Cobalt-based alloys are widely used as hardfacing materials when wear resistance is required at room temperature or high temperature applications. However, their performance is a consequence of their microstructures t...
详细信息
Cobalt-based alloys are widely used as hardfacing materials when wear resistance is required at room temperature or high temperature applications. However, their performance is a consequence of their microstructures that depends on the processing conditions. This work focused on the influence of solidification rate on the structure development by processing the alloys with and without the interference of the substrate. The coatings were characterized by scanning electron microscopy, energy dispersive spectrometer, optical microscopy and instrument indentation tests. Results showed that despite the same phases developed in tested conditions, differences in the solidification microstructure and the influence of Fe diffusing from the substrate accounted for the measured variation in hardness. Higher hardness values were obtained for the samples processed free-standing (mini billets) with respect to the coatings and they were independent of the processing parameters, indicating that the substrate compromise the properties of hardness, as expected.
Silicon nanodevice biosensors have been attracted a lot of attention due to its advantages of label-free, real-time and very high sensitive detection. This study employs self-assembly monolayer (SAM) of methoxy-poly(e...
详细信息
ISBN:
(纸本)9781457717666
Silicon nanodevice biosensors have been attracted a lot of attention due to its advantages of label-free, real-time and very high sensitive detection. This study employs self-assembly monolayer (SAM) of methoxy-poly(ethyleneglycol) silane (MPEG-sil) as passivation on Si nanodevices. Ablation of SAM by Joule heating (JH) was performed at n - region of a nanobelt device, where the linker molecules, biotin were modified subsequently. Detection of Alexa dye-labeled Streptavidin (SA) showed that the fluorescence intensity at n - region increased with each 50-μl SA injection and saturated after the 4 th injection. A difference of fluorescence intensity between SAM-ablated device and without passivation is 4.9 fold. Threshold voltage (V th ) shifted ca. 35 mV after the 4 th injection for SAM-ablated device and as-fabricated device exhibited only a 10-mV V th shift. The results indicated that SAM-ablated device possess potential in reduction of sensing time and in increase of sensitivity for low concentration detection.
Fabrication of graphene was demonstrated by electrochemical exfoliation of graphite in an ammonium hydroxide solution. The processing parameter of applied voltage was optimized to accomplish graphene productivity and ...
Fabrication of graphene was demonstrated by electrochemical exfoliation of graphite in an ammonium hydroxide solution. The processing parameter of applied voltage was optimized to accomplish graphene productivity and desired chemical composition. Images from the atomic force microscopy showed graphene sheets with lateral sizes of several hundred nanometers. Images from the transmission electron microscopy indicated the existence of stacked graphene sheets with thickness of a few graphene layers. Raman spectroscopy confirmed variation of as-synthesized graphene and bulk graphite. X-ray photoemission spectroscopy suggested the formation of graphene oxide at large voltage.
In this work ceramic foams of 3 and 8 mol% yttria-stabilized zirconia (3YSZ and 8YSZ) were manufactured by the replication method using polystyrene-polyurethane foams with pore sizes in the 7–10 ppi range. A second c...
In this work ceramic foams of 3 and 8 mol% yttria-stabilized zirconia (3YSZ and 8YSZ) were manufactured by the replication method using polystyrene-polyurethane foams with pore sizes in the 7–10 ppi range. A second coating was carried out on presintered foams in order to thicken struts and hinder microstructural defects. The produced ceramic foams were structurally and thermomechanically characterized. Samples recoated with 3YSZ presented the highest relative densities (0.2 ± 0.1) which contributed to a better mechanical and thermal behavior.
暂无评论