基于均匀形核的金属液滴凝固过程

研究了均匀形核的金属液滴凝固过程,应用渐近分析法求得金属液滴内晶核生长数学模型的渐近解,分析了表面张力、界面动力学参数、初始晶核尺寸和过冷度对晶核界面生长速度、晶核半径以及液滴凝固时间的影响.在一定的过冷条件下,表面张力和界面动力学参数显著减缓了晶核界面生长速度.在凝固开始的很短时间内晶核界面生长速度迅速上升,当速度上升到最大值后,随着晶核半径的增大,界面生长速度逐渐减慢,表面张力和界面动力学参数对晶核生长速度的作用也逐渐减小.过冷度越大,液滴凝固时间越短.经过在开始的瞬变凝固阶段之后,温度场从设定的初始分布迅速地调整为由过冷度、表面张力、界面动力学参数等所确定的特定温度分布.      

含碳球团还原过程中粘接行为的量化研究

通过负荷还原试验,在温度为分别为1173,1273和1373K,负荷为0.1MPa,N2流量为1.0L/min条件下对含碳球团还原过程的粘接行为进行了研究,并且对粘结临界状态进行了明确界定,对粘结指数的测定方法进行了改进。研究表明,含碳球团在还原过程中出现粘接现象,温度是影响粘结的重要因素,温度越高,粘接越严重,1373K时,含碳球团的粘结指数达到88.7%,粘结指数能够客观地反映出含碳球团在还原过程中的粘接情况,铁连晶和氧化亚铁连晶生长出界造成含碳球团的粘接,温度的升高,铁链晶和氧化亚铁连晶长大速度变大,使连晶生长出界的可能性变大,球团粘接变得严重。     

铅对蚕豆种子萌发及根生长的影响

[目的]研究铅对蚕豆种子萌发、根生长以及细胞分裂的影响.[方法]用不同浓度的PbCl<,2>溶液培养蚕豆种子,以蒸馏水培养作为对照,统计蚕豆种子萌发率,测量根长,根尖固定、染色、压片后镜检,计算有丝分裂指数.[结果]1.0×10<'-4>～5.0×10<'-4>mol/L Pb<'2+>处理第1、2天,蚕豆种子萌发率稍高于对照,培养第3、4天则与对照相当,Pb<'2+>对蚕豆种子的萌发没有显著影响.Pb<'2+>对蚕豆根尖生长产生抑制作用,随着浓度增加,根的生长速率递减,随着处理时间延长,每单位时间的根生长速度递减或停止.根尖细胞有丝分裂指数随Pb<'2+>浓度的增高和处理时间的延长而递减.[结论]Pb<'2+>对蚕豆根尖生长发育有影响,其影响程度与Pb<'2+>处理浓度、处理时间有关.     

氢化锆与O_2反应制备氢渗透阻挡层的研究

采用原位氧化的方法,通过氢化锆直接与O2反应在表面生成氧化膜作为氢渗透阻挡层。分析了氧化工艺参数对氧化膜生长速度的影响,并对氧化膜的物相组成、截面形貌和阻氢性能进行了研究。结果表明,温度是影响氧化膜生长速度的主要因素,氢化锆在450℃以下的温度范围内氧化,氧化膜生长速度很小,氧气分压对氧化膜生长速度无明显影响;在450℃以上,氧化膜生长速度随着氧气分压的增大和氧化温度的升高而增大;氧化膜的质量增重与氧化时间的关系曲线符合抛物线生长规律。氧化膜为双相复合结构,由单斜相M-ZrO2和四方相T-ZrO2组成。氢化锆原位氧化后经650℃真空脱氢50 h后样品失氢量低于0.2%。     

Ti—Cl—H—N体系化学气相沉积TiN动力学和机构

本文研究了热壁反应器内沉积参数对 TiN 沉积速度的影响,确定了化学平衡生长、传质限制生长和表面过程限制生长的沉积条件。在表面过程控制范围内,提出了化学气相沉积(CVD)TiN 机构,推导了 TiN 沉积速度方程。用实验证明 HCl 是阻碍剂,它对基体的刻蚀作用可以忽略。获得了添加 HCl 后的 TiN 沉积速度方程,方程计算结果与实验结果一致。     

300 mm单晶硅生长过程中直径的功率控制方法

直拉法硅单晶生长过程微缺陷的形成和长大遵循Voronkov提出的V/G(V是晶体生长速度,G是晶体生长界面的轴向温度梯度)理论.在G由热场设计和液面位置决定的前提下,单晶硅生长过程中品体提升速度的精确控制是生长无空洞型原生微缺陷大尺寸单晶硅的关键.为控制品体的提升速度处于无原生微缺陷单晶硅生长所需的范围内,同时获得±1...     

烟煤胶质层指数准确度的试验

介绍了烟煤胶质层指数的测定方法,分析了煤样粒度、装样量、升温速度等对烟煤胶质层指数测定的影响,对传统法与半自动法的胶质层指数测定准确度进行了试验,该试验结果准确,能满足邯钢焦化厂的生产需要。     

Ca2+对蚕豆种子萌发及根生长的影响

[目的]研究不同浓度Ca<'2+>对蚕豆种子萌发、根长以及根尖细胞有丝分裂的影响.[方法]用不同浓度的CaCl<,2> 溶液培养蚕豆种子,以蒸馏水培养为对照,统计不同处理下蚕豆种子萌发率;测量根长;根尖固定、染色、压片后进行观察,计算有丝分裂指数.[结果]1.0-5.0 mmol/L Ca<'2+> 对蚕豆种子萌发没有影响.当Ca<'2+> 浓度超过10.0 mmol/L后,随着Ca<'2+>浓度的增高,蚕豆种子萌发速率降低,但对最终萌发率没有影响;1.0-10.0mmol/L Ca<'2+> 能不同程度地促进蚕豆根生长和细胞分裂,其中5.0mmol/L Ca<'2+> 处理的蚕豆根长和有丝分裂指数最高,之后随着Ca<'2+> 浓度的继续增高,根生长和细胞分裂速度开始下降,甚至受到抑制.[结论]Ca 是植物体生长的必需元素,但Ca<'2+> 浓度过高不利于植物生长发育,这为合理施用钙肥提供了科学依据.     

熔剂配比对烧结矿质量的影响

系统研究了生石灰含量的提高对烧结矿质量的影响规律并揭示了其作用机理。结果表明:随着生石灰含量的升高,烧结矿成品率和垂直烧结速度出现先升高后下降、转鼓指数出现先升高后平稳再下降、而低温还原粉化指数出现逐渐升高的趋势。综合分析各指标确定生石灰最佳配比,保证成品率、垂直烧结速度、转鼓指数、低温还原粉化指数最佳。利用扫描电子显微镜(SEM)对烧结矿矿相进行分析,从微观角度阐明不同生石灰含量对烧结矿冶金性能的影响机理。     

用超声波对球铁生产进行质量控制

本文表述了一些在合理建立机械性能与超声波检查之间有关的物理本质概念，特别强调的是对球铁在线生产建立了石墨形态Ss和石墨析出平均数NA对拉伸强度和纵向超声波速度影响的评价。以契形试块进行试验，试验包括拉伸、组织检测和纵向超声波速度检测，试样拉伸产生断裂时检测的纵向超声波速度、平均石墨析出数，石墨形态指数，得出了机械性能，石墨形态指数和石墨析出数量与纵向超声波速度之间的关系。     

Mechanism of Effect of Lanthanum Nitrate on Vigor of Aged Rice Seeds

Ｓｅｅｄｓｅａｒｌｙｄｅｇｅｎｅｒａｔｅｄｏｒａｇｅｄｂｙｕｎ ｓｕｉｔａｂｌｅｃｕｌｔｉｖａｔｉｏｎｏｒｕｎｓｔｏｒａｇｅｔｅｃｈｎｉｑｕｅｓｍａｙｒｅｓｕｌｔｉｎｄｅｃｒｅａｓｉｎｇｏｆｓｅｅｄｖｉｇｏｒａｎｄｏｆｔｈｅｃｒｏｐｓｏｕｔｐｕｔ,ｅｓｐｅｃｉａｌｌｙｆｏｒｒｉｃｅ.Ｒａｒｅｅａｒｔｈｓａｃｃｅｌｅｒａｔｅｔｈｅｇｅｒｍｉｎａｔｉｏｎａｎｄｇｒｏｗｔｈｏｆｔｈｅｃｒｏｐｓ ,ｓｕｃｈａｓｒｉｃｅ ,ｗｈｅａｔ,ｂａｒｌｅｙ ,ｖｅｇ ｅｔａｂｌｅｓａｎｄｏｉｌｐｌａｎｔｓ[1～ 3] .Ｔｈｅｓｔ…     

Effects of Rare Earth Elements on Vigor Enhancement of Aged Spinach Seeds

Inthe 1 970s ,asakindofmicroelementfertilizerinagriculture ,rareearthelements (REEs)wereusedtoachieveanotablecropyieldinChina[1～ 3] .Alargenumberofexperimentsindicatedthatthegerminationrateandvigorofseedswereincreasedbythetreatmentwithrareearthelements ,andthegrowthofseedlingswasalsopromoted .Hongetal.provedthatsoakingseedswithLa3+ ,andCe3+ couldacceleratetheger minationofriceseeds ,greatlypromoteseedvigor ,in creasetherespirationofgerminatedseeds ,obviouslyactivatesomehydrolyticenzymessuch…     

硝酸铈对水稻种子活力和萌发期间酶活性的影响

用２．５～３０ｍｇ／ＬＣｅ（ＮＯ３）３浸泡水稻种子能明显提高稻种的活力，促进幼苗的生长。这与Ｃｅ提高稻种萌发期间的呼吸速率、增加淀粉酶、蛋白酶和脂肪酶等水解酶的活性有密切关系。其中用１０ｍｇ／Ｌ浓度的Ｃｅ（ＮＯ３）３浸种效果最好。当浓度超过５０ｍｇ／Ｌ时，种子的萌发、呼吸作用及三种酶的活性均受到抑制。     

Effect of Cerium on Seed Germination under Acid Rain Stress

Ｐｌａｎｔｓｈａｒｍｅｄｂｙｔｈｅａｃｉｄｉｃｒａｉｎｉｎｔｅｒｒｅｓ ｔｒｉａｌｅｃｏｓｙｓｔｅｍｓｈａｓｂｅｅｎｒｅｐｏｒｔｅｄｉｎｍａｎｙｃａｓｅｓ[1～ 4] .Ｍａｃｒｏｓｃｏｐｉｃａｎａｌｙｓｉｓｓｈｏｗｓｔｈａｔａｃｉｄｒａｉｎｈａｒｍｓｐｌａｎｔｓｔｏｔｈｅｉｒｇｒｏｕｎｄａｎｄｕｎ ｄｅｒｇｒｏｕｎｄｏｒｇａｎｓａｎｄｔｈｅｌａｔｔｅｒｉｓｄｕｅｔｏｔｈｅａｃｉｄｉｆｉｃａｔｉｏｎｏｆｓｏｉｌｅｎｖｉｒｏｎｍｅｎｔ.Ｉｔｆｏｌｌｏｗｓｔｈａｔｔｈｅａｃｉｄｉｆｉｅｄｓｏｉｌａｆｆｅｃｔｓ…     

稀土浸种对油菜种子萌发及种苗生长的生物效应

浓度低于（８００μｇ／ｍＬ）稀土可促进油菜种子萌发的启动。使用浓度为１００μｇ／ｍＬ,１２小时计数其发芽率为２５％,对照为１２％。但浓度高于１０００μｇ／ｍＬ时,会明显抑制萌发。处理浓度低于８００μｇ／ｍＬ时,稀土浸种对油菜种苗根系的生长有明显促进作用。表现为根长、根鲜重增加,根系活力和幼根内源激素—ＧＡｓ、ＩＡＡ含量都得到提高。幼苗子叶中叶绿素含量提高。高浓度（＞１０００μｇ／ｍＬ）对幼苗生长会有抑制作用,正常苗的百分比下降。     

Effect of La3+ on seed germination and seedling growth of Salvia miltiorrhiza

The purpose of this study is to determine the effect of La³⁺ solution on seed germination and seedling growth of Salvia miltiorrhiza. Different concentrations of La³⁺ were used on seed by soaking treated to determine which concentration is the most suitable for the growth of S. miltiorrhiza. Results show that the low concentration of La³⁺ displays the promotion effect on S. miltiorrhiza seed germination rate and germination potential, and the promotion effect reaches the highest level when the concentration of La³⁺ solution is 30 mg/L, the germination index and vigor index are the highest in 20 mg/L, and it can also increase the contents of soluble sugar, soluble protein and chlorophyll. Meanwhile, the activity of antioxidant enzyme system (CAT and SOD) are improved, thus the photosynthesis and resistance of plant are enhanced. On the contrary, when the La³⁺ concentration is high, La³⁺ can inhibit plant growth. Thus La³⁺ displays the "homesis effect" on S. miltiorrhiza growth.     

Control effect of lanthanum against plant disease

Effect of La on emergence, growth and development of Isatis indigotica Fort. and Festuca arundinacea seedlings was researched by pot experiments of inoculating Rhizoctonia solani and with the mixture ofRhizoctonia solani and Fusarium solani in disinfected soil after the seeds were soaked in the solution with different concentrations of La^3＋. The results indicated that infection rate decreased and there were significant disease controlling effects on seed rot, bud rot and root rot caused by pathogenic fungi when the seeds were soaked by La^3＋. Thus, the rates of emergence of Isatis indigotica Fort. and turfgrass Festuca arundinacea were increased, When La^3＋ concentration was in a proper range, the growth and development of plant seed/ings were promoted. Spraying La on rice plants showed a significant controling effect on Rhizoctonia solani. Furthermore, the EC50 of La^3＋performed 128.7 and 128.1 mg/L at 1 and 7 d after spraying La in rice plants, respectively. The EC50 of La^3＋ performed in vivo （in rice plant） was lower than that in vitro （171.9 mg/L）.     

Structures and electrochemical performances of as-cast and spun RE-Mg-Ni-Mn-based alloys applied to Ni-MH battery

The RE-Mg-Ni-Mn-based AB2-type La1-x Cex MgNi3.5 Mn0.5 (x =0-0.4) alloys were prepared by spinning treatment.For obtaining the optimum performance,the effects of Ce content and spinning rate on the hydrogen storage performance of the alloys were studied systematically.The results show that the variations of the spinning rate and Ce content result in noteworthy changes of the phase content without altering phase composition of the alloys.Specifically,the LaMgNi4 phase increases and LaNi55 phase decreases when increasing the spinning rate and Ce content.Furthermore,the crystalline grains of Ce-containing alloys prepared by spinning treatment are remarkably refined.The alloys own superior electrochemical performance.All alloys reach the optimal discharge capacity at the initial cycle.Increasing Ce content and spinning rate lead the discharge capacity and electrochemical kinetics rise to an optimal value and then start to reduce.Meanwhile,the electrochemical cycle stability is also improved,which is ascribed to the great enhancement of anti-pulverization and anti-corrosion abilities resulting from the spinning treatment and the substitution of Ce for La.     

The effect of rare earths on the solidification structure of Fe-36Ni invar alloy

The effect of Ce,La and mischmetal on the solidification structure of Fe-36Ni invar alloy was investigated.The results show that great amounts of high-melting point compounds (Ce2O3,La2O2S and (Ce,La)2O2S) respectively formed in the alloy with the addition of Ce,La or mischmetal.Based on the theory of lattice misfit,the lattice misfit between the (0001) surfaces of Ce2O3,Ce2O2S and La2O2S and (100) surface of Fe-36Ni invar alloy were 6.21%,5.77% and 5.42%,respectively,which are relatively low.Therefore,Ce2O3 ,La2O2S and (Ce,La)2O2S could serve as the core of heterogeneous nucleation,improve the equiaxed grain ratio,reduce the equiaxed grain size and refine the solidification structure of alloy.     

Effects of rare earth addition on microstructure of C–Mn steel

Abstract

The microstructures were observed in C–Mn steel and statistical analysis of the inclusions produced when trace amounts of rare earth were added to the steel. The results show that the content of intragranular acicular ferrite decreased in the order of being treated with La+Ce/La/Ce in C–Mn steel after the treatment of different kinds of rare earths. The optimum mass ratio of La and Ce for La+Ce combined treatment is 3:1.The best incubation time after Le+Ce (3:1) treatment is 5?min. The size of inclusion nuclei favouring intragranular acicular ferrite nucleation concentrates in the range of 1–4?μm. The disregistries between rare earth inclusions and α-Fe are small, which plays an important role in rare earth inclusions inducing intragranular acicular ferrite nucleation.