Zhengyou ZHOU
,
Xiaoshan WU
,
Jun DU
金属学报(英文版)
doi:10.1016/S1006-7191(08)60070-8
Effects of soft-magnetic MnZn ferrite (Mn0.5Zn0.5Fe2O4, MZF) and hard-magnetic Ba
ferrite (BaO?6Fe2O3, BaM) on the structure and magnetic transport properties of [La2/3Sr1/3MnO3]
(LSMO)/(x) [ferrites] (ferrites=MZF, BaM) composites have been investigated. It was found that the inclusion of MZF phase reduces
magnetization and ferromagnetic-paramagnetic transition temperature (Tc) of the composites. With increasing the content of the
dopants, the high-temperature magnetoresistance (MR) decreases, whereas low-temperature MR increases and reaches 42% at 150~K and
x=0.1. However, for the LSMO/BaM composites, magnetization and ferromagnetic-paramagnetic transition temperature (Tc)
decrease firstly as x<5 %, and then increase as x>5 %. The resistivity of the composites increases by five orders of magnitude
at x=1 % and is out of measured range at x=5 %. High magnetic field has little effect on the resistivity and magnetoresistance for
the composites with x>5 %, which may originate from the pinning effect of BaM grains.
关键词:
Composites
,
null
,
null
,
null
Mingjiu ZHAO
,
Yue LIU
,
Liqing CHEN
,
Jing BI
材料科学技术（英文）
In the present study, the modified continuum model, quench strengthening and dislocation pile-up model was respectively used to estimate the yield strength of SiCp/Al composites. The experimental results showed that the modified shear lag model or quench strengthening model would underestimate the yield strength of SiCp/Al composites. However, the modified Hall-Petch correlation on the basis of the dislocation pile-up model, expressed as σcy = 244 + 371λ-1/2, fitted very well with the experimental data, which indicated that the strength increase of SiCp/Al composites might be due to the direct blocking of dislocation motion by the particulate-matrix interface. Namely, the dislocation pile-up is the most possible strengthening mechanism for SiCp/Al composites.
关键词:
Silicon carbide particulate
,
null
,
null
,
null
Xin TONG
,
Yong CHEN
,
Huiming CHENG
材料科学技术（英文）
Carbon nanofiber (CNF)-reinforced polypropylene (CNF/PP) composites with different CNF contents were prepared by melt mixing, and the mechanical properties and crystallization behavior of the CNF/PP composites obtained were investigated. It was found that the tensile modulus of the composites was increased with the addition of CNFs, but their elongation at break and fracture strain energy were decreased, while the tensile strength of the composites was firstly increased and then decreased due to the agglomeration of CNFs at higher loading. Nonisothermal crystallization analysis showed that the CNFs played a role as nucleating agent in PP matrix, which led to increment in the crystallization rate and the degree of crystallinity of PP. Moreover, X-ray diffraction studies showed that the CNFs incorporated in the PP matrix favored the growth of (040)-oriented PP crystals. With the increase in the CNF content, the nucleating and orientation roles of the CNFs were obviously enhanced.
关键词:
Carbon nanofibers
,
null
,
null
,
null
S.Kesteloot
,
C.Djelal
,
S.Baraka
,
I.Benslimane
材料科学技术（英文）
Man-entry sewers sustain many types of structural deterioration, and current repair techniques are very costly. Our objective was therefore to apply methods of localised strengthening by the adhesion of composite plates, as currently used in the construction and public works industry. To do so, it was necessary to run numerical simulations to determine the behaviour and mechanism of the ovoid sewer sections, to ascertain which areas required strengthening. A scale-1 experiment series was carried out to validate the process on reinforced-concrete multicracked ovoid sewers.
关键词:
Sewage systems
,
null
,
null
刘杰
,
郝巍
,
孟江燕
宇航材料工艺
综述了有关铝蜂窝芯、芳纶纸蜂窝芯及其复合材料在制造工艺上的研究成果；蜂窝夹层结构复合材料在隔音、隔热、耐老化、冲击性能等方面的最新研究进展,并对蜂窝夹层结构复合材料的研究方向提出了几点建议.
关键词:
铝蜂窝
,
芳纶纸蜂窝
,
复合材料
,
力学性能
新型炭材料
doi:10.1016/S1872-5805(09)60032-9
运用两种不同技法制备了ZrO2纳米粒子改性的膨化石墨/焦炭复合材料,应用XRD、SEM和TEM对所得ZrO2改性炭材料进行了表征.技法1:在ZrO(NO3)2及NH4OH溶液中反复交替地浸渍低密度膨化石墨/焦炭块体,随后在1200℃氮氛中热处理,以使在炭块自由表面沉积ZrO2纳米粒子的薄层.技法2:将可膨胀石墨、酚醛树脂粉和ZrOC2 O4-改性的纤维素纤维混合物封装于一容器中,使之经受900℃热激震,随后在氮氛中1200℃热处理,获得改性复合材料.结果表明:复合材料中ZrO2纳米粒子呈现三种尺寸:6nm～30nm为单独的纳米粒子和小微粒;200nm～1000nm为长树突状结构物;1μm～40μm为形如纤维素前驱体的杆状物.
关键词:
膨化石墨
,
焦炭
,
ZrO2
,
复合材料
