煅烧对半水硫酸钙晶须稳定化的影响
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摘要
以二水硫酸钙(DH)为原料通过水热法合成半水硫酸钙(HH),再进行煅烧得到稳定的硫酸钙晶须。采用SEM、TG、XRD等分析方法,系统地研究了煅烧温度和煅烧时间对硫酸钙晶须稳定化的影响。结果表明,在200～600℃下,提高煅烧温度和延长煅烧时间,能有效促进硫酸钙晶须的稳定化;当煅烧温度为650℃、煅烧时间为1 h时,所得产物均为无水死烧硫酸钙晶须。无水死烧硫酸钙结构致密,水分子难进入晶体内部,不易水化,可以实现硫酸钙晶须的稳定化。
As a new type of filling material with excellent performance, calcium sulfate whisker has been widely used in many fields, such as plastics, papermaking and rubber. In this paper, calcium sulfate dihydrate(DH) was used as a raw material to synthesize calcium sulfate hemihydrate(HH) via hydrothermal synthesis followed by calcination,leading to anhydrous calcium sulfate(AH) whisker. The effects of calcination temperature and calcination time on the stabilization of calcium sulfate whiskers were systematically studied by SEM, TG, XRD and other analytical methods.The experimental results showed that the calcination temperature and the calcination time could effectively promote the stabilization of calcium sulfate whiskers at the temperature range between 200 °C and 600 °C. When the calcination temperature was 650 °C and the calcination time was 1 h, the obtained products were all dead roasted calcium sulfate(DAH). The crystal surface of HH showed hexagon channels, which contain the water crystals. Upon the treatment of calcination, the water molecules were evacuated out from the crystal along the channels, and the SAH with hexagon hollow holes were generated. Upon increasing the calcination temperature, the hollow channels of SAH collapsed due to the thermal motion of atoms in the crystals; and increasing the calcination time, the atoms continue to move and reorganize. On this basis, the DAH with stable structure was generated by controlling the calcination temperature and calcination time at appropriate values. Due to the dense structure of the DAH whisker, the access of water molecules into the crystal interior is dramatically limited. As a result, DAH is difficult to be hydrated, which endows the stabilization of calcium sulfate whisker. These results provide some fundamental basics for the selection of preparation technology parameters and the industrial production of the stabilized calcium sulfate whisker.
As a new type of filling material with excellent performance, calcium sulfate whisker has been widely used in many fields, such as plastics, papermaking and rubber. In this paper, calcium sulfate dihydrate(DH) was used as a raw material to synthesize calcium sulfate hemihydrate(HH) via hydrothermal synthesis followed by calcination,leading to anhydrous calcium sulfate(AH) whisker. The effects of calcination temperature and calcination time on the stabilization of calcium sulfate whiskers were systematically studied by SEM, TG, XRD and other analytical methods.The experimental results showed that the calcination temperature and the calcination time could effectively promote the stabilization of calcium sulfate whiskers at the temperature range between 200 °C and 600 °C. When the calcination temperature was 650 °C and the calcination time was 1 h, the obtained products were all dead roasted calcium sulfate(DAH). The crystal surface of HH showed hexagon channels, which contain the water crystals. Upon the treatment of calcination, the water molecules were evacuated out from the crystal along the channels, and the SAH with hexagon hollow holes were generated. Upon increasing the calcination temperature, the hollow channels of SAH collapsed due to the thermal motion of atoms in the crystals; and increasing the calcination time, the atoms continue to move and reorganize. On this basis, the DAH with stable structure was generated by controlling the calcination temperature and calcination time at appropriate values. Due to the dense structure of the DAH whisker, the access of water molecules into the crystal interior is dramatically limited. As a result, DAH is difficult to be hydrated, which endows the stabilization of calcium sulfate whisker. These results provide some fundamental basics for the selection of preparation technology parameters and the industrial production of the stabilized calcium sulfate whisker.
引文
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[17]吴士伟.半水硫酸钙晶须的稳定化研究[D].沈阳:东北大学,2008.
[18]WANG J C,TANG L J,WU D,et al.Application of modified calciumsulfate whisker in methyl vinyl silicone rubber composites[J].Polymers&Polymer Composites,2012,20(5):453-462.
[19]BOISVERT J P,DOMENECH M,FOISSY A,et al.Hydration of calcium sulfate hemihydrate(CaSO4·1/2H2O)into gypsum(CaSO4·2H2O):The influence of the sodium poly(acrylate)/surface interaction and molecular weight[J].Journal of Crystal Growth,2000,220:579-591.
[20]韩跃新,王宇斌,袁致涛,等.煅烧对硫酸钙晶须结构及稳定性的影响[J].化工矿物加工,2008(3):13-16.
[21]CHENG G C H.ZUSSMAN J The crystal structure of anhydrite(CaSO4)[J].Acta Crystallographica,1963,16:767-769.
[22]BEZOU C,NONAT A,MUTIN J C,et al.Investigation of the crystal structure ofγ-CaSO4,CaSO4·0.5H2O,and CaSO4·0.6H2O by powder diffraction methods[J].Journal of Solid State Chemistry,1995,117(1):165-176.
[23]FUJII K,KONDO W.Kinetics of hydration of calcium sulfate sulphate hemihydrate[J].Journal of the Chemical Society DaltonTransactions,1986(4):729-731.
[24]HAYNES W M.Handbook of Chemistry and Physics[M].New York:CRC Press,2016:862-865.
[2]RU X,MA B,HUANG J,et al.Phosphogypsum transition toα-calcium sulfate hemihydrate in the presence of omongwaite in nacl solutions under atmospheric pressure[J].Journal of the American Ceramic Society,2012,95(11):3478-3482.
[3]HOU S C,XIANG L.Influence of activity of CaSO4·2H2Oon hydrothermal formation of CaSO4·0.5H2O whiskers[J].Journal of Nanomaterials,2013,2013:1-5.
[4]周健.硫酸盐晶须改性ABS复合材料的性能与微观结构[J].化工学报,2010,61(1):243-248.
[5]FAN H,SONG X,LIU T,et al.Effect of Al3+on crystal morphology and size of calcium sulfate hemihydrate:Experimental and molecular dynamics simulation study[J].Journal of Crystal Growth,2018,495:29-36.
[6]向兰,王靖.水热法制备纳米分散颗粒和晶须材料进展[J].化工学报,2014,65(7):2638-2644.
[7]李延峰,张予新,张光旭,等.钾长石分解制备硫酸钙晶须工艺研究[J].无机盐工业,2013,45(3):25-27,33.
[8]MAO X,SONG X,LU G,et al.Control of crystal morphology and size of calcium sulfate whiskers in aqueous HCl solutions by additives:Experimental and molecular dynamics simulation studies[J].Industrial&Engineering Chemistry Research,2015,54(17):4781-4787.
[9]SONG X,ZHANG L,ZHAO J,et al.Preparation of calcium sulfate whiskers using waste calcium chloride by reactive crystallization[J].Crystal Research and Technology,2011,46(2):166-172.
[10]刘天杰,范浩,许妍霞,等.水化时间和温度对半水硫酸钙晶须水化过程的影响[J].华东理工大学学报(自然科学版),2018,44(1):9-14.
[11]LUO K,LI C,XIANG L,et al.Influence of temperature and solution composition on the formation of calcium sulfates[J].Particuology,2010,8(3):240-244.
[12]王宇斌,何廷树,袁致涛,等.温度对半水硫酸钙晶须水化过程的影响[J].硅酸盐通报,2013,32(10):1958-1961.
[13]LI Z,DEMOPOULOS G P.Model-based construction of calcium sulfate phase-transition diagrams in the HCl-CaCl2-H2O system between 0 and 100℃[J].Industrial&Engineering Chemistry Research,2006,45(13):4517-4524.
[14]王晓丽.硫酸钙晶须的表面改性研究[D].沈阳:东北大学,2005.
[15]袁致涛,韩跃新,王宇斌,等.低温煅烧下硫酸钙晶须水化性能的研究[J].中国非金属矿工业导刊,2007(64):104-106.
[16]PAN W,WANG P.Effect of compounding of sodium tripolyphosphate and super plasticizers on the hydration ofα-calcium sulfate hemihydrate[J].Journal of Wuhan University of Technology-Mater.Sci.Ed.,2011,26(4):737-744.
[17]吴士伟.半水硫酸钙晶须的稳定化研究[D].沈阳:东北大学,2008.
[18]WANG J C,TANG L J,WU D,et al.Application of modified calciumsulfate whisker in methyl vinyl silicone rubber composites[J].Polymers&Polymer Composites,2012,20(5):453-462.
[19]BOISVERT J P,DOMENECH M,FOISSY A,et al.Hydration of calcium sulfate hemihydrate(CaSO4·1/2H2O)into gypsum(CaSO4·2H2O):The influence of the sodium poly(acrylate)/surface interaction and molecular weight[J].Journal of Crystal Growth,2000,220:579-591.
[20]韩跃新,王宇斌,袁致涛,等.煅烧对硫酸钙晶须结构及稳定性的影响[J].化工矿物加工,2008(3):13-16.
[21]CHENG G C H.ZUSSMAN J The crystal structure of anhydrite(CaSO4)[J].Acta Crystallographica,1963,16:767-769.
[22]BEZOU C,NONAT A,MUTIN J C,et al.Investigation of the crystal structure ofγ-CaSO4,CaSO4·0.5H2O,and CaSO4·0.6H2O by powder diffraction methods[J].Journal of Solid State Chemistry,1995,117(1):165-176.
[23]FUJII K,KONDO W.Kinetics of hydration of calcium sulfate sulphate hemihydrate[J].Journal of the Chemical Society DaltonTransactions,1986(4):729-731.
[24]HAYNES W M.Handbook of Chemistry and Physics[M].New York:CRC Press,2016:862-865.
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