304不锈钢表面Ta沉积膜N离子 注入后的摩擦学性能

利用磁控溅射方法在304不锈钢表面沉积厚约100 nm的钽膜,并对其进行氮等离子体基离子注入,注入能量为50 keV,用掠射X线衍射(GXRD)分析了改性层的组成相结构,选取φ6 mm的GCr15钢球作为对磨件,测试了处理后试样的磨损性能.研究结果表明:改性层含有钽的氮化物,注入剂量较低时,化合物为TaN0.1;随着注入剂量的增加,形成TaN.经过该处理后的304不锈钢磨损性能提高,磨损率降低幅度达到66.3％;摩擦因数有所降低,表面摩擦因数由未处理前的1.0～1.2下降至处理后的0.2～0.4.     

微波ECR等离子体中铝合金的全方位氮离子注入

使用微波ECR等离子体对LD10铝合金材料进行全方位氮离子注入。AES深度分布结果表明,在30KV注入电压下,注入深度约有150mm。对相互垂直的两不同表面进行的硬度分析表明,全方位氮离子注入对试样的不同表面改性效果相同,硬度均获得明显提高。     

局部非热平衡对增强型地热系统的影响探究

干热岩的有效开发需要依托增强型地热系统所形成的复杂裂缝网络,而致密基质与不同裂缝之间形成了不同尺度的传质传热环境,导致多孔介质传质传热过程存在复杂性．为分析局部非热平衡对复杂裂缝系统传质传热过程的影响,建立考虑局部非热平衡假设的微观孔隙尺度传质传热模型,揭示局部非热平衡假设对基质-裂缝传质传热过程影响的微观作用机理．同时,建立考虑局部非热平衡假设的嵌入式离散裂缝模型和求解方法,通过储层物性参数敏感性研究分析考虑局部非热平衡假设的必要性．结果表明,不考虑局部非热平衡假设会低估在近裂缝区域的岩石温度,而高估传热前缘区域的流体温度;局部非热平衡对增强型地热系统的影响主要体现在注入早期;注入强度越高,或基质裂缝渗透率越低,或基质裂缝孔隙度差异越大,或岩石热扩散系数越大,或对流换热系数越小,都越需要考虑局部非热平衡假设．研究结果可为增强型地热系统的精确数值模拟提供参考．     

基片温度对氧离子注入硅形成SOI材料的影响

系统地研究了氧离子注入时基片的温度对形成硅-绝缘体(SOI)材料的影响.研究结果表明:在氧离子注入时基片温度为550℃,注入能量为150 keV,注入剂量为1.8×1018ions/cm2的条件下,能够形成质量良好的SOI材料.     

微波ECR氧等离子体参数测量

利用双探针对微波ECR氧离子体参数进行了诊断研究,测量了等离子体的双探针伏安曲线并计算出电子温度和离子密度,分析了气压、微波功率、氧气流量等参数对等离子体参数的影响.结果表明:a.随着气压的升高,等离子体密度先增大后减小,电子温度逐渐减小.b.等离子密度随微波功率的增加先增加后达到饱和,电子温度受微波功率影响很小.c.随着氧气流量的增加,等离子体密度和电子温度都减小.     

铝合金等离子体基离子注入氮/钛改性层成分分布

用X射线光电子能谱（XPS）研究了工艺参数（注入电压或能量、注入时间或剂量、磁控靶溅射电流）对铝合金LY12（即2024）等离子体基离子注入氮 离子注入钛形成的改性层成分分布影响。结果表明，氮在注入层呈高斯分布，而钛沿注入方向逐渐减少。钛的注入使已注入的氮的分布有所拓宽。随着注入电压和时间的增加，钛的注入深度及含量有所增加；存在一个注入时间或/和磁控靶溅射电流阈值，在低于该值下注入钛主要表现为注入效应，没有钛沉积层出现，在高于该值下注入钛由注入效应逐渐表面为沉积效应，有明显的钛层出现。     

等离子体联合超声波生物酶技术在织物退浆中的应用

研究等离子体预处理后织物在超声波作用下采用生物酶退浆处理的工艺.获取了等离子体联合超声波生物酶处理工艺中超声波的最佳工艺参数,即处理功率180W,温度50℃,时间40min.结果表明,这种新工艺的组合不但能够达到良好的退浆效果,而且加工过程较超声波生物酶工艺更节能、环保.     

飞秒激光切割CFRP质量实验及模拟研究

为了探究飞秒激光切割碳纤维增强树脂基复合材料(CFRP)的主要影响因素,采用控制变量法探究了不同能量密度和光斑重叠率对热影响区宽度、表面粗糙度及切缝锥度的影响规律,基于双温方程,采用时间差分法模拟了飞秒激光与碳纤维相互作用时电子-晶格的温度场演变过程。实验结果显示:在脉冲频率不变条件下,提高激光功率可使切缝热影响区宽度增加,粗糙度及切缝锥度加大,切割质量下降;在固定激光功率并单一提升脉冲频率条件下,切割质量随脉冲频率增加而降低并趋于饱和。模拟结果显示:能量密度越大,电子和晶格的平衡温度越高,达到热平衡所用的时间越长,热效应越明显。分析指出光斑重叠率和脉冲能量密度是影响加工质量的两个重要因素,激光功率及脉冲频率的改变可改变脉冲能量密度和光斑重叠率,间接影响加工质量。     

电子等离子体的束缚和热平衡必要条件

电子等离子体在静磁场和静电场的束缚下,可以达到热平衡态。达到热平衡态的必要条件是电子等离子体的密度分布要满足泊松方程,且使得等离子体内的磁力线为等势线.同时,电子等离子具有柱体的形状,在任何部位不能扩展出它所在的磁通管.当磁场有不均匀性时,电子等离子体是不能达到热平衡态的,最终电子都将扩散到管壁.     

FLUENT模拟分析巴基纸基复合材料的温度场分布

为了研究加热过程中加热功率及聚合物基体导热系数等因素对巴基纸基复合材料达到稳态所需时间及温度场分布的影响规律,采用有限元软件FLUENT分别模拟了不同工况条件下矩形弯曲、正弦形及平板形巴基纸增强聚合物基复合材料的热传导性能。计算结果表明:三种形状巴基纸基复合材料加热达到稳态后整体温度水平均随加热功率的增大呈线性增长,且巴基纸基复合材料达到稳态时所需时间也随加热功率的增大而延长。随着聚合物基体材料导热系数的增大,巴基纸基复合材料温度分布更加均匀,且巴基纸基复合材料达到稳态所需要的时间越短。分析认为,加热功率对巴基纸基复合材料温度分布规律的影响主要通过巴基纸加热片的单位体积热源起作用;聚合物基体导热系数增大利于巴基纸加热片热量的散出,因此缩短了巴基纸基复合材料达到稳态的所需时间。     

退火条件对注Mn GaAs结构的影响

通过离子注入在半绝缘GaAs衬底中掺引入Mn杂质,进行不同温度的退火后,在样品中形成了磁性MnAs粒子.利用原子力显微镜和磁力显微镜对样品的表面进行分析,发现退火条件会影响样品磁性粒子的分布.运用二次离子质谱仪测量了样品中Mn的深度分布,发现退火温度对样品中Mn的分布有很大影响.     

Synthesis of Co-silicides and fabrication of microwave power device using MEVVA source implantation

Co synthesis silicides with good properties were prepared using MEVVA ion implantation with flux of 25-125μA/cm2 to does of 5×1017/cm2. The structure of the silicides was investigated using X-ray diffraction (XRD) and transmission electron microscopy (TEM). TEM analysis shows that if the ion dose is greater than 2×1017/cm2, a continuous silicide layer will be formed. The sheet resistance of Co silicide decreases with an increase in ion flux and ion dose. The formation of silicides with CoSi and CoSi2 are identified by XRD analysis. After annealing, the sheet resistance decreases further. A continuous silicide layer with a width of 90-133 nm is formed. The optimal implantation condition is that the ion flux and dose are 50μA/cm2 and 5×1017/cm2, respectively. The optimal annealing temperature and time are 900℃ and 10 s, respectively. The ohmic contact for power microwave transistors is fabricated using Co ion implantation technique for the first time. The emitter contact resistance and noise of the t     

STUDY ON COMPLEX IMPEDANCE SPECTROSCOPY OF CU-IMPLANTED SEMICONDUCTING (BaO.72PbO.28)TiO3 CERAMICS

The ac impedance of Nb-doped semicon-ducting (Bao.72Pbo.28)TiO3 ceramics implanted with copper ions(200keV,6X1015 and 1X1017 ions/cm2) in the temperature range 25-320C and the frequency range 10 Hz -13MHz was measured. According to the change of impedance spectroscopy and the equivalent circuit model of semiconducting(Ba, Pb)TiO3 ceramics, the dependence of resistance of bulk and grain-boundary on temperature was analyzed. The results show that relatively low dose must be used to increase the magnitude of the positive temperature coeffieient of resistance(PTCR)effects in the cermmics. In addition,the effects of Cu ion implantation on the PTCR behavior of the ceramics was studied by raststance-tempera-ture measurement.     

PCR热循环系统热性能影响因素的等效电路研究

根据热电相似性理论,建立基于半导体制冷片的聚合酶链反应(PCR)热循环系统的等效电路模型,将系统中各部件的热参数等效替换成相应的电路参数.利用该模型,分别分析在加热和制冷模式下,驱动电流、散热器热阻和样品块材料等因素对PCR热循环系统热性能的影响程度,得到了在各工作状况下样品块温度的稳态和动态曲线.结果表明：当驱动电流取最佳值Im时,系统可获得最佳制冷效果;驱动电流越大或材料的热容越小,系统升降温速度越快;材料不同对系统的Im值无明显影响;散热器热阻越小,样品块温度稳态值越低,系统的Im值越大.在设计时选择低热容的材料、低热阻的散热器以及最佳Im,可使系统获得最佳的热性能.     

退火温度对铜纳米颗粒复合材料的三阶非线性光学性质的影响

采用离子注入法制备铜纳米颗粒复合材料,在波长为790 nm的入射激光作用下,运用Z-扫描技术测量了铜纳米颗粒复合材料的非线性光学折射率和非线性光学吸收系数,分析了退火温度对铜纳米颗粒复合材料光学性质的影响。结果表明,随着退火温度的升高,铜纳米颗粒复合材料的颗粒尺寸明显增大,且光学非线性折射率上升。通过改变非晶二氧化硅中铜纳米颗粒复合材料的形状,得到不同的三阶非线性光学系数的特定值。     

Experimental and numerical study on a micro jet cooling solution for high power LEDs

An active cooling solution based on close-looped micro impinging jet is proposed for high power light emitting diodes (LEDs). In this system, a micro pump is utilized to enable the fluid circulation, impinging jet is used for heat exchange between LED chips and the present system. To check the feasibility of the present cooling system, the preliminary experiments are conducted without the intention of parameter opti-mization on micro jet device and other system components. The experiment results demonstrate that the present cooling system can achieve good cooling effect. For a 16.4 W input power, the surface temperature of 2 by 2 LED array is just 44.2℃ after 10 min operation, much lower than 112.2℃, which is measured without any active cool-ing techniques at the same input power. Experimental results also show that increase in the flow rate of micro pump will greatly enhance the heat transfer efficiency, how-ever, it will increase power consumption. Therefore, it should have a trade-off be-tween the flow rate and the power consumption. To find a suitable numerical model for next step parameter optimization, numerical simulation on the above experiment system is also conducted in this paper. The comparison between numerical and ex-periment results is presented. For two by two chip array, when the input power is 4 W, the surface average temperature achieved by a steady numerical simulation is 34℃, which is close to the value of 32.8℃ obtained by surface experiment test. The simu-lation results also demonstrate that the micro jet device in the present cooling sys-tem needs parameter optimization.     

超临界水中典型金属离子溶解度研究

研究了Cu^2 、Mn^2 和Fe^2 在超临界水中的溶解度，通过实验发现，金属离子在超临界水中的溶解度在开始阶段随着停留时间的增加而减少，当停留时间达到一定的时间后，溶解度基本上不再变化。实验对因反应器腐蚀而溶出的铁离子质量浓度进行了测定，以了解超临界水体系对反应器的腐蚀状况，反应器溶出的Fe^2 浓度随着温度的升高而增加。采用基于水合机理模型关联了金属离子在超临界水中的溶解度，表明在同一温度下，金属离子的溶解度对数与水密度对数呈线性关系。     

分布反馈光纤激光传感阵列结构优化

为解决分布反馈光纤激光传感阵列功率一致性的问题,建立了分布反馈光纤激光波分复用阵列输出功率预测模型,采用差值寻优法对激光器进行排序,并通过在阵列尾部增加980nm反射镜进一步提高了阵列的功率均衡水平,实现了阵列结构优化。实验结果表明,优化后的阵列功率波动水平明显改善,有效地解决了阵列末端信号解调效果差的问题,扩大了阵列实际复用容量,提高了组阵效率。上述方法对大规模分布反馈光纤激光器传感器阵列的结构设计具有借鉴价值。     

Dielectric Properties and Microwave Heating of Molybdenite Concentrate at 2.45 GHz Frequency

Dielectric properties were measured using cavity perturbation method. The temperature rising behaviors of molybdenite concentrate were investigated in the field of microwave. This process was conducted to show the microwave absorption properties of molybdenite concentrate and the feasibility of microwave roasting molybdenite concentrate to prepare high purity M_OO_3. The dielectric constant,dielectric loss,and loss tangent increase from 3. 51 to 5. 04,0. 22 to 0. 51 and 0. 065 to 0. 102 respectively. They are proportional to the apparent density of molybdenite concentrate in the range of 0. 9-1. 4 g/cm3. The results show that the molybdenite concentrate has good microwave absorption capacity in the conventional density range. The temperature rising curves show that the apparent heating rate of the molybdenite concentrate increases with the increase in microwave power and decreases with the increase in the sample mass and thickness. The temperature of concentrate sample of 100 g reaches approximately 800 ℃ after 5 min of microwave treatment at 0. 5 kW of power. Our findings show that it is feasible to prepare high-purity M_OO_3 from molybdenite concentrate by microwave roasting.     

Dielectric Properties and Microwave Heating of Molybdenite Concentrate at 2.45 GHz Frequency

Dielectric properties were measured using cavity perturbation method.The temperature rising behaviors of molybdenite concentrate were investigated in the field of microwave.This process was conducted to show the microwave absorption properties of molybdenite concentrate and the feasibility of microwave roasting molybdenite concentrate to prepare high purity MoO3.The dielectric constant,dielectric loss,and loss tangent increase from 3.51 to 5.04,0.22 to 0.51 and 0.065 to 0.102 respectively.They are proportional to the apparent density of molybdenite concentrate in the range of 0.9-1.4 g/cm3.The results show that the molybdenite concentrate has good microwave absorption capacity in the conventional density range.The temperature rising curves show that the apparent heating rate of the molybdenite concentrate increases with the increase in microwave power and decreases with the increase in the sample mass and thickness.The temperature of concentrate sample of 100g reaches approximately 800 ℃ after 5 min of microwave treatment at 0.5 kW of power.Our findings show that it is feasible to prepare high-purity MoO3 from molybdenite concentrate by microwave roasting.