Narrow Results

The shell material of microcapsules has an important effect on the electrolytic co-deposition behavior, the release of core material and the surface performance of composite coating. This paper discussed the tensile property and the stability of three shell materials including polyvinyl alcohol (PVA), gelatin and methyl cellulose (MC). It is found that these three shell materials have good mechanical strength and flexibility which are favorable to electrolytic co-deposition and stability of microcapsules in composite coating and that MC has well permeability and porosity which has a positive effect on the release of the core material in composite coating. Moreover, the study of the thermal properties and water vapor permeability of the three shell materials showed that their permeability improved with increase of temperature and humidity. In addition, the composite copper coating containing microcapsules with PVA, gelatin or MC as shell material was prepared respectively.

Cellulose nanofibers have been showing much greater potential to enhance the mechanical and physical properties of polymer-based composite materials. The purpose of this study is to extract the cellulose nanofibers from waste bio-resources; such as waste newspaper and paper sludge. The cellulosic raw materials were treated chemically and physically in order to extract individualized cellulose nanofiber. The combination of acid hydrolysis and following mechanical treatment resulted in the extraction of cellulose nanofibers having diameter of about 40 nm. In order to examine the reinforcing effect of the extracted cellulose nanofibers, fully biodegradable green nanocomposites were fabricated by composing polyvinyl alcohol (PVA) resin with the extracted cellulose nanofibers, and then the tensile tests were conducted. The results showed that the enhancement in mechanical properties was successfully obtained in the cellulose nanofiber/PVA green nanocomposites.

In this work, we investigated the microstructure and tensile properties of Inconel 718 alloy processed by selective laser melting (SLM) and conventional casting technique using multiscale characterization methods. Results indicated that a columnar grain structure containing cellular structure units with submicron size was the major feature in the as-printed Inconel 718 alloy. At the cellular structure boundaries, the high-density dislocation tangles, segregation of Nb/Mo atoms and nano-sized Laves phases were found. Meanwhile, we also observed dislocation pile-ups and stacking faults in the interior of the cellular structure. In contrast, in the as-cast Inconel 718 alloy, both the grains and Laves phases were much coarser. Discrete dislocations, dislocation tangles and $\gamma$” precipitates were locally observed in the grains. Tensile results showed the as-printed Inconel 718 alloy had a higher strength and a lower elongation in comparison with those in the as-cast alloy. Based on the experimental results, the formation mechanism of the cellular structure was discussed.

Direct Laser Metal Deposition (DMD) processes can be utilized to generate functional parts providing an opportunity to generate complex shaped or functionally graded. In this paper, the relationship between energy density and microstructure of cobalt base alloy during DMD process has been discussed mainly. The microstructure, properties and preparation mechanisms of the specimens were studied using metallographic microscopy, scanning electron microscopy and X-ray diffraction. The result shows that relative density of the deposited builds is more than 99.40%. With the decrease of energy density, the relative density is reduced, the grain size and secondary dendritic space are also decrease. The average tensile strength and yield strength is 860.27 MPa and 572.4 MPa, respectively. The average elongation is 19.97%. The deposited specimens show obviously anisotropy at tensile property due to columnar grain microstructure throughout interlayer.

A 2 mm-thick 6061-T6 aluminum alloy sheet was friction stir welded in order to examine its friction stir welding (FSW) characteristics. The experimental results indicate that the mechanical properties of the FS-welded joints are lower than those of the base material, and the maximum ultimate-strength efficiency is only 50.7%. The FSW parameters significantly affect the tensile properties of the joints, and the suitable welding parameters for the 3 mm-thick 6061-T6 aluminum alloy sheet can be varied only in a relatively narrow range. Due to softening of joints and sheet thickness reduction, the nugget center becomes the weakest area of the joint.