冷压烧结法制备碳纤维增强铜基复合材料的研究

以碳纤维和Cu粉为原材料,采用冷压烧结法制备了碳纤维增强铜基复合材料,研究了压制压力、烧结温度和烧结时间对复合材料性能的影响.结果表明：随着压力的增加,冷成形压坯的密度和压溃强度均先快速提高,而后缓慢增长,较合理的压制压力为238～286 MPa;碳纤维增强铜基复合材料的密度和强度都随着烧结温度的增大而快速提高,但在800℃以上,密度基本不变,强度开始下降;提高烧结温度可提高复合材料的抗摩擦性能,当烧结温度超过750℃时,摩擦性能基本保持不变;碳纤维增强铜基复合材料的密度、强度和抗摩擦性能都随着烧结时间的延长而提高,但是提高速度越来越慢,当烧结时间超过40 min后,这些性能基本不再随时间变化.

急冷烧结法制备六钛酸钾晶须的工艺研究

以分析纯K2CO3和工业纯TiO2为原料,采用急冷烧结法制备了六钛酸钾晶须,利用扫描电镜、X射线衍射仪等手段,研究了二次保温时间和钛源化合物类型等对其形貌及物相的影响。结果表明:以金红石型二氧化钛为钛源,TiO2/K2CO3的摩尔比为5.5∶l时,1200℃保温3 h,然后在高于1114℃二次保温2 h,再经急冷后进行解离、抽滤和烘干,即可得到分散性好、物相纯度较高的六钛酸钾晶须。

冷压烧结法制备Cu-15%Cr_2AlC复合材料工艺研究

以自制的高纯Cr2Al C陶瓷粉体和工业纯铜为原料,采用冷压真空烧结技术制备了Cu-15%Cr2Al C(体积分数)复合材料。通过正交优化试验探讨了压制压力、烧结时间及烧结温度对复合材料相对密度、显微硬度的影响,并对复合材料组织进行扫面电镜分析。结果表明:压制压力对复合材料性能的影响大于烧结时间和烧结温度;随着压制压力的增加,复合材料的相对密度和显微硬度逐渐升高;Cr2Al C颗粒弥散分布于Cu基体中;压制压力为500发MPa,烧结时间为1 h,烧结温度为1 000℃,密度为6.91 g/cm3,相对密度达到97.26%,显微硬度为158.93 HV,压溃强度为280 MPa。

AZO陶瓷靶材粉体冷压-烧结致密化研究

采用冷压-烧结法制备氧化锌铝陶瓷靶材(ZnO:Al,简称AZO靶材)。用正交实验法设计实验,探讨氧化铝质量分数、压制靶材的压力、烧结温度和烧结时间对靶材致密度的影响,确定最佳制备工艺参数。研究结果表明最佳制备工艺参数是:氧化铝质量分数为4%,压制靶材的压力为11 MPa,烧结温度为1300℃,烧结时间为2 h。在此条件下,靶材的相对密度可达98%以上,即可实现AZO靶材的超高致密度化。

石墨/铜复合材料的载流摩擦磨损性能

分别采用粒径为150μm的镀铜石墨粉和不镀铜石墨粉,通过冷压烧结法制备了不同成分的石墨/铜复合材料,用销-盘式载流摩擦磨损试验机研究了石墨/铜复合材料的载流摩擦磨损性能,利用扫描电镜对磨损表面进行了分析。结果表明:在试验参数范围内,采用镀铜石墨粉能够有效降低复合材料的摩擦因数,但对耐磨性能影响趋势不明显;随石墨含量的增加,复合材料摩擦因数减小;石墨质量分数为10%时,复合材料的磨损率最低。

纤维状态对碳纤维-铜基复合材料性能的影响

以电解铜粉和碳纤维等为原料,采用冷压烧结法制备碳纤维-铜基复合材料并研究了纤维质量分数、纤维长度以及纤维电镀等对其性能的影响。结果表明,1）碳纤维-铜基复合材料的相对密度和导电性能都随着纤维质量分数的增加不断下降,强度和耐磨性却随着纤维质量分数的增加先上升后下降,当碳纤维质量分数在3.0%~4.5%之间时,复合材料具有较好的综合性能。2）随着纤维长度的增加,碳纤维-铜基复合材料的相对密度、导电性和耐磨性等会由于孔隙率的升高和界面结构变差而下降,强度却随着纤维长度的增加而先上升后下降。3）与预镀镍相比,采用碳纤维预镀铜的方法制备的碳纤维-铜基复合材料,导电性能提高,机械性能下降。

电石渣骨架定型相变材料储热性能研究

电石渣是生产乙炔过程中伴生的工业固体废弃物,大量堆积污染环境。在碳中和背景下,为资源化利用固体废弃物,以电石渣为骨架材料,NaNO_(3)为相变材料,采用冷压缩-热烧结法制备电石渣基复合相变储热材料。采用X射线衍射法(XRD)、热重‑差示扫描量热法(TG‑DSC)和激光导热分析法(LFA)对该材料进行了表征和分析。结果表明,该复合材料具备良好的化学相容性,NaNO_(3)和电石渣质量比为5∶5时,各种热物理性能最好,为最佳比例。该比例下复合材料的导热系数最大为0.18 W/(m∙K),50~500℃内的储热密度为457.2 J/g,具备良好的储热性能。

超高致密度氧化锌铝陶瓷靶的研究

采用冷压-烧结法制备掺铝氧化锌(AZO)陶瓷靶材。用正交试验法设计实验,探究WAl O2 3(%)、压机压力(MPa)、烧结温度(℃)和烧结时间(h)四个因素对相对密度的影响,确定最佳的WAl O2 3(%)、压力(MPa)、烧结温度(℃)以及烧结时间(h)。研究结果发现,四个因素对相对密度的影响程度大小依次为:烧结温度>>压力>WAl 2 O3>烧结时间;最佳的工艺组合为WAl O2 34%、压力10Mpa、烧结温度1300℃和烧结时间2h。在此条件下,靶材的相对密度最大,可达到97%左右。

Er,Yb∶(LaLu)_2O_3透明陶瓷制备及上转换发光性能

采用柠檬酸燃烧法制备Er,Yb∶(La Lu)_2O_3陶瓷粉体,用X射线衍射对其进行了物相鉴定,研究表明1 000℃时已经得到纯相的(La Lu)_2O_3。采用冷等静压-真空烧结法制备了Er,Yb∶(La Lu)_2O_3和Er∶(La Lu)_2O_3陶瓷,对陶瓷的结构和光谱性能进行了详细的研究,研究发现掺杂5%Yb^(3+)和10%La^(3+)样品的上转换发光强度与未掺Yb^(3+)、La^(3+)样品相比明显增大,根据上转换光谱显示较强发射峰位于564 nm和661 nm处,对应Er^(3+)的~4S_(3/2)(~2H_(11/2))→~4I_(15/2)能级跃迁和~4F_(9/2)→~4I_(15/2)能级跃迁,并讨论了Er^(3+)-Yb^(3+)的能量传递过程及其上转换发光机制。

薄膜锂离子电池用LiCoO_2靶材的制备

分别采用热压和冷压烧结法制备出LiCoO2靶材,其中热压法使用了不同材质的模具,冷压烧结法以环氧树脂为粘结剂,确定了粘接剂的最佳添加量为1.0%。对制得的靶材进行了XRD、热重及SEM分析,并用排水法测量了靶材的密度。实验结果表明:热压法烧结时,使用SiC模具制备的靶材密度为5.21 g/cm3;添加1%粘结剂后,使用冷压烧结方法制备的靶材密度为4.89 g/cm3。热压法制备的靶材致密度高于冷压法制备的靶材,烧结程度更深。

Design and Realization of Metadata Standard for Informationized Construction of the Auxiliary Shaft in Longgu Mine

Based on the analysis of status quo of metadata technology and the informationized freezing construction of an auxiliary shaft in Longgu mine, the necessity and feasibility of applying metadata standards for informationized construction is discussed. The prototype of metadata standard for the construction is designed and established by using a modeling method, and the framework with XML/RDF for such standard is given.

激光-电弧组合焊接厚壁金刚石钻头的研制

阐述了激光-电弧组合焊接厚壁金刚石钻头的研制过程,重点介绍了钻头齿的冷压、热压模具结构,激光焊接夹具和电弧焊接夹具的结构,同时也介绍了关键工序的参数与测试结果,介绍了产品的使用效果。

Morphological and ultrastructural changes in rat ovarian tissues after cryopreservation

Objective: The aim of the study was to observe and compare the effects of cryopreservation and thawing meth- ods on rat ovarian tissues. Methods: Twenty 5-6 weeks old SPF-SD female rats were randomly divided into two groups, with ten rats in each group. Freshly isolated ovaries saved as a control (group 1: fresh ovaries) in formalin-fixed or vitrified immediately after dissection (group 2: vitrified ovaries). Ovaries in vitrified group were processed into thin slices then cryo- preserved, stored in liquid nitrogen for 21 days, rapidly thawed and grossly examined. All of the collected ovaries underwent hematoxylin and eosin-stained paraffin serial sections and observed the microscopic evaluation in vitrified ovaries. Results: Grossly the vitrified ovaries turned pale color and the size was same as before freeze. The vitrified ovarian tissue had normal anatomical structures of cortex and medulla under the microscope and had no difference with the fresh control ovarian tis- sue. The number and distribution of the follicles were similar with the fresh ovarian tissue, but had smaller size and the gap between oocyte and the surrounding granulosa cells was increased. Few ooctyes were in irregular appearance however the morphology of follicular cells did not give a different appearance as compared to the fresh control ovarian tissue. Conclusion: Cryopreservation of ovarian tissues by vitrification method has some detrimental effect on the morphology of follicles but does not induce negative impact on the number, density and survival of the primordial ovarian follicles. However the whole follicle anatomical structures also had no significant changes.

铥镱双掺氧化钆钇透明陶瓷的制备与发光性能

采用柠檬酸燃烧法制备了(GdY)_2O_3:Tm,Yb粉体,并确定其制备工艺条件为:煅烧温度1 000℃,Gd^(3+)、Tm^(3+)、Yb^(3+)掺杂的摩尔分数分别为20%、4%、5%。以此条件得到的粉体的平均粒径约65 nm。粉体的发射光谱表明:在980 nm激发源激发下,在484 nm处得到的蓝光,对应于Tm^(3+)的1G4→3H6能级跃迁;在658 nm处得到的红光,对应于Tm^(3+)的3F2→3H6能级跃迁。用制备的粉体作为原料,采用真空烧结法制备(GdY)_2O_3:Tm,Yb陶瓷,其烧结工艺条件为:烧结温度为1 750℃,保温20 h。制备的陶瓷在400~3 300 nm波长范围内的平均透过率为71%。

Cu-TiN复合材料的制备方法及性能

利用粉末冶金工艺制备了Cu-TiN复合材料,对复合材料的显微组织和力学性能进行了分析,探讨了不同制备方法对复合材料性能的影响。结果表明,与纯Cu相比,加入TiN后,复合材料电导率明显下降。随着TiN含量的增加,材料的密度、抗拉强度、硬度和电导率降低。真空热压烧结法制备的复合材料的密度、硬度和电导率明显优于冷等静压烧结法制备的复合材料。

Temperature Measurement of Supercooled Droplet in Icing Phenomenon by means of Dual-luminescent Imaging

The collision of a supercooled water droplet with a surface result an object creates ice accretion on the surface. The icing problem in any cold environments leads to severe damages on aircrafts, and a lot of studies on prevention and prediction techniques for icing have been conducted so far. Therefore, it is very important to know the detail of freezing mechanism of supercooled water droplets to improve the anti-and de-icing devices and icing simulation codes. The icing mechanism of a single supercooled water droplet impacting on an object surface would give us great insights for the purpose. In the present study, we develop a dual-luminescent imaging technique to measure the time-resolved temperature of a supercooled water droplet impacting on the surface under different temperature conditions. We apply this technique to measure the exact temperature of a water droplet, and to discuss the detail of the freezing process.