石墨烯化学镀铜及其对石墨烯/铜基复合材料组织性能的影响

以还原氧化石墨烯（reduced graphene oxide,RGO）和CuSO₄·5H₂O为主要原料,通过化学镀法得到铜包覆RGO复合粉体,再与铜粉混合得到含有不同质量分数RGO（0.2%、0.4%、0.6%、0.8%）的RGO/Cu粉末混合料,经压制及烧结得到RGO/Cu复合材料。通过X射线衍射仪（X-ray diffraction,XRD）、拉曼光谱仪（Raman spectroscopy,RS）和场发射扫描电镜（field emission scanning electron microscope,FESEM）等对RGO/Cu复合材料的微观组织和相关性能进行测试分析,并与由未镀铜处理的RGO所制备的RGO/Cu复合材料的组织性能进行对比。结果表明,经化学镀处理的RGO在RGO/Cu复合材料中分布较均匀,而未镀铜处理的RGO在基体中发生明显的团聚。RGO/Cu复合材料的导电导热性随石墨烯加入量的增加有所下降,但石墨烯的加入可有效提高RGO/Cu复合材料的力学性能,且由镀铜RGO所制备的RGO/Cu复合材料的性能要优于由未处理RGO所制备的RGO/Cu复合材料的性能。此外,RGO加入量对复合材料性能也有明显影响,当添加RGO质量分数为0.4%时,由镀铜RGO所制备的RGO/Cu复合材料的综合性能达到最好,其电导率达95.01% IACS,热导率达415.5W·（m·K）-1,而压缩屈服强度和抗拉强度分别为156.73 MPa和268.62 MPa,较相同工艺条件制备的纯铜的屈服强度（75 MPa）和抗拉强度（234.64 MPa）提升了109%和14.48%。     

粉末冶金法制备石墨烯/2024Al复合材料的组织及性能研究

本文以石墨烯纳米片和2024Al合金粉末为原材料,利用冷等静压+真空烧结+热挤压的方法制备了不同质量分数的石墨烯/2024Al复合材料,通过对复合材料进行SEM表征、能谱分析以及力学性能测试,研究了不同质量分数石墨烯/2024Al复合材料微观组织和宏观性能。结果表明：经过冷等静压+烧结后的石墨烯/2024Al复合材料中石墨烯呈现随机分布,此时致密度较低。通过热挤压后,能够使石墨烯呈定向排列,且显著提高复合材料的致密度。0.5%和1%挤压态石墨烯/2024Al复合材料的抗拉强度可分别达到290.6 MPa和321.1 MPa,相比基体分别提高了48.8%和64.4%,表明石墨烯的引入以及质量分数的增加能显著提高复合材料的抗拉强度。     

石墨烯增强铝基复合导线制备及其表征

通常铝石墨烯复合材料会生成较多的Al₄C₃,使其电导率相对于纯铝下降较大。为减少Al₄C₃生成,采用粉体连续挤压法制备Al-Gr(石墨烯)复合材料。研究表明：采用粉体连续挤压法制备Al-Gr复合材料,Al与Gr在界面上生成的Al₄C₃相极少,抗拉强度提高,随着石墨烯含量的增加而增大,电导率随石墨烯含量增加而降低,但Al-0.5%Gr复合杆材电导率仍保持为62.28%IACS,相比基体纯铝仅下降2.1%,而抗拉强度提高了16.3%。     

半固态烧结制备石墨烯/7075铝基复合材料与性能研究

通过球磨混粉+半固态烧结法成功制备出质量分数为0.5%的石墨烯/7075铝基复合材料,通过扫描电子显微镜、能谱分析仪和室温拉伸力学性能测试等手段,对石墨烯/7075铝基复合材料的显微组织及力学性能进行了研究。结果表明:复合材料中的石墨烯纳米片均匀的分散在7075铝合金基体中,相比于未添加石墨烯的7075铝合金基体,复合材料的密度有所下降,维式硬度和抗拉强度则分别提高了14%和32%,延伸率无明显变化。     

石墨烯增强TC4复合材料的微观组织及力学性能

采用球磨法将石墨烯与TC4预合金粉末混合,通过放电等离子烧结工艺在1 200℃制备了石墨烯/TC4复合材料。采用扫描电子显微镜、X射线衍射仪等研究了复合粉末混合前后的形貌和物相结构;采用显微硬度计、Gleeble-3800D热模拟试验机等分析了复合材料的显微硬度和压缩性能。结果表明:通过干法球磨和放电等离子烧结工艺制备的复合材料组织致密,石墨烯与TC4原位生成的TiC在晶界处析出,提高了复合材料的力学性能。复合材料的室温压缩强度和屈服强度,相对于基体分别提高了17.03%和12.5%;硬度和延伸率分别提高了18.2%和60%。石墨烯的加入使得TC4基体晶粒细化,同时与基体反应生成了TiC颗粒,对基体产生了强化效果。     

定向分布石墨烯纳米片/Al8030复合材料的低温蠕变性能研究

采用粉末改性和半固态挤压工艺制备了石墨烯纳米片/Al8030复合材料, 其中石墨烯纳米片质量分数为0.5%, 研究了石墨烯纳米片对铝基复合材料显微组织和低温蠕变性能的影响。结果表明: 石墨烯纳米片主要分布于晶界处, 并且具有与挤压方向平行的定向分布特征。复合材料样品在服役条件下的稳态蠕变速率与铝合金基体相比下降超过50%。在90 ℃和50~90MPa实验条件下, 基体的蠕变机制以位错攀移机制为主, 而复合材料的蠕变则由位错滑移和位错攀移机制共同影响; 在120~150 ℃和50~90MPa实验条件下, 基体和复合材料的蠕变均由位错攀移机制和第二相增强机制协同控制, 但石墨烯纳米片的添加使得第二相增强机制对蠕变的控制更明显。     

石墨烯含量对铝基复合材料微观组织和力学性能的影响

通过机械混合、低温球磨结合热挤压工艺制备了石墨烯增强铝基复合材料。通过透射电子显微镜(TEM)、能谱分析(EDS)和室温拉伸力学性能测试等手段,对石墨烯纳米片添加量对铝基复合材料微观组织和力学性能的影响进行了研究。研究结果表明,当石墨烯添加量为0.5%(质量分数),石墨烯基体沿着纳米晶铝的晶界均匀分布,石墨烯/铝界面结合良好。当石墨烯含量大于1.0%时,石墨烯在铝基体中分散性变差,容易团聚形成夹杂,使得石墨烯/铝界面结合变差。铝基复合材料的强度随着石墨烯添加量的增大先升高后降低。当石墨烯添加量为1.0%时,复合材料的强度达到最大值(抗拉248 MPa),与未添加石墨烯的纯铝相比,抗拉强度提高了68.7%。石墨烯增强铝基复合材料的塑性随着石墨烯添加量的增大,先保持不变而后急剧下降。当石墨烯添加量为0.5%,复合材料塑性与纯铝塑性相当。当石墨烯添加量为1.0%,延伸率为8.3%,此时材料的强韧性匹配度较好。     

Ni元素对Al-Cu-Mn合金组织及力学性能的影响

为研究添加Ni元素对Al-5.0Cu-0.6Mn合金组织及力学性能的影响,通过硬度试验、拉伸力学试验及摩擦磨损试验对合金力学性能进行研究;采用扫描电子显微镜、激光共聚焦显微镜及透射电子显微镜对合金微观组织进行检测分析。结果表明：向Al-5.0Cu-0.6Mn合金中添加Ni元素后,由于Al₃CuNi相析出的强化作用,并且与基体结合良好的增强相颗粒能均匀分布于合金中,使得合金硬度和强度大幅提高,摩擦磨损深度显著降低,综合力学性能得到有效的提升。当Ni元素的添加量为0.3%(质量分数)时,由于T相(Al₂₀Cu₂Mn₃)和Al₃CuNi相分布比较均匀,合金综合性能较为理想,其HV硬度、抗拉强度、摩擦磨损系数分别为126.4 MPa、395.2 MPa、0.12。     

镀铜石墨烯铝基复合材料的制备及性能研究

通过改进的Hummers法制备氧化石墨烯,对氧化石墨烯进行化学镀铜处理。复合材料以纯铝为基体,镀铜氧化石墨烯为增强相。通过放电等离子烧结工艺制备不同质量分数的镀铜石墨烯铝基复合材料。通过扫描电子显微镜(scanning electron microscope, SEM),X射线衍射仪(X-ray diffractometer, XRD)等表征材料的微观组织结构,利用微拉伸试验机测试材料的力学性能。结果表明,镀铜石墨烯质量分数达到0.15%时,镀铜石墨烯铝基复合材料综合性能达到最优,维氏硬度和抗拉强度分别达到56和224 MPa,比石墨烯铝基复合材料的维氏硬度和抗拉强度分别提高6%和24%,比纯铝的维氏硬度和抗拉强度分别提高30%和103%。镀铜石墨烯铝基复合材料具有较好的减磨性。     

铜与氧化石墨烯协同增强钛基复合材料显微组织及性能研究

通过放电等离子烧结(SPS)技术制备铜(Cu)和氧化石墨烯(GO)协同增强的钛基复合材料(GO/Cu/TA1),研究了氧化石墨烯和Cu元素对钛基复合材料组织、硬度及拉伸性能的影响。结果表明：GO/Cu/TA1复合材料晶内析出金属间化合物Ti₂Cu相,晶界处存在非连续分布的TiC颗粒。复合材料的抗拉强度和屈服强度较TA1纯钛分别提高了66%和82%,显微硬度提升了58.4%,且延伸率保持在15%左右。硬度及强度的提升归因于晶界处分布的TiC颗粒与晶内析出的金属间化合物Ti₂Cu相的协同强化作用。     

转炉炉壳热应力分析

根据实际转炉建立实体模型。以有限元为手段,考虑了炉衬和炉壳材料的物性参数随温度变化的特点和炉衬与炉壳之间膨胀间隙,计算了转炉炉壳在温度载荷和炉衬膨胀压力同时作用下的热应力。所得结果可为转炉炉壳设计提供依据。     

焦炭热性能指标意义浅析

通过对焦炭在高炉内的历程及其变化规律的剖析,阐述焦炭热性能指标的意义,形象地把焦炭在高炉内的损耗分为三部分(M1,M2,M3)。指出M2对焦比及焦炭价格有一定的指导作用。     

Results of treatment of cancer of the cardia

Cancer of the cardia is traditionally discussed with cardiac cancer of the lower portion of the esophagus and upper gastric cancer invading the esophagus, and the specific characteristics of cancer of the cardia have never been clearly defined. We reviewed the outcome of 172 patients with adenocarcinoma of the cardia who had undergone radical surgery between 1949 and 1994 in the Division of Gastrointestinal Surgery of the Cancer Institute Hospital. The centers of the tumors were located within 2 cm above and below the boundary between the esophagus and the stomach, and their longitudinal diameter was less than 8 cm. We divided the patients into an early period (1949-1979; n = 79) and a late period (1980-1994; n = 93), and focused on the historical transition. There were no differences in patient gender or histology between the two periods. However, the late period was associated with fewer cases of esophageal invasion and shorter longitudinal diameter, as the age of the population advanced. The number of advanced cancers such as the localized and infiltrative type had decreased, and early cancer and early clinical stage had become more common, but despite the fact that the number of early cancers had increased, extended dissection, such as thoracic and paraaortic lymph node dissection, was performed more frequently. By clinical stage, the long-term outcome markedly improved in Stage I patient in the late period, and tended to improve in Stage II and III patients. This appears to have been attributable to the prevention of micrometastasis by extended dissection, although the number of early cancers is another major potential cause. There were no differences in the outcome of Stage IV patients between the two periods, and further advances in multimodality therapy must be awaited. The range of resection is basically proximal gastrectomy, and if there are adequate indications, the prognosis is favorable. In view of the status of lymphatic flow and lymph node metastasis, and long-term results, lateroaortic lymph node dissection is important. Since the number of early cancer patients has been increasing, if intraabdominal recurrence is prevented, intrathoracic lymph node dissection will contribute greatly to the outcome of such patients.     

Effect of antibiotics of chemotaxis of human leukocytes

The effect of 20 different antibiotics on chemotaxis by human neutrophils was studied. Human leukocytes incubated with chloramphenicol, rifampin, sodium fusidate, and tetracyclines in vitro showed markedly depressed migration. The mechanisms by which these antibiotics affect leukotaxis are discussed.     

Quality of life of relatives of mental patients

Usage of quality of life of psychiatric patients' relatives as the parameter of estimation of the quality of psychiatric care is considered. By means of standard questionnaire elaborated by the authors as well as by means of both individual and group conversations the quality of life was analyzed in 40 relatives which lived together with psychiatric patients. Different spheres of their life and difficulties (financial, social-psychologic, production) were examined in families with such patients. The defects of psychiatric care that had direct influence on the quality of life of the psychiatric patients' relatives are outlined.     

The effect of amount of possession of the trait of hostility on accuracy of perception of hostility in others.

Some theories of personality hold that an individual's perception of others is influenced by his own personality characteristics; more specifically, that a trait of low social value will be projected more into others, and that insight into the possession of these characteristics reduces this distortion. These 2 hypotheses were tested by having a group of college students rate each other (including themselves) on degree of friendliness or hostility. Agreement with group rating about self yielded the insight score. In general, the hypotheses were supported; the "friendly" Ss were most accurate in their perception of others, and insight was positively associated with accurate perception. From Psyc Abstracts 36:04:4HL16M. (PsycINFO Database Record (c) 2010 APA, all rights reserved)