33results about How to "Stable phase structure" patented technology

The invention discloses a microwave dielectric ceramic, a temperature frequency characteristic regulator of the microwave medium ceramic and an LTCC material thereof. The microwave dielectric ceramic comprises a principal crystalline phase. The chemical formula of the principal crystalline phase is BaSixO2(x+1)(x is greater than or equal to 1.56 but less than or equal to 1.85). The ceramic has a low dielectric constant (epsilon r is equal to 7.1-7.9), a relatively high quality factor (Q*f is equal to 10973-20350GHz) and a relatively wide sintering temperature (750-1250 DEG C). Meanwhile, the principle crystalline phase which is sintered in a reductive atmosphere N2-1vol%H2 still has an excellent microwave dielectric property and is the microwave dielectric material with good reduction resistance. The microwave dielectric material can be used as the temperature frequency characteristic regulator of the microwave medium ceramic and can keep a stable phase structure and a good microwave dielectric property (reduction resistance) in the reductive atmosphere. Compared with a conventional adjustor, the microwave dielectric ceramic has an obvious advantage and is a novel temperature frequency characteristic regulator which can be applied to BME-MLCC.

The invention relates to a Sb-Te-W phase-change target material for phase-change storage and a preparation method thereof. The Sb-Te-W phase-change target material has a general chemical formula of SbxTeyW1-x-y, and in the general chemical formula, x is >0 and <1, y is >0 and <1, the sum of x and y is <1, x / y is >=0.67 and <=4 and a mass fraction of W is <=10%. An intermediate compound is synthesized by a sheath seal vacuum melting synthesis technology and the Sb-Te-W phase-change target material is prepared by a bidirectional compaction vacuum hot-pressing sintering technology. The preparation method can effectively solve the problem that in alloy melting, material components are nonuniform because of difference of component melting points and densities, and can produce the Sb-Te-W phase-change target material having high density, high stability and high purity. Compared with the existing Ge2Sb2Te5 materials used widely, the Sb-Te-W phase-change target material has a high crystallization temperature and a low melting point and has good heat stability and good data retention when being used as a phase-change storage material.

The present invention relates to the technical field of powder metallurgy preparation of refractory metal materials; specifically discloses a method for preparing powder metallurgy refractory multi-principal element high-entropy alloys, which specifically includes the following steps: Step S1: refractory metal element powder is passed through a 300-mesh sieve, and The multi-element powder mixing method is mixed to obtain a mixed material; the mixed material is at least four elements of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W; the atoms occupied by each element in the mixed material Percentages are 5%‑35%; total percentages are 100%. Step S2: Press forming to obtain a compact; Step S3: Vacuum high-temperature solid-phase sintering to obtain a sintered block. The invention has the advantages of easy composition control, high production efficiency, and near-net shape, and the prepared powder metallurgy refractory multi-principal element high-entropy alloy has relatively stable structure and performance, low cost, and is more suitable for high-performance powder metallurgy refractory alloys. There will be significant advantages in the research and development of principal element high-entropy alloys and the flexible mass production of multi-shape products.

The invention discloses a preparation method of a composite ceramic powder material used for an environmental barrier coating. The composite ceramic powder is composed of single phase BSAS (1-xBaO-xSrO-Al2O3-2SiO2, x is more than 0 and less than 1). The obtained BSAS composite ceramic powder has the advantages of easiness for ingredient control, high purity, high crystallinity and low synthesis temperature. The composite ceramic powder can be used for plasma spraying after being subjected to ball milling, agglomeration, pelletizing and high-temperature heat treatment, so that the environmental barrier coating is prepared on the surface of a C / C-SiC composite material, the coating can be used for effectively improving high-temperature water oxygen corrosion resistance performance of a C / C-SiC matrix, is applicable to surface high-temperature protection of other silicon substrate materials, can be used for solving the problem of high-temperature water oxygen corrosion of a silicon substrate composite material and has an important application value.

The invention belongs to the technical field of metal oxide coatings and discloses a method for low-temperature reactive sputtering deposition of a nanometer alpha-Al2O3 coating. The method comprisesthe following steps: manufacturing Al powder and alpha-Al2O3 powder into a composite material through a powder metallurgy method; after cutting the composite material to reach the size required for equipment, mounting the composite material of the required size on a target station for radio frequency magnetron sputtering as a deposition target material, and mounting a workpiece substrate on a sample table in a deposition cavity; after removing residual steam in the deposition cavity, vacuumizing to achieve base pressure, and then injecting a gas mixture of Ar and O2 for pre-oxidation treatment; and adjusting the partial pressure of O2 in the gas mixture of Ar and O2 to reach the range of 15% to 25%, adjusting the temperature of the workpiece substrate to reach the range of 550 DEG C to 750DEG C, starting a radio frequency magnetron sputtering film coating system, and starting reactive deposition so as to obtain the nanometer alpha-Al2O3 coating. The nanometer alpha-Al2O3 coating obtained through the method disclosed by the invention is of a nanocrystalline structure, is high in toughness, can be firmly combined with the workpiece substrate, and has a stable alpha-phase structure at relatively low temperature.

The invention relates to a preparation method of yttrium silicate ceramic powder, in particular relates to a preparation method of yttrium silicate ceramic powder for environment barrier coating, and belongs to the technical field of oxide ceramic material preparation. The method comprises the following steps: using a yttrium solution with Y<3+> ion concentration of 0.6-1.5 mol / L as solution A; weighing silicate ester according to a molar ratio of Y to Si being 2: 1; adding alcohol and water in the weighed silicate ester according to a volume ratio of the silicate ester to alcohol to water being 1: 1-2: 2-6 to obtain solution B; uniformly mixing the solutions A and B solution to obtain the mixed solution containing aluminum and silicon; adding the mixed solution containing aluminum and silicon into ammonium hydroxide with pH value of 9-10 at a speed of dropwise adding 0.2-0.5 L of the mixed solution containing aluminum and silicon in 1L of precipitator every minute, and stirring to obtain the co-precipitate; after the reaction is finished, standing, filtering, washing and drying the residue, calcining for at least 4 hours at 800-1000 DEG.C to obtain the Y2SiO5 ceramic composite powder. The method provided by the invention is short in reaction period and good in repeatability; and the obtained product is high in purity and is of a single crystal form.

The invention discloses a preparation process of a zirconium alloy surface high-temperature oxidization resistant ZrNx / (ZrAlFe)N / (ZrAlFeM)N composite gradient coating, wherein M is any two kinds of elements in Ti, V and Nb. The concrete process comprises the steps of substrate pretreatment, target material cleaning, ZrNx / (ZrAlFe)N / (ZrAlFeM)N composite coating deposition and the like. The compositecoating preparation is performed in two steps; in the first step, a ZrNx / (ZrAlFe)N gradient transition layer is prepared; firstly, a Zr coating is deposited for 3min on the substrate; then, N2 is gradually introduced at the flow from 0sccm to 6sccm for depositing ZrNx, wherein the flow rate of N2 is 2sccm / min; then, continuous transition is performed to (ZrAlFe)N; in the second step, a (ZrAlFeM)Nmulti-component nitride layer is prepared. In the decomposed (ZrAlFe)N transition layer, the Zr element atom content is in gradient change from 100 at percent to 30 at percent in the thickness direction; the Al and Fe element atom contents are in gradient change from 0 at percent to 35 at percent in the thickness direction; the Zr, Al, Fe and M element atom contents in the decomposed (ZrAlFeM)N multi-component nitride layer are between 10 at percent and 35 at percent; the N element atom content is between 5 at percent and 20 at percent. The process has the characteristics that through the design of a structure with the coating in the gradient change state, the residue stress in the coating can be relieved; the high-temperature oxidization resistance performance is realized; the mechanicalproperty is excellent, and the like.

The invention discloses a method for preparing a high-strength toughness high-entropy alloy, which relates to the technical field of alloy material production; the specific steps are: configuring Mn with an atomic percentage of 27-30%, Co with 8-12%, Cr with 8-12% and 0.4 ~1.3% C, the rest is high-entropy alloy powder of Fe; the high-entropy alloy powder is ball-milled, and then pre-pressed, the pressure is 300-500MPa, and the pressure is maintained for 200-300s to obtain a pre-pressed block of the high-entropy alloy; The pre-pressed block is vacuum annealed, vacuum hot-pressed and sintered, and then cold-rolled and deformed; the cold-rolled and deformed high-entropy alloy sheet is subjected to a restricted carbon distribution treatment at 400-550 ° C to diffuse free carbon elements; the present invention prepares a compound containing The non-isoatomic FeMnCoCrC high-entropy alloy of C has excellent strength and plastic bonding, and at the same time improves the problem of uneven composition and unstable structure of the high-entropy alloy prepared by the traditional process.

The invention discloses rare earth surface modified aluminum nitride powder and preparation method thereof, and relates to a modifying method of aluminum nitride powder. The rare earth surface modified aluminum nitride powder disclosed by the invention aims at solving the technical problems that the performance of a composite material using AlN as a reinforcement phase is influenced since impurity elements are introduced into the existing modified AlN powder and the modified AlN power and the metal are non-wetting. The rare earth surface modified aluminum nitride powder is aluminum nitride powder coated by rare earth oxide. The preparation method comprises the following steps: step one, preparing a rare earth nitrate solution; step two, adding the AlN powder in the rare earth nitrate solution, dropwise adding strong ammonia water while stirring, so as to obtain a mixed slurry; step three, filtering, washing and drying the mixed slurry; step four, sintering in a muffle furnace to obtain the rare earth surface modified aluminum nitride powder. The powder cannot be hydrolyzed after being soaked in water at 60 DEG.C for 30 hours, and the wetting angle of the powder and the copper at 1200 DEG.C is 85-89 DEG according to a sessile drop method, and the powder can be applied to a metal-based composite material as reinforcement.

The invention discloses a microwave dielectric ceramic, a microwave dielectric ceramic temperature-frequency characteristic regulator and an LTCC material thereof. The microwave dielectric ceramic includes a main crystal phase, and the chemical formula of the main crystal phase is BaSi x O 2x+1 (1.56≤x≤1.85). The ceramic has a low dielectric constant (ε r =7.1~7.9), high quality factor (Q×f=10973~20350GHz), wide sintering temperature (750℃~1250℃), and the main crystal phase in reducing atmosphere N 2 ‑1vol%H 2 After sintering, it still has excellent microwave dielectric properties. It is a microwave dielectric ceramic material with good reduction resistance. The microwave dielectric ceramic can be used as a temperature-frequency characteristic regulator of microwave dielectric ceramics. It can It maintains a stable phase structure and good microwave dielectric properties (reduction resistance), which has obvious advantages over traditional regulators. It is a new temperature-frequency characteristic regulator that can be applied to BME‑MLCC.

The invention belongs to the technical field of metal coatings and discloses a nano alpha-aluminum oxide / chromium oxide composite coating and a preparation method thereof. The preparation method comprises the steps that AlCr alloy serves as a deposition target material, and the deposition target material and a workpiece base body are installed on a high power pulsed magnetron sputtering target station and a deposition chamber sample platform correspondingly; after residual water vapor in a vacuum chamber is removed, the vacuum chamber is pumped to a base vacuum; the workpiece base body is heated to the required temperature, then mixed gas of Ar and O2 is injected, and pre-oxidation treatment is conducted; and the partial pressure of the O2 in the mixed gas of the Ar and the O2 is adjusted to be 6%-15%, the temperature of the workpiece base body is adjusted to be 480-700 DEG C, a high power pulsed magnetron sputtering film coating system is started, reaction and deposition are started, and the nano alpha-aluminum oxide / chromium oxide composite coating is obtained. The nano alpha-aluminum oxide / chromium oxide composite coating obtained through the preparation method is a nanocrystalline structure coating, good in toughness and firmly combined with the base body and has a stable alpha phase structure.