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A method for solidifying ceramic slurry by using metal ions in temperature-controlled slow-release sintering aid

A technology of ceramic slurry and metal ions, which is applied in the field of curing ceramic slurry by using metal ions in temperature-controlled slow-release sintering aids, can solve the problems of low strength of ceramic green blanks, long curing time, and uneven curing uniformity, etc. Facilitate large-scale production, good uniformity, improved density and comprehensive mechanical properties

Active Publication Date: 2020-01-21
HUAZHONG UNIV OF SCI & TECH +2
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] In view of the above defects or improvement needs of the prior art, the object of the present invention is to provide a method for solidifying ceramic slurry using metal ions in a temperature-controlled slow-release sintering aid, wherein the key solidification process principle and each reaction parameter (For example, the type, addition ratio, mode of action of the temperature-sensitive ester pH regulator, and the composition ratio of the ceramic slurry, etc.) are improved, and compared with the prior art, it can effectively solve the long curing time of the ceramic slurry and obtain The strength of the ceramic green body is low, or other impurities are introduced, and the uniformity of curing is not high. The present invention decomposes the acid by controlling the temperature of the ester pH regulator and chemically reacts with the metal oxide sintering aid in the ceramic slurry. High-priced counter ions are released to realize the direct solidification of the ceramic slurry, which can avoid the introduction of impurities during the curing process, and at the same time avoid problems such as uneven curing of the slurry caused by uneven mixing of the curing agent and the ceramic powder; and, the present invention uses The sintering aid provides the high-priced counter ions required for the curing of the ceramic slurry, which can not only achieve the uniform curing of the slurry, but also effectively reduce the sintering temperature, improve the density and comprehensive mechanical properties of the ceramic

Method used

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  • A method for solidifying ceramic slurry by using metal ions in temperature-controlled slow-release sintering aid

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0044] 0.7 wt% magnesia, 2.0 vol% diacetin solidified 50 vol% alumina slurry dispersed with 0.2 wt% ammonium citrate.

[0045] Mix 50 grams of alumina powder, 0.35 grams of magnesium oxide, 0.1 grams of ammonium citrate and 12.6 grams of water, and ball mill for 1.0 hour at a ball milling speed of 250 r / min to prepare negatively charged particles with a solid phase volume fraction of 50%. Then stir and degas under vacuum for 20 minutes, then add 0.68 ml of glycerol diacetate, stir with a glass rod for 30 seconds, then inject into the mold, place it at 70°C for 1 hour, then demould, and dry at 90°C After 24 hours, the temperature was raised to 1550° C. at a heating rate of 3° C. / min and kept for 4 hours for sintering. The relative theoretical density of the obtained ceramic dry body is 51.3%, and the shrinkage rate is 2.4%; the relative theoretical density of the obtained ceramic sintered part is 99.2%, and the shrinkage rate is 17.2%.

Embodiment 2

[0047] 1.5wt% magnesia, 0.5vol% glycerol triacetate solidified 55vol% zirconia slurry dispersed in 0.8wt% tetramethylammonium hydroxide.

[0048] Mix 50 grams of zirconia powder, 0.75 grams of magnesium oxide, 0.4 grams of tetramethylammonium hydroxide and 7.0 grams of water, and ball mill at a ball milling rate of 400 r / min for 0.5 hours to prepare particles with a solid phase volume fraction of 55%. Negatively charged ceramic slurry on the surface, then stirred and degassed under vacuum for 20 minutes, then added 0.15 ml of glycerol triacetate, stirred the glass rod for 15 seconds and then injected into the mold. ℃ for 48 hours, and then heated to 1450 ℃ at a heating rate of 6 ℃ / min for 6 hours for sintering. The relative theoretical density of the obtained ceramic dry body is 56.7%, and the shrinkage rate is 2.4%; the relative theoretical density of the obtained ceramic sintered part is 99.4%, and the shrinkage rate is 18.4%.

Embodiment 3

[0050] 1.0 wt% yttrium oxide, 3.0 vol% ethyl acetate solidified 50 vol% silicon nitride slurry dispersed in 0.2 wt% tetramethylammonium hydroxide.

[0051] 50 grams of silicon nitride powder, 0.5 grams of yttrium oxide, 0.1 grams of tetramethylammonium hydroxide and 15.7 grams of water were mixed, and ball milled at a ball milling rate of 200 r / min for 1.5 hours to prepare a solid phase volume fraction of 50%. Negatively charged ceramic slurry on the surface of the particles, then stirred and degassed under vacuum for 10 minutes, then added 0.47 ml of ethyl acetate, stirred the glass rod for 10 seconds, then injected into the mold, placed at 60 ° C for 1 hour, and demolded at 80 °C ℃ for 24 hours, and then heated to 1800 ℃ at a heating rate of 3 ℃ / min for 8 hours for sintering. The relative theoretical density of the obtained ceramic dry body is 57.2%, and the shrinkage rate is 2.3%; the relative theoretical density of the obtained ceramic sintered part is 99.0%, and the shrin...

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Abstract

The invention discloses a method for solidifying ceramic slurry by employing metal ions in a temperature-controlled slow-release sintering aid. The method comprises the following steps of firstly mixing ceramic powder, a dispersing agent, a metallic oxide sintering aid and water, carrying out full ball-milling to obtain the ceramic slurry with negatively charged particle surfaces; carrying out vacuum mixing on the slurry to degas and then adding an ester pH modifier, stirring evenly and then injecting a mixture into a mold, standing at 35-70 DEG C for 1-5 hours, demolding to obtain a wet ceramic body and drying to obtain a dry body; and then sintering to obtain a ceramic sintering body. An acid is decomposed from the ester pH modifier through temperature control to react with the sintering aid in the slurry to release highly-valence counter ions, so that direct coagulation casting of the ceramic slurry is achieved. A biscuit prepared by the method is good in uniformity; the sintering temperature can be effectively reduced and the consistency and the overall mechanical property of a sintered part can be effectively improved through adding the sintering aid; the method has the advantages of being suitable for any negatively charged ceramic slurry, friendly to environment and simple in operation; and massive production is easy to implement.

Description

technical field [0001] The invention belongs to the technical field of inorganic non-metallic ceramic slurry solidification, and more specifically relates to a method for solidifying ceramic slurry by using metal ions in a temperature-controlled slow-release sintering aid. Background technique [0002] The direct coagulation injection molding process (Direct Coagulation Casting, DCC) uses urease to catalyze urea to adjust the pH value of the slurry to the isoelectric point to reduce the repulsion energy between particles, or to increase the ion (counter ion) opposite to the surface charge of the particle. ) concentration, the double electron layer on the surface of the ceramic particles is compressed by the counterion to shorten the particle distance, and finally realize the in-situ solidification of different ceramic slurries. This process has the advantages of few organic additives, no debinding of the green body, uniform density of the green body, etc., and can form ceram...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C04B35/63C04B35/64
CPCC04B35/6303C04B35/64C04B2235/3206C04B2235/3217C04B2235/3225C04B2235/3244C04B2235/3249C04B2235/3272C04B2235/3281C04B2235/3418C04B2235/349C04B2235/3826C04B2235/3843C04B2235/3873C04B2235/6022C04B2235/606C04B2235/608C04B2235/77C04B2235/96
Inventor 吴甲民陈安南陈敬炎肖欢刘梦月马伊欣陈芬史玉升贺智勇
Owner HUAZHONG UNIV OF SCI & TECH
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