DOI:10.30919/esmm5f616

Received: 30 Nov 2019
Accepted: 11 Dec 2019
Published online: 25 Dec 2019

Materials Properties and Manufacturing Processes

Liping Wang

School for Engineering of Matter, Transport and Energy, Arizona State University, Tempe, Arizona, USA

Email:liping.wang@asu.edu

 

Materials properties highly depend on the manufacturing processes. In this issue, nine recent studies reported on how to understand and improve the (i.e., optical, mechanical, thermal, piezoelectric, etc) with the manufacturing processes for different applications. Sun et al. (doi: 10.30919/esmm5f605) provided a comphrensive review on the recent progress in hot embossing of polymer materials for micro/nanoscale manufacturing, including plate-to-plate, roll-to-plate, and roll-to-roll forms. Research in simulation and mold fabrication for hot embossing were discussed, the various applications of polymer processing were highlighted with systematic catalogs, and challenges and future directions were outlooked. 

In the area of piezoelectrics, polyvinylidene fluoride (PVDF) attracts much attention for energy harvesting because of its superior elastic properties, high flexibility and low cost. In the work by Han et al. (doi: 10.30919/esmm5f612), they developed a novel approach to increase the b-phase concentration of electrospun PVDF nanofibers during the manufacturing process. With comprehensive materials characterizations with SEM, Energy Dispersive X-ray, and infrared spectroscopy, they found that high-quality PVDF fibers can be obtained by high molecular weight with electrospinning, and confirmed the improved polarization of PVDF fibers with zinc oxide nanoparticle dopants. Wu el al. (doi: 10.30919/esmm5f601) demonstrated the improved interlaminar shear strength by 28.4% and impact toughness by 53.3% of carbon fibers unsaturated polyester composites by a vinyl ester sizing agent containing vinyl-functional carbon nanotubes. After studying the surface characteristics and interfacial properties of the composites before and after treated with the sizing agent, the improved wettability, chemical bonding and mechanical interlocking were found to be associated with the enhanced interfacial adhesion by the sizing agent.

In the communication by Tian et al. (doi: 10.30919/esmm5f603), the microwave dielectric properties of Li6Mg7Zr3O16 ceramics prepared with the pure cubic phase using the traditional solid state method were studied, which are important for microwave communication applications. It was found that the sintering temperatures of 1500°C yielded the best properties of high quality factor Q·f value of 81,284 GHz (at 8.94 GHz), dielectric constant of 14.22, and a near-zero temperature coefficient of the resonant frequency (tf) of -21.56 ppm/°C. By doping with different LiF additives, the ceramics samples with 5 wt% LiF achieved a lower densification temperature of 1100°C, with improved above properties of 132,600 GHz (at 9.26 GHz), 13.67, and -18.89 ppm/°C.

Moving from microwave to optical frequencies, Taylor et al. (doi: 10.30919/esmm5f607) investigated the temperature-dependent optical properties of phase-change VO2 thin films on quartz substrate prepared by two-step furnace oxidation method within visible and near-infrared regime. In-situ temperature dependent spectroscopy was used to measure the dramatic change in transmission due to VO2 phase transition, and more importantly, in a wide temperature range from 77 K to 750 K that revealed the excellent thermal stability of both insulating and metallic phases at cryogenic and high temperatures. The findings are important for VO2 in many applications in particular for space thermal control and optical propulsion.

The thermal effect on the nanostructured materials is also critical for high-temperature solid-state applications like thermoelectric power generation. In the study by Hao et al. (doi: 10.30919/esmm5f608), the annealing effect at temperatures above 1073 K on the nanoporous silicon thin films prepared by electron beam lithography followed by deep reactive ion etching was studied. With various annealing conditions and careful inspections with SEM, they found that the pore size can greatly shrink for suspended thin films, while it can be kept intact with the mechanical protection of SiO2/Si substrate from the thermal strain.  

By loading phase change material as temperature management agent into the lightweight sand with surface pores sealed by water for internal curing, Liao et al. (doi: 10.30919/esmm5f606) demonstrated a multifunctional aggregate for mitigating the damage of concrete due to thermal cracking. A mortar prepared from this aggregate achieved comparable 28-day strength to the reference mortar with 63% lower autogenous shrinkage. The semi-adiabatic temperature rise was 7 °C lower, along with slowed peak temperature occurrence and smoother cooling curve. Cai et al. (doi: 10.30919/esmm5f611) employed a method of chemical reaction along with freeze-drying and high-temperature annealing and successfully synthesized the reduced graphene oxide/amino multi-walled carbon nanotubes aerogel. Materials characterizations verified the strong chemical bonding with enhanced hydrophobic properties. They demonstrated that the manufactured aerogel could separate oil and water within 25 s with good promise for oil spill treatment.

         In addition to materials characterizations and manufacturing processes, numerical methods are also important for optimizing many processes. Wang et al. (doi: 10.30919/esmm5f615) studied a new self-adaptive differential evolution algorithm based on machining learning to optimize the reduced mechanism of 2-Butanone and its superior performance was verified by the comparison of commonly used generic algorithm and particle swam algorithm.    

In summary, manufacturing processes play a vital role in achieving enhanced materials properties for energy harvesting, thermal control, optical communication, construction, oil spill treatment, while novel manufacturing processes and exotic materials properties along with new numerical methods are to be fully explored for many other areas of applications.

 

  

 

 

说明: Wang_Liping_0223b Dr. Liping Wang received his Ph.D. in mechanical engineering with a focus on nanoscale radiative heat transfer in 2011 at Georgia Institute of Technology under the guidance of Professor Zhuomin Zhang. He started his academic career as an assistant professor at Arizona State University in 2012 and was promoted to associate professor with tenure in 2018. Dr. Wang’s research aims to selectively control thermal radiation for energy applications by fundamentally understanding and exploring novel physical mechanisms in nanoscale radiative transport. Besides, he has been investigating near-field thermal radiation for energy harvesting and thermal management applications, in addition to the development of novel optical and thermal metrologies. His research findings have been published in more than 60 peer-reviewed high-impact journal papers in applied physics, optics, heat transfer, and materials. He is the recipient of 2017 AFOSR Young Investigator Award, 2016 JQSRT/Elsevier Viskanta Young Scientist Award, and 2015 NSF CAREER Award, in addition to 2013 Top 5% ASU Engineering Faculty Teaching Award.