CN102366812A - Preparation method for sodium silicate sand used for casting - Google Patents

Abstract

The invention discloses a preparation method for sodium silicate sand used for casting. The method comprises the steps of preparing modified sodium silicate and preparing molding sand, wherein, the modified sodium silicate is prepared by using a composite modifier which comprises 35 to 50% of talcum powder, 6 to 12% of starch, 14 to 18% of polypropylene glycol and 25 to 35% of nanometer alumina powder on the basis of the total amount of the composite modifier. The molding sand in the invention enhances strength and improves collapsibility of the sodium silicate sand.

Description

A kind of preparation method of casting water glass sand

Technical field

The present invention relates to casting field, particularly water-glass sand sand casting field.

Background technology

Waterglass is nontoxic, tasteless, the green casting inorganic binder that a kind of people know, ancient moulding, coremaking is used, and introduces Foundry Production from the 1950's and (referring to BP, GB782205), has had the applicating history in more than 50 year so far.The water-glass sand serviceability is superior flexibly, but both also coremaking of mouldable, CO the earliest ₂The gas hardening cold core box process should belong to waterglass-CO ₂Method.But, CO ₂The greatest problem that the petrifying water glass sand exists is that cast back collapsibility is poor, and cast cleaning and old sand reuse difficulty have seriously hindered applying of it.

Compare with resin bonded sand mould; Many problems such as low modulus water glass sand exists that intensity is low, moisture resistance is poor, collapsibility is bad, cast cleaning and regenerating used reuse difficulty; Perplexing founder author's time of decades always, also do not solved preferably so far.

For solving the problems referred to above that low modulus water glass sand exists, China carried out a large amount of scientific research work to water-glass sand, but has not made a breakthrough yet in considerable time.Reason is that people attempt under low modulus sodium silicate addition condition with higher, to solve the problem of existence through adding accrete ways such as defeated and dispersed dose of various organic or inorganics, but produce little effect.Russia Р у с и н а В. В. wait the people to propose, in the waterglass compound of modulus≤2.0, add the accrete way of cinder, can make the adhesion strength of waterglass improve 5～10 times, because the modulus of the waterglass that adopts is too low, Na ₂O content is too high, is not suitable for foundary industry, and only is widely used in building trade.Japan two Yu rise people such as U.S.A and adopt heating using microwave to improve the intensity of sodium silicate sand core; Waterglass addition in the sand is reduced to 1%～2%; Reach the purpose of improving sodium silicate sand collapsibility, but the moisture resistance of the core of microwave irradiation is relatively poor, fails aborning to be applied.People such as Russia Ж у К О В С К И Й have found out the basic reason of sodium silicate sand collapsibility difference through test, when he thinks the cast of molten metal high temperature, water-glass sand under the effect of heat-flash, Na wherein ₂O forms sintered body to the erosion and the sintering of quartz sand.The intensity of this sintered body has determined the height of water-glass sand retained strength at normal temperatures.So the formation amount of minimizing sintered body promptly reduces Na ₂O is the retained strength that reduces water-glass sand to the erosion and the sintering of quartz sand, improves the basic method of its collapsibility.Therefore, reduce Na in the sand significantly ₂The content of O, promptly the quantity of sodium ion is only the basic method that addresses this problem.But the long-term production practice shows that the adhesion strength of waterglass is low, if the intensity of wanting to improve the water glass type core sand correspondingly, also just must cause its collapsibility poor with regard to needing to strengthen the addition of waterglass.So the two gets both if think enough hardening strengths and superior collapsibility, just must on the basis of raising modulus of water glass, increase considerably the adhesion strength of itself.

Summary of the invention

To the deficiency of prior art, one of the object of the invention is to provide a kind of preparation method of casting water glass sand, with the intensity that improves water-glass sand and improve its collapsibility.

For realizing above-mentioned purpose, the technical scheme that the present invention adopts is:

A kind of preparation method of casting water glass sand, this method comprises the steps:

1) preparing modified waterglass; At room temperature, be 2.5-3.5 at modulus, density is 1.30-1.45g/cm ³Waterglass in add the composite modifier account for waterglass total amount 8-10%; Said composite modifier is made up of talcum powder, starch, POLYPROPYLENE GLYCOL, nano alumina powder; Be that the benchmark talcum powder accounts for 35-50% with the composite modifier total amount wherein, starch accounts for 6-12%, and POLYPROPYLENE GLYCOL accounts for 14-18%; Nano alumina powder accounts for 25-35%, processes modified water glass after stirring;

2) preparation molding sand: in casting with normal sand, add the modified water glass of the step 1) preparation that accounts for quartz sand 5-6.5%, stirring got final product after 40-80 minute in puddle mixer.

The invention has the beneficial effects as follows:

Through choose reasonable each component with the collocation composite modifier; Make and play synergy between each component, make the sand bond for preparing by the modified water glass that has added this composite modifier improve more than 40%, and improved the collapsibility of molding sand; Only need to get final product knockout through the dry method vibrations; Avoid the quick-fried or water-soluble sand removal of water, cost saving, protection environment.

Further specify advantage of the present invention below in conjunction with embodiment.

The specific embodiment

Embodiment one

A kind of preparation method of casting water glass sand, this method comprises the steps:

1) preparing modified waterglass; At room temperature, be 2.5-3.5 at modulus, density is 1.30-1.45g/cm ³Waterglass in add the composite modifier account for waterglass total amount 8%; Said composite modifier is made up of talcum powder, starch, POLYPROPYLENE GLYCOL, nano alumina powder; Be that the benchmark talcum powder accounts for 35% with the composite modifier total amount wherein, starch accounts for 12%, and POLYPROPYLENE GLYCOL accounts for 18%; Nano alumina powder accounts for 35%, processes modified water glass after stirring;

2) preparation molding sand: in casting with normal sand, add the modified water glass of the step 1) preparation that accounts for quartz sand 5%, stirring got final product after 40 minutes in puddle mixer.

Embodiment two

A kind of preparation method of casting water glass sand, this method comprises the steps:

1) preparing modified waterglass; At room temperature, be 2.5-3.5 at modulus, density is 1.30-1.45g/cm ³Waterglass in add the composite modifier account for waterglass total amount 9%; Said composite modifier is made up of talcum powder, starch, POLYPROPYLENE GLYCOL, nano alumina powder; Be that the benchmark talcum powder accounts for 45% with the composite modifier total amount wherein, starch accounts for 10%, and POLYPROPYLENE GLYCOL accounts for 15%; Nano alumina powder accounts for 30%, processes modified water glass after stirring;

2) preparation molding sand: in casting with normal sand, add the modified water glass of the step 1) preparation that accounts for quartz sand 5.8%, stirring got final product after 60 minutes in puddle mixer.

Embodiment three

A kind of preparation method of casting water glass sand, this method comprises the steps:

1) preparing modified waterglass; At room temperature, be 2.5-3.5 at modulus, density is 1.30-1.45g/cm ³Waterglass in add the composite modifier account for waterglass total amount 8-10%; Said composite modifier is made up of talcum powder, starch, POLYPROPYLENE GLYCOL, nano alumina powder; Be that the benchmark talcum powder accounts for 50% with the composite modifier total amount wherein, starch accounts for 8%, and POLYPROPYLENE GLYCOL accounts for 16%; Nano alumina powder accounts for 26%, processes modified water glass after stirring;

2) preparation molding sand: in casting with normal sand, add the modified water glass of the step 1) preparation that accounts for quartz sand 6%, stirring got final product after 80 minutes in puddle mixer.

Embodiment four

A kind of preparation method of casting water glass sand, this method comprises the steps:

1) preparing modified waterglass; At room temperature, be 2.5-3.5 at modulus, density is 1.30-1.45g/cm ³Waterglass in add the composite modifier account for waterglass total amount 8-10%; Said composite modifier is made up of talcum powder, starch, POLYPROPYLENE GLYCOL, nano alumina powder; Be that the benchmark talcum powder accounts for 45% with the composite modifier total amount wherein, starch accounts for 11%, and POLYPROPYLENE GLYCOL accounts for 17%; Nano alumina powder accounts for 27%, processes modified water glass after stirring;

2) preparation molding sand: in casting with normal sand, add the modified water glass of the step 1) preparation that accounts for quartz sand 6.5%, stirring got final product after 60 minutes in puddle mixer.

The key technical indexes of the molding sand of embodiment one to four

24 hours dry-pressing intensity >=3.6MPa

100 ℃ of retained strength≤0.15MPa

Table 1 is the performance comparison of the light water glass sand of embodiment one to four performance and prior art:

The performance comparison of the light water glass sand of table 1 embodiment one to four performance and prior art

	The present invention	Prior art
			Dry-pressing intensity (MPa)	≥3.2	≥2.3
Retained strength (MPa)	≤0.15	≤1.5
			Collapsibility	Good	Difference
Gas forming amount (ml/g)	≤8	≤16
			The sand removal mode	The dry method vibrations	Water is quick-fried or water-soluble
Casting quality	Flawless, gloss, pore is few	Crackle is arranged, and dark and gloomy, pore is many

Applicant's statement; The present invention explains detailed process equipment of the present invention and technological process through the foregoing description; But the present invention is not limited to above-mentioned detailed process equipment and technological process, does not mean that promptly the present invention must rely on above-mentioned detailed process equipment and technological process could be implemented.The person of ordinary skill in the field should understand, and to any improvement of the present invention, to the interpolation of the equivalence replacement of each raw material of product of the present invention and auxiliary element, the selection of concrete mode etc., all drops within protection scope of the present invention and the open scope.

Claims (1)

1. the preparation method of a casting water glass sand is characterized in that, this method comprises the steps:

1) preparing modified waterglass; At room temperature, be 2.5-3.5 at modulus, density is 1.30-1.45g/cm ³Waterglass in add the composite modifier account for waterglass total amount 8-10%; Said composite modifier is made up of talcum powder, starch, POLYPROPYLENE GLYCOL, nano alumina powder; Be that the benchmark talcum powder accounts for 35-50% with the composite modifier total amount wherein, starch accounts for 6-12%, and POLYPROPYLENE GLYCOL accounts for 14-18%; Nano alumina powder accounts for 25-35%, processes modified water glass after stirring;

2) preparation molding sand: in casting with normal sand, add the modified water glass of the step 1) preparation that accounts for quartz sand 5-6.5%, stirring got final product after 40-80 minute in puddle mixer.