L.Li 1)
,
Z. P.Wang. 2)
,
Z.K.Qu 1)
,
D.M.Jia 3) and Z.Jiang 4) 1) Mechanical Engineering College
,
Shenyang University
,
Shengyang 110044
,
China 2) Harbin Research Institute of Welding
,
Harbin 150080
,
China 3) Information Engineering Collage
,
Shenyang University
,
Shengyang 110044
,
China 4) Materials Engineering College
,
University of Science and Technology Beijing
,
Beijing 100083
,
China
金属学报(英文版)
A novel test method of measuring the interface bond strength between a thermal sprayed coating and substrate is put forward first in this paper. The test method is simple and reliable, and exists no any inherent shortcoming and controversy. The interface bond strength obtained by the test method is completely the inherent property of the interface and depends only on coating material properties, spray conditions, and technique of depositing the coating. By extensive tests, it is shown that the test tesults are very tepeatable and reliable. Furthermore, from this test, the critical coating thickness under which the coating spall can not emerge is also obtained.
关键词:
coating
,
null
,
null
,
null
Metallurgical and Materials Transactions a-Physical Metallurgy and Materials Science
The influence of solution temperature on the microstructure and mechanical properties of TMW-4M3 superalloy has been investigated. Comparisons of mechanical properties have also been made between the heat-treated TMW-4M3 variants and the commercial U720Li. The key microstructural variables examined were grain size and the volume fraction and size of the strengthening gamma' precipitates that control the mechanical properties of these alloys. By increasing the solution temperature from 1373 K to 1393 K (1100 A degrees C to 1120 A degrees C), the volume fraction of primary gamma prime dropped from 16.9 pct to 14.5 pct, whereas the average grain size increased from 8.7 mu m to 10.6 mu m. Compared with an alloy with a smaller grain size, the alloy with a larger grain size exhibited superior resistances to creep and fatigue crack growth without the expense of reduced tensile strength and low-cycle fatigue resistance. This suggested that a higher solution temperature may benefit TMW-4M3 in terms of superior overall properties. The greater overall properties of TMW-4M3 variants than that of commercial U720Li were also demonstrated experimentally. The possible explanations for the improvement of mechanical properties were discussed.
关键词:
ni-base superalloy;low-cycle fatigue;heat-treatment;cooling;precipitation;stainless-steel;yield strength;udimet 720li;creep;behavior;alloy
Pan Ting
,
Song Wenjing
,
Cao Xiaodong
,
Wang Yingjun
材料科学技术（英文）
doi:10.1016/j.jmst.2016.01.007
Gelatin/Alginate hydrogels were engineered for bioplotting in tissue engineering. One major drawback of hydrogel scaffolds is the lack of adequate mechanical properties. In this study, using a bioplotter, we constructed the scaffolds with different pore architectures by deposition of gelatin/alginate hydrogels layer-by-layer. The scaffolds with different crosslinking degree were obtained by post-crosslinking methods. Their physicochemical properties, as well as cell viability, were assessed. Different crosslinking methods had little influence on scaffold architecture, porosity, pore size and distribution. By contrast, the water absorption ability, degradation rate and mechanical properties of the scaffolds were dramatically affected by treatment with various concentrations of crosslinking agent (glutaraldehyde). The crosslinking process using glutaraldehyde markedly improved the stability and mechanical strength of the hydrogel scaffolds. Besides the post-processing methods, the pore architecture can also evidently affect the mechanical properties of the scaffolds. The crosslinked gelatin/alginate scaffolds showed a good potential to encapsulate cells or drugs.
关键词:
Bioplotting
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Tissue engineering
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Scaffolds
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Gelatin
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Alginate
陈耿
,
谢建良
,
黄鹏
功能材料
采用陶瓷工艺制备C02Z(Ba3(Co0.4Zn0.6)2Fe23.4O41)和BaM(BaFi1.4Co1.4Fe9.2O19)六角铁氧体,二次球磨时掺杂少量BST(BaSrTiO3)铁电材料,对比研究了BST掺杂对Z型和M型铁氧体在1MHz～1GHz频率范围内相对复磁导率(μr=μr1-iμr")的影响.BST的掺杂使Z型铁氧体μr增大,共振频率点移向低频;使M型铁氧体的μr减小,共振频率点移向高频.通过对其微观结构和磁参数的测试分析,讨论了BST掺杂对Z型和M型铁氧体复磁导率不同影响的作用机理.
关键词:
Z型六角铁氧体
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M型六角铁氧体
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磁晶各向异性场
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相对复磁导率
材料科学技术（英文）
The cyclic plastic straining electrode technique has been used to investigate the transient electrochemical behaviour of Fe-26Cr-1Mo stainless steel in 1M H2SO4 solution at a passive potential. The influence of plastic strain amplitude and plastic strain rate on the dissolution current response was analysed. The experimental results showed that the transient current was dependent on the competitive process of the surface film rupture and repassivation of the new surface. The high plastic strain amplitude and the high plastic strain rate caused a change of electrochemical activity of specimen surface. In the condition of low strain amplitude and strain rate:, the characteristics of current response was mainly relative to the process of new surface repassivation. The competition kinetics has been analysed through the comparison of plastic strain rate and repassivating rate.
关键词:
Journal of Alloys and Compounds
The influence of magnetic fields on the mechanical loss (Q(-1)) of Terfenol-D/PbZr(0.52)Ti(0.48)O(3)/Terfenol-D three-layer laminated composites is investigated systemically using the technique for measuring the resonance magnetoelectric (ME) effect. The results indicate that Q(-1) varies non-monotonically with dc magnetic fields and shows a maximum near 500 Oe for all the samples with different layer thickness ratios (n) of Terfenol-D (Tb(0.3)Dy(0.7)Fe(1.92)). Considering various kinds of mechanical energy dissipation, it is found that Q(-1) is mainly dominated by the mechanical damping due to the domain wall motion in Terfenol-D under the actions of dc and ac magnetic fields as well as the stress at the interface. In addition, the effect of eddy current losses on the energy dissipation of the system is also discussed. (C) 2011 Elsevier B.V. All rights reserved.
关键词:
Magnetoelectric composite;Mechanical energy dissipation;Domain wall;motion;magnetomechanical damping capacity;terfenol-d;magnetostriction;alloys;tb0.27dy0.73fe2;tb0.3dy0.7fe1.95
Journal of Materials Research
Bonding character, elastic mechanical parameters, ideal strengths, and atomistic shear deformation mechanisms of M(3)AlN (M = Zr and Hf) were studied by first-principles method. M(3)AlN exhibits layered chemical bonding character due to the alternately stacking of relatively soft AI-M and strong N-M covalent bonds. The second-order elastic constants and mechanical parameters of M(3)AlN were reported for the first time. The stress-strain relationships for different deformation modes were studied and the ideal shear and tensile strength were obtained. M(3)AlN ceramics are predicted to be "quasi-ductile" layered nitrides based on the low shear-modulus-to-bulk-modulus ratios, positive Cauchy pressure (c(12)-c(44)), and lower ideal shear strength compared to ideal tensile strength. Investigation of the atomistic shear deformation mechanism of M(3)AlN shows that stretching of soft Al-Hf bonds and relatively weak bridge N-Hf1 bonds dominate the shear deformation; while the rigid N-Hf2 bonds resist against the applied shear strain. Chemical bonding characteristics and shear deformation mechanism of M(3)AlN are similar with those of other "quasi-ductile" ceramics, such as MAX phases, LaPO(4) monazite, and gamma-Y(2)Si(2)O(7). The results further suggest that M(3)AlN nitrides should be quasi-ductile and damage tolerant.
关键词:
electronic-structure;ternary carbides;ceramics;optimization;zr2al3c4;systems;solids;ti2alc
韩立军
,
李铁虎
,
刘建军
,
邱海鹏
,
丁海英
新型炭材料
doi:10.3969/j.issn.1007-8827.2004.02.004
采用炭纤维平纹织物和精细Z-pin制备了新型3D炭纤维预制件,炭基体采用等温化学气相沉积和高温煤沥青高压浸渍炭化制备.短梁剪切试验和开口拉剪试验用来表征Z-pin增强体对剪切破坏模式的影响.短梁剪切失效模式为假塑性,而拉剪失效模式为非假塑性破坏.分析了产生此现象的机制,短梁剪切假塑性失效由炭/炭复合材料叠层中纤维束内、纤维束间和叠层间微裂纹扩展形成,而产生拉剪失效的单一层间裂纹扩展不引起宏观假塑性现象.采用Z-pin作为提高层间剪切强度的增强体间隔1.5 mm比间隔2.5 mm可提高剪切强度40 %～50 %,该技术将成为3D炭/炭复合材料预制体制备更为先进的技术.
关键词:
层间破坏
,
3D C/C复合材料
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Z-pin
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假塑性
