3D Printing of Aramid Nanofiber Composites by Stereolithography

Vat photopolymerization is a versatile 3D printing method that produces parts using polymeric materials with uniform mechanical properties, high quality surface finish and high-resolution features. However, it is challenging to make composite materials with vat photopolymerization mainly due to the imperfect filler dispersion in the photo resin. Herein, we describe a methodology to incorporate aramid nanofibers (ANFs) into a 3D printable photoresin as a dispersion, followed by a solvent exchange process that limits anisotropic shrinkage and cracking of the printed polymer. By incorporating 0.60 wt.% of ANFs, both the tensile strength and toughness increased by 264 % and 219 % respectively, while the Young’s modulus had a 406 % increase compared to the control photoresin.

Large-Scale and Deep-Seated Gravitational Slope Deformations on Mars: A Review

The availability of high-quality surface data acquired by recent Mars missions and the development of increasingly accurate methods for analysis have made it possible to identify, describe, and analyze many geological and geomorphological processes previously unknown or unstudied on Mars. Among these, the slow and large-scale slope deformational phenomena, generally known as Deep-Seated Gravitational Slope Deformations (DSGSDs), are of particular interest. Since the early 2000s, several studies were conducted in order to identify and analyze Martian large-scale gravitational processes. Similar to what happens on Earth, these phenomena apparently occur in diverse morpho-structural conditions on Mars. Nevertheless, the difficulty of directly studying geological, structural, and geomorphological characteristics of the planet makes the analysis of these phenomena particularly complex, leaving numerous questions to be answered. This paper reports a synthesis of all the known studies conducted on large-scale deformational processes on Mars to date, in order to provide a complete and exhaustive picture of the phenomena. After the synthesis of the literature studies, the specific characteristics of the phenomena are analyzed, and the remaining main open issued are described.

Influence of the technical condition of the 011-1-02N Remdetal installation on the quality of the coatings formed

The main modules of the 011-1-02N Remdetal installation for steel tape electrical resistance welding are described. The plant malfunctions arising during operation are identified. The analysis of the influence of these faults on the formation of a high-quality surface layer during the restoration of parts is performed. Recommendations on the maintenance operations of the modules under consideration are given.

Si surface passivation by using triode-type plasma-enhanced chemical vapor deposition with thermally energized film-precursors

We fabricated hydrogenated amorphous Si (a-Si:H) passivation layers on the surfaces of Si wafers by using triode-type plasma-enhanced chemical vapor deposition with gas-heating, and discussed high-quality surface passivation for Si heterojunction solar cells. The sample with the a-Si:H layers corresponding to the highest proportion of SiHx(x=2,3) content in SiHx(x=1–3) content exhibited the minimum surface recombination velocity (S) after annealing. This suggests that using SiHx(x=2,3)-rich a-Si:H grown at low-temperature as a passivation layer is advantageous to inhibit an epitaxial growth at the a-Si:H/crystalline Si interface, and that a structural relaxation of the a-Si:H takes place during post-deposition annealing, drastically improving passivation quality. Also, the importance to use a low Tsub and to optimize gas-heating and the triode technique, for obtaining simultaneously higher film quality and abrupt interface, is suggested. Low S obtained for our unoptimized samples implies the potency of this deposition technique. Nevertheless, further studies are needed to elucidate the impact of gas-heating and the triode technique on Si surface passivation. Temperature-dependent effective carrier lifetime for our samples might suggest relatively large electron affinity for an a-Si:H, which might be one possible reason for high-quality surface passivation.

Choice of electrolytic polishing mode for carbon steels

The electrolytic polishing modes of carbon steels on example steel 20 on the installation LectroPol-5 using electrolyte of chemical composition of 90 % C4H100 and 10 % HClO4 are studied. Electrolytic polishing provides high-quality surface for metallografi c analysis.

Developing the surface layer parameters of road-building and mining machines

The article is intended for specialists in the field of restoring the parts of road-building and mining equipment. Information is given on the use of shot blasting to form a high-quality surface for parts of road-building and mining equipment. The selection of shot blasting regimes for increasing the durability, reliability and safety of parts is justified. The given information allows expanding the possibilities of using shot blasting for road construction and mining equipment.