 % Reduced Erosion 
                  8% 
                 11% 
                  4% 
                 13% 
                 −4% 
                 13% 
                 −9% 
                  2% 
               
               
                 % Reduced COF - Dry 
                 19% 
                 17% 
                 12% 
                 19% 
                  8% 
                   25 % 
                   27 % 
                 20% 
               
               
                 % Reduced COF - Lubricated 
                  0% 
                  0% 
                 10% 
                  5% 
                 −5% 
                  0% 
                   5 % 
                  5% 
               
               
                 % Increased LTC 
                  0% 
                  0% 
                  0% 
                  0% 
                  0% 
                  0% 
                  0% 
                  0% 
               
               
                 % Increased CRT 
                  0% 
                  0% 
                 23% 
                 31% 
                 31% 
                 15% 
                 31% 
                 15% 
               
               
                 % Increased CCT 
                  0% 
                  0% 
                 86% 
                 143%  
                 143%  
                 71% 
                 143%  
                 71% 
               
               
                 % Increased Impact 
                 − 73 %  
                 − 88 %  
                  0% 
                  0% 
                 − 83 %  
                   0 % 
                   −38 %  
                  0% 
               
               
                 % Increased HV 
                   71 % 
                   98 % 
                 10% 
                 54% 
                   111 %  
                   84 % 
                   79 % 
                 45% 
               
               
                   
               
             
          
         
       
     
         [0035]    Table 11 outlines the maximum particle concentrations allowed in an Alloy 625 matrix while maintaining a uniform, homogenous, metallurgically bonded coating free from macro cracks, micro cracks, or other dislocations and defects that would adversely affect corrosion resistance in a marine environment. 
         [0036]    The process parameters and MMC mixtures are likely to provide similar utility with any nickel alloy matrix, cobalt alloy matrix, and with nearly any combination of available wear particles in either nano or micro powder sizes when additional fusing is provided to powder carriers to promote even dispersion. 
         [0000]    
       
         
               
             
               
               
               
             
           
               
                 TABLE 11 
               
             
             
               
                   
               
               
                 Maximum Particle Concentrations 
               
             
          
           
               
                   
                   
                 Maximum Concentration  
               
               
                   
                 Particle 
                 in Alloy 625 matrix 
               
               
                   
                   
               
               
                   
                 WC 
                 20% 
               
               
                   
                 Mo 
                 25% 
               
               
                   
                 WC + Mo 
                 20% 
               
               
                   
                   
               
             
          
         
       
     
         [0037]    The disclosed MMC cladding compositions allow for single-pass processing of materials because of superior properties of a thin cladding, thereby providing advantaged economics when compared to multiple pass technologies required to create thick coatings of less capable materials.