燃料电池用新型封接玻璃的高温热稳定性分析

采用差热扫描示量法(DSC)对平板式固体氧化物燃料电池(p-SOFC)封接材料SrO2-Al2O3-SiO2-La2O3-B2O3玻璃进行析晶动力学分析。运用动力学模型计算出玻璃的析晶活化能为271kJ/mol,析晶过程主要受扩散控制。利用热膨胀数据和VFT粘度方程计算得到玻璃在800～950℃区间对应的粘度曲线。结果表明,该玻璃满足封接的高温流动性要求。在p-SOFC封接和工作温度下对玻璃进行不同时间的热处理,该玻璃转变为微晶玻璃,主晶相为Sr2SiO4和Sr2AlSiO7。通过XRD图谱拟合计算得出,在工作温度下保温时间达到20h以上,玻璃析晶趋势趋于平缓,结晶度在55%以上。     

Li2O-Al2O3-SiO2系统低膨胀微晶玻璃性能研究

Li2O-Al2O3-SiO2系统微晶玻璃是一种具有耐高温、耐热冲击、热膨胀系数低等性能的新型玻璃材料,受到科研人员的广泛关注.通过改变Li2O-Al2O3-SiO2系统微晶玻璃的基础配方以及热处理制度,制备了具有较低热膨胀系数的Li2O-Al2O3-SiO2系统微晶玻璃.结合运用差热热重、X射线衍射、扫描电镜等测试分析方法,研究性能与其组分、微观结构和热处理制度之间的相互联系.结果表明:通过对热处理制度的调整,促进了玻璃的析晶过程,核化温度和晶化温度有所降低.玻璃析出的主晶相为LiXAlXSi1-XO2,最低热膨胀系数达到25.365×10-7℃-1.     

SrO-Al2O3-SiO2系统微晶玻璃的晶化行为及性能

通过改变玻璃成分,在不同的热处理制度下制备SrO-Al2O3-SiO2系统微晶玻璃,用DTA、XRD、SEM等手段对该系统微晶玻璃材料的析晶过程进行了研究。在此基础上,讨论了晶化行为对微晶玻璃的热学及力学性能的影响。结果表明:材料的热学性能及力学性能与玻璃成分及热处理制度密切相关。可以找到某一确定组分的基础玻璃,经过较低的核化温度与较高晶化温度热处理后,能够得到力学性能优良、热学性能较好的微晶玻璃材料。     

Preparation,crystallization,and wetting of ZnO-Al_2O_3-B_2O_3-SiO_2 glass-ceramics for sealing to Kovar

A novel type of ZnO-Al2O3-B2O3-SiO2 glass-ceramics sealing to Kovar in electronic packaging was developed,whose thermal expansion coefficient and electrical resistance are 5.2×10-6/oC and over 1×1013 Ω·cm,respectively.The major crystalline phases in the glass-ceramic seals were ZnAl2O4,ZnB2O4,and NaSiAl2O4.The dielectric resistance of the glass-ceramic could be remarkably enhanced through the control of alkali metal ions into crystal lattices.It was found that crystallization happened first on the surface o...     

A study of the crystallization kinetics of Ge-Te amorphous systems

The glass-forming ability of binary GexTe100-x (x=15, 20, 30) alloys was investigated. The crystallization mechanism of these amorphous bulks was studied by X-ray diffraction (XRD), scanning electron microscopy (SEM) and differential scanning calo- rimetry (DSC). The temperature of glass transition, the temperature of crystallization, the activation energy for glass transition and crystallization, and the order of the crystallization mechanism were calculated from the different heating-rates.     

用电解锰渣制备高铁硫铝酸盐水泥熟料

以湘潭电化集团“两矿法”生产电解二氧化锰排放的电解锰渣（EMR）为原料,采用X射线荧光光谱分析（XRF）、扫描电子显微镜一能谱仪（SEM—EDS）、X射线衍射（XRD）、热重分析（TG）等检测手段对其化学组成、形貌特征、物相结构及物化性质进行了分析．结果表明,电解锰渣是一种富含Si、S、Fe、Ca、Al的材料,可以用作烧制高铁硫铝酸盐水泥（FAC）熟料的原材料．分别考察了煅烧温度、保温时间、电解锰渣掺量对高铁硫铝酸盐水泥抗压强度的影响,当煅烧温度1200℃、保温时间60min、电解锰渣掺量25％左右时为煅烧工艺的最优条件,3d抗压强度最高可达49．8MPa．研究结果可为电解锰渣的资源化利用提供新的途径和方向．     

用差热分析法研究BAS凝胶玻璃的非等温结晶过程

由非等温ＤＡＴ实验和Ｂａｎｓａｌ等提出的动力学参数计算方法，首次直接采用修正的ＪＭＡ方程导出ＢＡＳ凝胶玻璃结晶动力学方程，计算的结晶体积分数和ＤＴＡ曲线上峰区面积比值确定的实验值很接近。     

Li~+掺杂对熔融法制备氟金云母析晶的影响

利用传统的熔融析晶工艺制备了Li+掺杂氟金云母,通过DTA和XRD研究了Li+部分取代K+对氟金云母析晶的影响。根据不同升温速率下的DTA析晶峰温度值计算出了玻璃的析晶活化能,结果表明,少量Li+的加入并不会改变主晶相,但会促进云母析晶;Li+摩尔分数在0~6.67%范围内会降低云母的析晶活化能,在6.67%的时候析晶活化能最低,超过6.67%,析晶活化能会升高。     

综合利用包钢高炉布袋除尘灰制备微晶玻璃的试验研究

以包钢高炉布袋除尘灰、二氧化硅、氧化钙、氧化铝为主要原料,采用熔融法制备CaO-Al2O3-SiO2系微晶玻璃.利用DSC,SEM等方法对该玻璃体系进行测试,探讨了微晶玻璃中布袋除尘灰含量对晶化行为的影响.试验结果表明,布袋除尘灰含量的利用率可达到50%.本研究为包钢高炉布袋除尘灰综合利用提供了途径,并有效地解决了环境污染和占地问题.     

A study of the crystallization kinetics of Ge-Te amorphous systems

The glass-forming ability of binary Ge_xTe_100-x (x=15, 20, 30) alloys was investigated. The crystallization mechanism of these amorphous bulks was studied by X-ray diffraction (XRD), scanning electron microscopy (SEM) and differential scanning calo-rimetry (DSC). The temperature of glass transition, the temperature of crystallization, the activation energy for glass transition and crystallization, and the order of the crystallization mechanism were calculated from the different heating-rates.     

Crystallization kinetics of lithium aluminum germanium phosphate glass by DSC technique

The crystallization kinetics of Li2O-Al2O3-GeO2-P2O5 (LAGP) glass fabricated via the conventional melt-quenching method was studied by differential scanning calorimetry (DSC) under non-isothermal condition at different heating rates. The activation energy of glass transition Eg is 634.4 kJ/mol, indicating that LAGP glass is easy to crystallize at an elevated temperature. The activation energy of crystallization Ec and Avrami index n obtained from Matusita’s model are 442.01 kJ/mol and 1.7, respectively. The value of n reveals that bulk crystallization predominates slightly over surface crystallization during crystallization process. LAGP glass-ceramics after different heat treatments have the same crystalline phases determined as major phase LiGe2(PO4)3, with AlPO4 and GeO2 as their impurity phases.     

金属玻璃P1峰弛豫激活能的一种计算新方法

提出了金属玻璃P1峰弛豫激活能的一种计算方法 .计算金属玻璃P1峰激活能的常用方法是由不同频率下升温测得的不同内耗峰的温频关系来求得 .然而 ,自由衰减法有限的变频范围 ,以及由于受晶化的影响 ,使两次升温测量时样品的初始状态不易重复 ;用强迫振动法测量时 ,同步变频条件限制了升温速率 ,造成金属玻璃的晶化过程严重影响了测量结果 .该方法仅用自由衰减法一次升温测得的内耗峰及损耗模量峰的温频关系 ,便可以计算出金属玻璃P1峰的弛激活能     

含氟羟磷灰石的生物微晶玻璃的制备

由熔融浇铸压制成形法与晶化、水热合成过程相结合,研制出用于牙面修复的CaO-SiO_2-P_2O_5系统新型生物微晶玻璃。经DTA、XRD和TR分析鉴定主晶相为氟羟磷灰石固溶体[Ca_(10)(PO_4)_6F_(2-x)(OH)_x],其组成和结构与天然牙的羟基磷灰石[Ca_(10)(PO_4)_6(OH)_2]相近。并具有比天然牙更优的力学性质,如抗弯强度(142MPa)、断裂韧性(4.75MPam~(1/2)),硬度(VHN 5.33GPa)等。本文主要研究相变现象、核化、晶化和水热合成过程以及对生物微晶玻璃结构性质的影响。     

Effect of the Cool System on Internal Stress of CaO-Al203-SiO2 Glass-ceramic System

The samples were attained through altering the cooling system of producing glass-ceramics. The X-ray diffraction was used to test the stress value of different samples. The relation of the cooling system and internal stress were also investigated. The experimental results show that the stress of glass-ceramic had a close relation with starting cool temperature. Above 800 ~C, glass-ceramic could be accelerated cooling and did not bring stress. Temperature between 500 ℃ and 800℃ was an important temperature range of the formation of stress in glass-ceramic, in which the glass-ceramic stress would change obviously. Cool system was the key on how to control and eliminate internal stress in order to reduce the destroy of materials crated by internal stress. In addition, glass particles size increase, glass-ceramic stress increase in consequent.     

Influence of ZrO2 on sintering and crystallization of CaO-Al2O3-SiO2 glass-ceramics

ZrO2 was added into CaO-Al2O3-SiO2 glass-ceramics and the effect of ZrO2 on sintering and crystallization of CaO-Al2O3-SiO2 glass ceramics was investigated. The results show that the sintering shrinkage ratio of glass particles decreases with the increase of the content of ZrO2. ZrO2 has an unfavourable effect on sintering shrinkage ratio of glass particles. The sintering shrinkage ratio of glass particles increases with the increase of sintering temperature. The increase of sintering temperature favors the decrease of the liquid phase viscosity of glass particles. ZrO2 has little effect on crystallization of main crystalline phase （β-wollastonite）. However, it promotes the crystallization at relatively low temperature.     

Non-isothermal crystallization kinetics of kaolin modified polyester

Fiber-class modified kaolin and PET have been blended in the twin-screw and granulated to chips containing 4 wt% of kaolin.Non-isothermal crystallization process of kaolin modified polyester was investigated using a differential scanning calorimetry (DSC),and the addition of kaolin enhances either the melting temperature (Tm) or the crystallization temperature (Tc).The morphology of kaolin modified polyester,the melt of which is cooled at different cooling rate,was observed by scanning electron microscope (SEM).The relationship between Tc and cooling rate F was studied.Semi-crystalline phase t1/2 makes an exponential decline with increasing F,and the higher the cooling rate,the shorter the time of crystallization completion.Non-isothermal crystallization kinetics parameters and the activation energy were calculated,indicating that the higher rate of cooling needs the higher relative crystallinity in the unit crystallization time,the crystallization rate increased while speeding up the temperature reduction,and the activation energy ΔE was calculated to be-204.1566 kJ/mol for the non-isothermal crystallization processes by the Kissinger’s methods.     

Crystallization of Pd40Cu30Ni10P20 bulk metallic glass with and without pressure

The glass-transition behavior of Pd40Cu30Ni10P20 bulk metallic glass was investigated by differential scanning calorimetry （DSC） and X-ray powder diffraction （XRD）. The effect of pressure on the crystallization behavior of Pd40Cu30Ni10P20 bulk glass was studied by in situ high-pressure and high-temperature X-ray powder diffraction using synchrotron radiation. Phase analyses show at least six crystalline phases in the crystallized sample, namely, monoclinic, tetragonal CuaPd-like, rhombohedral, fcc-Ni2Pd2P, fcc-（Ni, Pd） solid solution, and body-centered tetragonal （bct） NiaP-like phases. The onset crystallization temperature increases with pressure having a slope of 1 1 K/GPa in the range of 0 to 4 GPa. The results are attributed to the competing process between the thermodynamic potential barrier and the diffusion activation energy under pressure.     

Ti6Al4V的激光选区熔化单道成形数值模拟与实验验证

对于Ti6Al4V材料的激光选区熔化（SLM）成形工艺,基于离散元方法（DEM）建立粉末颗粒随机分布的三维介观模型.采用流体体积法（VOF）对SLM成形过程的三维自由表面进行动态追踪;考虑TC4颗粒随机分布的粉床、随温度呈非线性变化的热物性参数、熔池自由液面演化、由温度梯度引起的表面张力以及蒸发作用;通过数值模拟研究激光与粉末颗粒相互作用过程中的传热、熔化、流动、凝固等过程. 结果表明,由温度梯度及表面张力梯度产生的马兰戈尼对流是影响熔池内部传热传质和熔池三维形貌的主要因素;线能量密度（LED）与马兰戈尼对流的强度呈正相关,当LED=92.9~183.0 J/m时,单道表面质量较优. 通过单道成形实验对熔池与熔道的三维尺寸与形貌进行观察分析,有效验证了数值模拟的正确性.     

Growth behavior of electroless copper on silicon substrate

The growth behavior containing deposit morphology, growth rate, activation energy, and growth mechanism of copper on silicon substrate, especially at the initial stage, in the electroless plating process was studied. Copper was deposited on the surface of the silicon substrate in an electloless plating bath containing formalin （CH2O 37vol%） as a reducing agent at a pH value of 12.5 and a temperature of 50-75℃. The copper deposit was characterized using a field emission scanning electron microscope and transmission electron microscope. The results showed that after the activation process, nanoscale Pd particles were distributed evenly on the surface of the silicon; in the deposition process, copper first nucleated at locations not only near the Pd particles but also between the Pd particles; the growth rate of electroless Cu ranged from 0.517 nm/s at 50℃ to 1.929 nm/s at 75℃. The activation energy of electroless Cu on Si was 52.97 kJ/mol.     

Zr_(65)Al_(7.5)Ni_(10)Cu_(15)Co_(2.5)合金的比热和热力学函数

采用差示扫描量热仪和差热分析仪测定了Ｚｒ６５Ａｌ７．５Ｎｉ１０Ｃｕ１５Ｃｏ２．５非晶合金的结晶温度和结晶焓、晶态的熔化温度和熔化焓、非晶态和晶态及液态的比热等热力学数据。在此基础上通过设晶态２９８Ｋ的自由焓为零，得到了晶态、非晶态和液态的热力学函数，据此研究了玻璃转变和真实玻璃转变温度，分析了理想玻璃转变温度、真实玻璃转变温度和实际测量的玻璃转变温度的关系。