CN108746475A - A kind of coated sand and preparation method thereof - Google Patents
A kind of coated sand and preparation method thereof Download PDFInfo
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- CN108746475A CN108746475A CN201810898021.8A CN201810898021A CN108746475A CN 108746475 A CN108746475 A CN 108746475A CN 201810898021 A CN201810898021 A CN 201810898021A CN 108746475 A CN108746475 A CN 108746475A
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22C—FOUNDRY MOULDING
- B22C1/00—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22C—FOUNDRY MOULDING
- B22C1/00—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds
- B22C1/02—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds characterised by additives for special purposes, e.g. indicators, breakdown additives
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Abstract
The present patent application belongs to casting and molding technical field, specifically disclose a kind of coated sand and preparation method thereof, precoated sand includes aggregate and thermoplastic resin, and the precoated sand includes aggregate and thermoplastic resin, and it is 35~100% that low-temperature phase β phases, which are 0~51%, high-temperature-phase α phases, in the aggregate；Amount ratio of the orthoclase in total crystal phase structure is no more than 16% in aggregate, and amount ratio of the plagioclase in total crystal phase structure is no more than 5%.This technology method provides a kind of forming a kind of tunable expansion behavior technique effect by adjusting the high-temperature-phase material component quantity relative ratio relationship of aggregate, to obtain the coated sand product for the suitable coefficient of thermal expansion that can be needed according to different cast applications, solves the technical barrier that the various casting caused by expansion behavior is not applicable expand class defect.
Description
Technical field
The invention belongs to casting and molding technical field, a kind of coated sand and preparation method thereof is specifically disclosed.
Background technology
Coated sand is the molding sand or core sand that sand grain surface is covered with one layer of hard resin film before moulding, it is a kind of
Casting and molding material, form are mostly the natural particle shape of dry state dispersion at room temperature.Coated sand is usually by as bone
The scouring sand of material, the thermoplastic resin used as bonding agent, as the methenamine of curing agent, and in order to improve a certain performance
And the materials composition such as other additives being added, by hot method overlay film, wet method overlay film and cold process overlay film etc. configure technique processing
At.Coated sand has the characteristics that heat cure intensity is high, gas forming amount is low, collapsibility is good with it, is widely used in surface quality
It is required that the production for the casting such as high, inner-cavity structure complexity and dimension control are stringent.
Coated sand becomes cast waste sand after completing moulding, cast, knockout, and cast waste sand can be become by regenerating means
For the repeatable reclaimed sand utilized, thermomechanometry develops relative maturity in present recycling cast waste sand means, and thermomechanometry refers to
It uses high temperature aerobic by using the thermal cracking characteristic of organic matter cast waste sand or oxygen-enriched air roasting removes membrane part, in conjunction with machinery
The regeneration method of the attachment of effect removal antiquated sand cast sintering.
Casting sand technology is that a kind of important material and application technology, casting sand have in machinery manufacturing technology field
High refractoriness and appropriateness high-temperature expansion be its application a kind of vital characteristic and thermal behavior feature, this characteristic
The quality and qualification rate of casting are determined with thermal behavior feature.For this purpose, casting engineering Shi Yizhi makes great efforts to develop different high temperature resistants
The coated sand product of low thermal expansion.Usually used technical solution is the refractory aggregate using higher refractoriness, selects tool
There are the aggregate and resinoid bond of low thermal expansion, or uses the additive and technique that can adjust precoated sand entire expanse rate
Deng.The artificial sand of the usual Ceramics quality of aggregate of high refractoriness, the quartz of emergy, magnesia, chromite sand, high silicon content
Sand etc., the phenolic resin etc. for the phenolic resin and low thermal expansion that resinoid bond usually selects remaining carbon high；Additive generally selects
With the inorganic material that improvement can be cooperateed with to thermally expand (contraction) characteristic or reduction resin film thermal cracking rate with phenolic resin, such as oxygen
Change the powder inorganic additive of aluminium, silica, iron oxide etc. and the various organic compounds that can play fire retardation so that overlay film
The resin film of sand is slowed down by high temperature pyrolysis rate and more resistant to high temperature.The above mode can realize prepared resin coating really
Film sand achievees the purpose that high temperature resistance low-expansion, but often these modes produce coated sand all with cost increase, technique
Complicated, properties of product fluctuate antiquated sand that is unstable, being formed after cast and regenerate difficult and regeneration cost since constituent content is complicated
The problems such as increasing.
Invention content
The purpose of the present invention is in a kind of coated sand of offer and preparation method thereof, with the high-temperature-phase material by adjusting aggregate
Material component quantity relative ratio relationship forms a kind of coordination expansion behavior technique effect, can be suitable using what is needed according to different cast to obtain
The coated sand product of suitable coefficient of thermal expansion solves the skill that the various casting caused by expansion behavior is not applicable expand class defect
Art problem.
In order to achieve the above object, base case of the invention is：A kind of coated sand, the precoated sand include aggregate
And thermoplastic resin, it is 35~100% that low-temperature phase β phases, which are 0~51%, high-temperature-phase α phases, in the aggregate；Orthoclase exists in aggregate
Amount ratio in total crystal phase structure is no more than 16%, and amount ratio of the plagioclase in total crystal phase structure is no more than 5%.
The method judgement that the qualitative determination of aggregate crystalline phase is combined using XRD with element chemical analysis method in this programme, this
Scheme andesine refers to orthoclase and plagioclase.
The advantageous effect of this base case is：In the aggregate low-temperature phase β phases be 0~51%, high-temperature-phase α phases be 35~
100%, orthoclase is less than 16%, plagioclase and is less than 5%, and the maximum of 1000 DEG C of the expansion characteristics satisfaction of obtained precoated sand swashs
Coefficient of thermal expansion is 0.45~1.2%；The expansion rate during 20~70 seconds under 1000 DEG C of sharp thermal environments meets linear regression side
The slope of journey is in 0.03~0.08 (%/second) so that precoated sand has under the conditions of high temperature (700~1650 DEG C) of cast application
Applicable expansion rate level and expansion behavior, and then the expansion class defect such as vein, fin, scab for realizing reduction casting occurs
Rate reduces casting cost, improves qualification rate.
Compared with prior art, the expansion characteristics of this coated sand are lower, and thermal behavior characteristic more can be from different casting
Pouring technology matching criteria and harmonious, compares after testing, and expansion rate is low using pure scouring sand horizontally relative to aggregate
30% or more, it is suitable with the expansion rate for the precoated sand for being added to nice foundry sand or emergy (but material cost declines 10~20%).
Further, the aggregate includes reclaimed sand, and clean sand, roasting sand, CJ4D sand, nice foundry sand, Saite ceramsite sand,
Natural or artificial refractory's aggregate is individually or the mixed sand that is mixed to form.The application of mixed sand, in existing thermal expansion character effect
On the basis of can further cooperate with increase other cast application effects, such as can further improve the high temperature resistant time of precoated sand, get angry
The performances such as characteristic, anti-burnon ability, thermal crack resistant.
Finished product after antiquated sand re-works after casting is referred to as reclaimed sand, the price of reclaimed sand well below roasting sand,
On the one hand the addition of reclaimed sand can substantially reduce the production cost of coated sand, be greatly reduced discharge, the processing of antiquated sand
Etc. expenses, reduce pollution of the antiquated sand uncontrollable discharge to environment；Simultaneously because of antiquated sand warp during the regeneration technology of thermomechanometry
A high temperature (400~800 DEG C) heat treatment process is gone through, antiquated sand aggregate is retained and undergoes micro- during this thermal history
Atomic rearrangement, adjustment crystal phase structure and conformation are seen, and fast cooling makes its crystal phase structure and conception freeze to become different crystalline phases
Structure creates the aggregate different from thermal behavior feature before regeneration, is selected when being produced precoated sand.The addition of artificial sand can increase
The hot properties such as anti-agglutinatting property of the prepared coated sand of adduction adjustment.The heating of other sand can be convenient for aggregate being adjusted to
Required state, to make prepared precoated sand various aspects of performance more preferably.
Further, it is 0~55% that sand is cleaned in the aggregate, and roasting sand is 0~80%, and reclaimed sand is 20~100%.It wipes
Washed-out sand low-temperature phase β phases in addition to feldspar are 100%, and reclaimed sand high-temperature-phase α phases in addition to feldspar are 100%, roast in sand and contain low temperature
Phase β phases and high-temperature-phase α phases；Using this few class sand, raw material is more easy to obtain, and configuration is more easy.
Further, the reclaimed sand includes following several：
A, it is passed through after being applied to the antiquated sand that non-ferrous metal, ferrous metal and cast steel casting are formed from sand in coating phenolic resin
Reclaimed sand prepared by thermomechanometry regeneration technology；
B, it is passed through thermomechanically after casting the antiquated sand to be formed applied to non-ferrous metal and ferrous metal from cold box resin sand
Reclaimed sand prepared by method regeneration technology；
C, it is applied to regenerate work through thermomechanometry after the antiquated sand that colored black metal casting is formed from furan resin-sand
Reclaimed sand prepared by skill；
D, it is cast after the antiquated sand to be formed through thermomechanometry regeneration technology system applied to ferrous metal from damp film green-sand
Standby reclaimed sand；
E, it is applied to regenerate through thermomechanometry after ferrous metal, the antiquated sand that cast steel casting is formed from alkali phenol resin sand
Reclaimed sand prepared by technique；
F, through thermomechanometry regeneration technology after the antiquated sand that the antiquated sand arbitrary proportion and described in A, B, C, D, E is mixed to form
The reclaimed sand of preparation.
Above-mentioned reclaimed sand enumerates most antiquated sand, is made full use of to most antiquated sands caused by casting,
Reduce the production cost of coated sand.
Further, the amount ratio of the addition of thermoplastic resin and the aggregate is 0.8~3.5%, the thermoplastic resin
Average degree of polymerization be 6~20, number average molecular weight distribution be 500~21000, weight average molecular weight is distributed as 600~25000,
The ratio of middle number-average molecular weight and weight average molecular weight is between 1~5.
Thermoplastic resin under the conditions of this is easier evenly and rapidly to be wrapped in the outside of aggregate during mulling, and makes
The various aspects of performance of coated sand is more preferably.
Further, the average degree of polymerization of the thermoplastic resin is 8~15, and number average molecular weight distribution is 800~16000,
Weight average molecular weight is distributed as 900~20000, and wherein the ratio of number-average molecular weight and weight average molecular weight is between 1.3~4.
Thermoplastic resin under the conditions of this is further easier evenly and rapidly to be wrapped in the outer of aggregate during mulling
Portion, and further make the various aspects of performance of coated sand more preferably.
The present invention also provides a kind of preparation methods of coated sand, include the following steps：
(1) aggregate：Select the phases of β containing low-temperature phase 0~51%, the phases of α containing high-temperature-phase 35~100%, 16% is less than containing orthoclase,
It is less than 5% aggregate containing plagioclase；Aggregate includes reclaimed sand and cleans sand, and roasting sand, CJ4D sand, nice foundry sand, Saite are made pottery
Granule, natural or artificial refractory's aggregate are individually or the mixed sand that is mixed to form；
(2) thermoplastic resin：The amount ratio of the addition of thermoplastic resin and the aggregate is 0.8~3.5%, thermoplastic resin
The average degree of polymerization of fat is 6~20, and number average molecular weight distribution is 500~21000, and weight average molecular weight is distributed as 600~25000,
Wherein the ratio of number-average molecular weight and weight average molecular weight is between 1~5；
(3) mulling：Aggregate is heated to 132~140 DEG C, viscosity of the thermoplastic resin at 128~132 DEG C 400~
It is added in aggregate when 600cp and carries out mulling, the rotating speed of mulling is 50~80r/min, after mixing, through broken, screening and cold
But coated sand is obtained.
Preparation method using the present invention has the following advantages that：Thermoplastic resin is used when being contacted with particles of aggregates
These dihedral coefficients with high-temperature-phase aggregate it is relatively low, enable thermoplastic resin more it is uniform it is quick package and
It is covered in the outside of aggregate, keeps made coated sand overlay film effect preferable, and therefore sphericity also increases, room temperature mobility
It increased compared to common precoated sand with temperature flowing.Meanwhile the maximum of 1000 DEG C of obtained coated sand swashs
Expansion rate during coefficient of thermal expansion is 20~70 seconds under 0.45~1.2%, 1000 DEG C of sharp thermal environments meets linear regression side
The slope of journey is in 0.03~0.08 (%/second)；So that precoated sand has under the conditions of high temperature (700~1650 DEG C) of cast application
Applicable expansion rate level and expansion behavior, so that precoated sand has preferable high refractoriness and high-temperature expansion.
Further, phenolic acid resin is modified using modifying agent in step (2) and thermoplastic resin is prepared, it is described to change
Property agent includes organic esters, organosilicon, organic long-chain alkyl acids, organic long-chain induced by alkyl hydroxybenzene, higher alcohols, advanced
Alkanes, cycloalkane heteropllyacids, naphthenic base amine, alkylbenzene amine, oxazine class, imidazoles, senior alkyl acid calcium salt class, nothing
Machine oxide or mineral powder.
The above modifying agent can further improve the overlay film effect of precoated sand, make the precoated sand various aspects of performance of preparation more preferably.
Further, the aggregate in step (3) is heated to 132~138 DEG C, and the rotating speed of mulling is 60~70r/min.
Precoated sand is prepared under these conditions, can further make the overlay film of precoated sand better.
Specific implementation mode
Below by specific implementation mode, the present invention is described in further detail：
The chemical composition discovery cleaned sand by research, roast sand, the crystal phase structure of reclaimed sand and composition crystal phase structure, three
The thermal expansion behavior of person has apparent difference, and especially sharp thermal expansion rates are significantly different, and this thermal behavior is characterized as us
Develop it is a kind of it is anti-casting expansion class defect occur coated sand solid technical foundation and principle are provided.Pass through XRD analysis
Clean the type acquisition result as shown in Table 1 and Table 2 of sand, roasting sand, reclaimed sand.
Table 1
Table 2
According to the data of Tables 1 and 2, the crystal form and crystalline phase that discovery reclaimed sand has are bright at shown physical property is grouped as
It is aobvious to be different from cleaning sand and roasting sand.It is hexagonal phase system to clean crystalline phase possessed by sand and roasting sand, but roasts sand and had
Some crystalline phases are obviously lower than the feldspar amount of dry sand at the low melting point feldspar amount contained in being grouped as, and more one kind in ingredient
Plagioclase；Secondly crystalline phase system possessed by roasting sand has roasted three main peak crystalline phase types of sand although same with scouring sand facies
Corresponding change has occurred, the XRD spectra classification number is caused to have changed, the being checked crystalline phase parameter hair cleaned sand and roast sand
There are three classes to change in existing five class crystalline phase parameters and different, determines that the analysis of different crystal forms amount accounting is tied by the total amount of peak value
Fruit finds that the low quartz accounting in roasting sand only has 70% or so, therefore the crystalline phase for roasting sand is sorted out from the pure of scouring sand
Low-temperature phase crystal form is partially converted into the high/low temperature mixing crystalline structure that high-temperature-phase crystalline structure accounts for 30% or so.Sand is cleaned in comparison
It is completely different with sand is cleaned from the crystalline phase parameter of the reclaimed sand crystalline phase parameter for finding reclaimed sand, have four in five kinds of crystalline phase parameters
Kind is different, illustrates that the high-temperature phase-transitional of reclaimed sand than roasting sand higher, belongs to 100% high quartz phase crystalline structure, and its
The accounting of orthoclase also wants low relative to roasting sand with the ratio for cleaning orthoclase in sand.
Materialization related data is inquired it is found that feldspar substance is divided into two major classes, one kind is that potassium feldspar is also referred to as orthoclase, separately
One kind is that albite (including oligoclase, andesine, bytownite, anorthite etc.) is also referred to as plagioclase.The fusing point 1290 of potassium feldspar
DEG C, high-temperature fusion interval is wider；1215 DEG C of albite fusing point, high-temperature fusion interval is small, and melt viscosity is low, at identical temperature
The fluxing action of albite is more than potassium feldspar.
Embodiment 1
A kind of preparation method of coated sand, includes the following steps：
(1) aggregate：Roasting sand 78.5% is selected, reclaimed sand 21.5% is configured to overlay film aggregate, wherein β containing low-temperature phase
Phase 49.4%, the phases of α containing high-temperature-phase 40.4% contain orthoclase 5.7%, contain plagioclase 4.5%.
The reclaimed sand includes following several：
A, it is passed through after being applied to the antiquated sand that non-ferrous metal, ferrous metal and cast steel casting are formed from sand in coating phenolic resin
Reclaimed sand prepared by thermomechanometry regeneration technology；
B, it is passed through thermomechanically after casting the antiquated sand to be formed applied to non-ferrous metal and ferrous metal from cold box resin sand
Reclaimed sand prepared by method regeneration technology；
C, it is applied to regenerate work through thermomechanometry after the antiquated sand that colored black metal casting is formed from furan resin-sand
Reclaimed sand prepared by skill；
D, it is cast after the antiquated sand to be formed through thermomechanometry regeneration technology system applied to ferrous metal from damp film green-sand
Standby reclaimed sand；
E, it is applied to regenerate through thermomechanometry after ferrous metal, the antiquated sand that cast steel casting is formed from alkali phenol resin sand
Reclaimed sand prepared by technique；
F, through thermomechanometry regeneration technology after the antiquated sand that the antiquated sand arbitrary proportion and described in A, B, C, D, E is mixed to form
The reclaimed sand of preparation.
(2) thermoplastic resin：The modified thermoplastic resin prepared, utilizes modifying agent pair based on casting phenolic resin
Phenolic acid resin, which is modified, is prepared thermoplastic resin, and the modifying agent includes organic esters, organosilicon, has captain
Alkyl group acids, organic long-chain induced by alkyl hydroxybenzene, higher alcohols, higher alkane class, cycloalkane heteropllyacids, naphthenic base amine, alkane
Base phenyl amines, oxazines class, imidazoles, senior alkyl acid calcium salt class, inorganic oxide or mineral powder etc..
The average degree of polymerization of thermoplastic resin is 6~20, and number average molecular weight distribution is 500~21000, weight average molecular weight point
Cloth is 600~25000, and wherein the ratio of number-average molecular weight and weight average molecular weight is between 1~5；The total bone of thermoplastic resin amount's accounting
The 2.5% of doses；
(3) mulling：Aggregate is heated to 132 DEG C, aggregate is added in 600cp in viscosity of the thermoplastic resin at 128 DEG C
In, and the curing agent methenamine for accounting for amount of resin 14% is added, the interleaving agent calcium stearate of aggregate amount 0.1% is accounted for, mulling is carried out,
The rotating speed of mulling is 65r/min, after mixing, obtains coated sand through broken, screening and cooling, and covered made of control
The total burning decrement of film sand is 3.1%.
Embodiment 2
Difference from example 1 is that in step (1), reclaimed sand 100% is selected to be used as overlay film aggregate, wherein
The phases of β containing low-temperature phase 0%, the phases of α containing high-temperature-phase 95.7% contain orthoclase 4.3%, contain plagioclase 0%；In step (2), thermoplastic resin
The 3.5% of the total aggregate amount of fat amount accounting；In step (3), aggregate is heated to 140 DEG C, viscosity of the thermoplastic resin at 132 DEG C
It is added in aggregate in 400cp, and the curing agent methenamine for accounting for amount of resin 20% is added, account for the interleaving agent of aggregate amount 0.2%
Calcium stearate carries out mulling, and the rotating speed of mulling is 80r/min, after mixing, resin coating is obtained through broken, screening and cooling
Film sand, and it is 4.5% to control the total burning decrement of manufactured precoated sand.Embodiment 3
Difference from example 1 is that in step (1), select and clean sand 10%, roasts sand 25%, reclaimed sand
65% be used as overlay film aggregate, wherein the phases of β containing low-temperature phase 25.1%, the phases of α containing high-temperature-phase 66.3%, containing orthoclase 7.2%, contain tiltedly
Feldspar 1.4%；In step (2), the average degree of polymerization of thermoplastic resin is 8~15, and number average molecular weight distribution is 800~16000,
Weight average molecular weight is distributed as 900~20000, and the wherein ratio of number-average molecular weight and weight average molecular weight is between 1.3~4, thermoplasticity
The 1% of the total aggregate amount of amount of resin accounting；In step (3), aggregate is heated to 140 DEG C, viscosity of the thermoplastic resin at 130 DEG C
It is added in aggregate in 450cp, and the curing agent methenamine for accounting for amount of resin 18% is added, account for the interleaving agent of aggregate amount 0.2%
Calcium stearate carries out mulling, and the rotating speed of mulling is 80r/min, after mixing, resin coating is obtained through broken, screening and cooling
Film sand, and it is 1.6% to control the total burning decrement of manufactured precoated sand.
Embodiment 4
Difference from example 1 is that the aggregate in step (3) is heated to 135 DEG C, thermoplastic resin is at 129 DEG C
Under viscosity be added in aggregate in 500cp and carry out mulling, the rotating speed of mulling is 70r/min, and mulling to thermoplastic resin is wrapped in
It on aggregate and solidifies, forms coated sand.
Comparative example 1
Difference from example 1 is that in step (1), roasting sand 78.5%, nice foundry sand 21.5% is selected to prepare
At overlay film aggregate, wherein the phases of β containing low-temperature phase 48.7%, the phases of α containing high-temperature-phase 20.9%, containing orthoclase 4.7%, contain plagioclase
4.2%, mullite phase 21.5%.
Comparative example 2
Difference from example 1 is that in step (1), select and clean sand 85%, reclaimed sand 15% is used as overlay film
Aggregate.
Comparative example 3
Difference from example 1 is that the aggregate is only with scouring sand.
Comparative example 4
Difference from example 1 is that the thermoplastic resin is using the thermoplasticity obtained by non-modified processing
Resin.
According to the preparation method for implementing 1- embodiments 4 and comparative example 1- comparative examples 4, resinousness precoated sand is prepared respectively.
Coefficient of thermal expansion is swashed to 1000 DEG C of maximums of coated sand after preparation, 1000 DEG C of sharp thermal expansion rates regression curve slopes carry out
Detection, and calculate production cost, the results are shown in table below.
Compare conclusion：
1, low-temperature phase β phases, high-temperature-phase α phases in aggregate can be seen that by the comparison of embodiment 1, embodiment 2 and comparative example 1,
Be maintained within the scope of this, obtained coated sand, it is suitable that 1000 DEG C of maximums swash coefficient of thermal expansion, and expansion rate relative to
Comparative example 1 is very fast, illustrates that the time for obtaining maximum swelling rate is shorter, it is very fast that prepared precoated sand is suitable for casting condensing rate
In the environment of apply, can be obtained in such a case than 1 better application effect of comparative example, while producing in this case
Cost substantially reduces.
2, the sharp coefficient of thermal expansion of 1000 DEG C of maximums can be seen that with the comparison of comparative example 2 by embodiment 1 and expansion rate is opposite
All reduce in comparative example 2, illustrates that embodiment 1 has obviously technical advantage when solving casting expansion bug.For casting
Part condensing rate is very fast and slower to be applicable in, and can be obtained than 2 better application effect of comparative example.
3, after by embodiment 1 and the comparison of comparative example 3 as can be seen that being mixed into reclaimed sand in aggregate, 1000 DEG C of maximums swash
Coefficient of thermal expansion and expansion rate reduce, and it is notable to illustrate that reclaimed sand acts in terms of reducing expansion rate and improving expansion behavior, together
When reclaimed sand have the characteristics that economy, the cost pressure of Foundry Works can be mitigated.
4, it is compared by embodiment 1, embodiment 3 and comparative example 4 as can be seen that using modified thermoplastic resin production
Coated sand, the sharp coefficient of thermal expansion of 1000 DEG C of maximums is suitable with comparative example, but expansion rate has detailed reduction, illustrates to obtain maximum
The time of expansion rate is longer, and prepared precoated sand is suitable for applying under the slower environment of casting condensing rate, in this environment
Under can obtain than 4 better application effect of comparative example.
Claims (9)
1. a kind of coated sand, which is characterized in that the precoated sand includes aggregate and thermoplastic resin, low temperature in the aggregate
Phase β phases are that 0~51%, high-temperature-phase α phases are 35~100%；Amount ratio of the orthoclase in total crystal phase structure is no more than in aggregate
16%, amount ratio of the plagioclase in total crystal phase structure is no more than 5%.
2. a kind of coated sand as described in claim 1, which is characterized in that the aggregate includes reclaimed sand, and is cleaned
Sand roasts the mixed sand that sand, CJ4D sand, nice foundry sand, Saite ceramsite sand, natural or artificial refractory's aggregate are independent or are mixed to form.
3. a kind of coated sand as claimed in claim 2, which is characterized in that it is 0~55% to clean sand in the aggregate, roasting
It is 0~80% to burn sand, and reclaimed sand is 20~100%.
4. a kind of coated sand as claimed in claim 2, which is characterized in that the reclaimed sand includes following several：
A, it is applied to after the antiquated sand that non-ferrous metal, ferrous metal and cast steel casting are formed through heat engine from sand in coating phenolic resin
Reclaimed sand prepared by tool method regeneration technology；
B, it is applied to non-ferrous metal and ferrous metal from cold box resin sand to cast after the antiquated sand to be formed through thermomechanometry again
Reclaimed sand prepared by raw technique；
C, it is applied to after the antiquated sand that colored black metal casting is formed through thermomechanometry regeneration technology system from furan resin-sand
Standby reclaimed sand；
D, it is applied to ferrous metal from damp film green-sand and casts prepare through thermomechanometry regeneration technology after the antiquated sand to be formed
Reclaimed sand；
E, it is applied to after ferrous metal, the antiquated sand that cast steel casting is formed through thermomechanometry regeneration technology from alkali phenol resin sand
The reclaimed sand of preparation；
F, it is prepared through thermomechanometry regeneration technology after the antiquated sand that the antiquated sand arbitrary proportion and described in A, B, C, D, E is mixed to form
Reclaimed sand.
5. a kind of coated sand as described in claim 1, which is characterized in that the addition of thermoplastic resin and the aggregate
Amount ratio be 0.8~3.5%, the average degree of polymerization of the thermoplastic resin is 6~20, number average molecular weight distribution is 500~
21000, weight average molecular weight is distributed as 600~25000, and wherein the ratio of number-average molecular weight and weight average molecular weight is between 1~5.
6. a kind of coated sand as claimed in claim 5, which is characterized in that the average degree of polymerization of the thermoplastic resin is
8~15, number average molecular weight distribution is 800~16000, and weight average molecular weight is distributed as 900~20000, wherein number-average molecular weight with
The ratio of weight average molecular weight is between 1.3~4.
7. a kind of preparation method of coated sand as described in any one of claim 1~6, which is characterized in that including following step
Suddenly：
(1) aggregate：It selects the phases of β containing low-temperature phase 0~51%, the phases of α containing high-temperature-phase 35~100%, be less than 16% containing orthoclase, containing oblique
Feldspar is less than 5% aggregate；Aggregate include reclaimed sand and clean sand, and roasting sand, CJ4D sand, nice foundry sand, Saite ceramsite sand,
Natural or artificial refractory's aggregate is individually or the mixed sand that is mixed to form；
(2) thermoplastic resin：The amount ratio of the addition of thermoplastic resin and the aggregate is 0.8~3.5%, thermoplastic resin
Average degree of polymerization is 6~20, and number average molecular weight distribution is 500~21000, and weight average molecular weight is distributed as 600~25000, wherein
The ratio of number-average molecular weight and weight average molecular weight is between 1~5；
(3) mulling：Aggregate is heated to 132~140 DEG C, viscosity of the thermoplastic resin at 128~132 DEG C is in 400~600cp
When be added in aggregate and carry out mulling, the rotating speed of mulling is 50~80r/min, after mixing, is obtained through broken, screening and cooling
Coated sand.
8. a kind of preparation method of coated sand as claimed in claim 7, which is characterized in that utilize modification in step (2)
Agent is modified phenolic acid resin and thermoplastic resin is prepared, and the modifying agent includes organic esters, organosilicon, has
Captain's alkyl group acids, organic long-chain induced by alkyl hydroxybenzene, higher alcohols, higher alkane class, cycloalkane heteropllyacids, Cycloalkyl amine
Class, alkylbenzene amine, oxazine class, imidazoles, senior alkyl acid calcium salt class, inorganic oxide or mineral powder.
9. such as a kind of preparation method of coated sand of claim 7-8 any one of them, which is characterized in that in step (3)
Aggregate be heated to 132~138 DEG C, the rotating speed of mulling is 60~70r/min.
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| CN201810898021.8A Pending CN108746475A (en) | 2018-08-08 | 2018-08-08 | A kind of coated sand and preparation method thereof |
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| CN (1) | CN108746475A (en) |
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| CN110560641A (en) * | 2019-09-20 | 2019-12-13 | 中国重汽集团济南动力有限公司 | Water jacket sand core of integral cylinder cover of engine and preparation process |
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| CN114367628B (en) * | 2021-12-29 | 2023-08-29 | 天阳新材料科技有限公司 | Vein-resistant precoated sand for turbine shell and preparation method thereof |
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Application publication date: 20181106 |