CN101700676A - Method for controlling deformation of ceramic blank in gel casting process - Google Patents
Method for controlling deformation of ceramic blank in gel casting process Download PDFInfo
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- CN101700676A CN101700676A CN 200910218750 CN200910218750A CN101700676A CN 101700676 A CN101700676 A CN 101700676A CN 200910218750 CN200910218750 CN 200910218750 CN 200910218750 A CN200910218750 A CN 200910218750A CN 101700676 A CN101700676 A CN 101700676A
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Abstract
The present invention discloses a method for controlling the deformation of ceramic blank in the gel casting process which has the key point that in the gel casting process, the deformation of the ceramic blank is controlled in the drying process of the ceramic blank by controlling the content of monomer used for the gelling reaction and the proportion of the monomer to crosslinker in the slurry. The method is characterized in that acrylamide (AM) is used as the monomer and N, N'-methylene bisacrylamide (MBAM) is used as the crosslinker to prepare the slurry, the distribution of the gel network in the ceramic blank and the strength of the ceramic blank are controlled by controlling the content of the monomer used for the gelling reaction and the proportion of the monomer to crosslinker in the slurry, and the problem of controlling the deformation of the ceramic blank in the drying process of the ceramic blank is solved.
Description
Technical field:
The invention belongs to the porous ceramics preparation field, relate to the method for deformation of ceramic blank control in a kind of gel casting process.
Background technology:
Along with the continuous practicability of the advanced ceramics with excellent specific property, the demand of making the complicated shape ceramic member is strong day by day.Forming technique is the prerequisite of preparation ceramic component, yet manufacturing process such as traditional technology such as dry-pressing, mold pressing, slip casting, injection more and more do not satisfy forming requirements, and this makes forming technique become the key of preparation complicated shape ceramic component.Therefore, for obtaining to have the advanced ceramics goods of expectation function, the forming technology of powder is particularly important in the whole process that pottery is made, the formed body that density is even, shape and size precision is high that must be shaped, and require forming technology simple, with low cost.Gel casting technology can effectively be controlled the reunion of powder granule as a kind of colloidal formation technology, is easy to large-scale production and satisfies above specification requirement.
Gel casting (Gel-casting) is a kind of method of new colloidal formation ceramic component, it is a kind of new ceramics forming technology that early 1990s waits invention by professor O.O.Omatete of U.S. Oak Ridge National Key Laboratory (ORNL), this new forming technique adopts no punch die, utilize the chemical reaction effect of slurry inside to make the organic monomer polymerization crosslinking in the suspended substance form the three-dimensional network skeleton, make ceramic particle fixing wherein, liquid slurry is changed into have certain intensity and flexible base substrate, acquisition has the biscuit of good microscopic uniformity and higher density, thereby the reliability of material of significantly improving, be the dead size moulding, produce complicated shape and high-quality goods, found a low-cost method for preparing the high-performance base substrate.At present, along with the updating and becoming better and approaching perfection day by day of gel casting technology, it has become an important manufacturing process of advanced ceramics.
In using about gel casting process in front, research about deformation of ceramic blank control, mainly concentrate on the drying control conceptual phase of base substrate, S.Ghosal etc. have studied the wet dry run of control of gel casting forming base substrate in great detail, and have set up corresponding dry physical model.Utilize this model, the humidity of given drier, temperature and wet base thickness just can be predicted the green compact water content exactly, accurately control the drying of gel casting forming base substrate.Prabakaran.K etc. are at room temperature with after the base substrate demoulding, under being 90%, 80% and 65% room temperature condition, relative humidity carries out drying successively, the baking oven of putting into 80 ℃ after base substrate humidity minimizing 30% again is dry, and this method has not only improved rate of drying but also distortion and crackle can not appear in base substrate.The research of Zhang Liming thinks that the main cause of season cracking is that low excessively the causing of solid volume fraction inorganicly in the base substrate shrinks excessively mutually, and the inorganic corresponding compression that is subjected to changes into that tension causes.
In the base substrate intensity of the distribution of gel network and base substrate to drying after the performance of gained base substrate very big influence is arranged, yet, at present in the gel casting process application facet, about the content of the monomer that is used for gelling reaction by control in the slurry and the ratio of monomer and crosslinking agent, reaching the research of controlling the morphotropism problem in the dry run does not almost have.Therefore, originally be operated in the gel injection-moulding process, by being used for the ratio of content of monomer and the monomer and the crosslinking agent of gelling reaction in the control slurry, reach the distribution of gel network in the control base substrate and the intensity of base substrate, solve distortion, contraction problem in the dry run.
Summary of the invention:
The objective of the invention is to reach the distribution of gel network in the control base substrate and the intensity of base substrate, solve the morphotropism problem in the dry run by being used for the ratio of content of monomer and the monomer and the crosslinking agent of gelling reaction in the control gel injection-moulding.Can realize that near net-shape prepares large scale, complicated shape ceramic body.
The method of control blank deformation in a kind of gel casting process, this method comprises: preparation slurry, curing molding and body drying:
(1) preparation slurry: at first, monomer and crosslinking agent are mixed into mixture, the mass ratio of monomer and crosslinking agent was less than 10: 1 in the mixture; Again mixture, dispersant and distilled water are mixed with into premixed liquid, the mass percent of mixture is 10～55% in the described premixed liquid, the mass percent of dispersant is 2%, surplus is a distilled water;
Secondly, add beta-silicon nitride powder and sintering aid is prepared into compound in described premixed liquid, the mass percent of beta-silicon nitride powder is 30～60% in the described compound, the mass percent of sintering aid is 3～10%;
At last, described compound pH value is adjusted to 9～11, and will makes slurry behind the compound ball milling 12h;
(2) forming and hardening: described slurry is through after the vacuum degassing, adds that to account for monomer mass percentage be 1～20% initator, and injection molding after the vacuum degassing once more reacts under 40～65 ℃ of conditions and made slurry gelling curing, the demoulding in 30～60 minutes, obtains wet base substrate;
(3) body drying: will wet base substrate in Constant Temperature and Humidity Chambers after dry 4 days, and dryly in 100 ℃ drying box again obtain dry ceramic body.
Described monomer is that acrylamide, crosslinking agent are N, and N '-methylene-bisacrylamide, initator are ammonium persulfate.
The ratio of described monomer and crosslinking agent is 5: 1,7: 1 or 9: 1.
The strength range of ceramic body is between 50～90MPa in the step (3), deformation rate less than 10%, shrinkage factor is less than 10%.
Technical process of the present invention is as follows:
(1) experiment is adopted silicon nitride powder (average grain diameter is about 0.37 μ m, α phase＞94wt.%), Al
2O
3(average grain diameter is about 1.07 μ m, purity＞99%) and Y
2O
3(average grain diameter is about 4.74 μ m, purity＞99%) is sintering aid, and monomer is acrylamide (AM), and crosslinking agent is N, and N '-methylene-bisacrylamide (MBAM), dispersant are ammonium polyacrylate (PAA-NH
4), initator is ammonium persulfate (APS), regulates the pH value with concentrated ammonia liquor.Billet surface produces the peeling peeling phenomenon in the gel injection-moulding process to overcome to add a small amount of polyacrylamide (PAM).
(2) specific embodiment: with a certain amount of monomer and crosslinking agent (content of monomer (MC) is 10～55%, the ratio (RM) of monomer and crosslinking agent less than 10), with 2% dispersant, the preparation premixed liquid adds 30～60% beta-silicon nitride powders and 3～10% sintering aid (Al in premixed liquid
2O
3And Y
2O
3), regulating the pH value is 9～11, makes slurry behind the ball milling 12h.Slurry is through after the vacuum degassing, adds initator, injection molding after the degasification once more, under 40～65 ℃ of conditions, reacts and makes slurry gelling curing, the demoulding in 30～60 minutes.After (25 ℃ and 90% above humidity) dry 4 days, dry in 100 ℃ drying box again in Constant Temperature and Humidity Chambers, finally obtain the ceramic body of doing.
Described monomer is acrylamide (AM), and crosslinking agent is N, N '-methylene-bisacrylamide (MBAM).
Content of monomer is 10%～55%, monomer and crosslinking agent ratio be less than 10.
Drying condition is: dry in 25 ℃, the Constant Temperature and Humidity Chambers of damp condition more than 90%.
(3) in the base substrate intensity of the distribution of gel network and base substrate to drying after the performance of gained base substrate very big influence is all arranged, by being used for the ratio of content of monomer and the monomer and the crosslinking agent of gelling reaction in the control slurry, reach the morphotropism problem in the control dry run.
(4) characteristics of this technology be the strength range of prepared dry base substrate between 50～90MPa, the contraction of base substrate and morphotropism have obtained fine control, can realize that near net-shape prepares large scale, complicated shape ceramic body.
The invention has the advantages that:
(1) in the gel injection-moulding process, be used for the content of monomer of gelling reaction and the ratio of monomer and crosslinking agent in the slurry by control, reach the distribution of controlling gel network in the base substrate and the intensity of base substrate, solved the morphotropism problem in the dry run;
(2) base substrate of this method preparation has high stability and high intensity, Si
3N
4Particle being evenly distributed in base substrate, deformation of ceramic blank is less in the dry run;
(3) adopt the strength range of silicon nitride ceramics dry base substrate of this method preparation between 50～90MPa; The deformation rate of base substrate and shrinkage factor are all less than 10% after dry.
(4) utilize the method can realize that near net-shape prepares the big-size complicated shape porous ceramic articles.
Description of drawings:
Fig. 1 content of monomer and monomer and crosslinking agent ratio are to the influence of deformation of ceramic blank; A figure is MC=20wt.%; B figure is MC=55wt.%.
Fig. 2 content of monomer and monomer and crosslinking agent ratio are to the influence of blank deformation rate.
Fig. 3 content of monomer and monomer and crosslinking agent ratio are to the influence of base substrate shrinkage factor.
The specific embodiment:
Further specify outstanding feature of the present invention and obvious improvement below by four specific embodiments, but the present invention is not limited to embodiment.
Embodiment 1
With 20% mixture (acrylamide and N, N '-methylene-bisacrylamide), wherein monomer is that 5,2% dispersant and water mix with the crosslinking agent ratio, the preparation premixed liquid adds 40% beta-silicon nitride powder and 3% sintering aid (Al in premixed liquid
2O
3Y
2O
3), regulating the pH value is 9～11, makes slurry behind the ball milling 12h; Slurry is through after the vacuum degassing, adds initator, injection molding after the degasification once more, under 40～65 ℃ of conditions, react and makes slurry gelling curing, the demoulding in 30～60 minutes, and drying under 25 ℃ and 98% damp condition obtains base substrate.The deformation rate of prepared silicon nitride ceramics base substrate, shrinkage factor, bending strength are respectively 3.5%, 2.9%, 27.9MPa.
Embodiment 2
With 55% mixture (acrylamide and N, N '-methylene-bisacrylamide), wherein monomer is that 5,2% dispersant and water mix with the crosslinking agent ratio, the preparation premixed liquid adds 40% beta-silicon nitride powder and 3% sintering aid (Al in premixed liquid
2O
3Y
2O
3), regulating the pH value is 9～11, makes slurry behind the ball milling 12h; Slurry is through after the vacuum degassing, adds initator, injection molding after the degasification once more, under 40～65 ℃ of conditions, react and makes slurry gelling curing, the demoulding in 30～60 minutes, and drying under 25 ℃ and 98% damp condition obtains base substrate.O.6% the deformation rate of prepared silicon nitride ceramics base substrate, shrinkage factor, bending strength are respectively, 1.95%, 60.2MPa.
Embodiment 3
With 20% mixture (acrylamide and N, N '-methylene-bisacrylamide), wherein monomer is that 7,2% dispersant and water mix with the crosslinking agent ratio, the preparation premixed liquid adds 40% beta-silicon nitride powder and 3% sintering aid (Al in premixed liquid
2O
3Y
2O
3), regulating the pH value is 9～11, makes slurry behind the ball milling 12h; Slurry is through after the vacuum degassing, adds initator, injection molding after the degasification once more, under 40～65 ℃ of conditions, react and makes slurry gelling curing, the demoulding in 30～60 minutes, and drying under 25 ℃ and 98% damp condition obtains base substrate.The deformation rate of prepared silicon nitride ceramics base substrate, shrinkage factor, bending strength are respectively 6.2%, 3.25%, 28.9MPa.
With 55% mixture (acrylamide and N, N '-methylene-bisacrylamide), wherein monomer is that 9,2% dispersant and water mix with the crosslinking agent ratio, the preparation premixed liquid adds 40% beta-silicon nitride powder and 3% sintering aid (Al in premixed liquid
2O
3Y
2O
3), regulating the pH value is 9～11, makes slurry behind the ball milling 12h; Slurry is through after the vacuum degassing, adds initator, injection molding after the degasification once more, under 40～65 ℃ of conditions, react and makes slurry gelling curing, the demoulding in 30～60 minutes, and drying under 25 ℃ and 98% damp condition obtains base substrate.The deformation rate of prepared silicon nitride ceramics base substrate, shrinkage factor, bending strength are respectively 1.0%, 2.2%, 87.6MPa.
Shown in top embodiment, content of monomer and monomer and crosslinking agent ratio factor are equipped with the influence of silicon nitride base substrate performance (deformation rate, shrinkage factor, bending strength) to the gel injection-moulding legal system in the gel injection-moulding method of having utilized designed experimental study, and result of the test shows along with increasing content of monomer makes Si
3N
4The deformation rate and the shrinkage factor of base substrate reduce; Increase the deformation rate and the dull increase of shrinkage factor of base substrate with monomer and crosslinked ratio.Deformation rate is very significant with the variation of monomer and crosslinked ratio when content of monomer is 20%, and when content of monomer deformation rate greater than 20% time be unconspicuous with the variation of monomer and crosslinked ratio.As seen by being used for content of monomer and the monomer and the crosslinking agent ratio of gelling reaction in the control slurry, can reach the morphotropism problem in the control dry run by top result of the test.
Above content is to further describing that the present invention did in conjunction with concrete preferred implementation; can not assert that the specific embodiment of the present invention only limits to this; for the general technical staff of the technical field of the invention; without departing from the inventive concept of the premise; can also make some simple deduction or replace, all should be considered as belonging to claims that the present invention submits to and determine scope of patent protection.
Claims (4)
1. the method for control blank deformation in the gel casting process,
This method comprises: preparation slurry, curing molding and body drying is characterized in that:
(1) preparation slurry: at first, monomer and crosslinking agent are mixed into mixture, the mass ratio of monomer and crosslinking agent was less than 10: 1 in the mixture; Again mixture, dispersant and distilled water are mixed with into premixed liquid, the mass percent of mixture is 10～55% in the described premixed liquid, the mass percent of dispersant is 2%, surplus is a distilled water;
Secondly, add beta-silicon nitride powder and sintering aid is prepared into compound in described premixed liquid, the mass percent of beta-silicon nitride powder is 30～60% in the described compound, the mass percent of sintering aid is 3～10%;
At last, described compound pH value is adjusted to 9～11, and will makes slurry behind the compound ball milling 12h;
(2) forming and hardening: described slurry is through after the vacuum degassing, adds that to account for monomer mass percentage be 1～20% initator, and injection molding after the vacuum degassing once more reacts under 40～65 ℃ of conditions and made slurry gelling curing, the demoulding in 30～60 minutes, obtains wet base substrate;
(3) body drying: will wet base substrate in Constant Temperature and Humidity Chambers after dry 4 days, and dryly in 100 ℃ drying box again obtain dry ceramic body.
2. by the method for deformation of ceramic blank control in the described gel casting process of claim 1, it is characterized in that: described monomer is that acrylamide, crosslinking agent are N, and N '-methylene-bisacrylamide, initator are ammonium persulfate.
3. by the method for deformation of ceramic blank control in the described a kind of gel casting process of claim 1, it is characterized in that: the ratio of described monomer and crosslinking agent is 5: 1,7: 1 or 9: 1.
4. by the method for deformation of ceramic blank control in the claim 1,2 and 3 described a kind of gel casting process, it is characterized in that: in the step (3) strength range of ceramic body between 50～90MPa, deformation rate less than 10%, shrinkage factor is less than 10%.
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107283610A (en) * | 2017-07-10 | 2017-10-24 | 河北盛平电子科技有限公司 | A kind of drying means of ceramic body, preparation method and ceramic body |
| CN108358644A (en) * | 2018-03-06 | 2018-08-03 | 济南大学 | Based on xanthans gel casting forming TiB2The preparation method of composite ceramics biscuit |
| CN109176828A (en) * | 2018-08-16 | 2019-01-11 | 中国船舶重工集团公司第七二五研究所 | Prevent the big specification plane ceramic green body gel-casting method of buckling deformation |
-
2009
- 2009-11-02 CN CN 200910218750 patent/CN101700676B/en not_active Expired - Fee Related
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107283610A (en) * | 2017-07-10 | 2017-10-24 | 河北盛平电子科技有限公司 | A kind of drying means of ceramic body, preparation method and ceramic body |
| CN108358644A (en) * | 2018-03-06 | 2018-08-03 | 济南大学 | Based on xanthans gel casting forming TiB2The preparation method of composite ceramics biscuit |
| CN109176828A (en) * | 2018-08-16 | 2019-01-11 | 中国船舶重工集团公司第七二五研究所 | Prevent the big specification plane ceramic green body gel-casting method of buckling deformation |
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