Recent Advances in Interface Modification of Cu/graphite Composites and Layered Ternary Carbides of Modified Layer Candidate

We review the fundamental properties and significant issues related to Cu/graphite composites.In particular,recent research on the interfacial modification of Cu/graphite composites is addressed,including the metal-modified layer,carbide-modified layer,and combined modified layer.Additionally,we propose the use of ternary layered carbide as an interface modification layer for Cu/graphite composites.

GLDA及其组合试剂对土壤中As、Cd、Cu和Pb的提取能力和机制

以重金属复合污染土壤为研究对象,将谷氨酸二乙酸四钠(GLDA)和其他生物可降解络合剂进行组合,研究了单一和组合试剂对土壤中不同重金属的提取效率和影响机制。结果表明:随着试剂与土壤重金属摩尔比的增加,重金属的提取率逐渐增加,最优摩尔比为5∶1;草酸(OA)对As、柠檬酸(CA)对Cu的提取能力高于乙二胺四乙酸二钠(EDTA)对As和Cu的提取能力;GLDA在偏酸的条件下对各种重金属的提取能力均较高;通过不同试剂的组合,GLDA和OA在摩尔比为1∶1时对土壤中As、Cu和Pb的提取能力最强,分别为52.4%、75.0%和89.8%,各重金属元素提取能力顺序为Pb>Cu≈Cd>As。而GLDA和CA在摩尔比为5∶1时对土壤中Cd的提取能力最强,为95.7%。提取前后的土壤重金属形态分级表明,GLDA+OA(1∶1)组合试剂降低了绝大多数形态的重金属含量,减少了易迁移和易被生物吸收的弱结合态重金属含量。

糖蜜与加密种植对水稻吸附Cd、Cu及对土壤微生物的影响

为研究糖蜜协同加密种植对水稻吸附重金属Cd、Cu的影响,以总Cd含量为0.675 mg/kg、总Cu含量为120 mg/kg的复合污染土壤为研究对象,以氨基酸废母液和糖蜜作为水稻种植肥料,结合不同的种植密度,研究水稻叶片SPAD值、稻米中重金属含量、土壤微生物种群变化以及土壤有效态重金属在不同时期的含量变化、水稻植物重金属在不同时期、不同部位的变化。结果表明,施加糖蜜能显著减弱重金属对水稻的胁迫,糖蜜与密度为4株/盆(加密1倍)协同阻控重金属吸收的作用更加显著。在水稻种植试验中,施加糖蜜与不同种植密度结合,可提高水稻叶片SPAD值1.82~6.51,降低土壤有效态Cd含量0.0220~0.0306 mg/kg,降低土壤有效态Cu含量2.2887~8.0300 mg/kg,分别降低水稻根中总Cd、总Cu含量0.0646~0.6357、1.5502~63.7990 mg/kg,降低水稻茎中总Cd、总Cu含量0.1148~0.4529、1.0433~20.2448 mg/kg,降低水稻叶中总Cd、总Cu含量0.0124~0.4951、0.6087~19.2278 mg/kg,降低水稻精米中总Cd、总Cu含量0.0223~0.0620、0.3431~1.5327 mg/kg。同时,施加糖蜜后能使土壤中微生物种群丰度明显增加,Ace指数最高达4830.46(A1处理),Chao指数最高达4320.18(A1处理),Shannon指数最高达6.50(A2处理),进一步验证糖蜜对水稻阻控复合污染重金属的积极作用。

小江河滩表土磁化率与Cu、Cd相关性差异及原因

磁化率与重金属元素之间的相关性是利用磁化率评估区域重金属污染的前提。文章通过测定东川小江河谷30个河滩表土样品的磁化率与Cu、Cd元素发现,小江河滩表土磁化率(低频)平均值为218.46×10-8m3/kg,频率磁化率百分数为0.87%;Cu、Cd平均含量分别为130.86 mg/kg和0.18 mg/kg。磁化率与Cu、Cd元素含量均在P<0.01级别上呈正相关,但磁化率与Cu的相关性(R=0.624)明显高于Cd(R=0.495)。X射线衍射鉴定和电子显微观察显示河滩表土的主要载磁物质(对表土磁化率值起主要贡献的物质)为粒径10~200μm的多畴磁铁矿。载磁物质的Cu、Cd元素测定结果显示,载磁物质Cu平均含量为420.95 mg/kg,高出所在表土样品平均值3倍以上,而Cd的平均含量为0.16 mg/kg,低于其所在表土样品的平均值。研究结果表明,载磁物质与Cu元素存在着同源(伴生)排放关系,而与Cd元素存在此类关系的概率较低,这可能是小江河滩表土磁化率与Cu相关性高于Cd的主要原因。

银叶树对Pb、Cd、Cu污染模拟湿地的适应性和修复潜力

【目的】探究银叶树(Heritiera littoralis)对重金属污染湿地环境的修复潜力。【方法】以银叶树为研究对象,在盆栽条件下模拟湿地环境,以不添加重金属为对照(CK),探究T_(1)(50 mg·L^(-1)Pb+5 mg·L^(-1)Cd+100 mg·L^(-1)Cu)、T_(2)(100 mg·L^(-1)Pb+10 mg·L^(-1)Cd+200 mg·L^(-1)Cu)、T_(3)(200 mg·L^(-1)Pb+20 mg·L^(-1)Cd+400 mg·L^(-1)Cu)3个复合污染水平(处理)对银叶树幼苗生长、养分吸收及Pb、Cd、Cu累积量的影响。【结果】与CK相比,T_(1)对银叶树根部生物量无显著影响,而T_(2)、T_(3)显著抑制根部生物量生长,3个处理银叶树的株高、地上生物量、总生物量与CK无显著差异;T_(1)处理银叶树的耐性系数为103.96%,T_(2)、T_(3)处理分别降至95.18%、80.80%;3个处理银叶树的N、P、K吸收量无显著变化。随着重金属含量的提高,银叶树对Pb、Cd、Cu的吸收量均不断增加,且大部分储存在根部;3个处理银叶树对Pb、Cu的转运系数较对照均显著下降,对Cd的转运系数则呈现先上升后下降的变化趋势。熵权TOPSIS模型评价结果表明,T_(3)处理银叶树的修复潜力最好,T_(2)、T_(1)次之。【结论】银叶树对复合重金属污染湿地的适应性较高,但高浓度重金属显著抑制根系生长;在ρ(Pb)≤50 mg·L^(-1)、ρ(Cd)≤5 mg·L^(-1)、ρ(Cu)≤100 mg·L^(-1)的重金属污染湿地中,银叶树生长不受影响。

叶面阻控剂对大白菜Cu、Pb、Cd、As含量及产量的影响

土壤重金属污染已成为威胁农产品安全和人类健康的重要问题。为了验证喷施叶面阻控剂降低As-Cu复合污染土壤上大白菜重金属铜(Cu)、铅(Pb)、镉(Cd)、砷(As)的污染效应,在弥勒市选取有代表性的农田,通过田间试验研究了硅肥、铁肥、锌肥、硒肥对As-Cu复合污染土壤上的大白菜Cu,Pb,Cd,As含量及大白菜产量的影响。结果表明,与对照相比,喷施叶面阻控剂均有效降低了大白菜可食用部位Cu、Pb、Cd、As含量,降幅分别为13.32%~36.15%、25.31%~52.39%、14.75%~29.27%、33.55%~45.68%。喷施不同叶面阻控剂有效增加了大白菜产量,增幅为0.10%~3.20%,其中以喷施硅肥处理的白菜产量最高。综合不同阻控剂降低大白菜可食用部位Cu、Pb、Cd、As含量及对大白菜的增产效应,在本试验条件下,在以硅肥的喷施效果最佳。

Revealing the Role of Defect in 3D Graphene-Based Photocatalytic Composite for Efficient Elimination of Antibiotic and Heavy Metal Combined Pollution

Defect engineering can give birth to novel properties for adsorption and photocatalysis in the control of antibiotics and heavy metal combined pollution with photocatalytic composites.However,the role of defects and the process mechanism are complicated and indefinable.Herein,TiO_(2)/CN/3DC was fabricated and defects were introduced into the tripartite structure with separate O_(2)plasma treatment for the single component.We find that defect engineering can improve the photocatalytic activity,attributing to the increase of the contribution from h^(+)and OH.In contrast to TiO_(2)/CN/3DC with a photocatalytic tetracycline removal rate of 75.2%,the removal rate of TC with D-TiO_(2)/CN/3DC has increased to 88.5%.Moreover,the reactive sites of tetracycline can be increased by adsorbing on the defective composites.The defect construction on TiO_(2)shows the advantages in tetracycline degradation and Cu^(2+)adsorption,but also suffers significant inhibition for the tetracycline degradation in a tetracycline/Cu^(2+)combined system.In contrast,the defect construction on graphene can achieve the cooperative removal of tetracycline and Cu^(2+).These findings can provide new insights into water treatment strategies with defect engineering.

Investigation on the Novel High-performance Copper/Graphene Composite Conductor for High Power Density Motor

High-performance Cu/Graphene composite wire synergistically strengthened by nano Cr_(3)C_(2) phase was directly synthesized via hot press sintering followed by severe cold plastic deformation, using liquid paraffin and CuCr alloy powder as the raw materials. Since graphene is in situ formed under the catalysis of copper powder during the sintering process, the problem that graphene is easy to agglomerate and difficult to disperse uniformly in the copper matrix has been solved. The nano Cr_(3)C_(2)-particles nailed at the interface favor to improve the interface bonding. The Cu/Graphene composite possesses high electrical conductivity, hardness, and plasticity. The composite wire exhibits high electrical conductivity of 96.93% IACS, great tensile strength of 488MPa, and excellent resistance to softening. Even after annealing at 400℃ for 1 h, the tensile strength can still reach 268 MPa with a conductivity of about 99.14% IACS.The wire's temperature coefficient of resistance(TCR) is largely reduced to 0.0035/℃ due to the complex structure,which leads the wire to present low resistivity at higher temperatures. Such Cu/Graphene composite wire with excellent comprehensive performance has a good application prospect in high-power density motors.

粉煤灰基P型沸石吸附水中Cu^(2+)和Cd^(2+)

以粉煤灰(FA)为原料经水热反应合成了P型沸石(Z-P).采用X射线荧光光谱仪、X射线衍射仪、场发射环境扫描电子显微镜、比表面孔径分析仪、傅里叶变换红外光谱仪和X射线光电子能谱对Z-P进行表征,并研究了其对Cu^(2+)和Cd^(2+)的吸附性能.结果表明,Z-P的BET比表面积和孔隙体积分别为38.46m^(2)/g和0.2180cm^(3)/g,均高于FA的1.273m^(2)/g和0.0120cm^(3)/g.FA、Z-P对Cu^(2+)和Cd^(2+)的吸附更符合拟二级动力学模型和Langmuir等温线模型.Z-P对Cu^(2+)和Cd^(2+)的最大吸附量分别为157.48,131.57mg/g,远高于于FA的30.88,25.47mg/g.Z-P对Cd^(2+)的循环再生吸附效果好,但对Cu^(2+)的循环再生吸附效果较差.离子强度对Z-P吸附Cu^(2+)和Cd^(2+)分别起促进和抑制作用.表明Z-P可以作为有效且廉价的Cu^(2+)、Cd^(2+)吸附剂,为FA的资源化利用和含Cu^(2+)、Cd^(2+)重金属离子废水吸附剂的开发提供了一种方法.

Morphology and Frictional Characteristics Under Electrical Currents of Al_2O_3/Cu Composites Prepared by Internal Oxidation

Two Al2O3/Cu composites containing 0.24 wt.% Al2O3 and 0.60 wt.% Al2O3 separately are prepared by internal oxidation. Effects of sliding speed and pressure on the frictional characteristics of the composites and copper against brass are investigated and compared. The changes in morphology of the sliding surface and subsurface are examined with scanning electron microscope （SEM） and energy dispersive X-ray spectrum （EDS）. The results show that the wear resistance of the Al2O3/Cu composites is superior to that of copper under the same conditions, Under a given electrical current, the wear rate of Al2O3/Cu composites decreases as the Al2O3-content increases, However, the wear rates of the Al2O3/Cu composites and copper increase as the sliding speed and pressure increase under dry sliding condition. The main wear mechanisms for Al2O3/Cu composites are of abrasion and adhesion; for copper, it is adhesion, although wear by oxidation and electrical erosion can also be observed as the speed and pressure rise.

Effect of electrical current on tribological property of Cu matrix composite reinforced by carbon nanotubes

Cu matrix composite reinforced with 10%（volume fraction） carbon nanotubes（CNTs/Cu） and pure Cu bulk were prepared by powder metallurgy techniques under the same consolidation processing condition.The effect of electrical current on tribological property of the materials was investigated by using a pin-on-disk friction and wear tester.The results show that the friction coefficient and wear rate of CNTs/Cu composite as well as those of pure Cu bulk increase with increasing the electrical current without exception,and the effect of electrical current is more obvious on tribological property of pure Cu bulk than on that of CNTs/Cu composite;the dominant wear mechanisms are arc erosion wear and plastic flow deformation,respectively;CNTs can improve tribological property of Cu matrix composites with electrical current.

Properties and microstructure of Cu/diamond composites prepared by spark plasma sintering method

Cu/diamond composites have been considered as the next generation of thermal management material for electronic packages and heat sinks applications. Cu/diamond composites with different volume fractions of diamond were successfully prepared by spark plasma sintering（SPS） method. The sintering temperatures and volume fractions（50%, 60% and 70%） of diamond were changed to investigate their effects on the relative density, homogeneity of the microstructure and thermal conductivity of the composites. The results show that the relative density, homogeneity of the microstructure and thermal conductivity of the composites increase with decreasing the diamond volume fraction; the relative density and thermal conductivity of the composites increase with increasing the sintering temperature. The thermal conductivity of the composites is a result of the combined effect of the volume fraction of diamond, the homogeneity and relative density of the composites.

Microstructural development and its effects on mechanical properties of Al/Cu laminated composite

The microstructural development and its effect on the mechanical properties of Al/Cu laminated composite produced by asymmetrical roll bonding and annealing were studied. The composite characterizations were conducted by transmission electron microscope（TEM）, scanning electron microscope（SEM）, peeling tests and tensile tests. It is found that the ultra-fine grained laminated composites with tight bonding interface are prepared by the roll bonding technique. The annealing prompts the atomic diffusion in the interface between dissimilar matrixes, and even causes the formation of intermetallic compounds. The interfacial bonding strength increases to the maximum value owing to the interfacial solution strengthening at 300 °C annealing, but sharply decreases by the damage effect of intermetallic compounds at elevated temperatures. The composites obtain high tensile strength due to the Al crystallization grains and Cu twins at 300 °C. At 350 °C annealing, however, the composites get high elongation by the interfacial interlayer with submicron thickness.

粉煤灰与生活污泥混合制备吸附剂对Cd(Ⅱ)和Cu(Ⅱ)的试验研究

以粉煤灰和生活污泥为原料,经过物理活化、物理-化学活化制备了改性污泥吸附剂,通过比表面积测定仪(BET)、扫描电镜(SEM)、X射线衍射仪、傅里叶红外光谱仪(FTIR)和Zeta电位仪等设备研究了污泥吸附剂的性质,分析了改性污泥吸附剂对Cd(Ⅱ)和Cu(Ⅱ)的去除效果和吸附机理。结果表明,原污泥吸附剂(RSA)结构致密,BET比表面积为12.604 m^(2)/g,改性污泥吸附剂(MSA)表面粗糙,孔洞明显变大,BET比表面积为52.573 m^(2)/g。RSA和MSA吸附Cd(Ⅱ)和Cu(Ⅱ)在360 min后基本达到平衡。MSA对Cd(Ⅱ)和Cu(Ⅱ)的去除率较RSA分别增大了30.83%和61.81%。随着pH值(2≤pH≤6)增大,RSA对Cu(Ⅱ)的去除率从16.83%上升到74.32%,对Cd(Ⅱ)的去除率从3.17%上升到36.33%;MSA对Cu(Ⅱ)的去除率从51.50%上升到95.77%,对Cd(Ⅱ)的去除率从25.00%上升到48.17%。MSA对Cd(Ⅱ)和Cu(Ⅱ)的吸附容量分别从298 K时的7.230 mg/g和15.480 mg/g增加到318 K时的9.540 mg/g和16.206 mg/g。MSA对Cd(Ⅱ)和Cu(Ⅱ)最大理论吸附量分别为18.69 mg/g和20.92 mg/g,Langmuir吸附等温模型R 2分别为0.9965和0.9980,准二级动力学模型R 2均为0.99以上,表明MSA对Cd(Ⅱ)和Cu(Ⅱ)的吸附过程以羟基和羧基反应的化学作用为主,单分子层吸附的物理作用为辅。MSA吸附Cd(Ⅱ)和Cu(Ⅱ)是一个吸热过程,且吸附Cu(Ⅱ)是自发的。因此,改性污泥可以作为一种潜在的吸附材料处理含重金属的废水。

rGO/CdS@HAP复合微球的光催化活性增强机理

为提升CdS基复合材料的光催化活性和稳定性,运用水热法在CdS@HAP(羟基磷灰石)微球表面包覆rGO(还原氧化石墨烯)并制备rGO/CdS@HAP光催化材料,利用XRD(X射线衍射)、SEM(扫描电子显微镜)、UV-vis(紫外-可见吸收光谱)等手段分析材料的晶体结构和理化性质,结合MB(亚甲基蓝)的光催化降解实验探讨rGO/CdS@HAP的光催化活性增强机理。结果表明:rGO/CdS@HAP具有中空微球结构,直径4—5μm,rGO以薄纱状均匀包裹在CdS@HAP表面;rGO/CdS@HAP具有优异的可见光吸收能力,在可见光辐射120 min后对MB的去除率高达94%,在光催化循环实验中表现出优异的光催化活性和稳定性。机理分析证实,由CdS和HAP构建的Ⅰ型异质结带隙较窄,有助于提升复合材料对可见光的吸收和利用,rGO在CdS@HAP表面的包覆提升载流子分离效率的同时为光生空穴提供高速的传输路径,有效抑制CdS的光腐蚀,从而实现rGO/CdS@HAP光催化活性和稳定性的显著增强。

时效处理对Cu-Y_(2)O_(3)-Ti复合材料组织及性能的影响

以Cu、Y、Ti和CuO粉末为原料,采用机械合金化(MA)和热还原的方法制备了Cu-Y_(2)O_(3)-Ti复合粉末。然后经放电等离子烧结(SPS)技术制备了Cu-Y_(2)O_(3)-Ti复合材料,并对材料进行了900℃固溶1 h和不同温度时效2 h的处理。采用光学显微镜(OM)、扫描电镜(SEM)、X射线衍射仪(XRD)、能谱仪(EDS)、拉伸试验和导电率测量仪等研究了不同温度时效处理对Cu-Y_(2)O_(3)-Ti复合材料组织及性能的影响。结果表明:随着时效温度的升高,Cu-Y_(2)O_(3)-Ti复合材料的晶粒和第二相尺寸增大,导电率降低,最大应变和抗拉强度先增大后减小。Cu-Y_(2)O_(3)-Ti复合材料经900℃固溶1 h+400℃时效2 h后,综合性能最优,其具有良好塑性的同时,抗拉强度和导电率分别达到326.4 MPa和73.0%IACS。

三维互穿结构Cu-W触头抗熔焊机理

触头闭合回跳电弧引起的开关电器动熔焊问题,直接影响大功率接触器的电寿命和可靠性。为此设计了2种三维互穿有序结构的四边形和菱形十二面体的Cu-W复合材料触头,围绕触头动熔焊过程中的电弧、熔池、液滴溅射及凝固相变降温等问题,建立触头熔池流体动力学模型和冷凝降温数学模型,研究了2种有序结构和商用无序结构的触头阳极在闭合回跳电弧作用下熔化温度分布、熔池喷溅形貌和接触区域金属凝固过程,通过模拟熔焊实验平台进行了熔焊力验证。结果表明,通过调节三维互穿有序W骨架结构,能够有效抑制熔池扩散和液态金属喷溅,并降低熔焊力,从而提高Cu-W复合材料的抗熔焊性能。

复合生物炭-坡缕石对Cd污染土壤的钝化修复

为实现重金属污染土壤的高效、环保修复,采用慢氧限制热解法制备生物炭-坡缕石复合材料(BC/PAL)。考察BC/PAL对土壤理化性质、Cd的浸出毒性和在土壤中的赋存形态、玉米生长状况及Cd的富集转运影响,从而评价该材料对土壤中Cd的潜在生态风险改善及稳定效果。结果表明,添加BC/PAL后土壤pH显著增加,当投加量为8%时,pH较对照组(CK)升高1.14。当BC/PAL投加量为6%和8%时,土壤中Cd的毒性特征浸出程序(TCLP)浸出毒性较CK下降60%以上。添加BC/PAL后,Cd在土壤中的赋存状态从活泼趋于稳定。BC/PAL可减轻Cd对玉米的胁迫,促进玉米生长,当投加量为6%时,玉米鲜重增加221.43%。BC/PAL大大降低了土壤中Cd的潜在生态风险及生物有效性,是一种高效、环保的土壤修复材料。

晶粒尺寸对界面含Cr-O-C防黏层Cu/Ni复合体拉伸性能的影响

通过分子动力学方法研究含Cr-O-C防黏层的具有不同晶粒尺寸的Cu/Ni复合体的拉伸变形。结果表明:当Cu/Ni复合体的晶粒尺寸大于12 nm时,不论界面不含Cr、O和C原子或含有定量Cr、O和C原子,复合体的屈服强度随着晶粒尺寸的减小呈现增大趋势,符合细晶强化规律,晶粒塑性变形主要受晶体内部的位错滑移控制,最大应力增加9.52%;当晶粒尺寸小于12 nm时,由于晶界所占比例的增加,拉伸过程的塑性变形更多受晶界变形控制,屈服强度下降。Cr-O-C界面弱化了Cu/Ni复合体的强度,随着界面上Cr、O和C原子数量的增加,Cu/Ni复合体的抗拉强度随之降低,最大应力下降56.40%,Cu/Ni复合体内部的位错数量也随之降低,转移到Ni表面的Cu原子数量随之减少。

生物炭降低铁皮石斛对重金属Cu和Cd吸收的效率及机制研究

目的:探究生物炭降低铁皮石斛对重金属铜(Cu)和镉(Cd)吸收的效率及机制,为生物炭在铁皮石斛等中药材种植过程中的应用提供科学依据。方法:基质浸泡于15 mg/L的Cu^(2+)和Cd^(2+)溶液,稳定后分别加入1%、5%及10%含量的不同种生物炭,以未施加生物炭的处理组作为对照,在种植铁皮石斛后10、30、50 d取样,运用ICP-OES检测铁皮石斛中2种重金属的浓度,分析玉米秸秆、污泥以及椰壳生物炭对铁皮石斛中重金属吸收的效果。结果:3种生物炭对重金属Cu^(2+)和Cd^(2+)都存在一定的吸附效果,其中添加10%的椰壳生物炭对Cu^(2+)吸附效果明显,平均去除率达30.99%;10%的玉米秸秆生物炭对Cd^(2+)吸附效果明显,平均去除率达27.95%。同时,3种生物炭对Cu^(2+)、Cd^(2+)的吸附过程符合准二级动力学和Langmuir模型,主要为化学吸附,吸附过程近似为单分子层吸附。结论:施加生物炭可以降低铁皮石斛中重金属Cu^(2+)和Cd^(2+)的含量,且对2种重金属吸附力较强的生物炭种类不同,主要原因由于生物炭之间比表面积以及孔隙的差异,造成不同生物炭与重金属之间的离子交换和沉淀作用不同。