载体包裹填料提高PE/PP/EPDM/BN材料导热性

以三元乙丙橡胶(EPDM)/氮化硼(BN)复合材料为母料,通过熔融共混EPDM/BN复合材料与聚乙烯(PE)、聚丙烯(PP),制备PE/PP/EPDM/BN复合材料。采用PE∶PP的比例为5∶5,以使复合材料形成共连续结构;通过EPDM包裹BN的方法,实现BN在PE/PP/EPDM/BN复合材料共连续结构的相界面处分布,以形成导热通路,从而提高PE/PP/EPDM/BN复合材料的导热性能。通过接触角测试和扩散系数公式计算预测了EPDM会选择性分布在PE/PP/EPDM复合材料共连续结构的相界面处。通过连续度计算结果得出,EPDM为PE和PP总质量的15%时,EPDM的连续度为85.3%。由扫描电子显微镜分析表明EPDM在PE/PP/EPDM/BN复合材料中连续贯通。由导热测试分析知,随着BN含量的增加,PE/PP/EPDM/BN复合材料的热导率逐渐增加。这项研究提高了PE/PP复合材料的热导率,此材料在电子工业中可能具有潜在应用。     

Effect of ZrO<Subscript>2</Subscript> coating on<Emphasis Type="Italic">in vitro</Emphasis> formation of calcium phosphate

We prepared zirconia thin films on (100) Si wafer by using a chemical solution deposition with a zirconium naphthenate as a starting material. The films were pyrolyzed at 500°C for 10 min and finally annealed for 30 min in air at 500°C. Amorphous films after annealing had no distinct structure and were uniform along the cross section line.In vitro formation of the calcium phosphate was evaluated by the field emission-scanning electron microscope, energy dispersive X-ray spectrometer and Fourier transform infrared spectroscopy.     

The characteristics of a low-power-consumption plasma jet and ceramic coatings

The effects of the composition of plasma gases (Ar-N₂, Ar-H₂), arc current, and voltage on the temperature and velocity of a low-power (5 kW) plasma torch in the arc field free region has been investigated using an enthalpy probe. Coatings of Al₂O₃-13TiO₂ were deposited under different conditions. The results show that in the Ar-N₂ plasma, the enthalpy, temperature, and velocity change little with arc current and voltage when regulating the nitrogen proportion in the plasma gas. The hardness of the resulting coatings is 800 to 900 kg/mm² HV.300. For Ar-H₂ plasma, however, increases in the H₂ content in the mixture of the gases remarkably enhanced the velocity and heat transfer ability of the plasma jet, with the result that the coatings showed high hardness up to 1200 HV.     

TiN涂层性能的分析与测定

测定并分析了用PCVD法获得的TiN涂层内的残余应力、涂层的抗变形性以及涂层的耐磨性。实验结果表明,TiN涂层内有残余应应力存在,在一定的变形力作用下,涂层将发生脆性断裂,TiN涂层的耐磨性是45°淬火钢的24倍。TiN涂层这些特性为它的应用奠定了基础。     

AGING BEHAVIOUR OF PARTICULATE REINFORCED ALUMINUM ALLOY MATRIX COMPOSITES

The process of aging precipitation in SiC_p/6061 and Al_2O_3/6061 composites were investigated. Hardness testing, differential scanning calorimetry(DSC) and transmission electron microscopy were employed. Results showed that the precipitation phase form directly along dislocation lines in the composites because the particles produce high densities of dislocations which makes vacancy densities in the composites decrease, and the main precipitation phase at peak hardness was β′ phase.     

介孔立方ZrO2球形粒子准气相反应合成工艺的优化

采用一种新颖的基于WEB的人工神经网络-遗传算法系统对介孔立方ZrO2球形粒子准气相反应合成的新工艺进行了建模与优化设计.结果表明,合成最小粒径ZrO2前驱物球的最优参数为M[ZrOCl2·8H2O]=0.49 mol/L,VS=0.035 m3/h,P=99.80 kPa;ZrO2前驱物球的最小平均粒径为0.75μm.通过实验验证,此最优参数下合成的ZrO2前驱物球平均粒径为0.72 μm,计算值与实验值符合的较好.将合成的最小粒径前驱物球经干燥和600℃煅烧后,得到了平均粒径为0.64 μm的介孔立方ZrO2球.     

保温条件下过共晶Al-Si合金半固态浆料的组织演变

研究了保温时间和保温温度对电磁搅拌ZL117合金半固态浆料稳定性的影响.试验结果表明：半固态浆料中初生Si的颗粒直径随着保温时间的延长而逐渐增大,但在前15 min内增长速度比较缓慢,15 min后增长较快;随着保温温度的升高而缓慢增大;初生Si的形状系数随着保温时间的延长而变得越来越大,但也在前15 min内变化较为缓慢,15 min后变大速度突然加快;初生Si的形状系数在620 ℃下保温时最小,在610～620 ℃之间随着保温温度的升高而缓慢变小;在620～650 ℃之间随着保温温度的升高而逐渐增加.     

Comparative study of bis-piperidiniummethyl-urea and mono-piperidiniummethyl-urea as volatile corrosion inhibitors for mild steel

Bis-piperidiniummethyl-urea (BPMU) and mono-piperidiniummethyl-urea (MPMU) were developed as novel volatile corrosion inhibitors (VCIs). Their vapor corrosion inhibition property was evaluated by volatile inhibiting sieve test (VIS) and vapor inhibiting ability test (VIA). Volatile weight-loss test in a closed space was used to compare their volatility. Electrochemical impedance spectroscopy of a volatile corrosion inhibitor monitor (VCIM) was applied to study the effect of BPMU and MPMU on the corrosion inhibition of mild steel in thin electrolyte layer. The results show that BPMU has the better protection effect compared with MPMU. Adsorption of BPMU and MPMU on steel surface was investigated by X-ray photoelectron spectroscopy (XPS). It was shown that one BPMU molecule has two N atoms to coordinate with one Fe atom, and that one MPMU molecule has one N atom to coordinate with one Fe atom. The quantum chemical parameters were obtained by PM3 semi-empirical method. BPMU has the smaller HOMO-LUMO energy gap and the smaller net positive charge intensities of 4N and 8N atoms in its molecule.     

消失模样性能对铝合金液充型速度及间隙压力影响的数值计算

采用计算机模拟技术研究了聚苯乙烯模样汽化潜热及发气性对消失模铸造铝合金液充填速度及金属液／模样间隙压力的影响。结果表明，模样汽化潜热与发气性均严重影响铝合金液的充型速度及间隙压力。     

DMTAM光度法同时测定钯和钴

以硫脲作为掩蔽剂,在pH3.75～5.0的HAc—NaAc缓冲介质中,Pd、Co(Ⅱ)和DMTAM均能形成稳定的1∶2型配合物,其表观摩尔吸光系数分别为ε_(Pd)=6.14×10~4,ε_(Co)=6.20×10~4,遵守比尔定律的线性范围分别为Pd0～35μg/25ml,Co0～15μg/25ml。研究了30余种共存离子的影响。可应用于分子筛和矿样中Pd、Co的同时测定。