The Electrical and Thermal Transport Properties of La-Doped SrTiO3 with Sc2O3 Composite

Donor-doped strontium titanate (SrTiO3) is one of the most promising n-type oxide thermoelectric materials. Routine doping of La at Sr site can change the charge scattering mechanism, and meanwhile can significantly increase the power factor in the temperature range of 423–773 K. In addition, the introduction of Sc partially substitutes Sr, thus further increasing the electron concentration and optimizing the electrical transport properties. Moreover, the excess Sc in the form of Sc2O3 composite suppresses multifrequency phonon transport, leading to low thermal conductivity of κ = 3.78 W·m−1·K−1 at 773 K for sample Sr0.88La0.06Sc0.06TiO3 with the highest doping content. Thus, the thermoelectric performance of SrTiO3 can be significantly enhanced by synergistic optimization of electrical transport and thermal transport properties via cation doping and composite engineering.

Preparation of 3D printed silver nanocomposites and their antibacterial properties

The 3D printed antibacterial polymer products were rapidly sintered to obtain by selective laser sintering with highly dispersed Nano-silver modified Kaolin powder and polyamide/polypropylene composite engineering material. The preparation method of polymer products not only shortens the preparation period, but also guarantees the precision and quality of the product as well as the slow-release function of the Nano-silver.

Innovation and Practice of Composite Engineering Teaching for New Engineering

At present, the material engineering industry is developing rapidly. As one of the most widely used materials in the market, composites are more and more widely used in the field of present production and construction applications. In the new engineering era, it is necessary to cultivate more innovative talents who can adapt to the composite engineering market, so as to promote the better development of composite engineering. Taking composite engineering teaching as an example, this paper introduces the necessity of innovation and reform of composite engineering teaching in the new engineering era, and analyzes the effective innovation and practical countermeasures of composite engineering teaching.

The Mechanical and Material Designs of Composite Ju|’hoansi Arrowheads

In this paper, we elucidate the composite engineering design skills of the Kalahari Ju|’hoansi (San) people, developed over at least tens of thousands of years. In particular, we show that the mechanical and physical properties of materials used by the Ju|’hoansi in the design of arrowheads are intimately linked to their unique geometrical and composite designs. The Ju|’hoansi arrowheads have evolved to become complex engineered units with distinct function-specific purpose. We demonstrate herein that the geometrical designs of the arrowheads are optimised with respect to the material used. We furthermore verify the veracity of the Ju|’hoansi claim that their composite link-shafts are designed to break off leaving the arrowhead in the animal and the remaining parts of the arrow intact, reusable and easily retrievable.

Tribological Behavior of a Polyester Composite System under Severe Wear Conditions

This work aims on the study of the wear resistance of a commercial polyester composite system under severe wear conditions. It is an example of composite engineering material manufactured from synthetic fibers and thermosetting resins with appealing physical and mechanical properties that make it very interesting for products like sheets, rods, tubes, flange, washers and wear ring. In order to make it suitable for applications where damage by metal roll surfaces can occur, the study of the wear behavior under specific conditions is then necessary. At this aim, a detailed experimental campaign, including tribological tests and microgeometrical measurements, was carried out. In particular, the tribological behaviour was studied through the pin-on-disk tests conducted at 209 mm/s as peripheral speed under an applied load comprising in the range of 10 - 70 N. The tests were followed by microgeometrical measurements by using a confocal microscope in order to critically observe the wear tracks, evaluate their depth, width and then to calculate the final less of volume. The results proved that the wear mechanisms founded for the composite under investigation differ from those commonly associated to metals; the surface asperities of the fibres allow to hold the lubricant inside the surface and thus assist in the maintenance of a continuous film on the working surface involving in very low friction coefficient.