35 results about "Acicular" patented technology

The invention relates to a quantitative measurement method for acicular ferrite of pipeline steel, which utilizes an electron backscattered diffraction (EBSD) assembled on a scanning electron microscope (SEM) to carry out quantitative measurement on the acicular ferrite of the pipeline steel and comprises the following steps: grinding the cross section of a pipeline steel sample into a metallographical polished surface; etching the polished surface with natal, eliminating surface stress and showing an acicular texture; utilizing a conductive adhesive to fix the prepared sample on an EBSD sample stage; controlling the sample stage to rotate for 70 degrees by utilizing the SEM; vacuumizing an electron microscope sample chamber; when the vacuum degree reaches the electron microscope operating requirements, applying operational high pressure to acquiring an image, and finding a typical viewing field; stretching the probe of the EBSD into the sample chamber, and acquiring EBSD pattern data; and carrying out statistical treatment on the EBSD pattern data to obtain the effective crystallite dimension of the acicular ferrite texture. The invention is applied to the quantitative measurement of the acicular ferrite texture with unsharp boundaries in the pipeline steel.

The invention discloses a method for rapidly measuring and finely classifying full-form crystal grains of a steel material. The method comprises the following steps: performing the operations of filtering, denoising, gray level correcting and binary segmentation treatment on an original image in sequence, and reducing a target crystal grain binary image; setting a scale for the reduced image, performing area calibration on target crystal grains respectively, and respectively extracting form characteristic parameters of each target crystal grain, wherein the form characteristic parameters include the area, the circumference, the grain size, the length-width ratio, the circularity degree, the form coefficient and the transgranular polar angle; distinguishing equiaxial crystal grains from non-equiaxial crystal grains according to a primary threshold of the circularity degree and a primary threshold of the form coefficient; distinguishing circular-like and polygon crystal grains from the equiaxial crystal grains according to a secondary threshold of the circularity degree and a secondary threshold of the form coefficient; and identifying strip-like and strip crystal grains and thick needle and small needle shaped crystal grains from the non-equiaxial crystal grains according to the length-width ratio and primary and secondary thresholds of the transgranular polar angle. The method is high in measurement precision, and the efficient and precise method is provided for rapid and fine microanalysis on the full-form crystal grains of the steel material.

The invention belongs to the field of selective laser melting forming, and particularly discloses a heat treatment method for obtaining a tri-state structure in an SLM forming titanium alloy. According to the heat treatment method, through multiple heat treatment of three stages of different temperature intervals, SLM forming near alpha and alpha + beta titanium alloy structures are adjusted, the original needle-like martensite structure (the forming direction is thick and large isometric crystals, the vertical forming direction is thick and large columnar crystals, the isometric crystals and the columnar crystals are internally provided with needle-like martensite, and a large number of twin crystals are included) is converted into the tri-state structure, the characteristic that the SLM forming near alpha and alpha + beta titanium alloy plasticity is poor is improved, and the tensile mechanical property with the strength and plasticity well matched is obtained.

Disclosed are a low-shrinkage, high-strength, and large ceramic plate and a manufacturing method thereof. The method comprises the following steps: (1) preparing a ceramic raw material powder; (2) subjecting an acicular wollastonite to surface coating with a silane coupling agent and to pre-dispersion with a fumed silica to obtain a pre-treated acicular wollastonite; and (3) thoroughly mixing the ceramic raw material powder and the pre-treated acicular wollastonite and granulating the resulting mixture, the amount of the pre-treated acicular wollastonite added being 10 wt % to 30 wt % of the ceramic raw material powder, and subjecting the resulting granules to dry pressing and sintering to obtain the large ceramic plate. The acicular wollastonite is incorporated into the manufacturing of the large ceramic plate to take full advantage of the reinforcing effect and low sintering shrinkage characteristics of the acicular wollastonite. The invention reduces sintering shrinkage and increases product strength.

The invention provides methods of modifying the crystal habit of a compound without altering the crystal structure of the compound through a controlled precipitation technique in the presence of a crystal growth inhibitor as well as the crystallized compounds formed by these methods. Using these methods, the crystal habit of the compound may be modified from acicular to bipyramidal. The modification in crystal habit is attributable to a preferential adsorption mechanism of the crystal growth inhibitor to a fast growing crystal face of the compound. Powder flow properties of the crystallized product are significantly enhanced with the habit modification. This selective crystal habit modification using a crystal growth inhibitor provides a strategy to circumvent the manufacturing difficulties associated with acicular crystal habits, and may increase the manufacturing capability of supercritical fluid based crystallization and precipitation technologies.

The invention provides a preparation method of boron carbide powder for grinding liquid. The preparation method comprises the following steps: (1) preparing a boron carbide raw material with the weight purity of 95 percent to 99 percent, wherein the volume percent ratio of needle-shaped crystals to flat crystals is smaller than or equal to 1 percent; (2) crushing the boron carbide raw material to obtain crushed boron carbide materials; (3) carrying out first-grade wind power grading and second-grade vibration sieving or carrying out primary vibration sieving, second-grade sedimentation and water selection, and second-grade drying to obtain a low-grade grinding material of the boron carbide powder for the grinding liquid; or carrying out multi-grade sieving and water selection to obtain high-grade micro-powder of the boron carbide powder for the grinding liquid. When the product prepared by the method is prepared into the grinding liquid for grinding, the grinding speed is rapid, and the flatness of a ground surface is high, so that the grinding cost of the product is greatly reduced.

The invention discloses a Ti-Al-Nb-based composite material and a preparation method thereof, the material comprises a Ti-Al-Nb alloy matrix and 1.5%-10% by volume of TiB whiskers, the matrix comprises 18-25 at% of Al, 12-27 at% of Nb and the balance Ti, the structure form of the matrix is that a needle-shaped O phase is distributed in a deformed non-equiaxial B2 phase matrix, and the average value of the ratio of the long axis to the short axis of B2 crystal grains is larger than or equal to 1.5; the TiB crystal whiskers are distributed at the B2 phase crystal boundary in a complete and unbroken form, are connected with B2 crystal grains on the two sides in a pin type structure, and pin the B2 phase crystal boundary. The matrix alloy of the composite material is deformed and has streamline characteristics; the reinforcement TiB whisker is complete, free of fracture and uniform in distribution; the TiB crystal whiskers with the high length-diameter ratio effectively pin a deformation matrix grain boundary, so that the grain boundary pinning strengthening effect and the intragranular deformation strengthening effect have a synergistic effect, and the thermal strength performance of the material is greatly improved.

The invention relates to a method for preparing acicular acetaminophen crystal by a time domain shaped femtosecond laser, and belongs to the field of preparation of pharmaceutical crystal materials. The method comprises the following steps: (1) preparing a supersaturated solution of acetaminophen by using a heating device; (2) using a femtosecond laser irradiation method to enable the acetaminophen supersaturated solution to be ionized to generate cavitation bubbles and generate acicular acetaminophen crystal as the bubbles rupture; and (3) drying filtered acicular acetaminophen crystal by using a heating device. The method for preparing the acicular paracetamol crystal provided by the invention is carried out under normal temperature and normal pressure without any addition in the production, the manufacturing time is short, the ratio of the acetaminophen crystal is high, and the size is controllable.

The invention provides a thermal treatment process for X12CrMoWVNbN10-1-1 grain refinement. According to the thermal treatment process, the amount of acicular austenite is decreased as much as possible by increasing the heating speed, and the amount of spherical austenite is increased, so that grain refinement is achieved, the grain size can meet the technical requirement, and the using range of X12CrMoWVNbN10-1-1 is enlarged. Fed materials are forged into workpieces, the workpieces are sequentially subjected to high-temperature normalizing, high-temperature tempering, conventional normalizingand high-temperature tempering, and then the workpiece subjected to high-temperature tempering are subjected to subsequent processing treatment. In the high-temperature normalizing process, the temperature increasing speed of the workpieces in an alpha and gamma two-stage region is increased, the workpieces can pass through the two-stage region rapidly, and the spherical austenite can be obtainedas much as possible. On one hand, the orientation relationship of crystallography is broken through to a greater extent, namely, the K--S relationship; and on the other hand, the nucleation rate of the austenite can be increased by increasing the heating speed. The high-temperature tempering process particularly comprises the steps that heat preservation is conducted for 15-20 h at the environmental temperature of 700 DEG C to enable carbides to be dissolved as many as possible to further destroy the orientation relationship of metallography, and then air cooling is conducted.

The invention discloses a fluxing agent for crystal growth and a crystal growth method. The crystal is Pb17O8Cl18, and a system of the fluxing agent comprises at least one of PbO, metal halide M'X, metal halide M''X2 and Bi2O3; wherein M' is Li, Na or K, M'' is Mg, Ca, Ba, Sr or Pb, and X is F or Cl. The crystal growth method comprises the following steps: mixing and melting a polycrystalline rawmaterial and the fluxing agent; starting seeding above a melt temperature saturation point, stabilizing the melt temperature at the saturation point, and starting crystal growth; and growing the crystal to a required size, lifting the seed rod crystal to be separated from the liquid level, and carrying out annealing treatment in a weak oxidizing atmosphere. According to the method, the crystal growth orientation is fully considered, the crystal growth stability is effectively improved, the solution volatilization and system viscosity in the growth process are reduced, the problems of needle-like growth of the crystal, easy cracking and color change of the grown crystal and the like are solved, and the grown crystal is large in size and high in optical quality.

The invention provides pyroxasulfone metastable-state and stable-state crystal forms, a preparation method and application, the preparation method comprises the following steps: step 1, stirring and heating pyroxasulfone in a first compound solvent to completely dissolve solids, cooling and crystallizing, filtering and drying to obtain white fine-needle-shaped crystals, namely the metastable-state fine-needle-shaped crystal form A; and 2, mixing the metastable-state fine-needle-shaped crystal form A and a second compound solvent in a pressure kettle, pressurizing in an inert gas atmosphere, keeping the temperature and pressure, keeping the reaction kettle sealed, reacting, cooling, crystallizing, relieving the pressure, filtering and drying to obtain a semitransparent columnar crystal B, namely the stable-state columnar crystal form B. The invention also discloses a preparation method of the stable-state fine-needle-shaped crystal form B. The stable-state fine-needle-shaped crystal form B is prepared from the metastable-state fine-needle-shaped crystal form A and the stable-state columnar crystal form B. The crystal form B subjected to high-temperature, high-pressure and high-supersaturation-degree treatment is a stable-state crystal form, so that the crystal form B is better in stability, lower in hygroscopicity and convenient to store, and single-dosage-form or compound-dosage-form wettable powder, water dispersible granules and other solid preparations prepared from the crystal form B are good in stability and good in pesticide effect and have very high practical value for industrial production, popularization and application of pyroxasulfone.

The invention discloses a welding joint of low-alloy and ultrahigh-strength steel. The welding joint is characterized in that the welding joint structure comprises acicular martensite and strip-shapedbainite, the volume percent of the acicular martensite is 70-80%, and the volume percent of the strip-shaped bainite is 20-30%. The invention further discloses a welding method forming the welding joint. Compared with the prior art, the complex-phase welding joint can meet the using requirements for high strength and high toughness of a welding joint piece of a low-alloy and ultrahigh-strength steel medium-thick plate, and meanwhile is easy to operate, high in welding efficiency and easy to apply and popularize.

A steel sheet having a prescribed chemical composition, the steel sheet having a metallographic structure in the center of the sheet thickness comprising, in area%, 0-80% of polygonal ferrite; the present invention relates to a steel sheet having an effective crystal grain size of 15.0 [mu] m or less, and one or two elements selected from acicular ferrite and bainite, the remainder being an M-A phase, the steel sheet having an effective crystal grain size of 15.0 [mu] m or less, the metallographic structure in a surface layer, which is a range from the surface to 1.0 mm in the thickness direction, containing 95% or more in total in area% of one or two elements selected from acicular ferrite and bainite, and the remainder being an M-A phase, the steel sheet having an effective crystal grain size of 15.0 [mu] m or less, and the steel sheet having an effective crystal grain size of 15.0 [mu] m or less. The surface layer has a maximum hardness of 250 HV0.1 or less.

A lead frame includes, as an outermost plating layer, a roughened silver plating layer having acicular projections and covering only top faces on the upper surface side of a lead frame substrate made of a copper-based material. The roughened silver plating layer has a crystal structure in which the crystal direction <101> occupies a largest proportion among the crystal directions <001>, <111>, and <101>. The lead frame can be manufactured with improved productivity owing to reduction in cost and operation time, and achieves remarkably high adhesion to sealing resin while keeping the total thickness of plating layers including the silver plating layer to be thin.

The invention belongs to the field of steel smelting continuous casting, and relates to an experimental method capable of controlling uniform crystal phase and eliminating needle crystal. According tothe experimental method, after protective slag is directly melted at the two ends of thermocouples by means of a thermocouple double-wire technology, a uniform and consistent environment of the crystallization temperature of the protective slag is created by controlling the same temperature of the thermocouples at the two ends and setting the same hearth temperature so that in the crystal solidification process of the liquid protective slag, the uniform crystal phase can be obtained and needle crystal can be eliminated. According to the experimental method, the process of crystallizing the protective slag from high temperature to low temperature in the continuous casting process in a factory is simulated, and is more like the actual production process, the obtained experimental data is more convincing, compared with the method for obtaining the crystal phase by re-rising the temperature of the glass slag obtained by quenching the molten protective slag, the experimental method has theadvantages that the experimental operation time is short, the steps are simple and convenient, the workload is smaller, and the obtained product has no needle crystal and the like.