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排序方式: 共有5650条查询结果,搜索用时 15 毫秒
91.
研究了20Cr11MoVNbNB钢550—650℃的蠕变性能及组织的变化,发现在550℃,蠕变应力>180MPa时,过渡蠕变应变和蠕变时间的ε_β-ι~(1/3)关系中,呈现前期斜率β_1大于后期β_2的两段线性关系;550℃稳态蠕变速率可用■=Aσ~nexp(-Q_c/RT)来表示,其中n=4.7,Aexp(-Q_c/RT)=5.37×10_(-16);550—650℃的表观蠕变激活能Q_c=430kJ/mol,其值远大于基体Fe原子的自扩散激活能;发现在蠕变过程中,随蠕变应力和蠕变时间增加,沉淀相的总量和其中的Cr,Mo,V含量增加,Fe和Nb含量则下降。 相似文献
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93.
Manish Roy 《Journal of Thermal Spray Technology》2002,11(3):393-399
The objective of the present work was to determine the dynamic hardness of WC-Co coatings from the dynamic hardness of the
coating substrate system. It was also the purpose of this work to evaluate the influence of coating composition, coating thickness,
and substrate materials on the dynamic hardness of the coating. To achieve the above-mentioned objectives, WC-12%Co and WC-17%Co
coatings were deposited by detonation spraying on three different substrate materials: mild steel, commercially pure (CP)
aluminum, and CP titanium. The dynamic hardness of the coating/substrate composite was evaluated by a drop weight system.
The dynamic hardness of the coating independent of the substrate was determined from the dynamic hardness of the coating/substrate
composite. 相似文献
94.
Thermally sprayed WC-Co is widely used as a wear-resistant coating for a variety of applications. Although it is well established
that thermal spray processes significantly affect chemistry, microstructure, and the phase distribution of WC-Co coatings,
little is known about how these changes influence wear resistance. In this study, the microstructure and wear behavior of
sintered and thermally sprayed WC-Co materials are examined. Powders of WC-12 wt% Co and WC-17 wt% Co were pressed and sintered,
as well as thermally sprayed by high-velocity oxy-fuel (HVOF), air plasma spray (APS), and vacuum plasma spray (VPS) techniques.
Results indicated considerable differences in the resulting microstructures, mechanical properties, and wear resistance. The
thermally sprayed coatings showed anisotropic fracture toughness, whereas the sintered materials did not. It was also shown
that a combined mechanical property/microstructure parameter, based on considerations of indentation fracture mechanisms,
can be used in most cases to describe abrasive and erosive wear resistance of thermally sprayed WC-Co materials as follows:
Wear resistance a
whereK
ic
is the indentation fracture toughness,H is hardness, andV
Co
f
is the volume fraction of cobalt. This relationship provides a means for assessing wear resistance of WC-Co coatings intended
for industrial applications requiring abrasion and/or erosion resistance. 相似文献
95.
Recent progress of CERN RD50 Collaboration 总被引:1,自引:0,他引:1
P. LUUKKA 《中国有色金属学会会刊》2006,16(B01):133-136
The objective of the CERN RD50 Collaboration is to develop radiation hard semiconductor detectors for very high luminosity colliders, in particular, for the upgrade of the large hadron collider (LHC) which itself is scheduled to be operational in 2007. The approach of the RD50 has two major research lines, material engineering and device engineering. These are further subdivided into projects covering defect characterization and engineering, new detector materials, detector characterization, new detector structures and full detector systems. Presently, 264 members from 53 institutes are actively participating in the RD50 Collaboration. Detectors made of defect engineered substrates, e.g. high resistivity magnetic Czochralski (MCz-Si), epitaxial silicon (Epi-Si) on Czochralski silicon (Cz-Si) substrate, intentionally thermal donor (TD) compensated p-type MCz-Si and oxygen enriched (DOFZ) silicon, have been demonstrated by the RD50 Collaboration. An overview and highlights of the results of these defect engineering techniques were given in this report. 相似文献
96.
97.
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100.
堆焊焊条设计试验采用L9(34)式正交表设计,以石墨、碳化硼和铁粉3个因素为变量,通过工艺性能定性分析,硬度值正交回归,最优化计算,得到优化试验配方和建立堆焊层金属硬度的回归方程,从而找到药皮主要成分石墨、碳化硼、铁粉对堆焊金属硬度、耐磨性等性能的影响规律.其中,碳化硼影响最大,铁粉次之,最小是石墨.随着碳化硼、铁粉、石墨增加硬度与耐磨性提高.铁粉量增加焊缝成型好,飞溅小.而石墨增加焊缝成型不好.碳化硼增加,飞溅加大.得到的最佳堆焊焊条配方,其焊接工艺性能优良,硬度值达68~71 HRC. 相似文献