Depositing material on fibrous textiles using atomic layer deposition for increasing rigidity and strength

Embodiments relate to depositing on one or more layers of materials on a fiber or fiber containing material using atomic layer deposition (ALD) to provide or enhance functionalities of the fibers or fiber containing material. A layer of material is deposited coated on the fibers or fiber containing textile by causing the relative movement between a fiber or the fiber containing textile and a source injector. The surface of the material is oxidized, nitrified or carbonized to increase the volume of the deposited material. By increasing the volume of the material, the material is subject to compressive stress. The compressive stress renders the fibers or the fiber containing material more rigid, stronger and more resistant against bending force, impact or tensile force.

BACKGROUND

1. Field of Art

The disclosure relates to depositing materials on fibers or textiles using atomic layer deposition to increase rigidity or afford other useful characteristics to the fibers or the textiles.

2. Description of the Related Art

A fiber generally lacks sufficient strength or rigidity for various applications. Hence, multiple fibers are often interlocked into yarn for higher strength and rigidity. The yarn is then used for producing textiles, crochet, knits, and ropes. Alternatively, fibers (e.g., carbon fibers) can be combined with other materials (e.g., polymer) to produce composites that are strong yet economically viable. Example of such composites include, among others, carbon-fiber-reinforced polymer (CFRP). CFRP may include Kevlar, aluminum or glass fibers in addition to carbon fibers for increased strength and improved properties

To increase strength or rigidity, fibers may be coated with materials. However, such fibers tend to form cracks or other defects on their surfaces when the fibers are bent beyond a certain curvature or stretched beyond an extent.FIG. 1is a cross-sectional diagram of a fiber100coated with a material102subject to bending force F. As the fiber100is bent (as illustrated inFIG. 1), the upper part of the fiber100and the coated material102is subject to tensile stress (denoted by “T” inFIG. 1) whereas the lower part of fiber100is subject to compression stress (denoted by “C” inFIG. 1). When the tensile stress exceeds a certain limit (e.g., when the fiber100is bent beyond an angle), the coated materials may crack due to cohesive failure (shown by reference numeral104) and adhesive failure (shown by reference numeral108). Similar cracks may occur when the fiber100and the coated material102are pulled or otherwise subject to tensile stress. Cracks formed on the coated materials result in reduced strength or rigidity of the fibers in addition to deterioration of functions provided by these coated materials.

When thin fibers are used, conventional methods of coating the materials on the fibers may be inadequate. That is, the materials may not become coated in a conformal manner on the fibers and the thickness of the coated materials may not be sufficiently thin to achieve the desired functionalities and properties.

SUMMARY

Embodiments relate to depositing material on a fiber or a fiber containing material to increase strength or rigidity of the fiber or the fiber containing material. Source precursor is injected onto the fiber or the fiber containing material followed by injection of reactant precursor on the fiber or the fiber containing material to deposit a layer of material on the surface of the fiber or the fiber containing material using atomic layer deposition (ALD). Compressive stress is induced in at least part of the layer by converting at least an outer portion of the layer to another material. The converted material has larger volume compared to the unconverted material, and therefore, introduces compressive stress in the layer.

In one embodiment, the conversion includes oxidizing, nitrifying or carbonizing the unconverted material.

In one embodiment, the deposited layer includes polycrystalline material. The compressive stress is induced by oxidizing, nitrifying or carbonizing at least part of grain boundaries and the outer surface of the polycrystalline material.

In one embodiment, the polycrystalline material layer includes at least one of semiconductor, metal compound or metal. The polycrystalline material layer may include TiN.

In one embodiment, an amorphous material layer is deposited on the surface of oxidized, nitrified or carbonized polycrystalline material layer. The amorphous material layer may include at least one of Al2O3or SiO2.

In one embodiment, the fiber comprises a carbon fiber.

In one embodiment, the reactant precursor comprises radicals generated by exposing gas to plasma.

In one embodiment, the deposited layer includes an amorphous material. The amorphous material may be Al2O3or SiN.

Embodiments also relate to a textile comprising a plurality of fibers where each of the fibers is deposited with a layer of material on its surface using atomic layer deposition (ALD) to increase strength or rigidity. A treated layer is formed on the surface of the material by oxidizing, nitrifying or carbonizing parts of the material layer to induce compressive stress in the deposited material layer. The treated layer at least partially diffuses into the grain boundaries of the material layer. The compressive stress in the material layer increases strength or rigidity of each fiber.

In one embodiment, the deposited layer includes polycrystalline material. The compressive stress is induced by oxidizing, nitrifying or carbonizing at least part of grain boundaries and the outer surface of the polycrystalline material.

DETAILED DESCRIPTION OF EMBODIMENTS

Embodiments are described herein with reference to the accompanying drawings. Principles disclosed herein may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. In the description, details of well-known features and techniques may be omitted to avoid unnecessarily obscuring the features of the embodiments.

In the drawings, like reference numerals in the drawings denote like elements. The shape, size and regions, and the like, of the drawing may be exaggerated for clarity.

Embodiments relate to depositing one or more layers of materials on a fiber or fiber containing material using atomic layer deposition (ALD) to increase rigidity or strength to provide resistance to bending, impact or tensile force. A layer of material is deposited on the fibers or the fiber containing material and then at least part of the deposited material is oxidized, nitrified or carbonized to induce compressive stress in the material layer. The deposited material may be polycrystalline material or amorphous material. The compressive stress renders the fibers or the textile more rigid, stronger and more resistant against bending force, impact or tensile force. Further, the fibers or the textile can be coated with additional materials to prevent oxidization or prevent detection against night vision cameras.

The fiber containing material described herein refers to any material containing fibers. The fiber containing material include, for example, yarn, textile and composite material. The fibers in the fiber containing materials may or may not be interlocked with each other.

The one or more layers of materials described herein may be deposited on the fibers before or after being incorporated into the fiber containing material.

Example Fibers or Textile Coated with Materials

A fiber and fiber containing material may lack desired properties such as rigidity or strength that may lead to reduced resistance against bending force, impact or tensile force. In order to increase the rigidity or strength, the fiber or the fiber containing material may be deposited with materials that enhance the rigidity or strength. However, the deposited material is often subject to tensile stress after deposition of the material. Hence, the deposited material is vulnerable to cracks or other defects when the fiber or the fiber containing material is bent or subject to tensile stress for other reasons.

Especially, when the material deposited on the fiber or fiber containing material is polycrystalline material, the grain boundaries of the material have a higher free energy and are often in an unstable state. Further, the bonding force between the grains is generally weak. Therefore, a layer formed of polycrystalline material has an inferior barrier characteristic as well as being prone to cracks or other failures that propagate from the grain boundaries.

In one or more embodiments, the rigidity or strength of the fiber of the fiber containing material is increased by expanding the volume of the grains after the polycrystalline material is deposited on the fiber or the fiber containing material. The volume of the grains can be increased by oxidizing, nitrifying or carbonizing the surface and at least part of the grain boundaries of the polycrystalline material.

Alternatively, amorphous material may be deposited on the fiber or fiber coating material instead of depositing the fiber or fiber containing material with polycrystalline material. The outer region of the amorphous material may be oxidized, nitrified or carbonized to expand the volume and introduce compressive stress in the outer region of the material.

FIG. 2Ais a cross sectional view of a fiber200deposited with a polycrystalline material layer204, according to one embodiment. AlthoughFIG. 2Aillustrates a single fiber200deposited with the polycrystalline material layer204, an entire yarn, textile or any other fiber containing material may be deposited with the polycrystalline material layer204using atomic layer deposition (ALD). In one embodiment, the polycrystalline material is TiN and has a thickness of 10 Å to 500 Å using a deposition device, described below in detail with reference toFIGS. 4 through 6. In other embodiments, the polycrystalline material may be one or more of semiconductor material (e.g., Si, Ge), metal (e.g., Al, Ti, Ta), metal compounds with a high melting temperature (e.g., TiAlN, TiCN, WC).

The use of ALD for depositing the polycrystalline material layer204is advantageous, among other reasons, because the layer204is deposited on the fiber200in a conformal manner with a thin thickness at a lower deposition temperature than other deposition methods.

The fiber200may be a carbon fiber or any other fibers. In an embodiment where the fiber contains carbon, the initial deposited layer may react with carbon atoms to create stronger bonding with the fiber. For example, when a carbon fiber is deposited with TiN, an initial layer of TiN film reacts with carbon atoms in the carbon fiber and forms a TiCN layer. TiCN layer advantageously increases the bonding force between the carbon fiber and TiN layer204further deposited on the TiCN layer.

After a polycrystalline layer of TiN204is formed on the TiCN layer, the fiber200is exposed to oxygen, H2O, ozone, O* radicals or a combination thereof to oxidize the surface and grain boundaries of the TiN layer204into TiON. The grain boundaries of the TiN layer204are oxidized by diffusing these oxidizing agents into the grain boundaries. Because the extent of diffusion of oxidizing agents decreases with the depth of the TiN layer, the oxidized portion of the TiN layer204tends to be wider at the surface but becomes thinner as the depth towards the fiber200increases. As a result of the oxidization, the cross sectional shape of TiON layer208takes a revere triangular shape that extends at least partially into the grain boundaries of TiN layer204.

Because TiON takes up more volume compared to TiN, the overall volume of the deposited material increases as the surface and the grain boundaries of the TiN layer204are oxidized into a TiON layer208. However, since the TiN layer204and the TiON layer208are bonded to the fiber200, the spatial expansion of these layers is restricted. As a result, these layers are instead subject to compressive stress.

Moreover, the bonding of TiON with the grains of TiN is stronger than the bonding between the grains of TiN. Therefore, cracks are less likely to occur between the boundaries of TiON and the TiN grains. As a result, the oxidization of the TiN into TiON between the boundaries further increases the strength of the fiber. In one or more embodiment, the thickness of the TiON layer is 5 to 50 Å.

TiON is also more resistant to diffusion compared to TiN. Therefore, TiON layer208may also function as a diffusion barrier to prevent other materials from penetrating into the fiber200.

Alternatively, TiN layer204may be carbonized using, for example, C* radicals. As a result, a TiCN layer is formed on the surface of the TiN layer and also penetrates into the grain boundaries of TiN. The TiCN layer also has a larger volume compared to a TiN layer, and therefore, the formation of TiCN layer on the surface of TiN layer and penetration of TiCN into the grain boundaries cause compressive stress in TiN and TiCN layer. Further, TiCN is more resistant to diffusion compared to TiN, and therefore, TiCN also functions as a diffusion barrier for the barrier.

A layer formed by oxidizing, nitrifying or carbonizing the polycrystalline layer advantageously increases the rigidity or strength of the fiber and also functions as a diffusion barrier for the fiber.

In one embodiment, an amorphous layer is deposited on the oxidized, nitrified or carbonized polycrystalline layer. For example, a layer of Al2O3or SiO2of 10 to 100 Å thickness is deposited on the oxidized, nitrified or carbonized polycrystalline layer. The amorphous layer reduces problems associated with coating of the polycrystalline layer because the amorphous layer may have tensile stress and the combination of different stressed films results in increased stiffness.

In one embodiment, multiple sets of layers of TiN and TiON can be deposited on the fiber or the fiber containing material. The process of depositing TiN and forming TiON may be repeated for a predetermined number of times to deposit multiple sets of TiN/TiON layer on the fiber or the fiber containing material to further increase the rigidity or strength of the fiber or the fiber containing material.

In another embodiment, multiple sets of layers, each set including a TiN layer, a TiON layer and an amorphous layer, are deposited on the fiber by repeating the process for a predetermined number of times.

FIG. 3Ais a cross sectional view of a fiber300A deposited with materials, according to one embodiment. The fiber300A may be a carbon fiber, which is then deposited with a first material (e.g., TiN, Al2O3, SiN)310A of thickness t1a, a layer320A of thickness t2aformed by oxidizing, nitrifying or carbonizing the first material (e.g., TiON, TiCN, AlON, SiO2), and an amorphous layer330A of thickness t3a. In one embodiment, the thickness of t1ais 10 to 500 Å, the thickness of t2ais 5 to 50 Å and the thickness of t3ais 10 to 500 Å.

The process of depositing layers310A,320A,330A may be repeated for a predetermined number of cycles to deposit sets of layers on the fiber300A.

In another embodiment, an amorphous layer is deposited on the fiber before depositing the polycrystalline layer. As shown inFIG. 3B, for example, an amorphous layer330B of Al2O3or SiO2is first formed on fiber300B using ALD. Subsequently, a polycrystalline layer320B is deposited on the amorphous layer330B. Finally, the polycrystalline layer320B is oxidized, carbonized or nitrified to form a final layer310B. The amorphous layer330B has a thickness of t1b, the polycrystalline layer320B has a thickness of t2b, and the oxidized, carbonized or nitrifying layer310B has a thickness of t3b. The thickness of t1bis 10 to 500 Å, the thickness of t2bis also 10 to 500 Å, and the thickness of t3bis 5 to 50 Å.

The process of depositing layers310B,320B,330B may be repeated for a predetermined number of cycles to deposit sets of layers on the fiber300B.

Instead of depositing polycrystalline material on the fiber, amorphous material may be deposited on the fiber. For example, Al2O3may be deposited on the fiber using trimethylaluminium (TMA) as source precursor, followed by purging of TMA physisorbed on the fiber using a purge gas, and then injecting reactant precursor generated from H2O, O3, O2plasma or N2O plasma onto the fiber. Such layer of Al2O3generally has 5×109to 1×1010dyne/cm2of tensile stress.

The Al2O3layer is then exposed to O* radicals and/or N* radicals generated by causing plasma on a gas including O2and NH3or N2O and NH3. The percentage of NH3may be retained below 30% since excessive NH3tends to create particles that may negatively affect the deposition process. In this way, the outer periphery of the Al2O3is converted into AlON which has an increased volume compared to Al2O3. The AlON layer is subject to compressive stress of about 1×109to 5×109dyne/cm2.

As a result of depositing Al2O3and AlON on the fiber, the fiber becomes more robust against bending and also stiffer. Multiple layers of Al2O3and AlON may be deposited on the fiber in an alternating matter to afford increased resistance to bending and stiffness.

The thickness Al2O3layer formed on the fiber may be less that 2% of the diameter of the fiber. The thickness of Al2O3layer may be 50 Å through 300 Å.

The amorphous material may also be SiN. SiN may be deposited on a fiber using HMDS (Hexamethyldisilazane: (CH3)3—Si—NH—Si—(CH3)3) as a source precursor, and N* radicals as reactant precursor. The thickness of SiN layer may be less than 2% of the diameter of the fiber. The thickness of SiN layer may be 50 Å through 300 Å. The outer periphery of SiN layer may be exposed to O* radicals to convert the exposed portion of the SiN layer to SiO2. SiO2has a higher volume compared to SiN, and therefore, compressive stress is introduced into the deposited material.

Examples of Deposition Device

FIG. 4is a perspective view of a deposition device400, according to one embodiment. Although the deposition device400is illustrated as depositing layers of materials on a textile, the same deposition device400may be used to deposit layers of material on a fiber or other fiber containing materials.

The deposition device400may include, among other components, an upper reactor430A and a lower reactor430B. As textile420moves from the left to right (as indicated by arrow414) and passes between the upper and lower reactors430A,430B, the textile420is deposited with a layer440of material. In one embodiment, the layer440is a polycrystalline layer, a layer formed by oxidizing, carbonizing or nitrifying the polycrystalline layer or an amorphous layer.

The entire deposition device400may be enclosed in a vacuum or in a pressurized vessel. Although the deposition device400is illustrated as depositing material on the textile420as the textile420moves horizontally, the deposition device400may be oriented so that the layer440is deposited as the textile420moves vertically or in a different direction.

The upper reactor430A is connected to pipes442A,446A,448A supplying precursor, purge gas and a combination thereof into the upper reactor430A. Exhaust pipes452A and454A are also connected to the upper reactor430A to discharge excess precursor and purge gas from the interior of the upper reactor430A. The upper reactor430A has its lower surface facing textile420.

The lower reactor430B is also connected to pipes442B,446B,448B to receive precursor, purge gas and a combination thereof. Exhaust pipes (e.g., pipe454B) are also connected to the lower reactor430B to discharge excess precursor and purge gas from the interior of the lower reactor430B. The lower reactor430B has it upper surface facing the textile420.

The deposition device400performs atomic layer deposition (ALD) on the textile420as the textile420moves from the left to the right between the lower surface of the upper reactor430A and the upper surface of the lower reactor430B. ALD is performed by injecting source precursor on the textile420followed by reactant precursor on the textile420.

FIG. 5is a cross sectional view of the deposition device400taken along line A-B ofFIG. 4, according to one embodiment. The upper reactor430A may include, among other components, a source injector502and a reactant injector504. The source injector502is connected to the pipe442A to receive the source precursor (in combination with carrier gas such as Argon) and the reactant injector504is connected to the pipe448A to receive reactant precursor (in combination with carrier gas such as Argon). The carrier gas may be injected via a separate pipe (e.g., pipe446A) or via the pipes that supply the source or reactant precursor.

The body510of the source injector502is formed with a channel542, perforations (e.g., holes or slits)544, a reaction chamber534, a constriction zone560and an exhaust portion562. The source precursor flows into the reaction chamber534via the channel542and the perforations544, and reacts with the textile120. Part of the source precursor penetrates the textile420and is discharged via an exhaust portion268formed on the lower reactor430B. The remaining source precursor flows through the constriction zone560in parallel to the surface of the textile420and is discharged into the exhaust portion562. The exhaust portion is connected to the pipe452A and discharges the excess source precursor out of the injector502.

When the source precursor flows through the constriction zone560, excess source precursor is removed from the surface of the textile420due to the higher speed of the source precursor in the construction zone560. In one embodiment, the height M of the constriction zone560is less than ⅔ the height Z of the reaction chamber534. Such height M is desirable to remove the source precursor from the surface of the textile420.

The reactant injector504has a similar structure as the source injector502. The reactant injector504receives the reactant precursor and injects the reactant precursor onto the textile420. The source injector504has a body514formed with a channel546, perforations548, a reaction chamber536, a constriction zone564and an exhaust portion566. The functions and the structures of these portions of the reactant injector504are substantially the same as counterpart portions of the source injector502. The exhaust portion566is connected to the pipe454A.

The lower reactor430B has a similar structure as the upper reactor430A but has an upper surface facing a direction opposite to the upper reactor430A. The lower reactor430B may include a source injector506and a reactor injector508. The source injector506receives the source precursor via the pipe542B and injects the source precursor onto the rear surface of the textile420. Part of the source precursor penetrates the textile420and is discharged via the exhaust portion562. The remaining source precursor flows into the exhaust portion568in parallel to the surface of the textile420and is discharged from the source injector502.

The structure of the reactor injector508is substantially the same as the reactor injector504, and therefore, detailed description thereof is omitted herein for the sake of brevity.

The deposition device400may also include a mechanism580for moving the textile420. The mechanism580may include a motor or an actuator that pulls the textile420to the right direction as illustrated inFIG. 5. As the textile420is move progressively to the right, substantially the entire surface of the textile420is exposed to the source precursor and the reactant precursor, depositing material on the textile420as a result.

By having an opposing set of reactors, the source precursor and the reactant precursor flow perpendicular to the surface of the textile420as well as in parallel to the surface of the textile420. Therefore, a layer of conformal material is deposited on the flat surface as well as the pores or holes in the textile420. Hence, the material is deposited more evenly and completely on the textile420.

In order to reduce the precursor material leaked outside the deposition device400, the distance H between the textile420and the upper/lower reactor430A,430B is maintained at a low value. In one embodiment, the distance H is less than 1 mm, and more preferably less than tens of μms.

In one embodiment, TiCl4is used as the source precursor and NH3is used as the reactant precursor to form a polycrystalline TiN layer on the textile420. After forming TiN layer on the textile420, the textile may be exposed to oxygen, H2O, ozone, O* radicals or a combination thereof to oxidize the surface and grain boundaries of the TiN layer into TiON.

Furthermore, inorganic material such as SiH4, SiCl2H2or organic metal compound such as hexamethyldisilazane (HMDS), tetramethyldisiloxane (TMDSO), tris(dimethylamino)silane (TDMAS) is used as source precursor, and O* radical, H2O, ozone or a combination thereof is used as reactant precursor to deposit SiO2on the fiber. In order to deposit Al2O3, TMA or dimethylaluminumhydride (DMAH) may be used as the source precursor.

FIG. 6is a cross sectional view of a deposition device600including radical reactors604,608A, according to one embodiment. The deposition device600is substantially the same as the deposition device500except that the injectors504,508are replaced with the radical reactors604,608A.

The deposition device600includes source injectors602,606A and the radical reactors604,608A. The structure and function of the source injectors602,606A are the same as the source injectors502,506, and therefore, the description thereof is omitted for the sake of brevity. The textile420moves from the left to the right as shown by arrow611inFIG. 6so that the textile420is exposed first to the source precursor (by the source injectors602,606A) and then the radicals (by the radical reactors604,608A).

The radical reactor604may include, among other components, an inner electrode614and a body620. The body620may be formed with, among other structures, a channel622, perforations (e.g., holes or slits)618, a plasma chamber612, an injection holes626, a reaction chamber624and an exhaust portion632. Gas is provided into the plasma chamber612via the channel622and the perforations618. Voltage difference is applied between the inner electrode614and the body620of the radical reactor604to generate plasma within the plasma chamber612. The body620of the radical reactor604functions as an outer electrode. In an alternative embodiment, an outer electrode separate from the body620may be provided to surround the plasma chamber612. As a result of generating the plasma, radicals of the gas is formed in the plasma chamber612and injected into the reaction chamber624via the injection holes626.

As described above with reference toFIG. 5, part of the radicals generated by the radical reactors604,608A penetrate the substrate and are discharged by exhaust portions provided in the radical reactors of the opposite side. The other radicals flow in parallel to the surface of the textile420and are discharged by the exhaust portions of the radical reactor that generated the radicals.

In one embodiment, the radical reactors604,608A generates and injects N* radicals as reactant precursor onto the textile420previously injected with source precursor including TiCl4to form a polycrystalline TiN layer on the textile420.

In one embodiment, the radical reactors604,608A generate and inject O* radicals as reactant precursor onto the textile420previously injected with source precursor including inorganic material such as SiH4, SiCl2H2or organic metal compound such as hexamethyldisilazane (HMDS), tetramethyldisiloxane (TMDSO), tris(dimethylamino)silane (TDMAS) to deposit SiO2on the fiber. Similarly, O* radicals may be injected as the reactant precursor onto the textile420previously injected with source precursor including trimethylaluminium (TMA) or dimethylaluminumhydride (DMAH) to deposit Al2O3on the textile420.

Fibers or fiber containing materials may be processed by the depositing devices500,600to deposit materials on the fibers or the fiber containing material. Furthermore, the same textile, fibers, yarn or other component structures may undergo repeated processes at the depositing devices500,600to deposit multiple sets of layers on the fibers or the fiber containing material.

Devices for depositing materials on the fibers or the fiber containing material are described above with reference toFIGS. 4 through 6are merely illustrative. Various other devices may be used to deposit materials on the fibers of the fiber containing material.

Examples Method of Depositing Material

FIG. 7is a flowchart illustrating a method of depositing materials on the fibers or fiber containing material, according to one embodiment. First, a layer of first material layer is deposited702on a fiber or a fiber containing material using ALD. For this purpose, a depositing device described above with reference toFIGS. 4 through 6may be used. The first material may be polycrystalline material such as TiN or amorphous material such as Al2O3or SiO2.

After a layer of first material is deposited on the fiber or the fiber containing material, at least part of the first material is converted706into second material that has larger volume than the first material to introduce compressive stress in the layer. The conversion may oxidizing, nitrifying or carbonizing of the first material. The second material may include, for example, TiON when the first material is TiN.

Then an amorphous material layer may be deposited710on the oxidized, nitrified or carbonized surface of the polycrystalline material layer. The amorphous material layer may include, for example, Al2O3or SiO2. In this way, the amorphous layer may be subject to tensile stress and combination of differently stressed films will increase the stiffness of the fiber or the fiber containing material, and the outer most layer should have compressive stress for the increased rigidity on the fibers or fiber containing materials.

It is then determined714whether the thickness of deposited materials is sufficient. If the thickness of the deposited materials is not sufficient, the process returns to depositing702a layer of first material on the fiber or the fiber containing material. If the thickness of the deposited materials is sufficient, then the process terminates.

The process illustrated inFIG. 7is merely illustrative. Alternatively, certain steps inFIG. 7may be omitted. For example, depositing710of the amorphous layer may be performed before depositing a polycrystalline material layer on the fiber or the fiber containing material. Alternatively, depositing710of the amorphous material layer may be omitted.

Depositing Material for Other Functionality

In lieu of or in addition to coating materials to increase rigidity or strength, the fiber or the fiber containing material may be coated with material to lower the emissivity of the fibers, yarn or textile. The emissivity is a property of a material related to emission of energy from its surface relative to other materials. In applications such as military uniforms, it is advantageous to lower the emissivity of the fiber or fiber containing material to prevent detection of the person wearing the military uniform by night vision. To lower the emissivity, the fiber or the fiber containing material may be coated with paint to reduce the emissivity of the uniform. However, the effect of the paint may not endure for a long time since the paint may be become peeled off or removed during washing or repeated use of the uniform.

In one embodiment, aluminum is deposited on the fibers, yarn or textile using ALD to lower emissivity. For this purpose, DMAH (DimethylaluminumHydride) may be used as a source precursor and hydrogen plasma may be used as a reactant precursor. Aluminum deposited using ALD is bonded securely to the fibers, yarn or textile. Hence, the decreased emissivity persists for a longer duration compared to coating of paint on textile.

Fibers may be deposited with material to isolate the fibers from moisture or oxygen. Carbon fibers, for example, are used as heating components in heaters due to its high electric conductivity. However, these fibers may react with moisture or oxygen at a high temperature (e.g., 300° C.) and oxidize. Therefore, materials such as Al2O3may be deposited on the carbon fibers to prevent the carbon fibers from oxidizing at a high temperature. Al2O3may be deposited on the fibers, for example, by using trimethylaluminium (TMA) or dimethylaluminumhydride (DMAH) as the source precursor and O* radical, H2O, ozone or a combination thereof as reactant precursor.

Example Use of Fibers, Yarn or Textile Deposited with Material

The fibers, yarn or textile deposited with polycrystalline material and its corresponding carbonized, nitrified or oxidized layer may be used to form fabric. Such form can be cut and shaped into wearable clothes. One of such wearable clothes is military uniforms or bullet proof vests. The same fibers, yarn or textile may be coated with low emissive material, as described above, to decrease the chance of detection by night vision cameras. Alternatively, different fibers, yarn or textile coated with low emissive material may be used in conjunction with the fibers, yarn or textile deposited with polycrystalline material for to fabricate clothes with enhanced strength and rigidity as well as lower detection by night vision cameras.

The fibers, yarn or textile deposited with polycrystalline material and its corresponding carbonized, nitrified or oxidized layer may be used as component for composite material. For example, the fibers, yarn or textile coated with the polycrystalline material may be used in carbon-fiber-reinforced polymer (CFRP).

Although the present invention has been described above with respect to several embodiments, various modifications can be made within the scope of the present invention. Accordingly, the disclosure of the present invention is intended to be illustrative, but not limiting, of the scope of the invention, which is set forth in the following claims.