METHOD FOR ATOMIZING AND DEPOSITING CERAMIC NANOPARTICLE INK ONTO A SUBSTRATE SURFACE

Description

RELATED APPLICATIONS

This document claims the benefit of and priority to U.S. Provisional Patent Application Ser. No. 63/730,171 filed on Dec. 10, 2024, and U.S. Provisional Patent Application Ser. No. 63/787,604, filed on Apr. 11, 2025, the full disclosures of which are incorporated herein by reference.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

This invention was made, in part, with government support under Grant/Contract No. PADR 3210001950 awarded by the Army Research Laboratory. The government has certain rights in the invention.

TECHNICAL FIELD

This document relates generally to a new and improved method for depositing a ceramic nanoparticle ink-based coating onto the surface of a substrate using an aerosol formulation that allows for ultra-high temperature ceramic (UHTC) coatings to be applied via aerosol in the absence of the extreme heat and pressure associated with prior art coating processes.

BACKGROUND

Current approaches used to deposit or apply UHTC coatings to a substrate surface include plasma spark sintering, thermal spraying, and bulk sintering. Disadvantageously, all of these prior art approaches impose high heat loads and lack the ability to micro-structure coatings. As a result, these approaches are unable to reduce coating stress, and coating adhesion and shear resistance suffer.

This document relates to a new and improved method for depositing a ceramic nanoparticle ink onto a surface of a substrate utilizing a UHTC aerosol formulation that may be simply applied by airbrushing, conventional painting, or aerosol jet printing using, for example, ultrasonic and pneumatic atomizers, without any application of heat or pressure. Such a process is uniquely suited for laser coating/cladding and ceramic additive manufacturing with broad application potential across both many Department of Defense and civilian applications including, for example, turbine blades, rocket/space-reentry heat shielding or thermal protection systems, exhaust systems, and the like.

SUMMARY

Each of the following terms written in singular grammatical form: “a”, “an”, and “the”, as used herein, means “at least one”, or “one or more”. Use of the phrase “One or more” herein does not alter this intended meaning of “a”, “an”, or “the”. Accordingly, the terms “a”, “an”, and “the”, as used herein, may also refer to, and encompass, a plurality of the stated entity or object, unless otherwise specifically defined or stated herein, or, unless the context clearly dictates otherwise. For example, the phrase: “an ink”, as used herein, may also refer to, and encompass, a plurality of inks.

Each of the following terms: “includes”, “including”, “has”, “having”, “comprises”, and “comprising”, and, their linguistic/grammatical variants, derivatives, or/and conjugates, as used herein, means “including, but not limited to”, and is to be taken as specifying the stated component(s), feature(s), characteristic(s), parameter(s), integer(s), or step(s), and does not preclude addition of one or more additional component(s), feature(s), characteristic(s), parameter(s), integer(s), step(s), or groups thereof.

The phrase “consisting of”, as used herein, is closed-ended and excludes any element, step, or ingredient not specifically mentioned. The phrase “consisting essentially of”, as used herein, is a semi-closed term indicating that an item is limited to the components specified and those that do not materially affect the basic and novel characteristic(s) of what is specified.

Terms of approximation, such as the terms about, substantially, approximately, etc., as used herein, refers to ±10% of the stated numerical value.

In accordance with the purposes and benefits set forth herein, a new and improved method is provided for depositing a ceramic nanoparticle ink onto a surface of a substrate. The method comprises, consists of or consists essentially of:

• • (a) atomizing the ceramic nanoparticle ink;
  • (b) depositing the atomized ceramic nanoparticle ink onto the surface of the substrate at temperatures below 50° C.; and
  • (c) adhering the deposited ceramic nanoparticle ink to the surface of the substrate.

In at least some embodiments, the method may further include depositing the atomized ceramic nanoparticle ink onto the surface of the substrate at temperatures between 15° C. and 25° C. In still other possible embodiments, the method may include depositing the atomized ceramic nanoparticle ink onto the surface of the substrate at temperatures between 46° C. and 100° C. In some other embodiments, the method includes depositing the atomized ceramic nanoparticle ink onto the surface of the substrate at temperatures between 20° C. and 35° C. In other embodiments, the method includes depositing the atomized ceramic nanoparticle ink onto the surface of the substrate at temperatures between 100° C. and 200° C.

In some particularly useful embodiments, the atomizing is accomplished by pneumatic atomizing, ultrasonic atomizing, and combinations of pneumatic and ultrasonic atomizing. In some particularly useful embodiments, the depositing is by aerosol jet printing, conventional painting or combinations of aerosol jet printing and conventional painting. In some particularly useful embodiments, the adhering is accomplished by sintering. The sintering may be localized laser sintering. The localized laser sintering may be accomplished by using a 1064 nm Nd:YAG laser in either constant or pulsed modes. Coating layer depths of 10-100 microns may be achieved at travel speeds on the order of 50-500 mm/s with laser spot sizes between 100-1000 microns and average laser power of between about 50-5000 W.

The method may include using a ceramic nanoparticle ink comprising a composite combination of about 5-60 weight percent total solids and about 40-95 weight percent liquid feedstock, wherein the total solids include (a) about 80-98.9 percent ultra-high temperature ceramic nanoparticles, (b) about 0.1-10 percent solid dispersant/surfactant, and (c) about 1-10 percent carbon nanospheres. The liquid feedstock may be water. The liquid feedstock may be alcohol. In some embodiments, the liquid feedstock is selected from a group consisting of water, ethanol, acetone, isopropyl alcohol, ethylene glycol and mixtures thereof.

The ultra-high temperature ceramic nanoparticles may be selected from a group consisting of zirconium diboride, silicon carbide, hafnium carbide, hafnium diboride, tantalum carbide, and mixtures thereof. In at least some embodiments, the ultra-high temperature ceramic nanoparticles include zirconium diboride and silicon carbide at a ratio of zirconium diboride to silicon carbide of about 9:1. The solid dispersant/surfactant may be polyethylenimine. In some possible embodiments, the ultra-high temperature ceramic nanoparticles have a size of about 5-500 nm.

In the following description, there are described several different embodiments of the new and improved (a) method for depositing a ceramic nanoparticle ink onto a surface of a substrate and (b) aerosol formulation. As it should be realized, the method and aerosol formulation are capable of other, different embodiments and their several details are capable of modification in various, obvious aspects all without departing from the method and aerosol formulation as set forth and described in the following claims. Accordingly, the descriptions should be regarded as illustrative in nature and not as restrictive.

DETAILED DESCRIPTION

The new and improved method relates to the atomization, deposition and pressureless curing/sintering of a nanoparticle-based ultra-high temperature ceramic (UHTC) feedstock ink for coatings with high oxidation and thermal resistance. Key benefits of the methodology include the ability to deposit the ceramic particles at low (room) temperature to achieve stress-free and highly accurate deposition on ceramic, composite, and metal substrates. This methodology substantially differs from current approaches, such as plasma spark sintering, thermal spraying, and bulk sintering of bulk impregnated samples, which all impose high heat loads and lack the ability to micro-structure coatings and reduce coating stress to maximize adhesion and shear resistance.

The method includes: (a) atomizing the ceramic nanoparticle ink, (b) depositing the atomized ceramic nanoparticle ink onto the surface of the substrate at temperatures below 50° C., and (c) adhering the deposited ceramic nanoparticle ink to the surface of the substrate. In some embodiments of the method, the depositing of the atomized ceramic nanoparticle ink onto the surface of the substate is completed at temperatures between 15-45° C., 18-40° C., 20-35° C., 20-30° C. or 20-25° C.

As noted above, the ink needs to be atomized. This may be achieved pneumatically, by shear thinning of feedstock into droplets, or ultrasonically. Both methods have benefits and drawbacks. Pneumatic atomization is capable of atomizing higher viscosity inks with greater solids loading, but is typically characterized by having less control over droplet size and impaction dynamics (wetting, drying, etc.). The maximum viscosity and solids loading for ultrasonic atomization are 5 cP and 60 wt %, while pneumatic atomization can work with viscosities of up to 1000 cP and 80 wt % solids loading. Maximum particle sizes with ultrasonic atomization are 50 nm. Maximum particle sizes with pneumatic atomization are 500 nm.

Both conventional painting techniques and aerosol jet printing (AJP) are viable approaches for depositing coatings with the proposed method. While conventional painting offers greater deposition rates and coverage-speed, it suffers from limited droplet control, including limited control over impaction dynamics. In contrast, aerosol jet printing uses a sheath gas, of, for example, argon and mixtures of argon, carbon dioxide and helium for some applications, to focus and guide the atomized droplets onto the substrate, thereby achieving very limited overspray and very precise deposition kinetics. For this reason, aerosol jet printing is the preferable approach for many applications of the proposed coating methodology.

Localized sintering is the currently preferred approach to adhere the deposited ceramic nanoparticle ink to the surface of the substrate. The ideal sintering temperature for ZrB₂/SiC/C nanoparticle composite, which can be sintered without the need for high pressures (i.e., pressureless), is between 1900-2100° C. Other feedstocks may require slightly higher or lower temperatures. In all cases, the ability to sinter only the surface allows for careful control over coating and substrate stresses.

Nanoparticles require different sintering approaches than bulk coatings, so parameter development is conducted using process models and fundamental thermal transfer equations. To reduce thermal stress and damage to substrates with melting/degradation temperatures lower than this temperature range, localized laser sintering is used. This approach leverages transient heat transfer to locally heat and sinter the nanoparticles coating using a laser with small spot size and high travel speed to achieve thermal layer depths no greater than the desired near-surface coating/substrate region. A small spot size is necessary as the affected thermal layer depth is proportional to the laser spot size d and travel or scanning speed v. The exact size of the laser, its frequency, pulse width parameters, wavelength, and travel speed depend on the desired coating thickness, as well as coating material and substrate properties.

Higher laser average and peak pulse power enable higher sintering temperatures and faster scanning speed at a given processing temperature, while larger laser spot sizes provide deeper sintering depths. Pulsed lasers enable finer control over heat input while constant power lasers provide more consistent heating and typically feature significantly higher average power ratings than their pulsed counterparts. For pulsed lasers, control over the Q-pulse width enables very fine heat input control and is thus desirable for highly heat sensitive ceramic coatings. Although precise prediction of sintering temperatures and thermal layer depths requires sophisticated analytical and numerical modeling approaches, an approximation of the depth of the heated layer depth δ_thermal can be made based on the thermal diffusivity a of the ceramic feedstock material, the laser spot diameter d, and scanning velocity v via Equation (1).

δ thermal = 8 ⁢ α ⁢ d v Equation ⁢ 1

In one possible embodiment of the method, the localized laser sintering may be accomplished by using a neodymium-doped yttrium aluminum garnet (Nd:YAG) laser at a wavelength of 1064 nanometers in either constant or pulsed modes. Coating layer depths of 10-100 microns may be achieved at travel speeds on the order of 50-500 mm/s with laser spot sizes between 100-1000 microns and average laser power of between about 50-5000 W.

Aerosol formulations of ceramic nanoparticle ink useful in the method, include, but are not necessarily limited to a composite combination of about 5-60 weight percent total solids and about 40-95 weight percent liquid feedstock, wherein the total solids include (a) about 80-98.9 percent ultra-high temperature ceramic nanoparticles, (b) about 0.1-10 percent solid dispersant/surfactant, and (c) about 1-10 percent carbon nanospheres. In some embodiments, the dispersant/surfactant comprises between about 0.1-10% of the total solids.

The carbon nanospheres in the formulation act as a sintering aid to lower the minimum sintering temperature and promote greater solid-stage diffusion and neck formation during sintering at the short time scales of dynamic laser sintering. Significantly, it should be appreciated that the entire feedstock needs to be formulated/designed for laser sintering, which is significantly more challenging than feedstocks for conventional furnace or even SPS (spark plasma sintering) processes. The latter operate on the order of several seconds to minutes and even hours, while laser sintering operates on the order of milliseconds to fractions of seconds. (0.001 to 0.1 s). In one embodiment, a ceramic coating of gradient multi-component composition is designed to minimize thermal expansion mismatch between subsequent layers. For example, a relatively thin (˜10 micron) pure SiC base layer onto a carbon-based composite substrate would gradually transition to a ZrB₂/SiC composite composition of 80/20 wt. % over a distance of 100 microns in 3 layers with increasing ZrB² content in order to minimize the risk of cracking during both deposition and service. For gradient compositions, the feedstock needs to maintain an approximately constant viscosity so combination of multiple individual streams of individual UHTC particles, each with some amount of carbon nanospheres and dispersant/surfactant to tailor viscosity and promote efficient atomization, wetting onto the substrate, and sintering.

For most applications, water is used as the liquid feedstock as it is the most sustainable and environmentally friendly option. That said, other liquid feedstocks may be used. Those include high volatility alcohols and low volatility solvents. Specific examples of alternative liquid feedstocks include, but are not necessarily limited to, isopropyl alcohol, ethanol acetone and ethylene glycol. Mixtures of liquid feedstocks may also be used.

Ultra-high temperature ceramic nanoparticles refers to refractory ceramic materials that are able to withstand extremely high temperatures (up to and including 2,000° C.) without degrading. Useful UHTC materials include borides, nitrides, oxides and carbides of early transition metals. Specific examples of materials useful in the formulation include zirconium diboride (ZrB₂), silicon carbide (SiC), hafnium carbide (HfC), hafnium diboride (HfB₂), tantalum carbide (TaC), and mixtures thereof. In one particularly useful embodiment, the ultra-high temperature ceramic nanoparticles include zirconium diboride and silicon carbide at a ratio of zirconium diboride to silicon carbide of about 9:1. Preferably, the ultra-high temperature ceramic nanoparticles have a size of about 5-500 nm.

The solid dispersant/surfactant used in the formulation may be substantially any UTHC compatible surfactant known to those skilled in the art. For example, polyethyleneimine (PEI), may be utilized. Other examples include oxalic acid, polyacrylic acid (PAA), ammonium polyacrylate and other carboxylate polymers that act as anionic dispersants.

Experimental Section

Synthesis of the UHTC feedstock first requires mixing of the nanoparticles, which include the various ceramic and/or composite particles and the surfactant. In a specific embodiment, this included 1:5 solid/liquid ratio by weight in pure water as the liquid feedstock. Out of the 20% total weight percent dedicated to solids, a solid ratio of 9:1 between ZrB₂ and SiC nanoparticles with a mean diameter of 50 nm was used. Out of the total solids, 85% were ZrB₂ and SiC, 13% were 50 nm diameter porous carbon nanospheres, and 2% was a solid surfactant. The latter was provided by linear PEI solid powder. A surfactant was used to avoid clumping of the UHTC nanoparticles in the dispersion but may not be necessary in all embodiments. All solid particles and the liquid solution were weighed to a tolerance of 0.01 g with a total liquid volume of 10 ml for a small single batch of liquid feedstock. The solution was ball milled for 48 hours inside of a 30 ml Teflon bottle along with 5 mm diameter alumina spheres to promote mechanical milling without the risk of chemical reaction during the process. Following ball milling and removal of the ceramic balls with a sieve, the solution was ultrasonically agitated inside of a Teflon bottle for 30 minutes, which was repeated prior to each use of the feedstock as a coating ink to ensure proper dispersion of the particles. The ink was deposited onto ceramic and C/C substrates using aerosol jetting and subsequently demonstrated to significantly reduce substrate oxidation and ablation in a pure oxygen plasma.

Additional Ceramic Ink Feedstocks

UHTC feedstock synthesis first requires the creation of the nanoparticle colloidal systems, which include concentrated solutions of various ceramic and/or composite materials and a surfactant. For a specific embodiment, the following materials are used:

• • □ SiC with a purity of >99% and a particle diameter of 45-65 nm
  • □ ZrB₂ with a purity of 99% and a particle diameter of <43 nm
  • □ ZrB₂ with a purity of 99% and a particle diameter of 500 nm
  • □ TaC with a purity of >99% and a particle diameter of 300 nm

The concentrations of which are variable based on the viscosity of the feedstock. Each embodiment had a solids loading of between 4-12 vol %. The concentration of the feedstocks is measured by volume to overcome the difference in density that was causing some embodiments, specifically SiC concentrations, to have extremely high nanoparticle counts, and thus higher dynamic viscosities when compared to other feedstocks of similar concentrations. For example, a TaC feedstock, which has a density of nearly 4 times that of SiC, qualitatively had a viscosity similar to that of water at 30 wt %, while SiC was comparable to honey at that concentration.

In each system, an additional surfactant was added at 2% of the total solution by volume. This surfactant is an aqueous PEI solution. The surfactant is used to avoid clumping of the UHTC nanoparticles for some systems but may not be necessary in all embodiments. However, the addition of PEI increases the pH of embodiments contained therein, and PEI has been included in all embodiments to reduce the likelihood of unwanted chemical reactions.

The process for fabrication of these feedstocks are as follows:

• • 1. Prepare 30 ml Teflon bottle by filling it with 15 g of 5 mm diameter alumina spheres to promote mechanical milling without the risk of chemical reaction during the process.
  • 2. All solid particles, surfactant, and liquid water are weighed to a tolerance of ±0.01 vol % expected concentration and are kept separated to avoid preemptive cross-contamination.
  • 3. Liquid water and PEI surfactant are added to Teflon bottle, which is then sealed and ball milled for 10 minutes to promote a cohesive mixture and increase the pH of the solvent before adding solids.
  • 4. UHTC nanoparticle solids are added to the mixture, which is continuously ball milled for 48 hours.

A specific example of the creation of 18 mL of a 12 vol % ZrB₂-500 nm feedstock is as follows:

• • 1. Prepare 30 ml Teflon bottle by filling it with 15 g of 5 mm diameter alumina spheres to promote mechanical milling without the risk of chemical reaction during the process.
  • 2. Weigh the solid particles, surfactant, and liquid water according to the following breakdown, ensuring that the materials are kept separated

• • 3. Add liquid water and PEI to bottle and ball mill for 10 minutes. Remove from ball mill and add ZrB₂. Mill for an additional 48 hours.

Following the synthesis process, feedstocks are stored in a sealed container in the Teflon bottles to reduce loss. To counteract sedimentation, prior to use, the feedstock is ultrasonically agitated for 30 minutes at 30° C., repeated any time the feedstock has been stored for more than 60 minutes.

Aerosol Jetting Deposition

In some embodiments, deposition of the atomized ceramic feedstock is performed using aerosol jet printing (AJP). AJP enables the focusing of atomized droplets through a coaxial sheath gas flow that constricts and stabilizes the aerosol stream. This focusing mechanism provides improved spatial resolution, minimized overspray, and precise control of droplet impaction dynamics compared to conventional spraying or painting. As demonstrated in the literature, ceramic nanoparticles—including ZrB₂/SiC composites—can be deposited onto porous and dense ceramic substrates using ultrasonic aerosolization, though pneumatic atomization may offer higher throughput, broader viscosity tolerance, and improved reliability for higher-density or higher-solids UHTC inks.

In at least some embodiments, the AJP system is operated using a nozzle-to-substrate distance between 0.5-2.0 mm, with a preferred distance of approximately 1.27 mm (0.05 inches) to ensure line fidelity while reducing the likelihood of nozzle flooding or clogging. The sheath gas may comprise nitrogen, argon, air, or combinations thereof, and may be delivered at flow rates between 50-250 standard cubic centimeters per minute (sccm). The carrier gas flow rate may likewise be between 50-250 sccm, with higher carrier gas flow improving solids loading per unit length and enabling line thicknesses up to several micrometers per pass. In some embodiments, focusing (sheath) ratios between 0.5 and 2.0 are optimal for ceramic inks due to their higher viscosity and surface tension relative to conductive inks.

In certain embodiments, ultrasonic atomization may be employed when particle sizes are below approximately 50 nm and feedstock viscosity at atomization shear rates is below approximately 5 cP. However, pneumatic atomization may be used for inks containing particles up to approximately 500 nm and viscosities up to 1000 cP, enabling higher solids loading and the use of larger or denser ceramic powders such as TaC and coarse ZrB₂. Pneumatic atomization further enables stable droplet formation at higher flow rates, which reduces clogging risk and increases deposition rate.

The AJP methodology may employ either single-pass or multi-pass deposition strategies depending on the desired coating thickness. Single-pass deposition generally yields more uniform and sharper line profiles, whereas multi-pass depositions may increase coating width due to displacement of partially dried ink by the sheath gas. In some embodiments, printed features may exhibit line widths between 50-500 m, with inner widths corresponding to the highest solids density and outer widths originating from overspray associated with the aerosol plume. In some embodiments, lines widths on the order of several centimeters can be achieved with pneumatic atomization and a wide fan-shaped spray nozzle, in order to prioritize surface coverage over feature size when coating large areas.

Depending on substrate roughness and porosity, process windows may vary. In some embodiments, rough ceramic substrates such as sintered alumina exhibit more consistent line widths, reduced droplet beading, and improved nanoparticle adhesion compared to polished surfaces. Substrates with roughness values (Sa) between approximately 1-5 m may produce more uniform coatings due to enhanced liquid spreading resistance and reduced droplet mobility. Smooth substrates may produce droplet coalescence and discontinuous lines; therefore, roughened or textured surfaces may be advantageously selected for high-fidelity UHTC coatings via aerosol jetting. Surface preparation may be carried out by mechanical machining, bead blasting, or with laser machining techniques to obtain a surface with sufficient surface area to promote physical and mechanical bonding, while avoiding excessive roughness beyond Sa surface roughness values of m, which result in bead spreading and inconsistent surface coverage.

It may be said that this document relates to the following items.

• • 1. A method for depositing a ceramic nanoparticle ink onto a surface of a substrate, comprising: atomizing the ceramic nanoparticle ink;
    • depositing the atomized ceramic nanoparticle ink onto the surface of the substrate at temperatures below 50° C.; and
    • adhering the deposited ceramic nanoparticle ink to the surface of the substrate.
  • 2. The method of item 1, further including depositing the atomized ceramic nanoparticle ink onto the surface of the substrate at temperatures between 15° C. and 45° C.
  • 3. The method of item 1, further including depositing the atomized ceramic nanoparticle ink onto the surface of the substrate at temperatures between 18° C. and 40° C.
  • 4. The method of item 1, further including depositing the atomized ceramic nanoparticle ink onto the surface of the substrate at temperatures between 20° C. and 35° C.
  • 5. The method of item 1, further including depositing the atomized ceramic nanoparticle ink onto the surface of the substrate at temperatures between 20° C. and 30° C.
  • 6. The method of item 1, further including depositing the atomized ceramic nanoparticle ink onto the surface of the substrate at temperatures between 20° C. and 25° C.
  • 7. The method of item 1, wherein the atomizing is by pneumatic atomizing.
  • 8. The method of item 1, wherein the atomizing is by ultrasonic atomizing.
  • 9. The method of item 1, wherein the depositing is by aerosol jet printing.
  • 10. The method of item 1, wherein the depositing is by conventional painting.
  • 11. The method of item 1, wherein the adhering is by sintering.
  • 12. The method of item 11, wherein the sintering is localized laser sintering.
  • 13. The method of item 12, including completing the localized laser sintering using a neodymium-doped yttrium aluminum garnet laser to provide a coating of ceramic nanoparticle ink having a thickness of 10-100 microns at travel speeds between 50-500 mm/s with laser spot sizes between about 100-1000 microns and at an average laser power of about 50-5000 W. 14. The method of item 1, including using a ceramic nanoparticle ink comprising a composite combination of about 5-60 weight percent total solids and about 40-95 weight percent liquid feedstock, wherein the total solids include (a) about 80-98.9 percent ultra-high temperature ceramic nanoparticles, (b) about 0.1-10 percent solid dispersant/surfactant, and (c) about 1-10 percent carbon nanospheres.
  • 15, The method of item 14, wherein the liquid feedstock is water.
  • 16. The method of item 14, wherein the liquid feedstock is alcohol.
  • 17. The method of item 14, wherein the liquid feedstock is selected from a group consisting of water, ethanol, acetone, isopropyl alcohol, ethylene glycol and mixtures thereof.
  • 18. The method of item 14, wherein the ultra-high temperature ceramic nanoparticles are selected from a group consisting of zirconium diboride, silicon carbide, hafnium carbide, hafnium diboride, tantalum carbide, and mixtures thereof.
  • 19. The method of item 14, wherein the ultra-high temperature ceramic nanoparticles include zirconium diboride and silicon carbide at a ratio of zirconium diboride to silicon carbide of about 9:1.
  • 20. The method of item 14, wherein the solid dispersant/surfactant is polyethylenimine.
  • 21. The method of item 14, wherein the ultra-high temperature ceramic nanoparticles have a size of about 5-50 nm.

Although the aerosol formulation of this disclosure has been illustratively described and presented by way of specific exemplary embodiments, and examples thereof, it is evident that many alternatives, modifications, or/and variations, thereof, will be apparent to those skilled in art. Accordingly, it is intended that all such alternatives, modifications, or/and variations, fall within the spirit of, and are encompassed by, the broad scope of the appended claims.