39results about How to "Control crystal form" patented technology

The present invention is a silicon carbide smelting method, the steps of which are as follows: carry out the following treatment on the selected silicon carbide which will be used as the seed crystal: crushing treatment and screening treatment, selecting silicon carbide with a particle size of 3 to 8 millimeters and adopting pickling method Carry out purification treatment, and then rinse with pure water; place 0.1%~5% 6H silicon carbide seed crystals within 0~10cm, and place 0.3%~8H 6H silicon carbide seed crystals within 10cm~25cm, centering on graphite electrodes. %, place 1%~10% 4H silicon carbide seed crystals within the range of 25cm~40cm. The method of the invention has reasonable design and strong operability. By adding seed crystals in silicon carbide smelting, the growth efficiency of silicon carbide can be effectively improved, the crystal form of silicon carbide can be effectively controlled, and energy consumption can be reduced.

The invention discloses a method for preparing phase-change microcapsules by a hydrothermal method, comprising: preparation of phase-change material emulsion; dropping bismuth salt solution into the phase-change material emulsion, stirring, and then adding tungstate solution or borax solution Drop into the phase change material emulsion, stir, and in the process of stirring, use ammonia water to adjust and adjust the phase change material emulsion to be neutral, and obtain the phase change material emulsion containing the shell precursor; the phase change material emulsion containing the shell precursor Adding it into a hydrothermal reaction kettle for hydrothermal reaction; cooling the system after the hydrothermal reaction to room temperature, taking out the phase-change microcapsules, washing with deionized water, and drying to obtain the phase-change microcapsules. The invention adopts the hydrothermal method in the preparation of phase change microcapsules, which has the advantages of simple reaction, adjustable temperature and controllable product morphology; meanwhile, organic solid-liquid phase change material is used as the core material, which is an inorganic material with radiation protection function As the shell material, the prepared phase change microcapsules have dual functions of phase change energy storage and radiation protection.

Provided is a method for producing fine particles, comprising: a dissolving step of dissolving at least one kind of fine particle raw materials in a solvent using a stirrer having a rotating stirring blade to obtain a fine particle raw material solution; At least one of the precipitated solvents and the fine particle raw material solution are introduced between at least two processing surfaces that are oppositely arranged, accessible and / or separate, and at least one of them rotates relative to the other. This is a precipitation step in which fine particles are precipitated by mixing in the thin film fluid formed between the treatment surfaces. In the above-mentioned dissolving step, the stirring energy specified by the stirring time conditions using the stirrer, the peripheral speed conditions of the stirring blades, and the temperature conditions of the fine particle raw material solution is increased or decreased by changing at least one of the above conditions. , by increasing or decreasing the stirring energy, the crystallinity and crystal form of the particles obtained in the precipitation step are controlled.

The invention relates to a preparation method of fine aspirin crystals, belonging to the field of medical and chemical engineering. The preparation method comprises the following steps: (1) putting salicylic acid, acetic anhydride and fine aspirin crystal mother liquor into a dissolving tank to be stirred, and after rising the antipyretic temperature to 80-90 DEG C to dissolve, preserving the temperature for 1-2 hours to obtain hot liquor; (2) adding acetic anhydride, fine aspirin crystal mother liquor or the mixture of acetic anhydride and fine aspirin crystal mother liquor into a crystallizing tank to stir to obtain cold liquor; (3) filtering the hot liquor after preserving temperature to the crystallizing tank, controlling the temperature of the crystallizing tank in the filtering process to gradually rise, after preserving temperature after filtering, and then cooling and carrying out centrifugal separation to obtain solid state fine aspirin crystals. The obtained fine aspirin crystals mother liquor is recycled to the steps (1) and (2). According to the method provided by the invention, the crystal form, the uniformity and the granularity which are fine aspirin crystals are effectively controlled, so that the preparation method is environment-friendly, and the product yield is improved and the production cost is lowered.