阅读说明：本技术 一种生铁熔模铸造用粘结剂的制备方法 (Preparation method of binder for pig iron investment casting ) 是由 江进华 于 2019-09-29 设计创作，主要内容包括：本发明公开了一种生铁熔模铸造用粘结剂的制备方法,具体涉及铸造领域,利用本发明粘结剂制备的型壳不仅具有较高的力学性能,同时其透气性良好,在铸造时可以顺利排出气体,避免铸件产生气孔、浇不足等缺陷；本发明将宝珠砂反复焙烧淬火,制备成微米级别的颗粒,与改性膨润土制备成膨润土-宝珠砂复合物,其依靠改性膨润土接枝的1,4-萘二甲酸与宝珠砂表面的羟基发生反应,从而有机结合起来,得到的膨润土-宝珠砂复合物不仅具有较好的韧性和流动性,其粘结性能较好,同时其热膨胀系数较低,在型壳焙烧后,增强型壳的抗弯强度。(The invention discloses a preparation method of a binder for pig iron investment casting, and particularly relates to the field of casting, wherein a shell prepared by using the binder has high mechanical property and good air permeability, can smoothly discharge gas during casting, and avoids the defects of air holes, insufficient casting and the like of a casting; the bentonite-jewel sand composite obtained by organically combining the bentonite-jewel sand composite prepared by repeatedly roasting and quenching jewel sand to prepare micron-level particles and modified bentonite has the advantages of better toughness and fluidity, better bonding property and lower thermal expansion coefficient, and the bending strength of a shell is enhanced after the shell is roasted.)

1. The preparation method of the binder for pig iron investment casting is characterized by comprising the following steps:

(1) 20-25 parts of Baozhu sand by weight are put into a roasting furnace, roasted for 3-5h at the temperature of 300-;

(2) carrying out modification treatment on 30-35 parts of sodium bentonite to obtain modified bentonite;

(3) adding 30-35 parts of modified bentonite obtained in the step (2) into deionized water with the volume 5-7 times that of the modified bentonite, then adding 5-8 parts of copper sulfate, 15-20 parts of 1, 4-naphthalenedicarboxylic acid and 20-25 parts of Baozhu sand obtained in the step (1), stirring for 15-20min at the temperature of 50-60 ℃ and the speed of 200-230rpm, transferring into a reaction kettle, reacting for 12-15h at the temperature of 155-160 ℃, cooling, filtering, washing and drying to obtain a bentonite-Baozhu sand compound;

(4) adding 30-40 parts of bentonite-Baozhu sand compound obtained in the step (3) into deionized water with the volume 5-10 times of that of the bentonite-Baozhu sand compound, adding 5-10 parts of sodium carboxymethylcellulose, stirring and dispersing at 40-50 ℃ and 300-400rpm for 20-30min, then adding 80-120 parts of zirconium oxychloride ethanol solution, heating to 75-78 ℃, then dropwise adding 3-5% by mass of sodium hydroxide solution until no precipitate is generated, then adding shell powder and polyvinyl alcohol into the solution, and continuously stirring for 20-30min to obtain the modified zirconium dioxide sol.

2. The method for preparing the binder for pig iron investment casting according to claim 1, wherein the modified bentonite in the step (2) is prepared by the following steps: 30-35 parts of sodium bentonite is placed in a ball milling tank, deionized water is added for ball milling for 15-20min, then 8-12 parts of brominated 1-ethyl-3-methylimidazole is added, reflux reaction is carried out for 7-10h at the temperature of 102 ℃ and 105 ℃ and at the speed of 200rpm and 300rpm under the protection of nitrogen, then cooling, filtering and drying at the temperature of 40-50 ℃ after washing are carried out, thus obtaining the modified bentonite.

3. The method for preparing the binder for investment casting pig iron according to claim 1, wherein the mass fraction of the ethanol solution of zirconium oxychloride in the step (4) is 8-12%.

Technical Field

The invention belongs to the technical field of casting, and particularly relates to a preparation method of a binder for pig iron investment casting.

Background

Investment casting, which is a simple near-forming process, can be used for producing castings with high precision and complex shapes, usually adopts fusible materials to prepare fusible models, then refractory coatings and sand spraying are coated for a plurality of times to prepare shells, the shells are formed by procedures of drying, hardening and the like, the wax models are melted off by steam or hot water, then the shells are placed in a furnace for high-temperature roasting, the roasted shells are taken out, after being cooled, high-temperature molten metal is poured into the shells, and the required castings are obtained after the shells are removed. The binder is a main raw material for preparing the investment casting coating, not only influences the surface quality of a shell and a casting, but also has great influence on the whole investment casting production period and cost.

Patent (publication No. CN 106955966B) discloses an inorganic binder for casting and a preparation method thereof, wherein the preparation method comprises the step of adding methyl silicate, methyl silicone oil or sodium alkyl benzene sulfonate and sodium tripolyphosphate or sodium hexametaphosphate into sodium silicate or sodium potassium silicate at the temperature of 45 ~ 65 ℃ until a system is clear, but the strength of a shell prepared by the inorganic binder needs to be improved, the air permeability is poor, and the service performance of the shell is influenced.

Disclosure of Invention

In view of the above problems, the present invention aims to provide a method for preparing a binder for investment casting of pig iron.

The invention is realized by the following technical scheme:

the preparation method of the binder for the pig iron investment casting specifically comprises the following steps:

(1) 20-25 parts of Baozhu sand by weight are put into a roasting furnace, roasted for 3-5h at the temperature of 300-;

(2) carrying out modification treatment on 30-35 parts of sodium bentonite to obtain modified bentonite;

(3) adding 30-35 parts of modified bentonite obtained in the step (2) into deionized water with the volume 5-7 times that of the modified bentonite, then adding 5-8 parts of copper sulfate, 15-20 parts of 1, 4-naphthalenedicarboxylic acid and 20-25 parts of Baozhu sand obtained in the step (1), stirring for 15-20min at the temperature of 50-60 ℃ and the speed of 200-230rpm, transferring into a reaction kettle, reacting for 12-15h at the temperature of 155-160 ℃, cooling, filtering, washing and drying to obtain a bentonite-Baozhu sand compound;

(4) adding 30-40 parts of bentonite-Baozhu sand compound obtained in the step (3) into deionized water with the volume 5-10 times of that of the bentonite-Baozhu sand compound, adding 5-10 parts of sodium carboxymethylcellulose, stirring and dispersing at 40-50 ℃ and 300-400rpm for 20-30min, then adding 80-120 parts of zirconium oxychloride ethanol solution, heating to 75-78 ℃, then dropwise adding 3-5% by mass of sodium hydroxide solution until no precipitate is generated, then adding shell powder and polyvinyl alcohol into the solution, and continuously stirring for 20-30min to obtain the modified zirconium dioxide sol.

Further, the preparation method of the modified bentonite in the step (2) comprises the following steps: 30-35 parts of sodium bentonite is placed in a ball milling tank, deionized water is added for ball milling for 15-20min, then 8-12 parts of brominated 1-ethyl-3-methylimidazole is added, reflux reaction is carried out for 7-10h at the temperature of 102 ℃ and 105 ℃ and at the speed of 200rpm and 300rpm under the protection of nitrogen, then cooling, filtering and drying at the temperature of 40-50 ℃ after washing are carried out, thus obtaining the modified bentonite.

Further, the mass fraction of the ethanol solution of zirconium oxychloride in the step (4) is 8-12%.

The invention has the beneficial effects that: the shell prepared by the binder has high mechanical property and good air permeability, can smoothly discharge gas during casting, and avoids the defects of air holes, insufficient casting and the like of a casting; according to the invention, the Baozhu sand is repeatedly roasted and quenched to prepare micron-level particles, the micron-level particles and the modified bentonite are prepared into a bentonite-Baozhu sand compound, the 1, 4-naphthalene dicarboxylic acid grafted by the modified bentonite reacts with hydroxyl on the surface of the Baozhu sand, so that the bentonite-Baozhu sand compound is organically combined, the obtained bentonite-Baozhu sand compound not only has better toughness and fluidity, but also has better bonding property, and meanwhile, the thermal expansion coefficient is lower, and after the shell is roasted, the bending strength of the shell is enhanced; the sodium bentonite is modified by brominated 1-ethyl-3-methylimidazole, 1-ethyl-3-methylimidazole cations enter between bentonite layers to enlarge the space between the bentonite layers, then added copper ions are complexed with nitrogen and oxygen atoms in 1-ethyl-3-methylimidazole and 1, 4-naphthalene dicarboxylic acid to obtain the modified bentonite, the space between the layers is further enlarged, and the adsorption and bonding properties are remarkably improved, so that the bonding properties of the binder are enhanced. The air permeability of the obtained shell is obviously improved by adding the shell powder.

Detailed Description

The invention is illustrated by the following specific examples, which are not intended to be limiting.