摘要:
A method of making a multi-composition fiber is provided, which includes providing a precursor laden environment, and forming a fiber in the precursor laden environment using laser heating. The precursor laden environment includes a primary precursor material and an elemental precursor material. The formed fiber includes a primary fiber material and an elemental additive material, where the elemental additive material has too large an atom size to fit within a single crystalline domain within a crystalline structure of the fiber, and is deposited on grain boundaries between adjacent crystalline domains of the primary fiber material to present an energy barrier to atomic diffusion through the grain boundaries, and to increase creep resistance by slowing down growth between the adjacent crystalline domains of the primary fiber material.
摘要:
Nanotube filaments comprising carbon, boron and nitrogen of the general formula BxCyNz, having high-aspect ratio and high-crystallinity produced by a pressurized vapor/condenser method and a process of production. The process comprises thermally exciting a boron-containing target in a chamber containing a carbon source and nitrogen at a pressure which is elevated above atmospheric pressure.
摘要:
A method of forming a nanowire comprising: providing nanoparticles of a metallic material; providing a vapor of fluorocarbon molecules by heating a solid polymer; depositing at least some of the carbon of said molecules onto an exterior of one of said particles to form a deposit of carbon which surrounds at least part of the exterior of said one particle and assembling further of said particles with said one particle to form an elongate configuration of material in the form of a nanowire. Similar methods of production of nanotubes are also disclosed.
摘要:
A metal carbide ceramic fiber having improved mechanical properties and characteristics and improved processes and chemical routes for manufacturing metal carbide ceramic fiber. Metal carbide ceramic fibers may be formed via reaction bonding of a metal-based material (e.g. boron) with the inherent carbon of a carrier medium. One embodiment includes a method of making a metal carbide ceramic fiber using VSSP to produce high yield boron carbide fiber. Embodiments of the improved method allow high volume production of high density boron carbide fiber. The chemical routes may include a direct production of boron carbide fiber from boron carbide powder (B4C) and precursor (e.g. rayon fiber) having a carbon component to form a B4C/rayon fiber that may be processed at high temperature to form boron carbide fiber, and that may be subsequently undergo a hot isostatic pressing to improve fiber purity. Another route may include a carbothermal method comprising combining boron powder (B) with a precursor (e.g., rayon fiber) having a carbon component to form a B/rayon fiber, carbonizing and a chemical reaction of boron (B) and carbon (C) to form boron carbide fiber. Another carbothermal method may comprise combining boron oxide powder (B2O3) with a precursor (e.g., rayon fiber) having a carbon component to form a B2O3/rayon fiber, carbonizing and a chemical reaction of boron oxide (B2O3) and carbon (C) to form boron carbide (B4C) fiber.
摘要翻译:一种金属碳化物陶瓷纤维,其具有改进的机械性能和特性,以及用于制造金属碳化物陶瓷纤维的改进方法和化学 金属碳化物陶瓷纤维可以通过金属基材料(例如硼)与载体介质的固有碳的反应结合而形成。 一个实施方案包括使用VSSP制备金属碳化物陶瓷纤维以产生高产率碳化硼纤维的方法。 改进方法的实施例允许高容量生产高密度碳化硼纤维。 化学路线可以包括从碳化硼粉末(B4C)直接生产碳化硼纤维和具有碳组分的前体(例如人造纤维),以形成可在高温下加工以形成碳化硼纤维的B4C /人造丝纤维, 然后可以进行热等静压,以提高纤维纯度。 另一种途径可以包括碳热法,其包括将硼粉末(B)与具有碳组分的前体(例如人造丝纤维)组合以形成B /人造丝纤维,碳化和硼(B)和碳(C)的化学反应, 以形成碳化硼纤维。 另一种碳热法可以包括将氧化硼粉末(B 2 O 3)与具有碳成分的前体(例如人造纤维)组合以形成B 2 O 3 /人造丝纤维,碳化和氧化硼(B 2 O 3)和碳(C)的化学反应与 形成碳化硼(B4C)纤维。
摘要:
A metal carbide composition and a process for synthesizing metal carbides, through a single step process, wherein oxides of different metals, including, but not limited to Si, Ti, W, Hf, Zr, V, Cr, Ta, B, Nb, Al, Mn, Ni, Fe, Co, and Mo were physically mixed with spherical or filamentateous nano structured carbon, and inductively heated to a certain temperature range (900-1900° C.) where the metal oxide reacts with carbon to form different metal carbides. The process retains the original morphology of the starting carbon precursor in the resultant metal carbides. This method also produces highly crystalline metal nano-carbides. The metal carbide products would have applications in high temperature thermoelectric devices, quantum wells, optoelectronic devices, semi-conductors, body armour, vehicle armour, catalysts, and as discontinuous reinforced agents in metal such as aluminum and other alloys.
摘要:
A plurality of carbide, such as silicon carbide, tungsten carbide, etc., nanofibrils predominantly having diameters substantially less than about 100 nm and a method for making such carbide nanofibrils. The method includes the steps of: heating a plurality of carbon nanotubes or nanofibrils predominantly having diameters less than about 50 nm in a reaction chamber in the presence of a gas of the form QnAm, where Q is a metal capable of forming a carbide, A is an element or radical and n and m are integers necessary to satisfy valences, such as, for example silicon monoxide, and an inert gas in a reaction vessel to a temperature substantially less than 1700 C but sufficently high to cause substantial reaction of the metal in the gas with the carbon of said carbon nanotubes or nanofibrils to form, in situ, solid carbide nanofibrils, the temperature being sufficiently low to prevent substantial fusing together of individidual ones of said carbide nanofibrils, removing at least a portion of A-based gas from said reaction chamber as said reaction progresses, and maintaining said temperature until substantially all the carbon of said nanotubes or nanofibrils has been converted into Q-based carbide.
摘要:
A high temperature, preferably polycrystalline, ceramic fiber having a selectable diameter of between 1 and 200 microns. The fiber is stable in an inert atmosphere at a temperature above about 1700.degree. C. and is often stable even in air at a temperature above 1500.degree. C. The fiber comprises a sintered ceramic powder having a maximum particle size less than the diameter of the fiber and an average particle size less than 0.2 times the diameter of the fiber. The ceramic powder is also stable in an inert atmosphere at a temperature above about 1700.degree. C. At least 90% of the ceramic is selected from borides, nitrides, carbides, and silicides. The fiber is characterized by a smooth surface and is preferably out of round.The invention further comprises a textilable sinterable filament, comprising a flexible polymer matrix containing high temperature sinterable ceramic powder particles. The ceramic powder particles are selected from ceramic borides, nitrides, carbides, and silicides. The diameter of the filament is from 2 to 300 microns. The invention also comprises the method for making textilable filament by fiberizing a mixture of a polymer and a sinterable non-oxide fiber and the method wherein the high temperature ceramic fiber is prepared by sintering the textilable sinterable filament as previously described. The invention also includes composites containing such filaments.
摘要:
A process for strengthening carbide fibers by removing internal stresses caused by their formation. This process is accomplished by drawing the carbide fiber under tension through a furnace. The temperature of the furnace may range from about 2050.degree. to 2300.degree.C while the fiber tensile stress may vary from about 200 to 3500 p.s.i. when using boron carbide fibers with diameters ranging from about 8 to 14 microns.
摘要:
Boric oxide fibers having a maximum diameter of about 10 microns are heated in an ammonia atmosphere to about 350*-600*C at a rate of temperature rise of up to about 5,000*C/hr. to produce ammonia-treated fibers consisting essentially of B, N. O and H. The ammonia-treated fibers are heated in an amine atmosphere at about 600*-1,000*C to produce amine-treated fibers consisting essentially of B, C, N, O and H and containing at least about 15% C. The amine-treated fibers may be heated at about 2,000*-2,350*C in an inert atmosphere to produce boron carbide fibers.