Recently Published Documents
The effects of lithium slag on microstructure and mechanical performance of metakaolin-based geopolymers designed by response surface method (RSM)
As a major component of lignocellulosic biomass, lignin is one of the largest natural resources of biopolymers and, thus, an abundant and renewable raw material for products, such as high-performance fibers for industrial applications. Direct conversion of lignin has long been investigated, but the fiber spinning process for lignin is difficult and the obtained fibers exhibit unsatisfactory mechanical performance mainly due to the amorphous chemical structure, low molecular weight of lignin, and broad molecular weight distribution. Therefore, different textile spinning techniques, modifications of lignin, and incorporation of lignin into polymers have been and are being developed to increase lignin’s spinnability and compatibility with existing materials to yield fibers with better mechanical performance. This review presents the latest advances in the textile fabrication techniques, modified lignin-based high-performance fibers, and their potential in the enhancement of the mechanical performance.
Mechanical performance of a novel environmentally friendly basalt‐elium ® thermoplastic composite and its stainless steel‐based fiber metal laminate
Development of self-compacting concrete using Bailey aggregate grading technique in comparison with Indian standard code of practice
Purpose This study aims to present the results of an experimental evaluation of low (M30), mid (M40) and high (M50) grade self-compacting concrete (SCC) with three nominal maximum aggregate sizes (NMAS), namely, 20 mm, 16 mm and 12.5 mm, with Bailey gradation (BG) in comparison with Indian standard gradation (ISG). Design/methodology/approach This study was conducted in a laboratory by testing the characteristics of fresh and hardened properties of self-compacting concrete. Findings Rheological and mechanical properties of SCC were evaluated in detail and according to the results, a concrete sample containing lower NMAS with BG demonstrated improvement in modulus of elasticity and compressive strength, while improving the rheological properties as well. Meanwhile, SCC demonstrated poor performance in split tensile and flexural strengths with lower NMAS gradations and a direct correlation was evident as the increase in NMAS caused an increase in the strength and vice-versa. Originality/value Upon comparison of BG with ISG, it was revealed that BG mixes succeeded to demonstrate superior performance. From the material optimization, rheological and mechanical performance study, it is recommended that BG with NMAS 16 mm can be used for conventional SCC.
Raw powders are processed in water during the freeze-dry pulsated orifice ejection method (FD-POEM), leading to the inclusion of oxygen impurities. This study proposes a strategy for removing the oxygen content and enhancing the mechanical performance of laser powder bed fusion (L-PBF) builds from powders using carbon nanotubes (CNTs) and H2 reduction. Spherical 1.5 wt.% CNT/Mo composite powders with uniform dispersion were fabricated via FD-POEM. The quantity of MoO2 decreased significantly, and a hexagonally structured Mo2C phase was simultaneously formed in the L-PBF build. The Mo2C with network structure was distributed along the boundaries of equiaxed Mo grains, leading to an increased Vickers hardness of the matrix. This study demonstrates the feasibility of fabricating oxygen-free and high-strength refractory parts during L-PBF for ultrahigh-temperature applications.
Effect of Specimen Orientation on the Mechanical Performance of Diffusion Bonded 316 Stainless Steel for Hybrid Printed Circuit Heat Exchangers
The growing demand for increased chip performance and stable reliability calls for the development of novel off-chip interconnection and bonding methods that can process good electrical, thermal, and mechanical performance simultaneously as well as superior reliability. A chip bonding method with the concept of “nano-locking” (NL) is proposed: the two surfaces are locked together for electrical interconnection, and the connection is stabilized by a dielectric adhesive filled into nanoscale valleys on the interconnecting surfaces. The general applicability of this new method was investigated by applying the method to the die-substrate bonding of two different packages from two different manufacturers. Electrical, optical, and thermal performances as well as reliability tests were carried out. The surface morphology of the bonding package substrates plays an important role in determining the contact resistance at the bonding interfaces. It was shown that samples with different roughness height distribution on the metallic surfaces formed a different total number of contacts and the contact area between the two bonding surfaces under the same bond-line thickness (BLT): a larger number of contact area resulted in a reduced electrical resistance, and thus an improved overall device performance and reliability.
Coconut Fibre and Sawdust as Green Building Materials: A Laboratory Assessment on Physical and Mechanical Properties of Particleboards
This paper evaluates, via a laboratory assessment, the physical properties (BS EN 323:1993, BS EN 324) and mechanical performance (BS EN 310: 1993) of hybrid particleboards using agricultural wastes, namely coconut fibre and sawdust. The process begins with the preparation of the materials where they are sieved and retained with the 5-mm sieve and then oven-dried. The hybrid particleboard mixed with the addition of resin (urea formaldehyde) was sprayed and hot pressed. The hot press temperature was set at 180 °C, with the resin content of 8 wt.% and the design density of 650 kg/m3 used in producing the particleboard. The percentage/ratio of the composition of sawdust (SD) to coconut fibre (CF) varied ranging from 100SD:0CF to 70SD:30CF, 50SD:50CF, 30SD:70CF, and 0SD:100CF. Meanwhile, as for the thickness of the boards, it was categorised into three groups which are 16 mm, 20 mm, and 32 mm. The particleboards were conditioned to the room temperature for seven days before being tested for physical properties and mechanical performances. The results show that the most optimum composition of sawdust to coconut fibre is 0% sawdust to 100% coconut fibre (0SD: 100CF) and the optimum thickness is 20 mm, where its density is 761.99 kg/m3, swelling thickness is 11.98%, and water absorption at 37.64%. With the modulus of elasticity of 1510 N/mm2, the modulus of rupture of 17.8 N/mm2, and the internal bonding of 1.08 N/mm2, they satisfied the universal standard of Particleboard Type P3 of BS EN 312:2010.