232 results about "MAX phases" patented technology

The invention discloses a broadband wave-absorbing material based on an MAX-phase metasurface structure and an impedance matching optimization method of the broadband wave-absorbing material. The wave-absorbing material comprises an MAX-phase ceramic substrate and periodic metasurface structures which are arranged on the surface of the MAX-phase ceramic substrate in an array mode and composed of conductive resonance units. The resonance units are isolated through gaps, an equivalent R1L1C1 series resonance circuit is formed in an electromagnetic field, and a base body is equivalent to a parallel resistor R2. By establishing an equivalent circuit model and optimizing parameters R1, L1, C1 and R2, impedance matching of the wave-absorbing material in a target frequency band can be regulated and controlled, so that the wave-absorbing material at least has an absorption peak of which the reflection loss is less than-10 dB. According to the optimization method, electromagnetic simulation and circuit simulation are combined, optimized circuit parameters are reversely mapped into structure geometric parameters, material preparation is guided, and accurate design and broadband absorption of the wave absorbing performance are achieved.

The invention discloses a silane coupling agent grafted MXene composite material and a preparation method thereof, relates to the technical field of composite materials, and aims to provide a surface modification method to enable the MXene composite material to be in good contact with a PDMS (polydimethylsiloxane) material. The surface modification method comprises the following steps: S1, performing wet chemical etching on an MAX phase material in combination with mechanical stripping to obtain a few-layer MXene dispersion liquid; s2, strong base is added into the few-layer MXene dispersion liquid in the step S1, the PH value of the few-layer MXene dispersion liquid is adjusted, a reaction is conducted in the argon environment, and hydroxyl modified MXene dispersion liquid, namely h-MXene dispersion liquid is obtained; and S3, adding a silane coupling agent and a catalyst into the h-MXene dispersion liquid in the step S2, and reacting in an argon environment to obtain the silane coupling agent grafted MXene composite material.

The invention provides an alkaline ion battery negative electrode material as well as a preparation method and application thereof, and particularly relates to an MXene / MoS2 / TiO2 composite material which is prepared by the following steps: etching an MAX phase by using mixed acid containing HF to obtain MXene; performing freeze drying to obtain powder containing MXene, a Mo source and an S source; and calcining to obtain the composite material. According to the negative electrode material disclosed by the invention, MoS2 is supported by utilizing high conductivity of MXene and structural collapse of the MoS2 is relieved, and TiO2 enhances cycle stability, is designed for a negative electrode of an alkaline ion battery and shows good cycle performance. MXene is obtained by etching an MAX phase with mixed acid, the composite material is prepared by combining freeze drying and calcination, NH prevents MXene from stacking and expands interlayer spacing, MoS2 is formed after calcination, and a small amount of TiO2 is generated in situ. And the single-layer MXene is used as a binder to replace a traditional material, so that the electrochemical performance of the composite electrode is improved.

The invention discloses a large-lamellar MXene material as well as a preparation method and application thereof. The preparation method comprises the following steps: carrying out etching treatment on an MAX phase material by using an etching agent to obtain a multi-layer MXene material; and dispersing the multi-layer MXene material in a dispersion medium, and carrying out mechanical stress shear stripping to obtain the large-lamellar MXene material. According to the preparation method provided by the invention, the large-lamellar MXene material with the average transverse size of 4.2 microns or above can be obtained through high-yield stripping, the product quality is high, the yield is high, and industrial batch production is facilitated; the MXene film obtained based on the large-lamellar MXene material has good electromagnetic shielding capability and can be widely applied to the field of electromagnetic absorption shielding.

The invention relates to a preparation method of an MAX phase material. According to the specific technical scheme, precursor powder materials needed for preparing the MAX phase material are mixed to obtain mixed powder, the mixed powder is subjected to mechanical ball milling and cold press forming to form a blank, a to-be-sintered blank is obtained, the to-be-sintered blank is subjected to ultra-fast Joule hot sintering, and the MAX phase material is prepared. The MAX phase material is prepared by using an ultra-fast Joule thermal sintering method, the Joule thermal sintering method has the characteristics of high heating and cooling rate (104 DEG C / min) and high heating temperature (3000 DEG C), and according to the Arrhenius formula, the synthesis rate of the MAX phase material can be greatly improved due to the characteristics of high heating and cooling rate and high heating temperature, and rapid preparation of the MAX phase material is realized. According to the method, the preparation period of the MAX phase material can be greatly shortened, so that the aging can be improved, the energy consumption can be reduced, accurate and controllable preparation can be realized, and the method has important significance on low-cost and large-scale preparation of the MAX phase material.

The invention discloses a two-dimensional layered MXene nanosheet and a preparation method thereof, and belongs to the technical field of MXene preparation. The method comprises the following steps: (1) etching an MAX phase powder material by using hydrofluoric acid to obtain an etched MAX phase; (2) centrifuging and drying the etched MAX phase to obtain multi-layer MXene powder; (3) carrying out homogenization treatment on the multiple layers of MXene powder; and (4) carrying out rapid annealing treatment on the powder obtained after homogenization treatment to remove functional groups on the surface of MXene so as to prepare the MXene nanosheet with a regular structure and few defects. The method effectively avoids the oxidation problem of MXene, realizes feasible preparation with uniform thickness, stability, regular shape and fewer defects, and has the advantage of replacing an organic reagent intercalation preparation method to become a mainstream preparation method.

A hardened alloy composite material comprising an alloy matrix and reinforcing particles dispersed in the alloy matrix, the reinforcing particles having a shell and core structure, wherein the shell and the core have different chemical compositions, and wherein the reinforcing particles are formed by a MAX phase compound and / or a MAB phase compound.

The invention discloses a high-entropy MAX phase ceramic material and a preparation method and application thereof, the molecular formula of the high-entropy MAX phase ceramic material is M2AlC, and M is selected from at least four of Ti, Zr, Hf, Nb, Ta and V. The high-entropy MAX phase ceramic material is prepared by a vacuum hot pressing sintering method, on one hand, transfer of temperature and pressure is facilitated under vacuum hot pressing, the temperature and the pressure are more uniform and sufficient, the tissue structure of the prepared high-entropy MAX phase ceramic material sample is more compact and uniform, and the obtained performance is more excellent; and 2, oxidation during sample preparation can be prevented, and pollution of impurities to the sample is reduced, so that the sample with higher purity can be prepared.

The embodiment of the invention provides a nickel alloy surface composite coating and a preparation method thereof, and relates to the technical field of protective coatings, the nickel alloy surface composite coating comprises a Ta diffusion barrier layer prepared on the nickel alloy surface, and TiAlTa / (TiAlTa) xC1-x functional layers alternately arranged on the surface of the Ta diffusion barrier layer. The Ta diffusion barrier layer is adopted, so that excellent corrosion resistance is provided, corrosion of various corrosive media including strong acid, strong alkali and the like can be effectively resisted, the mutual diffusion effect of the nickel alloy and Ti, Al and other elements in the coating under the high-temperature condition is remarkably reduced, and the binding force of the coating and a base material is remarkably enhanced. The TiAlTa / (TiAlTa) xC1-x functional layers are alternately arranged, a formed multi-layer alternate structure can break the growth of penetrative columnar crystals and reduce the porosity, so that the corrosion resistance of the coating is improved, the surface layer (TiAlTa) xC1-x comprises various MAX phases and carbide phases, and the antifriction and wear-resistant effects and the corrosion resistance of the composite coating are improved.

Disclosed are a MAX-Ag conductive composite coating and a preparation method therefor. The conductive composite coating comprises a MAX phase and an Ag phase. The chemical formula of the MAX phase is Mn+1AXn, where M is a transition metal element, A is an Al element, X is a C or N element, and n is an integer ranging from 1 to 3. The MAX phase is of a strip-shaped structure, and the Ag phase is of a nanotwinned structure. The Ag phase aggregates at the grain boundaries of the MAX phase, and the conductive composite coating is of an Ag-wrapped MAX phase structure as a whole. In the present invention, the MAX phase coating is designed, by means of Ag doping, to have a heterogeneous grain shape. The doped Ag affects the growth of MAX phase grains, so that the MAX phase grains are of the strip-shaped structure. Furthermore, the doped Ag is of the nanotwinned structure, and fully wraps the MAX phase grains. Ag is continuously distributed at the MAX grain boundaries. Such a special structure may effectively reduce the scattering of electrons, provide a strong conductive path, and enable the coating to have excellent conductive properties.

The invention relates to a preparation method and application of an oxidation-resistant MXene material with a defect ordered hexagonal hole structure, and the preparation method comprises the following steps: mixing MAX phase Ti3AlC2 with hexagonal holes, CuCl2 and NaCl, loading into an alumina corundum square, covering with a NaCl salt bed boat, putting into a muffle furnace, and carrying out constant-temperature sintering at 820 DEG C in an air atmosphere for 3 hours; the method has the advantages that the process is simple and reasonable, a barrier for resisting attacks of oxygen molecules and water molecules is effectively constructed under the combined action of trace metal oxides on the surface of the MXene material, and the oxidation resistance of the MXene material is remarkably improved.

The present invention specifically relates to a copper-based powder metallurgy friction material containing a pretreated MAX phase and its application. The raw materials used in the present invention include pre-burned powder, copper powder, nickel powder, iron powder, tungsten powder, graphite powder, boron carbide powder, and zirconium oxide powder. The raw materials used in the pre-burned powder are composed of copper powder A and Ti2AlN in a mass ratio of copper powder A:Ti2AlN = 1-6:1. The material is prepared by a process of ball milling followed by pre-burning, wherein the ball milling speed is 100-200 r / min and the time is 12-28 hours; the pre-burning temperature is 500-900°C and the time is 140-160 minutes. The preparation method of the product of the present invention includes the preparation of pre-burned powder, mixing, pressing and sintering. The resulting product has high hardness, friction coefficient, friction stability coefficient, compressive strength, and shear strength, and has a low wear rate on the brake disc. The components of the present invention are rationally designed, the process is simple and controllable, and the resulting product has excellent performance and is easy to industrialize and apply.

The invention relates to the technical field of silica powder surface modification, in particular to a novel silica powder surface modification method and application of a composite material of the novel silica powder surface modification method. Silica powder surface modification comprises the steps that silica powder is subjected to surface chemical modification through a titanate coupling agent, active functional groups are introduced, and the interface bonding force between the silica powder and MXene is enhanced; high-quality preparation of MXene: etching an MAX phase by adopting hydrofluoric acid (HF) or lithium fluoride / hydrochloric acid (LiF / HCl), and obtaining few layers of MXene nanosheets through ultrasonic stripping to ensure high conductivity and large specific surface area; the modified silica powder and MXene dispersion liquid are uniformly mixed, MXene stacking is inhibited, the specific surface area is increased, and the ion transmission efficiency is improved; mXene nanosheets grow on the surface of the silica powder in situ to form a core-shell structure, so that the interface bonding strength and the mechanical property are enhanced; the composite material is applied to the fields of electromagnetic shielding, energy storage, flexible electronics and the like.

The invention discloses Si-based MAX phase powder and a preparation method thereof, and belongs to the technical field of ceramic material preparation. The preparation method of the Si-based MAX phase powder comprises the following steps: mixing a transition metal source, polysiloxane, a solvent, a curing agent and a platinum catalyst to obtain a mixed solution; the curing agent is vinyl modified siloxane; heating and curing the mixed solution to obtain a solid precursor; and crushing the solid precursor into powder, and then carrying out pressureless sintering in a protective atmosphere, thereby obtaining the product. According to the method, subsequent ball milling and other procedures are omitted, and impurity introduction to the product is avoided. According to the invention, the operation difficulty is greatly reduced, the production efficiency is improved, the energy consumption is reduced, and large-scale and low-cost production is realized.

The invention discloses a method for efficiently preparing MAX-phase metal carbonitride through microwave molten salt, and relates to the technical field of synthesis and preparation of new materials. The preparation method comprises the following steps: selecting several of M-site metal, A-site metal, AlN, a carbon material and inorganic salt according to a target product, carrying out one-step microwave molten salt heating to obtain a mixed product, washing the product with deionized water to remove the inorganic salt, and drying the solid product after washing to obtain the required MAX phase material. According to the method for efficiently preparing the MAX-phase metal carbonitride through microwave molten salt, the MAX-phase material with the controllable morphology structure is prepared, the morphology structure characteristics are obvious, the reaction is rapid, the method is simple and efficient, and industrial production is easy.

The invention discloses metal ceramic MAX-phase composite powder for spraying and a preparation method of the metal ceramic MAX-phase composite powder, and belongs to the field of metal ceramic composite materials. The method comprises the following steps: mixing Ni powder, Cr powder and Cr2AlC nano powder with deionized water, a binder and a dispersant according to a specific ratio, and carrying out wet ball milling to prepare uniform slurry; carrying out spray granulation to obtain primary spherical powder; and finally, carrying out spheroidizing treatment on the primary powder by adopting radio frequency plasma under the protection of inert gas to obtain a final product. The core of the preparation method is that through an optimized two-step process, many limitations in the application aspect of an existing MAX phase material are solved, and the composite powder which is high in sphericity degree, good in flowability, compact in interior and stable in MAX phase component is successfully prepared. The powder can be directly used for thermal spraying, and an ideal raw material is provided for preparing a high-performance MAX-phase metal ceramic coating.

The invention discloses a Ti-Nb-Zr / MAX phase / Cr-C-N multi-layer composite coating bipolar plate and a preparation method thereof. The multi-layer composite coating sequentially comprises a Ti-Nb-Zr alloy transition layer, an MAX phase middle layer and a Cr-C-N nano composite surface layer from inside to outside. According to the Ti-Nb-Zr / MAX phase / Cr-C-N multi-layer composite coating bipolar plate and the preparation method thereof, through the synergistic effect of the Ti-Nb-Zr alloy transition layer, the MAX phase middle layer and the Cr-C-N nano composite surface layer, the comprehensive optimization of the coating performance is realized: the Ti-Nb-Zr alloy transition layer provides excellent matrix adhesive force and stress buffer effect; the MAX-phase intermediate layer provides a main corrosion-resistant barrier and self-repairing capability; the Cr-C-N nano composite surface layer provides low contact resistance and good surface stability; and meanwhile, the interlayer stress is effectively reduced by utilizing the gradient transition region, the bonding strength and long-term stability of the coating are improved, and the comprehensive performance of the multi-layer composite coating bipolar plate is effectively improved.

The invention discloses a preparation method of a gas sensitive material, a gas sensor and a preparation method of the gas sensor, and relates to the field of sensors. The method comprises the following steps: mixing a hydrofluoric acid solution with an MAX phase material to prepare an MXene solution; the preparation method comprises the following steps: mixing a graphene oxide solution, a tungsten ion compound, ascorbic acid and an MXene solution, so that graphene oxide in the graphene oxide solution is reduced by the ascorbic acid, and an rGO / MXene / WO3 mixed solution is prepared; the rGO / MXene / WO3 mixed solution is subjected to a hydrothermal reaction, and the rGO / MXene / WO3 gas sensitive material is prepared. The invention aims to solve the problem that NO2 cannot be accurately and rapidly detected due to poor gas-sensitive performance of the existing gas-sensitive material.

The present invention provides a halogen-free MXene represented by the following formula (1), that has no halogen in its surface functional group by performing an etching process to generate MXene from a MAX Phase material, and after the etching process, performing an impurity removal treatment process of etching and removing impurities using a halogen-free etchant and a halogen-free post-treatment agent, respectively.Mn+1XnTx  [Formula 1]wherein, M is a transition metal element selected from the group consisting of Sc, Ti, V, Cr, Mn, Y, Zr, Nb, Mo, Hf, and Ta, X is at least one of carbon and nitrogen, and n is an integer from 1 to 4, and Tx is a functional group selected from the group consisting of oxygen, alkoxide of 1 to 5 carbon atoms, alkyl, carboxylate, hydroxide, hydride, oxide, sub-oxide, nitride, sub-nitride, sulfide, sulfonate, thiol, and epoxide.

The invention discloses a preparation method of an MXene reinforced Cu-based composite material with strong interface bonding, and belongs to the technical field of composite material preparation. According to the method, an MAX phase material is adopted, few layers of MXene are mixed with copper salt, and MXene with Cu or Cu2O single or mixed nano-particles uniformly deposited is formed; then mixing with copper powder or copper ions to obtain MXene / Cu composite powder; and finally, the MXene / Cu composite material with strong interface bonding is obtained through sintering. According to the preparation method, the spontaneous reduction deposition reaction of MXene with high reaction activity and Cu ions is utilized, and the structure and distribution of deposited nano-particles are subjected to interface regulation and control, so that tight interface combination between a copper matrix of the composite material and MXene is realized, inelastic scattering of carriers at an interface is reduced, the interface load transmission capacity is enhanced, and the mechanical property of the composite material is improved. Therefore, the strengthening efficiency of the MXene on the copper matrix is obviously improved; the prepared copper-based composite material has excellent mechanical and electrical properties, the yield strength of the copper-based composite material ranges from 295 MPa to 564 MPa, and the electric conductivity of the copper-based composite material is kept at 84.5%-94.5% IACS (International Annealed Copper Standard). The composite material is simple in preparation process and low in cost, and has the potential of large-scale industrialization.

A preparation method and application of a defect-ordered hexagonal pore structure antioxidant MXene material, comprising mixing hexagonal pore MAX phase Ti3AlC2 with CuCl2 and NaCl, loading into alumina corundum squares, and covering with a NaCl salt bed boat, placing the mixture in a muffle furnace, and sintering at a constant temperature of 820°C for 3 hours in an air atmosphere; after washing to remove impurities, the mixture is filtered, vacuum dried, and ground to obtain a defect-ordered hexagonal pore structure antioxidant. The advantages are: a simple and reasonable process, and under the joint action of trace amounts of metal oxides on the surface of the MXene material, an effective barrier against attacks by oxygen and water molecules is constructed, significantly improving the antioxidant properties of the MXene material.

A coated part includes a metallic substrate, a thermal barrier comprising a ceramic material and covering the metallic substrate, wherein the coated part further includes a protective coating covering the thermal barrier, the protective coating including, in a first region, a first MAX phase, denoted PZ2, of formula (ZrxTi1-x)2AlC or a first MAX phase, denoted PC2, of formula (CrxTi1-x)2AlC with x non-zero and less than or equal to 1 in the MAX phases PZ2 and PC2, and the protective coating includes, in a second region covering the first region, a second MAX phase of formula Ti2AlC.

The invention relates to a method for preparing a nitrogen-doped MXene / TiO2 material. The method can be used for preparing a novel flexible electrode two-dimensional nano material with excellent physical and chemical properties. The method comprises the following steps: firstly, etching an MAX phase ceramic material to remove an A atomic layer to obtain a multi-layer MXene material; then, layering the multiple layers of MXene by using a compound capable of ionizing ammonium ions, and increasing the subsequent nitrogen doping amount while layering; and finally, carrying out solvothermal reaction on a nitrogen-containing compound serving as a nitrogen source and single-layer or few-layer MXene to carry out nitrogen doping and controllably generate a small amount of uniformly distributed TiO2. The nitrogen-doped MXene / TiO2 prepared by the method has excellent electrochemical properties such as high specific surface area, high electrochemical activity and high conductivity, and can be applied to the energy storage fields such as supercapacitors and lithium ion batteries.

The invention discloses a self-lubricating high-wear-resistance coating and a preparation method thereof, and belongs to the technical field of coating protection. The coating provided by the invention comprises the following components in percentage by mass: 10 to 15 percent of MAX phase, 2 to 5 percent of fiber and the balance of TiO2, wherein the MAX phase comprises one of Ti2AlC, Ti3SiC2 and Cr2AlC. A coating with high wear resistance, good self-lubricating performance and excellent fracture toughness is prepared by optimizing a coating formula and combining the powder and a coating treatment method, and long-acting protection is formed on polycrystalline silicon powder conveying equipment and pipelines, so that the purity of a polycrystalline silicon product is further improved, and the service life of the equipment is prolonged.

The invention provides an MAX phase / alumina layered composite ceramic and an in-situ synthesis preparation method thereof, and the method comprises the following steps: respectively preparing an alumina matrix layer and an MAX phase interface layer through a tape casting method, then alternately laminating the alumina matrix layer and the MAX phase interface layer, and finally carrying out hot pressed sintering to obtain a layered composite ceramic product. According to the invention, the layered composite ceramic which takes aluminum oxide as a matrix and MAX-phase ceramic as an interlayer is prepared through an in-situ synthesis technology, so that the effects of great toughening, strength increase without reduction and high damage tolerance are realized, and the fracture mode is converted from brittle fracture of aluminum oxide ceramic to safe stepped fracture. The strength and toughness of the aluminum oxide ceramic are successfully balanced and synergistically improved, and the industrial problem that strength and toughness cannot be both considered in a traditional aluminum oxide ceramic toughening technology is solved.

The invention discloses a preparation method of a medium-entropy MAX phase based on zirconium component regulation and control, which comprises the following steps: 1) material preparation: titanium, vanadium, zirconium, niobium, aluminum and graphite powder are used as raw materials, and the molar ratio of the zirconium element phase in transition metal elements is 8-25%; and 2) sintering: uniformly mixing all the raw materials, and carrying out sintering reaction under the condition of argon Ar protective atmosphere to obtain the medium-entropy MAX phases with different configurations. The controllable preparation of the quaternary medium-entropy MAX phase with brand new element combination is realized by accurately regulating and controlling the molar ratio of the zirconium element in the (Ti, V, Zr, Nb) n + 1AlCn system, and the phase purity is obviously improved; and the medium-entropy MXene material is further prepared by taking the medium-entropy MAX phase as a precursor. The prepared medium-entropy MAX phase has a compact layered structure, and the derived medium-entropy MXene presents an ultrathin and stable two-dimensional lamellar morphology, so that the medium-entropy MXene shows abundant electrochemical active sites and excellent conductivity, and shows good application prospects in many fields.

The invention provides a nanometer Al3Ti reinforced aluminum-based composite material and a preparation method thereof, and relates to the technical field of aluminum-based composites.The preparation method comprises the following steps that MAX-phase ceramic particles and aluminum raw material powder are mixed and then subjected to first ball milling treatment, and first mixed powder is obtained; wherein the MAX phase ceramic particles are micron-sized ceramic particles; the first mixed powder is heated, the MAX phase reacts with Al to form A13Ti, and second mixed powder is obtained; the second mixed powder is subjected to second ball milling treatment, and third mixed powder is obtained; wherein the average particle size of A13Ti in the third mixed powder is nanoscale; and the third mixed powder is subjected to aftertreatment, and the nanometer Al3Ti reinforced aluminum matrix composite is obtained. According to the method, a nanometer strengthening phase is introduced into an aluminum matrix in a rough-to-fine mode, and the problem that when nanometer raw material powder is directly added, nanometer particles are agglomerated, and consequently the strength and plasticity of the composite material are poor is solved.

This invention discloses a coatable, moldable dual-functional coating material for heat protection and stealth, and its preparation method. The coating material is formed from a SiC-based composite ceramic aerogel slurry, a perovskite / MAX phase composite ceramic absorber, and a high-temperature resistant binder. The composite ceramic aerogel slurry is composed of SiC micro / nano-scale aerogel powder, SiC nanowires, and a high-temperature resistant binder; the perovskite ceramic absorber is lanthanum strontium manganese oxide (La). 1‑x Sr x MnO3), lanthanum strontium iron oxide (La) 1‑ x Sr x FeO3), lanthanum strontium cobalt oxide (La) 1‑x Sr x The MAX phase ceramic absorber is Ti3SiC2, and it contains substances such as CoO3. The technology of this invention enables the rapid application of coating materials to the surface of equipment via brushing, enhancing high-temperature radar absorption stealth and thermal protection capabilities, and facilitating the preparation and efficient repair of high-temperature stealth coatings.

This invention proposes a mullite composite brick, its preparation method, and its applications, belonging to the field of refractory materials technology. MXene is prepared by etching the MAX phase with hydrofluoric acid, and Si / Al oxide intercalated MXene is prepared by sol-gel reaction. After modification with polydopamine, intercalated montmorillonite is obtained by adding it to a sodium-based montmorillonite suspension. This intercalated montmorillonite is then uniformly mixed with a binder, high-alumina bauxite, and silicon carbide powder, machine-pressed, and calcined to obtain the mullite composite brick. The mullite composite brick prepared by this invention has good thermal insulation, heat insulation, refractory, and mechanical properties, excellent alkali resistance, improved bonding strength, and extended service life. It also has excellent thermal insulation effect, reduces heat loss, and thus plays a role in energy saving, showing broad application prospects.