Improved method for preparing superfine high length-diameter-ratio anhydrous calcium sulfate crystal whiskers by using hydrothermal process

A technology of calcium sulfate anhydrous and calcium sulfate hemihydrate, applied in chemical instruments and methods, single crystal growth, crystal growth and other directions, can solve the problems of poor product morphology and long hydrothermal reaction time, and achieve uniform morphology , The effect of promoting fast directional arrangement and stable performance

Inactive Publication Date: 2015-04-01
TSINGHUA UNIV
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0007] The purpose of the present invention is to seek a kind of hydrothermal preparation method of fast preparation superfine high aspect ratio anhydrous calcium sulfate whisker, to overcome the defects of long hydrothermal reaction time and poor product morphology existing in the prior art, To further expand its industrial application

Method used

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  • Improved method for preparing superfine high length-diameter-ratio anhydrous calcium sulfate crystal whiskers by using hydrothermal process
  • Improved method for preparing superfine high length-diameter-ratio anhydrous calcium sulfate crystal whiskers by using hydrothermal process
  • Improved method for preparing superfine high length-diameter-ratio anhydrous calcium sulfate crystal whiskers by using hydrothermal process

Examples

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Effect test

Embodiment 1

[0028] Weigh 100 grams of calcium sulfate dihydrate (main content 95wt%, particle size less than 150 mesh) and place in a muffle furnace, roast at a constant temperature of 100°C for 6 hours to obtain active calcium sulfate hemihydrate; add active calcium sulfate hemihydrate containing 0.5wt % hydrochloric acid, 0.1wt% magnesium sulfate aqueous solution, made into a suspension with a solid content rate of 0.5wt%, reacted for 1 hour at 10°C under stirring (50 rpm), filtered, washed and dried at 80°C for 1 hour hour, obtain instant calcium sulfate hemihydrate; instant calcium sulfate hemihydrate is added to the saturated calcium sulfate solution containing 0.0001wt% sodium ethylenediamine tetraacetate, 0.001wt% sodium fluoride, and the solid content rate is made into 0.1wt%. The suspension was hydrothermally reacted at 100°C and stirred (250 rpm) for 2 minutes, cooled, filtered, washed, and dried (80°C, 1 hour) to obtain a main content of 95wt%, a diameter of 10 μm, and a length ...

Embodiment 2

[0030] Weigh 100 grams of calcium sulfate dihydrate (main content 99wt%, particle size less than 150 mesh) and place in a muffle furnace, and roast at a constant temperature of 180°C for 1 hour to obtain active calcium sulfate hemihydrate; add active calcium sulfate hemihydrate containing 50wt% The aqueous solution of sulfuric acid and 20wt% magnesium nitrate was made into a suspension with a solid content rate of 50wt%, reacted at 80°C under stirring (500 rpm) conditions for 1 hour, filtered and washed and dried at 110°C for 1 hour to obtain Instant calcium sulfate hemihydrate; Instant calcium sulfate hemihydrate is added to the saturated calcium sulfate solution containing 1wt% sodium dodecylsulfonate, 5wt% potassium fluoride to make a suspension with a solid content rate of 25wt%. 200 ° C, stirring (500 rpm) under the condition of hydrothermal reaction for 20 minutes, cooling, filtering, washing, drying (110 ° C, 6 hours), to obtain a main content of 99.2wt%, a diameter of 5...

Embodiment 3

[0032] Weigh 100 grams of calcium sulfate dihydrate (main content 96.4wt%, particle size less than 150 mesh) and place in a muffle furnace, and roast at a constant temperature of 150°C for 3 hours to obtain active calcium sulfate hemihydrate; add active calcium sulfate hemihydrate containing 20wt % nitric acid, 5wt% magnesium chloride aqueous solution, made into a suspension with a solid content rate of 10wt%, reacted for 4 hours at 50°C under stirring (250 rpm) conditions, filtered, washed and dried at 100°C for 5 hours to obtain Instant calcium sulfate hemihydrate; add instant calcium sulfate hemihydrate to a saturated calcium sulfate solution containing 0.1wt% sodium dodecylbenzenesulfonate and 1wt% ammonium fluoride to make a suspension with a solid content of 10wt%. , hydrothermal reaction at 140°C, stirring (150 rpm) for 10 minutes, cooling, filtering, washing, and drying (105°C, 4 hours), to obtain a main content of 97wt%, a diameter of 0.005μm, a length of 50μm, and an ...

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Abstract

The invention discloses an improved method for preparing superfine high length-diameter-ratio anhydrous calcium sulfate crystal whiskers by using a hydrothermal process and belongs to the technical field of preparation of inorganic chemical materials. The improved method for preparing the superfine high length-diameter-ratio anhydrous calcium sulfate crystal whiskers by using the hydrothermal process takes calcium sulphate dihydrate as the raw material and comprises the following steps: firstly activating and roasting at the low temperature to prepare active calcium sulfate hemihydrates, subsequently doping, acidizing, hydrating and drying to prepare a quick-soluble calcium sulfate hemihydrates precursor with the structure defects; then adding the precursor into a saturated calcium sulphate liquid containing a chaotropic agent and a polar solvent, carrying out hydrothermal reaction at 100-200 DEG C for 2-20 minutes, cooling, filtering, washing and drying to prepare superfine high length-diameter-ratio calcium sulfate hemihydrate crystal whiskers with diameter of 0.005-10 microns, length of 10-5000 microns, length-diameter-ratio of 100-10000, and main content of greater than 95%; then mixing the calcium sulfate hemihydrates crystal whiskers with a trace solvent, roasting at 600-800 DEG C for 1-6 hours, cooling, filtering, washing and drying to prepare the superfine high length-diameter-ratio anhydrous calcium sulfate crystal whiskers with appearance which is as same as that of the calcium sulfate hemihydrates crystal whiskers and main content of greater than 95wt%. The improved method for preparing the superfine high length-diameter-ratio anhydrous calcium sulfate crystal whiskers by using the hydrothermal process is rapid and simple in process and low in costs; and the prepared superfine high length-diameter-ratio anhydrous calcium sulfate crystal whiskers can be used as reinforcement materials.

Description

technical field [0001] The invention relates to an improved preparation method of ultrafine high aspect ratio anhydrous calcium sulfate whiskers, belonging to the technical field of preparation of inorganic chemical materials. Background technique [0002] my country has abundant natural gypsum and industrial by-product gypsum resources, which provide good conditions for the development of calcium sulfate whisker materials. Compared with other whisker materials, calcium sulfate whiskers have the characteristics of good mechanical strength, non-toxicity, stability, and low price. Therefore, its controllable preparation has attracted increasing attention in recent years. [0003] In 1976, the U.S. patent literature (US3961105 and US patent 3961105) and the German patent literature (DE2613651) introduced the method of using calcium sulfate dihydrate as raw material for the first time and adopting hydrothermal reaction-roasting method to prepare anhydrous calcium sulfate whiske...

Claims

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Application Information

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IPC IPC(8): C30B7/10C30B29/62C30B29/46
Inventor 向兰侯思超
Owner TSINGHUA UNIV
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