Classifications

• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C4/00—Coating by spraying the coating material in the molten state, e.g. by flame, plasma or electric discharge
  • C23C4/04—Coating by spraying the coating material in the molten state, e.g. by flame, plasma or electric discharge characterised by the coating material
  • C23C4/06—Metallic material
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C45/00—Amorphous alloys
  • C22C45/02—Amorphous alloys with iron as the major constituent
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C33/00—Making ferrous alloys
  • C22C33/003—Making ferrous alloys making amorphous alloys
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C24/00—Coating starting from inorganic powder
  • C23C24/02—Coating starting from inorganic powder by application of pressure only
  • C23C24/04—Impact or kinetic deposition of particles
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C4/00—Coating by spraying the coating material in the molten state, e.g. by flame, plasma or electric discharge
  • C23C4/04—Coating by spraying the coating material in the molten state, e.g. by flame, plasma or electric discharge characterised by the coating material
  • C23C4/06—Metallic material
  • C23C4/067—Metallic material containing free particles of non-metal elements, e.g. carbon, silicon, boron, phosphorus or arsenic
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B82—NANOTECHNOLOGY
  • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
  • B82Y30/00—Nanotechnology for materials or surface science, e.g. nanocomposites

Definitions

• the invention pertains to metallic coatings and methods of forming metallic coatings.
• BACKGROUND OF THE INVENTION Steel is a metallic alloy which can have exceptional strength characteristics
• steel which is accordingly commonly utilized in structures where strength is required or advantageous.
• Steel can be utilized, for example, in the skeletal supports of building structures, tools, engine components, and protective shielding of modern armaments.
• the composition of steel varies depending on the application of the alloy.
• steel is defined as any material that is used in construction.
• iron-based alloy in which no other single element (besides iron) is present in excess of 30 weight percent, and for which the iron content amounts to at least 55 weight percent, and carbon is limited to a maximum of 2 weight percent.
• steel alloys can be any other single element (besides iron) in excess of 30 weight percent, and for which the iron content amounts to at least 55 weight percent, and carbon is limited to a maximum of 2 weight percent.
• steel alloys can be any other single element (besides iron) is present in excess of 30 weight percent, and for which the iron content amounts to at least 55 weight percent, and carbon is limited to a maximum of 2 weight percent.
• Steel alloys can also incorporate carbon, silicon, phosphorus and/or sulfur.
• carbon, silicon, phosphorus and/or sulfur can also incorporate carbon, silicon, phosphorus and/or sulfur.
• steel typically contains small amounts of
• Steel is typically formed by cooling a molten alloy. The rate of cooling will determine
• microcrystalline internal grain structures are formed, or, in
• molten alloy generally determines whether the alloy solidifies to form microcrystalline grain
• the amorphous character of metallic glass can provide desired properties.
• some glasses can have exceptionally high strength and hardness.
• some glasses can have exceptionally high strength and hardness.
• microcrystalline grain structures are preferred.
• grains i.e., grains having a size on the order of 10 "6 meters
• the invention encompasses a method of forming a metallic coating.
• metallic glass coating is formed over a metallic substrate. After formation of the coating, at
• the metallic glass can be converted into a crystalline material having a
• the invention encompasses metallic coatings comprising metallic
• the invention encompasses metallic coatings comprising
• Fig. 1 is a block-diagram flowchart view of a method encompassed by the present
• FIG. 2 is a diagrammatic perspective view of a barrel being treated according to a
• Fig. 3 is a fragmentary, diagrammatic, cross-sectional view of a metallic material
• Fig. 4 is a view of the Fig. 3 fragment shown at a processing step subsequent to that of
• Fig. 5 is a view of the Fig. 3 fragment shown at a processing step subsequent to that of
• Fig. 6 is a view of the Fig. 3 fragment shown at a processing step subsequent to that of
• Fig. 5 is an optical micrograph of a metallic glass ribbon formed in accordance with
• Fig. 8 is a scanning electron microscope micrograph of a cross section of a gas atomized powder particle formed in accordance with the present invention, and formed from a composition comprising Fe 63 Cr 8 Mo 2 B 17 C 5 Si 1 Al 4 .
• Fig. 9 is a graph illustrating the results of a differential thermal analysis scan of a ribbon produced in accordance with the present invention. The ribbon was produced from a composition comprising Fe 63 Cr 8 Mo 2 B 17 C 5 Si 1 Al 4 . An exothermic glass to crystallization transition occurs at 550°C, and an endothermic solid to liquid melting transition occurs at
• Fig. 10 is a TEM micrograph of a steel alloy produced in accordance with the
• Fig. 11 illustrates Vickers hardness for different metallic alloys. Specifically, the figure compares DAR1 (Fe 63 Cr 8 Mo 2 B 17 C 5 Si 1 Al 4 ) with DAR20
• Fig. 12 shows examples of Nickers hardness tests using a diamond pyramid indenter. Specifically, a top portion of the figure shows the test relative to gas atomized powder
• Fig. 13 is an optical micrograph of a steel composition which has been plasma sprayed onto a stainless steel substrate.
• the plasma-sprayed steel composition comprises Fe 63 Cr 8 Mo 2 B 17 C 5 Si 1 Al 4 .
• the top portion of Fig. 9(a) is a cross-sectional view of the sprayed
• the lower portion (b) shows a top surface of the coated material.
• Fig. 14 illustrates an x-ray diffraction scan of a plasma-sprayed deposit having a free
• the plasma-sprayed composition was Fe 63 Cr 8 Mo 2 B 17 C 5 Si 1 Al 4 .
• Fig. 15 shows an x-ray diffraction scan of the plasma-sprayed composition of Fig. 14,
• Fig. 16 illustrates a graph showing coefficient of friction versus the number of turns
• the tested coating was Fe 63 Cr 8 Mo 2 B 17 C 5 Si 1 Al 4 . It
• Fig. 17 is a profile curve of a "wear-groove" on an as-sprayed steel substrate after
• Fig. 18 is an optical micrograph of an as-spun ribbon of (Fe 08 CR 02 ) 81 B 17 W 2 .
• Fig. 19 illustrates data obtained from differential thermal analysis of
• Fig. 20 shows peak crystallization temperatures measured by differential thermal
• Fig. 20 shows the alloy Fe 63 Cr 8 Mo 2 B 17 C 5 Si 1 Al 4
• Fig. 21 illustrates crystallization enthalpies measured by differential scanning
• Fig. 22 illustrates a graph of transformation rates of glass to crystallization
• Fig. 23 illustrates peak melting temperatures measured by differential thermal analysis
• Fig. 23 shows the
• a molten alloy is formed.
• Such alloy comprises a steel composition.
• An exemplary alloy comprises at least 50% Fe and at least one element selected from the group consisting of
• the alloy will be a magnetic alloy with ultrafine crystal grains having a composition represented by the formula: Fe(100-x-y)M(x)B(y) (atomic percent) wherein M represents at least one element selected from Ti, Zr, Hf, V, Nb, Mo, Ta,
• alloy structure is preferably occupied by crystal grains having an average size of 1000A or less, with the crystal grains being based on a bcc structure.
• the alloy can further contain X (Si, Ge, P, Ga, etc.) and/or T (Au, Co, Ni, etc.). Alloys of the present invention preferably comprise fewer than 11 elements, and can
• alloys can comprise
• alloys of the present invention have from four to six elements in their
• compositions are iron; chromium, which can be included for
• Exemplary alloys which can be utilized in methodology of the present invention are: (F e o. 8 r 0 . 2 ) 83 B ⁇ , (Fe 075 Cr 025 ) 83 B 17 , (Fe 08 Mo 02 ) 83 B 17 , (Fe 06 Co 02 Cr 02 ) 83 B 17 , F e o. 8 Cro . i 5 M£> O 05 ) 83 B 17 , (Fe 08 Cr 02 ) 79 B 17 C 4 , (Fe 08 Cr 02 ) 79 B 17 S ⁇ 4 , (Fe 08 Cr 02 ) 79 B 17 Al 4 ,
• the alloy of step (A) can be formed by, for example, melting a composition under an
• step (B) of Fig. 1 the alloy is cooled to form a metallic glass. Such cooling
• the cooling can be accomplished by a number of
• the powder can be consolidated by, for
• step (B) is accomplished by centrifugal atomization.
• the melt stream leaves a centrifugal cup and is hit by high pressure helium gas to facilitate fast cooling (greater than 10 s K/s.)
• the helium gas can be collected, purified and reused.
• the speed of the rotating centrifugal cup is preferably about 40,000 RPM, and such speed can be adjusted to produce a fine powder with about a 25 micrometer mean size.
• step (C) of Fig. 1 the metallic glass of step (B) is devitrified to form a crystalline steel material having a nanocrystalline grain size.
• Such devitrification can be accomplished by heating the metallic glass to a temperature of from about 600°C to less than the melting temperature of the alloy. Such heating enables a solid state phase change wherein the amorphous phase of the metallic glass is converted to one or more crystalline solid phases.
• the solid state devitrification of the amorphous precursor from step (B) enables uniform nucleation to occur throughout the metallic glass to form nanocrystalline grains
• the metal matrix microstructure formed via the devitrification can comprise a steel matrix (iron with dissolved interstitials), with an intimate mixture of ceramic precipitates (transition metal carbides, borides, suicides, etc.).
• the nanocrystalline scale metal matrix composite grain structure can enable a combination of mechanical properties which are improved compared to the properties which would exist with larger grain sizes or
• Post treatment of the devitrified metallic material from step (C) can include a surface treatment utilized to transform only the surface of the material to a metallic glass.
• Exemplary surface treatment techniques are high and low pressure plasma spraying, high velocity oxyfuel spraying, and spray forming.
• the plasma spraying can be accomplished with a plasma spray system.
• the post treatment can offer improvements in, for example, corrosion resistance and lowering the coefficient of friction of a steel material.
• a metallic glass coating can also offer advantages over existing coatings such as, for example, chrome, nickel and tin plating in that the metallic glass coating can be cheaper and can give a better metallurgical bond between the surface and the base metal.
• Fig. 2 illustrates a metallic barrel 50 being sprayed with a molten metal material 52.
• Molten metal material 52 is sprayed from a spraying device 54, and can comprise, for example, one or more of the above-described exemplary alloys of the present invention.
• the molten metal can be formed by melting an alloy composition under an argon atmosphere and subsequently centrifugally atomizing the alloy composition. As the melt stream leaves a centrifugal cup, it can be hit by a high pressure helium gas to form a fine
• drum 50 comprises a steel drum, such as, for example, a 55 gallon steel drum. It is noted that the powder may or may not be fully melted upon exposure to the plasma, and will be deposited into and onto the surface of barrel 50 as a
• Drum 50 cools rapidly to form a metallic glass.
• Drum 50 can be subsequently heat-treated at a
• the metallic structure formed over and within barrel 50 from material 52 can have
• Drum 50 be utilized, for example, for storing
• FIG. 3-6 illustrate another embodiment application of the present invention.
• a metallic substrate 100 is provided.
• Such substrate can comprise, for example,
• a metallic melt 102 is sprayed onto substrate 100 utilizing a
• Melt 102 can comprise, for example, a molten alloy comprising one or more of
• material 102 can alternatively comprise a
• Material 102 deposits on substrate 100 to form a layer 106. Material 102 also heats an
• heat-treated portion 108 can comprise a devitrified material. Specifically, if layer 106 is formed at a temperature which heats a surface of layer 100 to greater than 600°C, such heating can devitrify a portion of material 100 exposed to such temperatures. In particular applications, temperatures greater than 600°C can permeate entirely through substrate 100 to heat-treat an entire thickness of material 100. Spray nozzle 104 is preferably resistant to the temperature and composition of material 102. Referring to Fig. 5, substrate 100 is illustrated after layer 106 has been formed across an entire surface of substrate 100. Heat-treated portion 108 also extends across an entire
• layer 106 can be formed as a metallic
• each of the layers 106 and 120 can be deposited as metallic glass and can remain in the metallic glass form during deposition of
• Outermost layer 124 may or may not be heat-treated, and can comprise a metallic glass. Accordingly, the method of the present invention has enabled an exterior coating to be
• Figs. 3-6 can have application for a number of uses, including military uses. Specifically, armor can be formed out of a material 100. If the armor becomes punctured or cracked, the methodology of Figs. 3-6 can be utilized to repair the armor and effectively build a metallic shell over the weakened areas of the armor. Spraying device 104 can be adapted to be utilizable in battlefield situations. In addition to the utilizations described above for materials of the present invention,
• the materials can also be utilized as powders for surface finishing (i.e., mechanical blasting) and surface treatments such as, for example, shot peening.
• the invention can be considered a method for forming a new class of steel called
• DNC steel devitrified nanocomposite steel
• DNC steel being defined as having a primarily nanoscale (less than 100 nanometer) microstructure grain size developed by processing the steel through a solid-solid transformation (specifically, glass devitrification). Alloys are developed having low cooling rates (less than 10 6 K/s) for metallic glass formation, and accordingly the alloy compositions form metallic glasses when rapidly solidified by a chill
• the glass is utilized as a precursor stage, and the alloy subsequently processed through a glass devitrification transformation upon heating above a crystallization temperature of the alloy. Due to uniform nucleation in the glass coupled with a high nucleation frequency, there is little time for grain growth processes, and nanoscale
• nanocomposite microstructures result.
• the nanocomposite microstructures can lead to materials having significant increases in hardness and strength over conventional steel alloys.
• Initial studies described herein show that DNC steel formed in accordance with methodology of the present invention has exceptional hardness and wear resistance, and can be used potentially for any application which involves sliding, rolling, or rotation. Additionally, initial studies have shown that the unlubricated DNC steel surface has exceptionally low coefficients of friction (in the range of lubricated steels) which can be a beneficial property in reducing wear resistance, frictional energy losses, and heating between
• DNC steel in unlubricated applications, and can also be useful as a fail-safe mechanism allowing additional time before failure in some applications, such as gasoline or diesel engines, where lubrication is unexpectedly lost.
• the high wear resistance of DNC steel, coupled with low friction, can allow extension of the lifetime of parts formed from DNC steel relative to parts formed from conventional steel alloys. Such can enable large savings in both operating energy and cost associated with part replacement, repair, maintenance and down-time.
• Exemplary applications for utilization of DNC steels of the present invention include bearings, gun barrel surfaces, bearing journals, hydraulic cylinder connecting rods, crankshafts, pistons, cylinder liners, gears, camshafts, universal joints, valves, gun breach boxes, missile launcher tubes, and tank gear boxes.
• DNC steel utilizes a different approach, and specifically utilizes processing through a solid/solid state glass devitrification transformation.
• DNC steel alloys have been developed which have exceptionally low cooling rates (10 3 K/s to 10 5 K/s) for metallic glass formation. This can allow the production of metallic glass structures during rapid solidification via chill surface or atomization methods. Examples of DNC steel melt-spun ribbon and gas atomized powder are shown in Figs. 7 and 8, respectively. Metallic glass structures are produced by both of these rapid solidification processing methods.
• the glass precursor can be devitrified into a nanoscale composite microstructure by heating above the crystallization temperature.
• a differential thermal analysis scan for as-spun DNC steel is shown in Fig. 9.
• the glass crystallization temperature typically varies from 750K to 900K with enthalpies of transformation from -75 J/g to -200 J/g, and melting temperatures from 1,375K to 1,500K for alloys encompassed by the present invention (as described in the charts of Figs. 20-23).
• nanoscale nanocomposite microstructures are formed.
• the individual phase sizes can vary from 1 to 75 nanometers, which is finer than conventional steels produced by conventional casting or even when rapidly solidified.
• a high percentage of the atoms of the material (about 30%) can be associated with grain boundaries, and an extremely high density of two-dimensional defect interfaces (such as phase in grain boundaries) reside in the microstructure.
• the microstructure of a devitrified ribbon showing the nanoscale nanocomposite microstructure is shown in Fig. 10. The nanostructure results in the development of extreme strength and hardness, which are significantly higher than found
• the yield strengths for the DNC steel can be estimated to be 725 ksi, which is significantly higher than conventional (150 ksi) or ultra high strength (220 ksi) steels. If the plasticity is fully developed, the yield strength can be estimated to be 1/3 of the hardness. This gives the DNC steel a specific strength of 0.65 x 10 6 M which makes this material an alternate for Al in lightweight applications. Little hardness difference was found between the large and small heated powders indicating that similar microstructures were obtained independent of powder size. It is noted that the
• a preferred material of the present invention (specifically DAR20) is compared with DAR1 in Fig. 11. Specifically, Nickers microhardness measurements with a 100 gram load were performed on 75 micrometer to 100 micrometer powder size fractions for as-atomized alloys, and also as a function of heat treatment temperature. The tested alloys exhibited extreme hardness from 10.1 GPa to 16.0 GPa Nickers hardness. Examples of diamond pyramid indentations on a melt-spun ribbon and gas-atomized powder particle are shown in Fig. 12. While the Rockwell C is the most common hardness measurement for steels, it cannot be used in the present case due to the extreme hardness of the alloys of the present invention (which are off of the Rockwell C scale). Note that a Nickers Hardness number of
• D ⁇ C steels contain multiple combinations of elements which result in relatively low melting points (typically around 1,150°C) and low melt viscosities. This can make the D ⁇ C steels easy to process from the liquid state, and ideal feedstock materials for forming coatings by thermal deposition methods.
• Initial low plasma spraying tests have been performed utilizing the atomized 20 to 50 micrometer Fe 63 Cr 8 Mo 2 B 17 C 5 Si,Al 4 steel powder as feed stock.
• Several uniform D ⁇ C steel coatings of 0.1 inch in thickness were deposited onto 4"x4" 301
• Metallographic examinations of the coatings indicate that the percent porosity of the initial coatings was at least 3%.
• X-ray diffraction scans were performed both on the substrate side and free surface side of the coatings, and show that an amorphous structure was obtained through the cross-sectioning of the coatings (specifically, Fig. 14 shows an x-ray structure of a free surface side of the coating, and Fig. 15 shows an x-ray structure of the substrate side of
• DNC steel coatings represent a class of materials called bulk glasses.
• Bulk glasses are normally very difficult to produce, but readily form in the DNC alloys by thermal processing methods.
• the as-sprayed DNC metallic glass coatings can be devitrified into a nanoscale structure by heating above the crystallization temperature.
• the glass state itself may be useful as a coating.
• Metallic glasses are essentially super-cooled liquids, and have structures which are very homogeneous. Typically there are few defects, and there can be a complete absence of grains and phase boundaries. Hardness testing was performed on both the as-sprayed (amorphous) and heat- treated (800°C for one hour) nanocrystalline coatings. The Nickers hardness of these coatings
• the coefficients of sliding friction were obtained for specimens sliding over a normalized steel (0.13% C, 3.42% Ni): aluminum (0.6), cartridge brass (0.5), copper (0.8), cast iron (0.4), and normalized steel (on itself 0.8).
• the coefficients of static friction for unlubricated surfaces generally vary from 0.8 to 1.0, while
• lubricated steels have much lower values (typically from 0.1 to 0.25).
• the unlubricated DNC steels have coefficients of static friction in the range of lubricated steel surfaces. Accordingly, utilization of DNC steel coatings in place of conventional steel may allow the elimination of lubrication in some applications.
• the coefficient of sliding friction of the steel substrate could not be measured due to Si 3 N 4 deposition from the pin.
• the profile of the wear surface of the steel showed that the steel experienced no wear during the test (Fig. 17). Instead of the expected wear groove, a raised hill of deposited Si 3 N 4 was found on the steel surface. Examination of the silicon nitride ball showed that it experienced a large ball scar as a result of wear. This was surprising due to the hardness of the ball material (15.4 GPa), which is used specifically for these type of tests due to its
• Si 3 N 4 is currently the hardest pin material available to perform this ASTM test.
• the Fe 63 Cr 8 Mo 2 B ⁇ 7 C 5 Si 1 Al 4 steel utilized in generating the data described above is an exemplary DNC steel.
• it suffers from a disadvantage of having numerous elements included therein, which can make it difficult to produce uniform batches of the material. Accordingly, improved DNC alloys have been developed. Such improved alloys are listed in Table 1 as DAR2 through DAR19. The alloys have been designed to form metallic glasses at low cooling rates, and are further designed to reduce the number of elements utilized in the
• materials of the present invention having less than 11 elements, and more preferably less than seven elements, can form glass compositions. It is not a trivial task to form materials having such limited number of elements, which are also capable of forming metallic glasses. However, such has been accomplished in the present invention.
• the present invention also has developed improved
• DNC steel alloys are believed to be useful for numerous services, including military applications, due to their strength and wear resistance.
• the alloys can also be resistant to electrochemical attack (i.e., corrosion). In general, as the scale of a microstructure decreases, the electrochemical resistance of a particular material is expected to increase.
• nanocrystalline scale DNC microstructures are expected to have good corrosion resistance. Further, metallic glass DNC structures can have improved corrosion resistance due to high homogeneity (short range order on a 2 nanometer length scale) and the absence of two- dimensional defects (such as grain or phase boundaries). Specifically, a uniform single-phase structure can make it difficult for sites to initiate for anodic attack and electron transfer since
• a high level of chromium can improve resistance to
• alloys can contain a relatively high percentage of transition metals (from 90% to 97%) which
• materials is that the materials of the present invention can comprise no carbon.
• untempered martensite and transition metal carbides are typically hard, and also brittle).
• Group VI transition metals (Cr, Mo, and W) can be particularly potent additions to
• Chromium consistent with data on conventional steel alloys, is expected to also have
• Molybdenum and tungsten can be exceptionally
• Tungsten can also be potent at
• DNC steel Because of its hardness and high strength (greater than 725 ksi), DNC steel can be
• DNC steel can be easy to process from the liquid state.
• powder of DNC steel can be fed through a conventional plasma gun and sprayed as a coating onto metal substrates with good adhesion and with absence of cracking.
• Other methods for forming a coating of DNC steel include axial feed plasma spray, conventional plasma spray, high velocity oxy-fuel spray, and a detonation gun.
• DNC steel is sprayed onto metallic substrates it can readily form a metallic glass structure. If consecutive layers are continuously sprayed onto a bulk substrate (thickness greater than 0.1 inches) metallic glasses can be formed. This may be the most inexpensive and easiest way to form bulk metallic glass coatings or even bulk glass monolithic parts.
• DNC steels can be rapidly solidified into an amorphous glass precursor and then the rapidly solidified powders can be consolidated into a useful form. Accordingly, the cost of technology of the present invention can involve three items: the alloy cost, the powder production cost, and the consolidation cost. All three items can be estimated. To produce rapidly solidified powder, centrifugal atomization may be the best method, and even at relatively low production rates. If it is feasible to produce DNC steel powder by water
• DNC steel coating may also be a direct competing technology to replace tungsten carbide cemented carbide coatings, since the DNC steel exhibits higher hardness and greater tensile ductility.
• alloys of the present invention can also be coated on non-metallic substrates, such as, for example, ceramics, to provide a hard and/or lubricating surface over the non-metallic substrates.

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• Chemical & Material Sciences (AREA)
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• Physics & Mathematics (AREA)
• Coating By Spraying Or Casting (AREA)
• Other Surface Treatments For Metallic Materials (AREA)
• Manufacture Of Metal Powder And Suspensions Thereof (AREA)
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