采用微波烧结新技术研究了纳米金属陶瓷材料的烧结工艺与性能。结果表明:微波烧结Al2O3 TiC Mo Ni纳米金属陶瓷在1500℃的温度下保温10min时,可达到99.0%的相对密度;使烧结温度降低,烧结时间大幅度缩短,且烧结前后晶粒粒径分别为35和55...采用微波烧结新技术研究了纳米金属陶瓷材料的烧结工艺与性能。结果表明:微波烧结Al2O3 TiC Mo Ni纳米金属陶瓷在1500℃的温度下保温10min时,可达到99.0%的相对密度;使烧结温度降低,烧结时间大幅度缩短,且烧结前后晶粒粒径分别为35和55nm,变化很小。展开更多
为降低新鲜茭白冻干作业能耗,提高冻干成品的品质,以总能耗、体积保留率、复水比、色差值为考察指标,开展了热板冻干、微波冻干、热板-微波联合冻干试验研究。研究表明:35℃热板冻干后茭白品质好,但能耗高;60℃热板冻干能耗低,但水分升...为降低新鲜茭白冻干作业能耗,提高冻干成品的品质,以总能耗、体积保留率、复水比、色差值为考察指标,开展了热板冻干、微波冻干、热板-微波联合冻干试验研究。研究表明:35℃热板冻干后茭白品质好,但能耗高;60℃热板冻干能耗低,但水分升华过快对茭白微观结构造成较大破坏,降低了茭白品质;采用35℃热板冻干8 h后,再采用60℃热板冻干或3 k W微波冻干可有效降低冻干能耗,同时冻干后茭白品质良好。在此基础上,采用均匀设计法,开展热板-微波联合冻干工艺参数优化试验研究,通过逐步回归分析,得出了冻干总能耗、体积保留率、复水比、色差关于加热板温度、脱水转换点、微波功率的三元二次回归方程,并通过四维切面等位线图分析了上述4个考察指标受3个试验因素取值变化的影响机理。最后,采用综合加权评分和逐步回归分析得出综合指标关于加热板温度、脱水转换点、微波功率的回归方程,进一步确定加热板温度为30℃、脱水转换点为72%、微波功率为3 k W为最优的热板-微波联合冻干工艺参数,此时综合加权评价指标值76.07,总能耗、体积保留率、复水比、色差分别为90.6 k W·h、51.86%、10.59、4.32。该研究为制定产品优良、高效节能的冻干工艺提供参考。展开更多
In order to improve the flocculation efficiency of polydiallyldimethylammonium chloride（PDADMAC）, high molecular weight PDADMAC should be prepared from high purity diallyldimethylammonium chloride（DADMAC） monomers...In order to improve the flocculation efficiency of polydiallyldimethylammonium chloride（PDADMAC）, high molecular weight PDADMAC should be prepared from high purity diallyldimethylammonium chloride（DADMAC） monomers. In this paper, a cleaner method with microwave irradiation and alkali solidification was proposed for preparing high pure DADMAC by selective heating under low temperature, and the prepared high purity DADMAC is characterized using FTIR and atomic absorption spectrometry. The new method provides a solution to the key technical problem of PDADMAC synthesis. Comparing with the conventional methods, the results showed that the advantages of the novel synthesis include： （a） high purity DADMAC is improved from 57% to 71% ; （b） reaction time of tertiary amine preparation is shortened from 6 h to 7 min; （c） water instead of acetone was used as reaction medium; （d） toxic by-products, wastewater and waste gas are eliminated. Flocculant made from the synthesized high purity DADMAC monomers was proved more efficient in flocculation tests.展开更多
文摘为降低新鲜茭白冻干作业能耗,提高冻干成品的品质,以总能耗、体积保留率、复水比、色差值为考察指标,开展了热板冻干、微波冻干、热板-微波联合冻干试验研究。研究表明:35℃热板冻干后茭白品质好,但能耗高;60℃热板冻干能耗低,但水分升华过快对茭白微观结构造成较大破坏,降低了茭白品质;采用35℃热板冻干8 h后,再采用60℃热板冻干或3 k W微波冻干可有效降低冻干能耗,同时冻干后茭白品质良好。在此基础上,采用均匀设计法,开展热板-微波联合冻干工艺参数优化试验研究,通过逐步回归分析,得出了冻干总能耗、体积保留率、复水比、色差关于加热板温度、脱水转换点、微波功率的三元二次回归方程,并通过四维切面等位线图分析了上述4个考察指标受3个试验因素取值变化的影响机理。最后,采用综合加权评分和逐步回归分析得出综合指标关于加热板温度、脱水转换点、微波功率的回归方程,进一步确定加热板温度为30℃、脱水转换点为72%、微波功率为3 k W为最优的热板-微波联合冻干工艺参数,此时综合加权评价指标值76.07,总能耗、体积保留率、复水比、色差分别为90.6 k W·h、51.86%、10.59、4.32。该研究为制定产品优良、高效节能的冻干工艺提供参考。
基金The National 10th Five-year Science and Technology Project of China(No.2002BA806b04-01B) and the Hi-Tech Research and Development Program(863) of China(No.2002AA601310)
文摘In order to improve the flocculation efficiency of polydiallyldimethylammonium chloride（PDADMAC）, high molecular weight PDADMAC should be prepared from high purity diallyldimethylammonium chloride（DADMAC） monomers. In this paper, a cleaner method with microwave irradiation and alkali solidification was proposed for preparing high pure DADMAC by selective heating under low temperature, and the prepared high purity DADMAC is characterized using FTIR and atomic absorption spectrometry. The new method provides a solution to the key technical problem of PDADMAC synthesis. Comparing with the conventional methods, the results showed that the advantages of the novel synthesis include： （a） high purity DADMAC is improved from 57% to 71% ; （b） reaction time of tertiary amine preparation is shortened from 6 h to 7 min; （c） water instead of acetone was used as reaction medium; （d） toxic by-products, wastewater and waste gas are eliminated. Flocculant made from the synthesized high purity DADMAC monomers was proved more efficient in flocculation tests.
