CHINA NATIONAL BUILDING MATERIAL GROUP CO., LTD. (Chine)
Inventeur(s)
Sun, Feng
Wang, Lu
Wang, Zaiyi
Huang, Xuebin
Dong, Tingxia
Zhang, Linlin
Ding, Hao
Xu, Jinmeng
Jiang, Zifei
Abrégé
The present application relates to the field of silicon nitride ceramics, and disclosed therein are silicon nitride ceramics and a preparation method therefor. The specific preparation method comprises: preparing a slurry; granulating the slurry, and then pressing same into silicon nitride ceramic ball biscuits; performing isostatic cool pressing on the ceramic ball biscuits after adhesive discharging; performing semi-sintering on the ceramic ball biscuits that have been subjected to isostatic cool pressing so as to obtain a semi-sintered blank; re-sintering the semi-sintered blank to obtain a sintered blank; and processing the sintered blank to obtain the silicon nitride ceramics. By combining a semi-sintering process and a semi-sintered blank re-sintering process in the present application, on the premise of ensuring the high performance of silicon nitride ceramics, the atmosphere sintering temperature and the temperature-holding time are reduced, the processing efficiency of silicon nitride ceramics is obviously improved, the preparation cost is reduced, and compared with a traditional sintering process, the process of semi-sintering and re-sintering has a more obvious improvement on the performance of silicon nitride ceramics, and provides a feasible solution for the low-cost and large-scale preparation of high-performance silicon nitride ceramics.
Provided in the present invention is a dynamic sintering method for a nitride ceramic substrate, which belongs to the technical field of ceramic materials. In the present invention, by means of the differences between a support block and a nitride ceramic substrate in the shrinkage starting temperature and the shrinkage rate, the shrinkage starting temperature of the support block is controlled to be lower than or higher than that of the nitride ceramic substrate, and the linear shrinkage rate thereof in a height direction is controlled to be higher than that of the nitride ceramic substrate, such that the dynamic process from non-contact to contact between a pressing plate and the substrate during the sintering process can be achieved; therefore, the deformation and cracking of the substrate during sintering are avoided.
The present invention relates to the technical field of silicon nitride ceramics, and provides a method for preparing silicon nitride ceramic granulated powder. In the present invention, a sintering aid, water, and silicon nitride raw powder are ground and mixed to obtain a first slurry; polyvinyl alcohol and polyethylene glycol are dissolved in water to obtain a colloidal solution, the mass ratio of polyvinyl alcohol to polyethylene glycol being (0.16-0.20): 1, and the total mass of polyvinyl alcohol and polyethylene glycol being 2-8% of the total mass of the sintering aid and the silicon nitride raw powder; the first slurry, the colloidal solution, and a dispersant are mixed to obtain a second slurry; the second slurry is subjected to spray granulation to obtain granulated powder, the inlet temperature of the spray granulation being 300-340°C.The method of the present invention can increase the bulk density of the silicon nitride ceramic granulated powder to more than 0.92 g/cm3.
C04B 35/584 - Produits céramiques mis en forme, caractérisés par leur compositionCompositions céramiquesTraitement de poudres de composés inorganiques préalablement à la fabrication de produits céramiques à base de non oxydes à base de borures, nitrures ou siliciures à base de nitrure de silicium
C04B 35/626 - Préparation ou traitement des poudres individuellement ou par fournées
Provided in the present invention are a high-precision silicon nitride ceramic microsphere, and a preparation method therefor and the use thereof, belonging to the technical field of ceramic sphere preparation. According to the present invention, the defects of pores, abnormal large grains, surface pits, flakes, etc. of silicon nitride ceramic microspheres are overcome, and the high-precision preparation of a silicon nitride ceramic microsphere is realized. The results of embodiments show that the Vickers hardness HV10 of the high-precision silicon nitride ceramic microsphere prepared in the present invention reaches up to 1524 kg/mm2, the fracture toughness reaches up to 8.6 MPa·m1/2Dwphph is greater than or equal to 0.03 μm and less than or equal to 0.08 μm, and all the performance indexes of the high-precision silicon nitride ceramic microsphere meet the G3-level standard requirements prescribed in Rolling Bearing Balls Part 2: Silicon Nitride Ceramic Microbeads GB/T308.2-2010/ISO3290-2:2008.
C04B 35/584 - Produits céramiques mis en forme, caractérisés par leur compositionCompositions céramiquesTraitement de poudres de composés inorganiques préalablement à la fabrication de produits céramiques à base de non oxydes à base de borures, nitrures ou siliciures à base de nitrure de silicium
C04B 35/622 - Procédés de mise en formeTraitement de poudres de composés inorganiques préalablement à la fabrication de produits céramiques
Provided are a large-size silicon nitride ceramic ball, a preparation method therefor and use thereof, belonging to the technical field of ceramic materials. By means of the present invention, a vacuum injection-coagulation forming method is used, such that the forming of large-size and supersized silicon nitride ceramic balls with a high degree of sphericity and a uniform density can be realized; microwave drying is used, such that the drying speed is high, and the deformation of a green body is small; a cold isostatic pressing treatment is carried out on debound ceramic balls, such that the density of sintered ceramic balls is improved; and a two-step gas pressure sintering process is used, such that the internal pores of the ceramic balls are removed, and the density is further improved. By means of the invention, the surfaces and the core parts of the large-size and supersized silicon nitride ceramic balls prepared by means of the method of combining injection-coagulation forming with cold isostatic pressing forming and two-step gas pressure sintering have no obvious difference in properties such as relative density, Vickers hardness and fracture toughness, and the homogenization of the density and mechanical properties of the large-size and supersized silicon nitride ceramic balls can be realized.
C04B 35/584 - Produits céramiques mis en forme, caractérisés par leur compositionCompositions céramiquesTraitement de poudres de composés inorganiques préalablement à la fabrication de produits céramiques à base de non oxydes à base de borures, nitrures ou siliciures à base de nitrure de silicium
C04B 35/622 - Procédés de mise en formeTraitement de poudres de composés inorganiques préalablement à la fabrication de produits céramiques
Provided in the present invention is a preparation method for a silicon nitride-based multiphase conductive ceramic. In the present invention, silicon nitride is used as a matrix, a conductive phase and a sintering aid are added simultaneously, and a two-step microwave sintering method is used; the prepared silicon nitride-based multiphase conductive ceramic has fine uniform grains with a high density, and the mechanical properties thereof such as strength and hardness are also significantly improved. The two-step microwave sintering method used in the present invention can inhibit grain boundary migration and, by using grain boundary diffusion, the green body can be densified; thus, the present method not only inhibits the growth of grains at the later stage of sintering, but will also not affect densification. The embodiment results show that the relative density of the silicon nitride-based multiphase conductive ceramic provided in the present invention is greater than 99%, the Vickers hardness is greater than 15 GPa, the fracture toughness is greater than 6 MPa·m1/2, the bending strength is greater than 900 MPa, and the resistivity is less than 1Ω·cm.
C04B 35/584 - Produits céramiques mis en forme, caractérisés par leur compositionCompositions céramiquesTraitement de poudres de composés inorganiques préalablement à la fabrication de produits céramiques à base de non oxydes à base de borures, nitrures ou siliciures à base de nitrure de silicium
The present invention relates to the technical field of ceramic substrates, and provides a high-thermal-conductivity silicon nitride ceramic insulating plate and a preparation method therefor. According to the present invention, magnesium oxide is used as a first sintering aid, and during a sintering process, magnesium oxide reacts with raw material silicon nitride powder to generate a liquid phase, so that the sintering temperature can be reduced, the production cost is saved, and the density and the bending strength of the silicon nitride ceramic insulating plate can also be improved; hafnium oxide is used as a second sintering aid, and due to the fact that hafnium oxide has a strong capacity of binding to oxygen, hafnium oxide is bound to impurity oxygen in the raw material silicon nitride powder during the sintering process, so that the content of lattice oxygen is eliminated, and the thermal conductivity of the silicon nitride ceramic insulating plate is improved; a third sintering aid of the present invention can prompt liquid phase reaction during the sintering process, and the third sintering aid reacts with silicon nitride powder to form a solid solution, so that amorphous phases at the grain boundary are reduced, high thermal conductivity is ensured, and the bending strength of a product is improved. In addition, according to the present invention, the problem in the prior art that a large-size ultra-thin substrate is difficult to prepare is solved.
C04B 35/584 - Produits céramiques mis en forme, caractérisés par leur compositionCompositions céramiquesTraitement de poudres de composés inorganiques préalablement à la fabrication de produits céramiques à base de non oxydes à base de borures, nitrures ou siliciures à base de nitrure de silicium
A batch processing method for a silicon nitride ceramic microbead, comprising the following steps: step 1, rough grinding: loading silicon nitride blank beads into a groove between an upper grinding plate and a lower grinding plate, adding a grinding medium for processing, and performing repeated cyclic grinding between the upper grinding plate and the lower grinding plate; step 2, fine grinding: adjusting the pressure and rotation speed between the upper grinding plate and the lower grinding plate, loading the silicon nitride ceramic microbeads obtained in step 1 between the upper grinding plate and the lower grinding plate, and adding a grinding medium for processing and grinding; step 3, fine grinding: selecting silicon nitride ceramic microbeads having no obvious processing defects on the surface from the silicon nitride ceramic microbeads obtained in step 2 for processing and grinding; step 4, fine grinding; and step 5, super fine grinding. Said processing method has a high efficiency, a reasonable design and low costs, is easy to operate, and has a high processing efficiency.
B24B 37/02 - Machines ou dispositifs de rodageAccessoires conçus pour travailler les surfaces de révolution
B24B 37/025 - Machines ou dispositifs de rodageAccessoires conçus pour travailler les surfaces de révolution conçus pour travailler les surfaces sphériques
9.
METHOD FOR PREPARING HIGH-RELIABILITY LONG-SERVICE LIFE SILICON NITRIDE CERAMIC BALL FOR AVIATION BEARING
AECC HU’NAN AVIATION POWERPLANT RESEARCH INSTITUTE (Chine)
Inventeur(s)
Zhang, Jing
Wang, Wenxue
Liu, Lu
Sun, Feng
Yan, Jiasen
Song, Jian
Yang, Wenwu
Yang, Kaining
Liu, Fubing
Yu, Anle
Abrégé
A method for preparing a high-reliability long-service life silicon nitride ceramic ball for an aviation bearing, pertaining to the technical field of silicon nitride ceramic ball manufacturing. The method uses a metal organic salt (aluminum isopropoxide and a metal acetate) as a precursor of a sintering aid, and employs hydrolysis, spray drying, and calcination processes, such that the sintering aid can be coated on the surface of silicon nitride to achieve uniform dispersion of the sintering aid in the silicon nitride, thereby avoiding decreases in the reliability and fatigue life of the silicon nitride ceramic ball due to agglomeration and segregation of the sintering aid. The density of the prepared silicon nitride ceramic ball reaches 99.9% or more, the Vickers hardness (HV10) is greater than 1,500, the crushing load ratio is greater than 45%, the Weibull modulus is greater than 15, and the rolling contact fatigue (RCF) life is 400 h or more, and the silicon nitride ceramic ball is especially suitable for manufacturing rolling elements for aviation bearings.
C04B 35/584 - Produits céramiques mis en forme, caractérisés par leur compositionCompositions céramiquesTraitement de poudres de composés inorganiques préalablement à la fabrication de produits céramiques à base de non oxydes à base de borures, nitrures ou siliciures à base de nitrure de silicium
An environmentally-friendly finishing machining method for silicon nitride ceramic balls, belonging to the technical field of ceramic material machining. During a finishing machining process, a water-based circulating liquid is used to replace the existing oily grinding paste, such that oil sludge is avoided, the machining environment is improved, the concept of environmental protection is met, the production process can be simplified, the machining efficiency is improved, the machining cost is saved, and the service life of a cast iron plate is prolonged. A silicon nitride ceramic fine grinding ball obtained by means of machining by using the method meets the fine machining ball unloading requirements, which are set by our enterprise, in the aspects of machining efficiency, surface quality and size precision of a ball body; in addition, all precision indexes of the silicon nitride ceramic ball body can reach the national G20 standard.
B24B 1/00 - Procédés de meulage ou de polissageUtilisation d'équipements auxiliaires en relation avec ces procédés
B24B 11/02 - Machines ou dispositifs pour meuler des surfaces sphériques ou des portions de surfaces sphériquesAccessoires à cet effet pour meuler des billes
11.
DEVICE FOR BATCH-PROCESSING SILICON NITRIDE CERAMIC MICROBEADS
A device for batch-processing silicon nitride ceramic microbeads, relating to the technical field of mechanical processing, and comprising columns (20) which are symmetrically arranged, wherein an upper beam (15) is fixedly arranged at the top of the columns (20), a pressurization mechanism (10) is fixedly connected under the upper beam (15), an upper grinding plate (1) is arranged at the bottom of the pressurization mechanism (10), a lower grinding plate (2) is symmetrically arranged under the upper grinding plate (1), the lower grinding plate (2) is fixedly arranged on a machine bed (19), an unloading pulley mechanism (11) is connected to the bottom of the machine bed (19) by means of a lower spindle (14), and the unloading pulley mechanism (11) is connected to a gear motor (7) and a hydraulic tank (8), respectively; a bead inlet (12) is arranged on one side of the upper grinding plate (1), a bead outlet (13) is arranged on one side of the bottom of the lower grinding plate (2), the bead inlet (12) and the bead outlet (13) are respectively in communication with a storage device, and a vacuum pump (9) is arranged on the storage device; and silicon nitride ceramic microbeads (3) are placed and ground between the upper grinding plate (1) and the lower grinding plate (2).
B24B 37/025 - Machines ou dispositifs de rodageAccessoires conçus pour travailler les surfaces de révolution conçus pour travailler les surfaces sphériques
34344is 93% or above; and the crushed silicon nitride layer generated in the previous reaction can be used as a diluent for the next reaction, and therefore, there is no need to add extra silicon nitride as the diluent, thus improving the net yield of the silicon nitride powder and reducing production cost.
Disclosed is a blank trimming apparatus for a biscuit ceramic ball formed of dry powder, the blank trimming apparatus comprising a base (1), a workbench (3), a rounding handle (7), a tray (9), a plurality of ball trimming steel dies (6) and a plurality of upright posts (2). The workbench (3) is arranged above the base (1), two ends of each upright post (2) are respectively connected to the base (1) and the workbench (3); a through hole (4) is formed in the workbench (3); a plurality of clamping grooves (5) are formed in the periphery of the through hole (4); and the tray (9) is arranged on the base (1). Each ball trimming steel die (6) comprises a circular sleeve (61) and a plurality of clamping strips (62) arranged on the outer side wall of the circular sleeve (61), wherein the clamping strips (62) match the clamping grooves (5) in structure, one clamping strip (62) is arranged in one clamping groove (5), the circular sleeve (61) is arranged in the through hole (4), the inner diameters of the circular sleeves (61) of the plurality of ball trimming steel dies (6) are different from one another, and the head of the rounding handle (7) is a spherical surface recessed inwards.
B28B 11/08 - Appareillages ou procédés pour le traitement ou le travail des objets façonnés pour façonner des surfaces, p. ex. replanissage, bouchardage, gaufrage, rainurage
B24B 11/02 - Machines ou dispositifs pour meuler des surfaces sphériques ou des portions de surfaces sphériquesAccessoires à cet effet pour meuler des billes
B24B 23/00 - Machines de meulage portatives, p. ex. à guidage manuelAccessoires à cet effet
B24B 41/06 - Supports de pièces, p. ex. lunettes réglables
B24B 55/12 - Dispositifs d'évacuation du nuage d'huile ou de l'agent de refroidissementDispositifs pour collecter ou récupérer des matériaux issus du meulage ou du polissage, p. ex. métaux précieux, pierres précieuses, diamants ou similaires
The present invention discloses a ceramic ball automatic sorting system and method. The system automatically sucks a ceramic ball on a ceramic ball feeding track for image acquisition, identifies whether the ceramic ball is defective according to the acquired image information, and determines a ball storage device into which the ceramic ball is placed, and the whole process does not require manual participation, which achieves the automation of ceramic ball defect identification and sorting and improves the ceramic ball defect identification accuracy and sorting efficiency. According to the method, images of the ball surface shot at each angle are automatically spliced by using an automatic image splicing technology to achieve full coverage. A defect is identified by using a threshold segmentation algorithm according to a set threshold, and whether the ceramic ball is defective and the ball storage device where the ceramic ball should be placed are determined, thereby achieving the automation of ceramic ball defect identification and sorting, and improving the ceramic ball defect identification accuracy and sorting efficiency.
G05B 19/4155 - Commande numérique [CN], c.-à-d. machines fonctionnant automatiquement, en particulier machines-outils, p. ex. dans un milieu de fabrication industriel, afin d'effectuer un positionnement, un mouvement ou des actions coordonnées au moyen de données d'un programme sous forme numérique caractérisée par le déroulement du programme, c.-à-d. le déroulement d'un programme de pièce ou le déroulement d'une fonction machine, p. ex. choix d'un programme
15.
SYSTEM AND METHOD FOR AUTOMATICALLY SORTING CERAMIC BALLS
Disclosed by the present invention are a system and method for automatically sorting ceramic balls. The system automatically absorbs ceramic balls on a ceramic ball feed rail for image collection, recognizes whether the ceramic balls are defective balls or not according to collected image information, and determines a ball storage device where the ceramic balls are put. Manual participation is not needed in the entire process, and ceramic ball defects are recognized and sorted automatically, thereby improving the accuracy of ceramic ball defect recognition and the sorting efficiency. According to the present method, captured ball surface images of various angles are spliced automatically using an automatic image splicing technology, so as to achieve full coverage. Defects are recognized using a threshold segmentation algorithm according to set thresholds. Whether ceramic balls are defective balls or not is determined and the ball storage device where the ceramic balls should be put is determined. Thus, ceramic ball defects are recognized and sorted automatically, thereby improving the accuracy of ceramic ball defect recognition and the sorting efficiency.
A ceramic sphere abrasive, a preparation method therefor, and use thereof. The ceramic sphere abrasive comprises the following components in mass percentages: 6-30% of grinding agent; 0.5-5% of dispersant; 15-40% of suspending agent; 10-40% of curing agent; and 20-60% of grinding aid, the grinding agent being a diamond micro powder. The ceramic sphere abrasive has high grinding efficiency which is 3-5 times of that of the conventional process, and has low abrasive cost which is about one third to one quarter of that of the conventional process.
B24B 37/025 - Machines ou dispositifs de rodageAccessoires conçus pour travailler les surfaces de révolution conçus pour travailler les surfaces sphériques
brevets
