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A kind of method that calcium sulfate hemihydrate whisker prepares

A technology of calcium sulfate hemihydrate and calcium sulfate, applied in chemical instruments and methods, calcium/strontium/barium sulfate, single crystal growth, etc., can solve the problem of large solidification of α-calcium sulfate hemihydrate, low conversion rate, Low strength and other problems, to achieve the effect of high aspect ratio, uniform length and diameter, and mild reaction conditions

Inactive Publication Date: 2011-12-07
中国人民解放军第三五九医院 +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] Using dihydrate gypsum as raw material, it is prepared by hydrothermal method or steam pressurization method. The obtained α-calcium sulfate hemihydrate generally solidifies in a large crystal form and has low strength. It needs to add a crystal modifier, and the conversion rate is low.

Method used

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  • A kind of method that calcium sulfate hemihydrate whisker prepares
  • A kind of method that calcium sulfate hemihydrate whisker prepares

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0016] Amorphous calcium sulfate preparation:

[0017] Prepare 750 ml each of 0.5 mol / L potassium sulfate and 0.5 mol / L calcium nitrate, mix them in a 2 L beaker, stir with electric power for 30 min, let stand for 24 h, filter, and store the obtained filter cake.

[0018] Determination of moisture content of filter cake:

[0019] Weigh a filter cake with a mass of about 1 g in a small crucible, calcined at 400 °C for 3 h, take it out and weigh it, and calculate its water content.

[0020] Preparation of α-calcium sulfate hemihydrate whiskers:

[0021] Dissolve amorphous calcium sulfate in deionized water, stir for 10 min, and ultrasonically disperse for 20 min to prepare 50 ml of calcium sulfate suspension with a mass fraction of about 5%. Move the suspension to a 100 ml high-pressure hydrothermal reactor, under saturated vapor pressure, the reaction temperature is 110 °C, and the reaction time is 6 h. Calcium sulfate hemihydrate whiskers.

[0022] Determination of water c...

Embodiment 2

[0029] Same as Example 1, but changing the reaction temperature to 120°C, 130°C, and 140°C respectively, the results obtained are shown in Table 1.

[0030] It can be seen from Table 1 that the water content of the raw material amorphous calcium sulfate is between about 45% and 50%. When the reaction time was 12 h and the reaction temperature increased from 110°C to 140°C, the water content of the product first increased from 0.44% to 3.29%, then decreased from 3.29% to 1.14%, and the aspect ratio first increased from 21 to 35, and then reduced from 35 to 25, which shows that raising the reaction temperature is conducive to the increase of the aspect ratio of the product, but too high a reaction temperature makes the product easy to lose water, which is not conducive to the production of calcium sulfate hemihydrate, resulting in a decrease in the aspect ratio , so the optimum reaction temperature is 120 ℃.

[0031] In Example 2, when the reaction temperature is 120°C, the dry...

Embodiment 3

[0034] Same as in Example 1, but keep the reaction temperature at 120 °C, the reaction time at 18 h, the drying time at 6 h, and change the drying temperature to 115 °C and 135 °C respectively. The results are shown in Table 2.

[0035]

[0036] It can be seen from Table 2 that when the reaction temperature is 120 °C, the reaction time is 18 h, and the drying time is 6 h, when the drying temperature increases from 115 °C to 135 °C, the water content of the product first increases from 2.55% to 2.83%. As the drying temperature decreased to 2.69%, the increase in water content was due to the continuous transformation of amorphous calcium sulfate to calcium sulfate hemihydrate. The unit cell parameters a:b:c values ​​are 12.02:6.88:2.69, and the α-calcium sulfate hemihydrate unit cell parameters a:b:c values ​​are 12:6:12, which are close to it, indicating that the main product of the product It is α-calcium sulfate hemihydrate whiskers. The aspect ratios are 18, 21 and 16, r...

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Abstract

The invention relates to a method for preparing alpha-hemihydrate calcium sulfate crystal whisker. The method comprises the following steps: (1) mixing K2SO4 and Ca(NO3)2.5H2O according to a mole ratio of the K2SO4 to the Ca(NO3)2.5H2O of 1:1, carrying out electric stirring for 30 minutes to prepare amorphous calcium sulfate; (2) dissolving the amorphous calcium sulfate into deionized water, carrying out stirring for 10 minutes, the carrying out ultrasonic dispersion for 20 minutes to prepare calcium sulfate suspension liquid having a mass fraction of 4-6%; transferring the calcium sulfate suspension liquid to a high pressure hydro-thermal reaction kettle, then carrying out a reaction for 6-18 hours under saturated vapor pressure at a reaction temperature of 110-140 DEG C, filtering the resulting precursor when the precursor is hot, followed by carrying out forced air drying for 6-8 hours at the temperature of 110-130 DEG C to prepare the alpha-hemihydrate calcium sulfate crystal whisker. According to the present invention, the amorphous calcium sulfate is adopted as the raw material, the crystal modifier is not required; the prepared alpha-hemihydrate calcium sulfate crystal whisker has characteristics of high purity, uniform long diameter and high length-diameter ratio; the reaction conditions are mild; the production process accords with the requirements of the industrial production.

Description

technical field [0001] The invention relates to a calcium sulfate hemihydrate whisker (specifically α-CaSO 4 ?0.5H 2 O) The method of preparation, specifically refers to using amorphous calcium sulfate as raw material, using hydrothermal method, at a reaction temperature of 110 ℃ ~ 140 ℃, a reaction time of 6 h ~ 18 h, and a drying temperature of 110 ~ 130 ℃, A method for preparing α-calcium sulfate hemihydrate whiskers with a drying time of 6 to 8 h. Background technique [0002] Due to their small diameter, whiskers are highly ordered in atomic arrangement during crystallization, which changes the defects of voids and dislocations that conventional materials have. Therefore, calcium sulfate whiskers have unique and excellent properties. Calcium sulfate whisker is a fibrous substance with high cost performance. It is an environmentally friendly material with excellent performance and low price. It has strong market competitiveness and can be widely used in reinforced pla...

Claims

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Application Information

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IPC IPC(8): C30B7/10C30B29/22C30B29/62C01F11/46
Inventor 陈建民刘方刚殷恒波冯永海陆秀凤王爱丽祝永强高军吴占敖
Owner 中国人民解放军第三五九医院
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