CN109482813B - WCp/EPS lost foam pattern and preparation of WCp/Fe composites - Google Patents

Abstract

The invention discloses a WCp/EPS lost foam pattern and a WCp/Fe composite material lost foam casting forming process, belonging to the technical field of metal forming. The method for preparing the WCp/EPS lost foam pattern includes the following steps: weighing WC particles, rare earth powder, EPS beads, and binder by volume, and mixing them evenly to complete the preparation of the mixture; preheating the mold, when the mold temperature reaches When the working temperature is 100 °C, start filling; use compressed air to fill the mixture into the mold, and pass hot steam; after the hot steam is released, spray water on the back of the mold for cooling, so that the pattern temperature is quickly cooled to 40 °C ~ 50 °C, Drop below the softening temperature, and after the pattern is set, the mold is released. The process method provided by the invention enables the alloy particles to be firmly bonded to the matrix, the particles are evenly dispersed, the comprehensive mechanical properties of the product are improved, and large-scale and complex-shaped WCp/Fe composite parts can be produced through lost foam casting.

Description

WCp/EPS lost foam pattern and preparation of WCp/Fe composites

technical field

The invention belongs to the technical field of metal forming, and particularly relates to a WCp/EPS lost foam pattern and a lost foam casting forming process of a WCp/Fe composite material.

Background technique

Because WC has excellent physical and chemical properties, and the market of WC particles as abrasive is very mature, especially WCp/Fe composite material is a composite of hard phase WC and iron matrix, so it is most suitable for high stress, high wear and strong impact. working conditions, and because WCp/Fe composites are widely used in practical industrial production due to their low price, excellent high temperature resistance, high-speed wear resistance and good mechanical properties.

The existing WCp/Fe composite materials preparation processes include powder metallurgy, dynamic forming, spray deposition, pressureless infiltration and casting.

Powder metallurgy involves first mixing the base alloy powder 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 or hot rolling) Wait). The process method has the characteristics of arbitrarily adjusting the amount of reinforcement added, accurately controlling the proportion of components, and the like, and the prepared parts are dense, refined, uniform, and have few internal defects. However, the requirements for raw materials are high, the equipment cost is also expensive, and secondary plastic processing of composite materials is required. Therefore, the process of preparing particle-reinforced metal matrix composites by powder metallurgy is complicated, and must be carried out in a sealed, vacuum or protective atmosphere, the required equipment and production costs are high, and the structure and size of the prepared parts are limited.

The dynamic forming method uses the strong shock wave generated by explosion, gas-driven gun or electromagnetic force to act on the powder instantly to make it form. Due to the high pressure impact on the powder, it can cause severe shear deformation between the powder particles and the surface of the particles. Instantaneous melting, resulting in particle cohesion. During the forming process, the energy of the shock wave is mainly consumed on the surface of the particles, while the internal temperature changes little, and the microstructure of the formed blank only changes locally. The advantage of the dynamic forming method is that the particles can retain the metastable state of the powder.

Jet deposition technology is a new type of rapid solidification technology, which is to add reinforcing particles during the liquid metal atomization process, so that the alloy powder and the reinforcing particles are deposited on the collector at the same time. In the process of preparing the iron-based composite material by the method, the contact time between the molten metal and the reinforcing particles is short, so the interface reaction is small, and macroscopic casting defects are unlikely to occur. The prepared composite material has an equiaxed grain structure with good mechanical properties. And the production cycle is short and the molding speed is fast. However, the composite material prepared by this method also has disadvantages, such as the inability of the reinforcing particles to be uniformly distributed, the expensive production equipment, resulting in high production costs, and the low utilization rate of the reinforcing particles.

The casting method refers to introducing reinforcing particles into the metal melt and uniformly dispersing the reinforcing particles in the melt and then casting to form. According to the different dispersion methods, it is divided into mechanical stirring, electromagnetic stirring, ultrasonic vibration treatment, etc. According to the different solid and liquid states of the metal melt, it is divided into liquid stirring and semi-solid stirring. Compared with other methods, the casting method can use traditional casting equipment and devices, and has the advantages of low cost, suitable for industrial production, and the ability to manufacture large and complex parts. The main process method. Including: die casting, reverse pressure casting, squeeze casting, semi-solid casting, etc.

Die casting method refers to filling liquid or semi-liquid metal matrix composite material or metal at a certain speed into the pores of die casting mold cavity or reinforcing material preform under the action of pressure, and rapidly solidifying and forming under the action of pressure to prepare metal matrix composite material. process technology methods. The specific process is as follows: first, pour the metal melt containing the reinforcing material into the preheated mold, and rapidly pressurize (the pressure is about 70~100MPa) to rapidly solidify the metal matrix composite material solution; wait for the composite material to be completely solidified After ejection, the metal matrix composite material blank or die casting of the required shape and size is obtained. Compared with other casting technologies, the surface of die castings is smoother and the dimensional consistency is good, but the air tightness is poor. In comparison, the cost of die-casting equipment and molds is high, so this process method is generally only suitable for mass production.

Reverse pressure casting, also known as differential pressure casting and differential pressure casting, is a casting process method that fills and solidifies and crystallizes under pressure, and has the characteristics of low pressure casting and autoclave casting. The process method can be described as follows: a sealing cover is installed outside the casting mold, compressed air is introduced into the crucible and the sealing cover at the same time, and the pressure in the crucible is controlled to be higher than the pressure in the cover; the molten metal in the crucible is in the pressure difference. Under the action, it is injected into the mold from the bottom of the mold through the riser, and crystallized under the action of pressure. The reverse pressure casting method has the characteristics of stable filling, dense casting structure, stable casting size and good surface quality, but this process method has high requirements on equipment and high investment cost.

Squeeze casting method, squeeze casting is to bond the reinforcing particles in a certain way to form the required reinforcement preform, put the reinforcement preform in the mold, and then pour the liquid metal material into the mold, and then apply A certain pressure makes the solution penetrate into the gap of the preform, and then naturally cools to obtain a composite material of the desired shape. Squeeze casting also has certain shortcomings. (1) Prefabricated parts are not easy to prepare, especially prefabricated parts with complex shapes. (2) The pressure of squeeze casting is not easy to control. If the pressure is too small, the liquid aluminum is not easy to be squeezed in. If the pressure is too high, it is easy to damage the shape of the preform and the quality of the composite material. (3) During the liquid squeeze casting process, the WC particles tend to sink, resulting in uneven distribution of the reinforcement phase. (4) The existing technology cannot solve the problem of the uniformity of WC particle distribution in the preform.

The semi-solid casting method is to add reinforcing particles into a semi-solid metal melt, and uniformly distribute the particles in the matrix material by stirring, so as to achieve good interfacial bonding; Die-cast in a mold. Although the semi-solid casting method is simple in process, it is difficult to control the interface bonding between the reinforcing particles and the base metal melt and the uniformity of particle distribution, and the ratio of the reinforcing particles added has an upper limit.

The lost foam casting surface composite material process is to coat the prepared alloy coating on the casting model made of expandable polystyrene, brush the refractory material and dry it, and then use dry sand to vibrate the model. When the alloy liquid is filled, the foam pattern and the organic binder in the alloyed coating layer are decomposed and gasified when the high temperature alloy liquid is encountered. Under the action of capillary force, negative pressure suction, hydrostatic pressure, etc., the alloy powder penetrates into the gap of the alloy powder, and the alloy powder particles melt, decompose and diffuse, and finally combine with the mother liquid to form a casting with special properties on the surface.

In particular, the patent CN103394671A discloses a preparation process of a lost foam casting high manganese steel wear-resistant surface composite material. The lost foam casting method is used to prepare the surface composite material. The process steps are: preparing a water-based coating and preparing the raw materials for the water-based coating. Selection: SiC particles, ferrochrome powder, rare earth, EPS beads, CMC, weigh SiC particles, ferrochrome powder, rare earth, EPS beads, CMC by weight; The surface of the pattern; put the painted lost foam pattern into the drying room for baking, and after the water-based paint is painted and hung, finally apply the ordinary lost foam cast iron paint and dry it. Group box, dry sand vibration molding; pouring. The surface wear-resistant composite material prepared by this process has a surface composite layer thickness of 3-4 mm. However, in this technical solution, since the technical process is to apply paint on the surface of the pattern, the surface paint layer and the metal liquid undergo metallurgical reaction to form a surface composite material layer, that is, a part of the part. However, when the pattern is coated with paint, because the thickness of the paint is difficult to accurately control, the size of the parts cannot be accurately controlled, so it brings great difficulties to mass production, and the thickness of the wear-resistant layer cannot be made too thick. The thickness of the grinding layer is usually only 3-5mm.

SUMMARY OF THE INVENTION

The purpose of the present invention is 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, low cost, firm bonding between alloy particles and matrix, uniform particle dispersion The comprehensive mechanical properties of the parts are improved, and the method can produce large and complex WCp/Fe composite parts.

In order to achieve the above object, the technical scheme adopted in the present invention is:

A method for preparing a WCp/EPS lost foam pattern, comprising the following steps:

1) Weigh WC particles, rare earth powder, EPS beads, and binder by volume, and mix the weighed WC particles, rare earth powder, EPS beads, and binder evenly to complete the preparation of the mixture;

2) Preheat the mold to a working temperature of 100°C;

3) Use compressed air to fill the mixture into the mold, pass hot steam to the mold, and carry out pressure-holding treatment at the same time;

4) After the pressure holding is over, release the hot steam, spray water on the back of the mold for cooling, so that the temperature of the pattern is quickly cooled to 40 ° C ~ 50 ° C, below the softening temperature, the pattern is set and then the mold is released to obtain WCp/EPS disappear model.

A further improvement of the technical solution of the present invention is that the rare earth powder in step 1) adopts rare earth silicon.

A further improvement of the technical solution of the present invention is that the volume fractions of the mixture in step 1) are: 5-10 parts of WC particles, 1-2 parts of rare earth powder, 87-92 parts of EPS beads, and 2-3 parts of binder.

A further improvement of the technical solution of the present invention is that: the particle size of the WC particles in step 1) is 500-2000 mesh.

A further improvement of the technical solution of the present invention is that: in step 3), the temperature of the hot steam is 120° C., the air pressure is 0.15-0.25 MPa, and the ventilation and pressure-holding time in the mold is 0.5-10 min.

A further improvement of the technical solution of the present invention is that the complex pattern is first manufactured in multiple modules, and then each module is assembled into an overall pattern, and the overall pattern and the gating system are assembled into a pattern group.

A WCp/Fe composite lost foam casting forming method adopts the WCp/EPS lost foam pattern prepared by any one of claims 1-5, and the specific steps are:

1) The surface of WCp/EPS pattern is coated with cast iron lost foam casting paint;

2) Put the painted WCp/EPS pattern into the drying room for baking, the baking temperature is 50-55 ℃, and the relative humidity of the drying room is less than or equal to 30%;

3), group box, vibrate with dry sand;

4), pour the cast iron alloy liquid in the box, the pouring temperature is 1380-1480 ℃, keep the temperature for 2-10 hours after pouring, turn the box, drop the sand, and get the casting;

5) Heat treatment for the lost foam casting test block, the heating temperature is 1050℃-1100℃, and the holding time is 1-3h.

A further improvement of the technical solution of the present invention is that in step 1), the thickness of the cast iron coating layer is: 1.2-1.8 mm.

A further improvement of the technical solution of the present invention is: in step 1), the cast iron paint layer is ZT-1 cast iron paint.

A further improvement of the technical solution of the present invention is that: in step 4), negative pressure is used for pouring, the degree of negative pressure is 0.03-0.06MPa, and the pressure is maintained for 10-60 minutes.

Owing to having adopted the above-mentioned technical scheme, the technical effects obtained by the present invention are as follows:

The method for preparing WCp/EPS lost foam pattern and the lost foam casting forming method for WCp/Fe composite material provided by the invention have high production efficiency, low cost, firm bonding between alloy particles and matrix, uniform particle dispersion, and significantly improved parts integration. Mechanical properties, this method can make large and complex WCp/Fe composite parts.

Rare earth elements have a large solid solubility in silicon, and rare earth silicon has a large rare earth content, and has good solid solution strengthening and precipitation strengthening effects on products, which can effectively improve the alloy structure and microstructure, and improve the room temperature and high temperature mechanics of the alloy. performance, enhanced alloy corrosion resistance and heat resistance, etc. At the same time, rare earth elements have a good aging strengthening effect, and can precipitate very stable dispersed phase particles, which can greatly improve high temperature strength and creep resistance. After the addition of rare earth silicon, the tensile strength and elongation of the alloy were significantly improved, and with the increase of the rare earth silicon content, it first increased and then decreased. When the mass fraction of rare earth silicon is about 1.5%, the microstructure refinement effect of the alloy is the best, and the tensile strength reaches the maximum value.

The present invention mainly uses raw materials such as WC particles, rare earth powder, additives, EPS beads, etc., and the WC particles have a wide source. The hard phase WC particles are evenly distributed in the iron matrix, which plays a role in dispersion strengthening. At the same time, as a hard phase, the WC particles share the external load and reduce the wear effect on the iron matrix. EPS beads have a certain compressive strength to ensure that the WC particles do not collapse and agglomerate before mixing into the molten iron, and at the same time have good volatility to ensure that they can quickly vaporize and disappear after interacting with the high-temperature molten iron.

The volume ratio of WC particles, rare earth powder, EPS beads, and binder makes the WC in the preformed pattern well supported by the EPS beads, and the WC particles can be evenly distributed in the space dominated by the EPS beads without segregation.

Compressed air is used for filling during the preparation of the lost foam pattern, which can ensure that the mixed material is evenly filled in the mold; the pressure-holding treatment can ensure that the beads are further expanded in the mold and improve the density and integrity of the lost foam pattern. The air pressure parameters and the pressure holding time are matched with each other to ensure that the lost foam pattern meets the quality requirements.

The complex pattern can be manufactured in a plurality of modules, and then assembled to form an overall pattern, which reduces the requirements for the mold, simplifies the manufacturing process of the complex pattern, and expands the scope of application of the present invention.

The lost foam pattern preparation method and the composite material lost foam casting forming method provided by the present invention are a set of complete processes. First, the WCp/EPS lost foam pattern containing reinforcing particles is prepared, and then the lost foam casting method is used to prepare the WCp/Fe composite material. This process can produce not only integral composite parts, but also wear-resistant surface composite parts. When making surface wear-resistant composite materials, it is only necessary to cut the prepared disappearing pattern containing reinforcing particles according to the shape and size, and then bond it to the surface of the EPS pattern. After pouring, the wear-resistant surface composite material can be obtained here. , and the size is accurate and the yield is high.

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 can greatly increase the thickness of the wear-resistant layer compared with the process of coating the surface of the pattern.

The invention is suitable for the manufacture of particle-reinforced iron-based composite material parts with complex shapes, for the production of thin-walled or thick iron-based composite material parts, and improves the dimensional accuracy of the iron-based composite material products. The invention has strong operability, low production cost, high production efficiency, is easy to realize industrialized production, and is beneficial to energy saving and consumption reduction.

The WCp/EPS lost foam pattern preparation method and the WCp/Fe composite lost foam casting forming method provided by the invention have strong operability, low production cost, high production efficiency, easy to realize industrialized production, especially improved The mechanical properties of the target parts, prolong the service life of the target parts, save energy and reduce consumption, in line with the national strategy of sustainable development.

Description of drawings

Fig. 1 is the method flow chart of a kind of WCp/EPS lost foam pattern preparation method provided by the present invention;

Fig. 2 is a method flow chart of a lost foam casting forming method of a WCp/Fe composite material provided by the present invention.

Detailed ways

The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

The invention discloses a method for preparing a WCp/EPS lost foam pattern and a WCp/Fe composite material lost foam casting forming method. The method is used for preparing the lost foam pattern and iron-based composite material casting.

1, the method flow chart of a method for preparing a WCp/EPS lost foam pattern provided by the present invention is a new process technology for the preparation of a lost foam pattern, and the preparation method mainly adopts WC particles and EPS beads. And rare earth powder, binder and other auxiliary materials; WC particles have excellent physical and chemical properties, because the market of WC particles as abrasives is very mature, so that there are many varieties of WC powder, and WC particles reinforced cast iron composite materials have good application prospects. Therefore, the WC particles provided by the abrasive industry are added to the iron alloy (casting method), and the prepared WC particle-reinforced iron-based composite material has the advantages of low cost and suitability for industrial production. The method includes the following steps:

1) Weigh WC particles, rare earth powder, EPS beads, and binder by volume, and mix the weighed WC particles, rare earth powder, EPS beads, and binder evenly to complete the preparation of the mixture.

Among them, WC particles and EPS beads are the main materials, and rare earth powder and binder are auxiliary materials. In the embodiment of the present invention, the volume fractions of the mixture are: 5-10 parts of WC particles, 1-2 parts of rare earth powder, 87-92 parts of EPS beads, 2-3 parts of binder, and the particle size of WC particles. For 500-2000 mesh.

In the embodiment provided by the present invention, first, the binder is prepared into a molten liquid, then the solution is sprayed on the surface of the EPS beads, and then the WC cemented carbide particles and the EPS beads are stirred evenly, and then compressed air is used to The mixed EPS beads are sent into the mold.

Specifically, the EPS in the embodiments of the present invention refers to expanded polystyrene (EPS for short), which is a light-weight high molecular polymer. It is a foamed plastic with a rigid closed-cell structure by adding a foaming agent to polystyrene resin, and heating it to soften it to generate gas.

The surface of the WC particles in the examples of the present invention is ultrasonically cleaned before the preparation of the mixture. In the local composite material of the wear surface of the slurry pump overflow part prepared by the WC particles in the embodiment of the present invention, the uniform composite of complex parts is basically realized, and the erosion and wear resistance of the obtained composite material is nearly improved compared with high-chromium cast iron. 3 times. The tungsten carbide particle reinforced iron matrix composite material was obtained by vacuum negative pressure process, the microstructure of the composite layer was analyzed, and the actual working conditions were simulated to investigate the slurry erosion resistance of the composite layer. The obtained composite material has high erosion resistance. 3 to 4 times that of chrome cast iron. The addition of WC particles to high-chromium cast iron can form some strengthening phases, such as new hard phases such as Fe ₆ W ₆ C, C _0.055 Fe _1.943 , W ₂ C, Fe ₇ W ₆ , etc. These new strengthening relatively improve high-chromium cast iron. The wear resistance plays a significant role.

The rare earth powder in the embodiment of the present invention adopts rare earth silicon.

2), preheat the mold, when the mold temperature reaches the working temperature of 100 ℃, start filling.

3), use compressed air to fill the mixture into the mold, and pass hot steam, and at the same time carry out pressure-holding treatment.

Specifically, the mixed material is filled into the mold with compressed air, steam is passed through, the steam temperature is 120 ° C; the pressure is 0.15-0.25 MPa; the pressure-holding time is determined by the average thickness of the pattern, and the pressure-holding time is 0.5-10min. In the preparation of WCp/EPS lost foam patterns with a thickness of 3-7mm, the pressure holding time of steam heating is 3-5min, and the steam pressure is 0.2MPa; in the preparation of patterns with an average thickness of 8-12mm, the steam pressure is 0.25MPa, and the heating time is 5. -10min.

Compressed air is used for filling in the preparation process of the lost foam, and the pressure-holding treatment can ensure that the beads are further expanded in the mold and improve the density and integrity of the lost foam pattern. The air pressure parameters and the pressure holding time are matched with each other to ensure that the lost foam pattern meets the quality requirements.

4) After the pressure holding is over, release the hot steam, spray water on the back of the mold for cooling, so that the temperature of the pattern is quickly cooled to 40 ° C ~ 50 ° C, below the softening temperature, the pattern is set and then the mold is released to obtain WCp/EPS disappear model.

The complex pattern is first manufactured in multiple modules, and then each module is assembled into an overall pattern, and the overall pattern and the gating system are assembled into a pattern group. Specifically, for complex patterns, it is often impossible to integrally foam and form, and it needs to be manufactured in blocks, and then each module is assembled into an overall pattern. In addition, patterns and gating systems are assembled into pattern sets. This operation can reduce the requirements for the mold, simplify the manufacturing process of complex patterns, and expand the scope of application of the present invention.

Further, the lost foam casting forming method of a WCp/Fe composite material provided by the present invention continues on the basis of first preparing the lost foam pattern of WCp/EPS; combined with a WCp/Fe composite material provided by the present invention shown in FIG. 2 . The method flow chart of the material lost foam casting forming method, the specific method steps are as follows:

1) The surface of WCp/EPS pattern is coated with cast iron lost foam casting paint.

Specifically, in the embodiment provided by the present invention, the cast iron paint layer adopts the mature ZT-1 cast iron paint on the market, and the thickness of the cast iron paint layer is 1.2-1.8 mm.

2) Put the painted WCp/EPS pattern into the drying room for baking, the baking temperature is 50-55 ℃, and the relative humidity of the drying room is less than or equal to 30%.

3), group box, use dry sand to vibrate and shape.

4) Pour cast iron alloy liquid under negative pressure, the degree of negative pressure is 0.03-0.06MPa, the pouring temperature is 1380-1480 ℃, the temperature is kept for 2-10 hours after pouring, the box is turned over, the sand is dropped, and the casting is obtained.

The specific casting process adopts negative pressure casting, the degree of negative pressure 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 1450-1470°C, the negative pressure is 0.03MPa, the pressure is maintained for 15 minutes, the heat preservation is performed for 3 hours after pouring, the box is turned over, and the sand is dropped to obtain the test block.

5) Heat treatment for the lost foam casting test block, the heating temperature is 1050℃-1100℃, and the holding time is 1-3h.

In combination with the above, the present invention provides a method for preparing a WCp/EPS lost foam pattern and a method for forming a WCp/Fe composite material by lost foam casting. Dry and lost foam casting WCp/Fe composite material process flow, pouring process, heat treatment process, etc. The method and process for making the surface wear-resistant composite material provided by the present invention needs to first prepare a pattern containing reinforcing particles, which can also be cut according to the shape and size, and then adhere to the surface of the EPS pattern. Surface composite material and conform to the target shape and size of the material with great precision.

Example 1

A process for preparing a WCp/EPS lost foam pattern, comprising the following process steps:

1) Weigh 5 parts of WC particles, 1 part of rare earth powder, 92 parts of EPS beads, and 2 parts of binder by volume, and mix the weighed WC particles, rare earth powder, EPS beads, and binder evenly, Complete mix preparation. Wherein, the particle size of the WC particles is 500 meshes, and the rare earth powder is rare earth silicon.

2), preheat the mold, when the mold temperature reaches the working temperature of 100 ℃, start filling.

3) Use compressed air to fill the mixed material into the mold, pass steam, the steam temperature is 120 ℃; the pressure is 0.15MPa; the pressure-holding time is determined by the average thickness of the pattern, and the pressure-holding time is 1min.

4) After the pressure holding is over, release the hot steam, spray water on the back of the mold for cooling, so that the temperature of the pattern is quickly cooled to 50°C and below the softening temperature. After the pattern is set, the mold is released.

A WCp/Fe composite lost foam casting forming method is carried out on the basis of first preparing the WCp/EPS lost foam pattern. The specific method steps are as follows:

1) The surface of WCp/EPS pattern is coated with cast iron lost foam casting paint.

The cast iron paint layer adopts the mature ZT-1 cast iron paint on the market, and the thickness of the cast iron paint layer is 1.2mm.

2) Put the coated WCp/EPS pattern into the drying room for baking, the baking temperature is 50℃, and the relative humidity of the drying room is 30%.

Specifically, the paint should be brushed once in total, and it should be dried after painting.

3), group box, use dry sand to vibrate and shape.

4) Cast the cast iron alloy liquid with negative pressure, the negative pressure is 0.03MPa, the pressure is maintained for 60 minutes, the pouring temperature is 1480℃, the heat preservation is 10 hours after pouring, the box is turned over and the sand is dropped to obtain the casting.

5) Heat treatment of the lost foam casting test block at a heating temperature of 1050°C and a holding time of 3h.

Embodiment 2

A process for preparing a WCp/EPS lost foam pattern, comprising the following process steps:

1) Weigh 10 parts of WC particles, 2 parts of rare earth powder, 85 parts of EPS beads, and 3 parts of binder by volume, and mix the weighed WC particles, rare earth powder, EPS beads, and binder evenly, Complete mix preparation. Wherein, the particle size of the WC particles is 2000 meshes, and the rare earth powder is rare earth silicon.

2), preheat the mold, when the mold temperature reaches the working temperature of 100 ℃, start filling.

3) Use compressed air to fill the mixed material into the mold, pass steam, the steam temperature is 120 ℃; the pressure is 0.25MPa; the pressure holding time is determined by the average thickness of the pattern, and the pressure holding time is 10min.

4) After the pressure holding is over, release the hot steam, spray water on the back of the mold for cooling, so that the temperature of the pattern is quickly cooled to 40°C and below the softening temperature. After the pattern is set, the mold is released.

A WCp/Fe composite lost foam casting forming method is carried out on the basis of first preparing the WCp/EPS lost foam pattern. The specific method steps are as follows:

1) The surface of WCp/EPS pattern is coated with cast iron lost foam casting paint.

The cast iron paint layer adopts the mature ZT-1 cast iron paint on the market, and the thickness of the cast iron paint layer is 1.8mm.

2) Put the coated WCp/EPS pattern into the drying room for baking, the baking temperature is 55 ℃, and the relative humidity of the drying room is 25%.

Specifically, the paint should be brushed twice in total, and it should be dried after each application.

3), group box, use dry sand to vibrate and shape.

4) Use negative pressure to pour cast iron alloy liquid, the negative pressure is 0.06MPa, the pressure is maintained for 10 minutes, the pouring temperature is 1380 ° C, the heat preservation is 2 hours after the pouring, the box is turned over, the sand is dropped, and the casting is obtained.

5) Heat treatment of the lost foam casting test block at a heating temperature of 1100°C and a holding time of 1h.

Embodiment 3

A process for preparing a WCp/EPS lost foam pattern, comprising the following process steps:

1) Weigh 8 parts of WC particles, 1 part of rare earth powder, 89 parts of EPS beads, and 2 parts of binder by volume, and mix the weighed WC particles, rare earth powder, EPS beads, and binder evenly, Complete mix preparation. Wherein, the particle size of the WC particles is 1000 meshes, and the rare earth powder is rare earth silicon.

2), preheat the mold, when the mold temperature reaches the working temperature of 100 ℃, start filling.

3) Use compressed air to fill the mixed material into the mold, pass steam, the steam temperature is 120 ℃; the pressure is 0.2MPa; the pressure-holding time is determined by the average thickness of the pattern, and the pressure-holding time is 5min.

4) After the pressure holding is over, release the hot steam, spray water on the back of the mold for cooling, so that the temperature of the pattern is quickly cooled to 45°C and below the softening temperature. After the pattern is set, the mold is released.

A WCp/Fe composite lost foam casting forming method is carried out on the basis of first preparing the WCp/EPS lost foam pattern. The specific method steps are as follows:

1) The surface of WCp/EPS pattern is coated with cast iron lost foam casting paint.

The cast iron paint layer adopts the mature ZT-1 cast iron paint on the market, and the thickness of the cast iron paint layer is 1.6mm.

2) Put the coated WCp/EPS pattern into the drying room for baking, the baking temperature is 53 ℃, and the relative humidity of the drying room is 28%.

Specifically, the paint should be brushed twice in total, and it should be dried after each application.

3), group box, use dry sand to vibrate and shape.

4) Cast the cast iron alloy liquid with negative pressure, the negative pressure is 0.05MPa, the pressure is maintained for 30 minutes, the pouring temperature is 1420℃, the heat preservation is 6 hours after the pouring, the box is turned over and the sand is dropped to obtain the casting.

5) Heat treatment of the lost foam casting test block at a heating temperature of 1080°C and a holding time of 2h.

Example four (comparative example)

A process for preparing a WCp/EPS lost foam pattern, comprising the following process steps:

1) Weigh 15 parts of WC particles, 3 parts of rare earth powder, 80 parts of EPS beads, and 2 parts of binder by volume, and mix the weighed WC particles, rare earth powder, EPS beads, and binder evenly, Complete mix preparation. Wherein, the particle size of the WC particles is 1000 meshes, and the rare earth powder is rare earth silicon.

2), preheat the mold, when the mold temperature reaches the working temperature of 100 ℃, start filling.

3) Use compressed air to fill the mixed material into the mold, pass steam, the steam temperature is 125 ℃; the pressure is 0.15MPa; the pressure-holding time is determined by the average thickness of the pattern, and the pressure-holding time is 3min.

4) After the pressure holding is over, release the hot steam, spray water on the back of the mold for cooling, so that the temperature of the pattern is quickly cooled to 40°C and below the softening temperature. After the pattern is set, the mold is released.

A WCp/Fe composite lost foam casting forming method is carried out on the basis of first preparing the WCp/EPS lost foam pattern. The specific method steps are as follows:

1) The surface of WCp/EPS pattern is coated with cast iron lost foam casting paint.

The cast iron paint layer adopts the mature ZT-1 cast iron paint on the market, and the thickness of the cast iron paint layer is 1.2mm.

2) Put the coated WCp/EPS pattern into the drying room for baking, the baking temperature is 50℃, and the relative humidity of the drying room is 30%.

Specifically, the paint should be brushed once in total, and it should be dried after painting.

3), group box, use dry sand to vibrate and shape.

4) Cast the cast iron alloy liquid with negative pressure, the negative pressure is 0.045MPa, the pressure is maintained for 15 minutes, the pouring temperature is 1400℃, the heat preservation is 6 hours after the pouring, the box is turned over and the sand is dropped to obtain the casting.

5) Heat treatment of the lost foam casting test block at a heating temperature of 900°C and a holding time of 2.5h.

Experiments combined with the comparative examples show that the size of the production parts can be accurately controlled according to the method provided in the present application, the thickness of the wear-resistant layer can reach 3-20mm, the wear-resistance performance is improved by about 3 times, and the thickness of the wear-resistant layer and the wear resistance can be improved. were significantly improved.

Obviously, the above-mentioned embodiments are only examples for clear description, and are not intended to limit the implementation manner. For those of ordinary skill in the art, changes or modifications in other different forms can also be made on the basis of the above description. There is no need and cannot be exhaustive of all implementations here. And the obvious changes or changes derived from this are still within the protection scope of the present 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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