Search

CN-119819875-B - Coating for casting alloy steel lost foam, preparation method and application

CN119819875BCN 119819875 BCN119819875 BCN 119819875BCN-119819875-B

Abstract

The invention provides a coating for casting an alloy steel lost foam, a preparation method and application thereof, wherein the coating comprises the following raw materials in parts by weight: 79-89 parts of aggregate, 3-7 parts of binder, 4-7 parts of suspending agent, 1.5-3 parts of surfactant, 1.5-2.5 parts of defoamer and 1-1.5 parts of preservative; the aggregate comprises 78-82 wt% of bauxite, 12-15 wt% of mica and 3-10 wt% of quartz powder by mass percent; the binder comprises, by mass, 42-50% of anhydrous aluminum dihydrogen phosphate, 18-25% of white carbon black, 12-17% of ethylene glycol and 8-28% of magnesium oxide; the coating for the lost foam of the cast alloy steel maintains good suspension property, high-temperature air permeability, coating property, high-temperature crack resistance and falling property of the coating, has smooth casting surface, no sand sticking, less volatile harmful gas during firing, and can absorb the harmful gas generated by the combustion of the lost foam.

Inventors

  • WANG CHEN
  • WANG XIAO

Assignees

  • 上海迪升防腐新材料科技有限公司

Dates

Publication Date
20260505
Application Date
20250117

Claims (10)

  1. 1. The coating for the lost foam of the cast alloy steel is characterized by comprising, by weight, 79-89 parts of aggregate, 3-7 parts of binder, 4-7 parts of suspending agent, 1.5-3 parts of surfactant, 1.5-2.5 parts of defoaming agent and 1-1.5 parts of preservative; Wherein the aggregate comprises 78-82wt% of bauxite, 12-15wt% of mica and 3-10wt% of quartz powder by mass percent; the binder comprises, by mass, 42-50wt% of anhydrous aluminum dihydrogen phosphate, 18-25wt% of white carbon black, 12-17wt% of ethylene glycol and 8-28wt% of magnesium oxide; the surfactant is isomeric tridecanol polyoxyethylene ether; the defoaming agent is n-octanol; the preservative comprises, by mass, 25-50wt% of potassium sorbate and 50-75wt% of chitosan.
  2. 2. The coating for casting alloy steel lost foam according to claim 1, wherein the suspending agent comprises, by mass, 35-50wt% of sodium carboxymethyl cellulose, 45-50wt% of sodium bentonite and 10-20wt% of sodium alginate; and/or the bauxite is 220-270 mesh high bauxite, and the Al 2 O 3 content is more than 85%; And/or the mica is 250-270 meshes; and/or the quartz powder is 180-220 meshes; And/or, the white carbon black is nanoscale white carbon black; And/or the anhydrous aluminum dihydrogen phosphate, the white carbon black and the magnesium oxide are all powder.
  3. 3. The method for preparing the coating for casting the alloy steel lost foam according to any one of claims 1 to 2, which is characterized by comprising the following steps: s1, preparing a sodium carboxymethyl cellulose suspension according to a proportioning ratio, preparing a sodium bentonite suspension, and preparing a sodium alginate suspension; s2, mixing and grinding aggregate, anhydrous aluminum dihydrogen phosphate, white carbon black and magnesium oxide according to a mixing proportion to obtain a mixed abrasive; And S3, mixing the three suspensions in the step S1 to obtain a mixed suspension, adding the surfactant, the defoamer, the preservative and the ethylene glycol into the mixed suspension in batches, adding the obtained mixed solution into the mixed abrasive obtained in the step S2 in batches, and uniformly mixing to obtain the coating for the lost foam of the cast alloy steel.
  4. 4. The method for preparing the coating for the lost foam of the cast alloy steel according to claim 3, wherein the concentration of the sodium carboxymethyl cellulose suspension in the step S1 is 2-3 wt%; and/or the concentration of the sodium bentonite suspension in the step S1 is 1.5-2wt%; and/or the concentration of the sodium alginate suspension in the step S1 is 1-1.5wt%.
  5. 5. The method for preparing a coating for a lost foam for casting alloy steel according to claim 3, wherein the sodium carboxymethyl cellulose suspension, the sodium bentonite suspension and the sodium alginate suspension in the step S1 are all deionized water.
  6. 6. The method for preparing the coating for the lost foam of the cast alloy steel according to claim 5, wherein in the step S1, the sodium carboxymethyl cellulose suspension, the sodium bentonite suspension and the sodium alginate suspension are obtained by respectively adding sodium carboxymethyl cellulose, sodium bentonite and sodium alginate into deionized water, respectively mixing into slurry, and foaming.
  7. 7. The method for preparing the coating for the lost foam of the cast alloy steel according to claim 3, wherein bauxite, mica and quartz powder in the aggregate in the step S2 are firstly kept at a temperature of 200-230 ℃ for at least 30min before being mixed, and then are mixed and ground after being cooled in a dry environment.
  8. 8. The method for producing a coating for a lost foam for casting alloy steel according to claim 7, wherein the heat preservation is performed in a high-temperature sintering furnace.
  9. 9. The method for preparing the coating for the lost foam of the cast alloy steel according to claim 3, wherein the grinding in the step S2 is performed in a planetary ball mill, zirconia grinding balls with the diameter of 1.4-1.6 mm and the content of more than 90% are adopted, and the mixed grinding materials are ground for 3-4 hours at the rotating speed of 300-330 revolutions per minute.
  10. 10. The use of the coating for casting an alloy steel lost foam according to any one of claims 1-2 in the field of alloy steel lost foam casting.

Description

Coating for casting alloy steel lost foam, preparation method and application Technical Field The invention relates to the technical field of lost foam coating, in particular to a coating for casting alloy steel lost foam, a preparation method and application thereof. Background Lost foam casting is also called gasification die casting, full mold casting, and the core technology is to replace the original wood die or metal die molding with foamed plastic (EPS, STMMA or EPMMA) polymer material, process and bond with plastic plates or foam with plastic beads to form a die (white die) similar to the size and shape of a casting, dip-coat fireproof paint (with strengthening, smoothing and ventilation effects) and dry, then embed the die in dry quartz sand, and perform three-dimensional vibration molding, and the die is not taken out after molding, so that a solid cavity with the die is established in a sand box. And casting molten metal in a negative pressure state, so that the high polymer material model is heated, gasified and pumped out, and then replaced by liquid metal for cooling, and the required casting is obtained after solidification. Compared with traditional casting modes such as sand casting, the lost foam casting has a series of advantages: (1) The lost foam casting design has large freedom, for parts with complex shapes, the lost foam casting adopts a method of manufacturing a plurality of dies and then bonding to obtain an integral pattern, and finally the integral casting is obtained by molding and pouring without complex core mold and multi-component assembly, thereby greatly reducing the manufacturing cost and difficulty. (2) The lost foam casting can realize near-zero-allowance casting, the material utilization rate can reach more than 95%, the material utilization rate of the traditional casting technology is generally lower, a large amount of waste materials are generated, the surface finish degree and the dimensional accuracy of the casting of the lost foam casting are higher, the internal defects are few, and the workload of subsequent processing and cleaning is reduced. (3) The lost foam casting can reduce or eliminate the manufacturing and maintenance cost of the die, and meanwhile, due to the one-time molding characteristic, the production period can be shortened, and the production efficiency of enterprises can be improved. (4) The casting material has wide selection range, and can be used for casting metal castings such as cast steel, iron castings, aluminum magnesium alloy castings and the like by using the lost foam casting method. Therefore, the lost foam casting technology is widely used in the industries of automobiles, aerospace and the like. Also because of these characteristics, in the lost foam casting process, the coating of the outer layer of the white mold has important effects on the filling of molten metal, the discharge of decomposition products of the pattern and the quality of the casting. The main function of the coating is that the coating is actually used as a casting mould in casting, and the coating has higher refractoriness and chemical stability, certain normal-temperature strength and rigidity for preventing sand sticking and crush, higher air permeability for ensuring timely discharging of gas or liquid products generated by thermal decomposition of a pattern, higher high-temperature strength and high-temperature crack resistance for preventing the coating from crush under high-temperature fluid scouring and back pressure (high-temperature molten metal and white mould gasification products) and preventing the molten metal from penetrating into molding sand to cause sand sticking of castings due to coating cracking. In order to ensure the coating quality, the paint also has good suspension stability, good wettability and adsorptivity, good coating property, good dripping resistance and the like. Production experience has shown that 60% of the reasons for the reject of lost foam castings are due to the paint. The quality of the coating can be marked with an equal sign with the quality of the final casting. The materials frequently used in the lost foam coating on the market at present often contain some environmentally unfriendly raw materials, especially some common organic adhesive agents such as asphalt, coal tar, rosin, phenolic resin and the like, and the raw materials are decomposed at high temperature during sintering and high-temperature casting to generate VOCs harmful gases such as benzene, toluene, styrene, ethylbenzene and the like, and the common surfactant OP-10 can cause adverse effects on the environment, especially is difficult to degrade in water bodies and has potential harm to aquatic organisms. Disclosure of Invention In view of the above-mentioned shortcomings of the prior art, the present invention aims to provide a coating for casting alloy steel lost foam, a preparation method and application thereof, which are used for solving the pro