113results about How to "Reduce crack defects" patented technology

The invention relates to a fine-pottery sanitary ceramic body and a manufacturing method thereof and belongs to the technical field of ceramic products, which is used for reducing the deformation of a sanitary ceramic product and improving the quality of glaze. The fine-pottery sanitary ceramic body is characterized in that a body raw material comprises the following components in part by mass: 10 to 30 parts of ball clay, 30 to 60 parts of kaoline, 5 to 15 parts of porcelain clay, 5 to 15 parts of quartz and 5 to 15 parts of wollastonite, wherein the kaoline comprises 10 to 25 calcined kaoline. In the manufacturing method, the raw materials and the adding proportion of the fine-pottery body are preferably selected, the crystal phase content of mullite, quartz and the like is controlled, and the glass phase content and the high-temperature plastic deformation are reduced so as to fulfill the aim of reducing the deformation of fine-pottery sanitary ceramics; while reducing the hygroscopic expansion of the body, the manufacturing method improve thermal expansion coefficient of the body at the temperature of 200 DEG C to make the glaze bear high compressive stress, thereby improving the anti-cracking performance of products and ensuring enough long service life. Through the refinement of slurry granularity, the method remarkably reduces the occurrence of disadvantage of glaze pinholes, does not need to reduce the pinholes by using engobe, simplifies a production process, and improves the production efficiency and the qualification rate of the products.

The invention provides a semiconductor device and a method for fabricating the semiconductor device. The semiconductor device has a pad structure with a ring-shaped stress buffer layer between a metal pad and an under-bump metallization (UBM) layer. The stress buffer layer is formed of a dielectric layer with a dielectric constant less than 3.5, a polymer layer, or an aluminum layer. The stress buffer layer is a circular ring, a square ring, an octagonal ring, or any other geometric ring.

The invention relates to an inductance and ultrasound coupling-assisted method for direct laser deposition of a metal material, belongs to the field of additive manufacturing and relates to a coupledenergy field. The energy field is obtained by coupling an inductance temperature field and an ultrasonic wave field. A follow-up electromagnetic induction device is suspended right below a laser headthrough an induction coil, so that the coil moves along with the laser head to preheat and slowly cool a round area around a molten bath. A bottom ultrasonic device is fixed between a worktable and abase plate, and ultrasonic waves are conducted to the molten bath upward through the base plate to impact and stir the molten bath and a solid-liquid interface. The coupled energy field makes up defects that a single inductance temperature field has no stirring effect to the molten bath and a single ultrasonic wave field which is short in action time to the molten bath is not obvious in effect. Induction heating plays a preheating and slow cooling role to reduce a temperature gradient and to reduce a thermal stress. The temperature field improves the impacting and stirring efficiency to the molten bath effectively by alleviating the solidification rate of the molten bath. The coupled energy field can reduce defects of cracks and pores, so that the mechanical properties of a metal materialformed part are improved.

The invention discloses a kind of niobium-titanium microalloying HRB400-scale screw-thread steel and a manufacturing method thereof. The screw-thread steel comprises C, Si, Mn, P, S, Nb, Ti, N and the balance Fe and impurities. The manufacturing method of the niobium-titanium microalloying HRB400-scale screw-thread steel comprises the following steps of smelting in a revolving furnace, treatment outside the furnace, continuous casting, casting blank heating and rolling. During smelting in the revolving furnace, alloy such as silicomanganese and ferroniobium is added for niobium microalloying treatment. During treatment outside the furnace, argon is blown in an argon station, and refining is conducted in an LF furnace. In the process of refining in the LF furnace, a ferrotitanium core-spun yarn is fed for titanium microalloying treatment. According to the technical scheme, before tapping, alloy such as silicomanganese and ferroniobium is added for niobium microalloying treatment, the ferrotitanium core-spun yarn is fed in the process of refining in the LF furnace for titanium microalloying treatment, after titanium is fused into molten steel, proper niobium-titanium microalloying treatment is conducted, the yield of the niobium-titanium alloy is increased, and stable, sustainable and low-cost production of the screw-thread steel is achieved.

The invention relates to the technical field of valve body casting and discloses a high-temperature high-pressure ultralow sulfur-and-phosphorus valve body casting forming process. A plane in which the centers of three pipe openings of a high-temperature high-pressure ultralow sulfur-and-phosphorus valve body casting part are located is used as a parting surface, first dead heads are arranged right above the three pipe opening respectively, second dead heads are arranged above the intersected positions of all pipes of the valve body casting part respectively, a plurality of chilling blocks are arranged under the intersected positions of all the pipes of the valve body casting part respectively, the chilling blocks are separated from the casting part by chromium ores, a bottom-returning type pouring system is adopted for pouring, a cross gate is positioned under the valve body casting part and is connected with a plurality of inner gates on the same horizontal plane, and an outlet in the top end of each inner gate is formed in the wall, close to the end surface, of the corresponding pipe opening. The valve body produced by adopting the casting forming process has the good casting forming quality, the formed matrix structure is compact, the CAE (Computer Aided Engineering) simulation technique is adopted, the production period of the casting part is shortened, the casting part manufacturing process is reasonably optimized, models and molding materials can be saved, the casting part production cost is reduced and the high economic benefit is achieved.

The invention relates to a PEPSET resin moulding and sand cyclic utilization clean casting technology. The technology comprises the following steps: using raw materials to carry out PEPSET resin sand moulding: putting a sand core into a mould cavity, closing the mould cavity by using an automatic mould closer, then casting with molten iron; shaking out the sands after the moulding of product; transferring the old sands into a waste sand regeneration processing system; wherein the regenerated sands can be applied to a cold box core blower to manufacture sand cores, thus the addition amount of new sands is reduced, and the cyclic utilization of old sands is achieved.

The invention provides a method for integrally densifying, drying and carbonizing wood. The method is implemented by the aid of a hot press and includes the steps: compressing the wood in the thickness direction on the hot press at the temperature of 130-150 DEG C; drying the wood in a pressure maintaining state when the wood is compressed to the target thickness; carbonizing the wood when the temperature rises to 180-220 DEG C. Therefore, the wood can be integrally and technically densified, dried and carbonized. The method has the advantages that the technological process is simple, production cycle is short, manpower and material resources are saved, economic benefit is high and the like.

The invention relates to a ceramic sanitary ceramic green body and a preparation method thereof, and belongs to the technical field of ceramic preparation. The preparation raw materials of the ceramicsanitary ceramic green body comprise a green body material and an auxiliary agent, wherein the green body material comprises, by weight, 10%-30% of a southern black mud, 5%-10% of a southern kaolin,8%-14% of a waste ceramic powder, 5%-12% of a blast furnace slag, 10%-20% of a southern pyrophyllite, 1%-5% of talc, 5%-10% of calcined kaolin, 1%-5% of dolomite, 15%-20% of quartz and 4%-6% of wollastonite; and the auxiliary agent is boron nitride micro-powder, and the usage amount of the auxiliary agent is 0.1%-0.5% of the green body material mass. The blast furnace slag and the ceramic waste powder are introduced as raw materials of the ceramic green body, southern raw materials are added, and boron nitride micro-powder is added as the firing auxiliary agent, so that the blast furnace slagand the ceramic waste powder can be subjected to resource utilization, and firing flexural strength of a product can be improved.

The invention discloses a welding method for prolonging service life of a high-strength metal shell, which adopts high-strength anti-wearing steel CiNiMo as a welding substrate. The welding method comprises the following steps of: preparing before welding, carrying out tack welding, pre-heating a welding piece, carrying out welding construction, polishing and carrying out nondestructive testing. The welding method disclosed by the invention is suitable for welding a large-sized piece of low-middle carbon alloy high-strength steel; the welding production rate is high and the anti-cracking performance is good; the welding deformation is small; the welding method has the advantages that selected materials are reasonable and have higher strength; welding current is controlled in a certain range and the occurrence possibility of crack defects is reduced; and with the adoption of the welding method disclosed by the invention, hydrogen removing treatment is carried out after the welding, residual hydrogen in a welding connector is dispersed and escaped in time, and the generation of delaying cracks is reduced.

The invention provides a tensile bending forming process of a complex section bar, relating to the technical field of section bar bending forming and solving the problems of quality defects generated in a section bar bending process in the prior art. The tensile bending forming process of the complex section bar comprises the following steps of: manufacturing a concave mould cavity and a movable mould which corresponds to the concave mould cavity according to the bending radius, the bending angle and the sectional shape of a machined part; rotating a regulating mechanism to loosen the movablemould, and placing the section bar into the concave mould cavity; clamping one end of the section bar into a collet, and placing the other end of the section bar into a stretching device; applying a pulling force on the stretching device so that the section bar generates elongation, and rotating the regulating mechanism to enable the movable mould to tightly press on the section bar; applying a bending moment to the movable mould to enable the movable mould, the section bar and the stretching device to rotate along a scale so as to enable the section bar to be bent at a needed angle; and rotating the regulating mechanism, removing the movable mould, the stretching device and the collet, and taking out the bending formed section bar. According to the tensile bending forming process disclosed by the invention, the section bar with a complex sectional shape can be formed; the forming quality of a bending part is good, and a resilience amount is small.

The invention relates to a method for testing the crack sensitivity of a precision steel casting and a model thereof. The method is suitable for the crack sensitivity test of material components and casting process parameters, and the model is a grid type; different fillet sizes are adopted at the transition parts of the model grid, and grid rib plates are different in thickness; and the model is cast and shot blasting is performed according to normal processes, a crack observing part is determined, and the crack at the part is detected and evaluated. The model and test method provided by the invention can effectively predict the cracking trend of different materials and process parameters in the precision casting process, and also can provide reference to the design of the casting fillet size so as to guarantee the rationality in designing the casting structure, the casting material components and the casting process parameters, reduce the cracking defect of the casting and obtain a high-quality low-cost precision steel casting.

The embodiment of the invention discloses a method and device for machining a tungsten and titanium alloy target material. The method comprises the step of machining the tungsten and titanium alloy target material by adopting a diamond abrasive tool with the granularity of 120-150 meshes, wherein the rotating speed of the diamond abrasive tool is 3500-4000r / m, the feed amount is not more than 0.02 mm each time and the feed speed is not more than 500mm / m. The materials for the machining device comprise diamond with the granularity of 120-150 meshes. By applying the machining method provided by the embodiment of the invention, the cracking defect generated in the machining process of the tungsten and titanium alloy target material can be reduced and the machining precision can be remarkably improved. The materials of the machining device for the tungsten and titanium alloy target material provided by the embodiment of the invention comprise the higher-hardness diamond, so that the integral hardness of the machining device can be improved, the cracking defect of the tungsten and titanium alloy target material can be reduced and the machining quality can be improved; meanwhile, the wear on the machining device can be reduced, the frequent replacement for the machining device can be avoided, the machining efficiency can be improved and the machining cost can be reduced.

The invention relates to the technical field of precise hot forming of material difficult to deform in metal material plastic processing, in particular to a die and method for forming a straight tube section-expansion section composite titanium alloy equal-wall-thickness curved generatrix thin wall rotation body component. The problems that according to an existing method, the wall thickness is reduced sharply, axial cracking is prone to occurring, in the forming process, deformation is uneven, and overall performance of the component is reduced are solved. The forming method includes the steps that the shape and size of a variable-wall-thickness tube blank are calculated through theoretical calculation, an original thick wall tube blank is machined, a lubricant and a protective agent are used for performing coating before rotation, the tube blank with the variable wall thickness is formed in a rotary extrusion mode, the mouth part of the tube blank with the variable wall thickness is sheared at an electric spark end, before hot expanding, a lubricant and a protective agent are used for performing coating, and then induction heating is performed on an expanded mouth to obtain the straight tube section-expansion section composite equal-wall-thickness titanium alloy curved gemetratrix component. Evenness of the integral wall thickness of the obtained workpiece is high. The expanding coefficient and overall performance of the component are improved.

The invention discloses a high-strength antifriction lead-free copper-based sliding bearing material. A ball milling process is adopted to enable copper powder, iron powder and copper sulphide powderto be mechanically alloyed, and CuS and Fe mixed powder can generate superfine particle nanocrystalline FeS in a high-energy guide-in manner through a mechanically induced chemical reaction. The reaction in situ composite process is used for solving the problems that enhanced particles are added externally, air suction and wettability are poor, and the interface combination is poor; meanwhile, through the ball milling process, the phenomenon that when ferrous sulfide is directly added, agglomeration is easily caused is avoided; in the ball milling process, the other part of Fe atoms is added into copper atoms in a solid solution manner so as to achieve the solid solution reinforcing effect, and the copper base composite is reinforced. The antifriction and anti-sticking capacity of FeS is mainly used for replacing lead in the original copper base bearing material, lead pollution is avoided, meanwhile, through Fe solid solution, the copper-based sliding bearing material is reinforced, and effective unifying of high strength and good lubricating characteristics of the lead-free copper-based sliding bearing material is achieved.

The invention relates to a metal active gas (MAG) welding method for butting quenched low-alloy super-high-strength steel and high-quality carbon structural steel and a low-alloy super-high-strength steel MAG welding method, which solve the welding technical problems that the thickness difference and the material performance difference of heterogeneous steel, namely the quenched low-alloy super-high-strength steel and the high-quality carbon structural steel, are large and the weldability of the quenched super-high-strength steel is low. The MAG welding method comprises the following main steps of: machining a part to be welded; quenching and tempering a 35CrMnSiA barrel piece; preheating, tacking and welding; and slowly cooling the 35CrMnSiA barrel piece; and detecting the 35CrMnSiA barrel piece. By the MAG welding method, the weldability of the quenched super-high-strength steel and the carbon structural steel is enhanced; fusion of a welding line is high; and through penetrant flawdetection and coloring flaw detection, the most sensitive crack defects of the super-high-strength steel are not found in a welding bead and a heat affected zone, so the shape of the welding line is good. The MAG welding method belongs to semi-automatic welding; and compared with manual arc welding, the MAG welding method has the advantages of reducing arc striking points and arc receiving points, so that welding defects can be reduced effectively.

The invention is a multi-point altering edge pressing force hydraulic pressure presser which is for sheets pressing shaping field. The invention includes: main cylinder, bridging beam, sliding block, crutch, hydraulic power drawing mechanism, base, and workbench. The main cylinder is fixed on the bridging beam with its piston linked with the sliding block which sliding up and down along the crutch. The hydraulic power drawing mechanism is set below the workbench all supported by the base. The hydraulic power drawing mechanism includes connecting rod, several edge cylinders, jacking cylinder, soleplate, lower draw rod, drawing bed piece, jacking rod. The invention advantages are that several independent controlling edge cylinder is installed below the presser casting through the drawing bed plate on different sections of the edge rings with different edge pressing force altering by time so to precisely control the edge pressing force stroke-wise according to the technics and the designer requirements so that the sheet shaping property and size stability is greatly enhanced which lies a cornerstone for enhance the pressing piece qualities.

The invention discloses a surface modification layer containing an iron and aluminum intermetallic compound and a preparation method of the surface modification layer. The preparation method comprises the following steps: taking an aluminum powder pressing body as a tool electrode, taking aluminum powder and coal oil mixed liquid as working liquid, and taking common low-carbon steel as a workpiece; enabling pulse discharge to be generated between the electrode and the workpiece in the working liquid by using a common electric spark machine tool; enabling the electrode, aluminum in the working liquid and iron in the workpiece to carry out in-situ alloying reaction with the aid of discharge energy; and finally, forming the surface modification layer containing the iron and aluminum intermetallic compound on the surface of the workpiece. The modification layer prepared by the method has the advantages of compact structure, good basic binding force and the like, and is expected to be widely used in the field of surface modification for improvement of corrosion resistance and wear resistance of structure materials.

The invention discloses a crystallizer for preparing a superhard aluminum alloy flat cast ingot and a use method of the crystallizer and relates to a tool for preparing the superhard aluminum alloy flat cast ingot and a use method of the tool.The crystallizer aims at solving the problem that superhard aluminum alloys produced by the existing casting tool have high possibility of crack rejects. The crystallizer for preparing the superhard aluminum alloy flat cast ingot comprises a crystallizer water chamber, a water chamber gland, a secondary water distribution plate and an oil gland, wherein the crystallizer water chamber comprises a water chamber internal wall, a water chamber external wall and a water chamber base; a plane is arranged at a junction between the internal surface and the upper surface of the water chamber internal wall; water outlet holes are formed in the plane; water inlet holes are formed at the two ends of the water chamber gland in a length direction; and a lubricating oil channel is arranged on the water chamber base and located close to the water chamber internal wall on the plane on the outer side of a cavity.The use method comprises the step of arranging a water baffle in a down direction of the cast ingot below the crystallizer when in use.The method reduces crack tendency.

The invention discloses a ceramic coating protection gradient carbon-ceramic composite material and a preparation method thereof. The ceramic coating protection gradient carbon-ceramic composite material comprises: a gradient carbon-ceramic composite material which is provided with a concave structure on the surface thereof and is a gradient C / C-ZrC-SiC composite material; and an ultrahigh-temperature ceramic coating which is continuously arranged along the surface of the gradient carbon-ceramic composite material and the inner wall surface of the concave structure. The ultrahigh-temperature ceramic coating is an indissolvable metal carbide coating formed by diffusing and infiltrating indissolvable metal along the surface of the gradient carbon-ceramic composite material and reacting the indissolvable metal with the surface of the gradient carbon-ceramic composite material. Therefore, the formed ceramic coating is a three-dimensional jack structure coating, the interfacial strength of the ceramic coating is far higher than that of a two-dimensional plane coating, the surface area of the coating is greatly increased due to the arrangement of the concave structure, meanwhile, the flow resistance of melt on the surface of the composite material can be improved, then the overall temperature resistance of the composite material can be improved, and the risk of coating stripping is reduced.

Disclosed is a glass plate package body wherein a glass plate stack formed by stacking a plurality of glass plates with a sheet between the plates is packed by a package container, and wherein the glass plate has a thickness of 0.7 mm or less, the glass plates are vertically stacked to be tilted relative to the vertical direction to form the glass plate stack, and the deviation in the thickness of the glass plate stack is 10% or less.

The invention provides an integrated water tank type crystallizer used for casting 7 series extra super duralumin alloy, relating to a crystallizer. The invention solves the problem that cast ingot produces cracks caused by stress concentration as the existing crystallizer is not even in water-cooling distribution. The cross section contour of the flat through hole is composed of two arc sections and two straight line sections, each arc section is formed by butt joint of two arcs in different diameters; the lower end face of all the side walls of crystallizer tank body is opened with an annular groove, the lower end face of the annular water feeding hole wall body between the annular groove and the flat through hole is opened with a plurality of osculums in uniform distribution, the lower end of each osculum is inclined toward the central axis of the flat through hole; and four clapboards are respectively arranged at the two ends of the annular groove and divide the annular groove into four regions. The crystallizer of the invention adopts four-section design and different diameters of osculums to control water flow, so that cooling of cast ingot is even, temperature is ensured to be consistent with stress field distribution, and cast ingot crack tendency is greatly reduced.

The invention provides an induction heating assisted underwater laser cladding or additional material device which includes a controller. The controller is connected with a laser, a robot, a wire feeder and an induction heating machine, the laser is connected with a laser head through an optical fiber, a laser welding torch is fixedly arranged directly below the laser head, and the laser head is further connected to the robot. The laser welding torch is further provided with a wire feeding end opening, a wire feeding tube is arranged inside the wire feeding end opening, one end of the wire feeding tube extends into the laser welding torch, and the other end of the wire feeding tube is butt joint with the wire feeder. A welding wire is guided into the wire feeding tube, the laser welding torch is internally provided with an induction coil I, the induction coil I is slidably connected to a transmission shaft through a connecting device, the transmission shaft is fixed to the inner wall of the laser welding torch in a bridge joint mode, the transmission shaft is connected with a stepping motor arranged on the outer side of the laser welding torch, and the opening and closing of the stepping motor are controlled by the controller through a control system. The end of the induction coil I is connected to the induction heating machine through a waterproof cable penetrating through thewall surface of the laser welding torch. The induction heating assisted underwater laser cladding or additional material device can be widely used in the technical field of underwater laser cladding / additional materials.

The invention discloses a high-strength and high-plasticity high-entropy alloy and a preparation method thereof, and belongs to the technical field of metal materials and manufacturing. The high-entropy alloy is prepared from the following raw materials of metal particles of Co, Cr, Fe and Ni and intermediate alloy particles of Al-10Er (the mass fraction of Er is 10%). The preparation method specifically comprises the following steps that the metal particles are weighed according to the set proportion, melted in a high-vacuum electric arc melting furnace and then solidified in a copper mold soas to prepare a high-entropy alloy, wherein in order to ensure the uniformity of alloy components in the smelting process, alloy blocks need to be repeatedly smelted; and the as-cast high-entropy alloy prepared in the initial stage is homogenized in a high-temperature heat treatment furnace, then water quenching is carried out, the high-entropy alloy ingot is rolled at the temperature of 500-800DEG C, and the rolled sample is cooled along with air to obtain the high-strength and high-plasticity high-entropy alloy. The high-entropy alloy prepared by using the preparation method has excellentmechanical properties, and the preparation process is simple.

The invention discloses a porcelain plate formed by one-time dry pressing of a prefabricated mold and a manufacturing method. The porcelain plate comprises a flat blank layer and a prefabricated protrusion, the flat blank layer and the prefabricated protrusion are integrally formed by porcelain raw materials in a dry pressing mode, the height H1 of the prefabricated protrusion ranges from 8 mm to20 mm, and the thickness H2 of the flat blank layer ranges from 6 mm to 15 mm. According to the porcelain plate formed by one-time dry pressing of the prefabricated mold and the manufacturing method,safer curtain wall dry hanging application of the porcelain plate can be carried out through hanging pieces, the fact that the flat blank layer and the prefabricated protrusion are integrally formed in a dry pressing mode is adopted, the porcelain plate has the characteristic of being high in strength and good in integrality; and therefore, a curtain wall material with better physical and chemicalproperties and safer dry hanging is provided for dry hanging application of a building curtain wall.

The invention discloses a technique device for improving the core sand deformability and collapsibility of the device. Through the method, the deformability of sodium silicate core sand can be greatly improved, the collapsibility of the sodium silicate core sand is greatly improved, by widely applying the technology, cracks of castings are reduced by 90% or above compared with cracks formed originally, meanwhile, due to the fact that the collapsibility of the core sand is improved, the sand cleaning labor intensity of workers for the same casting is reduced by 90%, and the working efficiency is greatly improved. Through the technique device, the crack defects of castings is greatly reduced, the rejection rate is lowered, sand cleaning is easy due to the good collapsibility, the production cycle is shortened, and thus the manufacturing cost is lowered.

The invention provides an MAB phase ceramic metal layered composite material and a preparation method and application thereof. The composite material comprises metal layers and MAB phase layers whichare alternately stacked, wherein the MAB phase layers are attached to the metal layers; the preparation method of the composite material comprises the following steps: preparing MAB phase slurry; coating the MAB phase slurry on the surface of a metal substrate; drying and curing the metal base material coated with the MAB phase slurry, and then performing lamination to obtain a laminated blank; preprocessing the laminated blank to obtain a pre-product; and sintering the pre-product, and cooling the sintered product along with the furnace to obtain the MAB-phase ceramic metal layered compositematerial. The composite material has the advantages of high interface strength, light weight, high strength, wear resistance and corrosion resistance, and can meet the application requirements in thefields of carrying tools, power transmission and transformation or military materials.

The invention belongs to the field of chemical engineering devices and relates to a carbonization and activation device for active coke production. The device comprises a material channel and flues at two sides of the material channel. The device also comprises a preheating section, a carbonization section, an activation section and a cooling section and the sections are orderly arranged from top to bottom along a vertical direction. The flues in the carbonization and activation sections are respectively provided with gas burners. The flue in the activation section is provided with an activator inlet. The device realizes combination of carbonization and activation, has less processes, uniform and continuous reaction processes, a fast activation rate, a high raw material utilization rate and high production power, greatly reduces power and energy consumption and has a low cost and a high product yield.

The invention discloses an aviation titanium alloy 3D printing enhancement process, which comprises the following steps: S1, outputting a to-be-laid powder raw material through a mixer, and flatly laying the to-be-laid powder raw material on a powder bed through a scraper strip and a powder leaking groove; S2, performing laser scanning on metal powder on the powder bed for the first time until thetemperature of the metal powder laid on the powder bed rises to a preset temperature; S3, planning a scanning path for a preheated metal powder layer according to a set scanning strategy, and performing laser scanning for the second time; S4, cooling and molding to obtain a solidified metal sheet; S5, performing laser scanning on the solidified metal sheet for the third time to obtain a semi-finished product; and S6, performing laser scanning on the surface of a metal cutting layer of a finished product for the fourth time, and then the aviation titanium alloy 3D printing enhancement processis completed. The process provided by the invention can reduce cracks and bubbles in the finished product, and the finished product is high in mechanical strength, dimensional precision and compactness and low in surface roughness Ra value.

The invention discloses an antifriction lead-free copper-based sliding bearing material and a preparation method thereof. The ferrous sulfide powder, the bismuth powder and the bronze powder are subjected to mechanical alloying by adopting a ball milling technology to improve the interface adhesive strength of the ferrous sulfide, the bismuth and the bronze, and the phenomenon that the ferrous sulfide is easy to agglomerate when the content of copper matrix is relatively high is improved, the structure of FeS is good in oil storage capacity, the stability of the liquid-solid lubricating film is enabled to be good, so that the process of Bi spalling, the fusion of the low-melting-point component Bi and separating out of the low-melting-point component Bi are relieved, and the liquid-solid lubricating film can also be repaired and completed, so that the antifriction performance of the material is improved; in conclusion, the antifriction and wear-resistant properties of the copper-basedsliding bearing material are improved, the lead which is used as a lubricant in the copper-based bearing material is replaced by the good synergistic effect of the ferrous sulfide and the bismuth, sothat the pollution of lead is avoided; and the antifriction lead-free copper-based sliding bearing material and the preparation method thereof have the advantages of being low in cost and suitable forindustrial production.

The invention provides an Al-Cu series aluminum alloy fired mold precision casting deformation control method for severe transition of the wall thickness of a C-shaped opening. The method comprises the steps that firstly, according to the structural features of a casting, a pouring system is designed, a cross gate in the shape of a half Chinese character 'mi' is designed, an anti-deformation rib is arranged at the opening of the thick wall portion, a wax mold is pressed, and module combining is carried out; then, the size of the anti-deformation rib is adjusted till the size of the C-shaped opening is qualified, and after the wax mold is fixed, the anti-deformation rib is removed; and finally, according to the fired mold casting technological process, shell making and pouring of the casting are carried out, the cross gate with the direction the same as that of the C-shaped opening of the casting is kept, the casting is subjected to heat treatment according to the technological requirements, and after heat treatment, the cross gate is removed. The casting is subjected to X-ray detection, fluorescence detection and size inspection. After combining, the anti-deformation rib of the waxmold is removed, and the situation that the wax mold deforms in the module combining process, and consequently finally the size of the casting is unqualified is avoided; and the cross gate is removedafter heat treatment, and the situation that the casting deforms in the heat treatment process, and consequently the size of the casting is unqualified is avoided.