CN109482813B - WCp/EPS lost foam pattern and WCp/Fe composite material preparation - Google Patents
WCp/EPS lost foam pattern and WCp/Fe composite material preparation Download PDFInfo
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- CN109482813B CN109482813B CN201811567823.7A CN201811567823A CN109482813B CN 109482813 B CN109482813 B CN 109482813B CN 201811567823 A CN201811567823 A CN 201811567823A CN 109482813 B CN109482813 B CN 109482813B
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22C—FOUNDRY MOULDING
- B22C7/00—Patterns; Manufacture thereof so far as not provided for in other classes
- B22C7/02—Lost patterns
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22C—FOUNDRY MOULDING
- B22C9/00—Moulds or cores; Moulding processes
- B22C9/02—Sand moulds or like moulds for shaped castings
- B22C9/04—Use of lost patterns
- B22C9/046—Use of patterns which are eliminated by the liquid metal in the mould
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D18/00—Pressure casting; Vacuum casting
- B22D18/04—Low pressure casting, i.e. making use of pressures up to a few bars to fill the mould
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D27/00—Treating the metal in the mould while it is molten or ductile ; Pressure or vacuum casting
- B22D27/20—Measures not previously mentioned for influencing the grain structure or texture; Selection of compositions therefor
Abstract
The invention discloses a WCp/EPS (tungsten carbide/expanded polystyrene) lost foam pattern and a WCp/Fe composite material lost foam casting forming process, belonging to the technical field of metal forming. The WCp/EPS lost foam pattern preparation method comprises the following steps: weighing WC particles, rare earth powder, EPS beads and an adhesive in parts by volume, and uniformly mixing to complete the preparation of a mixed material; preheating the mould, and when the temperature of the mould reaches the working temperature of 100 ℃, starting to fill; filling the mixed material into a mould by using compressed air, and introducing hot steam; after the hot steam is removed, spraying water on the back of the die for cooling, so that the temperature of the die sample is quickly cooled to 40-50 ℃, the temperature is reduced to be below the softening temperature, and the die sample is removed after being shaped. The process method provided by the invention has the advantages that the alloy particles and the matrix are firmly combined, the particles are uniformly dispersed, the comprehensive mechanical property of the product is improved, and large WCp/Fe composite material parts with complex shapes can be manufactured by lost foam casting.
Description
Technical Field
The invention belongs to the technical field of metal forming, and particularly relates to a WCp/EPS (tungsten carbide/polystyrene) lost foam pattern and a WCp/Fe composite lost foam casting forming process.
Background
The WC has excellent physical and chemical properties, the market of WC particles as an abrasive is mature, and particularly, the WCp/Fe composite material is formed by compounding hard-phase WC and an iron matrix, so that the WCp/Fe composite material is most suitable for working conditions of high stress, high abrasion and strong impact, and the WCp/Fe composite material is gradually and widely applied to actual industrial production due to low price, excellent high-temperature resistance, high-speed abrasion resistance and good mechanical property.
The existing WCp/Fe composite material preparation process comprises a powder metallurgy method, a dynamic forming method, a spray deposition technology, a non-pressure infiltration method, a casting method and the like.
Powder metallurgy is a process in which a matrix alloy powder is first mixed with reinforcement particles, whiskers, or platelets in the solid state, followed by cold pressing, encapsulation, degassing, and high temperature densification (including hot pressing, hot extrusion, hot rolling, etc.). The process method has the characteristics of randomly adjusting the adding amount of the reinforcement, accurately controlling the proportion of the components and the like, and the prepared workpiece has compact, refined and uniform tissue and few internal defects. However, the requirements for raw materials are high, the equipment cost is also expensive, and secondary plastic working is required for the composite material. Therefore, the process for preparing the particle-reinforced metal matrix composite material by adopting the powder metallurgy method is complex, and the preparation process needs to be carried out under the sealed, vacuum or protective atmosphere, the required equipment and production cost are high, and the structure and the size of the prepared part are limited.
The dynamic forming method is a method in which a strong shock wave generated by explosion, a gas-driven gun, an electromagnetic force, or the like is instantaneously applied to a powder to form the powder, and since high-pressure impact is applied to the powder, the powder particles are severely sheared and deformed and the particle surfaces are instantaneously melted, thereby causing the particles to be bonded. In the forming process, the energy of the shock wave is mainly consumed on the surface of the particles, the internal temperature change is not large, and the blank structure after forming is only locally changed. The dynamic forming method has an advantage of enabling the particles to retain a metastable state of the powder, and has disadvantages of being easily cracked and enabling a change in the material structure during the high-pressure application and release.
The spray deposition technology is a new type of fast solidification technology, and is to add reinforcing particles during the atomization of liquid metal to make alloy powder and reinforcing particles deposit on a collector simultaneously. In the process of preparing the iron-based composite material by the method, the contact time of molten metal and the reinforced particles is short, so that the interface reaction is small, and macroscopic casting defects are not easy to appear. The prepared composite material has an equiaxed crystal structure and good mechanical property. And the production cycle is short, and the molding speed is high. However, the composite material prepared by this method has disadvantages such as non-uniform distribution of the reinforcing particles, expensive production equipment, high production cost, and low utilization of the reinforcing particles.
The casting method refers to a method of casting by introducing reinforcing particles into a metal melt and uniformly dispersing the reinforcing particles in the melt and then shaping. According to different dispersion modes, the method comprises mechanical stirring, electromagnetic stirring, ultrasonic vibration treatment and the like. The method is divided into liquid stirring, semi-solid stirring and the like according to the difference of solid and liquid states of the metal melt. Compared with other methods, the casting method can use traditional casting equipment and devices, has the advantages of low cost, suitability for industrial production, capability of manufacturing large and complex parts and the like, and is the main process method for preparing the particle, whisker and short fiber reinforced metal matrix composite at present. The method comprises the following steps: die casting, counter pressure casting, squeeze casting, semi-solid casting, and the like.
The die casting method is a technological method for preparing the metal-based composite material by filling a liquid or semi-liquid metal-based composite material or metal into a die casting mold cavity or pores of a reinforced material preform at a certain speed under the action of pressure and quickly solidifying and forming under the action of pressure. The specific process comprises the following steps: firstly, pouring a metal melt containing a reinforcing material into a preheating mould, and quickly pressurizing (the pressure is about 70-100 MPa) to quickly solidify a metal matrix composite solution; and ejecting the composite material after the composite material is completely cured to obtain the metal matrix composite material blank or die casting with the required shape and size. Compared with other casting process technologies, the surface of the die casting is smoother, the size consistency is good, and the air tightness is poor. In contrast, die casting equipment and dies are expensive to manufacture, and therefore the process is generally only suitable for mass production.
The counter-pressure casting is also called differential pressure casting and differential pressure casting, is a casting technique method of mold filling and solidification crystallization under the action of pressure, and has the characteristics of low-pressure casting and pressure kettle casting. The process can be described as follows: installing a sealing cover outside the casting mould, introducing compressed air into the crucible and the sealing cover, and controlling the pressure in the crucible to be higher than the pressure in the cover; the molten metal in the crucible is injected into the casting mold from the mold bottom through the riser tube under the action of pressure difference, and crystallization is carried out under the action of pressure. The counter-pressure casting method has the characteristics of stable mold filling, compact casting structure, stable casting size, good surface quality and the like, but the process method has high requirements on equipment and high investment cost.
The extrusion casting method is that the reinforcing particles are bonded into the required prefabricated member of the reinforcing body in a certain mode, the prefabricated member of the reinforcing body is placed in a mould, then the liquid metal material is poured into the mould, a certain pressure is applied to enable the solution to permeate into the gap of the prefabricated member, and then the composite material with the required shape can be obtained after natural cooling. Squeeze casting also has certain disadvantages. (1) Preforms are not easy to produce, especially preforms of complex shape. (2) The pressure of extrusion casting is not easy to control, the pressure is too low, liquid aluminum is not easy to extrude into the prefabricated part, and the shape of the prefabricated part is easy to damage when the pressure is too high, so that the quality of the composite material is damaged. (3) During liquid squeeze casting, WC particles tend to sink and cause uneven distribution of the reinforcing phase. (4) The existing process can not well solve the problem of uniformity of WC particles in the prefabricated member.
The semi-solid casting method is to add the reinforced particles into the semi-solid metal melt and to evenly distribute the particles in the matrix material by stirring, so as to obtain good interface combination; and then the semi-solid composite material is cast into a mould. Although the semi-solid casting method has a simple process, the interface bonding between the reinforcing particles and the matrix metal melt, the uniformity of particle distribution, and the like are difficult to control, and the ratio of the reinforcing particles to be added also has an upper limit.
The technology for casting surface composite material by using lost foam is characterized by that the prepared alloy coating material is coated on the casting mould made of expandable polystyrene, and after the refractory material is coated and dried, it is vibrated and moulded by using dry sand. When the alloy liquid is filled, organic binders and the like in the foam pattern and the alloying coating layer are decomposed and gasified when meeting the high-temperature alloy liquid, generated gas overflows from the coating gaps under the action of negative pressure suction, high-temperature metal liquid permeates into the alloy powder gaps under the action of capillary force, negative pressure suction, iron liquid static pressure and the like, and alloy powder particles are melted, decomposed and diffused and finally combined with mother liquid to form a casting with special surface performance.
In particular, patent CN103394671A discloses a preparation process of lost foam casting high manganese steel wear-resistant surface composite material, which adopts a lost foam casting method to prepare the surface composite material, and the process steps are as follows: preparing water-based paint, wherein the raw materials for preparing the water-based paint are selected from the following raw materials: weighing SiC particles, ferrochrome powder, rare earth, EPS beads and CMC in parts by weight; coating the prepared water-based paint on the surface of a lost foam pattern; and (3) placing the lost foam pattern coated with the coating into a drying chamber for baking, coating the water-based coating, then coating the common lost foam iron coating, and drying. Assembling boxes, and performing dry sand vibration molding; and (6) pouring. The thickness of the surface composite layer of the surface wear-resistant composite material prepared by the process is 3-4 mm. However, in the technical scheme, the surface of the pattern is coated with the coating, and the surface coating layer and the molten metal are subjected to metallurgical reaction to form a surface composite material layer, namely a part of the part. However, when the coating is applied on the pattern, the size of the part cannot be accurately controlled due to the difficulty in accurately controlling the thickness of the coating, which causes great difficulty in mass production, and the thickness of the wear-resistant layer cannot be made too thick, which is usually only 3-5 mm.
Disclosure of Invention
The invention aims to provide a WCp/EPS lost foam pattern preparation method and a WCp/Fe composite lost foam casting forming method, the method has high production efficiency and low cost, alloy particles are firmly combined with a matrix, the particles are uniformly dispersed, the comprehensive mechanical property of parts is obviously improved, and the method can be used for manufacturing large WCp/Fe composite parts with complex shapes.
In order to achieve the purpose, the invention adopts the technical scheme that:
a WCp/EPS lost foam pattern preparation method comprises the following steps,
1) weighing WC particles, rare earth powder, EPS beads and an adhesive in parts by volume, and uniformly mixing the weighed WC particles, rare earth powder, EPS beads and adhesive to complete the preparation of a mixed material;
2) preheating the mould to the working temperature of 100 ℃;
3) filling the mixed material into a mould by using compressed air, introducing hot steam into the mould, and simultaneously performing pressure maintaining treatment;
4) and after pressure maintaining is finished, removing the hot steam, spraying water on the back of the die for cooling, quickly cooling the temperature of the die sample to 40-50 ℃, reducing the temperature to be below the softening temperature, shaping the die sample, and demolding to obtain the WCp/EPS lost foam die sample.
The technical scheme of the invention is further improved as follows: the rare earth powder in the step 1) adopts rare earth silicon.
The technical scheme of the invention is further improved as follows: the volume parts of the mixed materials in the step 1) are as follows: 5-10 parts of WC particles, 1-2 parts of rare earth powder, 87-92 parts of EPS beads and 2-3 parts of an adhesive.
The technical scheme of the invention is further improved as follows: the granularity of the WC particles in the step 1) is 500-2000 meshes.
The technical scheme of the invention is further improved as follows: in the step 3), the temperature of hot steam is 120 ℃, the air pressure is 0.15-0.25MPa, and the ventilation and pressure maintaining time in the mold is 0.5-10 min.
The technical scheme of the invention is further improved as follows: the complex pattern is first manufactured in several modules, and then the modules are assembled into an integral pattern, and the integral pattern and the casting system are assembled into a pattern group.
A WCp/Fe composite material lost foam casting forming method adopts a WCp/EPS lost foam pattern prepared according to any one of claims 1-5, and comprises the following specific steps:
1) coating cast iron lost foam casting coating on the surface of the WCp/EPS pattern;
2) placing the WCp/EPS pattern coated with the coating into a drying chamber for baking, wherein the baking temperature is 50-55 ℃, and the relative humidity of the drying chamber is less than or equal to 30%;
3) assembling boxes, and performing vibration molding by using dry sand;
4) pouring cast iron alloy liquid in the box at the pouring temperature of 1380-1480 ℃, preserving the heat for 2-10 hours after the pouring is finished, turning the box and shakeout to obtain a casting;
5) and carrying out heat treatment on the lost foam casting test block, wherein the heating temperature is 1050-1100 ℃, and the heat preservation time is 1-3 h.
The technical scheme of the invention is further improved as follows: the thickness of the cast iron coating layer in the step 1) is as follows: 1.2-1.8 mm.
The technical scheme of the invention is further improved as follows: the cast iron coating layer in the step 1) is ZT-1 cast iron coating.
The technical scheme of the invention is further improved as follows: and 4) in the step 4), negative pressure casting is adopted, the negative pressure degree is 0.03-0.06MPa, and the pressure is maintained for 10-60 minutes.
Due to the adoption of the technical scheme, the invention has the following technical effects:
the WCp/EPS lost foam pattern preparation method and the WCp/Fe composite lost foam casting forming method provided by the invention have the advantages that the production efficiency is high, the cost is low, the alloy particles and the matrix are firmly combined, the particles are uniformly dispersed, the comprehensive mechanical property of the part is obviously improved, and the method can be used for manufacturing large WCp/Fe composite parts with complex shapes.
The rare earth element has higher solid solubility in silicon and higher rare earth content in the rare earth silicon, has good solid solution strengthening and precipitation strengthening effects on products, and can effectively improve the alloy structure and microstructure, improve the mechanical properties of the alloy at room temperature and high temperature, enhance the corrosion resistance and heat resistance of the alloy and the like. Meanwhile, the rare earth element has good aging strengthening effect and can precipitate very stable dispersed phase particles, so that the high-temperature strength and the creep resistance can be greatly improved. After the rare earth silicon is added, the tensile strength and the elongation of the alloy are both obviously improved, and the alloy tends to increase and then decrease along with the increase of the weight fraction of the rare earth silicon. When the mass fraction of the rare earth silicon is about 1.5%, the alloy structure refining effect is best, and the tensile strength reaches the maximum value.
The invention mainly adopts WC particles, rare earth powder, additives, EPS beads and other raw materials, and the WC particles have wide sources. The hard phase WC particles are uniformly distributed in the iron matrix, so that the dispersion strengthening effect is achieved, and meanwhile, the WC particles are used as the hard phase, so that the external load is shared, and the abrasion effect on the iron matrix is reduced. The EPS beads have certain compressive strength, ensure that the WC particles do not collapse and agglomerate before being mixed into the molten iron, have good volatility and can be quickly gasified and disappear after being reacted with the high-temperature molten iron.
The volume proportion of the WC particles, the rare earth powder, the EPS beads and the adhesive ensures that WC in the preformed model obtains good support of the EPS beads, and the WC particles can be uniformly distributed in a space mainly comprising the EPS beads without segregation.
Compressed air is adopted for filling in the preparation process of the lost foam pattern, so that the mixed material can be uniformly filled in the mold; the pressure maintaining treatment can ensure that the beads are further expanded in the die, and the density and the integrity of the lost foam pattern are improved. The air pressure parameters are matched with the pressure maintaining time, so that the lost foam pattern meets the quality requirement.
The complex pattern can be manufactured by a plurality of modules, and then the whole pattern is formed by assembling, so that the requirement on a die is reduced, the manufacturing process of the complex pattern is simplified, and the application range of the invention is expanded.
The preparation method of the lost foam pattern and the casting forming method of the composite lost foam provided by the invention are used as a set of complete process, firstly, the WCp/EPS lost foam pattern containing the reinforced particles is prepared, and then the WCp/Fe composite material is prepared by adopting a lost foam casting method. When the surface wear-resistant composite material is manufactured, the prepared lost foam sample containing the reinforced particles is cut according to the shape and size, then is adhered to the surface of the EPS mold sample, and after casting, the wear-resistant surface composite material can be obtained at the position, and the wear-resistant surface composite material is accurate in size and high in yield.
The invention obtains the thickness of the wear-resistant layer equal to the thickness of the lost foam mold through the negative pressure of lost foam casting, and the thickness of the wear-resistant layer can be greatly increased compared with the process of coating the paint on the surface of the pattern.
The invention is suitable for manufacturing the particle reinforced iron-based composite material part product with a complex shape, is suitable for the production of thin-wall or thick iron-based composite material parts, and improves the size accuracy of the iron-based composite material product. The method has the advantages of strong operability, low production cost, high production efficiency, easy realization of industrial production and contribution to energy conservation and consumption reduction.
The WCp/EPS lost foam pattern preparation method and the WCp/Fe composite lost foam casting forming method which is matched and connected with the WCp/EPS lost foam pattern preparation method have the advantages of strong operability, low production cost and high production efficiency, are easy to realize industrial production, especially improve the mechanical property of a target part, prolong the service life of the target part, save energy, reduce consumption and meet the strategic national policy of national sustainable development.
Drawings
FIG. 1 is a flow chart of a method for preparing a WCp/EPS lost foam pattern provided by the invention;
FIG. 2 is a flow chart of a method for casting and forming a WCp/Fe composite material by a lost foam provided by the invention.
Detailed Description
The invention is described in further detail below with reference to the figures and the embodiments.
The invention discloses a WCp/EPS (tungsten carbide/polystyrene) lost foam pattern preparation method and a WCp/Fe composite lost foam casting forming method.
Referring to fig. 1, the invention provides a flow chart of a method for preparing a WCp/EPS lost foam pattern, which is a novel lost foam pattern preparation process technology, and the preparation method mainly adopts WC particles, EPS beads, rare earth powder, an adhesive and other auxiliary materials; the WC particles have excellent physical and chemical properties, and the market of the WC particles as the grinding material is mature, so that the WC powder has more varieties, and the WC particle reinforced cast iron composite material has good application prospects. Therefore, the WC particles provided by the abrasive industry are added into the iron alloy (casting method), and the prepared WC particle reinforced iron-based composite material has the advantages of low cost, suitability for industrial production and the like. The method comprises the following steps:
1) weighing WC particles, rare earth powder, EPS beads and an adhesive in parts by volume, and uniformly mixing the weighed WC particles, rare earth powder, EPS beads and adhesive to complete the preparation of the mixed material.
Wherein, WC particles and EPS beads are used as main materials, and rare earth powder and adhesive are used as auxiliary materials. In the embodiment of the invention, the mixed materials comprise the following components in parts by volume: 5-10 parts of WC particles, 1-2 parts of rare earth powder, 87-92 parts of EPS beads and 2-3 parts of an adhesive, wherein the particle size of the WC particles is 500-2000 meshes.
In the embodiment provided by the invention, firstly, the adhesive is prepared into a melt, then the solution is sprayed on the surface of the EPS beads, then the WC hard alloy particles and the EPS beads are uniformly stirred, and then the uniformly mixed EPS beads are sent into a die by compressed air.
Specifically, the EPS in the embodiment of the present invention refers to Polystyrene foam (Expanded Polystyrene abbreviated as EPS), and is a light polymer. Polystyrene resin is added with foaming agent, and simultaneously heated for softening to generate gas, so that the foamed plastic with a hard closed-cell structure is formed.
WC particles in the examples of the invention are tabulated before compoundingAnd (5) carrying out ultrasonic cleaning on the surface. In the local composite material of the wear-resistant surface of the slurry pump overflowing piece prepared from the WC particles, the complex parts are basically and uniformly compounded, and the erosion and wear resistance of the obtained composite material is improved by about 3 times compared with that of high-chromium cast iron. The tungsten carbide particle reinforced iron-based composite material is obtained by adopting a vacuum negative pressure process, the microstructure of a composite layer is analyzed, the slurry erosion abrasion resistance of the composite layer is investigated by simulating the actual working condition, and the erosion resistance of the obtained composite material is 3-4 times that of high-chromium cast iron. WC particles added to high-chromium cast iron can form some strengthening phases, such as Fe6W6C、C0.055Fe1.943、W2C、Fe7W6And the new strengthening plays a remarkable role in relatively improving the wear resistance of the high-chromium cast iron.
The rare earth powder in the embodiment of the invention adopts rare earth silicon.
2) And preheating the mould, and when the temperature of the mould reaches the working temperature of 100 ℃, starting to fill.
3) And filling the mixed material into a mould by utilizing compressed air, introducing hot steam and simultaneously carrying out pressure maintaining treatment.
Specifically, the mixed material is filled into a die by utilizing compressed air, steam is introduced, and the steam temperature is 120 ℃; the pressure is 0.15-0.25 MPa; determining the pressure maintaining time according to the average thickness of the pattern, wherein the pressure maintaining time is 0.5-10 min. Preparing a WCp/EPS lost foam pattern with the thickness of 3-7mm, wherein the pressure maintaining time of steam heating is 3-5min, and the steam pressure is 0.2 MPa; when a mould with the average thickness of 8-12mm is prepared, the steam pressure is 0.25MPa, and the heating time is 5-10 min.
Compressed air is adopted for filling in the preparation process of the lost foam, and the pressure maintaining treatment can ensure that the beads are further expanded in the mold, so that the density and the integrity of the lost foam pattern are improved. The air pressure parameters are matched with the pressure maintaining time, so that the lost foam pattern meets the quality requirement.
4) And after pressure maintaining is finished, removing the hot steam, spraying water on the back of the die for cooling, quickly cooling the temperature of the die sample to 40-50 ℃, reducing the temperature to be below the softening temperature, shaping the die sample, and demolding to obtain the WCp/EPS lost foam die sample.
The complex pattern is first manufactured in several modules, and then the modules are assembled into an integral pattern, and the integral pattern and the casting system are assembled into a pattern group. Specifically, the complex pattern often cannot be foamed and formed integrally, and needs to be manufactured in blocks, and then all the modules are assembled into the integral pattern. In addition, the pattern and the gating system are assembled into a pattern set. The operation can reduce the requirement on the die, simplify the manufacturing process of the complex pattern and enlarge the application range of the invention.
Further, the WCp/Fe composite material lost foam casting forming method provided by the invention is continued on the basis of firstly preparing the WCp/EPS lost foam pattern; with reference to the flow chart of the method for the evaporative pattern casting forming method of the WCp/Fe composite material, which is shown in FIG. 2 and provided by the invention, the specific method steps are as follows:
1) and the surface of the WCp/EPS pattern is coated with the cast iron lost foam casting coating.
Specifically, in the embodiment provided by the invention, the cast iron coating layer is a commercially mature ZT-1 cast iron coating, and the thickness of the cast iron coating layer is 1.2-1.8 mm.
2) And placing the WCp/EPS pattern coated with the coating into a drying chamber for baking, wherein the baking temperature is 50-55 ℃, and the relative humidity of the drying chamber is less than or equal to 30%.
3) And assembling the boxes, and performing vibration molding by using dry sand.
4) And pouring the cast iron alloy liquid under negative pressure, wherein the negative pressure is 0.03-0.06MPa, the pouring temperature is 1380-1480 ℃, after the pouring is finished, preserving the heat for 2-10 hours, and performing box turning and sand shakeout to obtain the casting.
The concrete pouring process adopts negative pressure pouring, the negative pressure degree is 0.03-0.06MPa, and the pressure is maintained for 10-60 minutes. Taking high-chromium cast iron as an example, the pouring temperature is 1450-.
5) And carrying out heat treatment on the lost foam casting test block, wherein the heating temperature is 1050-1100 ℃, and the heat preservation time is 1-3 h.
In combination with the above, the WCp/EPS lost foam pattern preparation method and the WCp/Fe composite lost foam casting forming method provided by the invention have the overall processes of WCp/EPS composite material pattern preparation process flow, pattern coating drying, WCp/Fe composite material lost foam casting process flow, pouring process, heat treatment process and the like. The method and the process for manufacturing the surface wear-resistant composite material provided by the invention have the advantages that a mould containing the reinforced particles is prepared firstly, the cutting can be carried out according to the shape and the size, then the mould is adhered to the surface of the EPS mould, and the wear-resistant surface composite material can be obtained after the casting, and the target shape and the size of the material are very accurate.
Example one
A WCp/EPS lost foam pattern preparation process comprises the following process steps:
1) weighing 5 parts of WC particles, 1 part of rare earth powder, 92 parts of EPS beads and 2 parts of an adhesive in parts by volume, and uniformly mixing the weighed WC particles, the rare earth powder, the EPS beads and the adhesive to complete the preparation of the mixed material. Wherein, the granularity of WC particles is 500 meshes, and the rare earth powder is rare earth silicon.
2) And preheating the mould, and when the temperature of the mould reaches the working temperature of 100 ℃, starting to fill.
3) Filling the mixed material into a die by utilizing compressed air, and introducing steam, wherein the steam temperature is 120 ℃; the pressure is 0.15 MPa; determining the pressure maintaining time according to the average thickness of the pattern, wherein the pressure maintaining time is 1 min.
4) And after the pressure maintaining is finished, removing the hot steam, spraying water on the back surface of the mold for cooling, quickly cooling the mold to 50 ℃, reducing the temperature to be below the softening temperature, shaping the mold, and demolding.
A WCp/Fe composite material lost foam casting forming method is carried out on the basis of firstly preparing a WCp/EPS lost foam pattern, and the specific method comprises the following steps:
1) and the surface of the WCp/EPS pattern is coated with the cast iron lost foam casting coating.
The cast iron coating layer is a commercially mature ZT-1 cast iron coating, and the thickness of the cast iron coating layer is 1.2 mm.
2) And placing the WCp/EPS pattern coated with the coating into a drying chamber for baking, wherein the baking temperature is 50 ℃, and the relative humidity of the drying chamber is 30%.
Specifically, the coating is coated once in total and dried after being coated.
3) And assembling the boxes, and performing vibration molding by using dry sand.
4) And pouring the cast iron alloy liquid by adopting negative pressure, keeping the negative pressure at 0.03MPa for 60 minutes, keeping the pouring temperature at 1480 ℃, preserving the heat for 10 hours after the pouring is finished, and performing box turning and sand shakeout to obtain the casting.
5) And carrying out heat treatment on the lost foam casting test block, wherein the heating temperature is 1050 ℃, and the heat preservation time is 3 h.
Example two
A WCp/EPS lost foam pattern preparation process comprises the following process steps:
1) weighing 10 parts of WC particles, 2 parts of rare earth powder, 85 parts of EPS beads and 3 parts of an adhesive according to the volume parts, and uniformly mixing the weighed WC particles, the rare earth powder, the EPS beads and the adhesive to complete the preparation of the mixed material. Wherein, the granularity of WC particles is 2000 meshes, and the rare earth powder is rare earth silicon.
2) And preheating the mould, and when the temperature of the mould reaches the working temperature of 100 ℃, starting to fill.
3) Filling the mixed material into a die by utilizing compressed air, and introducing steam, wherein the steam temperature is 120 ℃; the pressure is 0.25 MPa; and determining the pressure maintaining time according to the average thickness of the pattern, wherein the pressure maintaining time is 10 min.
4) And after the pressure maintaining is finished, removing the hot steam, spraying water on the back surface of the mold for cooling, quickly cooling the mold to 40 ℃, reducing the temperature to be below the softening temperature, shaping the mold, and demolding.
A WCp/Fe composite material lost foam casting forming method is carried out on the basis of firstly preparing a WCp/EPS lost foam pattern, and the specific method comprises the following steps:
1) and the surface of the WCp/EPS pattern is coated with the cast iron lost foam casting coating.
The cast iron coating layer is a commercially mature ZT-1 cast iron coating, and the thickness of the cast iron coating layer is 1.8 mm.
2) And placing the WCp/EPS pattern coated with the coating into a drying chamber for baking, wherein the baking temperature is 55 ℃, and the relative humidity of the drying chamber is 25%.
Specifically, the coating is coated twice in total, and is dried after each coating.
3) And assembling the boxes, and performing vibration molding by using dry sand.
4) And pouring the cast iron alloy liquid by adopting negative pressure, keeping the negative pressure at 0.06MPa for 10 minutes at 1380 ℃, keeping the temperature for 2 hours after pouring, turning the box and shakeout to obtain a casting.
5) And carrying out heat treatment on the lost foam casting test block, wherein the heating temperature is 1100 ℃, and the heat preservation time is 1 h.
EXAMPLE III
A WCp/EPS lost foam pattern preparation process comprises the following process steps:
1) weighing 8 parts of WC particles, 1 part of rare earth powder, 89 parts of EPS beads and 2 parts of an adhesive according to the volume parts, and uniformly mixing the weighed WC particles, the rare earth powder, the EPS beads and the adhesive to complete the preparation of the mixed material. Wherein, the granularity of WC particles is 1000 meshes, and the rare earth powder is rare earth silicon.
2) And preheating the mould, and when the temperature of the mould reaches the working temperature of 100 ℃, starting to fill.
3) Filling the mixed material into a die by utilizing compressed air, and introducing steam, wherein the steam temperature is 120 ℃; the pressure is 0.2 MPa; and determining the pressure maintaining time according to the average thickness of the pattern, wherein the pressure maintaining time is 5 min.
4) And after the pressure maintaining is finished, removing the hot steam, spraying water on the back surface of the mold for cooling, quickly cooling the mold to 45 ℃, reducing the temperature to be below the softening temperature, shaping the mold, and demolding.
A WCp/Fe composite material lost foam casting forming method is carried out on the basis of firstly preparing a WCp/EPS lost foam pattern, and the specific method comprises the following steps:
1) and the surface of the WCp/EPS pattern is coated with the cast iron lost foam casting coating.
The cast iron coating layer is a commercially mature ZT-1 cast iron coating, and the thickness of the cast iron coating layer is 1.6 mm.
2) And placing the WCp/EPS pattern coated with the coating into a drying chamber for baking, wherein the baking temperature is 53 ℃, and the relative humidity of the drying chamber is 28%.
Specifically, the coating is coated twice in total, and is dried after each coating.
3) And assembling the boxes, and performing vibration molding by using dry sand.
4) And pouring the cast iron alloy liquid by adopting negative pressure, keeping the pressure for 30 minutes at the negative pressure of 0.05MPa, keeping the temperature for 6 hours after pouring, and performing box turning and sand shakeout to obtain a casting.
5) And carrying out heat treatment on the lost foam casting test block, wherein the heating temperature is 1080 ℃, and the heat preservation time is 2 h.
EXAMPLE four (COMPARATIVE EXAMPLE)
A WCp/EPS lost foam pattern preparation process comprises the following process steps:
1) weighing 15 parts of WC particles, 3 parts of rare earth powder, 80 parts of EPS beads and 2 parts of an adhesive according to the volume parts, and uniformly mixing the weighed WC particles, the rare earth powder, the EPS beads and the adhesive to complete the preparation of the mixed material. Wherein, the granularity of WC particles is 1000 meshes, and the rare earth powder is rare earth silicon.
2) And preheating the mould, and when the temperature of the mould reaches the working temperature of 100 ℃, starting to fill.
3) Filling the mixed material into a die by using compressed air, and introducing steam at the temperature of 125 ℃; the pressure is 0.15 MPa; and determining the pressure maintaining time according to the average thickness of the pattern, wherein the pressure maintaining time is 3 min.
4) And after the pressure maintaining is finished, removing the hot steam, spraying water on the back surface of the mold for cooling, quickly cooling the mold to 40 ℃, reducing the temperature to be below the softening temperature, shaping the mold, and demolding.
A WCp/Fe composite material lost foam casting forming method is carried out on the basis of firstly preparing a WCp/EPS lost foam pattern, and the specific method comprises the following steps:
1) and the surface of the WCp/EPS pattern is coated with the cast iron lost foam casting coating.
The cast iron coating layer is a commercially mature ZT-1 cast iron coating, and the thickness of the cast iron coating layer is 1.2 mm.
2) And placing the WCp/EPS pattern coated with the coating into a drying chamber for baking, wherein the baking temperature is 50 ℃, and the relative humidity of the drying chamber is 30%.
Specifically, the coating is coated once in total and dried after being coated.
3) And assembling the boxes, and performing vibration molding by using dry sand.
4) And pouring the cast iron alloy liquid by adopting negative pressure, keeping the pressure for 15 minutes at the negative pressure of 0.045MPa, keeping the pouring temperature at 1400 ℃, keeping the temperature for 6 hours after pouring, and performing box turning and sand shakeout to obtain a casting.
5) And carrying out heat treatment on the lost foam casting test block, wherein the heating temperature is 900 ℃, and the heat preservation time is 2.5 h.
Experiments combined with comparative examples show that the method provided by the application can accurately control the size of a produced part, the thickness of the wear-resistant layer can reach 3-20mm, the wear-resistant performance is improved by about 3 times, and the thickness and the wear resistance of the wear-resistant layer are both obviously improved.
It should be understood that the above examples are only for clarity of illustration and are not intended to limit the embodiments. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. And obvious variations or modifications therefrom are within the scope of the invention.
Claims (5)
1. A WCp/EPS lost foam pattern preparation method is characterized in that: comprises the following steps of (a) carrying out,
1) weighing WC particles, rare earth powder, EPS beads and an adhesive according to the volume parts, preparing the adhesive into a solution, spraying the solution on the surfaces of the EPS beads, and uniformly stirring the WC particles, the rare earth powder and the EPS beads to complete the preparation of a mixed material; the mixed materials comprise the following components in parts by volume: 5-10 parts of WC particles, 1-2 parts of rare earth powder, 87-92 parts of EPS beads and 2-3 parts of an adhesive; the granularity of WC particles is 2000 meshes; carrying out surface ultrasonic cleaning on WC particles before preparing the mixed material; the rare earth powder adopts rare earth silicon;
2) preheating the mould to the working temperature of 100 ℃;
3) filling the mixed material into a die by utilizing compressed air, and introducing steam, wherein the steam temperature is 120 ℃; preparing a WCp/EPS lost foam pattern with the thickness of 3-7mm, wherein the pressure maintaining time of steam heating is 3-5min, and the steam pressure is 0.2 MPa; or preparing a mold with an average thickness of 8-12mm, steam pressure of 0.25MPa, and steam heating for 5-10 min;
4) and after pressure maintaining is finished, removing the hot steam, spraying water on the back of the die for cooling, quickly cooling the temperature of the die sample to 40-50 ℃, reducing the temperature to be below the softening temperature, shaping the die sample, and demolding to obtain the WCp/EPS lost foam die sample.
2. The WCp/EPS disappearance mould pattern preparation method according to claim 1, characterized by that: the complex pattern is manufactured by dividing the complex pattern into a plurality of modules, then assembling the modules into an integral pattern, and then assembling the integral pattern and a pouring system into a pattern group.
3. A WCp/Fe composite material lost foam casting forming method is characterized in that: the WCp/EPS lost foam pattern prepared by any of claims 1-2, comprising the steps of:
1) coating cast iron lost foam casting coating on the surface of the WCp/EPS pattern; the thickness of the cast iron coating layer is as follows: 1.2-1.8 mm;
2) placing the WCp/EPS pattern coated with the coating into a drying chamber for baking, wherein the baking temperature is 50-55 ℃, and the relative humidity of the drying chamber is less than or equal to 30%;
3) assembling boxes, and performing vibration molding by using dry sand;
4) pouring cast iron alloy liquid in the box at the pouring temperature of 1380-1480 ℃, preserving the heat for 2-10 hours after the pouring is finished, turning the box and shakeout to obtain a casting;
5) and carrying out heat treatment on the lost foam casting test block, wherein the heating temperature is 1050-1100 ℃, and the heat preservation time is 1-3 h.
4. The WCp/Fe composite lost foam casting method of claim 3, wherein: the cast iron coating layer in the step 1) is ZT-1 cast iron coating.
5. The WCp/Fe composite lost foam casting method of claim 3, wherein: and 4) in the step 4), negative pressure casting is adopted, the negative pressure degree is 0.03-0.06MPa, and the pressure is maintained for 10-60 minutes.
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