215results about How to "Short sintering time" patented technology

A niobic acid potassium sodium system lead-free piezoelectric ceramic and its production are disclosed. The components of the niobic acid potassium sodium system lead-free piezoelectric ceramic are (1-n)KxNa1-xNbO3.nMH, it is prepared by SPS process. The production is carried out by grinding mixing raw materials, calcining synthesizing niobate, using SPS process for the obtained powdery material, annealing treating under oxygen atmosphere, and obtaining piezoelectric/ferroelectric ceramic materials. Its advantages include lead-free composition, good piezoelectric performance, low calcining temperature, short calcining time and fine tissue.

The invention relates to a flexible circuit conductive composition for a flexible printed circuit board (FPC), a preparation method and a using method thereof. The preparation method comprises the following steps of: adding photocurable resin and an optical activity monomer into a conductive nanometer material dispersion liquid and then preparing the composition by adopting a double-curing mode such as firstly photocuring and then thermal treatment. The photocuring leads the surface coating to be rapidly cured so as to achieve good mechanical property; and the thermal curing leads the coatingto be cured completely so as to reach the deep curing requirements. The thermal treatment leads nanometer metals to be sintered together so as to achieve good conductive performance. The prepared conductive system obtains a predesigned pattern in the specific area of a base material in a screen printing or nanometer impressing mode; the conductive pathway is obtained after the double curing and has the advantages of short curing time, low curing temperature, good electrical conductivity, high resolution ratio; and the prepared conductive film has the advantages of good adhesiveness, high hardness and good flexibility.

Aiming at the problems of low strength and low toughness of bioactive ceramics, the invention provides a method for strengthening and toughening a bioactive ceramic material by use of graphene and preparing graphene/biological ceramic artificial bone by a selective laser sintering (SLS) technology. The method has the advantages that graphene is added into the bioactive ceramic (hydroxylapatite, calcium phosphate, bioglass, calcium silicate and the like) as a nano enhanced phase, and the strength and toughness of the ceramic can be remarkably improved by use of the excellent mechanical property of graphene; the SLS technology is applied to the preparation process of graphene/biological ceramic artificial bone, and the sintering time can be shortened to the second level and even millisecond level by use of the characteristic of quick heating and cooling of laser so as to avoid structural injury of graphene caused by long-time high-temperature effect. The method for strengthening and toughening the ceramic material by use of graphene provided by the invention is of great significance to the application of bioactive ceramic to the load bearing parts of the human body.

The present invention relates to a preparation method of boron carbide ceramics. In particular, the preparation method comprises the following steps: first, boron powder and carbon powder are weighed and mixed with the molar ratio of boron and carbon equal to 0.5 to 22.5; secondly, the powder prepared in the first step is arranged in a die and transmitted to discharging plasma sintering equipment for sintering, and the temperature is raised to be between 1300 and 2200 DEG C under the vacuum conditions; thirdly, the die is taken out from the discharging plasma sintering equipment and cooled to be at the room temperature; then the die is drawn away and thus the final product is prepared. In the preparation method, the direct synthesis and densification of boron carbide are completed in one step; the powder is sintered under the vacuum conditions; and the prepared boron carbide ceramics has the advantages of high purity, variety in the ratio of boron and carbon, and high hardness.

The invention relates to a repairing mass for repairing in the converter production process of steel making and vanadium extracting of steel enterprises, in particular to a repairing mass used for a converter lining made of magnesia carbon bricks and a preparation method thereof, and provides a repairing mass having the advantages of short sintering time and long service life for meeting the requirement of production. The repairing mass per 100 weight parts comprises the following raw materials in parts by weight: 48-60 parts of fused magnesia, 22-28 parts of magnesite clinker, 10-16 parts ofmodified asphalt, 1-5 parts of metallic aluminum powder, 1-4 parts of ferric oxide powder and 2-10 parts of adhesive. The preparation method of the repairing mass is simple and convenient, i.e. all the raw materials are mixed. In the fettling production process of the vanadium extracting converter, when a local breakage appears on the converter lining, the repairing mass is coated on the part to be repaired; the repairing mass is sintered by utilizing the wall temperature of the converter, and production by blending with iron can be carried out after sintering; and under the conditions of lowsmelting temperature (1,360-1,400 DEG C) of the vanadium extracting converter and shorter smelting period (5-10 minutes), the repairing mass still can be quickly sintered with a working lining to form an organic combination with higher strength so as to prolong the service life of the repairing mass.

The invention relates to a method for producing potassium-calcium fertilizer by using potassium feldspar, limestone and phosphogypsum, and belongs to the technical fields of three-waste treatment and chemical engineering technical field. The method comprises that: the feldspar, the limestone and the phosphogypsum are mixed in certain proportion, subjected to grinding, ball forming or block forming and then baked in a rotary kiln, vertical kiln or tunnel kiln, and the sintered grog is crushed and packaged into products of the potassium-calcium fertilizer. One of main raw materials for producing the potassium-calcium fertilizer is industrial waste residue phosphogypsum, and the method has more advantages than the prior methods for producing the potassium-calcium fertilizer.

The invention discloses a high strength and toughness 3Y-TZP composite ceramic and a preparation method thereof. The 3Y-TZP composite ceramic consists of 3Y-TZP, a SiC crystal whisker and Sr2Nb2O7; and the preparation method of the 3Y-TZP composite ceramic comprises the steps of preparing and mixing Sr2Nb2O7 powder, ball milling, profiling, degumming and sintering. The composite ceramic is obtained by sintering the SiC crystal whisker and a Sr2Nb2O7 ferroelectric material second-phase addictive which are introduced into the 3Y-TZP. The ceramic material with high strength and toughness can be obtained by adjusting the contents of the SiC crystal whisker and the Sr2Nb2O7 and optimizing a microwave sintering process under the synergistic effect of reinforcing by the SiC crystal whisker and toughening by the Sr2Nb2O7 piezoelectric second phase. The invention has reasonable components and simple preparation process and simultaneously achieves the effects of strengthening and toughening by adopting a synergistic technology of reinforcing by the SiC crystal whisker and toughening by the Sr2Nb2O7 piezoelectric second phase. In addition, the invention is applicable for industrial production, effectively improves the mechanical property of the 3Y-TZP ceramic and widens the application field of the 3Y-TZP ceramic.

The invention relates to a plastic forming technique and a powder metallurgical technique, in particular to a nano crystal tungsten based alloy block material and a method for preparing the same. The block material comprises the following components in weight percentage: 86 to 88 percent of W, 6.5 to 7.5 percent of Ni, 2.5 to 3.5 percent of Fe, 2 to 4 percent of Mo and 1 to 2 percent of Co. The preparation method comprises the following steps: Fe-Co-Ni and W-Mo after dry mixing are ball milled in advance respectively until the Fe, Co and Ni completely form solid solution, and tungsten phase crystal grain is thinned to below 100nm; the Fe-Co-Ni and W-Mo are subjected to high energy ball milling until the Fe-Co-Ni is evenly distributed around the W-Mo crystal grain; and the discharge plasma rapid sintering is adopted. The nano crystal tungsten based alloy block material has the advantages of reasonable formula, even and thin microstructure, nearly full compact, higher hardness and tensile strength and good specific elongation, and the method for preparing the block material effectively improves the mechanical performances of the sintering material.

The invention belongs to the field of powder metallurgy sintering, in particular refers to a trace cobalt-containing tungsten carbide without bonding phase and preparation method thereof. A hard alloy comprises components, by weight, as follows: 0.20-1.00% of Co, 0.01-0.50% of Cr3C2, 0.01-0.50% of VC and the balance of WC with grain size of 0.2-0.8 mum. The preparation method comprises the steps of: carrying out feeding and high energy ball milling according to the above raw material powder ratio, until WC powder in the ball milling powder has an average grain size refined to less than 200nm; then sintering the cemented carbide powder rapidly after the high energy ball milling by discharge plasma. The tungsten carbide base cemented carbide powder of the invention has reasonably designed components and a simple preparation method; the powder gives out heat uniformly and has fast heating and cooling speed, low sintering temperature and short sintering time to save the energy greatly; and the obtained ultrafine-grained WC cemented carbide has excellent integrated properties.

The invention discloses a method for preparing a radioactive waste solidified body. The method is characterized by comprising the following steps of: finely grinding a raw material which comprises 9.53 to 29.41 weight percent of ZrSiO4, 23.36 to 32.12 weight percent of CaCO3, 31.07 to 38.46 weight percent of TiO2, 0 to 15.66 weight percent of Nd2O3, 0 to 29.09 weight percent of CeO2 and 0 to 3.97 weight percent of Al2O3; drying the raw material; and adding polyvinyl alcohol sol, granulating, screening, molding, discharging the sol, performing vacuum hot-pressing sintering, and thus obtaining the radioactive waste solidified body. By adoption of the method, the raw material is low in cost, a high-purity and high-density perovskite acorite and titanite combined mineral solidified body is prepared at low temperature by using a simple and practical hot-pressing sintering technology, and foundation is laid for engineering application to artificial rock solidification treatment of high-level waste.

The invention relates to a partial pressure sintering method for sintering a neodymium-iron-boron magnet. Certain inert gases Ar are filled into various deflation sections in the sintering process, the pressure of the Ar gases inside a furnace is regulated according to blank deflation velocity and vacuum pump system exhaust velocity through vacuum degree control, so that heating sintering is carried out by uniformly deflating under different partial pressures of the Ar gases, and negative pressure is still kept. The partial pressure sintering method disclosed by the invention ensures the consistency and uniformity of magnetic property and saves the sintering time.

The invention relates to a bismuth telluride based bulk nano crystalline thermoelectric material and preparation method thereof. The technical scheme includes that: firstly simple substance powder with mass percent more than 99.99% is taken as raw material, burdening is carried out according to the chemical formula (SbxBi1-x)2Te3 or Bi2(SeyTe1-y)3, wherein x is more than or equal to 0.75 and less than or equal to 0.85, y is more than or equal to 0.04 and less than or equal to 0.06, mixing to be uniform is carried out, and then ball milling is carried out by a ball mill, thus obtaining bismuth telluride base alloy nano powder; secondly, the bismuth telluride base alloy obtained in the first step is loaded into a graphite mould or ceramic mould to be sintered in a micro wave irradiation pressure sintering device; temperature rises to 300-550 DEG C by heating under the condition that the pressure applied to the powder is 10-40MPa, and then heat preservation is carried out for 10-60min under the condition that the pressure applied to the powder is 30-60MPa, thus obtaining the bismuth telluride based bulk nano crystalline thermoelectric material. The invention has the characteristics of less investment, low production cost, simple technology and short period; and the obtained bismuth telluride based bulk nano crystalline thermoelectric material has high performance.

The invention relates to a method for preparing titanium niobium zirconium tin biomedical titanium alloys by discharge plasma sintering, and belongs to the technical field of biomedical material preparation. The method provided by the invention comprises the following steps of: weighing Ti, Nb, Zr and Sn metal powders according to a chemical composition ratio, mixing the powders by a ball mill, putting into a graphite die, then placing into a discharge plasma sintering furnace, applying axial pressure of 10-40MPa, sintering in vacuum with the vacuum degree being 2-6 Pa while the heating rate is 50-100 DEG C/min and the sintering temperature is 950-1100 DEG C, keeping warm for 5-10 min after reaching the sintering temperature, and cooling in furnace to room temperature to obtain the titanium niobium zirconium tin biomedical titanium alloy material. The titanium niobium zirconium tin biomedical titanium alloys prepared by the method has uniform components and microstructure, high density (more than 98%), low elastic modulus (41-50GPa) and the like. In the mean while, the method provided by the invention has advantages of simple process, convenient operation and low cost, and is easy to realize industrial production.

The invention discloses a preparation method of microwave dielectric ceramics materials. The preparation method of the microwave dielectric ceramics materials comprises that the mixed powder of strontium carbonate, alumina, lanthanum oxide and titanium oxide are mechanically and evenly mixed in a spherical tank to form powder particles; and first time high energy ball milling is carried out on the powder particles to mill the powder particles evenly. The powder after the first time high energy ball milling is high-temperature calcined in a closed container to form precursor powder; and a second time high energy ball milling is carried out on the precursor powder to further mill the precursor powder evenly so as to form ceramic powder. The preparation method of the microwave dielectric ceramics materials sinters microwave dielectric ceramics materials with high densified mediation electric constant and a high quality factor by adopting low temperature, sintering temperature can be greatly lowered, sintering time can be greatly shortened, high densification is achieved, and therefore production cost and technical difficulty are reduced.

The invention discloses a method for preparing a high-compact ITO target material through two-step sintering. The method comprises the following steps: firstly manufacturing the raw material into a biscuit, keeping warm and degreasing under the air atmosphere, directly placing under the air atmosphere to warm to 800-1300 DEG C after the degreasing and keeping warm for 5-30 hours to perform the first step of pre-sintering; placing the pre-sintered green body on a sintering bearing plate, warming to 1500-1600 DEG C and keeping warm for 5-30 hours under the oxygen atmosphere so as to perform the second step of sintering; stopping introducing the oxygen 1-5 hours before finishing the sintering; and performing furnace cooling to obtain an ITO target sintering body. The pre-sintering is performed under the air atmosphere so that the sintering time of the oxygen atmosphere can be shortened, the production energy consumption is greatly lowered; the degreasing and the pre-sintering process are integrated so that the sintering total time is saved; the pre-sintering enables the particles in the green body to be further homogenized, the abnormal crystal grain growth is avoided, and the microscopic homogeneity of the target is improved, and the strength and the thermal shock resistance are improved; the prepared ITO target density reaches to 7.128g/cu.cm and more.

The invention discloses a connecting method for sintering/welding titanium-steel dissimilar metal. The differences of physical properties of the titanium and the steel which are dissimilar metal are large, and the titanium and the steel are hard to connect through conventional methods. According to the connecting method, firstly, the titanium or titanium alloy, V-Cu gradient alloy powder C1, C2 and C3 and stainless steel are placed in a die one by one to be pressed in advance, and secondly, the die is placed in a sintering device to be sintered in a spark plasma mode, wherein the V-Cu gradient alloy powder C1, C2 and C3 are composed of mixed powder which is formed by mixing a plurality of kinds of metal powder according to different proportions, and the expansion factor gradient of the V-Cu gradient alloy powder C1, the expansion factor gradient of the V-Cu gradient alloy powder C2 and the expansion factor gradient of the V-Cu gradient alloy powder C3 are matched with one another. The titanium or the titanium alloy and the stainless steel are directly connected and formed at a time in a sintering mode, the method of spark plasma sintering is particularly suitable for sintering molding of V-Cu gradient connectors of the titanium and the stainless steel, and a titanium-steel dissimilar metal sintering/welding connector can have a high mechanical property.

The invention discloses a method for preparing a machinable microcrystal glass material with high bioactivity, which comprises the steps of: preparing hydroxyapatite powder by using ammonium dihydrogen phosphate and calcium nitrate as raw materials; preparing fluorophlogopite powder by the melting-water quenching method; preparing 45S5 bioactive glass powder by the sol-gel method; uniformly mixing the three precursor powders and adding the polyvinyl alcohol used as a binding agent, compression moulding and then crystallizing and sintering to obtain the machinable microcrystal glass material with high bioactivity. The microcrystal glass prepared by the invention has good bioactivity, machinability and mechanical properties and performances can be realized by adjusting the ratio of the three precursor powders and are easy to control. With adoption of co-firing at low temperature, the invention greatly reduces the sintering temperature, shortens the sintering time and lowers the cost while ensuring that components are uniformly distributed at the same time.

A method for preparing a high-purity and high-density polycrystalline CeB6 cathode material pertains to the technical field of rare earth boride cathode materials. The existing preparation process of the CeB6 is complicated, and the obtained sample has low purity and poor density. The method comprises the following steps: cerium hydride nano-powder is prepared by a DC arc evaporation condensation process, then the cerium hydride nano-powder and boron powder are mixed by grinding in a hypoxia environment, and sintered in vacuum or a high-purity argon atmosphere by a discharge plasma sintering technology to obtain the polycrystalline CeB6 cathode material. The method has the advantages of simple process and low sintering temperature, and that the prepared cathode material has high purity, good density, high chemical purity and excellent emission performance.

The related microwave sintering method for piezoresistor comprises: selecting material as ZnO, Bi2O3, TiO2, Co2O3, Ni2O3, Mn (CO3)3 or MnO2; mixing material for blank to put into sintering bowl and together into the microwave furnace; then, heating as 5~50Deg/min till 1000~1300Deg; holding for 5~120min; cooling as 2~50Deg/min to 700~90Deg, and cooling to room temperature and obtain the final product. This invention has supper performance to traditional product, and fit to large-scale industrial production.

The invention relates to a graded ordered porous TiAg alloy preparation method, which belongs to the technical field of biomedical material preparation. Flat shuttle Ti powder and the Ag powder are weighed according to the required proportion and are ball-milled to acquire composite powder. Acquired Ti-Ag composite powder is mechanically pressed into a center bar blank. The center bar blank and a fixator are combined and placed into a graphite mold, and the surrounding is filled with spherical Ti powder of the equal height. Punches are added to the mold up and down. Placing into a discharge plasma sintering furnace is carried out. The system is vacuumized to 2 to 6 Pa. According to a step heating method, the blank is heated to the first level graded temperature 600 to 800 DEG C at the heating rate of 80 DEG C/min, and then heat preservation is carried out for 3 to 5min; the blank is heated to the second level graded temperature 800 to 1000 DEG C at the heating rate of 50 to 80 DEG C/min, and then heat preservation is carried out for 10 to 15min; and demolding is carried out to acquire graded ordered porous TiAg alloy. The graded ordered porous TiAg alloy prepared by the method provided by the invention has the characteristics of good antibacterial property, biological activity and high strength, and is especially suitable for human body hard tissue defects in biomedical engineering, such as artificial joint, artificial bone, dental implant and the like.

The invention provides a method for preparing a boron carbide ceramic material through low-temperature fast sintering. The method is characterized in comprising the following steps: a hard template is adopted as a structure-directing agent; porous boron carbide powder is synthesized with a nano-scale casting method; the porous boron carbide powder is added into a graphite mold, and the mold is placed into a chamber of a spark plasma sintering furnace; sintering is carried out under vacuum and in an inert or reductive atmosphere; after sintering, the product is cooled to room temperature with the furnace; and grinding is carried out, such that the boron carbide ceramic material is obtained. According to the low-temperature fast sintering boron carbide ceramic preparation method, the porous boron carbide powder is adopted as a sintering raw material. The porous boron carbide powder has the advantages of large specific surface area, high surface energy, good sintering activity, and the like, such that the powder is easier to be densified during sintering. Also, pressurization can be realized during a sintering process with a spark plasma sintering technology, such that pore collapse and densification of the porous boron carbide powder can be facilitated, and thus the boron carbide ceramic can be obtained under a relatively low temperature. The technology has advantages of fast temperature increasing speed, short sintering time, and the like. The method is an energy-saving and environment-friendly preparation method, and has good application prospect.

The invention discloses nanostructured lithium orthosilicate ceramic spheres used for tritium propagation and a preparation method thereof. The nanostructured lithium orthosilicate ceramic spheres are made by preparing precursor powder with uniform particle size through a solvothermal method, obtaining a lithium ceramic sphere blank with a uniform microstructure through wet moulding, and carrying out two-step sintering. The prepared lithium orthosilicate ceramics is high in purity, good in sphericility, small in hole size and uniform in hole dispersion, has a crystal grain size in nanometer order and allows the radiation resistance, mechanical properties and tritium release properties of tritium propagation ceramics to be improved at the same time.

The invention provides an oscillating hot press sintering furnace and relates to the field of high-performance ceramic and powder metallurgy material preparation, in particular to equipment adopting the hot press sintering method. The oscillating hot press sintering furnace comprises a furnace body and a hydraulic mechanism. An upper water cooling pressure head, an upper graphite pressure head, a lower water cooling pressure head and a lower graphite pressure head are arranged inside the furnace body. The hydraulic mechanism comprises an upper oil press and a lower oil press. The upper oil press is connected with the upper water cooling pressure head. The lower oil press is connected with the lower water cooling pressure head. The top of the upper water cooling pressure head and the bottom of the lower water cooling pressure head are provided with electromagnetic resonance pressure applying devices correspondingly. The electromagnetic resonance pressure applying devices can adjust the vibration frequency, vibration amplitude and pressure while hot press sintering is conducted. According to the oscillating hot press sintering furnace provided by the invention, high-frequency vibration amplitude/pressure can be achieved through the bidirectional pressurizing mode, the sintering time is shortened, energy consumption is reduced, and the compactness of a product is more uniform; and in addition, system faults can be found in time, and safe production is guaranteed.

A preparing method of a glass ceramic type solid electrolyte is disclosed. The chemical formula of the solid electrolyte is Li<1+x>Al<x>Ti<2-x>(PO4)3, wherein 0<=x<=0.5. The preparing method includes weighing Li<2>CO3, Al<2>O3, TiO2 and (NH4)<2>HPO4 powder according to a mass ratio, grinding each raw material, fully mixing the ground raw materials, adding the mixture to a crucible, heating the mixture to melt the mixture, performing water quenching to obtain glass splinters, grinding the glass splinters firstly, then subjecting the glass splinters to ball milling in a dry ball mill to obtain glass powder, adding the glass powder to a specific graphite die, and rapidly heating the glass powder under protection of an inert gas by utilizing high-intensity pulse current (assistant by an electric field) to crystallize the glass. The glass ceramic type solid electrolyte with excellent properties is prepared through controlling the heating rate, synthetic temperature, insulation temperature and other process parameters.

The invention discloses a method for preparing WC-Co hard alloy by rapid sintering under a multi-physics coupling action, which is characterized by comprising the steps of: evenly mixing powder of WC and Co, wherein the weight ratio of WC to Co is 84-94: 16-6; weighing and then filling into a mould; then, under the conditions that the heating speed is 15-100 DEG C/ s and the vacuum degree is less than or equal to 0.01Pa, electrifying the mould containing the WC-Co powder with alternating current for rapid heating, and applying 10-200MPa acting force to the two ends of the mould; under the continuous action of electric field and force field, carrying out instant electric heating impact for different times when temperature rises to 800-1000 DEG C; and finally, cutting off the power, cooling with air and taking out the product. The electric heating impact comprises the following steps: cooling from the sintering temperature to 400 DEG C at the cooling speed of 15-100 DEG C/ s and then heating to the sintering temperature at the heating speed of 15-100 DEG C/ s; wherein the circulation time(s) is/ are 1-10 time(s). The method simplifies the technological process, is rapid, efficient, energy-saving and environment-friendly, improves the quality of the hard alloy and is capable of replacing the existing preparation method of the hard alloy.

A process for preparing high-purity Ti-Al-C block by discharge plasma sintering includes such steps as proportionally mixing Ti3AlC2 powder or Ti powder, Al4C3 powder and active carbon powder, ball grinding, baking sieving, loading in graphite mould, discharging plasma sinter under protection of inertial gas, holding the temp for a certain time and cooling. Its advantages are high purity (90% or more) and high mechanical performance.

The invention discloses a mullite fiber preparation method which is efficient, rapid, environment-friendly and low in cost. The method includes: taking raw materials according to stoichiometric ratio of elements in the mullite fiber chemical formula, preparing colloid, performing fiber forming and drying for colloid discharging to obtain mullite non-crystal fiber, adding the fiber into a sagger made of wave permeable materials, placing the sagger in a special microwave oven, controlling heating rate by adjusting the microwave power under the air or oxygen atmosphere, heating to a heat treatment temperature, and cooling to the room temperature to obtain the mullite fiber. The mullite fiber prepared by the method is high in impurity and low in porosity, the grain size is about 30nm, and the fiber diameter ranges from 6 micrometers to 10 micrometers. Further, the mullite fiber is excellent in uniformity, brittle fracture and chalking of the fiber are greatly reduced, yield is increased, heat treatment temperature is lowered, heat insulation time is shortened, and production efficiency is greatly improved.

The invention discloses a self-grinding diamond tool matrix material. The self-grinding diamond tool matrix material comprises the following components in percentage by weight: 91 to 99.5 percent of FAM cobalt-substitute pre-alloy powder and 0.5 to 9 percent of a grinding material; the FAM cobalt-substitute pre-alloy powder comprises the following components in percentage by weight: 25 to 50 percent of electrolytic fernico powder with a nano cellular structure, 40 to 60 percent of copper-iron alloy powder, and 10 to 30 percent of copper-tin alloy powder. The self-grinding diamond tool matrix material has the following characteristics: firstly, through the adoption of the ultrafine FAM cobalt-substitute pre-alloy powder in the matrix, the holding force of the matrix on a diamond can be increased, and the function of each diamond can be performed fully; meanwhile, the sintering temperature can be lowered, so as to reduce damage of high temperature to the diamond and reduce the production cost; secondly, through the addition of ordinary grinding materials such as alumina, silicon carbide, quartz sand or cooked mica into the matrix, the matrix has a self-grinding or self-weakening effect, but the holding force of the matrix on the diamond is not influenced, so as to achieve relatively-great diamond protrusion height.

The invention belongs to the field of rare-earth permanent magnetic materials and particularly provides a method for preparing high-density and fine-grain sintered Nd-Fe-B. The production method comprises the following steps: smelting and casting master alloy to make a rapid hardening thin band, grinding powder by hydrogen pulverizing gas flow, sintering and densifying under hot isostatic pressure after oriented molding, and finally carrying out tempering treatment to obtain a product. In the invention, through the application of gas pressure which is not lower than 0.5MPa in the sintering process, not only is the density of the magnet increased, the sintering temperature and the sintering time can also be lowered and shortened; and as a result, grains are obviously refined, and the distribution of Nd-rich phases among the grains is more uniform, so that the remanence and the coercivity of the magnet are improved, and the comprehensive performance is obviously improved.

The invention discloses a high-speed and high-efficiency diamond grinding wheel as well as a preparation method and a usage method thereof. The diamond grinding wheel comprises a base body and a working layer, wherein the working layer comprises raw materials in percentage by mass as follows: 75%-93% of metal and ceramic composite binding agent powder and 7%-25% of diamond. The metal and ceramic composite binding agent powder is prepared from 65%-80% of pre-alloy powder and 20%-35% of glass-ceramic binding agent powder. When the grinding wheel is applied to a glass edge grinding machine, a combined grinding wheel comprising a fine grinding wheel and a rough grinding wheel is mounted on each of two electrode spindles, two combined grinding wheels are mounted in a cross manner, and rough grinding and fine grinding are performed simultaneously. The diamond grinding wheel prepared with the method has the characteristics of stable performance, sharp grinding, low cost and the like; the traditional glass edge grinding and chamfering machining manner is changed, glass machining procedures are greatly simplified, and the glass machining efficiency and quality are improved.